Proposed Sampling and Analysis Plan for Sediment and Soil Characterization at Fletcher’s Cove along the Potomac River
I. Introduction Fletcher’s Cove is located on the Potomac River about 2.5 miles upstream of Theodore Roosevelt Island in Washington, DC. The cove area is part of the C&O Canal National Historical Park and a recreational portion for river enthusiasts throughout the region. While natural sedimentation in the cove has likely been a continuous process for hundreds of years, the deposited sediment has been subjected to scour during higher flow events on a periodic basis up to the 1960s, based on the bank elevations just upstream of the cove. This scour has kept the cove from filling with sediment. In the 1960s, the area upstream of the cove was used for the placement of fill from a construction project (8-‐10 feet deep along a 3-‐acre portion) along the upstream shoreline that redirected the high flows and prevented the periodic scour of the cove. A smaller area at the southern end of the cove was also filled as part of the change in the shoreline. Subsequently, the annual deposition of sediment increased dramatically and the depth of the cove has been adversely impacted, requiring dredging on two separate occasions to remediate the sediment accumulation, restore access to the cove, and restore the recreation uses (Figure 1).
Fletcher’s Cove Comparison on 1955 and 2007 Aerial Photographs Extent of Siltation is Clearly Visible
195The Point 1955
2007
Dock
Dock
Filled areas 2007
Figure 1. Comparison of Fletcher’s Cove before and after the fill placed in the area upstream of the cove. The area in the 1955 photo shown in “yellow” was overtopped during high-‐flow events and scoured previously deposited sediment from the river.
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II. Problem Characterization Currently, there are two issues that require additional data for decision-‐making. First, the sedimentation at the cove has progressed to the point of interfering with the intended uses for river access and recreation. This will require a short-‐term dredging solution while longer term plans are formulated and discussed among the stakeholders. The sediment present in the cove requires sampling and analysis of physical and chemical characteristics to assess potential disposal locations for the dredged material. Second, in order to address potential alternatives to the periodic dredging, the physical and chemical composition of the fill area that has resulted in the excess sedimentation and need for periodic dredging also requires characterization. While it is not anticipated that the fill area is contaminated with hazardous substances, the characterization is a necessary part of the initial scoping activity for alternatives to periodic dredging. For example, one alternative would involve the removal of the fill and river shoreline restoration to permit high-‐flow cove scouring to maintain the intended uses, without the need for periodic dredging. The characterization of the fill will allow conceptual discussions of alternatives to proceed on a more defined path. If the characterization determines the presence of hazardous substances in the fill, the alternatives will be more complicated, expensive, and difficult to implement. This would be a different pathway than that with an uncontaminated fill that only requires, in simple terms, the movement of material from the immediate portion of the shoreline that has resulted in the siltation problem at the cove. Both pathways are more complicated as the restoration would require an analysis of sediment transport and predicted sedimentation for any proposed alternative for restoring the cove. A part of the preliminary characterization of the two environments, the fill soils and the cove sediments, this proposal provides a strategy for filling important data gaps that will lead to more focused planning and analysis of alternatives for the future. III. Proposed Sampling Strategy for Sediment Characterization at the Cove Analysis of dredging for the cove typically requires a consideration of the sediment removal process, releases of any contaminants, dredged material disposal, and a host of other concerns such as public safety, completion time, impacts of sediment resuspension on downstream environmental resources, transport of dredged material, and equipment access. Since dredging has been utilized in the past to restore access to the cove, although for a limited time, the feasibility as part of an initial evaluation is not necessary. The chemical and physical characterization of the sediment is needed, however, to address data gaps. The sampling program is designed to address the horizontal and vertical extent of the deposited sediments in the cove. The physical analysis of particle sizes and the chemical analysis will address any concerns related to disposal locations for the dredged material. The sampling and analysis program will collect a variety of information to proceed to the next decision point for the dredging project, namely, a more detailed description of the dredging environment, including items such as the extent, disposal, and access issues. If contaminated sediments are present in the cove above acceptable
