ILLINOIS URBAN MANUAL PRACTICE STANDARD COFFERDAM no - PDF document

ILLINOIS URBAN MANUAL CODE 803 Source: Kane-DuPage Soil and Water Conservation District The purpose of this practice is to waterway or body of water while impoundment). Cofferdams may also be utilized in in otherwise unsuitTypical activities requiring the use of stabilization of a water body; culvert, bridge, pier, or abutment; open-cutting for the installation of utilities; and strflow of water in a linear waterway and partial cofferdam will refer to a For situations in waterways where a CHANNEL 676PD TEMPORARY STREAM may sheet pile cofferdam. Cofferdams designed utilizing this standard may necessitate review by an Illinois licensed engineer, depending on the wing authority. maintain cofferdams shall be non-such as grout, shall be non-toxic, equipment that Stationary equipment such as equipment shall be stored outside of avoid inundation during a high water The term “low-flow conditions” used within this standard refers to flow at mark (OHWM). The OHWM refers to fluctuations in water levels. To avoid a linear water feature shall be temporary periods of low- or no-flow conditions. Scheduling shall also impacts on fish and other aquatic Disturbance or removal of vegetation necessary to complete operations. Disturbed areas shall be stabilized Excavated material or spoils resulting from the activity shall be should be restored following the partial cofferdam is to maintain stream activities, all appropriate soil measures shall be properly installed. equipment must access the work causeway must be constructed. Following cofferdam installation, the standards DEWATERING 813 and SUMP PIT 950 may be utilized in shall be filtered toincrease in suspended solids or all applicable local, regulations, whichever is most to accept flows, as determined by The downstream cofferdam shall be Design the 2-year peak elevation, unless If waterway information is not available, the ordinary high water indicator. maintained at a rate similar to used in situations where there is a variations in the base elevation will full and partial cofferdam situations. be constructed in accordance with specific sizing, installation allowable flow velocities and other used in situations where there is a relatively flat base material. Large variations in the base elevation will full and partial cofferdam situations. specific sizing, installation allowable flow velocities and other Barrier used in partial cofferdam situations extend out past the edge of the the barrier is pulled over the rip rap, it will likely be necessary to hold the cofferdam is able to withstand design Steel sheet cofferdams are different Steel sheet cofferdams are Steel sheet cofferdams should not Steel sheet shall be driven into the avoid undercutting. Steel sheets Impermeable Barrier Material The impermeable barrier used in this standard should consist of one of the 1) rubber liner with a thickness necessary to affix material 2) polypropylene liner with a necessary to weld pieces 3) polyvinyl chloride (PVC) liner A solvent weld is necessary to affix material into larger CONSIDERATIONS This standard describes four typical similar cofferdam types. As an Resources and Illinois Environmental Protection Agency. Additional requirements may apply in threatened or endangered species Prior to the installation or removal of a cofferdam, a SILT CURTAIN 917 should never be placed across should be placed parallel to flow or the installation of the cofferdam. The use of sandbags as a seal for be placed within the cofferdam when utilized for this purpose. on the individual site conditions and designed by an engineer and PLANS AND SPECIFICATIONS cofferdams shall be in keeping with 1) The location of the cofferdam 2) Cofferdam type 3) Normal water elevation 4) Installation, inspection, and 5) The 2-year peak flow and elevation values Frame Cofferdam, IUM-503AP – A-503BF – Bladder Cofferdam, IUM-OPERATION AND MAINTENANCE monitored daily and must not be left shall be stabilized in preparation as damage to the installation. made to retain the existing soil and stabilized with an appropriate erosion control blanket and the construction conditions. Stabilization of all remaining disturbed areas shall rdams. In no REFERENCES Division of Water Pollution Control. Tennessee Erosion and Sediment – Division of Soil & Water