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Upstream Discovery <br />The existing upstream basin consists of the landscaped area separating the development to the <br />east. Flows from the landscaped area will be very minimal if any. These flows will be <br />intercepted and routed through the detention system and/or bypassed to the wetland area to <br />the west. No negative impacts are anticipated for the upstream basin. <br />Downstream Analysis <br />Stormwater runoff from the proposed development will enter the existing drainage system in <br />80T" Street S.W. Flows travel west in a series of pipes and catch basins along 80T Street. <br />Flows then travel north along 16r" Avenue West. Apparently the flows enter a large wetland <br />north of 75T" Street S.W. and east of Seaway Boulevard. Flows eventually enter Narbeck Creek <br />and flow to Port Gardner Bay. <br />Conclusions <br />The downstream conditions and conveyance systems are adequate to handle the additional <br />flow that this development will create. Additionally, the proposed development will be <br />discharging at'/: the existing 2-, the 10- and 100- year storm event rates. There were no signs <br />of erosion, sedimentation, flooding or conveyance restrictions within one -quarter mile <br />downstream of the site. No adverse impacts are anticipated on the downstream conveyance <br />system as a result of this development. <br />M.1SDG1800117/-SDG-01%docslDrainageAnatyslsT?.doc 13 <br />