720 Page 479720 BANK AND CHANNEL PROTECTION GABIONS
720.1DESCRIPTION
This work consists of furnishing, assembling and filling woven wire gabions with stones as specified in the contract in conformance with the dimensions, lines, and grades shown on the plans or established by the Engineer.
720.2MATERIALS
Materials will conform to the following requirements and Sections. A.Stone: The stone will be durable stone or ledge rock, free of seams, cracks, and defects. Slabby stone pieces will not be acceptable. The stone will range in size from a minimum of 4 inches to a maximum of 8 inches in the greatest dimension. The majority of the stones will be in the 5 to 6 inch range and cubical or rounded in shape. Stone will not have an L.A. Abrasion of more than 40%. B.Gabions: Gabions will conform to the plans and Section 1030 . C.PVC Coating: When specified, the wire used in the fabrication of the bank and channel protection will be PVC coated. After zinc coating, the PVC coating will be extrusion bonded on the wire. The PVC coating will have a nominal thickness of 0.02165 inches and a minimum thickness of 0.015 inches. The lacing wire will also be PVC coated. The PVC coating will not crack, peel, blister, split, or have any other defects. The coating material will be resistant to the effects of weather and exposure to ultraviolet rays. D.Drainage Fabric: Drainage fabric will conform to Section 831, Type B. E.Lacing and Internal Connecting Wire: Lacing and internal connecting wire will be 0.0866 inch diameter steel wire ASTM A641 Class 3 soft temper measured after galvanizing and for PVC coated baskets will be 0.0866 inch diameter steel wire measured after galvanizing but before PVC coating. F.Interlocking Fasteners: Interlocking fasteners will conform to Section 1030 .
720.3CONSTRUCTION REQUIREMENTS
Slopes to be protected by gabions will be free of brush, trees, stumps and other objectionable material and will be dressed to a smooth surface. Soft or spongy material will be removed to the specified depth and replaced with suitable material. Filled areas will be thoroughly compacted. The bank and channel protection will be assembled individually by erecting the sides, ends and diaphragm(s) with all creases in the correct position and the top of all sides satisfactorily level. Lacing wire, fasteners, or both will be used to assemble the units and to join the units together. A.Lacing: The lacing procedure is as follows: 1.Cut a length of lacing wire approximately 1½ times the distance to be laced but not exceeding 5 feet. 720 Page 4802.Secure the wire terminal at the corner by looping and twisting. 3.Proceed lacing with alternating single and double loops at a spacing not to exceed 6 inches. 4.Securely fasten the other lacing wire terminal. B.Interlocking Fasteners: Interlocking fasteners may be used for basket assembly as final construction of gabion structures. Spacing of fasteners during all phases of assembly and construction will not exceed 6 inches. C.Alternate Fasteners: The use of alternate fasteners will be permitted in lieu of lacing wire provided the following has been demonstrated. 1.The ability of the alternate fastener to contain a minimum of four selvedge wires while remaining overlapped a minimum of 1 inch for overlapped type or in a locked and closed condition. 2.The proposed fastener system can consistently produce a four selvedge wire joint with a strength of 1400 pounds per linear foot for a galvanized joint and 1200 pounds per linear foot for PVC coated gabion joints. 3.The proper installation can be readily verified by visual inspection. When drainage fabric is specified, the surface to be covered will be smooth, free of obstructions, and will conform to plan shown dimensions prior to placement of the drainage fabric. The drainage fabric will be placed under and along all sides of the bank and channel protection that is in contact with earth, unless otherwise shown on the plans. Lapped joints in the drainage fabric will be placed transverse to the direction of flow with the overlap in the direction of flow. All lapped joints will be lapped a minimum of 12 inches. Vehicles and equipment will not be operated directly on the drainage fabric. A standard fence stretcher, chain fall, or iron rod may be used to stretch the bank and channel protection and hold alignment. The units will be filled with stone carefully placed by hand or machine to assure alignment and avoid bulges with a minimum of voids. To allow for settlement, overfilling of 2 to 3 inches is required. After each unit has been filled, the lid will be stretched tight over the stone fill using only an approved lid closing tool, until the lid meets the perimeter edges of the front and end panels. Using crowbars or other single point leverage bars for lid closing will be prohibited. After the units are filled, the lid(s) will be folded over to meet the sides and edges and secured with lacing wires, fasteners, or both. When PVC coated bank and channel protection is specified, special care will be taken during the filling operation to avoid damaging the coating. Bank and channel protection on which the PVC coating has been damaged will be repaired or replaced. Whenever a structure requires more than one tier, the upper empty cells will also be connected to the top of the lower tier along the front and back edges of the contact surface using the same connecting procedure described above using lacing wire or fasteners or both. 720 Page 481Internal connecting wires will be installed in multi-tiered structures as follows: 36 Inch High Gabions: 36 inch high gabions will be filled in three layers, 1 foot at a time. After the placement of each layer, that is at 1 foot high and 2 feet high, connecting wires will be placed according to the manufacturer’s recommendations to connect the exposed face of a cell to the opposite side of the cell. An exposed face is any side of a cell that will be exposed or unsupported after the structure is completed. 18 Inch High Gabions: 18 inch high gabions do not require connecting wires unless the cells are used to build vertical structures. In some cases, these units will be filled in two layers, 9 inches at a time. After the placement of the first layer, connecting wires will be placed according to the manufacturer’s recommendations to connect the exposed face of a cell to the opposite side of the cell. An exposed face is any side of a cell that will be exposed or unsupported after the structure is completed.
