504Section 504

504.01 This work consists of constructing a Concrete Panel Facing Mechanically Stabilized

Earth (MSE) Retaining Wall System at the locations and to the lines and grades shown on the plans. Either metallic or geosynthetic reinforcement (woven fabrics or geogrids) as specified in this specification may be used as MSE reinforcement in the reinforced struct ure backfill zone. The retained structure backfill zone is the structure backfill retained by the reinforced structure backfill zone as shown on the plans. This work consists of constructing a permanent soil nailed retaining wall (also referred to as ground nail wall), with complete details starting in subsection 504.2 3. MATERIALS

504.02 Shop Drawings. The Contractor shall submit one electronic submittal of shop drawings

and certified material test reports for review before construction of the wall. See subsection 504.07, for a complete list of submittal requirements. Shop drawings shall be submitted per subsection 105.02. The shop drawings shall provide the details necessary to demonstrate compliance with the Contract, including :

11.10.6 4.3b -2 using independently certified test results.

504.03 Backfill. Unless otherwise specified on the plans, wall backfill material in the

reinforced structure backfill zone and the associated trapezoidal retained structure backfill zone shall conform to the requirements for Structure Backfill (Class 1) of Section 206. For reinforcement tensile stress and associated pullout, a friction angle of 34 degrees shall be assumed for Structure Backfill (Class 1). Structure Backfill (Class 1) sh all be considered to be non-aggressive soil for corrosion and durability computations. All reinforcing elements shall be designed to ensure a minimum design life of 75 years for permanent structures.

504.04 Leveling Pad . Concrete for the leveling pad shall be Concrete (Class D) conforming to

the requirements of Section 601. Unless specified on the plans, the maximum vertical step shall be no greater than 36 inches. The leveling pad shall be reinforced as shown on the pl ans. When the toe of wall is founded on slope steeper than 1.5 (H) to 1 (V), the leveling pad shall be constructed with reinforced concrete with same reinforcing schedule as at its steps. Leveling pad concrete shall be cured for at least 12 hours before placement of the concrete panels.

504.05 Geomembrane and Joints . A geomembrane shall be installed on all walls at the top of

the reinforced structure backfill zone and retained structure backfill zone to intercept surface runoff and prevent salt penetration into the backfill of the wall as shown on the plans. The geomembrane shall meet the requirements of subsection 712.07 for geomembrane and be LLDPE with a minimum thickness of 30 mils. It shall be spliced with a dual track field seamed joint per ASTM D4437 and ASTM D5820. For small local coverage areas, less than 30 square feet, the membrane may be spliced using a 6 -inch minimum overlap and an adhesive or a single seam portable thermal welding tool, as suggested by the membrane manufacturer and approved by the Engineer. Unless otherwise shown on the plans, the membrane shall have a minimum coverage length measured perpen dicular to the wall face of at least the Pay Length for Geomembrane (PLG) as shown on the plans. The membrane shall be install ed with a slope between 20:1 (minimum) and 10:1 (maximum), as shown on the plans, from the block facing to a drainage system located at the cut or pre- filled slope as shown on the plans. The Contractor shall provide a site-specific working drawing that indicates sheet splices, pattern, slope, and daylight location. Before membrane installation, the working drawing shall be submitted by the Contractor and approved by the Engineer. The drainage system shall consist of a 12 -inch-wide geocomposite strip drain inserted into a slot in the geomembrane, at 10 -foot maximum spacing, that collects the water from the membrane and conveys it to a water collector system at the toe of the excavat ion slope as shown on the plans. The water collector system shall consist of a 4 -inch diameter perforated collector pipe surrounded by Filter Material Class B and wrapped with Class 1 Geotextile. A 4 - inch diameter non -perforated drainpipe , at 100- foot ma ximum spacing, shall be used to discharge the water in the water collector system out the face of the wall. Alternatives for the drainage system shown on the plans may be used by the Contractor. A detailed layout of this equivalent water collection system shall be provided by the Contractor and approved by the Engineer. 504.06 504-6 For tiered walls, a geomembrane shall be installed between the top of the bottom wall and the toe of the top wall as shown on the plans.

504.06 Pre-Cast Concrete Panel Facing Unit and Panel Joint Material . The pre -cast concrete

panels shall conform to the requirements shown on the plans and these specifications including the color, texture, dimensions and pattern. These facing units shall be factory made with an approved Class D or G Concrete and shall conform to the requirements of Section 601. The Contractor may elect to use an approved self -consolidating Class D or G Concrete. Pre- cast panels shall be cured per AASHTO M170.

