2011-04-29_HYDROLOGY - M1986015 - Laserfiche WebLink

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Mr. Dick Wolfe January 12, 2011 Page 2 the State will issue an approval letter. Therefore, the water removed with the mined product at the East Pit (within Phase 2) does not need to be replaced. Transit Mix will use City of Pueblo water for all hatching and truck washing requirements at the site. However, Transit Mix will continue to take dust control water from the pit through the same pump and pipeline as the product wash water. Dust control water is split off prior to the existing 12 inch meter through a 3 inch meter and assumed to be 100% consumptive. The dust control estimates given are based upon maximum historical seasonal dust control pumping. A network of drainage ditches and settling ponds is used to de-water the mining area. The total exposed water surface area of this network is 10.3 acres. The associated gross evaporative loss is 43.2 ac-ft per year. Gross evaporative losses are offset by effective precipitation and phreatophyte credits. The effective precipitation credit is 70 percent of the precipitation on all but 1.5 acres of the exposed area at the site. Historical phreatophyte credit is claimed on the other 1.5 acres which historically had 100% canopy cover and 5.5 feet per year of potential consumptive use. The net evaporation replacement requirement after accounting for these credits is 28.2 ac-ft per year, as shown in Table 1. REPLACEMENT SOURCES Transit Mix has three sources of replacement water available for the operation of this plan. The first is the excess credits from the Hamp-Bell Ditch water rights which were changed in Case No. 03CW8 and subject to an April, 2004 agreement between Transit Mix and PBWW. Depending upon PBWW's ability to store the Hamp-Bell Ditch water, Transit Mix's use of the credits is subject to different conditions. Currently, PBWW does not have the right to store the Hamp-Bell Ditch water, and it is unknown when they may obtain the right. Therefore, we have presented two scenarios showing the replacement sources under the conditions in which PBWW cannot store the credits, Scenario A, and under the conditions in which PBWW can store the credits, Scenario B. The second source of replacement water is fully consumable water leased from PBWW. Transit Mix has a lease with PBWW that will provide up to 106 ac-ft of totally consumable water delivered annually through September 30, 2012. The lease was provided with a previous SWSP request. The water released in accordance with the lease will be from Pueblo Reservoir or another equivalent source such as Clear Creek Reservoir. Transit Mix plans to extend the lease with PBWW through January, 2013. We will forward a copy of the lease once it has been signed. The third replacement source is 33.63 ac-ft from Transit Mix's ownership of 60 shares of Twin Lakes Reservoir water. As of November 1, 2010, Transit Mix had approximately 61.63 ac-ft of Twin Lakes Reservoir water stored in its account. Approximately 28 ac-ft of this is committed to their Grisenti Pit each year, leaving 33.63 ac-ft available for their Pueblo pits. OPERATION OF PLAN SCENARIO A Scenario A represents the current operations which are subject to the conditions in which PBWW cannot store the Hamp-Bell Ditch credits. Under this scenario, summertime Hamp-Bell Ditch credits in excess of the Chain of Lakes augmentation requirement are available to replace East Pit depletions. Additionally, Transit Mix is responsible for replacing the Hamp-Bell Ditch delayed return flows to the stream. The replacements under Scenario A are shown in Table 2A. The combination of projected Hamp-Bell Ditch credits and return flow obligations is shown in Column [4] of Table 2A. Column [6] shows that the