The existing creek system below Highway 1 has many sections that are incapable of conveying large storm events safely. These events, while infrequent, would overpower the existing creek systems and potentially cause significant damage to existing properties and infrastructure. The proposed diversion system in the Five Creeks watershed will leave the creek system functioning as it does today, up to the two year storm event. For all storms larger than that, and for events up to the 200 year storm, there will be a splitting of the flows between the creek and the diversion. This will reduce downstream flows during large storms and lessen the chance of damage to life and property while leaving base flows necessary for environmental conservation in the creeks.
How does it work?
This project is a "stormwater diversion" to manage excess storm and rainwater. A large-diameter pipe with creek intake structures will collect excess flow from creeks during significant storm events. Like other stormwater systems, it will be installed underground and will run from above the Upper Levels Highway down to Burrard Inlet at the foot of 31st Street.
The pipe is designed to convey excess flow from creeks during significant rainfall events (i.e. events that only take place every two or more years) with the intake structures designed to split the excess flow so that some of the flow remains in the creeks and some of the excess flow is diverted into the storm diversion system. Water that would normally “jump the banks” and trigger overland flooding will instead be diverted into the new pipe.
Once completed, the system will serve five creek watersheds: Pipe, Westmount, Cave, Turner and Godman.
WHY IS IT NECESSARY?
One of Council's priorities is to plan for climate change and future weather events. Stormwater events are already increasing in frequency and intensity: this is projected to continue. Much of the current stormwater infrastructure, including culverts and creek channels, do not have capacity to convey the increasingly-significant flows.
Stormwater events are rainfall events that generate major flows and the impact of these flows is increased by our mountainous terrain. When water overflows the creeks, erosion and environmental impact can occur, and there is a risk of property damage due to flooding.
The new larger pipe with creek intake points will reduce the risk of flooding and property damage to 800 homes in Rodgers Creek, Westmount and Altamont neighbourhoods, while improving the health and condition of the creeks themselves.
I LIVE NEAR A CREEK AND HAVE NEVER EXPERIENCED FLOODING.
Our weather is changing and properties near creeks are at risk. It’s just a matter of time. The District is taking proactive action to prevent this from happening to residents.
In January 2005, heavy rain on the North Shore caused flooding in a number of places. Within the Five Creeks watershed, Pipe Creek overflowed and washed out Spencer Drive. Basements in the area were flooded. Read the news story here.
WHY HASN'T THE COMMUNITY BEEN CONSULTED?
This ISMP, along with others developed for District watersheds, was in response to provincial and regional requirements. We are required to complete ISMPs in watersheds of this size with developed lands.
The development of the District's Integrated Stormwater Management Plan (ISMP) included public consultation and information from 2008–2013.
- In August 2008 a letter was sent to residents along the creek corridors notifying them of work taking place to gather information for the ISMP.
- In December 2008 the project team made the decision to bring specific stakeholders to the table early, including Streamkeepers, Coho Society, North Shore Wetland Partners and relevant neighbourhood groups.
- In June 2009 a community consultation meeting on a draft ISMP was held at Sentinel High School. In addition to general advertising inviting the general public, specific stakeholders were invited directly.
- In 2010, at a stakeholder consultation meeting, with modifications introduced, the draft ISMP was finalized and posted to the District’s website.
- In 2013, there was further consultation with stakeholders and the report was finalized.
DID THE DISTRICT CONSIDER ALTERNATIVES TO THE DIVERSION PIPE PLAN?
Yes. Three potential solutions were considered to mitigate the impacts of the development and to resolve the existing issues downstream of Highway 1:
- Low Impact Development measures include wetlands, retention trenches and absorbent landscaping. These practices are being implemented in BPP’s developments and provide systems which help to remove contaminants from the surface runoff prior to the water re-entering the creek systems. Implementing these systems reduces the impacts of frequent rainfall events on the creeks but are not suitable for dealing with extreme rainfall events.
- Detention Ponds were considered but dismissed as not being a viable option. The five creeks being intercepted by this project, have a combined, existing catchment area of 615 hectares. The size of pond or tank required to detain the significant flow volumes generated from these existing watersheds is too large to be located on the steep terrain typical of these watersheds.
- Through the ISMP process, a peak stormwater diversion pipe with sufficient capacity to deal with both existing conditions and the impacts of new development was identified as being the best solution to: provide protection to the creeks in terms of minimizing stream bank erosion; minimize disruptive flow events which reduce the potential for the creek to provide beneficial environmental habitat; provide protection to adjacent properties from flood damage.
THE ISMP IS SEVERAL YEARS OLD. DOESN’T IT NEED TO BE REVIEWED OR UPDATED?
No. We are confident that the plan is up-to-date. Studies like the ISMP are developed with the expectation that implementation will take several years. This ISMP was finalized in May 2013 and the recommendation coming out of it for this diversion pipe is a complex infrastructure design and it has taken a couple of years to complete.
