Remediation of Copper Contaminated Sediment Site

Remediation of Copper Contaminated Sediment Site: TREATABILITY STUDY AND CAP EFFECTIVENESS MODELING July , 2012 Sandip Chattopadhyay Prepared under:

U.S. Army Corps of Engineers, Sacramento District Contract Number W91238-06-D-0018

TABLE OF CONTENTS ACRONYMS AND ABBREVIATIONS ........................................................................................v EXECUTIVE SUMMARY .......................................................................................................ES-1 1.0

INTRODUCTION ...............................................................................................................1 1.1 PURPOSE AND SCOPE ................................................................................................1 1.2 DESCRIPTION OF IN SITU CAPPING ............................................................................1 1.3 REPORT ORGANIZATION ...........................................................................................2

2.0

BACKGROUND .................................................................................................................2 2.1 PROJECT LOCATION AND LAND USE .........................................................................2 2.2 PHYSICAL SETTING ...................................................................................................2 2.2.1 Geology and Sediments ...............................................................................3 2.2.2 Hydrogeology ..............................................................................................3 2.2.3 Ecology ........................................................................................................5 2.3 HISTORY OF CONTAMINATION ..................................................................................5 2.4 CONCEPTUAL SITE MODEL .......................................................................................6 2.5 NATURE AND EXTENT OF CONTAMINATION ..............................................................8 2.5.1 Arsenic .........................................................................................................8 2.5.2 Cadmium ......................................................................................................9 2.5.3 Copper ........................................................................................................10 2.5.4 Lead............................................................................................................10 2.5.5 Mercury ......................................................................................................11 2.5.6 Selenium ....................................................................................................12 2.5.7 Zinc ............................................................................................................12 2.6 REMEDIATION GOALS .............................................................................................13

3.0

REMEDIAL DESIGN .......................................................................................................14 3.1 DESIGN REQUIREMENTS AND OBJECTIVES ..............................................................14 3.1.1 Remedy of Record .....................................................................................14 3.1.2 Design Process Overview ..........................................................................15 3.1.3 Cap Design and Performance Criteria .......................................................16 3.2 CAPPING MATERIALS TREATABILITY STUDY EVALUATION SUMMARY ..................16 3.2.1 Testing of Materials ...................................................................................17 3.2.2 Test Results ................................................................................................18 3.2.3 Evaluation Results - Chemical Flux Modeling ..........................................20 3.2.4 Selection of Cap Material ..........................................................................21 3.3 CAP STABILITY EVALUATION .................................................................................22 3.4 BIOTURBATION EVALUATION .................................................................................23 3.5 CAP DESIGN ............................................................................................................23

Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

i

TABLE OF CONTENTS (Continued) 4.0

CAP MATERIAL PLACEMENT AND OPERATIONS PLAN ......................................24 4.1 GENERAL CONSIDERATIONS ...................................................................................24 4.2 LAYDOWN AREA, ACCESS, AND CONSTRUCTION EQUIPMENT USAGE ....................25 4.3 PLACEMENT AND CONSTRUCTION METHODS ..........................................................25 4.3.1 Processing of Bay Mud Material ...............................................................26 4.3.2 Placement of Cap Material.........................................................................26 4.3.3 Survey Plates ..............................................................................................26 4.3.4 Field Control ..............................................................................................27 4.4 MINIMIZING ECOLOGICAL IMPACTS ........................................................................27 4.5 CAP PLACEMENT CONSTRUCTION SEQUENCE .........................................................28

5.0

POST-CONSTRUCTION CAP MONITORING AND MAINTENANCE ......................28 5.1 MONITORING REQUIREMENTS.................................................................................28 5.1.1 Physical Monitoring ...................................................................................28 5.1.2 Analytical Monitoring................................................................................29 5.2 MAINTENANCE........................................................................................................29

6.0

REFERENCES ..................................................................................................................30


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LIST OF FIGURES 1

MOTCO Location

2

Site 32 and Site 33 Locations

3

Remediation Footprint for Site 32 and 33

4

Arsenic Concentrations in Sediments Sites 32 and 33

5

Cadmium Concentrations in Sediments Sites 32 and 33

6

Copper Concentrations in Sediments Sites 32 and 33

7

Lead Concentrations in Sediments Sites 32 and 33

8

Mercury Concentrations in Sediments Sites 32 and 33

9

Selenium Concentrations in Sediments Sites 32 and 33

10

Zinc Concentrations in Sediments Sites 32 and 33

11

Construction Sequence

LIST OF TABLES 1

Maximum Concentrations of Arsenic in Sediment (mg/kg) ................................................9

2

Maximum Concentrations of Cadmium in Sediment (mg/kg) ............................................9

3

Maximum Concentrations of Copper in Sediment (mg/kg) ..............................................10

4

Maximum Concentrations of Lead in Sediment (mg/kg) ..................................................11

5

Maximum Concentrations of Mercury in Sediment (mg/kg) ............................................11

6

Maximum Concentrations of Selenium in Sediment (mg/kg) ...........................................12

7

Maximum Concentrations of Zinc in Sediment (mg/kg) ...................................................13

8

Final Remediation Goals....................................................................................................14


iii

APPENDICES A

Treatability Study and Cap Effectiveness Modeling

B

Cap Stability Evaluation for Site 32 and 33 In Situ Cap

C

Bioturbation Evaluation

D

Design Drawings

E

Field Investigation Measurements

F

Response to Comments on 30 Percent Submittal, Remedial Design Report for In Situ Cap at Sites 32 and 33 Litigation Area


iv

ACRONYMS AND ABBREVIATIONS µg/L µS/cm2

Micrograms per liter MicroSiemens per square centimeter

ARAR Army AWQC

Applicable or relevant and appropriate requirements U.S. Department of the Army Ambient water quality criteria

bgs bss

Below ground surface Below sediment surface

CERCLA CFR CNPS COEC CPC

Comprehensive Environmental Response, Compensation, and Liability Act Code of Federal Regulations California Native Plant Society Chemical of ecological concern Chemical and Pigment Company

DI DTSC

Deionized water California Environmental Protection Agency Department of Toxic Substances Control

EPA

U.S. Environmental Protection Agency

FS

Feasibility Study

GCC

General Chemical Corporation

Kd

Partitioning coefficient

mg/kg MOTCO msl

Milligrams per kilogram Military Ocean Terminal Concord Mean sea level

NCP NTU

National Oil and Hazardous Substances Pollution Contingency Plan Nephelometric turbidity unit

PRG

Preliminary remediation goal

RASS RD RG ROD

Remedial Action Subsite Remedial Design Remedial goal Record of Decision

SARA SVOC

Superfund Amendments and Reauthorization Act of 1986 Semivolatile organic compound


v

ACRONYMS AND ABBREVIATIONS (Continued) TDS

Total dissolved solids

U.S.C.

United States Code

VOC

Volatile organic compound

Water Board WET

San Francisco Bay Regional Water Quality Control Board Waste extraction test


vi

EXECUTIVE SUMMARY This remedial design (RD) report addresses Litigation Area Sites 32 and 33 at Military Ocean Terminal Concord (MOTCO) in Concord, California. The location of MOTCO and Sites 32 and 33 is illustrated on Figures 1 and 2. This document was developed to describe the remedial action to provide an in situ cap for the contaminated sediments in the mosquito ditches of Site 32 and also in the southern portion of Lost Slough, which makes up Site 33. Sites 32 and 33 are located within the Litigation Area, which is composed of upland and wetland habitats and is not currently developed. After this RD is implemented in the field, the success of this remedy will be the subject of ongoing long-term monitoring, including annual monitoring and Five-Year Review reports per the requirements of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). The purpose of this RD is to set forth the remediation plan in sufficient detail to describe the design objectives and evaluations, the components of the design and the implementation by construction, and the subsequent field monitoring. Site Descriptions: Sites 32 and 33 are part of remedial action subsite (RASS) 1, which covers 210 acres adjacent to Suisun Bay and includes tidally-influenced brackish wetland, with minimal upland and associated transitional zone habitat. Neither the Army nor the Navy conducted any operations on RASS 1 that contributed contamination; these properties were used only as buffer zones for munitions loading at the installation. Major sources of contamination to RASS 1 were historical spills from: (1) the adjacent General Chemical/Honeywell facility to the east, (2) the General Chemical/Honeywell property adjacent to the southeastern corner of the RASS 1 wetland (Corner Lot), and (3) the former Chemical and Pigment Company facility upstream on Nichols Creek. Chemicals posing risk at levels that drive remedial action at the sites are: •

Site 32: Arsenic at a single sample location, zinc at a single sample location, and copper throughout most of the area

•

Site 33: Cadmium at a single sample location, zinc at a single sample location, and copper over most of the areas

Remedial Design Considerations: The design process for Sites 32 and 33 includes evaluation and selection of the cap materials, thickness and placement methodology and erosion control improvements, if required. The design includes a treatability study, a cap stability evaluation, and a bioturbation evaluation. The treatability study is summarized in Section 3.2, and the full study report is included as Appendix A. The cap stability evaluation is summarized in Section 3.3, and the complete report is included as Appendix B. The bioturbidity evaluation is summarized in Section 3.4, and the complete evaluation is included as Appendix C. The in situ caps for Site 32 and 33 will consist of a soil cap of Bay Mud dredge spoils obtained from Martinez Marina spread uniformly on the exposed sediment surfaces of Sites 32 and 33. The exposed sediment surfaces to be covered are normally inundated with surface water that either flows into or out of the system of mosquito ditches and naturals sloughs that make up Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

ES-1

Site 32 and Site 33. The selection of the cap material is based on the following considerations: sorption capacity, cap stability against erosion, material availability, cost effectiveness, and ecological impact. Cap Thickness: Considering the treatability study, cap effectiveness modeling, stability evaluation, and bioturbation, the cap thickness design for Site 32 is 8 inches of Martinez Marina Bay Mud. The chemical flux model indicates a cap of 8 inches thick will result in a pore water concentration that does not exceed the Target Area Weighted Average Concentration Remediation Goal within 30 years. The 8-inch-thick cap design will provide adequate physical isolation since the benthic community is not expected to extend into contaminated sediments. The cap thickness design for Site 33 east and west tributaries is 8 inches of Martinez Marina Bay Mud based on the chemical flux model. The chemical flux model indicates that a cap thickness of 8 inches will result in a pore water concentration that does not exceed the Target Area Weighted Average Concentration Remediation Goal within 30 years. The 8-inch cap will also provide adequate physical isolation since the benthic community is not expected to extend into contaminated sediments. In addition, the cap design for the main channel of the slough will include an additional 4 inches of Bay Mud, for a total cap thickness of 12 inches to account for erosion that may occur only in the main channel of the slough. Cap Construction: Cap material placement considerations are influenced by the site-specific conditions and limitations imposed by the presence of sensitive wildlife habitat. Equipment and placement methodologies have been selected to minimize impacts to the site. Specific avoidance measures are included in the plan for the protection of threatened and endangered species. Construction monitoring is required to assess the placement techniques and provide quality control to assure that the placement methods meet design objectives. No heavy equipment will be used to place or spread the cap materials because construction equipment such as excavators, loaders, and trucks would disturb the marsh plain at Sites 32 and 33. The entire cap within Site 32 and 33 will be constructed by hand placement of woven polypropylene bags filled with Bay Mud. A helicopter will be used to transport bags from the project staging area to the sides of the ditches or sloughs. Subsequently, each bag will be manually placed on the contaminated sediment surface until the entire area requiring a surface cap is covered with a uniform layer of bagged Bay Mud to the design thickness. In the slough, the bags will be placed on a geotextile liner, which will provide a stable surface for workers as well as the cap. Survey plates will be installed to monitor cap thickness immediately after construction and during the long-term monitoring. Monitoring: Cap monitoring will include both physical and chemical parameters. Physical monitoring will include measuring the thickness of the cap to verify that an adequate layer remains in place to isolate the underlying contaminated sediments. Chemical monitoring will include laboratory analysis cap materials for metals to verify that concentrations remain below remedial goals.


ES-2

1.0

INTRODUCTION

This remedial design (RD) report addresses Litigation Area Sites 32 and 33 at Military Ocean Terminal Concord (MOTCO) in Concord, California. The location of MOTCO and Sites 32 and 33 is illustrated on Figures 1 and 2. This document was developed to describe the remedial action to provide an in situ cap for the contaminated sediments that are located in the mosquito ditches of Site 32 and also in the southern portion of Lost Slough, which makes up Site 33. The location of Sites 32 and 33 at MOTCO are also indicated on the project plans that are the drawings associated with this RD report. This RD was developed as an amended remedy for Sites 32 and 33 in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA) (Title 42 United States Code [U.S.C.] Section (§) 9601, et seq.) and, to the extent practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) (Title 40 Code of Federal Regulations [CFR] Part 300). The Department of the Army, the U.S. Environmental Protection Agency (EPA), the California Environmental Protection Agency Department of Toxic Substances Control (DTSC), and the San Francisco Bay Regional Water Quality Control Board (Water Board) have working together on investigations, the feasibility study, the amended record of decision (ROD), and now on this RD for Sites 32 and 33. After this RD has been implemented in the field, the success of this remedy will be the subject of ongoing long-term monitoring, including annual monitoring and Five-Year Review reports per the requirements of CERCLA. 1.1

PURPOSE AND SCOPE

The purpose of this RD is to set forth the remediation plan in sufficient detail to describe the design objectives and evaluations, the components of the design and implementation of the remedial action, and monitoring the cap after it has been constructed in the field. To provide a complete understanding of this design, this RD provides project background and the design process that has led to the complete remedial design. This document includes construction details and materials evaluations and discusses the construction plan. Lastly, the postconstruction monitoring plan is presented to describe the ongoing process of inspections and measurements to evaluate the performance of the in situ caps in Sites 32 and 33. 1.2

DESCRIPTION OF IN SITU CAPPING

The in situ caps for Site 32 and 33 will consist of a soil cap of Bay Mud dredge spoils from Martinez Marina placed uniformly on the exposed sediment surfaces of Sites 32 and 33. The surfaces to be covered are normally inundated with surface water that either flows into or out of the system of mosquito ditches and naturals sloughs that make up Site 32 and Site 33. The location of Sites 32 and 33 is illustrated on Figure 2. The in situ caps are designed to isolate the contaminated sediments at Site 32 and 33 from benthic organisms, and avoid the detrimental environmental impact of removing these materials. In addition, removal is likely infeasible because of site conditions and proximity of threatened and endangered species to potential work areas. Placing an in situ cap of clean material over the Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

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contaminated sediments will prevent exposure to both benthic invertebrates and the sensitive species that feed on the invertebrates. 1.3

REPORT ORGANIZATION

Section 1.0 provides an introduction to the RD. Section 2.0 presents background information for the RD, including a description of the land, history of contamination, and details of the contamination at the site. The background section concludes with the remediation goals. Section 3.0 presents the remedial design, including a review of the design requirements and objectives, the treatability study for the capping materials, and other evaluations that have led to the cap designs. Section 4.0 covers details of the design itself and construction. Section 5.0 covers the post-construction cap monitoring and cap maintenance. 2.0

BACKGROUND

This section presents background information for Sites 32 and 33, including site location, physical setting, the conceptual site model, nature and extent of contamination, and remedial objectives. 2.1

PROJECT LOCATION AND LAND USE

MOTCO is in north-central Contra Costa County, approximately 30 miles northeast of San Francisco, California. Locations of MOTCO, the Litigation Area, and Sites 32 and 33 are illustrated on Figure 1 and Figure 2. MOTCO operates as an ocean shipping terminal to transfer ordnance from trucks or railcars to ships. The facility is bounded on the north by Suisun Bay, on the east by private land and the City of Pittsburg, and on the south and west by the City of Concord (population 121,000). MOTCO encompasses 7,648 acres. A portion of MOTCO includes a landholding referred to as the Litigation Area. The Litigation Area was named as a result of litigation between the Navy and the former property owners regarding recovery of funds to pay for cleanup of contamination in the area. The Litigation Area was contaminated before the Navy acquired the property. Sites 32 and 33 are located within the Litigation Area. The Litigation Area was purchased for use as a buffer zone for military operations to prevent human access and habitation near the weapons handling piers located in the north-central portion of MOTCO. Consistent with that purpose, the area is undeveloped marshland with meandering sloughs, and no future development of the area is planned. 2.2

PHYSICAL SETTING

MOTCO is approximately 10 miles west of the confluence of the Sacramento and San Joaquin Rivers. The confluence of these two rivers forms the delta region, which contains more than 600 miles of interconnected and meandering tidal waterways. Except for a few small streams that drain west into San Francisco Bay, the drainage of Contra Costa County flows either north or west into the San Joaquin River, San Pablo Bay, or Suisun Bay. Drainage from MOTCO flows almost exclusively northward into Suisun Bay. The Litigation Area is composed of upland Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

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and wetland habitats and is not currently developed. Sites 32 and 33 are located within remedial action subsite (RASS) 1 of the Litigation Area. 2.2.1

Geology and Sediments

The geology at the Litigation Area is dominated by Pleistocene and Holocene geomorphology. The subsurface zone consists of inter-fingering alluvial and estuarine depositional environments. Foot slopes, flood plains, and marsh or wetland areas of Quaternary age characterize the Litigation Area. Terraced Pleistocene alluvial fans and flood plain deposits form the foot slopes. Pleistocene deposits are overlain by Holocene flood plain deposits that consist of unconsolidated sands, silts, gravels, and clays. In the wetlands adjacent to Suisun Bay, Holocene alluvial material has been overlain by fine-grained silt and clay, mixed with organic material that makes up the Bay Mud. Most surface area of RASS 1 is primarily underlain by younger Bay Mud and silty peat, a highly compressible fibrous sediment that contains 30 to 75 percent organic materials. Both Bay Mud and silty peat are typical for bay margin marshes. 2.2.2

Hydrogeology

The Litigation Area, which lies on the southern margin of Suisun Bay, includes more than 200 acres of tidal marsh. Nichols Creek drains a local watershed in Los Medanos Hills south of the area and discharges into the marsh in RASS 1. The hydrology of the marsh is characterized by the complex interplay of tides, currents, surface water runoff, evapotranspiration, and weather. The following subsections describe the hydrologic features of the Litigation Area. 2.2.2.1

Surface Water

Surface water bodies in the Litigation Area consist of the natural slough in RASS 1 (referred to as Lost Slough) and tributaries that meander throughout the marsh, the network of manmade mosquito abatement ditches, a ponded area at the western end of RASS 3, and the seasonal stream (Nichols Creek) that flows across RASS 3 and drains into the RASS 3 pond. The Nichols Creek and Lost Slough drainage system discharges into Suisun Bay. RASS 1 is brackish marsh transected by a natural slough, tributaries, and an extensive network of mosquito abatement ditches. Semidiurnal tides in Suisun Bay cause the slough and mosquito abatement ditches in the Litigation Area to flood and drain twice daily. The ditches and Lost Slough are normally partially filled with water. Both seaward and landward currents in the ditches and Lost Slough are strong, with intervening periods of slack water. Field observations have shown that the marsh surface periodically floods during high tides and that up to 2 feet of water may occur on the marsh when high tides coincide with storm events. The extensive network of mosquito ditches in RASS 1 affects the hydrology of the Litigation Area marsh (Figure 3). Review of aerial photographs revealed that ditches had been installed in several stages beginning in 1952 and continuing through 1976. From 1976 to the present, Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

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the network of ditches does not appear to have been modified (Tetra Tech 2003). The morphology of the mosquito abatement ditches indicates that the ditches are dynamic features that have changed significantly since they were dug. As a result of erosion and deposition, the ditches currently range from 1 to 5 feet deep and from 1 to 4 feet wide. The ditches are wide and deep at the proximal end (nearest the slough), but narrow and shallow at the distal end (farthest from the slough), suggesting that the distal ends of the ditches are filling as a result of sedimentation. The results of the tidal monitoring indicated water levels in the marsh at high tides are generally 0.5 to 1 foot lower than water levels at Port Chicago, indicating some attenuation of the high tide elevation occurs across the marsh. Water levels in the marsh at low tide were significantly higher than the levels at Port Chicago during most of February 1998 (Tetra Tech 2003). In contrast, marsh water levels in February 2005 closely matched low tides at Port Chicago, despite similar rainfall patterns (SulTech 2006). Patterns of marsh drainage suggest that the magnitude of the high tide exerts a controlling influence on the degree to which the marsh drains at low tide. The marsh does not drain completely at low tide if an extreme high tide inundates the tidal marsh with an unusually large volume of water. Most of the marsh surface lies between 2.8 and 3.2 feet above mean sea level (msl) and is inundated by high tides from 10 to 27 percent of the time. On average, more than half of the marsh was flooded for several hours each day during the 1997 to 1998 rainy season. Several hours of inundation per day is most likely an upper bound of a typical wet season because conditions were unusually wet during that period. The marsh surface is an accretional environment and the accretion rate is estimated at 2.2 to 4.5 millimeters per year (1 to 2 inches per decade). Metal concentration profiles from the ditch and Lost Slough bottoms exhibit a pattern of both depositional and erosional processes (Tetra Tech 2003). Nichols Creek is a narrow, seasonal creek that drains a small, undeveloped, upland watershed of approximately 1 square mile in Los Medanos Hills south of the sites (Cullinane, Lee, and O’Neill 1988). The creek currently runs along the western boundary of the former Chemical and Pigment Company (CPC), through a culvert beneath the Union Pacific and Burlington Northern Santa Fe Railway Company railroad tracks, and along the southern side of the Union Pacific railroad tracks in RASS 3 to the pond. The creek flows beneath the railroad trestle at the northwestern corner of RASS 3, discharging from the RASS 3 pond to Lost Slough in RASS 1. The creek is narrow (3 to 5 feet wide) and shallow (1 to 2 feet deep), and the creek bed is completely dry during the dry season (typically April through October). The RASS 3 pond is hydraulically connected to RASS 1. The base of the RASS 3 pond is elevated relative to Lost Slough and the mosquito ditches, and a submerged embankment prevents complete drainage of the pond. 2.2.2.2

Groundwater

Groundwater at the Litigation Area occurs in a shallow unconfined water-bearing zone predominantly composed of silty clays. Water occurs at elevations of approximately 3 to 5 feet above msl over most of the Litigation Area. Because of changes in surface elevations, depth to water ranges from about 5 feet below grade in the tidal marsh area to 45 feet below grade in the extreme southern part of the Litigation Area. Groundwater generally flows to the northwest Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

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near the tidal marsh; however, a persistent groundwater mound in the area where Nichols Road crosses the railroad tracks causes groundwater to flow to the west and southwest in the southern portion of the Litigation Area (Tetra Tech 2003). Groundwater quality is generally fair; however, total dissolved solids (TDS), hardness, chlorides, and concentrations of iron are relatively high, especially when data for groundwater are compared with available data for surface water in the area. Groundwater is not a potential source of drinking water because TDS concentrations in groundwater are relatively high throughout most of the Litigation Area (Tetra Tech 2003). A tidal influence study in 1997 showed groundwater in some portions of the Litigation Area is tidally-influenced, but groundwater and surface water do not interact to a significant extent (PRC Environmental Management Inc. [PRC] 1997). Groundwater and surface water may interact to a greater extent near the RASS 3 pond. Groundwater Technology, Inc. (1995), reported that groundwater at the General Chemical Corporation (GCC) property, east of RASS 2, is tidally influenced, and water levels at that location vary by as much as 2 feet over the tidal cycle. 2.2.3

Ecology

Numerous ecological monitoring surveys have been conducted within the Litigation Area, including Sites 32 and 33. Pre-remediation monitoring conducted in 1991 included ecological monitoring for vegetation, small mammals, and rail surveys (PRC 1994). The postremediation monitoring program also included ecological monitoring and the results were presented in the annual monitoring reports as well as the Final Five-Year Periodic Review Assessment for Litigation Area (Tetra Tech 2003). The ecology of the Litigation Area is characteristic of a relatively intact San Francisco Bay estuary. Suisun Bay is influenced by both fresh water from the Sacramento and San Joaquin Rivers and the partly marine waters of San Francisco Bay. RASSs 1 and 2 are characterized by marsh habitat and vegetation that tolerates brackish water. RASSs 3 and 4, which are farther upland, tend to be drier and are characterized by disturbed grasslands. A small, freshwater marsh area can be found in RASS 4, and a small pond lies in the western part of RASS 3. Based on the ecological monitoring, the threatened and endangered species present in the Litigation Area include salt marsh harvest mice (Reithrodontomys megalotis) (federally and state-listed endangered species); California black rail (state-listed threatened species); Delta tule pea (Lathyrus jepsonii, California Native Plant Society [CNPS] List 1B [rare, threatened or endangered in California and elsewhere]); soft bird’s beak (Cordylanthus mollis, federal endangered, California rare, CNPS List 1B); Mason’s lilaeopsis (Lilaeopsis masonii, California rare, CNPS List 1B), and Suisun marsh aster (Aster lentus, CNPS List 1B) (CNPS 2009). 2.3

HISTORY OF CONTAMINATION

Sources of contamination to the Litigation Area and Sites 32 and 33 are the result of off-site manufacturing processes by several companies. The property east of RASS 1 was owned by Allied Signal during the 1991 litigation and is currently owned by Honeywell International Inc. and GCC. The property has been industrially active since 1905, and facilities there have Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

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produced or produce acetic, chromic, hydrochloric, hydrofluoric, nitric, phosphoric, and sulfuric acids; aluminum sulfate; and ammonium hydroxide. Various solvents were also repackaged on the site. On-site disposal of wastes was a standard practice in the early years of operation, including discharge of the effluent from operations into the Suisun Bay (CH2M Hill 2000). Early Navy investigations identified areas of the facility that were potential sources of contamination, including a former alum mud pond, an inactive solid waste disposal area, a former gypsum stockpile area, and a former hydrofluoric acid plant (Cullinane, Lee, and O’Neill 1988) (Figure 2). The former CPC facility is located upgradient of the Litigation Area at 600 Nichols Road in Pittsburg, California (Figure 2). From 1960 to 1998, the CPC facility was used to produce zinc-based chemicals for a variety of uses, including fertilizers, sediment amendments, pharmaceuticals, toiletries, electro-galvanizing, and fungicide sprays. CPC filed for bankruptcy in 1998. Shortly thereafter, it ceased operations at the site and abandoned the facility (DTSC 2003; Engineering/Remediation Resources Group, Inc. [ERRG] 2004). DTSC stated that “significant concern for off-site migration of contaminants” existed based on a site inspection on September 24, 1999 (DTSC 1999). DTSC concluded that CPC’s corrective action measures were inadequate, and predicted “a high probability of releases from the sumps and pits could endanger human health and the environment” (DTSC 2000a). In March 2000, CPC converted from Chapter 11 to Chapter 7 bankruptcy (CWC 2000). In July 2000, the site was transferred to DTSC’s Site Mitigation Branch (DTSC 2000b). Surface water runoff that contains dissolved metals and contaminated sediments has been and may be a continuing source of metals contamination to the Litigation Area because CPC is situated upslope from the Litigation Area. The original course of Nichols Creek emptied into the RASS 2 area and likely contributed to contamination of RASS 1 and RASS 2 from the upstream CPC. The course of Nichols Creek has changed, and it now empties under the railroad trestle farther west and flows into a mosquito ditch that empties into Lost Slough; this more recent course likely carried contamination from the original source to Lost Slough in RASS 1. In addition to the chemical companies cited above, a variety of other activities in or near the Litigation Area may have contributed contaminants to Sites 32 and 33. These activities include the Getty Oil Nichols Pumping Station, which operated until 1971, and a series of brick kilns or Herschoff Ovens. 2.4

CONCEPTUAL SITE MODEL

The conceptual site model for Litigation Area Sites 32 and 33 was developed during the 2008 supplemental feasibility study and has been updated based on accumulated site knowledge. The current conceptual site model is presented below. Sites 32 and 33 are in RASS 1, which covers 210 acres adjacent to Suisun Bay and includes tidally-influenced brackish wetland, with minimal upland and associated transitional zone habitat. Neither the Army nor the Navy conducted any operations on RASS 1 that contributed contamination; these properties were used only as buffer zones for munitions loading at the installation. Major sources of contamination to RASS 1 were historical spills from: (1) the adjacent General Chemical/Honeywell Inc. facility to the east, (2) the General Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

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Chemical/Honeywell Inc. property adjacent to the southeastern corner of the RASS 1 wetland (Corner Lot), and (3) the former Chemical and Pigment Company facility upstream on Nichols Creek. Smaller on-site sources from previous landowners may have contributed some contamination to the RASSs. Although most of this contamination was released within the past 50 years, ongoing sources of contamination may still exist off site. DTSC issued a final Remedial Action Implementation Work Plan for remediating contamination at the former CPC in May 2012 (ERRG 2012). Seven metals (arsenic, cadmium, copper, lead, mercury, selenium, and zinc) considered COECs in sediment at the Litigation Area. Of these seven metals four are driving the remediation for each area as indicated on Figure 3. Chemicals posing risk at levels that drive remedial action in Site 32 include arsenic at a single sample location, zinc at a single sample location, and copper throughout most of the area. Chemicals posing risk in Site 33 including cadmium at a single sample location, zinc at a single sample location, and copper over most of the areas. Potential pathways for chemical mobilization and transport within the Litigation Area and to Suisun Bay or other off-site locations include: •

Particulate surface transport by wind erosion as dust

•

Surface water transport of dissolved chemicals or chemicals adsorbed to suspended particles

•

Bioturbation caused by invertebrates moving through sediments within the biologically active zone of the sediment

•

Groundwater transport of dissolved metals

•

Biotic transport of chemicals in plant and animal tissue

Of these mechanisms, sediment transport by surface water movement and bioturbation within the biologically active zone are considered the most significant pathways at Sites 32 and 33. Most movement is likely caused by sediment transport by water, and a lesser degree is likely a result of bioturbation. Most biological activity occurs within the top few centimeters of sediment (EPA 2005). Benthic invertebrate populations are less likely to inhabit anoxic sediments, so the depth to the anoxic layer provides an indication of the depth of biologic activity at a sediment site. Direct observation in RASS 1 indicate the depth to the anoxic layer at the sites rarely extended more than 2 inches and, except for one measurement of 10 inches, did not exceed 4.5 inches (PRC 1996). The marsh surface, mosquito ditches, and Lost Slough at Site 32 and Site 33 are within an accretional environment. The accretion rate on the marsh surface is estimated at 2.2 to 4.5 millimeters per year (Tetra Tech 2003). Metal concentration profiles from the ditch and Lost Slough bottoms exhibit a pattern of both depositional and erosional processes (Tetra Tech 2003).


7

The accretion rates within Lost Slough and the mosquito ditches are not known. While accretion may bury the sediments, bioturbation tends to bring a small portion of the buried contaminants up and into the cleaner sediments. Bioturbation, which primarily occurs within the top 6 inches, will eventually not be a concern as the contaminants become more deeply buried. At present, some of the contamination still exists in the biologically active zone and therefore currently poses risk to the environment. Remediation of Sites 32 and 33 is necessary to address risk of chemicals of ecological concern (COEC) to the environment. 2.5

NATURE AND EXTENT OF CONTAMINATION

The following sections identify and describe the extent of the seven metals (arsenic, cadmium, copper, lead, mercury, selenium, and zinc) considered COECs in sediment at the Litigation Area. Data for characterizing the nature and extent of contamination are from 5 years of post-remediation monitoring, the October 2000 sampling event, and the Lost Slough sediment characterization included in a treatability study in summer 2005, and the 2009 pre-RD sampling event. In the following sections are brief discussions of concentrations and distributions of those seven metals in sediment at Site 32 (Unit 7, mosquito abatement ditches) and Site 33 (Units 10 and 11, Lost Slough). Metals concentrations were detected in samples collected from 0 to 0.5 feet below sediment surface (bss) during 5 years of monitoring (1995 through 1999), from 0 to 1.0 foot bss during the treatability study in 2005, and 0 to 0.5 foot bss and 1.0 to 1.5 feet bss during the pre-RD field investigation. For reference, concentrations are also provided for Unit 9 of Lost Slough. A more detailed analysis of variations in chemical concentrations at sampling locations is presented in the Five-Year Periodic Review Assessment Report (Tetra Tech 2003), treatability study (SulTech 2006), and pre-RD technical memorandum (Tetra Tech 2010). 2.5.1

Arsenic

The highest sediment concentrations of arsenic were detected in the southeastern portion of RASS 1 in the ditches within Unit 7; the maximum concentration was 3,260 milligrams per kilogram (mg/kg) detected during Year 2. Scattered high concentrations were also detected at some locations in Lost Slough. This spatial distribution is consistent with the historical source of spills coming from the GCC facility to the east and the former CPC site to the south and migrating into Lost Slough over time (Tetra Tech 2003). The maximum concentrations of arsenic at each site during the 5-year monitoring program and additional site investigations are listed in Table 1 and shown in Figure 4.


