There are many issues associated with the impacts of residential construction on watersheds. Examples include sediment laden or chemically contaminated water entering into watercourses and a trend towards increased home sizes that can reduce the amount of land available for rainwater infiltration. The cumulative effects of widespread construction are not well understood and there is not currently an easy to follow guide to help builders and contractors minimize damage to the surrounding watershed while building or renovating single-family homes.
There are two overall objectives associated with this project. The first is to create a clear, easy to follow, online resource that can be used to reduce the potential negative impacts of residential construction on watercourses and watersheds. The second objective is to obtain buy-in from the construction industry in order to facilitate small changes that will have a positive impact on watershed health.
The North Shore is made up of three municipalities: the District of North Vancouver, the City of North Vancouver and the District of West Vancouver. Collectively, these municipalities are referred to as the North Shore. Every year, each one of these municipalities issues hundreds of building permits for the construction or renovation of single-family homes. While there are bylaws in place in each of these municipalities that try to prevent pollution of the storm water system, there are no mechanisms in place to help builders reduce their impacts at each phase of the construction process. This project aims to identify current gaps in knowledge within the residential construction industry, identify key issues at each phase of a residential building process affecting watersheds, and will then attempt to create a clear, easy to follow, generic procedure for builders to follow in order to minimize their impact at each phase of the building process.
The current challenge is multifaceted and can be seen as a communication issue between municipal staff and private contractors, combined with a lack of awareness in the construction industry of the negative impacts building a home can have on a watercourse and watershed. While the impacts from building one home might not be significant, when the effects from all of the homes built each year are combined, the results can be significant.
The first step of this project is to conduct a base line, information gathering survey using an anonymous questionnaire. The target audience of this survey includes builders and contractors, architects and designers and the various sub-trades involved in building residential homes on the North Shore. The questionnaire will be used to gauge the current level of knowledge about the impacts of residential construction, as well as the willingness to change how homes are currently built in order to minimize the impacts to watershed health. No information about company names or people will be recorded.
The second step of this project is to determine and outline all of the phases involved with a typical residential construction project in order to identify the watershed impacts that can occur at each distinct phase. After determining these phases, it will be important to weigh the risks of watershed health from activities conducted in different phases and rank and compare phases to determine which appears to be most detrimental. The most detrimental phases will be defined as those that carry the highest risk without application of better management and design practices.
Residential construction can negatively impact local watercourses and entire watersheds in many ways. Some examples of the potential negative impacts include:
- Run off generated from land clearing activities often enters the storm system unfiltered; the suspended sediment can directly affects aquatic life (damage to fish gills, settling over eggs, reduces visibility for foraging etc.)
- Products used during residential construction often leave site and enter the storm system; these products can have detrimental effects on ecosystems because of the chemicals they may contain. Examples include: paint, drywall residue, tile/stone cutting dust, silica dust, damp proofing spray (often a petroleum based product), concrete run off (lime based) etc.
- Dwelling size is increasing on most lots, reducing the area of land left to allow for rainwater infiltration
- Lack of understanding/no appetite/no incentive/no knowledge to install water storage features on lots. Examples include rain gardens with storage, swales with storage and green roofs.
While the overarching goal of this project is to provide a procedure to guide members of the construction industry in order to reduce the negative impacts that residential construction projects can have on watershed health, there are many objectives to be met along the way leading up to this major goal. Some of the smaller objectives required to meet the overall goal include:
- Creating and distributing a questionnaire that will be completed anonymously by contractors working on the North Shore to identify the current gaps in knowledge surrounding watersheds and the impacts of the residential construction industry
- Identifying building practices that have the potential to negatively affect watercourses and watersheds
- Determining a more proactive way to communicate to the affected stakeholder groups based upon the questionnaire feedback
The main outcome of this project is to create a clear, easy-to-follow, generic procedure for builders to follow that explains the benefits that small changes in practice can cumulatively have on watershed health. This tool can be used to guide residential construction projects in a manner that reduces the negative impacts on watersheds that can be associated with construction projects.
There is currently a gap in knowledge that must be addressed with respect to what the questionnaire respondents think happens to products that are disposed of in the storm water system. 24% of respondents answered that the storm water system leads to a water treatment facility and 12% did not know where the storm water system drained to. The storm water system on the North Shore drains directly into local watercourses which then drain into the ocean; none of the water in the storm water system is treated prior to discharging into local watercourses. This gap in knowledge must be addressed moving forward because the majority of the negative impacts seen on watersheds arise from pollutants that are released into the storm water system.
The rate of new construction is unprecedented on the North Shore; change and continued outreach and education is required to ensure that the appropriate techniques and practices are incorporated into construction projects to ensure that the current rate of construction does not come at the expense of the health of local watersheds.