SECTION 02270

SLOPE PROTECTION

PART 1 - SCOPE

This section of the specifications will govern the furnish- ing of all labor, equipment, appliances, materials and all incidental and appurtenant operations necessary to place a protective covering of erosion-resistant material on the slopes of embankments, dikes, or streambanks, at culvert inlets and outlets, on bottoms and side slopes of channels, at abutment wings, at structure foundations, at other loca- tions shown on the plans, or as directed by the Engineer. The work shall be done in accordance with these specifica- tions and applicable special provisions and in conformity with the lines and grades shown on the plans or established by the Engineer.

The types of slope protection included in this specification are:

1.01 Dumped Riprap, or Riprap

Dumped riprap, or riprap, consists of stone or broken con- crete dumped in place on a filter blanket or prepared slope to form a well-graded mass with a minimum of voids.

1.02 Gabions

Gabions consist of mats or baskets fabricated from wire mesh, filled with stone, connected together and anchored to the slope. Details of construction may differ depending upon the degree of exposure and the service, whether used for revetment or used as a toe protection for other types of slope protection.

1.03 Grouted Riprap

Grouted riprap consists of riprap with all or part of the interstices filled with portland cement mortar.

1.04 Concrete-Slab Riprap, or Slope Paving

Concrete-slab riprap, or slope paving, consists of concrete, plain or reinforced, cast in place or precast concrete blocks.

1.05 Aggregate Filter Blanket

A filter blanket consists of one or more layers of graded material placed on the underlying bank before placing the riprap in order to prevent the bank material from passing through the riprap protection. The thickness and gradation 02270 - 2

of filter blanket will be shown on the plans.

1.06 Filter Fabric

Filter fabric consists of a pervious plastic filter cloth meant to provide the same separation of bank material and riprap protection as an aggregate filter blanket.

PART 2 - MATERIALS

This part of the specifications deals with the quality and type of certain construction materials to be used in connec- tion with the work, and the methods of determining their fitness for use in the project. The Engineer is authorized to reject any materials which do not comply with the speci- fications and test herein established, or which do not comply with commonly accepted standards of quality whether or not included in these specifications. Any materials rejected by the Engineer shall be promptly removed from the project by the Contractor and at no additional cost to the Owner.

2.01 Dumped Riprap, or Riprap

Stone used for dumped riprap shall be hard, durable cold- stone or rough, unhewn quarrystone, angular in shape; resis- tant to weathering and to wave action; free from overburden, spoil, shale and organic material; and shall meet the grada- tion requirements specified. Neither breadth nor thickness of a single stone should be less than one-third its length. Rounded stone cobbles or boulders will not be accepted unless authorized by special provision. Broken concrete may be substituted for stone when authorized by special provi- sion. Shale and stone with shale seams are not acceptable. The stone shall have a specific gravity (bulk-saturated- surface-dry basis, AASHTO Test T-85) of at least 2.4.

The sources from which the stone will be obtained shall be selected well in advance of the time when the stone will be required in the work. The acceptability of the stone will be determined by service records and/or by suitable tests. If testing is required, suitable samples of stone shall be taken in the presence of the Engineer at least 25 days in advance of the time when the placing of riprap is expected to begin. The approval of some rock fragments from a par- ticular quarry site shall not be construed as constituting the approval of all rock fragments taken from that quarry.

In the absence of service records, resistance to disintegra- tion from the type of exposure to which the stone will be subjected will be determined by any or all of the following 02270 - 3

tests as stated in the special provisions:

A. When the riprap must withstand abrasive action from material transported by the stream, the abrasion test in the Los Angeles machine (AASHTO Test T-96) is used, the stone shall have a percentage loss of not more than 40 after 500 revolutions.

B. In locations not subject to freezing or where the stone is exposed to salt water, the sulfate soundness test (AASHTO Test T-104) for ledge rock using sodium sul- phate) shall be used. Stones shall have a loss not exceeding ten percent with the sulfate test after five cycles.

