609AGGREGATE SLOPE PROTECTION

484

608.08Method of Measurement

The geotextile will be measured by the square yard {square meter} from the payment lines shown on the plans, or from the payment lines established in writing by the Engineer. This excludes seam overlaps. Excavation, backfill, bedding, and cover material are separate pay items.

608.09Basis of Payment

The accepted quantities of geotextiles will be paid for at the contract unit price per square yard {square meter} in place.

608-A Separation Geotextile - per square yard {square meter} AGGREGATE SLOPE PROTECTION

609.01Description

This Section shall cover the work of furnishing and constructing a slope protection layer of graded aggregate on slopes as shown on the plans or directed in accordance with these Specifications. This Section shall also cover the work, if shown on the plans, of furnishing and installing a geotextile filter blanket on slopes which are to receive the aforementioned aggregate protection layer.

609.02Materials

Materials furnished for use shall conform to the appropriate requirements of Division 800, Materials, and the following:

The geotextile shall meet the requirements of AASHTO M 288 for Permanent Erosion Control Geotextile, Class 2, and Section 810 of these specifications. In addition, the fabric shall have a minimum coefficient of friction of the wet fabric on wet aggregate of 0.4 as determined by the Department's Central Lab. The geotextile shall be selected from List II-3, of the Department's manual titled "Materials, Sources, and Devices With Special Acceptance Requirements". Information concerning this list is given in Subarticle 106.01(f) and ALDOT-355.

Securing pins for anchoring the filter shall be 3/16 of an inch {5 mm} steel bars, pointed at one end and fabricated with a head to retain a steel washer having an outside diameter of not less than 1.5 inches {38 mm}. The length of the pin shall not be less than 18 inches {450 mm}.

The aggregate shall be crushed stone meeting the requirements given in Section 801. The aggregate gradation shall be: AGGREGATE GRADATION FOR AGGREGATE SLOPE PROTECTION Percent Passing by Weight {Mass} Sieve Size Minimum Maximum 7" {175 mm} 100 - 6" {150 mm} 90 100 4" {100 mm} 20 55 3" {75 mm} 0 15 2" {50 mm} 0 5

609.03Construction Requirements

The slope to be treated shall be prepared by removing vegetation, topsoil, and dressing the slope to reasonable line and grade. The surface shall then be compacted, if necessary, by the use of mechanical tampers to the satisfaction of the Engineer before placement of the geotextile filter and AGGREGATE SLOPE PROTECTION 485

aggregate blanket. The dressing and preparation of the slope shall be considered incidental to the placement of the Aggregate Protection Blanket and no direct payment for such will be made. Where grading has been completed under another contract and regrading is necessary to obtain the desired uniform slope, such regrading shall be considered incidental to the placement of the aggregate protection blanket and no direct payment for such will be made.

The geotextile filter, if required, shall be placed in the manner and at the locations shown on the plans or as directed by the Engineer. Exposure of the geotextile to the elements between lay down and cover shall be a maximum of 14 days to minimize damage potential. At the time of installation, filter shall be rejected if it has defects, rips, holes, flaws, deterioration, or damage incurred during manufacture, transportation, or storage. The filter shall be placed with the long dimension horizontal with the natural ground line, unless otherwise directed by the Engineer, and shall be laid smooth and free of tension, stress, folds, wrinkles or creases. The strips shall be placed to provide a minimum width of 3 feet {1 m} of overlap for each joint. Overlap joints and seams shall be measured as a single layer of cloth. Securing pins with washers shall be inserted through both strips of overlapped cloth at not greater than the following intervals along a line through the midpoint of the overlap. Pin Spacing Slope 2 feet {0.6 m} Steeper than 1:3 3 feet {1.0 m} 1:3 to 1:4 5 feet {1.6 m} Flatter than 1:4 The filter shall be turned down and buried approximately 12 inches {300 mm} at all exterior limits. Additional pins, regardless of location, shall be installed as necessary to prevent any slippage of the geotextile filter. Each securing pin shall be pushed through the filter until the washer bears against the filter and secures it firmly to the foundation. The filter shall be protected at all times during construction from contamination by surface runoff and any filter so contaminated shall be removed and replaced with uncontaminated filter. Any damage to the filter during its installation or during placement of riprap shall be replaced by the Contractor. The work shall be scheduled so that 30 days does not expire between placement of the filter and the covering of the filter with the graded aggregate. Aggregate shall not be dropped on the filter from a height greater than 1 foot {300 mm}. Greater drop heights will be permitted if the Contractor provides a cushioning layer of sand on top of the filter before dumping of stone. The combination of drop height for stone and sand cushion layer thickness to be approved shall be demonstrated to not puncture or damage the filter. No measurement or separate payment shall be made for a sand cushion layer placed for the purpose of allowing an increased drop height of stones. Any damage to the geotextile filter during placement of aggregate shall be corrected prior to proceeding with the work.

