Emerald Gateway

Ecology negotiated a legal agreement called an Agreed Order with Prologis-Exchange 3301 South Norfolk LLC (Prologis), the Potentially Liable Person (PLP), for the Emerald Gateway Site (Site). The order requires them to investigate environmental conditions, develop a cleanup plan, and conduct an interim cleanup.  In the meantime, they will be conducting an interim cleanup (Interim Action) for part of the Site.

In 2019 Ecology hosted a public comment period for this Agreed Order and related documents. Ecology received no comments that warranted changes to these documents, and they were made final following the comment period.

Agreed Order – requires the PLP to investigate contamination, complete a Remedial Investigation (RI), Feasibility Study (FS) and draft Cleanup Action Plan (dCAP) for the Site.

Interim Action Work Plan – describes how the PLP will conduct a partial cleanup of the contaminated soil at the Site.

Public Participation Plan – describes how Ecology will inform the community about Site activities and opportunities to be involved in the cleanup process.

On April 6, 2020, Ecology approved and Interim Action Design Report. This report builds on the Interim Action Work Plan, adding details on how to implement it and remediation levels that must be met.

Prologis plans to implement the Interim Action Work Plan in 2020, with Ecology oversight.

Why this cleanup matters 

This site is part of Ecology’s Lower Duwamish Waterway source control efforts, because it is contributing pollution the Lower Duwamish Waterway (LDW) Superfund Site. The 5-mile stretch of the Duwamish River that flows north into Elliot Bay was added to the Superfund National Priorities List by the U.S. Environmental Protection Agency (EPA) in 2001. The sediments (mud) in the river contain a wide range of contaminants due to decades of industrial activity and runoff from urban areas. EPA is leading efforts to clean up the river sediments. Ecology is leading efforts to control sources of contamination from the surrounding land area. The long-term goal is to minimize recontamination of the river sediment and restore water quality in the river. The Site is one of several sites that will be cleaned up as part of Ecology’s Source Control Strategy – controlling sources of pollution to the river. Contaminants in the soil and groundwater around the river pose a risk to human health and the environment. They can also find their way into the river through storm runoff and other pathways. For more information, visit our Source Control page.

Site location and history

The Emerald Gateway Site is located on a property that consists of 29 King County parcels over approximately 63 acres of land at two addresses:

• 3301 South Norfolk Street, Seattle – historically used for commercial warehousing of food products by Unified/Associated Grocers or predecessors, and included truck maintenance and repair operations, truck refueling facilities, and associated underground storage tanks. Additional historical operations included automobile service stations and a dry cleaner.

• 10230 East Marginal Way South, Tukwila – historically used for automobile wrecking and parts salvaging by Northwest Auto Wrecking, Inc. and is currently vacant.

Prologis purchased the property in 2016 and is planning to redevelop it as a warehouse and distribution center. They plan to conduct the Interim Action concurrently with the property redevelopment. Some investigations and cleanup work have been conducted in different parts of the Site since 1989.


Contamination

Investigations found the following contaminants in soil and groundwater:

• petroleum hydrocarbon constituents
• metals
• polycyclic aromatic hydrocarbons (PAHs)
• polychlorinated biphenyls (PCBs)

All of these contaminants were found at levels that exceed allowable standards under the state’s cleanup law, the Model Toxics Control Act (MTCA), and therefore must be cleaned up. Previous property owners conducted some cleanup actions under Ecology’s Voluntary Cleanup Program. Those actions included excavating contaminated soil and groundwater and removing underground storage tanks (USTs).

The Model Toxics Control Act (MTCA; Chapter 70.105D RCW is Washington’s environmental cleanup law). It provides requirements for contaminated site cleanup and sets standards that protect human health and the environment. Ecology enacts the MTCA and oversees cleanups. The MTCA site cleanup process is completed in steps (see graphic below) over a variable timeline.