Results of EPA Research on Permeable Pavement
Results of EPA Research on Permeable Pavement Michael Borst Thomas O’Connor U.S. Environmental Protection Agency Edison, NJ
NJ ASLA Annual Meeting February 22, 2016
Office of Research and Development National Risk Management Research Laboratory Water Supply and Water Resources Division Urban Watershed Management Branch
Green Infrastructure Research
In order to get measurements at the realworld scale, we need to be involved in the design stage.
2 Green Infrastructure Research
In 2009, EPA designed and built a 1-acre parking lot for facility staff and visitors that was surfaced with three types of permeable pavement.
EPA Facility Parking Lot Edison, New Jersey 3 Green Infrastructure Research
The construction recycled the demolished concrete Demolition of existing concrete surface
Clearing
Crushing and screening
4 Green Infrastructure Research
Excavating the storage volume.
The recycled concrete aggregate was placed over a geotextile to form the storage layer.
Geotextile placed on bottom and sides
AASHTO No 2 sized RCA Added from North to South 20-ton Non-vibratory compaction 5 Green Infrastructure Research
Overall, construction took about a year. November 26, 2008
February 26,2009
March 25, 2009
June 1, 2009
August 5, 2009
6 October 6, 2009
October 8, 2009
October 28, 2009
The design incorporated water quality and hydrologic monitoring capabilities.
7
PICP
PC
PA
4
4
4
3
3
3
2
2
2
1
1
1
Interlocking concrete pavers
Pervious concrete
Porous asphalt
Buried distribution pipes
Tree islands
Hot mix asphalt
Buried well/piezometers
Collection tanks
Rain gardens
Buried WCRs Green Infrastructure Research
Interlocking concrete paver installation took a little more than a week.
8
EPHenry EcoPavers
East Penn Pavement CompanyGreen Infrastructure Research
Porous concrete pour took two days followed by a week of covered cure time
9
Weldon Concrete
Nova Crete, Inc.
Green Infrastructure Research
Placing the porous asphalt took two days
10
Stavola, Inc.
Stavola, Inc.
Green Infrastructure Research
Vertical cross sections of permeable sections varied slightly from material to material.
Concrete Pavers (3.125 in.)
Pervious Concrete (6 in.)
Porous Asphalt (3 in.)
AASHTO No. 8 (2 in.) AASHTO No. 57 (4 in.) AASHTO No. 2 RCA (depth varies) EPDM Membrane
AASHTO No. 2 RCA (depth varies)
AASHTO No. 2 RCA (depth varies)
EPDM Membrane
EPDM Membrane
Existing Subgrade
Existing Subgrade
Existing Subgrade
11 Green Infrastructure Research
Post excavation testing showed large infiltration rates for the underlying soil. Underlying Soil Infiltration Rate (in/hr)
60 50 40 30 20 10 0 12
ICP PICP
North
PC
PA
South
Green Infrastructure Research
Four equally-sized and spaced lined sections collect infiltrating water from each monitored permeable surface with the balance infiltrating to the underlying soil.
13 Green Infrastructure Research
Infiltrate drains from the lined sections to 1,500gallon tanks on the east side of the parking lot where it can be sampled.
14 Green Infrastructure Research
The tanks are designed to collect a 1.5-inch rain event before bypassing.
15 Green Infrastructure Research
Tanks are cleaned before each event.
16 Green Infrastructure Research
Collection tanks are homogenized with a centrifugal pump and sampled while particles are still in suspension.
17 Green Infrastructure Research
Samples of asphalt runoff are collected at the southern end of the parking lot to serve as a control for comparison to infiltrate.
18 Green Infrastructure Research
Rain water is sampled to document stressors from atmospheric deposition.
19 Green Infrastructure Research
SOME WATER QUALITY RESULTS
20 Green Infrastructure Research
Calcium chloride (with no sand) and a rubber edged plow blade were used to manage snow and ice.
21 Green Infrastructure Research
22
10,000
1,600 1,400 Acute (860 mg/L)
1,000
Chronic (230 mg/L) 100
1,200 1,000 800 600
10
MDL (5 mg/L)
400 200
1
PICP
Cumulative Depth (mm)
LS Mean Chloride Conc. (mg/L)
After winter salt application, chloride concentration decreases throughout the remainder of the year.
