Workshop Road Map - The Partnership

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Designing with Nature:Designing with Nature:A WebA Web--based Tool for based Tool for

Protecting WatershedsProtecting Watersheds

Courtenay Water Balance Model Workshop Courtenay Water Balance Model Workshop June 2004June 2004

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Workshop Road Map

Context & OverviewContext & OverviewWhy the Water Balance ModelWhy the Water Balance ModelHow to Use the ModelHow to Use the ModelApplication of Source ControlsApplication of Source ControlsScenario ModelingScenario ModelingRoundtable DiscussionRoundtable Discussion

Photo from: Smart Growth BC

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Setting the Scene

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Implications of Climate Change:

Rainfall Volume has Increased~20% Over the Past 20 Years

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www.waterbalance.cawww.waterbalance.ca

• Public Domain• Web-based• Interactive• Decision Support

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Inter-Governmental Partnership: Steering Committee and Development Team

Project TeamKSA Consultants LtdLanarc Consultants LtdCH2M HILL Canada Ltd

Focus GroupCity of ChilliwackCity of SurreyDistrict of North VancouverGreater Vancouver Regional District

Co-ChairsBC Ministry of Agriculture, Food & Fisheries

Environment Canada

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Inter-Governmental Partnership: History

Formed in 2002 as a result of a GVRD-sponsored project on the effectiveness of rainwater source control

Desire was to develop an internet-based, public-domain scenario modeling tool for rainwater management

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Inter-Governmental Partnership: Vision

To promote changes in land development practices so that:

The built environment will preserve and/or restore the natural water balance over timePerformance targets will be achieved for runoff volume and flow rate reduction

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Inter-Governmental Partnership: Key Partnerships

Real Estate Foundation of BC

Urban Development Institute

BC Water and Waste Association

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Inter-Governmental Partnership: Outreach & Continuing Education Program

Elected OfficialsLocal Government StaffDevelopment CommunityMunicipal Advisory CommitteesCommunity Stewardship GroupsProfessional Journals

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The Water Balance Model has been developed as an extension of the Guidebook methodology

http://wlapwww.gov.bc.ca/epd/epdpa/mpp/stormwater/stormwater.html

Key Messages

ADAPTGuiding Principles

PERFORMANCE TARGETS: Think Through the Details &

Design Sites to Function Naturally

COMMUNICATION: Understand the Big Picture &

Draw Pictures to Convey Strategies

WATER BALANCE MANAGEMENT:Think Outside the Pipe &

Make Better Land Use Decisions

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Marble Racing!

Workshop Road Map



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Integrated Rainwater Management Planning

From TRADITIONAL toDrainage SystemsReactive (Solve Problems)Engineer-DrivenProtect PropertyPipe and ConveyUnilateral DecisionsLocal Government OwnershipExtreme Storm Focus

INTEGRATED:EcosystemsProactive (Prevent Problems)Interdisciplinary Team-DrivenProtect Property and HabitatMimic Natural ProcessesConsensus-Based DecisionsPartnerships with OthersRainwater Integrated with Land Use

What Are What Are Your Expectations For Your Expectations For

This Workshop?This Workshop?

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Learning Outcomes: Participants will be able to….

A. WHY THE WATER BALANCE MODEL: Identify and express why we need to change the way we develop land and manage water at the site level

B. HOW TO USE THE MODEL: Use the WBM effectively to enter data and generate outputs

C. SOURCE CONTROL: Understand the capabilities of the WBM to evaluate rainwater source controls and how to achieve performance targets for volume reduction and rate control

D. SCENARIO MODELING: Apply judgment in using the WBM effectively to produce practical and achievable solutions in real-life situations

How We Will Achieve the Outcomes

• What Do You Know?• What Do You Wonder?• What Have You Learned?

Workshop is Also a Feedback Loop for

Refinements to the Model

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Guidebook Premise: Land Development and Guidebook Premise: Land Development and Watershed Protection can be CompatibleWatershed Protection can be Compatible

PolicyPolicy Level Development ObjectivesLevel Development Objectives

Site DesignSite Design Practices that achieve ObjectivesPractices that achieve Objectives

ScienceScience--BasedBased UnderstandingUnderstandingof Development Impactsof Development Impacts

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By 1969, we had put a man on the moon…

……. but we did not truly understand . but we did not truly understand how urban land use changes degrade streamshow urban land use changes degrade streams

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Balancing Objectives

What the public is demandingWhat the development community “can afford”What the environment can handle

East Clayton Photo from: James Taylor Chair in Landscape and LivEast Clayton Photo from: James Taylor Chair in Landscape and Liveable Environments.eable Environments.

