12. 1
Chapter One: Introduction
Figure 1.1: Villanova University Constructed Stormwater Wetland
(View from Upstream/Inlet Looking Downstream/Outlet)
1.1 Introduction
The primary purpose of the present study is to analyze the pollutant removal efficiency o
the Villanova University Constructed Stormwater Wetland (CSW) during both times of baseflow
and storm events. This research analyzes the presence of a trend in the pollutant removal
efficiencies throughout the different seasons of the year as well as in the removal efficienci
between the different pollutants. Additionally, while not part of this present research, the data
collected and analyzed add to the body of nutrient data for this CSW. A secondary aspect of the
study is the investigation of plant effects on the removals. Factors that impact nutrient removal
include the flow path, retention time, plant density and plant type. The Villanova University
CSW has a Phragmites australis invasion problem. Although P. austra
f
es
lis is very efficient at
moving nutrients, control regimes are used to remove P. australis from the CSW in order to
ival of the native plants. This poses a question: If P. australis is
re
allow for the continued surv

13. 2
effective at removing pollutants, why should it be removed from the CSW? A second
component of the present study, a plot study, aims to answer this question. The plot study is a
series of plots within the CSW with different plant types. As flow moves through each plot,
as surface water and groundwater, nutrients may be removed through physical, chemical and
biological action. Another question addressed in the plot study is: Are nutrients removed
through the plots? To answer these questions, the study will test the hypothesis of: A species
diverse CSW is more effective at removing pollutants than a P. australis dominated CSW. If th
studies show that native plants are just as or more effective at pollutant removal than P. austral
then P. australis control programs would be more substantiated, and the goal of maintaining a
species diverse CSW will receive an even larger desire for realization.
1.2 General Background
The objective o
both
e
is,
f the present study is to examine the nutrient removal efficiency of a
d Wetlands
rest
m
ar’s time will be analyzed in order to assess the functioning and seasonal performance
f a ma
ivil
rmwater
artnership (VUSP) in 2002. The mission of the VUSP is to foster the developing
omprehensive stormwater management field as well as aide the formation of public and private
partnerships through research on stormwater Best Management Practices (BMPs), directed
studies, technology transfer and education. The VUSP manages a collective research effort on a
functioning CSW. Constructed stormwater wetlands (CSWs) are designed to remove pollutants
from stormwater runoff via a variety of mechanisms: plant uptake, microbial breakdown of
pollutants, retention, settling and soil adsorption (Metropolitan Council, Constructe
Stormwater Wetlands, 2001). CSWs have low operating and maintenance costs, and they are
also aesthetically pleasing (EPA, Constructed Treatment Wetlands, 2004). The CSW of inte
is a green infrastructure located on the campus of Villanova University (Figure 1.1). Previous
studies have been performed on this CSW addressing the removal efficiencies during times of
storm events and baseflow (Rea, 2004; Woodruff, 2005). Both storm and baseflow events fro
over a ye
o ture CSW. The pollutants of interest in the removal studies are: total nitrogen, total
phosphorus, total orthophosphate, total chloride, total suspended solids, and total dissolved
solids.
The Pennsylvania Department of Environmental Protection and the Department of C
and Environmental Engineering of Villanova University created the Villanova Urban Sto
P
c

14. 3
variety of stormwater BMPs both on and in the vicinity of Villanova University’s campus in
Villanova, Pennsylvania (VUSP Mission, 2008); one such BMP is the Villanova University
CSW.
The Villanova University CSW was retrofitted from an existing dry detention basin
(Figure 1.2) in October of 1999 with an EPA 319 Program grant from the Pennsylvania DEP
(Stormwater Wetland Project Report, 2008). This detention basin acted more like a detention
pond, which treated stormwater flows from both the main and west campuses of Villanova
University, totaling an approximate total drainage area of 56.6 acres (Woodruff, 2005).
Figure 1.2: Original Dry Detention Basin
(Rea, 2004; Stormwater Wetland Project Report, 2008)
Water quality considerations were not taken into account in the original design of the dry
detention basin (Figure 1.3). The basin was designed with the intended purpose of reducing and
managing stormwater runoff flows from Villanova’s campus. Runoff entered the basin from two
inlet pipes and sheet flow from a parking lot. (EPA, Section 319 Success Stories, 2007) The dry
detention basin was constructed with an outlet structure designed to pass the 25, 50 and 100-year
storms (Woodruff, 20 basin dry during
periods of non-storm events. However, it was discovered that even though the basin would
05). It was built with a 12 inch underdrain that kept the

15. 4
remain dry, there was baseflow throughout the year in the underdrain, even during the summer
ce of the baseflow may be from a series of natural springs. The constant
baseflo ter
1999 drought; the sour
w made the site an ideal location for the creation of a stormwater wetland. (Stormwa
Wetland Project Report, 2008)
Figure 1.3: Plan of Original Dry Detention Basin
(Stormwater Wetland Project Report, 2008; Woodruff, 2005)
1.3 Site Retrofitting
The design concepts presented in the Pennsylvania Handbook of Best Management
Practices for Developing Areas (Pennsylvania Association of Conservation Districts, 1998) were
used during the retrofitting of the dry detention basin into the CSW. The retrofit of the dry
detention basin concentrated on retaining small storms while simultaneously not violating the
original stormwater peak flow controls mandated by law (EPA, Section 319 Success Stories,
2007). The CSW maintained the basin’s ability to moderate the two to 100-year storms, but it
also became a water quality treatment facility (Woodruff, 2005). The underdrain of the basin
was removed in order to allow for baseflow, wh h is a critical part of the CSW, to flow
throughout the ba dering wetland
ic
sin. Earthen materials were shaped into berms to create a mean

16. 5
channel in order to in bay was created in
order to allow for suspended particles to settle ou the water column. (Stormwater Wetland
In addition, the CSW was planted with a diverse selection of native
crease flow path distance (Figure 1.4). A sediment fore
t of
Project Report, 2008)
wetland plants (EPA, Section 319 Success Stories, 2007).
Figure 1.4: Design Plan for the Villanova University CSW
(Stormwater Wetland Project Report, 2008; Woodruff, 2005)
1.4 Site Description
The Villanova University CSW receives stormwater runoff from a 57 acre watershed;
approximately 32 acres of impervious surfaces such as parking lots, dormitories, school
buildings, railroads, highways and housing areas; approximately 16 acres of semipervious
rfaces, such as lawns; approximately seven acres of the watershed is made of pervious surfaces
such as trees; approximately one acre of the watershed consists of the CSW itself (Jones, 2008).
The CSW consists of two inlets, a sediment forebay, a meandering channel and an outlet
structure.
su

17. 6
ke up the inlet
tructure
nal to the
reten
lined with wetland plants, which help to increase roughness and promote friction between the
water flow and land, thus Wetland Project
Report, 2008) Low velocities allow
g Channel Flow Path
04; St Wetlan rt, 20
The inlet structure of the original dry detention basin was not altered during the
retrofitting of the site into the current CSW (Figure 1.4). Two main inlet pipes ma
structure of the CSW.
The sediment forebay was an addition during the retrofit of the dry detention basin
(Figure 1.4). The main purpose of the sediment forebay is to capture the sediment loads and
prevent them from exiting the CSW (Davis, 1995). It was placed offline from the outlet s
to aid in the prevention of resuspension.
The meandering channels were created during the retrofit of the dry detention basin
(Figure 1.5). The ability of a CSW to efficiently remove pollutants is directly proportio
tion time of the water. In order to increase the water’s retention time, meandering channels
were created to extend the flow path of water through the CSW. The meandering channels were
constructed with a minimal channel slope to allow for low velocities. The channels were also
creating low water flow velocities. (Stormwater
an increase in the retention time of water in the CSW, which
increases the pollutant removal efficiency. (Kadlec, 1995)
Figure 1.5: Meanderin
(Rea, 20 ormwater d Project Repo 08)

18. 7
The outlet structure of the original dry detention basin was alter g the construction
of the CSW (Figure 1.4). The outle ned with the purpose of maintaining the existing
flood control functionality while still s ricting low flows. (Stormwater
Wetland Project Report, 2008)
1.5 Wetland Plan
One of the goals in creating CSWs is to generate dense, diverse vegetation that mimics
that of nearby natural wetlands. The wetland plants are the h system as
they provide she t f w ita nt removal.
The plants selected (Table 1.1) are native to the south egion of ania, and their
growing requirem rop ions they w (Figure 1.4).
Table 1.1: Original Wetland Plant List
Common Name Scientific Name Common Name Scientific Name
ed durin
t was desig
upporting the CSW by rest
ts
earts of the wetland eco
lter and habita or organisms as ell as play a v l role in polluta
eastern r
in which
Pennsylv
ere plantedents are app riate to the locat
Sweet Flag Acorus calamus Arrow Arum
Peltandra
virginica
Swamp Milkweed
Asclepias
incarnata Pickerelweed
Ponteteria
cordata
New England Aster
Aster novae-
anglia Lizards Tail Saururus cernus
Blue-Joint Grass
Calamagrostis
canadensis
New York
Ironweed
Vernonia
noveboracensis
Fringed Sedge Carex crinata Smooth Alder Arnus serrulata
Lurid Sedge Carex lurida Red Chokeberry Aronia arbutifolia
Tussock Sedge Carex stricta Buttonbush
Cephalanthus
occidentalis
Blue Flag Iris Iris versicolor Sweet Pepperbush Clethra alnifolia
Cardinal Flower Lobelia cardinalis Silky Dogwood Cornus amomum
Blue Lobelia Lobelia siphilitica Blueberry angustifolium
Lowbush Vaccinium

19. 8
1.5.1 Phragmites australis
Phragmites australis invasion is an ongoing problem in many CSWs, including that of
illanova University. P. australis is an invasive species with a high salinity tolerance that is
ense patches and is effective at removing pollutants from the CSW; however, it
utcom
; a
ngs
e
d its
reproductive rhizomes (Maryland Department of Natural Resources, 2008).
belief
.6 CS
is the part of the CSW discharge, not attributable to direct runoff from precipitation
instead sustained by groundwater and other daily sources of inflow.
.7 Research Objective
The objective of this study is to examine the yearly pollutant removal trends seen in the
illanova University CSW. The removal efficiencies of each pollutant are analyzed on a
asonal and yearly basis during both times of baseflow and storm events. A plot study is used
order to gain a more thorough understanding of the differences in pollutant removal
efficiencies between native and invasive plant species. The results of the preliminary plot study
V
able to grow in d
o petes the native plants originally planted and species diversity has thereby decreased. To
maintain a species diverse CSW, it is imperative to control the rapid expansion of P. australis
control regime has been implemented which includes continuous cycles of glyphosate sprayi
and cuttings. Glyphosate, commercially known as Rodeo, is a broad spectrum aquatic herbicid
that is applied to the foliage of actively growing P. australis in order to kill the plant an
1.5.2 Plot Study
A plot study was conducted to compare the pollutant removal efficiencies of native
wetland plants and the invasive P. australis. The preliminary results demonstrate that a native
plant is equally or more efficient at removing nutrients than P. australis, supporting the
that a species diverse CSW is more effective at removing pollutants than a P. australis
dominated CSW. Consequently, these results give validity to a P. australis control plan.
1 W Flow
Direct runoff is overland flow that is caused by excess precipitation which is not stored in
depressions in the ground, intercepted, evaporated, transpired by plants or infiltrated into the
ground (Mays, 2005). The main source for direct runoff is precipitation from storm events.
Baseflow
events, which is
1
V
se
in