0
PC
PA
Snow (by season)
Rain (since previous snow event)
Bars represent 95% confidence intervals; snowfall data from NJ State Climatologist.
Green Infrastructure Research
All permeable surfaces reduced Suspended Solids Concentration (SSC) to different degrees. 175
Mean SSC (mg/L)
150 125 103.0
100
Date Range: 1/26/2010 – 6/4/2013 Events sampled: 42 (PICP, PC, and PA) 28 (Runoff)
75 50
52.7 mg/l
25 0 23
21.3 7.6
PICP
PC
PA
Runoff
Mean Mean±0.95 Conf. Interval Note: NSQD TSS commercial median 98 mg/L Green Infrastructure Research
Acidic rainfall is buffered by all pavement surfaces, and PA exfiltrate is surprisingly high. 12 11
10.8
Mean pH
10 9
8.8
9.1
8 7.3
7 6
5.5
5 24
PICP
PC
PA
Runoff
Rain
Date Range: 1/26/2010 – 6/4/2013 Events sampled: 42 (PICP, PC, and PA) 34 (Runoff) 36 (Rain) Mean Mean±0.95 Conf. Interval NSQD commercial 7.4 (n=527) Green Infrastructure Research
TN concentrations in PICP, PC, and Runoff were not significantly different, but all three were significantly less than PA. Average EMC (mg/L)
1.2
A
1.0 B
0.8
B
B
A
PC
RO
RAIN
PA
C
BB
0.6 C
0.4
A A CC
B
AA
D A
0.2 DC
B C
C
BD
0.0 NH3 25
PICP
NO2
NO3
TON
TN
Date Range: 10/28/2010 – 9/7/2011 Events sampled: 13 (PICP, PC, and PA) 12 (Runoff and Rain)
Stressor Green Infrastructure Research
Total phosphate concentrations in PICP and PC were significantly larger than Runoff, and all were significantly larger than PA. Average EMC (mg/L)
0.25 0.20 0.15
A
A
PC
RO
RAIN
PA
A
AB
0.10
B
B
C
C
0.05 D
D
T-PO4
F-PO4
0.00 26
PICP
Date Range: 10/28/2010 – 9/7/2011 Events sampled: 13 (PICP, PC, and PA) 12 (Runoff and Rain)
Stressor Green Infrastructure Research
27
Total Zinc
PICP PC
PA
RO Rain
Total Zinc Concentration (mg/L) log -scale
Concentration (mg/L) log -scale
Total Zinc does not vary by surface and the concentration was never larger than the GEL for any surface.
Exceedance Probability
Infiltrate sample concentrations did not differ from rainwater or runoff sample concentrations Green Infrastructure Research
28
Total Copper
PICP PC
PA
RO Rain
Concentration (mg/L) log -scale
Concentration (mg/L) log -scale
The concentration of total copper in the infiltrate from the PICP is larger than the infiltrate concentration from PA or PC, but none exceeded the GEL. Total Copper
Exceedance Probability Green Infrastructure Research
Total Arsenic
PICP PC
PA
RO Rain
Total Arsenic Concentration (mg/L) log -scale
Concentration (mg/L) log -scale
Total Arsenic does not vary by surface, but the concentration exceeded the GEL for some samples from all surfaces.
Exceedance Probability
29 Green Infrastructure Research
SURFACE INFILTRATION & SURFACE CLOGGING 30 Green Infrastructure Research
We measured surface infiltration rates using a modified version of ASTM C1701 at roughly monthly intervals for about three years.
Modifications were (1) how the seal was achieved between the ring and the surface (2) added temperature measurements of surface and water. 31 Green Infrastructure Research
The infiltration rate varies among the four tested surfaces, but all surfaces are sufficient to handle maximum expected direct rainfall rates.
