- 685 - SECTION 811 -- TRANSITION MAT
811.01 Description
1.This work consists of the fu rnishing and installation of transition mats as shown in the contract or as directed by the Engineer. A transition mat is a semi-rigid plastic, rubber mat or concrete blocks imbedded into a high strength geogrid that protects t he soil from scour and erosion. It is placed in ditches or at the culvert outlets and is generally used in conjunction with a soil retention blanket.
811.02 Material Requirements
1.The Transition Mat shall be lis ted on the Department’s Approved Products List.
2.Erosion Control Class 2A is required under all installations.
811.03 Construction Methods
1.This work shall be performed as soon as possible after the finish grading operations have been completed.
2.The Contractor shall install the soil retention blanket as detailed in Section 810.
3.The transition mat shall be placed as per the manufacturers recommended installation instructions at the locations as shown in the contract.
811.04 Method of Measurement
1.The quantity of transition mat fo r which payment will be made will be the number of square yards placed.
2.Sod placed will be paid for according to Section 809 – Sodding. 3. Soil retention blankets placed will be paid for according to Section 810 -- Erosion Control.
811.05 Basis of Payment
1.P a y I t e m P a y U n i t Transition Mat Square Yard
2.All anchoring devices shall be s ubsidiary to the item “Transition Mat”.
3.Payment is full compensation for all work described in this Section. - 686 - SECTION 812 -- SILT CHECKS
812.01 Description
1.This work consists of furnishi ng and placing silt check devices at the locations shown in the contract or as directed by the Engineer.
2.There are two separate and di stinct types of silt checks.
a.Silt Checks are placed as show n in the contract or as directed by the Engineer after final grading is complete in conjunction with the final stabilization.
b.Temporary Silt Checks are placed as shown in the Temporary Erosion Control plans or as directed by the Engineer throughout the construction process.
812.02 Material Requirements
1.Approved silt check devices are listed in and shall be selected from the Department’s Approved Products List.
a.Silt Checks used for final stabilization shall be the type shown in the contract and selected from the Department’s Approved Products List.
b.Temporary Silt Checks ma y be any product listed on the Department’s Approved Products List. T he following chart shall be used to determine the appropriate application of Temporary Silt Checks during construction. Type Material Ditch Grade Uses/Locations 1 – Low 9 “ Diameter Straw Wattle < 2% Medians, Slopes and Urban Ditches 1 – High 12” Diameter Straw Wattle < 2% Wetlands, Stream Banks, Slopes and Rural Ditches 2 – Low 9” Diameter Wood Fiber Wattle All Medians and Urban/Rural Ditches 2 - High 12” Diameter Wood Fiber Wattle All Wetlands, Stream Banks, and Rural Ditches 3 – Low 9” Diameter Coir Wattle All Slopes, and Rural Ditches 3 – High 12” Diameter Coir Wattle All Wetlands, Stream Banks, Slopes and Rural Ditches 4 Synthetic All Urban Ditches
2.All silt check devices have uniq ue staking or pinning requirements based upon the Best Management Practices (BMPs) and its use. The hold down stakes and pins shall be as show n on the Silt Check All Types Special Plan.
812.03 Construction Methods
1.The silt checks shall be placed and secured as shown in the contract or as directed by the Engineer.
2.The limits of the completed silt check shall extend up the foreslope and backslope of the ditch to effectiv ely contain the run-off and prevent
Source: Nebraska Standard Specifications for Highway Construction, 2017 Edition. Pages 719–719 of 1,048.