The Town of Cobourg says it has started work to remove drilling mud from the east tributary of Brook Creek after an accidental discharge during micro-tunnelling activity earlier this month.
Town officials say the cleanup operation started Monday and will continue throughout the week, with environmental monitoring and remediation measures in place.
The incident occurred on Nov. 18, when pressurized drilling mud used in the installation of a trunk sanitary sewer entered the waterway about 350 metres north of the railway tracks at Brook Road North, according to the town.
Since then, the town and its consultants have been co-ordinating with the Ganaraska Region Conservation Authority, Ontario’s Ministry of the Environment, Conservation and Parks, and the federal Department of Fisheries and Oceans to develop a recovery strategy, explain officials.
Officials say the drilling mud has since settled and containment measures were implemented to prevent migration further along the creek. The remediation plan includes vacuum extraction of the mud, ongoing monitoring and adaptive measures as necessary depending on conditions observed during cleanup.
Residents are advised that some cloudiness, which has been described as a milky appearance, may occur temporarily as sediment is disturbed during removal. The town says this is anticipated and should dissipate within a few days once remediation is complete.
Drilling mud is used in trenchless construction methods to lubricate tunnelling equipment and transport displaced soil. The product in use on this project consists of bentonite clay mixed with water and is certified as inert and non-hazardous under potable-water safety standards, explain officials.
The town says it will continue to work with regulatory agencies, keep residents informed and ensure environmental protection measures remain in place as cleanup progresses.
(Written by: Joseph Goden)