0.15-m (6-in.) thick
100-year, 5-minute rainfall intensity
0.20-m (8-in.) thick
• Edison, NJ 20.8 cm/hr (8.2 in/hr)
32 Green Infrastructure Research
Mean Monthly Infiltration Rate (cm/h)
Infiltration decreased with age for the three surfaces that received run-on from driving lane. 3,000
2010
2011
2012
2,500
2,000
1,500
1,000 0
5
10 15 20 25 Number of Months Since Opening PICP
30
35
Linear (PICP) y = -21.97x + 2455 R² = 0.4194 p = 0.0003
33
Bars represent standard error.
Green Infrastructure Research
We developed a working hypothesis of the mechanics of the infiltration processes. Flow
Small response
Large response
34 Green Infrastructure Research
As gaps fill with sediment, the location of the primary infiltration area moved downgradient.
Large response
Flow
Medium response
35 Green Infrastructure Research
Inspection supports the proposed mechanism.
36 Green Infrastructure Research
The progressive accumulation was also visible in the PICP section.
No sediment 37
Sediment Green Infrastructure Research
The surface clogging progression has varied slightly because of microtopography.
High resolution LASER survey
PICP row
38 Green Infrastructure Research
Street slopes (longitudinal and transverse) and curbs (height and condition) are important considerations when placing the controls in a curb and gutter system. Crown of road Curb / Sidewalk
Short curbs by design (or resulting from multiple resurfacing without milling) will limit the working flow width of the control. Steeper slopes concentrate flow and use less surface area.
39 Green Infrastructure Research
The important consideration is working surface area, not surface area. 100%
Y2004 Y2005 Y2006 Y2007
60%
Sc=2.81% So=1.30% n = 0.013 Louisville Control 19G
CPDF
It is not obvious what to use as a working width (e.g., mean / median calculated 5-minute average flow width).
80%
The current ICPI guidance is a ratio of control area to drainage area.
40%
Y2008 Y2009 Y2010 Y2011
20%
Y04-11 0% 0
1
2
3
4
5
6
7
8
5-minute average flow Width (ft)
40
50% of 5-minute average flow widths (excluding infiltration) are 0.75 ft or less Green Infrastructure Research
If this model is accurate, the particle size distribution of up gradient and down gradient sediment should differ.
Large response
Flow
Medium response
41 Green Infrastructure Research
Particle size distribution of the clogging sediment collected from a control in Louisville. 100 90
Percent Passing
80
Flow
70 60
Down gradient
19 G-A
50
19 G-B
40
19 G-C
30
19 G-D
20 10 0 10.000
1.000 0.100 0.010 Particle Size (mm)
0.001
42
Based in Research by Amir Ehsaei, University of Louisville
Green Infrastructure Research
Removing pavers at selected locations shows how clogging advances with gaps filled and small debris loading.
43 Green Infrastructure Research
With aggregate between the pavers, most of the fines are trapped in the top 20 mm.
44 Green Infrastructure Research
When pavers are installed without interstitial gravel, sediment progresses the full depth of the paver.
45
OTHER STUFF
46 Green Infrastructure Research
4.0 Water Level (m)
3.5 3.0
20
2.5
15
2.0 10
1.5 1.0 0.5 0.0 3:00
47
25
Measured Water Level Water Corrected Level Water Assuming Level No (noInfiltration exfiltration) Rainfall
During low-intensity rainfall the continuing exfiltration restores part of the storage volume.
6:00 9:00 Time of day (EST) 01/11/2012
5
Cumulative Rainfall (mm)
Intra-event exfiltration can be significant part of the collected water volume for long duration events
0 12:00
Level data at 1-minute intervals Rainfall data from MSD gauge TR05 at 5-minute intervals Green Infrastructure Research
Large portions of the pervious concrete at the Edison site disaggregated.
The problem first became apparent about 18 months after pouring concrete. It was repaired by the contractor in May 2011, but has recurred.
48 Green Infrastructure Research
Is structural failure coupled with chloride? Mg
Cl
Concentration Wt%
0.07 0.06 0.05 0.04 0.03 0.02 0.01
ND
0 0-2
3-4 Depth (inch)
5-6
April 14, 2014 49 Green Infrastructure Research
NRMCA revised O&M guidance (2015)
“Deicing chemicals should not be used on any type of concrete in the first year.”
