SECTION 602: SLOPE AND EROSION PR OTECTION STRUCTURES
602.1 Description
This Work consists of providi ng and placing riprap, gabions, re vetment mattresses, sacked concrete revetment, concrete block revetment, wrapped ro ck faces, and other systems on the Embankment slopes and t he sides and bottoms of channels, drain outlets, ditches, and other such locations.
602.2 Materials
Unless otherwise specified in the Contract, the Contractor shal l provide slope protection Structures as follows: 1. Hexagonal double-twisted wire mesh riprap, gabions, and reve tment mattresses; or 2. Welded wire mesh gabions, revetment mattresses, and wrapped rock faces. The Contractor shall provide gal vanized slope protection items in accordance with ASTM A 641. If specified in the Contract, the Contractor shall coat galvanized items with PVC in accordance with Section 602.2.2.2.9, “PVC Coating.” The Contractor shall provide double-twisted riprap, gabions, an d revetment mattresses in accordance with ASTM A 975. The Contractor shall provide welde d wire mesh gabions, revetment mattresses, and wrapped rock faces in accordance with ASTM A 974.
602.2.1 Classifications
The Department will classify riprap and gabions in accordance w ith Table 602.2.1:1, “Riprap Classifications and Gabion Requirements.” The Contractor shall provide riprap with at least 80% of the st ones meeting the specified size requirements. The Contractor shall use stones less than t he minimum dimensions to fill voids. For riprap Class A, wrapped rock faces, and gabions, th e Contractor shall not use stones smaller than the mesh openings. The Department will classify riprap and gabions in accordance with Table 602.2.1:1 “Riprap Classifications and Gabion Requirements” with the excep tion of Class D, Derrick Stone. Class D, Derrick Stone will follow the gradation requir ements in Table 602.2.1:2 “Gradation Requirements for Cla ss D, Derrick Stone” shown below . Table 602.2.1:1 Riprap Classifications and Gabion Requirements Class Stone volume (ft3) Minimum dimension (in)a Description Minimum Maximum
A.Wire enclosed riprap 1/6 2/3 4 Bb Non-enclosed riprap 1 2 6 Cb Non-enclosed riprap 2 4 9
E.Grouted riprap 1/3 1 3
F.Grouted riprap 1 2 6
G.Rock plating — — 4–8c Table 602.2.1:1 Riprap Classifications and Gabion Requirements Class Stone volume (ft3) Minimum dimension (in)a Description Minimum Maximum N/A Wrapped rockfacing — — 1 N/A Gabions — — 4–8c aMinimum size in the least dimension. bClass B and C stone — at least two (2) Fractured Faces. c70% to 80% of the stone — at least four (4) inches but not more than eight (8) inches in the smallest dimension. 30 to 20% of the stone — no larger than fo ur (4) inches in any dimension. Table 602.2.1:2 Gradation Requirements for Class D, Derrick Stone Class, Description Percent of Rock Equal or Smaller By Count, D X Range of Intermediate Dimension 1, (inches) Range of Rock Weight2, (pounds) D, Derrick Stone3 100 30 5000 70 24 – 18 1780 – 2500 40 11 – 14 360 – 500 20 6 – 8 70 - 100 1 Intermediate dimension measur ed as the shortest straight-line distance from one side of the rock or rock particle to the other on the maximum projection pl ane (plane of rock or rock particle with the largest projected surface area). 2 Weights based on a specific gravity of 2.65. 3 Include spalls and rock fragment s to provide a stable dense ma ss.
602.2.2 Riprap, Gabions, and Revetment Mattresses
602.2.2 1 Stone for Riprap, Gabions, Revetment Mattresses, and Rock Faces
Except for Class G riprap, the C ontractor shall provide rocks o r rough quarry stone with no more than 60% wear, in accordance with AASHTO T 96. The Con tractor shall provide stone with a soundness loss of no more than 21, in accordance w ith AASHTO T 104 using a magnesium sulfate solution with a five (5)-cycle test duration. The Contractor shall provide stone for riprap, gabions, revetme nt mattresses, and rockfaces in accordance with Sec tion 602.2.1, “Classifications. ”
602.2.2 2 Wire Mesh
The Contractor shall provide non-raveling, double-twisted wire mesh forming hexagons for riprap, gabions, and revetment mattresses in accordance wit h Section 602.2.2.3, “Pull- Apart Test.” The Contractor shall provide non-raveling welded wire mesh for gabions, wrapped rock faces, and revetment mattresses forming squares or rectangles in accordance with ASTM A 974, Section 7, Material Properties, except that the strength requirement for mattress joints is 900 lb per foot instead of 600 lb per foot. 602.2.2.2.1 Wire Section 602: Slope and Erosion Protection Structures Page 610 The Contractor shall provide soft temper wire with a Class 3 zi nc coating for constructing wire mesh in accordance with ASTM A 641. The Contractor shall provide 0.120-inch diameter wire for gabions and riprap and 0 .087-inch diameter wire for re vetment mattresses and wrapped rock faces.
