A Sustainable Drainage
Strategy for the
South Campus
Neighbourhood
January 2005
This report was prepared for UBC Properties Trust by:
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Surrey, BC , Canada
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A Sustainable Drainage Strategy for the South Campus Neighbourhood
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Table of Contents
1.0
Introduction ................................................................................................................... 4
Environmental Issues............................................................................................................... 4
Policy Framework ................................................................................................................... 5
Planning Framework ............................................................................................................... 6
Regulatory Framework ............................................................................................................ 7
2.0
UBC Stormwater Management System.............................................................................. 8
UBC Catchment Areas ............................................................................................................ 8
Design Service Levels .............................................................................................................. 9
3.0
The South Campus Neighbourhood ............................................................................... 11
Watershed Structure ............................................................................................................. 11
South Campus Stormwater Management Objectives................................................................ 12
4.0
Stormwater Management Opportunities for South Campus .............................................. 13
Total Impervious Area (TIA) and Effective Impervious Area (EIA) ................................................ 13
Stormwater Conveyance........................................................................................................ 15
Stormwater Detention ........................................................................................................... 15
Stormwater Retention and Infiltration ...................................................................................... 16
Aquifer Recharge.................................................................................................................. 18
Stormwater Quality and Treatment ......................................................................................... 19
Maintenance........................................................................................................................ 21
5.0
Innovative Options Technical Discussion......................................................................... 22
Aquifer Recharge.................................................................................................................. 22
Stormwater Re-use................................................................................................................ 22
6.0
South Campus Stormwater Management Strategy............................................................ 24
Responsibilities ..................................................................................................................... 24
Effective Impervious Area ...................................................................................................... 24
Detention Strategy ................................................................................................................ 24
Community-Level Infrastructure .............................................................................................. 25
Neighbourhood Character, Placemaking & Identity ................................................................. 25
Building Design and the Private Realm ................................................................................... 26
Street Design........................................................................................................................ 26
The Public Realm.................................................................................................................. 27
Parking Lots ......................................................................................................................... 28
Habitat ................................................................................................................................ 28
Protection of Booming Ground Creek .................................................................................... 29
7.0
Conclusion .................................................................................................................. 30
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1.0 Introduction
UBC is developing plans for the South Campus Neighbourhood in a progressive manner, including
addressing sustainability objectives. The management of stormwater has been identified as an
important aspect of developing the community. The stormwater system for South Campus will
recognize the ecological integrity and health of the landscape, and must provide for safe conveyance
of large stormwater flows to protect people and property. Hydrogeologic and stormwater issues in
South Campus are complex and the opportunities for innovation are immense. Accordingly, this
document outlines key issues and strategies for managing stormwater in South Campus.
Environmental Issues
Area-specific conditions to the UBC Point Grey Campus have positively or negatively impacted the
management of stormwater management over the years. A list of conditions or instances follows.
Soils and the Point Grey Aquifer
UBC soils in general consist of approximately 0.5m of
organic topsoil, underlain by up to 30m of relatively
impermeable glacial till. Below this level is the Quadra Sand
unit, which incorporates the upper and lower aquifers that
underlie much of Point Grey. The aquifers are tilted towards
the west resulting in sub-surface water flowing west and
seeping from the cliff face in Pacific Spirit Park. The
“Preliminary Hydrogeotechnical Assessment” completed by
Golder Associates Ltd. in 1999 found that groundwater
contributed to cliff face erosion. Their study also pointed out
that the surficial cap of the peninsula was of limited
permeability and that much of the groundwater originated
east of UBC. A subsequent study by Piteau Associates
indicates that flows out of the upper aquifer could contribute
to cliff face erosion. Groundwater flows from the lower
aquifer would not likely result in further erosion since it is at
or below sea level.
Erosion of Peninsula Cliff Faces and Other Channels
UBC’s idyllic location at the terminus of the West Point Grey Peninsula has challenged site planners
and storm sewer designers for generations due to instances of cliff face erosion, channel erosion and
the potential loss of structures adjacent to the cliff face . Specific instances include:
ƒ In the 1930’s, a large washout occurred at the north end of East Mall. To preclude this from
re-occurring, a spiral drain was constructed in the late 1930’s in North Campus to prevent
stormwater from flowing over the face of the cliffs.
ƒ In the vicinity of the spiral drain, the less than 10-year storm capacity of the spiral drain was
exceeded in 1994, resulting in significant erosion of the adjacent cliff face. Remediation
measures have included bank stabilization and changes to effectively increase the ability of the
spiral drain to handle large storm events.
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Existing flows to Trail 7 outfall cannot be sustained due to erosion of the west cliff face by the
existing flow. Therefore the existing watercourse will need to be changed to accept the flows or
the flows need to be diverted to a new outfalls
At the 16th Avenue catchment outfall to Botanical Gardens Ditch, the existing outfall is
inadequate and has experienced extensive erosion over the years. Flow from this catchment
area should be largely diverted to a new outfall to minimize further erosion.
The existing outfall that drains the forested area west of Marine Drive should be reconstructed
due to erosion concerns.
Booming Ground Creek
The south and east portions of the campus drain via sewers and ditches along Marine Drive to the
lower reaches of Booming Ground Creek. The creek eventually flows through the portion of Pacific
Spirit Park south of the campus. Waterfalls and pools characterize the lower sections of the creek,
and fish populations have been reported in these lower portions. The creek channel is currently
experiencing problems with erosion and has sensitive habitat values in its lower reaches that must be
respected.
New Development and Impervious Area
The Point Grey campus of UBC has grown continuously since its inception in 1923. As more of the
campus is developed, there are fewer natural or vegetated areas to allow rainfall to dissipate into soils
naturally. Impervious surfaces such as building roofs and paved hard surfaces do not permit
rainwater to reach the soils underneath. Consequently, rainwater is concentrated resulting in higher
volumes of runoff flowing with greater velocity that can potentially lead to flooding, erosion and/or
destruction of property, habitat or life if not managed properly. The UBC Comprehensive Community
Plan proposes development in various areas of the campus. Accordingly, this will likely cause an
increase in peak and average storm flows depending on technologies employed. New storm
management systems will need to be constructed to service this new development. Most importantly,
new infrastructure for conveying flows resulting from major storm events to the Fraser River will be
required.
Stormwater Quality
Raincoast Applied Ecology conducted a monitoring program of the quality of stormwater at the spiral
drain, Booming Grounds Creek and Trail 7 outfalls. Contaminant levels and patterns were generally
consistent with other systems around the Lower Mainland. Concentrations of numerous metals
exceeded BC Water Quality guidelines at all outfalls. Oil, grease, and hydrocarbons were below
detection levels. The Stormwater Monitoring Program was completed in September 2002 and the
report submitted in February 2003. It is recommended that the program be continued to provide ongoing stormwater monitoring for the South Campus Development.
