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- Site Background
- EPA’s Involvement at this Site
- Site Status
- Work to Protect Human Health and the Environment
- Site Risks
The Cherokee County Site is a former mining area in southeast Kansas, part of a larger regional mining area known as the Tri-State Mining District. It covers about 115 square miles. Over 100 years of widespread lead and zinc mining created piles of mine tailings covering more than 4,000 acres. The mine tailings contaminated groundwater with lead, zinc and cadmium. Following cleanup, operation and maintenance activities and monitoring are ongoing.
EPA’s Involvement at this Site
Lead and zinc mining began in the middle 1800s and continued for over a century in the Tri-State Mining District; the final mining activities ceased in 1970. Sphalerite (zinc sulfide) and galena (lead sulfide) were the principle mined ores, and several other metal sulfides were found in association with the economic ores. The mining activities changed the hydrology of the area by creating a labyrinth of underground voids and many open conduits. These features facilitate surface subsidence and collapse as well as enhanced flow of mineralized groundwater in the subsurface. Surficial mining wastes also leach metals into the groundwater system and surface water bodies. The normal surface and subsurface flow characteristics have been modified by past mining activities; and since much of the surface vegetation is impacted or absent, there is increased infiltration of surface water into the shallow groundwater system and erosion of mining wastes into surface water bodies. During the active mining years, water was continually pumped out of the mines because the ore was predominantly located in the saturated zone of the same bedrock formations that contain the area’s shallow aquifer. When mining ceased, the mines refilled with water as a result of natural groundwater recharge and surface water inflow through mine shafts and subsidence areas. The upper aquifer is now contaminated with metals and is acidic in some areas. Acid mine drainage is prevalent throughout many areas of the Tri-State Mining District.
The primary sources of contamination at the site are the residual and metal sulfides in the abandoned mine workings, chat piles, and tailings impoundments in addition to historic impacts from smelting operations. Upon exposure to the atmosphere, metal sulfides can become oxidized and mobilize as dissolved compounds which increase the acidity of surface water and groundwater. The resulting metal-laden acidic water, referred to as acid mine drainage, can further leach metals from bedrock, contaminate groundwater, and fill mine shafts and subsidence features. The acid mine drainage can also surface through springs and combine with metal-laden surface water runoff to ultimately contaminate rivers, creeks, and lakes. The shallow aquifer is impacted by heavy metals as a result of past mining practices.
EPA placed the site on the National Priorities List (NPL) by publication in the Federal Register on September 8, 1983. EPA began its investigation of the Galena subsite in 1985. The Galena subsite investigations demonstrated that the shallow groundwater aquifer and the surface water were contaminated with elevated concentrations of metals. Many private shallow aquifer wells were found to be contaminated with metals that exceeded the primary and secondary Maximum Contaminant Levels established by the Safe Drinking Water Act.
Immediate Actions: EPA installed water treatment units on eight contaminated wells in 1985. In 1995, EPA removed metal-contaminated soils from 62 residential properties.
EPA defined several Operable Units (OUs) to manage and prioritize cleanup actions:
OU 01 - Alternate Water Supply: EPA selected an alternate water supply approach that included collecting clean groundwater through existing wells owned by the City of Galena, Kan., distributing that water through a pipeline network to affected residences and businesses, rehabilitating two wells needed for the project, and drilling a new well if needed. EPA later updated the remedy to include two new deep aquifer wells to collect water, two water storage tanks and the creation of a rural water district. Construction of the aquifer wells and water storage tanks finished in 1992. Water line easement acquisition activities finished in 1993. As part of the cleanup, EPA provided over 500 residences with a permanent source of clean drinking water.
OU 02 - Spring River Basin: Many of the subsites drain to the Spring River basin; thus, EPA will address this subsite when cleanup of the other subsites finishes. Studies to determine the extent of contamination are ongoing. This OU is still in the site characterization phase and a remedy selection has not been made.
