217SPECIAL PROTECTION FOR ROCK SLOPES

134

The diameter and length of the rock bolt to be used shall be determined by the Engineer. All installations shall be in accordance with the recommended procedure or method as given by the manufacturer of the rock bolts. When directed by the Engineer, proper tests will be made to determine what torque the rock can withstand. If the tests show that the highest torque practical is of a certain value for a particular grade of rock, then torque shall be applied to the rock bolt provided the torque does not exceed the maximum recommended by the manufacturer of the rock bolts. It is recognized that any over-application of torque will only destroy the anchorage in the rock and in due time destroy the initial tightness of the bolt. It is desired that a minimum torque of 125 foot pounds {170 N•m} be applied in all cases where the rock will withstand such pressure.

Extreme care shall be taken to keep the drill hole aligned perpendicular to the plate bearing surface. The diameter of the drill hole shall be as recommended by the manufacturer for the type of expansion unit to be used for anchorage into the rock. Expansion units shall not be used in holes larger than that for which they are designed. When slotted type rock bolts are used, the bolt with wedge shall be inserted in the hole until the wedge hits the bottom of the hole. The bolt shall then be driven into the hole with an air-percussion hammer forcing the wedge into the slotted end of the bolt, thus anchoring the bolt in the hole. The plate and nut shall then be installed on the collar end of the bolt and the nut tightened to the torque recommended by the manufacturer.

The seam designated by the Engineer for sealing shall be examined carefully during the grading operations for evidence of seepage which will require construction of weep holes in the sealing cap as well as for the best method for placing the sealing cap.

The material in the seam to be treated shall be routed out or otherwise removed to a depth at least equal to the thickness of the seam or layer to be treated or to a depth which will give firm support to the sealing material.

The clean seam shall be sealed or packed with one of the following types of concrete mixes. The method of packing or placing the sealant shall be left to the Contractor provided the method used produces the desired results and presents an acceptable appearance. Weep holes, when deemed necessary, shall be placed as directed.

Specifications.

water applied pneumatically. (Mix designed by the Contractor to produce a 28-day cylinder strength of 5000 psi {35 Mpa})

An Asphalt Surface shall be placed on areas designated by the Engineer to prevent excessive erosion from surface runoff over relatively soft and erodible materials.

The surface to receive the asphalt surfacing shall be fairly uniform, without excessive high and low spots, suitable for coverage with asphalt. The surface shall be clean and free from loose rock fragments before applying the surfacing material.

The surfacing material shall be Asphalt Cement Grade 40 or an approved equal. The bituminous material shall be applied at the rate of 1.25 gallons per square yard {5 L/m²}. The method of application shall be that of the Contractor's provided it is approved by the Engineer, and it produces the desired results and presents a pleasing appearance. SPECIAL PROTECTION FOR ROCK SLOPES 135

The exposed surface designated by the Engineer to receive this type of treatment shall be carefully examined to determine the installation procedure which will be necessary to conform to the reinforcing details shown on the plans.

The area to be treated shall be cleaned of all loose scaly rock or soil fragments by the use of pressurized water and air jets or other approved means as directed by the Engineer.

Anchorage of the reinforcement to the slope shall be accomplished by the use of the anchor bolts of the size and shape shown by plan details.

aggregates, and water pneumatically applied to the surface to be treated. (The mix shall be designed by the Contractor so as to produce a 28-day cylinder strength of 5000 psi {35 Mpa}). Placement of the pneumatic concrete shall be in accordance with the supplying producer’s recommendations, provided the method used produces the desired results and presents an acceptable appearance. (Note - It is not the intent of this specification to require a uniform surface, but to provide a fairly uniform layer of concrete of not less than the depth shown on the plans, which in general parallels the surface being treated.)

217.04Method of Measurement

The measurement for rock bolts will be the linear feet {meter} of the specific size designated by the Engineer, complete in place and accepted.

The seam sealing material will be measured in cubic yards {cubic meters}, complete in place. The volume of material actually placed will be computed from measurements of the actual length, width, and depth of the excavated seam opening. No allowance will be made for the replacing of material removed beyond the depth directed.

The Asphalt Surfacing material will be measured in gallons {liters}.

The measurement of the Pneumatic Concrete Blanket will be measured in square yards {square meters}, computed from the areas actually ordered treated. No allowances will be made for material placed outside of the designated areas nor for crevices, etc., required to be filled in order to obtain a continuous blanket over the area.

217.05Basis of Payment

The accepted length of rock bolts placed as directed will be paid for at the contract price per linear foot {meter}, complete in place, which price shall be full compensation for furnishing and installing all materials, including bolts, wedges, expansion shells, and accessories and for all equipment, tools, labor, and incidentals necessary to complete the work.

