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Implementing quality control in HDD projects—a North American prospective
Tunnelling and Underground Space Technology 16 Suppl. 1 (2002) S3–S12
Implementing quality control in HDD projects—a North American prospective Erez N. Allouche* Department of Civil and Environmental Engineering, University of Western Ontario, London, Canada
Abstract The Horizontal Directional Drilling (HDD) industry in North America has experienced a tremendous rate of growth within the last decade. However, the development of acceptable operating standards and quality control (QC) and quality assurance (QA) procedures significantly lags behind the current utilization level of HDD. This gap is now considered to be one of the main obstacles for wider acceptance of HDD by the engineering community in North America. This paper describes various risks and quality-related problems in HDD practice. Recent efforts to promote and regulate quality project delivery in HDD projects are outlined. Thereafter, quality control and quality assurance are defined in the context of HDD. It is recommended that a universally recognized standard such as ISO 9000 be adopted as the basis for an industry-wide quality management system. Examples of how to customize selected ISO 9000 clauses to meet the directional drilling industry’s QCyQA needs are given. Additionally, a new approach for QC during HDD installation is described and its merits discussed. 䊚 2002 Elsevier Science Ltd. All rights reserved. Keywords: Horizontal directional drilling; North America; Quality control; Borehole monitoring
1. Introduction The Horizontal Directional Drilling (HDD) industry has experienced tremendous growth in recent years that has been supported by technological innovations, a strong economy, the telecommunication revolution and the need to reduce the impact of construction activities in urban areas (Carpenter, 1999). During this time, limited attention was given to the development of industry standards in terms of quality control (QC) and quality assurance (QA). Developments in these areas were primarily in response to needs of a specific segment of the industry or challenges posed by a particular project. One example involves the development of breakaway pins by the natural gas industry to protect medium density polyethylene (MDPE) pipes from excessive tensile loads during installation (Troch and Doyle, 1998). The industry at large has limited itself to inspection and testing, a lower level of quality commitment. Sample practices include pulling out a short section of pipe from the exit bore to inspect for damage (CALTRANS, 1999), pressure tests, and CCTV inspec*Tel.: q1-519-661-4197; fax: q1-519-661-3942. E-mail address: [email protected] (E.N. Allouche).
tions of municipal installations (Allouche and Ariaratnam, 1999). As the HDD market matures there has been a growing need for the implementation of higher levels of quality commitment. This demand is fueled, on the one hand, by owners seeking warranties for long-term performance and, on the other hand, by tighter profit margins and thus the need for greater efficiency. Additionally, an increase in market share in key sectors, an essential condition for future growth, is dependent to a great extent on a reduction in the perceived risk associated with HDD installations. One such sector is the municipal area, a conservative market that to date has hesitated to endorse HDD to the same extent it is utilized in the telecommunications and electrical conduits markets. In fact, several municipalities in California have declared a moratorium on HDD activities in their jurisdictions as a result of poor performance including heave in roads, damaged sidewalks and foundations, and repeated ‘hits’ of existing buried services (Ariaratnam, 2001). With nearly 7000 HDD rigs operating daily across North America the issue of avoidance of existing buried utilities is rapidly becoming a major problem. Recently, the telecommunications industry in the United States (US) has established the
0886-7798/02/$ - see front matter 䊚 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 8 8 6 - 7 7 9 8 Ž 0 2 . 0 0 0 6 2 - 7
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Fig. 1. Levels of quality commitment.
‘National Telecommunications Damage Prevention Council’ (NTDPC), an organization responsible for promoting awareness and new technologies for detection of buried pipes and conduits. Owners of buried infrastructure also have begun to prosecute HDD contractors who repeatedly damage buried lines. Quality control (QC) and quality assurance (QA) are among the best available means to minimize these hits and the liability associated with HDD work for all parties involved. The first section of this paper is devoted to an overview of quality management theory and its applications in the area of construction. Thereafter, potential risks in directional drilling installations are described and recent efforts to promote quality project delivery in the HDD industry are presented. Selected ISO 9000 clauses were customized to meet the HDD industry QCy QA requirements, as an example of a futuristic industrywide QCyQA standard. A new approach currently under development at the University of Western Ontario to enhance quality control during HDD installation is also described. The paper concludes with a discussion of current needs in the area of quality management in the HDD industry. 2. Quality management—theory and terminology Reaching an agreement on the definition of quality is no simple task. For the purpose of this paper, quality will be defined as ‘free from deficiencies and fit for use’. Quality management is a tool aimed at risk mitigation, prevention, minimization of losses through the elimination of poor practices and the optimization
of day-to-day processes and procedures. Voluntary quality systems are common practice in the manufacturing sector using a combination of internal and external audit systems. In recent years, the concept of quality control has begun to gain acceptance in the North American construction industry. There is a family of quality standards working in unison that enables an organization to develop a quality management system. Fig. 1 illustrates the levels of an organization’s quality commitments and their associated hierarchy. The discussion in this paper is limited to the three lower levels—inspection, quality control (QC) and quality assurance (QA). 2.1. Quality control Quality control involves techniques and activities aimed both at monitoring processes and eliminating causes of unsatisfactory performance. It is concerned with processes and operational techniques and aimed at achieving and sustaining the planned quality criteria, using feedback from inspection at various stages in the process to identify inefficiencies and implement corrective actions. In the construction industry, the quality of the finished work is commonly controlled by means of inspection and random sampling and testing as construction proceeds. The major drawback of this ‘inspectorial system’ of quality control is that it defines the mistakes after the event. Additionally, many defects are covered up during subsequent construction activities and consequently the quality of the finished work cannot be assessed by final
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inspection (Bubshait, 1999). This is particularly true in trenchless construction, where in most cases the installed product cannot be easily accessed for direct inspection without defeating the purpose of using a trenchless method.
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● Turnover of manpower in construction is higher than in manufacturing, which increases the cost of training and makes long-term planning difficult.
While quality control is an organization’s technical arm, quality assurance serves as a management tool. In contractual situations, quality assurance also serves to elevate the client’s or supplier’s confidence in the ability of the firm to fulfill its commitments. To practice quality assurance, an organization has to establish and maintain a quality system in its day-to-day operations. A quality system contains, among other things, a set of documented procedures for the various processes carried out by the organization. Implementing a quality assurance system does not replace the existing quality control functions nor does it result in more inspection and testing; it just ensures that the appropriate type and amount of verification is performed as scheduled. This is why a quality system is sometimes referred to as a QCyQA (quality controlyquality assurance) program. Quality assurance is oriented towards prevention of quality deficiencies by minimizing the risk of making mistakes in the first place, thereby avoiding the necessity for rework, repair or rejection. Quality assurance systems involve internal and external aspects. An internal quality system covers activities such as an internal audit whose aim it is to provide confidence to management that the intended quality is being achieved. An external quality system covers activities, such as ISO 9000 registration, aiming at inspiring confidence in external clients or permitting agencies that the product or service provided satisfies acceptable quality requirements. This confidence comes from the objective evidence that systems and controls are in place and working effectively, i.e. quality manuals, procedures, audits and reviews.
While the above arguments are valid, it is important to realize that it is the repetition within the construction processes themselves that permit quality management to work. Aspects such as administrative procedures, construction practices, format and frequency of communication, and decision-making processes form the basis for a firm’s efficient and effective operation and are independent of the actual projects themselves. The successful implementation of a formal quality management system can allow a construction firm to realize numerous benefits including: improvement in workmanship and efficiency; a decrease in wastage and rework; increased safety; reduced losses and downtime due to accidents; identification and elimination of inefficient practices; and improvement in the flow of activities and coordination of the organization. The results are not only improved profitability but also growth through an improved quality image. The establishment of confidence in the quality of productyservice delivery is of utmost importance to the trenchless industry, since in many cases a visual examination of the installed product is difficult if not impossible to achieve. A formal commitment by the contractor to deliver quality service can inspire a client’s confidence and readiness to try a new technology. A recent moratorium of HDD activities in some US municipalities and high fines handed down by various courts in compensation to utility owners for losses incurred due to inadvertent drilling that damaged existing services are initial signs of a potential confidence crisis in the safety of utilizing HDD in urban environments. An industry-wide QCyQA program can alleviate much of the anxiety some engineers and contract administrators might feel towards this construction method as well as assisting HDD contractors to demonstrate due diligence in cases where damage to existing services did occur.
