Laserfiche WebLink
<br />The applicant also proposes excavation of old placer aggregate <br />piles located upstream of the County Road 625 bridge. <br />Approximately 304 of the area has already been mined from the <br />southern end of the site (about 200 feet above the county road <br />bridge) and is proposed to continue upstream for a total of 1,700 <br />feet. Material is removed first from deposits furthest from the <br />river and then removed laterally toward the river. Aggregate <br />will be excavated to depths of approximately 10 to 25 feet using <br />a dozer, end loader, and/or hydraulic excavator. The material is <br />loaded directly into trucks and hauled to the processing area <br />near the center of the property. As the operation approaches the <br />river, a diversion excavation is then proposed immediately <br />upstream to route flows to the opposite (south) side which has <br />been excavated. The gravel extracted to make these diversions <br />will also be hauled for processing or stockpiled in upland areas. <br />Extraction will then continue in the dewatered channel. Once <br />completed, the diversion will be blocked and the river will be <br />returned to its approximate pre-mining configuration (i.e. width, <br />depth, and alignment but not elevation). This site shall be <br />worked from November to May when runoff is at a minimum. Total <br />reserves available in this area are estimated at 350,000 tons, <br />with an estimated 55,000 tons mined annually until depleted. <br />Procedures proposed to mine these two areas would consist of <br />retaining the separating berm feature, installation of one clear- <br />span crossing (two flatbed railroad cars and 450 cubic yards of <br />angular riprap) and two temporary low water crossings (three 36- <br />inch culverts and 550 cubic yards of gravel fill per crossing), <br />and two diversions of the San Miguel River. The clear-span is <br />proposed as the main crossing above the county road bridge <br />northeast of the shop area to access the old placer aggregate <br />area for the life of operations. The other two crossings are <br />described as temporary from November 1 through April 30, at which <br />time they would be removed to accommodate spring runoff. One <br />crossing would be located at the entrance of the gravel harvest <br />area to access bar accumulations at the confluence and assist in <br />controlling flows into the harvest area. The other crossing and <br />channel diversions are proposed in the upper part of the placer <br />aggregate area as referenced on Figure 3. <br />The applicant requests discretion to construct a low water <br />crossing (temporary from November 1 to April 30) at the location <br />of the clear-span structure if maintenance or other circumstances <br />necessitate an alternative crossing type. Furthermore, the same <br />discretion is requested to install a similar clear-span crossing <br />(less the heavy riprap) for use as a low water crossing in either <br />or both of the two areas previously identified as the gravel <br />harvest area and upper placer aggregate area. Again, if a clear- <br />span structure is opted as a low water structure alternative, it <br />would be temporary from November 1 to April 30. <br />2 <br />