for Highway Construction Page 571 of 715 SECTION 646-RESERVED for Highway Construction Page 572 of 71 5 SECTION 647 – TEMPORARY TURBIDITY CURTAIN
647.01 Description.
Provide and install a geosynthetic barrier that totally encloses construction within watercourses to confine sedimentation within the work area. The turbidity curtain must be a pre- assembled system, including the geotextile/geomembrane, connection, securing mechanisms, flotation devi ces, stakes, and ballast chain. Provide a system that is adequate and appropriate for the site conditions (e.g., current, wind/waves, depth [stream bottom elevation to normal water surface elevation]). Construct the turbidity curtain according to this specification, the plan details specified, or as directed. The work includes continued performance inspection , maintenance, and removal of the turbidity curtain and all accessories upon completion of the work within the turbidity curtain area. Before delivery to the project site, submit manufacturer’s cut- sheets and shop drawings detailing the materials, installation, maintenance, and removal of the temporary turbidity curtain for approval. This submittal must include at least 3 examples of projec ts where the manufacturer’s turbidity curtain was used.
647.02 Materials.
Ensure that the turbidity curtain is a bright color (i.e., yellow or international orange) that will attract the attention of boat traffic. Turbidity curtain installation must include navigation warning lights along the curtain at least every 20 feet and at each corner. Use 22 ounces per square yard PVC -coated fabric with a minimum grab tensile strength of 500 pounds for the turbidity curtain. Provide the geosynthetic material, anchoring system, floatation, and other necessary hardware to meet a Type 3 turbidity curtain installation for the anticipated construction conditions. Provide certifications and written specifications from the manufacturer to confirm compliance. Turbidity curtain will be accepted in accordance with the applicable procedures specified in subgrade separation geotextile Type II in 640 and 718.
647.03 Construction Requir ements.
Securely place, orient, and anchor the turbidity curtain according to the specified locations and depths, and according to the manufacturer’s written installation guidelines or as directed before work commences. Design the turbidity curtain system to handle site- specific drainage or flow conditions. Provide and maintain sufficient anchors, tie- downs, or other mechanisms to ensure proper position and performance of the turbidity curtain in accordance with the manufacturer’s written directions. Connect individual segments of curtains together using the manufacturer’s end- to-end attachments. Attach anchor lines to the flotati on device as described in the manufacturer’s written installation instructions. Any visible plume of cloudy water outside the protected construction area constitutes inadequate turbidity curtain performance. Immediately modify, adjust, or repair any portion of the turbidity curtain to correct inadequate performance. Design the anchor system to maintain adequate shape and barrier integrity of the curtain system under the construction conditions. Ensure the anchor system does not impede construction operations. Ensure that the turbidity curtain maintains continuous contact with the bottom. Excess curtain must lie without wrinkles on the bottom, away from construction activity. Maintain the turbidity curtain until the construction activity within the watercourse is complete and the turbidity is reduced to approved levels. Maintenance includes inspecting the turbidity curtain, flotation, and ballast to ensure the work area is securely partitioned from the waterway.