504.07 Certifications, Calculations, and Testing Reports . The Contractor shall provide the

following reports, certifications, calculations, and checklists as needed to accompany the shop drawing submittal. The Contractor’s Engineer shall electronically seal all engineering calculations, as stated in subsections 504.02(f), 504.02(g), 504.02(j), 504.02(k), 504.07(e), 504.07(f), 504.07(g), and 504.07( h).

504.08 Hybrid or Smaller Panel MSE Wall Systems.

A hybrid system is one that combines elements of both externally and internally stabilized systems. An externally stabilized system uses a physical structure to hold the retained soil. The stabilizing forces of this system are mobilized either through the weight of a shape stable structure or through the restraints provided by the embedment of wall into the soil, if needed, plus the tieback forces of anchorages. An internally stabilized system involves reinforced soils to retain fills and sustain loads. Reinforcement may be added to either the selected fills as earth walls or to the retained earth directly to form a more coherent stable slope. These reinforcements can either be layered reinforcements installed during the bottom -to-top construction of selected fills or be driven piles or drilled caissons built into the retained soil. All this reinforcement shall be oriented properly and extend beyond the potential f ailure mass. Hybrid MSE wall systems may be used unless otherwise noted on the plans. Hybrid MSE wall systems are subject to the same design requirements for MSE walls and this specification. The shop drawings for the Hybrid MSE wall system shall include a combinatio n of design calculations and appropriate test results to demonstrate that it meets or exceeds the regular system. Hybrid MSE wall systems shall have a modular facing and be stabilized by a counterfort or a coherent mass such as interlocked wire basket sys tem. The Certifications, Calculations, and Testing Reports in subsection 504.07(e) are not required for Hybrid MSE wall systems. The facing to soil reinforcement connection test, subsection 504.07(c), may be waived only if the soil reinforcing spacing is less than or equal to 8 inches or the facing is secured and stabilized by hybrid components with primary reinforcement spacing less than 24 inches. The Contractor shall provide the following additional reports, certifications and calculations to accompany the shop drawing submittal for Hybrid MSE wall systems:

504.09 Approval and Qualifications of MSE Wall Installer . The job site wall foreman shall

have experience in construction of at least five transportation -related MSE walls within the last three years. Transportation related MSE walls are walls that carry or are adjacent to vehicular traffic and are constructed with MSE reinforcement in the reinforced structure backfill zone. The foreman shall have prior experience or adequate training on the products that the Contractor elects to use on the project. The resume and credentials of the foreman shall be submitted to the Engineer for approval before the Pre -construction Conference. The foreman shall be on the site for 100 percent of the time during which the work is being done.

504.10 Wall Test Segment. The wall test segment shall be the first segment of the wall

constructed. The wall test segment shall be constructed in the presence of the Technical Representative and the Engineer and shall include construction of each of the five elements listed in subsection 504.11. The minimum length of the wall test segment shall be 40 feet or the full length of the wall if less than 40 feet. A wall test segment shall be constructed for the first wall constructed from each wall product used on the project.

504.11 Technical Representative of Wall Product Supplier . The Contractor shall arrange for

a technical representative (Tech Rep) of the manufacturer of the selected wall products to be present during the construction of each wall test segment. If the selected wall products are supplied from different manufacturers, a Tech Rep from each wall pro duct shall be present. The Tech Rep shall be present for construction of the wall test segment and each of the following elements:

504.12 Facial Panel Quality Control, Placing Plan, and Daily Placement Logs. Before the

start of wall construction, the Contractor shall provide a panel- placing plan and shall supply daily placement logs to the Engineer weekly and at the completion of the wall. The daily placement log shall consist of an elevation view of the wall showing th e dates, number of panels placed, and the serial numbers of the panels placed. The panel quality control shall contain multiple submittals if required by subsections 504.07(g) and (h). Panels shall be labeled with a serial number for each panel and corresponding certification with one set of random samples tested for each 220 panels or 5,500 square feet of wall face. At least one certification with supporting test results is required for each wall. Test results will be reviewed and pre -approved by the Engineer before shipment. The Contractor shall coordinate and mark the panel and backfill placing sequence on the daily placement logs. The log serves as means for the Engineer to identify where each panel was placed.

504.13 Wall With Curved Alignments, Tight Curved Corners, and Sections Adjacent t o

Bridge Abutment. The Contractor shall provide a placement plan that shows curved layouts, special corner panel, sequence of panel placement, and construction offsets as recommended by the manufacturer. The Contractor shall install vertical slip joints as shown on the shop drawings for tight curved corners (8 -foot radius or less) and dissimilar foundations such as bridge abutments, to avoid panels with random cracks.

