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S ~' <br />~ ~~ COLORADO P.O. Box 1301 <br />- ~~~ RIVER Rifle, co alsso <br />Tel 970-625-4933 <br />ENGINEERING, INC. Fax 970-625-4564 <br />April 19, 2000 <br />Mr. Allen Sorenson <br />__ Colorado Department of Minerals & Geology <br />- 1313 Sherman St. Rm 21~ <br />._ Denver, CO. 80203 <br />RE: American Soda LLP, Yankee Gulch Minerals Project <br />Storm Runoff Pond -Construction Inspection (Permit # M-99-002) <br />Dear Mr. Sorenson <br />- On behalf of Kvaemer Metals, Colorado River Engineering [nc. has completed quality assurance <br />inspection services during the construction of the storm runoff retention pond at the American Soda LLP <br />Yankee Gulch Minerals Project, upper site. The retention pond has been constructed with an impermeable <br />High Density Polyethylene (HOPE) plastic liner and is designed to retain storm runoff collected from the <br />_ • upper plant site, We have prepared this letter report to summarize construction observations, testing results, <br />and as-built documentation. This letter shall serve as certification that the pond has been constructed in <br />accordance with the attached design drawings, specifications, and liner installation guidelines. <br />Attached in Appendix-A are the following design drawings and technical specifications for the <br />project. <br />I. Kvaemer Metals Drawing No. Ol-V-008, "Upper Plant Site Storm Retention Pond" <br />2. Kvaemer Metals Drawing No. Ol-V-009, "Upper Plant Site Storm Retention Pond, Sections <br />:. & Details". <br />3. Kvaemer Metals Specifications GC-O1, "Site Work' <br />4. Kvaemer Metals Specifications GC-18, "Geosvnthetic Lining", Revisions,: A-8/19/98, 0- <br />6/3/99 <br />Also included in Appendix-A are the quality assurance manuals provided by the lining manufacturer <br />(Agra America) and lining installation contractor (Colorado Lining International). <br />Construction Summary <br />'~' Construction on the stormwater retention pond began the fast week of February 3000. The site was <br />first grubbed with organics and topsoil stockpiled. The top 1'f of soils was stripped and stockpiled for future <br />use as bedding material. The retention pond embankment was constructed by ruing excavated material from <br />- the eastern bank and pond floor for fill on the downgradient western bank and on the northern and southern <br />embankments. Additional boaow material was used from the parking area north of the pond. The <br />T embankment material consisted of sandstone rock, fine sands, and fines (silts & clays). The embankment was <br />i constructed in 8-inch vertical lifts and compacted using a sheepsfoot vibratory compactor. Moisture content <br />was maintained by application from a water truck. <br />_. <br /> <br />