Plume studies

Englobe project managers, Chris Gallant and Natasha Horsman have been charged with the unique and important task of analyzing the effects of wastewater effluent pumped into the Northumberland Strait by the Greater Shediac Sewage Commission in southern New Brunswick. Known as a plume study, they are tracking the distance and radius the treated water reaches to ensure it isn’t harmful to the public, namely the local community – including tourists – who flock to Shediac’s and surround each summer.

How a plume study works

As shown in this drone footage, dye can be discharged into a body of water during both high and low tide, as well as amid varying weather conditions, and instruments can be used to measure the dye particles of the plume to determine its direction and dilution. This is how the effectively determines the effluent’s path in Shediac and its concentration in the ocean (when it reaches its dilution factor – ideally, 1:100).

“Once the dye is discharged into the water, we get an accurate depiction of where the plume is generally headed, in addition to how quickly it’s diluting because you have a grace period once it’s discharged, as to how much concentration it is acceptable for the receiving body of water to have.” added Natasha.

Typically, the plume can reach anywhere from 400 to 1,000 metres in radius from the source, depending on the weather. The drone footage can then be uploaded to a computer software that generates models mimicking severe weather events such as storms, to determine whether the effluent should be released further out into the strait, according to acceptable norms.

Beyond quality assurance, why is the Commission paying for this study now?

Following several public consultations and majority community approval, Shediac has mandated Englobe with the construction of a new wastewater treatment facility comprising a state-of-the-art headworks building and ponds to treat additional volume. What will become one of the , construction is set to begin next year with an expected completion date by 2024.

“With a price tag of $32 million, it’s one of the biggest – if not, THE biggest, contract that Englobe’s Moncton team has been awarded to date.” declared Chris, “

What are the benefits of building a new facility?

• Improved capacity for the town’s wastewater management
• Mitigation of water quality concerns 
• Custom, modern design that considers surrounding wildlife, for example: including berms in the project plans upon which local and migrating birds can build their nests. Certain types of birds will nest there almost immediately.

What do we hope to achieve through this project?

“Shediac is growing probably faster than any town or city in this province, and it’s a coastal town. Therefore, water quality is its most important asset.” clarified Chris, “This facility will probably be the most advanced one this side of Quebec, so it will be producing water quality well past provincial requirements. The Commission wanted to exceed the current quality; most wastewater treatment plants or lagoons are not discharging this kind of modern quality treated water. When all is said and done, we will be seeing multiple levels of treatment and that’s what’s important – for the environment, our client and Englobe.”