Voter interest in large-scale improvements to our sewer piping would have little 'traction' were it not for the overflows of sewage into the lake during rainstorms. Yet the true cause of these overflows is simply store water that is directed into our sanitary sewer. It is called in-flow and infiltration, some of it on public and some on private property. Existing pipes at the West End become choked with storm water.
So far the projected improvements would do nothing to stop this in-flow and infiltration. City policy seems to be build it bigger and swallow it all. Building it bigger would still require the Tryon Creek Plant to handle storm water from infiltration and in-flow. Sometimes this flow is so great that the mixture cannot be fully treated, so they just chlorinate a partially treated effluent and release it into the Willamette River. Do we want this to continue?
The fact that storm water enters our sanitary sewer is proven by the daily meter readings at the treatment plant. Records show that flow rates during rain events are often more than three times the normal dry weather flow. We have known about this for decades but have done little to stop it other than require new buildings to separate the flows. Even with population growth over the years, that ratio shows no sign of changing.
Granted, the 'big pipe' under the lake is getting old. But in dry weather it continues to carry sanitary sewage down to the treatment plant. Assuming we can do something to reduce the storm water flow, this raises the question: Can we keep the existing pipes working for a few more years while we accumulate a 'sinking fund' (earning interest) for its ultimate replacement? Part of the cost of replacing the 'big pipe,' et al, with new and improved pipes is that seismic (earthquake) design standards have been raised. Yet the present design seems to be surviving.
Portland and many other cities recognize that 'combined sewers' are costly. The new 'green' way is to separate surface water drainage from sanitary sewers. Portland even offers incentives to redirect roof and parking area drains into the natural environment. I've done it and it was easy. Suppose everyone did it? If we substantially cut infiltration and in-flow, would sewage spills cease? Why not start now? New piping wouldn't be operational for two or more years.
Voters will soon be asked to approve a big bond issue for sewer piping improvements. Before we do that, should we rethink this issue more thoroughly?
Henry Germond is a resident of Lake Oswego.