8

TABLE 1: MAXIMUM CONCENTRATIONS OF ARSENIC IN SEDIMENT (mg/kg) Remedial Design Report, In Situ Cap, Site 32 and 33, Litigation Area, MOTCO

Unit

Year 1 (1995)

Year 2 (1997)

Year 3 (1997)

Year 4 (1998)

Year 5 (1999)

Five-Year Review & Data Gaps Sampling (2000)

Sample Depth

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

Site 32 (Unit 7)

1,110

3,260

1,110

706

1,000

Site 33 (Unit 10 and 11)

487

331

375

1,060

228

Notes: bgs ft J mg/kg

Below ground surface Feet Estimated concentration Milligrams per kilogram

2.5.2

Cadmium

NA RD U

Treatability Study (2005)

Pre-RD Investigation (2009)


0-1.0 ft bgs

0-0.5 ft bgs

1.0-1.5 ft bgs

385

NA

2,200

526

185

572

203J

NA

Not analyzed Remedial design Undetected concentration

The highest sediment concentrations of cadmium were detected in 1997 in Site 33; the maximum concentration was 832 mg/kg. The maximum concentrations of cadmium for each unit during years 1 through 5 and subsequent studies are provided in Table 2 and shown in Figure 5. TABLE 2: MAXIMUM CONCENTRATIONS OF CADMIUM IN SEDIMENT (mg/kg) Remedial Design Report, In Situ Cap, Site 32 and 33, Litigation Area, MOTCO

Unit

Year 1 (1995)

Year 2 (1997)

Year 3 (1997)

Year 4 (1998)

Year 5 (1999)


Sample Depth

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

1.0-1.5 ft bgs

Site 32 (Unit 7)

16.5

8.4

148

109

94.6

63.8

NA

24.9

247


63.8

26.1

832

108

124

16.2

70.3

90.6

NA




NA RD U





9

2.5.3

Copper

The highest sediment concentrations of copper were detected within the southeastern portion of the marsh in Site 32 ditches; the maximum concentration was 1,540 mg/kg detected during Year 3. Scattered high concentrations were also detected in Lost Slough at Site 33. This spatial distribution is consistent with the historical source in spills coming mainly from the former CPC site to the south. The maximum concentrations of copper for each site during the 5-year monitoring program and additional site investigations are listed in Table 3 and shown in Figure 6. TABLE 3: MAXIMUM CONCENTRATIONS OF COPPER IN SEDIMENT (mg/kg) Remedial Design Report, In Situ Cap, Site 32 and 33, Litigation Area, MOTCO

Unit

Year 1 (1995)

Year 2 (1997)

Year 3 (1997)

Year 4 (1998)

Year 5 (1999)


Sample Depth

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

1.0-1.5 ft bgs

Site 32 (Unit 7)

569

1,400

1,540

1,420

1,410

892

NA

955

1,290


586

208

1,140

689

518

196

460

342J

NA


2.5.4


NA RD U





Lead

In RASS 1, the highest sediment concentrations of lead were in Site 32; the maximum concentration was 475 mg/kg detected during Year 3. Lead has been detected at consistently elevated concentrations in a few locations within RASS 3, adjacent to the former CPC facility, and downstream in the RASS 3 pond (Tetra Tech 2003). The maximum concentrations of lead for each site during the 5-year monitoring program and additional site investigations are listed in Table 4 and shown in Figure 7.


10

TABLE 4: MAXIMUM CONCENTRATIONS OF LEAD IN SEDIMENT (mg/kg) Remedial Design Report, In Situ Cap, Site 32 and 33, Litigation Area, MOTCO

Unit

Year 1 (1995)

Year 2 (1997)

Year 3 (1997)

Year 4 (1998)

Year 5 (1999)


Sample Depth

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

Site 32 (Unit 7)

168

444

475

175

134


231

128

331

112

209



2.5.5

NA RD U




0-0.5 ft bgs

0-0.5 ft bgs

1.0-1.5 ft bgs

94.8

NA

325

172

108

115

71.3

NA


Mercury

Mercury data are available for only a limited number of sediment samples. Samples were analyzed for mercury in 1995, 2000, and 2005 during the treatability study and in 2009 during the pre-RD investigation. The highest concentration of mercury was 1.61 mg/kg at Site 32 during the pre-RD investigation. The maximum concentrations of mercury at each site during year 1, data gaps sampling, the treatability study, and pre-RD investigation are listed in Table 5 and shown in Figure 8. TABLE 5: MAXIMUM CONCENTRATIONS OF MERCURY IN SEDIMENT (mg/kg) Remedial Design Report, In Situ Cap, Site 32 and 33, Litigation Area, MOTCO

Unit Sample Depth Site 32 (Unit 7) Site 33 (Unit 10 and 11) Notes: bgs ft J mg/kg

Year 1 (1995)

Five-Year Review & Data Gaps Sampling(2000)

TS (2005)



0-0.5 ft bgs NA

0-0.5 ft bgs 0.52

0-0.5 ft bgs NA

0-0.5 ft bgs 1.02

1.0-1.5 ft bgs 1.61

0.67

0.36

1.3

0.725U

NA



NA RD U


11

2.5.6

Selenium

The highest sediment concentrations of selenium were detected at Site 32 during the pre-RD investigation at a depth from 1.0 to 1.5 feet below ground surface (bgs). In bottom sediments, the maximum concentration was detected in Unit 10; 8.0 mg/kg was detected during the 2005 treatability study. Scattered high concentrations were also detected at some locations during monitoring years 1 through 5. The maximum concentrations of selenium for each site during the 5-year monitoring program and additional site investigations are listed in Table 6 and shown in Figure 9. TABLE 6: MAXIMUM CONCENTRATIONS OF SELENIUM IN SEDIMENT (mg/kg) Remedial Design Report, In Situ Cap, Site 32 and 33, Litigation Area, MOTCO

Unit

Year 1 (1995)

Year 2 (1997)

Year 3 (1997)

Year 4 (1998)

Year 5 (1999)


Sample Depth

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

Site 32 (Unit 7)

3.1

7.6

7.2

6.5

5.7


3.6

6.5

7.0

4.8

4.0


2.5.7


NA RD U




0-0.5 ft bgs

0-0.5 ft bgs

1.0-1.5 ft bgs

2.8

NA

12.2

11.9U

3.7

8.0

7.3U

NA


Zinc

Zinc concentrations were elevated at many locations across the Litigation Area; this distribution likely reflects the historical role of Nichols Creek in transporting zinc from the source at the former CPC, downstream through RASS 3 into RASS 1. High concentrations of zinc in sediment occurred across the southern portion of RASS 1, including Lost Slough and the mosquito ditches. Most locations in the southern portion of RASS 1 contained zinc concentrations exceeding 1,640 mg/kg; many concentrations were between 10,000 and 20,000 mg/kg, and one was as high as 89,300 mg/kg. Concentrations in RASS 3 were typically greater than 1,640 mg/kg, especially near the former CPC property and in the RASS 3 pond. The maximum concentrations of zinc for each site during the 5-year monitoring program and additional site investigations are listed in Table 7 and shown in Figure 10.


12

TABLE 7: MAXIMUM CONCENTRATIONS OF ZINC IN SEDIMENT (mg/kg) Remedial Design Report, In Situ Cap, Site 32 and 33, Litigation Area, MOTCO

Unit

Year 1 (1995)

Year 2 (1997)

Year 3 (1997)

Year 4 (1998)

Year 5 (1999)


Sample Depth

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

0-0.5 ft bgs

1.0-1.5 ft bgs

Site 32 (Unit 7)

2,040

2,600

11,700

8,070

7,950

2,950

NA

3,300

33,800


6,480

5,560

89,300

15,000

19,500

3,000

6,980

7,230

NA



2.6

NA RD U





REMEDIATION GOALS

Preliminary remediation goals (PRG) for the Litigation Area were calculated for Sites 32 and 33 using the same general modeling methods and parameters presented in the baseline ecological risk assessment for the Five-Year Periodic Review Assessment Report (Tetra Tech 2003). PRGs were calculated separately for Sites 32 (Unit 7, mosquito abatement ditches) and 33 (Units 10 and 11, Lost Slough) for the seven COECs (arsenic, cadmium, copper, lead, mercury, selenium, and zinc) in sediment, and for each of the following assessment endpoints: •

The mallard was selected as an assessment endpoint representing aquatic birds at Site 33 (Units 10 and 11, Lost Slough).

•

The California black rail was selected as an assessment endpoint representing carnivorous shorebirds at Sites 32 (Unit 7, mosquito abatement ditches) and 33 (Units 10 and 11, Lost Slough).

•

The Virginia rail was selected as an assessment endpoint representing carnivorous wading birds at Sites 32 (Unit 7, mosquito abatement ditches) and 33 (Units 10 and 11, Lost Slough).

•

The great blue heron was selected as an assessment endpoint representing wading birds at Site 33 (Units 10 and 11, Lost Slough).

•

The Suisun song sparrow was selected as an assessment endpoint representing passerine birds at Sites 32 (Unit 7, mosquito abatement ditches) and 33 (Units 10 and 11, Lost Slough).

•

The river otter was selected as an assessment endpoint representing carnivorous mammals at Site 33 (Units 10 and 11, Lost Slough).


13

Final remedial goals (RGs) were based on the calculated sediment concentration for the most sensitive receptor, which is the highest concentration of a chemical in sediment expected to be protective of all ecological receptors. The final RGs for Unit 7, mosquito abatement ditches, and Units 10 and 11, Lost Slough are listed In Table 8. TABLE 8: FINAL REMEDIATION GOALS Remedial Design Report, In Situ Cap, Site 32 and 33, Litigation Area, MOTCO Source

Arsenic

Cadmium

Copper

Lead

Mercury Selenium

Zinc

Site 32 (Unit 7 Mosquito Abatement Ditches) Target Concentrations (Area-Weighted Averages) Remediation Goals (Do-Not-Exceed Criteria)

b

689

12.2

111

95.0

2.98

12.0

2,420

1,380

124

200

553

6.89

24.18

12,100

Site 33 (Units 10 & 11 of Lost Slough) Target Concentrations (Area-Weighted Average)

603

10.7

96.7

95.0

2.62

16.1

2,110

Remediation Goals (Do-Not-Exceed Criteria)

1,200

120

150

484

6.03

28.3

10,600

Notes:

All concentrations in milligrams per kilogram.

a b

Remediation goals rounded to three significant figures Tidal Area ambient concentration (Appendix I of Tetra Tech 2003)

3.0

b

REMEDIAL DESIGN

This section discusses design requirements and objectives, summarizes the capping materials treatability study (Appendix A), cap stability evaluation (Appendix B), bioturbation evaluation (Appendix C), and the cap design (Appendix D). 3.1

DESIGN REQUIREMENTS AND OBJECTIVES

Design requirements are mandated by the ROD. This section provides an overview of the design process and design criteria. 3.1.1

Remedy of Record

The remedy selection criteria outlined in CERCLA § 121 (b) were used to select the Army’s preferred remedies for Sites 32 and 33. As described in the ROD amendment, in situ capping for Site 32 and in situ capping for Site 33 satisfy the CERCLA selection criteria. The in situ cap will consist of active or passive material placed over the contaminated sediments. The in situ cap location covers the areas requiring remediation as shown in Figure 3 as well as Sheets C-3 and C-4 of the design drawings (Appendix D), and the cap will extend across the entire width of the ditches and slough. The selected remedies satisfies all nine CERCLA selection criteria and: (1) are Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

14

protective of the environment, (2) comply with applicable or relevant and appropriate requirements (ARARs), (3) are effective and permanent in the long term, (4) reduce toxicity, mobility, or volume through treatment to the extent practicable, (5) are effective in the short term, (6) are cost effective, (7) can be implemented, (8) are supported by the community, and (9) are supported by state regulatory agencies. The selected remedies for Sites 32 and 33 satisfy the CERLA threshold criteria because they protect the environment and comply with ARARs. In addition, they provide the highest combined benefit considering each of the above CERLCA balancing and modifying criteria. The selected remedies are the most beneficial in part as a result of the low degree of impact or intrusion caused during implementation. These alternatives protect the sensitive marshland, which provides valuable habitat for many life forms, including threatened and endangered species. The low degree of impact is primarily the result of the following critical elements embodied in the selected remedies: •

The selected remedies do not rely on construction of temporary roadways on the marsh surface that would likely cause long-term disturbance to this sensitive habitat.

•

The work will occur outside the black rail nesting season. Only small and isolated staging areas for the work will be necessary on the marsh surface. Potentially damaging disturbance caused by staging the work in habitat areas of the endangered salt marsh harvest mouse will be held to a minimum.

•

The work area is limited to the bottom of the sloughs and ditches to avoid disturbances to existing marshland and to minimize the re-suspension of contaminated sediment that exists below the marsh surface.

In situ capping for Sites 32 and 33 was selected in the June 3, 2012 ROD (Tetra Tech 2012). 3.1.2

Design Process Overview

The design process for Sites 32 and 33 includes evaluation and selection of the cap materials, thickness, and placement methodology and erosion control improvements, if required. The design includes a treatability study, a cap stability evaluation, and a bioturbation evaluation. The treatability study is summarized in Section 3.2, and the full study report is included as Appendix A. The cap stability evaluation is summarized in Section 3.3, and the complete report is included as Appendix B. The bioturbidity evaluation is summarized in Section 3.4, and the complete evaluation is included as Appendix C. Detail design information regarding the selected cap design is presented in Section 3.5. The lateral extent of the cap is based on the remedial investigation data and the cap remediation area identified in the Final Supplemental Feasibility Study Amendment (Tetra Tech 2011) and ROD (Tetra Tech 2012).


15

The cap material and design thickness are based on the chemical sequestering abilities of the cap material, physical isolation properties, and stability based on estimated tidal current flows through sloughs and ditches and the critical shear stresses. 3.1.3

Cap Design and Performance Criteria

Several design and performance factors have been assumed in the design, and each is discussed below. Cap design and performance are intended to provide a cap life of 30 years before the total flux of copper concentration exceeds the Target Concentrations - Area Weighted Average Remedial Goal for Copper. Copper was sued as the basis of design because it is the most prevalent and had lower average partition coefficient (Kd) then arsenic. The cap stability criterion for erosion will be based on critical stormwater runoff (flood) conditions with a 1 percent chance that it would be exceeded in a given year, and the flood event is assumed to occur while the tidal elevation in Suisun Bay is at mean low water. Tidal changes are dynamic and transitory in nature, but the modeling was conducted assuming steady-state conditions. A lower channel velocity and less erosion will occur during higher tides, so the model assumption is considered conservative. The cap provides physical isolation of contaminated sediments. Bioturbation mixing zone depths are considered in the design to address bioturbation by burrowing invertebrates and higher level animals feeding on invertebrates. Overall, sediment is expected to accumulate (accrete) naturally on the cap as a result of sea level rise and long-term sediment consolidation. Although accretion is expected, it is not accommodated in the design. The sediment accretion contributes to the conservative (protective) nature of the design because the accumulation of sediment will increase the thickness of the cap over time. 3.2

CAPPING MATERIALS TREATABILITY STUDY EVALUATION SUMMARY

A comprehensive site-specific evaluation of cap materials for Sites 32 and 33 was conducted in 2011 (Tetra Tech 2011). The effectiveness of the proposed cap materials at isolating existing site contaminants is closely related to site-specific conditions, including material properties of the contaminated sediments, contaminated sediment pore water, surface water conditions, and the relationship between cap materials and the contaminated sediments below the cap. Because of the interrelated dependencies, the evaluation included testing potential cap materials obtained from off-site sources, contaminated sediments obtained from Sites 32 and 33, sediment pore water extracted from the contaminated sediments obtained from Sites 32 and 33, and samples of surface water obtained from Sites 32 and 33.


16

3.2.1

Testing of Materials

Materials and chemical tests were run on each of the imported cap materials, on imported cap materials in the presence of native contaminated sediments, on native sediments and sediment pore water, and on native surface waters. The tests performed on each medium are described below. 3.2.1.1

Testing Cap Materials

Five distinct potential cap materials were considered in the evaluation and subjected to a battery of tests to evaluate cap material properties. Samples of the following potential cap materials were obtained and tested: 1. Dredge spoil deposits of San Francisco Bay Mud obtained from a local source, Martinez Marina dredge spoil ponds 2. Aggregate gravel coated with modified clay obtained from a commercial supplier and marketed under the name of AquaGate 3. Macroporous aluminosilicate, a manufactured porous ceramic composite material obtained from a commercial supplier 4. Rock Phosphate (mineral apatite) obtained from a commercial quarry operated by PotashCorp in Northbrook, Illinois 5. Biological Apatite (Apatite II), a product made from natural fish bones and sold under the commercial name of Apatite II from PIMS-NS, Inc., in Kennewick, Washington The following tests were conducted on potential cap materials. 1. Physical testing including moisture content, specific gravity, grain size, total organic carbon, and metals 2. Leachable metals, leachable volatile organic compounds (VOCs), and leachable semivolatile organic compounds (SVOCs) using a deionized water (DI) waste extraction test (WET) 3. Sorption tests to determine the arsenic and copper sorption capacity 4. Settling velocities of selected cap materials in site-specific surface water. 3.2.1.2

Combined Testing of Contaminated Sediments with Cap Materials

Each of the cap materials was tested to evaluate if metals would be desorbed when cap materials are in the presence of contaminated on-site sediments because desorption of metals is enhanced in some cases when certain cap materials and certain contaminated sediment media are present. Desorption of various metals (aluminum, antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, molybdenum, nickel, Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

17

selenium, silver, thallium, vanadium, and zinc) from the cap materials when combined with sediment was assessed by testing. 3.2.1.3

Testing Contaminated Sediments and Sediment Pore Water

Sediments from Sites 32 and 33 were obtained using a ponar sampler in the field. Samples from each site were analyzed for total metals including arsenic, cadmium, copper, iron, lead, mercury, selenium, and zinc. Sediment samples from each site were also tested to evaluate sorption of arsenic and copper to sediment. Pore water was extracted separately from the sediment samples at each site and analyzed for total metals, including arsenic, cadmium, copper, iron, lead, mercury, selenium, and zinc. 3.2.1.4

Testing of Surface Water

Samples of surface water were obtained from Sites 32 and 33 and field analyses included; temperature, pH, conductivity, oxidation-reduction potential, dissolved oxygen, and turbidity. 3.2.2

Test Results

The results of each of the above described tests are summarized below. Detailed information is presented in Appendix A. 3.2.2.1

Test Results for Cap Material

Cap Material Physical Properties

Physical property test results for each cap material are used in the design process to quantify general properties of the potential cap materials. Detailed test results for moisture content, specific gravity, grain size, total organic carbon, and metals are presented in Appendix A. Cap Leaching Properties

Each cap material was tested using a modified version of the California Code of Regulations, Title 22 WET. The test was modified by using DI water in lieu of the standard method leachate to more closely mimic field conditions. The concentrations of selected metals in the DI-WET leachate were compared with various water quality screening criteria developed by the San Francisco Bay Region Water Board Basin Plan (Water Board 2010), National AWQC, or California Toxics Rule including: 1. Freshwater acute ambient water quality criteria (AWQC) 2. Freshwater chronic AWQC 3. Marine chronic AWQC


18

Most of the tested metal concentrations in DI-WET leachate are lower than the freshwater acute and chronic AWQC. The concentration of leachable arsenic (68 micrograms per liter [µg/L]) from the Apatite II during the DI-WET test was lower than the freshwater acute (340 µg/L) and chronic (150 µg/L) AWQC, but higher than the marine chronic (36 µg/L) AWQC. It should be noted that the total arsenic concentrations in the Apatite II were relatively smaller (0.25 mg/kg) with respect to the average concentrations of arsenic present in other selected cap materials (8.75 mg/kg for AquaGate, 4.65 mg/kg for Macroporous Aluminosilicate, and 14.67 mg/kg for Bay Mud). The leaching of nickel from the Bay Mud in DI-WET is significantly lower than the freshwater acute and chronic AWQC and slightly higher than marine chronic AWQC. Overall, the DI WET concentrations for metals are below the average background DI WET concentrations for the site and would not pose a risk to the environment. The DI WET arsenic concentration from Apatite II was significantly higher than that from AquaGate, Mineral Apatite, and Bay Mud. The DI WET arsenic concentration from Apatite II was higher than the marine chronic AWQC. The DI WET arsenic concentration from phosphate rock was higher than the other cap materials, but less than that of Apatite II. Cap Material Sorption

Sorption tests were performed using batch methods to assess the capacity of the cap materials to sorb copper and arsenic. Each cap material was evaluated by mixing native surface waters spiked with various concentrations of arsenic and copper with a sample of the cap material under consideration. The mixture was agitated for 48 hours. After it had been agitated, the mixture was assumed to be at or near its equilibrium concentration, and the sorption of metals to the cap materials was evaluated by measuring the concentration of residual contamination in the fluid portion of the sample and comparing that result with the original spiked concentration. A partitioning coefficient (Kd) was calculated for each test. Because each cap material has a differing capacity to sorb metals, each material can be ranked in order in its sorption capacity relative to the other cap materials. The amount of copper sorbed by the each cap material on a site-specific basis for Sites 32 and 33 is ranked in the following order: 1. 2. 3. 4.

Macroporous Aluminosilicate Phosphate Rock Apatite II Bay Mud and AquaGate with similar results.

The amount of arsenic sorbed by each cap material for Sites 32 and 33 is ranked in the following order: 1. 2. 3. 4.

Macroporous Aluminosilicate Bay Mud and Apatite II with similar results AquaGate Phosphate Rock.


19

Cap Material Settlement Velocities

AquaGate and Macroporous Aliminosilicate had the highest settling velocities. Bay Mud settlement depended on particle size, with the largest particles settling more rapidly than the finer grained particles. 3.2.2.2

Test Results from Combined Testing of Sediments and Cap Materials

In general, heavy metals were not released from cap materials in the presence of contaminated sediments at a rate that was significantly higher than the rate the sediment materials released metals in the absence of cap materials. Apatite II did not follow the same pattern, however. Arsenic was desorbed from sediment and Apatite II at a rate higher than the control of contaminated sediment alone. 3.2.2.3

Test Results from Contaminated Sediments and Sediment Pore Water

Iron is abundant in the native sediments, generally considered helpful in binding contaminants, and not considered toxic. The concentrations of metals in sediment and pore water show similar trends in metals concentrations in both media (sediments and sediment pore water), indicating similar partitioning patterns of these metals. The sediment samples collected from Site 33 showed lower concentrations of these metals than the remediation goals. The copper concentrations in replicate samples were 89 mg/kg, 93 mg/kg, and 100 mg/kg, while the discrete do-not-exceed and target area weighted average goals of copper for Site 33 were 96.7 mg/kg and 139 mg/kg. The grab sediment sample collected from Site 32 showed lower concentrations of arsenic, lead, mercury, and selenium than that of the remediation goal concentrations. The metals concentrations (except copper) were significantly lower than the discrete do-not-exceed limit for Site 32. The zinc concentrations were lower than the discrete do-not-exceed limit and higher than target area weighted average for Site 32. 3.2.2.4

Field Measurement from Surface Water

The surface water temperature varied from 19 ºC to 23.7 ºC. The in situ pH measurements of surface water varied from 6.70 to 7.26. The turbidity varied for various locations and depths ranging from 4.6 to 29.1 nephelometric turbidity units (NTU). The variations in pH and turbidity might be caused by the change in tidal inflow and outflow water and characteristics of local deposits of sediment materials. Conductivity varied from 8,042 microSiemens per square centimeter (μS/cm2) to 9,239 μS/cm2. The field measurements were within the expected ranges. 3.2.3

Evaluation Results - Chemical Flux Modeling

The final portion of treatability study and cap effectiveness modeling incorporates the many test results into a model to estimate chemical flux and provide estimates of cap life for each material for a given thickness with time. The model is based on the mass transfer equations for advection and diffusion. The flux modeling evaluates all cap materials, but ends up concentrating on Bay Mud as a cap material because Bay Mud is: (1) effective as a cap Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

20

material, (2) locally available requiring relatively little transportation cost and fuel energy, and (3) a free and renewable resource resulting from the regular dredging of Martinez Marina for which there is no market, and which otherwise accumulate on land. •

Chemical flux modeling for Site 32 indicates that an 8-inch cap of Bay Mud would reduce pore water concentration below that of the discrete do-not-exceed remediation goal at Site 32 for 30 years.

•

Chemical flux modeling for Site 33 indicates that an 8-inch cap of Bay Mud would reduce pore water concentration below that of the discrete do-not-exceed remediation goal at Site 33 for 30 years.

3.2.4

Selection of Cap Material

Bay Mud is the selected cap material for Sites 32 and 33 based on the following considerations: •

Availability – Bay Mud is readily available within 20 miles of the site; other materials are manufactured and not locally available.

•

Cost Effectiveness – Bay Mud is a free from a local borrow source.

•

Ecological impact – Bay Mud is a natural material similar to the existing material in the slough and ditches and analytical chemistry results did not identify elevated chemical concentrations.

•

Physical Isolation – Bay Mud is effective in providing physical isolation of the contaminated sediments from the environment and also creates a suitable substrate for invertebrates after remediation.

•

Sorption Capacity – Bay Mud exhibited good sorption capabilities for arsenic and copper, and the model indicated Bay Mud was as effective as the other active cap materials. Bay Mud is effective at providing chemical isolation of the contaminated sediments from the environment. A cap thickness of 8 inches of Bay Mud at Site 32 and Site 33 will meet the design criteria of having a flux concentration of copper below the Target Area Weighted Average Remediation Goal for 30 years.

•

Cap Stability — The Bay Mud has a lower critical velocity than the other cap materials, but all of the cap materials — with the exception of macroporous aluminosilicate — had critical velocities less than the current velocity and would erode. The erosion concerns can be mitigated by increasing the thickness of the cap. In addition, Bay Mud has a slower settling velocity, which could increase turbidity and resuspension of the material. However, field implementation methods can be designed to minimize this impact.


21

3.3

CAP STABILITY EVALUATION

The cap stability evaluation was conducted to evaluate erosion potential of water moving through the ditches and sloughs at Sites 32 and 33 for each of the potential cap materials and included: 1. Performing hydraulic modeling to estimate current flows at various locations in the ditch and slough system. 2. Estimating cap-specific critical flow velocities at which particulate erosion occurs. 3. Evaluating the modeled water velocity relative to the critical flow velocity to determine estimated stability under various estimated flows and locations in the sloughs and ditches to identify areas potentially subject to erosion. 4. Performing engineering design to minimize the possibility of erosion in areas identified as subject to erosion. Flow velocities within the Site 33 slough were estimated using a hydraulic model of the surrounding watershed during flood events, presuming flooding at low tide. Preliminary flow velocity calculations within the slough range from 0.21 to 4.1 feet per second. The flow velocities in the main channel of the slough were much higher than in the east and west tributaries. Based only on the Capping Materials Treatability Study Evaluation (Appendix A), a cap of Bay Mud dredge spoils can be designed to be protective of the environment. Since Bay Mud is the only locally-available material and is the only material available free of charge, each evaluation is first directed at assessing whether Bay Mud is suitable or if it must be rejected as a cap material. The critical flow velocity to initiate erosion of Bay Mud was estimated at 0.83 feet per second to 0.89 feet per second, which are less than the estimated bottom current velocity of 3.5 feet per second to 4.1 feet per second in the main channel of the slough indicating potential for erosion. The bottom current velocity in the east and west tributaries, which is assumed to be similar to the velocity in the ditches, was less than the critical flow velocity for Bay Mud. Therefore, erosion is not anticipated in the ditches and tributaries at Site 32 and Site 33. Erosion of the Bay Mud cap is a concern in the main channel of the slough. Based on the Sedflumes study evaluation (Appendix B), the Bay Mud consolidates to a higher critical shear stress with depth. The evaluation and corresponding calculations indicate that the critical shear stress of Bay Mud at a depth of approximately 10 centimeters (3.94 inches) would result in minimal erosion of the cap. Therefore, the cap design will include an additional 4 inches of Bay in the main channel of the slough.


22

3.4

BIOTURBATION EVALUATION

The Bioturbation Evaluation (Appendix C) evaluates the required cap thickness necessary to prevent the benthic invertebrate community from burrowing through the cap into the contaminated sediments below. Locally-derived Bay Mud dredge spoils from the Martinez Marina are similar to the sediments in the ditches and sloughs and, if used as a cap material, would eventually support a benthic community similar to that which exists at the site now. The estimated depth of bioturbation for Bay Mud sediments imported from Martinez Marina is anticipated to be similar to the existing sediments. The benthic invertebrate and fauna in sediments in the ditches and sloughs reside in the oxygen-rich oxic layer of sediment. The benthic invertebrate characterization conducted in 1995 surveyed 34 sediment sample locations in the tidal wetland habitat and visually estimated and then measured the estimated thickness of the oxic layer in each sediment core. The upper 95 percent confidence interval of the mean for the thickness of the oxic layer and therefore the thickness of the bioturbation zone is 2.44 inches. The maximum recorded thickness was 10 inches and the next thickest measurement was 5 inches. The 10-inch-thick measurement was considered a statistical outlier and was not used. The maximum design thickness is 5 inches. These estimates agree with general recommendations for mixing zone depth for the design of in situ caps. 3.5

CAP DESIGN

Considering the treatability study, cap effectiveness modeling, stability evaluation, and bioturbation, the cap thickness design for Site 32 is 8 inches of Martinez Marina Bay Mud. The chemical flux model indicates that a cap thickness of 8 inches will result in a pore water concentration that does not exceed the Target Area Weighted Average Concentration Remediation Goal within 30 years. The 8-inch-thick cap design will provide adequate physical isolation so that the benthic community is not expected to extend into contaminated sediments. The cap thickness design for Site 33 east and west tributaries is 8 inches of Martinez Marina Bay Mud based on the chemical flux model. The chemical flux model indicates that a cap thickness of 8 inches will result in a pore water concentration that does not exceed the Target Area Weighted Average Concentration Remediation Goal within 30 years. The 8-inch cap will also provide adequate physical isolation so that the benthic community is not expected to extend into contaminated sediments. In addition, the cap design for the main channel of the slough will include an additional 4 inches of Bay Mud for a total cap thickness of 12 inches. Locations that will receive the cap are based on the Final Supplemental Feasibility Study Addendum (Tetra Tech 2011), meeting the Target Area Weighted Average Remediation Goal based on the metal concentration of the cap material and sampling results from the 1999 and 2009 investigations. Based on field observations, there are ditches within Site 32 that are less than 12 inches deep and overgrown with vegetation and deposited materials. Ditches less than 12 inches deep will not be capped. The extent of capping is indicated on design drawing sheets C-3 and C-4 in Appendix D. Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

23

4.0

CAP MATERIAL PLACEMENT AND OPERATIONS PLAN

This section describes the methodologies and sequence for placing the cap material and the overall operations plan. Cap placement considerations are influenced by the site-specific conditions and limitations resulting from the presence of sensitive wildlife habitat. Equipment and cap placement methodologies have been selected to minimize impacts to the site. Specific avoidance measures are included in the plan for the protection of threatened and endangered species. Construction monitoring is required to assess the placement techniques and to provide quality control to assure that the placement methods meet design objectives. 4.1

GENERAL CONSIDERATIONS

The selection of equipment and the cap placement methods reflects the following objectives and working conditions: •

Placing the cap in a controlled and accurate manner in a layer of uniform thickness.

•

Minimizing disturbance of sloughs and ditches and consequent re-suspension of contaminated sediments.

•

Minimizing disturbance of the marshland surface, except to allow access and working area for cap placement.

•

Maintaining cap stability during ebbing and flooding tides and during stormwater runoff events.

•

Working with site conditions: − Most areas to be covered with the cap are lower than the mean lower low water elevation, so the cap surface will typically be under water and the tidal elevations and currents will be continually changing. − The existing sediments are extremely soft and potentially unstable across much of the site. − Sensitive species are present including the salt marsh harvest mouse and the California black rail − Sensitive plant species are present including the Suisun marsh aster, soft birds beak and delta tule pea (see Sheet C-2 in Appendix D)

The ditches are narrow ranging from approximately 2 feet to 5 feet (Appendix E). Water depth varies with the tide and water depths can be up to approximately 4 feet. The main slough is wider, ranging from 8 to 12 feet, and water depths can be up to 5 feet. The bottom of ditches and slough beds are soft and easily disturbed. A person attempting to stand in the channels will sink as much as 2 feet into the sediment in softer portions of the ditches and sloughs. Uneven loading of the softer sediments is therefore expected to be highly disturbing to the ditch and slough bottom resulting in an uneven surface. As a result, cap Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

24

placement techniques must be gradual and uniform to avoid undue mixing of existing sediment layers, uneven foundation conditions, and subsequent irregularities in the cap thickness or surface elevation. Much of the site is covered with thick vegetation growing up to the slough and ditch edges. This thick vegetation makes it difficult to access the site and also makes it difficult to see the slough and ditches, resulting in a trip and fall hazard. Some ditches within the remediation area are shallow (less than 12 inches deep), and most of these areas are heavily overgrown with plants. The shallow depth of these ditches and plant growth are the result of active sediment accretion. These ditches do not warrant installation of an in situ cap since they are similar in elevation to the marsh plain, are covered with plants that slow tidal velocities, and are expected to continue to accrete sediment rapidly as a result of the subdued tidal flows. The placement methodologies presented in this report are intended to minimize impacts during placement of the cap. This design includes the following:

4.2

•

Minimized foot traffic to avoid disturbance of the sediments in the sloughs and ditches.

