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Mr. Jared Dains May 17, 2011 <br />Middle Poudre Combined Plan - Lafarge West, Inc. Page 2 of 9 <br />Shields Mine M-06-064 04/13/2010 0.7 acres <br />all post 1981 <br />"The pre 81 area currently exposed at the site is 20.5 acres, because 4.5 acres are currently being dewatered, <br />however when the dewatering ceasing the 4.5 acres will fill thus creating a total of 25 acres exposed prior to 1981 <br />"The exposed area based on the March 17, 2011 survey (attached to this letter) <br />The exposed surface area at all the sites has been updated based on the current conditions for <br />each site using a 2009 aerial photo. The 31.4 acres exposed at the Three Bells Pit Site is an expansion <br />of the 11.7 acres identified in the previous SWSP. The exposed surface area at the Kyger Pit site is 10 <br />acres based on the current conditions. For the Shields Mine Site the surface area exposed in the <br />dewatering trenches (outline provided by Lafarge and assuming the trench is 10 feet wide) is 0.7 acres. <br />Mining at the East Rigden Pit has been completed and construction of a clay reservoir liner is in <br />process on the property. According to the updated information provided on your May 10, 2011 letter, the <br />total exposed surface area at this site is 38.9 acres. Of the 38.9 acres exposed at the East Rigden site, <br />25 acres of water surface was exposed within the reclamation permit boundary prior to January 1, 1981. <br />This results in 13.9 acres of exposed surface area requiring replacement of depletions from evaporation. <br />The consumptive use at the East Rigden site also includes dust control and water consumed from <br />drinking and sanitary purposes within an onsite office, which water returns through a septic system. A <br />storage water right for the East Rigden Pit was filed in Division 1, Water Court case no. 2001CW202, <br />however this case was dismissed by the water court on June 11, 2010. <br />The Three Bells Pit will include evaporation, water retained in the product and dust control. <br />Mining was re-started at the Three Bells Pit in February 2006 in an area of approximately 20 acres. This <br />site has been continuously dewatered at a rate of 1,200 gallons per minute. <br />The only consumptive use at the.Kyger Pit, Port of Entry Pit and Weitzel Pit sites is the <br />evaporation of exposed ground water. The Kyger Pit has continuously dewatered directly back to the <br />Cache la Poudre River since 2000. The estimated dewatering rate at the Kyger Pit site is approximately <br />1,200 gallons per minute. Mining is complete at the, Weizel Pit site. The Port of Entry Pit site is currently <br />undergoing reclamation. Lafarge West, Inc. filed for a plan for augmentation for the Port of Entry Pit site <br />in case no. 2004CW111 and this case is currently pending. Lafarge West, Inc. also filed for a plan for <br />augmentation for the Weitzel Pit site in case no. 2002CW205 and this case is currently pending. <br />Shields Mine will include evaporation and dust control. This site will also be dewatered at a rate <br />of 1,200 gallons per minute. Based on the information from the DRMS file, the Shield Mine will be <br />dewatered into the Fossil Creek Reservoir Inlet Ditch. This ditch lies directly to the west of the Shields <br />Mine. The discharge into the Fossil Creek Reservoir Inlet Ditch is the proposed mitigation to address any <br />drawdown impacts from mining in close proximity of the ditch. The dewatering water is measured and <br />returned to the river from the Fossil Creek Reservoir outlet. The releases shall be measured in a manner <br />acceptable to the water commissioner and the division engineer. - J ?- <br />Computation of evaporation under this combined plan from December through February was <br />reduced during the ice covered period. You have assumed the ice covered period to occur during the <br />months of December through February, based on the average temperatures of 29°F for December, 27°F <br />for January and 31 °F for February; taken from the Fort Collins weather stations (053005) for the time <br />period from 1900 through 2005. However, for the purpose of this SWSP, the Applicant shall replace the <br />net evaporation depletions from the exposed ground water surface area that may occur during the <br />assumed ice covered period (December through February) for any time that the pit is not completely <br />covered by ice.