20. 9
help to demonstrate the importance of maintaining a species diverse CSW: namely that
preventing the invasion of exotic species helps to increase the efficiency of a CSW as a whole.
Chapter Two has a review of the literatur ent to this study. Chapter Three
delineates the methods used in the present study. Chapters Four and Five review the results and
present a discussion on pollutant fate for storm and baseflow conditions, respectively. Chapter
Six describes the plot study. Chapter Seven presents conclusions and suggestions for future
studies.
e pertin

21. 10
Chapter Two: Literature Review
2.1 Introduction
“When the well is dry, we know the worth of water.” Benjamin Franklin spoke these
wise words in 1746 in Poor Richard’s Almanac. Water is an infinitely valuable resource, and
steps must be taken to safeguard it for both ourselves and for future generations. The United
States has already taken many steps to protect its water resources. In 1948, Congress enacte
Federal Water Pollution Control Act, or Clean Water Act. This is the principal law which
governs pollution in the nation’s waters. In 1972, the Clean Water Act was revised and ame
with various programs for water qualit
d the
nded
y improvement. Many of these programs have thus been
xpanded and are still in use today. Further amendments were made to the Act in 1977, 1981
ment technology advancements, even more revisions might
be mad
e of fill
soil
etland Regulatory Authority, 2004)
2.3 Non
eric
e
and 1987, and with future water treat
e. (Copeland, 2002)
2.2 Regulations of Natural Wetlands
Section 404 of the Clean Water Act instituted a program to regulate the discharg
or dredged material into the waters of the United States. It regulates the depositing of sand,
and other fill materials into natural wetlands. Regulated water activities under this program
include: fill for development, water resource projects, infrastructure development, and mining
projects. Under Section 404, a permit must be received before dredged or fill material may be
discharged into wetlands. In order to receive a permit, one must demonstrate that steps have
been taken to avoid wetland impacts, to minimize the potential impacts on wetlands and to
provide compensation for any remaining unavoidable impacts. One such compensation is the
construction of artificial wetlands for the treatment of nonpoint sources of pollution. (EPA,
W
point Sources of Pollution
Nonpoint sources of pollution are the result of precipitation, land runoff, atmosph
deposition, infiltration, drainage, seepage, or hydrologic modification. As the runoff from
rainfall or melting snow moves across the ground, it collects and carries natural and human-made
pollutants and ultimately deposits them into lakes, rivers, wetlands, coastal waters and

22. 11
groundwater. Section 319 of the Clean Water Act was passed in 1987 to launch a national
program which controls nonpoint sources of water pollution. (EPA, National Managemen
Measures to Protect and Restore Wetlands and Riparian Areas for the Abatement of Nonpo
Source Pollution, 2005) Although it is unrealistic to believe that all nonpoint source pollution
can be eliminated, the EPA recognizes that the use of BMPs is an acceptable method of reducing
nonpoint source pollution, as they are structural or nonstructural methods preventing or r
sediment, nutrients, pesticides and other pollutants from being transported between the land and
surface or ground water (Division of Forestry and Wildlife, Best Management Practices, 200
2.4 Best Management Practices
t
int
educing
7).
ed wetlands, retention systems, detention systems, and alternative outlet
esigns. (Metropolitan Council, Best Management Practices, 2001) These green infrastructures
al life support system - an interconnected network of waterways,
wetland
urces
essential and innovative conservation practice for the twenty-first century
(Bened
d to
n
There are two major types of BMPs: Runoff Pollution Prevention and Stormwater
Treatment. Stormwater Treatment BMPs, as used in this study, are effective in filtering
stormwater, reducing the speed at which stormwater leaves a site, and reducing the volume of
runoff. There are various kinds of Stormwater Treatment BMPs: infiltration systems, filtration
systems, construct
d
are: “our nation’s natur
s, woodlands, wildlife habitats and other natural areas; greenways, parks and other
conservation lands; working farms, ranches and forests; and wilderness and other open spaces
that support native species, maintain natural ecological processes, sustain air and water reso
and contribute to the health and quality of life for America’s communities and people.”
(Benedict and McMahon, 2002). Green infrastructure helps to restore and protect ecosystems by
supplying a blueprint for future development that promotes ecological, social and economic
benefits. It is both an
ict and McMahon, 2002).
The focus of this study is CSW BMPs. CSWs are artificial wetland systems designe
maximize the removal of pollutants from runoff through various methods: microbial breakdow
of nutrients, plant uptake, retention, adsorption and settling (Metropolitan Council, Constructed
Wetlands Stormwater Wetlands, 2001). The function and design of CSWs emulates that of
natural wetlands.

23. 12
2.5 Natural Wetlands
A wetland is a region that is covered by shallow water and supports vegetation ad
for life in saturated soil conditions. Wetlands are a habit
apted
at for an extensive variety of plants and
nimals, and they also provide numerous services to mankind. They are dubbed “nature’s
tland plants helps to improve the quality of water as it
flows t t
by storing water during and after a rain event (EPA,
Econom ds
structed Stormwater Wetlands
ir
e runoff and the CSW, the greater the amount of pollutant removal. CSW design
a
kidneys” because the filtering action of we
hrough them (National Centre for Tropical Wetland Research, 2001). Wetlands intercep
water runoff and retain excess nutrients and pollutants that come from fertilizers, manure and
municipal sewage.
The dense plant cover of wetlands intercepts overland flow, which helps to protect
against soil erosion and sediment buildup (National Centre for Tropical Wetland Research,
2001). Wetlands act like natural sponges
ic Benefits of Wetlands, 2006). The water storage and retention capacities of wetlan
help to control floods. Wetland vegetation slows the velocity of flood waters and distributes
them in a more evenly fashion over the floodplain. Wetlands that are not filled to capacity with
storage water reduce flood peaks and slowly release floodwaters to downstream areas. The
water retention and storage capacity of wetlands also serve to allow wetlands within and
downstream of urban areas to counteract the increased rate of surface water runoff from
pavement and buildings. (EPA, Flood Protection, 2007)
2.6 Con
Since natural wetland systems are effective at improving water quality and preventing
floods, engineers and scientists construct artificial wetland systems that replicate the functions of
natural wetlands. CSW BMPs use natural processes involving wetland vegetation, soils and the
associated microbial life to improve water quality, support habitat life, increase biological
diversity, attenuate flooding and reduce peak discharges (Metropolitan Council, Constructed
Wetlands Stormwater Wetlands, 2001).
Constructed stormwater wetlands regulate stormwater runoff from a variety of both
impervious and vegetated sources ranging from roadways, parking lots, roofs, construction sites,
golf courses and lawns. CSWs help to intercept pollutants, such as nutrients, road salts, heavy
metals, petroleum, sediments and bacteria, from the stormwater runoff. The longer the contact
time between th

24. 13
aims to create the longest possible flow path in order to maximize the contact of stormwater with
the CSW; this is achieved by providing long flow paths at shallow depths. The
length s,
lizing
stormwater
be delivered in a sheet flow to the remainder of the CSW. Sediment forebays ought to
ast 10% of the CSW volume. Gabions, riprap or berms are used to separate the
remove
e sediments. To allow for this, a concrete bottom is often installed to support this machinery.
avis, 1995)
s to
the surfaces of
of these paths can be increased by adding berms to form meandering channels. (Davi
1995)
Constructed stormwater wetland design also includes a sediment forebay which slows the
stormwater inflow and absorbs its force while reducing peak storm flow volumes and equa
flow to the CSW. The sediment forebay traps heavier sediment loads and prevents them from
entering the rest of the CSW. These heavier sediments, namely sands and gravels, contain a
large amount of the pollutants. Removing them in the forebay helps to reduce the buildup of
sediment in the rest of the CSW, thus extending its life. The forebay also allows for
to
encompass at le
forebay from the rest of the CSW. The forebay must have access for heavy equipment to
th
(D
2.7 Plantings
Dense vegetative growth aides sedimentation and provides sites for microorganism
growth within the CSW. A diverse community of wetland plants is less vulnerable than low
diversity communities to disease and animals. The most diverse and dense plant growth usually
occurs in shallower areas, and more efficient pollutant removal also occurs in these areas.
(Davis, 1995) Plant species should be selected based on how well the CSW site matches their
environmental requirements. Hydroperiod, light conditions, and depth ranges are some factor
be considered. It is also important to use plants which are native to the region in which the CSW
is built. (Metropolitan Council, Constructed Wetlands Stormwater Wetlands, 2001)
2.8 Pollutants
This section will discuss the pollutants evaluated in the present study’s analysis.

25. 14
2.8.1 Nitrogen
The most important forms of nitrogen found in CSWs are nitrogen gas (N2), nitrite (N
nitrate (
O2),
NO3
-
), ammonia (NH3), and ammonium (NH4
+
). The chemistry of nitrogen removal is
comple
re
it.
position
a
, 1995)
trification rates begin to drop at 6◦
C and become repressed at 10◦
C (Picard et al.,
2005).
its
ntration of nutrients in the plant tissue. The desirable traits of a plant
for nut
r phenomenon because a
majorit
x. CSWs chemically transform nitrogen between its inorganic and organic states through
various mechanisms: volatilization, ammonification, nitrification, nitrate-ammonification,
denitrification, N2 fixation, plant and microbial uptake, ammonia adsorption, organic nitrogen
burial and ANNAMOX (anaerobic ammonia oxidation). Some of these mechanisms require
energy and others release energy that is used by organisms. These nitrogen transformations a
required for CSW ecosystems to function efficiently, and most of these chemical changes are
controlled via the production of catalysts and enzymes by the organisms in which they benef
(Vymazal, 2007)
A significant portion of organic nitrogen is converted to ammonia through decom
and mineralization processes in the CSW. Ammonia is oxidized to nitrate by nitrifying bacteri
in the aerobic process of nitrification; these bacteria grow on wetland vegetation. (Davis
Denitrification converts nitrate into nitrogen gas with the aid of denitrifying bacteria; this gas is
then released into the atmosphere (DeBusk, 1999). Nitrification is inhibited in the colder
months; ni
Some nitrogen is taken up directly by wetland plants and becomes incorporated into the
plant tissue through nitrogen assimilation. This process converts inorganic nitrogen into organic
compounds which serve as the building blocks for cells and tissues. The two most commonly
used forms of nitrogen in assimilation are ammonia and nitrate. They are assimilated through the
roots and shoots of submerged plants. The rate of nutrient uptake by a plant is limited by
growth rate and the conce
rient assimilation include rapid growth, high tissue nutrient content and the ability to
accomplish a high standing crop. (Vymazal, 2007)
Constructed stormwater wetlands are affected by the seasonal cycles of ambient
temperatures and solar radiation. Nutrient uptake is a spring-summe
y of assimilation occurs during the growing season. The CSW nutrient cycle is
continuous as the plant biomass decomposes over the winter, thus releasing nitrogen back into

