Permeable

Paving by

Tom Barrett

Green Water Infrastructure, Inc.

www.ThinkGWI.com

Follow on Twitter @TomBarrett_GWI

(317) 674-3494Copyright © Tom Barrett, 2011

All Rights Reserved

The GREENEconomy

LOW IMPACT SITE DEVELOPMENT

How Much Rain Falls in Chicago?

January - 1.86"February - 1.58"March - 2.59"April - 3.28"May - 3.75"June - 4.08"July - 3.39"August - 3.38"September - 2.91" October - 2.65"November - 2.09"December - 1.88"Total 33.44"

Image of Rain Falling

Graph of Chicago Rain Fall

0

1.25

2.50

3.75

5.00

January February March April May June July August September October November December

Thirty Year Average Monthly Rain Fall Chicago (1971 - 2000)

Inch

es

Month

How Much Water Falls in Chicago?

January - 2,727 gallonsFebruary - 2,540March - 4,130April - 5,735May - 5,268June - 5,657July - 5,470August - 7,200September - 5,096 October - 4,223November - 4,691December - 3,787Total 56,525

Image of Rain Falling

2,500 sq. ft. Roof

How Much Water Falls in Chicago?

January - 11,880 gallonsFebruary - 11,065March - 17,990April - 24,982May - 22,945June - 24,642July - 23,828August - 31,363September - 22,199 October - 18,397November - 20,434December - 16,496Total 246,221

Image of Rain Falling

¼ Acre Residential Property

How Much Water Falls in Chicago?

January - 142,560 gallonsFebruary - 132,784March - 215,876April - 299,783May - 275,344June - 295,710July - 285,934August - 376,358September - 266,383 October - 220,764November - 245,203December - 197,954Total 2,954,654

Image of Rain Falling

3 Acre Commercial Property

How Much Water Falls in Chicago?

January - 475,195 gallonsFebruary - 442,610March - 719,581April - 999,267May - 917,805June - 985,690July - 953,105August - 1,254,515September - 887,936 October - 735,873November - 817,335December - 659,842Total 9,848,756

City Block (660’ x 660’ – 10 acres)

How Much Water is in Rain Event?¼” Rain ½” Rain 1” Rain

2,500 ft. sq. Roof

390 gallons 779 gallons 1,558 gallons

¼ Acre Residential Property

1,697 3,994 67,789

3 Acre Commercial Property

20,366 40,731 135,770

Chicago City Block

67,885 135,770 271,540

Landscape Ecology

Size the landscape to the 80% of the average rain water production.

– Roof Runoff

– Hardscape Runoff

Balancing rain water to landscape creates a functional landscape that utilizes the site’s water production.

Stormwater Mitigation

Stormwater Mitigation

Stormwater Mitigation

Stormwater Mitigation

Stormwater Mitigation

Stormwater Mitigation

– Collection runoff near the source

– Slow it down

– Soak it in

– Filter it

– Apply it to the landscape

– Create habitats

Peak Flow(1 Acre Site)

Grass Field Roof

1 Year Storm 1.4 cfs 4.3 cfs

2 Year Storm 2.1 cfs 5.4 cfs

10 Year Storm 4.3 cfs 8.0 cfs25 Year Storm 5.7 cfs 9.5 cfs

100 Year Storm 8.0 cfs 12.0 cfs

cfs – cubic feet per second

Peak Flow(1 Acre Site)

Grass Field Roof

1 Year Storm 10.5 gps 32.2 gps

2 Year Storm 15.7 gps 40.4 gps

10 Year Storm 32.2 gps 59.8 gps25 Year Storm 42.6 gps 71.1 gps

100 Year Storm 59.8 gps 89.8 gps

gps – gallons per second

Peak Flow(1 Acre Site)