504.14 Excavation and Backfill. The base of leveling pad shall receive the same compaction

as cut area required by subsection 203.07. The Contractor shall report to the Engineer in writing density test results for any unsatisfactory bearing material that does not meet the minimum 90 percent compaction for walls less than 16 feet high and 95 per cent of AASHTO T 180 for walls higher than 16 feet. If the excavation for the placement of the leveling pad exposes an unsatisfactory bearing material, the Engineer may require removal and replacement of that material. The removed material shall be replaced with Structure Backfill (Class 1) compacted in conformance with subsection 206.03. The Engineer with the assistance of the geotechnical engineer of record will provide the limits including the depth of removal. As directed by the Engineer, and if required, Structure Backfill (Class 1) shall be reinforced with soil reinforcements in conjunction with wick drains and outlet pipes. The Contractor shall grade the foundation for the bottom of the wall for a width equal to or exceeding the limits of the Reinforcement Length (RL) plus 18 inches as shown on the plans. This graded area shall be compacted with an appropriate vibratory roller weighing a minimum of 8 tons for at least five passes or as directed by the Engineer. For cut wall with continuous seepage, phasing of foundation construction or a different drainage and foundation improvement plan may be necessary. The reinforced structure backfill zone and the retained structure backfill zone portion immediately behind the wall as defined on the plans shall be Structure Backfill (Class 1). Recycled asphalt, recycled concrete, and flow -fill material shall not be substituted for Structure Backfill (Class 1). Each compacted layer of backfill within a distance equal to the reinforcement spacing away from the back of the panels shall not exceed 4 inches. The triangular or trapezoidal portion behind the concrete panels and above the spill of backfill, as shown on the plans, shall be filled with 3/8- inch or larger crushed rock, filter aggregates with 504.15 504-10 filter fabric, or wall system specific fill as approved by the Engineer. Density tests behind and parallel to the wall in the triangular or trapezoidal portion above the backfill spill zone are not required. Each compacted layer of backfill shall be in even increments up to 8 inches thick. The fill and compaction operation shall start 3 feet from the wall back face and progress toward the end of the reinforcement. All Structure Backfill (Class 1) including fill material under the wall and on- site material as allowed by subsection 504.03 shall be compacted to a density of at least 95 percent of the maximum density according to AASHTO T 180. For on -site foundation material containing more than 30 percent retained on the 3/4- inch sieve, a method of compaction consisting of a conventional heavy vibratory roller starting with minimum 5 passes shall be used to establish the number of passes required to exceed the 95 percent T180. At least 6 inches of material shall be in place before operation of tracked vehicles over soil with reinforcement. Only power operated roller or plate compaction equipment weighing less than 1,000 pounds is allowed within 3 feet of the front of the wall f ace. The reinforcement shall not be connected to the wall until the compacted fill is at or slightly higher than the location of the connector. Backfill containing frost or frozen lumps shall not be used. Backfill that has been placed and becomes frozen shall be removed and replaced at the Contractor's expense. If cold weather conditions prevent the placement of Structure Backfill (Class 1), the Contractor may use Filter Material Class B as backfill without compaction at the Contractor’s expense and approved by the Engineer. The Contractor shall provide a test report, prepared and certified by an independent laboratory, that the internal frictio n angle of soil for the Filter Material Class B meets or exceeds that shown on the plans. The Contractor shall place additional panels including partial height panels and properly compacted fill material to return the finished grade to the plan elevations if settlement, as determined by the Engineer, has occurred. A final inspection before the installation of rail anchoring slab will be made after constru ction settlement, if any, has occurred or 30 days after the completion of the wall. The Contractor shall provide immediate temporary stormwater protection and wind erosion control at the end of each day during construction. If settlement occurs as the result of loss of backfill due to wind or water erosion, non -conforming backfill such as frozen fill or over -saturated fill, or if the backfill does not meet compaction requirements, the Contractor shall remove the backfill, wash the soil reinforcement, and bring the elevation to the finished grade at the Contractor's expense. Before final project acceptance, the Contractor shall repair all backfill losses due to wind and water erosion. To avoid the foundation of the leveling pad being washed out by rain, the area in front of the wall and around the leveling pad shall be backfilled as soon as practicable.

