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CHAPTER IV <br />DAM SITE RECONNAISSANCE REPORTS <br />Reconnaissance reports were prepared for 19 dam sites and 3 <br />entities who did not have a specific dam site. The sites and type <br />of analysis was generally the same as envisioned in Task 1 but some <br />of the sites changed in scope or new information showed the site <br />was at a different stage of development than originally thought. <br />The reports are attached in alphabetical order by dam site. Each <br />report is self supporting; it does not need this summary or other <br />information to be reviewed. <br />The reports are based on the best available data, which in some <br />cases is significant and others minimal. <br />The general assumptions used in the reports are described in the <br />following sections of this chapter. <br />Design Assumptions <br />The designs included in the Study primarily involve a new dam or <br />enlargement of an existing dam. Most of the sites included in the <br />Study are earth embankments; however, there is at least one site <br />which is probably best suited to roller compacted concrete (RCC) <br />because of spillway requirements. <br />The basic earth dam embankment design assumption is that when in <br />doubt of stability, flatten the embankment slopes. Flattening the <br />slopes increases the amount of material to be placed but reduces <br />the design costs and makes the construction simpler. Also, the <br />embankments are usually assumed to be homogeneous, not zoned. This <br />assumption is based on the availability of impervious material at <br />most locations. <br />Most of the entities prefer to use local contractors who are <br />familiar with compacted earth embankments but are not familiar with <br />internal drainage systems (e.g. chimney drains) and may have <br />problems with zoned embankments. Even though the amount of <br />embankment material is increased, the total construction cost is <br />probably less because of simpler designs and construction <br />procedures. <br />The "Rules and Regulations for Dam Safety and Dam Construction" <br />(Regulations) prepared by the State of Colorado, Office of the <br />State Engineer, Division of Water Resources were used for the <br />preliminary designs. <br />Small Dam Site Recon. Study 9 <br />