Compliance verification activity type: Field Inspection
Team:
Regulated company: Trans Mountain Pipeline ULC
Operating company: Kinder Morgan Canada Inc
Province(s) / Territory(s):
Discipline(s):
Related events:
Rationale and scope:
TMEP Inspection of Burnaby Mountain Tunnel - Construction and Westridge terminal construction progress. To include follow-up items from CV2122-313.
Compliance tool(s) used:
Facilities:
Facility Types
Life-cycle Phases
Regulatory requirements that apply to this activity:
Observation 1 - Inspection summary
Date & time of visit: 2022-05-09 17:30
Discipline: Integrity Management
Categories:
Facility:
Observations:
Tunnel work: As of May 9, 2022, 1470 m length of tunnel has been excavated and installed 959 PCTL rings have been installed. This comprises the completion of 56% of tunnelling work. The normal pace of the construction is an average of 40 segments per day which is equivalent to 6 rings (~10m of tunnel) per day in two-10 hours shift (Boring time on average is 50 millimetres per minute). TMEP said they use a dedicated FLHA (Field Level Hazard Assessment). A maximum of 16 workers are allowed in the tunnel at one time. At the time of the inspection, the tunnel boring was halted, and only proof grouting injection work was carried out. (See proof grouting issue). Staff noted that some water was flowing from the tunnel. The water was at the 6 o’clock position of the tunnel. TMEP confirmed it was construction-related cleaning water. Annular-Grouting: Right next to the WMT tunnel entrance, a grout plant (40 tons) is set up. The grout is continuously injected into the annulus of the rings and tested every day (7-28 days strength tests are also performed in line with TM specifications TMEP-TU-3200) The plant consists of 4 pumps with 2 in use. Two pumps are redundant. McNally contractor mentioned that approximately 4 cubic meters of grout are used for 0.5m of the ring (the theoretical grout volume per ring is ~3m3). This is an approximation as the exact volume for a ring is not measured because of the continuous injection process. Annular grouting is carried out during tunnelling using the Tunnel Boring Machine (TBM). An annular grouting operation was not observed during the inspection. Proof Grouting: While continuing to bore the tunnel, the proof grouting activities were stopped in March 2022 due to large water inflows coming from a grouting port. TMEP mentioned that the trigger to stop the activities was an RFI response related to issues with proof grouting of rings #325 and #345. These proof grouting activities were only completed once the proof grout RFIs were addressed. TMEP paused tunnel boring in early May in order to catch up on proof grouting activities that were not observed during the inspection. In line with TMEP-TU-2800 specifications, proof grouting needs to be completed at least every 20 rings installed (the first 25 rings installed were systematically tested). Impressions “ports” are 1.5” in diameter and the drill bit is 5/8, the ports are cast into the segment and subsequently drilled-through. Proof grouting injection is performed via the ports located at the 12 o'clock position ("crown of the ring"). TMEP said that any water inflow (i.e., coming from the outside of the ring through the ports) is estimated using the “three buckets" method where the volume of water collected during a certain time is measured. After annular grouting is completed, a proof grouting injection is performed. The injection stops when the ring annulus is 100% filled (where “refusal” is reached). TMEP stated that proof grouting and tunnelling cannot be performed at the same time. The proof grout injection pressure must be within the acceptable range indicated in TMEP specifications TMEP-TU-3200, section 3.3.3: the minimum proof grout injection pressure shall be the existing hydrostatic pressure + 1 bar and the maximum is hydrostatic pressure + 2 bar. During the injection of proof-grouting, if the annulus grouting refusal criterion is not met twice, then it is considered that the proof-grouting does not pass. Therefore, further investigations will be discussed between McNally and TMEP. Further proof grouting can also be conducted 5m downstream and upstream of the “issue” ring to better estimate the potential for voids in the annulus (as per TM specifications TMEP-TU-3200 section 3.5.3.3). TM mentioned for example that rings #445 and 465 had issues. CER Staff asked if other injection ports (located at 3 or 6 o’clock) were used, in case of unsuccessful proof grouting, in order to check the extent of grout filling. TM said that only a few rings were subject to 3 – 6 o’clock proof-grouting injection (rings #321, 296 and 294), but not for the purpose of checking the extent of grout filling. Upon CER Staff request, TM provided their [Updated Proof Grout Log - Tunnel.pdf] which identify the rings where proof grouting (strength test and pressure testing) was executed. CER Staff analyzed the information provided in the document [Updated Proof Grout Log - Tunnel.pdf] confirming that rings #445 up to 865 are subject to further investigations as the tests were not successful (no refusal even with 1000 litres injected, or low pressure that required by the specification TMEP-TU-3200). CER Staff also confirm that proof grouting reported in the Updated Proof Grout Log is effectively executed at least every 20 rings (as per TMEP specifications TMEP-TU-3200 3.3.2). TMEP has stopped the proof grouting operations following the large water inflows event that occurred in March 2022 but resumed proof grouting in May 2022. However, TMEP said there is no timing requirement in the TMEP-TU-3200 specification and mentioned that for some other projects, proof grouting can be carried out once tunnelling and entire annular grouting is completed. With respect to blue marked segments, TMEP mentioned that one blue marked ring (#405) must be investigated as it did not achieve the refusal. As the number of rings and corresponding length of potential voids are significant, TMEP said that on 11 May 2022, a meeting with TMEP, Subject Matters Experts (McNally), and the Engineer Of Record (Hatch contractor) will be held to address the issue. TMEP said that the outcomes of the meeting would be provided to the CER Staff (see IR #1.1 response in the Documents section). PCTL Rings management: As part of the follow-up from CV2122-313, CER Staff observed TMEP’s inspection processes after PCTL segments arrived at the Westridge Marine Terminal. TMEP said that PCTL inspections are performed at 4 different stages: once at the WMT tunnel portal before loading the segment onto the wagon that will transport it inside the tunnel (see document Delivery inspections.pdf), 2 visual inspections inside the tunnel (not documented), and on final inspection to verify Rings alignment (see document Ring reports Tunnel.pdf). CER Staff also requested TM to provide an example of a rejected segment. TMEP provided “May 06 Delivery Segment Inspection - PC Tunnel.pdf” which includes a rejected segment. TMEP indicated as of 9 May 2022 only 3 segments were damaged (corners were damaged during handling of the segment), and one was rejected (the size of the concrete damaged was too important). TMEP also said that PCTL manufacturing is completed at 98 % by the MSE and will complete the manufacturing process in June 2022. WMT tunnel portal has space limitations to stockpile the entire manufactured lot and therefore the storage is located at the MSE. CER Staff inspected a few Rings stockpiled outside the tunnel:
Compliance tool used: No compliance tool used
Identified non-compliances to company plans or procedures are non-compliances either to:
- the condition of an authorization document that requires the implementation of that plan or procedure; or
- the relevant section of the regulations that requires implementation of that plan or procedure including those sections that require implementation of plans or procedures as a part of a Program
