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By Peter J. Nicholson

A new method of constructing retaining walls, in-situ, prior to excavation has been developed. This "Vertical Earth Reinforcement Technique" VERT, has been demonstrated at a full scale test wall at the National Geotechnical Experimentation Site at Texas A&M University. This 10 meter high wall, was constructed of elements of soil mixing in an array that forced composite behavior between the soil mixed elements and the in-situ soils. Inclinometers and extensometers were used to verify the performance of the wall. The construction and results of the testing are presented.

Jan 1, 1998

By Gerald Verbeek, Erick Baziw

Downhole Seismic Testing (DST) is a very popular applied seismology site characterizing tool within geotechnical engineering. A challenging aspect of DST is to characterize the acquired seismic data sets to determine the analysis method that will result in the most accurate interval velocity values. BCE has invested considerable resources into developing Seismic Trace Characterization (STC), which uses various independent parameters of the acquired data at a particular depth. Initial work in this area resulted in the selection of the linearity estimate from the polarization analysis, the cross correlation coefficient of the full waveforms at the particular depth and the preceding depth and a uniquely developed parameter referred to as the signal shape parameter for this characterization. Subsequent analysis in STC identified two other parameters: the Signal-Noise-Ratio (SNR) and the Peak Symmetry Differential (PSD). The paper briefly describes these parameters and then outlines how they can guide the data analysis to derive more accurate results, especially near surface, which is especially important to assess the liquefaction potential in areas prone to earthquakes, such as California. The process will be illustrated with actual data from another area prone to earthquakes, namely New Zealand. 1. INTRODUCTION The near surface characterization of low strain in-situ shear wave velocities (VS) has proven critical for liquefaction assessment. Liquefaction is a phenomenon in which dynamic loading of saturated soil results in the material properties to change suddenly from a solid state to a liquefied state. VS is an important parameter for evaluating liquefaction potential due to fact that it is influenced by many of the variables that influence liquefaction (e.g., void ratio, soil density, confining stress, stress history, and geologic age (Andrus et al., 1997)). Aki and Richards (2002) also outline that the amplitude of ground motion should depend on the density and shear wave velocity of near surface soils and rocks according to the theory of wave propagation. Since the change in density with the increase in depth is relative minor compared to that of the shear wave velocity, the latter is a very useful parameter to represent site conditions (Stewart et al., 1997). Bray (2014) and his colleagues carried out an extensive geotechnical analysis of the catastrophic liquefaction that occurred in Christchurch, New Zealand in 2010 and 2011 and found that near surface rather than deep liquefaction resulted in extensive foundation damage.

Jan 1, 2018

By Martin J. Kenwright

Within the famous Harrods department store, a new lift shaft has been constructed, servicing a depth of 22m below ground level as well as the existing 6 storeys of the store. The shaft will connect with a new goods tunnel which is to be excavated beneath the shop, as well as new floor space above ground level which has resulted from the infilling of a previously existing lightwell within the store. The construction of the deep shaft while maintaining uninterrupted use of the store by the Client led to a number of innovative solutions being undertaken. Empirical assessments were made of settlements anticipated from the construction process, which took place within a congested environment of existing foundations. Various elements were designed and installed to mitigate the effects of the inevitable ground movement on the surrounding overlying structure, which supported sensitive high quality finishes and mechanical and electrical installations The reinforced concrete lining of the shaft was contained within a cofferdam of minipiles. The minipile placement accuracy (1 in 150) was vital as it could not interfere with the subsequent tunnelling works. As the scheme progressed this became even more critical since the minipiles were needed as support for parts of the permanent works This paper describes:- the high quality placement and control of the minipiled cofferdam, the methods employed in assessing ground movements and the techniques used to mitigate against the effects of these movements.

