The emergence of horizontal directional drilling (HDD) technology has introduced an innovative approach for the installation of ground water wells. The horizontal configuration seems appealing for remediation scenarios where an affected area is quite large in lateral extent, and a horizontal well could potentially be more effective than a vertical well. The technology also may be beneficial in reaching areas under large buildings that would otherwise be difficult to access with vertical wells.
Horizontal wells have been installed for air sparging, soil venting, and ground water extraction since the late 1980s. Initial installations of these wells in both saturated and unsaturated sediments have produced encouraging results. Unfortunately, comprehensive performance studies of field installations are scarce, leaving the design aspects of these wells to either a trial-and-error approach or to computer models that have not been validated to this application.