2014-05-06_HYDROLOGY - M1986079 - Laserfiche WebLink

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OF Olp\ .c /rye �' 1 G 87 i DEPARTMENT OF NATURAL RESOURCES DIVISION OF WATER RESOURCES Mr. Rick Parsons, P.E. Parsons Water Consulting, LLC I 4729 W 32nd Ave Denver, CO 80212 John W. Hickenlooper Governor Mike King Executive Director May 6, 2014 Dick Wolfe, P.E. Director /State Engineer Re: M &G4ubstitute Water Supply Plan (WDID 0202503) M &G Pit, DRMS No. M- 1986 -079 (WDID 0203063) Water Division 1, Water -strict 2, Weld County Approval Period: April 1, 2014 — March 31, 2015 Contact phone number for Mr. Parsons: (303) 667 -5067 Dear Mr. Parsons: We have reviewed your letter dated March 14, 2014 requesting a renewal to the Substitute Water Supply Plan ( "SWSP ") for the above mentioned gravel pit. The current SWSP was approved on March 28, 2013 and expired March 31, 2014. The required $257 fee to renew an SWSP has been submitted (receipt no. 3663998). Plan Operation The M &G Pit (aka Polly Mann Pit) was previously operated by Lafarge West, Inc. On May 12, 2011, the Division of Mining, Reclamation, and Safety ( "DRMS ") approved a succession of operators from Lafarge to Mann Resources LLC ( "Applicant ") for this operation. Mann Resources is now the permitted operator of this Pit and has assumed all reclamation responsibilities for the site. Mining has ceased and the only remaining work to be done is reclamation. The current plan is to backfill the exposed groundwater within the next 3 to 5 years, depending on the availability of suitable backfill material. The exposed water surface has varied significantly since mining commenced on the site. In addition to exposing ground water, urban runoff is diverted from the up- gradient Dunes subdivision through culverts and into the gravel pit site, and ultimately into the South Platte River. Therefore the water level can fluctuate in response to the frequency and magnitude of runoff events. A precise record of the exposed ground water surface area was not kept by the original gravel pit operator. The Applicant's consultant analyzed various records including seven aerial photographs from 2003 through 2012. These records showed a maximum surface area of 62.2 acres in May 2003 and a minimum surface area of 17.8 acres in July 2005. More recently the exposed area was 21.4 acres in August 2011 and 27.57 acres in May 2012. In the previous SWSP, evaporative depletions were estimated based on an assumption of a steady exposure of 27.57 acres as supported by the August 2011 and May 2012 aerial survey, and is consistent with recent trends of the ground water surface area. Backfilling at the site over the last year has reduced the exposed water surface area by approximately 15 percent. Therefore for the purpose of this SWSP evaporative depletions were estimated based on the current exposed area of 23.43 acres. Although the operational plan is to continue backfilling the site, this SWSP covers the expected depletions assuming the exposed acreage does not grow or shrink in size. Office of the State Engineer 1313 Sherman Street, Suite 818 • Denver, CO 80203 • Phone: 303 - 866 -3581 • Fax: 303 - 866 -3589 www. water. state. co.us