Silty soils and muddy runoff at middle school construction site draw attention of DEP and town

By Susan Mustapich | Dec 04, 2018
Courtesy of: Town of Camden Heavy rains this fall caused erosion-control systems at the Camden Rockport Middle School construction site to fail.

CAMDEN — The Department of Environmental Protection has issued a notice of violation after heavy rains carried soil from the middle school construction site into the Megunticook River on multiple occasions, a problem construction officials say has been addressed.

The Camden Rockport Middle School is on Knowlton Street. The new school under construction is behind the existing buildings, and the river and wetlands wind around the back of the school property.

As of Dec. 3, reinforced drainage structures are working, and emitting clear water, according to Ledgewood Construction Project Manager Peter Reynolds and Project Field Superintendent Steve Claffie.

Ledgewood, the company building the new school, has been improving erosion control structures for the past few weeks, in order to to filter soil out of the runoff, according to Reynolds. Since Nov. 27, the improvement work has continued through the weekends.

SAD 28 Superintendent Maria Libby asserted Dec. 3 that the school district is "making every effort to make sure we don't have sediment running into the river."  The district takes the issue very seriously, and is working to eliminate the problem, she said.

Camden Planning and Development Director Jeremy Martin said his concerns began in September, after nearly 5 inches of rain fell in a 24-hour period and overburdened the erosion-control systems on the site, resulting in soil discharges into the river. He acknowledged that was a lot of rain for one day, and engineers generally do not design for that type of event.

He said the soil on the site, a mix of marine clay and silt, increases the problem. Other types of soil will settle to the bottom when mixed with water, but silt remains suspended in water much longer, he explained. This makes it harder to separate silty clay soil from water using systems such as sediment ponds and filters.

Martin, who oversees the local permitting process, is most concerned that exposed soil on the construction site be stabilized for the onset of the winter freeze-and-thaw cycle and spring runoff. The construction company and school district are "going to have to be on top of this the whole time, until the project is done," he said Dec. 3.

David Madore, DEP deputy commissioner and communications director, explained in a Dec. 3 email that "staff was onsite last week and the department has been in communication with the superintendent, town officials and contractors." He said the notice of violation was issued Nov. 30 to SAD 28, Ledgewood and Jake Barbour Inc.

DEP staff visited the construction site Nov. 27, and noticed soil discharge into the Megunticook River and an adjacent fresh water wetland, according to the NOV. DEP staff determined the erosion and sedimentation control plan was not adequately followed in order to "prevent an unreasonable amount of erosion and sedimentation from occurring." This violates the SAD 28 stormwater management permit, as well as state sedimentation and erosion control and water protection laws, according to the notice.

Libby described the construction project as facing difficult challenges, including the amount of clay that had to be dug out and removed from the site, and the rain, which overwhelmed the erosion control strategies in place. She pointed out that all along, there have been water collection systems, fencing, mulch and other erosion-control measures. Ledgewood Construction and its subcontractor, JBI, have been operating erosion-control and drainage systems to keep excavated soil from getting into the river. But it hasn't been enough because of the heavy rains and the type of soil, she said.

Reynolds said the erosion-control structures were built for the average rainfall, which is typically around 4 inches in October.

Rainfall this September was 8.07 inches, in October, it was 7.31 inches and in November, 10.58 inches, according to data collected by the Camden Wastewater Department.

Excavation work uncovered three times more soil that had to be removed from the site than expected, Reynolds said. The company estimated it would have to haul 500 yards of soil off the site, but because of the clay in the soil, it ended up having to haul off 1,500 yards of soil, because it was unsuitable for the site.

While the first order of business was to get that material off the site, multiple rain storms throughout October increased the difficulty of removing it, he said.

The best practice is to let excavated soil dry before moving it, so the company piled the soil up waiting for it to dry, he said. Instead, it became wetter and wetter. While the soil had to be removed, the timing was made more difficult by the rain. In removing the soil, when it rains, there's a fine line between helping and hurting the situation, according to Reynolds. The excavated soil was removed by the end of October, he said.

Recent improvements at the construction site include a new spillway to channel water and filter sediment along the way; a newly installed heavy layer of bark mulch over cleared open areas to reduce surface water migration; improved erosion-control sediment traps, berms and filter fencing in the low point at the back of the property, where water had concentrated; new sediment ponds, and a layer of bark mulch covering filter fabric, located next to the stone berm approximately 30 feet from the edge of the site. Erosion-control mechanisms now span the entire distance to the fence, and more than 200 imported bales of hay brought to the site Dec. 1 cover stockpiles of soil.

 

Claffie described the site as containing two drainage systems, one to the south of the site, where the ballfields are located, and the other to the north of the site, closer to the Knowlton and Washington street side of the property. By Dec. 2, both were emitting clear water, he said.

Major work to improve erosion-control systems is now producing clear water at the Camden Rockport Middle School construction site. (Photo by: Steve Claffie, Ledgewood Construction)
The newly installed heavy layer of bark mulch over cleared open areas reduces surface water migration at the Camden Rockport Middle School construction site. (Photo by: Steve Claffie, Ledgewood Construction)
Erosion control improvements include a new layer of bark mulch covering filter fabric next to a stone berm located approximately 30 feet from edge of the middle school construction site. (Photo by: Steve Claffie, Ledgewood Construction)
Newly improved erosion control sediment traps, berms and filter fence are located towards the back fields, where water had concentrated on the middle school construction site. (Photo by: Steve Claffie, Ledgewood Construction)
Comments (1)
Posted by: Richard McKusic, Sr. | Dec 04, 2018 16:14

Camden  seems quick to mitigate any problems that come up. That takes goo teamwork among all parties, Kudos.



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