529RETAINING WALL

402

construction requirements shall be shown on the details of the wall submitted by the Contractor. The details of the wall will be distributed by the Engineer for inspection of the installation of the wall.

All precast and masonry concrete items shall meet the requirements given in Section 831. All precast and masonry concrete items shall meet the material requirements established by the ALDOT through the submittal and approval of wall designs, material requirements and details.

529.03Construction Requirements

The Contractor shall have the following four options for the construction of a retaining wall if the required type of wall is not shown on the plans:  ALDOT designed cast-in-place reinforced concrete retaining wall;  Contractor designed cast-in-place reinforced concrete retaining wall;  reinforced mechanically stabilized earth (MSE) retaining wall;  gravity wall. MSE and gravity walls shall be designed and fabricated by, or under the technical supervision of an ALDOT approved supplier. Approved ALDOT MSE walls systems are shown in the "Material, Sources and Devices with Special Acceptance Requirements" manual, List II-22, “MSE Wall Systems”. Approved ALDOT gravity walls systems are shown in List II-28, "Gravity Wall Systems". Information concerning these lists is given in Subarticle 106.01(f) and ALDOT-355.

The Contractor shall submit descriptions of the retaining wall projects completed in the last three years to serve as evidence of the capability to construct the chosen wall system. The descriptions of the retaining wall projects shall contain names and telephone numbers of owners’ representatives who can verify the Contractor’s participation on those projects. These descriptions shall be submitted with the "wall installation plan" and will be evaluated by the Engineer.

The submittal of the design and details of a retaining wall is required if the details of the retaining wall are not shown on the plans. The Contractor shall submit Working Drawings in accordance with Article 105.02. The contractor shall also submit a Wall Installation Plan that includes:

installation;

to the reinforcement during subsequent backfill placement. The design calculations shall include an analysis of the internal and external stability of the wall and all structural connection details of the wall. The design shall be in conformance with the requirements given in the current AASHTO Standard Specifications for Highway Bridges as amended by interim revisions. The Engineer will not approve the submittal but will review it to make sure that it is sufficiently complete to allow the construction of the wall. s. Any proposed modification of the installation plan during construction shall be submitted to the Construction Engineer for review and distribution.

The Contractor shall perform the excavation in a manner that will prevent damage to adjacent structures and maintain the stability of the ground adjacent to the excavation. Excavated material that remains after the construction of the wall shall be used in the formation of the embankment, roadbed, base layers, shoulders, slopes, bedding, backfill for culverts, and for other purposes as allowed or directed by the Engineer. The material shall be suitable for the use that is allowed or directed by the Engineer. Excavated material that cannot be used as a part of the construction in other areas of the project shall be disposed of in accordance with the requirements given in Section 210 for the disposal of surplus material. RETAINING WALL 403

ALDOT designed Cast-In-Place Walls shall be constructed in accordance with the details shown on Sheets 1 through 4, in ALDOT Standard Drawing – Retaining Walls 0’ to 34’ Heights - . Concrete for cast-in-place reinforced concrete retaining walls shall be furnished and placed in accordance with the requirements given in Section 501. Reinforcing steel shall be furnished and placed in accordance with the material and construction requirements given in Section 502. All other materials shall be installed in accordance with the details shown on the standard wall details or the approved wall details.

The Contractor shall construct the mechanically stabilized earth (MSE) retaining wall in accordance with the details shown on the Contractor's submittal of the MSE wall that is distributed by the Engineer.

The Contractor shall construct the gravity wall in accordance with the details shown on the Contractor's submittal of the gravity wall that is distributed by the Engineer.

A drainage layer of backfill is required where there are weepholes. The drainage layer shall be free draining material placed full length along the back face of the walls at the line of weepholes. The drainage layer shall not be less than 1 foot {300 mm} wide and 1 foot {300 mm} deep.

Unless shown otherwise on the plans, MSE and gravity walls shall be built using the concrete finish provided by the manufacturer.