C. When the freezing and thawing test (AASHTO Test T-103) for ledge rock procedure A) is used as a guide to resistance to weathering, the stone shall have a loss not exceeding ten percent after twelve cycles of freez- ing and thawing.

Stone shall be free from over burden, spoil, shale, and organic material and shall meet the following gradation requirements:

% of Material Smaller than Typical Stone Typical Stone Riprap Stone Size 2 3 4 d501 (inches) Typical Stone Dimensions (inches) Weight ( Pounds) 70-100 12 85 50-70 9 35 35-50 6 10 6 2-10 2 0.4 70-100 15 160 50-70 12 85 35-50 9 35 9 2-10 3 1.3 70-100 21 440 50-70 18 275 35-50 12 85 12 2-10 4 3 100 30 1280 50-70 24 650 35-50 18 275 18 2-10 6 10 100 42 3500 50-70 33 1700 35-50 24 650 24 2-10 9 35 02270 - 4

1. Nominal size stone 2. Based on typical rock mass 3. Equivalent spheical diameter 4. Specific gravity of 2.5

Each load of riprap shall be reasonably well graded from the smallest to the maximum size specified. Stones smaller than the specified ten percent size and spalls will not be per- mitted in an amount exceeding ten percent by weight of each load.

Control of gradation will be by visual inspection. The Contractor shall provide, unless exempted under the special conditions, two samples of rock of at least five tons each, meeting the gradation for the class specified. One sample at the construction site may be a part of the finished riprap covering. The other sample shall be provided at the quarry. These samples shall b used as a frequent reference for judging the gradation of the riprap supplied. Any difference of opinion between the Engineer and the Contrac- tor shall be resolved by dumping and checking the gradation of two random truckloads of stone. Mechanical equipment, a sorting site, and labor needed to assist in checking grada- tion shall be provided by the Contractor at no additional cost to the Owner.

2.02 Gabions and Slope Mattresses

Stone used for gabion shall meet the requirements of Section 2.1, except for size and gradation of stone, and as provided hereafter. Stone used shall be well graded within the sizes available and 90 percent, by weight, shall exceed in least dimension the wire mesh opening. The maximum size of stone shall not exceed the minimum basket dimension. Rounded stone, cobbles and boulders will not be accepted for gabion fill.

All wire used in the manufacture and assembly of the mesh shall equal or exceed Federal Specification QQ-W-461G, Wire, Steel, Carbon (Round, Bare and Coated) including the follow- ing specific requirements; finish 5, class 3 weight of zinc coating.

Wire mesh for Gabions (cage thickness 12" and greater) shall be 11 gauge (U.S.), soft temper.

Wire mesh for Slope Mattress (cage thickness up to 10") shall be 14 gauge (U.S.), soft temper.

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Tie and connecting wire shall be supplied for securely fastening all edges of the gabions and diaphragms. Gabions shall be provided with 4 cross connecting wires in each cell ½ unit high and 8 in each cell one unit high. Gabions shall also have inner tie wires connecting the front face to the rear face at approximate spacing of 12" in both vertical and horizontal dimensions. Tie wire shall meet the same speci- fications for wire used in the mesh except that tie wire for gabion cages shall not be more than 2 gauges lighter.

All wire used, including tie and connecting wire, shall be certified by mill test report(s) showing compliance with specifications requirements.

Mesh Openings - The longer dimension of the mesh openings for gabions and slope mattresses shall be as shown on plans.

Wire Mesh - Wire mesh shall be woven in such a manner as to be non-raveling and have elasticity.

Edge Wire Connection - The edge wire connection for both gabions and slope mattresses shall be strong enough so that when tested the first wire break shall occur in the wire mesh.