The accepted volume of seam sealant, measured as noted above, will be paid for at the contract unit price bid for the seam sealant which shall be payment in full for the item complete in place and shall include all excavation, disposal of excavation, materials, furnishing of the sealant, placing of the sealant, and for all equipment, tools, labor, and incidentals necessary to complete the work.

LANDSLIDE CORRECTIONS 136

The accepted volume of asphalt surfacing placed as directed will be paid for at the contract unit price bid per gallon {liter} which shall be payment in full for the bituminous material complete in place and includes furnishing the bituminous material, preparing the surface, transporting and heating of the material as required, placing the material in the areas designated, and for all equipment, tools, labor, and incidentals necessary to complete the work.

The accepted area treated under this item will be paid for at the contract unit price bid per square yard {square meter} which shall be payment in full for the pneumatic concrete blanket complete in place and includes preparation of the surface to be treated, furnishing all materials, installation of wire reinforcement, its accessories and anchor bolts, placement of the pneumatic concrete, and for all equipment, tools, labor, and incidentals necessary to complete the work.

217-A Rock Bolting, 1" {25 mm} Slotted - per linear foot {meter} 217-B Rock Bolting, 5/8" {16 mm} Headed - per linear foot {meter} 217-C Rock Bolting, 3/4" {19 mm} Headed - per linear foot {meter} 217-D Rock Bolting, 7/8" {22 mm} Headed - per linear foot {meter} 217-E Seam Sealant - per cubic yard {cubic meter} 217-F Asphalt Surfacing - per gallon {liter} 217-G Pneumatic Concrete Blanket, ___ inches {mm} thick - per square yard {square meter} LANDSLIDE CORRECTIONS

219.01Description

This Section shall cover the work of correcting a landslide in an existing roadway slope within the designated areas shown on the plans or directed by the Engineer, all in accordance with the details shown on the plans or noted in this provision.

219.02Materials

Materials furnished for use shall conform to the appropriate requirements of the Standard Specifications for the type work performed or noted herein.

A geotextile to be used as a special underdrain shall meet the requirements of plan details, AASHTO M 288 for Subsurface Drainage Geotextile, Class 2, and Section 810 of these specifications. The geotextile shall be selected from List II-3, of the Department's manual MSDSAR. Information concerning this list is given in Subarticle 106.01(f) and ALDOT-355.

The drainage pipe shall be PVC, Schedule 80, Type I or II, or Schedule 120 conforming to the requirements given in ASTM D 1785. The I.D. of the pipe shall be 1.5 inches {38 mm}, unless noted otherwise on the plans. The pipe shall be furnished in lengths suitable for use with the drilling equipment approved for use. The ends of the pipe shall be machined to provide a smooth wall slip coupling when joined using appropriate solvent welding material thus precluding the use of conventional slip couplings. Fittings necessary for the outfall connections outside the drilling limits shall be PVC, Schedule 80, Type I or II, or Schedule 120 fittings having a burst strength equal to or greater than the pipe noted herein. All pipe and fitting connections shall utilize solvent weld joints. Slotted pipe shall be furnished unless noted otherwise on the plans. Slotted pipe shall have two rows of slots circumferentially cut 120 degrees apart. The average configuration shall be 46 slots per row, per foot {300 mm} with a maximum 0.010 inch {0.25 mm} slot opening when used in silty or clay soil or 42 slots per row, per foot {300 mm} with a maximum 0.050 inch {1.3 mm} slot opening when used in a granular material. The configuration and the slot opening size shall be as shown on the plans. LANDSLIDE CORRECTIONS 137

Unless otherwise noted on the plans, rock buttress material shall be sandstone, limestone, dolomite, or granite free of dirt and debris. Rock buttress material shall have the physical properties for soundness, wear resistance and limited deleterious material content given in Section 814 for riprap. No more than 10 % of the rocks used for the main buttress construction shall have a weight over 500 pounds. At least 50 % shall have a weight over 80 pounds. No more than 10 % shall have a weight under 10 pounds. Oversize rocks may be allowed by the Engineer if spaced to permit filling and densification of the buttress. Rock used for choking shall pass a 4 inch {100 mm} screen and shall be no more than 10 % of the total rock required for the buttress. Acceptance of the gradation will be by visual inspection by the Engineer at either the source of the rock or at the project site. Any difference of opinion between the Engineer and the Contractor about the acceptability of the gradation shall be resolved by sampling and testing the rock in accordance with the method provided in ALDOT-239. The equipment, labor and sorting site for this procedure shall be provided by the Contractor at no cost to the Department.

