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Tire crumb rubber in stormwater filtration

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Title:
Tire crumb rubber in stormwater filtration
Creator:
Rhodes, Emily Perdue
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Language:
English
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xvii, 127 leaves : illustrations ; 28 cm

Subjects

Subjects / Keywords:
Stormwater infiltration ( lcsh )
Rubber, Reclaimed ( lcsh )
Crumb rubber ( lcsh )
Crumb rubber ( fast )
Rubber, Reclaimed ( fast )
Stormwater infiltration ( fast )
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bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

Notes

Bibliography:
Includes bibliographical references (leaves 122-127).
General Note:
Department of Civil Engineering
Statement of Responsibility:
Emily Perdue Rhodes.

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|University of Colorado Denver
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|Auraria Library
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
747101214 ( OCLC )
ocn747101214
Classification:
LD1193.E53 2011m R46 ( lcc )

Full Text
M
TIRE CRUMB RUBBER IN STORMWATER FILTRATION
by
Emily Perdue Rhodes
B.A., Willamette University, 2007
A thesis submitted to the
University of Colorado Denver
in partial fulfillment
of the requirements for the degree of
Master of Science
Civil Engineering
2011


This thesis for the Master of Science
degree by
Emily Rhodes
has been approved
by
4 /zi/-zol\
April 15,2011


Rhodes, Emily Perdue (M S., Civil Engineering)
Tire Crumb Rubber in Stormwater Filtration
Thesis directed by Professors David C. Mays and Zhiyong (Jason) Ren
ABSTRACT
Stormwater contributes significant contamination to receiving waters, and mitigating
this impact is becoming increasingly important. This research aims to evaluate the
feasibility of replacing sand with tire crumb rubber in granular media filters used for
stormwater pollution control. Granular media filters suffer from high operation and
maintenance costs, and removing suspended solids, which filters do particularly well,
results in clogging that reduces their hydraulic capacity. Previous work has suggested
that using tire crumb rubber, rather than sand, reduces clogging in granular media
filters used to polish treated sewage without compromising pollutant removal. Tire
crumb rubber has the potential to remove suspended solids, nutrients, metals, and
pathogens, which are the main concerns in stormwater runoff, and may reduce the
maintenance costs. Tires may also remove certain pollutants better than traditional
sand due to the hydrophobicity of the tire crumb rubber. In addition, replacing sand
with tire crumb rubber would provide an end use market for tire crumb rubber made
from scrap tires. Recent estimates indicate that more than 2 billion scrap tires are
currently stockpiled in the United States and approximately 280 million more tires are
added annually. Based on the literature, leaching of zinc from the tire crumb rubber
appears to represent the most significant water quality concern associated with using
this material in stormwater sand filters. Zinc oxide is generally used in tire
manufacturing, representing approximately 1.6% of the final product by mass. In this
research, we performed batch and column leach tests to explore the concentration of
zinc that leaches from tire crumb rubber. Next, we examined stormwater contaminant
removal in column filtration tests with sand and tire crumb rubber as the filter media.
The results suggest that tire crumb rubber leaches zinc in concentrations above the
Environmental Protection Agencys freshwater limits. However, after an initial pulse
of higher concentrations, the concentration of zinc leaching from the tire crumb
rubber approaches this limit of 0.12 mg/L. When testing contaminant removal with
tire crumb rubber and sand as the filter media, the filters containing 100% tire crumb
rubber performed similarly to the filters containing sand, however, due to the leaching


of zinc, 100% tire crumb rubber filters are not recommended for stormwater pollution
control.
This abstract accurately represents the content of the candidates thesis. I recommend
its publication.
Signed
d C. Mays


DEDICATION PAGE
I dedicate this thesis to my soon to be husband, Buddy George, for his encouragement
and support while I was completing my Masters program. I also dedicate this thesis
to my parents, Earl and Cindy Rhodes, who have always supported me in my every
endeavor.


ACKNOWLEDGMENT
Thank you to my advisors, David C. Mays and Zhiyong (Jason) Ren, for their
continual guidance and support. I could not have asked for more helpful and
dedicated professors to assist me in my research and graduate program. Thank you to
Jeffery Gee and Phil Robinson for their contributions and support. I would also like to
thank machinist, Randy Ray, for his expert assistance.
Funding for this work was provided by the Colorado Department of Public Health
and Environment through the Advanced Technology Grant Program.


TABLE OF CONTENTS
Figures..................................................................xii
Tables...................................................................xvii
Chapter
1. Introduction and Background Information................................18
1.1 Research Objective.................................................18
1.2 Stormwater Management..............................................19
1.3 Scrap Tire Management..............................................21
1.4 Tire Crumb Rubber..................................................23
2. Literature Review......................................................24
2.1 Toxicity...........................................................24
2.2 Filtration.........................................................30
3. Leaching Experiments...................................................31
3.1 Methods............................................................32
3.1.1 SPLP............................................................32
3.1.2 Batch...........................................................33
3.1.3 Column..........................................................33
3.2 Results............................................................35
3.2.1 SPLP............................................................35
3.2.2 Batch...........................................................35
3.2.3 Column..........................................................37
4. Stormwater Filtration Experiments......................................41
4.1 Methods............................................................41
4.2 Results............................................................46
4.2.1 Nutrients.......................................................46
ix


4.2.2 Metals..............................................................53
4.2.3 TSS/TDS.............................................................57
4.2.4 COD.................................................................60
4.2.5 Oil and Grease......................................................62
4.2.6 Pathogens...........................................................63
4.2.7 Flow Rates..........................................................64
4.2.8 Hydraulic Conductivity..............................................64
5. Discussion................................................................66
5.1 Zinc Leaching.........................................................66
5.1.1 SPLP................................................................66
5.1.2 Batch...............................................................66
5.1.3 Column..............................................................66
5.2 Filtration Performance................................................67
6. Conclusions and Future Research...........................................68
6.1 Conclusions...........................................................68
6.2 Future Research.......................................................68
Appendix
A. Nutrient Effluent Concentrations in Saturated and Unsaturated Stormwater
Filtration Tests..........................................................70
B. Metals Effluent Concentrations in Saturated and Unsaturated Stormwater
Filtration Tests..........................................................82
C. TSS and TDS Effluent Concentrations in Saturated and Unsaturated Stormwater
Filtration Tests..........................................................94
D. COD Effluent Concentrations in Saturated and Unsaturated Stormwater
Filtration Tests.........................................................104
x


E. Oil and Grease Effluent Concentrations in Saturated and Unsaturated
Stormwater Filtration Tests...........................................110
F. Total Coliform Effluent Concentrations in Saturated and Unsaturated
Stormwater Filtration Tests...........................................113
G. Flow Rates in Saturated and Unsaturated Stormwater Filtration Tests...115
H. Hydraulic Conductivity in Saturated Stormwater Filtration Tests.......118
References.................................................................122
xi


FIGURES
Figure 1-1: Stormwater Sand Filter in Portland, OR (City of Portland, 2004)......18
Figure 1-2: Stormwater samples before and after passing through a sand filter (Urban
Drainage and Flood Control District, 2008a)..................................21
Figure 1-3: Stockpiled tires. More than 2 billion tires are currently stockpiled in the
United States and 280 million are added annually (En Tek, 2011)..............22
Figure 1-4: 6M tire crumb rubber distributed by AcuGreen.......................23
Figure 3-1: Sieve Analysis of tire crumb rubber..................................32
Figure 3-2: Agitator used in the EPA's synthetic precipitation leaching procedure. 33
Figure 3-3: Testing Apparatus. Tap water was pumped from the barrels to the
columns and effluent samples were analyzed for zinc concentrations. This
apparatus was also used in the filtration experiments............................34
Figure 3-4: Zinc leached versus average radius in the synthetic precipitation leaching
procedure (SPLP) test. Note: the 6M sample was a mixture of all represented
sizes........................................................................35
Figure 3-5: Zinc leached over time in batch leach test 1 while stirring and not stirring
the tire crumb rubber at pH 6.3..............................................36
Figure 3-6: Zinc leaching over time in batch test 2 at pH 6.2....................36
Figure 3-7: Zinc leaching over time in batch test 3 at pH 6.7....................37
Figure 3-8: Zinc leaching over time in column test 1 at pH 6.4...................38
Figure 3-9: Zinc leaching over time in column test 2 at pH 6.....................39
Figure 3-10: Zinc leaching over time in column test 2 at pH 6.5..................40
Figure 3-11: Zinc leaching over time in column test 2 (unwashed) and 3 (washed). .40
Figure 4-1: Nitrate percent removal...............................................48
Figure 4-2: Nitrate+Nitrite percent removal.......................................49
Figure 4-3: Orthophosphate percent removal........................................50
Figure 4-4: TKN percent removal...................................................51
Figure 4-5: TP percent removal....................................................52
Figure 4-6: Zinc percent removal..................................................54
xii


Figure 4-7: Copper percent removal..............................................55
Figure 4-8: Lead percent removal................................................56
Figure 4-9: TSS percent removal.................................................58
Figure 4-10: TDS percent removal................................................59
Figure 4-11: COD percent removal................................................61
Figure 4-12: Oil and grease percent removal.....................................62
Figure 4-13: Pathogen removal in the sand column unsaturated filtration test 2 with
water from the South Platte........................................'.......63
Figure 4-14: Pathogen removal in tire column during unsaturated filtration test 2 with
water from the South Platte................................................63
Figure 4-15: Piezometers and pressure ports for measuring the pressure difference
across the filter media....................................................65
Figure A-l: Nitrate effluent concentration in saturated filtration test 1: (a) raw data
(b) normalized data.......................................................70
Figure A-2: Nitrate effluent concentration in saturated filtration test 2: (a) raw data
(b) normalized data.......................................................71
Figure A-3: Nitrate + nitrite effluent concentration in saturated filtration test 3: (a)
raw data (b) normalized data..............................................72
Figure A-4: Nitrate + nitrite effluent concentration in unsaturated filtration test 1: (a)
raw data (b) normalized data..............................................73
Figure A-5: TKN effluent concentration in saturated filtration test 2: (a) raw data (b)
normalized data...........................................................74
Figure A-6: TKN effluent concentration in saturated filtration test 3: (a) raw data (b)
normalized data...........................................................75
Figure A-7: TKN effluent concentration in unsaturated filtration test 1: (a) raw data
(b) normalized data.......................................................76
Figure A-8: Orthophosphate effluent concentration in saturated filtration test 1: (a)
raw data (b) normalized data..............................................77
Figure A-9: Orthophosphate effluent concentration in saturated filtration test 2: (a)
raw data (b) normalized data...................................................78
xm