•

Minimized disturbance to the marsh plain and sensitive species by limiting access to defined paths cleared of vegetation and the use of only foot traffic. The access pathways illustrated on Sheet C-2 (Appendix D) were located to avoid sensitive plant species. LAYDOWN AREA, ACCESS, AND CONSTRUCTION EQUIPMENT USAGE

Two laydown areas shown on Sheet C-1 (Appendix D) are located near Site 32 and 33 to provide field support and material storage. One laydown/staging area is located at Stevens Road and White Road and will be used as the main staging area where the project trailer will be located. This area will also be used to receive and store equipment and material. The other parking area is located in the southeast corner of the Litigation Area and will be used for parking and for staging personnel and equipment near the work zone. To minimize disturbance to the sensitive habitat of the marsh plain, no trucks or heavy construction equipment will be used. Instead, the cap material will be staged off site and transported to the staging are in the southeast corner of the Litigation Area by helicopter guided by field personnel, as described in Section 4.3. 4.3

PLACEMENT AND CONSTRUCTION METHODS

The cap material consists of Bay Mud dredged from Martinez Marina. No heavy equipment will be used to place or spread the cap materials. Instead, the entire cap within Site 32 and 33 will be constructed by hand placement of woven polypropylene bags filled with Bay Mud. The filled bags will be placed on a geotextile fabric in the slough to provide a more stable surface. A Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

25

helicopter will transport the bags from the project staging area to the sides of the ditches or sloughs where each bag will then be placed by hand on the contaminated sediment surface until the entire area requiring a surface cap is covered with a uniform layer of bagged Bay Mud to the design thickness. Using bags filled with Bay Mud has the following advantages:

4.3.1

•

Provides a manual method of placing the cap material without using heavy construction equipment.

•

Provides a stable container that holds the Bay Mud in pace during placement.

•

The bags are not ultraviolet stable, so the upper surface of the bags are expected to degrade and leave an exposed Bay Mud cap surface.

•

Polypropylene is nontoxic (polypropylene is used to store food products and is also commonly used for surface water control at construction sites). Processing of Bay Mud Material

The bags will be woven polypropylene bags with approximate dimensions of 24 inches by 12 inches, 4 inches thick, and weighing approximately 50 pounds. The Bay Mud fill will be tilled and air dried at the dredge spoil pond site at the Martinez Marina until the clay is broken up into well-graded particles. The particle size and moisture content will be within a range that allows easy loading of the material into the bags. Once processed, the Bay Mud will be loaded into a hopper connected to a bag filling machine. The bag filling machine will fill, close, and discharge bags containing the tilled Bay Mud. The filled bags will be transported by truck to the staging area at the intersection of Stevens Road and White Road. 4.3.2

Placement of Cap Material

The helicopter will use a cargo net to move the bags from the staging area at the intersection of Stevens Road and White Road to the ditches and slough. The helicopter will lower the cargo net into the ditches and slough or along the sides as needed for placement of the cap. The bags will be manually placed within the slough and ditches. Before individual bags are set in the slough, a temporary sheet pile dam will be constructed in the slough downstream of the cap area near Trestle Road (Sheet C-2, Appendix D). The water level in the slough will be lowered to expose the slough bottom by pumping the water out of the slough and discharging the water downstream of the sheet pile dam. A 12-ounce non-woven geotextile fabric will be placed along the bottom of the slough to provide a stable working surface for the field personnel and create a more stable surface for the cap. The geotextile is also expected to limit the development of mud waves when the cap material is placed. 4.3.3

Survey Plates

Survey plates will be installed at the locations shown in Sheets C-3 and C-4 (Appendix D) and be used to monitor cap thickness immediately after construction and during the long-term monitoring, as described in Section 5.0. A typical survey plate detail is shown in Sheet C-5 Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

26

(Appendix D). The elevation of the bottom of the plate and top of the riser pipe will be recorded to establish a baseline reading. In addition, the top riser pipe and the top of the fill elevation will be recorded and marked on the riser pipe with a brass tag after a minimum waiting period of 3 weeks to allow consolidation settlement to occur. The survey will use a fixed datum or benchmark outside of the cap area. The location of the plates and baseline readings will be surveyed and recorded on a survey drawing of the site. 4.3.4

Field Control

Before the bags are put in place, the cap areas will be surveyed and staked to control placement of the bags over the remediation area. Cap design thickness will be achieved with a 4-inch bag placed in two rows for the 8-inch thick cap sections in Site 32 and the east and west tributaries at Site 33 (Sheets C-3 and C-4, Appendix D). Cap design thickness will be achieved with a 4-inch bag placed in three rows for the 12-inch-thick cap in the main channel of Site 33 (Sheets C-3 and C-4, Appendix D). Ground crews and surveyors will verify that a sufficient quantity of material is placed in each stretch of the slough to achieve the design thickness of the cap. Site ground crews will be used for horizontal control of sections of the cap during placement. Grid markers or other means will be used to assure uniform placement of cap materials. Placement thickness will be controlled by field quality control. Verification that the cap is the proper design thickness will be assured by measuring representative bags at Martinez Marina during the filling process and tracking the number of layers placed. The lateral limits of the cap sections will be surveyed. Additional cap thickness verification and monitoring are described in Section 5.0. The cap thickness will also be verified daily during placement by the quality control supervisor measuring the cap thickness from the bottom of the bags to the top of the bags. A quality control tracking record will be maintained to verify that the bags were adequately placed. 4.4

MINIMIZING ECOLOGICAL IMPACTS

The construction methods are intended to minimize impacts to the sensitive ecology of the site including: •

Access pathways will be routed under the guidance of appropriately qualified biologist or botanist.

•

Vegetation will be cleared by hand and will be limited to the minimum necessary for safe worker and equipment access.

•

Pickleweed (habitat for the federally-listed salt marsh harvest mouse) will be left undisturbed.

•

Once pathways are established, all foot traffic to and from work areas will be restricted to the paths to prevent harm to the salt marsh harvest mouse and the sensitive plant species.


27

•

4.5

Construction will occur outside the California black rail nesting season of February through the end of August unless a nesting survey indicates that all black rails have fledged their nests within 300 feet of all construction and traffic areas.

CAP PLACEMENT CONSTRUCTION SEQUENCE

Figure 11 provides a general sequence of the remedial construction of the cap. During the 2012 construction season, the cap will be placed within Site 32; during the 2013 construction season the cap will be placed within Site 33. The short construction season does not allow completion of the cap in a single season at both sites. The first construction activities are mobilization of equipment and personnel and establishing laydown and staging areas. Initial activities also include preparing the Bay Mud materials at the Martinez Marina borrow source and filling the bags. Another early activity will be establishing footpaths to provide access to the site. Once the bags are filled, they will be transported by truck to the staging area on Nichols Road. The helicopter will transport bundles of bags to locations beside and in the ditch at Site 32. The cap will be constructed by hand placement of bags in the ditches. The initial post-construction monitoring will be conducted 3 weeks after cap completion (see monitoring description in Section 5.0) to allow for cap consolidation. Once the cap is complete, the equipment and personnel will demobilize until the next construction season, and the process will be repeated in Site 33. The sequence at Site 33 is similar, with the exception that the sheet pile dam will be constructed after mobilization to facilitate access to the slough and stabilize the working surface for placement of the Bay Mud filled bags. 5.0

POST-CONSTRUCTION CAP MONITORING AND MAINTENANCE

This section discusses cap monitoring and maintenance requirements after construction. A sampling and analysis plan will be prepared as part of the remedial action to describe specific field procedures and quality control. 5.1

MONITORING REQUIREMENTS

Post-construction monitoring the cap will include physical monitoring and analytical monitoring for metals. Physical monitoring encompasses measuring the thickness of the cap to verify that an adequate layer of cap is in place to isolate the underlying contaminated sediments. Analytical monitoring encompasses sampling the cap materials and analyzing the samples for metals. 5.1.1

Physical Monitoring

Physical monitoring will first be performed 3 weeks after construction of the cap is complete. Physical monitoring will be repeated annually for 5 years and at 5-year intervals thereafter. Physical monitoring will include measuring the elevation of the base of the cap and the elevation of the cap surface. The base elevation of the cap is measured nondestructively by recording the elevation of the survey plate riser and subtracting the height of the riser. The surface elevation of the cap is measured 2 feet upstream of each survey plate on the surface of the cap. Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

28

Physical monitoring will be conducted at each of the 16 survey plates on Sheets C-3 and C-4 of the design drawings in Appendix D. Details regarding the construction of the survey plates are illustrated in Sheet C-5. The horizontal location and elevation of each survey plate will be established by a land surveyor to the nearest 0.05 foot horizontally and 0.01 foot vertically. The initial measurement will be considered the baseline reading, and all subsequent measurements will be compared with the baseline reading. The elevation of the cap top surface also will be measured 3 weeks after the cap is complete, and this measurement will also be considered a baseline reading that will be used for comparison with all subsequent readings. The initial measurement and all subsequent readings will be recorded using the same technique, as follows: 1. The cap top surface will be probed using a 1-foot-diameter rigid light-weight plate mounted at the end of a pole. 2. The pole will be probed through the water column until the first sign of resistance is noted on the top of the cap. 3. The elevation of the cap top surface will be recorded at that point. Annually after the first reading for 5 years and every 5 years thereafter, the elevation of the survey plate and cap top surface will be recorded and compared with the baseline measurements to determine (1) the thickness of the cap, (2) cap accretion or erosion since the baseline readings, and (3) overall settlement of the cap since the baseline readings. 5.1.2

Analytical Monitoring

Chemical monitoring will be performed to evaluate: (1) if off-site contamination is migrating on site, and (2) if the underlying contamination is breaking through the cap. Annually for the first 5 years and every 5 years thereafter, one sediment sample will be collected from the top 2 inches of sediment adjacent to each survey plate. The sediment sample will be located 2 feet downstream of each survey plate. Each sediment sample will be analyzed for arsenic, cadmium, copper, lead, mercury, selenium, and zinc. If the analytical results suggest that off-site contamination or cap breakthrough is occurring, a more detailed sampling program may be necessary to identify the contaminant source (from breakthrough or off-site sources). Possible mechanisms for off-site recontamination of the cap include erosion from contaminated slough sidewalls or from the contaminated marsh surface or from sources outside RASS 1. 5.2

MAINTENANCE

Erosion of the cap or accretion will be evaluated at the test section locations during the 5-year reviews based on cap thickness measurements and chemical analysis of sediment. If the cap does not meet remedial action objectives, additional remedial actions will be evaluated in a supplemental feasibility study. Remedial Design Report for In-situ Cap Sites 32 and 33, MOTCO

29

6.0

REFERENCES

California Native Plant Society. 2009. California Native Plant Ranking System. Available online at: http://www.cnps.org/cnps/rareplants/ranking.php CH2MHill. 2000. “Draft Honeywell Bay Point Property Phase II Work Plan.” August. Clarke, D.G., Palermo, M.R., and Sturgis, T.C. 2001. “Subaqueous cap design: Selection of bioturbation profiles, depths, and rates.” DOER Technical Notes Collection. ERDC TN-DOER-C21. U.S. Army Engineer Research and Development Center. Vicksburg, Mississippi. www.wes.army.mil/el/dots/doer Cooper, White, and Cooper, LLP. 2000. Letter Regarding Interim Corrective Action Measures for Former Chemical and Pigment Company Facility. From Cooper, White, and Cooper, LLP to Mohinder S. Sanhu, P.E., Chief Standardized Permits and Corrective Action Branch. March 10. Cullinane, M.J., C.R. Lee, and L.J. O'Neill. 1988. “Feasibility Study of Contamination Remediation at Naval Weapons Station, Concord, California.” Volume I. Miscellaneous Paper EL-86-3. U.S. Department of the Army, Waterways Experiment Station, Corps of Engineers. September. Department of Toxic Substances Control (DTSC). 1999. Letter regarding the Withdrawal of the Standardized Hazardous Waste Facility Permit Application, Series A, CAD 009 159 476. From Mohinder S. Sandhu, P.E., Chief Standardized Permits and Corrective Action Branch, DTSC. To Robert G. Knox, III, President, Chemical and Pigment Company. June 8. DTSC. 2000a. Letter regarding Removal of Hazardous Waste and Potentially Hazardous Waste from Chemical and Pigment Company. From Mohinder S. Sandhu, P.E., Chief Standardized Permits and Corrective Action Branch, DTSC, to Keith Howard, Esq., Cooper, White, and Cooper, LLP. March 15 DTSC. 2000b. Letter regarding the Transfer of Chemical and Pigment Company for Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Remedial Action. From Mohinder S. Sandhu, P.E., Chief Standardized Permits and Corrective Action Branch, DTSC. To Barbara Cook, P.E., Chief Site Mitigation Branch. July 10. DTSC. 2003. “Final Interim Remedial Measures Plan, Chemical and Pigment Company, Bay Point, California.” June 30. DTSC. 2010. “Responsiveness Summary. Public Comments Received on the Draft Remedial Action Plan and Draft Negative Declaration for the Chemical and Pigment Company Site.” July 13.


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Engineering/Remediation Resources Group, Inc. (ERRG). 2004. “Implementation Report, Chemical and Pigment Company, Removal and Stabilization, Bay Point, California.” Prepared for DTSC. ERRG Project No. 22-093.” February. ERRG. 2012. “Remediation Work Plan, Chemical and Pigment Company, Former Plant Area and Nicholls Creek (Operable Units 1 and 2), 600 Nicholls Road, Bay Point, California.” Prepared for DTSC. ERRG Project No. 2010-179. May. Groundwater Technology, Inc. 1995. “Final Resource Conservation and Recovery Act Facility Investigation Report, General Chemical Corporation Bay Point Works Facility, 50 I Nichols Road, Pittsburg, California.” EPA 009142290. October 30. PRC Environmental Management Inc. (PRC). 1994. “Draft Baseline Conditions Report, Litigation Area Sites, Naval Weapons Station, Concord, California.” February 14. PRC. 1996. “After Remediation (Year 1) Draft Remedial Action Monitoring Report, Litigation Area, Naval Weapons Station, Concord, California.” May 31. PRC. 1997. “Qualitative Ecological Assessment, Litigation Area, Naval Weapons Station, Concord, California.” September 2. SulTech. 2006. “Treatability Study Litigation Area Report, Naval Weapons Station, Seal Beach Detachment Concord.” January. Tetra Tech EM Inc. (Tetra Tech). 2003. “Final 5-Year Periodic Review Assessment Litigation Area, Naval Weapons Station, Seal Beach Detachment Concord.” June 30. Tetra Tech. 2008. “Final Year 3 Revised Post-Remediation Monitoring Program, Technical Memorandum, Litigation Area Naval Weapons Station Seal Beach Detachment Concord, Concord, California.” August 17. Tetra Tech. 2010. “Technical Memorandum, Pre-Remedial Design Field Investigation at Sites 32 and 33, Litigation Area, Military Ocean Terminal Concord, Concord, California.” February 22. Tetra Tech. 2011. “Final Supplemental Feasibility Study Addendum, Military Ocean Terminal Concord, Concord, California.” May. Tetra Tech. 2012. “Draft Final Amended Record of Decision Litigation Area Sites 32 and 33, Military Ocean Terminal Concord, Concord, California.” June. U.S. Environmental Protection Agency (EPA). 2005. “Contaminated Sediment Remediation Guidance for Hazardous Waste.” EPA-540-R-05-012. OSWER 9355.0-85. December. Regional Water Quality Control Board (Water Board). 2010. San Francisco Basin Plan. Available on-line at: http://www.swrcb.ca.gov/rwqcb2/basin_planning.shtml


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FIGURES

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Suisun Bay

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Site 32

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Site 32 MOTCO

Site 33

Military Ocean Terminal Concord

4

FIGURE 1 MOTCO LOCATION Remedial Design Report

2011-03-23

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FIGURE 2 SITE 32 AND SITE 33 LOCATIONS Remedial Design Report

2011-03-23

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Area Requiring Remediation Under Agreed Do-Not-Exceed Criteria and 2009 Sample Results 0

Aditional Area Requiring Remediation to Meet Target Average Using 2009 Sample Results

200

400

Feet


Area Requiring Remediation Using 1999 Sample Results Note: Labels indicate the chemical(s) driving remediation of each area. Those in (parenthesis) are based on 1999 sample results; all others are based on 2009 sampling results.

Area Not Requiring Remediation Water (Outside Model)

FIGURE 3 REMEDIATION FOOTPRINT FOR SITES 32 AND 33 Remedial Design Report

2011-05-03

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Site 33

2 Si t e 3

Round 2: Dec. 1992 - Mar. 1997 48 Samples

Round 1: Aug. - Sept. 1995 28 Samples

Arsenic Results Detection < Target Area Weighted Average RG Detection ≥ Target Area Weighted Average RG and ≤ Discrete Do-Not-Exceed RG Detection > Discrete Do-Not-Exceed RG

Round 4: June - July 1998 49 Samples

Round 3: May - June 1997 49 Samples

Site 32 Arsenic Remediation Goals: 689 mg/kg - Target Area Weighted Average 1380 mg/kg - Discrete Do-Not-Exceed Site 33 Arsenic Remediation Goals: 603 mg/kg - Target Area Weighted Average 1200 mg/kg - Discrete Do-Not-Exceed

Notes: All samples were collected from 0.0 to 0.5 feet bgs except the Treatability Study (2005), which was collected from 0.0 to 1.0 foot bgs. bgs below ground surface mg/kg milligrams per kilogram


Data Gaps Sampling: 2000 9 Samples

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Treatability Study: 2005 14 Samples 2011-05-12

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Pre-Remedial Design Field Investigation: October 2009 109 Surface Samples TtEMI-OAK

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FIGURE 4 ARSENIC CONCENTRATIONS IN SEDIMENT SITES 32 AND 33 Remedial Design Report

Site 33

2 Si t e 3



Cadmium Results Detection < Target Area Weighted Average RG Detection ≥ Target Area Weighted Average RG and ≤ Discrete Do-Not-Exceed RG Detection > Discrete Do-Not-Exceed RG



Site 32 Cadmium Remediation Goals: 12.2 mg/kg - Target Area Weighted Average 124 mg/kg - Discrete Do-Not-Exceed Site 33 Cadmium Remediation Goals: 10.7 mg/kg - Target Area Weighted Average 120 mg/kg - Discrete Do-Not-Exceed




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FIGURE 5 CADMIUM CONCENTRATIONS IN SEDIMENT SITES 32 AND 33 Remedial Design Report

Site 33

2 Si t e 3



Copper Results Detection < Target Area Weighted Average RG Detection ≥ Target Area Weighted Average RG and ≤ Discrete Do-Not-Exceed RG Detection > Discrete Do-Not-Exceed RG



Site 32 Copper Remediation Goals: 111 mg/kg - Target Area Weighted Average 200 mg/kg - Discrete Do-Not-Exceed Site 33 Copper Remediation Goals: 96.7 mg/kg - Target Area Weighted Average 139 mg/kg - Discrete Do-Not-Exceed




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FIGURE 6 COPPER CONCENTRATIONS IN SEDIMENT AT SITES 32 AND 33 Remedial Design Report

Site 33

2 Si t e 3



Lead Results Detection < Target Area Weighted Average RG Detection ≥ Target Area Weighted Average RG and ≤ Discrete Do-Not-Exceed RG Detection > Discrete Do-Not-Exceed RG



Site 32 Lead Remediation Goals: 95 mg/kg - Target Area Weighted Average 553 mg/kg - Discrete Do-Not-Exceed Site 33 Lead Remediation Goals: 95 mg/kg - Target Area Weighted Average 484 mg/kg - Discrete Do-Not-Exceed




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FIGURE 7 LEAD CONCENTRATIONS IN SEDIMENT SITES 32 AND 33 Remedial Design Report

Site 33

2 Si t e 3

Mercury Results Detection < Target Area Weighted Average RG Detection ≥ Target Area Weighted Average RG and ≤ Discrete Do-Not-Exceed RG

Pre-Remedial Design Field Investigation: 1995 13 Samples

Pre-Remedial Design Field Investigation: October 2000 7 Samples

Site 32 Arsenic Remediation Goals: 2.98 mg/kg - Target Area Weighted Average 6.89 mg/kg - Discrete Do-Not-Exceed Site 33 Arsenic Remediation Goals: 2.62 mg/kg - Target Area Weighted Average 6.03 mg/kg - Discrete Do-Not-Exceed

Note: mg/kg milligrams per kilogram

0

500

1,000

1,500

Feet

Pre-Remedial Design Field Investigation: July 2005 14 Surface Samples

2011-05-12

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Pre-Remedial Design Field Investigation: October 2009 109 Samples

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FIGURE 8 MERCURY CONCENTRATIONS IN SEDIMENT SITES 32 AND 33 5HPHGLDO'HVLJQ5HSRUW

Site 33


2 Si t e 3


Selenium Results Detection < Target Area Weighted Average RG Detection ≥ Target Area Weighted Average RG and ≤ Discrete Do-Not-Exceed RG Detection > Discrete Do-Not-Exceed RG



Site 32 Selenium Remediation Goals: 12 mg/kg - Target Area Weighted Average 24.19 mg/kg - Discrete Do-Not-Exceed Site 33 Selenium Remediation Goals: 16.1 mg/kg - Target Area Weighted Average 28.3 mg/kg - Discrete Do-Not-Exceed

Notes: 1) No analytes detected in samples above the Discrete Do-Not-Exceed Remediation Goal 2) All samples were collected from 0.0 to 0.5 feet bgs except the Treatability Study (2005), which was collected from 0.0 to 1.0 foot bgs.



bgs below ground surface mg/kg milligrams per kilogram

0

500

1,000

1,500

Feet



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FIGURE 9 SELENIUM CONCENTRATIONS IN SEDIMENT SITES 32 AND 33 Remedial Design Report

Site 33

2 Si t e 3



Zinc Detections Detection < Target Area Weighted Average RG Detection ≥ Target Area Weighted Average RG and ≤ Discrete Do-Not-Exceed RG Detection > Discrete Do-Not-Exceed RG



Site 32 Zinc Remediation Goals: 2420 mg/kg - Target Area Weighted Average 12100 mg/kg - Discrete Do-Not-Exceed Site 33 Zinc Remediation Goals: 2110 mg/kg - Target Area Weighted Average 10600 mg/kg - Discrete Do-Not-Exceed




0

500

1,000

1,500

Feet


Pre-Remedial Design Field Investigation: October 2009 109 Surface Samples


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FIGURE 10 ZINC CONCENTRATIONS IN SEDIMENT SITES 32 AND 33 Remedial Design Report


FIGURE 11 CONSTRUCTION SEQUENCE FOR SITE 32 AND SITE 33 Remedial Design Report 2012-07-18

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APPENDIX A TREATABILITY STUDY AND CAP EFFECTIVENESS MODELING

TABLE OF CONTENTS ACRONYMS AND ABBREVIATIONS ................................................................................... A-v A1.0

INTRODUCTION ....................................................................................................... A-1 A1.1 A1.2

BACKGROUND ................................................................................................ A-1 PURPOSE OF TESTING ..................................................................................... A-1

A2.0

SAMPLES TESTED.................................................................................................... A-2

A3.0

TEST RESULTS .......................................................................................................... A-8 A3.1

A3.2

A3.3

A3.4

A3.5

A3.6

A3.7

A4.0

SUMMARY ............................................................................................................... A-47 A4.1 A4.2

A5.0

CHARACTERISTICS OF SURFACE WATER AND CAP MATERIALS ..................... A-8 A3.1.1 Test Procedure ............................................................................... A-8 A3.1.2 Results ............................................................................................ A-9 TOTAL METAL CONCENTRATIONS IN SEDIMENT AND PORE WATER ............ A-14 A3.2.1 Test Procedure ............................................................................. A-14 A3.2.2 Results .......................................................................................... A-15 BATCH SORPTION CAPACITY TESTS ............................................................. A-15 A3.3.1 Sorption Isotherm Test Procedure ............................................... A-19 A3.3.2 Results .......................................................................................... A-20 LEACHING TESTS OF CAP MATERIALS ......................................................... A-25 A3.4.1 Batch Leaching Test Procedure ................................................... A-25 A3.4.2 Results .......................................................................................... A-25 DESORPTION OF CONTAMINANTS FROM CAP MATERIALS ............................ A-27 A3.5.1 Desorption Test Procedure ........................................................... A-27 A3.5.2 Results .......................................................................................... A-28 A3.5.3 Effect of pH on Desorption .......................................................... A-33 SETTLING VELOCITY .................................................................................... A-33 A3.6.1 Test Procedure ............................................................................. A-34 A3.6.2 Results .......................................................................................... A-35 CHEMICAL FLUX MODEL ............................................................................. A-37 A3.7.1 Introduction .................................................................................. A-37 A3.7.2 Transport Model........................................................................... A-38 A3.7.3 Model Conclusions ...................................................................... A-42

CAP PERFORMANCE AGAINST DQOS ........................................................... A-48 SELECTION OF CAP MATERIAL..................................................................... A-49

REFERENCES .......................................................................................................... A-51

Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-i

FIGURES Figure A-1

Treatability Study Process Flow Diagram .......................................................... A-3

Figure A-2

Site 32 Sediment Sample Locations ................................................................... A-4

Figure A-3

Site 32 Sediment Sample Locations ................................................................... A-5

Figure A-4a

Water Quality Parameters at Various Depths ................................................... A-11

Figure A-4b

Changes in DO and ORP at Various Depths .................................................... A-11

Figure A-5

Particle Size Distribution of Selected Cap Materials........................................ A-13

Figure A-6

Total Metal and Pore Water Concentrations in the Grab Sediments from Sites 32 and 33 ......................................................................................... A-18

Figure A-7

Sorption Isotherms of Copper on Sediments from Sites 32 and 33 .................. A-21

Figure A-8

Sorption Isotherms of Arsenic on Sediments from Sites 32 and 33 ................. A-21

Figure A-9

Sorption Isotherms of Copper on Selected Cap Materials ................................ A-22

Figure A-10

Sorption Isotherms of Arsenic on Selected Cap Materials ............................... A-22

Figure A-11

Concentrations of Total Metals and DI-WET Metals in the Cap Materials .................................................................................................... A-26

Figure A-12

Comparison of Metals Leached in DI-WET and Water Quality Screening Criteria ............................................................................................. A-27

Figure A-13

Release of As from Various Cap Materials in the Presence of Sediments from Sites 32 and 33 ......................................................................................... A-31

Figure A-14

Percent As Desorbed from Sites 32 and 33 Sediments and Cap Materials ...... A-32

Figure A-15

Equilibrium pH of Sediments and Cap Materials ............................................. A-33

Figure A-16

Attainment of Terminal Velocity by a Cap Material When Dropped from Rest in a Cylinder Containing Site-Specific Water.................................. A-35

Figure A-17

(a) Dispersed Sediment at the Beginning of the Test, and (b) Settled Solids After 10 Days ....................................................................... A-36

Figure A-18

Settling Velocities at Various Particle Sizes of Cap Materials ......................... A-37

Figure A-19

Mass Flux of Copper Through the Sediment and Bay Mud Cap Material ....... A-40


A-ii

FIGURES (CONTINUED) Figure A-20

Copper Concentrations in Sediments from Sites 32 and 33 at Various Shallow Locations ............................................................................... A-41

Figure A-21

Flux of Copper Through Bay Mud at Various Cap Thickness at Site 32 ......... A-43

Figure A-22

Flux of Copper Through Bay Mud at Various Cap Thickness at Site 33 ......... A-44

Figure A-23

Flux of Copper Through Various Cap Materials for Site 32 at Average Copper Loadings and Seepage Velocity 10 cm/year......................... A-45

Figure A-24

Flux of Copper through Various Cap Materials for Site 33 at Average Copper Loadings and Seepage Velocity 10 cm/year......................... A-46


A-iii

TABLES Table A-1. Surface Water Quality Field Parameters ............................................................... A-10 Table A-2. Physical Characteristics of Cap Materials ............................................................. A-12 Table A-3. Martinez Marina Bay Mud Chemical Data ........................................................... A-16 Table A-4. Grab Sediments Pore Water Data from Sites 32 and 33........................................ A-19 Table A-5. Partitioning Coefficient (Kd) of Copper on Sediments and Cap Materials Using Site-Specific Water.......................................................................................... A-23 Table A-6. Partitioning Coefficient (Kd) of Arsenic on Sediments and Cap Materials .......... A-24 Table A-7. Metal Concentrations after Equilibration of Sediments and Cap Materials in DI Water ................................................................................................................ A-30

ATTACHMENTS A1

X-ray Diffraction of Cap Materials for Military Ocean Terminal Concord (MOTCO) Sites 32 and 33Lost Slough Channel Velocity Determination


A-iv

ACRONYMS AND ABBREVIATIONS ºC ρ ρp µg/L µS/cm2 ut

Degree Celsius Density of surrounding fluid Density of particle Micrograms per liter Micro-Siemens per square centimeter Terminal velocity

AIS Ap ASTM AWQC

American Integrated Services, Inc. Projected area of the particle in direction of motion American Society for Testing and Materials (now ASTM International) Ambient Water Quality Criteria

CVAA Cc Cu

Cold Vapor Atomic Absorption Coefficient of gradation Uniformity coefficient

D10 D30 D60 DI DO DQO DTSC

Diameter corresponding to 10 percent finer in particle-size distribution Diameter corresponding to 30 percent finer in particle-size distribution Diameter corresponding to 60 percent finer in particle-size distribution Deionized Dissolved oxygen Data quality objective Department of Toxic Substances Control

EPA

U.S. Environmental Protection Agency

g gm

Acceleration due to gravity Gram

ICP-MS

Inductively Coupled Plasma-Mass Spectrometry

L/kg

Liter/kilogram

mg/kg mg/L mL mg/m2/yr MOTCO mp mV

Milligram per kilogram Milligrams per liter Milliliter Milligrams per square meter per year Military Ocean Terminal Concord Mass of particle Millivolts


A-v

ACRONYMS AND ABBREVIAITONS (Continued) NRe NTU

Particle Reynolds numbers Nephelometric turbidity unit

ORP

Oxidation-reduction potential

PET ppt

Polyethylene terephthalate Parts per thousand

RCF RPM

Relative centrifugal force Rotations per minute

SVOC

Semivolatile organic compounds

TAL TCLP Tetra Tech TOC

Target analyte list Toxicity characteristic leaching procedure Tetra Tech EM Inc. Total organic carbon

UCL95

95% upper confidence limit

USACE

U.S. Army Corps of Engineers

VOCs

Volatile organic compounds

Water Board San Francisco Bay Regional Water Quality Control Board WET Waste Extraction Test XRD

X -ray diffraction


A-vi

A1.0 INTRODUCTION A1.1

BACKGROUND

The U.S. Army Corps of Engineers (USACE) tasked American Integrated Services, Inc. (AIS), to prepare treatability tests to evaluate the effectiveness of local and commercially available passive and active materials as a cap for contaminated sediment at Installation Restoration Program Sites 32 and 33 located at Military Ocean Terminal Concord (MOTCO) in Concord, California. Tetra Tech EM Inc. (Tetra Tech), as a subcontractor to AIS, prepared a work plan (AIS 2011) describing the sampling procedures and analytical methods required to evaluate these potential cap materials to sequester contaminants present in Sites 32 and 33 sediments. Sediment and water samples were collected during August and September 2011. Routine chemical and geotechnical analyses were performed by Curtis & Tompkins Laboratories in Berkeley, California, and Cooper Testing Laboratory in Palo Alto, California. The sorption and desorption testing and analyses were conducted by DHL Analytical in Round Rock, Texas. The pore water samples were extracted by Pacific EcoRisk in Fairfield, California. X-ray diffraction (XRD) analysis of the cap materials was performed by Ohio State University in Columbus, Ohio; the results are presented in Attachment A1. This report summarizes the results of the treatability tests performed under site-specific conditions using water and sediment samples collected from Site 32 and 33. A1.2

PURPOSE OF TESTING

The objective of the treatability study was to assess the effectiveness of various cap materials to provide long-term protection of the environment. A series of tests were conducted to evaluate physical and chemical characteristics of the following potential cap materials: • • • • •

Bay Mud from the Martinez Marina borrow source (Bay Mud) Aggregate gravel coated with modified clay (AquaGate) Macroporous Aluminosilicate Mineral apatite (Rock Phosphate) Fishbone product (Apatite II)

The cap materials were analyzed using the following tests: •

Moisture content, specific gravity, grain size, total organic carbon (TOC) and XRD

•

Leachable metals, volatile organic carbons (VOCs) and semivolatile organic compounds (SVOCs) to evaluate the potential for each material to leach metal and organic contaminants

•

Sorption tests to determine the arsenic and copper sorption capacity of each of the potential cap materials


A-1

•

Desorption of various metals (aluminum, antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, molybdenum, nickel, selenium, silver, thallium, vanadium, and zinc) in the presence of contaminated sediment to assess the potential release of contaminants by the cap materials

•

Settling velocities of selected cap materials in site-specific water.

