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Groundwater Well Installation Standard Operating Procedure SWE-FSOP-601;Revision 1 Ahtna Southwest Environmental Operations • Unless otherwise specified, cement grouts should be mixed using approximately 6 to 7 gallons of water per 94-pound bag of Type 1/11 Portland cement to a density of approximately 15 pounds/gallon. • If needed, add bentonite (5 to 10 percent)to the cement grout to strengthen the mix and delay the setting time. • Specific mixtures and other types of cement and grout proposed should be evaluated on a case- by-case basis by the field geologist and communicated to the drillers. During grout installation, maintain the bottom of the tremie pipe below the top of the grout to prevent free fall and bridging. When using drive casing or hollow stem auger techniques, raise the drive casing/augers in short increments during grout pouring, keeping the bottom of the drive casing/augers below the top of the grout. It is essential to calculate the approximate volume of grout required; note reduced/excessive volumes, which may indicate irregularities in the annulus or grout flow into a formation. Cease grouting when the grout level has risen to approximately one to two feet of the ground surface, depending on the surface completion type (flush-mount versus aboveground). Monitor grout levels to ensure that grout taken into the formation is replaced by additional grout. If settling occurs, additional topping off of the grout may be necessary. 4.3.7 Protective Casing For aboveground completions, place the protective steel casing (e.g., lockable "stovepipe") over the top of the well casing and insert it into the freshly grouted annulus. Before installation, place a 2-inch thick temporary spacer between the PVC well cap and the bottom of the protective casing cover to keep the protective casing from settling onto the well cap. Note: confirm the final clearance required between the top of the well casing and the cover; additional room may be needed for dedicated well equipment. After the protective casing is set in the grout, a drainage hole may be drilled into the protective casing if required in project work plans. The drainage hole is positioned approximately two inches above ground surface. Paint the protective casing with rust-preventive colored paint. Make sure the well is protected from potential vapors from paint. Label the wellhead to provide information such as well number, depth, and date of the installation based on project requirements. Wait 24 hours after grouting before installing concrete pad and steel guard posts (bollards) for aboveground completions or street boxes or vaults for flush-mount completions. Aboveground Completions A concrete pad, usually 3-foot by 3-foot by 4-inch thick, is constructed at ground surface around the protective steel casing. The concrete is sloped away from the protective casing to promote surface drainage away from the well. Where traffic conditions warrant extra protection, embed three to four steel guard posts (bollards) to a depth approximately 1.5 feet below ground surface with three to four feet of stickup depending on project requirements. Install the posts in concrete-filled post holes spaced equally around the well, commonly at 1.5 feet from the protective steel casing (check work plan for exact specifications). Where posts are removed for well access, embed mounting sleeves into the concrete. Page 13 of 16