The Washington County Lead District is located in Washington County, MO approximately 100 miles south-west of St Louis. The EPA Emergency Response program has been conducting Removal Assessment and Removal Action activities in Washington County since 2005. There are several EPA Superfund sites located Washington County, including; Potosi, Old Mines, Richwoods, Furnace Creek, Palmer and Pea Ridge. Most of these sites include residential properties contaminated with lead in both soil and drinking water. Lead contamination on site is the result of past surface mining operations that were prevalent throughout Washington County in the Nineteenth to early Twentieth Century. As part of the Superfund Response Action, the EPA provided an alternative water provision to residents with contaminated wells via a monthly bottled water delivery service. This service was provided as an interim measure until suitable drinking water treatment alternatives code be identified.
In order to determine the most appropriate option, a review of domestic water treatment technologies was conducted in a study prepared for the EPA by Shaw Environmental, Inc. in 2010 (“Sampling and analysis of Household Well Water in Mine Waste Areas and Selection of Point-of-Use (PoU) Treatment Devices", Shaw, April 2010). The study reviewed several types of PoU filters including Solid Activated Block Carbon filtration (SBAC), reverse osmosis and atomic adsorption. The report concluded that SBAC treatment systems would be recommended. The report stated that the selection was based on overall contaminant reduction performance, ease of use, and the minimal installation and maintenance costs of these systems.
In addition to lead contamination, a number of residential wells were also identified with cadmium contamination. These properties represent a small fraction of the number of contaminated wells within the County (a total of eleven out of 254 contaminated wells in Washington County have cadmium contamination above the MCL). The 2010 Shaw study recommended that wells contaminated with cadmium utilize reverse osmosis (RO) filtration systems for treatment instead of SBAC. Although SBAC was successful in removing cadmium contamination in some circumstances, SBAC filters were not certified by the National Sanitary Foundation (NSF) for the treatment of cadmium. In testing conducted during the Shaw POU Study, it was observed that cadmium breakthrough in SBAC filters consistently occurred when untreated water contained cadmium concentrations above 20 parts per billion (ppb). Due to this limitation with SBAC, reverse osmosis (RO) filtration units were recommended for all properties identified with cadmium contamination.
In December 2010, SBAC and RO systems were installed in 28 properties at sites within Washington County. The treatment systems were provided at no cost to homeowners. Sampling of these systems and further coordination with residents was conducted throughout 2010-2012 to confirm systems were functioning properly. During this time treatment systems were sampled once a quarter to track the contaminant reduction performance of the filters units. Following the initial installation and evaluation period, additional property owners at the Washington County Old Mines and Richwoods sites responded to the EPA and requested the installation of the systems. These additional installations were conducted throughout 2013-2014.
During the last quarter of 2014, installations were completed for all remaining properties identified with contaminated wells at the Washington Count Potosi site. Some property owners previously receiving bottled water from the EPA decided to purchase their own drinking water treatment alternative and notified the EPA that they would decline the filter. In addition, it was determined at several properties onsite that the installation of the systems could not be performed due to specific configuration and plumbing constraints. Treatment alternatives for these properties are currently under review and will be implemented in the coming months.
Residential yard assessment and soil cleanup activities are anticipated to continue through 2017, it is likely that additional contaminated wells will be identified as assessment work is underway (refer to POLREP #47 for more detailed information regarding yard remediation). The EPA will continue to coordinate remedial options for any additional properties that are identified with contaminated wells.
