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ITEM 767.12
COMPOST FILTER TUBES The purpose of this item is to provide embankment of organic material, to be placed in the path of storm water flows for the purpose of filtering a substantial portion of the suspended sediments from the flow. This item shall conform to the requirements of Section 767 of the Standard Specifications, Special Condition Number 25 of the Order of Conditions and the following: The filter tubes exterior shall be 100% organic hessian fabric (burlap) that will become incorporated with the organic interior material. Organic matter content shall be between 20 -100% (dry weight basis) as determined by ASTM D2974 (method A) Standard Test Methods for Moisture, Ash, and Organic Matter of Peat and Other Organic Soils. Moisture content shall be <150% by dry weight (<60% by wet weight) as measured by ASTM D2216 Standard Test Method for Laboratory Determination of Water Content of Soil and Rock and ASTM D2974 (cited above). Particle size is measured by sieving shall be as follows: Sieve Size % Passing 75mm 100% 19mm 70-100% #4 30- 75% #20 20-40% No particle may be longer than 150mm Soluble salts shall be <5.0 mmhos/cm (dS/m) The pH shall be between 5.5 and 8.0 Tubes for compost shall be burlap or approved biodegradable material. MAINTENANCE: The Contractor shall maintain the filter tubes in a functional condition at all times, including inspections after each rainfall and at least daily during prolonged rainfall. The Contractor shall immediately correct all deficiencies, such as overtopping, clogging with sediment, erosion or otherwise becoming ineffective. The contractor shall make a daily review of the location of the berm in areas where construction activity causes drainage runoff to ensure that the tube is properly located for effectiveness. Where deficiencies exist, such as overtopping or wash-out, additional mulch material shall be installed as approved or directed by the Engineer. Contractor shall remove sediment deposits as necessary to maintain the filters in working condition. REMOVAL: At the direction of the Engineer, the Contractor shall rake out filter berms so that filter material is no greater than 3" in depth on soil substrate. Typically filter berms shall be removed at the same time as conventional erosion control materials, such as filter berms and silt fence will be removed. If filter has been wrapped in fabric or fabric bags, all bag material shall be cut and removed and disposed of off-site by the Contractor, at no additional cost to the project. Filter material shall be raked out per previous paragraph. COMPENSATION: Measurement for this item shall be by the foot installed, approved, and maintained in place. Payment shall be the bid price per foot and shall be compensation for all labor, materials, and incidentals necessary to complete the work specified above. |
P.O. Box 737
Wrentham, MA 02093
508-384-7140 · Fax
508-384-0571
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