In an effort to minimize hydro acoustic noise impact and dive times for an efficient and safe pile cutting procedure, a leading company hired Mactech to produce the best internal cutting solution.

After careful consideration, Mactech’s ID Sever Machine was chosen to complete the cutting procedure. Mactech worked to provide a 33”-60” ID Milling Machine to cut each pile at the mudline.

Mactech’s Value Added to the Project

The Cook Inlet is notorious for huge tidal swings and fast currents as a result which limit dive time to 20-30 minutes per tidal cycle. As such, the client was looking for a diverless cutting solution. The options were the Mactech ID Sever Machine or an Abrasive Waterjet Tool, which has a much higher cost per cut that the Mactech approach.

Alternative Methods to Mactech’s Solution

Abrasive Waterjet Cutter. Larger spread, larger crew, higher per cut costs, the work location was also a factor, mobilizing gear to or from the mainland takes weeks or has extremely high “hotshot” costs. Mactech was able to work with the client on the standby rates to make it economical for them to use our solution.

Steps Taken to Complete the Job

There were 3 main operations – Pile installation, restrike pile, and cut pile. Mactech had a pile sample made using the customer’s specified material and made documented proving cuts at our MN facility to comfort the client’s concern over the effectiveness of our solution. With their Derrick Barge onsite, and an alternative cutting method weeks away, it was imperative that our tool work as designed.

Challenges and Advantages

The conditions and location provided challenges on the project. The project took place on the Knik Arm in upper Cook Inlet, which has tidal swings ranging from 25 feet to 35 feet and currents ranging from 2-4 knots. The Cook Inlet Beluga Whale population is listed as endangered by the National Marine Fisheries Service (NMFS). If any were sighted within 30 minutes before or anytime during operations, pile installation and restrikes were delayed. Working near/in Alaska’s busiest and most important transportation hub of goods and fuel would sometimes cause schedule conflicts and required a lot of logistical coordination.


The cutting procedure was completed on time and within budget.