Pipeline organizations are acutely aware of risks posed by natural gas cross bores caused by horizontal directional drilling (HDD), but although necessary, efforts to mitigate these risks can result in expansive and costly programs. Before we get into the specifics of the financial pitfalls your cross bore program could be facing, let's briefly look into why cross bore programs are important.
What's a Cross Bore?
A sewer cross bore is the inadvertent placement of a gas main or service through a sewer line, and typically occur during trenchless construction. Cross bores are a threat to the safety of industry workers and the general public in surrounding areas. The sewer line may become blocked and need to be cleared by a plumber or the building owner with adequate clearing tools. This may cause the gas line to be cut which could cause an explosion or fire. Energized utilities, such as natural gas, have potential immediate and long term danger which makes the detection, repair, and prevention of sewer cross bores a prominent part of integrity management programs across the industry. The knowledge of sewer and gas line intersections and the subsequent inspection locations are vital to the success of any cross bore program.
Inefficient Sewer Inspections
A component that can have a significant effect on your cross bore program budget is the efficiency of the sewer inspection execution. Sewers are fundamentally complex, reliable maps are hard to track down, and there are often times access limitations such as offsets, collapses, or buried cleanouts. Since locating the inspection can become area difficult, field crews run into inadvertent challenges such as:
- missed inspections
- failure to complete inspections at full length
- duplicated inspections
These can lead to an overall decline in productivity, cause schedule delays, and cost overruns. See an example of cumulative effects that missed and duplicated inspections can have in our recent Whitepaper.
The need for having accurate and precise information about the completion status of a designated inspection is necessary to ensure that field crews perfor the correct work, and for accurate accounting. When incorrect completion statuses, false completes and false incompletes, are entered into the database the risk of cross bores going undiscovered increases as well as additional schedule delays. Overall productivity is reduced when additional truck resources are added to maintain schedule, and additional administrative costs are applied to an extended schedule after field oversights.
The video review stage can also be a serious source of additional risk in overlooked cross bores. Factors such as screen visibility in variable light/weather, push camera operators operating alone, and poor training all contributed to this error rate.
Inefficient Data Management
Cross bore programs mirror sewer systems’ complexities. They require many moving parts and are as much data management projects as they are field projects. Requirements for assembling a record of information that is verifiable, traceable, and complete include:
- Field forms
- Sewer inspection data
- Geospatial information
- And more
The task of managing this data can become less efficient with many data sources changing between the field and office. When data is fragmented into multiple locations, requiring reliance on manual transfers, it is easy for some of it to get lost, incurring additional costs of retrieving lost data and additional resources.
There are simple solutions to mitigate the risks mentioned above and reduce incurred costs in your cross bore program. Some of these solutions include deploying maps to field crews, implementing an automated workflow management system, and performing video QC. To learn more about these solutions and others that can make your cross bore program run more efficiently, download G2’s Whitepaper: Five Financial Pitfalls of Cross Bore Programs & How to Avoid.