50 Green Infrastructure Research
Office of Research and Development National Risk Management Research Laboratory Water Supply and Water Resources Division Urban Watershed Management Branch
Green Infrastructure Research
NJ ASLA Annual Meeting February 22, 2016
Office of Research and Development National Risk Management Research Laboratory Water Supply and Water Resources Division Urban Watershed Management Branch
Green Infrastructure Research
In order to get measurements at the realworld scale, we need to be involved in the design stage.
2 Green Infrastructure Research
In 2009, EPA designed and built a 1-acre parking lot for facility staff and visitors that was surfaced with three types of permeable pavement.
EPA Facility Parking Lot Edison, New Jersey 3 Green Infrastructure Research
The construction recycled the demolished concrete Demolition of existing concrete surface
Clearing
Crushing and screening
4 Green Infrastructure Research
Excavating the storage volume.
The recycled concrete aggregate was placed over a geotextile to form the storage layer.
Geotextile placed on bottom and sides
AASHTO No 2 sized RCA Added from North to South 20-ton Non-vibratory compaction 5 Green Infrastructure Research
Overall, construction took about a year. November 26, 2008
February 26,2009
March 25, 2009
June 1, 2009
August 5, 2009
6 October 6, 2009
October 8, 2009
October 28, 2009
The design incorporated water quality and hydrologic monitoring capabilities.
7
PICP
PC
PA
4
4
4
3
3
3
2
2
2
1
1
1
Interlocking concrete pavers
Pervious concrete
Porous asphalt
Buried distribution pipes
Tree islands
Hot mix asphalt
Buried well/piezometers
Collection tanks
Rain gardens
Buried WCRs Green Infrastructure Research
Interlocking concrete paver installation took a little more than a week.
8
EPHenry EcoPavers
East Penn Pavement CompanyGreen Infrastructure Research
Porous concrete pour took two days followed by a week of covered cure time
9
Weldon Concrete
Nova Crete, Inc.
Green Infrastructure Research
Placing the porous asphalt took two days
10
Stavola, Inc.
Stavola, Inc.
Green Infrastructure Research
Vertical cross sections of permeable sections varied slightly from material to material.
Concrete Pavers (3.125 in.)
Pervious Concrete (6 in.)
Porous Asphalt (3 in.)
AASHTO No. 8 (2 in.) AASHTO No. 57 (4 in.) AASHTO No. 2 RCA (depth varies) EPDM Membrane
AASHTO No. 2 RCA (depth varies)
AASHTO No. 2 RCA (depth varies)
EPDM Membrane
EPDM Membrane
Existing Subgrade
Existing Subgrade
Existing Subgrade
11 Green Infrastructure Research
Post excavation testing showed large infiltration rates for the underlying soil. Underlying Soil Infiltration Rate (in/hr)
60 50 40 30 20 10 0 12
ICP PICP
North
PC
PA
South
Green Infrastructure Research
Four equally-sized and spaced lined sections collect infiltrating water from each monitored permeable surface with the balance infiltrating to the underlying soil.
13 Green Infrastructure Research
Infiltrate drains from the lined sections to 1,500gallon tanks on the east side of the parking lot where it can be sampled.
14 Green Infrastructure Research
The tanks are designed to collect a 1.5-inch rain event before bypassing.
15 Green Infrastructure Research
Tanks are cleaned before each event.
16 Green Infrastructure Research
Collection tanks are homogenized with a centrifugal pump and sampled while particles are still in suspension.
17 Green Infrastructure Research
Samples of asphalt runoff are collected at the southern end of the parking lot to serve as a control for comparison to infiltrate.
18 Green Infrastructure Research
Rain water is sampled to document stressors from atmospheric deposition.
19 Green Infrastructure Research
SOME WATER QUALITY RESULTS
20 Green Infrastructure Research
Calcium chloride (with no sand) and a rubber edged plow blade were used to manage snow and ice.
21 Green Infrastructure Research
22
10,000
1,600 1,400 Acute (860 mg/L)
1,000
Chronic (230 mg/L) 100
1,200 1,000 800 600
10
MDL (5 mg/L)
400 200
1
PICP
Cumulative Depth (mm)
LS Mean Chloride Conc. (mg/L)
After winter salt application, chloride concentration decreases throughout the remainder of the year.
