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Adams County <br /> Arapahoe County <br /> Aurora,CO <br /> E-470 Public Highway Authority Brighton,CO <br /> 22470 E.6th Parkway,Suite 100 <br /> Aurora,CO 80018 Commerce City,CO <br /> E47n. 303.537.3700 Phone Douglas County <br /> 303.537.3472 Fax Parker,CO <br /> Public Highway Authority <br /> Thornton,CO <br /> G,�v <br /> October 29, 2019 RNED <br /> Department of Natural Resources NOV 0,4 2019 <br /> Attn: Jared Ebert <br /> Colorado Division of Reclamation, Mining& Safety UNISiOMOF RECLAMATION <br /> 1313 Sherman Street Room 215 41WING&SAFETY <br /> Denver, CO 80203-2243 <br /> Re: Sandy Acres Pit, DRMS Permit No. M-1980-110 <br /> Hydrologic Balance response <br /> Dear Mr. Ebert: <br /> This is in response to the Hydrologic Balance topic in the Minerals Program Inspection Report <br /> from July 17, 2019. <br /> In the spring of 2016 the pond was backfilled to a depth of 4 feet above the pond water elevation <br /> at a cost of just under$3 million. All parties involved at that point in time concurred that <br /> backfilling to that elevation should eliminate issues with ground water causing a pond. Initially <br /> after the backfill was completed the pond bottom was dry but as time has progressed more of the <br /> area is being covered by water. At two points in time,July 1,2016 and September 19,2019,test <br /> pits were dug in the bottom of the backfilled pond area in an effort to determine if the water was <br /> ground water or ponding storm water. Both times pits were excavated to a depth of 4-5 feet <br /> below the water surface elevation and no water was encountered even though the pits were less <br /> than 100 feet laterally from the surface water. That would lead one to believe that the ponding <br /> water is storm water but we have observed that the area covered by water has continued to <br /> increase even during periods with little to no precipitation. It also appears that the area being <br /> covered by water is expanding from the south to the north. Because of these observations we <br /> have also met with the water district that has a 36 inch waterline traversing around the southern <br /> end of the pond. A site investigation did not uncover any telltale signs that the line is leaking. <br /> Pond area <br /> filled in <br /> es <br />