Selvedge - The selvedge on each sheet of mesh for both gabions and slope mattresses shall be galvanized steel wire (as described above) 2 gauges heavier than that used in the body of the mesh. For gabions, it shall be attached to the wire mesh strong enough so that when tested, no wire shall break until the loading on the table below has been reached. For slope mattresses, the first wire shall break in the wire mesh.

Field Connections - The field connections between adjacent wire baskets shall be made as recommended by the manufactur- er and shall develop a connection strong enough that the failure under test shall occur in the mesh rather than in the lacing.

TABLE FOR MINIMUM STRENGTH TESTS FOR GABION BASKETS ONLY

Minimum Strength Part Lb. per Lin. Ft.

Wire Mesh Pulled parallel to wire twist 3400 Pulled perpendicular to wire twist 1000 Connection of Selvedge wire to mesh 2200

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Dimensions - Gabions and slope mattresses shall be supplied in the various sizes shown on the plans. Cages and mat- tresses furnished by a manufacturer shall be of uniform size.

Tolerances - All gabion and slope mattress dimensions are subject to a tolerance limit of ±3% of manufacturer's stated sizes.

The sizes of riprap stone for gabions and slope mattresses shall conform to the following:

Stone Size

Gabions (cage thickness 12" or greater) 4" to 8" Slope Mattress 3" to 6"

Soil Anchor Stakes for Wire Mesh Slope Mattresses - Soil anchor stakes shall be steel and may be:

1. Crane rails of a convenient size (min. 40 lb./yd.) 2. 2" size steel pipe conforming to ASTM A-120 either black or galvanized. 3. 3"x3"x3/8" structural steel angles conforming to ASTM A-36 or better. 4. Used rails, pipe, or angles may be used provided the material is not rusted or damaged to such an extent that the strength of the stakes is affected.

Soil anchor stakes shall be of the lengths called for on the plans.

2.03 Grouted Riprap

Grout for grouted riprap shall consist of one part portland cement and three parts of sane, thoroughly mixed with water to produce grout having a thick creamy consistency. The minimum amount of water should be used to prevent excess shrinkage of the grout after placement. The cement, sand, and mixing shall conform to the specifications for concrete masonry, ASTM C-476.

The stones for grouted riprap shall meet the requirements of Section 2.1, except for size and gradation. Size and grada- tion will be specified for each particular project or as shown on the plans. Stone shall be free of fines which prevent penetration of grout and care shall be taken in placing the stone to keep earth or sand from filling the spaces between the stones. All fill beneath grouted riprap shall be compacted to 95% Proctor density. 02270 - 7

2.04 Concrete-Slab Riprap, or Slope Paving

Concrete for concrete-slab riprap shall be Class III unless the riprap is exposed to salt water, in which case it shall be Class IV. The slabs shall be of two types, plain con- crete and reinforced. If reinforcement is specified, it shall be furnished as shown on the plans. Except as modi- fied herein, materials and construction shall conform to specifications for Concrete Work and Reinforcing Steel, Section 03000.

2.05 Aggregate Filter Blanket

The filter blanket shall consist of one or more layers of gravel, crushed rock, sand, cinders, slag or other approved free-draining material of the thickness shown on the plans. The gradation of material in each layer of the filter blan- ket shall meet the requirements of the special provisions. All material comprising the filter blanket shall be composed of tough, durable particles, reasonably free from thin, flat and elongated pieces, and shall contain no organic matter nor soft, friable particles in quantities in excess of those approved by the Engineer.