0
PC
PA
Snow (by season)
Rain (since previous snow event)
Bars represent 95% confidence intervals; snowfall data from NJ State Climatologist.
Green Infrastructure Research
All permeable surfaces reduced Suspended Solids Concentration (SSC) to different degrees. 175
Mean SSC (mg/L)
150 125 103.0
100
Date Range: 1/26/2010 – 6/4/2013 Events sampled: 42 (PICP, PC, and PA) 28 (Runoff)
75 50
52.7 mg/l
25 0 23
21.3 7.6
PICP
PC
PA
Runoff
Mean Mean±0.95 Conf. Interval Note: NSQD TSS commercial median 98 mg/L Green Infrastructure Research
Acidic rainfall is buffered by all pavement surfaces, and PA exfiltrate is surprisingly high. 12 11
10.8
Mean pH
10 9
8.8
9.1
8 7.3
7 6
5.5
5 24
PICP
PC
PA
Runoff
Rain
Date Range: 1/26/2010 – 6/4/2013 Events sampled: 42 (PICP, PC, and PA) 34 (Runoff) 36 (Rain) Mean Mean±0.95 Conf. Interval NSQD commercial 7.4 (n=527) Green Infrastructure Research
TN concentrations in PICP, PC, and Runoff were not significantly different, but all three were significantly less than PA. Average EMC (mg/L)
1.2
A
1.0 B
0.8
B
B
A
PC
RO
RAIN
PA
C
BB
0.6 C
0.4
A A CC
B
AA
D A
0.2 DC
B C
C
BD
0.0 NH3 25
PICP
NO2
NO3
TON
TN
Date Range: 10/28/2010 – 9/7/2011 Events sampled: 13 (PICP, PC, and PA) 12 (Runoff and Rain)
Stressor Green Infrastructure Research
Total phosphate concentrations in PICP and PC were significantly larger than Runoff, and all were significantly larger than PA. Average EMC (mg/L)
0.25 0.20 0.15
A
A
PC
RO
RAIN
PA
A
AB
0.10
B
B
C
C
0.05 D
D
T-PO4
F-PO4
0.00 26
PICP
Date Range: 10/28/2010 – 9/7/2011 Events sampled: 13 (PICP, PC, and PA) 12 (Runoff and Rain)
Stressor Green Infrastructure Research
27
Total Zinc
PICP PC
PA
RO Rain
Total Zinc Concentration (mg/L) log -scale
Concentration (mg/L) log -scale
Total Zinc does not vary by surface and the concentration was never larger than the GEL for any surface.
Exceedance Probability
Infiltrate sample concentrations did not differ from rainwater or runoff sample concentrations Green Infrastructure Research
28
Total Copper
PICP PC
PA
RO Rain
Concentration (mg/L) log -scale
Concentration (mg/L) log -scale
The concentration of total copper in the infiltrate from the PICP is larger than the infiltrate concentration from PA or PC, but none exceeded the GEL. Total Copper
Exceedance Probability Green Infrastructure Research
Total Arsenic
PICP PC
PA
RO Rain
Total Arsenic Concentration (mg/L) log -scale
Concentration (mg/L) log -scale
Total Arsenic does not vary by surface, but the concentration exceeded the GEL for some samples from all surfaces.
Exceedance Probability
29 Green Infrastructure Research
SURFACE INFILTRATION & SURFACE CLOGGING 30 Green Infrastructure Research
We measured surface infiltration rates using a modified version of ASTM C1701 at roughly monthly intervals for about three years.
Modifications were (1) how the seal was achieved between the ring and the surface (2) added temperature measurements of surface and water. 31 Green Infrastructure Research
The infiltration rate varies among the four tested surfaces, but all surfaces are sufficient to handle maximum expected direct rainfall rates.
0.15-m (6-in.) thick
100-year, 5-minute rainfall intensity
0.20-m (8-in.) thick
• Edison, NJ 20.8 cm/hr (8.2 in/hr)
32 Green Infrastructure Research
Mean Monthly Infiltration Rate (cm/h)
Infiltration decreased with age for the three surfaces that received run-on from driving lane. 3,000
2010
2011
2012
2,500
2,000
1,500
1,000 0
5
10 15 20 25 Number of Months Since Opening PICP
30
35
Linear (PICP) y = -21.97x + 2455 R² = 0.4194 p = 0.0003
33
Bars represent standard error.
