Groundwater Extraction and Treatment System O&M
Client: USACE Kansas City District
CTI is providing Operation and Maintenance (O&M) services for the Operable Unit OU 2 groundwater extraction and treatment systems at the Rockaway Borough Well Field (RBWF) Superfund Site. The RBWF Site covers a 2-square mile area and includes three municipal water supply wells located in a bedrock glacial aquifer designated by EPA as the sole source aquifer for Rockaway Borough and the surrounding communities. CTI was contracted by USACE Kansas City District in 2011 to implement the long-term monitoring program to monitor plume stability and optimize remediation system performance. During the first year of system operation, CTI identified inconsistencies in the hydrogeologic interpretation and contaminant migration pathways. To address the concerns, CTI evaluated and reinterpreted Remedial Investigation, pre-design, and post construction as-built conditions and developed an innovative 3-D EVS-Pro geostatistical distribution model of the complex hydrogeologic environment and CVOC contaminant migration throughout the valley fill aquifer. The model established the horizontal and vertical groundwater flow paths and contaminant migration from the CVOC source area to the municipal water supply wells and provided CTI remediation engineers with critical groundwater flow, capture zone, and CVOC migration characteristics. Remedial Process Optimization of the groundwater extraction and treatment system included:
- Optimization of CVOC source area pumping rates to ensure capture thereby increasing source area mass removal from 43% to 86% of total CVOCs removed.
- Significant increase in CVOC source area removal reduced downgradient CVOC concentrations from 5,100 ug/l to 17 ug/l in 16 months and to less than 9.0 ug/L in 28 months.
- Maximized CVOC mass removal in down gradient extraction wells.
- Reduction in municipal well field CVOC concentrations from 86 ug/L to 20/ug/l in 28 months with one municipal well attaining non-detect within 4 years of operation.
- Successful completion of over 4 years of operation; maintaining over 93% operational time.