2021-04-28

Lunenburg installs, ponders prevention measures to avoid repeat of sewer plant flood

by KEITH CORCORAN

  • <p>The cover page of the 40-page report into flooding at Lunenburg&#8217;s sewer plant in 2019.</p>

Lunenburg bought an inflatable temporary plug and is planning for a back-up generator and an actively managed tide gate valve for the town's sewage treatment plant.

These and other short-term flood prevention measures are designed to ensure there is not a repeat of the September 2019 storm surge there.

The recommendations emanate from a flood study report commissioned by the town and carried out by CBCL, a renowned engineering and environmental services firm.

Amid Hurricane Dorian, the floor of Lunenburg's Starr Street wastewater treatment plant flooded with about 60 centimetres of of water. Culverts under Highway 332 and Kissing Bridge Road that link to the plant and back harbour area provided an ample path for stormwater to reach the facility. Wind direction and the topographical configuration around the back harbour also factored in.

CBCL's 40-page report, which cost $25,000, is dated October 2020, however it was only recently released and summarized to civic politicians by town engineering staff. The lag between report-and-presentation was due to the hiring of a new engineering staff during that period and other matters taking higher priority.

CBCL's report advised installing the gate valve - a water control device - on an outer culvert across Highway 332 to the back harbour. "This gate is to be closed during storm surge events, and opened to relieve any runoff accumulation in the marsh after the storm surge has subsided," reads CBCL's recommendation. "This solution is estimated to be satisfactory until at least 2070 under both moderate and high sea level rise scenarios."

Meanwhile, a generator is part of the overall wastewater plant upgrade project and pre-design engineering is expected to evaluate scope and cost estimate this summer. CBCL indicated that the back-up system ensures "that all treated wastewater can be safely pumped to the front harbour, during an emergency situation, when the culverts have been closed to protect the [plant] from storm surge."

Lunenburg deployed the temporary plug, a pipe-blocking tool, once last fall as a precautionary move when it was thought a hurricane may make landfall. Two inflatable plugs were purchased for $8,300 for two culvert locations.

"The culvert plug ... should only be seriously considered if one of the more permanent solutions, such as the tide gate, cannot be implemented in the near future," CBCL noted in the report.

Wastewater spending will make up a significant portion of Lunenburg's 2021-22 capital budget, Mayor Matt Risser told LighthouseNOW. Financial pressures associated with big ticket aging infrastructure is not a concept lost on the chief magistrate, especially when it comes to items regulated by another level of government.

"These types of complex services are always a struggle, particularly for small municipalities," he said during a telephone call. "It's a big thing for us to be taking on."

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