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CWN Rainwater Management, June 20-21, 2007Richard Boase, P.Geo., CCEP
North Vancouver District
New DirectionsIn
Urban Watershed Health
Total lot area = 1901 sq. m.
19% Hard Surface
53% Tree Canopy
15% Landscaping
13% Building Footprint
Aging SFD stock >50 years
Lower land value
Different appreciation for space
New SFD stock < 10 years
Higher land value
Different appreciation for space
Total lot area = 1972 sq. m.
24% Building Footprint
25% Hard Surface 23% Tree Canopy
By Covenant
28% Landscaping
59% increase 88% increase
Did I read it all wrong?
Have I just not Gotten It Yet?
Tragically Hip, Road Apples, Bring It All Back,
Designing With Nature
Simple New Approaches
Urban hydrology
This deceptively simple equation embodies the basic element of change that we must embrace to achieve water
sustainability.
Water OUT = Water IN
OUT = INOUT = IN
IN IN = = (hydrology, weather, time, infrastructure,…) (hydrology, weather, time, infrastructure,…)
OUTOUT = Uses = Uses + F+ Fsafetysafety
= (= (UUessentialessential + U + Uexcessexcess) + F) + Fsafetysafety
where….where….
UUessentialessential = = (population, ecology, industry, (population, ecology, industry, time, …)time, …)
UUexcessexcess = = (wealth, society, technology…) (wealth, society, technology…)
Over Time, the safety factor has been shrinking:
74%71%
21% 23%
4 % 6%
0
2 0
4 0
6 0
8 0
1 0 0
Pe
rce
nt
of
To
tal
An
nu
al
Ra
infa
ll
L e s s th a n 5 0 % o fM A R
5 0 % o f M A R to M A R G re a te r th a n M A R
R a in fa ll E v e n t S iz e (m m )
T y p ic a l V o lu m e D is tr ib u tio n o f A n n u a l R a in fa l l
S o u th C o a s t (B u rn a b y M o u n ta in ) O k a n a g a n (K e lo w n a A irp o rt)
N ote : B urnab y M oun ta in M A R * = 7 0 m m K e low n a M A R * = 20 m m (*2 4 -h o u r ra in fa l l )
How Do We Do It?
Simple Science for a Complex World
Keep it SimpleThe Way We Develop Land
Determines How Water is Used and How Water Runs Off the Land
So, We Can Achieve Cumulative Benefits One Site at a Time
By Implementing ‘Design with Nature’ Infrastructure Practices & Regulation
Design with Nature at a GlanceDesign with Nature at a Glance
North Vancouver North Vancouver
Mackay Creek
1999 2010 2020 2030 2040 2050
0
2000000
4000000
6000000
8000000
10000000
12000000
An
nu
al R
un
off
Vo
lum
e (
m3
)
Year
MacKay Creek Watershed Retrofit ScenariosRunoff Volume Reduction
10% TargetCondition
Rainwater Reuse+ Infiltration
Green Roofs +Infiltration
Retrofit withInfiltration
Unmitigated Re-development
Climate Change
Single Family Rainwater Single Family Rainwater Mgt.Mgt.
Why is this an issue?Why is this an issue?
MacKay Creek Watershed Retrofit ScenariosReduction in frequency of erosive streamflow
0
10
20
30
40
50
60
70
80
90
100
1999 2010 2020 2030 2040 2050
Year
# o
f D
ays
per
yea
r th
at N
atu
ral
MA
F i
s ex
ceed
ed
Climate Change
Existing Runoff
Retrofit withInfiltration
Green Roofs +Infiltration
Rainwater Reuse +Infiltration
MacKay Creek Watershed Retrofit ScenariosPeak Flow Reduction
0
5000
10000
15000
20000
25000
1999 2010 2020 2030 2040 2050
Year
Pea
k R
un
off
Rat
e fr
om
5-y
r R
ain
fall
E
ven
t (L
ps)
Climate Change
Existing Runoff
Retrofit withInfiltration
Green Roofs +Infiltration
RainwaterReuse +Infiltration
How Do We Get ThereHow Do We Get There
Design with Nature at a GlanceDesign with Nature at a Glance
The Design Objective is to Infiltrate the first 30mm of Rainfall
Design with Nature Ideas
Design with Nature at a GlanceDesign with Nature at a Glance
Remove concrete replace with gravel
Rain barrel to lighten the footprint
Disconnect leader install splash pad
Inflow from new garage roof 5’ extensions
into drain rock dispersal field
18” perforated secondary sump 4’
deep
We have partnered with UBC to develop a We have partnered with UBC to develop a ‘Tree Canopy Module’ and implement an ‘Tree Canopy Module’ and implement an
applied research program to populate the applied research program to populate the model with datamodel with data
Dr. Markus Weiler
The Home Depot in Courtenay has a The Home Depot in Courtenay has a deep well injection system designed for deep well injection system designed for
the first 20mm of rainfallthe first 20mm of rainfall
Flood Overflows in Some Flood Overflows in Some Areas are Chronic BecauseAreas are Chronic Because
Too Much Runoff Volume Culvert Constrictions Cause Backwatering Pump Station is a Bottleneck
“Sustainable Subdivision Design is Part of the Flooding Solution”
The City of Courtenay was thefirst municipality to adopt a Minimum Soil Depth Policy
StandardsStandards
New residential standards
Pervious PavingPervious Paving
PoliciesPolicies
How Do We Get ThereHow Do We Get There
Design with Nature at a GlanceDesign with Nature at a Glance
We’re Already There (almost!)We’re Already There (almost!)
