- 734 - SECTION 906 -- BROKEN CONCRETE RIPRAP
906.01 Description
1.a. The Contractor shall prep are the slopes and place broken concrete on the earth slopes at the locations shown in the contract.
b.Any excavation or embankm ent necessary to place the riprap to the limits shown in the contract shall be part of this work.
2.The concrete riprap shall be ob tained from the areas designated in the contract.
3.a. It shall be the responsibility of the Contractor to ensure that a sufficient quantity of concrete be brok en to the requirements stated below and removed for use as riprap.
b.Any concrete intended but not used as riprap shall be disposed of as directed by the Engineer.
906.02 Material Requirements
1.a. The Contractor shall size the riprap by breaking the concrete rubble so that no individual piece wi ll have a volume greater than 3.5 cubic (0.1 m3) feet.
b.No more than 10% of the ri prap pieces shall have a volume of less than 30 cubic inches (0.0005 m3).
c.Fifty percent of the riprap shall be composed of pieces with a volume less than 1,220 cubic inches (0.02 m3).
d.Each piece shall have no dimension greater than 4 times its least dimension.
2.Control of the sizing shall be by visual inspection to verify that the concrete rubble is well graded and conforms to the maximum and minimum sizes specified.
906.03 Construction Methods
1.Grading a. The finished earth surface shall conform to the grades and slopes of the neat lines of the bottom surface of the riprap as shown in the contract.
b.Depressions shall be filled with suitable dry material which shall be thoroughly tamped or otherwise compacted to insure stability.
c.Soft, unstable materials shall be removed and replaced with suitable material which shall be thoroughly tamped or otherwise compacted to insure stability. No raised places, bumps, or depressions will be allowed.
2.The Contractor shall place the broken concrete so each piece is touching the adjacent pieces in a conf iguration creating the highest possible density while producing a stable mass within the limits shown in the contract.
3.All material shall be placed so that the large and small sizes are well mixed.
4.Reinforcing steel bars projecting from the mass shall be cut off flush with the face from which it protrudes. Broken Concrete Riprap 906.05 - 735 - 5. All riprap placed will be covered with native soil and seeded above the historical ordinary high water mark or approximately three (3) feet above the existing channel flow line, whichever is greater.
906.04 Method of Measurement
1.Broken concrete riprap shall be measured by the ton (megagram).
2.The weight will be determined by measuring the volume [cubic yards (cubic meters)] of broken concrete riprap placed and multiplying by 1.35 ton/cubic yard (1.6 Mg/m3).
906.05 Basis of Payment
1.P a y I t e m P a y U n i t Broken Concrete Riprap Ton (Tn) [Megagram (Mg)]
2.Placing and mixing of native soil in the riprap is subsidiary to the excavation or embankment item.
3.Payment is full compensation for a ll work described in this Section. - 736 - SECTION 907 -- GABIONS AND REVET MATTRESSES
907.01 Description
1.The Contractor shall furnish, a ssemble, tie, and fill with approved stones mesh wire baskets constructed and placed in conformity with the lines, grades, and dimensions shown in the contract.
907.02 Material Requirement
1.Materials shall conform to t he requirements of Section 1074.
907.03 Construction Methods
1.The Contractor shall construct all gabion and revet mattress structures as shown in the contract.
2.All basket units shall be assembl ed by binding all adjacent vertical edges with basket connecting clips placed every 4 inches (100 mm).
3.Empty units shall be set to line and grade as shown in the contract. 4. Connecting clips shall be used to join the units together in the same manner as described above for assembling.
5.Internal connecting wires shall be uniformly spaced and securely fastened in each outside cell of the structure or where ordered by the Engineer.
6.A fence stretcher, chain fall, or iron rod may be used to stretch the wire baskets and hold alignment.
7.a. The baskets shall be filled wi th stone, carefully placed so that air void volume is minimized.
b.Hand placing of the rock-f ill shall be required on the exposed faces of the units so that the rock fill appears to be uniformly stacked.
c.The ledge rock shall be placed on its natural face surface rather than on the edge face.
d.After a basket has been filled, the lid shall be bent over until it meets the sides and edges.
8.Each basket shall be overfi lled approximately 2 inches (50 mm) above the sides before closing the lids. The lid shall then be secured to the sides, ends, and partitions with the connecting wire in the manner described above for assembling. Special attentio n shall be given to see that all projections or wire ends are turned into the baskets.
9.The Contractor shall also comp ly with all manufacturer installation requirements. The Contractor shall s ubmit the installation requirements to the Engineer two weeks prior to installation.
907.04 Method of Measurement
1.Gabions and revet mattresses shall be measured by the each.
907.05 Basis of Payment
1.P a y I t e m P a y U n i t Gabion, Type _____ Each (ea) Revet Mattress, Type _____ Each (ea) 2. Payment is full compensation for all work described in this Section.
Source: Nebraska Standard Specifications for Highway Construction, 2017 Edition. Pages 768–769 of 1,048.