The Chicago Zinc Works began smelting zinc in Weir in 1872and located the smelter in Weir due to nearby commercial coal deposits to fuel the smelter as well as the proximity to the Tri-State lead and zinc ore mining district. Chicago Zinc abandoned the smelter and in 1896 the Cherokee Lanyon Smelter Company purchased the smelter and owned it until 1906. Other operators of the smelter included the Weir City Zinc Works, the Cherokee Zinc Company Smelter, and the Cherokee Lanyon Spelter Company. Several owners held the property until the Weir Smelting Company purchased the smelter in 1917 and sold it in 1920. It is unknown if the Weir Smelting Company actively ran the smelter, as from other historical information it appears smelting operations closed in approximately 1909 when natural gas wells in other areas of Kansas made smelter operations from coal unprofitable.
The EPA and the Kansas Department of Health and Environment (KDHE) have documented elevated levels of lead in soils and waste at the Site. In March 2004 a KDHE contractor completed a Focused Former Smelter Assessment (FFSA) under KDHE’s State Water Plan program (SWP). The FFSA did not include any on-site sampling, but recommended sampling due to the historical documentation indicating smelter operations at the Site and visual observations of smelter waste during the site visit. In November 2004 the Phase II FFSA was completed by the same KDHE contractor. During the Phase II FFSA 34 unbiased and 8 biased soil samples were collected. The maximum lead detection was 12,100 mg/kg by X-ray fluorescence analysis (XRF) in HS-8. Two of the off-site samples (PS-1 and PS-6) indicated lead above 400 mg/kg, the current residential Risk-based Standard for Kansas (RSK).
In December 2008 a Site Investigation was completed under KDHE’s SWP. An additional 55 soil samples were collected and field analyzed by XRF. Six off-site samples were collected. A test trench was excavated in the former smelter works to determine the horizontal and vertical extent of waste. A total of 10 sediment and 5 surface water samples were collected from the intermittent branch of Brush Creek that flows through the site area. The maximum lead, arsenic, cadmium, and zinc concentrations in soil were 10,615 mg/kg, 143 mg/kg, 147 mg/kg, and 18,172 mg/kg, respectively. The highest concentrations were observed in the eastern portion of the site near the former railroad right-of-way. The initial waste estimation from the sampling and exploratory trench was approximately 19,000 cubic yards. Sediment and surface water were also determined to be impacted, and several samples collected in the predominant downwind directions based on historical wind roses also indicated lead and arsenic above residential RSKs of 400 mg/kg and 18.9 mg/kg, respectively, demonstrating a likely wind deposition of contamination from the smelter works.
In December 2011 KDHE’s SWP completed a Supplemental Site Investigation (SSI). The primary purpose of the SSI was to evaluate five off-site residential properties, and to collect sediment and background soil samples. The residential yard sampling was conducted consistent with EPA’s Superfund Lead-Contaminated Residential Sites Handbook, with each yard being subdivided into quadrants for composite sampling. Two yards were determined to be impacted by lead contamination above 400 mg/kg. The SSI recommended additional residential yard sampling to further determine the area of contamination. An Integrated Assessment was completed by KDHE in June 2013 followed by a Request for Federal Action (RFA) in July, 2013.
A Removal Assessment Report was completed by EPA’s Superfund Technical Assessment and Response (START) contractor in February 2016. During the Removal Assessment 22 properties were sampled in addition to surface water and sediments. These 22 properties included verification sampling at eight properties previously sampled by KDHE and an additional 14 properties previously not sampled.
The Removal Assessment Report concluded that 13 properties are impacted above the RML of 400 mg/kg for lead in one or more quadrants outside of the drip zone. An additional five properties had lead levels above 400 mg/kg in the drip zone but no exceedances outside of the drip zone. Since the completion of the Removal Assessment over 50 additional residential properties have had lead detections in one or more quadrants outside of the "drip zone" above 400 mg/kg.
The Removal Assessment also concluded that soil, sediment and surface water were likely impacted above background concentrations for lead, arsenic, cadmium and possibly selenium on or adjacent to the former smelter property. This removal action is only addressing priority residential properties in Weir, and the former smelter property itself is anticipated to be addressed through longer-term remedial actions by EPA.
The Cherokee Zinc Site has been proposed for listing on the National Priorities List in September 2020.