26. 15
the CSW waters, where they again will be assimilated during the next growing season. (Picard e
al., 2005)
Numerous studies have been conducted to examine the nitrogen removal capabilities of
CSWs. Kadlec (1995) studied nitr
t
ogen removal in surface flow constructed wetlands treating
astewater. Nitrogen was present in various forms throughout the wetlands. Biota utilized both
um, while decomposition processes released organic nitrogen and ammonium
back in 0 g/m2
d
oval
ANZE
ighly portable element in CSWs, and it is involved in numerous
biologi d
d
wetland plants and therefore signifies a major link between organic and inorganic phosphorus
w
nitrate and ammoni
to the water. One turn-over of 3000 g/m2
of biomass at 3% nitrogen represented 9
of nitrogen transfer, which is considerable in comparison with most wastewater nitrogen
loadings. (Kadlec, 1995)
Reinhardt et al. (2006) examined nitrogen fluxes in a small CSW in Switzerland an
found the CSW removed 45 g/m2
of nitrogen per year, which corresponded to a nitrogen rem
efficiency of 27%. Denitrification supplied 94% of the nitrogen removal, while 6% of the
removed nitrogen built up in the sediments. (Reinhardt et al., 2006)
Birch et al. (2004) studied the efficiency of a CSW in removing contaminants from
stormwater in Sydney, Australia. Urban stormwater flowing into Port Jackson in Sydney was
highly contaminated with pollutant nutrients. A CSW treating this stormwater was studied
during rain events by collecting samples from both the inlet and outlet of the CSW. The mean
concentration of total nitrogen (TN) in the inflow to the CSW was 36 times greater than the
CC/ARMCANZ guideline values (0.1-0.5 mg/L N), and the average removal efficiency of
TN was 16%. (Birch et al., 2004)
2.8.2 Phosphorus
Phosphorus is a h
cal and soil-water interchanges. Dissolved phosphorus is present in both organic an
inorganic forms, and it is readily converted between the two. (Davis, 1995) Organic forms of
phosphorus are generally not biologically or chemically reactive in CSWs and are instead
removed when adsorbed by wetland soils. (DeBusk, 1999) Wetland soil is a major sink for
phosphorus, but removal decreases as adsorption sites become occupied. The length of this
removal period depends on the chemical adsorption capacity of the sediments. (Davis, 1995)
Orthophosphate is the only form of phosphorus thought to be used directly by algae an

27. 16
cycling nic
en the plants die in the fall.
Becaus
rates
,
riations of
hosphorus within a cold climate subsurface flow constructed wetland, and the average annual
emoval rate was found to be 46%. Tonderski et al. (2005) modeled the impact of
CSWs
the
removal on a seasonal basis (McCarey et al.,
2004). ase
in CSWs (Vymazal, 2007). Organic phosphorus can also be broken down into inorga
phosphorus through the process of mineralization. This inorganic phosphorus can then be
removed through chemical and biological processes such as plant uptake. (DeBusk, 1999)
Wetland plants uptake soluble reactive phosphorus through leaves, roots and shoots and
convert it into tissue phosphorus. Soluble reactive phosphorus can also be absorbed by wetland
soils and sediments. There are various phosphorus transformations in CSWs: soil accretion,
adsorption, precipitation, plant/microbial uptake, fragmentation and leaching, mineralization, and
burial. (Vymazal, 2007)
Even though the seasonal uptake of phosphorus by plants can be considerable, the
phosphorus is generally recycled back into the CSW annually wh
e of this, long term phosphorus removal by CSWs is limited. (Davis, 1995) Similarly to
nitrogen removal, phosphorus removal in CSWs varies on a seasonal basis. Higher removal
are seen in the growing season while lower removal rates occur in the winter months. However
temperature affects phosphorus removal less than nitrogen removal because phosphorus removal
is dominated more so by sediment adsorption than biological processes. (Picard et al., 2005)
Several studies have examined phosphorus removal in CSWs (McCarey et al., 2004;
Tonderski et al., 2005; Birch et al., 2004). All studies have reported removal efficiencies
between 10 and 46%. McCarey et al. (2004) monitored the spatial and temporal va
p
phosphorus r
on phosphorus retention in southern Sweden and found that the CSWs functioned as sinks
for total phosphorus (TP). The CSWs removed 10 to 31% TP. As previously mentioned, Birch
et al. (2004) studied the phosphorus removal potential of a CSW in Sydney, Australia. The mean
concentration of TP decreased from 0.14 to 0.12 mg/L as the stormwater runoff traveled from
inlet to the outlet, corresponding to an overall reduction of 15%.
Mass balances throughout a year long study period on a subsurface CSW indicated a net
removal of phosphorus in all circumstances except for during the spring season. Its results
demonstrated significant variation in phosphorus
A CSW study in Sweden showed that during the warmest months, there was an incre
in outflow concentrations of phosphorus, suggesting that changes in the TP cycling within the
CSWs were what controlled phosphorus removal during warmer periods. It was hypothesized

28. 17
that phosphorus release from both accumulating solids in the sediment and phytoplankton uptake
was responsible for the outflow concentration increases. (Tonderski et al., 2005)
2.8.3 Solids
Total suspended solids (TSS) are removed in a CSW primarily through sedime
filtration. TSS removal increases as the amount of vegetation and complexity of surfaces within
the CSW increase. Denser vegetative growth promotes longer detention times, which increases
the amount of sedimentation, and thus TSS removal. (Davis, 1995) Vegetation reduces the
turbulence and w
ntation and
ater velocity of the runoff. Sometimes particles flow into the plant stems and
aves, or they stick to the biofilm layers of the plants. Vegetation can shelter the particles from
d it is also possible for aggregates of the suspended solids to be formed through
floccul
wo
ally pass unaltered through CSWs.
(DeBus
ers
A majority of this chloride infiltrated into the wetland and moved laterally to the upland with
le
resuspension, an
ation within the CSW. (Braskerud, 2001)
Braskerud (2001) found that resuspension decreased 40% in four years and became
negligible in a five year old CSW. Birch et al. (2004) found the TSS removal efficiency of a
Sydney CSW to be between 9 and 46% for four high flow events. They also discovered that
significantly higher TSS concentrations were found in the effluent than in the influent during t
extremely high flow events. These two events had TSS removal efficiencies of -98% and -67%.
TSS removal is less efficient during extreme storm events because the retention time of the
particles within the CSW is diminished as resuspension dominates. (Birch et al., 2004)
Total dissolved solids (TDS) are a combination of both inorganic and organic
compounds. Some of these compounds can be biologically or chemically utilized in the CSW.
However, TDS are generally composed of unreactive dissolved compounds that are not removed
in CSWs. TDS are similar to chloride ions because both gener
k, 1999)
2.8.4 Chloride
Studies often show that chloride passes through CSWs unaltered (Carlisle and
Mulamoottil, 1991; Rea, 2004). The main source of chloride comes from road salt, which ent
the CSW in snowmelt runoff. Hayashi et al. (1998) found that snowmelt runoff transported
between 4 and 5 kg/yr of chloride from the upland to a prairie wetland in Saskatchewan, Canada.

29. 18
shallow groundwater. The chloride then moved upward and accumulated near the surface while
water was removed via evapotranspiration. A portion of this chloride mixed with snowmelt
runoff a nal
r.
ownward flow of groundwater to the deep aquifer, but for the most part the chloride
moved through the wetland unchanged. (Hayashi et al., 1998)
ave shown chloride removal within CSWs. Mitchell and Karathanasis
(1995)
es.
necessity for plant physiological processes like the water-
splittin et
t,
ts.
f
nd was again returned to the wetland. This chloride cycle was a continuous and seaso
process, and around 5 kg of chloride were cycled between the upland and wetland each yea
The cycle occurred within 5-6 m of the ground surface. A minor amount of chloride escaped this
cycle in a d
Some studies h
simulated CSWs in a greenhouse study. One CSW had surface flow, and another had
subsurface flow. In a 12 week period, 25% chloride removal was found in the surface flow
wetland. Chloride removal was not influenced by plant species or substrate type, and there was
no apparent time effect. It was theorized that this chloride removal came from plant uptake,
anion exchange within the substrate, and adsorption in the form of metal-chloride complex
No chloride removal was observed in the subsurface flow experiment. This was likely due to the
saturation of the substrate anion exchange capacity or by competition for metals by other ions,
yielding fewer metal-chloride complexes. (Mitchell and Karathanasis, 1995)
Xu et al. (2004) found that T. latifolia and P. australis both took up chloride ions in a
greenhouse study. Chloride is a
g step of photosynthesis, and this might be a reason for its uptake by some plants. (Xu
al., 2004)
2.9 Invasive Species
Roadways supply suitable conditions for the invasion and establishment of exotic species
in CSWs. Roads alter soil density, salt levels, heavy metal levels, temperature, light levels, dus
surface waters, runoff patterns, sedimentation, and nutrient levels in the roadside environmen
Roads also further the dispersal of exotic species through the altering of habitats, stressing o
native species and providing easier movement by wild or human vectors. (Trombulak and
Frissell, 2000) Road construction modifies soils and causes disturbances to flood frequencies.
This stresses the native plants, and they cannot fend off invasive species, making possible the
spread of exotic plants. (Cusic, 2001) These exotic plants often establish colonies along

30. 19
roadsides or in disturbed habitats, and this causes major impacts on the biodiversity of a C
(Trombulak and Frissell, 2000).
Several studies have demonstrated how the salinity from road salts can decrease the
species diversity of a CSW. De-icing salts are generally composed of sodium chloride (NaCl),
but they can also be made of calcium
SW
chloride (CaCl2), potassium chloride (KCl) and magnesium
ant
y
in
ly salt-tolerant and is able to invade a colony of native
plants i
in northeastern Illinois. Marsalek
(2003) to a less
or
e
olonize both high
and low s
arsh
linities
chloride (MgCl2) (Trombulak and Frissell, 2000). Mature plants are generally more salt-toler
than seeds and seedlings, and some plant species are more resilient to salt than others. Road salt
has the capability of influencing the vegetative diversity of a freshwater CSW by substantiall
affecting seedling development and interspecific competitions. (Miklovic and Galatowitsch,
2005) Miklovic and Galatowitsch (2005) examined the effect of the addition of NaCl to a
greenhouse wetland microcosm. Eleven native plants were used in this microcosm. Five NaCl
treatments and two Typha angustifolia (cattail) treatments were assigned to the native plants
the microcosm. T. angustifolia is fair
n a CSW receiving high salt loads. Species diversity decreased in the NaCl treatments,
and it decreased more so in the NaCl and T. angustifolia treatments, suggesting that T.
angustifolia outcompeted the native species in the salt-laden environment. (Miklovic and
Galatowitsch, 2005) Panno et al. (1999) found similar results when T. angustifolia replaced the
native vegetation in a road salt laden fen-wetland complex
also described how road salt discharges caused another CSW ecosystem to shift
desirable species, Typha latifolia.
Phragmites australis is another undesirable salt-tolerant species. Disturbances along
roadways such as ditch digging, the application of de-icing salts, and runoff nitrogen input fav
the invasion of common reed colonies, such as P. australis, both along the roadways and in
CSWs. (Jodoin et al., 2008) Richburg et al. (2001) found that high salt concentrations from road
de-icing salts diminished the species diversity within a Massachusetts wetland. Many of th
native plants were less salt-tolerant than P. australis. P. australis was able to c
salt concentration areas within the wetland, and as a result the native plant colonie
diminished. (Richburg et al., 2001)
P. australis has a wide salinity tolerance and inhabits both freshwater and brackish m
environments. It has the ability to incorporate salts via ion accumulation, and it develops
osmotic regulatory pressure in its rhizomes. P. australis is able to reduce surface soil sa

