Key Steps To Profitable Foundation Drilling

Transcription

1 Key Steps To Profitable Foundation Drilling

2 KEY STEPS TO PROFITABLE FOUNDATION DRILLING Unlike geothermal and water well drilling operators, a foundation drilling contractor is a small cog in a large wheel. Whether it is civil construction or bridge construction, foundation drillers work with the prime contractors and perform within the confines of the design parameters of the larger project. The activities the foundation drillers perform, such as anchored earth retention, pile construction and drilled shaft foundations, are all determined by the factors that govern the engineering project they are part of. This necessitates a closer partnership between foundation drillers and prime contractors. A lot of issues determine the profitability of foundation drilling operations and the contractors must remain vigilant of poor bidding practices, delays, changeorders, budget overruns, distrust, disputes, and technical challenges to make sure that the drilling job is completed safely, soundly and profitably. This white paper discusses some of the key steps foundation drilling contractors need to take to keep their jobs profitable. 1. Thoroughly Study the Site Construction Report When a foundation drilling contractor is called in by a prime contractor, in most cases, some kind of preliminary work is already done on the project. The prime contractor will have access to site investigation reports performed on the project site before he or she bid for the project. These site investigation reports are a good source of information which every drilling contractor should study before bidding any work. The site investigation reports usually have a series of test borings or core borings done on site to check the soil properties and other geological information. A careful analysis of these reports will provide the drilling contractor with a lot of information critical to understanding the scope of the work such as; the type, size, quantity and the structural details of the piles that need to be constructed; site specific information about the structural nature of the overburden and rock layers (e.g. clays, glacial till, shale rock etc.) will be detailed in the bore logs on these reports. 1

3 There are different types of deep foundation piles such as end bearing piles, skin friction piles, settlement reducing piles, tension piles, laterally loaded piles, etc., but end bearing and friction piles are the two most commonly used construction techniques. End bearing piles are deep foundations which terminate in hard, relatively impenetrable material such as rock or very dense sand, gravel and sometimes limestone. They derive most of their load bearing capacity from the resistance of the stratum at the base of the pile. This requires foundation drillers to drill down through all the soft soil layers and drill into the bed rock and construct the pile. Drillers need to case the pile all the way down to the bed rock and drill further into the bed rock. Once the hole is drilled and cased common practice is to pressure fill the cavity with concrete. The pre-constructed steel pile is then lowered into the hole. Upon curing of the concrete the casing is removed leaving a constructed pile. This construction technique displaces the load on the pile into the solid bed rock. Friction piles obtain a greater part of their carrying capacity by skin friction or adhesion. This tends to occur when piles do not reach an impenetrable stratum but are driven for some distance into a penetrable soil. Their carrying capacity is derived partly from end bearing and partly from skin friction between the embedded surface of the soil and the surrounding soil. Foundation drillers employ pile driving machines to drive the casing down into the ground, beating it until it doesn t go any further. They drill down through the casing; drill underneath the casing and then pressure fill the hole with concrete. The casing is sometimes lifted as the hole is pressure-filled or removed after the concrete has cured. The concrete being forced into the hole under pressure swells out underneath the casing. As the casing is removed the bond between the concrete and the soil layers creates a friction on which the load of the pile is handled. Your site investigation report will help you choose the correct type of the pile method that should be employed. It also helps you to arrive at better informed decisions regarding pile bearing capacity and the methods of verification being used on site; specification of structural materials. 2

