Crews begin drilling inspection wells in downtown Walla Walla
By Dan Thesman on Thursday, September 21st, 2023 in Columbia Basin News More Top Stories
News release from city of Walla Walla
WALLA WALLA – Crews drilled two inspection wells on Wednesday afternoon. One well was then lined and the other one is being lined this morning (Thursday). The wells are lined with a sequence of sand, clay, bentonite (a form of clay) and concrete. After being lined, the wells can be used to extract samples of groundwater for analysis.
Crews expect to drill and line up to four more wells today (Thursday). The wells will be surveyed to determine the slope of the subsurface ground in the area, which in turn will show investigators the direction in which the groundwater is flowing and help lead them to the source of the contamination.
Pumping operations to remove more contaminated water resumed Wednesday night in the basement sumps at the Marcus Whitman Hotel and 106 N. 2nd Ave., both of which continue to collect water.
The team will take samples from all the gasoline tanks at the Chevron and Circle K fuel stations today and drive them to Portland for forensic “fingerprint analysis.” This testing can identify the age of the gasoline, its origin based on its specific additives and chemical makeup, how much it’s been affected by the environment, and more. Samples taken at Chevron and Circle K will also be compared to samples taken from the two affected buildings to see if there is a match. All of this evidence will help investigators identify the source of the gasoline.
Under the guidance of the Environmental Protection Agency, Clean Harbors installed additional precautionary collection booms into Mill Creek. Continued observation by EPA staff has detected no evidence of gasoline contamination entering Walla Walla’s waterways.
Air-quality monitoring remains in place in the area and Walla Walla Fire Department crews continue to test the surrounding buildings. This ongoing monitoring and testing has not detected the presence of high levels of volatile organic compounds (VOCs) or LELs (lower explosive limits) in any new areas.
The U.S. Postal Service has provided an update to its information about the services being provided at the College Place Post Office: “Post Office box customers, and any customer who receives the pickup notice, can collect their mail at the College Place Post Office located at 500 S. College Avenue. The office is open Monday – Friday, 8:30 a.m. – 5:30 p.m.” The current information from USPS is always available here.
The response team appreciates the flexibility of the community as we learn more about the situation and adjust our approach to changing conditions.
City staff will continue to provide these updates on the City website (https://www.wallawallawa.gov/gasoline) as the situation changes.
Photo via city of Walla Walla shows a crew drilling an inspection well into the ground below North 2nd Avenue, Wed., Sept. 20, 2023.
