Key sewer questions raised
We would like to thank Henry Germond for raising several important questions about the Oswego Lake Interceptor Sewer in his April 5 citizen's view. In fact, Henry raised several questions that city council members have asked city staff during the course of this project. We have attempted to paraphrase and, hopefully, help answer these questions, with what we have learned over the past several months about the community's wastewater collection and treatment system.
Some of Henry's questions included: If the current sewer deficiencies are primarily inflow and infiltration (I/I) during heavy rains in the laterals and trunk pipes leading to the interceptor, why don't we just fix the laterals? Why can't we keep the existing interceptor working until we save some money to replace it? Why don't we separate surface water drainage from sanitary sewers like Portland and many other cities?
The city of Lake Oswego has separate sanitary and storm systems. Portland does not. In fact, Portland is embarking on a plan to increase the size of its combined system so that more stormwater, along with wastewater, can be treated at its treatment plant.
Inflow and infiltration, or I/I, refers to stormwater and groundwater entering the wastewater collection (sanitary sewer) system through small cracks in pipes or manholes or illegally connected storm drains, or downspouts. Any piped collection system, whether combined or separated, has I/I because of those small cracks that can occur over time.
Lake Oswego will continue to address its I/I problem, funded with your sewer fees, as part of a sustained strategy to reduce costs paid to Portland for treatment and to protect ground and surface water quality. The city has been spending over $500,000 dollars annually to replace, repair and rehabilitate our wastewater collection system to reduce I/I. This year that amount has been increased to close to $2 million on rehab, assessment, monitoring and capital construction. Going forward, the draft FY 08/09 budget contains over $5 million for addressing the I/I issue through a variety of programs.
While I/I is a problem, the interceptor is also seismically deficient. It is because of this issue as well as past overflows that long term improvements cannot wait. More than 9,000 feet of the interceptor in the main portion of Oswego Lake is supported on piles and is not likely to survive moderate ground shaking from an earthquake, potentially spilling millions of gallons of raw sewage into the lake every day. The earthquake vulnerability, of course, depends on many factors, such as the depth of a quake, the distance of the lake from the epicenter of the quake and the strength of the quake. For example, had the epicenter of the Scott's Mills earthquake in 1993 been a few miles closer to us (it was 34 miles away), had the quake occurred at a slightly shallower depth than the nine miles at which it occurred or if it had been slightly stronger at the Scott's Mills location (it was 5.6 magnitude), the lake interceptor could have been damaged.
A solution must be found to address both the capacity and seismic issues. If we wait for the chance that our efforts will reduce I/I to a significant degree it would still only solve a part of the interceptor problem. The city is now under a Mutual Agreement and Order with the Department of Environmental Quality to stop the overflows. A slightly larger interceptor will stop overflows and will be seismically stable. Soon, with the help of citizens, we will be able to choose which solution, the in-lake or around-the-lake option, is the best for the community and the environment.
Mayor Judie Hammerstad and Councilors Ellie McPeak, Frank Groznik, Roger Hennagin, Kristin Johnson, Donna Jordan and John Turchi.