Jan 1, 2000

By Joseph T. Coe, Siavash Mahvelati, Alireza Kordjazi

This paper introduces recent advances in stress-wave NDT systems for use in assessments of in-service foundation integrity and drilled shaft construction. The primary results of the laboratory experiments are very promising, as the acquired image was capable of differentiating changes in pile cross section as low as 0.3 cm. The preliminary results with the same hardware components on a relatively large scale cemented sand model were also promising. A brief overview is provided of both systems including hardware, survey methods, and data processing techniques, followed by a discussion on application of the results to QA/QC of deep foundations. INTRODUCTION There are two main applications in which current QA/QC NDT technology fails to provide sufficient information regarding deep foundation conditions: (1) detection of flaws in outside cover concrete of drilled shafts and corrosion in steel piling; and (2) evaluation of anomalies beneath the bottom of drilled shaft excavations. Previous studies have demonstrated the capabilities of high frequency stress waves for geotechnical and foundation evaluation purposes (Lee and Santamarina 2005; Coe and Brandenberg 2010; Coe and Brandenberg 2012; Coe and Kermani 2016). Higher frequency waves can visualize smaller anomalous features at the expense of higher attenuation and smaller propagation distance. Therefore, the goal of this study was to advance the state of NDT practice by development of a prototype high resolution stress-wave imaging system as proof-of-concept. The equipment and hardware were modular, which allowed simultaneous development of two system configurations for application to in- service foundations as well as drilled shaft excavations during construction. Results are presented based on two large scale soil models. The first laboratory model simulated section loss in an in-service steel pipe pile and drilled shaft foundation (Fig. 1a). The second model simulated anomalous conditions beneath drilled shafts excavations as might be encountered in areas with significant karst (Fig. 1b). For both models, evaluation of foundation conditions relied on the propagation of small amplitude seismic stress waves using hardware similar to those described in Coe and Brandenberg (2010) and Coe and Brandenberg (2012).

Jan 1, 2018

By David Preece

The Thirlmere aqueduct was constructed over 110 years ago to provide water from the Lake District (in the north-west of England) to the city of Manchester some 60 miles (100 km) away. The aqueduct remains, to this day, a key piece of infrastructure in the distribution of raw water in the north-west of England. A short section of the aqueduct was identified as being in poor condition during routine inspections by the owner. Subsequent investigations attributed the conduit damage to the movement of unstable ground over the conduit. Bachy Soletanche Ltd was subsequently appointed to carry out the design and construction of the slope stabilisation works and to undertake repairs inside the damaged conduit. The works were undertaken on an existing slope which, in places stands at a gradient of up to 40º to the horizontal. Strict limitations on plant and equipment were imposed by the client (United Utilities) to ensure that slope and conduit loading and associated vibrations were kept to an absolute minimum during construction. An intensive instrumentation system was installed to monitor surface movements, ground movements at depth, conduit movement and strains across existing planes of weaknesses within the conduit. The solution comprised the installation of spaced piles up-slope and down-slope of the conduit. Restrictions were imposed on the minimum stand-off distance between the outside face of the conduit and the piling works so targeted permeation grouting was undertaken to improve the ?connection? between the conduit and the down-slope piles. The presence of existing sub conduit groundwater flows was suspected and the permeation grouting was focused in areas to minimize disruption to the groundwater regime. The paper presents the basis of the design and highlights the combined construction and instrumentation methods adopted to minimise damage to this valuable asset.

Jan 1, 2011

By Robert W. Schaut

The use of micropiles is increasing for new construction and to retrofit distressed foundations in expansive soils. Typical micropiles in expansive soils have a lower section where the micropile grout is embedded in direct contact with the soil, and an upper section that is cased with rigid PVC pipe or other material to reduce the friction between the micropile and the surrounding expansive soil. In the upper cased section, the micropile grout is in direct contact with the inside of the casing. During construction, grout can flow upward into the annular space between the soil and the outside of the casing as the grout is tremied into the micropile. Thus, various interfaces may exist in a typical micropile, including soil-to-grout, grout-to-PVC, and soil-to-PVC. As the surrounding soil heaves, shear stresses are mobilized along the interfaces. The frictional characteristics of the interfaces are design variables that must be evaluated. For this study, an experimental program was conducted to evaluate the shear strength of the three interfaces listed above. Conventional direct shear testing was performed at a commercial testing laboratory. In addition, specialized testing was performed at Colorado State University (CSU). For the CSU testing, an interface testing protocol was designed using a modified triaxial cell to allow evaluation of the interface characteristics between rigid PVC and cylindrical specimens of grout or clay soil. It is shown that the shear strength of the soil-to-PVC and grout-to-PVC interfaces are similar, both of which are significantly lower than the shear strength of the soil-to-grout interface. This indicates that the use of a PVC casing in the upper portion of a micropile has a positive effect in reducing friction and the shear stresses resulting from expansive soil.