Figure A-10: Total phosphorous effluent concentration in saturated filtration test 2:
(a) raw data (b) normalized data...........................................79
Figure A-l 1: Total phosphorous effluent concentrations in saturated filtration test 3:
(a) raw data (b) normalized data...........................................80
Figure A-l2: Total phosphorous effluent concentration in unsaturated filtration test 2:
(a) raw data (b) normalized data...........................................81
Figure B-l: Zinc effluent concentrations in saturated filtration test 1: (a) raw data (b)
normalized data............................................................82
Figure B-2: Zinc effluent concentrations in saturated filtration test 2: (a) raw data (b)
normalized data............................................................83
Figure B-3: Zinc effluent concentrations in saturated filtration test 3: (a) raw data (b)
normalized data............................................................84
Figure B-4: Zinc effluent concentrations in unsaturated filtration test 1: (a) raw data
(b) normalized data........................................................85
Figure B-5: Copper effluent concentrations in saturated filtration test 1: (a) raw data
(b) normalized data........................................................86
Figure B-6: Copper effluent concentrations in saturated filtration test 2: (a) raw data
(b) normalized data........................................................87
Figure B-7: Copper effluent concentrations in saturated filtration test 3: (a) raw data
(b) normalized data........................................................88
Figure B-8: Copper effluent concentrations in unsaturated filtration test 1: (a) raw
data (b) normalized data...................................................89
Figure B-9: Lead effluent concentrations in saturated filtration test 1: (a) raw data (b)
normalized data............................................................90
Figure B-10: Lead effluent concentrations in saturated filtration test 2: (a) raw data
(b) normalized data........................................................91
Figure B-l 1: Lead effluent concentrations in saturated filtration test 3: (a) raw data
(b) normalized data........................................................92
Figure B-l2: Lead effluent concentrations in unsaturated filtration test 1: (a) raw data
(b) normalized data........................................................93
Figure C-l: TSS effluent concentrations in saturated filtration test 1: (a) raw data (b)
normalized data.................................................................94
xiv


Figure C-2: TSS effluent concentrations in saturated filtration test 2: (a) raw data (b)
normalized data..................................................................95
Figure C-3: TSS effluent concentrations in saturated filtration test 4: (a) raw data (b)
normalized data............................................................96
Figure C-4: TSS effluent concentrations in unsaturated filtration test 1: (a) raw data
(b) normalized data........................................................97
Figure C-5: TSS effluent concentrations in unsaturated filtration test 2: (a) raw data
(b) normalized data........................................................98
Figure C-6: TDS effluent concentrations in saturated filtration test 1: (a) raw data (b)
normalized data............................................................99
Figure C-7: TDS effluent concentrations in saturated filtration test 2: a) raw data b)
normalized data...........................................................100
Figure C-8. TDS effluent concentrations in saturated filtration test 4: a) raw data b)
normalized data...........................................................101
Figure C-9: TDS effluent concentrations in unsaturated filtration test 1: a) raw data b)
normalized data...........................................................102
Figure C-10: TDS effluent concentrations in unsaturated filtration test 2: a) raw data
b) normalized data........................................................103
Figure D-l: COD effluent concentrations in saturated filtration test 1: (a) raw data (b)
normalized data...........................................................104
Figure D-2: COD effluent concentrations in saturated filtration test 2: (a) raw data (b)
normalized data...........................................................105
Figure D-3: COD effluent concentrations in saturated filtration test 3: (a) raw data (b)
normalized data...........................................................106
Figure D-4: COD effluent concentrations in unsaturated filtration test 1: (a) raw data
(b) normalized data.......................................................107
Figure D-5: COD effluent concentrations in unsaturated filtration test 2: (a) raw data
(b) normalized data.......................................................108
Figure D-6: COD effluent concentrations in saturated filtration test 4: (a) raw data (b)
normalized data............................................................109
Figure E-l: Oil and grease effluent concentrations in saturated filtration test 3: (a) raw
data (b) normalized data...................................................110
xv


Figure E-2: Oil and grease effluent concentrations in unsaturated filtration test 1: (a)
raw data (b) normalized data.......................................................Ill
Figure E-3: Oil and grease effluent concentrations in unsaturated filtration test 2: (a)
raw data (b) normalized data..................................................112
Figure F-l: Total coliform effluent concentrations in saturated filtration test 4: (a) raw
data (b) normalized data......................................................113
Figure F-2: Total coliform effluent concentrations in unsaturated filtration test 2: (a)
raw data (b) normalized data..................................................114
Figure G-l: Flow rates in saturated filtration test 2: (a) raw data (b) normalized data.
..............................................................................115
Figure G-2: Flow rates in saturated filtration test 3: (a) raw data (b) normalized data.
..............................................................................116
Figure G-3: Flow rates in saturated filtration test 5: (a) raw data (b) normalized data.
..............................................................................117
Figure H-l: Hydraulic conductivity in saturated filtration test 1. Note: the flow meter
on the tire column was faulty in this experiment.........................118
Figure H-2: Hydraulic conductivity in saturated filtration test 2: (a) raw data (b)
normalized data.........................................................119
Figure H-3: Hydraulic conductivity in saturated filtration test 3: (a) raw data (b)
normalized data..........................................................120
Figure H-4: Hydraulic conductivity in saturated filtration test 5: (a) raw data (b)
normalized data.........................................................121
xvi


TABLES
Table 1-1: Land-Use Average Event Mean Concentrations of Stormwater Runoff in
the Denver Metropolitan Area (Urban Drainage and Flood Control District,
2008b).............................................................20
Table 2-1: Summary of leaching data in the literature...................26
Table 3-1: Leaching test overview.......................................31
Table 4-1: Recipe for simulated stormwater runoff (Davis, Shokouhian, Sharma, &
Minami, 2001; Hong, Seagren, & Davis, 2006)........................42
Table 4-2: Filtration experiments testing overview......................43
Table 4-3: Testing laboratories and methods.............................44
Table 4-4: Summary of Results for Nitrate...............................48
Table 4-5: Summary of Results for Nitrate+Nitrite.......................49
Table 4-6: Summary of Results for Orthophosphate........................50
Table 4-7: Summary of Results for TKN...................................51
Table 4-8: Summary of Results for Total Phosphorous.....................52
Table 4-9: Summary of Results for zinc..................................54
Table 4-10: Summary of Results for copper...............................55
Table 4-11: Summary of Results for lead.................................56
Table 4-12: Summary of Results for TSS..................................58
Table 4-13: Summary of Results for TDS..................................59
Table 4-14: Summary of Results for COD..................................61
Table 4-15: Summary of Results for oil and grease.......................62
Table 5-1: Summary of performance of tire crumb rubber and sand filters.67
xvii


1. Introduction and Background Information
1.1 Research Objective
The objective of this research was to evaluate the feasibility of replacing sand with
tire crumb rubber in granular media filters used for stormwater pollution control.
Stormwater runoff occurs when precipitation flows over the ground and can include
suspended solids, oil and grease, toxic metals, nutrients, and microbial pathogens
(Urban Drainage and Flood Control District, 2008b). Stormwater Best Management
Practices (BMPs) are constructed to remove contaminants from stormwater before
these contaminants enter receiving bodies. Colorado requires stormwater to be treated
to the maximum extent practical, and stormwater BMPs provide significant
reductions for numerous pollutants.
Sand filters are an example of a standard stormwater BMP which provide removal of
various contaminants (Figure 1-1). Sand filters routinely clog and maintenance is
required to remove this clogged layer. Studies suggest that using tire crumb rubber
instead of sand may reduce clogging in the filters (Tang, Butkus, & Xie, 2006, 2009;
Xie, Killian, & Gaul, 2007). If tire crumb rubber filters clogged less often, less
maintenance would be required, reducing the operational cost of the filter. Research
also suggests that tire crumb rubber could remove oil and grease from stormwater
better than conventional sand filters (Park, et al., 2003). Also, using tire crumb rubber
replaces a virgin material with a recycled one, thus avoiding the need to mine sand
from streambeds.
18


In Colorado, over 5 million waste tires were generated during the calendar year, 2008.
This number is slightly over the national average of one tire per person per year.
Approximately 80% of these tires were recycled, the vast majority of which were
burned for fuel (Snapp, 2009). Colorado has one of the largest inventories of
stockpiled tires, thus finding an innovative use for recycled tires is considered
imperative (Rubber Manufacturers Association, 2009). This research hoped to
explore a useful end market for recycled tires that could also improve water quality.
Preliminary research suggested a substantial demand for tire crumb rubber filters and
that millions of scrap tires could be utilized if this use proved advantageous (Gee,
2009). However, before evaluating whether tires could replace sand in stormwater
filtration, the toxicity of the tire crumb rubber was examined. The results indicated
that while tires leach contaminants, the concentration may be low enough so that the
use may still prove viable. Next, experiments were conducted to determine whether
tire crumb rubber filters are effective for stormwater pollution control.
In order to better understand how tires may be utilized in stormwater filtration, a
basic understanding of stormwater management, scrap tire management, and tire
crumb rubber is needed.
1.2 Stormwater Management
When precipitation runoff flows over impervious surfaces, water collects pollutants
and debris which are then discharged into lakes, rivers and streams. This stormwater
runoff can contribute significantly to the pollution in receiving waters. Urbanization
also increases the flow rate, frequency and duration of stormwater which can result in
scouring of rivers and streams. Pollutants of concern in stormwater include nutrients,
metals, solids, oxygen demands, oil and grease, and pathogens. Table 1-1 lists the
main contaminant concentrations found in stormwater in the Denver Metropolitan
Area. Contaminants in stormwater can originate from agriculture, construction,
industrial activities, atmospheric deposition, sewers, parking lots, gasoline stations, as
well as other sources. Stormwater BMPs are used to mitigate the impacts of
stormwater discharging into receiving bodies (Figure 1- 2).
19


Table 1-1: Land-Use Average Event Mean Concentrations of Stormwater Runoff in
the Denver Metropolitan Area (Urban Drainage and Flood Control District, 2008b)
Constituent Unit Industrial Commercial Residential Undeveloped
Nitrate plus Nitrite (mg/L) 0.91 0.96 0.65 0.50
Total Kjeldahl Nitrogen (mg/L) 1.8 2.3 2.7 2.9
Total Phosphorus (mg/L) 0.43 0.42 0.65 0.40
Copper, Total Recoverable (pg/L) 84 43 29 40
Lead, Total Recoverable (Pg/L) 130 59 53 100
Zinc, Total Recoverable (Pg/L) 520 240 180 100
Total Suspended Solids (mg/L) 399 225 240 400
Total Dissolved Solids (mg/L) 58 129 119 678
Chemical Oxygen Demand (mg/L) 232 173 95 72
20


