On May 26, 2016, Michele Adams of Meliora Design and Tavis Dockwiller of Viridian Landscape Studio gave a presentation on green infrastructure during a workshop put together by New Jersey Future. The workshop was held for design professionals like engineers, landscape architects, and architects who design and/or review stormwater management systems in the Highlands of New Jersey.
4. Agenda
Welcome and Introductions
Green Infrastructure 101
Small Storm Volume Management
Why Green Infrastructure?
Policy, Highlands Stormwater, and the Market
Case Studies: Lessons Learned, Triple Bottom Line
and Myth Busting
Stormwater โCredit for GIโ
Break to Get Lunch
Lunch Discussion: Getting Past Barriers
Groups Report Out
Closing remarks
7. It wants to be a forest โ a tree is the best practice
99% of North America was covered by forest from the
Atlantic shoreline to the prairies of the Great Plains.
Today only fragments remain.
Pre-European settlement Present
http://earthobservatory.nasa.gov 14 October 2003
8. It wants to be a forest, butโฆ
43,480 square miles of blacktop = 5.5 the size of
New Jersey
10. How compacted is this soil?
Common Bulk Density Measurements
David B. Friedman, District Director -- Ocean County Soil Conservation District
Golf Courses, Parks, Athletic Fields
1.69 to 1.97g/cc
Undisturbed Lands:
Forests & Woodlands
1.03g/cc
CONCRETE
2.2g/cc
Residential
Neighborhoods
1.69 to 1.97g/cc
Bulk Density is defined as the weight of a unit volume of soil including its pore space (g/cc or grams/cubic centimeter). Water and air are
important components of soil and we must frame our soil concepts so that factors affecting water and air dynamics are included. Thus, we are
primarily interested in bulk density and pore space as they affect water and aeration status, and root penetration and development.
11. Despite decades of detention basins, we still have
flooding from development.
12.
13.
14.
15. โข Stream channel erosion
releases sediment
โข Pools and riffles are lost
โข Large storms cannot reach
floodplains
โข Less recharge = less
baseflow
โข Small streams can go dry
โข La
16. Two important observations:
96% of the annual rainfall volume is from storms 3 inches or less
Frequency: Most of the time, it rains 1 inch or less
Annual Percentages of Volume from Storms
17.
18. Section 438 of the Energy Independence and Security Act (Dec 2009)
Design, construct, and maintain stormwater
management practices that mimic natural hydrology
OR
Retain the 95th percentile Rainfall (around 1.7โ)
EPAโs Direction for Federal Facilities
We are seeing
variations of this
requirement in MS4
NPDES permits in
different states.
Municipal Separate
Storm Sewer System
19. Creating a Built Environment That Looks Like a Forest
26 in.
12 in.
12 in.
Evaporation
Infiltration
Runoff
Annual Rainfall
50 in.
20. How we BUILD and how we PLAN
Low Impact Development (LID)
or Green Infrastructure (GI)
โAllow natural infiltration to occur as close as possible to the
original area of rainfall. By engineering terrain, vegetation,
and soil features to perform this function, costly conveyance
systems can be avoided and the landscape can retain more of
its natural hydrologic function.โ
National Association of Home Builders
29. 22
โ
8โ
Tools for how we build:
โข Green roofs
โข Porous Pavements
โข Rain Gardens and Bioretention
โข Cisterns and Reuse
30. New Development: Residential
โข High Density Residential
โข 59 acres
โข 269 homes:
โข 146 Townhouses
โข 96 Quads
โข 17 Singles
โข Sinkholes and limestone
Can Water be Managed within the landscape?127 small measures, no detention basins.
31.
32.
33.
34.
35.
36. โข Quad homes without
basements have down
spouts connected to
infiltration beds beneath
impervious driveways.
โข Paths made of pervious
asphalt.
37. โข Stormwater beds beneath
driveways (standard
asphalt).
