Laserfiche WebLink
4-12 <br />to 40 feet below the ground surface and, therefore, far below <br />• the local streambed. The alluvial aquifer is being recharged <br />mainly from surface water, including direct infiltration of <br />precipitation. <br />Hydraulic conductivity of the East Salt Creek aquifer is in <br />the range of 1.04 to 2.89 ft.lday (3.69 x 10-4 to 1.02 x 10-3 <br />cm/sec). Permeability in the alluvium of the tributary chan- <br />nels is lower than that of the main stream because of a higher <br />content of fine grained materials. The hydraulic gradient in <br />the East Salt Creek alluvium is about 89.3 ft./mile at the <br />proposed site. <br />A monitoring well installed to a depth of 46 feet in Munger <br />Canyon (MW-3), close to the confluence with East Salt Creek, <br />did not indicate the presence of groundwater even in the wet <br />season. <br />• The side valley where the coal refuse disposal facility is <br />proposed has well developed alluvial sediments. Alluvial <br />sediments in this valley consist of silty clays with a dis- <br />tinctive layer of silty and sandy gravels. The top of bed- <br />rock consisting of shale and sandstone is at a depth of <br />between 51.5 feet (BH-1- and 36 feet (BH-3). During field <br />investigations at the refuse disposal site (November, 1981), <br />the groundwater presence was found only in the upper reaches <br />of the valley (Boreholes BH-3 and BH-4). Presence of ground- <br />water in Borehole BH-3 is related to a 1.5 feet thick layer <br />of gravel at a depth of 26 feet from the ground surface (see <br />Figures 4.2-25 and 4.2-45). <br />Bedrock <br />Within the Mesa Verde formation, as exposed in the study <br />area, there are no known major aquifers. Sandstone strata <br />sub-cropping underneath the saturated alluvium have a good <br />. potential for recharge and can develop into aquifers. The <br />