Assessment of Oil Field Activities, Non-Point Source Pollution & Water Quality in the Spring Creek Watershed and the City of Edmond Municipal Well Field

Since 1987 several homeowners in the Thunderhead Hills addition in Edmond, OK have experienced elevated concentrations of salt in their private water wells. As of 1999, there were at least twenty-two (22) domestic water wells degraded by salt water at concentrations exceeding the USEPA secondary standard for Chlorides in drinking water of 250 mg./L.  As a consequence of the contradictory conclusions reached by two studies conducted in 1997 and 1998, the need to more thoroughly investigate the problem, and the threat presented by the potential discharge of salt water into surface waters, the Oklahoma Corporation Commission contracted the Ground Water Protection Council to conduct a study into the possible causes of ground water contamination in the Thunderhead Hills area.

The purpose of the study was to use existing and newly gathered geophysical, geochemical and hydrologic data to:

• Determine the location, vertical and horizontal extent, and movement of the salt water plume(s) relative to the study area; and
• Characterize the geochemical makeup of the salt water for comparison with potential sources of contamination; and
• Eliminate potential sources of contamination and, if possible, identify the specific source or sources of the plume(s)

By evaluating hydrogeologic setting, plume delineation, geochemical framework and land use, the study successfully:

• Established the subsurface characteristics of the study area that controlled the vertical and lateral movement of plumes
• Determined the size, depth and movement of plumes
• Established the chemical relationships between contaminated water and potential contaminant sources
• Determined past and present land uses to eliminate potential sources and establish the framework for evaluating the geophysical, hydrogeologic and geochemical data used in the study