GZA investigated and undertook complex soil and groundwater remediation at this site, impacted by historic manufactured gas plant (MGP) activities, which houses the town’s century-old, 165-foot water tower. The high-profile project, located in a residential/commercial area, also addressed multiple stakeholder concerns.


GZA delineated impacted soil and groundwater and prepared a remedial alternative feasibility study which included bench scale testing and groundwater flow and contaminant transport modeling. GZA determined that volatile and semi-volatile organic compounds (VOC and SVOC, respectively) present within the near surface groundwater aquifer were separated from and did not impact the isolated and significantly deeper drinking water aquifer. Remediation of impacted soils included: in-situ solidification of impacted soil to approximately 65 feet below grade, excavation and removal of impacted overburden soil to allow for the ISS fluff, and installation of new subgrade utilities in a clean soil cap. This remedial approach, combined with an extensive network of geotechnical instrumentation that monitored the effects of construction on sensitive structures (including the water tower) and an eight-station automated perimeter air monitoring system that tracked real time dust and total and compound specific VOC concentrations, precluded the need for costly containment structures and air treatment units. The project also required demolition of existing buildings; temporary re-routing and then installation of new subsurface utilities including a water main, storm and sanitary; and a new roadway. Groundwater quality continues to be monitored to verify the accuracy of GZA’s Conceptual Site Model. GZA also served as both the design engineer and Construction Manager for this multimillion-dollar remedial effort.


GZA drew upon its multidisciplinary services to remediate a highly scrutinized, multifaceted site and to address stakeholder and regulatory concerns. Strategic sequencing of construction and beneficial reuse of soil created significant savings for the client.