Ordinance No. 20513 - Laserfiche WebLink

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Exhibit F to Ord. Exhibit 8 MEMORANDUM BAEZHIS & H UBBARD ENGINEERS 100 West 13 Avenue, Eugene, Oregon 97401 (541) 686 -8478 (phone) / (541) 345 -5303 (fax) www.hhengineers.com Mechanical • Electrical • Civil • Surveying To: Colin McArthur Company: Cameron McCarthy Project: EWEB Riverfront October 18, 2011 Subject: Evaluation of Existing Utility Infrastructure: Storm, Sanitary Sewer, and Water From: Geoff Larsen, P.E. Pages: 4 This memo provides a broad -level discussion of Civil Engineering - related development issues associated with the Eugene Water and Electric Board's (EWEB) Riverfront Master Plan. The focus of the following discussion is an evaluation of existing Stormwater, Sanitary Sewer, and Water utilities within the Riverfront property. Refer to the 10/03/11 memo titled "EWEB Riverfront - Review of Stormwater Standards and Proposed Code Amendments" for additional discussion concerning stormwater development issues. Stormwater The existing stormwater infrastructure throughout the EWEB Riverfront property consists of a mix of private and public drainage systems. The following provides a summary of the existing private and public stormwater infrastructure and a discussion about system capacity, basin delineation, and relevant capital improvement projects. Private Stormwater Infrastructure The majority of the roof and surface drainage throughout the EWEB property is conveyed through gravity -fed piped systems and discharged to either the existing public stormwater pipes crossing the site or to private outfalls located on the south bank of the Willamette River. The building layout and stormwater management concepts proposed in the Master Plan are expected to conflict with the majority of the existing private stormwater infrastructure throughout the site. As such, it is generally assumed that the majority of the private storm drain systems will be removed as part of the Riverfront redevelopment. Public Stormwater Infrastructure Two major public storm drainage systems extend through the EWEB Riverfront Property. The first system is the lowest reach of the 60 -inch piped segment of the Millrace, extending through the proposed Millrace Lane alignment to an outfall at the Willamette River. That segment of the Millrace, in conjunction with a secondary outfall near Kincaid Street, conveys storm drainage from the 775 -acre Millrace Major Subbasin'. The second major public drainage system is a piped system collecting drainage from the 4th Avenue right -of -way and the 47 -acre Minor Drainage Basin WS -100. That system enters the EWEB Riverfront property at the intersection of 4th Avenue and the Ferry Street Corridor as a 24 -inch pipe. From that point, it flows south for a distance of approximately 150 -ft, then flows in a northeasterly direction within a 36 -inch pipe located between the two existing EWEB Headquarters buildings, ultimately to the Willamette River outfall located near the existing pedestrian plaza east of the Headquarters Buildings. It should be noted that there are currently no drainage easements identified for the 4th Avenue public drainage system" Page 1 of 4