Groundwater Extraction and Treatment System O&M

LOCATION: Rockaway Borough, New Jersey
CLIENT: USACE Kansas City District

PROJECT DESCRIPTION

The Rockaway Borough Well Field (RBWF) Superfund Site covered a two-square mile area and includes three municipal water supply wells located in a sole source complex hydrogeologic bedrock valley-fill glacial aquifer.

For this HTRW remediation project, CTI performed RBWF Operations and Maintenance (O&M) activities and optimization services for the Operable Unit (OU)-2 Groundwater Extraction and Treatment Systems. Our efforts support the USACE Kansas City and New York Districts technical assistance to USEPA Region 2 under an Inter-Agency Agreement.

CTI operated the GWTS since July 2011 and routinely optimized the groundwater extraction pumping rates to maximize PCE mass removal and ensure source area containment to protect the downgradient municipal well field. The groundwater collection system was comprised of five extraction wells at the CVOC source area and within the downgradient plume.

The treatment system included a combination of particle filtration and air stripping capable of treating a process flow rate of 210 gpm and sized to meet the NJDEP Permit Equivalency discharge requirements. A VPGAC system was designed to remove 95% of CVOCs to ensure vapor discharged meets the NJDEP Air Pollution Control Permit Equivalency. CTI’s responsibilities included 24-hour response to alarm conditions, routine system maintenance, weekly system VPGAC performance checks, monthly influent / effluent monitoring, and all permit-related monitoring and reporting.

In August 2015, the operation of the RBWF OU-4 source area soil vapor extraction system (SVE) was merged with this Task Order to streamline and coordinate remediation of the CVOC source area. The SVE system included two vertical and one lateral SVE wells, a blower operating at 750 cubic feet per minute, and two 250-pound VPGAC. CTI evaluated and reinterpreted the RI, pre-design, and post construction as-built conditions to develop an innovative three-dimensional Environmental Visualization System (3D EVS-Pro) geostatistical model to reduce contaminant migration uncertainty and provide critical groundwater flow, capture zone, and CVOC nature and migration characteristics for Remedial Process Optimization (RPO).

Statistical analyses to successfully justify cost savings included a reduction in the number of monitoring wells sampled and a reduction in the sampling frequency, as appropriate. Additional monitoring wells were installed to fill identified data gaps, monitor potential contaminant migration pathways, and integrate local river and impoundment surface water elevations with the groundwater elevations to enhance the understanding of the groundwater flow regime. To monitor plume stability, CTI performs semi-annual groundwater monitoring of 45 wells and quarterly monitoring of 6 wells using passive diffusion bags (PDBs).

Category: Projects