Authors: M.D. Armstrong, W.R. Hoyle, B.G. Bennett
Abstract
An industrial facility in New Brunswick was found have three distinct areas of groundwater contamination (fuel oil, gasoline, and TCE). A Remedial Action Plan was implemented using two small dual phase extraction (DPE) systems and a potassium permanganate (KMnO4) injection system for the remediation of the petroleum hydrocarbons and TCE, respectively. Given typical Maritime winter conditions, the treatment systems were designed such that they would be shutdown instead of operating through extreme weather conditions. This not only allowed for savings in both capital (i.e., no insulation requirements) and operating/maintenance (i.e., heating and rectifying possible pipeline freeze-up) costs, but also enabled the subsurface conditions to stabilize to a new equilibrium between the spring to fall operating periods. The winter shutdown also allowed the residual KMnO4 to degrade, which enabled representative groundwater samples to be collected in the spring to confirm whether the remedial targets had been met. Both DPE systems used a network of existing monitoring wells and newly installed 100mm diameter recovery wells.
Pneumatic pumps were installed in these wells instead of electric submersible pumps for reduced cycling, improved groundwater level control and ease in rearranging the recovery well networks. Each DPE system also has five available recovery wells for four pneumatic pumps, which reduced the initial capital expenditures. Since both DPE systems are based on the same design, components can be transferred to where additional remedial efforts may be required with minimal effort. Greater than expected quantities of LNAPL (gasoline and fuel oil) during the first operating season resulted in an associated larger consumption of activated clay and liquid phase granular activated carbon. In response, the anticipated modifications to the DPE systems will include an oil water separator and an oliphobic filter unit.