219.03Construction Requirements

In general, the work necessary to correct a landslide is dependent upon the in-situ conditions and extent of damage existing at each site and will vary according to the details shown on the plans. Basic procedures may require any combination of the following work items:

as provided in Section 210 will apply unless otherwise noted by plan details.

provided in Section 606 or Special Underdrain as noted herein or detailed in the plans), or other methods of removing surface or ground water from the area.

Wall, or Rock Buttress) as noted by plan details to stop slippage of slope material.

ordinary or special borrow material as designated by the plans. This work requires the preparation of the surface by rolling or otherwise compacting the area as directed to receive the backfill material. The backfill material shall be placed in the same manner as prescribed in Subarticle 210.03(d) for embankment.

erosion control items provided in the contract.

The area designated for treatment shall be excavated to the depth indicated by the plans or directed to remove loose or otherwise unacceptable material. Removed material designated for reuse shall be stockpiled on approved areas; material not designated for reuse shall be disposed of as required in Article 210.05. Unless stockpile areas are designated on plan details, the Contractor shall provide, at his expense, satisfactory storage areas outside of the right of way limits.

appropriate item for such provided in the contract (reference Sections 610, 614, 615, 616, and 654).

the plan details.

size, shape, and content.

specifications, or as directed by the Engineer for size, shape, content, and type. If an aggregate blanket is required, the type and size of aggregate shall be as designated on the plans. The geotextile filter shall be placed in the manner and at the locations shown in the plans or as directed by the Engineer. At the time of installation, the geotextile shall be rejected if it has defects, rips, holes, flaws, deterioration, or damage incurred during manufacture, transportation, or storage. The geotextile shall be protected at all times LANDSLIDE CORRECTIONS 138

during construction from contamination by surface runoff and any geotextile so contaminated shall be removed and replaced with uncontaminated geotextile. Any geotextile damaged during its installation or during placement of backfill material shall be replaced by the Contractor at no additional cost to the State. The work shall be scheduled so that 14 days does not expire between placement of the geotextile and the covering of the geotextile with backfill. Backfill aggregate shall not be dropped on the geotextile 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 geotextile before dumping of any stone. The combination of drop height for stone and sand cushion layer thickness to be approved must be demonstrated to not puncture or damage the geotextile. No measurement or separate payment shall be made for a sand cushion layer placed for the purpose of allowing an increased drop of stone. Any damage to the geotextile during placement of aggregate shall be corrected prior to proceeding with the work.

shown on the plans or directed.  Horizontal drains shall cover the work of drilling appropriate size horizontal holes (angle and slope designated on plans) into backslope or frontslope and the installation of a designated size of slotted PVC drainage pipe to facilitate drainage of ground water.  The installation procedure requires the holes be drilled with rotary drilling equipment capable of providing 3 inch {75 mm} to six inch {150 mm} diameter holes up to 600 feet {180 m} in length to the designated lines and grades through soil and rock formations.  The drilling equipment shall allow the installation operation to be accomplished by inserting the plastic drain inside the drill hole the full length of the drill hole.  The installation operation of the drain pipe shall be done in such a manner that the drain pipe will be cemented together where necessary to form a continuous tube and will not be telescoped or damaged to the extent that its drainage efficiency will be impaired when completed.  The entrance end of the pipe shall be plugged with a rounded or pointed extension. The space between the drilled hole and the pipe shall be tightly plugged with earth for a length of at least 2 feet {600 mm} at the outlet end of the hole.  Water used for drilling and water developed during drilling operations shall be disposed of by the Contractor in such a manner that no damage will result to the work.  Unslotted PVC pipe approximately 10 feet {3 m} in length, shall be provided at the mouth of the drain to collector structure.

for as provided in the appropriate Section of the Specifications.

requirements:

The construction, in general, consists of the excavation of a trench, preparation of a bedding to receive a rock buttress and the construction of a rock buttress to the line, grades, and slopes detailed on the plans.

The excavation necessary to prepare the trench to the line, grades, slopes, and section shown on the plans or directed shall be classified and paid for under the Item of Unclassified Excavation or as provided on the plans.

The preparation of the trench bed shall be as detailed on the plans. Special bedding, if required, will be noted on the plans. Materials used in the special bedding shall conform to the specified sections of the Standard Specifications and will be paid for under the appropriate pay item for the materials used. LANDSLIDE CORRECTIONS 139

The rock buttress shall be placed in the prepared trench to the slopes shown on the plans or directed by the Engineer. Choking material shall be provided when needed to sufficiently fill the voids to allow for traversing by truck or as a filter layer between the rock buttress and any required embankment materials. Densification of the rock backfill will be required as directed by the Engineer, but density testing will not be required. Furnishing of the rock for the construction of the buttress shall be the responsibility of the Contractor. If permission is given to use any material outside regular excavation limits within the right of way, it will be paid for only once under the appropriate pay item provided by this Section.

