This property has a documented history as a property with a heating oil tank going back to 1957. Historical insurance policies issued during those prior operations and through 1986 could fund a cleanup.
This commercial property on Mercer Island features a building constructed in 1957, beneath whose adjacent parking area three 500-gallon heating oil underground storage tanks were closed-in-place and decommissioned in 2004. A Phase I Environmental Assessment completed in December 2022 confirmed that the tanks had leaked, with diesel-range hydrocarbon contamination documented in soil and groundwater as a result of historical heating oil releases. Cleanup under an independent action is pending and will require excavation and removal of the USTs and impacted soil to a depth of 14 feet, along with installation of at least three permanent groundwater monitoring wells monitored for a minimum of one year. That history could support an insurance cost recovery claim against carriers who issued insurance policies 40+ years ago.
Why Historical Insurance Policies May Be Accessible
Pre-1986 Commercial General Liability (CGL) policies were occurrence-based and did not contain an effective pollution exclusion in Washington. If contamination occurred while those policies were active, those historical insurance carriers may still have a legal obligation to fund the cleanup costs, even if the business closed or the property changed hands.
The heating oil system at this property served a building in continuous use since 1957 — nearly three decades before 1986, when occurrence-based Commercial General Liability policies were still the industry standard and lacked effective pollution exclusions. The contamination here reflects the slow, historical leakage pattern that pre-1986 CGL policies were designed to cover: incremental releases from aging USTs over an extended operational period, not a discrete accident. The costs now facing the property owner — UST excavation, contaminated soil removal to 14 feet, and multi-year groundwater monitoring — could plausibly be funded by historical carriers whose policies were in force during the decades the tanks were in active use.
Restorical's role is to locate viable historical policies, determine whether a successful coverage claim is possible, and assist our clients and their legal counsel to obtain insurance coverage. Restorical then manages the claim, including accounting, to ensure the cleanup is funded in a timely manner.
What We Look For
- Historical insurance policies (pre-1986)
- Policy numbers, carrier names, and coverage periods
- Connection between contamination timing and policy period
- Evidence linking cleanup obligation to insured activity
What We Deliver
- Historical Coverage Chart
- Trigger Analysis & Property/Policy Nexus
- Coverage strategy with recommendations
- Insurance funding for your remediation
- Claims Management & Forensic Accounting
The Restorical Proven Process
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Contact UsThis analysis is preliminary and based on publicly available records. Restorical Research is not a law firm and does not provide legal advice.