Grass Field Roof

1 Year Storm 630 gpm 1,932 gpm

2 Year Storm 942 gpm 2,424 gpm

10 Year Storm 1,932 gpm 3,588 gpm25 Year Storm 2,556 gpm 4,266 gpm

100 Year Storm 3,588 gpm 5,388 gpm

gpm – gallons per minute

Peak Flow(2,500 sq. ft. Roof)

Grass Field Roof

1 Year Storm 0.08 cfs 0.25 cfs

2 Year Storm 0.12 cfs 0.31 cfs

10 Year Storm 0.25 cfs 0.46 cfs25 Year Storm 0.33 cfs 0.55 cfs

100 Year Storm 0.46 cfs 0.69 cfs

cfs – cubic feet per second

Peak Flow(2,500 sq. ft. Roof)

Grass Field Roof

1 Year Storm 0.60 gps 1.85 gps

2 Year Storm 0.90 gps 2.32 gps

10 Year Storm 1.85 gps 3.43 gps25 Year Storm 2.44 gps 4.08 gps

100 Year Storm 3.43 gps 5.15 gps

gps – gallons per second

Peak Flow(2,500 ft. sq. Roof)

Grass Field Roof

1 Year Storm 36 gpm 111 gpm

2 Year Storm 54 gpm 139 gpm

10 Year Storm 111 gpm 206 gpm25 Year Storm 147 gpm 245 gpm

100 Year Storm 206 gpm 309 gpm

gpm – gallons per minute

Stormwater Effects of Urbanization

0%

75%

150%

225%

300%

1 Year Storm2 Year Storm10 Year Storm25 Year Storm100 Year Storm

Change in Peak Runoff Flow Before and after Development

Detention and Volume Control

Stormwater Mitigation

Detention Underneath

Elimination of Detention

Ponds

How Much Water ?

Rainfall Surface Area Water Volume

1/4” 43,560 ft2 6,800 gallons

1/2” 43,560 ft2 13,600 gallons

1” 43,560 ft2 27,200 gallons

Base Storage Capacity

Base Depth Surface Area Void SpaceStorage

Capacity

12” 43,560 ft2 40% 130,300 gallons

18” 43,560 ft2 40% 195,500 gallons

24” 43,560 ft2 40% 260,700 gallons

Infiltration

Replenishes the

Groundwater Supply

Currently 50% of our

Drinking Water

In the Future 80% of

our Drinking Water

Soil Infiltration Rates

Soil Texture Infiltration (in/hour)

Sand 8.30”

Loamy Sand 2.41”

Sandy Loam 1.02”

Loam 0.52”

Silt Loam 0.27”

Sandy Clay Loam 0.17”

Clay Loam 0.09”

Silty Clay Loam 0.09”

Clay 0.06”

Improved Water Quality

Removes Suspended

Solids

Removes Phosphorus,

Nitrogen, and Metals

Removes Harmful

Pollutants - Oil

Water Polishing - the final

step in cleaning

Pollutant Removal

Pollutant Median Pollutant Removal*

Suspended Solids95%

Phosphorus70%

Nitrogen51%

Metals99%

*Infiltration Trenches & Porous Pavement

Using Porous Asphalt and CU-Structural Soil®Urban Horticulture InstituteCornell University Department of Horticulture134A Plant Science BuildingIthaca, NY 14853www.hort.cornell.edu/UHI

Roadside Traction

Less Water

Roadside Traction

Less Ice

Design Considerations

Rainfall Intensity

Rainfall Duration

Runoff Coefficient is

Zero

Underdrain for Soil

Infiltration Rates of less

than 1/2” per Hour

Release Rate

UNILOCK PERMEABLE INTERLOCKING CONCRETE PAVERWith various aesthetically pleasing colors and textures, creative choices are not compromised by function. Permeable Interlocking Concrete Pavers (PICPs) are the most durable of any porous pavement material. Unilock’s minimum 8,500 psi (57 MPa), high-strength, no-slump concrete allows water to infi ltrate between paver units instead of through the material. The joint sizes vary between paver options, ranging from 0.25” (6 mm) to 0.5” (13 mm), which meet the Americans with Disabilities Act specifi cations for permeable pavements, and allows a minimum of 100” (2,540 mm) per hour of surface infi ltration.

