2-77 Sectio N 217 – Reinforce D Soil Slope
217.0 1 DESCRIPTION . This work shall consist of constructing a reinforced soil slope in accordance with the Contract and as directed by the Engineer. 217.0 2 MATERIALS . Materials shall meet the requirements of the following subsections: Granular Borrow ................................ ................................ ................................ ........ 703.04 Geotextile for Roadbed Separator ................................ ................................ .............. 720.02 Geog rid shall be new, clean, and in accordance with manufacturer recommendations. The geogrid reinforcement for primary slope stabilization shall be a uniaxially oriented grid structure. The geogrid reinforcement for secondary slope stabilization shall be a b iaxially oriented grid structure. Uniaxial geogrid shall have a regular grid structure. The geogrid shall have high resistance to deformation under sustained long -term design load while in service and shall also be resistant to ultraviolet degradation, damage under normal construction practices, and all forms of biological or chemical degradation normally encountered in the material being reinforced. Biaxial geogrid shall have a regular grid structure. The geogrid shall maintain its reinforcement and interlock capabilities under repeated dynamic loads while in service and shall be resistant to ultraviolet degradation, damage under normal construction practices, and all forms of biological or chemical degradation normally encountered in the material being re inforced. In addition, geogrid shall conform to the following requirements:
a.Long Term Tensile Strength . The Contractor shall provide manufacturer certified tested geogrid meeting the long term allowable tensile strengths shown on the Plans and conformi ng to the following criteria: 𝑇𝑎𝑙=𝑇𝑢𝑙𝑡 𝑅𝐹 where: Tal = Long term allowable tensile strength Tult = Ultimate tensile strength, as determined in the primary strength direction in accordance with ASTM D6637 RF = Total reduction factor
2-78 and,
𝑅𝐹=𝑅𝐹𝑐𝑟×𝑅𝐹𝑖𝑑×𝑅𝐹𝑑 where: RFcr = Reduction factor for creep deformation for 100 year design life, calculated in accord ance with Geosynthetic Research Institute GG4(a) and GG4(b) using ASTM D5262 RFid = Reduction factor for installation damage, calculated in accordance with ASTM D5818 RFd = Reduction factor for durability, as determined in accordance with EPA 9090 and ASTM D4355
b.Minimum Pullout Resistance Factor . The minimum pullout resistance factor shall be 0.50 as determined by ASTM D6706 .
c.Markings . Each roll of geogrid shall be plainly and permanently marked with the following information:
1.Name or trade mark of manufacturer.
2.Date of manufacture.
3.Product identification. 217.0 3 SUBMITTALS . The Contractor shall submit fabrication drawings and a narrative in accordance with Subsection 105.06 . The submittals shall include, but are not limited to, the following:
a.Data for each roll of material documenting that the strength and elongation at yield and break comply with the product specifications and material requirements in the Plans and herein.
b.A geogrid placement plan .
c.Installation details, including a description of sequence and backfill placement as well as how the proposed grade will be maintained. Submittals shall be made to the Engineer 30 calendar days prior to geogrid installation. Within 1 4 calendar days of completing the geogrid installation, the Contractor shall submit record drawings showing panel layout and installation sequence to the Engineer.
2-79 217.0 4 Constructio N Requirements .
a.Product Delivery, Storage, and Handling . The Contr actor shall deliver sufficient materials to the site to prevent interruption of the work. The Contractor shall inspect all materials upon delivery and shall notify the Engineer, and vice versa, of any damage. Damaged materials shall be returned and replace d at no cost to the Agency. Geogrid shall be stored above 32°F. The Contractor shall prevent mud, wet cement, epoxy, and similar materials which may affix themselves to the grid, from coming into contact with the geogrid material. Rolled geogrid material s hall be laid flat or stood on edge for storage. Geogrid shall be kept covered with protective wrapping until ready for use. Geogrid shall be handled carefully with approved handling devices in strict conformance with the manufacturer’s recommendations. Pro ducts shall not be dropped or rolled off trucks, nor shall products be otherwise dragged, rolled, or skidded.
b.Site Preparation . All areas immediately beneath the installation area for the geogrid shall be properly prepared. The subgrade surface shall b e level and free from deleterious material and loose or otherwise unsuitable soils in accordance with Section 203 . The subgrade surface shall be inspected and approved by the Engineer prior to backfill placement.
c.Geogrid Placement . The Contractor shall provide on -site representatives for consultation from the geogrid supplier for a minimum of 3 working days at the start of the geogrid installation. The geogrid shall be installed in accordance with the manufacturer ’s recommendations. The geogrid shall b e placed in continuous longitudinal strips in the direction of the main reinforcement. However, if the Contractor is unable to complete a required length with a single continuous length of geogrid, a joint may be made in accordance with manufacturer’s reco mmendations with the approval of the Engineer. Adjacent strips need not be overlapped. The Contractor shall only place that amount of geogrid required pending work to prevent undue damage. After a layer of geogrid has been placed in its entirety, the next succeeding layer of soil shall be placed in its entirety and compacted. After the specified layer has been placed in its entirety, the next geogrid layer shall be installed in its entirety. The process shall be repeated for each subsequent layer of geogrid and soil.
