DEPARTMENT OF THE ARMY U.S. Army Corps of Engineers CECW-CE Washington, DC 20314-1000 ETL 1110-2-565 Engineer Technical Letter No. 1110-2-565 30 September 2006 Engineering and Design FOUNDATION ENGINEERING: IN-THE-WET DESIGN AND CONSTRUCTION OF CIVIL WORKS PROJECTS 1. Purpose. This engineer technical letter (ETL) provides guidance for planning, design and construction of foundations constructed in-the-wet for civil works structures. This ETL concentrates on successful methods and potential problems. Case histories are provided. 2. Applicability. This ETL applies to HQUSACE elements, major subordinate commands, districts, laboratories, and separate field operating activities having responsibilities for the planning, design, and construction of civil works projects. 3. Distribution Statement. Approved for public release; distribution is unlimited. 4. References. References are listed in Appendix A. 5. Background/Discussion. a. Traditionally, marine structures have been constructed in-the-dry within a cofferdam using a dewatering system. An alternative method, with potential cost savings, is in-the-wet construction. To extend foundation preparation and construction technology to in-the-wet conditions introduces a new level of difficulty. b. This ETL will furnish guidance for the planning, design, and construction of foundations constructed in-the-wet for civil works structures. This document covers foundation types, subgrade preparation methods, test programs, positioning systems, installation techniques, quality control procedures, tolerances, case histories, and lessons learned. ETL 1110-2-565 30 Sep 06 Table of Contents Subject Paragraph Page Background A-1 A-1 Design Considerations A-2 A-2 Introduction A-2a A-2 Tolerances A-2b A-3 Interfacing with Existing Structures A-2c A-4 Structure–Foundation Connections A-2d A-6 Contingency—(Installation Considerations). A-2e A-9 Heave A-2f A-11 Settlement Around Piles A-2g A-11 Liquefaction of Saturated Sands During Pile Installation A-2h A-11 Obtaining High Quality Concrete in Drilled Shafts A-2i A-11 Buoyancy and Hydrostatic Pressure A-2j A-11 Need for Extensive Subsurface Investigation A-2k A-12 Environmental Impacts A-2l A-12 Non-Traditional Construction Methods A-2m A-13 Adjustments to Design Criteria to Mitigate Risk A-2n A-13 Environmental Considerations A-2o A-13 Limited Construction Periods Due to Environmental Issues A-2p A-14 Specialized Equipment A-2q A-14 Decreased Ability for QC A-2r A-14 Risk Mitigation, Repair A-2s A-15 Summary of In-the-Wet Foundation Types A-3 A-15 Introduction A-3a A-15 Driven Piles A-3b A-16 Drilled Elements A-3c A-21 Gravity Base A-3d A-25 Site Exploration A-4 A-37 Increased Need Due to Inability to Visually Inspect Foundation A-4a A-37 Evaluation of Aquifers—Artesian Aquifers A-4b A-37 Geophysical Methods for Broad Evaluation of Discontinuities A-4c A-38 Specialized In-situ Investigation Tools A-4d A-39 Subgrade Preparation and Improvement A-5 A-40 Soil and Rock Foundation Preparation A-5a A-40 Placement of Select Backfill A-5b A-44 Scour Protection A-5c A-45 Deposition, Maintenance Dredging During Construction A-5d A-46 Soil Replacement A-5e A-48 Admixture Stabilization A-5f A-48 Roller Compacted Concrete A-5g A-48 Deep Dynamic Compaction A-5h A-48 Vibro-Compaction A-5i A-48 Stone Columns (Vibro-Replacement) A-5j A-49 Gravel Drains A-5k A-49 Sand and Gravel Compaction Piles A-5l A-49 Explosive Compaction A-5m A-49 Permeation Grouting and Compaction Grouting A-5n A-49 i ETL 1110-2-565 30 Sep 06 Subject Paragraph Page Jet Grouting A-5o A-49 Deep Soil Mixing A-5p A-49 Mini-Piles A-5q A-50 Prefabricated Vertical Drains A-5r A-50 Electro-Osmosis A-5s A-50 Buttress Fills (Surcharge) A-5t A-50 Biotechnical Stabilization and Soil Bioengineering A-5u A-51 Location and Positioning Methods A-6 A-51 Introduction A-6a A-51 Global Positioning System (GPS) A-6b A-51 Templates A-6c A-52 Guides A-6d A-52 Optical Surveys A-6e A-53 Sonic Transponders A-6f A-53 Installation and Construction Methods A-7 A-53 Staging—Temporary Works A-7a A-53 Drilling Methods A-7b A-57 Driving Methods A-7c A-62 Self-Excavating Caissons (Open Caissons). A-7d A-68 Underbase Grouting, Tremie Concrete, Grout Bags, Seal, Load Transfer A-7e A-69 Cut-offs and Splicing A-7f A-72 Test Programs A-8 A-72 Load Test A-8a A-72 Model Test/Numerical Test A-8b A-77 Verification (Continuity) Tests A-8c A-77 Quality Control/ Quality Assurance A-9 A-78 Introduction A-9a A-78 Procedures—More Unknowns Require More Diligence A-9b A-79 CSL (Cross-Hole Sonic Logging) A-9c A-79 Gamma-Gamma Tests A-9d A-80 ROV/AUV (Remotely Operated Vehicle/Autonomous Underwater Vehicles) A-9e A-80 Acoustic Cameras A-9f A-81 Optical Surveys A-9g A-81 Divers A-9h A-82 Above Water