Performance of Pervious Pavement

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WELCOME
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Performance of Pervious Concrete and Comparison
to other BMPs Used to Reduce Average Yearly
Discharge

• Presentation by Marty Wanielista

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Team Members are Manoj Chopra, Marty
Wanielista, Eric Livingston, Mike Hardin,
Joshua Spence, Craig Ballock Ben Pernezny,
Erik Stuart, Pat Muench, Michael Davy, and
Matt Offenberg

• Stormwater Management Academy, UCF
• FDOT, Deland
• Rinker Materials, Orlando
• FDEP, Tallahassee

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Issues and Interests

• Need for Credit (partial or total) for reducing
  directly connected impervious surfaces
• Based on Volume of water that can be Stored and
  not released to surface waters on an annual
  basis.
• Issues Pervious Pavement
• What is design mix, materials, dimensions, GWT?
• What are proper construction methods?
• What is the infiltration rate for the system?
• What is effect on water quality?
• Can vacuum sweeping or other operations be used
  to rejuvenate the pavements?

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Comparisons

• Comparison Parameters
• Average yearly volume of water not discharged
• Pollutant mass associated with this water.
• Comparison to other BMPs
• Disconnecting Directly Connected Impervious areas
  using Retention Areas (on site infiltration).
• Green Roofs.
• Recycling Ponds.
• Use Treatment Trains.

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SMART STORMWATER MANAGEMENT

• Pervious Pavement
• Retention systems
• Infiltration basins
• Exfiltration trenches
• Green Roofs
• Recycling (reuse) ponds
• Flexipave
• Swales

Keep the water on site
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Overview of Pervious Concrete

• Pervious or no-fines Concrete mixture of coarse
  aggregate, Portland Cement, admixtures and water
• Increased Porosity due to limited fines and
  15-20 air voids
• Strong need for Current and Updated Assessment of
  Pervious Pavements

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Historical and Literature Review

• PC Pervious Pavements have been used for past 20
  years in Areas of Lower Traffic Loads (parking
  lots, shoulders, airport taxiways, some state and
  local roads).
• Common beliefs
• Infiltrating Subsoil Conditions
• Seasonal High Groundwater Table must be lower
  than at least one foot below the bottom of the
  pervious concrete.

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Test Cells at the University

• Using ASTM D3385-03 (Double Ring) procedure was
  compared to an embedded Single Ring and good
  comparisons.
• Initial Double Ring Tests on Compacted Subsoil
  before Concrete Placement have yielded an average
  infiltration rate of 2.6 in/hr
• Without compaction, the rate for the soil was
  12-20 in/hr

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Why does an infiltrometer not work on top of an
pervious surface?

• Double Ring Infiltrometer on the Surface of PC

Infiltration rates exceeded 200 inches per hour,
but how can that be if the soil infiltration
rates were only 2-4 inches per hour? Answer
lateral flow.
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Development of Embedded Single or Double Ring
Infiltrometer

• Double Ring Infiltrometer on the surface of
  Pervious Pavement not Suitable due to Preferred
  Lateral Migration of Water
• Led to Concept of Single and Double Ring Embedded
  Infiltrometer
• Depth of Embedment is an Important Parameter
  (Initial Assumption 14 inches including the 6
  inches of pavement) which resulted in 4 inches of
  water storage.
• Used a 12 inch Diameter (11-5/8 ID) with
  11-Gauge Steel

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Single-Ring Infiltrometer Development

• Comparative testing between the Single-Ring
  Infiltrometer and Double-Ring Infiltrometer on
  parent soils was performed to test agreement of
  the two.
• Specific Head tested between range of 4 to 8
  inches with little variance in infiltration rates
  between the two.

Measured Infiltration Rate (in/hr) Measured Infiltration Rate (in/hr)
Single-Ring Infiltrometer Double-Ring Infiltrometer
20.41 21.15
23.51 23.34
20.52 21.40
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Embedded Single Ring Infiltrometer

• One dimensional flow (no horizontal flow between
  pavement and soil).
• Representative of site existing conditions.
• Choice of 14 inches was based on a soil, concrete
  storage volume of 4 inches
• of rainfall. Four (4) inches of rainfall
  is greater than the average of the
• maximum daily rainfall in one year for
  Florida. Flow is maintained in a
• vertical direction within the ring. The depth
  of ring penetration can be
• greater if there is expected greater depth
  of infiltrate such as a combination
• of building runoff water plus rainfall.

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Field Sites (tested in 2006)

• Field Sites in Florida
• Vet Office in Sanford (18 years old)
• FCPA Office in Orlando (6 years)
• Sunray StoreAway Lake Mary (14 years)
• Strang Communications Lake Mary (13 years)
• FDEP Office Tallahassee (20 and 4 years)
• Field Sites outside Florida
• Cleveland Park - Greenville, South Carolina (10
  years)
• SOUTHFACE Office - Atlanta, Georgia (10 years)
• Effingham County Landfill - Guyton, Georgia (7
  years)

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Field Investigation Methodology

• 12-in diameter cores
• Run field tests
• Determination of Field Unit Weight of Compaction
• Embedded Single Ring Infiltrometer
• Collect soil samples
• Repair core locations
• Lab work on soil samples
• Sieve Analysis
• Liquid Plastic Limits
• Permeability Tests
• Lab test on core infiltration rates

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Field Investigation Sun-Ray Store Away
Core No. Field System Infiltration Rate (in/hr) Field Soil Infiltration Rate (in/hr) Laboratory Core Infiltration Rate (in/hr)
A-1 -- 34.5 --
A-2 17.8 -- 34.5
A-3 17.7 -- 20.2
A-4 10.5 -- 3.7
A-5 -- 14.8 4.8
A-6 10.4 -- 3.0
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Field Investigation Effingham Landfill, Georgia
Core No. Laboratory Core Infiltration Rate (in/hr)
LF-1 30.8
LF-2 11
LF-3 187
Notes 1. Clay soils, no measurable soil
infiltration 2. Reservoir under PC,
about 6 inches thick 3. Eight inch
PC Thickness 4. Used to support
dumpster trucks
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Field Investigation Cleveland Park, South
Carolina
Core No. Laboratory Core Infiltration Rate (in/hr)
SC-1 -- 86.2
SC-2 -- 0
SC-3 -- 84.7
Notes 1. About 6 inch Reservoir under PC 2.
Clay soils, no measured soil infiltration
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Typical Field Test Results
Conducted until volume into the system exceeded 3
inches
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Rehabilitation of Clogged Pavements

• Determine the effectiveness of various
  rehabilitation techniques on clogged previous
  concrete including
• Vacuum Sweeper
• Pressure Cleaning
• Combination of both of the above
• Develop a standardized inspection and maintenance
  schedule

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Laboratory Testing Process

• Determined initial infiltration rates of cores
  obtained in the field using SRI.
• One core was subjected to one of the following
  rehabilitation techniques
• Pressure Washer (3000 psi Gas Pressure)
• Vacuum Sweeper (6.5 hp Wet/Dry Vaccum Sweeper)
• Both Pressure Washer Vacuum Sweeper
• Determined the rehabilitated infiltration rates
  of cores using SRI.

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Test Setup
Single Ring Infiltrometer
8 in. head of water Constant Head Test
Seal
Pervious Concrete Core Wrapped in Impermeable
Poly Film
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Rehabilitation Techniques Results
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Effectiveness of Rehab-Observations

• Both methods resulted in significant increase in
  the infiltration rates.
• For properly constructed PC, the rates at the
  completion of the cleaning are higher than the
  soil rates measured at these sites.
• Recommend vacuum because pressure was observed to
  remove particles and may wash pollutants into the
  stormwater system.

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Construction Specifications

• Placement and finishing techniques for pervious
  concrete are different from plain concrete
• Pervious concrete must be placed with specialty
  equipment and the water content of the fresh
  concrete must be carefully controlled
• NRMCA has implemented a Contractor Certification
  Program as of September, 2005

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Construction Specifications

• Appropriate mix proportions
• /- 5 lbs/CF of design unit weight
• Discrepancies are generally related to water
  content
• Too much water must reject load

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Construction Specifications

• Concrete should be stricken off ¼ to ½ of an inch
  about the form boards and compacted to level
• Compaction roll with a 10-inch schedule 40
  steel pipe
• Curing Time pavement should be covered a
  minimum of 7 days
• Curbing should be used to direct infiltrating
  water downward and to prevent erosion at the
  edges of pervious concrete slabs

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Insufficient Curing
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Operational Specifications

• Limit frequency of heavy traffic e.g.
  construction vehicles, garbage trucks, etc.
• Remove or Limit sources of Sediments. Adjacent
  areas?
• Signage such as ADOPT A LOT
• Adopt a Standard Maintenance Schedule

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Proposed Design Section
COMPACT SUBGRADE TO 92 MODIFIED PROCTOR (ASTM
D-1557)
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Simulation Model
How can the credit ( of rainfall infiltrated or
kept on site) be determined?

