REFURBISHMENT, RECONSTRUCTION & TESTING OF AN EXISTING LARGE DIAMETER, SCREENED AND GRAVEL-PACKED MUNICIPAL PRODUCTION WELL
CLIENT: Town of Rothesay
LOCATION: Rothesay, New Brunswick, Canada
BGC staff have been providing professional hydrogeological expertise to the Town of Rothesay (TOR) since 2002. This work is associated with the development, protection, assessment and maintenance of their Carpenter Pond Wellfield. At the request of the Town, BGC staff refurbished and reconstructed an existing (old and prior high-yielding) production well in their wellfield. This well had experienced progressively declining pumping yields and increasing sand pumping for several years, as a result of a worsening screen breach and buckling that was first noted by BGC staff during a well assessment completed in 2007. The well refurbishment and reconstruction was completed throughout 2016, and, in general, consisted of removing the existing well materials, reconstructing the well with new materials, and redevelopment of the well, each in accordance with technical specifications made by BGC.
In the well reconstruction process, a new (second, upper) screened interval was added, which required additional development time using a combination of air jetting and well surging tools and methods. Indicators throughout development included changes in water clarity, volume of sand pumped, estimated flow and recording of various water quality indicator parameters in the field (i.e., pH, Eh, DO, Conductivity, TDS, and temperature). Once these physical and chemical indicators stabilized, it was determined that well development was complete.
Hydraulic testing was then completed in accordance with the applicable New Brunswick Department of Environment and Local Government (NBDELG) Water Supply Source Assessment (WSSA) Guidelines to derive the relevant aquifer parameters, extent and degree of potential well interferences, and to estimate the new, long-term safe yield for the refurbished and reconstructed well (1,360 m3/day, or 250 USgpm). This new safe well yield compared with the pre-refurbishment yield of approximately 327 m3/day, or 60 USgpm, translated to a quadrupling of well yield immediately following completion of this successful well refurbishment project.
Additional well reconstruction and refurbishment projects have since been successfully completed by BGC in 2017 and 2020, for two other (older) existing production wells within the Town of Rothesay’s Carpenter Pond Wellfield. An annual well rehabilitation program has also been completed at the wellfield by BGC since 2006, which involves well assessments, sampling and thorough chemical treatments of two or more supply wells that most warrant treatment each year. The on-going associated well rehabilitation methods and processes have been continually fine-tuned to reflect past findings.