2.06 Filter Fabric

Plastic Filter Cloth shall be manufactured especially for erosion control applications and shall consist of either polyvinylidene chloride, nylon/polypropylene or polypropy- lene monofilament yard. The plastic filter cloth shall meet the physical requirements for its intended use as set forth in the following table:

PLASTIC FILTER CLOTH

Fabric Requirements for Intended Use (Minimum Roll Averages Fabric Property Test Method Embankment Erosion Control

I. Plastic filter cloth shall be 100% insect, rodent, mildew and rot resistant for all applications.

II. Resistance to Installation Stresses

a. Grab tensile strength, lb. ASTM D-1682 125 lb.

b. Grab tensile elongation, % ASTM D-1682 20% 02270 - 8

c. Burst strength, psi ASTM D-751 125 (Diaphragm Method)

d. Trapezoid tear strength, lb. ASTM D 2263-78 60 lb.

e. Toughness, lb.% ASTM D-1682 4000 (Strength x Elongation)

III. Performance Criteria During Service Life

a. Equivalent opening size, U.S. Standard Sieve CW 002215 60-100

b. Water Flow Rate gal/min/ft2 H, 75 cm to 15 cm 100

IV. General Description

The plastic filter cloth shall be a woven or nonwoven fabric consisting only of long chain polymeric filaments or yarns formed into a stable network such that the filaments or yarns retain their relative positions to each other.

Securing pins shall consist of galvanized wire or other approved material. Wire pins shall be made of wire .091 inches or larger in diameter and "U"-shaped having legs 6 inches long and a 1-inch crown.

The Contractor shall furnish the Engineer three copies of a certified test report from the producer, showing all data required to indicate compliance with the specifications listed in the foregoing table.

PART 3 - CONSTRUCTION DETAILS

Slopes to be protected by riprap shall be free of brush, trees, stumps, and other objectionable material and be dressed to a smooth surface. All soft or spongy material shall be removed to the dept shown on the plans or as di- rected by the Engineer and replaced with approved material. Filled areas will be compacted as specified for Earthwork, Grading and Excavation, Section 02200. A toe trench as shown on the plans shall be dug and maintained until the riprap is placed.

Protection for structure foundations shall be provided as early as the foundation construction permits. The area to be protected shall be cleaned of waste materials and the 02270 - 9

surfaces to be protected prepared as shown on the plans. The type of riprap specified will be placed in accordance with these specifications as modified by the special provi- sions.

When shown on the plans, an aggregate filter blanket or filter fabric shall be placed on the prepared slope or area to be provided with foundation protection as specified in Section 3.5 or 3.6, before stone is placed.

3.01 Dumped Riprap

Stone for riprap shall be placed on the prepared slope or area in a manner which will produce a reasonably well graded mass of stone with the minimum practicable percentage of voids. The entire mass of stone shall be placed so as to be in conformance with the lines, grades, and thicknesses shown on the plans. Riprap shall be placed to its full course thickness at one operation and in such a manner as to avoid displacing the underlying material. Placing of riprap in layers, or by dumping into chutes, or by similar methods likely to cause segregation will not be permitted.

The larger stones shall be well distributed and the entire mass of stone shall conform to the gradation specified in Section 2.1. All material going into riprap protection shall be so placed and distributed that there will be no large accumulations of either the larger or smaller sizes of stone.

It is the intent of these specifications to produce a fairly compact riprap protection in which all sizes of material are placed in their proper proportions. Hand placing or rear- ranging of individual stones by mechanical equipment may be required to the extent necessary to secure the results specified.

Unless otherwise authorized by the Engineer, the riprap protection shall be placed in conjunction with the construc- tion of the embankment with only sufficient lag in construc- tion of the riprap protection as may be necessary to allow for proper construction of the portion of the embankment protected and to prevent mixture of embankment and riprap. The Contractor shall maintain the riprap protection until accepted, and any material displaced by any cause shall be replaced to the lines and grades shown on the plans at no additional cost to the Owner.

When riprap and filter material are dumped under water, thickness of the layers shall be increased as shown ont he plans; and methods shall be used that will minimize segrega- 02270 - 10

tion.

3.2 Gabions and Slope Mattresses

Gabions and slope mattresses shall be placed to conform with plan details. Riprap material shall be placed in close contact in the unit so that maximum fill is obtained. The units may be filled by machine with sufficient hand work to accomplish requirements of this specification.