The sediment and surface water samples collected from Sites 32 and 33 were analyzed for physical and chemical characteristics. The surface water samples were analyzed for temperature in degrees Celsius (ºC), pH, conductivity in micro-Siemens per square centimeter, (µS/cm2), oxidationreduction potential (ORP) in millivolts (mV), dissolved oxygen (DO) concentration in milligrams per liter (mg/L), and turbidity in nephelometric turbidity units (NTU). Pore waters were extracted from the sediment samples. Sediment, pore water, and cap material samples were analyzed for eight metals as indicated before. In addition, the sediment samples were analyzed for the sorption capacity with respect to arsenic and copper. Figure A-1 shows the design of treatability study and the sequence of tests. A2.0 SAMPLES TESTED Sediment and surface water samples from Sites 32 and 33 and four types of cap materials were tested. The sediment samples were collected from the locations that historically contained high concentrations of metals (Figures A-2 and A-3). In addition to sampling for sediment texture (clay, sand, silt, and organic composition), efforts were made during field sampling not to dilute the metal concentrations with cleaner sediments. Sediment samples were collected during low tide to minimize disturbance to the sediment surface and suspension of contaminated sediment in the ditches. Samples from Site 32 were collected with a trowel, shovel, and bucket. The three sample locations from each site were first composited in the field and once again in the laboratories. In case of Site 33, the top 6 inches of sediment were collected from each of the composite sampling location using a Ponar grab sampler from a flat-bottomed boat. The sampler consists of a pair of weighted, tapered jaws held open by a catch tension bar across the top of the sampler. The upper portion of the jaws is covered with a metal screen and a rubber flap, allowing water to pass through the sampler during descent and reduce disturbance at the sediment-water interface. When the sampler touched the bottom of the slough, the tension rod was released and the jaws were closed to collect the sediment. A surface water sample was collected from a single representative site location to assess background water quality (electrolyte concentrations, TOC content, and alkalinity). The sample was collected using a pre-cleaned bailer and 2.5-gallon plastic containers. The sample was collected from shallower water to avoid water at the bottom of the water column, where the concentration of suspended materials particulate matter increases. Field water quality parameters, including temperature, ORP, DO, pH, turbidity, and conductivity, were recorded at various depths while these samples were collected. The samples were shipped to the laboratories and stored in controlled temperature room (4±2 ºC) for the treatability tests. Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-2

Analyze for Total Metals and Organics

Chemical Composition

Conduct Desorption Tests

Yes

Are metals leaching?

No

Are Concentration Less than Basin Plan Discharge Requirements?

Analyze for Leachable Metals Collect/Procure Cap Material Samples

4 Materials

Analyze for Geotechnical Properties

Material Removed from Consideration

No

Yes

Grain Size, % Moisture, Bulk Density, Organic Carbon

pH, ORP, Temperature, Turbidity Settling Velocity

Analyze Water Quality Parameters

Conduct Settling Test

pore water Contaminant Concentration

Collect Surface Water Samples

Single Sample

No

Is the settling velocity acceptable?

Yes Conduct Batch Sorption Isotherms

Spike water with Copper and Arsenic

Estimate Partitioning Coefficient (Kd)

Metal Concentrations Analyze for Total Metals

Collect Sediment Samples Extract Pore Water

Composite Sample from each Site

Existing Data on Geotechnical Properties

Existing Data on Pore water Chemistry

Analyze Pore Water for Total Metals

Conduct Chemical Flux Modeling

Evaluate Chemical Flux, Effective Cap Thickness, & Cap Life

Conduct X-Ray Diffraction

Recommended Cap Material

Remedial Design

Contaminant Concentration Sediment Partition Coefficient Check Sediment Partition Coefficient Check

Grain Size, % Moisture, Bulk Density, Organic Carbon

Contaminant Concentration

Gather Site Specific Data Existing Total and Leachable Metal Concentrations

Existing Groundwater , Surface Water and Tidal Data

Total and Leachable Chemical Composition

Groundwater Surcharge Rate, Current Flow, and Tidal Period and Wave Height


FIGURE A-1 TREATABILITY STUDY PROCESS FLOW DIAGRAM Treatability Study Work Plan


A-3

Site 32

UN IT 7 DI T C H

R01DH113

( !

( !

R01DH265

R01DH266

( !

Los t

Current Flow Path of Nichols Creek into RASS 1

RASS 1

gh Slou

G

Brid ge

Creek Enters Pond

Burli

ngt on

Uni on

Feet

Paci

oad

fic R ailr o ad

Culv

( !

2011 Site 32 Sample Location Site 32 (Unit 7 Mosquito Abatement) Boundary

Suisun Bay

Site 33

Site 33

MOTCO

Site Boundary

Site 32

Waterway Mosquito Ditch Railroad MOTCO RASS

2011-07-19

RASS 3 R ailr

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k

Nor th e rn S a nta Fe

ree

Site 3

300

Historical Flow Path of Nichols Creek into RASS 2

ls C

150

ific Ra ilr oad

cho Ni

0

RASS 2 P ac

G

Un io n

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A-4

Military Ocean Terminal Concord Remedial Action Subsite


FIGURE A-2 SITE 32 SEDIMENT SAMPLE LOCATIONS Treatability Study Work Plan

( !

R01SH058

( !

R01SH077

Site 33

Los t

Current Flow Path of Nichols Creek into RASS 1

RASS 1

gh Slou

G

Brid ge

Site 32

R01SH098

( !

Creek Enters Pond

ngt on

Nor th e rn S a nta

fic R ailr o ad

Culv

( !

2011 Site 33 Sample Location Site 32 (Unit 7 Mosquito Abatement) Boundary

Suisun Bay

Site 33

Site 33

MOTCO

Site 32

Waterway

Railroad MOTCO RASS v:\concord\projects\s32_s33\treatability_study\wp\site_33_sample_locs.mxd


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Site Boundary

Mosquito Ditch

2011-07-19

Paci

ailr o ad

k

Uni on

Feet

RASS 3 Fe R

ree

300

Historical Flow Path of Nichols Creek into RASS 2

ls C

150

ific Ra ilr oad

cho Ni

Burli

0

RASS 2 P ac

G

Un io n

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A-5

Military Ocean Terminal Concord Remedial Action Subsite

FIGURE A-3 SITE 33 SEDIMENT SAMPLE LOCATIONS Treatability Study Work Plan

Four types of cap materials were evaluated. •

Martinez Marina Bay Mud: An abundant supply of clay-rich sediment is available from the prior dredging of Martinez Marina. The recreational Martinez Marina accumulates sediment and requires periodic dredging. The Bay Mud is stored in two large containment cells adjacent to the marina. This material is referred to as Bay Mud in this report.

•

Aggregate Gravel Coated with Modified Clay: A commercially available pelletized composite product from AquaBlok, known as AquaGate+, was used. This cap material is manufactured as composite coated aggregate that resembles gravel. Particles are composed of a central stone aggregate core coated with a patented manufactured modified clay product containing bentonite. Two forms of this material were procured for testing. These included the granular composite material containing aggregate and powdered patented modified clay material. For either form, this material is referred to as AquaGate in this report. The active ingredient (powdered AquaGate) was used for testing the sorption and desorption capacities, whereas the geotechnical analyses were conducted using the composite aggregate mix.

•

Macroporous Aluminosilicate: Porous aluminosilicates (ceramic matrix composites) containing active surface functional moieties (a moiety is a part of a molecule that may include either whole functional groups or parts of functional groups as substructures) have shown significant sorption of copper in bench-scale studies. The porous structure provides significantly large reactive surface sites; moreover, porous aluminosilicates have higher permeabilities than conventional cap materials. Higher permeability and high sorption capacity are desirable properties for a cap material. This aluminosilicate bonded ceramic typically has more than 85 percent interconnected open porosity with much higher surface area than most other media. The surface area of the supporting structure depends on the composition and the processing conditions and varies between 2 to more than 350 square meters per gram (m2/gm). This material can be synthesized in a variety of shapes and sizes, ranging from granular to monoliths, with desired bulk density to provide flexibility for specific applications. Granular size fraction of this material was selected for this series of screening tests for higher surface area and ease of application.

•

Rock Phosphate (Mineral Apatite) and Biological Apatite (Apatite II): Two available commercial types of apatite were evaluated in this treatability study. The chemical nature of these two materials was expected to differ as a result of the difference in their sources (mineral rock versus biogenic origin).


A-6

In general, the apatite structure conforms to the class of materials with hexagonal crystal structure and the generic formula Me5(XO4)3Z, where Me = calcium, strontium, barium, cadmium, or lead; X= phosphorous, arsenic, vanadium, manganese, or chromium; and Z= hydroxides, fluorine, chlorine, or barium. The apatite family includes carbonate apatite, chlorapatite, fluorapatite, hydroxyapatite, and others. Apatite can be available in natural minerals, ranging from sand- to pebble-sized Rock Phosphates, or may be found in processed fish bones. Biologic apatite from processed fish bones (Apatite II) is reported to have the nominal composition Ca10-xNax(PO4)6-x(CO3)x(OH)2 (where x < 1) (Martinez and others 2006). Apatites can react with heavy metals through both surface sorption reactions and precipitation reactions. Generally, divalent metals such as cadmium, copper, nickel, and zinc undergo sorption to the hydroxyapatite (Ca5(PO4)3OH) surface at low metal cation concentrations, form solid solutions (such as (Me,Ca)5(PO4)3OH) at concentrations around metal apatite saturation, and pure metal precipitates on the hydroxyapatite surface at concentrations above metal precipitate form under high carbonate concentrations. Apatites are geochemically stable as they are the most common diagenic1 product of sedimentary accretion of phosphate in marine sediments and are found in a range of sediment conditions, including oxidized to moderately reducing (Eh = –270 mV). However, releases of bound arsenic by competitive anions have been reported as a result of anion exchange. A variety of competitive anions (such as phosphate, bicarbonate, sulfate, or silicate), caused by its similar structure and chemical nature, can replace arsenic from sediment surfaces; phosphate can release arsenic up to three orders of magnitude more than bicarbonate, sulfate, or silicate. Desorption tests were conducted with known quantities of potential cap materials in the presence of site-specific composite sediment and surface water to evaluate whether the phosphates would not mobilize or desorb bound arsenic from this site-specific native sediment. Two types of apatite were procured for the treatability tests: (1) Rock Phosphate (32 percent bone phosphate of lime, BPL) from PotashCorp, Northbrook, Illinois, and (2) Apatite II from PIMS-NW, Inc., Kennewick, Washington. The purity (percent apatite content) and specific composition of other ingredients in these materials were not available. The work plan (AIS 2011) includes only one form of apatite for the treatability tests but during the procurement stage, it was decided to evaluate both of the commercial apatite sources described above. Limited tests (sorption, desorption, and settling velocity) were conducted for Rock Phosphate to evaluate the impact of different types of apatite, while Apatite II was tested more extensively.

1

Diagenesis, the sum of chemical, physical, and biological processes, commonly transforms sediments into sedimentary rocks and results in chemical and mineralogical changes.


A-7

A3.0 TEST RESULTS This section discusses the test procedures and results from the various analyses conducted for the treatability study. The following tests were conducted and are discussed below: • • • • • • A3.1

Characteristics of Surface Water and Cap Materials Surface Water and Pore Water Concentrations in Sediment Batch Sorption Capacity Test Leaching Tests of Cap Materials Desorption of Contaminants from Cap Materials Settling Velocity CHARACTERISTICS OF SURFACE WATER AND CAP MATERIALS

Surface water quality parameters were monitored to characterize the surface water as part of the sorption isotherm study and to evaluate general water parameters. The physical characteristics of the various cap materials were used as input parameters for the chemical flux model and were also used to evaluate the inherent stability and suspension properties of each material. A3.1.1

Test Procedure

Surface water quality parameters at various depths were monitored using a handheld multi-parameter YSI Quality Meter (Model 650 MDS). The water quality sensors simultaneously measured pH, temperature, DO, conductivity, turbidity, water depth, and ORP. Cap materials were analyzed for the grain size, specific gravity, and moisture content. Grain size analysis was conducted by Cooper Testing Laboratory using ASTM International Method D422 (Standard Test Method for Particle-Size Analysis of Soils). This test method provides a quantitative determination of the distribution of particle sizes. The distribution of particle sizes larger than 75 micrometers (µm) (retained on the No. 200 sieve) was measured by sieving, while the distribution of particle sizes smaller than 75 µm was determined by a sedimentation process using a hydrometer. The specific gravity of each cap materials was analyzed using ASTM Method D 854m (Standard Test Methods for Specific Gravity of Soil Solids by Water Pycnometer). The moisture content of each cap material was analyzed by ASTM Method D2216 (Test Methods for Laboratory Determination of Water [Moisture] Content of Soil and Rock by Mass). Sieve, hydrometer, and hygroscopic moisture analysis were performed by standard laboratory equipment, including balances, stirring apparati, hydrometers, sedimentation cylinders, thermometers, sieves, water baths or constant-temperature rooms, beakers, and timing devices.


A-8

A3.1.2

Results

The in situ water quality field parameters are shown in Table A-1 and Figure A-4a. The water depths are measured from the water surface. The temperature varied from 20 ºC to 23.7 ºC at the surface and 19.0 ºC at the 4-foot sediment-water interface to 20.5 ºC at the 6-foot sediment-water interface. The in situ pH measurements of surface water showed variations between 6.7 (at Site 32, ditch 300 feet north of surface water sampling location R01DH265) and 7.26 (at Site 33, at the nexus of the tributary and slough surface water sampling location). The turbidity varied for various locations and depths ranging from 4.6 NTU to 29.1 NTU. The variations in pH and turbidity might be caused by the change in tidal inflow and outflow water and characteristics of local deposits of sediment materials. The DO and ORP values are correlated well at various water depths (Figure A-4b). The conductivity varied from 8,042 µS/cm2 to 9,239 µS/cm2, indicating higher salinity caused by the sea water. The moisture content of the Bay Mud cap material was 30.6 percent. The pH value of AquaGate was 6.9, Apatite II was 6.3, Macroporous Aluminosilicate was 6.4, and Bay Mud was 7.1.


A-9

TABLE A-1. SURFACE WATER QUALITY FIELD PARAMETERS Remedial Design, Sites 32 and 33, Litigation Area, Military Ocean Terminal Concord, Concord, California Temp

pH

Conductivity µS/cm

2

ORP

DO

Turbidity

mV

mg/L

NTU

Site

Location

Depth

ºC

Site 32

Ditch 300 feet north of R01DH265 (surface water sampling location)

0.5 foot

23.7

6.7

9239

276

8.32

6.6

Site 33

R01SH098

2 feet

19.33

7

8808

240.6

7.27

8.6

Site 33

R01SH098

4 feet (sed-water interface)

19.04

7.09

8232

243.5

5.48

10.7

Site 33

R01SH098

Surface

20

7.15

8107

222.4

7.12

15.4

Site 33

R01SH058

Surface

20.58

7.19

8422

259.3

7.13

17.1

Site 33

R01SH058

1.5 feet

20.49

7.16

8425

255.4

7.36

29.1

Site 33

Tributary/slough nexus (surface water sampling location)

Shallow

20.31

7.26

8042

269.4

7.81

4.6

Site 33


6 feet (sed-water interface)

20.46

7.21

8243

267

7.68

17.8

Site 33


3 feet

20.33

7.22

8061

264.8

8.16

7

Notes: ºC µS/cm2 DO mg/L

Degree Celsius MicroSiemens per square centimeter Dissolved oxygen Milligrams per liter

mV NTU ORP

Millivolt Nephelometric turbidity units Oxidation reduction potential

(1)

Surface water field parameters at Site 33 were collected between 1130 and 1400 on 22 August 2011.

(2)

Surface water field parameters at Site 32 were collected between 1230 and 1430 on 23 August 2011.

(3)

Tide Information st

nd

rd

th

1 Tide 2 Tide 3 Tide 4 tide Time/ Time/ Time/ Time/ Date Tide Height (ft) Tide Height (ft) Tide Height (ft) Tide Height (ft) 357 1020 1422 2019 8/22/11 0.9 3.3 2.2 4.9 503 1124 1535 2126 8/23/11 0.6 3.5 2.4 4.9 Tide heights are expressed in feet referenced to Mean lower Low Water Reference: Tide Table for Port of Chicago ft - Feet


A-10

9400

Temperature pH

9200

Turbidity

30

DO Conductivity

9000

25 8800 20 8600 15 8400 10

Conductivity (µS/cm2)

Temperature (oC)/pH/ Turbidity (NTU)/Dissolved Oxygen (mg/L)

35

8200

5

8000

a 0

7800 0

1

2

3

4

5

6

Water Depth from Surface (ft)

Figure A-4a Water Quality Parameters at Various Depths 10

300

250

Dissolved Oxygen (mg/L)

8 7

200

6 5

150

4 100

3

b

DO

2

ORP

50

1 0

0 0

1

2

3

4

5

Water Depth from Surface (ft)

Figure A-4b Changes in DO and ORP at Various Depths


A-11

6

Oxidation-Reduction Potential (mV)

9

The physical characteristics of the cap materials are shown in Table A-2 and Figure A-5. The results of the mechanical analysis (sieve and hydrometer analyses) are shown as particle size distribution curves. The percent finer than a sieve size is calculated as follows: Percent Finer than a Sieve Size = 100% - ∑{(weight of solids retained/total solid weight) x 100%} Three basic parameters are generally determined from the particle size distribution curves: (1) effective size, (2) uniformity coefficients, and (3) coefficients of gradation. The uniformity coefficient (CU) is calculated as the ratio of the diameter corresponding to 60 percent finer in particle-size distribution (D60) to the diameter corresponding 10 percent finer (D10). The coefficient of gradation (CC) is expressed as the ratio of the D302 and the product of D10 and D60, where D30 is the diameter corresponding to 30 percent finer in particle size distribution. TABLE A-2. PHYSICAL CHARACTERISTICS OF CAP MATERIALS Remedial Design, Sites 32 and 33, Litigation Area, Military Ocean Terminal Concord, Concord, California

¥

Moisture Content

Specific Gravity

(percent)

*

D10 (mm)

D30 (mm)

NA

Cap Material

Visual Description

Bay Mud

Dark gray clay

30.6

2.78

AquaGate

Dark bluish gray well-graded gravel

1.5

3.39

Apatite II

Pale yellow poorly graded

9.2

2.12

Macroporous Aluminosilicate

Strong brown poorly graded

4.0

3.64

Effective Size

CU

CC

D60 (mm)

*

*

NA

0.0034**

NA

NA

1.84

5.24

7.41

4.02

2.01

0.091

0.18

0.72

7.89

0.51

0.48

0.73

1.16

2.39

0.94

Notes: ¥

* **

The process of grading soil/sediment material, in accordance with either the Unified Soil Classification System, involves data collection, calculating coefficients of uniformity and gradation. A poorly graded material, unlike well graded material, does not have a good representation of all sizes of particles from the No. 4 to No. 200 sieve. A poorly graded material generally has better drainage (permeability) than a well graded material. Dimensionless. The hydrometer analysis found the Bay Mud sample includes 0.7 percent sand, 49.4 percent silt, and 49.9 percent clay.

Cc Cu D10 D30 D60 NA

Coefficient of gradation Uniformity coefficient Diameter corresponding to 10 percent finer in particle-size distribution Diameter corresponding to 30 percent finer in particle-size distribution Diameter corresponding to 60 percent finer in particle-size distribution Not applicable.

The grab sediment samples collected from Sites 32 and 33 showed moisture contents of 80 percent and 76 percent. The foul smell of dark organic rich sediment samples indicated the potential presence of sulfur and methane. Gas bubbles were coming out of the sediment containers when the lids were open. Gas bubbles and bulging sediment containers indicated potential biological activities of the benthic communities and biogenic gas-ebullition. Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-12

Figure A-5

Particle Size Distribution of Potential Cap Materials

Cap materials behave differently depending on their geotechnical characteristics. The permeability of water through sediment or cap material is related to the size and chemical characteristics of the solid particles and how tightly they are packed. In general, the smaller the particles, the more energy is required to push the water through the pores, resulting in slower passage. However, in the natural environment, the individual particles are rarely uniformly sized, but consist of a range of particle sizes. Thus, the uniformity of the particle sizes also affects how water flows through the sediment-water interface. Cap material that contains enough smaller particles to pack around the big ones and fill the voids also resulting in low water flow, while materials with more open void spaces are more permeable. Additionally, the more tightly packed the solid substrate is, the less permeability it has. Clay particles in sediment or cap material have a chemical attraction to water that also tends to retard the flow of water.


A-13

The grain size distribution of a coarse grained material is generally determined through sieve analysis, where the solid sample is passed through a stack of sieves and the percentages passing different sizes of sieves are noted. The grain size distribution of the fines is determined through hydrometer analysis, where the fines are mixed with distilled water to make 1,000 milliliters (mL) of suspension and a hydrometer is used to measure the density of the solid-water suspension at different times. The time-density data, recorded over a few days, are translated into ever decreasing grain sizes remaining in suspension. Hydrometer analysis is effective for soil fractions down to about 0.5 μm. Very often, cap materials contain both coarse and fine grains, and it is necessary to do sieve and hydrometer analyses to obtain the complete grain size distribution data. Sieve analysis is carried out first on the coarser material, and then hydrometer analysis is performed on the solid fraction passing a 75-μm sieve. The grain size distribution curve shown in Figure A-5 and Table A-2 gives a quantitative picture of the relative proportions of the different grain sizes within the soil mass. D30 is a size such that 30 percent of the cap material grains are smaller than this size. D10 and D60 can be defined in similar manner. D10 is called the effective grain size, which gives a good indication of the permeability characteristics of a coarse-grained soil. The shape of the grain size distribution curve can be described through two simple parameters, namely, coefficient of uniformity (Cu) and coefficient of curvature (Cc). A coarse-grained material is said to be well graded if there is an even distribution of sizes in a wide range. In well-graded soils, the smaller grains fill the voids created by the larger grains, thus producing a soil with fewer voids. A sand is well graded if Cu > 6 and Cc = 1-3. A gravel is well graded if Cu > 4 and Cc = 1-3. A cap material that is not well graded is poorly graded. Uniform soils and gap-graded soils are special cases of poorly graded soils. In uniform soils, most grains are about the same size. A3.2

TOTAL METAL CONCENTRATIONS IN SEDIMENT AND PORE WATER

The total metal concentrations in the sediments and the sediment pore water were both analyzed. The samples were split so that each portion could be tested separately. One portion was analyzed for total metals, and the other portion was used to extract pore water, which was then analyzed. The metals in pore water are generally considered to be bioavailable. A3.2.1

Test Procedure

Pore waters were extracted from the sediment samples collected from Sites 32 and 33. Homogenized sediments were centrifuged at 2,500 times gravity (or × g) relative centrifugal force (RCF) maintaining 4 ºC using a ThermoForma centrifuge (Model M5682) equipped with an IEC rotor 218A. The supernatant water was filtered using 0.45 µm filter (Model # 7305004). The portion of sediment samples not extracted for pore water was analyzed for arsenic, cadmium, copper, iron, lead, mercury, selenium, and zinc. The concentrations of metals in sediments are reported as milligrams per kilogram (mg/kg) on a dry weight basis, and the concentration of metals in pore water is reported as micrograms per liter (µg/L). The sample preparation and digestion procedures followed U.S. Environmental Protection Agency (EPA) SW 846 Method 3050B and metal analyses (except mercury) were conducted following EPA Method 6020 by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Mercury concentrations were analyzed as per EPA Method 7471A using Cold Vapor Atomic Absorption (CVAA). Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-14

A3.2.2

Results

Table A-3 provides the chemical data results for Bay Mud, including total metals, deionized (DI) water waste extraction test (WET) dissolved metals, semivolatile organic compounds, and volatile organic compounds. Only the DI WET concentration for copper and nickel slightly exceeded the conservative marine chronic ambient water quality criteria but were below the 1hour and 4-day freshwater ambient water quality criteria (AWQC), which are 9.0 µg/L and 13µg/L for copper and 5.2µg/L and 470 µg/L for nickel. In addition, the DI WET concentrations for copper are below the average background concentration of 532.5 µg/L. The background concentration for nickel is not available. The total metal concentrations in the sediments from Sites 32 and 33 and in the pore water samples are shown in Figure A-6 and Table A-4. The primary y-axes for Sites 32 and 33 show the metal concentrations in sediments and the target area weighted average remediation goals, and secondary y-axes show the metal concentrations in pore water. The concentrations of iron were relatively high because of the abundance of iron in the native sediments. Generally, the iron is helpful in binding contaminants and it is not considered toxic. The concentrations of metals in sediment and pore water show similar trends in the solid and liquid media, indicating similar partitioning of each of these metals. The sediment samples collected from Site 33 showed lower concentrations of these metals than the remediation goals. The copper concentrations in replicate samples were 89 mg/kg, 93 mg/kg, and 100 mg/kg, while the discrete do-not-exceed and target area weighted average goals of copper for Site 33 were 96.7 mg/kg and 139 mg/kg. The grab sediment sample collected from Site 32 showed lower concentrations of arsenic, lead, mercury, and selenium than the remediation goal concentrations. The metals concentrations (except copper) were significantly lower than the discrete do-not-exceed limit for Site 32. The zinc concentrations were lower than the discrete do-not-exceed limit and higher than target area weighted average for Site 32. A3.3

BATCH SORPTION CAPACITY TESTS

The batch sorption tests assess the sequestering capabilities of copper and arsenic by the cap materials. The partition coefficient (Kd) is the ratio of the quantity of the contaminant sorbed per mass of cap material (or sediment) to the amount of the contaminant remaining in solution at equilibrium.


A-15

TABLE A-3. MARTINEZ MARINA BAY MUD CHEMICAL DATA Remedial Design, Sites 32 and 33, Litigation Area, Military Ocean Terminal Concord, Concord, California Analyte

Result

a

Screening Criterion

b

Total Metals (mg/kg) Aluminum Antimony Arsenic Barium Beryllium Cadmium c Chromium Cobalt Copper Iron Lead Manganese Mercury Molybdenum Nickel Selenium Silver Thallium Vanadium Zinc d DI WET Dissolved Metals (µg/L) Aluminum Barium e Chromium Copper Iron Manganese Mercury Molybdenum Nickel Thallium Vanadium Zinc f Semivolatile Organic Chemicals (µg/kg) Benzo(B)fluoranthene Bis(2-ethylhexyl)phthalate Chrysene Fluoranthene Pyrene


A-16

28,000 0.31 J 15 76 0.72 0.35 84 20 70 55,000 27 2,600 0.36 0.86 89 0.44 0.31 J 0.13 J 81 140

NA NA 603 NA NA 12.2 12.2 NA 111 NA 95 NA 2.98 NA 112 12 0.58 NA NA 2,420

16 J 69 2J 7.7 37 J 24 0.47 3.4 J 11 6.5 J 1.9 J 9.5 J

NA NA NA 3.1 NA NA 0.94 NA 8.2 213 NA 81

15 J 15 J 9.3 J 22 J 22 J

371 NA 289 514 665

TABLE A-3. MARTINEZ MARINA BAY MUD CHEMICAL DATA (CONTINUED) Remedial Design, Sites 32 and 33, Litigation Area, Military Ocean Terminal Concord, Concord, California Analyte

Result

a

Screening Criterion

f

Volatile Organic Chemicals (µg/kg) 2-Butanone Acetone Carbon Disulfide M,P-Xylene Methylene Chloride

12 J 94 25 3.7 J 3.4 J

O-Xylene

1.1 J

NA 88 330 43,200 430 NA

Notes:

Bold values exceed the screening criterion or remediation goal.

a b

c d e f

Only detected results are reported for full suite analysis of total metals, VOCs, SVOCs, and DI WET dissolved metals. Screening values are based on remediation goals for select metals (arsenic, cadmium, copper, mercury, lead, selenium, and zinc) in sediment are the lowest of the target weighted average remediation goals for Sites 32 and 33. Other metals are taken from the San Francisco Bay Regional Water Quality Control Board (Water Board) 2000. Screening criterion based on chromium III. DI WET metals concentrations are compared with marine chronic ambient water quality criteria Water Board (2010). Screening criterion for chromium in water is based on chronic marine ambient water quality criterion for chromium VI. Screening criterion taken from Water Board (2000).

