Painting It Green — Replacing an All-Pipe Solution with an Integrated Solution Emphasizing Low Impact Development

The City of Portland, Oregon Bureau of Environmental Services (BES) recently completed a pre-design project that saved the City nearly $60 million, thanks in part to low impact development facilities. The centerpiece of the original solution BES recommended in 2000 that addressed sewer capacity and structural problems in the Taggart D combined sewer basin was a new, parallel, separated stormwater collection system. However, in 2004, a number of factors prompted BES to revisit the recommendation of the 2000 pre-design. Following nearly three years of work, the Integrated Taggart D Pre-design solved these same problems with a heavy reliance on low impact development facilities, along with new combined sewer pipes. These stormwater facilities not only provide sewer capacity but also watershed health benefits such as groundwater recharge and added vegetation that improves urban habitat conditions. The cost estimate of the 2007 watershed-based solution is $81 million, compared to the $144 million investment needed to construct the original 2000 solution. The 2007 integrated pre-design approach enabled BES to address multiple goals through one pre-design. The project recommendation included elements to resolve sewer backups, to address pipe rehabilitation needs, to improve watershed health, and to assist in combined sewer overflow control. It produced 35 projects ready for final design within BES' capital improvement program. Construction of the first two projects, together includes approximately 75 low impact development facilities, is anticipated in spring 2009. These capital projects complement other parallel programs BES recently initiated that collectively advances watershed health conditions in this basin: street tree plantings, community outreach, and revegetation of areas containing invasive species.