Figure 1-2: Stormwater samples before and after passing through a sand filter (Urban
Drainage and Flood Control District, 2008a).
1.3 Scrap Tire Management
According to the EPA, more than 2 billion scrap tires are currently stockpiled in the
United States, and 280 million tires are disposed annually (USEPA, 2010). The
Rubber Manufacturers Association (RMA) estimates that about 4595.7 thousand tons
of scrap tires were discarded in 2007, representing each person discarding one tire per
year (Figure 1-3). According to RMA, from 2005-2007, 54.1% of recycled tires were
burned for fuel, while 12.2% of recycled tires were used in civil engineering
applications. Although scrap tires in stockpiles have been reduced by nearly 90
percent since 1990, in 2007, about 594.0 thousand tons of scrap tires were landfilled
in the United States (RMA, 2008).
21


Figure 1-3: Stockpiled tires. More than 2 billion tires are currently stockpiled in the
United States and 280 million are added annually (En Tek, 2011).
Over 5 million waste tires were generated in Colorado during the calendar year 2008.
According to the Colorado Department of Public Health and Environment, the use of
tire-derived aggregate (TDA) in civil engineering markets has declined since 2005. In
Colorado, nearly 50 million scrap tires are stockpiled. Alabama, Arizona, Colorado,
Massachusetts, Michigan, New York and Texas contain over 85 percent of the scrap
tires remaining in stockpiles. Landfilling scrap tires can cause problems due to the
tendency of tires to rise to the surface, which can harm landfill covers. Stockpiled
tires can create breeding grounds for mosquitoes and other pests as well as creating
large risks for hazardous fires. Discarded tires are not categorized as hazardous
material, but tire facilities that have caught on fire have been categorized as superfund
sites. These tire fires can generate unhealthy smoke and toxic oils, hazardous for both
human and environmental health (Rubber Manufacturers Association, 2009).
Colorado's waste tire program is funded by a $1 per tire fee levied on all waste tires
turned in to tire dealers at the time of purchase of new tires. $0.50 of the $1 is used to
provide low-interest loans to recycling businesses and $0.50 is used to clean up waste
tire stockpiles and encourage beneficial recycling. Colorado also offers a waste tire
processing and grant program to provide grants to counties and municipalities for the
removal of waste tires, and to encourage recycling and reuse of these waste tires
(EPA 2010).
22


1.4 Tire Crumb Rubber
Tire crumb rubber is produced when recycled tires are ground and the fiber and steel
belts are removed (Figure 1-4). Tire crumb rubber has a granular texture and ranges
in size from very fine powder to sand-sized particles and up to 3/8-inch pieces (Texas
Natural Resource Conservation Commission, 1999). Tire crumb rubber is used in
various applications including infill for turf fields, mulches, crumb rubber modified
asphalt and other civil engineering applications, as well as molded and extruded
products. Tire crumb rubber has a density between 1130-1160 kg/m3 (Tang, et al.,
2006), and ten to twelve pounds of tire crumb rubber can be derived from one scrap
passenger tire (Pierce & Blackwell, 2003).
Figure 1-4: 6M tire crumb rubber distributed by AcuGreen.
23


2. Literature Review
This chapter will provide an overview of the information on the toxicity of tire crumb
rubber found in the literature. Many studies evaluate the toxicity of tires to aquatic
organisms, while others quantify the toxic chemicals leaching from the rubber.
Knowledge of studies that have previously researched the toxicity of tire rubber can
help in understanding the potential risks associated with using the material in
stormwater filtration.
2.1 Toxicity
Applications utilizing recycled tire material are steadily increasing, however, tire
leachate can have negative impacts on aquatic life. Based on the literature, zinc is the
most significant water quality concern associated with using crumb rubber in
environmental applications where the tire material contacts water (Bocca, Forte,
Petrucci, Costantini, & Izzo, 2009; Gualtieri, Andrioletti, Vismara, Milani, &
Camatini, 2005; Gualtieri, Rigamonti, Galeotti, & Camatini, 2005, Mantecca, et al.,
2007; Nelson, Mueller, & Hemphill, 1994; Wik, 2007; Wik & Dave, 2006). Zinc is
added to tires during manufacturing, representing approximately 1% of tires by
weight. At elevated concentrations, zinc has been shown to cause a range of
reproductive, developmental, behavioral, and toxic responses in a variety of aquatic
organisms (Councell, Duckenfield, Landa, & Callender, 2004).
Wik and Dave (2009) provide a review of the ecotoxicological effects of tire wear
particles in the environment. The review focuses on the toxicity of tire leachates using
different leaching procedures and test organisms. Various other studies also research
the effects of tire leachate on differing aquatic organisms (Birkholz, Belton, &
Guidotti, 2003; Day, Holtze, Metcalfesmith, Bishop, & Dutka, 1993; Gualtieri,
Andrioletti, et al., 2005; Hartwell, Jordahl, & Dawson, 2000; Hartwell, Jordahl,
Dawson, & Ives, 1998; Nelson, et al., 1994; Sheehan, Warmerdam, Ogle, Humphrey,
& Patenaude, 2006; Wik, 2007; Wik & Dave, 2005, 2006).
Key findings in the literature regarding leaching of zinc:
More zinc leaches from rubber with greater surface area (Wik & Dave, 2009).
With an increased tire particle to liquid ratio, the amount of zinc leached
decreases due to particle aggregation causing decreased surface area
(Gualtieri, Andrioletti, et al., 2005).
24


Zinc leaches at greater concentrations when the pH is lower (Gualtieri,
Andrioletti, et al., 2005).
The acceptability of zinc inputs into receiving waters depend on the waters
susceptibility to increased zinc (Kanematsu, Hayashi, Denison, & Young,
2009).
The concentration of zinc leaching from tires decreases from 30 days vs. 60
days (Nelson, et al., 1994).
Mortality or aquatic organisms decreased after sequential leaching periods
(Hartwell, et al., 2000; Wik, Nilsson, Kallqvist, Tobiesen, & Dave, 2009)
Most of the toxic constituents appear to leach from the surface of the tire chips
relatively quickly and toxic chemicals do not appear to continually leach from
the tires (Hartwell, et al., 1998).
Tire leachate is less toxic as salinity increases (Hartwell, et al., 2000).
The percent of zinc that leached from the tires increased when the ratio of tire
particles to liquid decreased (Wik, et al., 2009).
The organisms sensitivity to the tire leachate can probably be explained by
the sensitivity of the organism to zinc (Wik, et al., 2009).
Zinc contributes most to the risk of using tire crumb rubber in turf fields
(Bocca, et al., 2009).
Given that rubber has an approximate zinc content of 1% by weight, 50% of
the zinc in the tire crumb rubber was leached during the digestion test
(Kanematsu, et al., 2009).
The use of tire rubber in stormwater BMPs is dependent on the ability of the
receiving body to receive increased levels of zinc (Kanematsu, et al., 2009).
In one study, with a solid to liquid ratio of 10 g/L tire crumb rubber, 10% of
the cumulative zinc was leached. Using 1 g/L tire rubber, 20% of the zinc was
leached. 70% of the cumulative zinc leached from the 0.1 g/L tire loading
(Kanematsu, et al., 2009).
The concentration of zinc leaching from tire crumb rubber depends on zinc
oxide levels in virgin tire compounds, particle size distribution, and surface
area of rubber granulates (L. Pysklo, 2006).
The average zinc concentration in the leachate of truck derived tire crumb
rubber for a column test was approximately 16 times lower than a Synthetic
Precipitation Leaching Procedure test (New York State Department of
Environmental Conservation, 2009).
The Clean Water Act requires the EPA to develop criteria for water quality that
protects aquatic organisms as well as human health. The EPAs freshwater quality
25


criteria for zinc is 0.12 mg/L (EPA, 2011). This means that to ensure the protection of
aquatic organisms and human health, zinc concentrations must not exceed 0.12 mg/L.
Similarly, the EPAs stormwater discharge benchmark value for zinc is set to
0.117 mg/L for multi-sector general permits for industrial activities (US EPA, 1996).
A new comparison of leaching data found in the literature (Table 2-1) highlights a
large degree of variability in these data, which suggests the need for a more
systematic approach to understand the mechanisms and kinetics of zinc leaching.
Table 2-1: Summary of leaching data in the literature.
Study Temp. (C) pH Particle Size Liquid to solid ratio Contact Time Cz (mg/L)
3 44.7
4 10.5
5 24 h 6.5
6 5.2
7 50 mg/L 1.2
24 h 44.7
(Gualtieri, 48 h 14.5
Andrioletti, et al.. Ambient 10-80 pm 72 h 13.3
2005) 96 h 8.5
240 h 28.6
6 24 h 35.3
48 h 13.0
100 g/L 72 h 12.4
96 h 9.3
240 h 20.2
N.S. not specified in study
26


Table 2-1 (continued): Summary of leaching data in the literature
Study Temp. rc) pH Particle Size Liquid to solid ratio Contact Time Czn (mg/L)
(New York State Department of Environmental Conservation, 2009) 23 2 4.2 Crumb 50g/L 18 h 1.947
1.15
Column Test 0.291
0.2141
(Nelson, et al., 1994) Ambient 8.36 Tire Plugs 181 g/L 31 days 0.755
(Kanematsu, et al., 2009) 10 5 590 pm 50g/L 3 days 12.483
7 4.177
9 2.544
25 5 18.930
7 5.597
9 2.544
40 5 27.839
7 3.263
9 2.082
(Mattina, 2007) 23 2 7 3 mm 50 g/L 18 h 1.05
4.2 2.75
(Bocca, et al., 2009) 25 5 3-4 mm 62.5g/L 24 h 2.55
water 0.966
(Davis, Shokouhian, & Ni, 2001) Ambient 4.3 Abraded with rasp 1 g/L 24 h 3.4
(San Miguel, Fowler, & Sollars, 2002) 20 6.2 < 0.42 mm 50 g/L 48 h 0.578
Ambient 7.0 0.1 g/L 24 h 0.55
N.S. not specified in study
27


