AgdaPkt 2010-02-01 clsd and regular

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7A - ATTACHMENT NO.3 Saltworks Proposal- Water Group Summary Report (22 January 2010) Page 17 2.3.5 Redwood City Attachment Q-Based Water Demand Summary Table 1 presents the Attachment Q-based water demand projections for the Saltworks project. Sased on the information in the preceding sections, the total water demand for the Saltworks project using the City's Attachment Q methodology is as follows: · Total Indoor Demand - 2,243 AFY (80 percent potable, 20 percent recycled) · Total Outdoor Demand - 1,396 AFY (100 percent recycled) · Total Water Demand - 3,639 AFY (50 percent potable, 50 percent recycled) When property is proposed to redevelop from one land use to another, the City typically provides a "credit" to the site for its historic/existing water usage in calculating total water demand; this credit is calculated into the Attachment Q demand. Therefore, existing potable water use at the Cargill salt harvesting operations would be subtracted from the projected new potable demand, to arrive at the net increase in water demand for the Saltworks project. The water team has been provided some potable water use data from the City for the Cargill site, but DMS has not confirmed this usage. Therefore, it has not been calculated into the Attachment Q water demand at this time. In addition, City staff has indicated that two potential water demands for the Saltworks project were not identified in the DMS Demand Report. These two uses are swimming pools for homeowners' associations and public facilities, and the proposed wetlands restoration. Swimming pools will likely be included in the Saltworks project, but they are not identified as a separate water demand category in the DMS Demand Report. Also, whether the proposed wetlands restoration at the project site will require potable or non- potable water, either during "construction" or as part of long-term operations, is not known. These two demands may need to be added into the Attachment Q calculation once additional detail about them is known. 2.4 Comparison of Water Demand Projections Table 2 presents a comparison of water demand projections using the DMS Demand Report assumptions and the City's Attachment Q methodology. As shown, the Attachment Q-based demand is approximately 31 percent higher than the DMS Demand Report estimates. This comparison of demands was discussed at a meeting between the water team and the DMS water team on October 28, 2009. The DMS team acknowledged that they, too, had performed an Attachment Q analysis, and a table-top review of their results revealed them to be nearly identical (within 3 to 5 percent) to the water team's Attachment Q-based analysis. DMS also acknowledged that the consultations with the City regarding demand factors and resulting water demand projections for the Saltworks project would occur as part of the WSA process. 2.5 Summary of Findings Regarding Water Demand DMS developed water demand for the Saltworks project which is described in the DMS Demand Report. The DMS Demand Report projection methods use published models and water industry resources to derive demand for each land use category in the project. The DMS projection shows a potable water demand of 1,080 AFY and a non-potable water demand of 1,430 AFY for a total demand of 2,510 AFY. The demand projection methods of the DMS analysis assume highly efficient fixtures, precise installation, and ongoing regulatory oversight to sustain the initial efficiency. 10