PLAN BUILDOUT WITH PROPOSED IMPROVEMENTS (SCENARIO

3)

This section describes the recommended pipeline improvements to address the hydraulic deficiencies identified in the Specific Plan buildout fire flow scenario. To address high velocities in smaller diameter pipelines during fire flow conditions, existing pipelines within the Specific Plan Area must be replaced with larger diameter pipelines.

Figure 3-6 shows the recommended new water pipelines needed to meet the fire flow requirements for new development in the Specific Plan Area. The recommended projects include:

• Install a new 12-inch diameter intertie to increase connectivity between the Victoria Turnout and El Camino Real;

• Replace approximately 1,500 linear feet (LF) of existing 6-inch diameter pipelines with new 10inch diameter pipelines;

• Replace approximately 8,850 LF of existing 6-inch diameter pipelines with new 12-inch diameter pipelines (5,250 LF located in El Camino Real);

• Replace approximately 500 LF of existing 8-inch diameter pipelines with new 10-inch diameter pipelines; and,

• Replace approximately 1,800 LF of existing 8-inch diameter pipelines with new 12-inch diameter pipelines (250 LF located in El Camino Real).

Figure 3-7 shows the available fire flow for the Buildout of the Specific Plan with the improvements listed above. Hydraulic modeling results indicate that all fire flow requirements are met throughout the Specific Plan Area with the construction of the abovereferenced improvements.

3.5 ESTIMATED PROJECT COSTS

Cost estimates prepared for this Water Master Plan Update are in accordance with the guidelines of the Association for the Advancement of Cost Engineering (AACE) International for a Class 5 Estimate.

Construction costs for the proposed water pipeline improvements are estimated using unit costs from the 2015 Water Master Plan, scaled to the November 2021 Engineering News Record Construction Cost Index for San Francisco of 14421. Unit construction costs for water pipelines

10 and 12 inches in diameter are provided in Table 3-2. These costs generally include pipe materials, trenching, placing and jointing pipe, valves, fittings, hydrants, service connections, placing imported pipe bedding, native backfill material, and asphalt pavement replacement, if required. For pipeline construction in El Camino Real, a 25 percent complexity allowance has been added to the unit cost based on construction costs from other public agencies in streets with similar conditions. Additionally, a 30 percent construction cost contingency, and a 30 percent implementation multiplier are added to estimate a total project cost.

Construction costs for interconnections in the domestic water system are assumed to consist of a nominal amount of standard 12-inch diameter piping and associated fittings. The unit cost for an interconnection is assumed to be approximately $100,000.

As presented in Table 3-3, the project has an estimated construction cost of $5.87 million (including construction contingency) and $7.64 million total project cost.