The method of placement of the aggregate shall be at the option of the Contractor provided it produces uniform coverage and depth without damaging the geotextile filter, if present. Any damage to the filter shall be cause for ordering the aggregate cleaned from the damaged area and the repair of the filter by an additional layer of filter covering the damaged area overlapping at least 3 feet {1 m} onto undamaged filter and securing the patch with adequate securing pins. If uniformity of coverage is not obtained by the method of placement, such shall be corrected in a manner satisfactory to the Engineer. No compaction of the aggregate blanket is required.

609.04Method of Measurement

Accepted aggregate slope protection and geotextile filter for aggregate slope protection, if applicable, will each be measured in square yards {square meters}, complete in place, computed from actual measurements taken along the top surface of the treated area to the nearest 0.1 square yard {0.1 m²}.

609.05Basis of Payment

The accepted Aggregate Slope Protection and geotextile filter for aggregate slope protection, measured as noted above, will each be paid for at the contract unit price bid per square yard {square meter}. Said unit price bid shall be full compensation for the item complete in place and includes the furnishing of all materials, the preparation of the slope (excavation, backfill, compacting slope, RIPRAP 486

disposal of surplus material), placement of materials and for all equipment, tools, labor, and incidentals necessary to complete the work.

609-A Aggregate Slope Protection - per square yard {square meter} 609-B Geotextile Filter for Aggregate Slope Protection - per square yard {square meter} RIPRAP

610.01Description

This Section shall cover the work of furnishing and constructing the several classes or types of riprap, each of which shall consist of a protective course of stone or other approved materials on embankment slopes, in channels and ditches, wave protection for causeways and shoreline roadway embankments, bridge piers and abutments, or other work as shown on the plans or directed, with or without a geotextile filter, all in accordance with these specifications and in conformity with the lines, and grades noted in the plan details.

610.02Materials

If a geotextile filter is required, it shall meet the requirements of AASHTO M 288 for Permanent Erosion Control Geotextile, Class 1, and Section 810 of these specifications. All other materials shall conform to the requirements of Division 800, Materials. Specific reference is made to Section 814, Riprap Materials. The geotextile shall be selected from List II-3, of the Department's manual titled "Materials, Sources, and Devices With Special Acceptance Requirements". Information concerning this list is given in Subarticle 106.01(f) and ALDOT-355. In locations where maintaining the clear zone is a consideration, a traversable tied concrete block mat may be used in lieu of riprap. Tied concrete block mat shall be selected from the Department’s Miscellaneous Approved Products List/LIST II-24 “TEMPORARY AND PERMANENT EROSION AND SEDIMENT CONTROL PRODUCTS.” All mats must be installed with the manufacturer’s recommended underlayments/backings for site specific conditions. All mats and accompanying underlayments/backings shall have a minimum shear stress capacity of 10 pounds per square foot as tested per ASTM D6460. Prior to installation, the contractor shall submit documentation from the manufacturer, indicating the product meets the requirements for approval by the Engineer.