JOINT AGGREGATE – ASTM NO. 8As the initial fi ltering layer, the 0.25” (6 mm) crushed, angular, chip stone captures approximately 80 percent of debris in the fi rst 1” (25 mm) to 2” (51 mm). The secondary function of the joint aggregate is to increase the positive interlock between the paver units that is essential to the structural stability of the PICPs. The joint aggregate must always remain fi lled to the lip of the PICP units to reduce unnecessary clogging.

SETTING BED AGGREGATE – ASTM NO. 8Using the 0.25” (6 mm) crushed, angular, chip stone, instead of sand, provides a smooth leveling course for placing pavers and additional structural interlocking of the PICPs. Unlike sand, the setting bed aggregate allows for rapid water infi ltration with over 500” (12,700 mm) per hour through the 40 percent void-space. Sand must be avoided as a setting bed in a PICP application.

BASE AGGREGATE – ASTM NO. 57When subsoil conditions are conducive to supporting the ASTM No. 57 crushed, angular, open-graded base material without migration, it can be used without ASTM No. 2 subbase aggregate. Minimum thickness must be determined by suffi ciently supporting anticipated loads, as well as accommodating stormwater detention in the 40 percent void space of the material. The ASTM No. 57 base aggregate, with a minimum thickness of 4” (102 mm), serves as a transition material between the ASTM No. 8 setting bed and the ASTM No. 2 subbase aggregate. The infi ltration rate of the ASTM No. 57 is over 500” (12,700 mm) per hour.

SUBBASE AGGREGATE – ASTM NO. 2Subsoil conditions will dictate the necessity of this larger ASTM No. 2, crushed, angular, open-graded subbase aggregate thickness. Installation of such material will provide increased structural stability on sites with poor soil conditions. A minimum thickness of 8” (203 mm) is required for effective performance. Subbase aggregate thickness must be designed to suffi ciently support anticipated loads. As an added feature, the ASTM No. 2 subbase aggregate temporarily detains stormwater runoff in the 40 percent void-space of the material. The ASTM No. 2 also has an infi ltration rate of over 500” (12,700 mm) per hour.

SUBGRADEExisting soil materials will determine the performance capabilities of the PICP system. Pre-construction soil analysis, including percolation, California Bearing Ratio and penetrometer measurements (blow counts), are mandatory for proper design. Subsoils with less than 0.5” (13 mm) per hour of infi ltration may require underdrainage, scarifi cation and potentially, amendments. Subsoils with greater than 0.5” (13 mm) per hour are considered highly permeable. Subsoil compaction can cause a detrimental reduction in permeability and could be eliminated.

EDGE RESTRAINTPICP containment is vitally important to the success of interlocking properties. Lack or failure of an edge restraint will negatively impact the integrity of the pavement surface. For all vehicular PICP applications, an edge restraint, such as a concrete curb is required. For non-vehicular and pedestrian areas, a plastic edging is suffi cient when properly anchored into the subbase.

UNDERDRAINIn PICP systems, the underdrain pipe is based on several factors, such as the permeability of the subsoil, detention requirements, and stormwater release rate of the site. With highly permeable subsoils over 0.5” (13 mm) per hour, underdrain pipe could be eliminated. Underdrain pipe size is inconsequential, provided the fl ow rate is greater than the release rate.

GEOTEXTILE FABRICSubsoil characteristics will determine the need for a geotextile fabric. If such fabric is required, placement will occur between the subsoil and ASTM No. 57 base aggregate or ASTM No. 2 subbase aggregate only. Geotextile fabric is not required between aggregate material layers. The geotextile fabric type must be determined by soil conditions specifi c to each project. Geotextile fabrics should be considered for any soils where migration may occur.