• Determine Rainfall Excess and Recharge
• Simulate over a period of time (1 year)
• One Dimensional

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Mass Balance Model

• Three Controlling Infiltration Rates Concrete,
  Soil, Water Table
• Other Parameters Concrete Soil Porosity,
  Depth of Concrete, and Depth of Soil to WT
• One year of Rainfall Data (2003)
• Variable Time Step (one minute - one day)

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Mass Balance Modeling
Dwt
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Field Results Yearly Retention

• Location Fconc Fsoil Faq Dc Dwt
  Retained
• (in/hr) (in/hr) (in/hr) (in)
  (in)
• Site 1.1 25.7 34.5 0.16 10
  120 99.9
• Site 1.2 3.6 14.8 0.16 10
  120 99.5
• Site 2 5.9 5.4 0.16 8
  120 99.6
• Site 3 14.4 21.5 0.16 7 72
  99.9
• Site 4.1 2.1 15.6 0.002 10 12
  40.9
• Site 4.2 2.9 15.6 0.002 8 12
  40.2
• Site 5 3.7 8.8 0.16 8
  72 99.5

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Yearly Retention as a function of Pervious
Concrete infiltration rate (in/hr)
From model using real field data, Rain 52.49
in/year, Fsoil 5.4 in/hr, Faq 0.16 in/hr, Dc
8 in, Dwt 24 in
1.5
3.5
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Percent Yearly Retention as a function of
concrete infiltration rate for groundwater
movement
Fwt 0.16 in/hr
Fwt 0.005 in/hr
Fwt 0.002 in/hr
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I-4 Shoulder and Watershed Area(equivalent to 6
lanes of traffic)
Test shoulder site is 90 feet long by 10 feet wide
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Under Drains and Separation Fabric to Collect
Water Quality Samples
Separation Fabric
Adjacent to existing pave And 7 feet from edge of
pave
Slotted pipe to collect Infiltrated water
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Filter Media, Pervious Concrete and Testing
Black and Gold Nuggets TM
Pervious Concrete
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Placement, Striking, Pizza Cutter and 7 day
Curing
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ERIK (Embedded Ring Infiltrometer Kit)
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Kit for Measurments
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Some Water Quality Results

• Based on 50 inches of runoff per year, the
  loading reduction is about 6 lbs of P and 12 lbs
  of N per year per parking acre.
• Runoff from 60 feet of parking has concentrations
  of OP4 about 0.7 mg/L and NO3-N of about 1.4
  mg/L.
• Based on seepage water under the I-4 rest area
  shoulder with a 12 inch depth of pervious
  concrete and 12 inches of water quality media.
• OP4 averages about .1 to .2 mg/l
• NO3-N averages about .3 to .4 mg/l
• Rainfall in the area has about
• OP4 of 0.2 mg/L
• NO3-N of 0.4 mg/L

Assumes 100 control
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Cost Savings

• Pond size reductions should be able to save the
  cost of the land and the construction of the
  pond, if pervious lot is constructed with a curb.
• Infrastructure cost assumed that the runoff is
  non existent from rainfalls up to 3 inches in one
  day, thus could result in smaller pipe sizes.
• Note a cost savings of over 60,000 per acre of a
  pervious lot in central Florida with land cost
  not being considered.

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Cost Comparisons

• PC Construction cost is about 25 more
• expensive than regular concrete.
• Infra structure cost savings on a 4 acre
• parking lot was about 235,000 (in pipes,
  inlets, and manholes)
• About 1.33 savings per square foot of parking
  lot.

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The New American Home for 2007
Completed in November 2006

Integrated bio-retention on the ground with
green roof areas on and at different levels of
the home. Also air conditioner condensate will
be recycled
Completed in November 2006
Design based on post discharge less than pre
discharge or 4 inches of rainfall storage and 95
reuse, over 95 pollutant mass reduction.
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Amendments for the New American Home
In the green roof
In the patio area
In the planter boxes
In the bio swale
In the runoff swale
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Green Roof Design

• Cistern Design
• Use CSTORM Model
• Choose Desired Yearly Stormwater Retention
• Use Respective Cistern Volume
• Storage Volume Will Vary With Location

a
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Green Roof Stormwater Price Comparison with land
costs(2005 prices)
100000 square foot roof 100000 square foot roof 100000 square foot roof 100000 square foot roof 100000 square foot roof
  Down Town Orlando N. Magnolia Lee Road and I-4 University Blvd. International Drive
Pond Price (Including Land Cost) 5,800,000.00 1,550,000.00 1,200,000.00 2,100,000.00
Green Roof Price 1,400,000.00 1,400,000.00 1,400,000.00 1,400,000.00
Realized savings 4,400,000.00 150,000.00 -200,000.00 700,000.00
Green Roof price includes the first year of
maintenance while the Pond price does not
include any maintenance. (based on 14/square
foot construction )
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Life Cycle Cost Analysiswithout land cost

