A. Incident Category: L
B. Site Description: Leaking Storage Tank
C. Site Location: 50 Alda Street (latitude 41° 41.208' North, longitude 72° 56.896' West), Bristol, CT.
The property at 50 Alda Street, Bristol, CT was identified by CTDEP as the source of a sheen observed on Polkville Brook. The Site was discovered when a report of a water- and oil- flooded basement led CTDEP to a property located at 40 Alda Street. The property was serviced by electricity, and no fuel tanks were located on the property.
In response to the NRC report received by US EPA on April 24, 2004, OSC Sims mobilized to the Site and met with CTDEP Responder Emanuelson to discuss the situation and determine if actions taken, to date, by CTDEP to mitigate the spill was not inconsistent with OPA/NCP standard operating procedures.
As part of the reconnaissance investigation, CTDEP reviewed the oil fill logs of a neighbor located directly adjacent and upgradient to the 40 Alda Street address. The frequency of refills at the 50 Alda Street indicated a possibility that the UST at the Site may be leaking. CTDEP mobilized it’s contractor to perform test pitting between the 2 properties to determine if there was subsurface contamination. The test pitting revealed evidence of subsurface free phase oil at 5-6 below ground surface. Temporary monitoring wells installed around perimeter of Site indicated that the plume was confined to the immediate area and down gradient 50-100 feet east of the source area. The plume appeared to flowing east from the 50 Alda Street property. Based on that finding, CTDEP excavated the 1,000 gallon capacity UST. Oil was observed leaking from several holes on the underside of the UST. The bottom portion of the excavation was saturated with free phase oil. CTDEP constructed an interceptor trench and temporary oil recovery system to mitigate the spill. Approximately 300 gallons of free phase oil was recovered during the initial response.
CT DEP will remove all free phase contaminated soil and construct a permanent recovery system at the Site which will consist of a sheltered pumping and filtration system to treat the oil contaminated water prior to discharging into the storm drainage system.
The temporary recovery system installed by CTDEP to treat the free phase oil and contaminated water will be used until a more permanent system can be placed at the Site. Pump and treat activities will continue under the supervision of CT DEP.
Based on this OSC’s findings, CTDEP’s actions to mitigate the spill were not inconsistent with OPA/NCP standard operating procedures.
Based on CTDEP's estimated costs for cleanup, this OSC requested an FPN ceiling of $50,000.
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