Scappoose advances $21 million wastewater plan
Upgrades to wastewater treatment infrastructure in Scappoose are estimated to cost roughly $21 million over the next 20 years.
For the past four years, the city has experienced measured growth in both housing and industry, but with growth comes the need for proper water and wastewater systems.
Scappoose city councilors advanced a first reading of an ordinance Tuesday, Sept. 4, to update the city's wastewater facilities plan. Initially, the city contracted with Keller Associates Inc. to develop a wastewater planning study. Not completely satisfied with the study produced by Keller, the city tapped Carollo Engineers in 2017 to create a facilities plan that projected the city's growth and wastewater treatment needs into 2042.
Using growth rate models from Portland State University, Carollo's plan estimates Scappoose's population will reach roughly 11,560 people over the next 20 years.
The plan analyzes the city's schematic of current equipment and facilities, how effective each machine is and when each component might need to be replaced.
The city's system relies on ultraviolet disinfection, clarifiers and what are called "lift stations."
Much of the city's equipment is outdated and doesn't function efficiently anymore, city public works staff noted.
"We have a very aged facility out there, everything is just starting to fail at this point," Dave Sukau, the city's public works director, told city councilors Tuesday.
"The secondary clarifiers do not have sufficient hydraulic capacity to meet projected peak flows," Carollo's plan states.
"This is equipment from 1992, it's outdated and not supported anymore," Kevin Turner, the city's wastewater treatment plant supervisor, said of the current UV disinfection equipment.
Phase 1: The first phase comes with an estimated price tag of $6.43 million and includes: a lift station near Spring Lake; new UV disinfection; hydraulic improvements; and the addition of a new, 50-foot piece of equipment called a clarifier.
Phase 2: The second and likely most costly phase of upgrades will include a new SCADA system and headworks and influent pump station. Those upgrades will cost somewhere around about $7.2 million.
Phase 3: Further down the road, the city will need to add an additional UV disinfection area and rehab several components of an effluent pump station, while adding a new 15-inch outfall at an estimated cost of $4.4 million.
Phase 4: As planned, the final phase includes the addition of a new $2.5 million aerobic digester to process biosolids.
"We kind of readjusted these timelines, based on what we thought were the real pressing needs of the facilities, not just what the engineers thought," Sukau noted.
City officials say the large capital projects will need to be funded through a variety of sources, including development fees, wastewater rates and new revenue sources. The city is currently considering whether to add an urban renewal area to help fund major infrastructure projects like these.
City councilors are expected to give final approval to the plan later this month.