23-106002-SU_Department Of Ecology Letter_12-20-23`
Heather Tatro, Associate Planner 6/22/2022
Encompass
165 NE Juniper St, Suite 201
Issaquah, WA 98027
Re: 2240 S 288th St Short Plat, Federal Way, Washington
Dear Heather Tatro,
Thank you for the opportunity to provide comments on the 2240 S 288th Street Short Plat project. The project
property is located in Federal Way, Washington on one, 0.9-acre King County parcel (3322049023). The proposed
project is located in an area affected by arsenic and lead in the soil resulting from the air emissions from the old
Asarco Smelter in Ruston, Washington.
American Price Lending LLC (American) proposed to develop this property into a residential development. Ecology
recommended soil sampling to evaluate the levels of arsenic and lead in the soil prior to construction. Ecology also
recommended enrollment in the Voluntary Cleanup Program (VCP) with Ecology if lead, arsenic, or other
contaminants are found at concentrations above Model Toxics Control
Act (MTCA) Method A cleanup levels.
Earth Solutions NW LLC (ES), on behalf of American, conducted soil
sampling on the project property on April 14, 2022. ES collected 20 soil
samples from 16 sampling locations. ES collected 16 soil samples from 0
to 6 inches below ground surface (bgs) and four samples from 6 to 12
inches bgs. They also collected four; 6-point composite duff samples
(Figure 2).
ES submitted the samples to
OnSite Environmental laboratory
in Redmond, Washington for an
analysis of arsenic and lead
concentrations with an
Environmental Protection Agency
(EPA) Method 6010D. ES prepared
a report summarizing the results
of the soil sampling 1. Ecology reviewed the report and concluded that
the average soil concentrations were below the cleanup level of 20 milligrams per kilogram (mg/kg) for arsenic
1 Earth Solutions NW, LLC. Limited Phase II Environmental Site Assessment, Tacoma Smelter Plume, South 288th Street Short
Plat, Federal Way, Washington. May 16, 2022.
THE MTCA SOIL CLEANUP LEVELS:
Average arsenic ≤ 20 mg/kg
Average lead ≤ 250 mg/kg
AND
Maximum arsenic ≤ 40 mg/kg
Maximum lead ≤ 500 mg/kg
Figure 1. Vicinity Map
Project Location
and 250 mg/kg for lead (Table 1). Similarly, no samples exceeded the maximum allowable concentration for a
single soil sample of 40 mg/kg for arsenic or 500 mg/kg for lead.
Table 1. Summary of Soil Sampling ay
Sample Depth
(feet)
Arsenic mg/kg (EPA 6010D) Lead mg/kg (EPA 6010D)
Minimum Maximum Average Minimum Maximum Average
0-6 11 15 12 5.6 36 17
6-12 11 11 11 5.5 5.7 5.65
Duff 12 15 13.25 6.2 32 17.9
MTCA Levels 40 20 500 250
Ecology does not recommend this property enter the Voluntary Cleanup Program. No soil remediation for the
contamination associated with the Tacoma Smelter Plume is needed for this property.
Please note, this not a “No Further Action” determination for the property, since the property was not enrolled
into the VCP.
Eva Barber
Technical Assistance Coordinator
Toxics Cleanup Program
Southwest Regional Office
Washington State Department of Ecology;
Eva.barber@ecy.wa.gov;
Phone: 360-999-9593
Figure 2. Approximate locations of soil samples