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Liberty makes no move on sewage plant
Members to consider county's overall water plan
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At a meeting to review the results of a study measuring the potential impact of a new wastewater treatment plant on the Laurel View River and discuss opponents’ concerns, members of the Liberty County Industrial Authority declined to make a move on requesting the permit for the plant be issued by the state.
Wayne Murphy with engineering firm C2HM Hill gave an overview of the study results that the Georgia Environmental Protection Division shared last month with stakeholders in Savannah, and told authority members the EPD expects a response sometime next month.
The board revisited several points in the study, including: tidal heights measured at one-mile intervals along the Laurel View River from its mouth to where it meets the Jerico River, including at the point of proposed discharge; a depth profile that determined the water’s vertical mix of dissolved oxygen was consistent; dye and drogue studies to determine the velocity of freshwater moving out of the system.
In the EPD study, Murphy said, scientists calculated the volume of freshwater moving into the system, primarily through runoff.
“They looked at present conditions, but they did not look at assumed land use increase or an increase in the amounts of impervious surfaces. They looked at a 21-day rainfall to determine runoff from the surrounding area,” Murphy explained.
Murphy also sought to calm concerns that the plant’s discharge would introduce nitrogen and phosphorous in amounts that can lead to a toxic aquatic environment. The plant would have to monitor in-stream for constituents under the permit’s rules, he said.
“There is a phosphorous and ammonia limit in the permit, and we are controlling for phosphorous in the system,” he said. “Nitrates can cause algae blooms but not without the presence of phosphorous. What we don’t know is which one of these is the limiting constituent.”
One point made several times throughout the meeting was that the state sets the limits for discharge permits, not the governing bodies that request them. The plant must then be built to meet those requirements, Murphy said.
“The state made the determination of the discharge limit and ran this study based on public concerns, to assure themselves and the general public that the system can adequately handle those limits,” he said.
Opponents continue to question the validity of EPD’s study, citing research provided by the Skidaway Institute of Oceanography, saying the EPD’s one-dimensional model is insufficient to capture the characteristics of the Laurel View River.
Murphy, however, said, “The concentration of dissolved oxygen at high and low tides shows little to no change at cross-sections. Because the water column is mixed and no thermocline is present, no two- [or three-] dimensional model is needed.”
Dr. Dana Savidge, assistant professor at Skidaway Institute, said in a phone interview she’s not sure why EPD is using the dissolved oxygen assessment as its reason for relying on a one-dimensional model.
Savidge said the complexity of water movement in the system is what needs to be addressed, and only a three-dimensional model can measure that.
While the EPD determined a 21-day retention time based on its model, Savidge said at least three characteristics of the system mean retention time can be much longer in some areas that could hold discharged treated water.
“One, the curvature of the channels, the depth and the width [at varying locations] make the water move in complicated ways,” Savidge said. “Water doesn’t move up and down uniformly. The tides are not sine wave curves, and the EPD assumes they are.”
Additionally, wind direction and strength can force water into adjacent marshlands and keep it there for much longer than 21 days, she said. The ability of organisms living in the system to use nutrients found in treated water depends also on the amount of solar radiation they receive as well as the length of time it’s received.
At the meeting, Allen Davis, president of the Coastal Estuary Protection Association, expressed the same concerns over inaccurate modeling and the potential for algae blooms.
He thanked Murphy and the board for presenting more updated information on the planned process and for the news that some constituent limits, such as for fecal coliform, have been lowered under the permit.
“One thing that needs to be factored into this discussion is the problem that these waters you would discharge into are connected to bodies of water in other counties and the U.S.,” Davis said. “We do need a wastewater treatment plan, and now that we’ve learned that there will be modifications to the permit, let’s see if those opponents will back off their opposition.
If the board does request the permit, they must also submit a timeline for the construction, Murphy said. If they do not request the permit, the authority’s current wasteload limits and study of the river will be scrapped and the entire project must be restarted.
Rep. Al Williams, attending by phone from Atlanta, said he would rather see the project go forward based on the data at hand than continue debating the merits of the EPD study.
“At some point, when do we stop being disagreeable just to be disagreeable?” he asked. “The study was done by the state organization (that issues permits) and that is their charge.”
Williams said Liberty County’s circumstances are different than Bryan County’s, and that Liberty needs to grow economically. Many of the opponents are Bryan County residents.
“At some point we’re going to have to move forward,” he said. “We can coexist with the environment. The scientists have said the impact is minimal. I am not interested in opinion that has no scientific basis. If science says we can do it, let’s do it.”
Hinesville Mayor Jim Thomas said he was hesitant to ask for the permit, citing discussions on the regional water council about how the county should approach its planned water use in light of unfavorable conditions.
Liberty County relies on the Upper Floridian Aquifer for drinking water but it sits in a yellow zone, meaning the potential for saltwater encroachment into freshwater resources along the coast is considerable. Thomas said he believes this should be considered when planning for the type and capacity of a sewage plant, as well as planned growth.
The authority has until sometime in May to make a decision on the permit, Murphy said. “The permit can’t be issued until the phasing is indicated.”
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