504.15 Reinforcement. Steel reinforcement shall be slack free and geosynthetic

reinforcement shall be slightly pre- tensioned. The minimum coverage ratio for geogrid reinforcement shall be 67 percent and the spaces between rolls shall be staggered between layers of soil reinforcement. The minimum coverage ratio for woven fabric reinforcement shall be 100 percent and an overlap between rolls is not required. Soil reinforcement shall not be cut to avoid obstruction unless shown on the shop drawings.

504.16 Leveling Pad . The foundation of the leveling pads shall meet the requirement of

subsection 504.04 for steel and concrete. The leveling pad shall be level within the tolerance of 1/8 inch for any two points along the length of a panel, and within 1/4 inch for any two points 10 feet apart. 504.17 504-11 Cushion or shimming material (expansion joint material, concrete mortar grout, roofing felt, or geosynthetic reinforcement) shall be used to support panels directly founded on the leveling pad. Before starting a new course of panels, the Contractor shall take steps to ensure that the wall elevations are matched at the neighboring panels. Cushion or shimming material shall be used to obtain necessary panel elevations at next leveling pad step. No more than two shims (each 3/16 inch thick) shall be required to level the panels on the leveling pad.

504.17 Wooden Wedges. Wooden wedges may be used to help to hold the panels at the

correct batter during the backfill operation. The wooden wedges shall be made from hard wood (such as oak, maple or ash). Wooden wedges shall be removed as soon as the precast panels above the wedged panels are completely erected and backfilled. There shall not be more than three rows of wooden wedges in place at one time. Panels that crack or spall due to failure to remove the wooden wedges shall be repaired or replaced.

504.18 Panel Facing. For walls that support a roadway, the wall layout line at the leveling

pad shall be set back and pre- measured with appropriate batter (5 to 8 percent) from the top of the panels according to the offset with respect to the centerline of the road. For walls adjacent to a roadway, the wall layout line at the leveling pad shall b e directly offset from the centerline of the road. An overall negative batter (wall face leaning outward) between the bottom and the top of the wall is not allowed. Unless otherwise noted on the plans for battered walls, the final wall face shall be vertical, or have a positive batter of not greater than 5 percent for construction control purpose. The surface of the wall face shall be tested with a 10- foot straightedge laid along th e surface in horizontal and vertical directions. Except as necessary for horizontal alignment of the wall, convex deviation of the wall face from the straightedge (belly wall) shall not be allowed, and concave deviation from the straightedge shall be less than 1/2 inch. Walls without a rail -anchoring slab, cast -in-place reinforced concrete coping with uniform exposed height is required to match the required finished elevations as well as to retain the panels’ lateral deformation. For walls with rail anchoring slabs, the top of panel elevations shall be within 8 inches of the bottom of the anchoring slab. Cast -in-place concrete or saw -cut partial height panels may be used to accomplish this. Where the geomembrane for drainage interferes with the continuation of reinforcement, the panels beyond the termination shall be reinforced with the same grade of additional soil reinforcing material to maintain the total amount of reinforcement per panel. To avoid leaking or soil erosion through the joint, a filter fabric at least 12 inches wide shall be glued to the panels behind all vertical joints. As shown on the plans, facing panels directly exposed to spray from deiced pavements and indirect windborne spray shall have three coats of water resistant or repellant concrete sealer applied to the front face of the wall before the wall is opened to traf fic. All damages to a completed wall or parts of a completed wall, including blemishes and discoloring of panels, shall be replaced or repaired before final payment is made. Sand blasting may be used if approved by the Engineer. 504.19 504-12

504.19 Fill under Leveling Pad. For walls requiring fill under the planned elevation of the

leveling pad, the Contractor may lower the elevation of the leveling pad as approved by the Engineer, except that the finished elevation at the top of the wall shall not be altered. As requested by the Contractor, and with the Engineer’s approval, the higher wall shall be redesigned wit h longer reinforcement length and revised reinforcement schedule. METHOD OF MEASUREMENT

504.20 MSE retaining walls will not be measured for payment in the field but will be paid for

by the calculated quantities shown on the plans for the five major components of the wall: structure excavation, structure backfill, concrete panel facing, mechanical reinforcement of soil, and geomembrane. The Contractor's construction of a system that requires increased or decreased quantities of any of the components to complete the wall to the dimensions shown will not result in a change in pay quantities. Exceptions will be made when field changes are ordered or when it is determined that there are discrepancies on the plans in an amount of at least plus or minus five percent of the plan quantity.