31. 20
by seizing salts in its belowground tissues. An effect of this is a higher capacity for ammon
adsorption in the soil. (Windham and Lathrop, Jr., 1999)
P. australis is considered to be a wetland invasive species because of its quick
population expansions over the past century and its ability to rapidly dominate marsh plant
communities throughout the United States. P. australis grows in dense patches, and its height,
stem density and detrital accumulation reduce the available light to the marsh surface soil, as
well as reduce the air te
ium
mperature. As a result, the germination and establishment of other plant
species as
ly
produc is
y
e
cies.
ed toxic
oxygen in
ts
competitor for this limiting nutrient because it is able to oxygenate its rhizosphere. Buried
may be inhibited. The low light levels resulting from the biomass accumulation in are
of P. australis can drastically delay the spring thawing of marsh substrates, which further
prevents the establishment of non-P. australis species. (Meyerson et al. 2000)
Meyerson et al. (2000) described how P. australis is easily dispersed in water and
generally settles disturbed sites. P. australis reproduces via a dynamic system of rhizomes and
stolons, and it forms dense monotypic communities (Ailstock et al., 2001). A root can on
e aerial stems, whereas rhizomes produce both aerial stems and underground roots. Th
gives an advantage to P. australis because it is able to utilize the nutrients stored in the
rootstocks, thus starting its growing season in the early spring. (Geller, 1972) P. australis
communities expand peripherally through lateral rhizome growth. The aerial stems formed b
the rhizome buds remaining from the prior year’s growth are used mainly for photosynthesis and
seed formation. At the end of the growing season, all of the aerial stems die and are restored th
following year through the growth of these pre-existing rhizome buds. The rapid growth rate of
P. australis via seeds, rhizomes and rooted shoots helps to make it an effective invasive spe
(Ailstock et al., 2001)
Windam and Lathrop, Jr. (1999) explained how P. australis uses a Venturi-enhanced
convective throughflow of gases to supply oxygen to its roots and to eliminate accumulat
gases. This enhances the oxygenation of below-ground tissues and increases the release of
into the rhizosphere. P. australis has low internal resistance to air flow suggesting aga
that it has a substantially high potential for root-zone oxygen release, which is consistent with i
ability to grow in deep waters and its deep rhizome and root penetration. (Tanner, 1996)
P. australis dominance might also be aided by the limitation of nitrogen. Under low
redox potentials, plants are restricted in their ability to uptake nitrogen. P. australis is a superior

32. 21
organic nitrogen can be mineralized more quickly in this oxygenated environment, and as a
result, ammonium supply rates increase. Furthermore, slight increases in salinity levels inhibit
nitroge y
alt-
c
nd
.
s
than neighboring short grass communities in a tidal marsh in southern
New Je
lotype
a main reason for this rapid expansion in North America (Jodoin et al., 2008).
League et al. (2006) examined the differences between the native haplotype F and the
. australis in a brackish marsh in Delaware. Shoots from the exotic
strain e
s,
ify
n uptake, reduce the capacity of ammonium adsorption to soils, and limits productivit
due to the energy investments required to exclude salts. However, since P. australis is more s
tolerant than many native wetland plants, its nitrogen uptake is not limited. (Windham and
Lathrop, Jr., 1999) In a study of eight wetland plants in wetland mecocosms, Tanner (1996)
found that P. australis had the highest above-ground tissue concentrations of nitrogen. An
increase in the availability of nitrogen may be another mechanism by which P. australis
continues its successful invasion in wetland communities. (Windham and Lathrop, Jr., 1999)
Dr. Harsh Bais of the University of Delaware refers to P. australis as “natural killers”
(Wetlands Institute, 2008). Roots of P. australis produce 3,4,5-trihydroxybenzoic acid (galli
acid). This toxin targets tubulin, the structural protein that aids plant roots in maintaining their
cellular integrity. Gallic acid elevates levels of reactive oxygen species (ROS) in plant roots, a
ROS disrupts the root architecture of susceptible plants by damaging the microtubule assembly
Once this happens, susceptible plants die. (Rudrappa et al., 2007) This is one strategy that make
P. australis an effective invasive species.
Windham and Lathrop, Jr. (1999) found that P. australis plots had ten times the live
aboveground biomass
rsey. Interstitial water salinity was also 2% less in the P. australis plots (Windham and
Lathrop, Jr., 1999). In a similar study, Jodoin et al. (2008) reported that over the past fifty years,
the quantity and size of P. australis colonies have expanded substantially along roadsides in
Canada and the United States. The introduction of an exotic genotype of P. australis, hap
M, is thought to be
exotic haplotype M of P
merged from the rhizomes earlier than those from the native strain. Come March, there
were substantially more new shoots of the exotic strain when compared to those of the native
strain. By August, the exotic strain was 30% taller than the native strain, and it also contained
twice the amount of both the leaf and total biomass. The combined factors of greater biomas
longer rhizome internodes, and the earlier surfacing of new shoots from rhizomes help to just

33. 22
the exotic strain’s advantage over the native strain as well as the means of its invasive nature.
(League et al., 2006)
Saltonsall (2002) found that the native haplotype of P. australis still remains in its
original range throughout North America. However, throughout this range there has been a rapid
expansion of the exotic haplotype M. It has replaced native types throughout New England, and
it has b
ductivity
nd Kadlec (2001) found that a greater species
diversity and species richness increased productivity in wetland mesocosms. Larger species
chness increased the amount of above-ground biomass. Each of the five plant species exerted
ifferent effects on above-ground biomass, the recovery of biomass after a disturbance, total
ry of respiration. (Engelhardt and Kadlec, 2001) Because
each in lhardt
s to
m
increased root
produc
een found in a test site in Camden, NJ, which is relatively close to Villanova, PA.
(Saltonsall, 2002)
2.10 Species Diversity
P. australis is the key species planted in CSWs in Europe because of its high pro
and its excellent nutrient removal capabilities. However, in the United States it poses a serious
weed risk. (Tanner, 1996) Preventing the invasion of P. australis is essential because of the
importance of species diversity. Engelhardt a
ri
d
ecosystem respiration and the recove
dividual species had unique and dominant effects on the wetland mesocosms, Enge
and Kadlec (2001) concluded that species diversity is important in order for different specie
fulfill different roles in an ecosystem.
Bouchard et al. (2007) found that an increase in species richness in a wetland mesocos
experiment enhanced belowground biomass and altered root patterns. The positive correlation
between species richness and belowground biomass was coupled with a more comprehensive
deployment of roots into varying soil layers in the highest diversity treatments. This suggested
that interactions among plant groups at higher diversity levels can impose soil resource
partitioning by inducing certain species to root at various and deeper depths. This
tion and increased rooting depth also served to decrease the amount of methane in the
wetland mesocosms. (Bouchard et al., 2007)

34. 23
2.11 Phragmites australis Control
In order to promote species diversity within a CSW, P. australis invasion must be
controlled. Warren et al. (2001) found that mowing lowered the P. australis aboveground
produc
rren et al. (2001), these effects were
short te
in
of
ch is
d
l of the sections. In the first summer following herbicide treatment and cutting, no
plants g econd
pha
.
There were numerous P. australis reed removal effects. The microbial nitrogen demand
ould not compensate for the removal of nitrogen by plant uptake, and therefore an accumulation
tion and increased stem density, but it was ineffective for control. After an herbicide
treatment, the frequency of P. australis decreased and the total live cover was less than eight
percent, leaving mainly heavy litter and dense standing dead stems. After two growing seasons,
P. australis contributed three percent cover to the combined herbicide and mowing treatment
area. However, both of these values of P. australis doubled after four years. Hence, a single
treatment was ineffective for long term P. australis control. Recurring treatments are required to
adequately control the invasive ability of this reed species. (Warren et al., 2001)
Ailstock et al. (2001) demonstrated that a one time herbicide application or herbicide
followed by a burning drastically reduced the abundance of P. australis in nontidal wetlands.
These reductions were then followed by a regrowth of other species, which thereby increased the
species abundance and diversity. In accordance with Wa
rm, and after the third growing season, there was a significant expansion of P. australis
that was not killed in the initial herbicide application. Because of this, additional spot herbicide
applications are required to prevent the long term regrowth of P. australis, as well as to mainta
plant biodiversity. (Ailstock et al., 2001)
Findlay et al. (2003) removed P. australis with a Rodeo herbicide spraying at the end
the growing season followed by a cutting the following spring. They partitioned the CSW into
different sections for comparison before treatment began. One section contained Typha, whi
a common genus replaced by P. australis. One section contained P. australis as a reference an
another section was a P. australis removed area. The plants and biomass were collected and
sampled in al
rew in the treated site and a thick layer of plant litter covered the area. By the s
summer, the litter layer had disappeared, and by the third summer, a patchy regrowth of Ty
and P. australis covered half of the treatment area. Substantiating the findings of Warren et al
(2001) and Ailstock et al. (2001), control was effective in the short term but without continuous
treatment, P. australis grew back. (Findlay et al., 2003)
c

35. 24
of ammonium occurred in the porewater that lasted at least two growing seasons. P. australis
ructure facilitates oxygen transport to the rhizosphere, and since microbial nitrogen demand
epends on the external oxygen supply, the killing of P. australis diminished the microbial
nitrogen demand, thereby increasing the ammonium content in the porewater. Since rhizosphere
oxidation by P. australis is a source of oxygen for nitrification, reed removal would cause a
decrease in nitrate, resulting in a decrease in denitrification. Another negative effect of the P.
australis reed removal was the reduction in nutrient sequestration in the plant biomass. (Findlay
et al., 2003)
Findlay et al. (2003) also found positive effects from the P. australis removal.
Originally, low diversity P. australis occupied the CSW. After reed removal, the species
richness of the CSW increased. When only P. a was present, there was an average of
three species per meter squared; after cutting, the regrowth contained an average of more than
seven species per meter squared. (Findlay et al., 2003)
st
d
ustralis

36. 25
Chapter Three: Methodology
This chapter describes the protocol used in the collection and analysis of samples. The
ntation used in data and sample collection, sampling routine and schedule and
rocedures will be explained in detail.
3.1 Introduction
instrume
laboratory p
3.2 Sampling Sites
The Villanova University CSW is located in Villanova, PA; it borders County Line Road
and is near several academic and maintenance buildings (Figure 3.1). It receives stormwater
runoff from approximately 56.6 acres of campus, 57.2% of which are impervious surfaces
(Jones, 2008). There are three water quality sampling sites within the CSW: the inlet, the
sediment forebay, and the outlet (Figure 3.2). Flow is sampled at two inflow pipes (inlet) and
one outflow pipe (outlet).
Figure 3.1: Location of CSW at Villanova University
(Rea, 2004; Stormwater Wetland Project Report, 2008; Woodruff, 2005)

37. 26
1. Inlets
2. Sediment
Forebay
3. Outlet
Figure 3.2: Sampling Site Locations within Villanova CSW
Inlet Main consists of a 42 inch pipe that transports flows from Mendel Hall, Tolentine
Hall, John Barry Hall and Falvey Library into the inlet of the Villanova CSW (Figure 3.3). Inlet
West contains a 48 inch pipe that transports flows from the Villanova University School of Law,
the law school parking lot, the nursing school and the West Campus apartments into the inlet of
the CSW, next to Inlet Main (Figure 3.3). While each inlet pipe was sampled individually for
flow, the water quality samples were taken just downstream of the entrance location as a
composite of the two inflows. The remainder of the watershed immediately adjacent to the CSW
enters the system via sheet flow and is not monitored.
The inlet is of significance because its layout changed throughout the study. In the
summer of 2007, construction began on the law school parking lot, located next to the inlet.
Throughout the fall and winter, the parking lot was excavated to allow for construction of the
new law school. Piles of soil became a constant sight in areas adjacent to the CSW. At the inlet
itself, numerous trees and foliage were removed. The grass on the hills leading down to the
CSW was also removed and a stone wall was constructed. Additionally, a flume was installed
in the summer of 2008. All in all, numerous changes occurred during construction that altered

38. 27
the area around the inlet and may have impacted water quality sampling (e.g. erosion and
sedimentation controls, such as silt fences were utilized, although they were occasionally in
disrepair). However, the flow through the inlet pipes was not impacted by the construction as the
flow originated upstream of the construction.
Inlet Main
Inlet West
Figure 3.3: Inlet Main and Inlet West
The second sampling site in the Villanova CSW is the sediment forebay (Figures 3.2,
3.4). The sediment forebay is a pool of water which enables particles to settle out of the water
column. It was offset from the CSW in order to bypass high flows while allowing low flows to
enter the forebay. The offset design also serves to avoid constant turbulence and to prevent the
resuspension of particles. The sediment forebay measures 40 ft by 40 ft by 4 ft; it was originally
thought that the watershed was smaller. The sediment forebay was designed to hold 0.1 inches
of runoff from impervious surfaces and 0.05 inches of runoff from the entire watershed.
(Stormwater Wetland Project Report, 2008; Woodruff 2005) Unlike the inlets, the sediment
forebay does not consist of a pipe that conveys flow, and no flow was monitored. Water quality
samples were collected at the downstream end of the forebay.

