A big excavation project led to equally big surprises for a project team at CFB Comox looking to improve the base's drainage system which was impacting neighbouring properties.
“Because it was such a big excavation project on an older site – we ran into unknowns every single day,” said Joel Upsdell, DCC Technical Specialist, Project Management in Comox, about the Queen's Ditch Infrastructure Improvements and Flood Protection Project.
Those unknowns included abandoned fuel lines that weren't actually abandoned, contaminated soils, and even finding fish in unlikely areas.
Queen's Ditch is a manmade drainage system created originally in the 1940s. Over the last decade, it had become apparent that more water management was required as flooding on properties along its path began to occur.
The project team started with a flow monitoring study, and it was found that in large storm events, runoff from the base was having an impact. The solution they found included constructing a series of retention (wet all the time) and detention (dry when not in use) ponds, connected to the ditch system.
“By retaining and slowly releasing water, it's meant to better manage the impact downstream,” said Upsdell.
They found locations for the new ponds on DND property – and started to dig just in time for one of the wettest April/Mays on record.
“It's probably the largest excavation project that has been done since the base was constructed—it was essential to manage the aspects of both water and soil,” said Upsdell.
Construction of the roughly $3.75-million project was completed in May 2018, to be ready for its first fall/winter on the rainy west coast.