Directional Drilling Job Safety

Safety is indispensable in all walks of life, especially in the workplace. Though Horizontal Directional Drilling jobs are of various kinds, occupational safety must be prioritized and given due emphasis. In essence, the safety precautions of HDD are along the same lines as construction. Safety commences at the top level in an organization and flows top-down, with the senior management leading by example.

Safety culture is an absolute prerequisite and is by no means inevitable. Only well-regulated and carefully planned out efforts fabricated by trained human resources can make construction a lucrative medium while not jeopardizing safety. For a workplace safety program to be efficacious and productive, it is imperative for all personnel to be bound by it and religiously follow it to the dot. Whatever be the operation at hand, it is vital for the employees to refer to and diligently follow the Manufacturer's Operator's Procedure Manual, a handbook that primarily details and provides exhaustive information on specific HDD equipment. This section exhibits and outlines the general job-site safety procedures that must be mandatorily be embraced and followed throughout the working lives of employees and is in compliance with the recommendations made by the Association of Equipment Manufacturers (AEM, 2000) and the Directional Crossing Contractors Association (000A, 2000)

HDD Safety Plan and Checklist

Every company should possess a safety manual to ensure occupational safety for all its employees. It must encompass the following:

• Standard maintenance and operational procedures, complying with applicable regulations;
• Emergency protocol for utility strikes;
• Contingency procedures for other hazardous activities;
• Comprehensive emergency evacuation or exit plan;
• Corporate training program;
• Records of workplace incidents, accidents, and training.

It is essential to create a safe working environment for all those working in an organization, establish coherent safety and communication procedures, and make all employees aware of the security log. For stable operation, it is pivotal for all business undertakings to keep on hand the emergency response plan, courses of action, and measures to be adopted to address predicaments and deal with crises. When devising a safety policy, attention must be promptly drawn to a checklist of issues as outlined below:

• Safety starts at the top;
• Determine the hierarchy of authority, i.e., the different levels of command within the organization;
• The basic tenets of corporate safety should be well-articulated and consistent and safe work procedures must be formulated;
• Active participation by all salaried and hourly employees;
• State the Personal Protective Equipment Policy that protects employees from worksite hazards;
• If there is reasonable cause to believe that work involved is unsafe, employees have the prerogative to refuse such work;
• Every construction site should compulsorily have a “Competent Person” and personnel trained in first-aid;
• All commercial vehicles and worksites must be well-equipped with first aid equipment and fire extinguishers at an identified location;
• Admittance to local emergency facilities and provision of location details with employees;
• Communication freedom should be promoted, and employees must be made aware of the points of contact;
• During employee orientation, the personnel must be made familiar with all the aspects of workplace safety detailed above and comply with the relevant safety regulations and protocols.

However, when designing safety regulations for certain types of activities, there are a list of topics that should be dealt with and tackled as depicted hereunder:

• The specific activity must be detected and delineated;
• Recognize potential pitfalls and hazards;
• Conceive a step-wise procedure in writing to execute the activity;
• The identified threats must be singled-out, controlled, or completely phased out with the help of the safety procedures;
• Constant risk surveillance to see changes in risk and the effect it has on other factors in the worksite;
• The procedures must be assessed and modified in the event of an incident or accident occurring;
• New and inexperienced employees must be carefully monitored.

A “Competent Person” is an employee who has the knowledge and ability to recognize and alleviate hazards and is entrusted with the responsibility of addressing issues. However, at the beginning of each shift, the topics depicted below should be evaluated and assessed in the presence of all employees:

• Specific hazards and procedures must be addressed;
• Decide upon the location of emergency facilities;
• Review the contingency procedures and emergency evacuation strategy in case of unforeseen disaster or accident;
• Brief all personnel, subcontractors, and visitors as they arrive on-site;
• Keep track of all discussions and participants present during the talks.

The safety concerns and issues vary from site to site. Since these issues are distinctive, it is paramount to bring to light the site-specific hazards, converse appropriate safety procedures to be adopted in case of any potential risk, and convey the emergency procedures to the crew.