Policy Framework
Sustainability Policy Context
In 1997 the University adopted a Sustainable Development policy, which contains the following
provisions relevant to stormwater management:
ƒ UBC contributes to the protection of its environmental life support systems. This means
minimizing the pollution of air, water and soil.
ƒ UBC preserves and enhances the integrity of ecosystems at UBC through careful
management, and the development and implementation of remediation measures for
degraded sites as appropriate.
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Planning Framework
UBC Official Community Plan
UBC is envisioned to be a community that is planned, designed, constructed and inhabited with
respect for the natural, cultural, and historical land and patterns. Its landscape and activities are
envisioned to follow ecological cycles and parallel natural systems. With respect to physical
development and servicing, the broad ecology policy is to minimize impact on the natural
environment. The need to complete long term plans for servicing is recognized in the OCP.
Comprehensive Community Plan (CCP)
The long-term strategy for stormwater management detailed in the CCP includes upgrading the
system while improving stormwater quantity and quality control and environmental enhancement. The
CCP also specifies that UBC intends to have a long-term stormwater system that is innovative and
provides a full range of solutions to a conventional system’s deficiencies.
The long-term strategy to achieve the stormwater management goals detailed in the CCP includes the
following innovative concepts:
ƒ re-establishment and maintenance of ground flows and surface flows so as to provide
sustained base flow in natural watercourses, where applicable;
ƒ extensive point source and non-point source pollutant control upstream of environmentally
sensitive areas;
ƒ reduction of groundwater infiltration in areas where groundwater contributes to cliff instability
and erosion; and
ƒ recycling of use of rooftop rainwater collection and storage systems to augment water
demands for toilet flushing, laundry, and irrigation.
Cliff Erosion Mitigation Plan: The Cliff Erosion Mitigation Plan was prepared by the GVRD and UBC,
with considerable public and stakeholder involvement. The plan was adopted by the UBC Board of
Governors in September, 2003 and subsequently adopted by the GVRD Board of Directors in
February, 2004 as a framework for cliff erosion mitigation. The GVRD Board of Directors
subsequently directed GVRD Parks staff to append the plan to the Pacific Spirit Regional Park
Management Plan.
UBC Master Servicing Plan for Stormwater Management
In 1999, UBC commissioned Aplin & Martin Consultants Ltd to prepare overall strategies for updating
and replacing aging infrastructure on campus and for providing new infrastructure to serve planned
development on campus. The Plan also addressed inadequacies and shortcomings of the current
system. A comprehensive series of reports were finalized in 2001, including a volume entitled
“University of British Columbia Master Servicing Plan, Stormwater Management Technical Report”.
The Stormwater Management Plan was the result of detailed analysis and computer modelling, and
was guided by input from a committee with broad experience in infrastructure and sustainability issues.
Aplin and Martin Consultants Ltd. studied the effect that the proposed development outlined in the
Official Community Plan (OCP, 1997) and the Comprehensive Community Plan (CCP, 2000) would
have on the stormwater flows on campus.
The Master Servicing Plan for Stormwater Management was developed with the following drivers for
design of the stormwater management system:
ƒ Public Safety;
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Protection of the property and buildings (real estate);
Service levels, watershed;
Detention, aesthetics;
Environmental considerations, fish habitat, ground water recharge;
Biofiltration Systems / Water quality;
Operation and Maintenance;
Best management practices; and
Education
Regulatory Framework
Internally, a Landscape and Infrastructure permit is required for all new drainage works in the public
domain thereby ensuring compliance with the overarching objectives of the Planning Principles, UBC
Policy on Sustainability and OCP derived neighbourhood plans. Approval from UBC Utilities that
storm water proposals meet regulatory standards is a pre-requisite for a Landscape and Infrastructure
Permit to be issued by Campus and Community Planning. For any new outfalls, UBC expects to seek
approval from the GVRD, GVRD Parks Department, Dept. of Fisheries & Oceans and Fraser River
Estuary Management Program (FREMP). FREMP also coordinates other approvals from other
agencies that may have an interest such as the North Fraser Port Authority etc. UBC Utilities is
expected to lead the process for review and approval of the new outfall proposed for South Campus.
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2.0 UBC Stormwater Management System
The hydrological cycle describes the planet’s water system as it
moves from the oceans to the atmosphere and back to the sea. In
natural, undeveloped conditions, rainwater from the atmosphere is
either intercepted by vegetation, infiltrated into soils, stored in
depressions, or becomes overland flow.
Overland
flow
Interception
Stormwater management is a process used to determine the
method of conveyance of rainfall from its landing point to the
Infiltration
ocean. In UBC’s case, this is largely accomplished through a
Depression
storage
network of gravity inlets, pipes, overland flow routes and open
channels (ditches), to a number of outfalls into Georgia Strait and
the mouth of the Fraser River. Concentrated stormwater can cause flooding, erosion, and property
and environmental damage. Thus it is of paramount importance that stormwater flows and the design
of the management systems are sufficient and controlled so as to prevent these unwanted conditions.
Infiltration into the ground, and ultimately, percolation to the Point Grey aquifer, also accounts for
some management of stormwater, especially in relation to small rainfall events and those that occur in
the drier seasons.
UBC Catchment Areas
A catchment area is defined by high elevation ridges on the landscape. These ridges serve to direct
the flow of surface or ground water where it is concentrated at the low point in the elevation. There
are four primary stormwater catchment areas at UBC, as shown in Figure 1. Computer analysis was
undertaken of each area in 2001 for both existing and future conditions.
North Catchment Area
This area is substantially developed, with only small areas designated for infill development and some
areas for redevelopment. The net impact of future development is expected to be negligible. It is in
this catchment area that the less than 10-year storm capacity of the spiral drain was exceeded in
1994, resulting in significant erosion of the adjacent cliff face. Remedial measures to stabilize the cliff
in this area and provide some flooding protection have been implemented until another outfall is
established to handle the major flows in this area.
West (Trail 7) Catchment Area
The outfall for this catchment area is located south of the Botanical Gardens. The area was previously
developed with parking lots, which are largely being redeveloped as part of the Hawthorn Place
neighbourhood. Existing flows to Trail 7 outfall are connected to erosion of the cliffs by the existing
flow. Therefore the existing watercourse will need to be changed to accept the flows or the flows need
to be diverted to a new outfall.