610.03Construction Requirements

All slopes to be treated with riprap shall be trimmed to the lines and grades indicated by the plans or directed; loose material shall be compacted by methods approved by the Engineer or removed. Slopes which require a geotextile blanket under the riprap shall, in addition to the above, be prepared as noted in Subarticle (b) below. Placement of any riprap on a filter blanket shall be by such means that will not damage or destroy the blanket. Any damage to the blanket shall be repaired without additional compensation. Unless otherwise authorized or directed by the Engineer, riprap protection for bridge ends shall be placed immediately following the grading operations. The bridge Contractor shall protect any slope protection material in place during the bridge construction and shall be responsible for any damage due to negligence on the part of his operations. If directed by the Engineer or shown by plan details, all outer edges and the top of riprap where the riprap terminates shall be formed so that the surface of the riprap will be embedded and even with the surface of the ground and/or slope. All riprap construction shall begin at the bottom of the slope and progress upward.

Unless otherwise specified by the plans or ordered in writing, the Contractor may select one of the filter blanket materials provided in Article 814.03 for construction of the filter blanket except that a geotextile blanket will not be allowed for soils with 85% by weight {mass} passing the #200 {75 µm} sieve. RIPRAP 487

If an aggregate blanket is used, the blanket shall be constructed using the designated material to a minimum thickness of 6 inches {150 mm}, unless otherwise shown by the plans, all in accordance with the provisions noted in this Subarticle and the plan details. If a geotextile filter is used, it shall conform with Article 610.02 of this Section.

Areas on which filter blankets are to be placed shall be uniformly trimmed and dressed to conform to cross sections shown by the plans within an allowable tolerance of plus or minus 3 inches {75 mm} from the theoretical slope lines and grades.

Filter blanket material shall be spread uniformly on the prepared base, in a satisfactory manner, to a thickness of not less than 1/2 of an inch {10 mm} from that specified and to neat lines as indicated on the plans. Placing or spreading of material by methods which will tend to segregate particle sizes within the filter layer will not be permitted. Any damage to the surfaces of the filter blanket foundation during the placing of the filter blanket shall be repaired before proceeding with the work. Compaction of the filter material will not be required but shall be finished to present a reasonably even surface free from mounds, depressions, or windrows.

Exposure of geotextiles to the elements between lay down and cover shall be a maximum of 14 days to minimize damage potential. The geotextile shall be placed and anchored on a smooth graded surface approved by the Engineer. The geotextile shall be placed in such a manner that placement of the overlying materials will not excessively stretch or tear the filter. Anchoring of the terminal ends of the geotextile shall be accomplished through the use of key trenches or aprons at the crest and toe of the slope. In certain applications, 18 inch {450 mm} long anchoring pins, placed on 2 to 6 foot {1 to 2 m} centers, depending on the slope of the covered area, should be used to expedite construction. Successive geotextile sheets shall be overlapped in such a manner that the upstream sheet is placed over the downstream sheet and/or upslope over downslope. In underwater applications, the geotextile and required thickness of backfill material shall be placed the same day. The backfill placement shall begin at the toe and proceed up the slope. Riprap and heavy stone filling shall not be dropped onto the geotextile from the height of more than 1 foot {300 mm}. Slope protection and smaller sizes of stone filling shall not be dropped onto the geotextile from a height exceeding 3 feet {1 m}. Any geotextile damaged during placement shall be replaced as directed by the Engineer at the Contractor's expense. The geotextile shall be joined by either sewing or overlapping. All seams shall be subject to the approval of the Engineer. Overlapped seams shall have a minimum overlap of 12 inches {300 mm} except where placed underwater where the overlap shall be a minimum of 3 feet {1 m}. A geotextile patch shall be placed over the damaged area and extend 3 feet {1 m} beyond the perimeter of the tear or damage.

Unless otherwise shown by the plan details or directed, stone riprap shall not be placed on slopes steeper than the natural angle of repose of the riprap material. Placement of stones may, unless otherwise noted in this Subarticle, be placed by methods and equipment approved by the Engineer suitable for the purpose of placing the riprap in accordance with the requirements for the class riprap involved without damaging any existing facility or construction feature.

