Wright-Pierce recently completed design, construction, and startup of a new 1.152-mgd groundwater supply well and iron and manganese removal water treatment plant for the Town of Bethel, CT. The project began in 2017 when the Bethel Public Utilities Commission (PUC) retained Wright-Pierce to assist with its water sourcing needs. At the time, the PUC operated multiple reservoir systems in conjunction with the Maple Avenue Wellfield. Because the surface water sources were costly to operate and provided low yield relative to the well source, the PUC decided to discontinue their use and to replace them with new groundwater wells. Wright-Pierce was selected to provide planning, exploratory drilling work, and permitting for the new groundwater supply source.
After the new well source was developed and permitted, Wright-Pierce worked with the Town of Bethel to evaluate alternative locations for the new water treatment plant. While the process included the evaluation of three potential sites, the Town ultimately selected an existing Town-owned property adjacent to the new well site.
Unique Site Challenges
The selected site presented engineering challenges. These included a high groundwater table and soft clay soils underneath the proposed water treatment plant building. Wright-Pierce, along with our geotechnical and ground improvements subconsultant Earth Design Associates, Inc., evaluated various options for ground improvements to mitigate impact to existing soft clay soils. Based on the analysis, Earth Design Associates, Inc. recommended the installation of GEOPIER® ground improvements, including rammed aggregate piers, beneath the building foundation.
The iron and manganese removal process uses Hungerford and Terry’s automatic pressure-type filtration system with GreensandPlusTM media. This treatment process requires backwash water source and backwash water storage tankage, which is typically designed and constructed beneath a treatment building. Because of the high groundwater table at this site, we constructed at grade two 40,000-gallon horizontal carbon-steel tanks for backwash water source and backwash water storage. Placing these tanks at grade eliminated the need for extensive dewatering and excavation beneath the building footprint, which provided significant cost savings to the Town. Additionally, disinfection contact time and 4-log removal are achieved in the finished water transmission main, eliminating the need for a clearwell.
Water Treatment Plant Startup and Project Impact
The water treatment plant was placed online in October 2025 and represents a significant investment by the Town of Bethel in its water system. The project was funded in part by a grant and a low-interest loan from the Connecticut Department of Public Health Drinking Water State Revolving Fund (DWSRF).
Regional Group Leader Mariusz Jedrychowski—who led both the groundwater exploration efforts and the water treatment plant design efforts—had this to say about Bergstrom Well and water treatment plant project: “Completion of this project brought the Town of Bethel to their long-term goal to replace their aged, existing surface water plants with a new groundwater source, providing excess water supply to their growing and vibrant town population and businesses. Wright-Pierce is proud that we could support the Town of Bethel on this important project.”
Contact us today to learn more about the project, the DWSRF program, or how we can provide similar services to your community.