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.. -~ 1 . , <br />,1 <br />The Denver Water Department submits the following comments <br />regarding Asphalt Paving Co's. operation of the Ralston Quarry, <br />Jefferson County, Colorado. <br />1, the peak particle velocity of one-half inch per second as <br />stipulated must apply for any structure or facility whether <br />that be within or outside the affected land limits of the <br />quarry. This refers specifically to the Long Lake feeder tunnel. <br />A review of the proposed quarry operation should De required <br />before excavation begins for Stages XI, XII, and XIII which <br />will affect the tunnel. <br />2. The west f]ank of the ridge (Ralston Dike) is underlain <br />by shale bedrock. This shale, and clays weathered from the <br />shale, underlie some of the moderate and steep slopes of the <br />ridge. A geologic map for the west side of the ridge should <br />be prepared defining the shale/basalt contact. <br />The shale and clays are susceptaBle to sliding if they are loaded <br />and/or saturated. Precautions should Be taken to insure that <br />no material will be stockpiled on shale or clay wherever it <br />may be exposed in the excavation. It is equally important, <br />if not more so, to keep the shale and clay dry. Grading of <br />the quarry floor should be such that water cannot have access = <br />to any exposed shale or clay. Operational plans for stock- <br />piling, if any is required, and for handling sut-face water should <br />be approved. <br />