µg/kg µg/L DI J mg/kg NA WET SVOCs VOCs

Microgram per kilogram Microgram per liter Deionized Water used as an extractant for waste extraction testing Estimated value Milligram per kilogram Not applicable Waste extraction test Semivolatile organic compounds Volatile organic compounds

References: Water Board. 2000. Draft Staff Report: Beneficial Reuse of Dredged Materials. Sediment Screening and Testing Guide. May 2000. Water Board. 2010. San Francisco Basin Plan. Available on-line at: http://www.swrcb.ca.gov/rwqcb2/basin_planning.shtml


A-17

Figure A-6

Total Metal and Pore Water Concentrations in the Grab Sediments from Sites 32 and 33


A-18

TABLE A-4. GRAB SEDIMENTS PORE WATER DATA FROM SITES 32 AND 33 Remedial Design, Sites 32 and 33, Litigation Area, Military Ocean Terminal Concord, Concord, California Analyte

Site 32 Result

Site 33 Result

140 4.4 85 28000 8 0.21 0.44 J 410

41 0.26 J 17 32000 5.6 0.13 J 0.69 J 54

Total Metals (µg/L) Arsenic Cadmium Copper Iron Lead Mercury Selenium Zinc Notes: µg/L

A3.3.1

Microgram per liter

J

Estimated value

Sorption Isotherm Test Procedure

Batch sorption tests were conducted by equilibrating the sediment or cap materials and the site-specific water as per Barth and others (2007). The native sediments, Bay Mud from Martinez marina, and native water samples were stored in a refrigerator at a temperature of 4±2 °C until the tests began. The other cap materials were stored at room temperature until the tests began. The tests with arsenic were conducted inside a glove compartment to maintain an oxygen-free (argon) environment. The water samples were mixed from carboys in equal portions to obtain a sitespecific homogenized water sample. Proper care was taken to avoid transfer of suspended and settled particles present in the water container by carefully siphoning water from the polyethylene terephthalate (PET) carboy to a 47-liter polypropylene mixing container. Once homogenized, the mixed site water was used to prepare the stock solutions and used for the control tests. The stock solutions were prepared separately using sodium arsenite (NaAsO2) (Ricca Chemical Catalog # RDCS0280100 with 99 percent purity) and copper nitrate trihydrate (copper [NO3]2. 3[H2O]) (Fisher/Acros Chemical Catalog # AC20768-500 with 99 percent purity). The spiked target initial concentrations of copper were 50, 500, 1,000, and 5,000 milligrams per liter (mg/L) and the same of arsenic were 50, 500, 1,000, and 3,000 mg/L. The highest concentrations of both chemicals were less than their solubility limits. A separate series of tests were conducted using site-specific water without any chemical spike. The sediment samples were homogenized in the buckets using a paddle stirring device and mixing at low speed until the sediment had a uniform consistency. The sediment samples were sieved through a #10 sieve (Stainless Steel – 8-inch outer diameter [OD] ASTM E-11, Cole Parmer, FH-SS-SS-US-10) prior to use to screen out vegetative matter. The moisture content of the sediment samples was determined for the homogenized wet samples and was reported on a percent dry weight basis. The sorption test results in this report are presented as dry weight basis (unless otherwise specified). The batch sorption tests were conducted in triplicates using 150- mL pre-cleaned PET bottles with high-density polyethylene (HDPE) lined caps. About 100 milligrams (mg) of sediment or cap material was added into each of the test bottles using a precision balance (American Scientific Products, Model #ER-180A, accurate to ±0.0001 gm). The control solutions and chemical-spiked solutions were poured into the bottles leaving no headspace Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-19

and capped tightly. The weights of all solids and liquids added to each bottle were recorded gravimetrically. After the test bottles had been mixed on the Glas-Col vortex shaker (Model #099A DPM12) for 30 seconds, the bottles were placed into the Environmental Express (Model #LE1002) toxicity characteristic leaching procedure (TCLP) rotator for end-over-end tumbling. The tumbling was conducted at 23±2 °C with 30±2 rotations per minute (RPM) for 48±2 hours. After equilibration, an aliquot of the sample was transferred to a 50-mL plastic container for pH analysis. The remaining portion of the sample was filtered using Teflon Filtermate 0.45µm dissolved metal filter (Environmental Express Catalog #SC0407). The filtrate was acidified with nitric acid to a pH less than 2 and digested following EPA Method 3005A – Acid Digestion of Waters for Total Recoverable or Dissolved Metals. The metal (copper or arsenic) concentrations were analyzed by ICP-MS (EPA Method 6020). Initial and final equilibrium pH values were recorded. A3.3.2

Results

A3.3.2.1

Sorption Results

A sorption isotherm describes the equilibrium of the sorption of a contaminant by sediment or a cap material at constant temperature. It represents the amount of material bound at the surface of the solid as a function of the contaminant present in the water phase. The initial and final concentrations of total dissolved metals (copper or arsenic) in the test bottles were measured to determine the amount of metal sorbed onto the solid media. The amount of metals sorbed per unit weight of sediment or cap material was plotted with respect to equilibrium concentrations for both copper and arsenic (see Figures A-7 and A-8). The sorption isotherms of copper and arsenic by the cap materials are shown in Figures A-9 and A-10. The amount of contaminants sorbed per unit weight of native sediment increased with increasing concentrations of copper and arsenic, except for the sediment from Site 33 with the highest concentration of copper. The amount of copper sorbed by Site 33 sediment samples decreased from 134,729 mg/kg to 68,155 mg/kg as the initial copper concentration was increased from 1,000 mg/L to 5,500 mg/L. Figure A-8 has an anomaly in the sorbed copper concentration for Site 33 sediment at Ceq = 5,200 mg/L. The anomaly may be a result of laboratory interferences at a very high concentration of copper or precipitation at high concentration caused by the presence of electrolytes or heterogeneity (the presence of gravels and other inert materials) of specific sediment samples used for the batch tests. The sorption isotherms at lower concentrations (first four concentration points) were plotted separately at higher resolution to focus on sorption profiles at concentrations that more closely mimic site field conditions. The sorption isotherms for the evaluated cap materials are shown in Figures A-9 and A-10. The amount of copper and arsenic sorbed per unit weight of cap material mostly increased with an increase in the spiked concentrations of the test solution (Figures A-9 and A-10). In the case of Bay Mud cap material, the saturation at an equilibrium concentration of 1,000 mg/L of copper indicating the limited capacity of the cap material for sorption at high loading of copper. The saturation concentrations of copper and arsenic were not reached for any of the materials under the tested conditions. The increasing trend of sorption for Macroporous Aluminosilicate and Rock Phosphate indicates the availability of active surfaces even at higher concentrations of copper. In the case of arsenic, the increasing trend of sorption was observed for these cap materials. Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-20

Figure A-7

Sorption Isotherms of Copper on Sediments from Sites 32 and 33

Figure A-8

Sorption Isotherms of Arsenic on Sediments from Sites 32 and 33


A-21

Figure A-9

Sorption Isotherms of Copper on Selected Cap Materials

Figure A-10 Sorption Isotherms of Arsenic on Selected Cap Materials


A-22

A3.3.2.2

Partitioning Coefficients

The partitioning coefficients (Kd) for spiked and unspiked test solutions for native sediments in Sites 32 and 33 and for the evaluated cap materials are shown in Tables A-5 and A-6. The partition coefficient, Kd, is defined as the ratio of the quantity of the chemical adsorbed per mass of solid to the amount of the chemical remaining in solution at equilibrium. TABLE A-5. PARTITIONING COEFFICIENT (KD) OF COPPER ON SEDIMENTS AND CAP MATERIALS USING SITE-SPECIFIC WATER Remedial Design, Sites 32 and 33, Litigation Area, Military Ocean Terminal Concord, Concord, California

Test Solution Target Spike and Actual Copper Concentration (mg/L)

Site Sediment Partition Coefficient

Evaluated Cap Material Partition Coefficients

Site 32 (L/kg)

Site 33 (L/kg)

Bay Mud (L/kg)

AquaGate (L/kg)

Apatite II (L/kg)

Rock Phosphate (L/kg)

Macroporous Aluminosilicate (L/kg)

Control (no arsenic and copper spike) and actual 0.028

907.5

1424.5

1399.6

1484.1

1388.0

1236.9

1436.4

Target 10 and actual 16.5

976.7

682.6

563.3

754.1

1179.4

795.6

1361.9

Target 500 and actual 440

110.6

92.7

44.4

100.3

149.9

230.2

305.7

Target 1,000 and actual 1,000

95.1

134.7

82.6

87.2

21.3

158.4

219.9

Target 5,000 and actual 5,500

522.5

583.6

522.5

1119.1

1283.7

1016.2

1399.2

Notes: L/kg

Liter per kilogram

mg/L


Milligram per liter

A-23

TABLE A-6. PARTITIONING COEFFICIENT (KD) OF ARSENIC ON SEDIMENTS AND CAP MATERIALS Remedial Design, Sites 32 and 33, Litigation Area, Military Ocean Terminal Concord, Concord, California Test Solution Target Spike and Actual Arsenic Concentration (mg/L)

Grab Sediment

Cap Materials

Site 32 (L/kg)

Site 33 (L/kg)

Bay Mud (L/kg)

AquaGate (L/kg)

Apatite II (L/kg)

Rock Phosphate (L/kg)

Macroporous Aluminosilicate (L/kg)

Control (no arsenic and copper spike) and actual 0.034

58.5

1448.5

1339.1

1457.1

989.7

76.3

1503.8


146.1

153.5

123.8

134.4

104.6

101.9

236.5


71.7

78.1

81.2

81.1

49.3

922.1

85.3

Target 1,000 and actual 800

126.7

141.8

149.1

138.8

149.1

133.9

196.1


100.7

455.5

423.3

795.8

547.1

89.1

870.2

Notes: L/kg

Liter per kilogram

mg/L

Milligram per liter

For the cap materials evaluated, the amount of copper sorbed can be ranked in the following order: 1. 2. 3. 4.

Macroporous Aluminosilicate Rock Phosphate Apatite II Bay Mud and AquaGate (results were similar)

For the cap materials evaluated, the amount of arsenic sorbed can be ranked in the following order: 1. 2. 3. 4.

Macroporous Aluminosilicate Bay Mud and Apatite II (results were similar) AquaGate Rock Phosphate.

The sediment and cap materials have varying level of sorption capacity to attenuate copper and arsenic. Although the phosphate-containing materials (Apatite II and Phosphate Rock) showed some sequestration of arsenic in the site-specific water, Bostick and others (2003) described that removal of contaminant oxyanions (such as selenite, SeO3-2, arsenate, AsO4-3, and chromate, CrO4-2) to Apatite II in batch tests was less successful. Those batch tests, however, showed nonlinear sorption isotherms for SeO3-2, indicating sorption for low levels of soluble contaminants. The present treatability test results also showed similar results with relatively lower sorption of arsenic by Apatite II and Rock Phosphate. Bostick and others (2003) reported the affinity for cationic contaminants on Apatite II follows the ranking with decreasing magnitude of the contaminant Kd at the lowest solution phase residual concentration evaluated as follows: Pb+2 > Cd+2 > Zn+2 > Cu+2 ~ Hg+2. It should be noted that Bostick and others Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-24

(2003) evaluated other metals, but only contaminants relevant to Sites 32 and 33 have been reported in this document. A3.4

LEACHING TESTS OF CAP MATERIALS

The addition of cap material to an aquatic environment needs careful evaluation to determine if metals from the introduced cap material will leach and expose benthic organisms or surface water to harmful concentrations. The tests discussed in the following sections were performed to assess the leaching potential of chemicals from the cap materials to the environment. The test results are compared with marine water quality objectives as one of several benchmarks to assess the desirability of the potential cap materials. A3.4.1

Batch Leaching Test Procedure

The WET is a leaching test developed by the Department of Toxic Substances Control (DTSC) (see California Code of Regulations, Title 22, Chapter 11, Appendix 2). For this evaluation, the DI water WET test was used to approximate the amount of metals that could leach under field conditions. One liter of deionized water was added to a 100-gram sample and allowed to equilibrate for 48 hours. The samples were then filtered and analyzed for metals. A3.4.2

Results

A chemical must be available to an organism before it can be accumulated or cause an adverse effect. The fraction of the total contaminant concentration that is available for uptake and accumulation by ecological receptors is considered the bioavailable fraction. Indirect methods of assessing bioavailability for sediments and water systems include correlating bulk chemistry with chemical extraction of sediment (such as the DI-WET). Other parameters also may affect bioavailability and include pH, ORP, total organic carbon, salinity, hardness, and grain size. Metals generally exist in dissolved complexes (free metals or inorganic and organic complexes), non-dissolved complexes (inorganic or organic such as complexes involving humic substances), or particulate phases (sorbed to sediment particles, organic detritus, or living periphyton or plankton). Not all soluble metal complexes are available, and free metal ions are more available. In a submerged sediment marshland setting such as exists in Sites 32 and 33, sulfur, iron, and manganese are important elements involved in the redox processes. Both iron and manganese are in the divalent form and are relatively soluble in sediments. Iron and its compounds, such as iron oxides, hydroxides, and oxy-hydroxides, are an important sink for other metals in oxic conditions because of the rapid sorption of metals to negatively charged sites on the surface of iron oxides. Hydrous iron- and manganese-oxides may scavenge soluble metalloids or metals, such as arsenic, copper, and zinc, from the surface water by co-precipitation. Hydrous iron-oxides tend to decrease the bioavailability of sediment bound arsenic, copper, lead, and zinc in aerobic or oxic conditions. Metals, such as cobalt, precipitate in the presence of oxygen; while other metals, such as cadmium, zinc, copper, and nickel, precipitate as sulfides in anoxic conditions. Copper partitions to organic materials in some sediments and to iron- or manganese-oxides in other sediments, based on the relative abundances of these components. Concentrations of total and leachable metals in the cap materials under evaluation were measured to determine if bioavailable metals might be present Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-25

in significant concentrations. Total metal concentrations in the cap materials do not necessarily reflect the amount of a contaminant available to the receptors. Total concentrations include structural ions that may not partition with soluble phases associated with uptake by plants or dermal and trophic uptake by animals. Aqueous extractions of metals, such as the DI-WET, can represent the soluble component of weakly bound contaminants.

1000000

150

AquaGate Apatite II Macroporous Aluminosilicate

100000

100

Bay Mud

Total Metal Concentration (mg/kg)

DI WET AquaGate 10000

DI WET Apatite II

50

DI WET Macroporous Aluminosilicate DI WET Bay Mud

1000

0 100 -50

Metal Leached by DI WET (µg/L)

The total concentrations of target analyte list (TAL) of metals (aluminum, antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, molybdenum, nickel, selenium, silver, thallium, vanadium, and zinc) present in the cap materials were analyzed and are plotted in Figure A-11. The concentrations of aluminum and iron were relatively high, as they are the major ingredients of several of the cap materials. The cap materials contained other metals that are naturally present in the mineralogical structures. The concentrations of metals present in the leachate of the DI-WET are also plotted in Figure A-11. DI-WET results showed leachable concentrations of aluminum, iron, manganese, and other metals. Apatite II showed a significant arsenic peak concentration in the DI-WET leachate. Though significant amount of iron was present in the Apatite II structure, it appears that these irons were not able to bind the available arsenic.

10 -100 1 -150 0.1

-200

0.01

-250

0.001

Al

Sb

As

Ba

Be

Cd

Cr

Co

Cu

Fe

Pb

Mn

Hg

Mo

Ni

Se

Ag

Tl

Va

Zn

Metals

Figure A-11 Concentrations of Total Metals and DI-WET Metals in the Cap Materials The concentrations of selected metals in the DI-WET leachate are compared with various water quality screening criteria in Figure A-12. The water quality screening criteria include (1) freshwater acute AWQC, (2) freshwater chronic AWQC, and (3) marine chronic AWQC. These criteria were developed by the San Francisco Bay Region Water Board as part of the Basin Plan or represent national AWQC or the California Toxics Rule. Most of the metal concentrations tested in DI-WET leachate are lower than the freshwater acute and chronic AWQC. The concentration of leachable Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-26

arsenic (68 µg/L) from the Apatite II during the DI-WET test was lower than the freshwater acute (340 µg/L) and chronic (150 µg/L) AWQC, but higher than the marine chronic (36 µg/L) AWQC. It should be noted that the total arsenic concentrations in the Apatite II was relatively smaller (0.25 mg/kg) with respect to the average concentrations of arsenic present in other selected cap materials (8.75 mg/kg for AquaGate, 4.65 mg/kg for Macroporous Aluminosilicate, and 14.67 mg/kg for Bay Mud). The leaching of nickel from the Bay Mud in DI-WET is significantly lower than the freshwater acute and chronic AWQC and slightly higher than marine chronic AWQC. Overall, the DI WET concentrations for metals are below the average background DI WET concentrations for the site and therefore would not pose additional risk to the environment. The desorption tests, described in the next section (Section A3.5), provide additional information on potential mobility and sequestration of arsenic by these cap materials. A3.5

DESORPTION OF CONTAMINANTS FROM CAP MATERIALS

Cap materials in sediment-water system are intended to sequester contaminants. However, some cap materials can encourage the release of metals from sediments that were not previously being released to the environment. Desorption tests are conducted to evaluate whether a proposed cap material will release bound metals. 10000 Freshwater Acute AWQC Freshwater Chronic AWQC Marine Chronic AWQC 1000

AquaGate Apatite II Macroporous Aluminosilicate Bay Mud

DI WET (µg/L)

100

10

1

0.1

0.01

As

Cd

Cr

Cu

Pb

Metals

Hg

Ni

Se

Ag

Zn

Figure A-12 Comparison of Metals Leached in DI-WET and Water Quality Screening Criteria A3.5.1

Desorption Test Procedure

The desorption tests were conducted for Bay Mud, AquaGate, Macroporous Aluminosilicate, Apatite II, and Rock Phosphate in the presence of site-specific sediments and DI water (ultrapure, 18 Megaohm quality water from US Filter/Siemens system). The native sediment samples were collected in 5-gallon plastic containers and homogenized in the laboratory using a Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-27

paddle stirring device at low speed until the sediment has a uniform consistency. The sediment samples and Martinez Marina Bay Mud samples were separately sieved through #10 sieve (Stainless Steel – 8-inch OD ASTM E-11, Cole Parmer, FH-SS-SS-US-10) before use to remove vegetative matter. The percent moisture content of the homogenized sediment samples was determined and reported on a dry weight basis. The mobilization of metals, if any, by the cap materials was evaluated by adding 5 percent by weight of the cap material to 12 grams (dry weight basis) of homogenized sediment. Each desorption test was conducted identically except the test using Rock Phosphate, which was added at 8 percent by weight. These desorption tests were conducted using 150-mL PET bottles with a polyethylene lined screw cap (QEC catalog #6213-0005PET) container using 60 mL of DI water. After DI water had been added, the slurry in each bottle was homogenized by shaking for 1 minute on the Glas-Col vortex shaker (Model 099A DPM12). These desorption tests were conducted in triplicate except for Apatite II, which was conducted in duplicate, and Rock Phosphate, which was conducted as a single series of tests. In addition, control tests (without cap material) were conducted using site-specific sediments and DI water. After the samples had been mixed on the vortex shaker, the test bottles with sediment and cap material mixtures were placed into the TCLP Rotator for end-over-end tumbling at 23±2 °C with 30±2 RPM for 48±2 hours. Time-dependent desorption of arsenic on various materials has been reported in the literature, and the equilibration time varied from 17 hours to 48 hours (Lin and Wu 2001; Myneni and others 1997). The equilibration times depend on the sorbents, water quality, mass transfer effects, and interfacial rates of desorption. The equilibrium tests (sorption and desorption tests) under this treatability study were performed with a 48-hour duration to ensure near-equilibrium conditions. After equilibrating for 48 hours, portions of the samples were analyzed for pH, the remaining portions of the samples were allowed to settle, and then the supernatant liquids were filtered using Whatman® 0.45-µm dissolved metals filters (Catalog # 09-905-17) and a Kontes Scientific glass filtration apparatus (Catalog # 953870-1000). The filtrates were collected into 50-mL polyethylene bottles and acidified with nitric acid to a pH less than 2. These samples were split into two portions, with one portion being prepared following EPA Method 3005A (Acid Digestion of Waters for Total Recoverable or Dissolved Metals), and the other portion prepared following EPA Method 7470A (Mercury in Liquid Waste). Seven metals (arsenic, cadmium, copper, iron, lead, selenium, and zinc) were analyzed using EPA Method 6020by ICP-MS (Agilent ICP-MS Model 7500ce) and mercury was analyzed using EPA Method 7470A by CVAA (CETAC Model M6100). A3.5.2

Results

Heavy metals are naturally occurring in the environment and tend to sorb strongly to clays, muds, and humic and organic materials. However, they can be mobile in the environment, depending on the pH, hardness, salinity, oxidation state of the element, soil saturation, and other factors. Competitive ion displacement can represent an important means by which metals, especially arsenic, can be released to the aqueous phase and can be subject to transport. Table A-7 shows the concentrations of eight metals (arsenic, cadmium, copper, iron, lead, mercury, selenium, and zinc) after equilibration of sediments from Sites 32 and 33 and cap materials in the presence of deionized water. Separate batches of sediment samples without any cap materials were used as controls to show release of metals from the native sediments without Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-28

the influence of other materials. The concentrations of cadmium, lead, mercury, and selenium were mostly non-detectable in these samples. Iron is one of the most abundant elements in the Earth’s crust. In the marine environment, suspended iron oxy-hydroxides are generally precipitated at higher salinities (10 parts per thousand [ppt] or greater) when the vast majority of the iron present occurs in particulate form. In anoxic marine waters, ferrous iron (Fe2+) is mobilized from sediments and diffuses into the water column. Grimwood and Dixon (1997) evaluated data on the saltwater toxicity of iron and found no reliable toxicity data that indicate higher sensitivity of saltwater organisms had been reported for iron. The concentrations of copper and zinc were mostly higher in native sediments with no cap materials added than when analyzed with cap materials added. Table A-7 and Figure A-13 show the predominant release of arsenic from the cap materials, especially from Apatite II, compared with native sediments. Percent arsenic released has been calculated to normalize the concentration of arsenic present in the sediment sites as follows: % Arsenic Released = Amount of Arsenic Desorbed (mg) x 100/Initial Total Amount of Arsenic in Sediment (mg)


A-29

TABLE A-7. METAL CONCENTRATIONS AFTER EQUILIBRATION OF SEDIMENTS AND CAP MATERIALS IN DI WATER Remedial Design, Sites 32 and 33, Litigation Area, Military Ocean Terminal Concord, Concord, California Metal Concentration Source Sediment Site 32 Site 33

As

Cd

Cu

Fe

Pb

Hg

Se

Zn

Cap Material

(mg/L)

(mg/L)

(mg/L)

(mg/L)

(mg/L)

(mg/L)

(mg/L)

(mg/L)

No Cap Material (control)

0.056

0.003

0.049

3.63

0.0005

ND

ND

0.683

0.014

ND

0.006

3.09

ND

ND

ND

0.025

0.059

0.005

0.057

4.10

ND

ND

ND

0.640

0.060

0.001

0.061

6.01

ND

ND

ND

0.186

0.056

0.006

0.049

4.13

ND

ND

ND

0.646

0.036

0.005

0.038

5.60

ND

ND

ND

0.455

0.046

0.001

0.015

4.85

ND

ND

ND

0.301

0.029

0.003

0.026

3.00

ND

ND

ND

0.480

0.079

ND

0.007

3.28

ND

ND

ND

0.029

0.082

ND

0.016

5.05

ND

ND

ND

0.019

0.061

0.003

0.028

3.15

ND

ND

ND

0.362

0.040

0.002

0.027

4.63

ND

ND

ND

0.291

0.035

0.003

0.030

3.63

ND

ND

ND

0.296

Bay Mud

AquaGate Site 32 Apatite II Rock Phosphate Macroporous Aluminosilicate

Bay Mud

AquaGate Site 33 Apatite II Rock Phosphate Macroporous Aluminosilicate

0.051

0.003

0.033

5.74

ND

ND

ND

0.393

0.005

ND

0.044

0.336

ND

ND

ND

0.070

0.012

ND

0.029

1.68

ND

ND

ND

0.030

0.031

ND

0.023

5.38

ND

ND

ND

0.016

0.0048

ND

0.015

0.212

ND

ND

ND

0.035

0.016

ND

0.022

3.19

ND

ND

ND

0.033

0.012

ND

0.014

1.54

ND

ND

ND

0.038

0.112

ND

0.009

12.6

ND

ND

ND

ND

0.097

ND

ND

10.0

ND

ND

ND

ND

0.006

ND

0.014

ND

ND

ND

ND

0.021

0.003

ND

0.015

0.212

ND

ND

ND

0.024

0.003

ND

0.019

0.301

ND

ND

ND

0.017

0.003

ND

0.0126

0.752

ND

ND

ND

0.016

Notes: mg/L ND

Milligram per liter Non-detect. The detection limits are 0.000333 mg/L for cadmium, 0.167mg/L for copper, 0.000333 mg/L for iron, 0.000267 mg/L for lead, 0.000333 mg/L for selenium, and 0.00667 mg/L for zinc.


A-30

Figure A-13 Release of As from Various Cap Materials in the Presence of Sediments from Sites 32 and 33


A-31

The percent arsenic desorbed from Sites 32 and 33 sediments and cap materials are plotted in Figure A-14. Horizontal reference lines are shown to mark the baseline conditions of arsenic desorbed from control (sediment only) samples. The concentrations above those lines identify the cap materials that desorbed arsenic and the points below indicate limited or desorption of arsenic from the sediments as a result of the presence of the cap materials in deionized water. For Site 32, AquaGate and Macroporous Aluminosilicate did not cause desorption of arsenic from site sediments. For Site 33, Rock Phosphate and Macroporous Aluminosilicate did not cause desorption of arsenic from site sediments. The percent arsenic desorbed from Bay Mud was slightly greater than that from control samples from Sites 32 and 33 but was judged to lie within the margin of error for the analysis.

Figure A-14 Percent As Desorbed from Sites 32 and 33 Sediments and Cap Materials Ion-exchange takes place between phosphate (PO4) and arsenic, as they share many similar properties and often compete for the same surface sorption sites. Dissolved silicate and organic matter can also competitively limit arsenic sorption or promote desorption, with concentrations common to sediments having an appreciable impact on dissolved arsenic concentrations. Carbonate present in the marine environment can also compete with arsenic for sorption sites on mineral surfaces, and natural organic matter may also compete with arsenic and inhibit arsenic sorption onto iron (hydr)oxides as a result of competitive sorption. Speciation of arsenic plays an important role in its bioavailability in the sediment-water systems. The release of arsenic can also depend on the hydrodynamic conditions.


A-32

A3.5.3

Effect of pH on Desorption

In near-neutral pH waters, arsenic III is present primarily as uncharged arsenous acid, whereas arsenic V is predominantly in the anionic form. Significant desorption of arsenic has been reported in presence of minerals such as Gamma Alumina, aluminum oxide (γ-Al2O3), goethite, and iron oxide (α-FeOOH) with the increase of pH (Ghosh and others 2006). Figure A-15 shows the equilibrium pH of DI water in the presence of sediments and sediment-cap mixtures. The equilibrium pH values of the sediment-DI water system were 6.64 for Site 32 and 6.62 for Site 33. Small changes in pH were observed when Bay Mud and AquaGate were added to the site-specific sediments. Moderate pH changes toward neutral water conditions were observed when Apatite II, Rock Phosphate, and Macroporous Aluminosilicate were added in the sediment. The change toward neutral pH conditions did not affect desorption of arsenic, as Macroporous Aluminosilicate showed strong binding to arsenic under the site-specific test conditions.

Figure A-15 Equilibrium pH of Sediments and Cap Materials A3.6

SETTLING VELOCITY

The settling velocity of the cap material is one of the key variables in the study of contaminant transport in sediment-water system, especially in cases where resuspension occurs because settling velocity is the dominant restoring force. In spite of this importance, it is nearly impossible to obtain its actual value in situ, so settling velocity is typically obtained from laboratory experiments or predicted by empirical formulas. This study includes experimentation and predicted results. Settling velocity tests were performed on the potential cap materials using the method described below.


A-33

A3.6.1

Test Procedure

This method used a 2-liter graduated cylinder containing site water and selected cap material (Chattopadhyay and others 2005). Cap materials, as received, were tested by settling solid materials under their own weight through still site water. When placed in fluid, a solid body denser than the fluid settles downward and accelerates in response to the force of gravity. As the velocity of the body increases, the fluid drag force grows until it eventually equals the submerged weight of the body, whereupon the body falls at its terminal velocity and no longer accelerates (Figure A-16). The terminal velocity is calculated using the following formula: ut =

2g ⋅ mp (ρ p − ρ )

ρρ p Ap C

where, Ut

=

Terminal velocity, g is acceleration caused by gravity

mp

=

Mass of particle

ρp

=

Density of the particle

ρ

=

Density of the surrounding fluid

Ap

=

The projected area of the particle in direction of motion

The drag coefficient, C, was calculated assuming that the particles are spherical rigid particles. Drag coefficients were calculated for appropriate particle Reynolds numbers (NRe) for: NRe < 0.1 0.1 > NRe > 1000 1,000 > NRe >350,000 The specific gravities and particle size distribution of various cap materials are discussed in Section 3.1.2.


A-34

Figure A-16 Attainment of Terminal Velocity by a Cap Material When Dropped from Rest in a Cylinder Containing Site-Specific Water A3.6.2

Results

Native sediments from Sites 32 and 33 formed a stable suspension by adding 100 grams of sediment to a 2,000-liter graduated cylinder. Site water was added to the graduated cylinders. Visual observation indicated the presence of fine particles associated with lighter organic-rich “fluffy” material. The suspension was settled in less than 10 days. Figure A-17 shows the suspended native sediment at the beginning of the test and as a settled mass after 10 days. The settling velocities of the native sediment samples were not calculated as the velocities depended on the individual particles (sand, silt, clay, and organic flocs). A low settling velocity for the cap material can result in a significant increase in water turbidity because a material with a low settlement velocity may not settle within the confines of the cap area and is also more susceptible to resuspension. For these reasons, a cap material with low settling velocity can reduce water quality. Too high a settling velocity of the cap materials could cause the cap material to sink into the sediment bottom, compact the sediments, and release and mix potentially highly contaminated interstitial water into the surface water. Therefore, it is important to determine the settling velocity of each potential cap material. The Cap Stability Evaluation conducted in Appendix B of the Remedial Design


A-35

Report will assess the stability of the cap material from erosional forces associated with current flow in the slough and ditches. The settling velocities of the cap materials tested are plotted in Figure A-18. The primary yaxis and solid lines indicate the settling velocities of the cap materials. The secondary y-axis and dashed lines indicate the grain size of the cap materials. These selected cap materials were settled within 30 minutes after test materials were added in the water columns. AquaGate and Macroporous Aluminosilicate had the highest settling velocities. The data in Figure A-18 showed the estimated settling velocity of Bay Mud when the dispersed state of the material (49 percent clay) was considered. Bay Mud was collected as irregular sized compacted mass from the Martinez Marina dredge spoil ponds. Depending on the size, the compacted mass of Bay Mud traversed the distance of the graduated cylinder (height of standing water column of 16.25 inches) from 29.85 seconds to 41.78 seconds. Though dispersed Bay Mud (as fine silty clay material) showed a lower settling velocity, the compacted mass (as received material) showed significantly higher settling velocity acceptable for placement of the cap.

(a)

(b)

Figure A-17 (a) Dispersed Sediment at the Beginning of the Test, and (b) Settled Solids After 10 Days Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-36

Figure A-18 Settling Velocities at Various Particle Sizes of Cap Materials A3.7

CHEMICAL FLUX MODEL

This section summarizes the preliminary simulation results of the transport modeling that was performed to evaluate the chemical flux in each cap material. An appropriate thickness for a specific cap material is designed based on the estimated chemical flux, the design life of the project, and site-specific remediation goals. The model simulations were conducted using sitespecific input parameters to assess long-term copper flux through sediment with and without cap materials. The copper concentrations drove the design thickness of the cap because the copper poses greater ecological risk at Site 32 and Site 33 than the arsenic or any other contaminant. A3.7.1

Introduction

The total thickness and composition of the cap materials are based on an evaluation of processes such as consolidation of cap materials, bioturbation, erosion, and mass transfer of the chemicals of concern through the cap. A conservative “layer approach” is used for a cap design with a granular material, where each component is considered, and the necessary cap thickness is assumed as the sum of the layers for each component. Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-37

Of particular importance is the layer that is responsible for maintaining chemical isolation of the contaminants of concern. The thickness of this layer is greatly affected by the affinity of the material for the particular chemicals of concern, which is copper in the case of Sites 32 and 33. Several numerical models are available to predict long-term movement of contaminants into or through caps as a result of advection and diffusion processes using a number of site-specific parameters. These results can be compared with applicable remediation goals, or interpreted in terms of a mass loss of contaminants as a function of time. A3.7.2

Transport Model

A computational model that includes numerical calculations of the mass flux of copper through the sediment and cap was used to establish an optimum cap thickness for the sediments in Sites 32 and 33. The model is based on the mass transfer equations for advection and diffusion. Assumptions made pertaining to the input data required for the model are summarized in Table A-8. TABLE A-8. MODEL KEY INPUT PARAMETERS Remedial Design, Sites 32 and 33, Litigation Area, Military Ocean Terminal Concord, Concord, California Parameter

Value

Source

Thickness effectively mixed by bioturbation (Lbio)

10 cm

Boudreau 1998; Reible 1998; Chattopadhyay and others 2005 and 2007

Consolidation distance within cap (ΔLcap)

5 cm

Engineering estimate

Consolidation distance of underlying sediment (ΔLsed)

15 cm


0.3 – 0.4


Void fraction within cap (ε) Molecular diffusion coefficient of copper in water (Dw)

-5

2

7.69 x 10 cm /sec

Du and Suni 2004

44-1400 (522) L/kg

Treatability testing

Partition coefficient for Phosphate Rock

158–1236 (687) L/kg


Partition coefficient for AquaGate

87-14484 (750) L/kg


Partition coefficient for Apatite II

150-1388 (804) L/kg


Partition coefficient for Macroporous Aluminosilicate

219-1436 (945) L/kg


Partition coefficient for Bay Mud

Notes: cm Centimeter cm2/sec Square centimeter per second L/kg Liter per kilogram The values within parentheses indicate the average values that were considered for the model simulations.

This model has been used to calculate an effective cap thickness based on the partition coefficients of both the cap and sediment materials and taking into consideration long-term losses that are associated with diffusive processes.


A-38

Based on the simulation results, the effective cap thickness of each of the cap materials, Leff, was derived for the copper contamination as per the following correlation:

Leff = L0 – Lbio – ∆Lcap – ∆Lsed, A In the above correlation, L0 is the initial thickness of the cap immediately after placement, ∆Lcap is the consolidation of the cap, Lbio is the bioturbation depth and ∆Lsed, A is the thickness of the cap compromised by copper during consolidation of the underlying sediment. The resulting cap thickness was calculated based on the input parameters as shown in Table A-8. The parameter ∆Lsed, A was calculated based on the assumed consolidation of the underlying sediment and a retardation factor for copper. The retardation factor was calculated based on an estimated void fraction of the cap material, the value of the bulk density of the sediment, and the partition coefficient of the individual cap materials in various simulation runs as determined by the treatability tests. The resulting effective cap thickness was used to assess long-term losses through the cap by advective or diffusive processes. A typical simulation output considering copper loading rate of 271 mg/kg is plotted in Figure A-19. The x-axis represents the time interval when mass transfer is occurring in years, and the y-axis represents the flux (in milligrams per square meter per year, mg/m2/yr) of copper through the sediment with and without the cap material. The curve denoted by the solid red line represents the mass flux of copper that would occur if the sediment was left uncapped. A high flux occurs initially at the beginning (time = 0) since the concentration of copper in the sediment at the sediment-water interface is at its greatest. As the copper is transported to the water column, the concentration at the uncapped sediment surface begins to decrease. Mass transfer of copper occurs between the deeper sediment and the surface sediment. Assuming that the transfer is very slow and that there are no disturbances from other sources (such as storms) that would agitate the sediment and would cause the rapid bulk movement of sediment and pore water, mass transfer between the deeper sediment to the surface sediment to the surface water will reach a near steady-state value, which is indicated by the solid red line. The blue dashed line represents the copper flux through the Bay Mud from Martinez Marina as cap material, considering a constant concentration of copper (semi-infinite) in the underlying sediment, while the green dashed line represents a finite mass (or concentration) of copper in the sediment layer (mass transfer that results in the depletion of copper in the sediment beneath the cap). Each of these fluxes (represented by the blue and green dashed lines) is expected to be zero until breakthrough of copper occurs from the cap into the surface water. The flux from the cap material into the surface water then slowly increases with time. After several years, the flux through the cap material into the surface water approaches the value that would occur if no cap was present (designated by the red line), indicating that the cap material had become saturated with copper. As per this simulation run using both semi-infinite and finite contaminant assumptions, it would take hundreds of years for the copper flux through the sediment capped with Bay Mud to ultimately reach a maximum of about 1x103 mg/m2/year.