Southwest (16th Avenue) Catchment Area
The 16th Avenue catchment outfalls to a ditch located at the Botanical Gardens. The existing outfall
has experienced extensive erosion over the years. This catchment area should be diverted to a new
outfall. The forested area west of Marine Drive will continue to flow to the existing outfall, which
should be reconstructed due to erosion concerns.
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South Catchment Area
The remainder of the stormwater from the south and east portions of the campus drains through
sewers and ditches to Booming Ground Creek. Booming Ground Creek eventually drains through
Pacific Spirit Park south of the campus. This creek channel is also experiencing problems with
erosion, and has sensitive habitat values in its lower reaches that must be respected.
Design Service Levels
During the development of the UBC Master Servicing Plan, much discussion focussed on determining
the appropriate levels of service for the stormwater management system. Design service levels balance
what is acceptable in terms of frequency of risk versus the costs involved to install the infrastructure
required to eliminate damage. For instance, when a storm sewer is designed for a minor storm event,
damage caused by ponding water and flooding basements should occur with less than the frequency
of the design storm, i.e. 5-year or 10-year. Stormwater infrastructure for a major storm is designed to
prevent flooding in areas where damage would be significant, such as erosion of cliff faces, loss of
buildings and infrastructure or the washout of a road. Not surprisingly, liability is an important factor
in determining the design service levels of stormwater infrastructure to provide greater protection to
life, property, and habitat.
It was determined through a committee process in 2001 that new storm sewers in the campus core
and development areas be designed to accommodate the 10-year (minor) storm peak flows, with
routing provided for the 100-year (major) storm, either in sewers or overland. Due to the significant
amount of existing sewers in the north campus, the 10-year storm flows would be allowed to
surcharge through sewers with minor or no surface flows. Because of the potential damage that could
result from uncontrolled flows between Marine Drive and the ocean, sewers, channels, and outfalls
west of Marine Drive should be designed to accommodate the 200-year storm. Also, since Marine Dr.
is under the jurisdiction of the Ministry of Transportation and Highways, the design service level for
infrastructure must be for the 200-year storm. Given that core campus areas could support surface
flows from a 100-year storm, inlet capacity is expected to be upgraded east of Marine Drive to
capture surface flows from the 200-year storm event.
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Figure 1: UBC Stormwater Catchment Areas
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3.0 The South Campus Neighbourhood
The South Campus neighbourhood falls within the South Catchment Area. The first phase of
development (the “Northeast Sub-Area”) of South Campus consists of approximately 39 hectares of
land that will be developed with predominantly residential uses, along with parks, roads, a school,
community centre and neighbourhood mixed-use commercial centre.
Watershed Structure
The South Campus watershed is characterized as follows:
Rainfall
Average annual rainfall is approximately 1200mm (47”) at the midpoint of South Campus. The land
generally slopes to the southwest, and historically surface water flowed in that direction and over the
cliffs.
Existing Stormwater Drains
South Campus has an existing storm sewer system to convey rainfall that is not absorbed into the
ground. The system conveys water in pipes to the south tip of the campus, then into an open channel
along the east side of SW Marine Drive eventually joining Booming Ground Creek. The creek then
flows through a culvert under the roadway to an outfall located in Pacific Spirit Park south of the
campus. As noted, the Booming Ground Creek channel west of Marine Drive is presently experiencing
problems with erosion.
Hydrogeology of the Site
South Campus soils consist typically of about 0.5m of organic topsoil, underlain by up to 30m of
relatively impermeable glacial till. Below this level is the Quadra Sand unit, which incorporates the
upper and lower aquifers that underlie much of Point Grey. The aquifer is somewhat tilted towards
the west, with the result being that sub-surface water flows west and seeps from the cliff face in Pacific
Spirit Park.
Booming Ground Creek Watershed
The majority of the South Campus area is not in the
same hydrological system as Booming Ground
Creek. However, a small portion in the northeast
area of South Campus drains to the east towards
Pacific Spirit Park. This area makes up a very small
portion of the total creek watershed. Stormwater
that is infiltrated into the soils in this area will likely
flow towards the creek but this contribution to base
flows is negligible since Booming Ground Creek
east of SW Marine Drive is an ephemeral creek that
is dry 4-6 months of the year.
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South Campus Stormwater Management Objectives
Overarching objectives sensitive to site conditions in South Campus were developed to be consistent
with the policy, planning and regulatory frameworks.
Stormwater Management Objectives:
ƒ Maximize landscaping vegetation and street trees in order to maximize interception of
rainwater;
ƒ Manage stormwater runoff from the 200-year storm so as to minimize flooding, erosion of
downstream cliffs and stream banks;
ƒ Maintain base flows in Booming Ground Creek so as to preserve the habitat value of the
lower reaches (west of Marine Dr.) of the creek;
ƒ Ensure that stormwater runoff originating from the neighbourhood is of a high quality and
implement point source and non-point source pollutant control upstream of environmentally
sensitive areas;
ƒ Treat stormwater as a resource for reuse to augment water demands for toilet flushing,
laundry, and irrigation when possible and appropriate. Stormwater should also be used in
research related work as an alternative to potable water where possible; and
ƒ Maximize South Campus placemaking opportunities and provide public amenity through the
management of stormwater.
Accordingly, stormwater infrastructure at the community and site level should be consistent with these
objectives.
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4.0 Stormwater Management Opportunities for South
Campus
A comprehensive stormwater management strategy for South Campus will be required to respond to
the particular conditions and context of the site and surrounding area in an appropriate and feasible
manner. Generally, a sustainable stormwater management strategy will seek to mimic natural
hydrologic processes and/or pre-development hydrological conditions.
Accordingly, general
strategies include retaining rainfall from small, frequent events, detaining larger events, and conveying
extreme events.
“Low Impact Development” (LID), “Best Management Practices” (BMP’s), and/or “Source controls”
provide direction on stormwater management techniques that minimize impact on the environment.
Many of these techniques focus on stormwater retention, infiltration, and potential re-use for irrigation.
A number of practical site-level solutions are outlined in this section, while more innovative and
experimental options are detailed in the next section in this report.
The following elements of the stormwater management system are discussed in more detail in the
following sections.
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Total Impervious Area and Effective Impervious Area;
Stormwater Conveyance;
Stormwater Detention;
Stormwater Retention and Infiltration;
Aquifer Recharge;
Stormwater Quality & Treatment;
Stormwater Re-use; and
Maintenance.
Total Impervious Area (TIA) and Effective Impervious Area (EIA)
Total Impervious area is the percentage of the basin covered by impenetrable, hard surfaces such as
rooftops, roads, sidewalks, driveways, and patios. Effective impervious area is the percentage of the
basin that is directly connected to the storm drainage system. If runoff from an impenetrable surface is
infiltrated into the ground or stored and reused, the surface is not considered “connected” and its
area can be subtracted from the TIA. In older, more established communities, the TIA equals the EIA.