“It’s My Back Yard”

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BOTTOM LINE CHALLENGEUnprecedented Growth

Georgia Basin / Puget Sound Population Trends (millions)

0123456789

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1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020

Key Message: Recognize that the Built and Key Message: Recognize that the Built and Natural Environments are Connected!!Natural Environments are Connected!!

PreserveFacilitate

Avoid

Design with

Nature to…

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By 1969, we had put a man on the moon…

Stable & Pristine(< 5% Impervious)

Start of Erosion(5% to 10%)

Visibly Impacted(> 20% Impervious)

But only in the past decade have we accepted that,as forest cover is replaced by an increasing percentage of hard surface,

stream quality decreases

UniverCity on Burnaby Mountain was the trigger for the Water Balance Methodology

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RAINFALL SPECTRUM

SITE

Infiltrate or Harvest Small Storms at the Source to Reduce

Total Runoff Volume

Provide Storage to Control the Rate of Runoff from Large Storms

WATERSHED

Ensure that the Downstream Systemcan Safely Convey

Extreme Storms

NEIGHBOURHOOD

LIGHTSHOWERS

HEAVY RAIN

EXTREME STORMS

KEEP RAIN ON SITE

DELAY THE RUNOFF

REDUCE FLOODING

ConventionalHydrologicModelingWater Balance

Modeling

INTEGRATED STRATEGY

75% 20% 5%Percentage of Annual Volume

Water Infiltrates & Moves Slowly Through Soil

The Water Balance Model, a The Water Balance Model, a Decision Support / Scenario Modeling ToolDecision Support / Scenario Modeling Tool

that is used to...that is used to...

Visualize the ‘how to’ details of source control implementationModel scenarios at the site, neighbourhood and watershed scales Make decisions through a scientifically defensible, interactive, and transparent process

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The Water Balance Model Simulates…

What Happens When Rain Falls on a SiteThe Wetting and Drying of Soil

Photo from: Wesbild

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Rainfall

Soil Saturation

Field Capacity

ET

Wilting Point

Runoff when soil is saturated

Infiltration rate is a function of soil moisture (limited by hydraulic conductivities)

Model tracks soil moisture fluctuation

Simple Soil Moisture Simulation (Module 3)

The hydrology engine is built around a continuous

Soil Moisture Simulation

The hydrology engine reflects the wisdom of an international Expert Panel, incorporates established soil science principles,

and provides a full accounting of the ‘water balance’

Evapotranspiration

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Performance Target #1 - Volume

This shows what level This shows what level of volume reduction of volume reduction can be achievedcan be achieved

Having an Internet-accessible tool:

Increases opportunities to promote widespread useResults in greater need to provide training in its use

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Next: Website Overview andDemonstration of Working Example

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Tiered Access ProtocolProject PartnerPaying SubscriberGeneral User

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How the Water Balance Model will be used to make better decisions:

Local Governments -when communicating with the publicPlanners and Engineers –when setting performance targetsDevelopers and their Consultants -when testing scenarios Environmental Agencies -when monitoring watershed health

Rainfall capture required on-lot in new subdivision because of downstream agricultural

concern over impact of increased volume

City of Courtenay Experience

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Having a Performance Target Having a Performance Target provides the starting point for provides the starting point for

Integrated SolutionsIntegrated Solutions

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1999 2010 2020 2030 2040 2050

0

10%

20%

30%

40%

50%

60%

70%

80%

Ann

ual R

ainf

all a

s R

unof

f (%

)

Year

The Big Picture:Current Trends

Ideal Condition

+ Climate Change

Impacts from Growth

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1999 2010 2020 2030 2040 2050

0

Ann

ual R

ainf

all a

s R

unof

f (%

)

Year

The Big Picture:Watershed Targets

Target is Specific to Target is Specific to each Watershed as each Watershed as determined in each determined in each

Watershed PlanWatershed Plan

Watershed Target (varies)

10%

20%

30%

40%

50%

60%

70%

80%

Think Outside the Pipe!

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Workshop Road Map



How Water Moves Through Soil

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City of Courtenay Soil Policy

Are You Comfortable Are You Comfortable Using the Internet?Using the Internet?

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Example Application to a Single Family Residential Site

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Key Details

Entire area is zoned RS1, each lot will have:roof leaders disconnected.roads serviced by rain gardenstopsoil depth such that runoff volume produced over a typical year is +/- 10%.