Where the length of the unit exceeds its horizontal width the gabion is to be equally divided by diaphragms, of the same mesh and gauge as the body, into cells whose length does not exceed the horizontal width. The unit shall be furnished with the necessary diaphragms secured in proper position on the base section in such a manner that no addi- tional tying at this juncture will be necessary.

A. Gabions - All perimeter edges of gabions are to be securely selvedged or bound so that the joints formed by tying the selvedges have approximately the same strength as the body of the mesh.

The gabion bed shall be excavated to the width, line and grade as staked by the Engineer. The gabions shall be founded on this bed and laid to the lines and dimensions required.

Excavation for toe or cut-off walls shall be made to the neat lines of the wall.

All gabion units shall be tied together each to its neighbor along all contacting edges in order to form a continuous connecting structure.

B. Slope Mattresses - Slope mattresses shall be filled with angular or fractured stone. Rounded boulders will not be permitted. Before the mattress units are filled, the longitudinal and later edge surfaces of adjoining units shall be tightly connected by means of wire ties placed every 4 inches or by a spiral tie having a complete loop every 4 inches. The lid edges of each unit shall be con- nected in a similar manner to adjacent units. The slope mattresses shall be anchored as shown on plans.

The Contractor shall determine for himself whether the holes for the soil anchor stakes are to be drilled or whether the stakes may be driven. Care shall be taken to avoid drilling holes to a greater depth than is necessary to place the top of the finished stake slightly above the top of the finished mattress. 02270 - 11

The Contractor will be allowed to assemble, partially fill and tie together mattress units on the subgrade provided they can be placed ont he slope without abrading the zinc coating on the wire mattress or permanently distorting the shape of the mattress in transporting and installing the units on the slope. All prefabrication procedures shall be subject to approval.

3.3 Grouted Riprap

The stones shall be placed on the prepared slope substan- tially to the dimensions shown on the plans. The stones and base material shall be thoroughly moistened and any excess of fines shall be sluiced to the underside of the stone blanket prior to placing grout.

The grout may be delivered to the place of final deposit by any means that will insure uniformity and prevent segrega- tion of the grout. If penetration of grout is obtained by gravity flow into the interstices, the grout shall be spaded or rodded into the interstices to completely fill the voids in the stone blanket. Pressure grouting shall not unseat the stone; and after placing by this method, the grout shall be spaded or rodded into the voids. Penetration of the grout shall be to the depth specified on the plans. When a rough surface is specified, stone shall be brushed until from ¼ to ½ of the depth of surface stone is exposed. For a smooth surface, grout shall fill the interstices to within ½-inch of the surface.

Weep holes shall be provided through the blanket as shown ont he plans or as directed by the Engineer. Where the depth specified for grouting is in excess of 12 inches, such as cutoff walls, the riprap shall be placed in lifts of 12 inches or less and each lift shall be grouted prior to placing the next lift. The succeeding lifts shall be con- structed and grouted before the grout in the previous lift has hardened.

Grout shall be placed only when the temperature is above 35°F and rising. It shall be protected from freezing and cured as specified in Concrete work and Reinforcing Steel, Section 03000.

3.04 Concrete-Slab Riprap, or Slope Paving

Slabs of the dimensions and type, plain and reinforced, shown on the plans shall be poured in place with Class III concrete unless otherwise specified. Alternate slabs shall be poured and the remaining panels shall be poured later. 02270 - 12

Unless otherwise specified, the slabs shall be laid in horizontal courses and successive courses shall break joints with the preceding ones. Horizontal joints shall be normal to the slope and shall be cold joints without filler. The joints extending up the slope shall be formed with 3/4-inch lumber, which shall be removed and the joint left open. The slabs shall be finished with a wood float.

The pouring and curing shall be carried out as specified for Class III concrete in Concrete Work and Reinforcing Steel, Section 03000.

