<p><p><h2>Preferred QC/QA Procedures</h2>The Federal Highway Administration (FHWA) provided QC/QA guidance for this technology. The documents are summarized below.</p><p><table class='tablepress' id='tablepress-2013'><thead><th><center>Publication Title</th><th><center>Publication
Year
</th><th><center>Publication Number</th><th><center>Available for Download</th></thead><tbody><tr><td ><center>Mechanically Stabilized Earth Walls and Reinforced Slopes, Design and Construction Guidelines</td><td > <center>2009</td><td > <center>Vol. I – FHWA-NHI-10-024, and Vol. II – FHWA-NHI-10-025</td><td > <center>Yes<sup>1,2</td></tr></tbody></table><br><p class="disclaimer"><u><sup>1</sup></u><a href="https://www.fhwa.dot.gov/engineering/geotech/pubs/nhi10024/nhi10024.pdf…; </u></p><p class="disclaimer"><u><sup>2</sup></u><a href="https://www.fhwa.dot.gov/engineering/geotech/pubs/nhi10025/nhi10025.pdf… quality is achieved by meeting established requirements, as detailed in project plans and specifications, including applicable codes and standards. Quality Control (QC) and Quality Assurance (QA) are terms applied to the procedures, measurements, and observations used to ensure that construction satisfies the requirements in the project plans and specifications. QC and QA are often misunderstood and used interchangeably. Herein, Quality Control refers to procedures, measurements, and observations used by the contractor to monitor and control the construction quality such that all applicable requirements are satisfied. Quality Assurance refers to measurements and observations by the owner or the owner's engineer to provide assurance to the owner that the facility has been constructed in accordance with the plans and specifications.</p><p>The components of QC/QA monitoring programs for mechanically stabilized earth walls are shown in Tables 1, 2, and 3. The entries in the table are a list of typical items, not a list of all methods that could be used for QC/QA. Some QC procedures and measurement items may also serve as QA procedures and measurement items.<br><h3>TABLE 1. TYPICAL EXISTING QC/QA PROCEDURES AND MEASUREMENT ITEMS</h3><table class='tablepress' id='tablepress-2014'><thead><th><center>QC or QA</th><th><center>Material or Process</th><th><center>Items</th></thead><tbody><tr><td ><center>QC</td><td ><center>Material Related</td><td >• Reinforced wall fill moisture content and density
• Reinforced wall fill material (gradation, plasticity, classification)
• Reinforced wall fill soundness and electrochemical properties
• Retained backfill moisture content and density
• Retained backfill material (gradation, plasticity, classification)
• Soil reinforcement tensile strength
</td></tr><tr><td ><center>QC</td><td ><center>Process Control</td><td >• Monitor fill compaction
• Monitor placement of reinforcing elements (spacing and length requirements)
• Placement of wall facing units
</td></tr><tr><td ><center>QA</td><td ><center>Material Related</td><td >• Reinforced wall fill moisture content and density
• Reinforced wall fill material (gradation, plasticity, classification)
• Retained backfill moisture content and density
• Retained backfill material (gradation, classification)
• Reinforced wall fill soundness, and electrochemical requirements
• Soil reinforcement tensile coupon testing
• Soil reinforcement manufacturer certification
</td></tr><tr><td ><center>QA</td><td ><center>Process Control</td><td >• Monitor lift thickness
• Monitor fill compaction
• Monitor placement of reinforcing elements (grade, strength, spacing, and length requirements)
• Placement of wall facing units
</td></tr></tbody></table><br><h3>TABLE 2. PERFORMANCE CRITERIA USE IN QC/QA MONITORING PROGRAMS</h3><table class='tablepress' id='tablepress-2015'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Parameters</td><td >• Soil shear strength of reinforced wall fill
• Drainage behavior of reinforced wall fill
</td></tr><tr><td ><center>System Behavior</td><td >• Horizontal or vertical movement of face or overall structure</td></tr></tbody></table><br><h3>TABLE 3. EMERGING QC/QA PROCEDURES AND MEASUREMENT ITEMS</h3><table class='tablepress' id='tablepress-2016'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Related</td><td >• None noted</td></tr><tr><td ><center>Process Control</td><td >• Intelligent soil compaction
</td></tr></tbody></table></p></p>
<p><p><h2>QC/QA Guidelines</h2>Inspections, construction observations, daily logs, and record keeping are essential QC/QA activities for all technologies. These activities help to ensure and/or verify that:<br><ul> <li>Good construction practices and the project specifications are followed.</li> <li>Problems can be anticipated before they occur, in some cases.</li> <li>Problems that do arise are caught early, and their cause can oftentimes be identified.</li> <li>All parties are in good communication.</li> <li>The project stays on schedule.</li></ul>Additional technology-specific details for inspections, construction observations, daily logs, and record keeping QC/QA activities are provided in the <em>Individual QC/QA Methods </em>section below.</p></p>
<p><p><h2>References</h2>Adams, M., Hicks, J., Stabile, T., Wu, J., Schlatter, W., and Hartmann, J. (2011).“Geosynthetic Reinforced Soil Integrated Bridge System, Interim Implementation Guide”, FHWA-HRT-11-026, Federal Highway Administration, Washington, DC.</p><p>Berg, R.R., Christopher, B.R., and Samtani, N.C. (2009). “Design and Construction of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes,” FHWA NHI-10-024 Vol I, Federal Highway Administration, Washington, DC, 306p.</p><p><a href="https://www.fhwa.dot.gov/engineering/geotech/pubs/nhi10024/nhi10024.pdf…, R.R., Christopher, B.R., and Samtani, N.C. (2009). “Design and Construction of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes,” FHWA NHI-10-025 Vol II, Federal Highway Administration, Washington, DC, 378p.</p><p><a href="https://www.fhwa.dot.gov/engineering/geotech/pubs/nhi10025/nhi10025.pdf…, V., Fishman, K.L., Christopher, B.R., and Berg, R.R. (2009). “Corrosion/Degradation of Soil Reinforcements for Mechanically Stabilized Earth Walls and Reinforced Soil Slopes,” FHWA NHI-09-087, Federal Highway Administration, Washington, DC, 142p.</p><p><a href="https://www.fhwa.dot.gov/engineering/geotech/pubs/nhi09087/nhi09087.pdf…, K.F., Harrison, F.E., Collin, J.G., Dodds, A., and Arndt, B. (2006), Shored Mechanically Stabilized Earth (SMSE) Wall Systems Design Guidelines.Report No. FHWA-CFL/TD-06-001.Federal Highway Administration.</p><p>Simac, M.R., Bathurst, R.J., Berg, R.R., and Lothspiech, S.E., (1993). Design Manual for Segmental Retaining Walls, 1st Edition, National Concrete Masonry Association, Herndon, VA, 336p.</p><p>Tanyu, B.F, Sabatini, P.J and Berg, R.R (2008). Earth Retaining Structures Reference Manual, U.S. Department of Transportation, Federal Highway Administration, Washington, DC, FHWA NHI-07-071, 654p.</p></p>