In newer communities, the EIA is lower than the TIA. Setting an EIA target will have a considerable
impact on decision-making during community design and development.
Strategies for reducing both the EIA and TIA are generally termed source controls and include:
Soil Layer Thickness and Composition
The organic top layer of soil (topsoil) typically has a good capacity to hold water, and thicker layers of
soil will hold more water. When landscapes incorporate a 300mm (12”) layer of organic soil, this will
facilitate on-site retention of rainwater, and in turn will generate healthier lawns and gardens. To
optimize infiltration and plant health the soil layer should have a high organic content (10 to 25%).
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Vegetation
Vegetation intercepts rainfall, creates natural mulch and slows runoff. Wellrooted lawns and gardens, particularly those with native species of trees and
shrubs, will retain moisture better. Well-established plant material also
prevents soil erosion.
Roof Downspout Disconnection
Street trees intercept falling
Building rooftops comprise a significant portion of the impermeable surfaces rainwater.
in urban areas, and thus generate a large percentage of stormwater runoff
volume. Normal practice is to direct this water through drains around the
building perimeter into a sump and then into the storm sewer system in the
street. However, this water is typically clean, and is easy to keep separate
from other stormwater that may contain pollutants (such as from roads). For
lower density developments the use of splash pads can disperse roof water
into the adjacent landscape, or towards lawn basin inlets connected to rock
pits that encourage infiltration. Rainwater can also be captured in rain
barrels and other storage facilities disconnected from the storm sewer system. Disconnected downspout
Green or Vegetated Roofs
A vegetated building rooftop is emerging as a technology to reduce stormwater runoff form
development sites. Other benefits include reduced energy consumption for heating and cooling and
provision of private green space.1 The quantity of rainfall retained by green roofs varies, but for small
rainfall events, little or no runoff has been recorded with the majority of the precipitation returning to
the atmosphere through evapo-transpiration. For storms of greater intensity a green roof can delay or
reduce the runoff peak flow that would otherwise occur with conventional roof design. In Vancouver,
monitoring of the green roof installed on the Central Library has shown that runoff has been reduced
by 48% compared to a traditional flat roof.2
City Hall green roof,
Chicago, USA
Eco-roof, Portland, USA
Rooftop herb garden at the
Fairmont Waterfront Hotel,
Vancouver
Green roof on Vancouver Public
Library
1
Lipton, T., Murase, R.K. (2002). Water Gardens as Stormwater Infrastructure (Portland, Oregon), In R.L. France (Ed.),
Handbook of Water Sensitive Planning and Design, (pp. 125-153). New York, NY, USA: Lewis Publishers, p.137
2
Rogers, R. (2004) Putting Green Roofs to the Test. Business in Vancouver Magazine – Green Space, 11, 21-23.
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Permeable Pavements & Surfaces
A variety of alternative paving materials are now being produced to create permeable surfaces that
are aesthetically pleasing for driveways, sidewalks and patios. Permeable pavement solutions such as
permeable paving or brick pavers can be effective at the site level to generate infiltration and reduce
rainwater runoff. Providing a subsurface infiltration trench below the permeable paving can enhance
effectiveness on soils of low permeability. Other applications include “grasscrete” and reinforced
plastic or metal matting. Both use honeycomb structural meshing or brick pavers with soil gaps to
increase the stability of soils thus permitting vehicle driving and parking while permitting the
percolation of stormwater. UBC recently constructed a parking lot using permeable surfaces on the
south side of the intersection of West Mall and Agronomy Rd. In this instance, plastic cell mats are
used to reinforce soil and gravel in the driving aisles of a parking lot and growing grass structural soil
in plastic mat are used for parking bays (as seen in the City of Vancouver’s “Country Lane” project
along East 37th Ave).
Installing brick pavers. Brick pavers allow
stormwater to infiltrate the soils underneath.
System requires maintenance to remain
functional.
Road with porous pavement running along a
swale
Parking lot with a
combination of
pavement and
aggregate
Stormwater Conveyance
If stormwater is not infiltrated into soils or stored, runoff from surfaces such as rooftops, parking lots,
and sidewalks must be transported, or conveyed, to a receiving body. Conveyance facilities such as
sewers and ditches are used to manage extreme and rare storm events due to their destructive
potential. Sewer diameters are determined by extreme and rare events. The presence or absence of
other stormwater management facilities does not significantly affect the design of conveyance facilities.
Conveyance systems are typically designed to accommodate the 100-year or 200-year storm events.
However, where conveyance is used alone as a method for managing all storm events, water quality
and quantity issues are passed downstream. For instance, filtration and groundwater or aquifer
recharge cannot occur.
Stormwater Detention
Stormwater detention is a technique used to detain rainwater in temporary storage facilities so that it
enters the conveyance system at a controlled rate. This method typically reduces the impact caused by
peak flows from extreme storm events and also reduces sewer diameters. Detention systems are
usually employed where storm sewers discharge into creeks that are sensitive to erosion and/or that
have habitat value. Detention facilities typically do not have a significant impact on improving water
quality.
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Strategies for detaining stormwater include:
Detention Ponds
Detention ponds, in which the water level is allowed to rise during
large storm events, are typically used to detain stormwater on site.
A stormwater strategy that relies on effective detention typically
requires large tracts of land for ponds. Vancouver’s rainforest
climate will require very large and/or deep ponds that exhibit
significant fluctuations in water levels. As a result, these facilities
typically have steep banks and require safety fencing in densely
populated areas. In practice, detention basins are generally not
suitable for high-density residential developments and should be
located where they are not easily seen or where they can be Detention pond, Surrey, BC
concealed with landscaping. Lastly, the maintenance costs
associated with detention basins are higher than other stormwater
treatment devices.
Detention Vault
Detention vaults are underground storage/treatment facilities
constructed of reinforced concrete or corrugated pipe. Detention
vaults are suitable for peak flow control, flood control, and stream
bank erosion protection but are generally more expensive than
surface systems.
Detention vault, Tacoma, WA, USA
Stormwater Retention and Infiltration
Retention is a practice used to keep rainwater from entering the storm sewer system. Typical retention
techniques encourage water to infiltrate naturally into the soil or provide water storage in tanks, ponds
or on rooftops for later reuse. Retention is particularly suitable for managing small, frequently
occurring rainfall events. Small, frequent storms can account for up to 90% of the total rainfall events
each year. Using a retention strategy, these events are easily managed at the level of individual
building sites and within the public realm. Landscape-based solutions that maximize water retention
provide opportunities to contribute to a sustainable drainage strategy.