720.4METHOD OF MEASUREMENT
A.Bank and Channel Protection Gabions: Bank and channel protection gabions will be measured to the nearest 0.1 cubic yard. If a substitution is made, the dimensions of the bank and channel protection installed will be equal to or greater than the dimensions specified. Payment will be based on plans quantity, unless changes are ordered in writing by the Engineer. B.Drainage Fabric: Drainage fabric will be measured to the nearest square yard. The lap at joints will not be included in the measurement.
720.5BASIS OF PAYMENT
A.Bank and Channel Protection Gabions: Bank and channel protection gabions will be paid for at the contract unit price per cubic yard. Payment will be full compensation for materials, equipment, labor, excavating, shaping and incidentals required. B.Drainage Fabric: Drainage fabric will be paid for at the contract unit price per square yard. Payment will be full compensation for furnishing and installing the drainage fabric as specified. Payment will be for plan quantity unless changes are ordered in writing. 730 Page 482730 SEEDING
730.1DESCRIPTION
This work consists of preparing a seedbed and furnishing and planting seed on disturbed areas, except roadbeds, within the limits of the work.
730.2MATERIALS
A.General: The seed will comply with the requirements of the South Dakota Seed Law. B.Origin Limitations: Grass seed furnished will be the grass species listed in the plans. The Contractor may use one of the grass varieties listed in the plans for the specified grass species or the Contractor may use a different grass variety of the same grass species specified. If the Contractor uses a grass variety listed in the plans for the specified grass species, the grass seed origin limitations will not apply. If the Contractor uses a grass variety not listed in the plans for the specified grass species, the grass seed furnished must originate in South Dakota, North Dakota, Montana, Wyoming, Nebraska, Iowa, Minnesota, Kansas, Colorado, or Wisconsin. Grass seed grown outside this area may be approved after the Contractor has furnished written certification from three seed suppliers confirming seed grown within this area is not readily available. Forb, sedge, rush, shrub, and wildflower seed must originate in the United States or Canada. Forb, sedge, rush, shrub, and wildflower seed grown outside the United States and Canada may be approved after the Contractor has furnished written certification from three seed suppliers confirming seed grown within the two countries is not readily available. C.Seed Testing: Seed will be tested within 9 months prior to planting, exclusive of the calendar month in which the test was completed. Testing will be performed by a State Seed Lab, Commercial Seed Testing Lab, or a registered member of the Society of Commercial Seed Analysts (Registered Seed Technologist). A certified test report will be furnished prior to the start of seeding operations. If the seed is not planted within the 9 month period, the Contractor will have the seed retested for germination, as described above, and a current germination report with the certified test report will be furnished prior to starting seeding operations. The retest will be based on a sample obtained from the seed out of compliance. D.Labeling: Each bag of seed delivered to the project will bear a tag which shows the following information: 1.Name and address of supplier. 2.County and project number for which seed is to be used. 3.Suppliers lot number for each kind of seed in the mixture. 4.Origin (where grown) for each kind of seed. 5.Purity, germination, and other information required by South Dakota Seed Law, for each kind of seed.