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SEE...The Difference! |
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Stell Environmental Enterprises, Inc. |
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Project Description |
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Waste disposal in a geologically complex setting provides unique ground water characterization challenges. Highly folded and fractured geologic strata can result in ground water flowing in multiple, or unexpected, directions. Incorporation of geophysical surveys and expedited analysis of ground water grab samples from boreholes allowing optimum monitoring well placement can provide a timely and cost effective approach to define the extent of contamination in a single field effort. SEE brings together the necessary field equipment, experience, and insight to conduct successful and cost effective ground water characterization assessments in highly complex geologic settings.
A seismic reflection survey was performed to define the subsurface geological features that may be influencing ground water flow. An iVi Minibuggy vibrator, which is capable of maneuvering in the steep and rugged terrain encountered at this site, was used as the seismic source. Multiple receiver channels and appropriate station spacing were used to image to the depth of a regional ground water aquifer, some 700 feet. A Geometrics Strataview seismograph recording system and geophones capable of recording frequencies in excess of 500 Hz were used for the survey. Following analysis of the seismic data, the results were incorporated with traditional sources of geological data such as surface geologic mapping and boring logs. This approach of integrating different types of geologic information led to an enhanced interpretation and superior understanding of the site hydrogeology.
Two sandstone intervals were identified as the most likely transport pathways for contaminated ground water and were targeted for subsurface investigation. Ground water grab samples were collected from the boreholes and analyzed using an expedited turn-around-time. The results from these samples were used to finalize placement of subsequent boreholes to ensure that the extent of contamination was delineated during a single field effort. A monitoring well network was located and installed using information obtained during the field effort. Subsequent sampling of the field-located wells has confirmed that the horizontal and vertical extent of ground water contamination has been delineated.
The integrated field program resulted in the client complying with RCRA ground water monitoring requirements; thus, avoiding a regulatory compliance order and associated financial penalties. The results of this effort were a timely and cost effective ground water plume definition and completion of a monitoring well network in a single field effort. |
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OBOD Area: Showing Complex Geology |
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Delineation of Ground Water Contamination in a Complex Geologic Setting, RCRA Permitted Open Burning/Open Detonation Area, Gallup, New Mexico |
