Laserfiche WebLink
2010 AHR McClane & Munger Canyon Mines Page 6 <br />McClane Creek Temporary Diversion <br />The Operator placed four wooden gabions in the McClane Creek channel during <br />1997 to ensure the channel would remain stable. The gabions were to provide a <br />solid place in the channel bottom to limit any further erosion. In 2004 a re-survey <br />was conducted and the data and inspection observations show there has been <br />significant erosion subsequent to the 1997 gabion installation. Future high flow <br />events may result in additional channel scour and side-cutting erosion. Portions <br />of the diverted channel appeared to be unstable and further erosion may be <br />likely. To alleviate this problem, the operator installed a 48" culvert ("P") under <br />the haul road during 2006 in order to reconnect upper McClane Creek to it's <br />original lower segment. <br />Probable Hydrologic Consequences <br />As demonstrated above, the mines had and will have a negligible effect upon the <br />hydrologic regime of East Salt Creek. The area disturbed is small, sedimentation <br />and surface water systems have functioned well for over ten years. The inherent <br />poor quality of surface water in the area is the result of site specific <br />environmental factors not from any impact caused by the mines. <br />Most storm events that have exceeded the design criteria required by the DRMS <br />have not been a problem for the system to handle. The effect that the mine has <br />on the groundwater hydrology of East Salt Creek has not been detected. <br />The mines will not have a detrimental impact upon the groundwater of the East <br />Salt Creek Valley. This is based partially on the relative sizes of the operation <br />and the size of the aquifer. It is also based on the fact that the groundwater <br />contained in the alluvium is substandard. East Salt Creek is an accurate name. <br />The water contained in the alluvium is virtually unusable. Field water sampling <br />has shown that the conductivity of the groundwater is extremely high (3,000 to <br />100,000). <br />Data gathered for SW-1 and GW-3 are presented in the Tables N-1 through N-7 <br />in Appendix N. The Division's 1987 Material Damage guidelines require any <br />measured salinity values over 1,000 umhos/cm be reported as 'suspect' values. <br />Since baseline values for SW-1 and GW-3 far exceed the Division's 'suspect' <br />levels, the Operator compiled data in order to demonstrate mine discharge does <br />not add salinity to the already high values, rather, lowers the salinity in SW-1 and <br />GW-3 during the irrigation season. By improving the salinity of the waters in <br />East Salt Creek and the East Salt Creek alluvium, downstream farmers will not <br />suffer loss of production due to the addition of mine discharge.