Laserfiche WebLink
the discussion of subirrigation. Unless more information on flows in <br />Little Salt Wash and information on subirrigation is submitted, the <br />Division must conservatively assume that water availability is sufficient <br />for agricultural activities. <br />One of the regional irrigation practices in the area of the proposed mine <br />is to store water in a reservoir during high flow periods for use later <br />in the season. Dorchester must submit an analysis of the feasibility of <br />flood irrigation based on storage of water in a reservoir. Otherwise, <br />the Division must conservatively assume that water availability would be <br />sufficient for agricultural activities in all drainages that meet the <br />geomorphic criteria for an AVF. <br />Other than Big Salt Wash, Coal Gulch has the largest drainage area of all <br />the watersheds within the proposed permit areas. If the analysis of <br />flood irrigation feasibility, using a reservoir to store and release <br />water, shows that this practice is not feasible on Coal Gulch, then the <br />Division will assume that this practice would not be feasible on the <br />remaining watersheds within the proposed permit areas, with the exception <br />of Big Salt Wash. <br />The feasibility of using reservoirs to sustain flood irrigated <br />agriculture on Little Salt Wash will have to be studied separately, since <br />it has a much larger drainage area than Coal Gulch. <br />Response: See Vol. II-A, Sec. 2.06.8 <br />- ~lorthern Lease P.A.R. (C-84-066) <br />Surface lJater: <br />The application does not contain a full year of baseline monitoring for <br />surface water. The surface water sites should continue to be monitored <br />for flow and chemistry through October with results submitted to the <br />Division to satisfy these requirements. <br />Response: See Vol. I-A, Sec. 2.04.7(2) <br />In order to verify the applicant's projections of hydrologic impacts to <br />the surface water system during mining, a more detailed monitoring <br />program than that submitted in the application is required. This program <br />must entail, at a minimum, the following: <br />1. Establishment of a surface water monitoring site upstream of <br />surface disturbance on Big Salt Wash and Garvey Canyon. These <br />sites must be sampled monthly for flow and field parameters and <br />quarterly for full chemical parameters. <br />2. Reestablishment of a flume in Big Salt Wash downstream of all <br />surface disturbance. Existing site SW-4 might be an appropriate <br />location as it is downstream of the refuse disposal site. The <br />Parshall flumes have proven to be inappropriate for the flows of <br />BSW. Amore appropriate flume design such as a 4.0 foot HL should <br />be installed with a continuous recorder. This site must be sampled <br />on the same basis as the above sites. <br />