Green Infrastructure Research
We developed a working hypothesis of the mechanics of the infiltration processes. Flow
Small response
Large response
34 Green Infrastructure Research
As gaps fill with sediment, the location of the primary infiltration area moved downgradient.
Large response
Flow
Medium response
35 Green Infrastructure Research
Inspection supports the proposed mechanism.
36 Green Infrastructure Research
The progressive accumulation was also visible in the PICP section.
No sediment 37
Sediment Green Infrastructure Research
The surface clogging progression has varied slightly because of microtopography.
High resolution LASER survey
PICP row
38 Green Infrastructure Research
Street slopes (longitudinal and transverse) and curbs (height and condition) are important considerations when placing the controls in a curb and gutter system. Crown of road Curb / Sidewalk
Short curbs by design (or resulting from multiple resurfacing without milling) will limit the working flow width of the control. Steeper slopes concentrate flow and use less surface area.
39 Green Infrastructure Research
The important consideration is working surface area, not surface area. 100%
Y2004 Y2005 Y2006 Y2007
60%
Sc=2.81% So=1.30% n = 0.013 Louisville Control 19G
CPDF
It is not obvious what to use as a working width (e.g., mean / median calculated 5-minute average flow width).
80%
The current ICPI guidance is a ratio of control area to drainage area.
40%
Y2008 Y2009 Y2010 Y2011
20%
Y04-11 0% 0
1
2
3
4
5
6
7
8
5-minute average flow Width (ft)
40
50% of 5-minute average flow widths (excluding infiltration) are 0.75 ft or less Green Infrastructure Research
If this model is accurate, the particle size distribution of up gradient and down gradient sediment should differ.
Large response
Flow
Medium response
41 Green Infrastructure Research
Particle size distribution of the clogging sediment collected from a control in Louisville. 100 90
Percent Passing
80
Flow
70 60
Down gradient
19 G-A
50
19 G-B
40
19 G-C
30
19 G-D
20 10 0 10.000
1.000 0.100 0.010 Particle Size (mm)
0.001
42
Based in Research by Amir Ehsaei, University of Louisville
Green Infrastructure Research
Removing pavers at selected locations shows how clogging advances with gaps filled and small debris loading.
43 Green Infrastructure Research
With aggregate between the pavers, most of the fines are trapped in the top 20 mm.
44 Green Infrastructure Research
When pavers are installed without interstitial gravel, sediment progresses the full depth of the paver.
45
OTHER STUFF
46 Green Infrastructure Research
4.0 Water Level (m)
3.5 3.0
20
2.5
15
2.0 10
1.5 1.0 0.5 0.0 3:00
47
25
Measured Water Level Water Corrected Level Water Assuming Level No (noInfiltration exfiltration) Rainfall
During low-intensity rainfall the continuing exfiltration restores part of the storage volume.
6:00 9:00 Time of day (EST) 01/11/2012
5
Cumulative Rainfall (mm)
Intra-event exfiltration can be significant part of the collected water volume for long duration events
0 12:00
Level data at 1-minute intervals Rainfall data from MSD gauge TR05 at 5-minute intervals Green Infrastructure Research
Large portions of the pervious concrete at the Edison site disaggregated.
The problem first became apparent about 18 months after pouring concrete. It was repaired by the contractor in May 2011, but has recurred.
48 Green Infrastructure Research
Is structural failure coupled with chloride? Mg
Cl
Concentration Wt%
0.07 0.06 0.05 0.04 0.03 0.02 0.01
ND
0 0-2
3-4 Depth (inch)
5-6
April 14, 2014 49 Green Infrastructure Research
NRMCA revised O&M guidance (2015)
“Deicing chemicals should not be used on any type of concrete in the first year.”
50 Green Infrastructure Research
Office of Research and Development National Risk Management Research Laboratory Water Supply and Water Resources Division Urban Watershed Management Branch
Green Infrastructure Research