504.21 The accepted quantity will be paid for at the contract unit price per unit of

measurement for the pay items listed below: Payment will be made under: Pay Item Pay Unit Panel Facing Square Foot Structure excavation will be paid for under the Section 206 Pay Item Structure Excavation. Structure backfill will be paid for under the Section 206 Pay Item Structure Backfill (Class 1). Soil reinforcement will be paid for under the Section 206 Pay Item Mechanical Reinforcement of Soil. Geomembrane will be paid for under the Section 420 Pay Item Geomembrane. 504.22 504-13 Rail anchoring systems (slabs) at the tops of walls and leveling pads at the bottom of wall will be measured and paid for separately under the Section 601Pay Item Concrete and the Section 602 Pay Item Reinforcing Steel. Payment will be full compensation for all work and materials required to construct the concrete panel facing MSE wall. Miscellaneous items such as dual track welding of geomembrane, drainage ditches, rundowns, filter material, filter fabric, grout, pins, shimming material, 1/4-inch-thick expansion joint material, concrete coating and providing a technical representative will not be measured and paid for separately but shall be included in the work.

504.22 Panel Facing Payment Reductions. In this subsection, a “panel” refers to either a

concrete panel or a hybrid unit. Each of the following shall be considered a defect:

504.23 Soil Nail Wall. This work consists of constructing a permanent soil nailed wall (also

referred to as ground nail wall) as specified, and as shown on the plans. Temporary soil nail walls and the final facing are not covered in this specification. The work includes:

504.24 Materials shall meet the following requirements:

504.25 Soil Nails

504.26 Bearing Plates, Washers, Nuts, and Headed Studs.

504.27 Welded Wire Fabric. Welded Wire Fabric shall conform to AASHTO M55, AASHTO M221,

or ASTM A1064. CONSTRUCTION REQUIREMENTS

504.28 Contractor Qualifications. The Contractor shall provide on -site supervisors and drill

operators with experience installing permanent soil nails on at least 3 permanent soil nail retaining wall projects during the past 3 years totaling at least 10,000 square feet of wall face area an d at least 500 permanent soil nails.

504.29 Submittals. The following documents shall be submitted per subsection 105.02. No

work relating to soil nail wall construction including ordering materials shall be performed before the following submittals have been reviewed and reviewed by the Engineer.

504.30 Protection and Cleanup. During work operations, the Contractor shall take such

precautions as may be necessary to prevent shotcrete overspray, drill cuttings, equipment exhaust, oil, wash water, and other materials from defacing or damaging private and public property including adjacent landscaping per subsections 107.1 2 and 107.2 5. The Contractor shall furnish all equipment as may be necessary to handle wastewater and material from the operations and clean up all waste resulting from the operations. The Contractor is responsible for the stability of the highway facility and nearby structures.

504.31 Storage and Handling. Soil nail bars shall be stored and handled in a manner to avoid

damage, excessive bending, permanent deformation, or corrosion. Bars exhibiting abrasions, cuts, welds, weld splatter, corrosion, or pitting shall be replaced. Bars exhibiting damage to encapsulation or epoxy coating shall be repaired or replaced. Repaired epoxy coating areas shall have a minimum 0.012- inch-thick coating. Bars exhibiting damage shall be repaired or replaced at the Contractor’s expense.