4 2. Understand Your Capabilities Every foundation drilling contractor needs to have a thorough and realistic understanding of their firm s capabilities in handling the size and scope of the drilling operations. The foundation drilling industry is littered with examples of when a contractor has embarked on a project exceeding his or her capabilities and has to call in external assistance half-way through the job; incurring expenses and compromising the profitability of the contract. You need to understand the capabilities in terms of your expertise and experience and then the capabilities of the equipment you employ in foundation jobs. Both are very important to be able to sail through drilling assignments smoothly. A mismatch between your capabilities and the requirements of the project may set you on a very huge and expensive learning curve. Capabilities of equipment are something foundation drillers should focus on. If their inventory consists of smaller rigs then their machinery is best suited for micro pile work in 5-1/2 inch OD, 6-5/8 inch OD, 7 inch OD, and 7-7/8 inch OD slots. These are the standard casing sizes used in foundation drilling industry. Since most projects build piles according to the standard casing sizes available in the industry, the smaller rigs have the capability to handle such micro pile and tie back work. Such rigs are also capable of building slanted piles in some bridge construction work. If a wall needs to be built at an angle of 70 or 80 degrees, a number of holes can be drilled from the side and anchors can be pushed into the bed rock so that walls can be attached firmly to these anchors dug deep into the solid rock. When foundation drillers try to employ the same machinery in drilling holes of large diameter, such as 20 inch or 24 inch, there is a serious mismatch between the available and the required capabilities. Smaller rigs just don t have the required torque needed and in most cases will not have the pullback capability to extract tooling safely. One way to solve this problem is to seek outside resources from specialists who have the experience in handling such large diameter works. By outsourcing or subcontracting different parts of your job to different specialists you can avoid an expensive learning curve and you can actually capitalize on their expertise and keep your foundation drilling job profitable. 3

5 3. Bid Your Projects Effectively While it s a foregone conclusion that it s impossible to predict how things will turn out in a drilling job, it is important prior to bidding of any job to thoroughly examine the project requirements. The size, scope, construction method and the quantity of the piles; geotechnical considerations; delivery of supplies to the site; your machineries capabilities; and the way payments are processed all affect the profitability of foundation drilling. Proper site investigation should show the geological conditions that the job will need to be performed in. However it is not uncomm0n to encounter conditions that vary from what the site investigation shows. As part of the bidding process the construction process that the drilling contractor will use is specified. If this needs to be changed during the job due to such a change in geology it is important that this is addressed in the bid, and responsibility for the additional costs identified. Foundation drillers should ask for specific performance criteria, such as permissible movements of structures, as part of pre-bid questioning so that the driller can identify suitable drilling and grouting procedures to effectively meet the project goals. There are many ways drillers are paid by the prime such as per pile accepted by the engineer, per pile placed with access tubes for down-hole integrity testing accepted by the engineer, per pile for integrity testing on a production pile, per pile for rapid load test on a production pile, per pile for dynamic load test on a production pile, and lump sum for pre-production test program as approved by the engineer. The contractor should have a clear-cut understanding of payment mechanism of the prime contractor and this should ideally be included in the bid and final agreement. 4

6 4. Plan Your Deliveries In the foundation drilling industry, the manufacturing timelines for much hardware especially the specialty tooling can take about 5 or 6 months. Such long manufacturing lead times have the potential to shut down operations due to down time. It is important for drilling contractors to understand how these delivery schedules affect the progress of their work and plan things accordingly. A clear definition of the scope of the work of the drilling contractor, the size and scale of the drilling operations, and a meticulous understanding of what is needed to effectively do the work helps you correctly assess the material requirements, their manufacturing timelines and scheduling of the entire job operations. The driller needs to understand the human resource requirements, plant and machinery requirements, construction materials requirements, coordination requirements, materials delivery scheduling, traffic management, and then plan labour, plant, equipment and tools, and construction materials in an effective way. 5. Adhere Strictly to Drilling Rules and Regulations As in water well drilling, the rules and regulations related to foundation drilling vary from state to state and country to country. As a foundation drilling contractor you have a requirement to understand these regulations. Should you accept a job in another province or country, it is very important that you acquaint yourself with all the statutory rules and regulations and strictly adhere to them. Some local authorities recognize only certain types of piles and restrict construction of other types. Some drilling practices, which are safe and legal under a different authority, might be banned in some places due to safety or geological considerations. For example, in the state of New York, a contractor is not allowed to advance the inner drill bit in front of the casing due to concerns about hole cavitation. 5