2.3. QCyQA systems in construction—obstacles and benefits
3. Risks and potential quality deficiencies in HDD operations
The adoption of formal QCyQA systems, such as ISO 9000, by construction firms in North America is not as common as in other industries, such as manufacturing. This is attributed mainly to the following:
The following sections describe operational risks and potential quality deficiencies associated with HDD operations.
2.2. Quality assurance
● Each construction project is a prototype encompassing a unique location, design, site constraints and a owner–designer–contractor team. In contrast, manufacturing relies on systems of mass production wherein most parameters are relatively stable. ● It is common to separate contracts for design and construction, thereby reducing the effectiveness of a QCyQA program.
3.1. Damage to the pipe column The nature of the damage that might be inflicted on a pipe column during a HDD installation depends primarily on the pipe material. Polyethylene (PE) pipes may be subjected to an excessive tensile force during installation. That could result in permanent deformation, consequently reducing the pipe’s mechanical strength and useful service life (i.e. years prior to replacementy
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rehabilitation). In extreme cases, the PE pipe might rupture. While the latter case is easily identifiable, the former case is very difficult to detect. Other damage that a PE pipe might experience includes grazing and denting during the installation process due to sharp stones or other objects projected into the borehole. Such damage might initiate crack propagation in PE pipes and corrosion in steel products. Kinks in the pipe might be the result of failing to maintain the minimum bending radius or the presence of large obstacles along the borehole. Such kinks might result in the onset of local buckling in steel pipes (O’Donnell, 1996) and reduced ovality in PE pipes. In many cases, it is difficult to establish whether poor product qualityyselection, inadequate borehole design or poor construction practices led to the failure. 3.2. Utility avoidance Failure to avoid existing utilities presents a serious hazard and a major cause of third party damage, and subsequently is a source of much concern in North America (Ariaratnam, 2000; Norman, 1999). An inadvertent encounter of the drilling head or the reamer with high voltage electrical cables presents a danger to the drilling crew. In the case of an encounter with a pipe carrying natural gas or other highly flammable substances the public at large is put at risk. In 1993 alone there were approximately 104 000 hits or third party damage to gas pipelines across the US with total costs exceeding $86 million (Doctor, 1995). The danger is particularly severe when the damage is not detected immediately, allowing flammable materials to enter other buried networks such as sewers, and from there into adjacent homes. Sterling (1999) reported an explosion in a home that has been traced to a damaged natural gas pipeline during an HDD installation that took place sometime prior to the incident. Other secondary damage includes pressurized water mains and sanitary sewers that might wash out roads and other surface improvements (Norman, 1999). The costs associated with damaging an existing utility can be significant and include the cost of the repair itself, project downtime, secondary damage, and in some cases, the downtime cost for the utility provider. 3.3. Environmental damage The most common type of environmental damage associated with HDD is ‘frac-out’, an unintentional return of drilling fluids to the surface. The phenomenon occurs when the drilling fluid pressure in the borehole exceeds the confining pressure of the overburden. Alternatively, drilling fluids from the borehole might migrate through existing fissures in the formation. Frac-out is also possible when pilot bore drilling or back-reaming
operations are conducted at an excessive rate, not allowing sufficient time for the cuttings to be washed out of the borehole (Gelinas and Mathy, 2001). In most cases, the impact of a frac-out is reduced public satisfaction as drilling fluids tend to take the path of least resistance and surface in driveways, gardens and near utility poles. In the case of crossing a natural watercourse or an environmentally sensitive area, introducing a large volume of drilling fluids into the aquatic environment can be detrimental to the local ecosystem. In the case of man-made canals, weep-tile systems can be silted up, requiring an expensive cleanup operation. If contaminated ground is encountered, drilling fluids can become contaminated, thus exposing those on the surface to the contaminants. Finally, drilling fluids might also present hazard to traffic by making roads slippery, and in any event presents an eyesore. 3.4. Damage to surface improvements and adjacent structures Pressurization of the borehole by the drilling fluids andyor over-compaction of the borehole walls during the pilot drilling and back-reaming operations (instead of cutting the soil and removing it to the surface) can cause surface heave due to an upward deformation of the formation (Canon, 1998). Consequently, roads and driveways crack; sidewalks heave and pedestals lift. Adjacent utilities and foundations can also sustain damage due to soil deformation (Chapman and Hunter, 2001). Common causes for excessive soil deformation include insufficient burial cover; insufficient clearance; excessive pilot drilling or reaming rates; failure to use drilling fluids to suspend and wash the soil cuttings outside of the borehole; and, borehole enlargement in too large increments (i.e. utilizing too few pre-ream operations). 3.5. Non-conforming installation The term ‘non-conforming installation’ refers to failure of the installation to meet technical requirements specified in the contract. Examples of non-conforming installations include: 1. failure to complete the installation from the entry to exit points; 2. unacceptable degree of damage to the pipe column (discussed in Section 3.1); 3. failure to steer the drilling head to an exit point located within an acceptable tolerance window; and 4. failure to maintain grade and alignment of installed products within pre-specified tolerances (e.g. gravity sewers). The causes for a non-conforming installation might range from poor drilling practices to inadequate soil investigation and improper selection of pipe product.
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4. Current efforts to promote quality project delivery in HDD The horizontal directional drilling construction process makes it difficult to ensure quality project delivery. The entire construction process takes place below ground level and is not accessible for visual inspection. In addition, drilling and reaming actions commonly take place tens or hundreds of metres away from the drill rig. Identifying problems before they arise, and in some cases even after they are encountered, is difficult when one considers the concealed and remote nature of the HDD process. Furthermore, in some cases even if the problem (e.g. pipe rupture, peeling of coating) was detected during or immediately after the installation process, repair requires digging out the entire installation, extracting the pipe or abandoning the original alignment altogether. Finally, the lack of accessibility makes it difficult for an independent verification of the quality of the installation by the contract administrator. Industry associations, large users or HDD services and permitting agencies have adopted several approaches to meet the challenge of ensuring quality project delivery in HDD operations. These include construction specifications and best practice guidelines; contractors’ prequalifications; and operator certifications. The following sections provide short descriptions of these methods and the current level of their implementation. 4.1. Specification and guidelines Currently, the industry in North America is governed by generally accepted practices with no specific regulations with which to comply. General construction guidelines (Ariaratnam and Allouche, 2000; CALTRANS, 1999; OPSS, 2002) are available in the industry and may range from recommended practices to project requirements. The available specifications are mainly concerned with general construction practices. The sections devoted to quality control are very limited, primarily due to a lack of means to perform direct measurements of the quality of the installation. Manufacturers’ specifications for steel and polyethylene pipes are used to specify the maximum allowable tensile and bending stresses during installation. However, to date there is no commercially available technology in North America to directly measure the loads applied to the pipe column during the installation, and current prediction models are inconsistent and inaccurate (Baumert and Allouche, 2002a). There has been a recent movement in the US towards the certification of HDD rig operators (Allouche, 2000) in order to provide some industry consistency. At present, government agencies and a consortium of industry associations are leading the development of a national best practices guideline in the US (Hemphill, 2000).
