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<br />7A - ATTACHMENT NO.3 <br />Saltworks Proposal- Water Group Summary Report (22 January 2010) Page 12 <br /> <br />The Saltworks project includes options for between 8,000 and 12,000 residential units. <br />To plan for the maximum residential water demand, 12,000 units is the basis for the <br />DMB Demand Report water demand. The residential units are all multi-family <br />(attached), and include townhouses, condominiums, and apartments. The DMB <br />Demand Report assumes a range of household sizes from 2.3 to 2.8 persons per <br />household, with an average occupancy of 2.55 persons per household. <br /> <br />Based on the methOdOlogy and results presented in the DMB Demand Report, the <br />average indoor residential unit demand factor would be approximately 37 gallons per <br />capita per day (gpcd). This factor results in an indoor residential demand of about 1,250 <br />acre-feet per year (AFY). The Saltworks project proposes to use potable water for all <br />residential indoor demands except toilet flushing. The Demand Report assumes that 75 <br />percent (940 AFY) of indoor residential use will be served by potable water, and 25 <br />percent (310 AFY) served by recycled water. <br /> <br />2.2.2 Commercial and Institutional (C&I) Indoor Demand <br /> <br />The land uses that fall into this category include office space, various types of retail <br />(including restaurants), community facilities (including fire station, library, educational <br />facility), and schools. The DMB Demand Report acknowledges that no standard models <br />have been developed to estimate water use factors for C&I land uses, as they have for <br />residential uses. The primary reference used for this category is the Pacific Institute's <br />2003 Waste Not, Want Not study. <br /> <br />Water use factors were developed for each of the C&I land uses based on information <br />and assumptions regarding employee water use factors, number of employees per 1,000 <br />sqft of building area, and estimated water savings from water-efficient designs and <br />technologies. Water demand for schools was based on a calculation of the number of <br />employees per student. The retail component was assumed to be 50 percent retail use <br />and 50 percent restaurant use. Similar to the residential methodology, additional <br />conservation savings (from efficient plumbing fixtures and appliances) were subtracted <br />from the employee-water-use-factors. These additional savings were also derived from <br />the Pacific Institute study. C&I indoor water use assumes that potable water will be used <br />for all demands except for toilet flushing and cooling, which would be served by recycled <br />water. The Demand Report assumes that 50 percent of indoor C&I use would be served <br />by potable water, and 50 percent by recycled water. <br /> <br />Based on the methodology and results presented in the DMB Demand Report, the <br />anticipated demand for C&I land use categories are as follows 1: <br /> <br />· Office (1 million square feet) - 130 AFY <br />· Retail (70,000 square feet) - 8 AFY <br />· Restaurant (70,000 square feet) - 12 AFY <br />· Community Facilities (50,000 square feet) - 5 AFY <br />· Schools (200 employees) - 25 AFY <br />· Total C&llndoor Demand -180 AFY <br /> <br />1 Due to rounding in the DMS Demand Report, the indoor water demand values presented in the <br />bullet list may not exactly match values from the DMS Report, but does not change the results of <br />the analysis. The total C&I indoor demand of 180 AFY does match. <br /> <br />5 <br />