Responsible Personnel

The Competent Person is the person authorized by the company to oversee and govern the entire project. This company-designated individual has the ability to identify existing and potential hazards, take corrective measures to rectify hazards and assign duties to fairly proficient personnel. Prior to the initiation of operations, as well as during the course of the project, the entire workforce should be notified and briefed about the safety guidelines and the precautionary steps to be undertaken in case of any unexpected circumstance. This individual is also liable to ensure that all personnel have familiarized themselves and are in line with the widely recognized construction safety practices and suitable job procedures. The company may assign a drill operator, drill locator, or another on-site supervisory person to assume the position of the competent person.

Operators of drilling, locating, and support equipment must be deemed qualified to perform their operations by the Competent Person or supervised by a skilled operator.

Post arrival, all support staff should be notified and briefed by the Competent Person. While engaged in their occupational activity, they should mandatorily comply with all safety procedures. The support personnel and visitors must be informed of activity restrictions along with the hazards related to their job.

Communication plays a key role in all the facets of a business. Likewise, effective communication also contributes to the success of a horizontal directional drilling project. Drill operators must be in constant touch with the drill locator as well as the product side personnel to efficiently manage the drilling operation. Before commencing their work, they should both have extensive knowledge and a comprehensive understanding of the job at hand. They are liable to analyze the bore path, check for signs of reinforced concrete, gauge any potential fields of electromagnetic (active) disturbance or passive interference that may obstruct operations with the help of locating equipment like DigiTrak and Ditch Witch to evaluate the identified hazards.

It is necessary to have two-way radios in long bores. Similarly, there should also be spare batteries and backup radios on hand that are readily accessible. Though "exit side control devices" cannot replace the reliable voice communication between the machine operator and exit side personnel, they are also commonly used in drilling sites. The remote lockout is one such device that may be utilized to help deactivate the drill string for safety reasons from a distance. Once disabled, the drill string movement will not resume operations until a run condition is enabled and the machine operator recommences the drill string operation. Additionally, confirming that there is enough signal range to cover the entire job site is highly significant.

Risk assessment is a process conducted to detect, evaluate, and control hazards and risks within the workspace. Performing a hazard analysis before initiating any boring activity or excavation is integral. The next phase involves establishing procedures to eliminate, isolate or otherwise control the identified hazards. Pertaining to general safety practices for activities, drilling operations, just as construction operations, must conform to the requirements of OSHA, State, and Local Regulations. The general safety regulations and guidelines are designed to meet the needs of activities such as:

• Motor-Vehicle operation
• Mobile (Heavy) Equipment operation
• Noise
• Traffic control
• Verification of underground utilities
• Workplace safety and isolation of hazards
• Manual lifting
• Trenching and Excavating - Shoring and Sloping
• Confined-space entry
• Hand tools
• Power tools
• Fall protection
• Material handling

Supplementary to the activities mentioned above, some of the hazardous activities geared specifically towards HDD that must be duly reflected are:

• Drill rig operation
• Pilot bore tracking
• Underground utility clearances
• Protection from striking electrical lines
• Rotating drill pipe
• Drilling fluid system operation
• Working on the product side
• Workplace communication
• Handling loose drill pipe
• Making/breaking toot joints/tool changes

Underground hazards to take into account include:

• Electrical power cables can, as a result of being faulty, short circuit or overload cause severe injury or electrocution.
• Fluid and gas pipes, transporting asphyxiating, toxic, flammable, and/or explosive gases or liquids.
• Low-pressure sewage and stormwater lines. The HDD gas or electric lines should stay clear of sewage lines. However, in the event where unknowingly, the HDD gas or electric lines have been installed through existing sewage lines, this could be problematic and constitute a potential threat, especially during subsequent maintenance or repair work, leading to a gas leak, electrocution, and maybe even an explosion.

It is an absolute precondition to carefully weigh the workplace surface for signs of potential underground hazards.

