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<br />, <br /> <br />V-2 <br /> <br />assume essentially that no live pathogenic bacteria or viruses can be pre- <br /> <br />sent in the finished water. Limiting chemical concentrations are given in <br /> <br /> <br />Table V-A on the following page. <br /> <br />Source Rei iability. Reliability design criteria cannot be specifically de- <br />fined and is principally a matter of measuring costs of reliability design <br />versus the probability of water system failure and the consequences. There <br />are possibilities of power outages affecting the plant, pipeline freeze-ups, <br />as well as breaks in the pipeline system. In our opinion, reliable design <br />criteria should include: <br />a. The general availability of stand-by wells and pumps. <br />b. The availability of clear water storage which can supply the <br />distribution system by gravity. The clear water storage should <br />range from approximately 30% of the maximum day's demand to 100%. <br />However, initial storage capacity can be minimal in the first phase <br />in order to reduce costs. <br />c. Pipeline design must take into account freezing problems. Cover <br />will vary with the pipelines and must be based upon freezing <br />hazards, but also must take into consideration the cost of rock <br />excavation. Bleeders, pipeline drains at low points, and other <br />anti-freeze techniques must be employed if dependable winter ser- <br />vice is to be provided. Drain provisions will also be necessary <br />if any portions of the the system are to be operated seasonally. <br />d. The recommendations of the National Bureau of Fire Underwriters <br />should be taken into consideration. However, this design cri- <br />terion should be limited for cost reasons to provide for no <br />better than a Class 9 Fire Insurance Rating. <br />e. Construction standards of the Colorado Health Department and <br />of the American Water Works Association would be used for all <br />construction. All pipelines intended for winter use should be <br />metallic to provide for thawing at convenient locations in the <br />event that freeze-ups did occur. All construction should be <br />based upon a minimum expected life of the system of OVer 50 years. <br /> <br />WATER SUPPLY FACILITIES <br />It has been extremely difficult to obtain past records, and because of these <br />inadequate past flow records, there is some question as to the constant avail- <br />ability of an adequate surface water supply in Willow Creek. Nevertheless, <br />