UO North Campus June 15, 2018 <br />Conditional Use Permit Stormwater, Sanitary Sewer, and Water Analysis Report <br /> <br /> <br />INTRODUCTION <br />This report provides an evaluation of the stormwater, sanitary sewer, and water supply <br />infrastructure requirements to support the UO North Campus Conditional Use Permit (CUP). This <br />report includes an analysis of stormwater management requirements to demonstrate compliance <br />with applicable City Code requirements. <br /> <br />STORMWATER <br />Existing Conditions and Drainage Patterns <br />The existing site south of the railroad tracks is fully developed with buildings, parking lots, walkways, <br />outdoor storage areas, and green space (i.e. lawns, landscaping, gardens, and riparian areas). The <br />existing site north of the railroad tracks (the Riverfront Area) consists primarily of vegetated land with <br />paved bike and pedestrian paths. The most significant impervious surface within the Riverfront area <br />idor extending from the north end of Riverfront Parkway to a point near <br />Autzen footbridge. <br />Stormwater runoff from the site is ultimately conveyed to the Millrace or the Willamette River. Existing <br />drainage basin boundaries and destination points are shown on Drawing C01 and summarized as <br />follows: <br />South Millrace Basin (Basin A): This basin represents the majority of the site south of the railroad <br /> <br />tracks and is characterized as the area that drains by gravity to the Millrace. The majority of the <br />drainage in this basin is collected and conveyed through piped conveyance systems, but <br />drainage adjacent to the Millrace is conveyed by sheet flow. The piped conveyance systems <br />discharge to the Millrace through multiple outfalls. <br />Riverfront Pump Station Basin (Basin B): This basin includes the area served by the Riverfront <br /> <br />Pump station, and includes land south and north of the railroad tracks. Drainage within this basin <br />is conveyed through public piped conveyance systems within Riverfront Parkway and Millrace <br />Drive. The storm drain system enters the ted in Riverfront <br />Parkway and th <br />the north bank of the Millrace (located under the Riverfront Parkway bridge). <br />North Athletic Field Basin (Basin C): This basin includes the athletic field located near the south <br /> <br />end of the Autzen footbridge. Surface and subsurface drainage from the field is conveyed to the <br />private outfall. <br />North Millrace / Willamette Basin (Basin D): This basin includes the remaining land in the <br /> <br />Riverfront area that is conveyed to the Millrace or Willamette River through sheet flow or shallow <br />surface flow. Flows from this basin are distributed throughout the length of the adjacent Millrace <br />and River. <br />Hilyard Street Outfall Basin (Basin E): Although this basin is not within the North Campus CUP <br /> <br />boundary, it is adjacent to the east edge of the CUP boundary and is noted here for context. <br />This basin includes the cul-de-sac at the north terminus of Hilyard Street and may include some <br />of the paved yard/lot located north of the cul-de-sac. Drainage from this basin is conveyed <br />public outfall to the Willamette River. <br /> <br />Soil and Groundwater Conditions <br />Soils: Based on City of Eugene and Natural Resource Conservation Service (NRCS) mapping, the <br />soils throughout the site are classified as sandy and gravelly soils with relatively high infiltration rates, <br />with Hydrologic Soil Group (HSG) classification of A or B. However, geotechnical boring log data, <br />available from the 1990 Riverfront Research Park Environmental Site Assessment (ESA), indicates <br /> <br /> <br /> <br /> <br /> |3 <br /> <br />