NJ011 – Fracturing and Atomized Emplacement of SRS
Northern New Jersey
At this former manufacturing facility in northern New Jersey, ARS was contracted to apply Pneumatic Fracturing (PF) and Atomized Liquid Injection (ALI) to address PCE contamination resulting from discharges in a former dry well at the facility. Groundwater in the underlying Brunswick Shale formation had been impacted with Tetrachloroethene (PCE) at concentrations ranging from 1.0-4.0 mg/L in the shallow bedrock zone beneath the dry well. Long-term groundwater data indicated the shallow and deep bedrock aquifer source area was conducive to anaerobic bioremediation. A focused remedial design investigation, including a microcosm study, was performed to select and design an appropriate remedial approach. The investigation characterized the bedrock formation as having an average of 2 fractures per 10 vertical ft. The fractures were filled or partially filled with calcite or open but tightly spaced, and as a result, the maximum achievable liquid injection rate without significant back pressure was only 7.5 gallons per minute. The study concluded biostimulation with bioaugmentation could be used to remediate the groundwater.
Prior to fracturing, down-hole geophysical testing was used to identify and select fractured zones within the open boreholes for targeted injections. Packers were used to isolate 4-5 fractured zones within each well during the injections to facilitate lateral substrate distribution. One existing monitoring well and three bedrock injection wells were used for fracturing and injections. Approximately 60-75 gallons (or 160 to 200 lbs. of emulsified vegetable oil) of dilute SRS™ was injected into each fracture zone.
Real-time data coupled with post-injection measurements confirmed an approximate 35 ft. injection radius of influence. In addition, significant decreases in DO and ORP into anaerobic conditions were measured 90 ft. in the down-gradient groundwater and bedrock strike direction. Bioaugmentation was performed three months after the EVO injections using the same technique.
Groundwater data collected 60 days after the SRS™ injection indicated anaerobic groundwater conditions favorable for reductive dehalogenation in a 30,000 square ft. area around the injection wells in the upper 40 ft. of the aquifer. Shallow bedrock monitoring wells (i.e., upper 20 ft.) within the injection zone experienced a 90% or greater reduction in PCE, minimal generation of TCE, 1,2-dichloroethene, vinyl chloride and significant (i.e., 150% to 200%) increases in hydrogen concentrations. The deep wells in the same area have also seen similar changes to the groundwater quality.