Problems/Comments

Residents of Kaltag informed ADEC in 1991 that oil seeps were appearing every spring at the Kaltag School. Probable sources include nearby former tank farms: notably a former Bureau of Indian Affairs (BIA) tank farm, a former Alaska Village Electric Cooperative (AVEC) tank farm, and a former Yukon-Koyukuk School District (YKSD) tank farm. The AVEC and YKSD former tank farms occupied the same gravel pad south of the Kaltag School. The former BIA tank farm was located to east of the school, was constructed by the BIA in the early 1960s, and consisted of three above ground storage tanks (ASTs). They were apparently in use by the Kaltag BIA School presumably until the BIA school burned and was replaced with the existing school in 1976. It is unclear when the former YKSD tank (located south of the school) was constructed, and whether the YKSD and new (existing) Kaltag School utilized the BIA Tank Farm, as it is identifiable in an aerial photograph of 1980, with no other apparent tank farms located near the school. There is a history of fuel oil spills near the school beginning in 1985. Outdated equipment and poor fuel transfer procedures also contributed to chronic leaks and spills from overfills. Site characterization in 1998 and 2000 show heavy soil staining at all three tank farm locations (former BIA Tank Farm, former AVEC Tank Farm, former YKSD tank Farm), and that diesel range organics (DRO) and benzene are the primary contaminants of concern, although some PAHs have also exceeded the most stringent cleanup levels. The supra-permafrost groundwater underneath the school has been impacted, and the contamination has migrated via this pathway underneath the school, along the ditches of the school road, and onto the neighboring (Semaken) property. General groundwater flow is to the north, northwest, somewhat parallel to the Yukon River. In 1998 Shannon & Wilson performed site characterization and installed as an interim corrective action - a roadway seepage control measure and a product recovery trench. Soil samples showed DRO present up to 67,300 milligrams per kilogram (mg/kg), gasoline range organics (GRO) up to 1,330 mg/kg, and benzene, toluene, ethylbenzene, and xylenes (BTEX) above ADEC cleanup levels. Groundwater analysis showed benzene contamination well above ADEC cleanup levels. Site data indicates the former BIA tank farm contains some of the greatest concentrations of DRO in soils found in the surrounding area (e.g., historic high of 97,300 mg/kg of DRO in soil), and is likely one of the most significant sources of contamination to groundwater and surface seeps near the school. The seepage filtration system (SFS) was to intercept water flow at the site's northern boundary, and to treat and dispose of collected seep water; however, low levels of supra-permafrost groundwater, and lack of consistent maintenance, have limited the effectiveness of the system. Groundwater monitoring has also been limited by low groundwater levels, and by traffic damage to well points. Vapor intrusion assessment has been done at the school, but results were confounded with indoor air sources of contamination; e.g., school boiler and other possible sources of VOCs. The School is located on state land. The YKSD constructed teacher housing on the site of the former BIA tank farm in 2008. A new contaminant (1-Chloro-octadecane) was also found during soil screening and sampling during October, 2010 at the former BIA tank farm, and surrounding locations near the school (e.g., YKSD Shop and Heating Oil Transfer Tank). Also see file numbers 850.38.001, 850.02.002, and 850.02.003.

Action Information

Contaminant Information

Control Type

Requirements

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