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The strategies for reducing the TIA & EIA discussed above also apply to this technique.
strategies for retaining and infiltrating stormwater include:
Other
Rain Gardens
A rain garden replaces a traditional landscape garden. Rain gardens are low-lying vegetated areas
engineered to accept rainwater from downspouts or gutters originating from impervious surfaces such
as sidewalks, rooftops and/or streets. Plants are chosen which will thrive in this wet environment and
infiltration eventually manages any excess water. This management technique can be adapted for
areas abutting natural forest areas or within sensitive watersheds. Captured rainfall is used as
supplemental irrigation and to allow natural dispersal and infiltration.
Roof drains into
vegetative filter,
Portland, USA
Courtyard
infiltration
Portland, USA
garden,
Rain Garden in parking lot,
Portland, USA
Outlet riser in rain
garden,
Portland,
USA
Infiltration Trenches and Rock Pits
Impermeable surfaces that generate rainwater runoff can be significantly offset at the site level with
effectively designed infiltration pits or trenches. These facilities store rainwater in the void space of
absorbent materials such as sand and gravel, to create a large contact area with the natural soil. In
areas with soils of low permeability, such as UBC, infiltration capacity can thus be increased. The
storage volume and contact area provided for infiltration are important factors in the design of
infiltration trenches and pits. The permeability of the underlying soil is also considered. Of course,
infiltration facilities will not be effective on top of underground parking or other such areas of minimal
soil depth. UBC has recently constructed a swale and groundwater infiltration chamber at the
intersection of West Mall with Agronomy. Stormwater from an asphalt parking lot surface drains from
into the new facility.
Swale, Princeton, USA
Infiltration trench with
overflow drain in swale,
Sydney, Australia
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Infiltration trench
draining street,
Seattle, USA
Street swale with rock pit,
Seattle, USA
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Infiltration Basins
Infiltration basins permit the artificial forcing of water into the underling soil for groundwater interflow
recharge, evapo-transpiration if sufficient vegetation exists and direct evaporation into the
atmosphere. A basin’s process of infiltration can serve to restore hydrological processes in the
landscape. Consequently, they are considered to be the most complete possible solution to the
environmental problems of urban stormwater.
Infiltration basin doubling as a
playground, Davis, California, USA
Mini-infiltration basin in a parking
median Orlando, Florida, USA
Infiltration basin in a school
playground, Owingen, Switzerland
Rain Barrels (Storage)
Rain barrels are an effective tool for storing rainwater from the rooftop so that it can
be used later to irrigate lawns and gardens. Rain barrels provide sustainability
benefits in two ways: they reduce stormwater runoff during wet periods and reduce
water consumption during dry periods. Overflows can be directed to splash pads,
lawn basins, rock pits and infiltration trenches.
Rain barrel
Water to Supplement Indoor Plumbing
Stormwater can be harvested to augment potable water supply for uses such as toilet flushing and
washing. Systems can be integrated into household plumbing with provision for back up water supply
in dryer periods. This technology is ideally suited for regions with water concerns such as the Gulf
Islands and the Okanagan region. Storage of rainwater on the roof or in tanks for reuse in nonpotable applications can be more effective if there is a daily use for the water. If the water is not
frequently used, the storage capacity can be quickly reached. If the container remains full, the system
would do very little to modulate peak storm runoff. This is discussed in more detail in Section 5.0.
Aquifer Recharge
Groundwater or aquifer recharge is of vital importance in sensitive watersheds. Groundwater flows
from aquifers, or base flows, supply water to creeks and rivers and sustain vegetation and wildlife.
The Point Grey aquifer, below the ground surface of the campus, provides an opportunity to direct
some stormwater to the aquifer. This opportunity is further discussed in the “Innovative Options
technical discussion” later in this report.
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Stormwater Quality and Treatment
Ensuring that stormwater is clean is a primary goal in a sustainable drainage strategy. UBC does not
have any combined sewers and thus stormwater is completely separate from sanitary sewers, which is
a significant benefit to water quality. Stormwater runoff from roof tops is typically of high quality while
runoff from roads and parking areas can contain oils, sediment, heavy metals, and other pollutants.
Concentrated pollutants fond in stormwater has the potential to negatively impact receiving bodies
and aquatic wildlife; stormwater quality control is intended to reduce or remove the pollutant threat.
Methods to control pollutants and their effectiveness are outlined in Table 1.
Table 1
Typical Stormwater Quality Control Methods
Sediment
MANAGEMENT
METHOD
Silts
Sand &
Gravel
Garbage
Heavy
Metals**
Oils
Street sweeping3
Good
Excellent
Excellent
Good
Poor
Catch Basins
Not Effective
Good
Good
Not Effective
Not Effective
Stormceptors
Good
Excellent
Good
Good
Excellent
Detention Ponds**
Good
Excellent
Good
Good
Not Effective
Biofiltration Swale
Good
Excellent
Poor
Good
Poor
Excellent
Excellent
Good
Excellent
Excellent
Biofiltration Pond**
*
Modern street sweeper with vacuum will remove 50 – 60% of silts and heavy metals. Street Sweeper with brushes
only is ineffective.
**
Solid metal particles only – dissolved pollutants would require extended storage times and possibly chemical
treatment.
With respect to runoff from roads and parking lots, of primary concern is the “first flush”. First flush
flow is the runoff from the first 15 to 30 minutes of initial rainfall after a dry spell and can contribute to
up to as much as 80% of the total pollutant load.4 An effective Best Management Practice would be
to treat a common rainfall event, say a 15 to 30 minute 1-year storm event. However, much remains
unknown about the local transportation of pollutants and the most effective BMP’s for treating
stormwater. Ongoing study of pollutant loads throughout a storm event may lead to alternate
conclusions as to what treatment facilities are to be provided
For stormwater treatment, some strategies are considered non-structural, such as sweeping, while
some are structural. Structural strategies are reviewed.
3
Advances in Modeling the Management of Stormwater Impacts, Volume 5, Edited by William James, Chapter 9 – Contrary
to Conventional Wisdom, Street Sweeping Can be an Effective BMP, Roger C. Sutherland and Seth L. Jelan.
4
Stormwater, Volume 2, Number 6, Rethinking First Flush, by Mary Catherine Hager.
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Strategies for treating stormwater include:
Stormceptor®
The Stormceptor® System is a stormwater separator that removes sediment and
hydrocarbons from urban runoff. A Stormceptor device captures stormwater
pollution at the source, effectively capturing high percentages of total
suspended solids (TSS) and total petroleum hydrocarbons (TPH). Stormceptors
are used in highly developed urbanized areas where land use is too restrictive
for conventional/natural devices.