Table 2-1 (continued): Summary of leaching data in the literature
Study Temp. (C) pH Particle Size Liquid to solid ratio Contact Time Czn (mg/L)
5 d 1.46
9 d 2.56
10g/L 20 d 4.46
7 d 2.57
5 d 1.75
lid 2.16
Abraded with Rasp: 5 d 1.14
9 d 1.49
Tires worn lg/L 20 d 1.44
to some extent 7 d 0.54
5 d 0.13
(Wik, et al., 2009) Ambient N.S lid 0.18
9 d 0.25
20 d 0.41
0.1 g/L 7 d 0.47
5 d 0.07
lid 0.12
5 d 2.24
AhraH^d 9 d 2.28
with Rasp: 10g/L 20 d 2.92
Heavily 7 d 1.08
Worn 5 d 0.52
lid 0.82
N.S. not specified in study
28


Table 2-1 (continued): Summary of leaching data in the literature
Study Temp. ro pH Particle Size Liquid to solid ratio Contact Time Czn (mg/L)
(Wik, et al., 2009) Ambient N.S. Abraded with Rasp: Heavily Worn lg/L 5 d 0.44
9 d 0.39
20 d 0.47
7 d 0.32
5 d 0.09
lid 0.12
0.1 g/L 9 d 0.16
20 d 0.38
(Minnesota Pollution Control Agency, 1990) Ambient 3 New Tires 1"square 428.9 g/L 24 h 18.6
3 Old Tires 1"square 437.4 g/L 23.5
5 New Tires 1"square 469 g/L 8.53
5 Old Tires 1"square 469 g/L 3.8
8 New Tires 1"square 250 g/L < 0.005
8 Old Tires 1"square 250 g/L < 0.005
(OEHHA, 2007) 37 C 2.3 N.S 0.2 g/ml 21 h 17
(Stephensen, et al., 2003) N.S 7.69 NS 100g/l N.S 2.29
(Park, et al., 2003) Ambient 6.9 5 cm Flow Through 1 m 1.3
6 m 0.140
(Hartwell, et al., 1998) 23 2 4.9 @5% Salinity 1 cm3 50g/L 7d 0.026
14 d 0.021
21 d 0.034
N.S not specified in study.
29


2.2 Filtration
Various studies have previously researched the use of tire crumb rubber in filtration.
Three studies have researched the use of tire crumb rubber to filter ballast water and
wastewater (Tang, et al., 2006, 2009; Xie, et al., 2007). These studies concluded that
tire crumb rubber can be used as filter media without significant loss of contaminant
removal. The use of tire crumb rubber researched in these studies has been patented.
Kocman et al. (2010) researched the use of tire crumb rubber in porous landscape
detention basins and ultimately recommended further research be conducted before
tire crumb rubber is used as filtration media due to leaching and the buoyancy of the
tire crumb rubber.
Other studies have research using tire crumb rubber mixed with sand in stormwater
filtration (Chang, Hossain, & Wanielista, 2010; Chang, Wanielista, & Daranpob,
2010; Chang, Wanielista, Daranpob, Xuan, & Hossain, 2010; Hossain, Chang, &
Wanielista, 2010; Ryan, Wanielista, & Chang, 2010; Xuan, Chang, Wanielista, &
Hossain, 2010). These studies were conducted by researchers at the University of
Central Florida and have trademarked the use of Black and Gold media. The Black
and Gold media mix consists of 45% expanded clay, 45% tire crumb, and 10% saw
dust. These studies conclude that the Black and Gold media effectively removes
the main contaminant of concern in stormwater.
Previous studies have evaluated the sorption of organic contaminants, metals, and oil
and grease onto tires (Calisir, et al., 2009, Kim, Park, & Edil, 1997; Knocke &
Hemphill, 1981, Lin, Huang, & Shern, 2008; H. S. Liu, Mead, & Stacer, 2000; Y.
Liu, Luo, Chen, Xie, & Yu, 2010; Oh, et al., 2008; Rowley, Husband, &
Cunningham, 1984). Many of these studies conclude that ground tire rubber shows
significant capacity as a sorbent.
30


3. Leaching Experiments
Because zinc is the main contaminant of concern in aquatic applications of tire
material, our study looked at the zinc leaching from the tire material. We did not
conduct testing on aquatic organisms, but rather focused on the qualitative and
quantitative mechanisms of zinc leaching. After reviewing leaching data in the
literature, we performed leaching tests to compare our results to those found in the
literature and to better understand the mechanisms of zinc leaching. We performed
the EPAs Synthetic Precipitation Leaching Procedure (SPLP), three batch leaching
tests, and three column leach tests. The SPLP test is specially designed to simulate the
leaching which occurs as a result of precipitation. The three additional batch leaching
tests focused on leaching over time, leaching from unwashed and washed rubber, and
leaching in agitated vs. quiescent water. The three column leach tests used washed
and unwashed rubber (Table 3-1).
Table 3-1: Leaching test overview.
Tested Zinc1 Tested Total Metals2 Washed Rubber3 Unwashed Rubber Agitated4 Not Agitated
SPLP Test X X X X
Batch Leach Test 1 X X X X
Batch Leach Test 2 X X X X
Batch Leach Test 3 X X X X X X
Column Leach Test 1 X X X
Column Leach Test 2 X X X
Column Leach Test 3 X X X
1 Testing performed by Colorado Analytical and Metro Wastewater Reclamation
Districts Laboratory
2 Analysis performed by Metro Wastewater Reclamation Districts Laboratory
3 The tire crumb rubber was washed following the ASTM standard
4 Samples were agitated with magnetic stir bars, SPLP specified agitation apparatus,
and metal paddles depending on experiment.
31


3.1 Methods
AcuGreen, a Colorado based tire recycling company, donated tire crumb rubber for
this research. AcuGreen provided us with four different sized samples of tire crumb
rubber. We performed a sieve test on the four different samples (Figure 3-1), and
concluded that the sample labeled 6M by the manufacturer best represented the C33
sand used in stormwater BMPs. The 6M tire crumb rubber has a d6o of 1 8mm and a
uniformity coefficient of 3.3. We decided not to sieve out the tire crumb rubber to
meet the ASTM standards for C33 sand because evidence in the literature suggested
that larger tire crumb particles could efficiently remove the main contaminants of
concern in stormwater (Tang, et al., 2006), and using the larger sized media would
reduce clogging, ultimately reducing filter costs. Additional sieving could add to the
cost of using the material.
Sieve Analysis of Tire Crumb Rubber
8-10M
6M
A Forever
Play
Forever
Mulch
Figure 3-1: Sieve Analysis of tire crumb rubber.
3.1.1 SPLP
To prepare for the SPLP test, we sieved out the original 6M sample into 4 different
sizes with diameters of 0.3mm, 0.6mm, 1.18mm, and 2.36mm. We performed the test
32


on each tire sample to better understand zinc leaching with respect to tire crumb size.
In this test, the tire crumb rubber is leached with an extraction fluid, pH of 5, for 18
hours in an end over end agitator (Figure 3-2).
Figure 3-2: Agitator used in the EPA's synthetic precipitation leaching procedure.
3.1.2 Batch
For the three batch tests, we filled 12, 600ml beakers with 25 g of 6M tires and
500 mL tap water. In the first batch leach test, six of the beakers were stirred at 60
RPMs with a standard jar testing apparatus. The other six beakers were set out on the
counter and not stirred. Samples were taken after 6 hr, 12 hr, 24 hr, 2 days, and
4 days.
In the second batch test, we tested a sample stirred by the metal paddle, an additional
sample stirred by a magnetic stir bar, and a third sample that was not stirred. In the 3rd
batch test, all stirred samples were stirred with magnetic stir bars. We also added two
additional samples, using unwashed tire crumb rubber instead of washed tire crumb
rubber.
3.1.3 Column
The acrylic column used in the leaching tests was 5ft tall and had an inner diameter of
4 inches (Figure 3-3). In each column experiment, the column was packed with tire
crumb rubber until the column was filled with 20 inches of tire crumb rubber. Once
filling the column was completed, a stainless steel wire mesh was added to the top of
the media to prevent the tire crumb rubber from floating. The column was filled with
tap water from the bottom at a rate of 80 mL/min. Filling the column from the bottom
better ensures that the media is fully saturated. Once the water level reached 1 inch
33


above the media, the column was filled from the top at a rate of 540 ml/mn. The
column was designed such that a fixed head of 36 in of water was maintained above
the tire crumb rubber media. Once the water reached the overflow valve, the release
valves were opened to allow the water to flow through the media. The effluent flow
rate in the first two tests was maintained at 8 gal/hr by use of a flow meter. We
performed two column leach tests with unwashed 6m tire crumb rubber and one
column leach test with washed 6m tire crumb rubber. The tire crumb rubber was
washed between a #16 and #200 sieve and tap water. The rubber was air dried and
then packed into the column using the method outlined above. The pH of the water in
the two tests was 6.8 and 6.6 respectively. In the third test, the tubing was
manipulated until the flow through the column was approximately 8 gal/hr to be
consistent with the first two column tests.
Figure 3-3: Testing Apparatus. Tap water was pumped from the barrels to the
columns and effluent samples were analyzed for zinc concentrations. This apparatus
was also used in the filtration experiments.
34


3.2
Results
3.2.1 SPLP
The findings from SPLP test indicate that the amount of zinc leaching from the tire
crumb rubber decreases with increasing tire particle radius (Figure 3-4). The highest
concentration of zinc leached was 1.3 mg/L.
Zinc Leached vs Tire Crumb Size
SPLP Test
1.40 -|
cr i-20 -
£ 1.00 -
f 0.80 -
8 0.60 -
a>
U 0.40 -
c
K 0.20 -
0.00 -

X

0.3
0.6
*A* 1.18
X -*- 2.36

6M
0.00 0.50 1.00 1.50 2.00 2.50
Size of Tire Rubber (mm)
Figure 3-4: Zinc leached versus average radius in the synthetic precipitation leaching
procedure (SPLP) test. Note: the 6M sample was a mixture of all represented sizes.
3.2.2 Batch
The results indicated that the rubber stirred with a metal paddle had less leaching than
the samples that were not stirred (Figure 3-5). This data was surprising and
inconsistent with data found in the literature. We thus conducted another study to
understand why the samples that were stirred had lower zinc concentrations. We
hypothesized that the metal paddles were removing zinc from the samples.
35


Zinc Leaching Over Time
Stirred vs Not Stirred in Batch Test 1
Figure 3-5: Zinc leached over time in batch leach test 1 while stirring and not stirring
the tire crumb rubber at pH 6.3.
The results from this second batch test showed similar zinc concentrations leaching
from all samples tested (Figure 3-6).
Zinc Leaching over Time
Batch Test 2
1.00 -I

M E 0.75 -
"O
0> .c u n a o 0.50 -
0.25 -
c
Ni 0.00 -
!
20 40 60 80 100
Not Stirred
Stirred with paddle
Stirred with
magnetic stir bar
Time (hr)
Figure 3-6: Zinc leaching over time in batch test 2 at pH 6.2.
36


