Solid Waste Management Unit 01

Public Comment Period for SWMU 01 has Expired

KDHE held a public comment period for this site from January 20 through February 18, 2022. All comments received during the public comment period will be addressed in the Final Agency Decision.

Proposed Remedial Measure

The proposed remedy for Solid Waste Management Unit (SWMU) 01 was excavation and disposal for contaminated soils and sediment and no further action was warranted for on-site groundwater. Groundwater in the area will be evaluated for sitewide Chemicals of Concern (COCs) during the Army’s site-wide assessment of Groundwater Operable Unit, GWOU #4. 

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.

The Classification Area (SWMU 01) was used as a receiving and sorting area during construction and production periods from 1942 to 1991. The first RCRA Facility Investigation (Law, 1997) included collecting 61 surface soil samples, 3 groundwater samples from four monitoring wells, 2 surface water samples, and 2 sediment samples. The investigation identified the presence of bis(2-ethylhexyl)phthalate (DEHP) and di-n-octylphthalate (DNOP) in groundwater. The investigation also identified the presence of numerous metals, polynuclear aromatic hydrocarbons (PAH), phthalates, trichloroethene and tetrachloroethene in surface soils, and the presence of coal fines on the surface east of the railroad tracks. Coal fines occupy an area approximately 250 feet by 2,600 feet.

The 2005 RCRA Facility Investigation (RFI) Addendum (Shaw, 2005) included collecting ten shallow subsurface soil samples, one sediment sample, and four groundwater samples. Analytical results for metals in subsurface soil samples indicated that 22 metals were detected in at least one of ten samples. The metals detected include aluminum, antimony, arsenic, barium, beryllium, cadmium, calcium, chromium, cobalt, copper, iron, lead, magnesium, manganese, mercury, nickel, potassium, silver, sodium, thallium, vanadium, and zinc; only two metals (calcium and thallium) were detected at concentrations exceeding their respective background limits for subsurface soils. Laboratory analysis of the sediment collected from a drainage ditch indicated the presence of 21 metals; cobalt was detected above its estimated background concentration.

Interim Remedial Measures (IRMs) consisting of the excavation and disposal of 7,500 tons of coal-impacted soil were conducted in May 2007. The soil was hauled to the Old Landfill (SAAP-018) to be used as fill material. Asbestos from a burned building was identified in soil during the final site walk in 2013. In 2019, the SFAAP completed additional interim corrective measures consisting of the excavation and disposal of 28.09 cubic yards of asbestos-contaminated soils and sediment at the Johnson County Landfill, removal of water from the scale house basement, collection of water characterization samples, and site restoration.

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 (2015) 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 Conceptual Land Use Plan for the former SFAAP, approximately 90% of the area encompassing SWMU 01 is proposed to be redeveloped as a highway commercial area, with the remaining 10% redeveloped as residential (Johnson County, 1998).

The KDHE has determined that interim actions completed for soil and sediment were the appropriate remedy for SWMU 01. The prior excavation of coal fines and asbestos containing material-impacted soil and sediments was protective of human health and the environment. In addition, subsequent groundwater sampling events determined that DEHP and DNOP are no longer detected in site-specific groundwater. This proposal is based upon KDHE’s review of all available historical documentation regarding the Site.

KDHE Site Documents