Stormceptor installation
Swales
A swale is a linear depression or wide, shallow channel used to collect, infiltrate, treat, and, in some
instances, convey stormwater. A swale can be a grassed swale, a vegetated swale, a ‘wet’ swale
(swale with standing water), a ‘dry’ swale (swale underlain with a covered rock pit), or a bioswale.
Removal of contaminants occurs through filtration of suspended solids by plant stems, absorption into
soil particles and plants, soil infiltration, and biological processes.
Dry swale in parking
lot, Krems, Austria
Bioswale in parking lot median
Swale in Strathcona Park, Vancouver,
Canada
Wetlands / Constructed Wetlands: Water is stored and absorbed into soils and plants in wetlands.
Treatment occurs through plant absorption and soil filtration. Constructed wetlands are emerging as
a technology for managing and treating contaminated stormwater runoff in urban environments.
Constructed wetlands are not typically intended to replace all of the functions of natural wetlands.
They are mainly intended to minimize point source and non-point source pollution prior to its entry
into receiving waters. Other benefits associated with wetlands include wildlife habitat, education,
trails, boardwalks, and improved aesthetics.
Wetland & pond in
neighbourhood
Small wetland,
Germany
Ford Plant wetland,
Detroit, USA
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Wetland in Strathcona
Community Gardens, Vancouver
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Maintenance
The level of maintenance provided will directly affect the efficiency of the storm sewer system. Catch
basin sumps should be cleared of accumulated sediments, debris and refuge on an ongoing regular
basis. All inlets, (catch basins, lawn drains, and inlet structures) should be cleared of debris, lawn
matting, leaves, or any other obstructions that would limit inlet capacity. Manhole sumps should be
cleaned and any channel obstructions removed. If a major storm was to occur in these
circumstances, impacts of nuisance flooding and potential impact to downstream areas due to large
uncontrolled surface flows could be costly. Street and parking lots should be cleaned on a regular
basis. This will reduce the frequency of required storm sewer maintenance, extend the life of the storm
sewer infrastructure (through reduction of abrasive grit), and reduce the pollutant load being
transported by the storm sewers.
Similarly, grass and vegetation in swales, infiltration basins, and any other retention facilities will
require some maintenance as in any landscaped area. Storage containers may require regular
emptying if not used regularly to prevent any algae or bacteria build up.
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5.0 Innovative Options Technical Discussion
A few strategies for managing stormwater have arisen during the planning of South Campus. The
practices are either untested at UBC or are still in the monitoring phase.
Aquifer Recharge
The presence of the Point Grey aquifer approximately 30 metres below the ground surface provides
an opportunity to direct some stormwater to the aquifer. Water that soaks into the sub-soil will
eventually percolate down to the aquifer, and techniques such as shafts (wells) drilled down to the
aquifer could convey larger volumes of water. While it is true that water in the upper aquifer will
eventually move towards the face of the cliffs and contribute to erosion, dewatering wells at selected
locations could drain this water to the lower aquifer, which is below the level of the base of the cliffs.
The effect of conveying water to the aquifer would thus be mitigated.
A test well is being drilled in Hawthorn Place neighbourhood (Mid Campus), and a monitoring
program will be put in place to determine its effectiveness. If conveying water to the aquifer in this
way is an effective method of handling some of the storm water in South Campus, it may become a
significant component of the drainage strategy.
Stormwater Re-use
Water Collection & Storage
An analysis completed for the City of Vancouver’s “model” sustainable neighbourhood Southeast
False Creek completed by Keen Engineering found that adequate stormwater would be available
about 75% of the time during an average year to serve the total domestic water needs or all toilets in
buildings. Storage would be required to provide water 100% of the time. Storage facilities, depending
on the application, can be above ground, underground or on rooftops.
The study also indicates that collection facilities for rain storage containers such as rooftops would
conflict with a vegetated or green roof strategy. As discussed previously, green roofs reduce and slow
down stormwater runoff. Green roofs, when designed properly, can also provide a significant amount
of private open space for homeowners; a coveted amenity in dense urban communities. Ultimately,
building developers and/or homeowners would have to balance the trade offs for choosing a strategy
for managing stormwater if presented with these two choices. In terms of market demand, private
open space is likely to be more valuable and desirable than stormwater toilets.
Treatment
No specific regulations exist for treatment of stormwater for reuse in indoor plumbing. The Keen
Engineering study recommended the following methods for treating stormwater for reuse:
ƒ roof drain strainers to filter leaf and organic debris;
ƒ sediment chamber to remove fines;
ƒ disinfection system;
ƒ sand filtration system;
ƒ pumping system to convey treated water back up to the dedicated plumbing system;
ƒ overflow such that, once full, rainwater would bypass the tank and flow into the regular
stormwater piping system or to site irrigation systems; and
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potable-water connection so that during a prolonged drought the tank could be topped up
with water controlled by float switches;
Costs
Stormwater collection, storage and reuse infrastructure would generate no savings for developers and
homeowners with respect to related infrastructure for water supply since these services would have to
be provided anyway, and be sized to accommodate failure of storage/reuse systems. The Keen
Engineering study calculated a conservative estimate of at least $1,200 to $1,500 per suite would be
required to pay for the capital costs of a stormwater system in a typical 100-suite complex (in addition
to the incremental costs of fixtures, appliances, and maintenance). The study used a water rate that is
three times greater than current rates to calculate a payback period. The payback period was
estimated to be approximately 50 years.
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6.0 South Campus Stormwater Management Strategy
The following development, design and operational strategies will inform the development of the
South Campus neighbourhood.
Responsibilities
UBC Properties Trust will develop the stormwater infrastructure at the neighbourhood level. Once
implemented, ownership will pass to UBC Utilities. Costs for the operation and maintenance of the
stormwater system are expected to be the responsibility of the University Neighbourhood Association
(UNA). Accordingly, the UNA would collect a fee from residential developments to address this fiscal
requirement.
Developers will responsible for the implementation of stormwater management infrastructure at the
site-level. UBC’s Environmental Assessment Program (EAP) not only defines what infrastructure and
design practices are required but also provides information regarding practices that are encouraged.
The EAP will grant sustainability credits for designs that reduce the demand on the storm sewer system.
UBC is also in the process of developing an incentive program to encourage developer participation
in any design and development practices that would otherwise be financially onerous.
The following sections outline a “menu” of some of the options that can be utilized by developers and
UBC. The EAP will determine which techniques will be optional and which will be required.
Effective Impervious Area
As South Campus is largely vegetated with forest and grass, its TIA is currently very low. However, as
development proceeds, the TIA will increase and will reach its maximum at build out. South Campus
soils do not naturally drain well, as the surficial geology has a limited capacity for water infiltration.
