By Blake Greene
In 2010 approximately 35,000 square feet of additions and 80,000 square feet of renovations were made to the existing RC Edwards Middle School located in Central, SC, adjacent to Hartwell Lake off of Highway 123 near Clemson University.
The construction site was relatively standard and didn’t appear to have any unusual storm water runoff concerns. But after an unusually heavy rain event lasting several days, the sediment ponds overflowed and stormwater runoff began rushing off the site.
The silt fence that was in place helped with some of the run-off but the area was still flooded with red clay-laden water, which ended up in a culvert that flowed to a nearby stream. The workers were forced to shut down the site until they could dewater the sediment pond.
This posed a problem for the contractor because dewatering highly turbid water was not allowed. The contractor opted for a dewatering solution from StormKlear.
|The TerraTex filter bag is equipped with a sleeve specifically designed to slide over Schedule 40 PVC pipe.|
The situation was challenging. To avoid a buildup of water pressure that would have overpowered the silt fence and sent red sediment-laced stormwater rushing off the site, dewatering had to take place outside the silt fence barrier.
Setting up the System
The StormKlear DPS dewatering system was deployed with segmented geosynthetic socks filled with flocculant. The socks were installed in a 6" dual-chambered Schedule 40 PVC manifold. The DBP-2100 sock was installed in the first chamber, and a GelFloc sock in the second. The discharge hose was then routed to a 10' x 15' TerraTex N08 filterbag.
A 4" Schedule 40 PVC was connected to the manifold system which housed the socks. The system was then connected to a 100-foot hose attached to a 3" trash pump, which was used to pump the dirty water out of the sediment pond. The filter bag is equipped with a sleeve specifically designed to slide over PVC pipe so the 4" PVC fits right inside the dewatering filter bag.
|With a 100-foot hose attached to the system, the contractor was able to discharge directly off site.|
At the time of initial setup of the system, influent was registering at 687 NTUs. But after deploying the manifold system in conjunction with the dewatering bag, the discharge was registering at 31.8 NTUs — well within the standard for the county and the state of South Carolina. As a result, the contractor was approved to discharge directly off site. In order to do that, an extra long, 100-foot hose was required.
|The silt fence helped with some of the run-off but flooding still occurred.|
Owing to its small footprint, the system can be stored on-site at all times. It’s also easy to break down and set up. For the contractor, this means inventorying a single solution that can be taken from job to job.
The biopolymer sock works on all soil types, eliminating the need to send off soil samples to figure out which product to use. It also eliminates work stoppages and waiting on soil analysis results.
Contractors know they need to dewater but many miss the opportunity to clean the water while they are at it. With this type of system, it can be a standard best management practice with little incremental expense for the owner.
StormKlear, located in Bothell, WA, offers products for stormwater treatment and dewatering from construction sites, ensuring clean, safe and healthy water sources while allowing contractors to meet local and state agency requirements, and remain productive throughout the year.
About the Author: Blake Greene is Branch Manager with Hanes Geo Components in Lawrenceville, GA, and has been in the Erosion Control industry for the past six years. He has a degree in Landscape Contracting and Management from Mississippi State University and has been able to incorporate his academic training in soil science into practical applications by using polymers and other erosion products to control sediment.