These results suggest that the stirred samples leached higher concentrations of zinc
than the unstirred samples (Figure 3-7). Also, the samples containing unwashed
rubber leached higher amounts of zinc than the sample with washed rubber after 18
hours.
Zinc Leaching over Time
Batch Test 3
Not Stirred -
washed rubber
Stirred washed
rubber
Not Stirred-
unwashed rubber
X Stirred unwashed
rubber
Figure 3-7: Zinc leaching over time in batch test 3 at pH 6.7.
The data from the batch leaching tests reveal a high degree of variability in the data.
The literature suggests that leaching will significantly decrease in column leach tests
compared to the SPLP leach tests due to the agitation in the SPLP test (New York
State Department of Environmental Conservation, 2009). Column leach tests are
believed to be more representative of zinc leaching from tire crumb rubber in
stormwater BMPs.
3.2.3 Column
During all column leach tests, the column was filled from below to ensure saturation.
Therefore, the water came into contact longer at the beginning. This could explain the
large peak in the data. In column test 1 (Figure 3-8), the maximum concentration of
zinc leached was 2.63 mg/L. This maximum point occurred after 50 min. After 2 hr
37


and 30 min, the zinc concentration started to approach the EPAs freshwater criteria
of 0.12 mg/L.
Zinc Leaching Over Time
Column Test 1
Time (hr)
Figure 3-8: Zinc leaching over time in column test 1 at pH 6.4.
In column test 2, the leaching again spiked around 2.55 mg/L and after 20 hours, the
zinc concentration fell to 0.115 mg/L, which is below the EPAs freshwater limit
(Figure 3-9).
38


Zinc Leaching Over Time
Column Test 2
3.0
25
20 hr Leaching Test
Figure 3-9: Zinc leaching over time in column test 2 at pH 6.
Column test 3 was conducted to explore the difference in leaching from washed and
unwashed rubber (Figure 3-10). Compared to the peaks in tests 1 and 2, 2.63 and
2.55 mg/L respectively, the peak in column test 3 was much lower, 0.60 mg/L. This
data suggests that washing the tire crumb rubber may decrease the initial leaching.
However, the zinc concentration in column test 3 was 0.149 mg/L after 24 hours,
similar to column tests 1 and 2. Figure 3-11 plots column tests 2 and 3 on the same
plot to better see the results of washing the tire crumb rubber.
39


Zinc leached (mg/L) c Zinc Leached (mg/L)
Zinc Leaching Over Time
Column Test 3
0.7
Column Leach Test 3
3-10: Zinc leaching over time in column test 2 at pH 6.5.
Zinc Leaching Over Time
Washed vs. Unwashed Rubber
Time (hr)
Figure 3-11: Zinc leaching over time in column test 2 (unwashed) and 3 (washed).
40


4. Stormwater Filtration Experiments
While the tire crumb rubber leaches zinc, the concentration leached was not so high
as to make continuing this research unreasonable. The ultimate goal of this research
was to investigate stormwater filtration with tire crumb rubber media. To accomplish
this goal, we conducted seven stormwater filtration tests using tire crumb rubber as
the media in one filter column and sand as a comparison media in the other column.
4.1 Methods
The filtration experiments involved pumping synthetic stormwater from barrels into
two clear columns with a depth of 20 in of filter media. Water samples were taken of
the influent and the effluent after the water had passed through the media. The
columns used in this experiment were 5 ft tall, 4 in. in diameter, clear, acrylic
columns purchased from McMaster Carr. The synthetic stormwater, made from
adding chemicals to tap water (Table 4-1), was stored in 60 gallon barrels. Water was
pumped from the barrels to the columns using a Masterflex peristaltic pump with
Masterflex tubing. Piezometers were installed to measure changes in pressure through
the filter media. Each column had an overflow valve located 36 in above the filter
media.
41


Table 4-1: Recipe for simulated stormwater runoff (Davis, Shokouhian, Sharma, &
Minami, 2001; Hong, Seagren, & Davis, 2006).
Parameter Concentration (mg/L) Chemical Used Manufacturer
Nitrate 2 Sodium Nitrate (NaN03) Colorado Scientific Lab Grade
Nitrogen 4 Glycine (NH2CH2COOH) Arcos 98%
Phosphorus 0.6 Dibasic Sodium Phosphate (NaHP04) Fisher Scientific Certified ACS
Copper 0.08 Cupric Sulfate (CuS04) Arcos Organics 98+% Certified ACS
Lead 0.08 Lead Chloride (PbCl2) Arcos Organics 99%
Zinc 0.6 Zinc Chloride (ZnCl2) Arcos Organics 99.99% Extra Pure
Suspended Solids 150 Kaolin Powder Aqua Solutions
Dissolved Solids 120 Calcium Chloride (CaCl2) Fisher Scientific Certified ACS
COD 70 Dextrose (C6H1206) Fisher Scientific Certified ACS
Motor Oil 20 Pennzoil 10W-30 Pennzoil
Pathogens - South Platte River Water
42


Overall, we performed seven filtration experiments, testing for various parameters.
We conducted five saturated filtration tests and two unsaturated filtration tests. Table
4-2 outlines the testing overview for the filtration experiments.
Table 4-2: Filtration experiments testing overview
Nitrate Nitrate + Nitrite TKN Orthophosphate Total Phosphorous Zinc Lead Copper Total Metals TSS/TDS COD Oil and Grease Pathogens Flow Rates Head Measurements
Saturated Filtration Test 1 X X X X X X X X X
Saturated Filtration Test 2 X X X X X X X X X X X X
Saturated Filtration Test 3 X X X X X X X X X
Saturated Filtration Test 4 X X
Saturated Filtration Test 5 X X
Unsaturated Filtration Test 1 X X X X X X X X X
Unsaturated Filtration Test 2 X X
43


Water samples were collected and analyzed for nitrate, nitrate+nitrate (N03+N02),
total keldjal nitrogen (TKN), orthophosphate, total phosphorous (TP), total metals
sweep (Beryllium, Chromium, Manganese, Nickel, Copper, Zinc, Arsenic, Selenium,
Molybdenum, Silver, Cadmium, Antimony), total suspended solids (TSS), total
dissolved solids (TDS), COD, oil and grease, pH and pathogens. Table 4-3 provides
information on sample analysis.
Table 4-3: Testing laboratories and methods.
Parameter Shared Analytical Laboratory at UCD Metro Wastewater Reclamation Districts Laboratory Environmental and Hydrology Laboratory at UCD Colorado Analytical Methods
Nitrate X EPA 300.0
Nitrate+Nitrite X EPA 353.2 revision 2.0
TKN X EPA 350.1
Orthophosphate X EPA 300.0
Total Phosphorous X EPA 365.4
Zinc X X EPA 200.8 revision 5.4
Copper X X EPA 200.8 revision 5.4
Lead X X EPA 200.8 revision 5.4
TSS/TDS X Standard Method 2540 D /2540 C
COD X HACH Method 8000
Oil and Grease X EPA 1664(A)
Pathogens X HACH Method 1002
PH X
44


All saturated filtration tests followed the same general methodology. First, we packed
one column with sand and the other column with unwashed tire crumb rubber. In the
sand column, the sand was poured continuously into the column. In the tire column,
300 ml of tire was added at a time and then packed with a wooden tamp until the
media reached 20 inches. The columns were filled with tap water from the bottom at
80ml/min to saturate the media. Once the water was 2 in above the media, the
columns were filled with synthetic stormwater from the top at a rate of 540 ml/min
until the columns had a constant head of 36 in above the filter media. Once the water
reached 36 in above the filter media, the water was allowed to flow. The flow rate on
the flow meters was set to 8 gal/hr and the inflow was kept at 540ml/min.
The volume of filter media in the columns was 254 in3. Multiplying this by the
porosity of the tire media gave a pore volume of 143 in3 or 2.3 L. Similarly with a
porosity of 0.30 for the sand media, the sand pore volume was 1.3 L. The time for one
pore volume to pass through the tire media was 4.6 min. The time for one pore
volume to pass through the sand media was 2.5 min. In the saturated filtration test 1,
our initial plan was to run the test for 24 hr, however, the flow meter on the tire
column appeared to restrict the flow. In the practice run with synthetic stormwater,
the tires clogged less than the sand. However, in the saturated filtration test 1, the tires
appeared to clog faster than the sand. We believe this was due to the flow meter and
not the tires clogging. We based sampling times off of pore volumes in this test.
Saturated filtration tests 3 and 4 followed similar methods except using washed tire
crumb rubber instead of unwashed rubber. Saturated filtration test 5 focused on
clogging in the media. Unlike the previous tests, the media was not changed after the
saturated filtration test 4. To conduct the experiment we first drained the columns
after the saturated filtration test 4 and then scraped 3 in of media off the sand and tire
filters. We then refilled the columns with new tire and sand. Next we filled the
columns from the bottom at 80ml/mn with tap water to ensure saturation. When the
water was 2 in above the filter media, we started filling from the top with tap water
combined with 150 mg/L kaolin clay. When the water level was at the overflow, we
allowed the columns to flow. We did not collect any samples. We took head
measurements and timed the flow using a stopwatch and a 300ml beaker. We ran the
test for 6 hours.
For the unsaturated stormwater infiltration test 1, the columns were packed with sand
and tire crumb rubber following the same methods as in previous tests. Both
unsaturated filtration tests used washed tire crumb rubber. Shower heads were
45


attached to the top of the influent tubes to disperse the water evenly. The columns
were filled from the top at a rate of 380ml/mn for 20mn which was the equivalent to
36 in of water being pumped into the column. Each 36in added to the columns was
considered to be one flush. During the first flush, a sample was taken at Omin and at
15min for the tire column and at 0 and 35 min for the sand column. Different sample
times were due to the differing flow rates between the tire and sand filters. For the
subsequent flushes, samples are taken at 15 mn into each flush for both sand and tire
columns. A total of 7 flushes passed through the tire column and 5 flushes passed
through the sand column. The head measurements were not taken for the tire column
because the water did not pond.
The unsaturated filtration test 2 was performed to test for filtration of pathogens.
Instead of using the synthetic stormwater recipe previously mentioned, we collected
water from the South Platte in Denver, CO. We followed the same methodology for
the unsaturated filtration test 2 as the unsaturated filtration test 1. However, in this
unsaturated filtration tests, the tire column was packed with unwashed tire crumb
rubber. The sand column was packed with washed C33 sand. Water was collected
from the South Platte, a river flowing through Denver, Colorado. The water was
collected approximately 200 m downstream of Confluence Park. The water was
collected near the surface of a stagnant eddy. Only oil was added to the water. The
flow rates in either column were not controlled, thus the tire column flowed much
faster than the sand column. We tested 4 flushes with the sand and tire columns. We
then flushed the tire column at 2300 ml/mn for 20 mn for two flushes and samples
were taken after each flush.
4.2 Results
The following sections provide a summary of the data from the filtration tests. In the
summary tables below, the standard error, St, was calculated based on the greater of
the standard deviation in effluent concentrations or 5% for nutrients and metals and
10% for oil and grease. Appendix A-H contains the raw data collected during the
filtration experiments.
4.2.1 Nutrients
The influent and effluent samples in the experiments were analyzed for nitrate, nitrate
+ nitrite, TKN, and orthophosphate. The nitrate and orthophosphate analysis was
46