2-80 Geogrid reinforcement shall be placed to lay flat and pulled tight prior to backfilling. After a layer
of geogrid has been placed, suitable means, such as pins or small piles of soil, shall be used to hold geogrid in position until the subsequent soil laye r can be placed. Geogrid shall be placed directly on the compacted horizontal fill surface. Geogrids are to be placed within 3 inches of the design elevations and extend the length as shown on the elevation view, unless otherwise directed by the Engineer. The Contractor shall verify correct orientation of the geogrid.
d.Backfill Placement . Any damaged geogrid shall be replaced prior to placement of any overlying material at no cost to the Agency. Backfill shall be granular borrow and shall be compacted t o at least 95% of the maximum density determined in accordance with AASHTO T 99 . Backfill within 3 feet of slope face shall typically be compacted with hand equipment. In-place density testing shall be performed by the Contractor for every soil lift at a f requency of one test for every 4,300 square feet, or as otherwise specified by the Engineer. Backfill shall be placed, spread, and compacted in such a manner to minimize the development of wrinkles or displacement of the geogrid. Fill shall be placed in 8 inch maximum lift thicknesses. Backfill shall be graded away from the slope crest and rolled at the end of each work day to prevent ponding of water on the reinforced soil mass. The site shall be maintained to prevent the flow of water from overtopping slo pe crest during construction and after completion of slope. The slope face shall be trimmed such that geogrid reinforcement extends to surface. Under no circumstances shall a tracked vehicle be allowed on the geogrid before at least 6 inches of soil has be en placed. Turning of tracked vehicles shall be kept to a minimum to prevent tracks from displacing the fill and the geogrid. All equipment shall travel at speeds of less than 10 mph. Sudden braking and sharp turning shall be avoided. 217.0 5 METHO D OF MEASUREMENT . The quantity of Reinforced Soil Slope to be measured for payment will be the quantity of geogrid, excluding overlaps, in square yards, in place in the complete and accepted work. The geogrid shall be measured from intact transverse rib to intact transverse rib.
2-81 217.0 6 BASIS OF PAYMENT . The accepted quantity of Reinforced Soil Slope will be paid for at the
Contract unit price per square yard. Payment will be full compensation for furnishing and installing the specified materials in accordance with the Contract, including on -site supplier representation, site preparation, geogrid reinforcement, geotextile placed under backfill, and backfill, and for furnishing all labor, tools, equipment , and incidentals necessary to complete the work . Payment for excavation, topsoil, turf establishment , mulch, erosion matting, and stone fill will be made separately under the appropriate Contract items. Payment will be made under: Pay Item Pay Unit 217.1000 Reinforced Soil Slope ................................ ................................ ............... Square Yard
2-82 Section 219 – Slope Stabilization System
219.01 DESCRIPTION . This work shall consist of furnishing all materials, equipment, labor, and services necessary to install and test a slope stabilization system (SSS), including, but not limited to , slope stabilization nails and a stabilizing facing, in accordance with the se specifications, the Plans , and as directed by the Engineer. 219.02 MATERIALS . Materials shall meet the requirements of the following subsections: Mortar, Type I II ................................ ................................ ................................ ......... 707.0 1(d) Bar Reinforcement ................................ ................................ ................................ .....713.01 Welded Wire Reinforcement ................................ ................................ ..................... 713.0 3 Slope Stabilization Nails ................................ ................................ ............................ 760.01 Shotcrete ................................ ................................ ................................ .................... 760.02 Slope Drainage ................................ ................................ ................................ ........... 760.03 Wire Mesh Facing ................................ ................................ ................................ ......760.04 In addition to the requirements of Subsection 713.0 3, the welded wire reinforcement shall be galvanized in accordance with ASTM A767 .
a.Centralizers . Centralizers for solid bars shall be made from plastic, such as schedule 40 PVC. Centralizers for hollow bars shall be mobile metal type centralizers that have an inside diameter larger than the outside diameter of the slope stabilization nail but smaller than the outside diameter of the couplers .
b.Grout . Grout shall be Type III mortar in accordance with Subsection 707.0 1(d).
c.Slope Drainage . Slope drainage shall be strip drain, sheet drain, or PVC drain as shown on the Plans. 219.03 GENERAL WORK REQUIREMENTS . Work required for the SSS includes but is not limited to slope clearing and scaling as needed, installation and testing of s lope stabilization nails of length and orientation as indicated in the Contract, installation or placement of facing material and related materials, and attachment to slope stabilization nails at specified pre -tensioned levels when applicable. The Contract or shall be responsible for construction means and methods and control of the work associated with SSS construction, including slope stabilization nail and stabilizing facing. This includes, but is not limited to, the construction sequence, the safety of t he workers, temporary handrails, work area access, barriers, and lifting of materials and construction equipment into and out of the work area. The construction sequence shall be in accordance with the approved SSS manufacturer’s instructions, unless appro ved otherwise by the Engineer.
Source: Vermont Standard Specifications for Construction, 2024 Edition. Pages 217–221 of 1,380.