Coweta’s B.T. Brown Water Treatment Plant, which for many years operated at a trickle because of low demand for locally produced water, is ramping up production and has now been approved to treat more water per day.
The Coweta Water and Sewerage Authority has received an approval letter for an increased filtration rate at the plant, which makes it possible for the plant to treat 7.77 million gallons of water per day. The previous maximum was 6.06 million gallons per day.
The filtration rate – the speed at which water goes through the plant’s filters, is being increased from 3 gallons per minute, per square foot, to 3.84 gallons per minute per square foot.
The filters, which use sand and anthracite coal, are the final physical step in the water treatment process. After filtration, the water is chlorinated.
The amount of water that authority customers use has grown steadily over the past few years – as has production at B.T. Brown, which is located on the B.T. Brown Reservoir on Alexander Creek Road.
The authority will be able to use more of its water as the water supply contract with Newnan Utilities ramps down in 2022. But at the same time, the authority’s 50-year contract with the city of Griffin ramps up to its maximum of 5 MGD.
The impetus for increasing the plant’s capacity came during a short drought in 2018. That’s when the plant and reservoir had more pressure on it than it had ever had before.
The authority petitioned the EPD to increase the filtration rate –the limiting factor when it comes to how much water can flow through the treatment plant.
Getting that approval required a lot of legwork from an engineering standpoint and a lot of data, said Authority Chief Operating Officer Rick Jones.
The authority had to provide data from plant operations and show that the increase was needed, he said. In January, the authority received the approval letter. That begins a six month period of operating at the higher rate and providing data to EPD, before there is an official increase in the treatment permit.
The 7.7 million gallons a day is the most the plant can produce without significant plant upgrades, Jones said.
Currently, “we’re running full steam,” he said. “We have to give six months of data, showing we can run at that rate for 24 hours a day for an extended period of time.”
While the overall increase is needed long term, there’s not a need for the plant to produce that much water during a rainy winter. So the authority has had to dramatically cut back on the water it is taking from Griffin and Newnan.
Jones said they’ve talked with Griffin to explain the decrease in how much water the authority is taking. Come summer, with higher demand, the authority should be able to make up the difference and “true up” the water purchases from Griffin and Newnan Utilities.
The authority has a permit to withdraw up to 10 MGD from the reservoir, but has never been able to treat that much, though that could become possible in the future with major plant upgrades.
In 2018, the drought and higher demand stressed the reservoir, with water levels dropping significantly. Because of low water levels, the boat ramp had to be temporarily closed.
One reason the reservoir got so low is that water levels had already been lowered because the authority was considering doing work on the overflow structure. The lake had to be lowered so that the overflow structure could be examined. When the drought began, the lake was already low.
The reservoir system includes a “pump back” downstream on Cedar Creek that can be used to add water to the reservoir. In the past, the pump back hadn’t been used fully, and there hadn’t been much demand on the reservoir.
Now the pump back is running regularly, and it can pump up to 4 MGD into the reservoir. While the pump back helps keep lake levels up in times of adequate flow, it might not be much help in a severe drought.
The pump back can only be operated when there is enough water flowing in Cedar Creek that water can be pumped out without impacting the stream.
Instead of helping refill a reservoir that is low, during times of drought, the pump back system is intended to keep the reservoir from getting low in the first place.
“The idea is to not get yourself in a bad situation to start with,” Jones said.