Jan 1, 2011

By Donald Bruce, Mark Harris, Wesley Schmutzler, James Sanders

"This paper evaluates the history, construction and most importantly the performance of two remedial seepage cutoff walls installed in two major dams in the United States. Beaver Dam, on the White River in northwest Arkansas, was completed in 1966 and seepage through the karstic limestone under the embankment was apparent almost immediately upon filling of the reservoir. Several attempts to stop the seepage by grouting were unsuccessful. In 1994 a cutoff wall consisting of secant piles drilled with 32"" diameter down-the-hole hammers to a maximum depth of 185'?was completed and the seepage was reduced to a negligible amount. It has been over 20 years since the completion of the cutoff wall, and all indications are that the cutoff wall is performing as expected. Walter F. George Lock and Dam on the Chattahoochee River near Fort Gaines, Georgia, was completed in 1963 and suffered the same problem as Beaver Dam due to the limestone on which the dam was founded. Cutoff walls were installed in both embankments (1980s) and solved the problem in these areas, but under-seepage at the concrete lock, dam and spillway structures increased to the point that remediation was essential. The cutoff wall had to be installed through 110'?of water and another 100'?into rock upstream of an active dam that continued to generate electricity during the construction of the cutoff wall. A secant pile wall, in combination with a diaphragm wall, was completed in front of these structures in 2004. It has been over 10 years since the completion this cutoff wall and, again, the cutoff wall is performing as expected. The paper describes the construction of these cutoffs, but focuses on the long-term performance in terms of controlling seepage and piezometric levels.BEAVER DAMBeaver Dam is located on the White River, 609 miles above its mouth, in Carroll County, Northwest Arkansas. The construction of the dam and Beaver Reservoir was authorized on September 1954 by the Congressional Flood Control Act for purposes of water supply, flood control and hydroelectric power generation. The dam site was selected in 1957: construction began in November 1960 and was completed in June 1966. (FIG. 1)"

Jan 1, 2017

By Paikowsky, Samuel G.

"Due to the way drilled deep foundations are being constructed, their structural integrity and geotechnical capacity are highly variable. Drop weight systems are increasingly being used to dynamically test the capacity and integrity of drilled deep foundations. Conventional pile driving hammers are often either inadequate or not economical to test these foundations and drop weight systems have therefore been developed to allow for dynamic testing.The advantages of the tests include high mobility, short testing time, low cost relative to static load tests (allowing multiple tests at a single site), and integrity/construction quality evaluation concurrent with capacity determination. The dynamic testing method for drilled deep foundations encounter several difficulties including: the need for a pre-testing analysis for matching pile, soil and testing system, adequate mass and drop height to reflect the mobilized capacity without structural damage, test interpretations for irregularly shaped and/or non-uniform piles, need for reliable dynamic measurements depending on the impact and the distance between the impact and the measuring point, and limited knowledge about the accuracy of the predictions.The principles of the tests are presented using simplified models and demonstrated via a case history. Drop weight systems are reviewed. Dynamic measurement principles are explained and the construction and testing quality effects are outlined and demonstrated via numerical modeling and case histories. A comparison of dynamic and static tests is presented via a database, case histories and finally a short review of relevant codes is provided.1 IntroductionTraditional static axial load test is performed by a slow application of a force produced against independent reaction, imitating structural loading. It is the most reliable method to determine the pile’s performance as commonly required under typical service conditions. The major limitations of this testing are: (i) high cost associated with set-up, test duration, interpretation and construction delays, and (ii) inability to obtain information about the pile-soil interaction along the pile without additional testing means (e.g. tell tales, strain gauges, etc.). These limitations are acute when high capacity foundations are involved."

Jan 1, 2015

By Allan Sylvester

This paper will discuss the design, construction, and performance of the support of excavation on the San Diego State University LRT Station. The vertical elements of the system include drilled secant piles and drilled soldier piles. We will discuss the geo-technical characteristics, design and construction considerations, loading criteria, construction techniques, schedule constraints, and performance of the pile and support of excavation systems. In consideration of the conference theme, there will be a discussion of the successful accomplishment of meeting the interim milestone dates of the Contract. The project team cooperatively worked to design and install approximately 1,100 drilled secant and soldier piles as well as excavate and install the balance of the support of excavation elements in such a manner as to minimize the disruption to campus students and operations.