A-39

Figure A-19 Mass Flux of Copper Through the Sediment and Bay Mud Cap Material The concentration of copper at various locations of the site is plotted in Figure A-20. The y-axis indicates the concentrations of copper in the sediment samples collected in 2009 at various locations. The various bars show the individual copper concentration at a particular collection point. The average concentration of copper in the shallower region at Site 32 is 270.9 mg/kg and the average concentration of copper in the shallower region at Site 33 is 127 mg/kg. The parallel dark lines in Figure A-20 show the standard deviations. The deeper section of Site 32 showed an average copper concentration of 228 mg/kg with highest concentration as 1,290 mg/kg. The maximum concentration of copper in the shallow zone of Site 33 (above 220 mg/kg) was observed at only two locations. The maximum concentration of copper in the shallow zone of Site 32 (above 900 mg/kg) was observed at only two locations. The minimum copper concentrations during 2009 sampling showed 20.6 mg/kg for Site 32 and 31 mg/kg for Site 33. Two sets of loadings of copper (271 mg/kg at Site 32 and 127 mg/kg at Site 33) in the sediment were used as input parameters for the model. Copper in the natural environment is generally distributed as isolated locations. Considering the localized distribution of copper in these sites, it is practical to consider the average copper loading value for the simulation of mass flux through the cap.


A-40

Figure A-20 Copper Concentrations in Sediments from Sites 32 and 33 at Various Shallow Locations


A-41

Considering the distribution of copper concentrations in the sediment, the flux calculations simulated two copper loadings in the native sediment: •

326 mg/kg, the 95% upper confidence limit (UCL95) of the mean concentrations for Site 32

•

142 mg/kg, the 95% upper confidence limit of the mean for Site 33.

The remedial objective of this site is based on site-specific remediation goals (target area weighted average and discrete do-not-exceed levels) for copper. The target area weighted average for Site 32 is 111 mg/kg and the discrete do-not-exceed copper goal is 200 mg/kg. The target area weighted average for Site 32 is 96.7 mg/kg and the discrete do-not-exceed copper goal is 139 mg/kg. Considering these remediation goals, simulation runs were conducted to estimate the copper flux at the treatment goal. Using the results of treatability tests of various cap materials, simulations were conducted at the above-mentioned two copper loadings. The simulation runs were also made at various initial thicknesses of Bay Mud. The results of various runs are plotted in Figures A-21 and A-22 for Site 32 and Site 33. The x-axis indicates the time interval when mass transfer is occurring in years and the y-axis indicates the flux (mg/m2/year) of copper through the cap material and the flux at the treatment goal. For comparison only, Figures A-23 and Figure A24 show the flux of copper through the five cap materials (Bay Mud, Phosphate Rock, AquaGate, Apatite II, and Macroporous Aluminosilicate) at two loadings (326 mg/kg for Site 32 and 142 mg/kg for Site 33) at a seepage velocity of 10 centimeters per year. These figures demonstrate the effectiveness of the various cap materials in sequestering the copper within the cap. A3.7.3

Model Conclusions

Figure A-21 provides the model results for Bay Mud at various cap thicknesses for Site 32. The flux that would occur in the sediment at the remediation goal is also demonstrated on the figure. As demonstrated on Figure A-21, the flux through the cap after 30 years for a cap thickness of 8 inches of Bay Mud is less than the time area weighted average and the discrete do-not-exceed remediation goals. The design criterion for the cap life is 30 years and, therefore, an 8-inch cap would meet the design criterion at Site 32 for isolating the metal contaminants. Figure A-22 provides the model results for Bay Mud at various cap thicknesses for Site 33. As with the previous figure, the flux that would occur from the sediment at the remediation goal is also demonstrated on the figure. The flux through the cap at 30 years for a cap thickness of 8 inches of Bay Mud is less than the time area weighted average and the discrete do-not-exceed remediation goals. Therefore, an 8-inch cap would meet the design criterion at Site 33 for isolating the metal contaminants. Additional cap thickness may be required to protect against erosion which is evaluated under Appendix B, “Cap Stability Evaluation”. Figure A-23 and Figure A-24 compare the effectiveness of the various cap materials with the cap thickness set at 12 inches. As shown on the figures, Bay Mud is not as effective as some of the other active cap materials, but it is not a significantly inferior performer. In fact, depending on the final porosity of the cap, Bay Mud may perform as well as the other active cap materials tested. Macroporous Aluminosilicate performed the best relative to the other cap materials tested. Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-42

Figure A-21 Flux of Copper through Bay Mud at Various Cap Thickness at Site 32 Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-43

Figure A-22 Flux of Copper through Bay Mud at Various Cap Thickness at Site 33 Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-44

Figure A-23 Flux of Copper through Various Cap Materials for Site 32 at average Copper Loadings and Seepage Velocity 10 cm/year Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

A-45

Figure A-24 Flux of Copper through Various Cap Materials for Site 33 at Average Copper Loadings and Seepage Velocity 10 cm/year


A-46

A4.0 SUMMARY The observations of the treatability studies are summarized below. •

The pH of the grab sediments was neutral or near neutral in Sites 32 and 33. The cap materials evaluated also have near-neutral pH values.

•

The partition coefficients change with equilibrium concentrations of contaminants and other site-specific conditions. The selected cap materials showed sorption of both tested contaminants (copper and arsenic). The amount of copper sorbed generally decreased in the following order: 1. Macroporous Aluminosilicate 2. Rock Phosphate 3. Apatite II 4. Bay Mud and AquaGate were similar. The amount of arsenic sorbed generally decreased in the following order: 1. Macroporous Aluminosilicate 2. Bay Mud and Apatite II were similar 3. AquaGate 4. Rock Phosphate.

•

The leaching (DI-WET) of arsenic from Apatite II was significantly higher than that from AquaGate, Apatite, and Bay Mud. The leached concentration of arsenic from Apatite II was also higher than the marine chronic AWQC.

•

The desorption tests conducted in the presence of site-specific sediments showed higher amount of arsenic released from the Apatite II and Rock Phosphate than the other cap materials selected. Macroporous Aluminosilicate showed the least amount of arsenic release in comparison to other cap materials for sediments from both Sites 32 and 33.

•

The settling velocity of the four cap materials were tested using the cap materials as received using site water. The fastest settling velocity was measured for AquaGate, followed by Macroporous Aluminosilicate and then Apatite II. Bay Mud had the slowest settling velocity. Settling velocity is considered further as an input parameter in the cap stability evaluation presented in Appendix B.


A-47

A4.1

CAP PERFORMANCE AGAINST DQOS

The following provides the results of the treatability study for each cap material against the original data quality objectives’ principal study questions defined in the work plan Chemical Isolation Effectiveness Chemical isolation effectiveness is assessed relative to the following two questions: 1. What is the required thickness of the cap material so that the flux of chemical contaminants remains below the remedial goal? Based on a cap life of at least 30 years, the minimum required thickness for each cap material is: •

Bay Mud — 8-inches for Sites 32 and 33

•

Aggregate Gravel Coated Modified Clay (AquaGate) — Less than 12-inches. The minimal thickness was not modeled.

•

Macroporous Aluminosilicate— Less than 12-inches. The minimal thickness was not modeled.

•

Mineral Apatite — Less than 12-inches. The minimal thickness was not modeled.

2. Can the cap material leach chemicals that could be toxic to the aquatic organisms? The DI WET metal concentrations from each cap material are compared with the freshwater and chronic acute AWQC provided below: •

Bay Mud — the DI WET metal concentration results were less than the freshwater acute AWQC and freshwater chronic AWQC except for cadmium and selenium, which slightly exceeded the freshwater chronic AWQC. The DI WET metal concentrations are less than the background native sediment DI WET values for all metals. A Bay Mud cap is judged to be nontoxic to the aquatic organisms at Sites 32 and 33.

•

Aggregate Gravel Coated Modified Clay (AquaGate) — the DI WET metal concentration results were less than the freshwater acute AWQC and freshwater chronic AWQC with the exception of cadmium, which slightly exceeded the freshwater chronic AWQC. The DI WET metal concentrations are less than the background native sediment metal concentrations for all metals. An AquaGate cap is judged to be nontoxic to the aquatic organisms at Sites 32 and 33.

•

Macroporous Aluminosilicate — the DI WET metal concentration results were less than the freshwater acute AWQC and freshwater chronic AWQC with the exception of cadmium and selenium, which slightly exceeded the


A-48

freshwater chronic AWQC. The DI WET metal concentrations are less than the background native sediment metal concentrations for all metals. A Macroporous Aluminosilicate cap is judged to be nontoxic to the aquatic organisms at Sites 32 and 33. •

Mineral Apatite — metal concentrations are less than the freshwater acute AWQC and freshwater chronic AWQC with the exception of cadmium and selenium, which slightly exceeded the freshwater chronic AWQC. The DI WET metal concentrations are less than the background metal concentrations in native sediment for all metals. An Apatite II cap is judged to be nontoxic to the aquatic organisms at Sites 32 and 33.

Sediment Stability and Erosion How effective is each cap material in stabilizing the sediments and the erosion resistance? The estimation of the critical velocity for each cap material was compared with the estimated bottom current velocity through the slough in Appendix B of the remedial design report for Sites 32 and 33 and this data quality objective (DQO) is fully evaluated in Appendix B. The results of the evaluation indicate that Bay Mud is a suitable cap material for use in Sites 32 and 33. Physical Isolation Effectiveness - Bioturbation Evaluation Review What is the required thickness of a cap that will physically isolate the contaminated material from benthic organisms? Appendix C of the remedial design report evaluated the required thickness to prevent the benthic invertebrate community from burrowing through the cap into contaminated sediments below, and this DQO is fully evaluated in Appendix C. The results of the evaluation indicate that Bay Mud is a suitable cap material for use in Sites 32 and 33. A4.2

SELECTION OF CAP MATERIAL

The selection of the cap material is based on this treatability study, the stability evaluation (see Appendix B), and the bioturbation evaluation review (Appendix C). The cap material selection considers the material’s ability to meet DQOs. The cap’s sorption capacity, stability against erosion, material availability, cost effectiveness, and ecological impact were all considered. Bay Mud was selected as the preferred cap material and offers the following advantages. •

Availability – Bay Mud is readily available within 20 miles of the site. The other materials are one or more of the following, manufactured, not locally available.

•

Cost Effectiveness – Material cost for Bay Mud is the lowest by a large degree. The mud is free of cost at the borrow source and requires a shorter trucking distance than any other material.


A-49

•

Ecological impact – Martinez Marina Bay Mud is natural sediment and possesses material properties that are similar to the native sediments in the slough and ditches. The analytical chemistry results did not identify elevated chemical concentrations in the Bay Mud cap materials that would be toxic in the sloughs and ditches in Sites 32 and 33.

•

Physical Isolation – Bay Mud is effective in providing physical isolation of the contaminated sediments from the environment and also creates a suitable substrate for invertebrate after remediation.

•

Sorption Capacity – Bay Mud exhibited effective sorption capabilities of arsenic and copper, and the model indicated Bay Mud was as effective as the other active cap materials. Based on the chemical flux model Bay Mud is effective at providing chemical isolation of the contaminated sediments from the environment. A cap thickness of 8 inches composed of Bay Mud at Site 32 and Site 33 is effective in meeting the design criteria of having a flux concentration of copper below the target area weighted average remediation goal for 30 years.


A-50

A5.0 REFERENCES American Integrated Services, Inc. (AIS). 2011. “Treatability Study Work Plan for Assessing Cap Material. Sites 32 and 33 Litigation Area, Military Ocean Terminal Concord, Concord, California.” Barth, E., Sass, B., and S. Chattopadhyay. 2007. “Evaluation of Blast Furnace Slag as a Means of Reducing Metal Availability in a Contaminated Sediment for Beneficial Use Purposes.” Soil and Sediment Contamination 16(3):281-300. Bostick, W.D., Stevenson, R.J., Harris, L.A., Peery, D., Hall, J.R., Shoemaker, J.L., Jarabek, R.J., and E.B. Munday. 2003. “Use of Apatite for Chemical Stabilization of Subsurface Contaminants.” U.S. Department of Energy, National Energy Technology Laboratory. DE-AC26-01NT41306. Boudreau, B.P. 1998. Mean mixed depth of sediments: The wherefore and the why. Limnol. Oceanogr. 43(3):524-526. Chattopadhyay, S., A. Gavaskar, M. Hackworth, V. Lal, B. Sugiyama, and P. Randall. 2005. “A Reactive Cap for Contaminated Sediments at the Navy’s Dodge Pond Site.” Environmental Security Technology Certification Program. Partners in Environmental Technology Technical Symposium & Workshop, Washington, DC. Chattopadhyay, S., V. Lal, S.H. Rosansky, M.R. Palermo, F. Oliveira, F. Carvalho, and O. Fukuda. 2007. In Situ Reactive Capping of Arsenic-Contaminated Sediments: Evaluation of Effectiveness of Various Reactive Cap Materials. 4th Conference on Remediation of Contaminated Sediments, Savannah, Georgia. Du, B., and I.I. Suni. 2004. Water Diffusion Coefficients during Copper Electropolishing. Journal of Applied Electrochemistry 34: 1215–1219. Ghosh, A., Eduardo Sa´ez, A., and W. Ela. 2006. “Effect of pH, Competitive Anions and NOM on the Leaching of Arsenic from Solid Residuals.” Science of the Total Environment 363:46-59. Grimwood, M.J. and E. Dixon. 1997. “Assessment of Risks Posed by List II Metals to Sensitive Marine Areas (SMAs) and Adequacy of Existing Environmental Quality Standards (EQSs) for SMA Protection.” Report to English Nature. Lin, T. and J. Wu. 2001. “Adsorption of Arsenite and Arsenate within Activated Alumina Grains: Equilibrium and Kinetics.” Water Res. 35:2049–57. Martinez, M.N., Hightower, S.M., Smith, G.B., Mueller, W., Conca, J.L., and J. Wright. 2006. “The Effect of Apatite II™ on the Biodegradation of TNT and Perchlorate in Contaminated Soil Samples.” Available on-line at: http://www.nmspacegrant.com/files/tiny_mce/file_manager/fellowships_research/martine z06.pdf Appendix A, Remedial Design, In Situ Cap Sites 32 and 33 Litigation Area MOTCO

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Myneni, S., Traina, S., Logan, T., and G. Waychunas. 1997. “Oxyanion Behavior in Alkaline Environments: Sorption and Desorption of Arsenate in Ettringite.” Environ Sci Technol. 31:1761–8. Reible, D. 1998. Model for Chemical Contaminant by a Cap. In: Guidance for In-Situ Subaqueous Capping of Contaminated Sediments. Technical Report DOER-1. Washington, DC. San Francisco Bay Regional Water Quality Control Board (Water Board). 2000. “Draft Staff Report: Beneficial Reuse of Dredged Materials.” Sediment Screening and Testing Guide. May 2000. Water Board. 2010. San Francisco Basin Plan. Available on-line at: http://www.swrcb.ca.gov/rwqcb2/basin_planning.shtml


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ATTACHMENT A1 X-RAY DIFFRACTION ANALYSIS

Qualitative Phase Analysis of Cap Materials by X-ray Powder Diffractometry Introduction The interaction of x-rays with crystalline matter gives us coded information about crystal structure in the form of diffracted intensity (I) as a function of the measured diffraction angle 2. Knowing the radiation wavelength (and measuring the diffraction angle (2) we can solve the Bragg Equation (n = 2dsin to obtain the interplanar distance (d) between related planes of atoms comprising the crystal lattice1. Qualitative phase analysis by x-ray diffraction relies on the unique collection of dspacings and relative intensities that are imposed on each crystalline phase by strict atomic ordering. The x-ray diffraction pattern becomes a “fingerprint” for phase identification2. Computer-assisted searches of reference phase data can be compared to the experimental unknown data until a suitable match is found. A measure of the performance of the search/match routine is given by a figure of merit (FOM) to each reference phase in the match-list. A small FOM indicates a better match. Inputs used in calculating FOMs include 1) the percentage of reference lines appearing in the unknown pattern, 2) the percentage of unknown lines matched

by the reference data and 3) the percentage of reference intensities that match the unknown pattern intensities3. The success of a search/match result can depend on such factors as 1) the quality of the reference data, 2) variable experimental conditions for data collection, 3) severe overlapping of diffraction peaks from multiphase samples, 4) preferred orientation of particles, 5) absorption of the incident beam and its effects on relative peak intensities and 6) effects of solid solution. Influences of these factors make it possible that the match list does not include the phase(s) actually present in the unknown specimen. Furthermore, a reference match may be isostructural with the unknown yet be inconsistent in its elemental analysis. A total elemental analysis of the unknown sample greatly aids in the selection or rejection of candidate phases from the matchlist4. The objective of this study is to identify the dominant crystalline phase(s) present in twelve samples (5 untreated and 7 treatments) using powder x-ray diffractometry. Phase selections are to be based on visual goodness-of-fit of the reference phase diffraction data compared to the experimental unknown diffraction patterns. Selections are also guided by FOMs from search/match of the reference phase database.

Method 1. Sample preparation Untreated samples were air-dried, crushed using an agate mortar and pestle (AGC-4 and MB-4) or disc-milled (PR-4, MAC-4, and AP2-4) using a Stiebteknik (Angstrom Inc.) processional mill. Treated (As5000 and Cu5000) sample suspensions were transferred to Teflon Oak Ridge-type 50-mL centrifuge tubes, balanced and centrifuged at 5000 rpm for 10 minutes using a Beckman Model J2-21 centrifuge equipped with an angle-head rotor. Decantates were Page 2 of 34

retained, the solids were quick-frozen in liquid nitrogen, lyophilized for 36 hrs using a Labconco Model Freeze Dryer 8, and powdered using an agate mortar and pestle.

Two-gram subsamples

of the sediments (AGC-4 and MB-4) were placed inside 2-mL cuvettes and equilibrated with ethylene glycol vapor for 3 days inside a glass dessicator at 60°C prior to scanning.

2. X-ray Diffraction Analysis The x-ray diffraction analysis was carried out using a Bruker D8 Advance Series II x-ray diffraction system equipped with K780 Generator operating at 40 kV and 40 mA, KFL 2.2 kW Cu tube, scintillation counter, diffracted-beam graphite crystal monochromator, 0.6-mm divergence slit, 0.6-mm anti-scatter slit, 0.1-mm receiving slit and 1.0-mm secondary monochromator anti-scatter slit. Powder specimens were top-loaded into 25.4-mm diameter Bruker powder mounts, the excess powder struck away from the mount surface so as to minimize preferred orientation and bring the specimen surface tangent to the goniometer circle. Instrumental settings are given in Table 1, sample scan settings are given in Table 2. The raw scans are collected using the Bruker XRD Commander data collection software.

Table 1. X-ray diffractometer settings. Tube voltage

40kV

Filament current

40mA

Source divergence slit

0.6 mm

Source anti-scatter slit

0.6 mm

Receiving slit

0.1 mm

Monochromator anti-scatter slit

1.0 mm

Scan mode

step

Scan type

2locked

Page 3 of 34

Table 2. Sample scan settings. Scan

Step

Count

range

interval

time per

(°2

(°2

step (sec)

AGC-4(untreated)

2-70

0.05

8

None

AGC-4(EG)

2-36

0.05

4

Ethylene glycol solvation

AGC-4-Cu5000

2-70

0.03

10

5000 ppm Cu

AP2-4(untreated)

2-70

0.01

10

None

AP2-4-As5000

2-70

0.03

10

5000 ppm As

AP2-4-Cu5000

2-70

0.03

10

5000 ppm Cu

MAC-4(untreated)

2-70

0.01

10

None

MAC-4-As5000

2-70

0.03

10

5000 ppm As

MAC-4-Cu5000

2-70

0.03

10

5000 ppm Cu

MB-4(untreated)

2-70

0.05

8

None

MB-4(EG)

2-36

0.05

4

Ethylene glycol solvation

MB-4-As5000

2-70

0.03

10

5000 ppm As

MB-4-Cu5000

2-70

0.03

10

5000 ppm Cu

PR-4(untreated)

2-70

0.05

8

None

Sample

Treatment

Scan processing and qualitative phase analysis were carried out using EVA data evaluation software. A program-default background function defining the level of noise in the scan was fitted and subtracted from each raw scan prior to launching the search/match routine. The EVA search/match algorithm tended to reject reference patterns whose lines fell within regions of null intensity in the unknown scan. User-defined parameters and filters were not declared prior to launching the search/match. A FOM was calculated for all patterns with at least one line falling within the unknown scan region of non-null intensity. Reference pattern lines falling within regions of null-intensity were penalized in proportion to their relative line Page 4 of 34

intensities. Reference patterns with lines falling within regions of non-null intensity present in the unknown sample scan were awarded bonus points. Weighting of bonus points from these matching lines were insensitive to reference line intensities and intensities of the matched regions of the unknown scan. The FOM was calculated from the penalties and bonus points given to each line of the reference pattern. The FOM was influenced by the users search criteria. The simple criterion was biased in favor of reference patterns with high crystallographic symmetry and thus, higher FOMs resulted from fewer lines in the unknown scan being matched by fewer lines in the high-symmetry reference pattern. By contrast, the complex criterion was biased in favor of reference patterns with low crystallographic symmetry and thus, lower FOMs resulted from relatively more unknown scan lines being explained by greater numbers of reference lines exhibited in lower-symmetry pattern matches. The neutral criterion was unbiased, allowing equal opportunity for the unknown scan to be matched by either high- or lowsymmetry reference patterns. The Powder Diffraction File (PDF), maintained by the International Center for Diffraction Data (ICDD), was accessed during the search/match operation. Candidate phases were sorted in order of increasing FOM (decreasing goodness of fit to the experimental scan).

Page 5 of 34

Results

Crystallinity Peak/background area ratios (Tables 3-7) described the coherent-diffracted fraction of the total intensity received at the detector resulting from constructive interactions between incident Curadiation and solid matter of medium- to long-range atomic periodicity (crystallinity). Based on peak/background area ratios, inferred relative crystallinities of untreated samples were in order of highest to lowest crystallinity PR-4 > AGC-4 > MB-4 > MAC-4 > AP2-4. The raw scan of the rock phosphate sample (PR-4, Fig. 5) was described as a collection of sharp, high-intensity peaks of narrow width, suggesting considerable crystal development. By contrast, raw scans of the fishbone (AP2-4, Fig. 2) and ceramic (MAC-4, Fig.3) samples possessed relatively wide, low-intensity peaks.

Apparent termination of growth along crystallographic

directions had given rise to small (nano) particles with limited development in the numbers of crystal planes needed to extinguish non-Bragg diffraction effects. These non-Bragg effects were expressed as intensity tailing off on low- and high-angle sides of peak maxima in the scans of AP2-4 and MAC-4. Implication of defect-rich (nano-porous, nano-particulate) materials were high specific surface area with associated sorption and reactivity.

Arsenic treatments X-ray diffraction evidence for the presence of As-containing phase(s) was confined to small regions of non-null intensity near the background functions of all As-treatments (Figs. 2-4). Areas of diffracted intensity associated with As-treatments tended to be of wide angular breadth and lacking clear peak maxima, suggesting that products of interaction between As and substrates were of low-crystallinity. Intensities of residual peaks from the substrates were observed above high-background intensities in all As-treated spectra. Page 6 of 34

Copper treatments Absorption of Cu-radiation from the incident beam and emission of fluorescent Cu-radiation by Cu-containing samples contributed to relatively higher background intensities in the XRD spectra of Cu-treatments (Figs. 1-4). Relative to their untreated analogs, the increased fluorescent intensities originated from smaller irradiated sample volumes. Precipitation of a Cu-containing phase(s) from incomplete removal of interstitial pore fluids in AGC-4-Cu5000 (Fig. 1), MAC-4-Cu5000 (Fig. 3) and MB-4-Cu5000 (Fig. 4) was seen in the d100 = 5.7Å reflection of Cu2(OH)3Cl (botallackite). Widths of reflections were only 3 to 4times the scan step-interval (0.091-0.105°) at half-maximum intensity, suggesting a high-degree of crystallinity in the Cu2(OH)3Cl precipitate. By contrast, evidence for significant Cuinteraction with the fishbone substrate and formation of a poorly-crystalline new phase was seen in the scan of AP2-4-Cu5000 (Fig. 2) as a broad 9.6Å- reflection with width 35-times the scan step-interval at half-maximum intensity.

Search/Match and phase selection Figures 6-19 are the individual raw sample scans from which fitted background functions were subtracted in order to define levels of non-null intensity for reference-pattern fitting. Key reflections are labeled according to d-spacing (Å) and contributing mineral phase(s). Top 50 results from search/matches of inorganic and mineral subfiles of the powder diffraction database are given in Excel worksheets for each treatment and untreated scan. The match-list outputs are spreadsheet columns containing powder diffraction file numbers (PDF#) with quality mark, compound (mineral) name, chemical formula, number of reference pattern lines matching the experimental scan (Mtc), number of reference pattern lines not matching the experimental scan Page 7 of 34

(nM), figure of merit (FOM) and rank number (N°). Three blocks of match-lists, one for each of the three search criteria (simple, complex and neutral) are stored within each worksheet. Candidate reference patterns were superimposed onto background-subtracted scans to test visual goodness of fit prior to phases selection or rejection. In the absence of supplementary chemical information, search and match fitting of reference pattern lines to experimental scans invoked tentative status to phase selections in Table 8.

Ethylene glycol solvation of organo-clay (AGC-4) and dredge (MB-4) materials Reference patterns that were selected from the match-lists to describe the untreated phase compositions of the organo-clay (AGC-4, Fig. 6) and the dredge (MB-4, Fig.15) materials comprised suites of mineral phases not uncommon to terrestrial sediments and soils Clear evidence of an expandable 2:1 layer silicate component (beidellite) in the organo-clay (AGC-4, Fig.7) was seen as a low-angle shift in the 12.6Å peak to 16.9Å following ethylene glycol solvation. Ethylene glycol expansion of interlayer space between 2:1 expandable unit-layers was far less-well expressed in the dredge (MB-4, Fig. 16).

Page 8 of 34

AGC-4 120 110 100 90

Cps

80 70 60 50

AGC-4-Cu5000 AGC-4(untreated)

40 30 20 10 0 2

10

20

30

40

50

60

°2-theta Cu K-alpha

Figure 1. Superimposed AGC-4(untreated) and AGC-4-Cu5000 XRD raw scans.

Page 9 of 34

70

AP2-4

40

AP2-4-Cu5000 AP2-4-As5000 AP2-4(untreated)

Cps

30

20

10

0 2

10

20

30

40

50

60

70


Figure 2. Superimposed AP2-4(untreated), AP2-4-As5000 and AP2-4-Cu5000 XRD raw scans.

Page 10 of 34

MAC-4 90

80

70

Cps

60

50

40

MAC-4-Cu5000 MAC-4-As5000 MAC-4(untreated)

30

20

10

0 2

10

20

30

40

50

60

70


Figure 3. Superimposed MAC-4(untreated), MAC-4-As5000 and MAC-4-Cu5000 XRD raw scans.

Page 11 of 34

MB-4 160 150 140 130 120 110

Cps

100 90 80 70 60 50

MB-4-Cu5000 MB-4-As5000 MB-4(untreated)

40 30 20 10 0 3

10

20

30

40

50

60

70


Figure 4. Superimposed MB-4(untreated), MB-4-As5000 and MB-4-Cu5000 XRD raw scans.

Page 12 of 34

PR-4 50

Cps

40

30

20

10

0 2

10

20

30

40


Figure 5. PR-4 XRD raw scan.

Page 13 of 34

50

60

70

Table 3. Integral statistics of the raw scans and the background functions for sample AGC-4. AGC-4

Scan parameter Left endpoint 2 Right endpoint 2 n data points Area Peak/Bkg area ratio

AGC4(untreated) Raw scan Bkg fnc 2.00 2.00 70.00 70.00 1361 250 5585 3674 0.52

AGC-4(EG) Raw scan Bkg fnc 2.00 2.00 36.00 36.00 681 289 2003 1392 0.44

Page 14 of 34

AGC-4-Cu5000 Raw scan Bkg fnc 2.00 2.00 70.00 70.00 2268 268 8973 7274 0.23

Table 4. Integral statistics of the raw scans and the background functions for sample AP2-4.

AP2-4


AP24(untreated) Raw scan Bkg fnc 2.00 2.00 70.00 70.00 1361 190 4602 4244 0.08

AP2-4-As5000 Raw Bkg scan fnc 2.00 2.00 70.00 70.00 2268 283 7396 6891 0.07

Page 15 of 34

AP2-4-Cu5000 Raw Bkg scan fnc 2.00 2.00 70.00 70.00 2268 253 12851 12096 0.06

Table 5. Integral statistics of the raw scans and the background functions for sample MAC-4. MAC-4 area Scan parameter Left endpoint 2 Right endpoint 2 n data points Area Peak/Bkg area ratio

MAC4(untreated) Raw scan Bkg fnc 2.00 2.00 70.00 70.00 1361 250 2792 2514 0.11

MAC-4-As5000 Raw scan Bkg fnc 2.00 2.00 70.00 70.00 2268 295 6271 5870 0.07

Page 16 of 34

MAC-4-Cu5000 Raw scan Bkg fnc 2.00 2.00 70.00 70.00 2268 232 5952 5287 0.13

Table 6. Integral statistics of the raw scans and the background functions for sample MB-4. MB-4


MB4(untreated) Raw Bkg scan fnc 2.00 2.00 70.00 70.00 1361 229 3705 2852 0.30

MB-4(EG) Raw Bkg scan fnc 2.00 2.00 36.00 36.00 681 226 1325 1048 0.26

Page 17 of 34

MB-4-As5000 Raw Bkg scan fnc 2.00 2.00 70.00 70.00 2268 280 7724 7006 0.10

MB-4-Cu5000 Raw Bkg scan fnc 2.00 2.00 70.00 70.00 2268 286 5902 4789 0.23

Table 7. Integral statistics of the raw scans and the background functions for sample PR-4.


