Q-Bridge Groundwater Treatment System

Connecticut Department of Transportation - New Haven, CT

RED was contracted through the Connecticut Department of Transportation to manage and operate the Central Groundwater Treatment Facility (CGWT) on the estimated $450 million dollar Q-Bridge project located in New Haven, CT. Surface preparations of the concrete bridge deck overlay for I-95 Northbound were conducted and included cutting, grinding and sand blasting. Surface preparations included an application containing latex modified concrete; the by-product of which generated a slurry-rich, alkaline wastewater with a pH of 12.44. Due to effluent discharge limitations of the CGWT facility, wastewater was required to be pretreated to a pH between 6.5 and 9.5 before the wastewater could be treated through the CGWT facility.

The slurry-rich wastewater was transported to the waste stockpile area and offloaded into temporary containment structures, constructed of earthen berms, to allow the solids to settle out of solution. Approximately 35,000 gallons of wastewater were decanted from the temporary structures and containerized into fractionation tanks.

RED performed an initial pilot test by introducing muriatic acid to 30 gallons of wastewater using a designed chemical injection feed system. The test was performed to determine the quantity of acid required to achieve the desired pH level and to confirm hydrogen gas would not be created nor cause a personnel safety issue.

Following satisfactory pilot test results, muriatic acid was metered through a chemical injection feed system to the fractionation tanks and monitored until the desired pH was achieved. Based on the specific chemistry of the wastewater, approximately 62 gallons of muriatic acid was added and resulted in a final pH of 6.88.