Jan 1, 2002

By Jacob Chacko

The east span of the San Francisco-Oakland Bay Bridge (SFOBB), which is one of the most heavily traveled bridges in the world, will be replaced due to seismic safety concerns. The majority of the new bridge will be founded on large-diameter (1.8 to 2.5 meters), approximately 60- to 100-meter-long pile foundations The large-diameter steel pipe piles and soil conditions are similar to those used/encountered in many offshore structures. Thus, the design methods used are based on site-specific modifications to the procedures recommended by the American Petroleum Institute rather than the conventional procedures that have been formulated and used for the design of much smaller piles. Pile foundations will experience their maximum loads during the design earthquake. For the Safety Evaluation Earthquake, tension loads of up to approximately 80 to 90 meganewtons (MN) and compression loads of up to approximately 120 to 140 MN were calculated. Due to the economic importance of the SFOBB and the consequences of catastrophic failure in both economic and human terms, the design and analysis of the pile foundations supporting the bridge consider a number of aspects of pile-soil behavior that are normally ignored. Those aspects include: 1) the effects of consolidation and setup, 2) the behavior under dynamic loading, 3) the losses of resistance under cyclic loading, and 4) the load-settlement behavior of the piles under severe cyclic loading conditions. Since the treatment of complex aspects of pile foundation behavior is not codified in any guiding documents, several project-specific methods were developed for design and analysis of the foundation piles.

Jan 1, 2002

By Rob Jameson

"The demand for commercial and residential construction has continued to evolve across the United States over the last decade. Our markets demand larger, deeper and inherently more complex structures, located within increasingly constrained urban locations and with challenging geotechnical conditions. As project demands incrementally escalate, specialty contractors are continuously challenged to extend their state of practice. Development in the size and capabilities of construction equipment, tooling, techniques, monitoring and verification systems over the last decade has consistently allowed contractors to build larger and deeper. For support of excavation (SOE), in addition to scale, selection of the most appropriate system has been a key to success in the most challenging ground conditions. This selection process is based on sound engineering and construction practice, and also prior experience, both positive and negative. Ultimately many Owners have chosen to manage their risk of SOE construction through design-build contracts, which allows specialty constructors to optimize the balance of cost, schedule, scope and associated risk based on their local expertise. Successful implementation of a design-build methodology begins long before a contractor is selected, with identification of key project requirements and risk factors during the feasibility studies and design development phases. In these early stages of the project development, advice and budgets are frequently solicited from Specialty Contractors. The Owner, Construction Manager and Consulting Team will filter this input from multiple sources to provide their specific recommendations, develop construction documents and select the appropriate form of contracting. Only in the final stages, after award of a Design-Build Subcontract, can the successful specialty contractor directly influence risk management approach on the project. A case study is presented from Block 9 in San Francisco’s Transbay District. This project demonstrates the incremental identification, assignment and mitigation of construction risk through the planning and design build process for SOE on the deepest planned excavation in San Francisco.INTRODUCTIONThe mature urban development market in United States results in high demand for complex Support of Excavation (SOE) schemes on constrained sites. The Design-Build approach can be applied to increasingly difficult SOE challenges, combining regional specialty subcontractor knowledge and experience in order to optimize solutions for cost and schedule. The most successful applications will involve early engagement of shoring subcontractors within the project teams, during feasibility and design development stages, in order to identify key scope and risk issues, and their potential solutions. Throughout the project development, it is important to reasonably assign responsibility for construction risks amongst the project stakeholders who are best able to control them.This paper presents a case history for San Francisco’s Block 9, a well-planned and successfully executed design-build SOE project in San Francisco’s Transbay Redevelopment area. Throughout the 4 year period from the Developers initial proposal to the Redevelopment agency, through completion of excavation down to subgrade, the project team developed a series of increasingly refined SOE schemes, with corresponding scope definition and cost and schedule estimates. This program relied on early identification of key challenges and risks for the project, and evolved through multiple phases of proposals as first the General Contractor (GC) and then Specialty Shoring Subcontractor were engaged for the project. The scheme, cost and schedule refinements continued throughout construction in order to accommodate unanticipated conditions and events as they unfolded."