PR-4 PR4(untreated) Raw Bkg scan fnc 2.00 2.00 70.00 70.00 1361 247 2554 1654 0.54

Page 18 of 34

Table 8. Summary table of phase selections from Eva Search/Match Sample AGC-4(untreated)

AGC-4-Cu5000

AP2-4(untreated)

AP2-4-As5000

AP2-4-Cu5000

MAC-4(untreated)

MAC-4-As5000

MAC-4-Cu5000

MB-4(untreated)

MB-4-As5000

MB-4-Cu5000

PR-4(untreated)

Selected Mineral Phases Muscovite 2M2 Beidellite Loughlinite Quartz Cristobalite Beidellite Ammonium Hafnium Fluoride Botallackite Illite Nontronite Hydroxylapatite Chlorellestadite Calcium Silicate Afwillite Phaunouxite Tooeleite Hydroxylapatite Goldquarryite Ramsbeckite Pseudomalachite Magnesioferrite Magnetite Maghemite Chromite Iron Quartz Makarochkinite Maghemite Sarmientite Kankite Botallackite Atacamite Malachite Maghemite Muscovite 2M1 Clinochlore1MIIb, ferroan Beidellite Quartz Quartz Anorthite, ordered Manganese Arsenate Hydroxide Unnamed Lindackerite Quartz Botallackite Owensite Ramsbeckite Carbonatefluorapatite Calcite Quartz

Page 19 of 34

Chemical Formula KAl2Si3AlO10(OH)2 (Na,Ca)0.3Al2(Si,Al)4O10(OH)2·xH2O Na2Mg3Si6O16·8H2O SiO2 SiO2 (Na,Ca)0.3Al2(Si,Al)4O10(OH)2·xH2O (NH4)2HfF6 Cu2(OH)3Cl K0.7Al2(Si,Al)4O10(OH)2 (Na,Ca)0.3Fe2(Si,Al)4O10(OH)2·xH2O Ca9.61(PO4)5.77(OH)2.29((H2O)1.01H0.59) Ca5(P,Si,S)3O12(Cl,OH,F) Ca3SiO5 Ca3(SiO3OH)2·2H2O Ca3(AsO4)2·11H2O Fe8(AsO4)6(OH)6·5H2O Ca5(PO4)3(OH) CuCd2Al3(PO4)4F2·12H2O Cu15(SO4)4(OH)22·6H2O Cu5(PO4)2(OH)4 MgFe2+3O4 Fe+2Fe2+3O4 Fe2O3 Fe+2Cr2O4 Fe SiO2 Ca2Fe4+2Fe+3TiSi4BeAlO20 Fe2O3 Fe2OH(AsO4)(SO4)·5H2O Fe+3AsO4·3.5H2O Cu2(OH)3Cl Cu7+2Cl4(OH)10·H2O Cu2+2(CO3)(OH)2 Fe2O3 KAl2.9Si3.1O10(OH)2 (Mg2.8Fe1.7Al1.2)(Si2.8Al1.2)O10(OH)8 (Na,Ca)0.3Al2(Si,Al)4O10(OH)2·xH2O SiO2 SiO2 CaAl2Si2O8 Mn7(AsO3OH)4(AsO4)2 Ca-Cu-AsO4-H2O Cu5(AsO4)2(AsO3OH)2·9H2O SiO2 Cu2(OH)3Cl (Ba,Pb)6(Cu,Fe,Ni)25S27 Cu15(SO4)4(OH)22·6H2O Ca10(PO4)5CO3F1.5(OH)0.5 CaCO3 SiO2

30

20

10

2 10

60

50

40

20 30

Page 20 of 34 40 50 60

d=1.375 Quartz, syn d=1.366 Cristobalite, syn d=1.353 Cristobalite, syn

d=1.399 Cristobalite, syn

d=1.432 Cristobalite, syn d=1.421 Cristobalite, syn

d=1.567 Loughlinite d=1.542 Quartz, syn d=1.517 Loughlinite d=1.495 Cristobalite, syn d=1.495 Montmorillonite-15A d=1.491 Loughlinite

d=1.695 d=1.690 Loughlinite Montmorillonite-15A d=1.675Quartz, Loughlinite d=1.672 syn d=1.659 Quartz, syn

d=1.818 Quartz, syn d=1.802 Quartz, syn

d=1.929 Cristobalite, syn d=1.907 Loughlinite d=1.871 Cristobalite, syn

d=2.010 Muscovite-2M2

d=2.160 Loughlinite d=2.138 Muscovite-2M2 d=2.118 d=2.110 Cristobalite, Loughlinite syn d=2.076 Muscovite-2M2

d=2.601 Loughlinite d=2.576 Muscovite-2M2 d=2.566 Muscovite-2M2 d=2.560 Montmorillonite-15A d=2.554 Muscovite-2M2 d=2.550 Loughlinite d=2.511 Muscovite-2M2 d=2.495 Muscovite-2M2 d=2.487 Cristobalite, syn d=2.479 Loughlinite d=2.467 Cristobalite, syn d=2.457 Quartz, syn d=2.440 Loughlinite d=2.438 Muscovite-2M2 d=2.412 Muscovite-2M2 d=2.384 Muscovite-2M2 d=2.329 Muscovite-2M2 d=2.282 Quartz, syn d=2.236 Quartz, syn

Muscovite-2M2 d=3.311 d=3.327 Loughlinite d=3.210 d=3.180Loughlinite Muscovite-2M2 d=3.136 Cristobalite, syn d=3.124 Muscovite-2M2 d=3.089 Loughlinite d=3.034 Muscovite-2M2 d=2.928 Muscovite-2M2 d=2.840 Cristobalite, syn d=2.796 Muscovite-2M2

d=3.631 Loughlinite d=3.556 Muscovite-2M2 d=3.516 Cristobalite, syn d=3.492 Muscovite-2M2 d=3.344 Quartz, syn

d=4.511 Loughlinite d=4.462 Montmorillonite-15A d=4.443 Muscovite-2M2 d=4.339 Loughlinite Muscovite-2M2 d=4.271 Muscovite-2M2 d=4.253 Quartz, syn d=4.150 Loughlinite d=4.039 Cristobalite, syn d=4.000 Loughlinite d=3.938 Muscovite-2M2 d=3.879 Muscovite-2M2 d=3.832Muscovite-2M2 Loughlinite d=3.779

d=4.989 Muscovite-2M2 d=4.808 Loughlinite

70

d=6.461 Loughlinite

80

d=7.628 Loughlinite

d=9.990 Muscovite-2M2

90

d=13.608 Montmorillonite-15A d=12.881 Loughlinite

Cps 120

AGC-4(untreated)

110

100

0 70


Figure 6. Background-subtracted (Bkg  = 1, Curvature = 1) scan of AGC-4(untreated) with selected d-I pattern overlays.

d=16.926 Beidellite, glycolated

110 100

d=12.615

AGC-4 120

90

Cps

70 60


50 40 30 20


80

Ethylene glycol solvated untreated

10 0 2

10

20

30


Figure 7. Background-subtracted scans of AGC-4 (ethylene glycol solvated and untreated) with selected d-I pattern overlays.

Page 21 of 34

20

10

40

30

2 10 20 30 d=2.689 Illite Botallackite d=2.602 Botallackite d=2.578 Botallackite d=2.571 Nontronite d=2.560 Illite d=2.511 Nontronite d=2.501 Illite d=2.490 Botallackite d=2.470 Botallackite d=2.457 Botallackite d=2.450 Illite d=2.409 Botallackite d=2.370 d=2.369 Illite Beidellite d=2.319 Ammonium Hafnium Fluoride d=2.308 Botallackite d=2.282 syn d=2.281 Quartz, Nontronite d=2.239 Illite d=2.200 Ammonium Hafnium Fluoride d=2.164Illite Nontronite d=2.160 d=2.128 Nontronite Quartz, syn d=2.127

d=3.565 Beidellite d=3.501 Illite d=3.360d=3.330 Ammonium Fluoride d=3.344 Quartz, syn IlliteHafnium d=3.290 Botallackite d=3.241 Nontronite d=3.230 Illite d=3.210 Ammonium Hafnium Fluoride d=3.160 Beidellite d=3.061 Nontronite d=3.059 Illite d=2.994Illite Nontronite Hafnium Fluoride d=2.990 d=2.960 Ammonium d=2.854 Botallackite d=2.840 Illite d=2.813 Botallackite

d=4.253 Quartz, syn d=4.171 Botallackite d=4.137 d=4.092 Botallackite Illite d=3.901 IlliteAmmonium Hafnium Fluoride d=3.839

d=4.536 Nontronite d=4.501 Illite

Page 22 of 34 40 50 60

d=1.352 Illite

d=1.383 Nontronite Nontronite d=1.382 Quartz, syn d=1.380 d=1.376 Nontronite d=1.372 Nontronite Quartz, syn

d=1.423 Nontronite

d=1.454Illite Nontronite d=1.453 Quartz, syn d=1.450

d=1.495 Illite

d=1.542 d=1.542Nontronite Quartz, syn d=1.536 Illite d=1.535 Botallackite d=1.532 Botallackite

d=1.621 Illite d=1.599 Botallackite d=1.591 Illite d=1.572Illite Botallackite d=1.567

d=1.696 Illite d=1.673 Nontronite d=1.672 Quartz, syn d=1.669 Nontronite d=1.665 Illite

d=1.755Illite Botallackite d=1.751

d=1.820Quartz, Ammonium d=1.818 syn Hafnium Fluoride d=1.817 Botallackite Nontronite d=1.813 Illite d=1.802 Quartz, syn

d=1.994 Illite d=1.984 Botallackite d=1.980 Nontronite Quartz, syn d=1.951Illite Botallackite d=1.944 d=1.932 Botallackite d=1.910 d=1.902Ammonium BotallackiteHafnium Fluoride

d=5.705 Botallackite

120


70

d=5.826 Ammonium Hafnium Fluoride

130

d=5.038 Illite

50

d=12.412 Beidellite

60

d=7.173 Beidellite

d=10.291 Illite

Cps 140

AGC-4-Cu5000

110

100

90

80

0 70


Figure 8. Background-subtracted (Bkg  = 1, Curvature = 1) scan of AGC-4-Cu5000 with selected d-I pattern overlays.

4

3

2

1

2 10

5

20

6

30 40

Page 23 of 34 50 60

d=1.476 Hydroxylapatite



8

d=1.455 Hydroxylapatite d=1.451 Hydroxylapatite

9


10


13

d=1.808 Hydroxylapatite d=1.782 Hydroxylapatite d=1.756 Hydroxylapatite

14


15


11


16







Cps 18

AP2-4(untreated)

17

12

7

0 70


Figure 9. Background-subtracted (Bkg  = 1, Curvature = 1) scan of AP2-4(untreated) with selected d-I pattern overlays.

3

2

2 10 d=5.063 Afwillite

4

20

5

30

Page 24 of 34 40 50 60 d=1.388 Afwillite

d=1.452 Afwillite d=1.429 Afwillite d=1.414 Afwillite

d=1.588 Afwillite d=1.583 Tooeleite d=1.574 Tooeleite

d=1.563 Tooeleite

d=1.666 Tooeleite

d=1.735 Phaunouxite

d=1.921d=1.913 Afwillite Afwillite d=1.896 Tooeleite d=1.858 Tooeleite Afwillite d=1.857

d=1.984 Afwillite

d=2.181 Afwillite d=2.149 Afwillite d=2.101 Afwillite

d=2.785 Phaunouxite

9

d=2.283 Afwillite d=2.278 Tooeleite

d=2.862 Phaunouxite

d=2.913 Phaunouxite d=2.835 Afwillite d=2.825 Tooeleite d=2.823 Phaunouxite d=2.817 Afwillite d=2.809 Phaunouxite d=2.758 Tooeleite d=2.755 Phaunouxite d=2.736 Phaunouxite d=2.727 Afwillite d=2.698 d=2.693 Phaunouxited=2.681 Tooeleite d=2.677 AfwilliteAfwillite d=2.660 Afwillite d=2.596 Phaunouxite d=2.589 Tooeleite d=2.587 Afwillite d=2.570 Phaunouxite d=2.535 Tooeleite d=2.528Afwillite Phaunouxite d=2.508

d=3.462 Tooeleite d=3.405 Phaunouxite d=3.445 Afwillite d=3.277 Phaunouxite d=3.208 Tooeleite d=3.127 Afwillite d=3.101 Phaunouxite d=3.048 Afwillite d=3.027 Tooeleite Phaunouxite d=3.005 Afwillite

d=4.092 Tooeleite d=3.894 Tooeleite d=3.842 Phaunouxite d=3.741 Afwillite d=3.683 Phaunouxite d=3.664 Tooeleite

d=4.692 Afwillite d=4.561 Phaunouxite

6 d=9.752 Tooeleite

7

d=5.418 Phaunouxite

d=11.506 Phaunouxite

Cps

AP2-4-As5000

8

1

0 70


Figure 10. Background-subtracted (Bkg  = 1, Curvature = 1) scan of AP2-4-As5000 with selected d-I pattern overlays.

Cps

2 10 20

d=9.438 Goldquarryite

30 40

Page 25 of 34 50 60

d=1.442 Ramsbeckite

d=1.515 Ramsbeckite d=1.505 Hydroxylapatite, syn

Ramsbeckite d=1.635 d=1.642 Goldquarryite d=1.618 Goldquarryite d=1.598 Goldquarryite d=1.577 Goldquarryite d=1.558 Ramsbeckite

d=1.732 Goldquarryite syn d=1.721 Hydroxylapatite, d=1.693 Goldquarryite d=1.684 Hydroxylapatite, syn

d=1.944 Hydroxylapatite, syn d=1.932 Goldquarryite d=1.890 Goldquarryite d=1.874 Ramsbeckite d=1.845 Goldquarryite d=1.834 Goldquarryite d=1.812 d=1.811Ramsbeckite Goldquarryite d=1.792 Ramsbeckite d=1.788 Goldquarryite d=1.781 Hydroxylapatite, syn d=1.776 Ramsbeckite d=1.769 Goldquarryite

d=2.145 Ramsbeckite d=2.140 Goldquarryite d=2.102 Goldquarryite d=2.059 Goldquarryite d=2.040 Hydroxylapatite, syn d=2.029 Ramsbeckite

d=2.318 Ramsbeckite d=2.297 Hydroxylapatite, syn d=2.284 Goldquarryite d=2.263 Hydroxylapatite, syn d=2.251 Goldquarryite d=2.229 Hydroxylapatite, d=2.213 Goldquarryite syn

d=3.096 Goldquarryite d=3.010 Goldquarryite d=3.003 Ramsbeckite d=2.996 Ramsbeckite d=2.932 Ramsbeckite d=2.911 Ramsbeckite d=2.885 Ramsbeckite d=2.821 Goldquarryite d=2.815 Hydroxylapatite, syn d=2.805 Ramsbeckite d=2.779 Hydroxylapatite, syn d=2.773 Ramsbeckite d=2.753d=2.722 Goldquarryite d=2.734 Goldquarryite d=2.720 Hydroxylapatite, syn Ramsbeckite d=2.695 d=2.682Ramsbeckite Ramsbeckite d=2.641 d=2.636Ramsbeckite Goldquarryite d=2.574 Ramsbeckite Goldquarryite d=2.570 Ramsbeckite d=2.516 d=2.510Ramsbeckite Ramsbeckite d=2.495 Ramsbeckite d=2.431 Goldquarryite d=2.414 Ramsbeckite d=2.395 Goldquarryite

d=3.495 Ramsbeckite d=3.468 Ramsbeckite d=3.442 Hydroxylapatite, syn d=3.408 Ramsbeckite d=3.311 Goldquarryite d=3.269 Goldquarryite d=3.253 Ramsbeckite

d=3.754 Ramsbeckite d=3.734 Ramsbeckite d=3.714 Ramsbeckite

d=4.724 Goldquarryite d=4.491 Goldquarryite d=4.280 Goldquarryite d=4.125 Ramsbeckite d=4.121 Goldquarryite d=4.059 d=4.031Ramsbeckite Ramsbeckite

d=5.596 Ramsbeckite d=5.319 Ramsbeckite d=5.278 Goldquarryite d=5.265 Hydroxylapatite, syn


d=7.087 Ramsbeckite


d=11.191 Ramsbeckite

25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

AP2-4-Cu5000

70


Figure 11. Background-subtracted (Bkg  = 1, Curvature = 1) scan of AP2-4-Cu5000 with selected d-I pattern overlays.

4

3

2

1

2 10 d=3.344 Quartz, syn

5

20 30

Page 26 of 34 40 50

6

60

d=1.382 Quartz, syn d=1.375 Quartz, d=1.372syn Quartz, syn

d=1.418 syn d=1.418Quartz, Magnesioferrite, disordered, syn

d=1.453 Quartz, syn

d=1.483 Magnesioferrite, disordered, syn

d=1.542 Quartz, syn

d=1.615 d=1.608 Quartz, syn Magnesioferrite, disordered, syn



d=1.802 Quartz, syn

d=2.020 Iron

8

d=1.980 Quartz, syn

9

d=2.128 Quartz, syn d=2.096 Magnesioferrite, disordered, syn

10

d=1.818 Quartz, syn


11


d=2.457 Quartz, syn d=2.422 Magnesioferrite, disordered, syn


d=4.253 Quartz, syn


Cps 12

MAC-4(untreated)

7

0 70


Figure 12. Background-subtracted (Bkg  = 1, Curvature = 1) scan of MAC-4(untreated) with selected d-I pattern overlays.

4

3

2

2 10 d=4.870 Sarmientite d=4.819 Maghemite-C, syn d=4.779 Makarochkinite d=4.639 Sarmientite

d=9.288 Sarmientite d=8.533 Sarmientite d=8.000 Makarochkinite

5

20

9

8

7

6

30

Page 27 of 34 40 50 60

d=1.480 Maghemite-C, syn



d=2.088 d=2.075Makarochkinite Makarochkinite


d=2.323 Makarochkinite d=2.319d=2.308 Maghemite-C, syn Makarochkinite

d=2.924 Makarochkinite d=2.870 Sarmientite d=2.792 Sarmientite d=2.781 Maghemite-C, syn d=2.769 Makarochkinite Sarmientite d=2.714 d=2.725 Makarochkinite d=2.675 Makarochkinite d=2.668 Sarmientite d=2.667 Makarochkinite d=2.601 Sarmientite d=2.547 Makarochkinited=2.525 Sarmientite d=2.530 Makarochkinite d=2.521 Maghemite-C, syn d=2.518 Makarochkinite d=2.507 Makarochkinite d=2.453 Makarochkinite d=2.437 Sarmientite

10

d=2.983 Makarochkinite

d=3.129d=3.120 Sarmientite Makarochkinite

d=3.410 Maghemite-C, syn d=3.330 Sarmientite

d=4.258 Sarmientite d=4.180 Maghemite-C, syn

Cps

MAC-4-As5000

1

0 70


Figure 13. Background-subtracted (Bkg  = 1, Curvature = 1) scan of MAC-4-As5000 with selected d-I pattern overlays.

20 d=5.491 Atacamite, syn

10

2 10 20

30

30

Page 28 of 34 40 50 60

d=1.369 Botallackite d=1.354 Maghemite-C, syn


d=1.432 Maghemite-C, syn d=1.423 Botallackite d=1.420 Atacamite, syn

d=1.498 Malachite, syn d=1.479 Botallackite d=1.478 Atacamite, syn d=1.476 Maghemite-C, syn

d=1.616Atacamite, Botallackite d=1.608 syn syn d=1.608 Maghemite-C, d=1.599Malachite, Botallackite d=1.594 syn d=1.591 Malachite, syn d=1.572 Malachite, syn d=1.559 Botallackite d=1.558 Atacamite, syn d=1.535 Botallackite d=1.532Malachite, syn d=1.531

d=1.719 Atacamite, syn d=1.705Malachite, Maghemite-C, d=1.698 syn syn

d=1.990 Malachite, syn d=1.984 Botallackite d=1.968 Maghemite-C, d=1.967 Atacamite, synsyn d=1.951 Botallackite d=1.947 Malachite, syn d=1.938 Malachite, syn d=1.932 Botallackite d=1.912 Malachite, d=1.902 d=1.899Botallackite Malachite, syn syn d=1.859 Botallackite d=1.833 Atacamite, Malachite, syn syn d=1.825 syn d=1.822 d=1.821 Malachite, d=1.817 Botallackite d=1.810Maghemite-C, Botallackite syn

d=2.059 Botallackite d=2.057 Malachite, d=2.052 Malachite, synsyn

d=2.159 Malachite, syn

d=2.315 Malachite, syn d=2.272 Atacamite, syn

d=2.521 Atacamite, syn d=2.518 Malachite, Maghemite-C, syn syn d=2.499 Malachite, d=2.490 Botallackite d=2.488 Malachite, syn syn d=2.457 Botallackite d=2.429 Malachite, syn Maghemite-C, syn d=2.409d=2.412 Botallackite

d=2.953 Maghemite-C, syn d=2.860 Malachite, syn d=2.854 Botallackite d=2.842 Atacamite, syn d=2.827 Malachite, syn d=2.813 Botallackite d=2.785 Maghemite-C, d=2.781 Malachite, syn d=2.773 Atacamite, synsyn d=2.745 Atacamite, syn d=2.689 Botallackite d=2.644 Maghemite-C, syn d=2.602 Botallackite d=2.578 Botallackite

d=3.439 d=3.416 Atacamite, Botallackitesyn d=3.290 Botallackite



d=4.541 Atacamite, syn

60 d=5.705 Botallackite

70

d=5.038 Malachite, Atacamite, syn syn

Cps

MAC-4-Cu5000

80

50

40

0 70


Figure 14. Background-subtracted (Bkg  = 1, Curvature = 1) scan of MAC-4-Cu5000 with selected d-I pattern overlays.

40

30

20

10

2

50

10 20 d=2.999 Muscovite 2M1, syn

30

Page 29 of 34 40 50 60

d=1.418 syn d=1.414Quartz, Clinochlore-1MIIb, ferroan d=1.401 Clinochlore-1MIIb, ferroan d=1.391 Clinochlore-1MIIb, ferroan d=1.382 Quartz, syn syn d=1.375 Quartz, d=1.372 Quartz, syn

d=1.453 Quartz, syn

d=1.510 Clinochlore-1MIIb, ferroan d=1.499 Muscovite 2M1, syn

d=1.563 Clinochlore-1MIIb, ferroan d=1.547 Clinochlore-1MIIb, ferroan d=1.542 Quartz, syn

d=1.608 Quartz, syn d=1.602 Muscovite 2M1, syn

d=1.823d=1.818 Clinochlore-1MIIb, Quartz, synferroan d=1.802 Albite, Quartz,calcian, syn ordered d=1.796 d=1.778 Albite, calcian, ordered d=1.748 Clinochlore-1MIIb, ferroan d=1.736 Muscovite 2M1, syn ferroan d=1.727 Clinochlore-1MIIb, d=1.720 Albite, calcian, ordered d=1.699 Muscovite 2M1, syn d=1.672 Quartz,2M1, syn syn d=1.670 Muscovite d=1.661 Clinochlore-1MIIb, d=1.659 Quartz, syn d=1.653 Muscovite 2M1, syn ferroan

d=1.886 Clinochlore-1MIIb, ferroan d=1.880 Albite, calcian, ordered

d=2.070 Clinochlore-1MIIb, ferroan d=2.051 Muscovite 2M1, syn d=2.028 Beidellite d=2.020 Clinochlore-1MIIb, ferroan d=2.010 Muscovite 2M1, syn d=2.006 Clinochlore-1MIIb, ferroan d=1.999 Albite, Illite-2M2 calcian, ordered d=1.993 d=1.980 Quartz, 2M1, syn syn d=1.975 Muscovite

d=2.282 Quartz, syn d=2.263 Muscovite Clinochlore-1MIIb, ferroan d=2.247 2M1, d=2.236 Muscovite Quartz, syn 2M1,syn syn d=2.201 Muscovite 2M1, synsyn d=2.185 Muscovite 2M1, d=2.149Muscovite Muscovite2M1, 2M1,syn syn d=2.132 d=2.128 Quartz, syn

d=2.597 Clinochlore-1MIIb, ferroan d=2.589 Muscovite 2M1, syn d=2.579 Muscovite 2M1, syn d=2.562 Muscovite 2M1, syn d=2.558 Clinochlore-1MIIb, ferroan d=2.514 Muscovite 2M1, syn d=2.498 Illite-2M2 d=2.459 Muscovite 2M1, d=2.457 Quartz, syn d=2.453 Clinochlore-1MIIb, d=2.445 Muscovite 2M1, synsyn ferroan d=2.395 Muscovite 2M1, syn d=2.387 Clinochlore-1MIIb, ferroan d=2.380 Muscovite d=2.369 Beidellite2M1, syn d=2.357 Clinochlore-1MIIb, ferroan

d=2.870 Muscovite 2M1, syn d=2.829 Muscovite Clinochlore-1MIIb, d=2.804 2M1, synferroan

100 d=3.344 Quartz, syn

110

d=3.208 Muscovite 2M1, syn Albite, calcian, d=3.183 Albite, calcian,ordered ordered d=3.160 Beidellite d=3.198

d=5.020 Muscovite 2M1, syn d=5.001 Beidellite d=4.989 Illite-2M2 d=4.708 Clinochlore-1MIIb, Clinochlore-1MIIb, ferroan ferroan d=4.639 d=4.481Muscovite Muscovite2M1, 2M1,syn syn d=4.462 d=4.390 Muscovite 2M1, syn d=4.298 Muscovite 2M1, synd=4.253 Quartz, syn d=4.108 Muscovite 2M1, syn d=4.031 Albite, calcian, ordered d=3.973 Muscovite 2M1, syn d=3.890 Muscovite syn ordered d=3.871 Albite,2M1, calcian, d=3.758 Albite, calcian, ordered d=3.734 Muscovite 2M1, syn d=3.707 Albite, calcian, ordered d=3.654 Albite, calcian, ordered d=3.565 Beidellite d=3.540 Clinochlore-1MIIb, ferroan d=3.501 Muscovite 2M1, syn d=3.489 Albite, calcian, ordered d=3.442 Albite, calcian, ordered d=3.368 Albite, calcian, orderedMuscovite 2M1, syn d=3.352 d=3.319 Illite-2M2

d=7.173 Beidellite d=7.136 Illite-2M2 d=7.074 Clinochlore-1MIIb, ferroan

d=10.089 d=9.990Illite-2M2 Muscovite 2M1, syn

d=14.124 Clinochlore-1MIIb, ferroan d=12.412 Beidellite

Cps 120

MB-4(untreated)

90

80

70

60

0 70


Figure 15. Background-subtracted (Bkg  = 1, Curvature = 1) scan of MB-4(untreated) with selected d-I pattern overlays.

60

50

40

30

20

2 10

untreated

110

100

Ethylene glycol solvated

20

Page 30 of 34


d=4.253 Quartz, syn

180

170

160 d=3.344 Quartz, syn

190


70


80


90




d=12.352

10 d=14.243


Cps 200

MB-4

150

140

130

120

0 30


Figure 16. Background-subtracted scans of MB-4 (ethylene glycol solvated and untreated) with selected d-I pattern overlays.

20

10

2 10

30

20 30

Page 31 of 34 40 50 60

d=1.375Quartz, Quartz,syn syn d=1.372

d=1.409 Anorthite, ordered

d=1.454 Quartz, Anorthite, d=1.453 synordered

d=1.489 Anorthite, ordered

d=1.550 Lindackerite d=1.542 Quartz,ordered syn d=1.541 Anorthite, ordered d=1.536 Anorthite,

d=1.605 Anorthite, ordered d=1.587 Anorthite, ordered

d=1.762 Anorthite, ordered d=1.731 Anorthite, ordered d=1.718 Anorthite, Anorthite, ordered ordered d=1.713 d=1.681 Anorthite, ordered d=1.659 Quartz, syn

d=1.836 Anorthite, ordered d=1.818 Quartz, syn

d=1.898 Lindackerite d=1.877 Anorthite, ordered

d=1.986 ordered d=1.980 Anorthite, Quartz, syn Lindackerite

d=2.128 syn d=2.126Quartz, Lindackerite

d=2.282Lindackerite Quartz, syn d=2.264 Anorthite, ordered d=2.237 ordered d=2.236Anorthite, Quartz, syn

40

d=2.667 Lindackerite d=2.639 Lindackerite d=2.609 Lindackerite d=2.570 Lindackerite d=2.557 Anorthite, ordered d=2.544 Anorthite, ordered d=2.535 Lindackerite d=2.524 Anorthite, ordered d=2.507 d=2.505 Lindackerite Anorthite, ordered d=2.484 Lindackerite d=2.470 Lindackerite d=2.457 Quartz, syn d=2.435 Anorthite, ordered d=2.405Anorthite, Anorthite,ordered ordered d=2.384 d=2.380 Lindackerite

50

d=3.344 Quartz, syn

d=3.341 Lindackerite

80

d=3.052 Lindackerite d=2.951 Anorthite, ordered d=2.860 Lindackerite

90

d=4.039 Anorthite, ordered d=3.912 Anorthite, ordered d=3.779 Anorthite, ordered d=3.622 Anorthite, ordered d=3.465 Anorthite, ordered d=3.363 Anorthite, ordered d=3.259 Anorthite, ordered d=3.238 Lindackerite d=3.208 Anorthite, ordered d=3.195 Anorthite, ordered d=3.180 Anorthite, ordered d=3.156 Lindackerite

d=4.414 Lindackerite d=4.267 Lindackerite d=4.253 Quartz, syn

d=4.953 Lindackerite d=4.686 Anorthite, ordered



Cps 100

MB-4-As5000

70

60

0 70


Figure 17. Background-subtracted (Bkg  = 1, Curvature = 1) scans of MB-4-As5000 with selected d-I pattern overlays

30

20

10

40

2 10

60

50

20 30

Page 32 of 34 40 50 60

d=1.382 Quartz low, syn d=1.375 Quartz d=1.372 Quartz low, low, syn syn d=1.369 Botallackite

d=1.420 Ramsbeckite

d=1.453 Quartz low, syn

d=1.479Ramsbeckite Botallackite d=1.478

d=1.545 Owensite d=1.542 Quartz low, syn d=1.532Owensite Botallackite d=1.528 d=1.522 Ramsbeckite d=1.515 Ramsbeckite

d=1.609 Quartz low, syn d=1.599 Owensite Botallackite d=1.597

d=1.672 Quartz low, syn d=1.670 d=1.660Ramsbeckite Quartz low, syn

d=1.707 Ramsbeckite

d=1.818 Quartz low, syn d=1.817 Botallackite d=1.812 Ramsbeckite d=1.792 Ramsbeckite d=1.779 Ramsbeckite Owensite d=1.772

d=1.932 Botallackite d=1.892 Owensite

d=2.136 Ramsbeckite d=2.128 Quartz low, syn d=2.126 Ramsbeckite d=2.107 Ramsbeckite d=2.059 Botallackite d=2.029 Ramsbeckite Owensite d=1.994 Owensite d=1.984 Botallackite d=1.980 Quartz low, syn

d=2.602 Botallackite d=2.578 Botallackite d=2.574 Ramsbeckite d=2.570 d=2.558Ramsbeckite Ramsbeckite d=2.516 Ramsbeckite d=2.495 d=2.490 Botallackite d=2.481Ramsbeckite Ramsbeckite Botallackite Quartz low, syn d=2.448d=2.457 Owensite d=2.388 Ramsbeckite d=2.379 Owensite d=2.317 Botallackite Owensite d=2.308 d=2.290 Botallackite d=2.282 Quartz low, syn d=2.237 Quartz low, syn

d=2.695 Ramsbeckite

150

d=3.003 d=2.996 Ramsbeckite Owensite Ramsbeckite d=2.932Ramsbeckite Ramsbeckite d=2.911 d=2.854 Botallackite

160

d=3.344 Quartz Ramsbeckite low, syn

170

d=3.571Ramsbeckite Ramsbeckite d=3.549 d=3.504Ramsbeckite Ramsbeckite d=3.495 d=3.416 Botallackite d=3.303 Ramsbeckite d=3.290 Botallackite d=3.282 Owensite d=3.253 Ramsbeckite d=3.243 Ramsbeckite d=3.233 Ramsbeckite d=3.198 Ramsbeckite d=3.188 Ramsbeckite d=3.175 Ramsbeckite d=3.148 d=3.124 Ramsbeckite Owensite

d=4.400 Ramsbeckite d=4.258 Quartz low, syn d=4.171 d=4.137Botallackite Botallackite Ramsbeckite d=4.125 Ramsbeckite d=4.059 Ramsbeckite d=4.031 Ramsbeckite d=3.901 Ramsbeckite Botallackite d=3.897 d=3.754 Ramsbeckite

Botallackite d=5.596 d=5.705 Ramsbeckite

d=7.087 Ramsbeckite d=7.026 Ramsbeckite d=6.461 Ramsbeckite

d=8.047 Ramsbeckite

Cps 180

MB-4-Cu5000

140

130

120

110

100

90

80

70

0 70


Figure 18. Background-subtracted (Bkg  = 1, Curvature = 1) scans of MB-4-Cu5000 with selected d-I pattern overlays

20

10

2 10

30

20 30 40

Page 33 of 34 50

d=1.931 Carbonatefluorapatite d=1.926 Calcite d=1.907 Calcite d=1.887 Carbonatefluorapatite d=1.873 Calcite d=1.855 Carbonatefluorapatite d=1.834 Carbonatefluorapatite d=1.818 Quartz, syn d=1.802 Carbonatefluorapatite Quartz, syn d=1.790 d=1.783 Carbonatefluorapatite d=1.754 Carbonatefluorapatite d=1.720 Carbonatefluorapatite

d=2.021 Carbonatefluorapatite d=1.980 Quartz, syn

d=2.134 Carbonatefluorapatite d=2.128 Quartz, syn d=2.094 Calcite

d=2.284 d=2.282 Carbonatefluorapatite Calcite Quartz, syn d=2.239 Carbonatefluorapatite d=2.236 Quartz, syn

60

d=1.382 Quartz, syn d=1.375 d=1.372Quartz, Quartz,syn syn

d=1.418 Quartz, syn d=1.417 Calcite

d=1.453 Quartz, syn d=1.441 Calcite

d=1.542 Quartz, syn d=1.525 Calcite d=1.506 Calcite

d=1.626 Calcite d=1.608 Quartz, syn d=1.604 Calcite d=1.582 Calcite


40

d=2.769 Carbonatefluorapatite d=2.691 Carbonatefluorapatite d=2.619 Carbonatefluorapatite

d=2.790 Carbonatefluorapatite

d=3.344 Quartz, syn

60

d=2.507 Carbonatefluorapatite d=2.495 Calcite d=2.457 Quartz, syn

d=2.835 Calcite

d=3.160 Carbonatefluorapatite d=3.050 Carbonatefluorapatite d=3.030 Calcite

50


d=4.253 Quartz, syn d=4.039 Carbonatefluorapatite d=3.861 Carbonatefluorapatite d=3.853 Calcite



Cps

PR-4(untreated)

0 70


Figure 19. Background-subtracted (Bkg  = 1, Curvature = 1) scans of PR-4 (untreated) with selected d-I pattern overlays.