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4.2. Pre-qualification and certification The shortcomings of the available construction specifications require owners to rely to a great extent on indirect measures for ensuring quality project delivery. Two approaches namely, pre-qualification and certification, might be adopted routinely in North America to ensure that the desired levels of experience and expertise are present in a HDD construction project. Pre-qualification is a widely utilized approach in the construction industry for contractor screening. It is typically used in conjunction with performance-based contracts or contracts that involve specialized construction methods, both attributes of HDD projects. Pre-qualification is a process whereby a contractor must meet certain administrative, experience andyor technical requirements to be able to submit a bid. Key elements for pre-qualification include experience in similar projects as well as having the technical expertise and financial capacity to execute the project. Specific pre-qualification requirements might include an implemented safety program, an outline of construction sequence, equipment capacity, the experience of the company and the crew, a drilling fluids management plan as well as proof of an adequate line of credit. Certification of the HDD operator is another way of trying to ensure quality installations. The rig operator is required to have completed formal training and to have passed a test that demonstrates a minimum level of knowledge with respect to issues such as preparation of a drill path profile; setup of the drilling rig and support equipment; and drilling fluids. The candidate must also be proficient in construction practices including drilling a pilot bore, tracking and installation of the pipe product as well as the proper response to various emergency situations. HDD certification programs are currently being offered primarily by the North American Society for Trenchless Technology (NASTT), in collaboration with local agencies (e.g. California Department of transportation). Several educational institutes, such as Missouri Western State College, also offer training and operating programs on an intermittent basis. Operator certification programs are recognized by many owners and contractors across the continent, however they are rarely required as part of the pre-qualification process. The certification and pre-qualification systems in the HDD industry in North America are ‘single level’, and are not limited by type of machinery, pipe diameter, nature of installation or length of installation. 5. QCyQA in the HDD industry As discussed in Section 2.3, individual firms and the trenchless industry as a whole can reap many benefits from the adoption of a formal QCyQA program, a management tool aimed at optimizing day-to-day oper-
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ations and procedures to minimize or eliminate poor project outcomes. The following sections describe various practices that can be adopted by HDD contractors to increase the level of quality control prior to and during the construction process. It is proposed to implement these measures via the framework of ISO 9000, a generic series of quality management and assurance standards accepted around the world. Thereafter, a new approach for implementing quality control during HDD installations is presented and its merits discussed. 5.1. ISO 9000 In 1987 the International Organization for Standardization (ISO) published ISO 9000, a single generic series of quality management and assurance standards. Due to its generic nature the 9000 series is an excellent foundation for developing specific and comprehensive quality systems tailored to particular industries. Over the past 15 years, ISO 9000 has been adopted by a large number of industries around the world and is currently recognized as the world’s leading quality systems standard. ISO requires that a company establish, document and maintain a quality system. It outlines definitions and document requirements as to how quality standards will be met, and mandates the documentation of all ISO procedures in a quality manual. The following discussion was organized to follow selected clauses in the ISO 9000 that were customized to reflect the nature and realities of the HDD construction process. For the development of a unified QCyQA for the industry, or for selected organizations, it is recommended that the relevancy of all twenty clauses supported by ISO 9000 be examined. More information regarding ISO 9000 can be found in Randall (1995). 5.2. Management responsibilities ISO philosophy is that good communication among all levels and a clear description of everyone’s responsibilities are basic requirements for a company success. A document expressing the responsibilities, authority and interrelation of each individual who may manage, perform and verify work affecting quality is a necessary step in the development and management of a system. It allows easier identification of resource requirements and the ability to adequately provide for them. Defining the duties and responsibilities of each individual promotes communication and cooperation among the various levels. 5.3. Contract review The ISO standard requires that the organization has documented procedures for contract review and for coordination of activities. Before acceptance of the
contract, the organization must review it to ensure that: (1) all requirements are adequately defined; (2) all verbal requirements are documented; and (3) the organization is capable of assuming all of the risks stated or implied in the contract. The contract review procedure is a checklist that ensures the contract provides sufficient protection to the contractor for foreseen and unforeseen risks. For example, the contract should address issues such as: compensation for incompleteyabandoned installation; compensation for multiple attempts; costs and liabilities associated with inadvertent returns and fracouts; adverse subsurface conditions; and circumstances under which the installation will be abandoned. 5.4. Design control The main objective of design quality control is to reduce design errors and costly changes during the construction process. Unlike most other segments in the construction industry, the involvement of consultant engineering firms in HDD projects in North America is limited. Many contractors prepare their own designs, especially in the case of short-to-medium length crossings. A HDD contractor should develop a guideline for the preparation of design and planning documents for every crossing. Key elements in the design guideline should be: ● Plan view—showing equipment footprint; entry and exit points; alignment; layout of string pipe; and significant surface features (e.g. roadways). ● Elevation view—showing the location and elevation of all known utilities and other buried obstacles; nature of the various utilities and clearance from the proposed installation. ● Construction sequence—size of pilot bore and prereaming operations; proposed borehole tools. ● Risk assessment—covering anticipated soil conditions (i.e. gravel, swelling soils); potential sources of electromagnetic interference; sensitive environmental areas; clearance from known utilities; transportation corridors; and potential areas where a frac-out may occur. ● Proposed mixture of drilling fluid (bentonites; polymers or a mixture of both); target marsh funnel viscosity for raw drilling fluids; additives and their proposed quantities per unit volume or weight. The plan will be prepared by the crew supervisor and will be submitted for review and approval by the next level in the organization’s hierarchy (e.g. project coordinator). The extent of documentation and the level of details will be a function of the project size and complexity, and should be aimed at meeting regulatory and client requirements. Proper planning is invaluable during both mobilization and construction, while proper
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design documents can be used to establish the firm’s due diligence in the case of damage to a third party. 5.5. Process control A detailed procedure for every routine activity performed during the mobilization, construction and demobilization phases should be developed and documented. These procedures will represent ‘best-practices’ and will be used for training as well as for the development of checklists to be used on the job site. Such ‘best practices’ may range from the proper way to anchor the rig to specifying the maximum recommended penetration and pullback rates for various formations and borehole diameters. Additionally, special procedures should be developed for emergency situations such as inadvertent drilling into a buried utility or a frac-out into a surface body of water. Quality control requires the development of such procedures; quality assurance ensures that they are followed as part of the organization’s daily routine. The combination of both is a powerful tool when it comes to demonstrating an organization’s due diligence in a court of law. 5.6. Monitoring, inspection and testing The main objective of the contractor inspection and testing program is to provide objective evidence that proper practices and materials are used during every phase of the project. The inspection and testing procedures specify quantatively and qualitatively acceptable criteria for construction workmanship and materials. In the context of HDD, inspection and testing measures can be classified into three categories A. Prior to commencement of drilling operations ● Testing of the fabricated pipeline product (e.g. Xray tests; pressure testing). B. During drilling operations ● Testing the compatibility of drilling fluids with the in-situ soils (e.g. marsh funnel viscosity test). ● Excavation of small observation shafts along the installation path to visually inspect the condition of the pipe as it is pulled through the borehole and verify that the back-reamer clear crossing utilities. ● The placement of weak-links, or breakaway swivels, between the pull-head and the reamer to prevent excessive pulling forces from being applied to the pipeline product. ● Pulling a test section (‘pig’) through the borehole prior to product installation to confirm that the borehole is clear of obstacles. ● Placing an electronic transmitter between the reamer and the pull-head to track the path of the pullback operation.
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● Monitoring the drill rig’s hydraulic gauges as a rough indication of the thrust and torque transmitted to the drill string. C. After drilling operations ● Pulling a section of the pipe equal to 1% of the total installation length or 2 m, whichever is less, out of the exit hole to inspect for damage (e.g. scours, dents). ● Running an electronic transmitter through the installed pipe to verify its location. ● A flow test and a CCTV inspection of the pipe interior to confirm that there are no sags in gravitydriven sewer lines installed using HDD. ● Pulling a short conical tube of a diameter somewhat smaller than that of the pipe’s internal diameter (i.e. a mandrel) to verify that the pipe is free from an unacceptable degree of ovality. 5.7. Document and data control Clear procedures must be established detailing the types of data to be collected, who should collect it and who should receive it. The term ‘data’ refers to accounting information, maintenance records; safety documents; internal audits; site reports; procurement records, etc. Proper data flow and handling procedures ensure that the correct information reaches those individuals who can act upon it in a timely manner. 5.8. Training ISO 9000 calls for establishing the experience and skill requirements for every position in the organization. A gap-analysis is then performed to identify any shortfalls and corrective actions required to close this gap by providing appropriate training. Examples of such training are operator certification courses, safety courses, project administration courses and butt-fusion tickets. 6. New approach to quality control in HDD Section 5 covers various clauses of ISO 9000 applicable to HDD contractors and their projects. This section describes a new tool that can significantly contribute to a high degree of quality control during horizontal drilling installations. One of the most costly problems that HDD contractors can face is non-conformity of the installed product, due to either: (1) failure to maintain the pipe product within the specified alignment and profile tolerances; or (2) pipe damage. The latter can take various forms including buckling due to excess bending forces; compromise of the product’s wall thickness due to deep cuts; peeling of the exterior protective coating; localized deformation of the product’s cross-section; and rupture of the pipe product. These problems are discovered only after the problem has occurred. At this point it is often
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Fig. 2. Prototype smart load cell with radio transmitting capabilities placed between pull-head and reamer.