504.32 Excavation. The Contractor shall be responsible for providing the necessary survey

and alignment control during the excavation for each lift, locating drill holes, and verifying limits of the soil nail wall installation. Before any excavation, surface water controls s hall be installed around the wall area as needed to prevent surface water , seepage, or springs from flowing within or into the excavation or as determined by the Engineer. The Engineer shall be notified 14 days before the beginning of excavation to allow scheduling of qualified representatives of the soil nail wall design professional engineer to observe the excavation and drilling as needed. The Engineer and the soil nail wall design engineer shall be contacted immediately if the Contractor encounters any ground conditions or materials during the excavation or drill ing that is not shown on the plan set or unanticipated seepage, springs, or other sources of groundwater to allow f or review of the design. The Contractor shall reference available Geotechnical Reports or other site condition reports per subsection 102.05 for additional information concerning the ground conditions that are anticipated during excavation. During construction of the soil nail wall, excavation not associated with the soil nail wall construction shall not be performed within a horizontal distance equal to the total height of the final soil nail wall face excavation. The height of the exposed unsupported final excavation face cut shall not exceed the vertical soil nail spacing plus the required reinforcing lap or the short -term stand -up height of the ground, whichever is less. Each lift excavation shall be completed t o the final wall excavation line and shotcrete applied in the same work shift, unless otherwise approved by the Engineer. Application of the shotcrete may be delayed up to 24 hours if the Contractor can demonstrate that the delay will not adversely affect the excavation face stabil ity. The Contractor shall modify excavation procedures and soil nail wall installation procedures to prevent the loss of material from the excavation face or from behind the previously installed shotcrete lift (chimneying). This may require adjustments to the sequencing between excavation, soil nail drilling and shotcreting to shorten the time the excavation lift is unsupported, drilling and installing the soil nails through temporary berms before final excavation and/or installing the initial shotcrete before drilling the soil nails. All voids that develop behind the shotcrete shall be filled with grout at no additional cost to the Department. 504.33 504-19 Excavation of the next -lower lift shall not proceed until soil nail installation, initial shotcrete face placement, attachment of bearing plates and nuts, and soil nail testing have been completed and accepted per subsection 504. 39 and 504.42 in the current lift. Soil nail grout and shotcrete shall have achieved a compressive strength of at least 1000 psi before excavation of the next underlying lift. Where the Contractor’s excavation and installation methods result in a discontinuous wall along any soil nail row, the ends of the upper lift excavation shall extend beyond the ends of the next lower excavation lift by at least 10 feet. Slopes at these discontinuities shall be constructed to prevent sloughing or failure of the temporary slopes. If sections of the wall are to be constructed at different times, the Contractor shall prevent sloughing or failure of the temporary slopes at the end of each wall section. The Contractor shall remove all or portions of cobbles, boulders, rubble or other subsurface obstruction encountered at the cut line which will protrude into the shotcrete facing including a method to safely secure remnant pieces remaining behind the excavation face and promptly backfilling voids resulting from removal of protrusions extending behind the excavation face. Voids, over -break or over- excavation beyond the plan wall excavation line resulting from t he removal of face protrusions or the excavation operation shall be backfilled with shotcrete, concrete, or grout.

504.33 Soil Nail Installation. Soil n ail length and drill hole diameter used shall be those

necessary to develop the specified load capacity to satisfy the acceptance criteria, but not less than the lengths or diameters shown on the plans. The Contractor shall modify their drilling procedures, as needed, to achieve the required soil nail pullout resistance specified in the plans. All work required to achieve the required soil nail pullout resistance including modifications to the drilling procedures will not b e measured separately but shall be included in the unit price of the work. Holes shall be drilled for the soil nails at the locations, elevations, orientations, and minimum lengths shown on the plans. Drilling equipment and methods shall be suitable for the ground conditions and conform to the installation methods submitted by the soil nailing Contractor. Drilling muds or other fluids shall not be used to remove cuttings. If caving ground is encountered, cased drilling methods shall be used to support t he sides of the drill holes. S elf-drilling soil nail bars (also known as hollow, self - grouting or pressure grouted soil nail bars) shall not be used unless indicated on the plans. Soil nail bars shall be as shown on the plans. Provide centralizers per Section 504. 25 (e).

504.34 Grouting. T he drill hole shall be grouted after installation of the soil nail bar and

within 2 hours of completion of drilling. The grout shall be injected at the lowest point of each drill hole through a tremie pipe, grout tube, or casing. The outlet end of the grout tube or casing shall be kept below the surface of the grout as the conduit is withdrawn t o prevent the creation of voids. The drill hole shall be completely filled in one continuous operation. Cold joints in the grout column are not allowed except at the top of the test bond length of proof tested production soil nails. Excessive grout take is defined as twice the theoretical grout volume to grout the drill hole. The Engineer shall be notified of excessive grout take to allow for modification of the wall design and construction. The Contractor shall maintain the stability of borings through the temporary unbonded length of proof test soil nails for subsequent grouting. If the unbonded test length of production proof test soil nails cannot be satisfactorily grouted subsequent to testing, the Contractor shall install a new soil nail in its plac e. In some granular soils with an open matrix with no cohesion, the potential for drill hole collapse or grout leakage may be large. In this case, a grout containment device or “sock” may 504.35 504-20 be used as approval by the Engineer to reduce excessive grout take in the highly permeable soil.

504.35 Underdrain. The underdrain shall be installed per Section 605.03. The underdrain

should be installed as part of the soil nail wall construction. If the underdrain is to be installed at a time after construction of the soil nail wall, the Contractor shall notify the En gineer to review any proposed excavation at the foot of the wall for stability.