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limits, then the next phase of the analysis of dredging may be more complicated. Regardless, the sediments must be characterized. Information to be collected or considered during the sediment sampling includes: • Sample locations and contingency locations. • Sample coordinates, compatible with GPS navigation systems. • Positioning method and accuracy (vertical and horizontal). • Method of establishing water surface elevation during sampling. • Method of establishing depth of water to mudline during sampling. • Number of samples. • Sampling method (cores or grab samples) and equipment. • Method to establish elevation of mud line during sampling. • Sample containers and preservation. • Depth and/or length of samples. • Decontamination procedures. • Compositing intervals and method. • Packaging, labeling, shipping and handling, and chain of custody. • Chemical analytes. • Physical and engineering properties to be tested. • Analytical procedures, sample cleanup, extraction methods, holding times, and required detection limits. • Applicable environmental criteria (for determination of DL requirements and comparison of resulting data). • Data analysis and reporting. • Management and disposal of samples. At present, the occurrence of contaminants in the bulk sediment is unknown. Consequently, a more broad approach is needed to assess the potential presence of “problem contaminants” that would require the next level of management actions. The broad approach requires analytical testing using several methods to characterize the sediments for metals, volatile organic compounds, semi-‐volatile organic contaminants, pesticides, total petroleum hydrocarbons (TPH), PCBs, and dioxins/furans. The success of this step rests heavily on a broad analysis of a spectrum of chemicals at environmentally relevant concentrations. The determination of so-‐called “bulk sediment chemistry,” the concentration of contaminants in the sediments on a dry-‐weight basis or on an organic-‐carbon normalized basis, are important components for determining how dredged sediment may need to be managed. This point in the sediment characterization requires only that sediment chemistry be addressed along with physical characteristics and not the more complicated issues such as contaminants in biota and factors that might affect contaminant mobility, or other relevant environmental concerns. Obviously, if contaminants are detected at concentrations that are of environmental concern, then more comprehensive characterization may be required. The outcome of this sediment characterization should define the nature of any sediment contamination and a list of contaminants-‐of-‐concern (COC), if they are present, and whether they
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are found above disposal requirements or are sufficiently bioavailable as to preclude in-‐water disposal or shoreline use of dredged material for fill. The proper identification of COCs is necessary for an accurate assessment of potential impacts and management alternatives. The contaminants found in the sediment samples will be carefully considered as part of the overall strategy for dredging the cove. Sample Locations. The cove has been sectioned using a grid approach with samples on 100-‐foot centers, as shown in Figure 2. At each grid point location, sediment will be collected from the full depth of the sediment (6-‐10 feet, or deeper), examined for physical changes in the deposition appearance, and divided into two-‐foot sections. Each of these sections will be sub-‐sampled to prepare a composite samples at each location. Each of these sections will be saved for potential future analysis based on the results of a composite sampled at each point. A composite sample will be prepared representing each of the rows of the E-‐W Transects (6 total samples – S1A, S1S2B, S1S2C, S1S2D, S1S2E, S2F). Chemical Analysis. Chemical analysis of sediment will include a variety of chemical analysis methods to assess the concentrations of a broad list (TCL-‐toxic compound list) of potential contaminants, including • Metals: Arsenic, Barium, Cadmium, Chromium, Copper, Lead, Nickel, Selenium, Silver and Zinc • Mercury • Volatile Organic Compounds (VOCs) • Semi-‐Volatile Organic Compounds (SVOCs) • Pesticides • Polychlorinated Biphenyls (PCBs) • Dioxins/Furans (2 samples) • Total Petroleum Hydrocarbons – Diesel Range Organics (TPH-‐DRO) • Total Organic Carbon • Total Solids Samples will be analyzed for the total concentrations and leachability using the Toxicity Characteristic Leaching Procedure (TCLP) test for TCLP listed metals, VOCs, and SVOCs only (See attached quotation for both sediments and soil analyses in Appendix A). Physical Analysis. Physical analysis will be conducted and include grain size distribution and percent clay-‐silt-‐sand for assessing potential disposal.
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3/24/15, 10:17 AM
Fletcher’s*Cove*Location*Map* and*Proposed*Soil*Boring*and*Sediment*Sample*Locations* * N-S Transects in North Fill Area ~150 ft. spacing except T2A and T4B (75 ft N-S) T1 T2 T3 T4 T5 A
C
0*
N-S Sediment Transects 100 ft. spacing
S1
D
S2 A
B
E E-W Transects ~100 ft. spacing
E-W Transects in North Fill Area
B
N-S Transect in South Fill Area
T6
C
D
E
F
Fletcher’s Cove G
*
* Legend* Fill Area Soil Boring Grid Sediment Sampling Grid Sample Location
Figure 2. Locations for the collection of sediment and soil samples at Fletcher’s Cove.