References 1. Elements of X-Ray Diffraction. B.D. Cullity. 1978. 555p. Addison-Wesley Publishing Company, Inc. 2. Principles and Applications of Powder Diffraction. Edited by A. Clearfield, J.H. Reibenspies and N. Bhuvanesh. 2008. 386p. John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK. 3. Powder Diffraction Theory and Practice. Edited by R.E. Dinnebier and S.J.L. Billinge. 2008. 582p. The Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB4 0WF, UK. 4. X-Ray and Electron Diffraction Studies in Materials Science. D.J. Dyson. 2004. 364p. Maney Publishing, 1 Carlton House Terrace, London SW1Y 5DB.

Page 34 of 34

APPENDIX B CAP STABILITY EVALUATION FOR SITE 32 AND 33 IN SITU CAP

TABLE OF CONTENTS ACRONYMS AND ABBREVIATIONS .................................................................................. iii B1.0

INTRODUCTION ........................................................................................................... 1

B2.0

OBJECTIVES ................................................................................................................. 1

B3.0

APPROACH ................................................................................................................... 2

B4.0

EVALUATION ............................................................................................................... 3 B4.1 HYDRAULIC MODEL OF THE LOST SLOUGH ............................................................ 3 B4.2 CRITICAL VELOCITY ESTIMATES ........................................................................... 7

B5.0

RESULTS ..................................................................................................................... 10 B5.1 HYDRAULIC MODELING ...................................................................................... 10 B5.2 CRITICAL VELOCITY ........................................................................................... 10 B5.3 COMPARISON OF CURRENT VELOCITY TO CRITICAL VELOCITY ............................ 10 B5.4 DESIGN CONSIDERATIONS ................................................................................... 11 B5.5 ESTIMATE OF EROSION AND SCOUR DEPTH FOR BAY MUD ................................... 13

B6.0

CONCLUSIONS ........................................................................................................... 15

B7.0

REFERENCES .............................................................................................................. 17

Appendix B, Remedial Design, In Situ Cap, Sites 32 and 33 Litigation Area, MOTCO

B-i

FIGURES B-1

Surveyed Slough Alignment

B-2

Slough Cross Sections

B-3


B-4


TABLES Table B-1. Lost Slough Main Channel Estimate Velocities......................................................... 4 Table B-2. Lost Slough Main Channel Estimate Shear Stresses .................................................. 5 Table B-3. East Tributary Velocities .......................................................................................... 6 Table B-4. West Tributary Velocities ......................................................................................... 6 Table B-5. Calculations for Critical Velocity to Initiate Movement for Cohesive Cap Material Alternatives .............................................................................................................. 9 Table B-6. Comparison of Current Velocity to Critical Velocity............................................... 12 Table B-7. Critical Shear Stresses from Sedflume Study .......................................................... 14 Table B-8. Critical Shear Stresses at Depth from Sedflume Study ............................................ 14 Table B-9. Erosion and Scour Depth for Consolidated Bay Mud at 10 cm Depth ...................... 15

ATTACHMENTS B1

Lost Slough Channel Velocity Determination

B2

Critical Velocity Calculations for Cap Material and Bay Mud

B3

Calculations for Erosion and Scour Depth for Bay Mud

Appendix B, Remedial Design, In Situ Cap, Sites 32 and 33 Litigation Area MOTCO

B-ii

ACRONYMS AND ABBREVIATIONS AEP

Annual exceedance probability

ft3/s ft/s

Cubic feet per second Feet per second

HEC-RAS

Hydrologic Engineering Center River Analysis System

kg/m3

Kilograms per cubic meters

lb/ft2

Pounds force per square feet

m MHW MLW MOTCO m/s m/sec2 m2/sec msl

Meter Mean High Water Mean Low Water Military Ocean Terminal Concord Meter per second Meter per square seconds Square meters per second Mean Sea Level

NOAA

National Oceanic and Atmospheric Administration

USGS

U.S. Geological Survey


B-iii

B1.0

INTRODUCTION

Site 32 at Military Ocean Terminal Concord (MOTCO) consists of narrow, man-made mosquito abatement ditches that were excavated into the marsh surface to reduce the amount of standing water to limit mosquito breeding habitat. The marsh surface and portions of the existing mosquito ditches were contaminated with metals from off-site sources. Site 33 consists of natural sloughs that meander through the marshland plain. Contaminated sediment transported from off-site locations has accumulated in portions of Lost Slough and in the mosquito ditches. The preferred remedial alternative at Site 32 and Site 33 is to install an in situ cap along the bottom of the mosquito ditches and the Lost Slough channel (over the bottom sediments) to isolate the elevated metal concentrations from the environment, thus preventing exposure of these contaminants to the environment and animals. In situ capping refers to placement of a cap material over contaminated sediment. Passive caps generally consist of granular material such as sand, clean sediment, or gravel. Reactive cap materials may also consist of active ingredients that can sequester or immobilize metal contaminants, creating a reliable, stable, and long-lasting cap in aquatic environments. Certain natural cap materials, such as Bay Mud, contain active ingredients such as organic matter and fine clay minerals that are able to sequester metal contaminants. An in situ cap is designed to provide long-term protection to the aquatic environment by reducing impacts from contaminated sediments by the following means: 

Physical isolation of the contaminated sediments, reducing exposure to organisms



Chemical isolation of contaminated sediment, reducing transport of dissolved contaminants into the water column



Stabilization of contaminated sediments, reducing erosional suspension and transport of the contaminated sediments.

The cap should be thick enough to effectively separate the contaminated sediments from most aquatic organisms that dwell or feed on, above, or within the cap. In addition, the in situ cap should be stable to withstand erosion or movement of cap material from the current and tidal forces in the slough and ditches. The mosquito ditches at Site 32 are tidally-influenced, and both current flow from site runoff and tidal influence affect the Lost Slough at Site 33. The overall stability of the cap at both sites will be evaluated based on predicted water velocities and the stability properties of various cap materials. B2.0

OBJECTIVES

The design objective of this evaluation is to assess the stability of the cap for erosion and movement of cap material under the influence of stormwater and tidal flows. The stability of the cap is evaluated based on whether shear stresses across the cap material caused by moving water Appendix B, Remedial Design, In Situ Cap, Sites 32 and 33 Litigation Area MOTCO

B-1

in the slough and ditches are at a level that would initiate motion of the cap. The cap stability was evaluated for the same cap materials as are in the treatability study (Appendix A). The cap materials under consideration include:    

Martinez Marina Bay Mud Aggregate gravel coated with modified clay (AquaGate) Macroporous Aluminosilicate Apatite (Mineral Apatite and Fishbone Apatite II).

The cap design considers the inherent stability of each cap material under the predicted current velocities. The stability evaluation only considered mineral apatite. The stability of the cap can be enhanced by increasing the thickness or by including an erosion-resistant armor layer B3.0

APPROACH

The cap stability design process includes the following steps: 1. Estimate current flow at Lost Slough by hydraulic modeling. The current flow in the mosquito ditches would be no more than the flows observed in the east and west tributaries of the slough. 2. Determine the critical velocity at which cap material will initiate movement. 3. Compare the estimated current flows against the critical velocity for evaluating the stability of the cap material. 4. Develop a cap design for erosion protection of any areas where the predicted current flows exceed the cap material critical velocity. The velocities through the Lost Slough were estimated using a Hydrologic Engineering Center River Analysis System (HEC-RAS) model (Attachment B1). The model extended 5,400 feet from the mouth of the slough at Suisun Bay to the Union Pacific Railroad Tracks and covers the runoff from the surrounding watershed draining into the slough. The two tributaries, identified as the East and West Tributaries, are included in the model. The mosquito ditches do not lend themselves to hydraulic modeling and were evaluated based on the tidal influence observed from the tributaries of the slough. The HEC-RAS model provided estimated current velocities through the Lost Slough for the following annual exceedance probability (AEP) flood event: 

20 percent chance of exceedance









1 percent chance of exceedance.


B-2

The expected AEP measures the annual likelihood that a flow will exceed a hydraulic target. For example, the AEP for a 100-year flood event is 0.01 or 1 percent, for a 50-year flood event is 2 percent, for a 10-year flood event is 10 percent, and for a 5 year flood event is 20 percent. The critical velocities are estimated for each cap material. The critical velocity is defined as the current velocity where the shear stress acting over the bed will begin to move the particles in the cap. The methods used to estimate the critical velocity include the expression for critical velocity (Palermo 1998), the Shields Diagram (Vanoni 1975), and the expression developed by van Rijn for fine particle beds (van Rijn 2007). These equations and curves provide the critical shear stress and flow velocity for initiation of motion along a plane bed. The critical shear stresses depend on the particle shape and size, density, water depth, and cohesive forces in clay. The flow velocities and bottom shear stresses in the Lost Slough estimated from the HEC-RAS model are compared with the calculated critical velocities and critical shear stresses. If the flow velocities are greater than the critical velocities, then there is potential for the cap material to move and erode. The cap design can be altered to compensate for potential erosion by using an armor layer of coarser or heavier material, designing the channel to reduce the water velocity, or placing additional material to consolidate the cap material to increase the resistance to erosion. B4.0

EVALUATION

This section presents the hydraulic model evaluation flow velocities and compares the result with the critical velocities for each cap material under consideration. B4.1

HYDRAULIC MODEL OF THE LOST SLOUGH

The hydraulic model of the Lost Slough is documented in Attachment B1; this section summarizes the model evaluation and results. The hydraulic model was created using HEC-RAS software version 4.1. Lost Slough was surveyed in support of the 2006 treatability study and supplemental feasibility data gaps technical memorandum at the Litigation Area (SulTech 2006). The elevations and cross sections from this study were used in the model. Inflows to the Lost Slough were developed for the 20-, 10-, 2-, and 1-percent chance of exceedance. Published U.S. Geological Survey (USGS) regional regression equations for the Central Coast Region were used to estimate the peak discharges for each event. The HEC-RAS model takes into account the tidal action basing the tide levels on the Tidal DATUM Report for Port Chicago, Suisun Bay, which was obtained from the National Oceanic and Atmospheric Administration (NOAA). Table B-1 summarizes the flow velocity estimates, and Table B-2 summarizes the shear stresses from the HEC-RAS Model for Mean High Water (MHW), Mean Sea Level (MSL), and Mean Low Water (MLW) Level at various sections along the main channel of the slough, as shown on Figure B-1 through B-.


B-3

TABLE B-1. LOST SLOUGH MAIN CHANNEL ESTIMATE VELOCITIES Remedial Design Report, In Situ Cap at Sites 32 and 33 Litigation Area, MOTCO, Concord, California Velocity for Annual Exceedance Probability Flood Event (ft/s) Tide

20%

10%

2%

1%

Mean High Water

0.3

0.3

0.5

0.5

Mean Sea Level

0.7

0.8

1.0

1.1

Mean Low Water

1.2

1.5

1.8

1.9

Mean High Water

0.5

0.6

0.8

0.9

Mean Sea Level

1.1

1.3

1.7

1.8

Mean Low Water

1.7

2.0

2.5

2.6

Mean High Water

0.9

1.1

1.4

1.5

Mean Sea Level

2.4

2.7

3.2

3.3

Mean Low Water

3.4

3.7

4.0

4.1

Mean High Water

1.4

1.5

1.8

1.9

Mean Sea Level

2.8

3.1

3.3

3.2

Mean Low Water

3.1

3.3

3.6

3.5

Mean High Water

1.9

2.1

2.6

2.7

Mean Sea Level

3.7

3.9

3.8

3.9

Mean Low Water

4.0

4.1

4.1

4.1

Section A

Section B

Section C

Section F

Section G

Notes: Sections listed in the table refer to the cross section located on Figure B-1. ft/s Feet per second


B-4

TABLE B-2. LOST SLOUGH MAIN CHANNEL ESTIMATE SHEAR STRESSES Remedial Design Report, In Situ Cap at Sites 32 and 33 Litigation Area, MOTCO, Concord, California Shear Stress for Percent Chance 2 Exceedance Event (lb/ft ) Tide

20%

10%

2%

1%

0

0

0

0

Mean Sea Level (MSL)

0.02

0.03

0.04

0.04

Mean Low Water (MLW)

0.07

0.09

0.1

0.1

0

0

0.01

0.01


0.03

0.05

0.07

0.08


0.09

0.11

0.13

0.14

Mean High Water (MHW)

0.01

0.02

0.03

0.03


0.16

0.18

0.21

0.22


0.19

0.21

0.23

0.23


0.03

0.04

0.05

0.05


0.13

0.15

0.16

0.18


0.13

0.15

0.17

0.19


0.05

0.06

0.09

0.09


0.23

0.24

0.22

0.21


0.23

0.24

0.22

0.21

Section A Mean High Water (MHW)

Section B Mean High Water (MHW)

Section C

Section F

Section G

Notes: Sections listed in the table refer to the cross section located on Figure B-1. lb/ft2 = Pounds-force per square feet

Table B-3 and B-4 provide the velocity estimates for the East and West Tributaries to the Lost Slough. The velocities in the tributaries are lower than the main channel and range from 0.21 feet per second (ft/s) to 0.99 ft/s at mean sea level tide. Generally, the velocities are below 1 foot per second for all events and tides. As a result of the low velocities, the shear stresses for the East and West Tributaries are less than 0.1 pounds force per square feet (lb/ft2) for all cross sections.


B-5

TABLE B-3. EAST TRIBUTARY VELOCITIES Remedial Design Report, In Situ Cap at Sites 32 and 33 Litigation Area, MOTCO, Concord, California Velocity for Annual Exceedance Probability Flood Event (ft/s) Tide

20%

10%

2%

1%

Mean High Water

0.24

0.23

0.21

0.21

Mean Sea Level

0.42

0.38

0.32

0.31

Mean Low Water Section E

0.56

0.45

0.36

0.34

Mean High Water

0.37

0.36

0.34

0.32

Mean Sea Level

0.7

0.6

0.5

0.47

Mean Low Water

0.99

0.76

0.57

0.53

Section D


TABLE B-4. WEST TRIBUTARY VELOCITIES Remedial Design Report, In Situ Cap at Sites 32 and 33 Litigation Area, MOTCO, Concord, California Velocity for Annual Exceedance Probability Flood Event (ft/s) Tide

20%

10%

2%

1%

Mean High Water

0.27

0.26

0.23

0.22

Mean Sea Level

0.33

0.3

0.25

0.24

Mean Low Water Section I

0.35

0.31

0.25

0.24

Mean High Water

0.25

0.23

0.21

0.2

Mean Sea Level

0.32

0.28

0.22

0.21

Mean Low Water Section J

0.34

0.29

0.23

0.21

Mean High Water

0.35

0.33

0.28

0.26

Mean Sea Level

0.5

0.41

0.31

0.29

Mean Low Water Section K

0.54

0.43

0.32

0.29

Mean High Water

0.51

0.47

0.4

0.37

Mean Sea Level

0.74

0.61

0.44

0.41

Mean Low Water

0.8

0.64

0.47

0.41

Section H



B-6

B4.2

CRITICAL VELOCITY ESTIMATES

Various researchers have provided means of estimating the critical shear stresses and velocity for particles on a plane bed. This evaluation used the following two methods for the large cap materials:  

Expressions for Critical Velocities for a Plane Bed (Palermo 1998) Shields Diagram for Initiation of Movement (Vanoni 1975)

The expression for critical velocity, ucr, as described by van Rijn, is defined as a function of grain size distribution and water depth as: (

)

(

)

for 0.0001 ≤ d50 ≤ 0.0005 m (

)

(

)

for 0.0005 ≤ d50 ≤ 0.002 m The Shields Diagram below was used to estimate the critical shear stress based on the particle Parameter Diameter D*, which is given by; (


(

)

B-7

)

The critical bed shear stress can be calculated from the dimensionless Critical Shields Shear Stress (mobility parameter). The friction velocity resulting from the critical shear stress and the corresponding critical current velocity can be estimated by the expressions below: √

and

√

Definition of Terms ucr d50 d90 τ b, cr h s g ν

− − − − − − − − −

C

− Chezy coefficient for bed roughness (

Friction velocity (m/s) Critical current velocity (m/s) Median grain size or the 50th percentile grain size (m) 90th percentile grain size (m) The critical shear stress on the bed that would initiate movement of particles Water depth (m) Specific gravity (unitless) Acceleration of gravity (m/sec2) Kinematic viscosity of water (m2/sec) Density of water (kg/m3) √

)

The calculations for the critical shear stresses and velocities for the cap materials (pelletized bentonite clay, macroporous aluminosilicate, and mineral apatite are presented in Attachment B2. The Bay Mud is a very fine silt and clay and develops cohesive properties when consolidated in an estuary environment. Van Rijn developed cohesive factors to take into account these effects (Attachment B3). The calculations for the critical shear stress and velocity for Bay Mud are presented in Attachment B3. Table B-5 provides the results of the calculations for critical velocity based on the expressions developed by van Rijn and the results for the critical velocity based on the Shields Diagram for the noncohesive cap materials. The water depth in the slough was assumed to be 1 meter in estimating the critical velocities.


B-8

TABLE B-5. CALCULATIONS FOR CRITICAL VELOCITY TO INITIATE MOVEMENT FOR COHESIVE CAP MATERIAL ALTERNATIVES Remedial Design Report, In Situ Cap at Sites 32 and 33 Litigation Area, MOTCO, Concord, California

Properties

Critical Velocity based on Mathematical Expressions

Critical Velocity based on Shields Diagram

Specific Gravity (Unitless)

50th Percentile Grain Size (meter)

Critical Velocity (m/s)

Critical Velocity (ft/s)

Critical Velocity (m/s)


s

d50

ucr

ucr

ucr

ucr

Martinez Marina Bay Mud

2.78

0.000002

0.27

0.89

0.25

0.83

AquaGate

3.39

0.00669

1.05

3.44

1.36

4.47

Apatite

2.12

0.00058

0.33

1.08

0.292

0.958


3.64

0.001

0.45

1.48

0.582

1.91

Sand

2.65

0.005

0.92

3.0

1.0

3.3

Material

Notes: d50 ft/s m/s s ucr

Median grain size or the 50th percentile grain size in meters (m) Feet per second Meter per second Specific Gravity Critical Velocity


B-9

B5.0

RESULTS

This section discusses the results of the hydraulic model and the critical velocities. The critical velocities are compared with the estimated current velocities in the slough during flood events to assess the stability of the cap material. B5.1

HYDRAULIC MODELING

The hydraulic model results indicated that the slough channel would overflow into the marsh plain during the 1 percent and 2 percent AEP. Therefore, the full flow of a 100-year or 50-year flood event would not increase the flow through the slough. The HEC-RAS model included a lateral weir at Section G to mimic the overflow and loss of water to the marsh plain. The results reflect this circumstance with the non-increasing velocity for 1 percent and 2 percent AEP. In addition, there is a strong tidal influence on the current velocities, resulting in a dampening effect during high tide. The velocities during mean low water level in the main slough channel range from 0.7 to 4.1 ft/s. The velocities in the East and West Tributaries are significantly less than in the main channel since flow in these tributaries is the result of backwater from the main channel. The velocities in the tributaries decrease during the 1 percent and 2 percent AEP as the channel backs up from the high flows. The tidal influence farther inland, as represented by the West Tributary, is minor, which is visible from the small increase in velocity between the tides. B5.2

CRITICAL VELOCITY

The critical velocity that would initiate movement of the cap particles varied from 0.83 ft/s for the smaller Bay Mud and up to 4.47 ft/s for the AquaGate material. Both methods of estimating the critical velocity resulted in consistent values, indicating the appropriate use of the methods. B5.3

COMPARISON OF CURRENT VELOCITY TO CRITICAL VELOCITY

Table B-6 compares the estimated current velocities at 1 percent AEP event during the mean low water level tide. As shown in Table B-6, the current velocity is estimated at 3.5 ft/s through Section F and 4.1 ft/s through Section G, which would result in movement of most material, with the exception of AquaGate. For the reasons summarized in this remedial design report and in the treatability study of this report (Appendix A), the preferred cap material is the Martinez Marina Bay Mud. The current velocity through Section F and Section G is estimated to be greater than the critical velocity of Bay Mud, resulting in potential movement of the Bay Mud as a cap material. A further evaluation of the amount of erosion and consideration of the cohesive and consolidation properties of Bay Mud is conducted in Section B5.5. The current velocity through the East and West Tributaries is below the critical velocity of Bay Mud and should not experience significant erosion. Section F and Section G are in the main channel of the slough (Figure B-1). Although the mosquito network could not be accurately modeled, the velocities in the mosquito ditches are Appendix B, Remedial Design, In Situ Cap, Sites 32 and 33 Litigation Area MOTCO

B-10

expected to be similar to or less than the velocities seen in the tributaries of the slough. The main source of flow in the ditches is from tidal influence, which is the main contributor of the flow in the tributaries. B5.4

DESIGN CONSIDERATIONS

Bay Mud has shown to be a cost-effective cap material for providing physical and chemical isolation of the contaminated sediments from the benthic community and is the recommended cap material. The current velocity through the main section of the Lost Slough may cause erosion of the Bay Mud material during a significant flood event. Refer to Attachment B3 for the evaluation of cap erosion and the increased design thickness to provide a consolidated cap of Bay Mud that will resist erosion. The amount of erosion and scour depth for Bay Mud exposed to the estimated shear stresses are estimated in this section. The mosquito ditches could not be modeled and are mainly under tidal influence. Based on the results for the East and West Tributaries, the current velocities are expected to be minor and less than the critical velocity for Bay Mud.


B-11

TABLE B-6. COMPARISON OF CURRENT VELOCITY TO CRITICAL VELOCITY Remedial Design Report, In Situ Cap at Sites 32 and 33 Litigation Area, MOTCO, Concord, California

Material


Critical Velocity from Shields Diagram (ft/s)

Highest Current Velocity at Mean Low Water Sea Level Tide (ft/s) Martinez Marina Bay Mud

Estimated Current Velocity Compared to Critical Velocity of Material (ft/s) Section F

Section G

West Channel

East Channel

3.5

4.1

0.8

0.8

0.89

0.85

Above

Above

Below

Below

3.44

4.47

Within Range

Within Range

Below

Below

Apatite

1.08

0.958

Above

Above

Below

Below


1.48

1.91

Above

Above

Below

Below

Fine Sand

0.97

1.29

Above

Above

Below

Below

Medium Sand

2.01

Above

Above

Below

Below

Coarse Sand

3.02

2.1 3.31

Above

Above

Below

Below

4.05

4.23

Below

Within Range

Below

Below

AquaGate

Fine Gravel Note: ft/s

Feet per second


B-12

B5.5

ESTIMATE OF EROSION AND SCOUR DEPTH FOR BAY MUD

Attachment B3 provides the calculations for the erosion and scour depth for the Bay Mud. The erosion depends on site-specific properties as well as the bottom shear stress and critical shear stress of the Bay Mud. The bottom shear stresses in the Lost Slough were estimated using the HEC-RAS model values as well as the quadratic stress equation with the current velocities in the Lost Slough estimated from the HEC-RAS model. The shear stresses estimated by the HECRAS model do not take into account the cohesive and flat bottom bed that is characteristic of the site, which is the rationale for also evaluating the shear stress based on the quadratic stress equation. Both values of shear stress will be used to estimate the erosion of the Bay Mud. One estimate of the critical shear stress for Bay Mud is based on an empirical calculation for cohesive binding forces developed by van Rijn (Attachment B3). The critical shear stress for Bay Mud from empirical equation calculation is estimated at: τcr = 0.0981 N/m2 or 0.981 dynes/cm2 Another way to evaluate critical shear stress is by direct measurement. A Sedflume study was conducted for USACE San Francisco by Sea Engineering on Bay Mud from San Pablo Bay, which would be similar material as the Bay Mud at Martinez Marina. The Sedflume study provides an opportunity to look at site-specific critical shear stress at different depths for Bay Mud. Site-specific Sedflume studies are more accurate estimates of critical shear stress than the empirical equations that have been developed by researchers. The critical shear stress for Bay Mud is based is the value calculated from the empirical equations for cohesive materials and the Sedflume study. The Sedflume study directly measures critical shear values at various depth of a sediment core. The study evaluated three cores from around the San Pablo Bay. Table B-7 provides the critical shear stress results and bulk density at the varying depths within the sediment core from the Sedflume study.


B-13

TABLE B-7. CRITICAL SHEAR STRESSES FROM SEDFLUME STUDY Remedial Design Report, In Situ Cap at Sites 32 and 33 Litigation Area, MOTCO, Concord, California Core SP-1

Core SP-2

Core SP-3

Depth

D50

ρb

τcr

Depth

D50

ρb

τcr

Depth

D50

ρb

τcr

cm

µm

g/cm^3

N/m^2

cm

µm

g/cm^3

N/m^2

cm

µm

g/cm^3

N/m^2

0

13.26

1.37

0.26

0

9.69

1.47

0.13

0

11.88

1.28

0.12

5.7

10.11

1.37

0.91

6.9

10.37

1.40

0.32

9.4

9.28

1.37

0.32

10

12.21

1.46

1.92

13.2

10.76

1.39

0.64

12.1

8.5

1.38

0.92

16

10.61

1.35

1.74

21

10.73

1.39

0.84

16.2

9.72

1.36

1.76

21

10.92

1.38

2.56

27

7.28

1.32

0.92

20.7

8.28

1.43

2.08

Mean

11.42

1.39

1.48

Mean

9.77

1.39

0.57

Mean

9.53

1.36

1.04

Notes: D50

Median particle diameter

ρb τcr

Bulk density Critical shear stress

cm µm 3 g/cm

Centimeter Micrometer Grams per cubic centimeters

N/m2

Newton per square meter

As noted form the Sedflume study, the critical shear stress increases substantially with depth. Cohesive materials such as Bay Mud consolidate with depth, increasing the critical shear stress. The critical shear stress at the surface is the same order of magnitude as the empirically calculated shear stress, but the shear stress of the consolidated material is an order of magnitude higher. To assess the stability of a Bay Mud cap, erosion of the first 10 centimeters will be allowed and then the stability and erosion will be evaluated based on the observed critical shear stress at 10 centimeters or less. Table B-8 summarizes the critical shear stress at depth from the Sedflume Study. TABLE B-8. CRITICAL SHEAR STRESSES AT DEPTH FROM SEDFLUME STUDY Remedial Design Report, In Situ Cap at Sites 32 and 33 Litigation Area, MOTCO, Concord, California

Sample Core SP-1 SP-2 SP-3 Mean Value

Core Depth (cm) 10 6.9 9.4 8.8

Critical Shear 2 Stress (N/m ) 1.92 0.32 0.32 0.853

Notes: cm N/m2 dynes/cm2

Centimeter Newtons per square meter Dynes per square centimeter


B-14

Critical Shear Stress 2 (dynes/cm ) 19.2 3.2 3.2 8.53

Two methods were used to evaluate the erosion and scour depths. The first method used the bottom shear stress estimated from the HEC-RAS model, and the other method estimated the bottom shear stress from the current velocity of the water in the slough. Table B-9 provides the results of the calculations. TABLE B-9. EROSION AND SCOUR DEPTH FOR CONSOLIDATED BAY MUD AT 10 CENTIMETER DEPTH Remedial Design Report, In Situ Cap at Sites 32 and 33 Litigation Area, MOTCO, Concord, California Estimations using Quadratic Stress Expression Max Bottom Shear Max. Scour Stress Erosion Depth dynes/ 2 2 2 cm lbs./ft mg/cm cm

Estimations at 1% AEP at MLW Bottom Shear Max Stress (From HEC Max. Scour Model Results) Erosion Depth mg/ dynes/ 2 2 cm2 cm cm lbs./ ft .

Velocity for 1% AEP at MLW

Velocity for 1% AEP at MLW

feet/sec

cm/sec

Section F

3.5

107

68

0.14

120

0.12

91

0.19

300

0.30

Section G

4.0

122

89

0.19

280

0.28

101

0.21

410

0.41

Section of Slough and Ditches

Notes: Cm

Centimeter

cm/sec

Centimeter per second

dynes/cm2

Dynes per square centimeter

Feet/sec

Feet per second

Lbs./ft2

Pounds per square feet

mg/cm2

Milligrams per square centimeter

As shown in Table B-9, the scour depth of the consolidated Bay Mud at a depth of greater than 10 centimeters is at most 0.41 centimeter (less than 0.25 inches). B6.0

CONCLUSIONS

Based on this evaluation, the design of the in situ cap at Sites 32 and 33 is recommended to include the following components: 

The cap material should consist of Bay Mud, which provides a cost-effective material while meeting the physical and chemical isolation requirements of the cap.



Taking into consideration of the consolidated Bay Mud’s critical shear stress at -4 inch (10-centimeter) depth, the Bay Mud Cap would be stable with minimal erosion during an extreme storm event.



An additional 4 inches of Bay Mud layer is recommended to account for the eventual erosion of the unconsolidated top layer of the Bay Mud above 4 inches (10 centimeters) within the main channel of the Lost Slough. As this material erodes, the lower layer shear stresses will be substantially higher and result in minimal erosion.


B-15



No appreciable erosion is expected to occur within the east and west tributaries or the mosquito ditches, so the design thickness of the bay mud cap in these reaches need not be increased above the thickness required for to provide chemical and physical isolation.


B-16

B7.0

REFERENCES

Brater, E. and King, H.W. 1976. Handbook of Hydraulics, McGraw Hill. Palermo, M.R., and others. 1998. “Guidance for Subaqueous Dredged Material Capping.” U.S. Army Corps of Engineers Waterways Experiment Station. SulTech. 2006. “Treatability Study and Supplemental Feasibility Study Data Gaps Study technical Memorandum at the Litigation Area, Naval Weapons Station Seal Beach Detachment Concord, Concord, California.” 23 February Vanoni, V.A. 1975. “Sedimentation Engineering.” ASCE Manuals and Reports on Engineering Practice – No. 54.SulTech, 2006. van Rijn L.C. 2007. “Unified View of Sediment Transport by Currents and Waves I: Initiation of Motion, Bed Roughness, and Bed-Load Transport.” Journal of Hydraulic Engineering. June. U.S. Bureau of Reclamation (USBR). 2001. Water Measurement Manual.


B-17

FIGURES

SUISU Suisun Bay 2.8

2.9 3.0

3 3.

3.0 3.1

3.1 3.1

3.3

3.0

3.2

4 3.

3.2

3 .5

3.6

3. 7

4.0 4.5

3.8

5.0

3.9

White R d.

3.4 3.3 3.2 0 4.

A

3.1

3. 4

2005 Lost Slough Alignment

Rd.

3.0

Stevens

RASS Boundary 3.1

Cross Section Location Mosquito Ditch

3.3 3.2

3. 2

3.1

B 2

.7

8 2.

L

Potential Location of Slough Check Dam

3.

0

2.9

4 .0

5.0

2.9

C

3.0

K

Railroad

2.9

RASS 1

Ground Surface Elevation Contour

UNIT 9 Slough

UNIT 10 Slough UNIT 11 Slough

3.1

E 3.0

D RO1SH077

0 3.

NOTES: 1. ELEVATION CONTOURS RELATIVE TO NATIONAL GEODETIC VERTICAL DATUM OF 1929. 2. CROSS SECTIONS SHOWN ON FIGURES 2, 3 AND 4.

3.1

3.1

3.0

3.3 3.5

2.9

3.7

3.9

3.1

F

J

2.9

3.1 3.2

TIDAL MONITORING

3.8

4 3.

8 2.

H 2. 9

Approximate Location of Fallen Tree

( !

N

3.3

STATION

I 3.2

3. 6

3. 4

3. 0

0 3.5

3.0

600

Feet

3.6

3.0

3.0

300

3.

7

3.3 3. 1

3.2

G

3.4

3. 0

4. 0

3.5

3.0

3.6 3. 7 3.8

ac ifi c

ther n

RASS 3

Fe R ailr o ad

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TtEMI-OAK

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MILITARY OCEAN TERMINAL CONCORD

5.0

RASS 2 Unio n

6.0

5.0

Rail road

San ta

3.0

N or

4.0

gton

Unio nP

2011-12-20

3.9 4.0

4. 0

Bur lin

3.8 3.9

Pac

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5.5

6.0

FIGURE B-1 SURVEYED SLOUGH ALIGNMENT ic Railroad Union Pacif

Treatability Study and Supplemental Feasibility Study Data Gaps Technical Memorandum

B-2

B-3

B-4

APPENDIX E FIELD INVESTIGATION MEASUREMENTS