Wednesday, November 12, 2008

A Sewage Fix on the Hudson Gives Researchers Immediate Data

When a sewage treatment plant needs to be fixed, the operators can't just shut off the flow of sewage into the plant. They have to plan the repairs for a time of low-flow (very late at night or very early in the morning), disinfest the sewage as best they can, continue to release it partially-treated, and hope for the best.

When Westchester County announced recently that it had to do just that, three researchers took it as an opportunity to get real data. Here's what the Journal News reported (although oddly it doesn't say which treatment plant the repairs were made at; the count has three on the Hudson: in Yonkers, Ossining and Peekskill):

Just hours after the predawn release, the three testers found levels of the sewage-indicating enterococcus bacteria that were four times higher than usual.

The highest levels recorded exceeded recommended federal guidelines for primary exposure, such as swimming.

Though the scientists' overnight data showed bacterial spikes, the levels receded within 24 hours, as expected. ...

"There have been dramatic improvements in the water quality of the Hudson River since the (1972) Clean Water Act," said Juhl, a research scientist with Columbia University's Lamont-Doherty Earth Observatory in Palisades. "But the current data sets consist of averages. People don't go into the average water on an average day. They go in at specific locations at specific times."

Out of 27 spots that Juhl and the crew tested repeatedly in 2006 and 2007, 21 had at least one instance when enterococcus levels per 100 milliliters of liquid were higher than allowed by federal authorities for anyone with direct contact with the water, such as swimmers.

The bad news is that the repair crews didn't finish the work and will have to try again. The good news is that there aren't likely to be many swimmers in the water at this time of year.



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