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~ • iii iiiiiiiiuiiiiii <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Drparlmenl n( Natural Resources <br />1313 Sherman 51., Room ? I S I~~IM~ <br />Dem•er, Culomdo 80203 I <br />Phone'. 130}) 866 3567 <br />FAX: X303) 8}2 8106 <br />DEPARTMENT OF <br />NATURAL <br />RESOURCES <br />Rov Rumer <br />DATE: September 7, 1994 c~~~^nor <br />Ken Salazar <br />TO: Berhan Keffelew Execw rve Due~u,~ <br />~j r~~~h,,eiP «~K <br />~"(/ Division Duec mr <br />FROM: Allen Sorenson <br />RE: Installation of Leak Collection Riser Pipes on Top of Liner, <br />Cresson Project, Cripple Creek and Victor Gold Co., Permit <br />No. M-80-244 <br />I am recommending approval of the above referenced specification change <br />because the revised installation details are a more constructable <br />design, and incorporate the advantage of eliminating the need to "boot" <br />the riser pipes through the geosynthetic component of the composite <br />liner. Such boots are a potential leakage pathway, and in fact are <br />suspected to be the cause of the initial leak at Summitville. The <br />function and utility of the leak collection riser pipes is the same in <br />either design. <br />I would recommend that all Cresson inspectors be given a copies of the <br />drawings submitted with the new design (I have already made copies for <br />myself). Specific aspects that will need to be inspected are the area <br />where the riser pipes will be "booted" through the primary geosynthetic <br />(shown on drawing B), and the installation and extrusion welding of the <br />VLDPE cover over the riser pipe bedding above the pregnant solution <br />storage area. The riser pipe bedding will have to be compacted without <br />damaging the underlying geosynthetic, and the VLDPE cover will have to <br />be tight (no wrinkles) over the pipe bedding. This is going to be <br />difficult for the contractors because the pipes are not being laid in <br />a trench. <br />Leak collection riser pipe installation at the 9360' level should become <br />and inspection milestone, and the operator should be instructed that the <br />various phases of this area of the pipe installation should not be <br />covered until inspected and accepted by the Division. <br />C:\WP51\CRESSON.15 <br /> <br />