• Transformer boxes should be thoroughly inspected by skilled utility technicians to ascertain the number and orientation of lines entering the box. The ground grids should also be examined.
• Manholes, which are access points to underground utility services within drill areas, should, without entering, be opened up, and a routine inspection should be carried out solely by authorized personnel. Before determining where the borewell should be built and reducing complexities relating to it, technicians should examine the flow direction in a sewer to measure the approximate grade, which helps determine the depth of the existing underground utility.
• Wires attached to poles should always be assumed to be live.
• Water and gas shutoff depths should be confirmed to provide initial confirmation of the depth of the pipe. A minimum of 150 to 200mm (6" to 8") should be added to depths for valves going to house services. Additional clearance may be required for large valves. This information can be used to facilitate potholing and is not by itself a safe method of verifying the depth or location of the utility before construction.
• Outbuildings (i.e., storage sheds) should be examined to make an assessment, track down, or confirm if, unlike what is indicated on the plan, there are any additional electrical wires or other utility services underground.
• Gas barbeque grills, outdoor lighting, etc., should be identified and services confirmed.
• Ditch line depressions in the landscape or obvious vegetation changes should be addressed to uncover previous excavation.
• Road repairs could draw to the fact that there was a recent installation or repaired utilities in the drill area.
• Pipeline marker signages or casing vents alert the presence of hazardous pipeline facilities at or near property lines.
• One Call operators do not mark private utilities and utilities that are not subscribed to the One-Call system. The contractor should investigate and go through Contract Documents and check State and local regulations to determine who is responsible for verifying locations of unmarked utilities, ascertain what all underground utilities are present, and prevent accidental damage to them.

Overhead power transmission lines are lethal if not properly grounded. Always stay clear and maintain a safe distance of at least 6m (20 ft) between the equipment and power lines. OSHA has outlined regulations regarding the required minimum separation if the voltage is known. It cannot be stressed and emphasized enough the precautions to be adopted when operating booms on vacuum trucks and cranes, handling drill pipe, loading and unloading heavy equipment, and operating other lifting devices for adding pipes or pipe boxes to drill units. For this purpose, it would be wise to have a signal person present to assist equipment operators in maintaining a minimum clearance distance between their heavy equipment and the power lines, as well as clearly displayed marker signages on either side of the overhead hazard.

Verify Utility Locates

Prior to excavation, it is crucial to validate and establish the location of all identified utilities by employing non-destructive digging techniques of excavation such as vacuum excavators. The Association of Equipment Manufacturers (AEM, 2005) has defined the safety procedures to be complied with by operators while handling such heavy excavators. When bore profiles are designed, due attention must be paid to maintain an acceptable clearance between the underground structures and the final reamed hole. Similarly, when establishing clearances, extra caution must be practiced during the possible migration of the back reamer, which occurs as a result of excessive steering or a tight radius from the pilot bore toward the utility. Nevertheless, in case of high demand for new utilities, it may become necessary to increase the easement widths, as they become increasingly congested.

In case of any anticipated risk element attached to the utility during the drilling phase, specialists, for the purpose of keeping a close watch and observing any unstable situations, digs and unearths a 'window' at or near the utility. However, if the situation is such that the bore is in very close proximity to the utility, even after the drill head or reamer passes the 'window,' continuous surveillance would still be done to oversee the separation as well as to see if the drill string or product pipe may during the completion of the installation be in contact with the utility. A vacuum unit is utilized to extract the drilling fluid during this process, and issues relating to high-pressure drilling fluid hazards would also be assessed.

In the course of the actual boring process, engineers will, with the help of a tracking device, check the readings frequently, document them, and compare them with the pre-operational readings. Supposing any abnormalities are viewed, under all circumstances, the HDD machine operator is required to put a stop to it immediately, back up, verify previous readings, investigate, and take appropriate safety precautions before once again proceeding with drilling the bore. It is pivotal to make a comparison between the present drilling status and the approved planned bore profile to ascertain if there exist any deviations as this can be an expensive and dangerous affair and can lead to an underground utility strike. Hence, special care should be taken during product installation and the possible straightening of the bore. Comparatively, once the bore has been drilled, the back reamers used in HDD operations to enlarge pilot bores should be drawn back with extra caution through the hole to prevent the utilities from getting perforated in the process. 

Traffic Control (Pedestrian and Vehicle)

Traffic control is one of the significant prerequisites in any worksite and must be retained throughout the project. It involves developing plans, drawing permits, giving notifications, designating traffic controllers or guards, and employing devices such as warning signs and barricades to reroute traffic, prevent workers, pedestrians, and vehicles from getting hurt, and protect them from potential hazards caused by vehicular traffic on the drilling sites. Traffic control ensures road safety and is urgently required during mobilization, loading, and unloading of materials, intermittent movement of mobile equipment, and demobilization. To avoid accidents in the work area, specifically, the entrance/exit pits and areas around the drill rig must be secured and accessed only by approved personnel. Nonetheless, emergency vehicles and buses must be given authorized entry even during construction.