504.36 Soil Nail Testing. Both verification and proof testing of designated test soil nails shall

be performed. Proof tests shall be performed on production soil nails at locations selected by the Engineer or as shown on the plans. Testing of a soil nail shall not be performed unt il the soil nail grout and shotcrete facing have cured for at least 72 hours or attained their specified 3-day compressive strength. The Contractor shall provide all necessary equipment to perform the soil nail testing including, but not limited to, dial gauges, dial gauge support, jack and pressure gauge, electronic load cell with machined platens placed at either end of the load cell, and a reaction frame. In non - creep susceptible soils and as approved by the Engineer, the use of a load cell may be replaced with a dual pressure gauge system with the low reading gauge being used for soil nail acceptance. The pressure gauge shall be graduated in 100 -psi increments or less. The soil nail head movement shall be measured with a minimum of two dial gauges capable of measuring to 0.001 inch. The Contractor shall have available calibrated back up gauges and test loading equipment to minimize down time due to testing equipment failure. The Contractor shall not apply loads greater than 80 percent of the minimum ultimate tensile strength of the tendon for Grade 150 bars or 90 percent of the yield strength of the tendon for Grade 75 bars. Preliminary results shall be submitted to the Engin eer within 24 hours of the test completion. A full report containing test load results shall be submitted to the Engineer within 5 working days of the test completion.

504.37 Verification Testing of Sacrificial Soil Nails. The total number and location of tests

shall be determined and spaced to evaluate soil nail performance in each soil strata encountered along the total length of the wall. A minimum of two verification tests shall be performed on sacrificial test soil nails at each soil nail wall as shown on the plans or as directed by the Engineer. Verification testing shall be performed before installation of production soil nails to confirm the appropriateness of the Cont ractor’s drilling and installation methods and verify the required soil nail pullout resistance. If the Contractor makes changes to the drilling or soil nail installation operation or variability in the soil conditions is encountered, the Engineer may req uest additional verification tests. Verification test soil nails shall have both bonded and unbonded lengths. Along the unbonded length, the soil nail bar shall not be grouted. The unbonded length of the test soil nails shall be at least 3 feet as measured from the back of the bearing plat e to the top of the grout. Verification tests shall be conducted according to the loading schedule of Table 504 -4. Each load increment shall be held for at least 10 minutes. The Contractor shall record soil nail movements at each load increment and the time intervals shown in the table for each load step. Creep tests shall be performed at 0.75 VTL. The alignment load (AL) should be the minimum load required to align the testing apparatus and shall not exceed 5 percent of the VTL. The dial gauges shall be 504.37 504-21 set to “zero” after applying the alignment load. Following application of the maximum load, the load shall be reduced to the alignment load and the dial gauge readings recorded as the permanent set. Each load increment shall be held for at least 10 minutes. The Contractor shall monitor the verification test soil nail for creep at the 0.75 VTL load increment by measuring and recording soil nail movement. The load shall be maintained during the creep test within 2 percent of the intended load by use of the load cell. The test results shall be presented for the Engineers review and acceptance before production. The Engineer shall have 10 working days to review the report and based on the results, design modifications may be required. The bonded length of the soil nail during verification tests (L B VT) shall be:

504.38 Proof Testing of Production Soil Nails. S uccessful proof testing shall be performed on

5 percent of the production soil nails in each soil nail row or a minimum of one per row. Verification tests shall not be included in the 5 percent; except that the Engineer may allow the verification tests to be included based on the plans and site conditions. The Engineer will determine the locations and number of proof tests before soil nail installation in each row unless otherwise shown on the plans. Production proof test soil nails shall have both bonded and temporary unbonded lengths. Fully grouted test soil nails shall not be proof tested. The Contractor shall maintain the stability of the hole for the temporary unbonded test length for subsequent grouting. If the unbonded test length of production pr oof test soil nails cannot be satisfactorily grouted subsequent to testing, the proof test soil nail shall become sacrificial and shall be replaced with an additional production soil nail installed at the Contractor's expense. The temporary unbonded length of the test soil nail shall be at least 3 feet as measured from the back of the bearing plate to the top of the grout. Proof tests shall be conducted according to the loading schedule of Table 504 -5. Unless the soil is susceptible to creep and tests modified per Note 3 of Table 504 -5, each load increment shall be held until readings are stable as defined by three readings within 0.005 inches taken one per minute over three minutes. The Contractor shall record soil nail movements at each load increment and the time intervals shown in the table for each load step. Creep tests shall be performed at 1.00 PTL. The alignment load (AL) shall be the minimum load required to align the testing apparatus and shall not exceed 5 percent of the PTL. Set dial gauges to “zero” after applying the alignment load. Following application of the maximum load, reduce the load to the alignment load and record the permanent set. The creep period shall start as soon as the maximum test load (1.0 PTL) is applied and the soil nail movement shall be measured and recorded at 1 minute, 2, 3, 5, 6, and 10 minutes. Where the soil nail movement between 1 minute and 10 minutes exceeds 0.04 inch, the maximum test 504-23 load shall be maintained for an additional 50 minutes and movements recorded at 20 minutes, 30, 50, and 60 minutes. All load increments shall be maintained within 5 percent of the intended load. The bonded length of the soil nail during verification tests, L B PT, shall be:

504.39 Test Soil Nail Acceptance Criteria. A test soil nail shall be considered acceptable when

the following criteria are met. 504.40 504-24 (a) Verification testing . The following criteria shall be met for acceptance of the soil nail:

504.40 Test Soil Nail Rejection. If a test soil nail does not satisfy the acceptance criterion in

subsection

504.41 Wall Drainage Network. All elements of the wall drainage network shall be installed

and secured as shown on the plans. The drainage network shall consist of installing geocomposite strip drains, PVC connection pipes, wall footing drains, and weepholes as shown on the plans. Exc lusive of the wall footing drains, all elements of the drainage network in the current lift shall be installed before shotcreting.

504.42 Initial Shotcrete Facing. The initial shotcrete facing shall be installed per Section

641. Membrane curing compound shall not be used. Maturity meters shall be used to monitor all shotcrete per subsection 641.05.

504.43 Forms and Falsework. Forms and falsework shall conform to subsections 601.09 and

601.11 respectively.

504.44 Reinforcing Steel. Reinforcing steel shall be installed per this specification and

Section 602.

504.45 Structural Concrete. Structural concrete shall be placed per this specification and

Section 601.

504.46 Acceptance. Material for the soil nail retaining wall will be accepted based on the

manufacturer production certification or from production records. Construction of the soil nail retaining wall will be accepted based on survey, visual inspection, and the relevant pr oduction testing records. METHOD OF MEASUREMENT

504.47 Soil nail walls will be measured by the quantities for the five major components of the

wall: soil nail, initial shotcrete facing, verification testing, excavation and underdrain. Soil nail will be measured by the linear foot of nail installed and accepted. Verification testing will be measured by the number of verification tests performed. 504.48 504-27BASIS OF PAYMENT

504.48 The accepted quantities, measured as provided above, will be paid for at the contract

unit price for the pay items listed below that are shown on the bid schedule. Payment will be made under: Payment will be made under: P ay Item Pay Unit Soil Nail Linear Foot Verification Testing Each P ayment for Soil Nail Wall will be full compensation for all work and materials required to complete soil nail wall. This work shall include but is not limited to soil nails, geocomposite strip drains, proof testing, drilling, grouting, bearing plates, end hardware (nuts, washers, couplers), certificates of compliance, and incidentals necessary to acceptably fabricate and construct the soil nail walls exclusive of any final facing items that may be tabulated on the plans. A ll excavation work required to construct the soil nail wall and the initial shotcrete facing to the lines and grades indicated on the plans will be measured and paid for per Section 203 or 206. Additional earthwork outside of excavation for the wall installation and backfilling beforeor post wall construction will not be measured and paid for separately but shall be included inthe work. U nderdrain will be measured and paid for per Section 605. I nitial Shotcrete Facing will be measured and paid for per Section 641under Pay Item Initial Shotcrete Facing. I ncidental shotcrete required for over -break will be measured and paid for per Section 641 under Pay Item Shotcrete. 504-28 THIS PAGE INTENTIONALLY LEFT BLANK 506.01 506-1 SECTION 506 RIPRAP DESCRIPTION

506.01 This work consists of the construction of riprap per these specifications and in

conformity with the lines and grades shown on the plans or established. MATERIALS

506.02 Riprap shall consist of hard, dense, durable stone, angular in shape and resistant to

weathering. Rounded stone or boulders shall not be used as riprap material. The stone shall have a specific gravity of at least 2.5. Each piece shall have its greatest dimension not greater than three times its least dimension. Material used for riprap may be approved by the Engineer if, by visual inspection, the rock is determined to be sound and durable. The Engineer may require the Contractor to furnish laboratory results if, in the Engineer's opinion, the material is marginal or unacceptable. At the request of the Engineer, the Contractor shall furnish laboratory test results indicating that the material meets the requirements for abrasion resistance or compressive strength as indicated in Table 506- 1. Table 506 -1 RIPRAP MATERIAL TEST REQUIREMENT S Test Description Test Method Specification Requirement Abrasion Resistance by Los Angeles Machine ASTM C535 50% Loss, max. Unconfined Compressive Strength of Drilled Core Specimen AASHTO T 24 2500 psi, min. Riprap shall conform to the gradation requirements given in Table 506 -2.