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<br />7A - ATTACHMENT NO.3 <br />Sa/tworks Proposa/- Water Group Summary Report (22 January 2010) Page 44 <br /> <br />water, and a storage system for this water. Given the complexity and cost of these <br />regulations, it is unlikely that OMS would opt to carry out this plan. <br /> <br />If graywater systems are installed in accordance with the OMS Supply Report, even if <br />only for landscape irrigation, the City will have the regulatory responsibility of permitting, <br />inspecting, monitoring, and backflow prevention for these systems. Monitoring <br />graywater systems can be time intensive since graywater can contain pathogens which <br />may result in a threat to health and safety if not handled correctly. <br /> <br />Rainwater as a supply source poses fewer regulatory concerns than graywater, but is a <br />much less predictable and reliable source of water supply due to variance in rainfall <br />amounts and timing. Since rainwater can be stored for months, tanks need to be <br />monitored for algae growth and mosquito habitat. Most tanks used for rainwater <br />harvesting are designed to mitigate these concerns, so that regular maintenance is <br />minimized. <br /> <br />3.6.4 Conclusions Regarding Graywater and Rainwater <br /> <br />Graywater and rainwater have the potential to provide supply for limited select demands <br />for the project. Regulations for indoor use of graywater adopted in 2009 severely limit <br />the intended use of graywater as described in the OMS Supply Report. While the OMS <br />Supply Report develops these sources as potential non-potable supply, OMS does not <br />depend on them to meet the overall water demands of the project. As described in <br />Section 3.4, all non-potable demand for the project can be met with recycled water, so <br />neither graywater nor rainwater is considered a critical component of the non-potable <br />supply solution. Additionally, the City would require the project to have an alternate <br />source of supply for any demand served by graywater or rainwater. While the project <br />may develop and use these supply sources, they cannot be counted on as reliable <br />supply for purposes of meeting project demand. <br /> <br />3.7 Conservation, Recycled Water and Groundwater Offsets as <br /> <br />Sources of Supply <br /> <br />The OMS Supply Report outlines plans to implement potable water demand reduction <br />projects, either within the Redwood City water service area or within the regional service <br />area of the SFPUC, for purposes of "freeing up" the potable water that is replaced by the <br />demand reduction project for use by the Saltworks project as potable supply. These <br />types of projects are called "offsets" and are described in this section. <br /> <br />3.7.1 Description of Concept <br /> <br />The OMS Supply Report proposes to obtain potable water supply from the City directly <br />through participating in water conservation or recycled water projects within the City's <br />water and recycled water service areas ("local offset"). The City's 2005 UWMP identifies <br />that through a combination of recycled water projects and water conservation, its 2030 <br />potable water demand will be approximately 500 AFY less than the current supply <br />guarantee from SFPUC. The recycled water supply of approximately 2,000 AFY by <br />2030 is further described by the City in the Recycled Water Task Force reports. The <br />OMS Supply Report includes supporting implementation of recycled water and <br />conservation projects to perfect these future supplies to support the demands of the <br />Saltworks project. Implementing this type of "local offset" supply source would require <br />the cooperation of both the City and entities that would participate in the water <br /> <br />37 <br />