Dense community design tends to lead to larger amounts of impervious area when compared to low
density communities. UBC will use BMPs, LIDs and Source Controls where possible to reduce the EIA.
Detention Strategy
UBC does not intend to have outfalls into creeks or other areas that are sensitive to flow volumes. For
instance, it is intended that flows into Booming Ground Creek will be maintained at base flow levels
only with large storm flows being directed to a new outfall in South Campus near the lookout on
Marine Drive. Since UBC is located very close to the ultimate receiving body – the ocean (and the
mouth of Fraser River), detention is not recommended as a significant component of UBC’s
stormwater management strategy. Preliminary calculations indicate that several acres would be
required for a detention pond (3m deep) to detain runoff from South Campus and could potentially
consume most of the available open space.
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Community-Level Infrastructure
A conveyance system to manage runoff from the 200 year will be required for the South Catchment
area to mitigate the risk of property damage and cliff erosion. A directionally-drilled sewer pipe has
been considered, but it appears that a drop-shaft sewer will be a superior solution to manage the flow
from this event.
Many of the site-specific options reviewed in this section are suitable for consideration at the
neighbourhood-level. Permeable surfaces and landscape-based retention techniques are particularly
applicable in the design of parks, greenways and other public realm areas.
Neighbourhood Character, Placemaking & Identity
Natural landscape systems and features can also serve to reinforce
local and/or regional identities in places that are being newly
developed. Older, more established cities provide us with clues
for how we can utilize natural processes to reinforce a regional or
local identity.
The building of pre-industrial cities required
vernacular responses to very local or regional landscape or
everyday life. On the hillside villas of Italy, the slopes of Istanbul or
the castles in Edinburgh, natural determinants of the built
environment such as cliffs, hills, depressions, ravines, creeks, Native sedges in a stormwater-friendly
wetlands, or densely forested areas served to provide distinguishing infiltration basin.
forms and features to the built environment that gave these places
a unique and endearing quality. Creeks and rivers flow in the very same ravines that they have for
millennia, hills and valleys are preserved in the landscape, and buildings built with shapes and form
that reflected landscape constraints. Whereas modern development has been able to exercise control
over the landscape and alter the natural processes that sustain it, these cities were constrained by
impassable, immovable or unavoidable obstacles.
The design of buildings, streets, and the public and private realms can contribute to a sense of
continuity and unique identity to the South Campus, the Point Grey
Peninsula, and/or UBC. With respect to stormwater management
systems, the use of surface management systems such as open
channels, creeks, swales, mini-wetlands, can serve to reinforce the
sense of the “Northwest Pacific rainforest” and the Point Grey
Peninsula location. Similarly, the use of indigenous species of trees,
shrubs, wildflowers, ferns, grasses and sedges contribute to a
cohesive and local identity.
Outdoor classroom
Benefits of Integrating Stormwater Infrastructure into Communities
Stormwater management features are increasingly capturing the
attention of residents and community planners for their ability to:
ƒ provide opportunities for education, interpretation and stewardship;
ƒ provide opportunities for wildlife habitat and preservation of environmentally sensitive areas
ƒ provide opportunities for human interaction with water through play and/or contemplation
ƒ reinforce local identity through revealing and celebrating native vegetation and landscape
features
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Building Design and the Private Realm
ƒ
Rooftops: Buildings rooftops are the first surface that falling
rainwater will encounter on a parcel. Pitched roofs are not well
suited for green roofs but some do exist. Flat roofs are ideally
suited for green roofs. In particular, large commercial or
multi-family residential buildings in South Campus are ideally
suited for green roofs. UBC recently installed 1015 sq. ft. of
vegetation on the new student residential building Vanier Place
/ Korea House. Roof tops can also act as a rainwater
collection area with water being conveyed to rain gardens or Green roof on a flat roof, Portland,
USA
disconnected roof leaders.
ƒ
Courtyards, Front and Back Yards & Interstitial Space: Private
yard spaces are ideal locations for infiltration trenches, rock
pits and/or rain gardens. In most instances, these stormwater
facilities replace conventional landscaping. Careful plant
selection or xeriscaping techniques5 will ensure a thriving yearround vegetated environment.
Street Design
ƒ
Brick-lined gutter drains to rain
garden
Green Streets: Some roadways in the neighbourhood are
envisioned as green streets. Green streets will not allow for
regular passage of cars. Essentially, green streets are multi-use
corridors designed for pedestrian and non-motorized
circulation, stormwater management, habitat, biodiversity and
recreation. Green streets and greenways form a ‘green
circulation network’ throughout the neighbourhood and
Stormwater–friendly street bulb out,
broader campus.
Portland, USA
ƒ
Street Trees: Not only do street trees increase the liveability of
the street environment, they also intercept falling rainwater and
reduce the risk of erosion caused by fast-moving volumes of
runoff. In the City of Salem, Oregon, a study found that all city
trees eliminated the need for $100 million USD (one-time
construction cost) of storm sewer infrastructure (i.e. if all trees
were cut down, $100 million would need to be invested in
sewers in order to manage the increased runoff caused by the
reduction of interception of rainwater).6
Curb cut-out provides runoff access
to infiltration trench, Portland, USA
5
Xeriscaping is climate-tuned landscaping that minimizes outdoor water use while maintaining soil integrity and building
aesthetics. This technique typically includes emphasis on native plantings, mulching, and no or limited drip/subsurface
irrigation and often relies on stormwater for irrigation purposes.
6
City of Salem's Natural Resources Section (2002). City of Salem Canopy Analysis. Retrieved from
http://www.cityofsalem.net/~naturalr/Trees/American_forests/Salem_final_report.htm#RESULTS Nov. 28, 2004.
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Driving and Parking Surface Treatment: Hard driving surfaces
are required for passing or parked vehicles. Permeable
paving, bricks pavers or aggregate or combinations of the
above can be used to increase the overall permeability of the
street. In Mid-Campus, UBC has used brick pavers for all onstreet parking stalls in order to increase stormwater infiltration
into soils despite the increased costs associated with this
choice. Simon Fraser University is using a similar approach Eco-Stone parking lot
for on-street parking areas.
ƒ
Swales, Linear Detention or Infiltration Basins and Rock Pits:
Many communities have successfully implemented these
stormwater management “technologies” to capture street runoff
caused by small frequent rain events with back up sewers or
conveyance channels for large and rare rain events. Most
street right of ways can accommodate a swale or linear basin
system in retrofit or new conditions. Since most of South Swale in median
Campus’ roads will be new, the opportunity exists for
determining an appropriate street right of way that will
accommodate a swale or more appropriate technology. Curbs
are optional for these technologies. Curb cut-outs have
successfully been implemented and tested in other jurisdictions.
