LETTER: Rain gardens part of urban rainwater runoff solution

LETTER: Rain gardens part of urban rainwater runoff solution

A letter to the editor in the Nov. 23 issue of the PQB News (Qualicum Beach intersection design is all wet) raised a number of concerns regarding the newly constructed rain garden at the intersection of Memorial Drive and Crescent Road West in Qualicum Beach.

It might be helpful to consider the role of rain gardens as part of the rainwater management system in urban settings. The Capital Regional District definition describes them as “landscape features designed to treat stormwater runoff from hard surfaces such as roofs, roads and parking lots. They consist of sunken garden spaces where runoff can pond and infiltrate into deep constructed soils and then into the native soils below. Rain gardens often have a drain rock reservoir and perforated drain system to take excess water to the storm drain system. The constructed soils of the rain garden are designed to replicate as many of the pollutant removal mechanisms that operate in forested ecosystems.

Qualicum Beach Streamkeepers are strong supporters of rain gardens and of this specific rain garden. It is operating as designed, capturing and slowing the rush of water, allowing pollutants to settle from the “first flush” of runoff, and then releasing excess water from high water events, such as the one experienced last week, into the storm drain system. The rain garden is not intended to capture all the water from extreme events; to do so would require a much larger capacity. Rather, it operates as part of the overall storm water management system, reducing peak flow levels downstream and protecting both municipal storm drain culverts and natural habitat.

We have observed over the past decade an increase in the intensity of rainfall events, resulting in higher levels of erosion on streambanks — negatively affecting salmon habitat — and more pressure on town culverts and pipes. More rain gardens and water retention ponds will be needed in the future, not only in new housing developments but also in established neighbourhoods. The Memorial Drive rain garden is an excellent example of the latter.

We look forward to observing its operation and supporting the Town of Qualicum Beach in the addition of more rain gardens in the future.

David James, president

Qualicum Beach Streamkeepers