<p><p><h2>Preferred QC/QA Procedures</h2>There is no standard FHWA document that specifically addresses the QC/QA procedures of Shored Mechanically Stabilized Earth (SMSE) wall systems. However, procedures from <em>Design and Construction of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes</em> (Berg et al. 2009a,b) can be applied to SMSE walls. This report includes checklists for inspections and detailed information to help determine causes of out-of-tolerance conditions and should be used as a reference when developing a comprehensive QC/QA plan. In addition to these procedures, detailed QC/QA procedures for construction of the chosen type of shoring wall should be taken from relevant design guidelines for each wall type. In the case of soil nail walls, this would be the FHWA <em>Geotechnical Engineering Circular #7 Soil Nail Walls</em> (Lazarte et al. 2015). For other shoring systems see the FHWA <em>Earth Retaining Structures</em> manual (Tanyu et al. 2008).</p><p>Construction 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 SMSE wall systems 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><strong>TABLE 1. TYPICAL EXISTING QC/QA PROCEDURES AND MEASUREMENT ITEMS</strong></h3><table class='tablepress' id='tablepress-2048'><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 >•Verify backfill and reinforcement material properties for MSE wall
</td></tr><tr><td ><center>QC</td><td ><center>Process Control</td><td >•Verify proper compaction and facing installation
•Verify reinforcement location, orientation, and connection
</td></tr><tr><td ><center>QA</td><td ><center>Material Related</td><td >•Monitor facing deterioration and potential corrosion of reinforcement
</td></tr><tr><td ><center>QA</td><td ><center>Process Control</td><td >•Monitor horizontal movement of face
•Monitor vertical movement of the surface of the overall structure
•Monitor differential settlement of shored wall and MSE wall
</td></tr></tbody></table><br><h3><strong>Table 2. PERFORMANCE CRITERIA USE IN QC/QA MONITORING PROGRAMS </strong></h3><table class='tablepress' id='tablepress-2049'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Parameters</td><td >•None noted
</td></tr><tr><td ><center>System Behavior</td><td >•Settlement and creep monitoring
•Load capacity
•Proper drainage
</td></tr></tbody></table><br><h3><strong>Table 3. EMERGING QC/QA PROCEDURES AND MEASUREMENT ITEMS</strong></h3><table class='tablepress' id='tablepress-2050'><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 >•Automated horizontal/vertical movement observation</td></tr></tbody></table></p></p>
<p><p><h2>QC/QA Guidelines</h2>SMSE wall systems are a composite technology, comprised of a shoring system and an MSE wall. Recommended QC/QA procedures for the two separate technologies should be incorporated into the overall QC/QA plan. These guidelines can be found in <em>QC/QA Procedures</em> product for the individual technologies. For example, if a traditional soil nail wall was used as the shoring system, QC/QA guidelines for the SMSE wall system should be developed from the applicable shoring technology and the <em>Mechanically Stabilized Earth Wall</em> technologies QC/QA Procedures products. In addition to these guidelines, monitoring of the shoring wall and MSE wall interface should be performed to identify tension cracking and differential settlements.</p></p>
<p><p><h2>References</h2>Berg, R.R., Christopher, B.R., and Samtani, N.C. (2009a). “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. (2009b). “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…, C.A., Robinson, H., Gómez, J.E., Baxter, A., Cadden, A., and Berg, R.R. (2015). “Soil Nail Walls Reference Manual,” FHWA NHI-14-007, GEC No. 7, Federal Highway Administration, Washington, DC, 425p.</p><p><a href="https://www.fhwa.dot.gov/engineering/geotech/pubs/nhi14007.pdf">https:/…, K.F., Harrison, F.E., Collin, J.G., Dodds, A., and Arndt, B. (2006), <em>Shored Mechanically Stabilized Earth (SMSE) Wall Systems Design Guidelines</em>. Report No. FHWA-CFL/TD-06-001. Federal Highway Administration.</p></p>