Authority to test sewer discharge
DEP requests review to determine if area’s overflow system pollution is a problem
Under pressure from the state Department of Environmental Protection, the Altoona Water Authority is planning a program to determine whether pollution from its two Combined Sewer Overflow systems is problematic.
CSOs were once commonly installed in cities, but were never ideal, because they collected both sewage and street runoff in the same pipes, so that when there were storms, and the volumes became too great for the pipes and sewer plants to handle, the excess carried sanitary sludge residue that had settled in the pipes during dry weather into the streams, polluting them.
Under pressure from DEP in the late 1980s, the authority built two facilities to hold the “first flush” from storms, keeping the worst of that pollution out of the streams, improvements supplemented a few years ago when the authority increased the capacity of its sewer plants — although during storms, when the tanks fill, and volume remains too high for the “outfall” pipes, some sanitary effluent still flows to the streams.
Under renewed pressure from DEP, the authority is planning a five-year pollution testing regimen for various locations downstream from the Westerly Sewer Treatment Plant, which discharges into the Beaverdam Branch of the Juniata River, and the Easterly plant, which discharges into the Little Juniata River, all the way to Petersburg, where the confluence of branches creates the Juniata River, authority consulting engineer Mark Glenn said.
Glenn and authority officials predicted that the testing won’t reveal there’s a problem.
Between the late 19th century construction of Altoona’s system — which serves the core areas of the city — and construction of the tanks at Tuckahoe Park and near the Peoples Natural Gas facility, the pollution that occurred was “objectionable,” Glenn said.
But the tanks helped greatly, according to Glenn.
Still, the DEP in recent years has become increasingly concerned with bacterial contamination, particularly fecal coliform, and especially because, with Altoona being at the headwaters of the Juniata system, the discharges can sometimes comprise a large portion of the stream flows, Glenn said.
The department has been delaying its grant of five-year discharge permits because of such concerns, he said.
The authority has tried to show with modeling that the current setup is adequate, Glenn said.
But DEP wants the testing.
Accordingly, the authority is developing a map of where it will set what will probably be automated equipment on bridge piers and other such structures in the rivers, according to staff engineer Michael Sinisi and General Manager Mark Perry.
There are no cost estimates yet for the program, Glenn said.
The DEP should finally grant new five-year discharge permits at the end of the program, Glenn predicted.
If the test results prove to be unsatisfactory, there are a couple of potential fixes — one or both of which could be put into place, according to Sinisi, who agrees with Glenn that the testing should prove such fixes unnecessary.
One of those fixes is installation of parallel outfall pipes from the CSO holding tanks to the sewer plants, both of which can handle the storm flows, but neither of which can receive them, because of the inadequate capacity of the outfall pipes — although ongoing lining projects will smooth those pipes and help increase flow somewhat, Sinisi said.
The other fix is installation of ultraviolet disinfection units in the channels that take the overflows that can’t fit into the outfalls — after the tanks are full — to the streams, Sinisi said.
“(Glenn) is hopeful we’re not going to have to (put those fixes into practice),” Sinisi said. “I’m not expecting that we’ll need to.”
One indicator that the current setup is not a problem is the existence of plenty of aquatic life downstream from the plants, which is reflected in the increasingly improved quality designations of those streams over the years, Glenn said.
The CSO system is partly under manual control and partly automatic, Sinisi said.
The manual control resides in a “pinch valve” with which the authority can direct excess volume into the tanks, until the tanks are full.
The automatic control is downstream from the tanks, where the pipes bifurcate into the outfalls to the plants and the channels to the streams.
The ideal is always to send the entire flow to the plants, Sinisi said.
But when a storm occurs, and rising volume threatens to exceed the capacity of the outfalls, the authority begins to divert water into the tanks, each of which hold more than a million gallons, Sinisi said.
It continues to do so until the tanks are full.
After that, if the flow volume exceeds the capacity of the outfall pipes, the effluent rises and begins pouring into the channels that take it to the streams, Sinisi said.
After the storm subsides, the authority pumps the tanks into the outfalls, so that water at least, is treated by the plants, Sinisi said.
Mirror Staff Writer William Kibler is at 949-7038.