โข Overflow to swales along
streets
38.
39.
40.
41. โข Each home manages its own
runoff in a Rain Garden and
Stone Seepage Bed, located
in the right-of-way.
43. Site Analysis โ Existing features inventory
โข Existing Natural Features
โข Waterbodies
โข Floodplains
โข Riparian areas
โข Wetlands
โข Woodlands
โข Natural drainageways
โข Sinkholes
โข Steep slopes
โข Undisturbed area
โข Manmade Features / Historic
Land Use
โข Former Land Use (ag,
indust., etc.)
โข Abandoned utilities
โข Active utilities
โข Easements/Deed
Restrictions
47. Mixed Use Development at Valley Square Town Center
โข Porous Pavement
โข Subsurface Infiltration Beds
โข Bioswales
โข Bioretention Systems
โข Reduced pre-development peak rates by 67.5% for 1-100 year storms
โขDistributed infiltration design, mostly under porous pavement โ almost 10
acres (plus multiple rain gardens and vegetated infiltration beds)
โขTotal infiltration area โ 16 ac
54. Green Infrastructure for Areas with Combined Sewers
Greening Schoolyards for Education and
the Environment
55. โSchools make up 2% of all
impervious cover in the City,
but because they are highly
visible and associated with
education, making them critical
components in a green
stormwater infrastructure
program, they present a high
priority target for greening.
The goal is to retrofit up to half
of all schools in the City in the
coming 20 years. PWD plans to
support the retrofitting of up to
5 school campuses per year,
utilizing an array of stormwater
measures such as rain gardens,
green roofs, rain barrels and
cisterns.โ
Section 10 โข Recommended Plan Elements 10-23
City of
Philadelphia
Goal: Capture 1โ Rainfall
Volume
62. Viridian Landscape Studio โข SMP Architects โข Meliora Environmental Design
Design: Engage all users
Address age preferences
Society: Encourage collaboration and engage the
public
Develop Community Stewardship
Education: Design to Inform the Public
Teach Future Generations
Effect Transformation of Future Generations
69. Materials: Salvaged Stone
Granite from the Philadelphia Zoo
Marble and granite from Independence Mall
Sandstone Bridge Abutments from Schuylkill River Bridges
70.
71. Planted in the style of the Wissahickon
Forest
Photo: Wissahickon Creek near Philadelphia c.
1865 from the National Gallery of Art by John
Moran
Painting: View on the Wissahickon by James
Peale 1830
Observation
73. Planting
Experts and
Volunteers
โข TreeVitalize
PA Dept of Conservation and Natural Resources and The Pennsylvania
Horticultural Society
โข CSX Corporation
Used Greenfield as a kick-off to their monumental initiative โ the planting of
one tree for every mile of the 21,000 miles of its commercial track.
โข ACT (Alliance for Community Trees
โข Greenfield Home and School Association
โข Parents/ Children
โข Teacher
โข Design Team
โข Contractors
โข Philadelphia Water Department Office of Water Sheds
81. ๏ง Security: The smaller play lot is remote and not supervised, site is
dark and 47th St. can be quite deserted and unsafe.
๏ง Only blacktop/ no shade on the playground
๏ง Vehicular access to dumpsters is bad
๏ง Basketball court orientation is a problem
๏ง Lack of age-range in equipment
CONCERNS AND CHALLENGES
NEEDS & DESIRES โ BIG IDEAS
๏ง Replicate the feel of the โsecret gardenโ within the school
yard
๏ง Create a link between neighborhood garden center/ existing
garden beds/ curriculum
๏ง Create a โvibrant community nodeโ
๏ง Foster partnership with adjacent tennis facilities
๏ง Incorporate stormwater management projects that PWD
would like to help realize
98. 6-8โ S-1 Soil Layer: Planting Soil Surface layer. A layer consisting of material with a USDA Texture of
sand to loamy sand (S2) amended with organic matter. (must be tested to meet specs after compost is
approved and added)
24โ S-3 Soil Layer: Planting Soil Drainage Layer consisting of a 6 layer of material with a USDA
Texture of coarse sand
Stormwater Section
108. 6-8โ S-1 Soil Layer: Planting Soil Surface layer. A layer consisting of material with a USDA Texture of
sand to loamy sand (S2) amended with organic matter. (must be tested to meet specs after compost is
approved and added)
24โ S-3 Soil Layer: Planting Soil Drainage Layer consisting of a 6 layer of material with a USDA
Texture of coarse sand
Stormwater Section
109. A 4โ x 5โx 3โ tree pit
(typical in urban settings)
only provides 60 cubic
feet of soil!