Jan 1, 2017

By Philip J. Daynes

As part of the regeneration of the centre of Dublin, a multi-functional development is being constructed on the site of the historic Smithfield Fruit Market. The site is being developed in three phases, and includes one of the deepest basements (10m) constructed in Ireland to date. Until the recent improved economic climate, there has been little requirement for deep basements in Dublin, and this is the first to be constructed entirely within fluvio-glacial gravels and boulders. The difficult ground conditions led to the adoption of a diaphragm wall solution to ensure a watertight construction. Tie-back anchorages are utilised in the temporary case, and the wall is propped by floor slabs in the permanent case. Where required by high bedrock levels, the diaphragm wall is dowelled into limestone bedrock to ensure toe stability. The recorded lateral movement of the wall is significantly below that calculated by numerical analysis. Temporary bentonite cut-off walls were installed to divide the site into discrete sections. The basement was constructed as a tanked structure, and is subject to uplift water pressure. Passive tension minipiles provides an innovative alternative to the standard stressed anchorage solution. This paper describes:- design and construction aspects of the diaphragm wall, tie-back anchorages, and anti-flotation minipiles, together with recorded lateral wall movements,

Jan 1, 2003

By H. W. Hunt

Accessories are increasingly used to protect and extend H, pipe, precast concrete, timber, and sheet piles for any soils conditions. With point protection, piles can be driven through boulders, layered rock, garbage dumps, and waterfront debris to provide dependable support for all types of structures. Splicers for pipe piles can be tapered for a water-tight drive-fit that does not require welding. The pipe splicer can be made applicable to precast concrete piles. Splicers for H make the long pile as strong as an unspliced length with only simple welding. Transition splicers quickly connect different types or sizes into efficient composite piles.

Jan 1, 2010

By Scott A. Walker, Frank L. Rollo

"The San Francisco Museum of Modern Art (SFMOMA) in downtown metropolitan San Francisco, California, is supported on a mat foundation. Although the mat foundation of the original museum was designed to accommodate a future expansion, the plans for expansion that developed in 2010 required a larger footprint to accommodate the new space requirements of the museum. The new, larger expansion was designed by lead architect Snohetta. It will be a tall 12-story, steel-framed building occupying an area that was once the eastern part of the existing museum as well as two adjacent and newly acquired parcels.As designed, the expansion includes a 30-foot-deep excavation which is surrounded by adjacent buildings and improvements. Because of variable subsurface conditions at the site, geotechnical challenges included mitigating anticipated differential settlement between the existing and new foundations, preventing overstressing of the existing mat foundation, controlling groundwater to prevent settlement of surrounding improvements, and providing temporary support of adjacent structures during excavation for the new basement.To address several of the geotechnical challenges, soil-cement mixed (SMX) ground improvement was recommended by Treadwell & Rollo. However, during contract negotiations and construction, the specialty contractor proposed using jet grouting as an alternative technique for ground improvement. The jet grouting approach was accepted in principal, but when implemented was only marginally successful. Accordingly, the contractor eventually installed SMX panels using a Cutter Soil Mixing (CSM) machine. Because the CSM machine was a late arrival during construction, the contractor was not able to take advantage of the ground-improvement technique to install many of the shoring elements that we had originally recommended (such as the cut-off shoring wall). In the end, SMX panels were installed as ground-improvement beneath the new mat foundation to (1) reduce the potential for liquefaction in clean sand below the groundwater by providing increased rigidity to the soil, (2) reduce the potential for disturbing a weak underlying marsh deposit during construction, and (3) transfer vertical building loads to a layer of underlying dense sand.This paper also discusses the quality control and quality assurance programs that were implemented to check that the ground-improvement techniques used were thorough and complete and provided the required strength to transfer the new foundation loads to the underlying strata."

Jan 1, 2014

By Ron Bromenschenkel

The State of California, Department of Transportation is currently retrofitting a major interchange near the San Francisco area. The project is located in a highly traveled area of Oakland with light rail commuter service near many footings. Over 600 micropiles are being used in conjunction with CIDH piles for footing stabilization. A specially designed Soil Nail pile will support footings for a new light rail utility structure. Pile testing features in this contract serve as points of interest for future foundation designs. The presentation focuses on substructure issues of this incterchange retrofit. Both design and construction considerations will be covered. Design Considerations: ? Project Description ? Structure inadequacies ? Design criteria ? Design contraints ? Retrofit strategy ? Consultant analysis ? Pile Designs and Test Sites ? Contract Specifications ? Construction Plan and Cost

