16-15 1634 -3 Construction Methods
Install coir fiber baffles on the upstream side of each type of dam in accordance with Section 1640 and as directed by the Engineer .
A.Type A Place structural stone in the channel, ditch diversion, swale or drainage turnouts with 2:1 side slope on the upstream side and 3:1 side slope on the downstream side. Plate the upstream side with sediment control stone approximately 12 inches thick. Use a minimum spacing of 15 f eet and as directed by the Engineer for the coir fiber baffles. Provide a weir section approximately 2/3 of the channel width and with an 8 f oot maximum height from the bottom of the channel. In the center of the device, place the weir section approximately 12 inches lower than the sides of the device or the top of the channel, whichever is lower.
B.Type B Place structural stone in the channel, ditch diversion, swale or drainage turnouts with 2:1 side slopes and plate the upstream side with sediment control stone approximately 12 inches thick. In the center of the device, provide a weir section with a 4 f oot minimum width constructed 12 inches lower than the sides of the device or the top of the channel, whichever is lower. Construct the temporary rock sediment dam Type B with a 5 f oot minimum thickness measured along the top of the dam structure. Use earthen backfill material to extend dam width and create a larger sediment storage volume for the temporary rock sediment dam T ype B where needed. 1634 -4 MAINTENANCE AND REMOVAL Maintain the temporary rock sediment dams, remove and dispose of silt accumulations at the sediment dams when so directed by the Engineer . Remove temporary rock sediment dams as the project nears completion, or at such time as the Engineer deems the device to be no longer useful. The Engineer will direct the actual time of removal. Prepare seed bed, seed and mulch the area in accordance with Section 1660. 1634 -5 MEASUREMENT AND PAYMENT Payment for temporary rock sediment dams will be made as follows: Coir Fiber Baffle with be measured and paid in a ccordance with Article 1640- 4. Stone for Erosion Control, Class ____ will be measured and paid in accordance with
Article 1610 — 4.
Sediment Control Stone will be measured and paid in accordance with Article 1610- 4. Silt Excavation will be measured and paid in accordance with Article 1630- 3. 1635 -1 DESCRIPTION Construct, maintain and remove devices placed around outside perimeters of pipe structures, to reduce water velocity and trap sediment. The conditions which occur during the construction of the project will determine the quantity of temporary rock pipe inlet sediment traps to be constructed. The quantity of inlet sediment traps may be increased, decreased or eliminated entirely as directed by the Engineer . Such variations in quantity will not be considered as alterations in the details of construction or a
Source: North Carolina Standard Specifications for Roads and Structures, 2024 Edition. Pages 765–765 of 857.