Chemical Treatments for Erosion and Turbidity Control: A Review

We all strive to reduce erosion and to discharge the best quality water we can from construction sites. There has been a fair amount of research on the use of chemical treatments to enhance erosion control and to help reduce turbidity in construction site runoff. For erosion control, most of the focus has been on polyacrylamide, but there are other chemicals which have been tested, either as a stand-alone product or to augment traditional products such as straw, erosion control blankets, and hydromulch. The results have been highly variable, but generally the treatments have been successful in reducing erosion when combined with a physical erosion control system. There have been fewer research studies on the use of chemical treatments to reduce runoff turbidity, although there have been many case studies presented. The lower cost approach, using passive treatment or simple gravity flow through a dosing area, has been demonstrated to work but it is highly sensitive to the conditions present. A more traditional, engineered approach using pumps and dosing systems, has been very successful when the project can absorb the costs. One of the major concerns with chemical treatments is the potential for environmental toxicity, since a chemical is being introduced into the runoff water, which will eventually be discharged. The risks and benefits will be discussed in detail so that participants can understand and explain these to clients and regulators in order to gain approval for chemical treatments where needed. The presentation will involve as much audience participation as possible in order to maximize the learning experience for everyone.