Class 1 riprap is essentially designed for hand placement and use with minimal water currents. Stones shall be laid with close broken joints and resting on the embankment slope. The stones shall be of such shape and shall be so laid as to produce a single layer of stone of the thickness shown on the plans, measured perpendicular to the slope. The bottom course shall be laid in a trench excavated to such depth below the toe of the slope that all parts of the bottom course will be 3 feet {1 m} below the toe. Trenching will not be required where the toe of the slope is below RIPRAP 488

water level. The back of the trench shall be on the same slope as the fill. The laying of the courses shall progress upward, the larger stones being placed in the lower courses. The individual pieces of stone in each horizontal course shall be laid so that they will break joints with the stones in the course below the tops sloped to drain away from embankment. Open joints shall be filled with spalls, or small stones in such manner that all stones are tightly wedged or keyed. The finished surface shall present a reasonably uniform appearance and shall not vary more than 6 inches {150 mm} from the average surface. The finished surface at the ends of the riprap shall be flush with the adjacent earth fill surface.

Class 2 and 3 riprap is designed for use in areas with minimal to medium water currents and wave action. The stones shall be placed in such a manner as to produce a reasonably well graded mass of rock with the minimum practical percentage of voids. The riprap shall be constructed to the lines, grades and thickness shown by the plans or directed within a tolerance of plus 15 inches {375 mm} or minus 3 inches {75 mm} from the designated finish surface of the riprap, except that either extreme of such tolerance shall be reached as a uniform rate over an area greater than 200 square feet {19 m²}. Riprap shall be placed in its full course thickness in one operation and in such a manner as to avoid displacing the filter blanket material, where filter blanket is required. The larger stones shall be well distributed and the entire mass of stones in their final position shall conform to a reasonable uniform gradation. The finished riprap shall be free from objectionable pockets of small stones and clusters of larger stones. Placing riprap by dumping into chutes or by other methods likely to cause segregation of sizes will not be permitted. The desired distribution of the various sizes of stones throughout the mass shall be obtained by selective loading of the material at the source, by controlled dumping of successive loads during final placing, or by other methods of placement which will produce the specified results. Rearranging of individual stones by mechanical equipment, or by hand, will be required to the extent necessary to obtain a reasonably well graded distribution of stone as specified above.

Class 4 and 5 riprap is designed for use in medium to high water currents and wave actions for the protection of bridge piers and abutments, and protection of channel slopes. Stones may be placed without strict gradation controls provided sufficient small sizes are included to choke the larger stones. Dumping of the stones will be allowed; however, mechanical equipment to dress the material to a reasonable uniform slope will be required. Stones deposited contrary to directions will be considered wasted and will not be paid for.

Immediately following mixing, as noted in Article 814.02, the mixture shall be placed in the bags, tied (so that when laid in position they will flatten out and give a thickness of not less than 6 inches {150 mm} and placed flat on the area designated. Bags shall be rammed against each other to form closed joints, with tied ends of sacks all laid in the same direction. When required to be placed under water, special care shall be taken to see that bags are closely jointed to give the same tight joints as required on dry slopes. After the riprap is placed, it shall be sprinkled with water as directed and kept damp for not less than three days. No Concrete Sacked Riprap shall be mixed in freezing weather.

Tied concrete block mat shall be placed according to the manufacturer’s recommendations.

The Contractor shall maintain all riprap until the contract is accepted, and shall replace, without additional compensation, any damaged or lost riprap.

610.04Method of Measurement

Loose Riprap of the class designated by the plans or proposal will be measured in square yards {square meters}, computed from measurements taken parallel to the surface of the riprap or in tons {metric tons} as specified in Subarticle 109.0l(h), whichever is specified by the plans or proposal. Concrete Sacked Riprap, Filter Blanket, and Tied Concrete Block Mat will be measured in square yards {square meters} computed from measurements taken parallel to the outer surface of the riprap or the filter blanket, whichever is applicable.