2014-01-28_HYDROLOGY - M2003091 - Laserfiche WebLink

Home Browse Search

Mr. Heintz & Ms. Wynne Duckworth SWSP January 27, 2014 Page 3 of 7 division engineer that water within LCP is being diverted for use or the accounting is not adequate to show that recharge of dewatering is occurring. MMM has obtained permission from the Smith and Emmons Ditch Company to run dewatering water in the ditch and MMM plans to construct a waste way for the Smith and Emmons Ditch which will run from the ditch due west and directly back into Boulder Creek. This structure and its measurement device must be in place and approved by the water commissioner prior MMM receiving any credit from dewatering unless MMM or the ditch company can show to the satisfaction of the water commissioner that an alternate route was provided to deliver the dewatering water to Boulder Creek. Discharging the dewatering water to Boulder Creek will create an instant dewatering credit and a lagged depletion. The depletions will be lagged using the same AWAS parameters as the evaporation and mining operations depletions. Dewatering is projected to occur at a constant rate of approximately 550 gpm in November and December and 1,000 gpm in January through October, or approximately 75 acre -feet and 135 acre -feet per month, respectively. Table 2 presents a dewatering schedule that assumes that all of the dewatered water is discharged to the silt ponds. Actual dewatering volumes will be metered and lagged depletions /credits will be based off of actual use. The Applicant must tract, and measure to the satisfaction of the water commissioner, the amount of water discharged to the silt ponds, the LCP and the Smith and Emmons Ditch. Replacements This plan provides four replacement sources that can be used during this plan, which are changed Rural Ditch shares, water stored in priority in Heaton Reservoir, excess augmentation credits available from MMM's South Platte Combined SWSP and dewatering credits from mining operations at the Duckworth Pit. Credits for dewatering are only applicable during the month they are generated and unused credits cannot be rolled over into future months. Rural Ditch (WDID 0600551) Shares MMM owns two shares in the Rural Ditch that were historically used on the Heaton property for irrigation. The Heaton property is north of the Duckworth pit and is the current site of Heaton Reservoir (WDID 0504089). These shares were previously apart of Case No. 01CW194 to be changed from irrigation to augmentation and other uses associated with Lafarge's (MMM's predecessor) sand and gravel operations. This case was dismissed without prejudice on April 5, 2011 before going to trial at the request of Lafarge because the credit sought would not adequately meet the needs of Lafarge's operation and new mining properties along the lower St. Vrain or the South Platte River, which could use the consumptive use credit, had not been identified. An engineering report (see November 12, 2010 letter attached) was completed for Case no. 01 CW194 and presents the historical consumptive use analysis for these two shares. This report is the basis for the historical consumptive use analysis for this SWSP. According to the engineering report, the average annual ditch diversions attributable to MMM's two shares is 204.2 acre -feet per year. An assumed 20% ditch loss assessed on the diversions provides an average annual farm headgate delivery of 163.4 acre -feet per year. The historic return flow obligations must be maintained and are equal to 73.3 acre -feet. Return flow obligations can be made by bypassing water through Heaton Reservoir or through the Smith & Emmons Ditch waste way. The shares will be delivered when in priority from April through September and shall not exceed the average monthly values given in attached Table 7. Table 8 of the report provides the depletion and return flow factors attributable to the two shares. For purposes of this SWSP the analysis previously provided will be accepted; however as