602.2.2 2.2 Mesh Openings
The Contractor shall ensure that mesh openings are uniform and hexagonal. The Contractor shall make mesh openings for riprap and double-twist ed gabions approximately 3 1/4 inch × 4 3/4 inch, and for double-twisted revetment mattres ses approximately 2 1/2 inch × 3 1/4 inch. The Contractor shall make mesh openings for welded wire mesh gabions approximately three (3) inch × three (3) inch, and for welded w ire mesh revetment mattresses and wrapped rock faces approximately 1 1/2 inch × three (3) inc h.
602.2.2 2.3 Selvedges
The Contractor shall mechanically selvedge the edges of double- twisted gabions, revetment mattresses, and wrapped rock face, including, end pan els and diaphragms. The Contractor shall use a selvedge wire with a diameter of at leas t 0.150 inch.
602.2.2 2.4 Lacing and Tie Wire
The Contractor shall provide lacing wire for double-twisted gab ions, revetment mattresses, and wrapped rock faces with a diameter of at least 0.087 inch. The Contractor shall provide tie wire for double-twisted gabions and revetment mattresses with a diameter of at least 0.087 inch. The Contractor shall provide tie wire for riprap with a diameter of at least 0.120 inch. The Contractor shall provide lacing and tie wire w ith the same tensile strength and coating as the mesh wire.
602.2.2 2.5 Spiral Binders
The Contractor shall provide spiral binders for welded wire mes h gabions, revetment mattresses, and wrapped rock faces, of the same wire quality as the mesh wire with a diameter of at least 0.106 inch. Unless otherwise approved, th e Contractor shall provide spiral binders with a maximum inside diameter of 2 1/2 inches and with a maximum pitch of three (3) inches.
602.2.2 2.6 Alternate Fasteners
The Contractor may use alternative fasteners, such as ring fast eners, with double-twisted wire mesh, and welded wire mesh riprap, gabions, revetment matt resses, and wrapped rock faces, if approved by the Project Manager. The Contractor shal l provide wire for alternative fasteners in accordance with Section 602.2.2.2.5, “Spiral Binde rs.”
602.2.2 2.7 Minimum Strength of Fasteners
The Contractor shall use fasteners that provide a minimum stren gth of 1,400 lb per foot for gabion baskets, and 900 lb per foot for revetment mattresse s and wrapped rock faces.
602.2.2 2.8 Approval of Alternative Fasteners
The Contractor shall use a certified Laboratory to test alterna tive fasteners in accordance with Section 602.2.2.3, “Pull-A part Test.” At least 60 Days be fore using alternative fasteners, the Contractor shall submit CTRs to the Project Manager verifyi ng that the fasteners meet the pull-apart test requirements. The Contractor shall provide a description of the fastener, wit h drawings and photographs showing the number of fasteners required, details of the fasten ers, and load capacities. In addition the Contractor shall: 1. Lock and close each interlocking fastener. For gabions, use fasteners in every other opening. For revetment mattresses and wrapped rock faces , use fasteners in every opening; and 2. Close each overlapping ring fastener and overlap ends a mini mum of one (1) inch. Provide one (1) ring for each opening. The Department will allow this fastener for forming individual baskets, but not for interconnecting baskets.
602.2.2 2.9 PVC Coating
The Contractor shall provide PVC coating with an average thickn ess of 0.0216 inch and a minimum thickness of 0.0150 inch per side. The Contractor shal l apply PVC coating over the galvanizing. The Contractor shall coat the galvanized wire with extruded or fusion bonded PVC Material. Unless otherwise specified, the Contractor shall use a gray or green colored coating. The Contractor shall use a PVC coating that meets the following requirements: 1. Specific gravity of from 1.20 to 1.40, if tested in accordan ce with ASTM D 792; 2. Abrasion resistance of less than 12% weight loss, if tested in accordance with ASTM D 1242-95A, Method B at 200 cycles, CSI-A Abrader Recordin g, 80 grit; 3. Brittleness temperature no higher than 15° F, if tested in a ccordance with ASTM D 746; 4. Tensile strength no less than 2,980 psi for extruded coating , if tested in accordance with ASTM D 412; and no less than 2,275 psi for fusion bonded c oating, if tested in accordance with ASTM D 638; 5. Modulus of elasticity no less than 2,700 psi at 100% strain for extruded coating, if tested in accordance with ASTM D 412; and no less than 1,980 ps i at 100% strain for fusion bonded coating, if tested in accordance with ASTM D 638; 6. Ultraviolet light exposure for a test period of no less than 3,000 h, using apparatus Type E at 145 °F, if tested in accordance with ASTM G 152; and 7. Salt spray test for a test period of no less than 3,000 h, i f tested in accordance with ASTM B 117.
