16-17 1636 -3 Construction Methods
Construct stream crossings according to Roadway Standard Drawings or as directed by the Engineer . The Contractor shall determine the diameter of pipe(s) that will pass the peak or bankfull flow, whichever is less, from a 2- year peak storm, without overtopping. Place the geotextile on natural ground, on streambanks and in streambed beneath the temporary pipe(s) and stone according to the detail. Install Class B stone around the pipe(s), in the stream channel and on the crossing road sideslopes. Place sedi ment control s tone on top of Class B stone according to Roadway Standard Drawings . 1636 -4 MEASUREMENT AND PAYMENT Sediment Control Stone will be measured and paid in accordance with Article 1610- 4. Stone for Erosion Control, Class __ will be measured and paid in accordance with
Article 1610 — 4.
Geotextile for Drainage will be measured and paid in accordance with Article 876 -4. Temporary Pipe for Stream Crossing will be measured and paid at the contract unit price per linear foot of temporary pipe approved by the Engineer and measured in place from end to end.
Article 104 — 5, pertaining to revised contract prices, will not apply to Temporary P ipe for
Stream Crossing . No revision in the contract unit price will be allowed because of any overrun or underrun. 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 construct the stream crossings. Payment will be made under: Pay Item Pay Unit Temporary Pipe for Stream Crossing Linear Foot RISER BASI N 1637 -1 DESCRIPTION Construct, maintain and remove riser basin devices to reduce water velocity and contain sediment. The actual conditions which occur during the construction of the project will determine the quantity of riser basin devices constructed. The quantity of riser basins may be increas ed, 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 change in the character of the work.
1637-2 Materials
Refer to Division s 3 and 10. Item Section C.S. Pipe Tee riser 1032 -3 Stone for Erosion Control, Class B 1042 Coir Fiber Mat 1060 -14 Provide appropriately sized and approved skimmer device .
16-18 1637 -3 Construction Methods
Work includes constructing earth embankments and overflow spillways, and installing outlet pipe, tee -riser sections, trash racks, anti -flotation dev ices, coir fiber baffles , skimmer and stone energy dissipater in silt basins in accordance with Roadway Standard Drawings . Use either anti- flotation method shown in the Roadway Standard Drawings . Construct earth embankments with 2:1 side slopes with mater ial meeting roadway embankment specifications in accordance with Section 1018 . The m aximum height of earth embankments is 12 feet. Compact embankment to at least 90% of AASHTO T 99 as modified by the Department or as directed by the Engineer . Excavate w hen required to provide minimum surface area and minimum storage volume area measured below the top of the principal spillway (top of the riser pipe). Install a C.S. pipe tee riser as specified in the plan s. Additional C.S. pipe may be required to obtain the required riser pipe height (crest elevation) as indicat ed in the plan s. Construct a trash rack and an anti -flotation device on the riser pipe. Attach skimmer to riser pipe 1 foot above bottom elevation of basin. Install coir fiber baffles in the basin in accordance with Section 1640 or as directed by the Engineer . Construct an overflow spillway outlet, on natural ground, one foot above riser pipe. Plate overflow spillway with erosion control stone Class B as spec ified in the plan s. Stabilize the embankment and surrounding areas with vegetation after installation. Construct energy dissipater pad at the barrel pipe outlet with erosion control stone Class B in accordance with the Roadway Standard Drawings . 1637 -4 MAINTENANCE AND REMOVAL Place a marker in the basin indicating the 50% volume level. Clean out riser basin i n accordance with Section 1630. Remove riser basin devices as the project nears completion or as directed by the Engineer . Prepare a seed bed, seed and mulch the area in accordance with Section 1660 after removal of the riser basin. 1637 -5 MEAS UREMENT AND PAYMENT C.S. Pipe Tee Riser, __ " Thick will be measured and paid in units of each installed and accepted. Such price shall include furnishing and installing any additional pipe required for correct riser height, the trash rack and the anti -flotation device. Stone for Erosion Control, Class __ will be measured and paid in accordance with
Article 1610 — 4.
Pipe for the outlet will be measured and paid in accordance with Article 310-6. Silt Excavation will be measured and paid in accordance with Article 1630-3. Coir Fiber Baffle will be measured and paid in accordance with Article 1640 -4. __" Skimmer will be measured an d paid in accordance with Article 1644-5. P ayment will not be made for any work performed under this section that is solely for the convenience of the Contractor or that is made necessary due to negligence of the Contractor. Payment will be made under: Pay Item Pay Unit __" x __" x __" C.S. Pipe Tee Riser, __" Thick Each