too late to initiate a corrective action and the only recourse is to remove the product andyor install a new product. Another potential damage during an HDD installation includes permanent deformation of the pipe due to excessive tensile force that may hinder the pipe’s structural strength and reduce its useful life. However, unlike previously mentioned non-conformities, this problem is difficult to identify during the construction process or immediately after it. To mitigate this problem some owners require the utilization of weak-links or breakaway swivels to prevent the application of an excessive tensile force onto the pipeline product. However, such practices result in ‘jamming’ the pipeline product in the borehole and subsequently a costly recovery of the pipe and re-installation. The contractor may lose not only the time spent on the failed installation and recovery of the product, but also the time spent on drilling the pilot bore if this cannot be re-used. The owner, on the other hand, may lose the pipeline product due to damage inflicted during the recovery operation or failure of such an operation. This approach may also penalize the contractor unnecessarily, as the application of high pulling forces may be the result of adverse soil conditions such as cobble or swelling clays. The con-
tractor may also be penalized for the specification of an undersized product by the owner’s representative. Additionally, it is unlikely that a thermoplastic pipe will suffer permanent damage from a single incident in which the specified load capacity was exceeded by a few percentage points over 20 or 30 s. However, under such conditions the weak-link will fail. Finally, the machine operator can learn little from the incident with respect to avoiding such failures in the future. In fact, many contractors view weak-links as an unnecessary risk in an already risky business and as a practice of questionable fairness. Subsequently, there is increased likelihood of fraud andyor an adverse relationship between the contractor and the owner. The smart load cell presents an approach that provides increasing quality control to the contractor and quality assurance to the client while avoiding most of the disadvantages associated with weak-links. The load cell is placed between the pull-head and the back-reamer, as shown in Fig. 2. The device is instrumented to measure the tensile force transferred from the reamer to the pullhead with an accuracy of "1%. The maximum capacities of the prototypes fabricated to date range between 50 and 245 kN (Baumert and Allouche, 2002b). Within
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Fig. 3. Sample data from a smart load cell.
the load cell there is an electronic system that converts the strain measurements to loads, and records them as a function of time. When the installation has been completed the data can be downloaded into a laptop computer and presented using Excel or other commercially available spreadsheet software. Alternatively, the load cell data can be transmitted during the installation in real-time via a radio transmitter to a display unit at the drilling rig. Based on the manufacturer’s maximum allowable loads, the installations can be categorized as either: ● Acceptable—allowable stresses were not exceeded during the installation. ● Fair—a few minor violations of maximum allowable stresses. ● Poor—multiple minor-to-moderate violations of maximum allowable stresses. ● Unacceptable—gross violation of maximum allowable stresses. Additional research is needed to establish acceptable criteria for ‘Fair’, ‘Poor’ and Unacceptable’ ratings. Based on the rating and specific site conditions, the installation will be declared to be: (1) acceptable; (2) acceptable but the contractor will be subject to a financial penalty due to poor performance; (3) unacceptable. The proposed system will enable expert judgment based on objective data rather than an instantaneous maximum loading condition to determine the fate of the installation. Contractors will realize substantial savings due to a reduction in the amount of rework, while owners will benefit from a high quality QCyQA system that is resistant to fraud or tampering. Additionally, the proposed system is not only fair, but it also provides excellent feedback to the operator regarding the impact of hisyher practices on the load applied to the pipe (Fig. 3). Based on this feedback, operators will be able to continuously improve their skills and understanding of the interaction between subsurface
conditions, borehole geometry, drilling fluid compositions and the force required to pull the product through the borehole. 7. Discussion and conclusions The successful implementation of a quality system can greatly benefit an organization in terms of improved profitability and growth via increased efficiency and improved quality image. The relatively low number of HDD firms in North America that have an official quality management program is due not only to the common obstacles facing most construction firms discussed above, but also to the special characteristics of the industry including: ● The concealed and remote nature of the HDD process makes it difficult to identify problems before they arise and in some cases even after they are encountered. Even if a problem was identified during the construction process, the corrective actions that are available are limited. ● Lack of means to perform direct measurements of the quality of the installation process. ● Lack of established standards and acceptable practices in North America-design specifications are scarce and construction specifications are still in their infancy. ● Fragmentation—the North American industry is comprised primarily of relatively small dedicated contractors, making it difficult to allocate the financial means needed to establish a formal QCyQA program. Nevertheless, there is growing recognition of the need to develop and implement a voluntary unified QCyQA standard in order to reduce the risks associated with the utilization of the HDD method, and subsequently to ease its acceptance by the engineering community. It is suggested that this QCyQA standard be based on an established and proven generic framework such as ISO 9000.
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A key obstacle is the difficulty in obtaining direct objective feedback as to the contribution, or lack thereof, of various practices to the quality of the installation. Recent efforts for developing means and measures that promote project quality delivery prior to, during and following an HDD installation were described in this paper. The most notable of these is the development of weak-links to protect PE pipes from damage due to excessive tensile force. However, in doing so, the construction process is being terminated, resulting in costly remediation measures to the contractor and potentially to the owner. Additionally, many contractors question the fairness of this approach as it may punish them not only for poor construction practices but also for adverse subsurface conditions and undersized products. An alternative approach to control tensile forces during HDD installations is the utilization of smart load cells. These devices measure and record the installation loads during the construction process. Based on these records and an assessment of the local subsurface conditions, the installation can be accepted or rejected by the owner. The data collected are also an invaluable asset for the training of drill operators. References Allouche, E.N., 2000. Prequalification and certification of HDD contractors. No-Dig Eng., USA 7, 11–14. Allouche, E.N., Ariaratnam, S.T., 1999. Municipal applications of horizontal directional drilling: construction considerations and Canadian case studies. Proceedings, INFRA ‘99 International Convention, Montreal, Nov. 22–24, Session 6B, 18 p. Ariaratnam, S.T., 2001. Overview—Horizontal Directional Drilling Training and Certification. North American Society for Trenchless Technology Workshop, May 16, Markham, ON, Canada. Ariaratnam, S.T., 2000. Avoiding the hazards of directional drilling. Utility Safety Mag. 3, 19–21. Ariaratnam, S.T., Allouche, E.N., 2000. Suggested practices for installations using horizontal directional drilling. Practice Periodical on Structural Design and Construction, ASCE, Vol. 5, No. 4, November, pp. 142–149.
Bubshait, A.A., 1999. ISO 9000 quality standards in construction. J. Manage. Eng., ASCE 15, 41–46. Baumert, M.E., Allouche, E.N., 2002a. Methods for estimating pipe pullback loads for HDD crossings. J. Infrastruct. Syst., ASCE 8, 12–19. Baumert, M., Allouche, E.N., 2002b. Real-time monitoring of HDD installations. Underground Construction Technology Conference, January 15–17, Huston, Texas, Track IX-A, 17 p. CALTRANS, 1999. Guidelines and Specifications for Horizontal Directional Drilling Installations. Headquarters Office of Encroachment Permits, July, 26 p. Canon, F., 1998. Fluid volumes—how much is enough. Directional Drilling 4, 47. Carpenter, R., 1999. A comprehensive HDD survey details industry growth trends. Underground Construct. 54, 36–37. Chapman, D.N., Hunter, A.E., 2001. Developing safe proximity charts for impact moling and horizontal directional drilling operations. Proceedings of The International Conference on Underground Infrastructure Research, Kitchener, Ontario, June 11–13, pp. 239– 245. Doctor, R.H., 1995. Third party damage prevention systems. Final report for the Gas Research Institute, Contract 5094-810-2870, by Nicor Technologies, Naperville, IL. Gelinas, M.M., Mathy, D.C., 2001. Horizontal directional drilling: lessons learned in conduit installation. Proceedings of The International Conference on Underground Infrastructure Research, Kitchener, Ontario, June 11–13, pp. 247–256. Hemphill, J., 2000. Cooperative efforts solidifies HDD future. Directional Drilling Mag. Oct., pp. 21–23. Norman, R.S., 1999. Obstacle Detection for Guided Directional Drilling for Gas distribution Applications. Trenchless Technology Mag., June, pp. G16–G18. O’Donnell, H.W., 1996. Steel pipeline buckling failure in HDD installations. No-Dig Eng. 3, 9–12. Ontario Provincial Standards Specification (OPSS) 450, 2002. Construction specification for installation of pipelines and utilities in soil by horizontal directional drilling. Randall, R.C., 1995. Practical guide to ISO 9000: Implementation, Registration and Beyond. Addison-Wesley Publishing Company. Sterling, R., 1999. Statement of need: utility locating technologies. Technology Transfer Information Center, National Agriculture Library, 10301 Baltimore Ave, Beltsville, MD 20705. Troch, S.J., Doyle, C.E., 1998. Break-away pulling heads for installing plastic pipe by horizontal directional drilling, Underground Trenchless Construction Conference and Trade Show, Houston, Texas, USA.
Implementing quality control in HDD projects—a North American prospective Erez N. Allouche* Department of Civil and Environmental Engineering, University of Western Ontario, London, Canada
Abstract The Horizontal Directional Drilling (HDD) industry in North America has experienced a tremendous rate of growth within the last decade. However, the development of acceptable operating standards and quality control (QC) and quality assurance (QA) procedures significantly lags behind the current utilization level of HDD. This gap is now considered to be one of the main obstacles for wider acceptance of HDD by the engineering community in North America. This paper describes various risks and quality-related problems in HDD practice. Recent efforts to promote and regulate quality project delivery in HDD projects are outlined. Thereafter, quality control and quality assurance are defined in the context of HDD. It is recommended that a universally recognized standard such as ISO 9000 be adopted as the basis for an industry-wide quality management system. Examples of how to customize selected ISO 9000 clauses to meet the directional drilling industry’s QCyQA needs are given. Additionally, a new approach for QC during HDD installation is described and its merits discussed. 䊚 2002 Elsevier Science Ltd. All rights reserved. Keywords: Horizontal directional drilling; North America; Quality control; Borehole monitoring
1. Introduction The Horizontal Directional Drilling (HDD) industry has experienced tremendous growth in recent years that has been supported by technological innovations, a strong economy, the telecommunication revolution and the need to reduce the impact of construction activities in urban areas (Carpenter, 1999). During this time, limited attention was given to the development of industry standards in terms of quality control (QC) and quality assurance (QA). Developments in these areas were primarily in response to needs of a specific segment of the industry or challenges posed by a particular project. One example involves the development of breakaway pins by the natural gas industry to protect medium density polyethylene (MDPE) pipes from excessive tensile loads during installation (Troch and Doyle, 1998). The industry at large has limited itself to inspection and testing, a lower level of quality commitment. Sample practices include pulling out a short section of pipe from the exit bore to inspect for damage (CALTRANS, 1999), pressure tests, and CCTV inspec*Tel.: q1-519-661-4197; fax: q1-519-661-3942. E-mail address: [email protected] (E.N. Allouche).
tions of municipal installations (Allouche and Ariaratnam, 1999). As the HDD market matures there has been a growing need for the implementation of higher levels of quality commitment. This demand is fueled, on the one hand, by owners seeking warranties for long-term performance and, on the other hand, by tighter profit margins and thus the need for greater efficiency. Additionally, an increase in market share in key sectors, an essential condition for future growth, is dependent to a great extent on a reduction in the perceived risk associated with HDD installations. One such sector is the municipal area, a conservative market that to date has hesitated to endorse HDD to the same extent it is utilized in the telecommunications and electrical conduits markets. In fact, several municipalities in California have declared a moratorium on HDD activities in their jurisdictions as a result of poor performance including heave in roads, damaged sidewalks and foundations, and repeated ‘hits’ of existing buried services (Ariaratnam, 2001). With nearly 7000 HDD rigs operating daily across North America the issue of avoidance of existing buried utilities is rapidly becoming a major problem. Recently, the telecommunications industry in the United States (US) has established the
0886-7798/02/$ - see front matter 䊚 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 8 8 6 - 7 7 9 8 Ž 0 2 . 0 0 0 6 2 - 7
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Fig. 1. Levels of quality commitment.
‘National Telecommunications Damage Prevention Council’ (NTDPC), an organization responsible for promoting awareness and new technologies for detection of buried pipes and conduits. Owners of buried infrastructure also have begun to prosecute HDD contractors who repeatedly damage buried lines. Quality control (QC) and quality assurance (QA) are among the best available means to minimize these hits and the liability associated with HDD work for all parties involved. The first section of this paper is devoted to an overview of quality management theory and its applications in the area of construction. Thereafter, potential risks in directional drilling installations are described and recent efforts to promote quality project delivery in the HDD industry are presented. Selected ISO 9000 clauses were customized to meet the HDD industry QCy QA requirements, as an example of a futuristic industrywide QCyQA standard. A new approach currently under development at the University of Western Ontario to enhance quality control during HDD installation is also described. The paper concludes with a discussion of current needs in the area of quality management in the HDD industry. 2. Quality management—theory and terminology Reaching an agreement on the definition of quality is no simple task. For the purpose of this paper, quality will be defined as ‘free from deficiencies and fit for use’. Quality management is a tool aimed at risk mitigation, prevention, minimization of losses through the elimination of poor practices and the optimization
of day-to-day processes and procedures. Voluntary quality systems are common practice in the manufacturing sector using a combination of internal and external audit systems. In recent years, the concept of quality control has begun to gain acceptance in the North American construction industry. There is a family of quality standards working in unison that enables an organization to develop a quality management system. Fig. 1 illustrates the levels of an organization’s quality commitments and their associated hierarchy. The discussion in this paper is limited to the three lower levels—inspection, quality control (QC) and quality assurance (QA). 2.1. Quality control Quality control involves techniques and activities aimed both at monitoring processes and eliminating causes of unsatisfactory performance. It is concerned with processes and operational techniques and aimed at achieving and sustaining the planned quality criteria, using feedback from inspection at various stages in the process to identify inefficiencies and implement corrective actions. In the construction industry, the quality of the finished work is commonly controlled by means of inspection and random sampling and testing as construction proceeds. The major drawback of this ‘inspectorial system’ of quality control is that it defines the mistakes after the event. Additionally, many defects are covered up during subsequent construction activities and consequently the quality of the finished work cannot be assessed by final
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inspection (Bubshait, 1999). This is particularly true in trenchless construction, where in most cases the installed product cannot be easily accessed for direct inspection without defeating the purpose of using a trenchless method.
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● Turnover of manpower in construction is higher than in manufacturing, which increases the cost of training and makes long-term planning difficult.
While quality control is an organization’s technical arm, quality assurance serves as a management tool. In contractual situations, quality assurance also serves to elevate the client’s or supplier’s confidence in the ability of the firm to fulfill its commitments. To practice quality assurance, an organization has to establish and maintain a quality system in its day-to-day operations. A quality system contains, among other things, a set of documented procedures for the various processes carried out by the organization. Implementing a quality assurance system does not replace the existing quality control functions nor does it result in more inspection and testing; it just ensures that the appropriate type and amount of verification is performed as scheduled. This is why a quality system is sometimes referred to as a QCyQA (quality controlyquality assurance) program. Quality assurance is oriented towards prevention of quality deficiencies by minimizing the risk of making mistakes in the first place, thereby avoiding the necessity for rework, repair or rejection. Quality assurance systems involve internal and external aspects. An internal quality system covers activities such as an internal audit whose aim it is to provide confidence to management that the intended quality is being achieved. An external quality system covers activities, such as ISO 9000 registration, aiming at inspiring confidence in external clients or permitting agencies that the product or service provided satisfies acceptable quality requirements. This confidence comes from the objective evidence that systems and controls are in place and working effectively, i.e. quality manuals, procedures, audits and reviews.
While the above arguments are valid, it is important to realize that it is the repetition within the construction processes themselves that permit quality management to work. Aspects such as administrative procedures, construction practices, format and frequency of communication, and decision-making processes form the basis for a firm’s efficient and effective operation and are independent of the actual projects themselves. The successful implementation of a formal quality management system can allow a construction firm to realize numerous benefits including: improvement in workmanship and efficiency; a decrease in wastage and rework; increased safety; reduced losses and downtime due to accidents; identification and elimination of inefficient practices; and improvement in the flow of activities and coordination of the organization. The results are not only improved profitability but also growth through an improved quality image. The establishment of confidence in the quality of productyservice delivery is of utmost importance to the trenchless industry, since in many cases a visual examination of the installed product is difficult if not impossible to achieve. A formal commitment by the contractor to deliver quality service can inspire a client’s confidence and readiness to try a new technology. A recent moratorium of HDD activities in some US municipalities and high fines handed down by various courts in compensation to utility owners for losses incurred due to inadvertent drilling that damaged existing services are initial signs of a potential confidence crisis in the safety of utilizing HDD in urban environments. An industry-wide QCyQA program can alleviate much of the anxiety some engineers and contract administrators might feel towards this construction method as well as assisting HDD contractors to demonstrate due diligence in cases where damage to existing services did occur.
