Washington Issaquah Bellingham Seattle Oregon Portland Bend Baker City California Oakland Sacramento Irvine September 1, 2016 Ms. Donna Musa Washington State Department of Ecology Northwest Regional Office 3190 160th Avenue Southeast Bellevue, Washington 98008-5452 BY E-MAIL ONLY RE: RELEASE NOTIFICATION AND NOTICE OF INDEPENDENT REMEDIAL ACTION MAPLE VALLEY PROPERTY (AKA FORMER KING COUNTY SHOPS SITE) 18825 SOUTHEAST RENTON-MAPLE VALLEY ROAD RENTON, WASHINGTON FARALLON PN: 525-022 Dear Ms. Musa: Farallon Consulting, L.L.C. (Farallon) has prepared this letter on behalf of Lakeside Industries, Inc. (Lakeside Industries) to report the discovery of a release and the planned independent cleanup of petroleum hydrocarbon constituents at 18825 Southeast Renton-Maple Valley Road in Renton, Washington (herein referred to as the Site) (Figure 1), in accordance with the requirements of Section 300 of Chapter 173-340 of the Washington Administrative Code (WAC 173-340-300) and other regulations. The Site comprises approximately 25.39 acres on King County Parcel No. 1923069026. The Site was originally developed in the 1920s by Pacific Coast Coal Company to support coal mining operations in the region. In the 1940s, the Site was sold to King County, which used the Site for maintenance, woodworking, fueling, and other activities through the 1980s. Following King County’s ownership, the Site reportedly was owned by various entities between the late 1980s and the late 1990s, when Goodnight Properties Inc. purchased the Site. Sunset Materials, which sells residential and commercial landscape materials, has occupied and operated the Site from that time until the present. A Phase I Environmental Site Assessment (Phase I ESA) was conducted at the Site by Farallon in February and March 2016 as part of Lakeside Industries due diligence related to the acquisition of the Site. The results of the Phase I ESA are documented in the Phase I Environmental Site Assessment Report, 18825 Southeast Renton-Maple Valley Road, Renton, Washington dated April 19, 2016, prepared by Farallon (Phase I ESA Report). According to information obtained during the Phase I ESA, King County Shops, listed at the Site address, was identified in the CSCSL, LUST, and SPILLS databases. According to the Ecology online Integrated Site Information System, the Site is identified as King County Shops, Cleanup Site ID: 9217 and FS ID: 6919. G:\Projects\525 Lakeside Ind\525022 18825 Southeast Renton-Maple Valley Road\Correspondence\Release Notification\Release Notification ltr.docx Quality Service for Environmental Solutions farallonconsulting.com Washington State Department of Ecology September 1, 2016 Page 2 According to information provided by the Washington State Department of Ecology (Ecology), two fuel underground storage tanks (USTs), three fuel pumps, a heating oil UST, and associated piping were removed from the Site by King County in 1997. Approximately 300 tons of impacted soil was excavated and removed from the Site by King County. According to documents reviewed during the Phase I ESA provided by Ecology, impacted soil remains in localized areas of the Site. During the UST excavations performed by King County, sheen was observed in groundwater; however, the extent of groundwater impacts was not investigated. According to Ecology, the Site has confirmed the presence of petroleum in soil and groundwater at concentrations exceeding their respective regulatory cleanup levels. The Site is listed as awaiting cleanup under an independent cleanup action. Farallon found no records of closure reports or No Further Action determinations for the Site. Based on the results