529.04Method of Measurement

Compensation for retaining walls will be made for the number of square feet {square meters} within the limits of payment shown on the plans. (The Engineer will not conduct field measurements of the wall for the purposes of payment, other than for Partial Payments under Article 109.07.) The limits of payment will be the following:  top of the wall;  bottom of the wall (bottom of leveling pad or footing where the bearing capacity is shown);  beginning and end of the wall. The limits for payment shown on the plans will not be altered unless directed by the Engineer in writing. All portions of the wall, except barrier rails, constructed outside the limits for payment shown on the plans will be considered integral and subsidiary to the construction of the wall and will not be measured for payment. Reinforced concrete barrier rails at the top of the wall will be measured and paid for under other items of work. All other items of work, including but not limited to selected backfill material for all components of the wall, the furnishing and installation/construction of all footings/leveling pads, copings, caps, reinforcing strips, reinforcing mesh, permanent and temporary facing shall be included in the contract price for the retaining wall and will not be measured separately for payment. The cost of all excavation within 4 feet {1.3 m} of the front face (top of wall to bottom of footing) of the wall and all excavation behind the wall shall be included in the square foot contract price for the wall. Separate payment will not be made for the use or disposal of the excavated material that remains after the completion of the construction of the wall. Excavation beyond 4 feet {1.3 m} from the front face of the wall that is required for roadway construction will be paid for under other items of work.

529.05Basis of Payment

The retaining wall will be paid for at the contract unit price per square foot {square meter} which shall be full compensation for all required designs and submittals and for furnishing all materials, fabrication, erection, construction, excavation, utilization and disposal of surplus excavated material, furnishing and placing selected backfill material, equipment, tools, labor, and incidentals necessary to complete this item of work.

ROADWAY PIPE CULVERTS 404

529-A Retaining Wall * - per square foot {square meter} * Retaining Wall Identification and Supplemental Description, if required. (i.e. Number 1, Number 2, MSE Wall Number 3, etc.) ROADWAY PIPE CULVERTS

530.01Description

This Section shall cover the work of furnishing and installing pipe type culverts of the size, shape, wall thickness, type material, and appropriate strength designated on the plans or in the proposal. The installation shall be at the locations shown on the plans or designated in conformity with the lines and grades shown by the plans or designated by the Engineer. The work shall include the furnishing and construction of such joints, cuttings, and connections to other pipes or structures as may be necessary to complete the work as shown on the plans or directed. This Section shall also cover the work of furnishing and installing pipe culverts by the jacking (boring) method of construction. Unless specifically authorized in writing by the Engineer, jacking (boring) shall be used only at the locations shown on the plans. This type of pipe installation will be paid for under Pay Item 530-C. The following abbreviations will be used: Concrete Pipe P.C. for plain concrete R.C. for reinforced concrete Corrugated Metal C.M. for any acceptable corrugated metal pipe covered by these specifications Protective Coating C. for any protective coating of metal pipe allowed by these specifications Paved Invert P.I. Corrugated Steel C.S. for Plain Corrugated Steel C.C.S. for Coated Corrugated Steel C.C.S.P.I. for Coated C.S. Paved Invert Corrugated Aluminum C.A. for Plain Corrugated Aluminum C.C.A. for Coated C.A. C.C.A.P.I. for Coated C.A. Paved Invert Concrete Lined C.L. Unless a specific type of pipe is designated by the plans or proposal, the Contractor may use one of the optional types of pipe shown by the plans or proposal. However, an installation, once started, shall be made with the same type of pipe throughout unless specifically designated otherwise by plan details, or directed in writing. The Contractor, at his option, may furnish a stronger grade pipe than specified provided no additional cost is incurred by the State for such installation. The Contractor shall also have the option to use Horizontal Elliptical (H.E.) Pipe in lieu of Concrete Arch Pipe provided the H.E. pipe equals or exceeds the Arch pipe in strength and equivalent opening. If the Contractor elects to use H.E. pipe, he shall still be paid under the Pay Item for which the H.E. pipe replaces.

530.02Materials

Materials furnished for use shall conform to the appropriate provisions of Division 800, Materials, with specific reference made to Sections 831 and 854 and the following:  Section 846 - Pipe Culvert Joint Sealers  Section 850 - Roadway Pipe If H.E. pipe is used as outlined in Article 530.01, the pipe shall meet the requirements of AASHTO M 207 {M 207M}. The test reports shall also state the size and class of Arch pipe for which the H.E. pipe is substituted. Concrete pipes furnished for jacking (boring) shall be smooth pipes without bells. Unless shown otherwise on the plans, smooth steel pipe furnished for jacking (boring) shall be manufactured from steel having a minimum yield strength of 36,000 psi {250 MPa}. The pipe shall be fabricated in sections for welded field joints. The Contractor shall select the wall thickness of the pipe consistent with his operation; however, the minimum wall thicknesses shall be as follows:

ROADWAY PIPE CULVERTS 405

30 inch {750 mm} and smaller diameter 3/8 inch {9.5 mm} 36 inch to 42 inch {900 mm to 1050 mm} diameter 1/2 inch {12.7 mm} 48 inch {1200 mm} and larger diameter 5/8 inch {15.8 mm} The pipe shall be coated inside and outside with at least one shop coat of an approved primer paint and one shop coat of asphaltum paint. Other approved protection material may be used if approved by the Department.

