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KELLERT.CC Page 1 MEMORANDUM Date: October 12, 1994 From: Les Lyle To: Mayor Bascom and City Council Subject: Tree Protection on Franklin Blvd. Sewer Rehab Project On September 14, 1994, Councilor Keller requested information regarding the tree protection measures we used on the Franklin Boulevard sewer rehabilitation project and what future specifications we may use given the Council adoption of the tree preservation ordinance. The Franklin sewer rehabilitation project involved the replacement of a deteriorated sewer system that has exhibited excessive infiltration effecting system capacity. The existing sewer was located within the medians the full length of the project. Staff evaluated a number of alternatives to avoid impacts to the trees in the medians and chose to relocate the sewer into the pavement area. This approach was more costly given expected rock excavation and greater traffic control. To reduce our pavement restoration costs and to address the pavements deteriorated condition, the City entered into an agreement with ODOT to have the City resurface the road following sewer installation. Since the proposed sewer construction would be in close proximity to the islands and trees, we created special provisions language that required "the contractor to protect all vegetation from damage" and that "the contractor shall minimize the operation of equipment around all trees in the median ". Early in the construction, we encountered excessive rock and had to revise portions of the alignment which caused the sewer to be closer to the trees than originally planned . In one specific location, we evaluated several alternatives to mitigate the effects of having to move back into the median, since remaining in the street would have had a very high cost to the City. Two options included using the existing sewer trench or lining the existing sewer with PVC pipe to avoid removing two trees. The condition of the existing pipe did not lend itself to lining and the existing trees were in poor condition, so staff concluded removing and replacing the sewer and trees was the preferred alternative. Also during construction, we found that the tree protection measures were not working as successfully as we would have liked, so we required the contractor to install root zone protection fencing and to remove any materials from the root zones. We have also modified our construction specifications to more effectively meet the requirements of the tree protection ordinance for all future projects. Our intent throughout the project was to balance the goals of the project with other goals of the Council and community. When designing and constructing an improvement project all the needs within the right -of -way are evaluated including ADA, bikelanes, sidewalks, trees, landscaping, number of travel lanes, alignment, utilities, etc. When trees are removed, our policy is to replace and were possible densify the number of street trees. For future projects, we will continue to evaluate the most appropriate and cost effective approaches to accomplish the multi - objective goals within the right-of-way. Each project is a learning experience and we strive to leam from those experiences.