602.2.2 3 Pull-Apart Test
602.2.2 3.1 Sample Preparation
The Contractor shall prepare two (2) identical rectangular pane ls along a selvedge wire, each about 10 1/2 mesh-openings wide. The Contractor shall att ach the two (2) panels along the two (2) selvedge wires using the proposed fastener system. If the Contractor uses alternative fasteners to join two (2) individual gabion baskets , the Contractor shall include two
2.additional selvedge wires (eac h mechanically wrapped with m esh wires) so that each fastener contains two (2) selvedges and two (2) mesh wires.
602.2.2 3.2 Test Procedures
The Contractor shall mount the joined test panels in a loading machine with grips or Section 602: Slope and Erosion Protection Structures Page 612 clamps that secure the panels uniformly along the full width. The Contractor shall use grips or clamps designed to transmit only tension forces. The Contracto r shall apply the load at a uniform rate of 50.7 lb per second until failure occurs. The D epartment will define failure as a drop in strength under continuous loading or, when an opening b etween two (2) joined selvedge wires exceeds two (2) inch. The minimum allowable str ength at failure is 1,400 lb per foot for joined gabions; and 900 lb per foot for joined rev etment mattresses and wrapped rock face panels.
602.2.2 4 Certification
The Contractor shall submit a certificate, to the Project Manag er, stating that the following proposed items meet the requirements of this Specification befo re their use: 1. Wire mesh; 2. Gabion baskets; 3. Lacing wire; 4. Tie wire; and 5. Approved alternative fastener systems.
602.2.2 5 Stakes
The Contractor shall use steel railroad rails, standard weight galvanized steel pipe, or steel angles for riprap stakes. The Contractor shall use railr oad rails with a unit weight of at least 30 lb per yard. The Contractor shall use standard weight galvanized steel pipe with a minimum outside diameter of four (4) inches. The Contractor sh all use steel angles that are at least four (4) × four (4) × 3/8 inch.
602.2.2 6 Grout
The Contractor shall provide portland cement, aggregate, and wa ter for grout in accordance with Section 509, “Port land Cement Concrete Mix Desi gns.”
602.2.2 7 Material
The Contractor shall provide geot extile (filter fabric) Class o ne (1) as per Section 604, “Soil and Drainage Geotextiles.”
602.2.3 Sacked Concrete Revetment
The Contractor shall provide sacked concrete revetment from a v endor on the Department’s Approved Products List. The Contractor shall provide bags of concrete that weigh from 60 lb to 80 lb each, dry weight, and contain from 0. 018 yd³ to 0.025 yd³ of concrete. The Contractor shall ensure each bag contains one (1 ) of the following mixes: 1. One (1) part cement to three (3) parts sand; 2. A mix design in accordance with the Contract; or 3. A mix design approved by the State Materials Bureau. The Contractor shall provide a concrete mix capable of attainin g a minimum compressive strength of 3,500 psi after 28 Days, unless otherwise specified in the Contract. The Contractor shall keep the sacked concrete in dry storage until application .
602.2.3 1 Packaging
Section 602: Slope and Erosion Protection Structures Page 613 The Contractor shall use permeable, biodegradable sacks made of jute, cotton, or scrim- reinforced paper that are capable of holding the sand-cement mi x without significant leakage and allowing sufficient water to hydrate the concrete mix. The Contractor shall provide non-asphaltic, three (3)-layer lam inated, polyester-fiber- scrim-reinforced paper sacks. The Contractor shall perforate e ach of the three (3) layers and offset the perforations to prevent cement leakage. The Contractor shall use only one (1) type and size of sack th roughout the Project, unless otherwise specified in the Contract.
602.2.3 2 Portland Cement
The Contractor shall provide portland cement in accordance with Section 509, “Portland Cement Concrete Mix Designs.”
602.2.3 3 Aggregate
The Contractor shall provide fine aggregate in accordance with Section 509, “Portland Cement Concrete Mix Designs.”
