The Board of Water Supply’s head announced that the utility will begin work today to attempt for the first time to repair a “very critical main in our water system” along the Moanalua Freeway from the inside of the pipe, which, if successful, will shave off a couple of weeks in repair time.

BWS Manager and Chief Engineer Ernest Lau said he estimates that with the new method it will take until the second or third week of July, working every day around the clock, to repair the 42-inch main that has required closure of some westbound lanes of the Moanalua Freeway.

Lau told reporters at a news conference Friday at BWS headquarters that this procedure has never been attempted before because “most of our water mains can’t fit a person into the pipe.” The work has always been done from the outside.

Phoenix International, which specializes in marine welding, will send someone inside the 42-inch main — the largest pipe in the BWS system — to repair a 6-by-10-inch hole by welding a repair plate over the tear from the inside of the quarter-inch steel pipe.

BWS officials will know by next week whether this method is successful, Lau said. If it fails and the standard method is used, it will probably be completed by late July, he said.

Hensel Phelps, a contractor for the U.S. Army Corps of Engineers, ruptured the pipe June 18 by using horizontal directional drilling equipment while microtunneling under the freeway to put in a sewer line for Fort Shafter.

BWS obtained a photo of the hole by excavating 16 feet down, breaking the 1-foot-thick concrete jacket that surrounds the pipe and exposing the steel pipe and cutting a hole into it. A camera was lowered into the pipe to help understand the nature of the damage and how to repair it.

Lau said the horizontal directional drilling tool ground through the concrete jacket and started to damage the steel pipe.

Although the hole is relatively small, it’s still serious, he said.

Once the repair to the pipe is complete, BWS will use jet grouting — drilling small-diameter holes near the concrete jacket and pumping cement grout to fill the void created by the damage.

The pipe will then be flushed out to remove debris, and the water will be tested to ensure it meets drinking standards.

LAU SAID there is also another “small puka” in the pipe created by one of the teeth in the drilling equipment.

If the repair from the inside fails, BWS will resort to its standard method of digging a deeper, larger hole in the ground to get to the outside of the pipe to expose the damaged area, which is near the bottom of the pipe, then weld a repair plate from the outside.

The area is just outside an area that BWS had shored up, so it will require more injection of cement grout to a larger area to stabilize the soil to prevent risk of collapse and injury to workers.

The final step requires repairing the freeway.

Department of Transportation spokeswoman Shelley Kunishige thanked the media for getting out the word about avoiding the area due to lane closures. “People are listening,” she said.

She reported that Moana­lua Freeway traffic is still less than 18% of what it was pre-COVID-19, and during the peak afternoon traffic it is “flowing well” with 500 fewer vehicles on the freeway at Fort Shafter following the main break.

The city Transportation Services Department also reports traffic is flowing normally on all the city’s major thoroughfares.

THREE OF the Moanalua Freeway’s four lanes in the Fort Shafter area are open, but an additional lane may have to be closed during night hours.

“We appreciate everybody’s patience,” Lau said.

And while traffic is a concern for BWS and motorists due to lane closures, it is not the main concern.

“The water system is stressed right now, with other sources having to make up the difference,” Lau said.

The main serves Honolulu from Kalihi to Hawaii Kai, and while it remains offline the system is drawing water from other sources. BWS does not want to put a strain on the other parts of the system, and is monitoring water levels in its east tanks before getting into the peak season for water demands, Lau said.

He called upon everyone “to use water wisely. Don’t waste it. It’s a precious resource from our community.”