<p><p><h2>QC/QA Guidelines</h2>Due to lack of literature regarding QC/QA test frequencies and criteria for CSV columns, QC/QA guidance provided here is primarily based on the <em>Technical Special Provisions for Combined Soil Stabilization with Vertical (CSV) Columns</em>, which is provided as part of the <em>Specifications</em> document for this technology.</p><p>A comprehensive CSV column QC/QA assessment program usually consists of trial columns and several QC/QA methods. Trial columns are installed during the preproduction phase and are a combination of calibration and test columns. Auger insertion speed, rotational speed, and crowd pressure must be synchronized with each other by means of calibration columns to insure that an adequate quantity of excess fill material surrounds the auger at all times during penetration and is displaced, preventing in-situ soil from entering the flights of the auger. Withdrawal speed also needs to be monitored to ensure adequate compaction of the column material. Diameters of the auger and compaction head should be monitored periodically to ensure wear on the tooling is within acceptable limits. A minimum of two calibration columns is required for each project, with a calibration column required for every 100 production columns. After the appropriate installation parameters have been determined, test columns should be installed at representative locations on the project site. From the <em>Technical Special Provisions for Combined Soil Stabilization with Vertical (CSV) Columns</em> it is recommended that a minimum of six test columns be installed, although this may vary depending on the size of the project. Half of the test columns should be excavated for visual assurance of integrity and continuity. Samples should then be taken from the columns and subjected to compressive strength testing. The remaining columns should be subjected to verification testing in accordance with ASTM D-1143, including performing a creep test for 60 minutes at 150% of the design load and loading the columns to a maximum test load of 200% of the design load. Details of the loading procedure and test criteria are included in the <em>Technical Special Provisions for Combined Soil Stabilization with Vertical (CSV) Columns</em>. Neither calibration nor test columns should be used as production columns.</p><p>Production columns should be installed using the same installation parameters as determined by the trial columns in the preproduction phase. This shall be verified by automatically monitoring insertion speed, withdrawal speed, rotational speed, and crowd pressure for all column installations. Auger and compaction head diameters should also be recorded periodically to evaluate wear. A proof test should be conducted for every 200 columns during production. During a proof test, the column should be loaded to 150% of the design load in accordance with ASTM D-1143. A successful verification test may be substituted in place of a required proof test. Details of the loading procedure and test criteria are included in the <em>Technical Special Provisions for Combined Soil Stabilization with Vertical (CSV) Columns</em>.</p><p>Post-construction QA can include surveying and load and compressive strength testing. All CSV columns should be surveyed to ensure that the as-built locations match the specified locations. Columns should be located at ±3 inches from the planned location and with an inclination of less than ±2º from vertical. Load and compressive strength testing for QA should be conducted in cooperation with QC measures during production.</p></p>