Alley Fuels is a bulk fuel distributer and card-lock retailer on the Banks/Lowman Highway, approximately 5 miles west of Garden Valley, Idaho. The facility consists of 5 above ground storage tanks (from approx. 5,000 to approx. 10,000 gallons) containing gasoline and diesel fuel. On April 15, 2003, Brico Oil, the supplier to Alley Fuels, reported to the Idaho Department of Environmental Quality (DEQ) that 5,000 gallons of unleaded gasoline was unaccounted for and suspected to have leaked into the ground from one tank at the Alley Fuels facility. Upon inspection, a hole was found in the bottom of the tank. The leaking tank is 470 feet from the Middle Fork of the Payette River, with an approximately 50 foot elevation drop to the River. The owner/operator of Alley Fuels indicated to DEQ and EPA that he did not have the resources to conduct necessary site investigation to determine the extent and migration of spilled gasoline in subsurface soils and groundwater.
On 7/14/03, EPA and EPA's START contractor mobilized to the site to conduct site investigation sufficient to determine whether spilled gasoline presents an significant threat of discharge to waters of the U.S.. A survey of the river bank and seeps along the area did not indicate a present discharge to the Payette River. START contractor installed six monitoring wells to determine subsurface characteristics, including groundwater depth and flow direction and soils type, and to try to locate the spilled fuel. Groundwater was observed at approximately 25 feet below ground surface. Strong photo-ionization detector (PID) readings (in the thousands of ppm) were observed in soils at approzimately 1 to 3 feet above the water table, indicated that groundwater had dropped significantly from the time of the spill, creating a "smear zone." Free phase petroleum was not initially observed in any of the wells, indicating that spilled petroleum was still largely hung up in the smear zone and/or the slug of it had already migrated through the area of the monitoring wells. START collected samples for laboratory analysis, and demobilized from the site on 7/19/03.
START will remobilize in early August to monitor the wells and perform well testing to assess soils permeability and transmissivity.
Review of groundwater and soils analytical data, and information from upcoming groundwater monitoring, will allow for development of groundwater flow map and BTEX concentration gradient to assist in determining if there exists a significant threat of dicharge to waters of the U.S.. High PID readings indicate the likelihood of a free-phase product layer, even though it wasn't initially observed in the wells. It is likely that as groundwater levels rise during wetter months, free product may remobilize and become evident in some of the wells. It is recommended that the wells be monitored at regular intervals over a one-year period to observe the effects of time and groundwater levels.
The OSC anticipates raising the FPN ceiling from $60,000 to $80,000 in order to accomplish necessary monitoring activities.
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