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Bernhardt Pit SWSP Page 2 of 5 March 9, 2015 Furthermore, both the concrete batching well and the concrete batching plant appear to be located outside the boundaries of the current DRMS permit. The inclusion of the concrete batching well in a SWSP approved pursuant to 5 37 -90- 137(11), C.R.S. may be accepted only if the Applicant will amend the DRMS permit boundary to include the site of the concrete batching well and concrete batching plant. If the Applicant seeks to use well no. 60729 -F for concrete batching without amending the DRMS permit boundary the Applicant will need to obtain a SWSP for the well pursuant to S 37 -92 -308, C.R.S. or include the well in a court approved augmentation plan. Depletions Currently 6.52 acres of ground water surface is exposed at the Bernhardt Pit within the three settling ponds and dewatering trenches (See Figure 1). Consumptive use of ground water from the Barnhardt Pit consists of 2.96 acre -feet for on -site dust control, 18.78 acre -feet of evaporation from the 6.52 acres of exposed ground water, and 1.47 acre -feet of water lost with the mined product. Evaporative depletions were calculated using a gross annual evaporation of 43.86 inches, with a credit of 9.29 inches for effective precipitation (based on an average annual precipitation of 13.27 inches for the Longmont weather station). During the SWSP period the Applicant projects up to 50,000 tons of aggregate production resulting in 1.47 acre -feet of water lost with the mined product. The total consumptive use at this site during this plan period is 23.21 acre -feet (See Table 1). Depletions from mining operations at the Bernhardt site will impact the Big Thompson River upstream of the Evanstown Ditch (WDID 0400517). Dewatering at the site commenced in October 2003 at a rate of 750 gallons per minute. In 2004 dewatering decreased to 350 gallons per minute. All water pumped in 2003 and 2004 for dewatering purposes was pumped from trenches into an on -site pond for recharge back to the Big Thompson River. In September 2004, pumping of the dewatering water into the pond ceased. All water pumped from the trenches since September 2004 has been pumped from within the slurry wall and used for the purposes described in this plan. Based on the analysis previously performed by the Applicant there are no depletions from past dewatering operations that will accrue to the river during this plan period. The depletions from evaporation and operational losses were lagged to the stream using a Glover analysis assuming a distance (X) from the centroid of the exposed ground water surface to the stream of 715 feet, a distance (W) to the impermeable boundary of 2,976 feet, a transmissivity (T) of 100,000 gal /day /ft, and a specific yield (S) of 0.2. The total lagged depletions that are to be replaced in 2015 are 22.9 acre -feet (See Tables 2b and 3). Replacements The proposed source of replacement for the Bernhardt pit is a lease of 22.1 acre -feet of excess augmentation credits available to Central Colorado Water Conservancy District ( "Central ") (WDID 0203334). Please note that the lease amount is for less than the calculated depletions due to free river conditions in January 2015, during which no replacements were required to be made. The excess credits accrue to the Big Thompson River in the same location that the tagged depletions from the Bernhardt Pit impact the river, therefore, no river conveyance losses will be assessed. A copy of the Lease Agreement with Central was submitted to this office on February 18, 2015, and is attached to this letter. A monthly breakdown of depletions and replacements is shown in the attached Table No. 4. Long -Term Augmentation In accordance with the letter dated April 30, 2010 (copy attached) from the Colorado Division of Reclamation, Mining, and Safety ( "DRMS "), all sand and gravel mining operators must comply with the requirements of the Colorado Reclamation Act and the Mineral Rules and Regulations for the