Jan 1, 1998

By Chris D. Shewmaker

So you want to install 2,600 augered cast-in-place piles, about 155,000 lineal feet, in 33 working days? It can be done. The Public Service Enterprise Group (PSEG) decided to build a combined cycle power plant in Lawrenceburg, Indiana. PSEG selected Fluor Constructors Indiana, L.P. to design and build the plant. Fluor Constructors, in turn, selected Richard Goettle, Inc. to install the piles. The initial plan was to install the 2,600 piles in 33 days, working six (6) ten hour days per week. After successfully installing and performing four pile load tests - up to 300 ton capacity - we set out to complete the work and meet the aggressive schedule. After three weeks of installing an average of 75 piles a day with three drill rigs, Fluor relaxed the schedule because we were so far ahead of their projected construction sequence. We elected to continue drilling on a ten-hour day, five days a week schedule. In all, we installed nearly 2,800 piles, totaling 175,000 lineal feet, in about 47 days.

Jan 1, 2004

By Michael H. Wysockey

The load test program for the pile foundation at Soldier Field included static and dynamic load tests at four locations around the site. The dynamic tests were run with no knowledge of the static results, and comparison between the two is very good. It was necessary to use a special testing hammer (not the production hammer) to demonstrate capacity with dynamic testing. Over 90% of the piles were HP14x89 with a design load of 230 tons (18 ksi). The load tests showed a capacity in excess of 590 tons for all tests where sufficient set up time was allowed. The remainder of the piles were mostly HP 12x53 with a design load of 100 tons (13 ksi). The measured capacity of these piles was typically about 250 tons. One experimental HP12×74 pile with a nominal yield of 65 ksi held 730 tons (67 ksi) before failing.

Jan 1, 2002

By Brian P. Waagner

Construction law in general and the law of deep foundations in particular continues to develop rapidly, particularly in the areas of risk allocation. Public and private owners are increasingly using contractual disclaimers to shift the risk of differing site conditions to contractors, and courts are increasingly willing to enforce these contractual devices. Perhaps also in an effort to control costs, public and private owners are turning to design-build contracting techniques. While design-build offers many advantages over traditional project delivery systems, it does not answer all of the risk-allocation questions that frequently arise. Even in design-build, problems with unanticipated subsurface conditions and defective design are not easily addressed. Finally, developments in electronic commerce present the potential to transform the construction industry.

Jan 1, 2002

By Gordon Chen

The Block 37 Chicago Transit Authority (CTA) Tunnel Construction Project was originally designed by STV to connect Blue Line subway in North Dearborn Street and Red Line subway in State Street in the downtown Chicago Area. The project was proposed using tunnel mining techniques combined with steel pipe jacking and fiber glass rebar soil reinforcement. Weidlinger Associates, Inc. (WAI) and Kiewit Construction Company proposed an alternate design using open cut construction technology. WAI designed a complex temporary excavation support system using Soldier Pile Tremie Concrete (SPTC) walls and Soldier Pile Lagging walls supported by cross lot/corner bracing elements. Below the top of the existing tunnel, a top-down construction technique was utilized. A steel temporary traffic decking system at top of the excavation site served as the daily street traffic function as well as the first level of bracing for the support of excavation. The project encountered great challenges of soft clay conditions in downtown Chicago, numerous existing utilities in the excavation site and the requirements of protection for a number of historical buildings nearby as well as the protection of the city streets. The construction was successfully completed at both State Street/Washington Street and Dearborn Street/Randolph Street. The monitoring system showed that ground movement and adjacent building settlement was kept to a minimum during construction.

Jan 1, 2009

By Gordon] [Reavis

Halliburton Services and Brown & Root have developed a unique foundation system that blends oilfield and construction technologies to construct deep foundations which offer significant advantages across a variety of soil profiles. This highly efficient system is being developed to meet the construction industry's needs into the 21st Century. Based on a concept initially introduced to Halliburton Services by V.L. Schellhorn in 1987, Halliburton combined their existing cement slurry mixing and pumping technology with oilfield drilling practices and a new tool design to field test the viability of the concept. Results looked encouraging, and Halliburton asked it's sister company, Brown & Root to evaluate and further develop the process. With Brown & Root's knowledge of the construction industry, the original concept has developed into a viable and efficient foundation construction system.

Jan 1, 1993