7 Usual regulations such as having your piling construction plans authorized by the local authority; details of monitoring requirements for the adjacent and nearby buildings, structures, land, streets and services arising from the proposed piling works; the contingency measures taken to avoid any calamity; pre-design ground investigations; pre-drilling studies; post construction proof drilling; rules regarding ground-borne vibrations and ground settlements arising from pile driving and similar operations; quality supervision; and on-time submission of piling record plans and reports must all be followed strictly. Not adhering to the rules and regulations related to drilling and not working within the specified parameters in an area may put you on the wrong side of the law and you may get fined or worse, an on-site inspector might shut the job site down. Apart from the above mentioned job-specific regulations, drillers need to respond in an appropriate manner to safety standards or regulations, which affect the operations. They should place the safety and well-being of their workers first, and be honest in the pursuit of safety standards. Drillers should regularly review and periodically update the safety requirements for the installation of piles, anchored earth retention systems, drilled shafts, and micro piles. Adequate education and training for the safe installation of deep foundations must be provided to your crew. 6. Build an Effective Relationship with the Prime Contractor The relationship between the prime contractor and subcontractor is an extremely important one. To this both the parties should do everything possible to manage this relationship as being as productive and positive as possible. Delays in deliveries, additional costs, changes in projects, and timely release of payments are some common irritants in the relationship between the prime contractor and subcontractors. It helps to clearly define how payments shall be made and on what basis they are made in a written agreement. It is not uncommon for a prime contractor to request that certain changes are made during the completion of the project. In such a case the subcontractor should ensure that all such requests are in writing. Revised completion schedules and additional costs if any should be defined also. 6

8 Contracting arrangements are usually framed so as to ensure that not only are subcontractors fairly managed, but also that prime contractors are able to hold subcontractors to account for poor performance and, where necessary, terminate agreements with subcontractors who are not performing to agreed standards. Understand that success in this profession depends on effective relationships between prime contractors and subcontractors. 7. Effective Production Management is the Key Unlike geothermal well drilling or water wells, foundation drilling assignments are not stand-alone jobs; they are a small cog in a large wheel. What drillers can do and when they can are subject to the requirements of the larger construction project they are part of. A significant part of their operations are beyond their control. Foundation drillers have to operate within this window and parameters. To effectively meet these challenges, foundation drillers need to excel in production management. They need to mobilise all the resources they need the tooling, the rig, the compressor, the concrete, and other supplies - on site to complete the job on time. Suspending work because some material has to be delivered on site reflects poorly on the contractor s professionalism. A superior knowledge of the requirements, procedures and materials that are needed to undertake drilling operations is necessary. Experience, either your own or of outside collaborators, in implementing appropriate procedures and techniques for the safe, effective and efficient achievement of the required drilling operations is important. Back-up plans should be ready to handle various frequently encountered problems during drilling operations such as keeping the hole open to carry out pile construction, equipment failure, drill string bogging, controlling drill hole direction, control of hydrostatic pressures, disposal of waste material and drilling in difficult ground. As in any other construction-related activity, successful production management involves careful planning, daily production meetings, job box meetings, midcourse corrections and working with others to plan, prepare and execute proper effective drilling operations. 7

9 8. Your Job is Not Done Till it is Approved To have your work approved you need to work with different kinds of inspectors, especially geotechnical engineers. Once the piles are built they will be subjected to load tests, side load, proof tests on foundation and other tests to check their integrity. Alternative procedures and acceptance criteria, or methods other than test loading or core-drilling, which can demonstrate the performance of the foundation under loads or verify the integrity and the load-response interaction between the foundation unit and the bearing stratum may also be performed by the inspectors. The construction is certified only after satisfactory piling records have been submitted; the required proof tests have been satisfactorily carried out; and all relevant imposed conditions including materials testing requirement have been complied with. Since drillers can t get their money unless their work is certified, they need to work closely with inspectors and assist them in assessing and certifying drilling work by providing them all the necessary information. Conclusion As you can see there are a number of factors to consider when planning and executing Foundation Drilling projects. By following these steps and taking action you can significantly improve the profitability of your contracts. I m sure like most foundation drilling contractors you have a wealth of knowledge and a lot of these steps will not be totally new to you. However it is worth taking a step back from your business sometimes and asking yourself if hand on heart you do actually follow all of these steps. 8

10 About Mincon International Mincon International was established in Shannon, Ireland in 1977 and has grown into a global business with a presence across 6 continents. Mincon produce a range of high quality DTH hammers and bits for a wide variety of drilling applications. With three state of the art manufacturing facilities in Shannon, Ireland, Benton, Illinois, USA and Perth, Australia, Mincon can supply its products worldwide. If you need specific advice on your next drilling project or would like to arrange a site trial with our hammers and bits then get in touch with your local office today: 9