STP963: The Modified Reverse-Circulation Air Rotary Drilling Technique for Development of Observation and Monitoring Wells at Ground-Water Contamination Sites

    DB, Bennett
    Hydrologist and environmental engineer, Edward E. Clark Engineers—Scientists, Inc., Miami, FL

    Busacca, M
    Ecological analyst, DF-EMS, National Aeronautics and Space Administration, Kennedy Space Center, FL

    EE, Clark
    Hydrologist and environmental engineer, Edward E. Clark Engineers—Scientists, Inc., Miami, FL

    Pages: 9    Published: Jan 1988


    Abstract

    Ground-water monitoring regulations on the state and Federal level establish general performance standards for the construction of monitoring wells. Of the many drilling techniques available for the construction of monitoring and observation wells, dry techniques are recognized as superior at sites of contamination. The dry technique of modified reverse-circulation air rotary drilling (RARD) is viable and a more advantageous alternative than many traditional techniques. It requires no liquid drilling fluids or muds, and therefore no foreign fluids are added to the aquifer. Furthermore, composite soil and water samples are collected during installation specifically and exclusively from the bit depth and are uncontaminated by drilling fluids. The method utilizes compressed air to clear the borehole and a tube within a tube drill pipe system to maintain the borehole. This allows the well assembly, filter pack, and borehole sealant to be properly placed thereby satisfying the strictest regulatory requirements for short and long-term monitoring. The method accommodates various field testing such as the measurement of in situ hydraulic conductivity and the collection of soil cores. To insure proper construction of monitoring wells, procedures and material requirements must be designed and fully specified.

    Keywords:

    modified reverse-circulation air rotary drilling, monitoring well construction, ground-water contamination


    Paper ID: STP44854S

    Committee/Subcommittee: D18.21

    DOI: 10.1520/STP44854S


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