Facility Site ID: 2901216 Cleanup Site ID: 1532

Current Status: Cleanup Phases Continue

Maury Island Open Space cleanup area. Cleanup area is outlined in yellow. Click on the map to enlarge it.
Maury Island Open Space cleanup area. Cleanup area is outlined in yellow. Click on the map to enlarge it.

Last Updated: June 2024

Información en español

Fact sheet  |  Postcard (February 2024)

Response to Comments (June 2024)

Ecology held a 30-day comment period (February 26 - March 26, 2024) to review an amendment to the legal agreement (Agreed Order) with King County that addresses contamination at the Maury Island Open Space cleanup site (site). The site is now referred to as the Maury Island Natural Area by King County.

As of December 2023, King County has already completed the first two cleanup phases of the Cleanup Action Plan. (See below)

The procedural amendments to the legal agreement included:

  • The final 2019 Cleanup Action Plan and an updated schedule of deliverables to complete the remaining phases.
  • An Environmental Covenant to restrict land uses on the site such as maintaining the capped roads and trails and not disturbing contaminated soil without Ecology permission.
  • Updated legal language to comply with updated applicable laws.

Ecology has reviewed and considered the public comments received on the legal agreement amendment. Based on Ecology’s evaluation of the comments, no changes to the document were necessary, and it is being finalized.

King County will continue completing Ecology’s Cleanup Action Plan through 2029:

  • Revegetate several areas within the site.
  • Cap maintenance roads and majority of trails with a minimum of 3 to 4 inches of compacted gravel and a 3-inch-thick layer of mineral soil or additional gravel.
  • Decommission some trails and redundant trail spurs.
  • Complete limited wetland remediation near gravel parking lot. 

General Cleanup Process

Click graphic to enlarge
Click graphic to enlarge
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 the MTCA and oversees cleanups.

The MTCA site cleanup process is completed in steps (see graphic) over a variable timeline.

Estimated Site Timeline

Maury Island Open Space cleanup phases (click to enlarge)
Maury Island Open Space cleanup phases (click to enlarge)

Completed cleanup phases:

  • Phase 1: 1A in July 2019: Capped all trails; 1B in October 2020: Cleaned up skeet range and removed invasive vegetation in Acres 4-6
  • Phase 2:  March 2022: Planted Acres 4-6




Future cleanup phases with schedule details in legal agreement amendment:

  • Phase 3:December 2024: Cleared and planted Acres 7-10
  • Phase 4: December 2026: Clear and plant Acres 11-13 and complete wetland remediation
  • Phase 5: December 2029:  Clear and plant Acres 14-16

Public Participation

Current Maury Island Open Space cleanup site Public Participation Plan (Updated February 2024)

This plan includes information for the public regarding opportunities to get involved in the Site cleanup process. The outreach activities and mechanisms presented reflect Ecology’s current plans for keeping the public informed and for receiving information and comments from the public. 

Cleanup Action Plan

Maury Island Open Space site Cleanup Action Plan (click to enlarge)
Maury Island Open Space site Cleanup Action Plan (click to enlarge)

Ecology’s Cleanup Action Plan requires King County to: 

  • Revegetate several areas within the site.
  • Cap maintenance roads and majority of trails with a minimum of 3 to 4 inches of compacted gravel and a 3-inch-thick layer of mineral soil (or equivalent).
  • Decommission some trails and redundant trail spurs.
  • Complete limited wetland remediation near gravel parking lot.

Site Background And Contamination

The site is approximately 266-acres and is located on the southeast side of Maury Island above Puget Sound. A portion of the site was formally operated as a sand and gravel mine by CalPortland (previously known as Glacier NW), and the 1-mile shoreline is the longest undeveloped stretch of Puget Sound shoreline in King County. The County acquired the site in 2010. It is currently open to the public for non-motorized recreation, including walking, hiking, mountain biking, and equestrian use. 

