Block 38 West

Updated November 2024

Fact Sheet: English | 中文 

The Department of Ecology (Ecology) is overseeing the cleanup of the Block 38 West Site (Site) in Seattle’s South Lake Union neighborhood. City Investors IX L.L.C. (City Investors IX) is the Potentially Liable Person (PLP) cleaning up the Site. We invite you to review and comment on the following documents:

• Remedial Investigation and Focused Feasibility Study (Volume 1 and Volume 2): describes contamination at the Site and evaluates and recommends a preferred cleanup action.


• Draft Cleanup Action Plan: describes the cleanup work to address contamination at the Site.


• Consent Decree: a legal agreement between Ecology and City Investors IX, that requires City Investors IX to implement the cleanup action plan for the Site.

Ecology will consider all comments received during this public comment period and may amend the documents based on the comments. If the documents require significant changes, we will hold another public comment period. If no significant changes are made, Ecology will finalize the documents.

Join our email list to receive updates about the South Lake Union cleanup sites, including Block 38 West. You may also email the Public Involvement Coordinator (listed under Contacts) to be added to the list. Unsubscribe at any time.

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The Model Toxics Control Act (MTCA) 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 MTCA and oversees cleanups. The MTCA site cleanup process is completed in steps over a variable timeline.

Current Block 38 West cleanup site Public Participation Plan

This plan describes how Ecology will share information with the community and how you can share information with us. Ecology will review this plan as the cleanup progresses and amend/update it as necessary.

Site Location

The Block 38 West Site is located in the South Lake Union neighborhood of Seattle. The Site includes the Block 38 West Property, a portion of the Westlake Avenue North right of way, and a north-south-trending alley (City of Seattle public right-of-way) east of the Block 38 West Property.

Site Background

Historical operations and placement of contaminated fill at the Block 38 West Property resulted in contaminated soil and groundwater at the Site.

From October 2019 through July 2021, substantial cleanup of the Block 38 West Site was performed through interim actions (early partial cleanups) on the Block 38 West Property and east-adjacent alley. These interim actions included removal and disposal of contaminated soil and were implemented in conjunction with the redevelopment of the Block 38 West Property.

View the Interim Action Completion Report for the Block 38 West Property:

• Part 1 – Text, Figures, Tables, and Appendix A
• Part 2 – Appendix B
• Part 3 – Appendix C through Appendix K

View the Interim Action Completion Report for the Alley

These reports are also included in the Documents tab under Technical Reports at the bottom of this webpage.

Recent Redevelopment

Redevelopment of the Block 38 West Property began in late October 2019. The former structures were demolished and a multi-story mixed-use building with 12 stories above street level and 4 levels of underground parking was constructed. Construction of the new building required mass excavation across the entire Block 38 West Property to approximately 30 to 35 feet below ground level.

Between 1994 and 2024 multiple phases of the Remedial Investigation were executed to assess the Site for contaminants of concern and to establish cleanup levels. Investigations found the following contaminants in soil and/or groundwater:

• Petroleum hydrocarbons as diesel-range organics (DRO), oil-range organics (ORO), and gasoline-range organics (GRO)
• Benzene
• Naphthalenes, including 1-methylnaphthalene and 2-methylnaphthalene
• Carcinogenic polycyclic aromatic hydrocarbons (cPAHs), including benzo(a)pyrene
• Metals (barium and mercury)

These contaminants were present at levels that exceeded standards under the state’s cleanup law, the Model Toxics Control Act (MTCA). Most of the contamination was removed during the interim actions. The interim actions constitute a permanent cleanup action to the maximum extent practicable in accordance with MTCA and current and future land use. Only the implementation of institutional controls remains.

Ecology is committed to providing people with disabilities access to information and services. To request an ADA accommodation, contact Ecology by phone at 360-407 6831, email ecyadacoordinator@ecy.wa.gov, or visit ecology.wa.gov/Accessibility. For Relay Service or TTY call 711 or 877-833-6341.

If you speak a non-English language, free language services are available.