1.1.1 Incident Category
Time Critical Removal Action

1.1.2 Site Description

Tributyl tin-contaminated sediments under Pier 4 in Tacoma, Washington.

1.1.2.1 Location

1 Sitkum Way, Tacoma, WA

1.1.2.2 Description of Threat

Tributyltin at levels exceeding 50,000 ug/kg were found in the sediments under Pier 4 during a predredge sampling performd by the Port of Tacoma in 2013. Tributyltin is an environmental toxin affecting mollusks and was banned in the 1990s.

1.1.3 Preliminary Removal Assessment/Removal Site Inspection Results

The Port of Tacoma collected and analyzed samples of sediment under Pier 4 in July 2014 to determine the extent and depth of contamination. Results indicated a removal action was necessary to dredge and remove approximately 50,000 cubic yards of sediment.

2.1.1 Narrative

2.1.2 Response Actions to Date
On 1/18/2016, the Port of Tacoma's contractor, OMI, began re-dredging dredge management units DMU 3, 4, 6, 7, 8 and continued on to dredge the external dredge management units waterward from the initial dredge footprint until completion on 2/15/2016. Pore-water and bulk sampling conducted on 1/29/2016 of the surface and depth sediments in DMUs 3, 4, 6, 7, and 8 indicated all had surface contamination only.  After consulting with EPA and the DMMP, the Port agreed to re-dredge an additional foot from the affected units without the need for additional sampling. On 2/8/2016, the OSC notified the resource agencies that contaminated dredging and pile pulling would continue into the first week of the fish window. The second redredging of the five DMUs occurred between 2/15 and 2/17/2016. On 2/17/2016, part of the bank above DMU4 collapsed before that section could be redredged. Since the contamination in that DMU was minimal, (0.16 ppb for an action level of 0.15 ppb TBT in porewater) EPA agreed that no additional dredging in the remaining 40% of DMU4 was necessary. On 2/18/2016, the Port provided the OSC with the bucket map showing that the required areas were redredged. The same day, the OSC issued a letter to the Port stating EPA agrees that the tributyl tin-contaminated sediments have been completely removed.

2.1.3 Enforcement Activities, Identity of Potentially Responsible Parties (PRPs)

The Port of Tacoma is the PRP performing the removal action. Research is being conducted to identify additional PRPs.

2.1.4 Progress Metrics

2.2.1 Anticipated Activities

2.2.1.1 Planned Response Activities

Final cleanup tasks from the contaminated dredging and operation of the transload and water treatment site at APM terminal are expected to continue into April 2016. A half day of in-water pile pulling will occur in March to remove the barge fender pilings from the APM terminal pier.

2.2.1.2 Next Steps

2.2.2 Issues

EPA

The Port of Tacoma

Orion Marine Contractors (OMI)

Subcontractors to OMI