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III IIIIIIIIIIIII III 999 June 29, 1999 Picket Wire Processing, LLC 4643 S. Ulster St., Suite 1720 Denver, CO 80237 Attention: Mr. AI Perry Subject: Observation of Perimeter Ditches New Elk RDA Westin, Colorado Job No. 28,170 Gentlemen: As the request of Greystone, we observed the perimeter (side collection) ditches on the east and west side of the New Elk RDA. Our observations were performed on June 25, 1999. We understand construction of the riprap ditches was completed prior to our February 1999 visit. We were provided with specifications for the ditches including Perimeter Ditch Cross-Sections (Fig. 9) and Trapezoidal Channel Specifications for RDA Perimeter Ditches (Table II). These figures are attached and were incorporated into Exhibit 20 of the Permit Documents, Refuse Pond Design and Certification. Ditch construction was completed at the time of our observations. Photographs of ditch conditions are presented on Figs. 1 through 5. Based upon our observations, we have the following comments: 1. At many location along the edges of the ditch, the filter blanket was evident. This is illustrated in the photo on Fig. 2. 2. Based upon our visual observation and evaluation of photographs, we believe the riprap material meets the intent of the size recommendations as outlined on Table 11. 3. In general, the riprap channels met the required width and depth dimensions for sections related to the lower half of the RDA as shown on Fig. 9. Two exceptions are discussed below. Although a precise trapezoidal channel is difficult to construct using riprap, we believe the ditches conform to the intent of the minimum dimensions shown on Fig. 9. Although we could not positively confirm a minimum 4-foot thickness of riprap is present, we saw no evidence it was not present. CTL/THOMPSON, INC. CONSULTING ENGINEERS 1971 WEST 12TH AVENUE ~ DENVER, COLORADO 80204 ~ (303) 825-0777