39. 28
Figure 3.4: Sediment Forebay
T-shaped
weir
15 inch orifice
and V-notch weir
Pressure
Transducer
Figure 3.5: Outlet Structure

40. 29
The third sampling site of the Villanova CSW is the outlet (Figure 3.2). The outlet
structure consists of a T-shaped weir, which controls the 25 and 50-year storms, and below the
T-shaped weir is a 15 inch orifice (Figure 3.5). A V-notch weir was installed in this orifice in
the fall of 2007 to measure low flows. The sides of the outlet structure each contain rectangular
slits that act as weirs as another control mechanism. The top of the outlet contains an iron grate,
which discharges the 100-year storm. A gabion was constructed in front of the outlet structure at
an elevation to pass the ten-year storm, and a smooth elevated weir was built at the end of the
gabion to allow flow to enter the outlet. Water quality samples were collected directly upstream
of the water flowing into the concrete outlet structure.
3.3 Instrumentation
Flow
The Sigma 950 is a portable flow meter that is self-contained (Figure 3.6) and measures
the average velocity of flow by using an area/velocity bubbler probe in order to measure the
velocity and depth of flow within the two inlet and outlet pipes. The area/velocity probe
contains a small air line that is attached to the Sigma 950. The 950 pumps air bubbles into this
air line and through the pipe, and it then measures the pressure of the air bubble at the release
point while calculating the depth of water from a calibration standard. The probe uses the
Doppler Effect to measure the velocity of the flowing pipe. The Sigma 950 releases a sound
wave from one end of the probe in order to measure the shift in frequency as the wave moves
away with the flow. This shift allows the Sigma 950 to determine the velocity of the flow. The
flow is calculated based on the current level of water and the continuity equation. (Hach, Sigma
950 Flow Meter, 2004) The Sigma 950 for Inlet Main is located in a metal cage behind the St.
Augustine Center and measures the flow at the upstream end of the pipe to avoid backwater
effects. The Sigma 950 for Inlet West is located in a metal lockbox at the inlet of the CSW and
the velocity and depth sensor is located about two feet upstream of the inlet. The Sigma 950 for
the outlet is located in a metal lockbox above the outlet structure, and the sensor is located
downstream of the outlet structure.

41. 30
Figure 3.6: Sigma 950 Flow Meter
The outlet is also equipped with a pressure transducer (Figure 3.5). The pressure exerted
on a submerged object is the sum of the hydrostatic pressure from the depth of water and the
atmospheric pressure. The pressure transducer installed at the outlet is the PS9800 5PSIG, which
is able to measure depths of up to roughly ten feet. The transducer’s 4-20 mA signal can be read
directly by the Analog Input capabilities available on the outlet’s American Sigma 950 Flow
Meter. The pressure transducer was calibrated on a monthly basis by submerging it in various
known depths of water. Once the pressure transducer calibration was completed, the depth data
were logged at specified time intervals and then stored on the Sigma 950 for later recovery.
(VUSP Watersheds Laboratory, 2007)
The pressure transducer is used in conjunction with the 90° V-notch weir to calculate
flow during low flow periods at the outlet. The pressure transducer measures the depth upstream
of the weir. The geometry of the V-notch weir makes it capable of accurately measuring both
low and high flows, although it is only intended to measure low flows in this application. The
weir at the outlet (Figure 3.7) was machined from an aluminum plate according to ASTM
standards, and it was securely mounted to the 15 inch orifice of the outlet structure. (VUSP
Watersheds Laboratory, 2007)

42. 31
Figure 3.7: View of V-notch Weir from
within the Outlet Structure
The general equation for flow over a V-notch weir is:
2
1
2
1
*
2
tan*2**
15
8
HgCQ d ⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
=
θ
)1.3(
Where: Q = flow rate (ft3
/s)
g = gravity (ft/s2
)
Cd = is the coefficient of discharge (varies)
θ = angle of V-notch (varies)
H = head on weir (ft)
The angle of the V-notch weir (θ ) is 90°. (VUSP Watersheds Laboratory, 2007)
Precipitation
An external “tipping bucket” rain gauge (American Sigma Model 2149) is connected to
the Sigma 950 at Inlet West (Figure 3.8). It provides a dry contact closure to the flow meter
(Hach Sigma 950 Flow Meter Instruction Manual, 2004). When 0.04 inches of rain occur in a 25

43. 32
minute time period, the rain gauge signals the Inlet West Sigma 950 that a storm event is
happening. When this happens, the Sigma 950 triggers the Inlet West Sigma 900, an
autosampler, to begin collecting water quality samples.
Figure 3.8: American Sigma Model 2149 Rain Gauge
Water Quality
The Sigma 900 can be programmed to take samples at various time intervals (Figure 3.9).
There are three Sigma 900s at the Villanova CSW which are located at the three water quality
sampling sites: inlet (a composite just downstream of the headwall where Inlet Main and Inlet
West enter the CSW), sediment forebay, and the outlet. When the Sigma 900 at Inlet West is
triggered by the Inlet West Sigma 950, it in turn activates the Sigma 900s at the sediment forebay
and outlet. A four-way splitter is used to directly connect all of the Sigma 900s to the Inlet West
Sigma 950 (VUSP, QA-QC Project Plan, 2008). During the fall of 2007 and winter of 2008, the
Sigma 900s at the sediment forebay and outlet had to be manually triggered because the wiring
connecting them to the inlet was not working. These data lines were repaired on February 25,
2008.

44. 33
Figure 3.9: Sigma 900 Automated Sampler
The Sigma 900s at the inlet, sediment forebay and outlet all had twelve (Model AM.S16)
350 mL sample bottles (Figure 3.10). The sampling regime spanned 36 time intervals. At each
time interval, one sample was taken, and three samples were taken per sample bottle. A
composite of three samples per bottle yielded 12 total composite samples for the sampling
period. Each bottle held three 100 mL samples, yielding 12 total samples of 300 mL each. The
time intervals for these 36 intervals are found in Appendix A. The intervals at the inlet were
shorter than those at the sediment forebay and outlet, ending at hour 36. The interval lengths of
the sediment forebay and outlet were longer than those at the inlet because it took longer for flow
to reach them; past studies (Rea, 2004; Woodruff, 2005) did not always capture the tail of the
storm hydrograph, so exaggerated sampling periods at the sediment forebay and outlet were used
to avoid this problem. Similarly, the sampling period at the outlet (87 hours) was longer than
that at the forebay (82 hours) because it took the longest for flow to reach the outlet.

45. 34
Figure 3.10: Bottle Setup within the Sigma 900
3.4 Sampling Routine
This study consisted of research from both baseflow and storm events. Baseflow was
defined as the flow occurring within the CSW a minimum of 72 hours after a precipitation event.
A storm event was defined as when 0.04 inches of rain occurred in a 25 minute time period. The
rain gauge determined if these parameters were met.
The sampling schedule was divided into four periods: fall (September-November),
winter (December-February), spring (March-May), and summer (June-August). The goal was to
collect three storm events and three baseflow events in each sampling period, although flow was
monitored continuously. Due to instrument malfunction and the lack of precipitation events, this
goal was not always met. The data from each period are compared with each other in order to
analyze the efficiency of the CSW in removing nutrients throughout the year.
3.5 Collection and Analysis Protocol
The samples for the storm events were collected by the Sigma 900s at the inlet, sediment
forebay and outlet. The samples for the baseflow events were collected in person with grab
sample bottles (Nalgene 250 mL). Three grab samples were taken at each of the three water
quality sampling sites. After the samples were taken, they were immediately taken to the
Villanova University Water Resources Laboratory to be analyzed. Both baseflow samples and
storm event water quality samples were tested for the same parameters: total nitrogen, total
phosphorus, total orthophosphate, total chloride, total suspended solids, and total dissolved

46. 35
solids. All collection techniques and laboratory analysis complied with recommended practices
by the manufacturer and an EPA approved QAPP.
3.6 Total Nitrogen and Total Phosphorus
The Hach DR/4000 Spectrophotometer was used to conduct the total nitrogen and total
phosphorus tests. The spectrophotometer measures the amount of light absorbed at specific
wavelengths in order to determine the concentration of a sample. The measured absorbance can
then be related to different chemical parameters. (Dukart, Total P – Total N, 2007)
Accurate sample volumes were necessary for determining the correct concentration
samples. TenSette Pipets were therefore used to precisely measure sample volumes. Models
19700-01 (one mL max) and 19700-10 (ten mL max) pipets were used depending on the sample
required. In order to prevent cross-contamination, the tip was changed between each sample.
(Dukart, Total P – Total N, 2007)
The Hach DR/4000 uses one inch square glass sample cells. The suggested cleaning and
handling procedures were strictly followed in order to prevent interference from the glassware.
Finger contact was avoided with the clear sides of the cells. The cells were oriented in the one
inch square cell adapter within the sample module, so that the fill marks were facing the user and
the clear sides were facing the lamp. The cells were wiped with a cloth to remove smudges and
fingerprints. The total nitrogen and total phosphorus spectrophotometric analyses were done in
manufacturer prepared digestion vials. The vials were held by the plastic caps in order to avoid
touching the glass vials. The glass vials were again wiped with a cloth before being placed in the
spectrophotometer. After the analysis, the vials were immediately emptied into specified
hazardous waste containers because they were not reusable and were disposed of as described in
the product’s Material Safety Data Sheet. (Dukart, Total P – Total N, 2007)
The total nitrogen and total phosphorous tests require that the samples go through a
digestion period at certain temperatures for 30 minutes (105° C and 150° C, respectively). The
Hach COD Reactor Model 45600 was used to warm the samples for the required time periods. It
can hold up to twenty-five 16x100 mm vials, and it has the ability to sustain temperatures up to
150° C. The COD Reactor Model has two modes: 150° C mode and an adjustable temperature
mode. (Dukart, Total P – Total N, 2007)

47. 36
3.7 Total Orthophosphate
The Hach DR/4000 Spectrophotometer was used to test total orthophosphate until
January 2008. The total orthophosphate test was carried out in a similar fashion as the total
nitrogen and total phosphorus tests. In January 2008, total orthophosphate began being tested
with Systea technology using EasyChem methodology. In this method, the aqueous sample
containing orthophosphate was mixed with sulfuric acid, ammonium molybdate and antimony
potassium tartrate to form antimony-1, 2-phosphorous molybdenum acid. Then, this complex
was reduced by ascorbic acid to form a blue heteropoly acid (molybdenum blue). The
absorbance of the formed blue complex was measured at 660 or 880 nm, and it was proportional
to the concentration of orthophosphate. (Systea Scientific, Ortho-Phosphate, 2006)
3.8 Total Chloride
Chloride was tested with the High Pressure Liquid Chromatograph (HPLC) until January
2008. The HPLC consists of the following components: a Waters Model 626 HPLC Pump with
IonPac®
ASII-HC Anion-Exchange Column, a Waters Model 431 Conductivity Detector, a
Waters Model 600s Controller, a Waters Model 717plus Autosampler, a Dionex AMMS®
III
Eluent Suppressor, Galaxie Chromatography Data System Version 1.7.4.5, IonPac ATC-3 Trap
Column 9x24mm, AG11-HC Guard Column, 4x50mm, and IonPac ASH11-HC Analytical
Column, 4x250mm. (Salas-de la Cruz, 2007)
The HPLC injected small amounts of sample into an anion exchange column that
separated out the present anions. After being separated, the anions were read by a conductivity
detector. The measured conductivities were then plotted and computer software integrated the
area underneath the peaks for each individual anion. The area underneath the chloride peak was
then related back to the calibration standard in order to determine the concentration of chloride in
each sample. (Rea, 2004)
In January 2008, chloride began being tested with Systea. In EasyChem methodology, a
thiocyanate ion was liberated from mercuric thiocyanate through the formation of soluble
mercuric chloride. In the presence of a ferric ion, free thiocyanate ion forms a highly colored
ferric complex. The intensity of this complex was measured at 480 nm, and this intensity was
proportional to the chloride concentration. (Systea Scientific, Chloride, 2006)