530.03Construction Requirements

Pipe shall be laid only in the presence of the Engineer or his authorized representative, and shall not be covered until approved. Pipe installed contrary to this requirement will be rejected and shall be replaced by the Contractor without additional compensation. Precast concrete pipe will be evaluated at delivery and any time prior to installation according to the criteria in AASHTO R 73.

The pipe shall be laid with ends abutting and with not more than a 1 inch {25 mm} variation from established alignment at the vertical centerline or from grade at the flowline. The Engineer will provide in the designated grade sufficient camber to prevent development of sag or reverse slope due to foundation settlement under embankment load.

The Contractor shall extend existing pipe culverts using the same construction methods and materials required for the installation of new pipe culverts. A pipe that extends from an existing manhole, inlet, or junction box, and a pipe that is extended from the installation of a collar shall be a pipe extension. A pipe that is extended from the installation of a new junction box is not a pipe extension and will be considered to be just a roadway pipe.

The fill height for determining the class or wall thickness of pipe will be the distance from the elevation of the top of the pipe to elevation at the top of the base course.

In the installation of coated, paved invert, or concrete lined pipe, care shall be taken not to damage the protective coating, lining, or the paved invert. Any damage shall be repaired with approved material or replaced as directed.

Where aluminum pipe is to be connected to galvanized or other metal pipe, the surfaces shall be separated from contact by an approved type of gasket.

Any damage to galvanizing shall be painted with two coats of approved galvanizing repair paint, Section 855, or approved zinc spelter paint.

Details of trenching and bedding of pipe will be shown on the plans. All pipe 48 inches {1200 mm} or less in horizontal diameter shall be laid in a trench extending at least 1 foot {300 mm} above the elevation of the top of the pipe. For such pipe, where the ground surface is less than 1 foot {300 mm} above the elevation of the top of the pipe, the Contractor shall first construct and compact the fill to a minimum height of 1 foot {300 mm} above the elevation of the top of the pipe and for a minimum distance of 10 feet {3 m} in each direction from the outside edge of the pipe. The trench shall then be excavated as specified in Section 214. Caution shall be used to keep the sides of the trench vertical and to specified dimensions. Extra wide excavation to accommodate pans or other unsuitable excavating equipment will not be permitted. Excavation above subgrade will be classified and paid for as roadway excavation. Excavation below subgrade will be classified and paid for as structure excavation except that no payment will be made for excavating that part of a fill section placed more than 1 foot {300 mm} above the top of the pipe. For pipe over 48 inches {1200 mm} in horizontal diameter, trenching will be required only where the original ground is above the elevation of the bottom of the pipe, and backfilling shall be performed as specified in Item 210.03(d)2. ROADWAY PIPE CULVERTS 406

Should the material encountered at the elevation of the trench floor not be suitable to support the structure, removal of unsuitable material and placement of foundation backfill shall be performed and will be paid for as specified in Section 214. Temporary drainage necessary for proper installations shall be provided by the Contractor without additional compensation.

All pipe culverts placed under this Section shall be placed in a prepared bed of one of the types noted herein. Unless otherwise provided, a Class "C" Bedding shall be used.

The pipe culvert shall be bedded in a continuous concrete cradle conforming to plan details.

The pipe shall be bedded with ordinary care in a prepared foundation bed to a depth of not less than 30 percent of the vertical diameter of the pipe plus 4 inches {100 mm}. The thickness of the foundation bed shall be a minimum of 4 inches {100 mm} in thickness and shall be shaped to fit the pipe for at least 15 percent of the vertical outside diameter. Recesses in the trench bottom shall be shaped to accommodate the bell of the pipe when bell and spigot type pipe is used. "Ordinary" care in this Article shall mean sufficient care to ensure that the permissible variations listed in Item 530.03(a)2 will not be exceeded. The bedding material shall be sand or an approved selected sandy soil.