3.05 Aggregate Filter Blanket

When required, a filter blanket shall be placed on the prepared slope or area to the full specified thickness of each layer in one operation, using methods which will not cause segregation of particle sizes within the bedding.

The surface of the finished layer should be reasonably even and free from mounds or windrows. Additional layers of filter material, when required, shall be placed in the same manner, using methods which will not cause mixture of the material in the different layers.

3.06 Filter Fabric

The plastic filter cloth or impervious plastic lining shall be laid to conform to plan details. Areas on which the cloth or lining is to be placed shall have a uniform slope, be reasonably smooth, free from mounds and windrows and free of any debris or projections which could damage the materi- al.

Plastic filter cloth shall be loosely laid (not stretched), and in such a manner to avoid rupture of the cloth. The cloth shall be anchored in place with two securing pins at three-foot spacing along, but not closer than two inches to the edges and to the extent necessary to prevent displace- ment. Overlaps shall be at least 18 inches. Laps shall be used wherever possible, in order to minimize the number of vertical laps. Lengths and widths of individual sheets shall be at the Contractor's option.

Riprap placed ont he plastic filter cloth shall not be dropped through a free fall greater than three feet. Any filter cloth damaged or displaced before or during placement of overlying layers shall be replaced or repaired to the satisfaction of the Engineer, at the Contractor's expense.

02270 - 13

PART 4 - GEOLOGICAL CONDITIONS

The Contractor shall assume all responsibility for deduc- tions and conclusions which may be made as to the nature of the materials to be excavated, including the difficulty of making and maintaining the required excavation, problems caused by groundwater should such be encountered, problems encountered in excavating for lines and structures, and any other difficulties which may result from the geological and physical conditions encountered at the site of the work.

PART 5 - INSPECTION

Inspection by the Soils Engineer shall be during the place- ment and compacting operations so that he can certify that the fill was made in accordance with the Specifications.

Inspection necessary to control fill and compaction opera- tions, including a Soils Engineer and/or compaction tests, will be at the expense of the Owner.

PART 6 - SEASONAL LIMITS

No fill material shall be placed, spread or rolled while it is frozen or thawing or during unfavorable weather condi- tions. When the work is interrupted by heavy rain, fill operations shall not be resumed until the Soils Engineer indicates that the moisture content and density of the previously placed fill are as specified.

PART 7 - METHOD OF MEASUREMENT

The quantity of riprap to be paid for, of specified thick- ness and extent, in place and accepted shall be measured by one of the following methods as specified for the type of riprap placed. Riprap placed outside the specified limits will not be measured or paid for, and the Contractor may be required to removed and dispose of the excess riprap without cost to the Owner.

7.01 Per Square Yard

The quantity for grouted riprap, aggregate filter blanket and filter fabric shall be the number of square yards as computed from surface measurements parallel to the riprap surface.

7.02 Per Cubic Yard

The quantity for dumped riprap, concrete-slab riprap and slope paving shall be the number of cubic yards obtained by 02270 - 14

measurements parallel to the surface and thickness measured normal to the surface. The quantity for gabions shall be the number of cubic yards obtained on the basis of the nominal wire basket dimensions.

PART 8 - BASIS OF PAYMENT

The quantities determined, as provided in Section 7, shall be paid for at the contract unit price per unit of measure- ment for each particular item listed in the following sched- ule and shown in the bid schedule, which price shall be full compensation for furnishing all materials, tools, and labor; the preparation of the subgrade; the placing of the filter blanket when required; the placing of the stone; the grout- ing when required; furnishing steel for reinforced concrete- slab riprap; and all other work incidental to finished construction in accordance with these specifications.

Pay Item Unit of Measurement

(X) Dumped riprap per cubic yard (X) Gabions per cubic yard ( ) Grouted riprap per square yard ( ) Concrete-slab riprap and slope paving per cubic yard ( ) Aggregate filter blanket per square yard (X) Filter fabric per square yard