16-22 (E) Attachment Device
Provide plastic ties, wire fasteners or other approved attachment d evice. 1640 -3 CONSTRUCTION METHODS Place the coir fiber baffles immediately upon construction of sediment dams and basins. Install 3 baffles in basins with a spacing of 1/4 the basin length and according to the detail sheets. Install 2 coir fiber baffles in basins less than 20 f eet in length with a spacing of 1/3 the basin length. Place s teel posts at a depth of 2 f eet below the basin surface, with spacing of no more than 4 feet. The top height of the coir fiber baffles shall not be below the elevation of the emergency spillway base of dams and basins. Attach a 9 -gauge high -tension wire strand to the steel posts at a height of 3 f eet with plastic ties or wire fasteners. Install a steel post into side of the basin at a variable depth and a height of 3 f eet from the bottom of the basin to anchor coir fiber mat. Secure anchor post to the upright steel post in basin wit h wire fasteners. Drape t he coir fiber mat over the wire strand with at least 3 feet of material on each side of the strand. Secure the coir fiber mat to the posts and wire strand with approved fastener . Place staples across the matting at ends and junct ions approximately one foot apart at the bottom and side slopes of basin. Overlap matting at least 6 inches where 2 or more widths of matting are installed side by side. Refer to details in the plans. The Engineer may require adjustments in the stapling requirements to fit individual site conditions. 1640 -4 MEASUREMENT AND PAYMENT Coir Fiber Baffle will be measured and paid as the actual number of linear feet of coir fiber baffle s which are installed and accepted. Such price and payment will be full compensation for all work covered by this section, including, but not limited to, furnishing all materials, labor, equipment and incidentals necessary to install the coir fiber baffles. Payment will be made under: Pay Item Pay Unit Coir Fiber Baffle Linear Foot 1642 -1 DESCRIPTION Work includes furnishing materials, installation of wattles, matting installation, maintenance and removing wattles. Install wattles as shown in the plans or as directed by the Engineer to intercept runoff, act as a velocity break and contain sediment. The actual conditions which occur during the construction of the project will determine the quantity of wattles constructed. The quantity of wattles may be increased, decr eased 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 change in the character of the work . 1642 -2 MATERIALS Refer to Division 10. Item Section Matting for Erosion Control 1060-8 Staples 1060-8(D)
16-23 (A) Stakes
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 sectio n approximately 2/3 of the channel width and with an 8 foo t 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.Wattle Excelsior Wattles shall meet Table 1642-1. TABLE 1642 -1 100% CURLED WOOD (EXCELSIOR) FIBERS Property Property Value Minimum Diameter 12 inches Minimum Density 2.5 pcf +/- 10% Net Material Synthetic Net Openings 1 inch x 1 inch Net Configuration Totally Encased Minimum Weight 20 lb +/ - 10% per 10 foot length Coir Fiber Wattles shall meet Table 1642-2. TABLE 1642 -2 100% COIR (COCONUT) FIBERS Property Property Value Minimum Diameter 12 inches Minimum Density 3.5 pcf +/ - 10% Net Material Coir Fiber Net Openings 2 inch x 2 inch Net Strength 90 lb Minimum Weight 2.6 pcf +/ - 10%
C.Flocculant Flocculant shall be applied in powder form and shall be anionic or neutrally charged. Soil samples shall be obtained in areas where the wattles will be placed, and from offsite material used to construct the roadway, and analyzed for the appropriate flocculant to be utilized with each wattle. The flocculant product used shall be listed on the North Carolina Department of Environmental Quality Division of Water Resources website as an approved flocculant product for use in North Carolina .
1642-3 Construction Methods
A.Wattle Check Wattles shall be excelsior or coir fiber as shown in the plans. Wattles shall be secured to the soil by wire staples approximately every 1 linear foot and at the end of each section of wattle. A minimum of 4 stakes shall be installed on the downstream side of the wattle with a maximum spacing of 2 linear feet along the wattle. Install a minimum of 2 stakes on the upstream side of the wattle. Stakes shall be driven into the ground a minimum of 10 inches with no more than 2 inches projecting from the top of the wattle. Drive stakes at an angle to wedge wattles to the bottom of the ditch. Only install wattle (s) to a height in ditch so flow will not wash around wattle and scour ditch slopes and as directed. Overlap adjoining sections of wattles a minimum of 12
16-24 inches.
Installation of matting shall be in accordance with the plans, and in accordance with
Article 1631 — 3.
Only apply flocculant on wattles per plans and as directed by the Engineer. When required, flocculant shall be applied over the lower center portion of the wattle where the water is going to flow over at a rate of 2 oz per wattle, and 1 o z of flocculant on matting on each side of the wattle. Flocculant applications shall be done during construction activities after every rainfall event that is equal to or exceeds 0.50 inches . Do not apply flocculent to a wattle that serves as a stormwater disch arge outfall .
B.Silt Fence Wattle Break Construct silt fence wattle breaks using excelsior or coir fiber wattles in conjunction with temporary silt fence as shown on the plans or as directed by the Engineer. Excavate a trench the entire length of each wattle with a depth of 1 inch to 2 inches for the wattle to be placed. Secure silt fence wattle breaks to the soil by wire staples approximately every linear foot and at the end of each wattle. Install at least 4 stakes on the downslope side of the wattl e with a maximum spacing of 2 linear feet. Install at least 2 stakes on the upslope side of the silt fence wattle break. Drive stakes into the ground at least 10 inches with no more than 2 inches projecting from the top of the wattle. Drive stakes at an angle to wedge wattles to the bottom of the trench. Install temporary silt fence in accordance with Section 1605 and overlap each downslope side of silt fence wattle break by 12 inches .
C.Wattle Barrier Construct wattle barriers with minimum 18 inch diamete r excelsior or coir fiber wattles as shown on the plans. Wattle barriers are to be placed at locations shown on the plans or as directed by the Engineer. When wattle barriers are used on slopes to reduce runoff velocity, 9 inch diameter wattles may be us ed. Align wattle barriers in an overlapping and alternating pattern. Overlap adjoining sections of wattles a minimum of 12 inches. Excavate a trench the entire length of each wattle with a depth of 2 inches to 3 inches for the wattle to be placed. Secur e wattle barriers to the soil by wire staples approximately every linear foot and at the end of each wattle. Install at least 4 stakes on the downslope side of the wattle with a maximum spacing of 2 linear feet. Install at least 2 stakes on the upslope s ide of the wattle barrier. Drive stakes into the ground at least 10 inches with no more than 2 inches projecting from the top of the wattle. Drive stakes at an angle to wedge wattles to the bottom of the trench. For wattle barriers used to reduce runoff velocity for large slopes, use a maximum spacing of 25 feet for the barrier measured along the slope . 1642 -4 MAINTENANCE AND REMOVAL Maintain the wattles, remove and dispose of silt accumulations at the wattles as directed by the Engineer in accordance with Section 1630. 1642 -5 MEASUREMENT AND PAYMENT _____ Wattle Check will be measured and paid for by the actual number of linear feet of wattles which are installed and accepted. Such price and payment will be full compensation for all work covered by this section, including, but not limited to, furnishing all materials, labor, equipment and incidenta ls necessary to install the Wattle. _____ Wattle Barrier will be measured and paid as the actual number of linear feet of wattles installed and accepted. Such price and payment will be full compensation for all work
Source: North Carolina Standard Specifications for Roads and Structures, 2024 Edition. Pages 772–774 of 857.