District of Squamish has no plans to undertake a wide-scale replacement of ditches with pipes, although it will consider requests from property owners to install pipes in front of their property.
Responding to a citizen’s observation about replacing ditches with pipes, David Roulston, Manager of Municipal Infrastructure, said district recognized the value in retaining ditches.
Ditches promote natural infiltration and reduce peak flows in the drainage system and downstream watercourses which can cause flooding and erosion, he said.
Infiltration also assists with maintaining base flows to watercourses during drier times of year to prevent watercourses from going dry.
Other benefits include environmental benefits such as biofiltration which removes contaminants such as heavy metals, petrochemicals, silt.
“Conversely, piped systems can cause higher peak flows (and resulting flooding and erosion), reduce stormwater storage, deplete the groundwater table and directly convey contaminants to sensitive downstream environments,” he told the local resident.
Replacing ditches with piped systems on a wide scale would be very costly, he added.
The district does not have a dedicated budget to undertake this work.
“The district will consider requests on a case by case basis from property owners who wish to install culverts fronting their property at their own cost,” he noted.
However, the district will consider the environmental value of the ditch, the length of pipes proposed and whether it meets all provincial and municipal regulations.