A 10โ x 34โx3โ tree
trench provides the
1000+cf necessary for
successful tree
canopy cover
120 cf 500 cf 1000 cf
The success to street tree longevity is credited to the amount of soil volume available for
tree growth. A large tree, with a desired lifespan beyond 15 years (average life of a
downtown street tree is just 13 years) needs a minimum 500 โ 1200 cubic feet of soil
to reach a size that significantly contributes to a healthy community and ecosystem.
60cf
With thanks to the work of Jim Urban, Edward Gilman and Tim Craul
The Truth about Trees
112. Utility vault uncovered during
construction is located directly in
proposed plant bed
ADA ramp conflict with
snow plows
No option to reject based on root
issues as nursery stock is already
dug and covered without tree tagging
Expect the Unexpected
113. MAINTENANCE: Hire the Contractor via a
Separate Contract for at least 1 year
RAIN GARDEN
I. 1st Year Maintenance: Inspect 2x/year
(Late May to early July, and/or late
August/early September)
II. Inspection: 1x/year minimum (Late May to
early July, and/or late August/early
September)
III. Weeding: 3x/year minimum (Spring clean
up, summer maintenance, fall put to bed)
IV. Mulching: Minimum 1x/year (Spring)
V. Pruning: 1x year (Spring)
Stuff We Try to Require
115. How are the streets swept?
Who cleans out inlets?
Who repairs the road?
Are their codes that must change?
What are the tools for collaboration?
Who is vested in the big picture?
Were the Long-Term Caregivers vested in
THE PLAN?
You Asked for it !
118. A landscape architectโs fairy tale: our dream of happily every after
Vincent Van Gogh: The Road Menders
The Phillips Collection, Washington, DC. Acquired 1949
125. Trench Configurations and Sizes: Soil Volume
What happens underground / who maintains it?
Soil & Stormwater Infiltration Bed/ Root Zone
Planting Trench
Standard or Porous
Paving
Soil Cells or
Structural Soil
Porous Hardscape or
Groundcover
129. East Liberty Cathedral of Hope
Pittsburgh PA
โThe prior landscaping. . .looked postcard-perfect from a distance, but it was functionally unwelcoming up
close. Now we have broken that stone border with a series of benches and tables. As people wait for the bus
or simply pause on their way up and down Penn Avenue, they can sit on benches . . . Our building now has a
living, active link to the neighborhood, modeling a renewed and faithful spirit of hospitality.โ East Liberty
Presbyterian blog June 9, 2014
141. 143
Multiple Land Uses and Soil Types:
โข Weighted CN
Runoff Depth 10 year, 24 hr
Q = (P-0.2S)2
(P+0.8S)
- 10 =S = 1000
CN
= 78
Weighted CN and
Runoff Depth
B
C
Residential 36% imp
Residential 36% imp
75
83
22.8
15.2
38
1,710
1,261
38
2,791
2,791
5.0 in
78
10 year
78
1000
78
-10 = 2.82
Q = (5.0 - 0.2 (2.82))2
(5 + 0.8(2.82))
in
Initial Abstraction = 0.2S = 0.56 in
Volume Runoff = Q x Drainage Area
= 2.71 in x 38 acres = 373,817 ft2
= 2.71 in
142. 144
Time of Concentration
(tc) is the time it takes
for runoff to travel from
the most hydraulically
distant point in the
watershed to the outlet.
