Part 1: SEPA OMDNS CONDITIONS OF PERMIT ISSUANCE
Mitigation List:
The following additional mitigation measures are included under SEPA authority. The following mitigation measures shall be attached as conditions of permit issuance. These mitigation measures are consistent with policies, plans, rules or regulations designated by KCC 20.44.080 as a basis for the exercise of substantive authority and in effect when this threshold determination is issued:
1. Washington State Department of Ecology This proposed project is located in an area that may have been contaminated with heavy metals due to the air emissions originating from the old Asarco smelter in north Tacoma (visit Ecologyโs Tacoma Smelter Plume map search tool: https://fortress.wa.gov/ecy/dirtalert/). Soil contamination from the former Asarco smelter poses a risk to human health and the environment. Children are at especially high risk from direct exposure to contaminated soil. Construction workers, landscapers, gardeners, and others who work in the soils are also at risk. Washington State Department of Ecology (Ecology) recommends that the lead agency include the following as conditions of approval, prior to the issuance of any site development permits or the initiation of grading, filling, or clearing:
a. Sample the soil and analyze for arsenic and lead following the 2012 Tacoma Smelter Plume Guidance. The soil sampling results shall be sent to Ecology for review. If the project includes open space areas, contact the Technical Assistance Coordinator, Eva Barber, for assistance in soil sampling methodology within the open space area.
b. If lead or arsenic are found at concentrations above the Model Toxics Control Act (MTCA) cleanup levels (Chapter 173-340 WAC); the owners, potential buyers, construction workers, and others shall be notified of their occurrence. The MTCA cleanup level for arsenic is 20 parts per million (ppm) and lead is 250 ppm.
c. If lead, arsenic and/or other contaminants are found at concentrations above MTCA cleanup levels, the applicant shall:
i. Develop soil remediation plan and enter into the Voluntary Cleanup Program with Ecology. For more information on the Voluntary Cleanup Program, visit Ecology website at: https://ecology.wa.gov/Spills-Cleanup/Contamination-cleanup/Cleanup- process/Cleanup-options/Voluntary-cleanup-program.
ii. Obtain an opinion letter from Ecology stating that the proposed soil remediation plan will likely result in no further action under MTCA. The applicant shall provide to the local land use permitting agency the opinion letter from Ecology.
iii. Prior to finalizing site development permits, provide to the local land use permitting agency โNo Further Actionโ determination from Ecology indicating that the remediation plans were successfully implemented under MTCA.
d. If soils are found to be contaminated with arsenic, lead, or other contaminants, extra precautions shall be taken to avoid escaping dust, soil erosion, and water pollution during grading and site construction. Site design shall include protective measures to isolate or remove contaminated soils from public spaces, yards, and childrenโs play areas. Contaminated soils generated during site construction shall be managed and disposed of in accordance with state and local regulations, including the Solid Waste Handling Standards regulation (Chapter 173-350 WAC). For information about soil disposal contact the local health department in the jurisdiction where soils will be placed (Correspondence from WSDOE received August 1, 2019).
Applied | Notice | 10/02/2020