Extensions/Tell-Tales/Survey Towers A-9i A-82 Coring/Verification/Cameras/Pressures Sensors A-9j A-82 Soundings/Hydrographic Surveys A-9k A-82 Geophysical Methods A-9l A-82 Test Procedures/Mockups A-9m A-82 Education/Training of Team—Knowledge Resources A-9n A-83 Instrumentation A-10 A-83 Considerations A-10a A-83 Instruments A-10b A-84 Select Case Histories and Lessons Learned A-11 A-85 Olmsted Approach Walls Foundations (Louisville District). A-11a A-85 Inner Harbor Navigation Canal (New Orleans District) A-11b A-98 New Braddock Dam Foundations (Pittsburgh District) A-11c A-99 Mississippi River Lock and Dam No. 24 A-11d A-120 ii ETL 1110-2-565 30 Sep 06 Subject Paragraph Page KY Lock Addition: Highway and Railroad Bridge Foundations (Nashville District) A-11e A-125 References A-12 A-132 Required Publications A-12a A-132 Related Publications A-12b A-132 iii ETL 1110-2-565 30 Sep 06 APPENDIX A Foundation Engineering: In-the-Wet Design and Construction of Civil Works Projects A-1. Background a. Constructing foundations in-the-wet has always presented challenges, uncertainties, and risks. Nevertheless, working in-the-wet presents not only difficulties, but also unique op- portunities. Man has been dealing with both these difficulties and opportunities to install struc- tural foundations in-the-wet since prehistoric times, and each new advance in foundation tech- nology has resulted in the construction of ever more demanding foundations built in-the-wet, while keeping the level of risk at, or below, the threshold of acceptance for each new era of building. b. The Neolithic lake-dweller culture, which peaked in 5000 B.C. in what is now Switzerland, utilized timber pile foundations driven in shallow water to support platforms for houses and other village buildings. When faced with difficult foundation conditions, this ancient culture often took advantage of marine transport to carry canoe loads of stone to dump around and to shore-up the timber piles. c. By 1500 B.C., the people of both northern India and Mesopotamia were excavating deep foundations for bridges to provide year-round transportation across seasonally flooding riv- ers. These Bronze Age cultures utilized technology learned from well construction to shore-up the holes with bricks and stones, and utilized divers and buckets to assist with underwater exca- vation. One of the great challenges for these early, over-water, bridge foundations came from scour during floods, which these people partially addressed by the use of scour stone, frequently facilitated by marine transport. d. By the Roman Era, engineers had developed crude crib-like cofferdams (two parallel walls of timber filled with clay) to enable the Romans to place pozzolanic concrete footings be- low water. Furthermore, the Romans made use of battened timber piles for the first time to resist lateral river forces. The Romans also used concrete placed underwater on a relatively massive scale in the construction of the breakwater for the Herodian artificial harbor in Israel. It appears that the Romans formed large concrete foundation blocks for the breakwater by sinking large timber forms with stone, and filling in the interstitial spaces between the stones with pozzolanic concrete placed by divers, with the forms and pozzolan being transported by water from Italy. e. By the beginning of the Modern Era, in the latter half of the 18th Century, engineers such as Eads and Roebling were using the pneumatic caisson method to build major marine bridge foundations, with these large caissons being floated into position prior to sinking. Other marine foundation advances of the early Modern Era include the use of tremie concrete, begin- ning around the time of the Civil War, and the open caisson method, which was used extensively for building foundations on the Mississippi River. f. In recent times engineers are minimizing risks: of delays, of cost over-runs, of claims, and of not being prepared to deal with changed subsurface conditions, by using advanced con- 1 ETL 1110-2-565 30 Sep 06 struction equipment and techniques, by minimizing the use of personnel, and by maximizing the use of prefabrication. Availability of large floating equipment has encouraged modern in-the-wet engineers to use large driven piles and drilled shafts (often socketed into rock). Indeed, offshore equipment has been used to install large diameter steel, concrete, and composite cylinder piles for major foundations in deep water and in difficult soils, safely, rapidly, and economically. g. Other modern in-the-wet foundation methods include the use of sunken prefabricated steel (and concrete) box caissons, in-the-wet slurry wall cofferdams (such as for the Kawasaki Ventilation Structure in Japan), and gravity base foundations.