Hers Industrial Park

This Site is being cleaned up under the Voluntary Cleanup Program (VCP). The Site was issued a No Further Action Likely Letter on June 4, 2025.

The Property is identified as 4403 Russell Road in Mukilteo, Washington, and is comprised of eight Snohomish County tax parcels located between Russell Road and Chennault Beach Road in Mukilteo, Washington.

The source of contamination on the Property is attributed to releases from the former operations at the industrial park and from a former underground storage tank (UST). The primary source of chlorinated volatile organic compounds (CVOCs) in soil and groundwater appears to have originated from storm drains located east of the former Intermec building (4403 Russell Road). The catch basins were reportedly not tight-lined to the existing main line, but allowed to discharge directly to the subsurface.

• Soil: CVOCs (tetrachloroethene [PCE] and trichloroethylene [TCE])
• Groundwater: CVOCs (PCE, TCE, cis-1,2-dichloroethene, vinyl chloride, and methylene chloride), total petroleum hydrocarbons in the diesel and oil ranges (TPH-D and TPH-O), and arsenic.

Fill is present on the Property from the ground surface to approximately 5 feet below the ground surface. The fill is underlain by Quaternary Vashon Till (dense, silt, sand and gravel) to approximately 177 feet below the ground surface. The upper 15 feet is described as weathered till underlain by very dense, relatively impermeable unweathered till. Vashon Advance Outwash deposits described as dense sand (Esperance Sand member) occur beneath the till to the maximum explored depth of 200 feet below the ground surface. The Esperance Sand member is estimated to be approximately 120 to 160 feet thick in the area of the Property.

Groundwater is present beneath the Property in shallow and deep zones:

• Shallow Groundwater: Shallow perched groundwater occurs from approximately 2 to 7 feet below the ground surface (perched within the weathered till). Shallow groundwater is likely recharged by stormwater infiltration from perforated storm drains since the Site is largely covered by impervious surfaces that prevent precipitation infiltration from the ground surface. The groundwater flow in the shallow zone is influenced by the topography and the stormwater system. The groundwater flow direction is variable, but generally flows to the north-northwest.
• Deep Groundwater: There are two deeper groundwater zones documented at 58 feet below the ground surface (encountered in well MW-16D) in the Vashon Till and at approximately 162 feet below the ground surface (encountered in well MW-2D) in the Esperance Sand (Vashon Advance Outwash). Groundwater flow in the deeper zones is anticipated to follow topography and flow to the west towards Puget Sound.

Site investigations beginning in 1994 included soil, groundwater, and soil gas sampling. Investigations were conducted before and after interim actions. The Remedial Investigation was completed in 2015.

Soil:  PCE- and/or TCE-contaminated soil above the state cleanup levels remains in the area near the northeast corner of the former Intermec building (identified as the source area) at the weathered/unweathered glacial till contact (approximately 12 to 17 feet below the ground surface). Contaminated soil is completely capped by the building and surrounding pavement.

Groundwater:  PCE, TCE, cis-1,2-dichloroethylene, and VC are above state cleanup levels in shallow groundwater near the former Intermec building (groundwater plume). TCE is present in the deep well located beneath the source area (MW-16D), but is not present in the downgradient deep well (MW-2D). TCE concentrations in MW-16D have been stabilizing over time. TPH-D, TPH-O, and total arsenic present in groundwater have also been decreasing and/or stabilizing. Contamination has not migrated off the Property. 

Soil Gas:  Soil gas samples collected in the source area as part of a vapor intrusion evaluation did not contain any detections of CVOCs. 

• The Feasibility Study was completed in 2021. The selected cleanup action focuses on the cleanup of CVOCS in soil and groundwater using in-situ chemical reduction/enhanced anaerobic biodegradation (ISCR/EAB) with institutional controls (IC) and monitored natural attenuation (MNA). ISCR/EAB is designed to destroy the contaminant mass and reduce the restoration time frame. It is anticipated that cleanup would transition to MNA (groundwater monitoring) when the effectiveness of the active treatment levels off. When active treatment is discontinued, an IC in the form of an environmental covenant will be recorded for the affected parcels to address any remaining contamination. The treatment would include two injection events within 4 years, and an estimated 5 years of groundwater monitoring. 
• The pilot test was completed in 2023. The results of the pilot test showed the successful reduction of PCE and TCE in groundwater in the source area, and the complete dechlorination of a substantial portion of the CVOC mass. The results of the pilot test were used to design a full-scale injection plan which was submitted to Ecology in 2024. The implementation of the full-scale injection program is expected to start in 2025.

• UST Removal (June 1995). An abandoned, single-wall steel UST was removed from the south side of the building located at 4493 Russell Road. The UST was 500 gallons in size and was used to store heating oil. Approximately 25 tons of petroleum-contaminated soil were excavated and disposed of off the Property. Confirmation soil samples were below the state cleanup levels.
• Excavation of Contaminated Soil from Floor Drain (July 1995). The floor drain located in the former Exotic Metals Welding tenant space (4433 Russell Road) was removed along with approximately 1 cubic yard of visually contaminated soil. The confirmation soil sample was below the state cleanup level.
• Excavation of Contaminate Soil and Removal of Catch Basin (September 1996). Contaminated soil at Catch Basin D34 was excavated and disposed of off the Property. The catch basin was located near the northeast corner on the former Intermec building (4403 Russell Road). Approximately 25 tons of petroleum contaminated soil were excavated and disposed of off the Property. The confirmation soil sample was below the state cleanup level.
• Groundwater Treatment - In-Situ Chemical Oxidation (ISCO) (2006). Completed three rounds (March, April and October 2006) of ISCO injections in the area of PCE and TCE contamination east and northeast of the former Intermec building. Following groundwater treatment in October4 2006, CVOC concentrations in seven of the nine monitoring wells located within the groundwater treatment area (contamination plume) decreased.
• Groundwater Treatment - ISCR/EAB (2023). Completed one round of injections in the source area in 2023. The injections were associated with the ISCR/EAB pilot test which included baseline groundwater sampling in May, one injection event in June, and post-injection groundwater monitoring in September and December, and May 2024. The results of the pilot test showed the successful reduction of PCE and TCE in groundwater in the source area, and the complete dichlorination of a substantial portion of the CVOC mass.

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.

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Counties: Island, King, Kitsap, San Juan, Skagit, Snohomish, and Whatcom

Email: nwroerts@ecy.wa.gov
Phone: 206-594-0000

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This site is in our Voluntary Cleanup Program, which provides technical help to owners of contaminated sites.

Voluntary Cleanup Program customers pay fees to cover our costs for technical help and reviewing cleanup reports. Sites in this program must meet the same cleanup standards as sites Ecology manages under legal orders.