1 2

3

5

7 8 9

6

4

1

3

4

5

6

7

8

2

9

Nine Components of a Highly Successful Permeable Pavement

Components of Permeable

Pavement

1) Pavement

2) Joint Aggregate

3) Setting Bed

Aggregate

4) Base Aggregate

5) Subbase

Aggregate

UNILOCK PERMEABLE INTERLOCKING CONCRETE PAVERWith various aesthetically pleasing colors and textures, creative choices are not compromised by function. Permeable Interlocking Concrete Pavers (PICPs) are the most durable of any porous pavement material. Unilock’s minimum 8,500 psi (57 MPa), high-strength, no-slump concrete allows water to infi ltrate between paver units instead of through the material. The joint sizes vary between paver options, ranging from 0.25” (6 mm) to 0.5” (13 mm), which meet the Americans with Disabilities Act specifi cations for permeable pavements, and allows a minimum of 100” (2,540 mm) per hour of surface infi ltration.

JOINT AGGREGATE – ASTM NO. 8As the initial fi ltering layer, the 0.25” (6 mm) crushed, angular, chip stone captures approximately 80 percent of debris in the fi rst 1” (25 mm) to 2” (51 mm). The secondary function of the joint aggregate is to increase the positive interlock between the paver units that is essential to the structural stability of the PICPs. The joint aggregate must always remain fi lled to the lip of the PICP units to reduce unnecessary clogging.

SETTING BED AGGREGATE – ASTM NO. 8Using the 0.25” (6 mm) crushed, angular, chip stone, instead of sand, provides a smooth leveling course for placing pavers and additional structural interlocking of the PICPs. Unlike sand, the setting bed aggregate allows for rapid water infi ltration with over 500” (12,700 mm) per hour through the 40 percent void-space. Sand must be avoided as a setting bed in a PICP application.

BASE AGGREGATE – ASTM NO. 57When subsoil conditions are conducive to supporting the ASTM No. 57 crushed, angular, open-graded base material without migration, it can be used without ASTM No. 2 subbase aggregate. Minimum thickness must be determined by suffi ciently supporting anticipated loads, as well as accommodating stormwater detention in the 40 percent void space of the material. The ASTM No. 57 base aggregate, with a minimum thickness of 4” (102 mm), serves as a transition material between the ASTM No. 8 setting bed and the ASTM No. 2 subbase aggregate. The infi ltration rate of the ASTM No. 57 is over 500” (12,700 mm) per hour.

SUBBASE AGGREGATE – ASTM NO. 2Subsoil conditions will dictate the necessity of this larger ASTM No. 2, crushed, angular, open-graded subbase aggregate thickness. Installation of such material will provide increased structural stability on sites with poor soil conditions. A minimum thickness of 8” (203 mm) is required for effective performance. Subbase aggregate thickness must be designed to suffi ciently support anticipated loads. As an added feature, the ASTM No. 2 subbase aggregate temporarily detains stormwater runoff in the 40 percent void-space of the material. The ASTM No. 2 also has an infi ltration rate of over 500” (12,700 mm) per hour.

SUBGRADEExisting soil materials will determine the performance capabilities of the PICP system. Pre-construction soil analysis, including percolation, California Bearing Ratio and penetrometer measurements (blow counts), are mandatory for proper design. Subsoils with less than 0.5” (13 mm) per hour of infi ltration may require underdrainage, scarifi cation and potentially, amendments. Subsoils with greater than 0.5” (13 mm) per hour are considered highly permeable. Subsoil compaction can cause a detrimental reduction in permeability and could be eliminated.

EDGE RESTRAINTPICP containment is vitally important to the success of interlocking properties. Lack or failure of an edge restraint will negatively impact the integrity of the pavement surface. For all vehicular PICP applications, an edge restraint, such as a concrete curb is required. For non-vehicular and pedestrian areas, a plastic edging is suffi cient when properly anchored into the subbase.

