The agreement also stipulated that there would be a minimum distance of 1 m between installations using the HDB installation method. In addition, Enbridge`s line representative had the authority to suspend work at any time in the event of concerns about the integrity of the pipeline or damage to Enbridge`s facilities or equipment. On the surface of the Line 2 pipeline junction, an access ramp from Rig mats for heavy vehicles extended over the pipeline. In the weeks leading up to the start of drilling for the NPS 20 pipeline, the Ledcor field team and the Enbridge representative discussed how the visual confirmation of the Line 2 pipeline would be carried out. To perform a hydrovac at this location along the NPS 20 trench line, the local Rig mast would first need to be highlighted and removed. Figure 13 shows the lines of communication between key team members. On November 29, 2016, Enbridge awarded the signed border crossing contract to GRP Ltd. after It was verified and approved by Enbridge`s Land Services Department. In one of these emails (dated January 23, 2017), GRP Ltd.
applied to Enbridge for permission to install the NPS 20 and NPS 36 pipelines in the eastern corridor with HDB (i.e. instead of an open ditch in accordance with the original agreement). However, this email is an extension of a previous email threadFootnote 28, which initially concerned only the NPS 36 pipeline. As a result, Enbridge has granted the authorization and has provided that it applies only to the NPS 36 pipeline. However, GRP Ltd also interpreted the authorisation for the NPS 20 pipeline. The amendment approved in the form of emails was appended to the original crossover agreement. (For more information, see Appendix A) On the checklist completed on the day of the occurrence, no differences were found with respect to the items requiring daylight and confirmation from foreign supply sites. The soil disturbance checklist incorrectly showed that visual deep confirmation was performed for all pipes to be crossed. As a result, there was a missed opportunity to continue to assess the drilling path at the Line 2 gas pipeline crossing. To determine the final drilling path for the NPS 20 pipeline, the Ledcor project engineer checked the cutting sheet. Based on the underlined value, the Ledcor project engineer felt that this had been done to emphasize that there was a significant difference between the declared depth of coverage of Line 2 at the envisaged crossing and the value of the initial crossing agreement.
The lack of clarity on the email request to amend the crossing agreement resulted in a missed opportunity to identify the potential conflict with the Line 2 pipeline. If no detailed procedure for modifying crossing agreements is established and followed, it is not possible to accurately identify all pipelines crossed, increasing the risk that a pipeline in service will be damaged during a ground malfunction. Ledcor has drawn up an implementation plan containing the provisions of the crossing agreements. GRP Ltd. has reviewed and accepted the plan. According to the plan, the following activities were to be completed before the start and during the operation of HDB: the operation of the pipeline, the condition of the pipeline and the integrity of the pipeline were not considered to be the cause of this accident. . . .