2.3. QCyQA systems in construction—obstacles and benefits
3. Risks and potential quality deficiencies in HDD operations
The adoption of formal QCyQA systems, such as ISO 9000, by construction firms in North America is not as common as in other industries, such as manufacturing. This is attributed mainly to the following:
The following sections describe operational risks and potential quality deficiencies associated with HDD operations.
2.2. Quality assurance
● Each construction project is a prototype encompassing a unique location, design, site constraints and a owner–designer–contractor team. In contrast, manufacturing relies on systems of mass production wherein most parameters are relatively stable. ● It is common to separate contracts for design and construction, thereby reducing the effectiveness of a QCyQA program.
3.1. Damage to the pipe column The nature of the damage that might be inflicted on a pipe column during a HDD installation depends primarily on the pipe material. Polyethylene (PE) pipes may be subjected to an excessive tensile force during installation. That could result in permanent deformation, consequently reducing the pipe’s mechanical strength and useful service life (i.e. years prior to replacementy
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rehabilitation). In extreme cases, the PE pipe might rupture. While the latter case is easily identifiable, the former case is very difficult to detect. Other damage that a PE pipe might experience includes grazing and denting during the installation process due to sharp stones or other objects projected into the borehole. Such damage might initiate crack propagation in PE pipes and corrosion in steel products. Kinks in the pipe might be the result of failing to maintain the minimum bending radius or the presence of large obstacles along the borehole. Such kinks might result in the onset of local buckling in steel pipes (O’Donnell, 1996) and reduced ovality in PE pipes. In many cases, it is difficult to establish whether poor product qualityyselection, inadequate borehole design or poor construction practices led to the failure. 3.2. Utility avoidance Failure to avoid existing utilities presents a serious hazard and a major cause of third party damage, and subsequently is a source of much concern in North America (Ariaratnam, 2000; Norman, 1999). An inadvertent encounter of the drilling head or the reamer with high voltage electrical cables presents a danger to the drilling crew. In the case of an encounter with a pipe carrying natural gas or other highly flammable substances the public at large is put at risk. In 1993 alone there were approximately 104 000 hits or third party damage to gas pipelines across the US with total costs exceeding $86 million (Doctor, 1995). The danger is particularly severe when the damage is not detected immediately, allowing flammable materials to enter other buried networks such as sewers, and from there into adjacent homes. Sterling (1999) reported an explosion in a home that has been traced to a damaged natural gas pipeline during an HDD installation that took place sometime prior to the incident. Other secondary damage includes pressurized water mains and sanitary sewers that might wash out roads and other surface improvements (Norman, 1999). The costs associated with damaging an existing utility can be significant and include the cost of the repair itself, project downtime, secondary damage, and in some cases, the downtime cost for the utility provider. 3.3. Environmental damage The most common type of environmental damage associated with HDD is ‘frac-out’, an unintentional return of drilling fluids to the surface. The phenomenon occurs when the drilling fluid pressure in the borehole exceeds the confining pressure of the overburden. Alternatively, drilling fluids from the borehole might migrate through existing fissures in the formation. Frac-out is also possible when pilot bore drilling or back-reaming
operations are conducted at an excessive rate, not allowing sufficient time for the cuttings to be washed out of the borehole (Gelinas and Mathy, 2001). In most cases, the impact of a frac-out is reduced public satisfaction as drilling fluids tend to take the path of least resistance and surface in driveways, gardens and near utility poles. In the case of crossing a natural watercourse or an environmentally sensitive area, introducing a large volume of drilling fluids into the aquatic environment can be detrimental to the local ecosystem. In the case of man-made canals, weep-tile systems can be silted up, requiring an expensive cleanup operation. If contaminated ground is encountered, drilling fluids can become contaminated, thus exposing those on the surface to the contaminants. Finally, drilling fluids might also present hazard to traffic by making roads slippery, and in any event presents an eyesore. 3.4. Damage to surface improvements and adjacent structures Pressurization of the borehole by the drilling fluids andyor over-compaction of the borehole walls during the pilot drilling and back-reaming operations (instead of cutting the soil and removing it to the surface) can cause surface heave due to an upward deformation of the formation (Canon, 1998). Consequently, roads and driveways crack; sidewalks heave and pedestals lift. Adjacent utilities and foundations can also sustain damage due to soil deformation (Chapman and Hunter, 2001). Common causes for excessive soil deformation include insufficient burial cover; insufficient clearance; excessive pilot drilling or reaming rates; failure to use drilling fluids to suspend and wash the soil cuttings outside of the borehole; and, borehole enlargement in too large increments (i.e. utilizing too few pre-ream operations). 3.5. Non-conforming installation The term ‘non-conforming installation’ refers to failure of the installation to meet technical requirements specified in the contract. Examples of non-conforming installations include: 1. failure to complete the installation from the entry to exit points; 2. unacceptable degree of damage to the pipe column (discussed in Section 3.1); 3. failure to steer the drilling head to an exit point located within an acceptable tolerance window; and 4. failure to maintain grade and alignment of installed products within pre-specified tolerances (e.g. gravity sewers). The causes for a non-conforming installation might range from poor drilling practices to inadequate soil investigation and improper selection of pipe product.
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4. Current efforts to promote quality project delivery in HDD The horizontal directional drilling construction process makes it difficult to ensure quality project delivery. The entire construction process takes place below ground level and is not accessible for visual inspection. In addition, drilling and reaming actions commonly take place tens or hundreds of metres away from the drill rig. Identifying problems before they arise, and in some cases even after they are encountered, is difficult when one considers the concealed and remote nature of the HDD process. Furthermore, in some cases even if the problem (e.g. pipe rupture, peeling of coating) was detected during or immediately after the installation process, repair requires digging out the entire installation, extracting the pipe or abandoning the original alignment altogether. Finally, the lack of accessibility makes it difficult for an independent verification of the quality of the installation by the contract administrator. Industry associations, large users or HDD services and permitting agencies have adopted several approaches to meet the challenge of ensuring quality project delivery in HDD operations. These include construction specifications and best practice guidelines; contractors’ prequalifications; and operator certifications. The following sections provide short descriptions of these methods and the current level of their implementation. 4.1. Specification and guidelines Currently, the industry in North America is governed by generally accepted practices with no specific regulations with which to comply. General construction guidelines (Ariaratnam and Allouche, 2000; CALTRANS, 1999; OPSS, 2002) are available in the industry and may range from recommended practices to project requirements. The available specifications are mainly concerned with general construction practices. The sections devoted to quality control are very limited, primarily due to a lack of means to perform direct measurements of the quality of the installation. Manufacturers’ specifications for steel and polyethylene pipes are used to specify the maximum allowable tensile and bending stresses during installation. However, to date there is no commercially available technology in North America to directly measure the loads applied to the pipe column during the installation, and current prediction models are inconsistent and inaccurate (Baumert and Allouche, 2002a). There has been a recent movement in the US towards the certification of HDD rig operators (Allouche, 2000) in order to provide some industry consistency. At present, government agencies and a consortium of industry associations are leading the development of a national best practices guideline in the US (Hemphill, 2000).
