719.1 General Description
This specification provides the requirements for furnishing and installing a silt filter bag to trap dissolved silt when pumping accumulated water from sediment basins or other areas where water may accumulate.
719.1.01 Definitions
General Provisions 101 through 150.
719.1.02 Related References
A. Standard Specifications General Provisions 101 through 150. B. Referenced Documents ASTM D 3776 ASTM D 4632 ASTM D 4833 ASTM D 4491 ASTM D 3786 ASTM D 4991 ASTM D 4355 ASTM D 4751 ASTM D 4884
719.1.03 Submittals
General Provisions 101 through 150.
719.2 Materials
Ensure that all materials meet the requirements of the following: A. Fabric The silt filter bag fabric shall be a non-woven geotextile conforming to the following properties: Property Minimum Value Test Method Weight 10 oz./yd2 (340 g/m2) ASTM D 3776 Tensile strength (minimum average of 5 specimens) 270 lb. (1100 N) ASTM D 4632 Puncture Resistance, 150 lb. (730 N) ASTM D 4833 Initial Flowrate 70 gal/min-ft.2 (3500 L/min- m2) ASTM D 4491 Bursting Strength 550 psi (3800 kPa) ASTM D 3786 Permitivity 1.3 sec-1 ASTM D 4991 UV Stability, 70% of initial Tensile Strength 173 lb. (770 N) ASTM D 4355 AOS Retained 100% ASTM D 4751 B. Seams All seams shall be sewn with a double needle machine using a high strength thread. The seams shall have a minimum average wide-width strength of 100 lb./in (17.5 N/mm) when tested according to ASTM D 4884. C. Opening Provide a silt filter bag with an opening to accommodate a 6 in. (150 mm) hose.
719.2.01 Delivery, Storage, and Handling
General Provisions 101 through 150.
719.3 Construction Requirements
719.3.01 Personnel
General Provisions 101 through 150.
719.3.02 Equipment
General Provisions 101 through 150.
719.3.03 Preparation
General Provisions 101 through 150.
719.3.04 Fabrication
General Provisions 101 through 150.
719.3.05 Construction
1. Place the silt filter bag on a #57 stone gravel bed sloped to ensure that the filtered water will exit at the desired location. Chose the exit location to prevent erosion. 2. Extend the pump hose past the inlet opening to ensure that the silt-laden water will discharge in the center of the bag. Ensure that the seal between the inlet and hose is watertight. 3. When the filter bag is full of silt and cannot readily pass any more water, use a new filter bag. If approved by the Engineer, bury the full filter bag on site or remove the top section of fabric and seed the exposed filtrate. The size and number of silt filter bags will be shown on the plans or determined by the Engineer.
719.3.06 Quality Acceptance
General Provisions 101 through 150.
719.3.07 Contractor Warranty and Maintenance
Continue water filtration as directed by the Engineer.
719.4 Measurement
Silt filter bags measured for payment will be the actual number of bags used for filtration, complete and accepted.
719.4.01 Limits
General Provisions 101 through 150.
719.5 Payment
Payment will be made under: Item No. 719. Silt filter bag Per each
719.5.01 Adjustments
General Provisions 101 through 150.
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