48. 37
3.9 Total Suspended Solids/Total Dissolved Solids
The term “total solids” refers to the material residue that is left in a container after a
sample is evaporated and dried in an oven at a defined temperature. Total solids include both
“total suspended solids,” which are the portion of total solids retained by a filter, and “total
dissolved solids,” the portion that passes through the filter in water. (Dukart, Total
Suspended/Total Solid/Metals, 2007)
Accurate sample volumes were of extreme importance in determining the correct
concentration of the sample. Each vacuum flask was weighed empty and then reweighed with
the sample. The weight of the empty flask was subtracted from the weight of the flask plus
sample in order to calculate the exact volume passed through the filter. Also, each filter was
weighed both prior to and after filtration/drying in order to determine the mass of suspended
solids. Similarly, each evaporating dish was weighed both prior to and after filtration/drying in
order to determine the mass of the dissolved solids. The concentration of the
suspended/dissolved matter could then be calculated. (Dukart, Total Suspended/Total
Solid/Metals, 2007)
The solid filter papers and the displaced liquid were dried in dishes in ovens set at
approximately 100° C and 250° C, respectively, for at least one hour, or until dry. Desiccators
were used to cool the samples without allowing moisture to permeate. (Dukart, Total
Suspended/Total Solid/Metals, 2007)
3.10 Pollutant Concentrations and Detection Limits
The water quality tests used have detection limits for pollutant concentrations. The Hach
total nitrogen test has a lower detection limit of 1.7 mg/L (Hach, 2003); those non-detected
samples falling below this range were given the value of 0.85 mg/L, which was half of the
detection limit. The Hach total phosphorus test has a lower detection limit of 0.06 mg/L (Hach,
2003); those non-detected samples falling below this range were given the value of 0.03 mg/L,
half of the detection limit. The Systea total orthophosphate test has a lower detection limit of
0.01 mg/L (Dukart, 2008); those non-detected samples falling below this range were assigned the
value of 0.005 mg/L. The Systea total chloride test has a lower detection limit of 0.5 mg/L
(Dukart, 2008); no samples fell below this limit. When the calculated total suspended solids and
total dissolved solids values were negative, these samples were assigned the value of 0. Some

49. 38
samples had true total suspended solids values of 0: 10/2/07:WT-BF-I1, 11/6/07:WT-OT-05,
11/15/07:WT-OT-05, WT-OT-06, 1/29/08: WT-OT-04, 4/3/08:WT-IN-05, WT-IN-07,
7/17/08:WT-BF-O1, 7/23/08:WT-OT-08, WT-OT-10, and 8/19/08:WT-BF-O1 (Appendix B).
All storm event and baseflow event pollutant concentrations (mg/L) are found in Appendix B.
Values in bold-faced font are those below the detection limits.
3.11 Data Analysis
Water quality parameters were analyzed in the laboratory and pollutant concentrations
were typically recorded in mg/L. It is also beneficial to look at the pollutant transport by the
mass loading in and out of the Villanova CSW; the mass (M) was calculated using:
M CQ t= ∆ (3.2)
where, C is concentration, Q is the volumetric flow rate, and ∆t is the time interval. During
storm events, the time interval was five minutes because this was how often the flow rate was
measured by the Sigma 950s. During baseflow events, the average concentration of samples was
assumed representative of the season, the flow was that measured by the respective site Sigma
950 at the time of sampling, and the time interval was three months, representing an entire
sampling season.
Unlike the flow data, water quality samples were not collected every five minutes. In
order to estimate pollutant concentrations and loadings in five minute intervals, a linear
interpolation was performed in between storm sample times using Microsoft Excel.
Interpolating might not characterize random fluctuations, but it does give a good representation
of the total quantity of pollutants moving through the CSW during a storm event (Rea, 2004).
The percent removal of pollutants was calculated using:
% removal= ΣMin-ΣMout* 100 (3.3)
ΣMin
A negative percent removal signifies that there was pollutant loading within the CSW, rather
than removal from the inlet to the outlet. (Wadzuk, 2008)
The Event Mean Concentration (EMC) is a flow weighted average concentration and was
used in the analysis of storm events. The EMC is the total mass (summing the interpolated
incremental masses) divided by the sum of the total flow volume multiplied by the time interval:

50. 39
M
EMC
Q t
=
∆
∑
∑
(3.4)
The EMC values were typically reported in mg/L. The percent reduction of pollutant EMC was
calculated using:
% reduction= ∆EMC * 100
EMCin (3.5)
where ∆EMC is the change in the EMC values between the inlet and the outlet
(∆EMC=EMCinlet- EMCoutlet). As the flow (Q) increases, the EMC decreases, and vice versa.
3.12 Plot Study
The location of the plot study was downstream of the sediment forebay and upstream of
the outlet (Figure 3.11). This location was chosen because it is located in the periphery of the
CSW. The periphery is more easily controlled by the glyphosate sprayings, so Phragmites
invasion poses less of a threat. The elevation of the CSW in this area decreases from upstream to
downstream, so water flows through the plots towards the outlet. A baseflow is also present,
which is essential for groundwater sampling. This area of the CSW is also more exposed to the
sun during the winter, so freezing is less of an issue.
Figure 3.11: Location of Plots (Pre-Study)

51. 40
The plots were cleared over a three day period at the end of April 2008. Pitchforks, rakes
and spades were used to loosen up the wetland soil, so that Phragmites rhizomes could be
removed (Figure 3.12). The water was opaque and knee deep, so it was nearly impossible to
remove all of the rhizomes, but a good portion were taken up from the CSW (Figure 3.13).
Figure 3.12: Clearing of the Plots
Figure 3.13: Removed Phragmites Rhizomes

52. 41
A
B
C
Figure 3.14: Cleared Plots
The cleared plots were sectioned off with stakes and rope into six foot by six foot
squares. Two six inch Model 601 Standpipe Piezometers were placed in each plot. Attached to
each piezometer was a 30 inch long, three-quarter inch diameter Schedule 40 PVC pipe. One
piezometer was placed in the upstream end of each plot (inlet), and one piezometer was placed in
the downstream end of each plot (outlet). The inlet piezometer was positioned so that its water
level was higher than that of the outlet piezometer. This was to assure that the groundwater
samples collected flowed through each plot from its inlet to its outlet.
In total, there were four plots. Three of these plots were cleared out in April: control,
sweet flag, and cattail. Because of spatial constraints, these plots were positioned in series
(Figure 3.14). The control plot (Figure 3.14, A) was located in the most upstream position,
nearest to the sediment forebay. It remained clear of plants and was composed of native wetland
soil. The sweet flag (Acorus calamus) plot (Figure 3.14, B) was downstream of the control plot,
and the cattail (Typha latifolia) plot (Figure 3.14, C) was downstream of the sweet flag plot. The
sweet flag plot was positioned in shallower water than the cattail plot because sweet flags
survive better at these depths (Sweet Flag, 2008). The fourth plot, Phragmites, was downstream
of the cattail plot, in the deepest water. Sweet flag reaches an average height of 1-4 feet
(Connecticut Botanical Society, 2008), cattail grows up to 5-10 feet in height (Typha latifolia,
2008), and Phragmites grows up to 12 feet tall (Wisconsin Department of Natural Resources,
2008). Their maximum heights were in accordance with their plot depths. The Phragmites plot

53. 42
was offset from the other three plots to help prevent invasion. A patch of existing Phragmites
was sectioned off (Figure 3.15), and the length of the Phragmites plot from its inlet to its outlet
moved away from the periphery of the CSW because the elevation decreased in this direction,
and more importantly, the water flow followed this course. As a precautionary measure, the Ju
17, 2008 glyphosate spraying was not conducted in the Phragmites plot.
ne
Figure 3.15: Phragmites Plot
May of 2008, plugs of sweet flags and cattails were planted in pots. They were
fertilize g
t in the
(Picture taken on 2008)August 7,
In
d and watered until they became tall enough to be planted in the CSW without bein
submersed. On July 1, 2008, 50 sweet flags and 45 cattails were planted. At this time,
Phragmites and other foliage had grown in densely in areas surrounding the plots, but no
plots themselves. This is evidenced by the control plot which was free of plants, and more
importantly Phragmites (Figure 3.16).

54. 43
Figure 3.16: Control Plot
(Picture taken on August 7, 2008)
Most of the sweet flag and cattail plugs reached the surface of the CSW water, and some of them
broke the water’s surface. The sweet flag plot (Figure 3.17) and the cattail plot (Figure 3.18)
both grew in biomass during the sampling period of July and August 2008.
Figure 3.17: Sweet Flag Plot
(Picture taken on August 7, 2008)

55. 44
Figure 3.18: Cattail Plot
(Picture taken on August 7, 2008)
The four plots were sampled on three dates in July and August 2008. Two surface
samples and two groundwater samples were taken from each plot; one surface and one
groundwater sample were taken from the inlet of each plot, and one surface and one groundwater
sample were taken from the outlet of each plot. Surface and groundwater samples were collected
in 50 mL polyethylene bottles. Groundwater samples were taken with half inch diameter, 36
inch long poly weighted bailers. The inlet and outlet surface water samples were taken at the
same time, and the inlet and outlet groundwater samples were taken at the same time in each
plot. It was assumed that the two surface and two groundwater samples were of the same
population and were representative of the baseflow.
The surface and groundwater samples were immediately taken to and tested in the
Villanova University Water Resources Laboratory. The samples were tested for total nitrogen,
total phosphorus, total orthophosphate and total chloride. The same lab testing protocol as
described in Sections 3.6-3.9 was used. Total suspended and dissolved solids were not tested
because it was thought that the sweet flag and cattail plots would not yet be dense enough to
allow for sufficient removal.

56. 45
Chapter Four: Storm Events
4.1 Introduction
This chapter will present and discuss the results from the storm events in the forms of
EMCs, loadings, percent reductions and percent removals. In addition, storm event data are
presented in a variety of pollutographs (found in Appendices C-V). The storm event
concentration pollutographs plot the concentration of each pollutant against t/(t rain event); t/(t
rain event) is the time the sample was taken divided by the time of the total rain event
(Appendices C-F). This was used to non-dimensionalize time, so all of the storms could be
compared efficiently. Four different mass loading pollutographs are used. One set of mass
loading pollutographs plot the loading of the pollutants throughout the sampling period (M)
against t/(t rain event) (Appendices G-J). The second set of mass loading pollutographs plot the
individual loadings at each of the five minute intervals divided by the total loading of the
sampling period (M/(M total)) against t/(t rain event) (Appendices K-N). The third set of mass
loading pollutographs plot the sum of the loading throughout the sampling period (∑M) against
t/(t sample length) (Appendices O-R); t/t(sample length) is the time of the sample divided by the
time of the total sampling period. Lastly, the fourth set of mass loading pollutographs plot the
sum of the loading at each of the five minute intervals divided by the total sum of the loading
from the entire sampling period (∑M/(M total)) against t/(t sample length) (Appendices S-V).
Each nutrient will be discussed separately. Individual storm events will be the main focus, but
seasonal storm summaries will also be touched upon.
Thirteen storm events were sampled between October 2007 and July 2008. These storms
ranged in size from 0.17 inches to 3.03 inches and in length from 3.8 hours to 65.9 hours (Table
4.1). Storm length was defined as the time from the beginning of precipitation to the last point of
precipitation before the start of a minimal 24 hour dry period. A new storm occurred after at
least 24 hours of no precipitation. When a new storm occurred during the extent of sampling,
this was classified as a double peaking storm event.

