Background/Objectives. Petroleum hydrocarbons (PHC) originated from a fueling service station and migrated offsite beneath an apartment building. In situ remediation was recommended to provide additional assurance on minimizing vapor inhalation risks associated with PHC impacts present beneath the building. The in situ remediation approach combined physical PHC removal (multiphase vacuum extraction (MPVE)) and enhanced aerobic bioremediation with air sparging. Limited access beneath the building and surrounding properties (i.e., roadways) required the installation of single entry (blind) horizontally drilled soil vapor extraction (SVE), air sparging and MPVE dewatering line concepts as major components of this remediation system. Blind horizontally drilled lines are avoided where possible, due to the complications attributed to borehole collapse, drill cutting removal inefficiencies and the risk of well refusals during the installation process. Siltation within horizontally installed remediation lines is also well known by industry to reduce the effectiveness of the lines. The objective was to develop a blind horizontal line installation method that increased the installation success of single and multiple line configurations, and to assess the ability of the dewatering line concepts to reduce silt intrusion and accumulation within the lines.
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