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November 2013 MM # 1351 SANITARY SEWER FEASIBILITY STUDY & REPORT NORTH SEBASTIAN AREA CONCLUSIONS & RECOMMENDATIONS This sanitary sewer Feasibility Study and Report for the North Sebastian Area has evaluated three (3) alternative systems which are in use in Indian River County. They are the conventional gravity sewer system, the vacuum collection system, and the low pressure system alternative utilizing grinder pumps or the STEP system. The majority of the collection systems in Indian River County utilize the gravity collection system. A vacuum collection system with over 400 users is located in the Rockridge community of Indian River County and there are several scattered developments and locations including Indian River Drive in Study Area #1 of this report which utilize low pressure grinder pump systems. Conceptual designs for each of the three (3) alternative systems are included in the report and are used as a basis of estimating quantities of the elements needed to construct each of the alternative systems. Estimated construction costs provided by a local, experience utility construction contractor were applied to these various elements and the resulting project costs were estimated for each of the alternatives. The alternatives and their estimated project costs are listed as follows: Gravity Sewer System Alternative: $ 5,000,000 Vacuum Collection System Alternative: $ 6,600,000 Low Pressure Pump System Alternative: Grinder Pump System. $ 8,600,000.00 STEP System. $ 7,100,000.00 The gravity sewer system alternative has the lowest project cost estimate. In addition, the gravity system is the most reliable, does not rely on mechanical components, and is the least expensive to maintain and operate. Finally, the gravity system does not have the disadvantages of the other alternatives which include: Requires much institutional involvement because the pressure and vacuum system has many mechanical components throughout the service area. • • The operation and maintenance (O&M) cost for a pressure and vacuum system is often higher than a conventional gravity system due to the high number of mechanical elements in use. • Annual preventive maintenance calls are usually scheduled for grinder pump components of. pressure sewers. STEP systems also require pump -out of septic tanks at two to three year intervals. • Public education is necessary so the user knows how to deal with emergencies and how to avoid blockages or other maintenance problems associated with low pressure systems. 23 31-35