performed in the Shared Analytical Laboratory at the University of Colorado Denver
following the EPAs 300.0 method by ion chromatography. In this method, the
samples have a hold time of 48 hours. The nitrate and orthophosphate samples in
saturated filtration tests 1 and 2 were not analyzed within this time frame and thus do
not follow the standard; therefore, the results must be interpreted with caution. The
analysis for nitrate+nitrite, TKN, and total phosphorous followed standard procedures
and was analyzed within the proper holding time at Metro Wastewater Reclamation
Districts laboratory.
Overall, the percent removals for nutrients were inconsistent. Nutrient removal is a
biological process, and thus, we did not expect to see high removal efficiencies for
nutrients. In general, the sand column removed contaminants equally well or better
than the tire column. For complete results, please consult Figures A-l through A-12
in Appendix A.
47


Nitrate
100%
80%
S 60%
i
40%
| 20%
a.
0%
-20%
i TIRE
i SAND
Saturated Filtration Test 1 Saturated Filtration Test 2
11% 90%
51% 19%
Figure 4-1: Nitrate percent removal.
Table 4-4: Summary of Results for Nitrate.
Nitrate Tire mg/L S, mg/L Sand mg/L st mg/L
Saturated Filtration Test 1 Influent 0.74 0.04 4.95 0.25
Effluent 0.66 0.03 2.45 0.12
Saturated Filtration Test 2 Influent 4.18 0.00 5.78 0.00
Effluent 0.43 0.05 4.67 1.50
48


Nitrate+Nitrite
100%
80%
I 60%
|
40%
h 20%
CL,
0% -20% r t j
^ 1
Saturated Filtration Test 3 Unsatrated Filtration Test 1
TIRE 1% -1%
SAND 1% 5%
Figure 4-2: Nitrate+Nitrite percent removal.
Table 4-5: Summary of Results for Nitrate+Nitrite.
Nitrate + Nitrite Tire mg/L s, mg/L Sand mg/L st mg/L
Saturated Filtration Test 3 Influent 1.38 0.07 1.39 0.07
Effluent 1.37 0.15 1.38 0.12
Unsaturated Filtration Test 1 Influent 1.46 0.07 1.53 0.08
Effluent 1.47 0.15 1.46 0.10
49


Orthophosphate
100%
80%
15
o e 60%
QJ
oc 40%
e
u 20%
a> a,
0%
-20%
it
Saturated Filtration Test 1 Saturated Filtration Test 2
0% 20%
0% 47%
i TIRE
i SAND
Figure 4-3. Orthophosphate percent removal
Table 4-6: Summary of Results for Orthophosphate.
Orthophosphate Tire mg/L St mg/L Sand mg/L st mg/L
Saturated Filtration Test 1 Influent 0.98 0.05 0.98 0.05
Effluent 0.98 0.05 0.98 0.05
Saturated Filtration Test 2 Influent 0.80 0.04 1.346 0.07
Effluent 0.64 0 0.718 0.12
50


TKN
SB

o
E
X
c
o>
u
u
u
CL.
100%
80%
60%
40%
20%
0%
-20%
-40%
-60%
-80%
Saturated Filtration Saturated Filtration Unsaturated Filtration
Test 2 Test 3 Test 1
TIRE 79% -11% -18%
SAND 82% 35% -4%
Figure 4-4. TKN percent removal.
Table 4-7 Summary of Results for TKN.
TKN Tire mg/L st mg/L Sand mg/L st mg/L
Saturated Filtration Test 2 Influent 5.30 0.27 5.40 0.27
Effluent 1.12 0.06 0.99 0.04
Saturated Filtration Test 3 Influent 5.20 0.26 6.90 0.35
Effluent 5.79 2.89 4.50 1.13
Unsaturated Filtration Test 1 Influent 5.20 0.26 5.10 0.26
Effluent 6.12 1.10 5.28 0.20
51


TP
100%
HJ /O Saturated Filtration Saturated Filtration Unsaturated Filtration
Test 2 Test 3 Test 1
TIRE -10% 37% 17%
SAND 21% 52% 62%
Figure 4-5: TP percent removal.
Table 4-8: Summary of Results for Total Phosphorous.
Total Phosphorous Tire mg/L st mg/L Sand mg/L s, mg/L
Saturated Filtration Test 2 Influent 0.67 0.03 0.68 0.03
Effluent 0.74 0.02 0.54 0.10
Saturated Filtration Test 3 Influent 0.66 0.03 0.67 0.03
Effluent 0.42 0.12 0.32 0.15
Unsaturated Filtration Test 1 Influent 0.62 0.03 0.64 0.03
Effluent 0.52 0.01 0.25 0.14
52


4.2.2 Metals
As was expected, the tire crumb rubber added zinc in the tire column. The zinc
concentration in the effluent was greater than the zinc concentration in the influent.
Zinc was consistently removed in the sand column. The data for the copper filtration
has large variability. The copper removal in the tire column ranged from -6% to 85%
removal. In the sand column, percent removal ranged from -1% to 16% removal.
Lead was removed well in both the sand and tire columns. For complete results,
please consult Figures B-l through B-12 in Appendix B.
53


Zinc
150% 100% 50% 0% -50% -100% -150% J ^ J
Saturated Filtration Test 1 Saturated Filtration Test 2 Saturated Filtration Test 3 Unsaturated Filtration Test 1
TIRE -40% -76% -17% -15%
SAND 95% 95% 92% 89%
Figure 4-6: Zinc percent removal.
Table 4-9: Summary of Results for zinc.
Zinc Tire mg/L s, mg/L Sand mg/L st mg/L
Saturated Filtration Test 1 Influent 0.61 0.03 0.55 0.03
Effluent 0.85 0.04 0.03 0.00
Saturated Filtration Test 2 Influent 0.55 0.03 0.57 0.03
Effluent 0.96 0.33 0.03 0.00
Saturated Filtration Test 3 Influent 0.82 0.04 0.60 0.03
Effluent 0.96 0.37 0.05 0.04
Unsaturated Filtration Test 1 Influent 0.80 0.04 0.58 0.03
Effluent 0.92 0.17 0.06 0.04
54


Copper
100%
£ -20%
-40%
-60% 4
Saturated Saturated Saturated Unsaturated
Filtration Test 1 Filtration Test 2 Filtration Test 3 Filtration Test 1
TIRE 85% 13% -6% 9%
SAND 16% -1% 16% 34%
Figure 4-7: Copper percent removal.
Table 4-10: Summary of Results for copper.
Copper Tire mg/L St mg/L Sand mg/L st mg/L
Saturated Filtration Test 1 Influent 0.07 0.00 0.08 0.00
Effluent 0.01 0.00 0.06 0.00
Saturated Filtration Test 2 Influent 0.11 0.01 0.10 0.01
Effluent 0.09 0.01 0.10 0.05
Saturated Filtration Test 3 Influent 0.10 0.01 0.10 0.01
Effluent 0.11 0.05 0.09 0.02
Unsaturated Filtration Test 1 Influent 0.11 0.01 0.12 0.01
Effluent 0.10 0.01 0.08 0.02
55


Lead
120%
-40% -60% -L
Saturated Filtration Test 1 Saturated Filtration Test 2 Saturated Filtration Test 3 Unsaturated Filtration Test 1
TIRE 100% 0% 100% 83%
SAND 110% 27% 100% 100%
Figure 4-8: Lead percent removal.
Table 4-11. Summary of Results for lead.
Lead Tire mg/L S, mg/L Sand mg/L st mg/L
Saturated Filtration Test 1 Influent 0.04 0.00 0.0 0.00
Effluent -0.04 0.00 0.0 0.00
Saturated Filtration Test 2 Influent 0.09 0.00 0.2 0.01
Effluent 0.09 0.04 0.1 0.04
Saturated Filtration Test 3 Influent 0.07 0.00 0.1 0.00
Effluent 0.00 0.00 0.0 0.00
Unsaturated Filtration Test 1 Influent 0.06 0.00 0.1 0.00
Effluent 0.01 0.01 0.0 0.00
Gray shading represents samples with concentrations below the detection limit. St
could not be calculated for these samples.
56


4.2.3 TSS/TDS
The total suspended solids were removed well in both the tire and the sand columns.
However, the effluent samples taken from the tire column appeared cloudier than the
effluent samples from the sand column. As expected, the TDS was not removed well
in either the sand or column filters. For complete results, please consult Figures C-l
through C-10 in Appendix C.
57


TSS

E

oc
CJ
tj
La
o>
a.
120%
100%
80%
60%
40%
20%
0%
Saturated Filtration
Test 1
Saturated Filtration
Test 2
Unsaturated Filtration
Test 1
i TIRES
96%
101%
84%
'SAND
96%
102%
104%
Figure 4-9: TSS percent removal.
Table 4-12: Summary of Results for TSS.
TSS Tire mg/L st mg/L Sand mg/L st mg/L
Saturated Filtration Test 1 Influent 193.25 9.7 313.5 15.7
Effluent 7.5 0.4 13.13 0.7
Saturated Filtration Test 2 Influent 116 5.8 128 6.4
Effluent -0.692 13.9 -2.87 7.0
Unsaturated Filtration Test 1 Influent 140.23 7.0 140.9 7.0
Effluent 22.986 7.2 -5.11 6.7
58


TDS
100%
50%
I -50%
u
-100% -150%
Saturated Filtration Test 1 Saturated Filtration Test 2 Unsaturated Filtration Test 1
TIRES 39% -17% 1%
SAND 37% -32% -10%
Figure 4-10: TDS percent removal.
Table 4-13: Summary of Results for TDS.
TDS Tire mg/L s, mg/L Sand mg/L st mg/L
Saturated Filtration Test 1 Influent 1415 71 1405 70
Effluent 860 43 882.5 44
Saturated Filtration Test 2 Influent 760 38 586.67 29
Effluent 892.73 149 774.67 341
Unsaturated Filtration Test 1 Influent 158.67 8 115.2 6
Effluent 157.57 28 126.77 23
59