UNDERDRAINIn PICP systems, the underdrain pipe is based on several factors, such as the permeability of the subsoil, detention requirements, and stormwater release rate of the site. With highly permeable subsoils over 0.5” (13 mm) per hour, underdrain pipe could be eliminated. Underdrain pipe size is inconsequential, provided the fl ow rate is greater than the release rate.

GEOTEXTILE FABRICSubsoil characteristics will determine the need for a geotextile fabric. If such fabric is required, placement will occur between the subsoil and ASTM No. 57 base aggregate or ASTM No. 2 subbase aggregate only. Geotextile fabric is not required between aggregate material layers. The geotextile fabric type must be determined by soil conditions specifi c to each project. Geotextile fabrics should be considered for any soils where migration may occur.

1 2

3

5

7 8 9

6

4

1

3

4

5

6

7

8

2

9

Nine Components of a Highly Successful Permeable Pavement

Pavement

• Pavers

• Concrete

• Asphalt

• Single-sized

Aggregate

• Resin Bound

Joint Aggregate

• Pavers only

• Initial Filter

• 1/4” crushed,

angular, chip stone

• ASTM No. 8

Setting Bed Aggregate

• Used in all systems

• Smooth Leveling

Course

• No Sand

• ASTM No. 8

Base Aggregate

• Used when subsoil

conditions allow

• Minimum thickness

4”

• ASTM No. 57

Subbase Aggregate

• Not always

necessary

• Dictated by Subsoil

Conditions

• Used for additional

structural stability

• ASTM No. 2

Subgrade

• Existing Soil

• Percolation

• California Bearing

Ratio

• Penetrometer

Edge Restraint

• Vitally Important

• Concrete Curb for

Vehicular Traffic

• Plastic may be

Sufficient for Non-

vehicular areas.

Underdrain Pipe

• Subsoil Permeablity

• Detention

Requirements

• Release Rates

• Not Always

Necessary

Geotextile Fabric

• Based Upon Existing

Soil Characteristics

• Between Subsoil and

Base Aggregate

Components of Permeable

Pavement

1) Pavement

2) Joint Aggregate

3) Setting Bed

Aggregate

4) Base Aggregate

5) Subbase

Aggregate

UNILOCK PERMEABLE INTERLOCKING CONCRETE PAVERWith various aesthetically pleasing colors and textures, creative choices are not compromised by function. Permeable Interlocking Concrete Pavers (PICPs) are the most durable of any porous pavement material. Unilock’s minimum 8,500 psi (57 MPa), high-strength, no-slump concrete allows water to infi ltrate between paver units instead of through the material. The joint sizes vary between paver options, ranging from 0.25” (6 mm) to 0.5” (13 mm), which meet the Americans with Disabilities Act specifi cations for permeable pavements, and allows a minimum of 100” (2,540 mm) per hour of surface infi ltration.

JOINT AGGREGATE – ASTM NO. 8As the initial fi ltering layer, the 0.25” (6 mm) crushed, angular, chip stone captures approximately 80 percent of debris in the fi rst 1” (25 mm) to 2” (51 mm). The secondary function of the joint aggregate is to increase the positive interlock between the paver units that is essential to the structural stability of the PICPs. The joint aggregate must always remain fi lled to the lip of the PICP units to reduce unnecessary clogging.

SETTING BED AGGREGATE – ASTM NO. 8Using the 0.25” (6 mm) crushed, angular, chip stone, instead of sand, provides a smooth leveling course for placing pavers and additional structural interlocking of the PICPs. Unlike sand, the setting bed aggregate allows for rapid water infi ltration with over 500” (12,700 mm) per hour through the 40 percent void-space. Sand must be avoided as a setting bed in a PICP application.

