4407 Henderson Blvd SE, Olympia, WA 98501


Cleanup at the Briggs Nursery site is completed and Ecology will remove the site from the state's Hazardous Sites List in 2019.

Ecology held a public comment period from February 19 to March 21, 2019, on its proposal to remove the site from the Hazardous Sites List. Ecology received three comments during the comment period.  The public comments and Ecology's response to comments are available in the Responsiveness Summary.

Because some contamination remains in the kettles (natural depressions) at the site, an environmental covenant was filed for the kettles in 2008. With the cleanup work completed and an environmental covenant in place, conditions at the site protect people's health and the environment.

Ecology will conduct a periodic review of the site about every five years to ensure that conditions at the site continue to protect human health and the environment. 


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The site is about 120 acres, and it is located north of the intersection of Henderson Blvd and Yelm Highway. The site is the former location of a wholesale nursery in operation since 1912. During the mid-2000s, the nursery moved away and the site is now changing to houses and businesses.


In 2002, Thurston County Health Department on behalf of Ecology decided a study of possible contamination was necessary based on information about pesticide use at the site.

In 2004, Ecology ranked the site as a 2 because dieldrin (a pesticide) levels in some soil samples were above state cleanup levels. A site is ranked based on its potential relative risk compared to other known contaminated sites in the state. Sites are ranked on a scale of 1 to 5 with 1 being the highest potential risk. When the site was ranked, Ecology put the site on the Hazardous Sites List.  

In 2004, Briggs Nursery entered into an Agreed Order (Agreed Order No. 1315) with Ecology to conduct a remedial investigation and feasibility study to find the extent of contamination and plan options for cleanup. As part of the investigation, owners tested soil, sediment, groundwater, and surface water for pesticides, metals, polychlorinated biphenyls (PCBs) and dioxins/furans.

Results of these studies showed there was no contamination of groundwater, or of nearby Ward Lake, from nursery operations.

Some areas at the site had dieldrin and PCBs contaminated soil exceeding state cleanup levels. To clean up the site, owners removed

  • 20,250 tons of dieldrin contaminated soil.
  • 1,811 tons of dieldrin and PCBs contaminated soil.

Following cleanup, concentration of contaminants in soil was below state cleanup levels, except for residual contamination remaining in the bottom of the kettles at the site. Kettle landforms are natural depressions created by melting ice blocks as a glacier retreats.

To eliminate possible exposure to contamination in the kettles, in 2008 an environmental covenant was filed for the site. The covenant restricts public access to the kettles and requires the owner to place fences and signs around the kettles. Thurston County is the current owner of the kettles and it is responsible for maintaining the fences and signs restricting public access to the kettle bottoms.

Ecology reviewed the cleanup work in combination with the environmental covenant that restricts access to the kettles and determined that conditions at the the site are effective in protecting people's health and the environment. Ecology held a public comment period in 2019 to provide an opportunity for the public to comment on the no further action memo and removing the site from the Hazardous Sites List. Ecology will remove the site from the list in 2019.



Map showing site location as Thurston County, WA SITE INFORMATION


View Electronic Documents

Cleanup Site Details Report

Facility Site ID: # 35797926

Cleanup Site ID: 4150

Olympia, Thurston County

Status: No Further Action   Get definitions of Status terminology

Mohsen Kourehdar
Site Manager
(360) 407-6256

Nancy Davis
Public Involvement Coordinator
(360) 407-0067

Document Repositories:

Southwest Regional Office
300 Desmond Dr SE
Lacey, 98503-1274