Environmental investigation, cleanup effort continues in downtown Walla Walla
By Dan Thesman on Wednesday, October 4th, 2023 in Columbia Basin News More Top Stories
News release from city of Walla Walla
WALLA WALLA – The focus of the incident response continues to transition from the initial life/safety response to an environmental investigation and cleanup effort.
Clean Harbors crews redirected the vent duct running from the basement of the Marcus Whitman Hotel to vent out above the building, instead of to 2nd Avenue as it had initially been set up. Clean Harbors also added new equipment to introduce additional fresh air into the basement.
The basement has been completely sealed off from the rest of the building. Constant ventilation of the basement continues to keep levels of volatile organic compounds (VOCs) at acceptable levels, and lower explosive limits (LELs) at zero.
With that situation stabilized, the City of Walla Walla Building Official has issued a conditional certificate of occupancy that allows the Marcus Whitman Hotel and Conference Center to be occupied if the current conditions are maintained. Hotel staff are currently working on a timeline for reopening for staff and guests.
Clean Harbors continues to pump affected water from the sump pumps in the hotel and the 106 N. 2nd Ave. building into frac holding tanks. From there, the water is running through a multistage filtration system to remove the contaminants.
Samples of the resulting cleaned water are currently being tested to ensure they contain no trace of contamination. Once investigators receive test results that indicate zero contaminants, the filtered water will be disposed of at Walla Walla’s Wastewater Treatment Plant. The contaminants filtered out of the mixture will be transported to a hazardous waste facility for disposal.
Investigators from the Washington Department of Ecology continue to work to delineate the gasoline plume and determine the best method of extracting the contamination from the ground.
Staff at the Wastewater Treatment Plant have been monitoring the wastewater system throughout the incident and have observed no evidence of gasoline entering the system. Similarly, monitoring of Mill Creek continues to detect no evidence of contaminants entering the waterway.
This update is based on information provided by Washington Department of Ecology staff. City staff will continue to provide these updates on the City website (https://www.wallawallawa.gov/gasoline) as we receive additional info from Ecology.
