01-22-2018 Council Meeting Packet

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The pressure system alternative also provides greater flexibility for connecting to existing properties. Unlike a gravity system, the pressure pipe services are not required to be placed at a down gradient from the home; a minimum pipe grade is not required for grinder pump service installations. The pressure system alternative was also evaluated for an open cut versus directional drilling installation method. Due to the high groundwater table and the smaller forcemain pipe diameter, the directional drilling operation is a more cost effective and less impactful method of installation. This would also minimize impacts to trees, driveways and other landscaping in the corridor. The proposed sanitary sewer system improvements for the West Shadow Lake Drive project area include both a gravity sewer collection system and a low-pressure force main system. The project area located north of the culvert crossing would be served by 4,500 lineal feet of 3-inch High Density Polyethylene (HDPE) sanitary sewer force main and extend through West Shadow Lake Drive, Sandpiper Drive, and Shadow Court. A connection would be made at the existing forcemain located at West Shadow Court/Sandpiper Drive intersection. The 8-inch gravity sewer collection system is proposed to be installed on West Shadow Lake Drive from Birch Street north to County Lakes Park, approximately 1,000 feet; The relatively shallow depth of this system does not preclude the use of a gravity line. Sanitary sewer service laterals would be extended to the right-of-way / property line from both the new and existing force main to each existing property, buildable lot, or sub-dividable lot. Feasibility Report Section 5.1 – Opinion of Cost A detailed opinion of probable cost is included with this report. The opinion of probable cost is based on projected construction costs for 2018, and includes a 10% construction contingency and 20% indirect costs. The funding for the watermain and sanitary sewer installations for West Shadow Lake Drive, Shadow Court, and Sandpiper Drive would be provided through a combination of City trunk utility funds, and special assessments The project costs and funding are summarized as follows: West Shadow Lake Drive Watermain and Sanitary Sewer Summary of Costs Assessed Trunk Total Schedule E – Sanitary Sewer Improvements $337,101.60 $126,456.00 $463,557.60 Schedule F – Watermain Improvements $706,292.40 $407,418.00 $1,113,710.40 TOTAL $1,043,394.00 $533,874.00 $1,577,268.00 Feasibility Report Section 5.2 – Assessment Analysis