<p><p><h2>Preferred QC/QA Procedures</h2>No FHWA guidance for quality control and quality assurance (QC/QA) exists for this technology. Several QC/QA procedures are recommended including the use of piezometers, settlement plates, inclinometers, field vane shear tests, drain material inspection, and cone penetration tests.</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 hydraulic fill with horizontal drainage are listed 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-1991'><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 >• Geosynthetic (geomembrane, seams, and PVD) properties, Granular layer properties, Pump characteristics, Consolidation tests</td></tr><tr><td ><center>QC</td><td ><center>Process Control</td><td >• Vacuum at pump, settlement, pore pressure, vacuum pump wattage, water flow, PVD installation (depth & verticality), geomembrane installation, trench depth and membrane anchorage</td></tr><tr><td ><center>QA</td><td ><center>Material Related</td><td >• CPT/qt & u, settlement plates, dilatometer, piezometers, inclinometers, consolidation tests, geosynthetic (geomembrane, seams, and PVD) properties, granular layer properties and installation, PVD installation (depth & verticality), geomembrane installation
</td></tr><tr><td ><center>QA</td><td ><center>Process Control</td><td >• Records of vacuum at pump
• Settlement
• Pore pressure
• Inclinometer
</td></tr></tbody></table><br><h3>TABLE 2. PERFORMANCE CRITERIA USE IN QC/QA MONITORING PROGRAMS</h3><table class='tablepress' id='tablepress-1992'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Parameters</td><td >• CPT/qt & u</td></tr><tr><td ><center>System Behavior</td><td >• Settlement
• Pore pressure
• Inclinometer
• Field vane shear test
</td></tr></tbody></table><br><h3>TABLE 3. EMERGING QC/QA PROCEDURES AND MEASUREMENT ITEMS</h3><table class='tablepress' id='tablepress-1993'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Related</td><td >• Geophysical monitoring to establish special variability of improvement
• Horizontal settlement profiler
</td></tr><tr><td ><center>Process Control</td><td >• Remote sensing for instrumentation monitoring</td></tr></tbody></table></p></p>
<p><p><h2>QC/QA Guidelines</h2><strong> </strong>A quality control program for the prefabricated drains is conducted both in-situ and in the laboratory. The program includes checking drain dimensions, apparent opening size, tensile strength, permeability, and discharge capacity. Characteristics of the drain and pump system should be documented prior to construction and during pumping. The estimation of degree of consolidation is recommended using both settlement and pore-water pressure data. The pore-water pressure distribution profile assessed by piezometers can be used to check whether the pore-water pressure dissipation is consistent with the degree of consolidation calculated based on settlement data. Field vane shear tests can be conducted before the construction, after the installation of the drains, and after release of vacuum loading to estimate the shear strength of soil. Cone Penetration Tests (CPT) are also used to estimate soil shear strength.</p><p>Strong project management teams are essential to achieve a successful QC/QA program for land reclamation projects. Contract management, coastal and geotechnical engineers are all needed in the project team. In addition, it is necessary for contractors having the knowledge of dredging techniques and equipment.</p></p>
<p><p><h2>References</h2>Bo, M.W., and Choa, V. (2004). <em>Reclamation and Ground Improvement</em>, Thomson Learning, Singapore.</p></p>