Unocal SS 2938
Site History
The site was formerly a service station that was demolished in 1990. Two 10,000-gallon underground storage tanks, a heating oil tank, waste oil tank, and the pump islands were removed. Contaminated soil from the tank excavations was taken to a landfill.
In 1994, nine groundwater monitoring wells were installed. Sample results showed benzene, gasoline, and diesel in groundwater required cleanup.
In 2003, 17 test pits were dug to find the extent of contamination. All soil sample results met state standards, except for two.
In 2012, part of a retaining wall was demolished and replaced. About 168 cubic yards of contaminated soil were removed during the process. Ten additional monitoring wells were installed, and groundwater was monitored through 2013. Sampling was stopped when results from the final four quarterly events met state standards.
Contaminated soil remains next to the retaining wall along the eastern side of the property and at a location along G Street. Ecology filed an Environmental Covenant to document the remaining contamination and restrict property use to protect people from being exposed to it.
Periodic reviews
Ecology visited the site September 29, 2022, to complete a periodic review. We found that the cleanup remains effective and the property owners are following the restrictions in the covenant.Voluntary Cleanup Program
This site was cleaned up under 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 the sites Ecology manages under legal orders.
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
- Prohibit Soil Disturbance
Restricted Media
- Soil
Documents 3
Legal 1
| Document Title | Document Date | Document Type |
| Unocal SS 2938 | 5/2/2016 | Environmental Covenant; Alternative Mechanism |
Technical Reports 1
| Document Title | Document Date | Document Type |
| Periodic Review: Unocal SS 2938 | 10/20/2022 | Periodic Review (5 Year) |
Voluntary Cleanup Program 1
| Document Title | Document Date | Document Type |
| Unocal SS 2938 - VCP Opinion on Site Cleanup - No Further Action | 5/6/2016 | VCP Opinion on Site Cleanup – NFA |
Places to see print documents
-
Eastern Regional OfficeN 4601 Monroe StSpokane, 99205-1265Please schedule an appointment to view print documents at this location.
Contaminants 7
| Contaminant Type | Soil |
Groundwater |
Surface Water |
Air |
Sediment |
Bedrock |
|---|---|---|---|---|---|---|
| Non-Halogenated Organics - Non-Halogenated Solvents | B | |||||
| Non-Halogenated Organics - Polycyclic Aromatic Hydrocarbons | RA | |||||
| Non-Halogenated Organics - Methyl tertiary-butyl ether | B | |||||
| Non-Halogenated Organics - Benzene | RB | RB | ||||
| Non-Halogenated Organics - Petroleum-Diesel | RB | RB | ||||
| Non-Halogenated Organics - Petroleum-Gasoline | RB | RB | ||||
| Non-Halogenated Organics - Petroleum-Other | RB | B |
- S
- Suspected
- C
- Confirmed Above Cleanup Levels
- B
- Below Cleanup Levels
- RA
- Remediated-Above
- RB
- Remediated-Below
- R
- Remediated