Water Street 'big dig' ditched for trenchless method: Here's how it will work

The City of St. John's has abandonedplans to dig up Water Street to replace the aging water and sewer pipes underneath in favour of a trenchlessapproach buthow exactly will that work?

Trenchless technology involves replacing or reinforcing underground pipes without having to dig up large areas of the street to get at and remove them.

In some cases the existing pipes are destroyed and replaced, but forthe Water Street projectset to begin in 2018 the plan is now to reinforce the existing pipes by filling them with aplastic-like material called an epoxy resin, which will then coatthe insideand harden to form a new lining.

Water Street infrastructure project delayed

8 years ago

Duration 2:08

The big dig on Water Street has been delayed until 2018, where much of the work will be done using "trenchless" technology.

Coun. Danny Breen said the approach is not only less disruptive to businesses and traffic than the original plan, but will cost 25 to 30 per cent less than traditonal replacement, and should last for at least 40 years.

Unusual pipes

Trenchless technology was used in the city before on Wishingwell Road and in Shea Heights and Breen is confident it will work on the old stone sewer pipes downtown as well.

"You're keeping the outside stone pipe, as that provides you with the support. Then inside it you have a new pipe," he said."It will last. It's been tested. It's durable and it's been done in other places, so we think it's the best solution for everybody."

Breen said the existingdowntown pipes are unusual as they are egg-shaped and made from brick, but after someresearch it was determined that the trenchless method would still work on them.

In fact, hesaid the new lining will actually stop ground water from seeping through the brickpipe and going into the pipe's flow water which then needlessly endsup being processed through the city's sewage treatment plant.

Holes on side streets

While there are no plans to digright on Water Street itself, there will stillbe holes dugto get atthe pipes. Baird's Cove and other connecting side streetswill be excavated. Breen said vehicle traffic will still continue to flow but with some delays and detours at times.

"It has to come down to the individual businesses and their requirements during the project to make sure that we minimize the disruption to their businesses," he said.

Breen said the plan is to start working on the west end of Water Street, and then move east, city block by city block. With underground infrastructure that is more than a century old, the city is aware there may be some unusual things to deal with along the way.

"I'm sure there's going to be challenges as we move through it," he said.

"But both our engineering staff and our consulting engineers along with the experts in this type of engineering technology are confident that this is a good procedure."

Breensaid the work is delayed until2018 to givethe city, businesses, engineers and consultants timeto figure out how to best phase inthe work. The first step is to have the contractgo to tender, but he expects even when the work starts it could take several years before all the pipes have been reinforced.

The video below demonstrateshow the trenchless method works on a residential property: