|Midessa Ground Water Plume||Odessa, Texas|
The Midessa Ground Water Plume is located in Midland County, west of the City of Midland city limits and east of Odessa city limits. The known ground water plume is generally centered along County Road 1290, between Interstate 20 to the south, and Interstate Business 20 to the north.
Chlorinated solvents were first detected at two public supply wells at the Midessa Oilpatch RV Park during routine sampling of public water supply wells by the Texas Commision on Environmental Quality (TCEQ). In July and August 2006, the Texas Commission on Environmental Quality (TCEQ) Superfund Site Discovery and Assessment Program (SSDAP) conducted a Screening Site Inspection (SSI) at the Midessa Ground Water Plume site under the Preliminary Assessment/Site Inspection (PA/SI) Program for the U.S. Environmental Protection Agency (EPA) Region 6 . One Public Water Supply (PWS) with two wells belonging to the Midessa Oil Patch RV Park located on County Road 1290, and 41 private drinking water wells were sampled within a quarter-mile radius of the approximate center of the plume.
The site consists of a ground water plume of a tetrachloroethene (PCE), trichloroethene (TCE) and cis 1,1-dichloroethene and 1-1-dichlorothane contaminated ground water originating from unidentified source(s ). Concentrations of PCE above the U.S. EPA Maxium Contaminant Levels (MCLs) were found in the Midessa OilPatch RV Park public supply wells and eight of the residential wells sampled. In addition, concentrations of PCE were found above the 10-6 cancer screening concentrations in an additional five wells, and detectable concentrations were found in nine additional wells below health based concentrations. Concentrations of PCE in wells range as high as 1200ppb TCE.
Potential Impacts on Surrounding Community/Environment:
The public supply wells serve the Midessa Oilpatch RV Park. The majority of park individuals reside at the park for more than a three month period; there are currently 12 units that have year round residents. Approximately 168 individuals have had their water supply contaminated including the residents of the RV Park and private wells containing one or more of the chlorinated solvents. There is no muncipal city water supply available to this rural sector of Midland county currently, or for the foreseable future. TCEQ has not yet defined the outer boundary of the plume.
Response Activities (to date):
As of February 19, 2007, a filtration system was installed by TCEQ, on the public supply wells at the Midessa Oilpatch RV Park. To date, seven filtration systems have been installed by the TCEQ, accounting for all but one private well found to exceed MCL's for any prior sampling event. One resident refused a filtration system. Currently the TCEQ is providing operation and maintenance for the filtration systems. The current systems have been designed for a six month period.
Need for NPL Listing:
The State of Texas referred the site to EPA because of the presence of TCE in a public water supply. TCEQ and EPA evaluated other cleanup programs to protect drinking water supplies and no other viable options were available. EPA received a letter of support for placing this site on the NPL from the State of Texas.
[The description of the site (release) is based on information available at the time the site was evaluated with the HRS. The description may change as additional information is gathered on the sources and extent of contamination. See 56 FR 5600, February 11, 1991, or subsequent FR notices.]
For more information about the hazardous substances identified in this narrative summary, including general information regarding the effects of exposure to these substances on human health, please see the Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs can be found on the Internet at ATSDR - ToxFAQs (http://www.atsdr.cdc.gov/toxfaqs/index.asp) or by telephone at 1-888-42-ATSDR or 1-888-422-8737.