By Tim Cox
Members of Celina City Council's utilities committee on Wednesday studied the results of pilot testing the city has been doing at the water treatment plant since mid-December.
City officials tentatively plan to add carbon-based filtration to the city's existing water treatment process. Preliminary results show trihalomethanes (THMs) levels ranging from 8 to 30 parts per million, with the EPA limit at 80 parts per million.
Before making the estimated $2 million expenditure, though, they want to make sure the technology will solve the city's problems at an affordable price. The city has $750,000 set aside from a Congressional line item grant to help pay for the water fix.
City officials plan to continue pilot testing during the next several months to ensure there are no anomalies in early test results. City officials have started sending water samples to a second laboratory to confirm early results.
Early testing shows the granular activated carbon (GAC) material can effectively reduce THM levels to within allowable levels. To carry out the lab tests, city officials take an unchlorinated water sample that has been run through the GAC pilot test. That sample then is sent away to a private laboratory where the water is chlorinated and then held for five days until further testing. The test is supposed to simulate what happens to city water after it leaves the plant and reaches the furthest homes from the water plant.
Those test results have proven promising but also a bit confusing. The lab has split some of the samples and tested both parts of them, sometimes yielding numbers that are not close to each other.
For example, one split sample showed THM readings of around 8 parts per million while the other sample split from it tested at 30 parts per million.
Water Superintendent Mike Sudman said city officials are looking for "repeatable results" that show similar numbers. That is why the second lab was used.
"Mike is constantly challenging the system," coming up with new twists on the lab tests to ensure city officials are covering all bases, city consultant Kent Bryan said.
Test results from the second laboratory have so far yielded more consistent results. Samples from that lab have been running just over 8 parts per million of THMs in the water and split-sample results are comparable.
Councilman Chris Mohler asked if the results skew wildly when organic content in Grand Lake rises dramatically in the spring and summer.
Sudman and Bryan said the organic content might rise somewhat, but also noted the water plant operates more efficiently when it draws warm water during the summer.
The carbon filtration absorbs suspended organic material from the water so it cannot eventually react with chlorine to form the potentially harmful THMs. The city has struggled for years with excessive levels of the chemical compound linked to some forms of cancer and other diseases in laboratory research.
While testing of the new system continues, design of the permanent GAC installation cannot wait much longer, Bryan said. The city faces an EPA-mandated deadline of November 2007 to fix the water. Bryan said he expects to make a recommendation to move forward with design after another four to six weeks of pilot testing.
The pilot testing will resume through the summer so if there are catastrophic test results, city officials will know that before building the new treatment area. However, if they were to abandon the GAC treatment at that point, there would be virtually no way to gain compliance by the EPA's deadline.