Problems/Comments

Adjacent to the seasonal residence on Lot 2, Pleasure Island (in the middle of Flat Lake) a 1,000-gallon home heating oil aboveground storage tank (AST) was installed over top of the location of a previously removed 500-gallon underground storage tank (UST). Over the winter and spring of 2011 a frost heave pushed the 2 X 4 tank frame into the pipe connections, snapping it in two, while the owner was away on vacation. On May 24, 2011 a neighbor smelled a strong odor of diesel and acted on the owners behalf digging an interception trench with a small back hoe on site as suggested by ADEC. In addition, ADEC 10 inch boom and absorbents were deployed at the shoreline to contain and collect fuel from Flat Lake. ADEC arrived on site 5/25/2011 observing an oil sheen in Flat Lake and a very strong smell of diesel in the air. The spill was located at the base of the hill and diesel was observed floating on top of the groundwater in the 3-4 foot deep trench. The interception trench worked well in collecting the majority of product and limiting contamination to Flat Lake. Spill volume is estimated at approximately 500 gallons. An estimated 200 gallons of product were removed from the interception trench and stored in the 500-gallon UST that had previously been removed. Alaska Soil Recycling (ASR) reported that 63.69 tons of contaminated dirt were removed from the site and transported to ASR for thermal treatment via super sacks by barge and semi trailer. The spill migrated under cement slab of the residential structure. Additional excavation was limited as to not jeopardize structural integrity of the house foundation, and the geological and ecological stability of the shoreline. Soil samples collected from eastern sidewall of the initial release (beneath residential structure) and base of excavation, exhibited elevated concentrations of diesel range organics (DRO), gasoline range organics (GRO), Benzene, 2-methylnaphthalene, and 1-methynaphthalene all above ADEC cleanup criteria method 2. Though no additonal sheening was observed upon completion of cleanup in the interception trenches or in Flat Lake, there is still a chance of additional seepage from under the residential structure during spring break up. On-site drinking water was tested and showed signs of hydrocarbons below ADEC cleanup levels. Periodic testing of the drinking water well should be performed to make sure ADEC cleanup levels are not exceeded. Verifying groundwater at the base of impacted area (at approximately 3 feet deep) should also be tested to limit additional seepage into Flat Lake.

Action Information

Contaminant Information

Control Type

Requirements

No associated sites were found.