2019-08-27_HYDROLOGY - M1989120 - Laserfiche WebLink

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Amended Aggregate Industries South Platte Combined SWSP August 27, 2019 Plan I Ds 3614, 47731 3624, 47721 4616, 3437, 3376, 3650, 3668, and 5475 Page 10 of 21 annual delivery amount of 146 acre-feet. A copy of the proposed 2019 delivery schedule, dated November 8, 2018, is attached. For this SWSP, transit losses were assessed assuming deliveries will be from the Big Dry Creek Wastewater Treatment Plant. Notice must be provided and approval made by the water commissioner at least 48 hours prior to the release of replacement water, or as required by the water commissioner, and must identify which source the replacement water will originate from (the Metro Wastewater Treatment Plant or the Big Dry Creek Wastewater Treatment Plant) to allow confirmation of release and that water was delivered. Thornton Lease Aggregate has a perpetual lease of 10.53 acre-feet of fully consumable effluent from the City of Thornton, which will be released from the Metro Wastewater Treatment Plant at a rate of 0.035 cfs daily from November 1st through March 31 st. Fulton Ditch Aggregate owns a total of 96 shares in the Fulton Ditch Company, consisting of 62 shares obtained from Cooley Gravel, 22 shares from CAMAS, 6 shares from CEtM Aggregates, and 6 shares from Hill Et Peterson. For 2019, Aggregate intends to utilize their 62 Cooley Gravel shares for replacement under this SWSP. (The 22 CAMAS shares, 6 CEtM Aggregates shares, and 6 Hill Et Peterson shares will be leased to others for irrigation purposes). Prior to 1977, the 62 Cooley Gravel shares were used in two blocks: 30 of the shares were owned by the Montandon Trust and used for the irrigation of 48.7 acres, and 32 shares were owned by the Palombos and used for the irrigation of 31.1 acres. The shares were purchased by Walt Flanagan Et Company in 1977 and little is known about the use of the shares after that time. The historic consumptive use analysis utilized a parcel-specific analysis for the period of 1919 to 1977. A total of 40 shares were used on the Montandon parcel prior to 1964, with 10 shares being sold off in 1964. The historic consumptive use analysis assumed that the subject 30 shares irrigated 75% of the Montandon parcel (36.5 acres) prior to 1964 and 100% of the parcel (48.7 acres) from 1964 to 1977. The crop mix for the Montandon and Palombo parcels was assumed to reflect the mix of crops for the Fulton Ditch as a whole as identified in the 1956 CDSS irrigated lands GIS layer, consisting of 44% alfalfa, 26% corn, 15% dry beans, 13% pasture grass, 1% small grains, and 1% sugar beets. A ditch loss of 20% and irrigation efficiency of 65% were utilized for the analysis. Based on the above, the historic consumptive use of the 62 Cooley Gravel shares is estimated as 1.87 acre-feet per share. Return flow obligations were allocated as 50% surface return flows and 50% subsurface return flows. The 62 shares to be used for replacement purposes under this SWSP will be delivered through the augmentation station owned by the South Adams County Water Et Sanitation District located just downstream of the ditch headgate. The expected consumptive use credit for the 62 Fulton Ditch shares for 2019 has been estimated from a dry-year farm headgate delivery of 2.64 acre-feet per share or approximately 164 acre-feet for all 62 shares. Actual deliveries, which were lower than projected deliveries, were used for the months of April and May 2019, resulting in a revised projected consumptive use credit of 133.40. After accounting for return flow obligations, the total consumptive use credit for the 62 shares is projected to equal 86.70 acre-feet in 2019. In the event the Fulton Ditch goes into Sections, the Applicant has sufficient alternative replacement supplies in the form of shares in the Brighton Ditch, as described below, to make up any temporary shortfalls. Brighton Ditch Pursuant to a March 4, 2010 Water Lease with the City of Westminster, Aggregate has the right to use 1.038 shares in the Brighton Ditch Company owned by the City of Westminster for augmentation purposes. The lease is currently valid through March 4, 2020. The subject 1.038