6301 36TH AVE W 2016-11-01 - Laserfiche WebLink

0 • The analysis in the Water System Plan projected the overall future peals-hour demand for the area at 2.7 gpm/acre (approximately 4,000 gpa/day peak flow),and assumed fire flow requirements of approximately 3,500 gpm for commercial and industrial/manufacturing uses. Based upon the proposed design of the water system,any development using more than 2.7 gpm/acre has the potential to affect water pressure on other sites. Additional analysis will be required for development proposals with a peak hour demand above 2.7 gpm/acre and/or a fire flow requirement of 3,500 gpm or greater. The additional analysis maybe as simple as calculations completed by the Public Works Department prior to a pre-application meeting on a specific development proposal. The additional analysis must determine how the proposal's water demand will affect the entire water supply and distribution system. Projects with no additional major improvements needed and no adverse cumulative impacts on the water supply and distribution system are covered by this analysis. The 2.7 gpm/acre is an overall average peak hour demand assumed for planning in large areas such as the study area. However,there will undoubtedly be site-specific proposals with larger demand. For example,large irrigation systems can exceed 50 gpm/acre demand. Other land uses with demands much lower than 2.7 gpm/acre,such as warehouses,are assumed to occur to offset the higher demand land uses,resulting in an overall area wide average of 2.7 gpm/acre. The impacts of construction of the new water line to service development west of Japanese Gulch were not covered in the EIS. Additional SEPA analysis is required to review alternative routes for the line which will minimize the impacts of the proposal. 8.6.3 Mitigation Measures 1. Looped water mains may be required for some sites to meet fire flow requirements and to protect water quality. Pressure reducing valves may be required when looped systems are constructed. (SEPA Public Services and Utilities Policies) 2. Developments must construct improvements necessary to provide a water pressure of 40-80 psi under normal operating conditions as required by Public Works. (SEPA Public Services and Utilities Policies) 3. Recycling of runoff water from bus or truck washing facilities is required. (SEPA Public Services and Utilities Policies) 4. New water system facilities must avoid environmentally sensitive areas to the maximum extent possible. Where water lines must be constructed through environmentally sensitive areas,best management practices must be followed. (See the mitigation measures discussed in Section 4) (SEPA Earth,Water,and Plant and Animal Policies) 5. Where utility connections are required through adjacent properties or connecting into residential areas, easements must be located in such a manner as to minimize the visual impact on the adjoining properties to the greatest extent feasible and must be revegetated in accordance with a landscaping plan approved by the Planning Department. Landscaping must be consistent with Engineering and Public Services requirements for protection and maintenance of the utility easement and facilities and should consist of native shrubs and groundcover. (SEPA Land and Shoreline Use,Plant and Animal,and Public Services and Utilities Policies) 8.7 SEWER 8.7.1 Threshold Capacity of the system is 1,700 gallons per gross acre per day,and 4,000 gallons per gross acre per day of instantaneous peak flow. Some sites may have capacity in excess of the threshold available to serve potential users. If a proposal would exceed 1,700 gallons per gross acre per day and/or 4,000 gallons per gross acre per day of instantaneous peak flow, additional analysis will be required. The additional analysis may be as simple as calculations completed by the 15 , �oa