502.5 sq. m. (includes road right-of-way strip)40% rooftop16% impervious driveway44% lawn

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Existing Conditions

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Existing Conditions

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Scenario 1

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Scenario 1

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Scenario 2

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Scenario 2

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Scenario 2

So, Is Everyone Getting theSo, Is Everyone Getting theSame Output?Same Output?

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74% 71%

21% 23%

4 % 6%

0

20

40

60

80

100

Pe

rce

nt

of

To

tal

An

nR

ain

fall

Less than 50% ofMAR

50% of MAR to MAR Greater than MAR

Rainfall Event Size (mm)

Typical Volume Distribution of Annual Rainfall

South Coast (Burnaby Mountain) Okanagan (Kelowna Airport)

Note: Burnaby Mountain MAR* = 70 mm Kelowna MAR* = 20 mm (*24-hour rainfall)

20%Large Storms

75%Small Storms

5%Extreme Storms

RAINFALL SPECTRUM

SITE

Infiltrate or Harvest Small Storms at the Source to Reduce

Total Runoff Volume

Provide Storage to Control the Rate of Runoff from Large Storms

WATERSHED

Ensure that the Downstream Systemcan Safely Convey

Extreme Storms

NEIGHBOURHOOD

LIGHTSHOWERS

HEAVY RAIN

EXTREME STORMS

KEEP RAIN ON SITE

DELAY THE RUNOFF

REDUCE FLOODING

INTEGRATED STRATEGY

Typical Volume Distribution of Annual RainfallBritish Columbia South Coast and Okanagan

LIGHT HEAVY EXTREME

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Practical Site Level Solutionsare Typically Landscape-based

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Key Messages

‘Break the connection’Encourage ‘rain gardens’

Roof runoff discharged into a soakaway, with overflow connection to storm sewer

City of Courtenay Experience

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‘Break the Connection’with a Rain Garden

Simple Infiltration + Reservoir+ Overflow

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‘Designing with Nature’ means…

Create a Greener CommunityAchieve a Higher Level of Stream Protection

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Workshop Road Map



WATER BALANCE MODELEXAMPLE SITE APPLICATION

HOME DEPOT PROJECT – COURTENAY, BC

Presented byIan Whitehead, P. Eng.

McElhanney Consulting Services Ltd.

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BACKGROUND:Roughly 10 acre sitePre-development conditions:

Second growth coniferous forestGently sloping topographyThin layer of permeable surficial soilsVery little runoff during minor storm events

THE CHALLENGE:Typical big box land developer wants to develop 9.99 acres out of 10 available“Prototype” site design does not provide for preferred site source controls, such as extensive absorbent landscaping or increased soil depthsDownstream/down-gradient landowners concerned over both increased surface runoff and decreased groundwater flow

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THE SOLUTION:Attempt to mimic predevelopment runoff and recharge volumes on an annual basis via distribution of water across the site

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A) The Solution:Roof water collected and routed to a shallow aquifer recharge trench after passing through oil/grit interception chambersLocation of this trench sited to take advantage of best available native surface soils

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B) The Solution:In the event that this shallow aquifer recharge trench is overwhelmed, water level rises and spills into deep well exfiltration system

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C) The Solution:Parking lot water is collected and passed through an oil/grit interception chamber (9,000 imperial gallons). This water then flows into a combined shallow/deep aquifer recharge system, similar to that designed for the roof water

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Overflow diversion structure allows larger storms to bypass the oil/grit chamber but still be directed to the shallow/deep aquifer recharge system. This made the City very nervous as there is greater potential for groundwater contamination. However, in order that the average annual volume of site runoff was held at pre-development levels, the design was implemented.

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Could have elected to pre-treat the full 2 year post development runoff through a vastly larger oil/grit chamber. Potential would exist for some hydro carbon contamination. Therefore, we elected instead for a monitoring programme. Hydrogeologist had suggested the hydrocarbon contamination potential was not a major concern

Monitoring wells were installed to depth, roughly 10 metres away from the deep recharge wells

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D) The Solution:Bio-vegetated filtration sample c/w underlying free draining recharge media, was installed along the rear property line, receiving water from loading bay areas and access roads

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E) The Solution:Landscaped areas were maximized c/w free draining abortive “structure soil” extending beneath them to a greater plan area

F) The Solution:Monitoring of quantities and quality of runoff (required by City)

