Fishbeck was retained by the Gratiot Area Water Authority to assess the geological and hydrogeological setting and aquifer production at Well No. 12.
Fishbeck analyzed available well logs, published reports, and test borings/wells data (such as sieve analysis results) to generate a conceptual understanding of the geological and hydrogeological setting in which the well would be installed.
Well No. 12 was installed in January 2021 by Peerless Midwest, Inc. (Peerless) using mud rotary drilling methods. Well No. 12 was completed at a depth of 255 feet below ground surface (bgs), constructed of 16-inch diameter steel casing, and equipped with a 40-foot long, slot 35, stainless steel screen.
Well No. 12 was completed in a confined aquifer comprised of glacial outwash deposits. An aquifer performance test was performed at Well No. 12 in February 2021., which calculated aquifer coefficients of transmissivity (T) and storativity (S). The rated capacity of Well No. 12 was determined to be 597 gallons per minute (gpm) based on the requirements of the Large Quantity Withdrawal Permit, well construction, and pump design characteristics.
Fishbeck used a numerical groundwater flow model to predict local and regional drawdown and its effect on nearby wells and environmental contamination sites.
Water samples were collected from Well No. 12 and analyzed for EGLE-required water quality parameters. Laboratory results indicated that water from the test production well meets all applicable federal water quality standards, with the exception of arsenic, which exceeded the federal and state maximum contaminant level (MCL); and iron which exceeded the federal secondary drinking water standards.