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4.2. Pre-qualification and certification The shortcomings of the available construction specifications require owners to rely to a great extent on indirect measures for ensuring quality project delivery. Two approaches namely, pre-qualification and certification, might be adopted routinely in North America to ensure that the desired levels of experience and expertise are present in a HDD construction project. Pre-qualification is a widely utilized approach in the construction industry for contractor screening. It is typically used in conjunction with performance-based contracts or contracts that involve specialized construction methods, both attributes of HDD projects. Pre-qualification is a process whereby a contractor must meet certain administrative, experience andyor technical requirements to be able to submit a bid. Key elements for pre-qualification include experience in similar projects as well as having the technical expertise and financial capacity to execute the project. Specific pre-qualification requirements might include an implemented safety program, an outline of construction sequence, equipment capacity, the experience of the company and the crew, a drilling fluids management plan as well as proof of an adequate line of credit. Certification of the HDD operator is another way of trying to ensure quality installations. The rig operator is required to have completed formal training and to have passed a test that demonstrates a minimum level of knowledge with respect to issues such as preparation of a drill path profile; setup of the drilling rig and support equipment; and drilling fluids. The candidate must also be proficient in construction practices including drilling a pilot bore, tracking and installation of the pipe product as well as the proper response to various emergency situations. HDD certification programs are currently being offered primarily by the North American Society for Trenchless Technology (NASTT), in collaboration with local agencies (e.g. California Department of transportation). Several educational institutes, such as Missouri Western State College, also offer training and operating programs on an intermittent basis. Operator certification programs are recognized by many owners and contractors across the continent, however they are rarely required as part of the pre-qualification process. The certification and pre-qualification systems in the HDD industry in North America are ‘single level’, and are not limited by type of machinery, pipe diameter, nature of installation or length of installation. 5. QCyQA in the HDD industry As discussed in Section 2.3, individual firms and the trenchless industry as a whole can reap many benefits from the adoption of a formal QCyQA program, a management tool aimed at optimizing day-to-day oper-
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ations and procedures to minimize or eliminate poor project outcomes. The following sections describe various practices that can be adopted by HDD contractors to increase the level of quality control prior to and during the construction process. It is proposed to implement these measures via the framework of ISO 9000, a generic series of quality management and assurance standards accepted around the world. Thereafter, a new approach for implementing quality control during HDD installations is presented and its merits discussed. 5.1. ISO 9000 In 1987 the International Organization for Standardization (ISO) published ISO 9000, a single generic series of quality management and assurance standards. Due to its generic nature the 9000 series is an excellent foundation for developing specific and comprehensive quality systems tailored to particular industries. Over the past 15 years, ISO 9000 has been adopted by a large number of industries around the world and is currently recognized as the world’s leading quality systems standard. ISO requires that a company establish, document and maintain a quality system. It outlines definitions and document requirements as to how quality standards will be met, and mandates the documentation of all ISO procedures in a quality manual. The following discussion was organized to follow selected clauses in the ISO 9000 that were customized to reflect the nature and realities of the HDD construction process. For the development of a unified QCyQA for the industry, or for selected organizations, it is recommended that the relevancy of all twenty clauses supported by ISO 9000 be examined. More information regarding ISO 9000 can be found in Randall (1995). 5.2. Management responsibilities ISO philosophy is that good communication among all levels and a clear description of everyone’s responsibilities are basic requirements for a company success. A document expressing the responsibilities, authority and interrelation of each individual who may manage, perform and verify work affecting quality is a necessary step in the development and management of a system. It allows easier identification of resource requirements and the ability to adequately provide for them. Defining the duties and responsibilities of each individual promotes communication and cooperation among the various levels. 5.3. Contract review The ISO standard requires that the organization has documented procedures for contract review and for coordination of activities. Before acceptance of the
contract, the organization must review it to ensure that: (1) all requirements are adequately defined; (2) all verbal requirements are documented; and (3) the organization is capable of assuming all of the risks stated or implied in the contract. The contract review procedure is a checklist that ensures the contract provides sufficient protection to the contractor for foreseen and unforeseen risks. For example, the contract should address issues such as: compensation for incompleteyabandoned installation; compensation for multiple attempts; costs and liabilities associated with inadvertent returns and fracouts; adverse subsurface conditions; and circumstances under which the installation will be abandoned. 5.4. Design control The main objective of design quality control is to reduce design errors and costly changes during the construction process. Unlike most other segments in the construction industry, the involvement of consultant engineering firms in HDD projects in North America is limited. Many contractors prepare their own designs, especially in the case of short-to-medium length crossings. A HDD contractor should develop a guideline for the preparation of design and planning documents for every crossing. Key elements in the design guideline should be: ● Plan view—showing equipment footprint; entry and exit points; alignment; layout of string pipe; and significant surface features (e.g. roadways). ● Elevation view—showing the location and elevation of all known utilities and other buried obstacles; nature of the various utilities and clearance from the proposed installation. ● Construction sequence—size of pilot bore and prereaming operations; proposed borehole tools. ● Risk assessment—covering anticipated soil conditions (i.e. gravel, swelling soils); potential sources of electromagnetic interference; sensitive environmental areas; clearance from known utilities; transportation corridors; and potential areas where a frac-out may occur. ● Proposed mixture of drilling fluid (bentonites; polymers or a mixture of both); target marsh funnel viscosity for raw drilling fluids; additives and their proposed quantities per unit volume or weight. The plan will be prepared by the crew supervisor and will be submitted for review and approval by the next level in the organization’s hierarchy (e.g. project coordinator). The extent of documentation and the level of details will be a function of the project size and complexity, and should be aimed at meeting regulatory and client requirements. Proper planning is invaluable during both mobilization and construction, while proper
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design documents can be used to establish the firm’s due diligence in the case of damage to a third party. 5.5. Process control A detailed procedure for every routine activity performed during the mobilization, construction and demobilization phases should be developed and documented. These procedures will represent ‘best-practices’ and will be used for training as well as for the development of checklists to be used on the job site. Such ‘best practices’ may range from the proper way to anchor the rig to specifying the maximum recommended penetration and pullback rates for various formations and borehole diameters. Additionally, special procedures should be developed for emergency situations such as inadvertent drilling into a buried utility or a frac-out into a surface body of water. Quality control requires the development of such procedures; quality assurance ensures that they are followed as part of the organization’s daily routine. The combination of both is a powerful tool when it comes to demonstrating an organization’s due diligence in a court of law. 5.6. Monitoring, inspection and testing The main objective of the contractor inspection and testing program is to provide objective evidence that proper practices and materials are used during every phase of the project. The inspection and testing procedures specify quantatively and qualitatively acceptable criteria for construction workmanship and materials. In the context of HDD, inspection and testing measures can be classified into three categories A. Prior to commencement of drilling operations ● Testing of the fabricated pipeline product (e.g. Xray tests; pressure testing). B. During drilling operations ● Testing the compatibility of drilling fluids with the in-situ soils (e.g. marsh funnel viscosity test). ● Excavation of small observation shafts along the installation path to visually inspect the condition of the pipe as it is pulled through the borehole and verify that the back-reamer clear crossing utilities. ● The placement of weak-links, or breakaway swivels, between the pull-head and the reamer to prevent excessive pulling forces from being applied to the pipeline product. ● Pulling a test section (‘pig’) through the borehole prior to product installation to confirm that the borehole is clear of obstacles. ● Placing an electronic transmitter between the reamer and the pull-head to track the path of the pullback operation.
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● Monitoring the drill rig’s hydraulic gauges as a rough indication of the thrust and torque transmitted to the drill string. C. After drilling operations ● Pulling a section of the pipe equal to 1% of the total installation length or 2 m, whichever is less, out of the exit hole to inspect for damage (e.g. scours, dents). ● Running an electronic transmitter through the installed pipe to verify its location. ● A flow test and a CCTV inspection of the pipe interior to confirm that there are no sags in gravitydriven sewer lines installed using HDD. ● Pulling a short conical tube of a diameter somewhat smaller than that of the pipe’s internal diameter (i.e. a mandrel) to verify that the pipe is free from an unacceptable degree of ovality. 5.7. Document and data control Clear procedures must be established detailing the types of data to be collected, who should collect it and who should receive it. The term ‘data’ refers to accounting information, maintenance records; safety documents; internal audits; site reports; procurement records, etc. Proper data flow and handling procedures ensure that the correct information reaches those individuals who can act upon it in a timely manner. 5.8. Training ISO 9000 calls for establishing the experience and skill requirements for every position in the organization. A gap-analysis is then performed to identify any shortfalls and corrective actions required to close this gap by providing appropriate training. Examples of such training are operator certification courses, safety courses, project administration courses and butt-fusion tickets. 6. New approach to quality control in HDD Section 5 covers various clauses of ISO 9000 applicable to HDD contractors and their projects. This section describes a new tool that can significantly contribute to a high degree of quality control during horizontal drilling installations. One of the most costly problems that HDD contractors can face is non-conformity of the installed product, due to either: (1) failure to maintain the pipe product within the specified alignment and profile tolerances; or (2) pipe damage. The latter can take various forms including buckling due to excess bending forces; compromise of the product’s wall thickness due to deep cuts; peeling of the exterior protective coating; localized deformation of the product’s cross-section; and rupture of the pipe product. These problems are discovered only after the problem has occurred. At this point it is often
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Fig. 2. Prototype smart load cell with radio transmitting capabilities placed between pull-head and reamer.
