The objective of this optimization project was to increase the rate of removal of perchloroethylene (PCE) contamination present in the groundwater from a number of former and active dry cleaners in the historic downtown of the City. Provost & Pritchard evaluated several alternatives to the existing air striper system. The goal was to maximize the volume of groundwater pumped and treated. The existing shallow tray air stripper was becoming unusable due to the precipitation of calcium from water due to the reduction of pH by the air stripper. The system was redesigned to utilize liquid phase activated carbon as a treatment alternative. This allowed the doubling of pumping rates and reduced O&M by City staff by 70%. Additional services included associated groundwater monitoring over a three-year period to assess the effectiveness of the remediation system by measuring concentrations of PCE, TCE, and other related breakdown chemicals within downtown Turlock.
Provost & Pritchard is currently providing environmental assessment and remedial services for the City of Merced’s Designated Local Authority (former Redevelopment Agency) R Street site which encompasses two gasoline service stations and a Methyl Tertiary Butyl Ether (MTBE) plume that has migrated over 1,500 feet down gradient. The project also includes assessment of total petroleum hydrocarbons (TPHg) from gasoline and related compounds, and remediation from two larger releases. Project responsibilities include assisting the client with project funding management—including a Brownfield grant, data review, communication with the Regional Water Quality Control Board, preparation of a focused feasibility study, groundwater monitoring and reporting for more than 50 groundwater monitoring wells, and the preparation of the Final Remedial Plan and implementation of two ozone sparge remedial systems across the entire project site including 40 Soil Vapor Extraction wells and 50 ozone sparge points. Since being retained on the project, the concentrations of TPHg and MTBE have fallen by orders of magnitude and the site is nearing closure. In additional to the technical aspects of the project, Provost & Pritchard has provided litigation support and expert witness services in two MTBE cases.