Since 2013, the District has conducted value-added engineering reviews to streamline the recommended solution whereby we reviewed opportunities that allowed us to reduce the impacts of construction.
HOW IS IT BEING PAID FOR?
The project is a significant piece of new infrastructure. Council priority is to identify sources of funds other than property taxes for municipal services and major projects.
The District has entered into an agreement with British Pacific Properties (BPP) to co-fund the project. The District will pay a fixed amount, up to a maximum of $6.25 million and BPP will assume the remaining project costs, including overseeing the project and assuming any unforeseen costs.
When complete, the District will assume ownership of the infrastructure, having avoided any financial risk to the taxpayer.
The District’s portion of costs will come from Development Cost Charges and from the capital reserve, which is funded by utility fees, not general taxation.
WHY WAS THE AGREEMENT DONE IN A CLOSED MEETING AND NOT DISCUSSED PUBLICLY?
Council made the decision in a closed meeting under Section 90 of the Community Charter, which applies to negotiations and related discussions respecting the proposed provision of a municipal service. Council announced at a later public meeting that the District had, in a closed meeting, approved a works and services agreement with BPP for the construction of the stormwater diversion project.
ISN’T THIS JUST BEING DONE TO ACCOMMODATE DEVELOPMENT ABOVE THE HIGHWAY AT THE EXPENSE OF HOMES BELOW THE HIGHWAY?
No. This project would be necessary even if there was no additional development above the highway, according to hydraulic analysis. Existing properties below the highway need the protection provided by the diversion pipe because these properties were often built inside current creek setbacks and, in some cases, on top of creeks. Many existing culverts are undersized and sections of channel are compromised by previously permitted and unpermitted encroachments within creek setbacks. All this creates risk of overland flooding.
IS BPP PAYING FOR THIS AS A REQUIREMENT OF THEIR DEVELOPMENT?
Council always searches for alternative sources of funding for infrastructure projects. Council entered into a partnership with British Pacific Properties (BPP) to build this important infrastructure that meets the needs of both parties to the benefit of District taxpayers. By working together and combining funds, we are able to build a better solution for all residents.
ARE THERE ENVIRONMENTAL IMPACTS TO THE CREEKS?
The project has the support of the West Vancouver Streamkeeper Society because of its environmental benefits.
Some members of our community are concerned about environmental impacts because the word "diversion" has been interpreted to mean that this project will either dam the creeks, take water away from the creeks or will destroy the health and ecology of the watershed. This is not true.
The creeks are important spawning habitat for cutthroat trout and salmon. High creek levels during a storm event can wash away the juvenile fish, their spawning habitat and the insects they rely on for food. There are existing creek diversions already in place that have demonstrated how the system protects the spawning environment.
DOES THE DISTRICT HAVE PERMISSION FROM THE PROVINCIAL AND FEDERAL GOVERNMENTS TO DO THIS WORK?
The construction of the intakes north of the highway requires permits, which is under provincial jurisdiction. Usually, these permits are for water licenses (to divert flows) and construction works instream to construct the intakes. Typically, diversion of water from creeks or bodies of water is related to profit and at an environmental or social cost (e.g. major hydro dam projects). However, this project’s water diversion is to protect properties and creek habitats.
The required approvals and water licensing have been in place prior to the start of construction in 2019.
WHAT ABOUT TREE LOSS DUE TO CONSTRUCTION?
The pipe is being installed on the District’s road and boulevard rights-of-way. Private encroachments such as vegetation and paving stones that have been placed by residents on District property must be removed to accommodate these public works.
CONSTRUCTION IMPACTS AND TRAFFIC
As with any construction project, the true impact will be the period of disruption during construction. This will include noise and traffic detours. The District is aware that residents will experience disruption; that is why we are phasing the work in segments.
As construction proceeds, residents will be impacted in their area for a couple of weeks, then work will move on to another segment. We are working to limit the amount of time that construction directly impacts each resident.
Traffic control persons will be on site to manage pedestrian, cyclist and vehicle safety through the construction zone.
Blasting may be required in some areas during construction due to topography. The exact extent won’t be known until excavation is underway. A pre-blasting survey will be done for any resident within 60 metres of a proposed blasting site. Any required blasting—in any section of the project—will be carefully considered and kept to a minimum.
HOW ARE SERVICES SUCH AS BUS ROUTES, GARBAGE PICKUP, SNOW REMOVAL AND EMERGENCY ACCESS IMPACTED?
There may be impacts to Blue Bus service during road restoration. Please check back for updates or sign up to receive updates by email.
Garbage & Recycling – There will be no impact to residents’ curbside collection schedule. The construction contractor will manage garbage and recycling pickup from the curbside when access is blocked.
Snow Removal – There will be no impact to snow removal. During a snow event, the District removes snow from streets on a priority basis and this will apply to the project area.
Emergency Access – Access for emergency responders and residents will be maintained by traffic control persons on-site during construction hours.