SWMU 70 - Diesel Fuel Spill at Building 129-2

Justification

The former Sunflower Army Ammunition Plant (SFAAP) is located near DeSoto, Kansas, in the northwest corner of Johnson County. It is approximately 30 miles southwest of Kansas City, Kansas, and 16 miles east of Lawrence, Kansas. The plant consisted of production facilities, administrative and storage facilities, powerhouses, landfills, lagoons, ditches, burning grounds, sumps, projectile ranges, and waste treatment facilities. The site is composed of 70 Solid Waste Management Units (SWMUs) where a release of hazardous waste was identified and 27 Areas of Concern (AOCs) where hazardous waste or constituents have been identified but are not linked to a specific solid waste management practice.

SWMU 70, Diesel Fuel Spill at Building 129-2, is in the north-central portion of the former SFAAP. The site includes Building 129-2 (Booster Station and Pump House, built in 1943) used until 1992, and the downgradient drainage ditch potentially contaminated from a historic diesel fuel spill. Building 129-2 housed multiple motors and pumps that supported Building 129-1 (Treated River Water Storage Tank), including three ASTs (two diesel and one gasoline). The two diesel fuel tanks supplied fuel to run the diesel motors that powered the water pumps associated with a 12-million-gallon reservoir. The historic diesel fuel spill occurred in 1984. The spill occurred due to a failure in an underground line leading from the two aboveground diesel fuel tanks. The underground pipe exiting the concrete tank containment basins broke loose and approximately 1,400 gallons of diesel fuel leaked from the ASTs over a span of 24 days. According to the spill records, straw, hay, sorbent pads, and sorbent booms were used to absorb the fuel and prevent further flow from the area. Visually impacted soil in the area was excavated and the bottom and banks of the downgradient drainage ditch were burned off with a portable propane burner. The diesel fuel that collected in the downgradient  OWS was burned off and absorbed with sorbent booms. A subsequent site walk completed in December 2012 identified an oily black sheen in the OWS downgradient from these former ASTs, but no investigation was completed. The SWMU 70 area was not used after 1992.

During the Resource Conservation and Recovery Act (RCRA) Facility Investigation (RFI) and Focused Corrective Measures Study (AECOM 2020), 34 surface soil samples, 12 subsurface soil samples, 3 OWS water samples, 3 OWS sludge samples, 3 pond surface water samples, and 3 pond sediment samples were collected and analyzed for RCRA metals, manganese, volatile organic compounds (VOCs), Polycyclic Aromatic Hydrocarbons (PAHs), and Total Petroleum Hydrocarbons-Mid Range Hydrocarbons/High Range Hydrocarbons (TPH-MRH/HRH) (AECOM 2020). TPH-MRH exceeded the residential surface soil Project Action Limit (PAL) of 250 milligrams per kilogram (mg/kg) at one drainage ditch sample location (070-AMSB0015-SO-ER0001). There were no PAL exceedances for TPH-MRH in subsurface soil. All surface and subsurface soil samples analyzed for RCRA metals, manganese, VOCs, PAHs, and TPH-HRH did not exceed their respective PALs (AECOM 2020). TPH-HRH exceeded the residential PAL (1.0 mg/L) in one OWS water sample (070-AMWB0001-SW-ER0001). No other PAL exceedances were reported for OWS water samples. TPH-MRH/HRH exceeded their respective residential PALs in all three OWS sludge sample locations. OWS sludge samples analyzed for metals, VOCs, and PAHs did not exceed their respective PALs. VOCs, PAHs, and TPH-MRH/HRH were not detected in any of the three pond surface water samples. The metals detected in the samples were at concentrations below their respective residential and non-residential PALs. No PAL exceedances were reported for the pond sediment samples (AECOM 2020).

There are currently no potable wells located at or near SWMU 70 and none are likely to be installed in the future. As a result, groundwater was not encountered during the RFI investigation and is not considered to be of sufficient yield and quality for a potable water pathway. 

The Army conducted a streamlined health risk evaluation by comparing RFI data to the approved Target Medial Cleanup Levels for the site. KDHE believes that proper employment of the KDHE (2021) Risk-based Standards for Kansas (RSK) Manual values result in risk-based remediation that is consistent with federally promulgated standards, including the Safe Drinking Water Act, 42 U.S.C. §300f – 300j-26, and is protective of human health as required by Resource Conservation and Recovery Act, 42 U.S.C. §6901 et seq., including the Hazardous and Solid Waste Amendments (HSWA) and 40 CFR Part 264.101. KDHE Tier 2 risk-based cleanup goals represent concentrations at which the contaminants pose an acceptable human health risk to receptors, including sensitive groups (e.g., children or the elderly), over a lifetime.

Cleanup goals were developed for two general categories of receptors residents and non-residents, according to the appropriate land-use designation, exposure frequency, and exposure duration. According to the Johnson County Conceptual Land Use Plan, the area encompassing SWMU 70 is proposed to be a “Business Center” (Johnson County, 1998).

The KDHE has determined that excavation of surface soil, pumping of OWS water and OWS sludge with concentrations exceeding PALs, and off-site disposal of wastes at the appropriate facility is the appropriate remedy for SWMU 70. Contaminated media identified and delineated during the RFI can be removed to limit potential exposure and contaminant migration. Conventional excavation and disposal technologies have successfully been implemented as remedial alternatives for other sites within SFAAP. The excavation, pumping, and off-site disposal of TPH-MRH/HRH contaminated soils (and other media) is appropriate for the site to be protective of human health and the environment. No Further Corrective Action Planned for groundwater is warranted based on the deed restriction on usable groundwater and the absence of potable wells in or around SWMU 70. This proposal is based upon KDHE’s review of all available historical documentation.