4.24 COD
In three of the six filtration tests in which COD removal was measured, the tire crumb
rubber added to the COD. In stormwater filtration test 4, river water from the South
Platte in Colorado was used, and the water was stored for two days. This increased
the total COD in the influent samples compared to other tests, possibly because
bacteria grew in the water while the water was stored. As with other parameters,
there exists a large degree of variability in the COD data. In general, the sand column
removed the COD better than the tire column. For complete results, please consult
Figures D-l through D-6 in Appendix D.
60


COD
120%
-OUVO Saturated Saturated Saturated Saturated Unsaturated Unsaturated
Filtration Filtration Filtration Filtration Filtration Filtration
Test 1 Test 2 Test 3 Test 4 Test 1 Test 2
TIRE -24% -37% 24% 80% -19% 34%
SAND 19% 11% -2% 95% -2% 35%
Figure 4-11: COD percent removal.
Table 4-14: Summary of Results for COD
COD Tire mg/L s, mg/L Sand mg/L st mg/L
Saturated Filtration Test 1 Influent 94 4.7 114 5.7
Effluent 117 5.8 92 4.6
Saturated Filtration Test 2 Influent 82 4.1 103 5.2
Effluent 112 7.7 91 1.6
Saturated Filtration Test 3 Influent 113 10.1 104 1.0
Effluent 86 9.0 106 11.9
Saturated Filtration Test 4 Influent 208 10.4 212 10.6
Effluent 41 2.1 11 0.6
Unsaturated Filtration Test 1 Influent 92 1.2 98 0.6
Effluent 110 8.7 99 0.9
Unsaturated Filtration Test 2 Influent 53 2.7 23 1.2
Effluent 35 1.8 15 0.8
61


4.2.5 Oil and Grease
Oil and grease was tested in saturated filtration test 4 and unsaturated filtration test 2.
Both the sand and tire columns removed the oil and grease with a relatively high
removal percentage. The influent level of oil and grease was much higher than what
would typically be seen in stormwater to test for a worst case scenario. For complete
results, see Figures E-l through E-4 in Appendix E.
Oil and Grease
120%
100%
| 80%
* 60%
2 40%
a
a.
20%
0%
TIRE 91% 89%
SAND 94% 58%
Figure 4-12: Oil and grease percent removal.
Table 4-15: Summary of Results for oil and grease.
Oil and Grease Tire mg/L st mg/L Sand mg/L st mg/L
Saturated Filtration Test 4 Influent 79 7.9 86 8.6
Effluent 7.0 0.7 <5.0 0.0
Unsaturated Filtration Test 2 Influent 65 6.5 12 1.2
Effluent 6.8 3.9 <5.0 0.0
Gray shading represents samples with concentrations below the detection limit. St
could not be calculated for these samples.
62


4.2.6 Pathogens
The removal of pathogens was tested in two experiments, during the saturated
filtration test 4 and unsaturated filtration test 2. Total coliforms were measured as an
indicator of pathogens using membrane filtration. In these filtration tests, water was
collected from the South Platte River in Denver, CO so that the water contained
coliforms. In general, the sand and tire columns had similar removal efficiencies for
total coliforms. The results are only preliminary as the number of coliforms colonies
on the membranes were above the standard for all experiments. For complete results,
please consult Figures F-l and F-2 in Appendix F.
Sand: Influent Effluent 1st Flush Effluent 4th Flush
/ .. . :+ : / **'i :* **': ..
'igure 4-13: Pathogen removal in the sand column unsaturated filtration test 2 with
water from the South Platte.
Tire: Influent Effluent 1st Flush Effluent 4th Flush

*5
>' 7
.
*.

AM *
*
. *
Figure 4-14: Pathogen removal in tire column during unsaturated filtration test 2 with
water from the South Platte.
63


4.2.7 Flow Rates
The flow rate was manually measured during the filtration tests. The unrestricted flow
was much greater in the tire column than the sand column due to the larger particle
size. In the saturated filtration tests, the flow rate in the tire column was set to match
the flow rate in the sand column at the beginning of each test through use of a flow
meter in saturated filtration test 1 and through manipulating the effluent tubing in all
remaining tests. During the unsaturated filtration tests, the flow rates were
unrestricted in both the tire and the sand columns. The sand column clogged faster
than the tire column in every test except saturated filtration test 1. We believe this
was due to a faulty flow meter, thus the flow meters were removed for the remaining
experiments. For complete results, see Figures G-l through G-3 in Appendix G.
4.2.8 Hydraulic Conductivity
Head loss measurements were taken during the saturated filtration experiments.
Pressure ports were installed in each column. Letting 0 cm be the top of the media,
the pressure ports were installed at 0.5, 2.6, 7.8, 18, 28.4, 38.5, 45.3 cm down the
media. Piezometer tubes were connected to the pressure ports and water levels in the
tubes were recorded during tests (Figure 4-3).
The hydraulic conductivity was calculated using the column area, flow rate data, head
loss data, and Darcys equation: q = K Thus, K = q ^. For complete
results, please consult Figures H-l through H-4 in Appendix H.
64


Figure 4-15: Piezometers and pressure ports for measuring the pressure difference
across the filter media.
65


5. Discussion
5.1 Zinc Leaching
Research in the literature indicates that the concentration of zinc leaching from tire
crumb rubber widely varies from study to study, which was confirmed by results from
this research. The maximum contaminant level set by the EPA for zinc in drinking
water is 5 mg/L, however, the EPA has set a zinc freshwater criteria limit of
0.12 mg/L. The maximum zinc concentration leached from the tire crumb rubber was
2.7 mg/L after 42 hours. Minimum zinc leaching concentrations approached the
0.12 mg/L freshwater criteria.
5.1.1 SPLP
We performed the EPAs SPLP test on the tire crumb rubber and tested for a total
metals sweep, which confirmed that zinc is the only metal of concern. The results
indicate that larger tire crumb rubber leaches smaller amounts of zinc than smaller
tire crumb rubber. This is due to the fact that smaller tire crumb rubber has a greater
surface area than larger rubber. Therefore, the smaller the tire particle, the
concentration of zinc leaching will be greater. The SPLP test represents a worst case
scenario since the rubber is agitated for 18 hours and in a solution of pH 5. The zinc
concentration leaching from the tires in the SPLP test was not great enough to
discontinue work on the remaining research.
5.1.2 Batch
The batch leaching tests explored batch leaching over time with washed and
unwashed tire crumb rubber which was agitated and not agitated. The zinc
concentration increased with time and zinc concentrations ranged from 0.2 to
4.5 mg/L. The data was highly variable, thus no significant difference was found
between agitated versus quiescent samples. Also, no significant difference was found
between washed versus unwashed samples.
5.1.3 Column
In the column leach tests, the columns were filled from the bottom to ensure
saturation. After the water was 2.5 cm above the tire crumb rubber, the columns were
66


filled from the top at an increased flow rate. Thus water at the top of the columns was
in contact with the rubber for a greater amount of time. The initial pulse of zinc
concentration was as high as 2.7 mg/L. However, the concentration rapidly decreased,
approaching the zinc freshwater criteria limit of 0.12 mg/L. When testing washed
crumb rubber, the results showed a similar initial pulse, however, the concentration
was reduced by half in comparison with unwashed rubber. This suggests that some of
the smaller tire particles were removed during washing. The long term zinc
concentrations approached the zinc freshwater criteria and were not significantly
lower than unwashed rubber.
5.2 Filtration Performance
As previously mentioned, in each filtration experiment we tested a wide variety of
parameters. Results from the filtration tests are broadly summarized in Table 5-1. As
with the batch and column leaching tests, there is a large degree of variability
between replicates. As seen in the table, the sand filter performed equally or better
than the tire crumb rubber filter for all parameters tested except two. The tire crumb
rubber filter performed better in regards to clogging and flow rate. The tire crumb
rubber granules were larger than the sand, thus the larger particles are expected to
have higher flow rates and greater resistance to clogging. The decision to use the
larger sized tire crumb rubber was deliberate for two reasons. First, we wanted to
compare a standard size of tire crumb rubber and sand that is readily available in the
industry. Secondly, literature suggests that the larger sized tire crumb rubber had
similar pollutant removal compared with smaller sand and therefore conveyed the
benefit of increased flow rates and decreased clogging without compromising
pollutant removal.
Table 5-1: Summary of performance of tire crumb rubber and sand filters.
Parameter Tire Better Similar Sand Better Comment(s)
Flow Rate X Only sand clogged.
Clogging X Only sand clogged.
Nutrients X Both filters poor.
Metals X
TSS X Both filters performed well.
COD X
Oil and Grease X Both filters performed well.
Pathogens X
67


6. Conclusions and Future Research
6.1 Conclusions
Evidence in the literature suggested that the benefits for using tire crumb rubber to
replace sand in stormwater filtration included:
Replacing a virgin material with a recycled material.
Less clogging, reducing filter maintenance and cost.
Increased removal of oil and grease.
Preliminary research evaluating the demand for tire crumb rubber filters concluded
that a significant number of discarded tires could be utilized in this manner if the use
proved advantageous, thus aiding in discarded tire abatement (Gee, 2009). We then
studied tire leaching and found zinc to be the main contaminant of concern when
using tire crumb rubber in aquatic applications. The concentration of zinc leaching
from the tire crumb rubber approaches the EPAs freshwater criteria limit of
0.12 mg/L, however, all leaching concentrations were above this level. The input of
zinc could be acceptable depending on the receiving bodys susceptibility to
increased concentrations of zinc. Based on our column leaching tests and on the batch
leach tests, washing the tire crumb rubber reduces the zinc leaching, at least in the
initial pulse. Therefore, washing the tire crumb rubber is recommended.
Regarding contaminant removal, the sand and tire filters had similar removal
efficiencies, even in the case of oil and grease. Because the tire crumb rubber has
similar but not enhanced removal capabilities and may also impair receiving water,
we do not recommend 100% tire crumb rubber filters be used in stormwater pollution
control. Tire crumb rubber used in mixed media filters may increase the flow rate
through the filters and decrease clogging, however, such a design should be evaluated
for zinc leaching before deployment. Another concern with using tire crumb rubber in
stormwater filters is that the tire crumb rubber floats when initially in contact with
water. Therefore, the rubber should not be used on the top layer of a granular media
filter without some mechanical restraint to prevent loss by floating.
6.2 Future Research
Using data collected during the first leaching test, we modeled the concentrations of
zinc leaching from the tire crumb rubber using HYDRUS-1D. This preliminary
modeling suggested that a general, mechanistic model of zinc leaching from the tire
68


crumb rubber can be created using an extensive set of experimental measurements.
Our data from the SPLP, batch and column leaching tests could be used to validate
this model. This type of model could facilitate understanding of zinc leaching when
tire crumb rubber is used in various environmental applications.
While 100% tire crumb rubber filters cannot be recommended due to zinc leaching, a
prospective solution would be to use mixed media filters. Combining the tire crumb
rubber with another material such as sand that would absorb the zinc leaching from
the rubber could decrease the amount of zinc leached from the tire crumb rubber. The
concentration of zinc in the effluent has been shown to decrease after passing through
soil. Therefore, the filter could alternatively be engineered so that the effluent water
discharges through soil before discharging into receiving waters.
69