Environmental investigations have shown that contaminants exist throughout the site because of fallout from the former ASARCO Tacoma Smelter smokestack, and from former shooting sports activities in the area. These include arsenic, lead, and polycyclic aromatic hydrocarbons (PAHs) in the soil that exceed levels allowed under the state’s cleanup law, the Model Toxics Control Act (MTCA).

This site is within the Tacoma Smelter Plume. Ecology’s Southwest Regional Office manages the overall Tacoma Smelter Plume cleanup. This site is being cleaned up on a separate track through the formal cleanup process, under the management of the Ecology’s Northwest Regional Office. Ecology funds and manages the Soil Safety Program as part of cleaning up the Tacoma Smelter Plume.

Translated Content

En español 

Si le gustaría recibir documentos en español, por favor llame a 425-324-5901 y espere a que un intérprete se una a la llamada o envíe un correo electrónico a preguntas@ecy.wa.gov.

Traducciones de avisos públicos para Maury Island Open Space se preparan bajo solicitud.  
Legal 3
Document Title Document Date Document Type
Maury Island Open Space April 2024 Agreed Order Amendment 4/29/2024 Agreed Order Amendment
Maury Island Open Space - Agreed Order Amendment - July 2023 7/20/2023 Agreed Order Amendment
Maury Island Open Space Agreed Order for RI, FS and draft CAP 2013 2/4/2013 Agreed Order
Public Information 10
State Environmental Policy Act 1
Document Title Document Date Document Type
SEPA Determination of Non-Significance and Checklist 3/1/2018 SEPA Documents
Technical Reports 18
Document Title Document Date Document Type
Maury Island Open Space - Progress Report - August 2024 9/3/2024 Progress Report
Maury Island Open Space - Progress Report 8/9/2024 Progress Report
Maury Island Open Space - Progress Report - April, May 2024 6/7/2024 Progress Report
Maury Island Open Space 2023-2024 Annual Report 5/1/2024 Progress Report
Maury Island Open Space - Progress Report 4/1/2024 Progress Report
Maury Island Open Space - Progress Report 2/14/2024 Progress Report
Maury Island Open Space - Progress Report 1/11/2024 Progress Report
Maury Island Open Space - Progress Report 5/8/2023 Progress Report
Maury Island Open Space Property Engineering Design Report 7/27/2020 Engineering Design Report
Maury Island Open Space - Final Cleanup Action Plan - November 2019 11/28/2019 Cleanup Action Plan
MINA Compliance Monitoring Plan 6/20/2019 Site Specific Technical Document - other
Maury Island - Remedial Investigation - March 2018 3/1/2018 Remedial Investigation Report
Maury Island - Feasibility Study - March 2018 3/1/2018 Feasibility Study
Maury Island Open Space - Interim Action Workplan - June 2016 6/30/2016 Interim Action Documents
Maury Island Open Space - Final Remedial Investigation 6/2/2014 Remedial Investigation Report
Maury Island Open Space Draft Final Skeet Range Investigation Report 6/27/2011 Remedial Investigation Report
Maury Island Open Space RI/FS Work Plan 2010 11/5/2010 Remedial Investigation Work Plan
Maury Island Gravel Mine Impact Study - Nearshore Impact Assessment 3/1/2000 Remedial Investigation Report
There may be more documents related to this site. To obtain documents not available electronically, you will need to make a public records request.

Places to see print documents

  • Northwest Regional Office
    15700 Dayton Ave N
    Shoreline, 98133
    Please schedule an appointment to view print documents at this location.
  • Vashon Library
    17210 Vashon Highway SW
    Vashon Island, 98070
    This location may only have print documents available during open comment periods.

Contaminants 2

Contaminant Type
Soil
Groundwater
Surface Water
Air
Sediment
Bedrock
Metals - Metals Priority Pollutants C
Metals - Arsenic C
S
Suspected
C
Confirmed Above Cleanup Levels
B
Below Cleanup Levels
RA
Remediated-Above
RB
Remediated-Below
R
Remediated
This contaminant list was based on our best information at the time it was entered. It may not reflect current conditions at the site.