Superfund Information Systems: Site Profile

Superfund Site:

SOLID STATE CIRCUITS, INC.
REPUBLIC, MO

Cleanup Activities

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Background

The Solid State Circuits, Inc. (SSC) Site is located in the old downtown of Republic, Missouri. The SSC site is less than one acre in size and is enclosed within a six-foot high chain link fence. The original plant building and basement were constructed prior to 1902. The building’s northern portion was four stories tall, the rest was one story. Numerous businesses operated on-site through the years in the building and little is known about chemicals used on-site. From 1902 to 1937, a cold refrigeration plant operated in the building’s northern portion. SSC operated in the building’s northern portion from 1968 until 1973, when SSC moved. SSC manufactured printed circuit boards and used trichloroethylene (TCE). The amount of TCE used is unclear due to poor record keeping. A photographic-processing firm operated on-site from 1973 until 1979, when the northern portion burned. The burned portion was demolished, the debris was pushed into the basement, it was filled-in to grade and the area is a vacant gravel lot. The former SSC manufacturing and plating plant was identified as the source of the TCE contamination. The site was listed on the Superfund National Priorities List (NPL) on June 10, 1986. EPA and MDNR entered into a Consent Decree with the responsible party for the cleanup.

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What Is Being Done to Clean Up the Site?

The Missouri Department of Natural Resources (MDNR) collected water samples from Republic's public water system in June 1982. Trichloroethylene (TCE) contamination was detected in Republic's municipal well CW-1, which triggered further investigations. Between April 1983 and March 1984, MDNR and EPA initiated response actions to identify contaminant sources and further investigate the TCE occurrence in well CW-1. In 1985, EPA removed about 2,000 cubic yards of soil from the basement, the soil underneath the basement and assorted debris to stabilize the site. EPA filled the basement with gravel and soil cover to bring it up to grade. EPA plugged the abandoned basement well and installed two wells to extract contaminated groundwater.

 

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What Is the Current Site Status?

The site is being addressed through federal, state and PRP actions. MDNR is the lead regulatory agency, with EPA in a regulatory support role. The potentially responsible party (PRP) installed the site’s remedy. It included extraction of contaminated groundwater using extraction wells; on-site treatment of extracted groundwater using two air strippers; discharge of treated water; and implementation of a city ordinance to prevent construction of drinking water wells in or near the contaminated groundwater plumes. EPA later updated the remedy to include use of a horizontal reinjection well. On December 8, 2011, a fire destroyed the groundwater treatment system and it is no longer operating. The responsible party is currently under a Force Majeure/Excusable Delay Agreement originally signed on June 15, 2011, then modified and re-signed on March 13, 2015. Under the revised agreement, continued site investigation, vapor intrusion sampling, cleanup and groundwater monitoring activities are ongoing.

 

The EPA has conducted several Five-Year Reviews of the site’s remedy. These reviews evaluate whether the remedies put in place protect public health and the environment, and function as intended by site decision documents. The September 2017 review indicated that the protectiveness of the remedy could not be determined until further data and information is obtained, due primarily to the destruction of the groundwater treatment system by fire in December 2011. Further data and information will be obtained by taking the following actions: completing a comprehensive vapor intrusion study of all structures overlying potentially impacted groundwater; addressing all soil source areas; delineating the contaminant plumes in all three water bearing zones; and fully containing the contaminant plumes in groundwater.


 

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Sampling and Monitoring

Groundwater samples are collected from site monitoring wells and the city water supply wells. Vapor Intrusion sampling is currently being conducted.

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