too late to initiate a corrective action and the only recourse is to remove the product andyor install a new product. Another potential damage during an HDD installation includes permanent deformation of the pipe due to excessive tensile force that may hinder the pipe’s structural strength and reduce its useful life. However, unlike previously mentioned non-conformities, this problem is difficult to identify during the construction process or immediately after it. To mitigate this problem some owners require the utilization of weak-links or breakaway swivels to prevent the application of an excessive tensile force onto the pipeline product. However, such practices result in ‘jamming’ the pipeline product in the borehole and subsequently a costly recovery of the pipe and re-installation. The contractor may lose not only the time spent on the failed installation and recovery of the product, but also the time spent on drilling the pilot bore if this cannot be re-used. The owner, on the other hand, may lose the pipeline product due to damage inflicted during the recovery operation or failure of such an operation. This approach may also penalize the contractor unnecessarily, as the application of high pulling forces may be the result of adverse soil conditions such as cobble or swelling clays. The con-
tractor may also be penalized for the specification of an undersized product by the owner’s representative. Additionally, it is unlikely that a thermoplastic pipe will suffer permanent damage from a single incident in which the specified load capacity was exceeded by a few percentage points over 20 or 30 s. However, under such conditions the weak-link will fail. Finally, the machine operator can learn little from the incident with respect to avoiding such failures in the future. In fact, many contractors view weak-links as an unnecessary risk in an already risky business and as a practice of questionable fairness. Subsequently, there is increased likelihood of fraud andyor an adverse relationship between the contractor and the owner. The smart load cell presents an approach that provides increasing quality control to the contractor and quality assurance to the client while avoiding most of the disadvantages associated with weak-links. The load cell is placed between the pull-head and the back-reamer, as shown in Fig. 2. The device is instrumented to measure the tensile force transferred from the reamer to the pullhead with an accuracy of "1%. The maximum capacities of the prototypes fabricated to date range between 50 and 245 kN (Baumert and Allouche, 2002b). Within
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Fig. 3. Sample data from a smart load cell.
the load cell there is an electronic system that converts the strain measurements to loads, and records them as a function of time. When the installation has been completed the data can be downloaded into a laptop computer and presented using Excel or other commercially available spreadsheet software. Alternatively, the load cell data can be transmitted during the installation in real-time via a radio transmitter to a display unit at the drilling rig. Based on the manufacturer’s maximum allowable loads, the installations can be categorized as either: ● Acceptable—allowable stresses were not exceeded during the installation. ● Fair—a few minor violations of maximum allowable stresses. ● Poor—multiple minor-to-moderate violations of maximum allowable stresses. ● Unacceptable—gross violation of maximum allowable stresses. Additional research is needed to establish acceptable criteria for ‘Fair’, ‘Poor’ and Unacceptable’ ratings. Based on the rating and specific site conditions, the installation will be declared to be: (1) acceptable; (2) acceptable but the contractor will be subject to a financial penalty due to poor performance; (3) unacceptable. The proposed system will enable expert judgment based on objective data rather than an instantaneous maximum loading condition to determine the fate of the installation. Contractors will realize substantial savings due to a reduction in the amount of rework, while owners will benefit from a high quality QCyQA system that is resistant to fraud or tampering. Additionally, the proposed system is not only fair, but it also provides excellent feedback to the operator regarding the impact of hisyher practices on the load applied to the pipe (Fig. 3). Based on this feedback, operators will be able to continuously improve their skills and understanding of the interaction between subsurface
conditions, borehole geometry, drilling fluid compositions and the force required to pull the product through the borehole. 7. Discussion and conclusions The successful implementation of a quality system can greatly benefit an organization in terms of improved profitability and growth via increased efficiency and improved quality image. The relatively low number of HDD firms in North America that have an official quality management program is due not only to the common obstacles facing most construction firms discussed above, but also to the special characteristics of the industry including: ● The concealed and remote nature of the HDD process makes it difficult to identify problems before they arise and in some cases even after they are encountered. Even if a problem was identified during the construction process, the corrective actions that are available are limited. ● Lack of means to perform direct measurements of the quality of the installation process. ● Lack of established standards and acceptable practices in North America-design specifications are scarce and construction specifications are still in their infancy. ● Fragmentation—the North American industry is comprised primarily of relatively small dedicated contractors, making it difficult to allocate the financial means needed to establish a formal QCyQA program. Nevertheless, there is growing recognition of the need to develop and implement a voluntary unified QCyQA standard in order to reduce the risks associated with the utilization of the HDD method, and subsequently to ease its acceptance by the engineering community. It is suggested that this QCyQA standard be based on an established and proven generic framework such as ISO 9000.
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A key obstacle is the difficulty in obtaining direct objective feedback as to the contribution, or lack thereof, of various practices to the quality of the installation. Recent efforts for developing means and measures that promote project quality delivery prior to, during and following an HDD installation were described in this paper. The most notable of these is the development of weak-links to protect PE pipes from damage due to excessive tensile force. However, in doing so, the construction process is being terminated, resulting in costly remediation measures to the contractor and potentially to the owner. Additionally, many contractors question the fairness of this approach as it may punish them not only for poor construction practices but also for adverse subsurface conditions and undersized products. An alternative approach to control tensile forces during HDD installations is the utilization of smart load cells. These devices measure and record the installation loads during the construction process. Based on these records and an assessment of the local subsurface conditions, the installation can be accepted or rejected by the owner. The data collected are also an invaluable asset for the training of drill operators. References Allouche, E.N., 2000. Prequalification and certification of HDD contractors. No-Dig Eng., USA 7, 11–14. Allouche, E.N., Ariaratnam, S.T., 1999. Municipal applications of horizontal directional drilling: construction considerations and Canadian case studies. Proceedings, INFRA ‘99 International Convention, Montreal, Nov. 22–24, Session 6B, 18 p. Ariaratnam, S.T., 2001. Overview—Horizontal Directional Drilling Training and Certification. North American Society for Trenchless Technology Workshop, May 16, Markham, ON, Canada. Ariaratnam, S.T., 2000. Avoiding the hazards of directional drilling. Utility Safety Mag. 3, 19–21. Ariaratnam, S.T., Allouche, E.N., 2000. Suggested practices for installations using horizontal directional drilling. Practice Periodical on Structural Design and Construction, ASCE, Vol. 5, No. 4, November, pp. 142–149.
Bubshait, A.A., 1999. ISO 9000 quality standards in construction. J. Manage. Eng., ASCE 15, 41–46. Baumert, M.E., Allouche, E.N., 2002a. Methods for estimating pipe pullback loads for HDD crossings. J. Infrastruct. Syst., ASCE 8, 12–19. Baumert, M., Allouche, E.N., 2002b. Real-time monitoring of HDD installations. Underground Construction Technology Conference, January 15–17, Huston, Texas, Track IX-A, 17 p. CALTRANS, 1999. Guidelines and Specifications for Horizontal Directional Drilling Installations. Headquarters Office of Encroachment Permits, July, 26 p. Canon, F., 1998. Fluid volumes—how much is enough. Directional Drilling 4, 47. Carpenter, R., 1999. A comprehensive HDD survey details industry growth trends. Underground Construct. 54, 36–37. Chapman, D.N., Hunter, A.E., 2001. Developing safe proximity charts for impact moling and horizontal directional drilling operations. Proceedings of The International Conference on Underground Infrastructure Research, Kitchener, Ontario, June 11–13, pp. 239– 245. Doctor, R.H., 1995. Third party damage prevention systems. Final report for the Gas Research Institute, Contract 5094-810-2870, by Nicor Technologies, Naperville, IL. Gelinas, M.M., Mathy, D.C., 2001. Horizontal directional drilling: lessons learned in conduit installation. Proceedings of The International Conference on Underground Infrastructure Research, Kitchener, Ontario, June 11–13, pp. 247–256. Hemphill, J., 2000. Cooperative efforts solidifies HDD future. Directional Drilling Mag. Oct., pp. 21–23. Norman, R.S., 1999. Obstacle Detection for Guided Directional Drilling for Gas distribution Applications. Trenchless Technology Mag., June, pp. G16–G18. O’Donnell, H.W., 1996. Steel pipeline buckling failure in HDD installations. No-Dig Eng. 3, 9–12. Ontario Provincial Standards Specification (OPSS) 450, 2002. Construction specification for installation of pipelines and utilities in soil by horizontal directional drilling. Randall, R.C., 1995. Practical guide to ISO 9000: Implementation, Registration and Beyond. Addison-Wesley Publishing Company. Sterling, R., 1999. Statement of need: utility locating technologies. Technology Transfer Information Center, National Agriculture Library, 10301 Baltimore Ave, Beltsville, MD 20705. Troch, S.J., Doyle, C.E., 1998. Break-away pulling heads for installing plastic pipe by horizontal directional drilling, Underground Trenchless Construction Conference and Trade Show, Houston, Texas, USA.