BASE AGGREGATE – ASTM NO. 57When subsoil conditions are conducive to supporting the ASTM No. 57 crushed, angular, open-graded base material without migration, it can be used without ASTM No. 2 subbase aggregate. Minimum thickness must be determined by suffi ciently supporting anticipated loads, as well as accommodating stormwater detention in the 40 percent void space of the material. The ASTM No. 57 base aggregate, with a minimum thickness of 4” (102 mm), serves as a transition material between the ASTM No. 8 setting bed and the ASTM No. 2 subbase aggregate. The infi ltration rate of the ASTM No. 57 is over 500” (12,700 mm) per hour.

SUBBASE AGGREGATE – ASTM NO. 2Subsoil conditions will dictate the necessity of this larger ASTM No. 2, crushed, angular, open-graded subbase aggregate thickness. Installation of such material will provide increased structural stability on sites with poor soil conditions. A minimum thickness of 8” (203 mm) is required for effective performance. Subbase aggregate thickness must be designed to suffi ciently support anticipated loads. As an added feature, the ASTM No. 2 subbase aggregate temporarily detains stormwater runoff in the 40 percent void-space of the material. The ASTM No. 2 also has an infi ltration rate of over 500” (12,700 mm) per hour.

SUBGRADEExisting soil materials will determine the performance capabilities of the PICP system. Pre-construction soil analysis, including percolation, California Bearing Ratio and penetrometer measurements (blow counts), are mandatory for proper design. Subsoils with less than 0.5” (13 mm) per hour of infi ltration may require underdrainage, scarifi cation and potentially, amendments. Subsoils with greater than 0.5” (13 mm) per hour are considered highly permeable. Subsoil compaction can cause a detrimental reduction in permeability and could be eliminated.

EDGE RESTRAINTPICP containment is vitally important to the success of interlocking properties. Lack or failure of an edge restraint will negatively impact the integrity of the pavement surface. For all vehicular PICP applications, an edge restraint, such as a concrete curb is required. For non-vehicular and pedestrian areas, a plastic edging is suffi cient when properly anchored into the subbase.

UNDERDRAINIn PICP systems, the underdrain pipe is based on several factors, such as the permeability of the subsoil, detention requirements, and stormwater release rate of the site. With highly permeable subsoils over 0.5” (13 mm) per hour, underdrain pipe could be eliminated. Underdrain pipe size is inconsequential, provided the fl ow rate is greater than the release rate.

GEOTEXTILE FABRICSubsoil characteristics will determine the need for a geotextile fabric. If such fabric is required, placement will occur between the subsoil and ASTM No. 57 base aggregate or ASTM No. 2 subbase aggregate only. Geotextile fabric is not required between aggregate material layers. The geotextile fabric type must be determined by soil conditions specifi c to each project. Geotextile fabrics should be considered for any soils where migration may occur.

1 2

3

5

7 8 9

6

4

1

3

4

5

6

7

8

2

9

Nine Components of a Highly Successful Permeable Pavement

UNILOCK PERMEABLE INTERLOCKING CONCRETE PAVERWith various aesthetically pleasing colors and textures, creative choices are not compromised by function. Permeable Interlocking Concrete Pavers (PICPs) are the most durable of any porous pavement material. Unilock’s minimum 8,500 psi (57 MPa), high-strength, no-slump concrete allows water to infi ltrate between paver units instead of through the material. The joint sizes vary between paver options, ranging from 0.25” (6 mm) to 0.5” (13 mm), which meet the Americans with Disabilities Act specifi cations for permeable pavements, and allows a minimum of 100” (2,540 mm) per hour of surface infi ltration.

JOINT AGGREGATE – ASTM NO. 8As the initial fi ltering layer, the 0.25” (6 mm) crushed, angular, chip stone captures approximately 80 percent of debris in the fi rst 1” (25 mm) to 2” (51 mm). The secondary function of the joint aggregate is to increase the positive interlock between the paver units that is essential to the structural stability of the PICPs. The joint aggregate must always remain fi lled to the lip of the PICP units to reduce unnecessary clogging.

