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The work covered by this section consist of the construction, maintenance, and removal of physical barriers placed in ditches, diversions, swales, or drainage turnouts to reduce water velocity and trap sediment. The quantity of temporary rock sediment dams to be constructed will be affected by the actual conditions which occur during the construction of the project. The quantity of sediment dams may be increased, decreased, or eliminated entirely at the direction of 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.
All materials shall meet the requirements of Division 10 shown below:
Plain Rip Rap, Class I Article 1042-1
Stone for Erosion Control Class ___ Article 1042-1
Sediment Control Stone Section 1005
(A) Type-A:
Temporary rock sediment dam type-A devices shall be constructed as shown on the plans. The temporary rock sediment dam type-A shall be constructed at the locations shown on the plans and at other locations directed by the Engineer.
The structural stone shall be placed 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. The upstream side shall be faced with sediment control stone approximately 12 inches thick.
The weir section shall be approximately 2/3 of the channel width where the device is being placed and shall have an 8 foot maximum height from the bottom of the channel. The weir section shall be approximately 12 inches lower than the top of the channel (whichever is lower) located in the center of the device.
(B) Type-B:
Temporary rock sediment dam type-B devices shall be constructed as shown on the plans. The temporary rock sediment dam type-B shall be constructed at the locations shown on the plans and at other locations directed by the Engineer.
The structural stone shall be placed in the channel, ditch diversion, swale, or drainage turnouts with 2:1 side slopes and shall be faced with sediment control stone approximately 12 inches thick.
The weir section shall have a 2 foot minimum width and shall be 18 inches lower than the sides or the top of the channel (whichever is lower) located in the center of the device.
The temporary rock sediment dam type-B shall have a 5 foot minimum thickness measured along the top of the dam structure. The structural stone apron shall be approximately 8 foot long with a 2 foot depth.
Earthen backfill material may be used to extend dam width and create a larger sediment storage volume for the temporary rock sediment dam type-B.
1634-4 MAINTENANCE AND REMOVAL.
The contractor shall maintain the temporary rock sediment dams, and shall remove and dispose of silt accumulations at the sediment dams when so directed by the engineer in accordance with Section 1630.
Unless otherwise directed by the Engineer, temporary rock sediment dams shall be removed as the project nears completion, or at such time the Engineer deems the device to be no longer useful. The actual time of removal shall be as directed by the Engineer. Upon removal, the Contractor shall dress the area to give a pleasing appearance, and shall seed and mulch the area in accordance with Section 1660.
Temporary rock sediment dams will not be measured for payment under this article.
Payment for temporary rock sediment dams will be as follows:
The quantity of structural stone measured as provided in Article 16104 will be made at the contract unit price per ton for "Stone for Erosion Control, Class ____" as provided in Article 16105.
The quantity of sediment control stone measured as provided in Article 16104 will be made at the contract unit price per ton for "Sediment Control Stone" as provided in Article 16105.
The removal and disposal of silt accumulations will be paid for
as provided in Section 1630.