Evaluation of the Current Effectiveness of Dewatering Bags and Potential Improvements

Dewatering bags are commonly used on Virginia Department of Transportation (VDOT) construction sites as an alternative to sedimentation basins for the treatment of dredged material. Visual observations have indicated that in some instances, fines can be released from these bags, increasing the turbidity of the receiving water. Due to the prevalence of protected aquatic species in Virginia, concerns have been raised regarding the use of these bags as well as the standards used to select them. The purpose of this research effort is to evaluate the effectiveness of dewatering bags currently on VDOT’s approved products list at removing fine silts and clays from sediment-laden water. The results of this evaluation will be used to assess the efficacy of VDOT's current specifications for dewatering bags. If needed, modifications to these specifications will be recommended. Additionally, methods of increasing the effectiveness of these bag will also be investigated.