245Silt Dike

245.01 Description . This work consists of furnis hing, installing, maintaining and

removing temporary silt dikes. Silt dikes shall be used for velocity reduction of stormwater run-off. Silt dikes shall be considered to have “minimal” capabilities for sediment filtration of stormw ater run-off. With the ex ception of placement along the ends and edges of a construction bridge across a Water of the U.S., silt dikes shall not be used as a discharge structure or the last sediment control item in a “BMP train” prior to stormwater discharge off Department Right-of-Way or into Waters of the U.S.

245.02 Materials. Silt dikes shall have a dike height of at least nine inches (9”) in the

center. The outer cover shall be a woven ge otextile fabric placed around the inner plane and allowed to extend beyond at least one side of the device for a minimum of two feet (2’) to form an apron. The device may also have aprons on both sides, each of which shall extend from the device a minimum of two feet (2’). In the event that the silt dike has an apron extending from only one side, geotextile fabric shall be placed under the silt dike as shown on the standard drawing. Silt dikes shall rebound to their originally installed height when driven over by vehicles or equipment. Silt dikes shall not be damaged when driven over by vehicles or equipment. The silt dike shall also be one listed on the Department’s APL.

245.03 Construction Requirements. The flexibility of the materials in silt dikes allows

them to conform to various channel configurations. The dikes shall be attached to the ground with wire staples. The staples shall be No. 11 gauge wire and be at least six inches long. As a minimum, the staples shall be placed as recommended by the manufacture. Prior to placement of the silt dikes, the Cont ractor shall make sure the surface on which the dike is to be placed is flat. The silt di kes shall be placed in ditch, keeping excess fabric extended up and downstream of the dam. Excess material shall be trenched into the ground on the upstream end and stapled on the downstream end. A minimum 6-inch overlap between end sections shall be required should the width require multiple silt dikes to be installed. The overlapped end se ctions shall be connected with wire wraps or staples every 12 inches on center. The dike aprons shall be entren ched at the upstream side and anchored to the ground at downstream end using staples. This device can be used on surfaces that do not allow for trenching by securing the aprons with sand or gravel bags or other manner as described by the manufacturer. The device can be easily removed for maintenance and is considered to be reusable. Silt dikes which do not rebound to their originally install height or become damaged shall be removed, disposed of, and replaced by the Contractor at no additional expense to the Department. The Contractor shall be required to remove and dispose of all sediment that is accumulated adjacent to the dike.

245.04 Method of Measurement. Silt dike will be measured by the linear foot.

245.05 Basis of Payment. Silt dike, measured as prescribed above, will be paid for by

the linear foot, which price shall be full compensation for all cost of equipment, labor, materials, installation, cleaning and removal, and all incidentals necessary to complete the work. Payment will be made under: 245-A: Silt Dike - per linear foot SECTION 246 - SANDBAGS AND ROCKBAGS

246.01 Description . This item of work shall consist of the furnishing, installing, and

maintaining sandbags and rockbags for the purpose of temporary erosion control by intercepting and slowing the flow of sediment-laden runoff water, or for use as a temporary dam.

246.02 Materials. The filler material for sandbags shall consist of a fine aggregate

meeting the requirements of Subsection 703.02. The filler material for rockbags shall consist of a size 57 aggregate meeting the requirements of Subsection 703.03. The bag material shall be woven polypropylene, polyethylene or polyamide fabric with a minimum unit weight of four (4) ounces per square yard. The bags shall be a minimum of 21 inches in length, 12 inches in width, and four (4) in thickness when filled.

246.03 Construction Requirements. Sandbags and rockbags shall be used to construct

a berm/dam that will intercept sediment-laden storm water runoff from disturbed areas, create a retention pond, detain sediment, and re lease water in sheet flow. Sand or rock shall be placed in the bag so that at least the top six (6) inches of the bag is unfilled to allow for proper tying of the open end. Any subsequent rows of bags shall be offset one-half the length of the preceding row to provide a layered brick-type arrangement. The sandbag and rockbag berm/dam installation shall be maintained in good condition by the Contractor. All necessary work and materials to maintain the integrity of the installation shall be provided until earthwork construction is complete and permanent erosion-control features are in place. The maintenance of the bags will not be paid for separately and will be included in the cost for sandbags or rockbags.

246.04 Method of Measurement. Sandbags and rockbags will be measured per linear

foot or each. Sandbags and rockbags measured by the linear foot shall be in accordance with the details in the erosion control drawing. The length of the sandbag or rockbag berm/dam