The pipe shall be bedded with ordinary care in a loosened soil foundation shaped to fit the lower part of the pipe exterior with reasonable closeness for at least 10 percent of its overall height. Use of a template for shaping will not be required. The shaped foundation shall be loosened by pulverizing the soil to a minimum depth equal to 0.125 times the diameter of the pipe or 3 inches {75 mm} maximum. "Ordinary care" in this Article shall mean sufficient care to ensure that the permissible variations listed in Item 530.03(a)2 will not be exceeded. Where ledge rock, rocky or gravelly soil, hard pan, or other unyielding foundation material is encountered at a culvert site, the pipe shall be bedded as follows: The hard unyielding material shall be excavated below the elevation of the bottom of the pipe, or pipe bell, for a depth of at least 12 inches {300 mm}, or 1/2 inch for each foot {40 mm for each meter} of fill over the top of the pipe, whichever is greater, but not more than 24 inches {600 mm}. Payment for this material shall be made under Structure Excavation. The width of the excavation shall be 12 inches {300 mm} greater than the outside diameter or span of the pipe and shall be filled with selected fine compressible material, such as silty clay or loam taken from selected grading operations or areas beyond the right of way and paid for as Foundation Backfill. This material shall then be lightly compacted in 6 inch {150 mm} compacted lifts and shaped as specified above.

Proper facilities shall be provided for lowering the sections of pipe into the prepared trench. The pipe laying shall begin at the downstream end of the pipe line. The lower segment of the pipe shall be in contact with the shaped bedding throughout its full length. Bell or groove ends of rigid pipe and outside circumferential laps of flexible pipe shall be placed facing upstream. Flexible pipe shall be placed with longitudinal laps or seams at the sides. Paved invert pipe shall be laid so that the longitudinal center line of the paved segment coincides with the designated flow line. All flexible (C.S. or C.A.) pipes 48 inches {1200 mm} or larger in diameter shall be shop elongated or field strutted except for arch pipe and concrete lined pipe. Details for field strutting shall be as provided by the plans and shall be accomplished prior to placing any embankment adjacent to the structure. Only horizontal ties shall be used in strutting paved invert pipe. The pipe shall be laid in the trench with the separate sections firmly joined together and with outside laps of circumferential joints pointing up stream and with longitudinal laps on the sides. Any metal in joints which is not protected by galvanizing shall be coated with suitable asphaltum paint. If headwalls are to be placed, the ends of the pipes laid on a skew shall be neatly cut off parallel with the centerline of the highway and flush with the outside face of the headwalls. ROADWAY PIPE CULVERTS 407

Where multiple lines of pipe are used, they shall be spaced far enough apart to permit thorough tamping of earth between adjacent lines. To this end the adjacent sides of circular pipe shall be at least 0.5 times the nominal pipe diameter apart, or 3 feet {1 m}, whichever is less. Spacing for arch pipe shall be as shown on the plans.

Rigid pipe may be of bell and spigot, tongue and groove, or other approved design unless a specific type is specified(joint configuration for round rigid pipe shall accommodate the use of a rubber gasket seal). The method of joining pipe sections shall be such that the ends are fully entered and the inner surfaces are reasonably flush and even. Joints for non-round rigid pipe shapes shall be sealed with bituminous plastic cement, preformed flexible sealant, rubber gaskets, (when joint configuration can accommodate the use of a rubber gasket), or other type sealers that may be approved. Joints shall be thoroughly cleaned before being sealed and shall be sealed for the full circumference of the joint unless otherwise directed. When joining round R.C. pipe, only rubber gaskets shall be used unless otherwise approved by the Engineer. When bituminous plastic cement is used, the interior surface of the hub, beginning at the lip of the normal interior surface of the pipe, shall be coated with a layer of sealing material that will cover at least 0.33 times the distance, measured along the surface of the hub, parallel to the normal length of the pipe. The thickness of the mastic placed shall be such that it will provide a uniform seal between the edges of the pipe sections being joined (approximately 1/2 of an inch {10 mm} on the inside shoulder of the hub and approximately 1/8 of an inch {3 mm} of material on the remaining area to be covered). When Pre-formed flexible sealant is used it shall be placed according to the manufacturers requirements. No joint shall be considered satisfactory when the space between the edges of the pipes being joined exceeds 1/2 of an inch {10 mm} for more than 0.33 times the circumference of the pipe. The inside of the joint shall be wiped and finished smooth. Rubber or other types of gaskets shall be installed as recommended by the manufacturer, rubber gaskets installation shall include gasket equalization and application of lubricant.

Flexible pipe shall be firmly joined by coupling bands of an approved type. Joints shall be thoroughly cleaned before being joined and shall be sealed for the full circumference of the joint with an approved sealer unless otherwise directed.

All pipe shall be inspected before any backfill is placed. Any pipe found to be out of alignment, unduly settled, or damaged shall be taken up and relaid or replaced.

