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Pennsylvania A, B, C, D Streets, and Colorado. The equalization basin and the coal mine trail interceptor projects were started and completed in 2006. NO PROJECTS FORECASTED: WASTEWATER TREATMENT PLAN & OPERATIONS BUILDING - N 5 RD The original two-lagoon system was built in 1973 and updated with an addition of a third lagoon and the building that contains the chlorine contact tank and aeration basin in 1989. In 2006/2007 when the City joins the regional sewer system it will be converted to an attenuation basin. STORM SYSTEM PLAN The Storm water system is made up of the old sewer system. The sewer system was upgraded in 1973 allowing the City of Roslyn to separate sewer and storm water. The storm water utility was created in 1996 and the system designed in 1997. The construction ofthe facility was done with a grant. Much of the work has been done already to separate the storm water and sewer system . CAPITAL IMPROVEMENT PROJECTS: The hydraulic model results identified locations where the conveyance system was under capacity and required larger pipes. City staff identified sections of the existing stormwater system that require maintenance or replacement. A goal of the City is to locate all drainage facilities in right-of-way or City owned property. The projects identified in the CIP plan support this goal. The projects described below are developed based on the hydraulic model results and input from City staff. Survey should be conducted as part of the design of any recommended capital improvement project to ensure the most accurate and effective design for the project. All recommended projects assume that the existing slope will be utilized in the future. CIP 1-PENNSYLVANIA PLACE BOTILENECK Schedule: 2016 Estimated Cost: $230,000 City staff has identified the pipe section south of Washington Avenue as the highest priority for replacement in the stormwater system because of the bottleneck that occurs at this location. The hydraulic model results indicate that this section has capacity to convey less than 15 percent of the flow from the 2-year storm event. To convey the 10-year peak flow of 186 cfs 325 feet of 24-inch-diameter pipe should be replaced with 48-inch-diameter pipe. CIP 2 -SOUTH A STREET CULVERT Schedule: 2016 Estimated Cost: $220,000 City staff has identified the culvert at South A Street, north of West Hoffmanville Avenue as a priority for replacement. The existing parallel 30-inch-diameter pipes do not have sufficient capacity to convey the 10-year peak flow of over 350 cfs. This culvert conveys flow for Crystal Creek and must meet the design guidelines in "Design of Road Culverts for Fish Passage," from Washington Department of Fish and Wildlife. The cost estimates here use the Stream Simulation Design Option resulting in a box culvert of dimensions 5-feet tall, 8-feet wide and 60-feet long. June 15, 2016