57. 46
Table 4.1: Summary of Rainfall and Storm Length
The total rainfall amount and duration is given. If the storm was double peaking (i.e. a minimum
of 24 hours between rainfall events) the amount and duration is given, which is in addition to the
initial rainfall amount and duration.
Storm Date
Antecedent
Dry Time
(hr) Rainfall (in)
Storm
Length (hr)
Dry Time
Between
Initial and
Double
Peaking
Storms (hr)
Double
Peaking
Storm
Rainfall
(in)
Double
Peaking
Storm
Length (hr)
9-Oct-07 88.75 3.03 58
6-Nov-07 228.5 0.22 8.6
15-Nov-07 24.92 0.63 58
29-Jan-08 264.17 0.25 18.8 25.2 1.67 11.4
13-Feb-08 134.75 2.44 15.8
26-Feb-08 24.83 0.17 6.2 83 0.09 1.8
4-Mar-08 84.67 1.15 35.6 30.4 2.3 27.7
3-Apr-08 47.17 0.57 11.4 45.6 0.08 4.7
26-Apr-08 131.58 1.49 65.9
31-May-08 72.67 0.47 3.8
5-Jul-08 111.75 0.18 27.2 46 0.18 2.7
14-Jul-08 105.33 0.51 5.2
23-Jul-08 38.5 1.65 32.8
Storm events are analyzed by season: fall (September – November), winter (December –
February), spring (March – May) and summer (June – August). During the fall and the winter,
the wiring connecting the Sigma 900s at the sediment forebay and outlet to the inlet was not
working, so the sediment forebay and outlet had to both be manually triggered. This wiring was
repaired on February 25, 2008, and because of this, the winter February 26, 2008 storm and the
spring and summer storms all required no manual triggering.
Occasionally, there were Sigma 900 errors, lack of sample, and human error, so not all of
the pollutants or samples were tested in each storm. Table 4.2 presents a summary of the water
quality tests performed for each storm event. Tables 4.3- 4.6 present summaries of the EMCs,
loadings, and percent reductions and removals of the six pollutants for each storm and each
season.

58. 47
Table 4.2: Summary of Storm Event Testing
Storm Date TN TP PO4 Cl TSS TDS
9-Oct-07 I/O I/O I/O I/O I/O I/O
6-Nov-07 I/O I/O I/O I/O I/O I/O
15-Nov-07 O I/O I/O I/O I/O I/O
29-Jan-08 I/O I/O I/O I/O I/O I/O
13-Feb-08 I/O I/O I I I/O I/O
26-Feb-08 I/O I/O I/O I/O I/O I/O
4-Mar-08 I/O I/O I/O I/O I/O I/O
3-Apr-08 I/O I/O I/O I/O I/O I/O
26-Apr-08 I/O I/O I/O I/O I/O I/O
31-May-08 I/O I/O I/O I/O I/O I/O
5-Jul-08 I/O I/O I/O I/O I/O I/O
14-Jul-08 I/O I/O I/O I/O I/O I/O
23-Jul-08 I/O I/O I/O I/O I/O I/O
I= Inlet Tested O= Outlet Tested
Table 4.3: Summary of Storm EMCs (mg/L) and % Reductions
(TN, TP, PO4)
Storm TN In TN Out
TN %
Reduction TP In TP Out
TP %
Reduction PO4 In PO4 Out
PO4 %
Reduction
10/9/2007 3.51 3.63 -3.26 0.97 0.44 54.96 0.35 0.21 39.10
11/6/2007 3.04 0.85 72.05 0.48 0.18 63.20 0.06 0.07 -9.70
11/15/2007 1.42 1.09 0.21 81.17 0.73 0.12 83.28
Fall
Average 3.28 1.97 40.00 0.84 0.27 67.79 0.38 0.14 64.52
1/29/2008 1.75 2.06 -17.47 0.59 0.70 -18.86 0.51 0.12 76.02
2/13/2008 0.89 0.87 2.51 0.40 0.08 79.03 0.07
2/26/2008 1.81 0.85 52.98 0.72 0.47 34.48 0.10 0.07 27.49
Winter
Average 1.48 1.26 15.14 0.57 0.42 26.53 0.23 0.10 57.42
3/4/2008 2.85 0.89 68.79 0.41 0.32 20.57 0.03 0.01 80.66
4/3/2008 0.85 0.85 0.00 0.25 0.14 43.20 0.01 0.01 0.00
4/26/2008 4.39 2.95 32.89 1.02 0.59 41.65 0.60 0.44 26.15
Spring
Average 2.70 1.56 42.07 0.56 0.35 36.80 0.21 0.15 28.72
5/31/2008 3.06 0.85 72.22 0.35 0.41 -18.35 0.84 0.02 97.75
7/5/2008 2.90 0.87 69.94 0.43 0.34 20.12 0.09 0.08 7.39
7/14/2008 2.55 1.08 0.64 40.98 0.05 0.07 -60.31
7/23/2008 2.27 1.32 42.04 0.91 0.46 49.56 0.03 0.01 85.70
Summer
Average 2.70 1.01 62.41 0.69 0.46 33.13 0.25 0.04 82.28

59. 48
Table 4.4: Summary of Storm EMCs (mg/L) and % Reductions
(Cl, TSS, TDS)
Storm Cl In Cl Out
Cl %
Reduction TSS In TSS Out
TSS %
Reduction TDS In TDS Out
TDS %
Reduction
10/9/2007 101.35 65.89 34.99 15.05 1.29 91.41 436.45 75.17 82.78
11/6/2007 154.87 160.04 -3.34 15.19 11.13 26.72 418.42 576.30 -37.73
11/15/2007 69.78 173.38 -148.47 125.00 0.00 100.00 136.08 557.43 -309.64
Fall
Average 108.67 133.10 -22.49 51.75 4.14 92.00 330.32 402.97 -21.99
1/29/2008 219.45 190.02 13.41 25.18 45.10 -79.07 520.02 401.52 22.79
2/13/2008 297.24 2.80 11.03 -294.20 649.23 486.35 25.09
2/26/2008 416.52 546.52 -31.21 416.52 9.91 97.62 4082.20 980.94 75.97
Winter
Average 311.07 368.27 -18.39 148.17 22.01 85.14 1750.48 622.94 64.41
3/4/2008 148.31 178.55 -20.39 40.14 14.17 64.69 327.13 416.08 -27.19
4/3/2008 184.39 145.38 21.16 2.37 7.32 -208.11 376.19 442.26 -17.56
4/26/2008 201.88 206.26 -2.17 43.65 19.44 55.47 493.85 986.30 -99.72
Spring
Average 178.20 176.73 0.82 28.72 13.64 52.50 399.06 614.88 -54.08
5/31/2008 196.25 122.46 37.60 48.63 0.18 99.64 663.51 0.92 99.86
7/5/2008 104.54 187.77 -79.61 29.90 2.49 91.66 389.21 462.10 -18.73
7/14/2008 156.90 92.14 41.27 20.08 25.06 -24.80 529.94 269.91 49.07
7/23/2008 151.84 60.68 60.03 16.60 19.81 -19.35 479.27 302.97 36.79
Summer
Average 152.38 115.76 24.03 28.80 11.89 58.73 515.48 258.98 49.76
Table 4.5: Summary of Storm Loadings (g) and % Removals (TN, TP, PO4)
Storm TN In TN Out
TN %
Removal TP In TP Out
TP %
Removal PO4 In PO4 Out
PO4 %
Removal
10/9/2007 7843.09 5737.98 26.84 2157.15 688.36 68.09 786.10 339.15 56.86
11/6/2007 4544.09 18.95 99.58 715.00 3.93 99.45 96.15 1.57 98.36
11/15/2007 201.50 3371.67 29.11 99.14 2261.50 17.33 99.23
Fall
Average 6193.59 1986.15 67.93 2081.27 240.47 88.45 1047.92 119.35 88.61
1/29/2008 7280.90 11926.55 -63.81 2452.92 4065.53 -65.74 2538.78 535.45 78.91
2/13/2008 4918.84 171.94 96.50 2219.36 16.69 99.25 624.49
2/26/2008 1630.17 404.75 75.17 649.72 239.22 63.18 449.83 36.37 91.92
Winter
Average 4609.97 4167.75 9.59 1774.00 1440.48 18.80 1204.37 285.91 76.26
3/4/2008 28956.28 800.11 97.24 4119.40 289.67 92.97 327.97 5.61 98.29
4/3/2008 2705.78 1123.90 58.46 811.44 191.44 76.41 15.92 6.61 58.46
4/26/2008 9625.45 455.44 95.27 2234.67 91.93 95.89 1305.02 67.95 94.79
Spring
Average 13762.50 793.15 94.24 2388.50 191.01 92.00 549.64 26.72 95.14
5/31/2008 7314.09 633.50 91.34 826.52 305.00 63.10 2014.21 14.15 99.30
7/5/2008 1435.58 969.03 32.50 211.56 379.46 -79.36 43.32 90.09 -107.96
7/14/2008 6642.17 2806.62 444.16 84.17 120.59 51.84 57.01
7/23/2008 5692.86 3646.80 35.94 2274.43 1267.95 44.25 87.58 13.84 84.20
Summer
Average 5271.18 1749.78 66.80 1529.78 599.14 60.83 566.43 42.48 92.50