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THE RESULTS:Direct rapid peak runoff to the Brooklyn Creek basin was drastically reduced, as compared to typical commercial developmentAverage annual runoff is held to historic predevelopment valuesShallow and deep aquifer recharge is accommodatedHydrocarbon and grit capture prior to discharge to the receiving environment

OBSERVATION:Costs were in excess of $400,000.00 for wells/chambers and recharge facilitiesOwner not overly perturbed over these costsOwner recognized a social duty to protect the local environment (and understood their development was contingent upon applying Water Balance Model type site service control measures)

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What is Your HandsWhat is Your Hands--On On Experience with Experience with

‘‘Rainfall Capture SystemsRainfall Capture Systems’’at the Site Scale?at the Site Scale?

Standard Sump

Exfiltration Sump

700 square foot garage

No storm connection at rear of property

Condition of permit

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Rainwater Source Controls

Rain Gardens

Raingardens - also called Bioretention…

Absorbent Landscape

Rainwater Source Controls

Infiltration Swales

Permeable Pavement

Green Roof

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GVRD Source Control Posters

Basic Source Control TypesAbsorbent LandscapeInfiltration SwalesRain GardensPervious PavingGreen Roof

Absorbent Landscape

WBMuses:

Surface Condition Parameters

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AbsorbentLandscape

AbsorbentLandscape

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AbsorbentLandscape

Infiltration Swales

WBM uses:Vegetated Swale w/o UnderdrainVegetated Swale w/ UnderdrainInfiltration Trench

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Infiltration Swales

Infiltration Swales

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Infiltration Swales

RainGardens

WBM uses:Bioretention w/o UnderdrainBioretention w/ UnderdrainInfiltration PondBox Planter

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Simple Infiltration

Rain Garden A

Rain Garden B

Simple Infiltration + Reservoir

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Rain Garden C

Simple Infiltration + Reservoir+ Overflow

Rain Garden C2

Simple Infiltration + Reservoir+ Overflow + Controlled Outlet

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Controlled Outlet Detail

Pervious Paving

WBM does not currently model Pervious Paving

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Green Roof

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Workshop Road Map



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Applying the Water Balance Model at Different Scales

SiteSubdivisionNeighbourhood

SiteSite

Watershed Watershed HealthHealth

WBMWBMBuilding sizeBuilding size

Hard surfaceHard surface

LandscapingLandscaping

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SubdivisionSubdivision

Watershed Watershed HealthHealth

WBMWBMLot sizeLot size

Road DesignRoad DesignGreen spaceGreen spaceLandscapingLandscaping

WatershedWatershed

WBMWBMZoningZoning

Road DesignRoad Design

Green spaceGreen space

LandscapingLandscaping

‘‘FacilitiesFacilities’’Watershed Watershed

HealthHealth

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Application of the Water Balance Model in the Millard/Piercy Watershed

Purpose

• Minimize any increases in post development stormwater run-off (ensuring stream stability and salmon survival into the future)

• Provide options for alternative stormwater source controls to achieve the above objectives

• Provide baseline stream flows to establish pre-development stream flow characteristics

• Conduct post-development water level monitoring

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Zoning Map of Study Area

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West Courtenay Development Plan for Property

Study Site• Piercy Creek crosses 374 metres

of the site and has some riparian cover

• protection from 15-30 metre set-back

• sloping to flat 11.7 acres• zoned multi-residential (35

units/acre) and single family residential

• most of site has been previously cleared for agricultural and residential use

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WBM Parameter Assumptions

• Climate: East Clayton, Surrey

• Soils: 1 metre of siltyclay loam on level and 2 metres consolidated til on sloped portion

• Area: 11.7 acres; 47,350 sq. m.

Scenarios• Greenfield

– 20% forest, 80% grass

• Maximum Buildout– 15 metre set-back - 24% of

property– Multi-family - 76%

developed

• Optimized Buildout– 30 metre set-back – 48%– Multi-family – 52%

developed– Stormwater Management

Source Controls

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Greenfield Results

Results

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Workshop Road Map



What Did You Learn from What Did You Learn from the Process?the Process?

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The Water Balance Model is about a way of thinking

Long-Term Vision

Use of the model will become standard practice in British Columbia for land development decisions

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Over time, we can…

move from cumulative move from cumulative impactsimpactsto cumulative to cumulative benefitsbenefits

Workshop Road Map - The Partnership

Documents

Transcript of Workshop Road Map - The Partnership