SETTING BED AGGREGATE – ASTM NO. 8Using the 0.25” (6 mm) crushed, angular, chip stone, instead of sand, provides a smooth leveling course for placing pavers and additional structural interlocking of the PICPs. Unlike sand, the setting bed aggregate allows for rapid water infi ltration with over 500” (12,700 mm) per hour through the 40 percent void-space. Sand must be avoided as a setting bed in a PICP application.

BASE AGGREGATE – ASTM NO. 57When subsoil conditions are conducive to supporting the ASTM No. 57 crushed, angular, open-graded base material without migration, it can be used without ASTM No. 2 subbase aggregate. Minimum thickness must be determined by suffi ciently supporting anticipated loads, as well as accommodating stormwater detention in the 40 percent void space of the material. The ASTM No. 57 base aggregate, with a minimum thickness of 4” (102 mm), serves as a transition material between the ASTM No. 8 setting bed and the ASTM No. 2 subbase aggregate. The infi ltration rate of the ASTM No. 57 is over 500” (12,700 mm) per hour.

SUBBASE AGGREGATE – ASTM NO. 2Subsoil conditions will dictate the necessity of this larger ASTM No. 2, crushed, angular, open-graded subbase aggregate thickness. Installation of such material will provide increased structural stability on sites with poor soil conditions. A minimum thickness of 8” (203 mm) is required for effective performance. Subbase aggregate thickness must be designed to suffi ciently support anticipated loads. As an added feature, the ASTM No. 2 subbase aggregate temporarily detains stormwater runoff in the 40 percent void-space of the material. The ASTM No. 2 also has an infi ltration rate of over 500” (12,700 mm) per hour.

SUBGRADEExisting soil materials will determine the performance capabilities of the PICP system. Pre-construction soil analysis, including percolation, California Bearing Ratio and penetrometer measurements (blow counts), are mandatory for proper design. Subsoils with less than 0.5” (13 mm) per hour of infi ltration may require underdrainage, scarifi cation and potentially, amendments. Subsoils with greater than 0.5” (13 mm) per hour are considered highly permeable. Subsoil compaction can cause a detrimental reduction in permeability and could be eliminated.

EDGE RESTRAINTPICP containment is vitally important to the success of interlocking properties. Lack or failure of an edge restraint will negatively impact the integrity of the pavement surface. For all vehicular PICP applications, an edge restraint, such as a concrete curb is required. For non-vehicular and pedestrian areas, a plastic edging is suffi cient when properly anchored into the subbase.

UNDERDRAINIn PICP systems, the underdrain pipe is based on several factors, such as the permeability of the subsoil, detention requirements, and stormwater release rate of the site. With highly permeable subsoils over 0.5” (13 mm) per hour, underdrain pipe could be eliminated. Underdrain pipe size is inconsequential, provided the fl ow rate is greater than the release rate.

GEOTEXTILE FABRICSubsoil characteristics will determine the need for a geotextile fabric. If such fabric is required, placement will occur between the subsoil and ASTM No. 57 base aggregate or ASTM No. 2 subbase aggregate only. Geotextile fabric is not required between aggregate material layers. The geotextile fabric type must be determined by soil conditions specifi c to each project. Geotextile fabrics should be considered for any soils where migration may occur.

1 2

3

5

7 8 9

6

4

1

3

4

5

6

7

8

2

9

Nine Components of a Highly Successful Permeable Pavement

Police StationAurora, Illinois

Buckingham FountainChicago, Illinois

POROUS PAVING • GREEN ROOFS • RAIN GARDENS • RAINWATER HARVESTINGNEW TOOLS FOR SUSTAINABLE SITE DEVELOPMENT

Green • Water • Infrastructure

Green • Water • Infrastructure

Green • Water • Infrastructure

Green • Water • Infrastructure

Green • Water • Infrastructure

Special Thanks

Thank You

P.O. BOX 124 WESTFIELD, INDIANA 46074

317-674-34949