Laserfiche WebLink
WATER INFORMATION EXHIBIT G <br />1. Surface Water General Discussion <br />The pre - mine site consists of mainly irrigated fields in the mine pit area. The overburden storage <br />area has been completely disturbed by past gravel mine activity, primarily as a stockpile area. <br />The slopes are gentle and the general slope of the land is approximately 1% to the south. <br />Irrigation water enters the property along the northern edge and flows by flood irrigation to the <br />south, where the water enters a series of 10" diameter CMP's which deliver the water to the 33 <br />Road Drain. The overburden storage area was mined in the past and has been filled with <br />overburden to the approximate original ground level. <br />The Oberding Drain is an irrigation return ditch that enters the property near the southwest edge. <br />It runs for approximately 1080 feet then turns south for approximately 330 feet. This drain then <br />enters the 33 Road Drain, which is a major drain return for the area. This main ditch flows to the <br />southwest immediately south of the pit area and will not be affected by the mining operation. A <br />short distance downstream from the southwest corner of the pit, this Drain enters the Colorado <br />River. There are no users of either the Oberding Drain or the 33 Road Drain that are downstream <br />of the mining operation. Both of these drains are owned and operated by the Grand Valley <br />Drainage District. <br />The Otter Creek Pit is a wet pit that will be dewatered to mine the gravel. It is seen from Map C- <br />1 that a large portion of the permit area is within the 100 year floodplain of the Colorado River. <br />If a 100 year flood occurs in the River, the water level at this site will be 4431' at the western <br />end of the permit area and 4435' at the upstream east end. This level has been mapped on Map <br />C -1 and should be more accurate than any regional floodplain map. If a large flood occurs, <br />United will monitor the level and will remove all mobile equipment and portable plants that may <br />be in the pit before there is a chance that the water could enter the pit. Once the flood subsides <br />and the water can be pumped cleanly, dewatering of the pit would resume. Any storage provided <br />by the pit would actually serve to lower the peak flow downstream and possibly prevent damage <br />to properties. <br />Otter Creek Pit December 12 G - <br />