Bremerton Naval Complex, WA

A.4 Bremerton Naval Complex, WA

A.4.1 Contacts

Regulatory Contacts: US Navy, USEPA, WDOE

A.4.2 Summary

Environment:	Marine embayment
Scale:	Full
Contaminants of Concern:	PCBs, mercury
Source Control Achieved Prior to Remedy Selection?	Yes
Final Remedy	MNR (230 acres), dredging, isolation cappingTechnology which covers contaminated sediment with material to isolate the contaminants from the surrounding environment., and thin-layer capping (61 acres)
Expected Recovery Time	10-30 years
MNR viewed as a success?	Not yet determined

A.4.3 Site Description

This site is located at the Bremerton Naval Complex (BNC), Operable Unit B. The entire Bremerton Naval Complex site includes 380 acres of upland and 270 acres of sediment in the southwest region of Puget Sound, on the Sinclair Inlet in Bremerton, WA. This case study focuses on the 230 acres of OU B (marine), one of the six areas of interest. This area is primarily subtidal land extending 1,500 ft offshore to depths of approximately 40 ft below mean lower low water.

The BNC has been in operation since the 1890s. Operations have included shipbuilding and vehicle maintenance, berthing for naval vessels, commercial activities, and housing. The BNC includes both the Puget Sound Naval Shipyard (PSNS) and the Naval Station Bremerton (NSB). The PSNS provides overhaul, maintenance, conversion, refueling, defueling, and repair services to the naval fleet. NSB serves as a deep draft home-port for aircraft carriers and supply ships.

The primary sources of contamination at this site are past direct discharges and releases, including from miscellaneous waste material used as fill during expansion of the Naval Complex as well as ongoing minor releases from upland soils via stormwater discharge. Hazardous materials generated during fleet support activities that are believed to be contained in the fill substrates below the site include metal plating, metal filings, electrical transformers (containing PCBs), batteries, paint and paint chips (containing heavy metals), acids, and other caustic substances.

CSM summary: The primary natural recovery process at the Bremerton site is physical isolation. Lines of evidence collected to support continuing sedimentation (0.5 - 0.75 cm/yr) and concurrent absence of erosional areas include:

Bathymetry: current and historical data collected to determine sedimentation rates
Sediment profile imaging: sediment mapping to characterize substrate and recently deposited layers

A.4.4 Remedial Objectives

The main risk concerning this case study is human health, primarily from PCBs in fish tissue. Currently, subsistence tribal fishermen consume seafood from the BNC site as well as nearby locations in Sinclair Inlet. It is possible that they could also consume seafood from other areas of the site in the future if these areas are opened up. Mercury was found to be a risk driver for human health after the completion of the RI, therefore it was included in the ROD; however, a cleanup level was not identified.

RAOs/project objectives for this site include the following:

Reduce the concentration of polychlorinated biphenyls (PCBs) in sediments to below the minimum cleanup level of 3 mg/kg organic carbon (OC) in the biologically active zone (0 to 10 cm depth) within OU B marine, as a measure expected to reduce PCB concentrations in fish tissue.
Control shoreline erosion of contaminated fill material at Site 1.
Selectively remove sediment with high concentrations of mercury collocated with PCBs.

Site-specific cleanup levels for sediments and remedial goals for fish include:

remedial action level for total PCBs in sediment of 6 mg/kg organic carbon (OC) for the biologically active zone (0-10 cm) throughout OU B (marine)
long-term cleanup goal for total PCBs in Sinclair Inlet sediments equivalent to the reference area concentration of 1.2 mg/kg OC
PCB remedial goal for fish tissue of 0.023 mg/kg wet weight

A.4.5 Remedial Approach

Final selected remedy: MNR (230 acres), dredging, isolation capping, and thin-layer capping (61 acres)

The remedy included dredging, thin-layer capping, MNR, and shoreline stabilization to reduce erosion of contaminated sediments. Dredging was selected for sediments with PCB levels of 12 mg/kg OC (approximately 200,000 yd³ of sediment). After dredging, the area-weighted average PCB concentration in sediments was expected to be reduced from 7.8 mg/kg OC to 4.1 mg/kg OC. After, MNR was expected to further reduce risks through natural deposition.

Thin-layer capping was selected for areas with PCB concentrations exceeding 6 mg/kg OC (approximately 16 acres adjacent to OU A). Another 13 acres in OU B were treated with isolation capping.

After implementing dredging and capping, MNR was expected to reduce the area-weighted PCB concentration in OU B sediments to below 3 mg/kg OC within 10 years (by 2014). The reference area goal (1.2 mg/kg OC) is expected to be reached within 30 years (2034).

A.4.6 Monitoring

Monitoring activities verified that remedial goals had been reached, confirmed the predicted natural recovery of sediments, and evaluated the remediationThe act or process of abating, cleaning up, containing, or removing a substance (usually hazardous or infectious) from an environment. success in reducing COC concentrations in fish tissue. Long-term monitoring started with a baseline evaluation in 2003 and addition assessments were to be conducted in 2005, 2007, 2012, and 2017. Activities detailed in the 2005 Final Marine Monitoring report (URS Group 2006) included:

Bathymetric surveys: Sediment elevations measured in 2001, 2003, and 2005 track each other within the range of expected intersurvey variability (1-2 ft.).
Surface sediment sampling: PCB concentrations exceeded the 3 mg/kg OC short-term goal.
Ongoing natural recovery modeling: Modeling based on the 2005 data predicts that natural recovery will likely not meet the goals set out in the ROD in the expected 10-year time frame.

Expected recovery time: 10-30 years

Projected monitoring costs: $2,500,000

RAOs/project objectives achieved? MNR is viewed as a success at this site. Results on monitoring activities through 2007 indicate that decreasing PCB concentrations are consistent with the cleanup goal target date of 2014.

A.4.7 References

USEPA Puget Sound Naval Shipyard Complex website. http://yosemite.epa.gov/r10/cleanup.nsf/7780249be8f251538825650f0070bd8b/fb496707a24fb2478825654b00793b26!OpenDocument.

USEPA. 2004. USEPA Superfund Explanation of Significant Differences: Bremerton Naval Complex, Operable Unit B. USEPA ID: SCD980310239, OU 01, Charleston, SC. U.S. Environmental Protection Agency, Region 4.

Publication Date: August 2014

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