Teamwork: Milepost 781 Dig above Keystone Canyon
Alyeska interim president Betsy Haines recently said: “What an amazing project, one of the most interesting and challenging of the decade! My visit to the worksite with our executive team and owner representatives was a memorable afternoon; the scale was something you had to see to believe. The group was all smiles despite the rain. It’s an honor to recognize this incredible work with a well-deserved Atigun Award for Teamwork.”
This story below was originally written in Dec. 2022.
Birds flying high above Keystone Canyon in summer 2022 witnessed an unusual boom of human activity. An area usually only frequented by bears, coyotes, ravens and an occasional hiker, saw a steady stream of people, trucks, heavy equipment, trailers and more, each making their way up eight hills to a spot approximately 1,100 feet above the Richardson Highway in the foothills of Stone Mountain.
The visitors had an important job – a massive pipeline integrity dig on a steeply inclined section of the TAPS Right of Way. Inline inspection tool findings alerted Alyeska to an abnormality on this section pipe and set the work in motion. After careful assessment and tracking and a project that removed more than 14,000 cubic yards of rockslide debris, it was time to survey, excavate, assess, repair and backfill a 26-foot section of pipe.
“This project, hands down, was one of the most unique pieces of work that TAPS has encountered since pipeline construction,” said Phil Huelskoetter, civil maintenance coordinator and one of two Alyeska leads for the project.
Setting the stage
Success was seeded from the beginning. The project design phase began years before when Alyeska system integrity engineer Frank Wuttig started working to choose an implementation firm. Condon Johnson (CJA) rose to the top.
“Early planning was so important,” said Nick Hasting, implementation assurance lead and Huelskoetter’s alternate on the project. “The early design meetings, the site visits, and the right contractor, CJA. When you bring a group in that has done this work – it’s what they do – it’s hard to beat. They made our life in the field a lot easier.”
Mobilizing materials and equipment to the scene was complicated by the site’s tricky access. Heavy equipment hauled in everything needed to perform the work since the challenging terrain did not allow for traditional tractor trailer access. Operators made several hundred trips transporting materials and equipment before excavation work began in late June. Each trip took 20-30 minutes one way, with close radio contact used to communicate along the narrow road.
Calling in reinforcement
On a steep hill that averaged a 22% longitudinal grade, a flat work pad was carefully fashioned and heavily reinforced for worker safety. Even before crews and excavators began digging, CJA fortified the slope above the work pad by excavating and installing a soil nail wall with 100 Tecco mesh protected soil nails affixed to a flat working bench. Berms and concrete barriers diverted rockfall from the site.
Once the work pad was established, crews began tunneling down to the site. A mini-excavator filled a special dirt bucket hoisted by crane to the work pad. As the 28′ diameter hole got deeper and deeper, personnel installed liner plate shoring to stabilize the walls of the dig, keeping the workers inside safe. Installing the shoring system required more than 6,000 hand-tightened pairs of nuts and bolts.
In between a rock and a hard place
Excavation below the pipe revealed the cause of the anomaly identified by inline inspection. A 10 ft. by 4 ft. boulder sat just under the pipeline with less than a foot touching the pipe, precisely where the “smart pig” detected the dent. There since construction, the boulder was removed piece by piece, mostly by hand and “very, very carefully,” according to Huelskoetter.
Rolling down their sleeve
With the pipe was exposed and the rock removed, Ahtna crews prepared the site for inspection with additional scaffolding and sandblasting the pipe. The inspection process was led by Matt Johnson with the Alyeska Systems Integrity team, with support from contractor TEAM Industrial. They reviewed the data and determined a sleeve would reinforce the slightly dented area of pipe.
The 4.5 foot sleeve utilized two contact bands welded to the mainline on the inner and outer edges with a bridge sleeve installed between them. The bridge sleeve then was fully welded to the contact bands. The annulus between the bridge sleeve and the pipeline was injected with grout. Houston Contracting Company pipe fitters completed the installation on August 30. With the sleeve in place, the entire exposed area was coated to protect the steel from corrosion.
Back(fill) to the future
Returning the site to its original TAPS design and elevation was the project’s final step. The liner plate shoring system was incrementally removed. Concrete trucks delivered more than 440 yards of slurry over seven days to backfill the excavation and site remediation finished on September 23.
Rain, rain and more rain
On such challenging terrain, the project was always going to be a #TAPSPride worthy effort, but the weather made things even more complicated as the area received above average rainfall in July through October. “Without a doubt, the biggest challenge was the weather. Any time you have an excavation and add rain to it, it’s a challenge,” said Hasting. “I’m not from Valdez, but I know to expect rain every day in August. But this year, it rained for three months straight!”
With careful planning and preparation, equipment to repair erosion and dewater the excavation was on site and the issues were continually mitigated.
The MP 781 project relied on work groups across Alyeska, every major contractor on TAPS, and many smaller ones as well. Teamwork drove success: Alyeska’s civil maintenance team worked closely with integrity engineers, safety and environment personnel. On top of the support provided by Condon Johnson, Ahtna Construction, HCC and Team Industrial, other contractors had their hands in the effort; Ahtna LWS Survey assisted with surveying, additional engineering was completed by Golder Associates and Coffman Engineering. Hi-Tech carried out rock fall mitigation.
The project team hosted a steady stream of visitors to the site, due to its importance and access 20 minutes from Valdez. Over the course of the summer, regulators, executives and owners made site visits.
“Everyone – from leadership to boots on the ground – everyone played a role in the success of this project,” said Hasting. “It’s a project for all of Alyeska to be proud of.”
The embodiment of #TAPSPride
On September 26, 2022 the MP 781 mission was achieved on time, on budget and without injury. “The work at MP 781.14 showcased that, no matter what the task is or how challenging it may appear, great things can be accomplished,” remarked Huelskoetter.
And the experience is already shaping future integrity digs.
“Next summer, we’re planning another integrity dig north Thompson Pass near the Tsina River. This project will be a specialty dig because of its depth and location. We’re already meeting with CJA about it; we’re going to take what we learned at MP 781 and do it again at MP 758,” said Hasting.
Huelskoetter reflected on the power of partnerships and their impact on the work above Keystone Canyon this summer:
“Ultimately, the teamwork involved in this project delivered the assurance of the integrity of our pipeline for generations to come. Keeping people and the environment safe is key, in the end it is what’s the most important.”