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<br />- • • iii iiiiiiiiuiiiiii <br />STATE OF COLORADO <br /> <br />DIVISION OF MINERALS AND GEOLOGY <br />Depa*imeni u( Nalmal Hc~uun cy <br />I S I S Sherman $1.. Kuum ! I S <br />Dt•nvcr. Cnlur,ulu !111!114 <br />Phunc' 1)031 Hob 15hi <br />FA% 110)1 H 4! HAIL <br />MEMO <br />lames 5 Lochhead <br />t rrcunvc Direanr <br />TO: Berhao Keffelew <br />FROM: James Dillie ~~. <br />DATE: January 25, 1996 <br />RE: Review Of Technical Revision -Cresson Project -Permit No. M-80-244 <br />I~~I~ <br />DEPARTMENT OF <br />NATURAL <br />RESOURCES <br />Ruy Rumri <br />Governor <br />Muhael B Lung <br />Drcmm~ Ducciw <br />Per your request, I completed a cursory review of the Procedures and Materials for 1996 <br />Construction. <br />I offer the following observations and comments: <br />1) Drain Cover Fill - No gradation change, so no comment. <br />- Change thickness of layer from 3 feet to 2 feet. This may present a myriad of <br />problems: 1) it reduces the flow area by 1/3 which, if fluid flow is encumbered as <br />a result of the reduction in flow area, could result in a buildup of head on the liner <br />system, 2) increases the probability of a geomembrane puncture or tear (from <br />equipment traffic) and 3) reduces the maximum allowable load from 8 psi to 4 psi <br />(Golder estimates) which will restrict the type of equipment that can be used. <br />2) Select Drain Cover Fill -Specification change not significant. <br />3) Low Volume Solution Collection System Fill - No problem with gradation. <br />- Change thickness of layer from 3 feet to 2 feet (see comment for Drain Cover <br />Fill). <br />4) Soil Liner Material - Slight specification change (more fines, higher P.I.), but <br />should meet or exceed permeability requirements. Only one problem noted--the soil <br />composition reduces resistance to shear (between the geomembrarre and the soil) <br />compared to the ironclad soil liner fill. <br />