Safe Practices and Safety Equipment

Strictly and thoroughly following safe practices and procedures ensures the safe use of equipment and processes, helps prevent injuries, and assesses unsafe situations. The four stages in evaluating hazards in the HDD worksites include recognition, isolation, control, and hazard elimination. The protective gear required on HDD job-sites are similar to the personal protective equipment on other construction job-sites, and they include:

• Approved hard hats, meeting OSHA specifications for head protection;

• Safety glasses, goggles, or face shields that comply with OSHA standards to protect eyes and face;

• Hearing protectors such as earplugs and earmuffs;
• Highly visible reflective apparel;

• All other safety equipment mandated by other rules or required by the Owner or regulatory agency;

• Dielectric footwear and gloves to prevent electrocution during high voltage while drilling/reaming;
• Effective communication devices;
• Remote breakout wrenches for working on the drill string;
• Quick connect/disconnect devices.

In the case where the drilling unit has been furnished with an Electrical Strike Sensing System, it should be used in accordance with the manufacturer's recommendations. The system may include audible and visual warning alarms, grounding mats, and personal protective equipment that protects workers exposed to all types of risks. Prior to drilling within the worksite, the strike alert system must be appropriately set up and tested, and the electrical sensing stakes must be inserted into the ground.

Drilling Precautions

Various preventive measures should be observed during the drilling activities as listed below:

• In case of any foreseen hazardous impediments during the drilling process, steps should be taken to discontinue operations immediately until the hazard is eliminated.

• Identify all potential "pinch points" on the drill rig and support equipment and avoid them to prevent hand injury.
• There must exist a safe and adequate clearance or spacing between the bore and all utilities of at least 3 ft or as specified by regulatory authorities. The final reamed diameter and the bend radius of the pilot bore should be considered when maintaining the minimum clearance.
• It is highly advocated that the utility be exposed at intervals of no more than 100 ft in the event where there occurs paralleling within 5 ft of an existing utility. This is done to confirm that sufficient separation is maintained throughout the pilot bore. Prolonged exposure may be necessary for safety-critical utilities such as high-pressure natural gas lines (NTSB, 1999).

• Extra caution should be exercised around pressurized drilling fluid.
• All workers must evade the rotating drill string.
• When the workforce performs on or near the drill string, the drill must not, in any case, be operated.
• In the absence of effective communication between the drill locator or exit side personnel, the drill should not under no circumstance be operated.
• The maximum torque and thrust/pullback capacity recommended by the drill pipe manufacturer must not be surpassed.
• Remote breakout wrenches must be used with utmost care. When hand wrenches are employed, it is crucial never to use drilling machine torque or an auxiliary machine such as a backhoe to gain leverage on a hand wrench to make or break remote tool joints.

Reaming and Installation Precautions

The checklist of safety precautions to be undertaken during the reaming and product installation process encompass the following:

• In the situation where the excavation crosses existing underground utilities, the utility must be exposed at the point of crossing, and this confirmed location has to be supervised during the crossing.
• There must always be two-way radio communication observed between the entry and exit sides. Additionally, utilizing an exit side control device assures that the drill string will be run into the bore only after the exit side technicians have achieved a safe separation distance.
• For the purpose of ensuring the safety of all workers, the drill pipe should be rotated only after all the personnel has been notified and acknowledgment has been received from their side.
• Prior to rotation, the reamer should be drawn out of the borehole to help prevent it from moving sideways when rotated.
• Personnel must be positioned at least 3 ft away from rotating drill pipes, and they should never step over the rotating drill.
• When hoisting the directional drilling assemblies out of the hole and positioning reamers to the drill string, appropriate lifting slings and equipment must be utilized.

Response to Events

If there ever occurs a situation wherein the existing utility gets hit during the drilling process, contingency measures must be set up to reduce the likelihood of human injury. Under these circumstances, based on the utility type, the sub-sections portrayed and summarized below should be pursued as laid down by The Association of Equipment Manufacturers (AEM, 2000).

