Memorandum <br />Page 1 of 2 <br /> <br /> <br />800 Willamette Street, Suite 400, Eugene, OR 97401 541.684.4902 FAX 541.684.4909 <br />Eugene, OR Portland, OR <br />DATE: May 8, 2026 <br /> <br />PROJECT: 2600120-Bushnell-Duke SUBJECT: Stormwater Analysis <br /> <br />TO: City of Eugene Planning Department FROM: Taylor Hood, PE <br /> KPFF Consulting Engineers <br /> PHONE: 541.735.9250 <br /> EMAIL: taylor.hood@kpff.com <br /> <br />This memo has been prepared to support the Bushnell University Duke Commons Site Review application <br />and to document compliance with the City of Eugene stormwater requirements. The proposed design <br />demonstrates consistency with the 2025 Eugene Stormwater Management Manual (SWMM) and applicable <br />stormwater quality, flood control, flow control, oil control and source control provisions of the Eugene City <br />Code. <br /> <br />The stormwater design may be refined during the Building Permit phase. However, all revisions will continue <br />to comply with the 2025 SWMM and Eugene City Code. <br />Existing Conditions <br />The project site encompasses approximately 0.79 acres and was developed with a primary building bordered <br />by an alleyway to the north. The site is a combination of small structures, landscaping and pedestrian areas. <br />The Millrace runs along the site’s southern edge. There has been some building demolition performed under <br />a separate permit. The total existing impervious surfacing is 21,233 square feet. <br />Site drainage generally sheet flows south toward the Millrace or is collected in drains and roof downspouts <br />within the site and conveyed to an existing public storm line in the alley that outfalls to the Millrace . Site <br />soils are mapped as the Malabon–Urban Land complex, classified as Hydrologic Soil Group C. <br />Proposed Conditions <br />The proposed development includes a single building with paved sidewalks and patios, stormwater <br />treatment, landscaping and utility installation. Proposed grading, drainage facilities and stormwater <br />improvements are shown on the accompanying Site Plans. <br />Stormwater Management Approach <br />Stormwater runoff will be managed in accordance with the 2025 City of Eugene Stormwater Management <br />Manual (SWMM). The SWMM requires water quality treatment for all new or replaced impervious areas. <br />For this Site Review Analysis, all proposed impervious areas are conservatively assumed to be replaced. Final <br />determinations regarding repaired versus replaced impervious area will be made during the Building Permit <br />phase, consistent with Chapter 9 of the SWMM. <br /> <br />The SWMM employs a hierarchical approach to stormwater management, prioritizing infiltration first, <br />followed by filtration where infiltration is not feasible. Runoff from impervious surfaces will be treated by <br />vegetated stormwater treatment facilities or otherwise addressed per the SWMM. Treated runoff will be