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IV. Proposed Sampling of the Soils in the Fill Area Analysis of the fill area for excavation and disposal typically requires a consideration of the excavation process, releases of any contaminants to the river, excavated material disposal, and a host of other concerning such as public safety, completion time, impacts of runoff on downstream environmental resources, transport of soils, and equipment access. The chemical and physical characterization of the soil is needed to address an important data gap. The sampling program is designed to address the horizontal and vertical extent of the deposited fill. The physical analysis of particle sizes and the chemical analysis will address any concerns related to feasibility of the removal alternative and disposal locations for these soils. The sampling and analysis program will collect a variety of information to proceed to the next decision point for the project, namely, a more detailed description of the soils environment, including items such as the extent of contamination, disposal, and access issues. If contaminated soils are present in the fill area above acceptable limits, then the next phase of the analysis of Fletcher’s Cove restoration may be more complicated. Regardless, the soils must be characterized. Information to be collected or considered during the soil sampling includes: • Sample locations and contingency locations. • Sample coordinates, compatible with GPS navigation systems. • Positioning method and accuracy (vertical and horizontal). • Number of samples. • Sampling method (cores or grab samples) and equipment. • Sample containers and preservation. • Depth and/or length of samples. • Decontamination procedures. • Compositing intervals and method. • Packaging, labeling, shipping and handling, and chain of custody. • Chemical analytes. • Physical and engineering properties to be tested. • Analytical procedures, sample clean-‐up, extraction methods, holding times, and required detection limits. • Applicable environmental criteria (for determination of DL requirements and comparison of resulting data). • Data analysis and reporting. • Management and disposal of samples. At present, the presence of contaminants in the bulk soils is unknown. Consequently, a more broad approach is needed to assess the potential presence of “problem contaminants” that would require the next level of management actions. The broad approach requires analytical testing using several methods to characterize the soils for metals, volatile organic compounds, semi-‐ volatile organic contaminants, TPH, pesticides, PCBs, and dioxins/furans. The success of this step rests heavily on a broad analysis of a spectrum of chemicals at environmental relevant concentrations. The determination of so-‐called “bulk soil chemistry,” the concentration of contaminants in the soils on a dry-‐weight basis or on an organic-‐carbon normalized basis, are
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important components for determining how excavated soils may need to be managed. This point in the soils characterization requires only that soils chemistry be addressed along with physical characteristics and not the more complicated issues such as contaminants in terrestrial biota and factors that might affect contaminant mobility, or other relevant environmental concerns. Obviously, if contaminants are detected at concentrations that are of environmental concern, then more comprehensive characterization may be required. The outcome of this soils characterization should define the nature of any soil contamination and a list of contaminants-‐of-‐concern (COC), if they are present and whether they are found above disposal requirements or are sufficiently bioavailable as to require more complicated excavation and disposal methods. The proper identification of COCs is necessary for an accurate assessment of potential impacts and management alternatives. The contaminants found in the soil samples will be carefully considered as part of the overall strategy for restoring the cove. Sample Locations. The North Fill Area has been sectioned using a grid approach with samples on mostly 150-‐foot centers, as shown in Figure 2, while the South Fill Area has a single transect roughly north-‐south with 100-‐foot sample spacing. At each sample location, soils will be collected from the full depth of the fill (6-‐12 feet), examined for physical changes in the fill appearance, and divided into two-‐foot sections. Several locations are outside of the suspected fill area and are collected to provide an indication of concentrations in natural soils and the transition between fill and natural soils. Each of these sections will be sub-‐sampled to prepare a composite samples at each location. Each of these sections will be saved for potential future analysis based on the results of a composite sampled at each point. A depth-‐composite sample will be prepared representing each of the points along the N-‐S and E-‐W Transects (12 total samples in the North Fill Area – T1A, T2A, T1A, T2B, T3B, T4B, T2C, T3C, T4C, T3D, T4D, and T4E; 4 total samples in the South Fill Area – T6D, T6E, T6F, and T6G ). Chemical Analysis. Chemical analysis of sediment will include a variety of chemical analysis methods to assess the concentrations of a broad list (TCL-‐toxic compound list) of potential contaminants, including • Metals: Arsenic, Barium, Cadmium, Chromium, Copper, Lead, Nickel, Selenium, Silver and Zinc • Mercury • Volatile Organic Compounds (VOCs) • Semi-‐Volatile Organic Compounds (SVOCs) • Pesticides • Polychlorinated Biphenyls (PCBs – 3 samples) • Dioxins/Furans (3 samples) • Total Petroleum Hydrocarbons – Diesel Range Organics (TPH-‐DRO) • Total Organic Carbon • Total Solids
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The samples will be analyzed for the total concentrations and the 8 samples (selected in the field) will be analyzed for leachability using the Toxicity Characteristic Leaching Procedure (TCLP) test for TCLP listed metals, VOCs, and SVOCs only. Physical Analysis. Physical analysis will be conducted by the geotechnical subcontractor for the project and include grain size distribution and percent clay-‐silt-‐sand for assessing potential disposal. V. Data Analysis and Report Production Results of the sampling will be used to provide needed data to evaluate potential dredging and excavation of fill, including the COCs, if any, naturally occurring substances that may be harmful to biota, urban and agricultural runoff chemicals, spills of oil, or other chemicals. Other information may be used, if available, to further examine potential problems, including: 1. Results of prior physical, chemical, and biological tests and monitoring of Potomac River sediments. 2. Information describing the source of the fill material to be excavated which would be relevant to the identification of potential COC. 3. Existing data contained in files of agencies such as EPA or USACE or otherwise available from public or private sources. Examples of sources from which relevant information might be obtained include: • Selected Chemical Spill Listing (EPA) • Pesticide Spill Reporting System (EPA) • Pollution Incident Reporting System (United States Coast Guard) • Identification of In-‐Place Pollutants and Priorities for Removal (EPA) • Hazardous waste sites and management facilities reports (EPA) • USACE studies of sediment pollution and sediments • Federal STORET, BIOS, CETIS, and ODES databases (EPA) • Water and sediment data on major tributaries (Geological Survey) • National Pollutant Discharge Elimination System (NPDES) permit records • Agencies with COC or related information, for instance, Fish and Wildlife Service (FWS), National Oceanic and Atmospheric Administration (NOAA), regional planning commissions, state resource/survey agencies • CWA 404(b)(1) evaluations • Pertinent and applicable research reports • Port and marina authorities • Colleges/Universities • Records of State agencies, (e.g., environmental, water survey, transportation, health) • Published scientific literature
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This information will be compiled and combined with the sampling results to provide and indication of the potential issues related to dredging or excavation of the fill area. The Final Report will be prepared within 2 months of receipt of the sampling results. VI. Cost Estimate by Task The project includes five tasks: • Field Sampling Plan and Access Preparation • Sediment Sampling • Soil Borings and Sampling • Sample Analytical Testing • Final Report Preparation Background Reading United States Environmental Protection Agency, 1995. QA/QC Guidance for Sampling and Analysis of Sediments, Water, and Tissues for Dredged Material Evaluations, Chemical Evaluations, Prepared by EPA and USACE, EPA 823-‐B-‐95-‐001, April. U.S. Army Corps of Engineers, 2003. Evaluation of Dredged Material Proposed for Disposal at Island, Nearshore, or Upland Confined Disposal Facilities — Testing Manual, U.S. Army Engineer Research and Development Center, 3909 Halls Ferry Road, Vicksburg, MS 39180-‐6199, Final report, ERDC/EL TR-‐03-‐1, January. United States Environmental Protection Agency, 2004. Evaluating Environmental Effects Of Dredged Material Management Alternatives -‐-‐ A Technical Framework, Office of Water and Department of The Army, U.S. Army Corps of Engineers (USACE), EPA842-‐B-‐92-‐008 Revised May 2004. United States Environmental Protection Agency, 2007. Identifying, Planning, and Financing Beneficial Use Projects Using Dredged Material Beneficial Use Planning Manual, EPA and USACE, October 2007. U.S. Army Engineer Research and Development Center, 2008. Technical Guidelines for Environmental Dredging of Contaminated Sediments, Michael R. Palermo, Paul R. Schroeder, Trudy J. Estes, and Norman R. Francingues, Environmental Laboratory, 3909 Halls Ferry Road Vicksburg, MS 39180-‐6199 ERDC/EL TR-‐08-‐29, September.
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