<p><p><figure id='attachment_3410' style='max-width:766px' class='caption aligncenter'><img class="wp-image-3410 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of deep mixing equipment used in construction of Levee LPV 111." width="766" height="582" /><figcaption class='caption-text'> Deep Mixing Construction of Levee LPV 111 (Courtesy Treviicos).</figcaption></figure></p><p><h2>Project Summary/Scope:</h2>Levee LPV 111 in New Orleans, LA stretches for about 8.5 km along the north bank of the Gulf Intracoastal Waterway adjacent to the Bayou Sauvage National Wildlife refuge. In order to meet the requirements for 100-year level flood protection, the levee needed to be raised from an existing elevation of 5.5 to 8.4 m (18 to 28 ft). To stabilize soft soils on site, provide adequate slope stability, and reduce settlement as well as minimize project costs, the deep mixing method was selected. By the end of construction, approximately 1.4 million m3 (1.7 million cy) of soilcement was completed to depths of up to 20.5 m (67 ft); this is the largest DMM project ever attempted in the United States. The project included over 17,000 DMM elements. Design utilized DMM elements made of two 1.6 m (5.2 ft) diameter columns with an overlap of 0.30 m; these were used both as singular elements and for panels. The design unconfined compressive strength was 690 kN/m² (100 psi).</p><p>Subsurface Conditions: Clayey levee fill overlying soft clays, peat, and organic clays from elevation 5.5 m (18 ft) to elevation -15.3 m (-50 ft). Stiff Pleistocene clays and medium dense sands were encountered beneath the soft clay soils.</p><p>To meet project deadlines, work was performed 24 hours per day, 5.5 days per week. Three double axis Trevi Turbo Mix (TTM) rigs, two single axis TTM rigs, and three double axis Contrivance Innovation Cement Mixing Column rigs were used for deep mixing. In addition, eight batch plants used over 460,000 short tons of slag/cement binder and 454,000 m3 (120 million gallons) of water to prepare grout slurry. The binder mix consisted of 25% type I/II Portland Cement and 75% slag cement.<br><h2>Complementary Technologies Used:</h2>Recycled embankment material (REM) from mixing process used as fill resulted in savings of approximately $15 million.<br><h2>Alternate Technologies:</h2>Reinforced concrete floodwall (T-Wall), PVD with high strength geotextile, and lightweight expanded clay-shale fill were also considered for the project. Earthen levee with DMM was selected because it was the lowestcost alternative and best met the owner’s requirements.<br><h2>Performance Monitoring:</h2>To ensure the uniformity and quality of mixing, the contractor recorded and reported information such as element diameter, location, top and bottom elevations, mixing tool penetration and withdrawal rates, rotation rate, grout delivery rate, and grout pressure. Much of this data was gathered by electronic control and logging devices installed on the contractor’s equipment. In addition, over 500 DMM elements (3% of total) were continuously cored from top to bottom to verify sufficient mixing. For each cored element, 10 specimens (over 5,000 in total) were subjected to UCS testing.<br><h2>Cost Information:</h2>The total cost of deep mixing, including mobilization and demobilization costs, was about $100 million.<br><h2>Project Technical Papers</h2>From ASCE (2012). <em>Grouting and Deep Mixing 2012, Proceedings of the Fourth International Conference on Grouting and Deep Mixing</em>, Editors: Johnson, L.F., Bruce, D.A., and Byle, M.J., GSP 228,ASCE, New Orleans, LA.:<br><p style="padding-left: 30px;">Bertero, A., Leoni, F.M., Filz, G., Nozu, M., and Druss, D. “Bench-Scale Testing and QC/QA Testing for Deep Mixing at Levee LPV 111.” pp. 694-705.</p><p style="padding-left: 30px;">Cali, P., Lelong, B., Bruce, D., Valagussa, S., Beckerle, J., Gardner, J., and Filz, G. “Overview of Deep Mixing at Levee LPV 111, New Orleans, LA.” pp. 661-671.</p><p style="padding-left: 30px;">Cooling, T., Boeckmann, A., Filz, G., Cali, P., Evans, J., and Leoni, F. “Deep Mixing Design for Raising Levee Section, LPV 111 New Orleans, LA.” pp. 672-681.</p><p style="padding-left: 30px;">Druss, D., Wilding, A., Cooling, T., Beckerle, J., Schmutzler, W., and Gardner, J. “Use of Deep Mixing Return Material for Levee Construction.” pp. 629-639.</p><p style="padding-left: 30px;">Schmutzler, W., Leoni, F., Bertero, A., Leoni, F., Nicholson, P., Druss, D., and Beckerle, J. “Construction Operations and Quality Control of Deep Mixing at Levee LPV 111 New Orleans.” pp. 682-693.</p></p><p><h2>Date Case History Prepared:</h2>December 2014</p></p>