By John Schaffner
Since January of this year, Collier Hills resident Amanda Mayberry and her neighbors have taken about 30 samples of creek water in Tanyard Creek Park. All but three have shown E. coli contamination levels above those the Environmental Protection Agency considers standard for recreational water quality.
Those three samples were recorded on Feb. 11 and 25 and March 4. Each sample since has registered slightly above the normal amount of 235 MPN/100 milliliters or higher. The high reading was 52,310 MPN/100 milliliters on March 11.
For months, Jason Ulseth, technical program director at the Upper Chattahoochee Riverkeeper organization, has been monitoring the readings ,each taken on a Thursday at about 1 p.m. In June, he began working with engineers at Atlanta’s Department of Watershed Management to try and determine a source for the contamination.
Both Ulseth and the DWM staff have concluded the stream waters are being contaminated somewhere upstream from Tanyard Creek Park, possibly in an area near apartment complexes just off I-75.
“The riverkeeper believes that the high E. coli levels are due to a ruptured sewer line or an illegal tie onto a storm drain somewhere upstream by the apartment complex,” Mayberry wrote in an e-mail to Collier Hills neighborhood president Barbara Kennedy.
Ulseth wrote in a separate e-mail to Kennedy, “We have identified one pipe in particular that we think has been contributing significantly to the high levels. The city is currently pulling additional samples from the pipe and will hopefully be source tracking through the pipe and will find the problem soon.”
Ulseth and DWM inspectors have walked from Tanyard Creek Park to the Combined Sewer Overflow (CSO) unit’s gates at I-75, pulling water samples.
In August, Ulseth said his analysis of samples for E. coli bacteria had shown that a sample taken at one source flowing into the stream registered 11,000 MPN/100 milliliters. Another sample registered 7.000 MPN/100 milliliters. That was before they became diluted by the stream water.
MPN stands for “most probable number.”