Time of Concentration (tc) affects the shape and peak of the hydrograph.
Small tc changes can sometimes have big qp impacts
SCS Dimensionless Unit Hydrograph
143. 145
โข Curve Number determines Runoff Depth (inches) and
Volume (ft3)
โข Hydrograph represents volume (flow over time)
โข Can we adjust CN to represent LID practices that
reduce volume?
โข Q is adjusted Runoff Depth managed by infiltration or
volume reduction practices
Adjusted CN McKuen
144. 146
Site Data
Total Drainage Area: 38 acres
Soil Types: 60% B (22.8 acres) 40% C (15.2 ac)
Land Use: Woods Good Condition (existing)
Proposed Land Use: ยฝ acre lots, impervious 36%
P = 10 year = 5.0 in
Existing Proposed
CN 61 78
Q runoff depth (in) 1.37 in 2.71 in
Volume (area x Q) 188,978 ft3 373,817 ft3
Ia (in) 1.27 in 0.56 in
Suppose we add SMPs that manage 93,800 ft3 of runoff? (thatโs equivalent to
about 1.89 in from 13.68 acres of impervious, or about 0.68 in over entire 38
acre site)
Example โ Residential Development
Letโs Add Volume Management
145. 147
Site Data
Total Drainage Area: 38 acres
Soil Types: 60% B (22.8 acres) 40% C (15.2 ac)
Land Use: Woods Good Condition (existing)
Proposed Land Use: ยฝ acre lots, impervious 36%
P = 10 year = 5.0 in
Existing Proposed
CN 61 78
Q runoff depth (in) 1.37 in 2.71 in
Volume (area x Q) 188,978 ft3 373,817 ft3
Ia (in) 1.27 in 0.56 in
93,800 ft3 managed / (38 acres x 43,560 ft/ac) x 1ft/12in =0.68 in
Q โ QE = Q ADJ = 2.71 in โ 0.68 in = 2.03 inches
Example โ Residential Development
Adjusted Q (runoff depth)
146. 148
Existing Proposed
CN 61 78
Q runoff depth (in) 1.37 in 2.71 in
Volume (area x Q) 188,978 ft3 373,817 ft3
Ia(in) 1.27 in 0.56 in
Q โ QE = Q ADJ = 2.71 in โ 0.68 in = 2.03 inches
Our new CN of 70 can be used to calculate peak discharge rate.
Example โ Residential Development
Calculate New CN
147. 149
โข Infiltration or Volume Management
distributed evenly over site
โข Each house has its own SMPs
โข Tc is not adjusted
โข Marylandโs goal is to replicate โwoods in good
conditionโ
โข Lookup Tables and Spreadsheet Tool
Important Assumptions
148. Maximum Extent Practicable is defined as maintaining
predevelopment site runoff to โwoods in good condition.โ
The resulting ESD volume typically ranges between 1.7
and 2.6 inches, depending on soils and development
intensity
Maryland ESD
150. Agenda
Lunch Discussion: Getting Past Barriers
1. Can GI benefit your clients, and what tools would help you?
2. What are the regulatory constraints to wider GI implementation?
3. What are the municipal constraints? Application Process?
4. Are there issues related to design standards and specifications?
5. are there issues related to property owner lack of demand/awareness?
6. Are design costs an issue?
7. Is permitting uncertainty an issue?
8. Are there construction considerations?
9. Are there maintenance concerns?
10. Is this a market opportunity for you?
151. Agenda
Lunch Exercise:
1. On your Colored Sticky Notes write:
Yellow: something that surprised you today
Purple: something you learned today
Blue: something you plan to do as a result of
the workshop
2. Stick the notes on the flip chart