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t <br /> <br />' SBHIBIT D <br />MINING PLAN <br />' General Descriation <br />The Winkler Quarry will be mined for rhyolite, a volcanic rock <br />found in flows located on various benches in the Castle Rock <br />area. Rhyolite is a lightweight material especially suited to <br />produce lightweight concrete and cut building stone. In addition <br />it has proven applications in asphalt, road base, septic fields, <br />and drainage. There are few sources of this material readily <br />available in the Front Range area. <br />' There is also an underlying deposit of volcanic clay beneath the <br />rhyolite. This clay has proven valuable for the manufacture of <br />bricks. The operator proposes to mine clay as an accessory use <br />to satisfy occasional contracts with brick making companies in <br />' theHetro Denver area. <br />' The initial annual removal of material from this quarry is <br />estimated to be 100,000 tons. The deposit that will be mined is <br />shoKn in the Colorado Geologic Survey report 'Sand, Gravel and <br />(. Quarry Aggregate Resources, Colorado Front Range Counties' (see <br />Figuire D-1). <br />' Therhyolite deposit to be mined varies in thickness from 10 feet <br />to ?0 feet, overlain by overburden materials. The topsoil ie of <br />0" t.o 6" thickness. The site overburden ranges from 4 feet to 16 <br />' feet. thick, with a typical thickness of about 6 feet. The quarry <br />stone is located along the Nillow Creek drainage. However it is <br />approximately 100 feet above the stream channel, therefore, <br />mining activities will not affect the surface water In the <br />stream. A maximum of 13 acres will be stripped at any one time <br />for mining during the life of the operation. <br />' Crushed Stone Operation <br />Overburden and topsoil will be removed from a ten acre area and <br />' sto~~kpiled away fram mining activities. Approximately 4,000 <br />cubic yards of topsoil material will be zemeved for each 10 acre <br />mining unit. An estimated 100,000 cubic yards of overburden <br />material will also be removed with each ten acres. Stockpiles <br />will. be located and aligned to minimize erosion from both wind <br />andwater. Any stockpiles left undisturbed for Wore than one <br />year will be seeded to establish a protective plant cover. <br />' I <br />~ D-1 <br /> <br />