parking forest to asce
DESCRIPTION
Overview of two pilot projects of the Parking Forest, an assembly of common materials used to increase tree canopy and manage stormwater in parking lots without losing parking spaces.TRANSCRIPT
The Parking Forest:Linear Tree Wells Using Structural Soil
Sustainability for all the places between the buildings
503.334.8634www.greengirlpdx.com
[email protected] certified women business enterprise
Clean Water ServicesHealthy Streams Plan
Main Street Tigard
Effective Impervious Areawithin the Tualatin Basin UGB
Source: Clean Water Services Healthy Streams Plan
8%
Why do we need more trees in the urban fabric?
Water Balance BEFORE Development
25% base flow
(shallow infiltration)
50%
ev
apor
ation
0.5% runoff10
0% X
X” a
vera
gean
nual
rain
fall
25%
gro
undw
ater
(dee
p in
filtr
ation
)
Water Balance AFTER DevelopmentExample: EVERYWHERE
redu
ced
evap
orati
on
98% runoff
2%
evap
orati
on
Redu
ced
infil
trati
on
100%
ave
rage
annu
al ra
infa
llN
o infiltration
Water Balance Runoff Compared
0.5% runoff
98% runoff
Hydromodificationfrom a Watershed Perspective
• Additional volumes result in exceeding pre-developed rates that scour stream banks.
• Additional durations of flow impact habitat further.Please! Keep your
runoff volume to yourself!
What’s wrong with the trees we’ve got?
What’s wrong with the trees we’ve got?!
Photo Source: gratefulmommy.com
What about all those lovely tree-lined streets in Portland?
Trees Need Soil to Grow
Graph Source: USDA Forest Service Center for Urban Forest ResearchSlide courtesy of Todd Prager ,Todd Prager & Associates
Trees Need Soil to Grow
5 ft Crown40 cu ft Soil
20 ft Crown450 cu ft Soil
40 ft Crown2000+ cu ft Soil
Photos and observations courtesy of Todd Prager, Todd Prager & Associates
The Parking ForestAn Assembly of Common Materials
Structural Soil (dry)
The Parking ForestA Close Up
Pavement outside of
Parking Forest
Re-paved areaTree
Structural SoilAmended native
clayey soilUndisturbed native clayey soil
Crushed aggregate
Wheel stop
Two Sites
Watershed base map courtesy of Tualatin River Watershed Council
Redevelopment
Retrofit
THPRD Sunset Swim CenterRedevelopment with Pervious Concrete
THPRD Sunset Swim Center in PlanRedevelopment with Pervious Concrete
Structural SoilOur “Secret Weapon”
Source: Cornell University – CU Structural Soil - http://www.hort.cornell.edu
How do we know it works?Olympia Results 8 Years Later
Control Trees Planted in Compacted Native Soil
Trees Planted in Structural Soil
Assembly Procedure
Assembly Procedure
Assembly Procedure
Assembly Procedure
Assembly Procedure
Assembly Procedure
Assembly Procedure
Assembly Procedure
Why these materials?
• Structural soil• Amended Native Soil• Trees• Wheel stops• Crush rock (in landscape area)
Why these materials?Structural Soil
• Structural soil versus structural supports
A Second Way of Providing Tree Roots with Adequate Soil Volume Under
Pavement
. Photo courtesy of Jim Labbe
Another Way of Providing Tree Roots with Adequate Soil Volume Under Pavement
A Second Way of Providing Tree Roots with Adequate Soil Volume Under
Pavement
. Photo courtesy of Jim Labbe
A Second Way of Providing Tree Roots with Adequate Soil Volume Under
PavementJim Labbe in Nijmegen Netherlands. Photo courtesy of Jim Labbe
A Third Way of Providing Tree Roots with Adequate Soil Volume Under Pavement
Photo probably ripped off the Silva Cell website by Brian Wegener
Why these materials?
Proprietary mix versus mixed by contractor
Mixing Structural Soil
Photo Source: www.greelysand.com/cu-soil.html
Olympia Soil Recipe
4 cubic yards Crushed Rock ¾”-1¼” + 1 cubic yard Loam/organic topsoil + 1 pound Soil Binder “Stabilizer” + 46 gallons water__________Makes 4.6 cubic yards Structural Soil
Structural Soil Costs - Olympia
“The price to supply, deliver and install the structural soil material per cubic
yard ranged from $19 to $85 with an average bid of $42, the median price
was $39.50.
The city paid $24 per cubic yard for the structural soil material to the low
bidder.
This compare to a price quote we received for the supply of CU structural
soil at $65 per cubic yard plus delivery. The source was over an hour’s drive
away and delivery charges were $85 per hr with a truck and trailer hauling 22
cubic yard. The expected cost delivered was $72 per cubic yard.”
Excerpted from “Structural Soil Demonstration Project”
http://olympiawa.gov/~/media/Files/CPD/Urban%20Forestry/Forms/StructuralSoil.ash
x
Source: City of Olympia -Structural Soil Demonstration Project
Why these materials?Amended native soil
Amended native soil versus faster draining “3-way” mix
Why these materials?Trees
Trees versus only shrubs &/or groundcover:• Interception & evaporation• Evapotranspiration• Heat island effect
Why these materials?Wheel stops
Wheel stops versus curbs
Why these materials?Crushed rock
¼”x 10 crushed rock versus rounded rock or pavers
Siting Criteria
• Site is suitable for infiltration• Non-expansive soils• Soils should infiltrate at least 0.2 inches/hour*. Clay soils
are OK!
*Based on 2ft of structural soil, 25% void ratio, facility empty in 30 hours to be ready for the next Type IA storm
PCC Sylvania Lot 10Drainage Area
6133 sf
1919 sf
754 sf
615 sf
2815 sf
6103 sf
Parking Lot
Sidewalk
<50% Grass HSG C
Woods, Good HSG C
L Street
PCC Sylvania Lot 10in Plan
The Parking Forest Retrofitat PCC Sylvania Lot 10
Ignore the piles of dirt. They’re
gone.
Design Differences at PCC Sylvania Lot 10
Left most of the parking lot
unmodified/ impervious
Installed an impervious liner adjacent to impervious
asphalt
Installed an impervious liner adjacent to impervious
asphalt
Stakeholders chose a native
conifer
Water quality and quantity monitoring
Design Differences at PCC Sylvania Lot 10
Straight head-in parking
Donated “old school” solid bottom wheel
stops = not ideal
Just trees
Erosive forcesare an issue at PCC
Non-attentive forcesare an issue at PCC
Thank You! Partners Who Donated In-Kind
Services/Products
Alder Geotechnical Services
Siting Criteria at PCC
• Site is suitable for infiltration• Non-expansive soils• Soils should infiltrate at least 0.2 inches/hour*. Clay soils
are OK!
*Based on 2ft of structural soil, 25% void ratio, facility empty in 30 hours to be ready for the next Type IA storm
More Informationwww.parkingforest.org
• Partners• Benefits• Design Criteria• Specifications• Plans & Details• Monitoring & Adaptive Management• Photo Galleries• Additional Resources• Press• Frequently Asked Questions