APPENDIX
A. Nutrient Effluent Concentrations in Saturated and Unsaturated Stormwater
Filtration Tests
E.
4)
4-*
m
6
5 4-
4
3 -
2 -
1
Nitrate Effluent Concentration
Saturated Filtration Test 1
0 50 100 1 1 150 200 1 1 250 300 350
(a) Time (min)
1 -| 0.8 -
o 0.6 -
c/< o o k> ifck .. i. 1 .
fi -
C 100 200 1 300 400
Time (min) ,(b) Figure A-l: Nitrate effluent concentration (b) normalized data. in saturated filtration test 1
------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Tire Effluent
Sand Effluent
70


Nitrate Effluent Concentration
Saturated Filtration Test 2
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Tire Effluent
Sand Effluent
Figure A-2: Nitrate effluent concentration in saturated filtration test 2: (a) raw data
(b) normalized data.
71


N05 Effluent Concentration
Saturated Filtration Test 3
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Time (min)
Tire Effluent
----Sand Effluent
Figure A-3: Nitrate + nitrite effluent concentration in saturated filtration test 3 (a)
raw data (b) normalized data.
72


N05 Effluent Concentration
Unsaturated Filtration Test 1
Flushes
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Tire Effluent
----Sand Effluent
(b)
Flushes
Figure A-4: Nitrate + nitrite effluent concentration in unsaturated filtration test 1: (a)
raw data (b) normalized data.
73


TKN Effluent Concentration
Saturated Filtration Test 2
-------Tire Influent
Tire Effluent
Sand Influent
Sand Effluent
Time (min)
Tire Effluent
Sand Effluent
Figure A-5: TKN effluent concentration in saturated filtration test 2: (a) raw data (b)
normalized data.
74


TKN Effluent Concentration
Saturated Filtration Test 3
Time (min)
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Figure A-6: TKN effluent concentration in saturated filtration test 3: (a) raw data (b)
normalized data.
75


TKN Effluent Concentration
Unsaturated Filtration Test 1
(a)
Flushes
-------Tire Influent
Tire Eflluent
------Sand Influent
Sand Effluent
+Tire Effluent
Sand Effluent
(b)
Flushes
Figure A-7: TKN effluent concentration in unsaturated filtration test 1: (a) raw data
(b) normalized data.
76


Orthophosphate Effluent Concentration
Saturated Filtration Test 1
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Tire Effluent
-HiSand Effluent
Figure A-8: Orthophosphate effluent concentration in saturated filtration test 1: (a)
raw data (b) normalized data.
77


Orthophosphate Effluent Concentration
Saturated Filtration Test 2
(a)
Time (min)
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Tire Effluent
Sand Effluent
Figure A-9: Orthophosphate effluent concentration in saturated filtration test 2: (a)
raw data (b) normalized data.
78


Total Phosphorous Effluent Concentration
Saturated Filtration Test 2
(a)
Time (min)
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
4Tire Effluent
Sand Effluent
Figure A-10: Total phosphorous effluent concentration in saturated filtration test 2:
(a) raw data (b) normalized data.
79


Total Phosphorous Effluent Concentrations
Saturated Filtration Test 3
Time (min)
-------Tire Influent
Tire Effluent
---- Sand Influent
Sand Effluent
Tire Effluent
----Sand Effluent
Figure A-11: Total phosphorous effluent concentrations in saturated filtration test 3:
(a) raw data (b) normalized data
80


TP (mg/L) TP (mg/L)
Total Phosphorous Effluent Concentration
Unsaturated Filtration Test 1
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Flushes
Tire Effluent
Sand Effluent
(b)
Flushes
Figure A-12: Total phosphorous effluent concentration in unsaturated filtration test 1
(a) raw data (b) normalized data.


APPENDIX
B. Metals Effluent Concentrations in Saturated and Unsaturated Stormwater
Filtration Tests
Zinc Effluent Concentrations
Saturated Filtration Test 1
Time (min)
(a)
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Tire Effluent
Sand Effluent
|bj Time (min)
Figure B-l: Zinc effluent concentrations in saturated filtration test 1: (a) raw data (b)
normalized data.
82


Zinc Effluent Concentrations
Saturated Filtration Test 2
Time (min)
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Figure B-2: Zinc effluent concentrations in saturated filtration test 2: (a) raw data (b)
normalized data.
83


Zinc Effluent Concentrations
Saturated Filtration Test 3
Time (min)
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Figure B-3: Zinc effluent concentrations in saturated filtration test 3: (a) raw data (b)
normalized data.
84


Zinc Effluent Concentrations
Unsaturated Filtration Test 1
0 1 2 3 4 5
Flushes
Flushes
(b)
Figure B-4: Zinc effluent concentrations in unsaturated filtration test 1
(b) normalized data.
Tire Influent
Tire Effluent
- Sand Influent
Sand Effluent
Tire Effluent
Sand Effluent
: (a) raw data
85


Copper Effluent Concentrations
Saturated Filtration Test 1
(a)
Time (min)
-------Tire Influent
Tire Effluent
Sand Influent
Sand Effluent
0.9
0.8
0.7
0.6
o 0.5
u
u 0.4
0.3
0.2
0.1
0
Tire Effluent
----Sand Effluent

0 100 200 300 400
(b)
Time (min)
Figure B-5: Copper effluent concentrations in saturated filtration test 1: (a) raw data
(b) normalized data.
86


Copper Effluent Concentrations
Saturated Filtration Test 2
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Tire Effluent
B--Sand Effluent
Figure B-6: Copper effluent concentrations in saturated filtration test 2: (a) raw data
(b) normalized data.
87


Copper Effluent Concentrations
Saturated Filtration Test 3
Figure B-7: Copper effluent concentrations in saturated filtration test 3
(b) normalized data.
Tire Influent
Tire Effluent
Sand Influent
Sand Effluent
Tire Effluent
Sand Effluent
: (a) raw data
88


Copper Effluent Concentrations
Unsaturated Filtration Test 1
(a)
Flushes
Figure B-8: Copper effluent concentrations in unsaturated filtration test
data (b) normalized data.
Tire Influent
Tire Effluent
Sand Influent
Sand Effluent
Tire Effluent
Sand Effluent
1: (a) raw
89


Lead Effluent Concentrations
Saturated Filtration Test 1
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Tire Effluent
Sand Effluent
Figure B-9: Lead effluent concentrations in saturated filtration test 1: (a) raw data (b)
normalized data.
90


Lead Effluent Concentrations
Saturated Filtration Test 2
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Tire Effluent
Sand Effluent
Figure B-10: Lead effluent concentrations in saturated filtration test 2: (a) raw data
(b) normalized data.
91


Lead Effluent Concentrations
Saturated Filtration Test 3
i -i
0.9 I
0.8 j
_ 0.7
^ 0.6
0 500 1000 1500
Time (min)
(b)
Figure B-l 1: Lead effluent concentrations in saturated filtration test 3:
(b) normalized data.
----Tire Influent
Tire Effluent
-- Sand Influent
Sand Effluent
Tire Effluent
Sand Effluent
(a) raw data
92


Lead Effluent Concentrations
Unsaturated Filtration Test 1
(a) Flushes
Flushes
(b)
Figure B-12: Lead effluent concentrations in unsaturated filtration test
(b) normalized data.
Tire Influent
Tire Effluent
Sand Influent
Sand Effluent
-Tire Effluent
-Sand Effluent
1: (a) raw data
93


APPENDIX
C. TSS and TDS Effluent Concentrations in Saturated and Unsaturated Stormwater
Filtration Tests
TSS Effluent Concentrations
Saturated Filtration Test 1
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Tire Effluent
Sand Effluent
Figure C-l: TSS effluent concentrations in saturated filtration test 1: (a) raw data (b)
normalized data.
94


TSS Effluent Concentrations
Saturated Filtration Test 2
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Tire Effluent
Sand Effluent
Figure C-2: TSS effluent concentrations in saturated filtration test 2: (a) raw data (b)
normalized data.
95


TSS Effluent Concentrations
Saturated Filtration Test 4
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Figure C-3: TSS effluent concentrations in saturated filtration test 4: (a) raw data (b)
normalized data.
96


TSS Effluent Concentrations
Unsaturated Filtration Test 1
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Figure C-4: TSS effluent concentrations in unsaturated filtration test 1: (a) raw data
(b) normalized data.
97


TSS Effluent Concentrations
Unsaturated Filtration Test 2
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Tire Effluent
- HiSand Effluent
Figure C-5: TSS effluent concentrations in unsaturated filtration test 2: (a) raw data
(b) normalized data.
98


TDS Effluent Concentrations
Saturated Filtration Test 1
(b)
Figure C-6: TDS effluent concentrations in saturated filtration test 1
normalized data.
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Tire Effluent
-Sand Effluent
: (a) raw data (b)
99


TDS Effluent Concentrations
Saturated Filtration Test 2
Time (min)
-------Tire Influent
Tire Effluent
------ Sand Influent
Sand Effluent
Figure C-7: TDS effluent concentrations in saturated filtration test 2: a) raw data b)
normalized data.
100


TDS Effluent Concentrations
Saturated Filtration Test 4
(a)
Time (min)
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
Tire Effluent
Sand Effluent
Time (min)
(b)
Figure C-8: TDS effluent concentrations in saturated filtration test 4: a) raw data b)
normalized data.
101


TDS Effluent Concentrations
Unsaturated Filtration Test 1
-------Tire Influent
Tire Effluent
------Sand Influent
Sand Effluent
(b)
Tire Effluent
----Sand Effluent
Figure C-9: TDS effluent concentrations in unsaturated filtration test 1: a) raw data b)
normalized data
102