City considers waste water
Published 8:13 pm Wednesday, September 18, 2019
When City of LaGrange staff learned about swift silt accumulation in Piney Woods Lake, the city began looking into where the extra dirt was coming from, and a contractor soon found banks eroding due to landowners clearing the buffers meant to hold the creek banks in place.
The LaGrange City Council received an update from Barge Design Solutions on the situation last week, and while several sections of city pipe were identified as repair needs, property owners removing vegetation near the creek feeding into the homeowner association controlled lake appeared to be a major contributor to the problem. The lake receives drainage from Granger Pond and a creek on Country Club Road.
“Me and Scott [Thompson] basically started at the very beginning at Piney Woods, and we walked in the center line of that creek, traced it all the way through pipes, got all the way through LaGrange High School, all the way to the amphitheater, and then we did the same thing for basin two,” said David Bishop of Barge Design Solutions.
“What you do see here is a lot of clearing being done within a buffer, and a buffer by EPD is 25-foot buffer that you can’t get inside. It is there to protect for erosion. It is there to protect ecological invertebrates, so it is there for a reason, but you’ll see this is a reoccurring theme throughout the study.”
Those empty banks mean that nothing is preventing them from collapsing into the stream during heavy rain and carrying that soil downstream.
“When you start to see the houses that tie to this creek, you see these banks that are eroding really bad,” Bishop said. “Every time it rains, it is taking soil with it, and then it is collapsing in. The trees are falling in, and that is where all the roots are being exposed from all the trees that used to be there.”
Barge Design Solutions recommended that the city repair the stream banks and educate the citizens on the purpose and regulations regarding stream buffers.
“Educate the public on how to maintain the basins for the stream banks properly, 25-foot, let the vegetation come up to stabilize,” said Scott Thompson of Barge Design Solutions. “Based on what we saw with the scoured stream banks, we believe that is the majority of the cause to the sedimentation.”
Thompson explained the available methods that the city could use to stabilize the stream banks, which ranged from making changes to allow for plants to stabilize the stream banks to concrete. Stream bank restoration is estimated to cost $300 per linear foot, putting the bill from Country Club to Piney Woods at around $900,000.
Several issues were also noted that impact Granger Pond. Granger Pond has also seen high silt accumulation, but Bishop said that build up is likely due to silt accumulation in an underwater pipe and pipe failures further up the line, which the city will need to address.
“There is also a 32 by 38-inch clay pipe that crosses North Greenwood in front of the high school that has lateral fractures within the pipe, and it is an immanent failure,” Thompson said
Both Granger Pond and Piney Woods Lake need to be mucked out, and Thompson recommended creating a settling pool for Granger Pond and adding aquatic life to the pond.
Because the repairs would likely be done over the course of several years, the council agreed to start with the pipe repairs and Granger Pond, using SPLOST funds designated for storm water management to fund the repairs.
Bob Smith from the Piney Woods neighborhood thanked the city for its efforts to find the source of the problem.