Electrical Strike

If an electrical strike occurs, workers should stay where they are, not move, and not touch the equipment or anything connected to the drill as these items may be highly charged. The step potential between the equipment and the ground, or even between a person's feet, would be enough to cause bodily harm or lead to fatality. The electrical utility company must be contacted immediately and informed of the situation. The drill operator must stay composed and try to break contact with the electrical line by moving the drill clear of the wires. The operator should wait for confirmation from the utility company that the mains have been switched off and then follow the manufacturer's procedure to determine if the drill is electrically charged before attempting to dismount the drill.

Gas Strike

While drilling, if the operators accidentally hit a gas line, the area must be instantaneously evacuated, and drilling must cease. Since gas is highly flammable, a crack in the gas line can lead to fire and explosion. Emergency services and the gas utility company should be notified immediately. The drill operator should shut down all engines, and under no circumstance should they, unlike in the case of an electrical strike, attempt to reverse the bore to break contact as the slightest of movement may ignite a spark and cause an explosion.

Fiber Optic Strike

If the drilling equipment unknowingly strikes a fiber-optic cable, workers must not look directly at the cut ends, as it can result in severe eye injury. Drilling must stop immediately, and the damage should be brought to the attention of the fiber company.

Communications Line Strike

If a communications line strike occurs, drilling must come to a stop immediately, and the utility company should be approached.

Sanitary/Storm Sewer and Water Strike

In case a water or sewer line has been struck, drilling should be just as in the case all other strikes be paused, all bystanders should be warned of the same, and should be asked to keep a safe distance. Immediate medical assistance must be provided to the individuals who have come into contact with sewage. Similarly, the utility owner should be contacted immediately.

Cross-Bore Issues

Unmarked non-metallic sewer service laterals are a severe concern facing the HDD industry (Griffin, 2007). When laying new gas pipelines or electrical lines, there is always a possibility of the contractors unintentionally puncturing an unmarked lateral. This type of pipeline damage is referred to as "cross-bore".

The problem usually starts a couple of years later, when it is time to clean and unclog the sewer lateral, and the homeowner is in need of professional help to resolve the problem. Generally, this process involves using a mechanical drain cleaning device, which removes all debris and cuts through roots to clear the sewer. The device may pierce a gas line cross-bored through the sewer lateral if not careful, and this can lead to gas leaks, thereby resulting in potential explosions and disastrous fatal accidents.

Likewise, a cross-bore involving an electrical line is also hazardous, and in this situation, the professional operating the mechanical drain cleaning device is in grave danger of getting electrocuted.

The HDD industry is working arduously and has made significant progress in alleviating the cross-bore predicament. They have adopted a combination of various measures, including creating awareness among the public and educating them, improved legislation ensuring pipeline safety during the drilling process, and promoting cooperation between all stakeholders. It is now mandatory in several states for all newly installed non-metallic sewer service laterals to have a tracer wire or electronic marker device, which aids workers in uncovering the underground utilities effortlessly from the surface itself and avoid perforating the existing utility lines while drilling using handheld locating devices.

Conclusion

Horizontal Directional Drilling operations involve high-risk factors that can potentially be risky to both the personnel carrying out the operations and the environment, leading to serious injuries, blowouts, and eventually, explosions. During the entire drilling process, extreme caution must be practiced by the entire workforce, right from start to finish. Hazards specific to HDD include the rotating drill string, making up and breaking out of tool joints, and unknown utility strike potential. However, the most common incidents and accidents on an HDD site are identical to those found on a construction site, such as slips, trips, falls, excavation cave-ins, pinched fingers and toes, vehicle accidents, and back injuries, to name a few. For the purpose of avoiding incidents and accidents, it is paramount to pinpoint the common hazards and hazards specific to HDD equipment and operations and isolate or remove them. The personnel must adhere to the safety protocol throughout the entire project to reduce the likelihood of incidents or accidents. Creating awareness in the workforce and educating them on the various guidelines is extremely important. The investment of time and money involved in training or hiring an experienced crew is minimal when compared to that of the cost of injuries or damaged utilities.

For more information regarding the safety guidelines to be adopted in HDD, safety videos, and written procedures developed by drill rig manufacturers and the Association of Equipment Manufacturers should be reviewed.