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Contamination from mining activities potentially impacts 37,050 residents of Camden County.
The Camden County Mining area was mined from 1830 to 1910, with lead as the principal product. After 1910, most of the mining was for barite, with galena (lead) as a minor by-product. By 1947, lead production in the Central Mining District had totaled 24,855 short tons. Since 1950, no lead and very little barite have been mined. Mining operations and associated lands in the CMD area have been owned, operated, and managed by various entities and/or private citizens (USGS and Missouri Division of Geological Survey and Water Resources 1967). Hazardous substances typically associated with historic mining sites in Missouri include arsenic, barium, lead, and cadmium. The mining waste products often end up on driveways, in yards, and in children’s play areas.
The CMD–Camden County covers approximately 655 square miles in central Missouri. The climate of the area is characterized by cool winters and hot summers. The average total annual precipitation is about 38–42 inches. Camden County site soils range widely in texture, natural drainage, depth to bedrock, and other characteristics. The predominant soil types are deep to moderately deep, sloping to very steep, very cherty silt that forms on uplands.
Several properties in the CMD–Camden County area were found to exceed the removal action level for lead. Sampling is continuing in this area.
Site assessment activities were conducted July–November 2006. Properties were sampled based on the Geological Survey and Resource Assessment Division's (GSRAD) Inventory of Mines, Operations, and Prospects database which identified more than 900 mining locations in the five-county Central Mining District area. The locations were then mapped out, and door to door sampling began. A total of 646 properties were sampled in the Central Mining District area. Thirty one properties were found to have lead greater than EPA's maximum contaminant level (MCL) of 15 ug/l; one property was found to have cadmium exceeding 5 ug/l, and eight properties were found to exceed the arsenic MCL of 10 ug/l.
A Regional Decision Team (RDT) meeting was held on 27 February 2007 where the proposed future actions of a second phase of sampling would be conducted. The purpose of this second phase was to sample the properties of residents who responded after November 13, 2006, when site assessment activities ended and to expand sampling into the other mining areas where limited sampling was conducted. At this meeting it was also agreed that site assessment would investigate the potential for naturally occurring contamination versus mining contamination. Also EPA’s toxicologist was tasked with completing a site-specific streamlined risk assessment. The naturally occurring contamination project, with associated sampling event and receipt of data, was completed in October 2007. This sampling event included sampling all properties that were found to exceed the MCL of 15 ug/l for lead, 5 ug/l for cadmium, and 10 ug/l for arsenic. At that time both wellhead and tap samples were taken. This information was provided to the removal program.
In June 2007, draft action memos were developed for the Central Mining District to address alternate drinking water sources, soil contamination, and continued drinking water sampling. On September 21, 2007, EPA's toxicologist completed site-specific removal action levels for lead in the Central Mining District memorandum. This memo set the Removal Action Level (RAL) for lead in drinking water at 30 ug/l. This memo is an attachment to the signed action memo.
The action memo for Camden County was signed on September 22, 2008. The response action includes continued sampling of drinking water sources, excavating contaminated soils in yards, and providing alternative drinking water sources to properties which exceed the RAL for this site.
During this reporting period, twelve additional properties were sampled at the wellhead. At properties that exceeded 15 ug/l for lead, 10 ug/l for arsenic, and/or 5 ug/l for cadmium at the wellhead, 15 additional samples were taken at the tap and after any existing filters.
During this reporting period, signed access agreements were obtained from two property owners where lead in drinking water exceeded the Removal Action Levels (RAL) for this site.
The EPA OSC is working with EPA's Emergency Response and Removal (ERRS) contrator to provide an alternate drinking water source at those residences.
Continue to conduct soil and water sampling activities in Camden County and respond to residents' inquires.
Resample (at the tap and the wellhead) those properties found to be above 15 ug/l for lead, 10 ug/l for arsenic, and/or 5 ug/l for cadmium.
Awaiting signed access agreements from property owners where the removal action level (RAL) was exceeded.
Continue to conduct soil and water sampling in Camden County.
Send data to residents. Contact residents of properties sampled at the wellhead where heavy metals were found above the following limits: 15 ug/l for lead, 10 ug/l for arsenic, and/or 5 ug/l for cadmium in drinking water to schedule resampling at the tap.
Awaiting sampling data.
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