of the Phase I ESA, a subsurface investigation was performed by Farallon to evaluate the potential presence of hazardous substances in soil and/or groundwater from historical and/or current operations on the Site. The subsurface investigation was conducted at the Site from March through May 2016. The main elements of the subsurface investigation included locating subsurface utilities, advancing and sampling soil from 16 test pits, and installing and sampling soil and groundwater from seven monitoring wells. Total petroleum hydrocarbons (TPH) as diesel-range organics (DRO), TPH as oil-range organics (ORO), and benzene were detected at concentrations exceeding the Washington State Model Toxics Control Act Cleanup Regulation (MTCA) Method A cleanup levels in soil at the Site during the subsurface investigation. These substances were identified as the constituents of potential concern (COPCs) for the Site. The source(s) of the COPCs in soil are confirmed and suspected releases primarily related to historical King County operations at the Site. Total and dissolved arsenic were detected at concentrations exceeding MTCA Method A cleanup levels in groundwater samples collected from monitoring wells MW-2 and MW-6 on the central portion of the Site. The source of the anomalous detections of total and dissolved arsenic is likely related to a localized source in shallow soil at the Site. Groundwater samples collected from the remaining monitoring wells at the Site were reported non-detect at the laboratory practical quantitation limits for all COPCs, including monitoring wells MW-4 and MW-5 at the down-gradient northern Site boundary. Based on these data, no further groundwater characterization is recommended at the Site. According to the results of the subsurface investigation, four localized areas of shallow petroleum hydrocarbon-contaminated soil are present at concentrations exceeding MTCA Method A cleanup levels, including: • A localized area of DRO-contaminated soil proximate to the northern side of the current diesel fuel storage building on the southwestern portion of the Site; • A localized area of DRO-contaminated soil proximate to the former fuel pumps/maintenance shop area operated by King County on the west-central portion of the Site; G:\Projects\525 Lakeside Ind\525022 18825 Southeast Renton-Maple Valley Road\Correspondence\Release Notification\Release Notification ltr.docx Quality Service for Environmental Solutions farallonconsulting.com Washington State Department of Ecology September 1, 2016 Page 3 • A localized area of ORO-contaminated soil proximate to the former wash bay on the eastern portion of the Site; and • A localized area of benzene-contaminated soil proximate to test pit TP-15 on the southeastern portion of the Site. Lakeside Industries intends to conduct an independent remedial action to address the affected media to the maximum extent practicable in accordance with applicable requirements of MTCA. The independent remedial action will be completed through the Ecology Voluntary Cleanup Program and performed in accordance with MTCA requirements for substantial equivalence as set forth in WAC 173-340-515, including providing Ecology with information on the Site and cleanup action, and obtaining confirmation from Ecology that the cleanup action is being performed in accordance with MTCA. Remedial activities also will meet the threshold requirements of WAC 173-340-360 to protect human health and the environment, comply with cleanup standards, and comply with applicable state and federal laws. Some or all of the costs for conducting the remedial action will be subject to a private Right of Action in