The past two years have seen many new initiatives that impact horizontal directional drilling (HDD). With HDD becoming a mature methodology, associations, government agencies and legislative groups from many origins have come to similar conclusions - that some form of industry-wide standard guidelines would mitigate HDD damages and accidents. Almost in the same breath, most initiatives call for a standardized training curriculum.
In December 2000 during back-to-back round table discussions, I had the opportunity to moderate several contractor, engineer and owner all-day sessions that add-ressed third-party damages and directional drilling. What follows is a compilation of the cream of the crop - the best practices for HDD damage prevention.
Just as a curriculum for directional drilling often is divided into pre-construction, construction and post-construction sections, our purposes here are best served by such an outline.
- Design realistic placement.
- Address the actual depth of existing infrastructure.
- Soil formation information/core samples should be provided.
- Engineers should use computer based bore-planners.
- Owners should select qualified HDD contractors.
- Fast-track start and completion deadlines should be shamed.
- Empower right -of-way gatekeepers to make and enforce placement standards.
- Bid documents should address actual length of bore and wireline locate tools.
- For possible electronic interference, itemize wireless locating equipment.
Use the One-call System
- Avoid bundled call requests.
- Call on off-peak days.
- Only request actual work.
- White line the bore path.
- Refresh tickets.
- Coordinate regular meetings with excavators, owners and locators.
- Promote full participation from all utilities in one-call system.
Site Investigation and Evaluation
- Employ high-tech locating technology such as Ground Penetrating Radar (GPR) and acoustic in underground survey.
- Request sewer lateral maps from the water company.
- Open manholes to determine direction of lines and verify depths.
- Familiarize crews with signs of utility placement (pedestals, manholes, tie-in boxes, private lighting).
Planning of Excavation
- Include a permanent method of locating when installing for future excavation.
- Mark and plot bore path, entry and exit points.
- Mentally plot side-view of entire bore path.
- Avoid exiting at congested pedestal/pole locations ("spider holes").
- Respect safety zones vertically and horizontally.
- Anticipate back-reamer diameter during pilot bore.
- Understand "deflection", "drill string straightening" and soil behavior.
- Report all hits, nicks and scratches
- Pay attention to atypical sounds and resistance.
- Inspectors should be trained and read drill head locator systems.
- Participate in local utility coordinating committees.
- Remember that HDD is not always the best way - protect the reputation of HDD.
- Attend refresher classes and cross-train on how other utilities are installed.
- Provide HDD training geared at inspectors and design engineers.
Drilling Safety Rules
- At all times, know where your drill head is and where existing underground facilities are located.