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<br />TR9PP8R DINING INC. 999 <br />FF p ~ 0 ~9~6 <br />~~~j r'~~}":'«~i~~y~Wi <br />.~ ' <br />,~'1i0 ~: <br />I, James M. Mattern, a Registered Professional Engineer in the State of <br />Colorado, in accordance with 2CCR407-2, Section 4.05.6(7), do certify that <br />Johnson Gulch dams 7A, 9, and 10 were constructed under my direct supervision. <br />Dams 7A and 9 were constructed in early 1985 (February-April) and enlarged <br />during pond cleaning operations in July. Dam 10 was constructed during the <br />summer of 1985 (August-September). Dams 7A and 9 were surveyed for capacity <br />determination in January, 1986. Dam 10 was surveyed in September, 1985. <br />Stage storage relationships, spillway elevations and hydrographs for a <br />10-year, 24-hour event and a 25-year, 24-hour event are shown in the attached <br />SEDIMOT II output. <br />During construction the dams were visually inspected daily to insure compli- <br />ance with prudent state-of-the-art construction meth ode. Compaction was <br />accomplished by laying fill in thin horizontal layers and compacting with a <br />vibratory roller compactor and dozers and/or scrapers. Standard Proctor den- <br />sities were determined in our lab using methods outlined in AASHO T99-61. <br />Percent compaction was monitored using a nuclear density probe until densities <br />were sufficiently high to insure stability. <br /> <br />~.. MgTJ~, a s M. Mattern, <br />N: 0 20537 W~ a e <br />a•s r:p <br />q>'%sS~ ..o;.' O <br />6 oNA~ ~P <br />JMM/jb <br />1/23/86 <br />P.O. Box 187 <br />Craig, Colorado 81626 <br />(303) 824-4401 <br /> <br /> <br />