Orcas Power and Light Cooperative is a member-owned, non-profit cooperative electric utility providing electric power from the main land to the San Juan Islands. The San Juan Islands are an archipelago located in Washington State between the U.S. mainland and Vancouver Island, British Columbia, Canada.
The Mosquito Pass Cable Conduit Installation Project required a horizontal directional drilling (HDD) installation of approximately 2,000 lf of 8-in., HDPE SDR 7 pipe — the majority in solid rock formations, from San Juan Island, under Mosquito Pass, to Henry Island. The purpose of the new 8-in. pipe was to provide a casing to replace a failing electric underwater power cable and provide an option for future Internet and water services to Henry Island.
Due to the project’s location in a very pristine and environmentally sensitive area of Washington State, an extensive permitting process with several agencies was required. OPELCO project administrator Joel Mietzner was instrumental in securing permits, easements and managing property owner negotiations during the planning and construction phases of the project.
The geographic location of the project presented several challenges. Tidal currents through Mosquito Pass made conventional walkover or wire grid locating of the pilot hole construction impractical. Drilling fluid management presented challenges as Henry Island is accessible only by small barge or landing craft vessels. Additionally, rainwater, collected in cisterns, is the only source of water on Henry Island. Any additional excavation in the vicinity of entrance and exit pits was restricted due to potential archeological concerns.
Getting the Bid
Trenchless Construction Services LLC was the low bidder on the project, bid on May 13, 2014. The project had an earliest starting date of September 2014, as the HDD entrance and exit locations were in proximity to very expensive vacation homes.
Although Trenchless Construction Services has been in the HDD business since 1999 and has completed numerous challenging HDD installations during that time, the Mosquito Pass Cable Conduit Installation Project was the company’s longest major project in solid rock.
Immediately following a formal notice to proceed, Trenchless Construction Services began formulating a team of key trenchless employees, material and equipment suppliers and sub-contractors to assist with the construction the project.
The first order of business was to acquire bigger HDD equipment than the company currently owned and staff training with the new equipment. After considering several options, the contractor purchased a new Universal HDD 250 X 400 Directional Drill and Off-board Mud Pump System. Universal HDD general manager Alex Veytsman was instrumental in providing the new 250 X 400 directional drill and off-board mud pump system to meet the construction schedule. Universal HDD also provided operational training of trenchless employees and assisted with the initial on-jobsite set up.
Due to tidal currents through Mosquito Pass, the bore depth, and the accuracy required at the exit point, the optional use of a conventional walkover or wire grid locating of the pilot hole construction was eliminated. SlimDril International operations manager Rollin Boyd recommended and provided the downhole pilot bore tooling, including a Gyro locating system and 6 ¾-in. mud motor, for the project.
Specially designed downhole reaming equipment was provided by Brook Niemi, sales manager of Inter-Mountain Drilling Supply and Dan Martin, owner of Everett Engineering.
Drilling fluid material, mix design and trenchless employee training was provided by Warren Lear, HDD Tech Service Mgr. of M-I SWACO.
Mobilization and setup at the drill entry point began Sept. 30, 2014, with pilot hole construction with the HDD 250 X 400 starting on Oct. 9. The 9 7/8-in. pilot hole was completed on Oct. 28, 2014. Gyro downhole guidance was provided by Art Nieto of SlimDril International.
Reaming operations of the bore hole to 16 in. started on Oct. 30 and completed on Nov. 13. One of the major challenges of this project was the storage and disposal of excess drilling fluids and access to fresh water on the remote Henry Island drill exit site. To address these issues, Trenchless Construction Services stationed a Vermeer 80 X 100 HDD and a Mud Technologies MCT 450 Recycler at the exit pit and recycled and pumped drilling fluids to the 16-in. reamer as the reamer was being pulled back to the HDD250 X 400 stationed at the drill entry pit on San Juan Island. Make-up water was pumped from San Juan Island through the HDD 250 X 400 drill steel to the exit pit on Henry Island and tank stored for future use, as needed.
The 8-in., HDPE SDR 7 casing, fused and stationed adjacent to the drill entry pit on San Juan Island, was pulled into place by the Vermeer D80 X 100 stationed at the exit pit on Henry Island on Nov. 15, 2014.
To dispose of the excess drilling fluids accumulated on Henry Island, the D80 X 100 drill rods were inserted into the newly installed 8-in. HDPE Casing and excess drilling fluids were pumped to the drill entry pit on San Juan Island.
Following the disposal of all excess drilling fluids at the drill entry point on San Juan Island, 2 EA 2-in. HDPE Pipes and a new electric power cable were pulled from the drill entry pit on San Juan Island to the drill exit pit on Henry Island by the Vermeer D 80 X 100.
The success of the 2014 Mosquito Pass Cable Conduit Installation Project can be attributed to a total team effort by a highly qualified and dedicated group of trenchless construction employees. Mark Handy, superintendent; Tony Arriaga, 250 X 400 drill operator; Shane Whited, crane operator; Russell Swett and Travis Freeman, reclaimer operators; and Josh Kilpatrick, equipment operator, all worked closely together and in conjunction with an outstanding support group including owner representatives and material and equipment Suppliers/sub-contractors.
Although the team faced several challenges during the project, timely corrective actions and adjustments lead to a highly successful project for all parties involved.
John Gustafson is managing member of Trenchless Construction Services LLC.