ƒ
Medians: Medians can also be integrated into the South
Campus stormwater system. Swales, linear detention basins or
rock pits can be accommodated in most median spaces. Street
Rock pit accepts stormwater
trees can also be integrated into a stormwater-friendly median.
The Public Realm
ƒ
Public art or other creative uses: Public art pieces can be conceived, developed and
constructed to be an integral part of the stormwater management system. Cisterns,
stormwater fountains, and stormwater treatment facilities such as small ponds, mini-wetlands,
or earth filters can be designed in a creative manner. Residents and the South Campus
environment would be greatly enriched by intriguing and even interactive public art pieces that
serve dual purpose as stormwater infrastructure.
“Wind and Water Wheel” art piece
activates with flowing stormwater from
rooftop in school yard
“Beckoning Cistern” captures and
stores runoff form a rooftop in
downtown Seattle,
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Creeks, Rivers, Streams & Wetlands: The natural flow of
water can be the basis for form in community design.
Natural or existing water features such as creeks or streams
can be integrated into a community’s open space system. In
this way, a site’s hydrological balance can be maintained
and/or enhanced.
Parking Lots
Vegetated swale infiltrates rainwater,
Portland, OR
ƒ
Trees: Not only do trees increase the sun protection for
parked cars they can also intercept falling rainwater and
reduce the risk of erosion caused by fast-moving volumes of
runoff. Trees can also reduce the visual impact of these
community facilities.
ƒ
Interstitial Space: Interstitial spaces in parking lots such as
medians, landscaping buffers are ideal locations for
infiltration trenches, rock pits and/or rain gardens. In most
instances, these stormwater facilities replace conventional
landscaping.
ƒ
Swales, Linear Detention Basins and Rock Pits: Stormwater
runoff moving over the large impervious areas created by
parking lots can drain to these stormwater management Clockwise: Infiltration trench
“technologies”. Many successful projects have also used construction; rock pit; infiltration basin;
and swale with trees in parking lot.
large infiltration basins and/or mini-wetlands as well.
ƒ
Driving and Parking Surface Treatment: Hard driving
surfaces are required for parked vehicles. Permeable
paving, bricks pavers or aggregate or combinations of the
above can be used to increase the overall permeability of
the street. Driving lanes can be either surfaced with
permeable pavement or brick pavers and parking stalls can
be surfaced with pavers or decomposed granite.
Habitat
Grass & brick parking stalls
Stormwater facilities in South Campus will provide the opportunity to enhance the community with new
areas having habitat value. Since biofiltration swales, ponds and wetlands rely on natural processes
to purify stormwater, the natural vegetation creates potential new habitat for small animals, birds and
other creatures. Care must be taken, however, to ensure that nuisances such as mosquitoes and rats
are not encouraged. With respect to mosquitoes, general strategies include7:
ƒ
ensure that systems designed to empty following a storm do so within 72 hours;
7
Marco E. Metzger, Managing Mosquitoes in Stormwater Treatment Devices, Vector-Borne Disease Section, California
Department of Health Services, 2004. Retrieved from http://www.anrcatalog.ucdavis.edu/pdf/8125.pdf Nov. 26, 2004.
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encourage a robust predator population in areas that remain wet, and limit the spread of
emergent vegetation by establishing permanent deep-water zones of at least four to six feet;
and
animate the water surface in ponds or pools with a spray, wave or flow motion, especially
where permanent deep-water zones are not possible.
Common failures involve excessive growth and decay of emergent vegetation, which can overwhelm
predator populations and clog conveyance and aeration features; accumulation of silt, trash and
other debris, which can create small pools of standing water; and mechanical or electrical
malfunctions that can entirely shut down a system. However, since large detention facilities are not
envisioned for South Campus neighbourhood, it is not likely that mosquito habitat will be an issue.
Protection of Booming Ground Creek
As previously described, Booming Ground Creek has historically drained portions of the South
Campus area. The existing South Campus drainage system discharges into a ditch along the east
side of SW Marine Drive and eventually joins the Booming Ground Creek channel approximately 400
metres south of the UBC campus. This ditch and a culvert under the roadway are owned by the
Ministry of Transportation. The culvert discharges to Pacific Spirit Park west of the roadway and
carries water down a ravine that has two waterfall sections with small ponding areas below the falls.
These ponds and the sections of creek below the upper falls provide fish habitat.
For much of the year, during the drier months, stormwater from UBC campus and runoff from the SW
Marine Drive roadway provides most of the flow in Booming Ground Creek. The portion of Booming
Ground Creek upstream of SW Marine Drive in Pacific Spirit Park dries up during those times. The
habitat value of downstream sections of Booming Ground Creek is dependent upon having yearround water flow, and therefore it will be beneficial for UBC and the Ministry of Transportation to
continue to direct some stormwater to this channel. However, it would be detrimental to use this
channel for all stormwater from South Campus due to erosion concerns.
It will be critical to ensure that stormwater directed to Booming Ground Creek is of high quality and
low velocity. Provision of a biofiltration channel in South Campus and/or along the SW Marine Drive
right-of-way will ensure clean water. Only base flows would continue to be routed to the Creek, and
major flows would be routed to a new outfall. UBC will need to work with GVRD Parks, the Ministry of
Transportation and GVS&DD drainage authorities in designing the ecologically appropriate solution
to protecting the Booming Ground Creek channel. The Fraser River Estuary Management Plan
(FREMP) referral process will also be involved in review of any proposals affecting the foreshore of the
Fraser River. The existing outfalls to Trail 7 and 16th Avenue could be re-routed to a biofiltration
channel on the east side of SW Marine Drive, and continue on to the new south outfall. The limited
capacity of the existing SW Marine Drive ditch would accordingly require upgrading to accommodate
the diverted flows.
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7.0 Conclusion
This strategy outlines the complex hydrogeologic and stormwater issues and planning and regulatory
frameworks that guide development in UBC and the South Campus. The opportunities for innovation
are significant in South Campus, and this strategy provides clarification on the many stormwater
management opportunities appropriate to the site and its context. Finally, a menu of management
practices for development and design is provided so that new development can proceed according to
a greater vision of a sustainable neighbourhood. Ultimately the stormwater system for South Campus
will be required to provide for safe conveyance of large volumes of stormwater to protect people and
property and to maintain the ecological integrity and health of the landscape. The stormwater
management solutions offered in this strategy can help to reinforce a cohesive and unique identity for
UBC and South Campus. The combined result of these efforts will lead to nothing less than a symbol
of excellence and a memorable urban environment with significant public & ecosystem amenity.
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