|
|
|
To Print Use The pdf File
ILLINOIS URBAN MANUAL
PRACTICE STANDARD
PORTABLE SEDIMENT TANK
(no.)
CODE 895
(Source: Kane-Dupage Soil and Water Conservation District)
DEFINITION
A compartmented container through which sediment-laden water is pumped to trap and retain the sediment.
PURPOSE
The purpose of this practice is to trap and retain sediment prior to pumping the water to drainageways, adjoining properties, and rights-of-way below the sediment tank site.
CONDITIONS WHERE PRACTICE APPLIES
A sediment tank is to be used on sites where excavations are deep and space is limited, such as urban construction, where direct discharge of sediment-laden water to stream and storm drainage systems is to be avoided. Also it is used where an excavation extends below the seasonal high water table causing a sump pump to be used.
CRITERIA
The portable sediment tank will be constructed with three equal baffled compartments. The inlet and outlet pipe will be a minimum diameter of 3 inches. The minimum storage volume of the tank shall be in cubic feet, calculated by multiplying 32 times the pump discharge in gallons per minute (GPM).
CONSIDERATIONS
The sediment tank should be located for ease of clean out and disposal of the trapped sediment, and to minimize the interference with construction activities and pedestrian traffic.
Portable sediment tanks should only be used when other sediment trapping practices cannot be installed due to lack of space or other reasons. This is due to their lack of efficiency and high labor requirements to remove the sediment.
PLANS AND SPECIFICATIONS
Plans and specifications for installing portable sediment tanks shall be in keeping with this standard and shall describe the requirements for applying the practice. The specifications will show the required storage volume of the tank.
All plans shall include installation, inspection, and maintenance schedules with the responsible party identified.
Standard drawing IL-595 PORTABLE SEDIMENT TANK PLAN may be used as the plan sheet. Other container designs can be used if the storage volume is adequate and approval is obtained from the local approving agency.
OPERATION AND MAINTENANCE
The tank shall be cleaned out when one-third of the storage volume is filled with sediment. All sediment collected in the tank shall be disposed of in an approved sediment trapping device such as practice standard TEMPORARY SEDIMENT TRAP 960 or IMPOUNDMENT STRUCTURE-ROUTED 842 or on the construction site or as approved by the engineer/inspector.
NRCS IL March 1994
