Progress on Tar Balls
Congaree Riverkeeper spent time on the water today, with a crew hired by SCE&G, to take core samples in the river. You may have seen the little pontoon boat out on the water below Gervais Street Bridge. The crew has sampled about a hundred points to identify the extent of the plume of tar that came out of the creek. At this point that plume is pretty well identified and extends approximately100' out into the river and about 1,600' down river. Bottom sediment at some points is nonexistent and may be 12' deep in others. But the thick spots are anomalies. The thickness of the sediment throughout the area averages about a foot. That's good news, because it means the tar is contained in a relatively small area.
The pontoon boat is fitted with a hydraulic press, which can push the core pipe into the sediment and pull it out. The core tube, at the lower end of the pipe, is lined with a plastic sleeve. The sleeve can be removed to save the core sample. A simple round bit, on the lower end, is pushed into the sediment. Core samples were taken 50’ to 100’ apart. As many as three samples may be taken at any one spot to assure accuracy. Black nodules in the core indicate TML (tar like material). If in doubt, smell the material in the core tube and you will know if tar is present.
It has taken a long time for SCE&G to get this far, but it is a complicated process to work out. Personally, I’d like them to take a thorough, long-time to complete these tests than a cursory, short-time. Once this testing is completed, SCE&G and DHEC plan to hold public meetings to explain the findings. At that time, all their findings will be made public.
Map of area to be surveyed
Core pipe, plastic tube, stopper and bit
Pneumatic drill / tamper aboard core boat