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DOWNTOWN IC SITES | NSGA IC SITES | OUTBACK IC SITES | SITE BACKGROUND | LOCATION | CHEMICALS OF CONCERN
PETROLEUM INSTITUTIONAL CONTROLS | PETROLEUM ENGINEERING CONTROLS
SA 78, Old Transportation Building,
USTs 10583, 10584, and ASTs
Background
SA 78, Old Transportation Building, is located approximately 5 miles north of downtown Adak in the NSGA complex, on the lower, southern slope of Mount Adagdak, near the northwestern shore of Clam Lagoon. The Old Transportation Building was used as the NSGA fire station and transportation garage from 1950 until mid-1991 (Navy 1996). Two USTs and two ASTs were used at the Old Transportation Building site to store motor vehicle gasoline (mogas) for vehicle fueling from the early 1960s until 1993. Exact installation dates of the USTs and ASTs are unknown.
The area east of the Old Transportation Building was filled, graded flat, and used as a vehicle fueling area. Although the site has been graded level, the surrounding topography of the Old Transportation Building site slopes southeast toward Clam Lagoon. Surface water runoff generally flows southeast toward Clam Lagoon, approximately 250 feet from the source area.
In May 1993, UST 10583 was excavated, removed, cleaned, and disposed of (Quest 1993). The two ASTs were removed during the excavation of UST 10583 (EMCON 1996a). Soil contamination and fuel leaking from piping connected to both ASTs and UST were observed during tank removal activities. UST 10584 could not be located to be removed; records could not confirm that the UST has been removed. GRO and BTEX were not detected in the three in-place soil samples collected from the excavation; however, these analyses were rejected because they did not meet Alaska DEC protocols (EMCON 1996a).
Three monitoring wells (MW-116, MW-117, and MW-118) were installed in 1994 during the PSE-2 investigation at several nearby sites. DRO was detected in the soil at location 10 and GRO was detected in the groundwater in well MW-117, downgradient of former UST 10583. No analytes were detected in the sediment samples collected along Clam Lagoon and an outfall discharge point. Between 1996 and 1997, seven soil borings and three monitoring wells (12-145, 12-151, and 12-152) were installed in the vicinity of the Old Transportation Building USTs and ASTs. DRO was detected in soil at all but one location and in groundwater from wells MW-117, 12-145, 12-151, and 12-152. Similar results were found when well MW-117 was resampled in 1997 and 1998 and well 12-145 was resampled in 1997. Two downgradient monitoring wells (12-801 and 12-802) were installed in 1999. No constituents were detected in the groundwater samples collected from these wells in 1998, 1999, or in 2000.
Free product was observed in well 12-145 in November 1996. Passive-style skimmers were used intermittently at this site to recover product when detected in measurable quantities, however, less than one gallon of product has been recovered. Free product has not been observed in any monitoring well in the vicinity of the SA 78, Old Transportation Building, since June 1999. Since June 1999, the Navy has gauged the wells periodically for the presence of free product. Because free product has not been found in any monitoring well since June 1999, data indicates that free product at this site has been recovered to the maximum extent practicable, as required by 18 AAC 75.325(f)(1)(B).
Chemicals of Concern
Soil analytical data collected from depths of less than 15 feet were compared to Alaska 18 AAC 75 Table B-1 Method 2 values; 21 exceedances of these criteria were noted in data collected from 9 locations (110, 113, 123, 12-145, 12-146, 12-147, 12-149, 12-150, 12-152) for at least one of the following analytes: DRO, GRO, benzene, ethylbenzene, toluene, and xylenes. Most exceedances were located downgradient and crossgradient to the former USTs. In addition, free product is considered an exceedance of the aforementioned criteria and has been observed in one well at this site in the past.
Location
GIS Survey description in Alaska state plane coordinates: Commencing at U.S. Navy control point M-8G (NAD 83 - N=346,983.09 E=3,147,350.90), which is North 05°52'01" West 2,182.08 feet from U.S. Navy control point E.A.; thence South 80°44'33" East 1,380.76 feet to the POINT OF BEGINNING; thence South 50°11'47" East 175.45 feet; thence South 00°30'24" West 110.27 feet; thence South 76°42'12" West 129.77 feet; thence North 31°51'07" West 105.44 feet; thence North 16°27'31" East 169.83 feet to the POINT OF BEGINNING. Containing 0.69 acres more or less.
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