Bellingham Bay, Whatcom Waterway, Bellingham, WA

A.3 Bellingham Bay, Whatcom Waterway, Bellingham, WA

A.3.1 Contacts

Regulatory Contact: WDOE

A.3.2 Summary

Environment:	Marine Embayment
Scale:	Full
Contaminants of Concern:	Mercury, 4-methylphenol, phenol. Mercury is the only bioaccumulative COC.
Source Control Achieved Prior to Remedy Selection?	Yes
Final Remedy:	MNR (110 acres), cappingTechnology which covers contaminated sediment with material to isolate the contaminants from the surrounding environment. and dredging (90 acres)
Expected Recovery Time:	30 years
MNR viewed as a success?	Yes

A.3.3 Site Description

The Whatcom waterway site runs along the downtown Bellingham waterfront and covers more than 200 acres in Bellingham Bay, as well as a former industrial waste treatment lagoon. The primary sources of contamination for this site are past direct discharges and releases from a former Georgia-Pacific chlor-alkali plant. Mercury was discharged in wastewater directly into Bellingham Bay from 1965-1971. Treatment methods reduced these mercury levels until 1979, when an aerated stabilization basin was installed which eliminated effluent released into the bay. The plant was shut down in 1999.

In 2000, an RI/FS was completed for the Star Rock sediment disposal area. Sediments dredged from the Whatcom waterway and adjacent areas deposited there during the 1960s dredging operations served as an internal source of mercury to the site. Cleanup and habitat restoration activities were carried out in 2000/2001. In 2007, a Consent Decree, including a cleanup action plan, was signed for the Whatcom Waterway site.

CSM summary: The primary natural recovery processes at Whatcom Waterway is physical isolation. Lines of evidences collected to demonstrate this include sediment traps to determine sedimentation rates, bathymetryThe measurement of or the information from water depth at various places in a body of water. data to corroborate sedimentation rates, sediment coring to demonstrate historical mercury recovery and sediment bioassays to determine acute and chronic risks to benthos. The results of the sediment bioassays were further corroborated by the biological endpoint monitoring record which indicated that the environmental exposure at the site had been reduced to below risk targets.

A.3.4 Remedial Objectives

Concerns for this case study include both ecological and human health risks associated with mercury. The objective of the sediment cleanup is to achieve compliance with cleanup standards in surface sediments of the bioactive zone (40 mg/kg, WDOE sediment quality standard). These are standards are defined in the 2007 Cleanup Action Plan for the site.

A.3.5 Remedial Approach

Final selected remedy: MNR (110 acres), capping and dredging (90 acres)

The final remedy (Alternative 6) targets the highest contaminated sediments in areas that are likely to be disturbed and can be removed without excessive short-term risk. This remedy consists of dredging the Aerated Stabilization Basin (ASB) and the outer waterway. The inner waterway multipurpose channel was dredged and then capped. Capping followed by MNR was selected for offshore low-energy areas in the bay.

Eight alternatives were considered for the site. Four of these alternatives were determined to be non-implementable. The remaining four alternatives included several combinations of dredging, capping, and MNR for various areas of the bay. The criteria used to evaluate the alternatives follow WDOE’s Model Toxics Control Cleanup Act (MTCA) and Sediment Management Standards and include:

overall protectiveness increases with volume of sediment removed
performance increases with volume of sediment removed
long-term effectiveness increases with use of high-preference remediationThe act or process of abating, cleaning up, containing, or removing a substance (usually hazardous or infectious) from an environment. technologies
short-term risk management decreases with increased dredging
implementability
consideration of public concerns addresses volume of contamination
restoration time
probable cost

Alternative 6 was determined to be “permanent to the maximum extent practicable” under the MTCA since it provided the greatest overall benefit of the practicable alternatives.

The primary lines of evidencePieces of evidence are organized to show relationships among multiple hypotheses or complex interactions among agent, events, or processes. A weight of evidence approach includes the assignment of a numeric weight to each line of evidence. used to investigate physical isolation included sediment core sampling and radioisotope analysis, bathymetric and sediment traps data, recovery and exponential decay modeling, and analysis of temporal trends in sediment toxicity test results.

A.3.6 Monitoring

Monitoring of physical isolation rates (long-term natural recovery performances) will include bathymetric surveys, sediment cores, and visual inspection of intertidal and shoreline areas. Risk reduction (remedial goal) monitoring will include surface sediment chemistry surveys (years 0, 1, 3, 5, 10, 20, and 30) as well as mercury bioaccumulationThe accumulation of substances, such as pesticides, or other organic chemicals in an organism. Bioaccumulation occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost. Thus, the longer the biological half-life of the substance the greater the risk of chronic poisoning, even if environmental levels of the toxin are not very high. monitoring in Dungeness crabs during years 3, 5, and 10.

Expected recovery time: 30 years

Projected monitoring costs: $1 million

RAOs/project objectives achieved? MNR is viewed as a success at this site. Analysis of historical natural recovery shows that MNR has been a successful remedy at Bellingham Bay. Mercury concentrations and toxicity have been reduced in sediments due to natural recovery over time. Models predicted mercury concentrations in surface sediments to be in compliance with cleanup standards by 2005; however, updated information is not available to confirm whether current mercury concentrations validate the model.

A.3.7 References

WDOE Whatcom Waterway. https://fortress.wa.gov/ecy/gsp/Sitepage.aspx?csid=219.

Publication Date: August 2014

Permission is granted to refer to or quote from this publication with the customary acknowledgment of the source (see suggested citation and disclaimer).