EPB is once again addressing concerns of possible overbilling. In a letter to the utility's board over the weekend,  Chattanooga Mayor Andy Berke asked the company to release details regarding the city's streetlight replacement program, and possible billing mistakes.

EPB says it told the city last year about the misclassification of street lights, which resulted in overbilling. But it says the city was also underbilled for the cost of buying the lights that were actually on the poles, so the costs canceled each other out. But Mayor Berke wants EPB to clear up any "confusion."

City auditor Stan Sewell turned in an April report to the city council that noted "during (the) deployment of the new (Global Green LED) lights, discrepancies were discovered in EPB's street light billing classifications." As a result, Global Green says the projected savings to the city for rolling out its new lights were thrown off, which Sewell acknowledged.

"The base month we used to project off of, was a single month's billing. And in that month, there was an over billing on energy costs because of the classification of the type of lights," said Sewell.

EPB CEO Harold DePriest says the overbilling was an independent discovery and had nothing to do with Global Green's lighting initiative.     

"I don't really see how it ties in. The time frame that we're talking about is several years before Global Green even existed. Other people may make that tie, but I don't really see it," said DePriest.

He says EPB was shocked to receive a letter from Mayor Andy Berke because EPB had already notified the city of the billing discrepancies in a meeting last year.

"We met with the city. We worked it out. We thought we had an understanding. So we were somewhat amazed when we heard a report that we had overbilled the city."

The audit the city is conducting is taking a closer look at EPB's billing practices prior to 2011, before Global Green came in the picture.

In the  meantime, EPB has hired independent auditor, Mauldin and Jenkins, to review its billing practices. DePriest says he does not want to lose customers' trust.

"We value their trust. And we're not going to do anything that screws up their trust for us to the do the right thing," said DePriest.

Mauldin and Jenkins plans to present its findings to the city by July 1st.