The list below includes EPA identification numbers and installation dates for all filter systems installed by the EPA at the Potosi Site. One additional property (property ID# 23658) was identified on the site with contaminated drinking water during the reporting period of 10/1/2015-12/31/2015. A drinking water filtration system was installed at this location on December 18, 2015.
| EPA ID# | Install Date | System | 1661 | 9/8/2014 | SBAC | | 23442 | 9/8/2014 | SBAC | | 20701 | 9/8/2014 | SBAC | | 23474 | 9/8/2014 | SBAC | | 24082 | 9/8/2014 | SBAC | | 20591 | 9/9/2014 | SBAC | | TBD | 9/9/2014 | SBAC | | 20427 | 9/9/2014 | SBAC | | 1 | 9/10/2014 | SBAC | | 20339 | 9/10/2014 | SBAC | | 20832 | 9/10/2014 | SBAC | | 449 | 9/10/2014 | SBAC | | 23064 | 9/11/2014 | SBAC | | 20410 | 9/11/2014 | SBAC | | 423 | 9/11/2014 | SBAC | | 116 | 9/15/2014 | SBAC | | 20486 | 9/15/2014 | SBAC | | 115 | 9/15/2014 | SBAC | | 87 | 9/22/2014 | SBAC | 89 | 10/6/2014 | SBAC | | 41 | 10/6/2014 | SBAC | | 20467 | 10/6/2014 | SBAC | | 20321 | 10/7/2014 | SBAC | | 470 | 10/7/2014 | SBAC | | 20397 | 10/7/2014 | SBAC | | 20604 | 10/8/2014 | SBAC | | 20603 | 9/8/2014 | SBAC | | 20362 | 10/8/2014 | SBAC | | 20362B | 10/8/2014 | SBAC | | 23482 | 10/8/2014 | SBAC | | 20459 | 10/9/2014 | SBAC | | 20379 | 10/9/2014 | SBAC | | 20465 | 10/13/2014 | SBAC | | 23712 | 10/13/2014 | SBAC | | 20625 | 10/13/2014 | SBAC | | 23427 | 10/27/2014 | SBAC | | 20917 | 10/27/2014 | SBAC | | 20332 | 10/27/2014 | SBAC |
1653 | 10/27/2014 | SBAC | | 20576B | 10/28/2014 | SBAC | | 20618 | 10/28/2014 | SBAC | | 20270 | 10/28/2014 | SBAC | | 23429 | 10/31/2014 | SBAC | | 20833A | 11/11/2014 | SBAC | | 20519 | 11/11/2014 | SBAC | | 441B | 11/21/2014 | SBAC | | 441A | 11/21/2014 | SBAC | | 20941 | 11/21/2014 | SBAC | | 24400 | 11/21/2014 | SBAC | | 75 | 11/21/2014 | SBAC | | 20455 | 12/16/2014 | SBAC | | 20331 | 12/23/2014 | SBAC | | 20503 | 1/16/2015 | SBAC | | 525 | 1/16/2015 | SBAC | | 524B | 1/16/2014 | SBAC | | 20344 | | Softener | | 1661B | | Softener | | 1663 | | Softener | | 20833B | | Softener | | 20604 | | Softener | | 20467 | | Softener | | 20305 | Decline | | | 20334 | Decline | | | 20576C | Decline | | | 23428 | Decline | | | 20325 | Decline | | | 24125 | Decline | | | 23566 | Decline | | | 69 | Decline | | | 20340 | Decline | | | 64 | Decline | | | 20424 | Decline | | | 20833B | Decline | | | 491 | Decline | | | 20380 | Decline | | | 20373 | Decline | | | 23438 | Decline | | | 23658 | 12/18/2015 | SBAC |
Summary of Residential Yard Cleanup Activities
Total Properties Remediated: 299
Total SBAC Water Filtration Units Installed: 56
Total Water Softeners Installed: 6
During the installation activities for the filter project, it was determined that installations were not feasible at several properties on the site. This was due mainly to configuration and plumbing limitations. These properties will remain on bottled water as alternative options are being evaluated. It is anticipated that these will be addressed in the next year or less.
It is anticipated that the EPA Remedial program will be conducting further sampling at the site as part of the RI/FS and will be addressing treatment issues for any new wells that are identified with lead or cadmium contamination at the Potosi site.
At this time cleanup activities under the Removal Action will continue for an extended period of time due to ongoing contract disputes in the Remedial Program.
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