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November 2013 <br />MM # 1351 <br />SANITARY SEWER FEASIBILITY STUDY & REPORT <br />NORTH SEBASTIAN AREA <br />GRAVITY SEWER SYSTEM ALTERNATIVE <br />The design professional must consider the topography and natural conditions of the study area in <br />order to design the most cost-effective sewer collection system utilizing gravity flow. The objective <br />is to follow natural slopes and maintain minimum depths of the sewer system to service existing <br />and proposed users by gravity flow. In general, the design sewer depths should be between 3 -feet <br />below grade as a minimum to 12 -feet below grade as a maximum. In addition to topography, soil <br />conditions and water table elevations are also factors to consider due to their impact on project <br />construction cost. A high water table condition may increase future operation and maintenance <br />costs due to infiltration of groundwater into the manholes and sewer pipelines as the system ages. <br />Masteller & Moler, Inc. obtained spot elevations at specific locations throughout Study Areas #1 <br />and #2 to establish the topographical conditions for design purposes. Also, a total of nine (9) soil <br />borings were taken at selected locations in order to determine the general soil conditions as well <br />the groundwater elevations. Masteller & Moler, Inc. utilized this topographical information in order <br />to generate design plan and profiles of the most cost effective gravity sewer system to serve Study' <br />Areas #1 and #2. The results of these efforts are shown Exhibits 1A, 1B and 2 which are included <br />within this section of the Report. Soil boring results are included in the Appendix of this report. <br />Study Area #1 <br />Study Area #1 is shown on Exhibits 1A and 1B. The existing sanitary sewer system is shown in <br />green and the proposed gravity sewer system is shown in red Study Area #1 has a north / south <br />sand ridge along the east side of US Highway 1. The result is the commercial users along the east <br />side of US #1 must be served by a separate gravity sewer system served by a small pumping <br />station as shown on Exhibits 1A and 1B. Since this proposed gravity sewer system must be <br />constructed in the eastern right-of-way of US #1, a meeting was held with representatives of <br />F.D.O.T. in Ft Pierce to discuss the project. During that meeting verbal approval was provided by <br />F.D.O.T. for the proposed gravity sewer system. The proposed gravity sewer system along the <br />east side of US #1 has sewer depths ranging from 4 -feet deep at the north and south ends to a <br />maximum of approximately 10 -feet deep at the proposed pumping station location shown on <br />Exhibit 1A. The construction of the system will provide sewer service to all existing and proposed <br />commercial users along the east side of US #1 north of the Sebastian Cemetery. <br />The majority of new gravity sewer in Study Area #1 is located in the area west of North Central <br />Avenue. As shown on Exhibits 1A and 1B, North Central Avenue extends in a north / south <br />direction from Roseland Road to the intersection of North Central Avenue and US #1. All of Study <br />6 <br />