After the pipe has been installed, the pipe trench shall be backfilled with the best of the suitable material excavated from the trench; if none of this excavated material is suitable, material from the roadway shall be used and paid for as such, or suitable material shall be hauled in and used with payment being made under the classification of the material ordered used. For backfilling above a point 1 foot {300 mm} above the top of the pipe, material from the trench may be used unless unsuitable for embankment. Backfilling will not be permitted until authorized by the Engineer.

The backfill material shall be compacted at near optimum moisture content, in layers not exceeding 6 inches {150 mm} compacted thickness, to a density of not less than 95 percent of AASHTO T 99 density by methods detailed in Section 210. Mechanical tampers shall be used unless another method of compaction is approved in writing; inundation or jetting will not be permitted unless specified on the plans. Care shall be exercised to thoroughly compact the backfill under the haunches of the pipe and to ensure that the material is in intimate contact with the pipe. The ROADWAY PIPE CULVERTS 408

backfill shall be brought up evenly in layers on both sides of the pipe for its full length until the trench is filled or up to subgrade elevation if the trench is in cut. When the plans require stone or aggregate backfill, the material will be compacted (in layers not exceeding 6 inches) to the satisfaction of the Engineer. Mechanical tampers or vibrator plate compactors shall be used unless another method of compaction is approved in writing. When the top of the pipe is exposed above the top of the trench, embankment material shall be placed and compacted for a width on each side of the pipe equal to at least twice the horizontal inside diameter of the pipe, or 12 feet {4 m} whichever is less. The embankment on each side of the pipe, for a distance equal to the horizontal inside diameter of the pipe, shall be of the same material and compacted in a normal manner. All pipe, after being bedded and backfilled as specified in this Section, should be protected by a 3 foot {0.6 m} cover of fill before heavy equipment is permitted to cross during construction of the roadway.

The Contractor shall exercise necessary care in installing and backfilling pipe, and it shall be his responsibility to see that the pipe is not damaged by lateral forces during backfilling, by heavy loads operating over the pipe, or by other causes. All damaged pipe shall be replaced or repaired by the Contractor at his own expense at the option of, and to the satisfaction of, the Engineer. Any pipe not true to designated alignment and grade within specified tolerances, or any pipe that shows settlement due to faulty installation, shall be relaid or replaced by the Contractor without additional compensation. Any pavement that settles or breaks over a pipe shall be replaced or repaired by the Contractor, at the option of the Engineer, without additional compensation. All pipe lines shall be thoroughly cleaned out prior to final acceptance.

For pipe sizes less than 42 inches {1050 mm} in diameter, the tunneling equipment used in the jacking (boring) operation shall have a steerable cutting head equipped with a grade indicator. For pipe sizes 42 inches {1050 mm} in diameter and greater, the tunneling equipment used in the jacking (boring) operation shall be a laser-guided tunnel boring machine (TBM). The use of unguided auger-type boring equipment will not be permitted. The tunneling equipment shall also be equipped with a closed-face cutting head or otherwise equipped to prevent unstable soils from entering the tunnel. The tolerance for grade control shall be plus or minus 0.020 feet per 100 feet {20 mm per 100 m} of length. The tolerance for line shall be 0.20 feet per 100 feet {200 mm per 100 m} of length. Smooth steel pipe shall be continuously welded at joints to form a rigid, watertight installation. Any coating disturbed during the welding procedure shall be repaired, both inside and outside, in a manner acceptable to the Engineer.

530.04Method of Measurement

The accepted length of pipe culverts laid as ordered will be measured along the bottom flowline, or invert, of the pipe complete in place. Measurements will be made between inside walls of designated structures (junction boxes, inlets, etc.) and along the centerline of the flowline of special fittings (elbows, wyes, etc.). The above applies to round or arch, beveled or unbeveled, pipe. However, in no case will measurement be made for lengths greater than the sum of the nominal laying lengths of the pipe sections used or for lengths greater than the length of culvert ordered by the Engineer. No separate measurement for payment will be made for the excavation and/or backfill volume needed to reroute water for temporary drainage which might be necessary for the proper installation of the pipe or to perform the imperfect trench method of installation. Structure excavation and foundation backfill, including that necessary for the installation of roadway pipe of a temporary nature, when ordered will be measured and paid for as prescribed in Section 214. The accepted length of pipe culverts jacked (bored) as ordered and acceptably installed will be measured along the bottom flowline, or invert, of the pipe complete in place. The limits of measurement of jacked (bored) pipe under this Section will not exceed the length along the flowline of the pipe from face to face of the boring pit or the length shown on the plans, except as otherwise directed in writing by the Engineer, whichever is less. There will be no separate measurement for payment for structure excavation and foundation backfill for pipe installed by the jacking (boring) method.