RETTEW Associates, Inc. (RETTEW), had prepared a layout for an impoundment structure to store process waste fluid from hydraulic fracturing operation associated with shale gas drilling in Barbour County, West Virginia, for CNX Gas Company, LLC. For this project, RETTEW requested consulting assistance from TRC in the design and development of the double geomembrane liner system for the impoundment.
TRC’s services included geotechnical analysis, geosynthetic design, leak detection system sump design, and pump sizing. The geotechnical analysis included evaluation of the results of a subsurface soil and groundwater exploration at the site, evaluation of global slope stability of the interior and exterior slopes, and evaluation of stability between the geosynthetic interfaces. The impoundment consisted of a surface area of approximately 3 acres with a capacity of approximately 7 million gallons.
TRC developed engineering plan sheets for a plan set to be included with the permit application submittal and for construction of the impoundment. The impoundment capacity was designed such that the structure would not fall under the requirements as a dam, but as a centralized waste pit classified by the West Virginia Department of Environment Protection Office of Oil and Gas. The engineering plan set was developed in AutoCAD/Civil 3D format, which included a liner grading plan, a cross section sheet, and multiple details sheets. As part of the permit application submittal, TRC also evaluated two groundwater flow paths for a breach analysis and hazard survey for the impoundment.
TRC prepared engineering plans for the permit application submittal, which would also be used by the contractor during construction of the impoundment. In addition to the plan set, TRC prepared an Inspection Plan for the engineer supervising during construction, a Construction Quality Assurance and Quality Control Plan for the contractor to follow during liner construction, and specifications for materials and installation for the double liner system. The specifications for the project followed the Design and Construction Standards for Centralized Pits developed by the West Virginia Department of Environmental Protection Office of Oil and Gas.
TRC provided RETTEW with consulting services related to tasks that fell outside RETTEW’s area of expertise. TRC worked in concert with RETTEW’s engineers to successfully design, permit and construct a centralized pit that met agency requirements so that their client, CNX Gas Company, LLC, could continue site operations without interruption.
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