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~, ~ III IIIIIIIIIIIIIIII <br />' WeSte~n •400 South Lorena Avenue Received <br />Technologies Farmington, New Mexico 87401 <br />InC. (SOSI 327-4966 • fax 327-5293 <br />The Quality People MAR 3 1 2000 <br />Sim 1955 <br />_ Durango Feb pn~e <br />March 17, 2000 s~~~~'rlF~ ~~='~~~~ O~OpofMineralcgGaology <br />°~aLIC FILE C®P1~ ~Y~ <br />Colorado Gravel Products ~~~~~ /I ,r c~ r~ ~°~`~~ <br />45247 Hwy 112 '/'~V'~~'/~ ~~_ / AP ~~ <br />Center, Colorado 81125 ~~~lE:l, ~O ~irtEV~~ ~~jv~- ~ ~~1(7 <br />Attn: Mr. Ken Smith Perry,r 4PP~T~1`m~ ~ e~t'-cry ~"~ral~ QO <br />~ Ge°~o:.Y <br />Re: Gravel Pit Job No. 3120Vars <br />North of Highway 1 12 <br />Center, Colorado <br />As you requested on February 28, on March 7 and 15, 2000, we have completed our <br />observations at the above referenced project. The purpose of our observations were to <br />sample and visually determine gravel-sand properties of the material and determine the slope <br />stability of the proposed finished gravel. pit slope along the powerline. <br />The proposed gravel pit will be located north across Highway 112 which is north of the <br />existing concrete batch plant and borrow pit. <br />1t is understood that the edge of the proposed borrow pit will be 40 feet from the powerline, <br />with a slope of 3 to 1 (horizontal to vertical) extending down into the pit to a depth of about <br />25 feet. <br />The gravel-sand mixture in the existing gravel pit consists of fine to coarse grained sand with <br />gravel up to about 3 inches in diameter. It is understood that the depth of water in the pit <br />varies depending on how much recharge water is being placed into the ground and if the <br />canals are flowing. It is understood that the surrounding area water well data indicates that <br />the gravel-sand material extends down.to a depth of about 30 to 40 feet. At a depth of 30 <br />to 40 feet a layer of clayey silt/clayey sand exists which is about 1-foot thick and is underlain <br />by gravel-clayey sand material. <br />Past experience and observation of the gravel-sand material indicates that this material <br />probably has an angle of internal friction of at least 30 degrees. The clayey silt/clayey sand <br />probably has an angle of internal friction of at least 20 degrees. <br />The static stability of the existing slope was analyzed using strength parameters estimated <br />from observations and past experience with similar materials. The analysis was conducted <br />on the proposed slope configuration. A computer program ISB Slope) developed by Von <br />Guten Engineering Software using simplified Bishop's Analysis was performed for the <br />proposed slope configuration. The results of the analysis indicates that a slope stability of 2.0 <br />was obtained. <br />