Stillwater Holdings Chevron
Ongoing Cleanup Activities
Page updated March 18, 2025.
In March 2025, Ecology hired NWFF Environmental to install more efficient equipment at the Stillwater Holdings Chevron property to continue protecting the community. Mitigating potentially harmful vapors in the Marcus Whitman Hotel and 106 Building remains the highest priority. We plan to collect another round of groundwater samples this month.
Stillwater Holdings has been cooperative and communitive throughout the installation of the new mitigation equipment and are working toward complying with the Enforcement Order. The first deliverable required from Stillwater Holdings is a comprehensive schedule and a remedial investigation work plan, which has not been submitted to us yet.
The sump water sample collected from the Marcus Whitman Hotel in November 2024 met state standards, while samples collected from the sump at the 106 Building had petroleum levels above standards. Groundwater samples from wells on and around the Chevron property were also above standards, although overall, levels are decreasing.
On September 5, 2024, Stillwater Holdings had five soil samples collected on their property while removing some old product lines and fuel pumps. Sample results showed contaminated soil near the southern fuel canopy at 300 milligrams per kilogram (mg/kg), and cleanup is required at 30 mg/kg. Stillwater Holdings’ consultant, Aspect, interpreted the contamination as highly weathered gasoline likely from the historical release.
Between August 16 and 21, 2024, Ecology sampled indoor air in the 106 Building, basement sumps in the 106 Building and the Marcus Whitman Hotel, and all site groundwater wells. The 106 Building sampling results showed initial indoor air was safe for adults working an 8-hour shift, but not for children or adults occupying the building for longer than a normal work shift. Groundwater sampling analysis showed results above state standards.
Concerns regarding a broken sewer line were provided via a letter from the owner of the 106 Building on August 15, 2024. Based on these concerns, the City of Walla Walla completed a dye test August 20, to check if there was a break in the sewer line. The city found that water discharging from the sink is discharging to Rose Ave., not 2nd Ave., indicating the system is functioning as it should.
Area Safe & Monitored
Local, state, and federal agencies, along with third-party contractors, have deemed the area safe for residents and visitors with protection measures and air quality monitoring in place. Testing of Walla Walla's municipal water and wastewater systems and nearby Mill Creek has shown no evidence of contamination.
The Cleanup Process & Public Input Opportunities
We held a public comment period June 18 – August 16 for the Enforcement Order and Public Participation Plan. The order requires Stillwater Holdings to continue work to reduce harmful vapors and remove contaminated water from nearby buildings until a permanent treatment system is installed. You can learn more in the public notice we mailed to the surrounding community. We responded to comments from five people and thank them for their input. Based on concerns expressed about using state funding for cleanup, we amended the Enforcement Order to require a remedial investigation and feasibility study.
Ecology held a public comment period for the draft State Environmental Policy Act documents for the underground storage tank system replacement April 1–15, 2024. We responded to comments from four people, and we thank them for their input. The tank replacement was postponed because the leaking tank was emptied during the initial spill response and has not been put back into use.
2023 Spill Response
On September 14, 2023, the Marcus Whitman Hotel was evacuated due to volatile organic vapors entering the building, also known as vapor intrusion. The Walla Walla Fire Department called in Ecology’s Spill Response Team to help assess the situation and identify the source.
Testing identified potentially harmful vapors and gasoline in the basement, and in two nearby buildings. The buildings were ventilated to eliminate the risk of an explosion, and the buildings’ drainage systems, also known as sumps, were pumped to reduce vapor concentrations.
An investigation found that gasoline pooling in the adjacent building sumps matched the fuel in Stillwater Holdings’ gasoline underground tank. Since the tank was taken out of service and emptied, product is no longer visible in the sumps, and petroleum contaminants continue to decrease in water samples from the sumps.
Site use restrictions called institutional controls are in effect
Institutional controls can be fences, signs, or restrictions on how the property is used. For instance, an institutional control may prohibit installing drinking water wells or disturbing a protective cap that isolates contamination. These restrictions keep the contamination contained and keep people from being exposed to the contamination. The controls are usually listed in environmental covenants recorded with the county.
Periodic reviews are required when institutional controls are required at a site. Ecology conducts reviews to make sure the controls remain effective and the cleanup still protects human health and the environment. We conduct periodic reviews about every five years.
Institutional Controls 1
Environmental Covenant
Restrictions/Requirements
- Prevent the Reuse or Relocation of Site Soil
- Prohibit Soil Disturbance
- Restrict Land Use
Restricted Media
- Soil
Documents 53
Legal 5
Document Title | Document Date | Document Type |
Access Agreement: Reata Ranches Ltd | 3/5/2025 | Property Access Agreement |
Access Agreement: MWH | 2/28/2025 | Property Access Agreement |
Enforcement Order Amendment: Stillwater Holdings | 9/17/2024 | Enforcement Order Amendment |
Enforcement Order: Stillwater Holdings Chevron | 6/18/2024 | Enforcement Order |
Environmental Covenant: Bill Singers Chevron | 5/20/2013 | Environmental Covenant; Alternative Mechanism |
Map 1
Document Title | Document Date | Document Type |
DRAFT Proposed Test Pit Investigation Locations 12.2023: Stillwater Holdings Chevron | 12/28/2023 | Map |
Outreach Information 8
Document Title | Document Date | Document Type |
March 2025 update: Stillwater Holdings Chevron cleanup | 3/13/2025 | Focus Sheet |
Response to Comments: EO for the Stillwater Holdings Chevron site | 10/1/2024 | Responsiveness Summary |
September 2024 update: Stillwater Holdings Chevron cleanup | 9/26/2024 | Focus Sheet |
August 2024 update: Stillwater Holdings Chevron cleanup | 8/30/2024 | Focus Sheet |
Public Participation Plan: Stillwater Holdings Chevron | 6/18/2024 | Public Participation Plan |
Legal Order and Public Participation Plan ready for comment: Stillwater Holdings Chevron | 6/18/2024 | Fact Sheet\Public Notices |
Response to Comments: State Environmental Policy Act documents for Stillwater Holdings Chevron | 5/29/2024 | Responsiveness Summary |
May 2024 update: Stillwater Holdings Chevron cleanup | 5/15/2024 | Focus Sheet |
State Environmental Policy Act 1
Document Title | Document Date | Document Type |
SEPA Checklist & Determination of Non-significance: Stillwater Holdings Chevron UST replacement | 4/1/2024 | SEPA Documents |
Technical Reports 38
Places to see print documents
-
Eastern Regional OfficeN 4601 Monroe StSpokane, 99205-1265Please schedule an appointment to view print documents at this location.
Contaminants 3
Contaminant Type | Soil |
Groundwater |
Surface Water |
Air |
Sediment |
Bedrock |
---|---|---|---|---|---|---|
Non-Halogenated Organics - Benzene | C | |||||
Non-Halogenated Organics - Other Non-Halogenated Organics | C | |||||
Non-Halogenated Organics - Petroleum-Gasoline | C | C | C |
- S
- Suspected
- C
- Confirmed Above Cleanup Levels
- B
- Below Cleanup Levels
- RA
- Remediated-Above
- RB
- Remediated-Below
- R
- Remediated