Erosion and Sediment Control
30 Minute Presentation
Low Impact Development (LID) is a new design philosophy made up of four key principles. The first is to conserve natural areas whenever possible. Second, design to minimize the development’s impact on hydrology. Next is design to reduce the velocity of the runoff at the point of impact, maintain the runoff rate and retain the stormwater on site. Finally, design to integrate microscale controls that infiltrate, evaporate, store and / or manage runoff close to the source.
Conserving natural areas points to leaving more area undisturbed. It can also mean improving existing areas that may already be experiencing some natural erosion control problems. Rolled erosion control products, hydraulic mulches and open weave textiles can all help you accomplish this. Coir logs can be used to help shorelines and stream banks from further erosion.
Minimizing impact on hydrology can be done a few ways. The best way is to avoid altering the existing drainage basins, but we all know that isn’t always practical. Another is to keep the amount of impervious area to a minimum. Turf reinforcement mats (TRMS) can often be used in place of hard armoring solutions. TRMs result in stronger, natural vegetation and are more cost effective than traditional hard armoring like rip rap or concrete liners.
Sediment fiber rolls can be instrumental in reducing velocity by acting as slope interceptors on a long slope. Open weave textiles and rolled erosion control products can be used as part of a bioswale or rain garden to help maintain the runoff rate and stormwater retention. Many producers now have biodegrable and organic options for these products
Designing to integrate microscale controls that infiltrate, evaporate, store and/ or manage runoff close to the source is really a summation of the 3 previous steps. If you are doing all you can to conserve natural areas, you are managing runoff close to the source. If you are making efforts to keep the drainage basins the same, you most likely can’t do a traditional “end of pipe” stormwater management plan. You will need to use several microscale controls to meet the requirements. Reducing the velocity and storage will encourage evaporation and infiltration.
This presentation will explain the basic principles of Low Impact Design and ways we can use different erosion control solutions to achieve the principles. It will help designers see the project beyond their permit and add some tools into their firm’s toolbox.