accordance with WAC 173-340-545. Farallon trusts this letter provides sufficient information to meet the requirements of WAC 173-340-300. Please contact Riley Conkin at (425) 295-0800 if you have questions or require additional information regarding the release at the Site. Sincerely, Farallon Consulting, L.L.C. Holly Corner, L.G. Associate Geologist J. Riley Conkin, L.G., L.H.G. Principal Geologist Attachments: Figure 1, Site Vicinity Map Figure 2, Site Plan cc: Karen Deal, Lakeside Industries (by e-mail) William Joyce, Joyce Ziker Parkinson, PLLC (by e-mail) HC/JRC:bw G:\Projects\525 Lakeside Ind\525022 18825 Southeast Renton-Maple Valley Road\Correspondence\Release Notification\Release Notification ltr.docx Quality Service for Environmental Solutions farallonconsulting.com FIGURES RELEASE NOTIFICATION AND NOTICE OF INDEPENDENT REMEDIAL ACTION Maple Valley Property (aka Former King County Shops Site) 18825 Southeast Renton-Maple Valley Road Renton, Washington Farallon PN: 525-022 G:\Projects\525 Lakeside Ind\525022 18825 Southeast Renton-Maple Valley Road\Correspondence\Release Notification\Release Notification ltr.docx SITE LOCATION Copyright:© 2013 National Geographic Society, i-cubed REFERENCE: 7.5 MINUTE USGS QUADRANGLE MAPLE VALLEY, WASHINGTON, DATED 2014 RENTON 0 2,000 SCALE IN FEET ³ Washington Issaquah Bellingham Seattle SITE VICINITY MAP LAKESIDE INDUSTRIES 18825 SOUTHEAST RENTON-MAPLE VALLEY ROAD California RENTON, WASHINGTON Oakland Sacramento Irvine Oregon Portland Bend Baker City Farallon CONSULTING Quality Service for Environmental Solutions Drawn By: tperrin FIGURE 1 farallonconsulting.com Checked By: TC Date: 6/17/2016 FARALLON PN: 525-022 Disc Reference: Document Path: G:\Projects\525 Lakeside Ind\525022 18825 Southeast Renton-Maple Valley Road\GIS\FIGURE 1_525-022_v3.mxd STORMWATER POND G SOUTHE AST RE NTON-M APLE VA LLEY RO A MW-4 ! < G FORMER STOCKPILING AREA D MW-5 ! < FORMER LANDSCAPE MATERIAL STORAGE AREA G FORMER CONCRETE CISTERN WITH ARTESIAN WELL G MAINTENANCE SHOP FORMER STOCKPILING AREA G SEPTIC DRAIN FIELDS G FORMER PETROLEUM STORAGE BUILDING ) G CB1 SCALE W " S W G G " S CB5 " S MW-1 ! TP-07 < ) W! . " TP-11 " ) CB6 " S SS MW-7 < ! TP-04 " ) TP-10 MW-2 " ) ! < " ) CB7 TP-15 " S CB8 " S G OVERHEAD ELECTRIC LINE TP-01 " ) TEST PIT LOCATION UNDERGROUND ELECTRIC LINE CB1 " S CATCH BASIN LOCATIONS . ! SPIGOT LOCATION SITE BOUNDARY SS STORM SEWER LINE W WATER UTILITY LINE G SS G MONITORING WELL TP-13 " FORMER ) WASH BAY TP-12 FORMER PARTS STORAGE BUILDING FORMER COVERED STORAGE AREA WELL HOUSE LEGEND ! < FORMER USED AST & DRUM STORAGE BUILDING " ) DIESEL FUEL STORAGE BUILDING MW-4 TP-14 " ) G CB4 G " ) CB3 " S " ) G CB2 " S TP-16 SS CURRENT STOCKPILING AREA " ) TP-09 FORMER VACANT BUILDING SS W FORMER GAS AND DIESEL USTS FORMER STORAGE AREA FORMER BOILER G ! MW-6 TP-05 " < ) MW-3 ! < " ) " ) TP-06 FORMER TP-02 HEATING TP-03 OIL UST G FORMER FUEL PUMPS OFFICE G G G . ! G " S SEPTIC TANK W " TP-01 OUTFALL CULVERT NOTES: 1) AST = ABOVEGROUND STORAGE TANK 2) UST = UNDERGROUND STORAGE TANK 3) THE SITE SLOPES NORTH KING COUNTY PARCEL 1923069026 0 ³ Washington Issaquah Bellingham Seattle Oregon Portland Bend Baker City Farallon 80 CONSULTING California Oakland Sacramento Irvine Quality Service for Environmental Solutions CULVERT DIRECTIONAL FLOW TO RIVER farallonconsulting.com FIGURE 2 SITE PLAN LAKESIDE INDUSTRIES 18825 SOUTHEAST RENTONMAPLE VALLEY ROAD RENTON, WASHINGTON FARALLON PN: 525-022 SCALE IN FEET Drawn By: tperrin Checked By: HC Date: 7/29/2016 Disc Reference: Document Path: G:\Projects\525 Lakeside Ind\525022 18825 Southeast Renton-Maple Valley Road\GIS\Figure 2_SitePlan_Utilities.mxd