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 geotextile. Anchoring of the terminal ends of the geotextiles shall be accomplished through the use of key trenches or aprons at the crest and toe of the back slope of the buttress or as specified on the plans. Successive geotextile sheets shall be overlapped in such a manner that the upslope sheet is placed over the downslope sheet or upstream over downstream. 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}. 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 no additional cost to the State. The geotextile shall be joined by either sewing or overlapping as outlined in Article 608.05 of these specifications. 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 under water where the overlap shall be a minimum of 3 feet {1 m}. A geotextile patch placed over a damaged area shall be extended 3 feet {1 m} beyond the perimeter of the tear or damage.

Restoration of slide slope (front or back) shall consist of preparing the area to receive the replacement material by the shaping and compaction of the area as prescribed in Subarticle 210.03(d) for embankments. The material in place shall be compacted as noted in the plan details or directed by the Engineer. The backfill material may be the material previously removed, ordinary borrow, or special backfill material of the type designated in the plans or proposal. Said backfill shall be placed in layers and compacted as prescribed in Section 210 or noted by plan details. Erosion control items provided in the plans shall be used to re-establish the ground cover damaged or destroyed by the landslide or the restoration work.

219.04Method of Measurement

Construction items not specifically provided in this Section will be classified, measured, and paid for under the respective pay items for such work provided in the contract.

The item of Rock Buttress for Landslide Correction, when provided in the plans or proposal, will be the weight {mass} of rock used in construction of the buttress, measured on approved scales. Measurement of any special bedding, if required, will be as specified for the respective pay item used for bedding.

The item of Special Underdrain, when provided in the contract, will be measured in linear feet {meters} of each special type detailed in the plans, along the center of each line or lateral, center to center of junctions and/or fittings. LANDSLIDE CORRECTIONS 140

The item of Special Filter Blanket, when provided in the contract, will be measured in square yards {square meters} to the nearest 0.1 square yard {0.1 m²}, complete in place, for the material placed and accepted.

Horizontal drains will be measured by the linear foot {meter} of drainpipe installed in the holes drilled, including the extension necessary to discharge into the collector structure.

contract, the material ordered and accepted will be measured in tons {metric tons} on approved scales.

provided in the contract, the accepted volume of backfill will be measured in cubic yards {cubic meters} complete in place by the cross section and average end area method. Cross sections shall be taken of the material in its original position, whether from a borrow pit, stockpile, or other approved source, before placing of the backfill and re-cross sectioned after placing the backfill. The volume computed between these cross sections shall be the volume of backfill.

219.05Basis of Payment

the accepted weight {mass}, measured as noted above, will be paid for at the contract unit price bid. Said contract unit price bid shall be payment in full for furnishing and/or producing material, royalties, loading, hauling, placing, consolidating, shaping, and for all equipment, tools, labor, and incidentals necessary to complete the work.

contract unit price bid per linear foot {meter}, which shall be full compensation for the underdrain complete in place. Said unit price includes excavation of the trench, backfill and compaction thereof, furnishing and installation of any pipe, fittings, geotextile filter, or filler necessary thereto, furnishing and placing of a connection to an outfall pipe or collector structure, the disposal of excess material, and for all tools, equipment, labor, and incidentals necessary to complete this item of work.

contract unit price bid per square yard {square meter}, which shall be full compensation for the item complete in place and includes the furnishing of all materials, preparation of the area to receive the filter blanket, installation of the blanket and for all equipment, tools, labor, and incidentals necessary to complete this item of work.

contract unit price per linear foot {meter}, which shall be full compensation for furnishing and installation of the drains complete in place and connected to the collector structure. Said unit price includes full compensation for furnishing all materials, services, equipment, tools, labor, and incidentals necessary to complete this item of work.

noted above, will be paid for at the appropriate unit price bid per ton {metric ton} or cubic yard {cubic meter}, complete in place, which shall be full compensation for the furnishing of the type material designated for preparation of the area to be treated, loading, hauling, placement, compaction, and dressing of the area to the designated slope and includes all equipment, tools, labor, and incidentals necessary to complete this item of work.

219-A Rock Buttress for Landslide Correction - per ton {metric ton} 219-B Special Underdrain ___ inch {mm} Diameter - per linear foot {meter} 219-C Special Filter Blanket * - per square yard {square meter} 219-D Horizontal Drain ___ inch {mm} Diameter - per linear foot {meter} 219-E Special Backfill for Landslide Correction - per ton {metric ton} 219-F Special Backfill for Landslide Correction - per cubic yard {cubic meter} * Specify either Aggregate or Geotextile.