MICHELLE GERRITS EROSION & SEDIMENT CONTROL SPECIALIST WISDOT Dewatering Technical Standard

SANITARY AND STORM SEWER LOCATIONS POTENTIAL CONTAMINATION SOIL TEXTURE DEPTH TO GROUND WATER KARST FEATURES DISCHARGE OUTFALL LOCATIONS TOPOGRAPHY & GROUND COVER CONDITION DISTANCE & CONVEYANCE TO RECEIVING WATERS What do you need to know before dewatering?

REUSE AS DUST CONTROL ONSITE INFILTRATION TRANSPORT TO SANITARY /TREATMENT FACILITY GEOTEXTILE BAGS GRAVITY BASED SETTLING SYSTEMS PASSIVE FILTRATION SYSTEMS PRESSURIZE FILTRATION SYSTEMS POLYMER ADDITION What are your dewatering options?

Geotextile Bags Type I & Type II Sized by soil particle size, pumping rate & 50% clogging factor

Gravity based settling >Portable Sediment Tank >Sediment Trap or Basin >Wet Detention Basin Rely on gravity settling as primary method, require quiescent conditions

Passive filtration >Manufactured Filters >Portable Filter Tank >Filter Basin >Vegetative Filter Relies on filtration as primary method

Pressurized filtration >Portable Sand Filter >Wound Cartridge Units >Membranes and Micro-filtration Pressurized systems force water through a media designed to handle higher flow rates and typically have automatic backwash systems. Most efficient at removing fine sediment.

FLOW CHART SOIL TEXTURE DEWATERING MATRIX How do you chose the right BMP for your situation?

Need to know 3 Basic Soil Textures Clayey - Fine to very fine particles >Snake Silty - Medium to fine particles >Binds Sandy - Coarse to medium particle >Falls apart

USE A FLOATING SUCTION HOSE PREVENT EROSION AT THE OUTFALL INFILTRATE WHEN PRACTICAL POLYMER USE INCREASES EFFICIENCY REMOVE ACCUMULATED SEDIMENT COMBINATION OF PRACTICES MAY BE NEEDED Key issues to remember when dewatering