• Conventional exposed roof vs. passive green roof
• Pay back period 15 years
• Not including energy savings
• Pay back period 10 years
• Including energy savings
• Conventional built-up roof vs. active green roof
• Pay back period of 35 years
• Including energy savings

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STORMWATER POND used for irrigation - Winter Park
Savings of 2500/year using stormwater over about
1 acre of land. Savings based only on the shadow
cost of potable water.
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A recycle or reuse pond
Reuse volume is similar to the treatment volume
in the sense that it is removed or reduced to
the control elevation and water is used from
the pond until a pond elevation equal to 1 inch
on the effective impervious area is reached
below the control or into the permanent pool.
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Horizontal Wellsfirst horizontal stormwater
recovery well in Bonita Springs 1990integrated
reclaimed and reuse system on the UCF campus 2007
Excellent for pollution control
from http//www.horizontal.com/Applications/Water
_Supply/Water_Supply_desc.html
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Cost and Payback Period for Recycling of
Stormwater

• Payback period varies from 3-12 years, and
  depends on system construction cost, and the cost
  of the water currently being used.
• Cost ranges from 0.25 to 1.50/1000 gal.
• Varies depending
• Physical conditions or location of the water
  source and the irrigation land, and extraction
  process
• FPSC franchise area or not
• Backup source cost
• Need to retire a local bond for replaced water

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Treatment Trains

• The placement of SMART (BMPs) together usually in
  series so that a higher effectiveness can be
  achieved.

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Treatment Trains

• Parallel the sum of the pollution mass removal
  is the sum of the individual systems. The
  effluent of BMPs go into one system.

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Treatment Trains

• Series when two or more BMPs are connected such
  that the effluent of an upstream one becomes the
  influent to the downstream one.

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Example Effectiveness Calculationsor how to meet
the pollution control

• A treatment train is the combination of BMPs
  where the discharge of one is influent to
  another.
• The general effectiveness is calculated by
  knowing the fraction removed by each BMP.
  For two BMPs in series.
• R 100 1 (1-r1)(1-r2)
• And for i in series R 100 1 Pi(1-ri)
• where R overall removal
• ri fraction removed in process I
• NOTE removal is based on postpre or a
  specific number like 80 or 90.

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Wet Pond Effectiveness
From Harper, 2006, page 5-46
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Enhance nitrogen effectiveness of a detention
pond by recycling the detained water A Recycling
Pond

• For 80 N effectiveness, what of the detained
  runoff has to be recycled (that is not
  discharged)? R1001-(1-.67)(1-.4) 80

Answer 67
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Green Roof to Detention Pond a regional pond
following an urban green roof with no room for a
cistern

• Nitrogen Water Quality Effectiveness or
• R1001-(1-.50)(1-.6) 80

Note a green roof with cistern designed at 1
gallon per square foot will have a
Nitrogen effectiveness of about 96.
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Three BMPs in series

• R 1001-(1-.5)(1-.6)(1-.8) 96

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Conclusions - Pervious Concrete

• Proper Construction (Placement, Water, and
  Curing) is Important. Certification is required!
  
• Specifications needed for Design and Operational
  Practices (Curbing, Pavement Thickness, Signage).
• New construction place single ring
  infiltrometers embedded within the PC, then
  testing is easier.
• Infiltration rates are Comparable to Stormwater
  Retention Ponds.

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Conclusions

• Water Quality in the filtrate is about equal to
  rainfall in terms of nitrate nitrogen and
  orthophosphate
• Site infiltration tests can be done. Rates less
  than 1.5 inches/hr indicates a need for
  rehabilitation.
• Pressure Washing and Vacuum Sweeping are
  Effective Rehabilitation Techniques. I recommend
  vacuum techniques.
• Water retention is directly proportional to the
  infiltration rates of the pervious concrete.
  Modeling efforts indicate pervious concrete
  should be given credit in a stormwater management
  plan.
• Other options are green roofs, retention areas
  and recycling of stored runoff water.

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Thank you, Questions? And Comments.
Wanielis_at_mail.ucf.edu and www.stormwater.ucf.edu