602.2.3 4 Steel Anchorage
The Contractor shall provide steel staples in accordance with S ection 540, “Steel Reinforcement.” The Contractor shall use steel staples either epoxy coated in accordance with AASHTO M 284, or galvanized in accordance with ASTM A 153.
602.2.4 Concrete Block Revetment
The Contractor shall provide concrete block revetment products from the Department’s Approved Products List. The Contractor shall provide concrete block units compatible with the geotextiles being used and with a minimum compressive strength of 3,000 psi, unless otherwise specified in the Contract.
602.3 Construction Requirements
602.3.1 General Placement Requirements
The Contractor shall place ri prap stones forming a continuous b lanket in accordance with the Contract. Unless otherwise specified, the Contractor shall construct rock plating using riprap Class G to minimum thickness of 12 inches. The Contract or shall place stones with the long axis parallel to the toe of the slope, with a stable beari ng upon the underlying soil or stones. The Contractor shall place large stones as close together as po ssible. The Contractor shall use smaller stones to fill the areas between the larger s tones, except when the Contract requires Class E or F (grouted) riprap. The Contractor shall ensure that the finished riprap surface va ries no more than three (3) inches from the specified sl ope; and derrick stone riprap varie s no more than eight (8) inches from the specified slope. Unless otherwise specified, the Contractor shall place the ripr ap foundation course in a trench excavated to 24 inches below the toe of the slope of the Embankment or side of channel. The Contractor shall place a layer of Class 1 geotextile filter fabric between the slope and erosion protection Structure s, and the backfill Material.
602.3.1 1 Grouted Riprap Placement
The Contractor shall fill riprap voids with grout to the full r iprap thickness. After placing grout, the Contractor shall sweep the riprap surface with a sti ff broom. The Contractor shall protect grout from freezing for at least f our (4) Days after placement. The Contractor shall cure grouted riprap placed in hot, dry wea ther in accordance with Section 511.3.9, “Curing.” 602.3.1.2 Proportioning and Mixing Grout The Contractor shall use grout that consists of one (1) part po rtland cement and three (3) parts fine aggregate (by volume). The Contractor shall mix wit h water to a workable consistency.
602.3.1 3 Class A Riprap Placement
The Contractor shall enclose Class A riprap with wire mesh draw n tightly on all sides. The Contractor may connect wire mesh using approved fasteners o r lacing wire. The Contractor shall weave adjacent edges at least once with double loops of lacing wire that is as strong and flexible as the mesh. The Contractor shall provide c ontinuous lacing as far as possib le that passes through each mesh opening. Where splicing is necessary, the Contractor shall overlap the lacing at least 12 inches. The Contractor shall space galva nized wire ties connecting top and bottom mesh layers approximately 24 inches on centers. The Contractor shall ancho r the ties to the bottom wire- fabric layer. The Contractor shall extend the ties through the rock layer and secure to the top wire-fabric layer. The Contractor shall anchor wire-enclosed r iprap to slopes with steel stakes driven into the Embankment. The Contractor shall space stakes in accordance with the Contract.
602.3.1 4 Placement of Geotextile
The Contractor shall place Class 1 non-woven geotextile (filter fabric) between the riprap or revetment mattresses and the supporting soil. The Contracto r shall ensure that the fabric is in accordance with Section 604, “Soil and Drainage Geotextiles. ”
602.3.2 Sacked Concrete Revetment Placement
The Contractor shall place sacked concrete revetment within ± 0 .2 ft of the specified grade and slope, or as direc ted by the Project Manager. The Contractor shall place the foundation course in a trench ex cavated to 24 inches below the toe of the slope of the Embankment or side of channel . The Contractor shall stagger the sack ends and steel st aple anchors of succeeding co urses. The Contractor shall tamp each row of sacks, round out the bags , eliminate wrinkles, minimize voids, and prepare an even surface for the next row. The Contractor shall obtain the Project Manager's approval of t he compaction method prior to backfill and compact soil behind each row of sacks bef ore placing the next row. The Contractor shall not place lar ge stones and jagged objects adja cent to the bags. The Contractor shall anchor the sacks with steel staples witho ut damaging the sacks. After placing the sacks, the Contractor shall wet thoroughly an d keep moist for at least three (3) Days.
602.3.3 Concrete Block Revetment Placement
The Contractor shall construct concrete block revetment systems in accordance with the manufacturer’s recommendations and the Contract. The Contractor shall remove slope obstructions, and fill voids with approved Material or grade slopes before placing concrete blocks.
