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I I I I I I I I I I I I I I I I I I II nature of the proposed alignment indicate the need for a moderate to intensive permitting work effort to secure approval for the project. 1.4 Conclusions and Recommendations Cost estimates have been developed for each of the alternatives presented in this report. These estimates include capital, operating and borrowing costs. Life cycle type analyses were performed to compare the alternatives using a common time basis. The present value costs developed for these alternatives vary from approximately $2.5 million to $3.2 million for the different tunnel/pipe combinations. The present value cost for the bypass pipelines is estimated to be $2.9 million. The construction schedules for tunnel and pipeline alternatives are expected to be similar. Each option will require 8 to 12 months to complete. A comparative evaluation of tunnel versus bypass pipeline alternatives was conducted comparing design, construction permitting, and right-of-way considerations as well as construction costs and construction duration. Based on this comparative evaluation, the tunnel alternative has been selected as the preferred alternative to increase delivery capacity along this portion of the water delivery system. Based on the preliminary analysis, a 42 inch diameter water transmission pipe through the tunnel will be adequate to meet the future District's water demands. However, the capacity of the tunnel alternatives is mainly regulated by the hydraulic characteristics of the entire pipeline system. In order to select the most feasible pipe size and to meet the proposed future water demands, a hydraulic study of the entire transmission system should be conducted. During this study the optimum tunnel alignment, pipeline diameter and configuration can then be determined based on the hydraulic characteristics of pipeline upstream and downstream from the tunnel section . 2.0 INTRODUCTION 2.1 Purpose The recent changes in the District water usage and steady population growth in the district service area have placed a high demand for delivery of a large and sustainable volume of high quality water to the District water treatment facility. Already, the water demand has exceeded the water transmission capacity for several days during the summer of 1990. Based on population growth projections for the District's service area, this condition will become more severe and prolonged 3