Owner/Client
Neville Chemical Company
Location
Pittsburgh, PA
CEC Services
- Environmental Investigation
- Groundwater Modeling
- Remediation Design
- Groundwater Sampling
- NAPL Collection and Recovery
CEC performed a comprehensive groundwater assessment and remedial design related to an Administrative Consent Order and Act 2 compliance at the Neville Chemical facility along the Ohio River. Work involved groundwater investigations, remedial design, air sampling, human-health and ecological risk assessment, groundwater modeling, remediation system design, permitting, and regulatory negotiation.
CEC began work with a groundwater investigation of the 75-year old organic chemical facility, which is located on an island in the Ohio River. A lock and dam system imposes a differential head across the island, so that groundwater flows from the back channel, across the island and through the Neville facility, discharging to main channel. Working with a well network installed previously, CEC installed additional wells and determined that groundwater was impacted by chlorinated and aromatic VOCs, LNAPL and DNAPL. Multiple pump tests were conducted to determine aquifer properties and facilitate the design of a system to prevent impacted groundwater and LNAPL from discharging to the main channel of the river.
CEC performed digital groundwater modeling to design a remediation system that will intercept all groundwater flowing across the island as well as remove LNAPL that accumulates in the resulting capture zone. The system includes eight high capacity pumping wells that intercept groundwater over the entire 2,500-foot downgradient property line. Water is treated with aqueous granular activated carbon. Extraction wells were installed using cable tool techniques and utilizing stainless steel screens with variable screen slot sizes based on aquifer samples collected during drilling. CEC utilized well development techniques to produce a natural pack around the well screens utilizing the natural sand and gravel aquifer. Capacity testing on the wells revealed them to be extremely efficient within the predicted pumping range. Measured drawdown and radius of influence were very close to those predicted by the numerical groundwater model. The extraction well design is complicated by the presence of LNAPL which is incompatible with much of the available removal equipment. CEC designed the wells with adjacent interceptor wells and removal equipment to be capable of removing LNAPL from the capture zone of the groundwater extraction wells. The final system was automated with level controls on the wells to maintain the proper groundwater gradient to achieve compete groundwater capture inclusive of river fluctuations. The entire system is computer controlled with little manual supervision required. The system also continuously records river and well levels to show that groundwater containment is being achieved.
CEC is providing ongoing support for the groundwater control system including periodic redevelopment of the extraction wells to maintain well efficiency, semiannual groundwater sampling at 20 monitoring wells and collecting static water level and LNAPL levels in 28 wells on a quarterly basis.