602.3.4 Gabions
The Contractor shall supply gabi ons within ± five percent (5%) of the manufacturer’s stated sizes.
602.3.4 1 Assembly of Gabion Baskets
The Contractor shall fabricat e gabions for individual assembly at the construction site. If a gabion is greater than 1 1/2 times as long as it is wide, the Contractor shall divide the gabion into cells using diaphragms of the same wire mesh as the body of the gabion. The Contractor shall create cells that are no longer than the gabio n is wide and anchor diaphragms to the base section of the gabion. The Contractor shall selved ges or bind perimeter edges so the joints are as strong as the gabion body. The Contractor sh all assemble perimeter edges using approved fasteners or lacing wire. The Contractor shall place fasteners in each mesh opening. The Contractor shall secure lacing wire by double loo ping through every other mesh opening. The Contractor shall assemble gabions using one (1) o f the following: 1. Double looped lacing twice; or 2. Connect with approved fasteners and double looped lacing onc e.
602.3.4 2 Foundation Preparation
The Contractor shall level and compact the top six (6) in of th e gabion foundation to at least 95% of maximum density in accordance with AASHTO T 180 (M odified Proctor), Method D (TTCP Modified), and to field densities in accordance with AA SHTO T 310.
602.3.4 3 Placement of Gabion Baskets
The Contractor shall set assembled, empty baskets into the spec ified positions and wire each unit to adjacent units along the top and vertical edges be fore placing stone.
602.3.4 4 Placement of Gabion Stone
The Contractor shall place stone in equal layers of from nine ( 9) inch to 12 inch. The Contractor shall minimize local d eformations by not filling a g abion more than 12 inches higher than an adjacent gabion. The Contractor shall hand place stone at exposed surfaces. The Contractor shall provide cross-connecting wires on gabions with cells 18 inches or higher. The Contractor shall pl ace cross connecting wires dire ctly above each layer of stone. The Contractor shall equally space and tightly tie two (2) conn ecting wires in each direction for each layer through two (2) mesh openings at opposite faces of e ach gabion cell. The Contractor shall maintain alignment while filling gabions ( minimizing voids and bulges, and finishing to a neat square appearance). After filling, the Contractor shall bend the lid over and tight ly bind to the perimeters and diaphragms in accordance with Section 602.3.4.1, “Assembly of G abion Baskets.”
602.3.4 5 Gabion Marking
The Contractor shall mark each gabion in an identifiable manner that clearly indicates its size.
602.3.4 6 Placement of Geotextile
The Contractor shall install Cl ass 1 non-woven geotextile (filt er fabric) between gabion baskets and supporting soil, and between gabion baskets and bac kfill.
602.3.5 Placement of Wrapped Rock Faces
The Contractor shall place wrapped rock faces within ± 0.2 ft o f the specified grade and slope. The Contractor shall place the foundation course 18 inches belo w the toe of the slope of the Embankment or side of channel. The Contractor shall place each level of welded wire forms with biaxial geogrid embedded in the rock face in accordance with the Contract, and tensioned with anchor pins to remove slack. The Contractor shall lap the geogrid a minimum o f 12 inches at the edges of adjacent panels. The Contractor shall tamp the welded wire for m face to eliminate wrinkles, minimize voids, and fini sh to an even surface. The Contractor shall backfill and compact behind each welded wi re form level before placing the next row. The Contr actor shall obtain the Project Manager's approval of the compaction method.
602.4 Method of Measurement
The Department will measure Riprap Class___ and Sacked Concrete Revetment based on the specified thickness and Accepted surface area. The Department will measure Concrete Block Revetment and Wrapped Rockfacing based on the Accepted surface area. The Department will measure Gabions and Revetment Mattresses based on the specified basket dimensions.
602.5 Basis of Payment
Pay Item Pay Unit Section 602: Slope and Erosion Protection Structures Page 617 Riprap Class ___ Cubic Yard Riprap Class G Square Yard Sacked Concrete Revetment Cubic Yard Concrete Block Revetment Square Yard Gabions Cubic Yard Revetment Mattresses Cubic Yard Wrapped Rockfacing Square Yard
602.5.1 Work Included in Payment
The following Work and items will be considered as included in the payment for the main item(s) and will not be measured or paid for separately: 1. Excavation, backfilling and dis posal of Material required fo r the placement of slope and erosion protection Structures; 2. Dewatering; and 3. Stakes and steel staples, drainage geotextile(s). Section 603: Temporary Erosion and Sediment Control Page 618
Source: New Mexico Standard Specifications for Highway and Bridge Construction, 2019 Edition. Pages 0–0 of 974.