OU 03 - Baxter Springs Subsite: Many phases of work have been completed, are underway, and have or are being conducted by potentially responsible parties (PRPs) and EPA at this subsite. The PRP portions of this OU are completed and are in the operation and maintenance phase. Approximately 1.5 million cubic yards of mining wastes have been remediated by EPA and PRPs to date. EPA is currently implementing the second and third phase mine waste remedial actions (RAs) for several hundred acres of wastes where there are no viable responsible parties.
OU 04 - Treece Subsite: Many phases of work have been completed or are underway and being conducted by PRPs and EPA at this subsite. The residential work at this OU was completed by PRPs and is currently in the operation and maintenance phase. The remaining PRP-lead cleanup actions for mine waste are ongoing. EPA is also conducting a remedial design (RD) for the next phase of cleanup that will address the remaining mine waste in the Treece Subsite.
EPA implemented a voluntary residential buyout for the community of Treece, Kansas, that was conducted by the Kansas Department of Health and Environment (KDHE). All buyout activities in the community of Treece were concluded with the disbandment of the Treece Relocation Assistance Trust on May 22, 2014.
OU 05 - Galena Groundwater and Surface Water Subsite: Work at this OU has been conducted by EPA and PRPs. The EPA fund-lead cleanup was completed in 1996 and the PRP work was completed in 2014.
OU 06 - Badger, Lawton, Waco and Crestline subsites:
Work at this OU has been conducted by EPA and PRPs. PRPs conducted response actions at the Waco and Crestline subsites. The PRP portions of this OU are completed and in the operation and maintenance phase. EPA completed response actions at the Badger, Lawton, and Waco subsites in 2012.
OU 07 - Galena Residential Soils: The selected long-term remedy included excavation and disposal of contaminated soils followed by placement of clean backfill and grass sod or seed. EPA remediated over 700 properties at the subsite. Operation and maintenance activities began in 2002 and are ongoing.
OU 08 - Railroads: During the mining years, railroads were constructed in Cherokee County to join conventional large-scale railroads to the individual mining operations. Historically, the ballast used in the railroad beds was composed of chat from surrounding mine waste piles. Traditionally, these historic railroads were abandoned when mining operations ceased in that mine. This OU is still in the site characterization phase and a remedy selection has not been made.
OU 09 - Tar Creek Watershed: Due to the exclusion of sediments as a media and perennial streams from the OU 04 ROD, the sediments for the perennial portion of Tar Creek in the Treece Subsite will be addressed under this OU. This OU is still in the site characterization phase and a remedy selection will be made at the time a remedy is selected for OU 02, Spring River Watershed.
Work to Protect Human Health and the Environment
The site is being addressed through federal, state and PRP actions.
Risks and pathways addressed by the cleanup include health risks
from people touching or ingesting soil, groundwater or mine wastes, or inhaling
Risks and pathways addressed by the cleanup include health risks from people touching or ingesting soil, groundwater or mine wastes, or inhaling contaminated dust.
Native grasses, streams and wildlife have replaced barren rock and gravel at the Cherokee County Superfund site in Cherokee County, Kansas. One hundred years of lead and zinc mining left the land strewn with contaminated debris and soil that caused contamination of area groundwater. EPA added the site to the Superfund program’s National Priorities List (NPL) in 1983. In 1993, after ensuring that area residents with private wells had safe drinking water, EPA gathered surface mine wastes and buried them on site. Workers covered land with clean soil, diverted streams to avoid the stored wastes and planted the entire site with native vegetation. In 2009, the site received $14.5 million in American Reinvestment and Recovery Act (ARRA) funds, which EPA is using to support cleanup activities at the Badger, Lawton, Baxter Springs and Treece sub-sites. The ARRA funding will enable EPA to complete the project in fewer years than originally anticipated. Today, EPA cleanup has restored a 25 square-mile portion of the 115 square-mile site as a wildlife habitat. Restoration efforts continue. Cleanup of this site has restored the delicate natural environment and reduced human health risks from contamination.