60. 49
Table 4.6: Summary of Storm Loadings (g) and % Removals (Cl, TSS, TDS)
Storm Cl In Cl Out
Cl %
Removal TSS In TSS Out
TSS %
Removal TDS In TDS Out
TDS %
Removal
10/9/2007 226359.62 104259.70 53.94 33616.98 2046.81 93.91 974750.22 118947.72 87.80
11/6/2007 231392.72 3568.13 98.46 22698.36 248.18 98.91 625186.63 12848.44 97.94
11/15/2007 21571.36 24576.17 -13.93 289571.41 0.00 100.00 315246.83 79015.72 74.94
Fall
Average 159774.57 44134.67 72.38 115295.59 765.00 99.34 638394.56 70270.63 88.99
1/29/2008 1085583.60 826613.55 23.86 104509.83 165714.20 -58.56 2158055.36 1475474.52 31.63
2/13/2008 2496609.30 23495.77 2182.64 90.71 5453114.24 96266.23 98.23
2/26/2008 1891980.07 276795.20 85.37 103181.17 5020.99 95.13 18217673.45 496817.49 97.27
Winter
Average 1824724.32 551704.38 69.77 77062.26 57639.28 25.20 8609614.35 689519.41 91.99
3/4/2008 1507645.87 160685.27 89.34 407002.32 12753.80 96.87 3317088.15 374443.27 88.71
4/3/2008 586970.97 192223.63 67.25 7559.92 9675.33 -27.98 1197510.76 584770.68 51.17
4/26/2008 442433.55 31869.14 92.80 95665.02 3003.29 96.86 1082289.23 152393.01 85.92
Spring
Average 845683.46 128259.34 84.83 170075.76 8477.47 95.02 1865629.38 370535.65 80.14
5/31/2008 469077.47 91266.38 80.54 116237.45 131.61 99.89 1585922.46 684.92 99.96
7/5/2008 51737.71 208649.78 -303.28 14795.85 2770.40 81.28 192613.08 513500.97 -166.60
7/14/2008 409040.96 64411.71 84.25 52357.71 17520.82 66.54 1381542.05 188679.58 86.34
7/23/2008 380240.13 167961.84 55.83 41575.53 54840.73 -31.91 1200242.30 838554.97 30.13
Summer
Average 327524.07 133072.43 59.37 56241.63 18815.89 66.54 1090079.97 385355.11 64.65
4.2 Total Nitrogen
Two sources of nitrogen to the Villanova University CSW are the atmosphere and
fertilizers. Through rainfall and runoff, the nitrogen found in the air and fertilizers makes its way
into the CSW. While the atmospheric loads of nitrogen and other pollutants during storm events
can at times be negligible, at other times this rainfall can be a significant source of pollutants to
CSWs (Krieger, 2003). Nitrogen is also a major component of stormwater runoff from urban
lands (DeBusk, 1999). Villanova University implements a fertilization routine to Mendel Field.
The turf is lightly fertilized with Earth Works; a product made of natural organic fertilizer
(compost and manure) and added nitrogen (Leeds, 2008). The runoff from Mendel Field thus
contains sources of nitrogen, which run into Inlet Main, and in turn the CSW.
It is expected that greater nitrogen removal will occur during times of baseflow rather
than times of storm events because the longer retention time of baseflow through the CSW
allows more time for nitrogen transformation, assimilation and removal to occur. Typically,
storm flows are too fast for similar removal to take place.
As mentioned in the Literature Review, plant uptake of ammonia or nitrate assimilates
nitrogen and stores it in an organic form in wetland vegetation (DeBusk, 1999). It is expected

61. 50
that the greatest removal for both baseflow and storm events will occur during the height of the
growing season (i.e. spring and summer) when there is increased plant biomass for more nitrogen
uptake. The lowest removal is expected to occur in the fall and winter when plants decompose,
releasing nitrogen into the CSW, where it again will be assimilated during the next growing
season. (Vymazal, 2007) Additionally, nitrification and denitrification remove nitrogen;
nitrification is an aerobic process, while denitrification is an anoxic process (Davis, 1995). The
optimal temperature for nutrient removal is 30° C. Nitrification rates become inhibited at 10° C
and begin to drop drastically at 6° C. Hence, less nitrogen removal is expected in the colder
months. (Picard et al., 2005) Most of the results of this study reflect the expected nitrogen
removal trends.
4.2.1 Fall
Concentration and mass load pollutographs for the fall storm events can be found in
Appendices C, G, K, O and S. Due to human error, the inlet samples for the November 15, 2007
storm were spilled before they could be tested for TN. The October 9, 2007 storm had a 3.3%
increase in the EMC of TN from the inlet to the outlet; however there was 26.8% removal of the
TN mass loading. TN removal is expected in the fall season (although less than in the summer,
the height of the growing season), which is inline with the mass removal observed. The EMC is
flow weighted (Equation 3.4), so as the flow decreases, the EMC increases, and vice versa. The
total sum of flow times the time step (Equation 3.4) at the outlet (186.4 cfs* ∆t to give cf) for the
duration of the October 9 storm sampling was less than that at the inlet (263.0 cfs* ∆t to give cf),
thereby resulting in a higher EMC at the outlet.
Of the nine inlet samples from the October 9 storm, four were above the PADEP TN
standard of 4.91 mg/L (PADEP Nonparametric Chemistry, 2008). Even though two of the ten
outlet samples were above this standard, six of the outlet samples had undetected concentrations
of TN. Only one inlet sample had an undetected TN value, and the average TN concentration of
the outlet samples (2.5 mg/L) was well below that of the inlet samples (4.3 mg/L). However, the
two outlet samples (Appendix B, Table 3) that fell above the PADEP TN standard did so by a
considerable margin (7.2 mg/L and 5.2 mg/L). They might have skewed the results, contributing
to the outlet having a higher TN EMC than the inlet.

62. 51
11/6/07 Total Nitrogen Pollutograph
0
0.5
1
1.5
2
2.5
3
3.5
4
0 2 4 6 8 10 12
t/(t rain event)
mg/LN
0
0.03
0.06
0.09
0.12
Rainfall(inches)
Inlet
Outlet
Rainfall
Graph 4.1: November 6, 2007 Total Nitrogen Pollutograph
The November 6, 2007 storm had a 72.0% reduction in the TN EMC from the inlet to the
outlet and a 99.6% removal in TN mass loading. All inlet and outlet samples fell below the
PADEP standard of 4.91 mg/L, and all outlet samples fell below the TN Hach detection limit of
1.7 mg/L. The concentration pollutograph of this storm event is a fairly idealized pollutograph
(Graph 4.1). Sampling began some time after initial rainfall because 0.04 inches of rain needed
to occur in a 25 minute time period in order for the Sigma 950 at the inlet to be triggered. The
inlet peaks in TN concentration during and right after high amounts of rainfall, and then it
steadily decreases in concentration. The outlet maintains a steady concentration both during and
after the rainfall that is well below that of the inlet. All outlet samples were assigned the value of
0.85 mg/L because they fell below the TN Hach detection limit (Refer to Section 3.10).

63. 52
Total Nitrogen Seasonal Summary
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Fall Winter Spring Summer
mg/LN
Inlet Storm
Outlet Storm
Graph 4.2: Summary of Total Nitrogen (mg/L) for Storm Events
Overall, there was a 40.0% EMC reduction in TN for the fall sampling period (Graph
4.2). The fall also had a 67.9% removal in TN mass loading. Graphs 1 and 2 of Appendices G
and O illustrate this removal; particularly, the cumulative mass curves (Appendix O) show the
accumulation of mass over time for the inlet and outlet.
4.2.2 Winter
Concentration and mass load pollutographs for the winter storm events can be found in
Appendices D, H, L, P and T. The January 29, 2008 storm event had a 17.5% increase in the TN
EMC from the inlet to the outlet and a 63.8% increase in TN mass loading from the inlet to the
outlet. All inlet and outlet samples fell below the PADEP TN standard of 4.91 mg/L. Sources of
nitrogen, and reason for the increase in concentration through the CSW could be because of
concurrent construction practices adjacent to the CSW that were primarily earth moving
practices at this time (Figures 4.1, 4.2). This construction and land moving could have exposed

64. 53
Figure 4.1: Inlet Pre-Construction
(Picture taken on July 19, 2007)
Figure 4.2: View of Construction at the Inlet
(Picture taken on January 17, 2008)

65. 54
the nitrogen stored in the CSW and resuspended it into the flow water. In general, little TN
removal is expected in the winter as plants are approaching the senescent stage. Therefore, they
will not be taking up nitrogen and will be potentially expelling nitrogen back into the water
column, as an excess of plant detritus near the outlet was observed.
The February 13, 2008 storm had a 2.5% reduction in the TN EMC through the CSW and
a TN mass loading removal of 96.5%. The February 26, 2008 storm had a 53.0% reduction in
TN EMC, as well as a loading removal of 75.2%. All of the inlet and outlet samples from the
February 13 storm were under the PADEP TN standard of 4.91 mg/L. Only one of the twelve
inlet samples from the February 26 storm fell above this standard. These storms had greater than
expected TN removals. As stated previously, nitrogen removal efficiency generally drops in the
winter months as CSWs are biologically dormant. However, in February the Phragmites
australis was harvested. Most of the debris was removed, and only about 20% remained in the
CSW. The stores of TN within the Phragmites were also removed during the harvest. This
could account for the larger than expected TN removal during the month of February.
The winter storm event samples had, on average, a TN EMC reduction (Graph 4.2) and a
TN mass loading removal of 15.1% and 9.6%, respectively. The extremely high load of TN at
the outlet (11926.6 g) for the January 29 storm was probably a fluke and resulted in the low
removal of TN for the winter season. Graphs 1 and 2 of Appendices H and P illustrate the winter
TN removal.
4.2.3 Spring
Concentration and mass load pollutographs for the spring storm events can be found in
Appendices E, I, M, Q and U. The March 4, 2008 and April 26, 2008 storm events had TN EMC
reductions of 68.8% and 32.9%, respectively, and TN mass loading removals of 97.2% and
95.3%, respectively. All inlet and outlet samples from the March 4 storm fell below the PADEP
TN standard of 4.91 mg/L. Six of the twelve inlet samples and one of the eight outlet samples
from the April 26 storm fell above this standard. This could be a result of nitrogen laden
fertilizers from Mendel Field being transported via runoff into Inlet Main, and in turn into the
CSW.
The April 3, 2008 storm showed no reduction in the TN EMC, but it had a 58.5%
removal of TN loading. As previously mentioned, EMC reduction and loading removal can have

66. 55
different trends for the same event because EMC is flow weighted (Equation 3.4). All of the
inlet and outlet samples were not detected by the Hach TN test as they fell below the limit of 1.7
mg/L and were assigned the value of 0.85 mg/L. This is why no EMC reduction was observed.
The average TN EMC reduction for the spring season was 42.1% (Graph 4.2), and the
average TN mass loading removal was 94.2%. The TN removal trend for the spring storms is
illustrated in Graphs 1 and 2 of Appendices I and Q.
4.2.4 Summer
Concentration and load pollutographs for the summer storm events can be found in
Appendices F, J, N, R and V. Construction and the installation of a flume were ongoing
practices in the CSW during the summer months (Figure 4.3). Due to human error, the outlet
samples from the July 14, 2008 storm were accidentally discarded before they could be tested for
TN. The May 31, 2008, July 5, 2008 and July 23, 2008 storms had TN EMC reductions of
72.2%, 69.9% and 42.0%, respectively. Each of these storms also had TN loading removals of
91.3%, 32.5% and 35.9%, respectively. All of the inlet and outlet samples from the May 31 and
July 5 storms fell below the PADEP TN standard of 4.91 mg/L. Two of the twelve inlet samples
and none of the outlet samples from the July 23 storm fell above this standard.
The average TN EMC reduction for the summer sampling period was 62.4% (Graph 4.2),
and the average TN mass loading removal for the summer was 66.8%. The removal trend for the
summer storms can be seen in Graphs 1 and 2 of Appendices N and R.
4.2.5 Nitrogen Summary for Seasonal Storm Events
The values of the average TN EMC reductions for the seasons in decreasing order are:
summer, spring, fall, winter. This trend is ideal. The summer had the greatest reduction because
it is the height of the growing season, and the winter had the lowest reduction because of
senescence.
The values of the average TN loading removals for the seasons in decreasing order are:
spring, fall, summer, winter. Both the fall and spring TN loading removals were greater than that
of the summer; this was not expected. For the year observed, the plants began to decay later in
the fall period and grow earlier in the spring period due to unseasonably warm temperatures, thus
allowing sufficient removal in both seasons. A glyphosate spraying was conducted on June 17,

67. 56
2008, thereby hindering the growth of Phragmites. With a smaller amount of plant growth and
biomass in the summer, nitrogen removal could have declined. Additionally, extensive
construction occurred at the inlet during the summer months. The water from the inlet had to be
redirected to the rest of the CSW, and a flume was installed (Figure 4.3). Earthen material had to
be moved and redistributed during this process, which would dislodge any additional stored
nitrogen, thus increasing the concentration of TN through the CSW. This could also explain as
to why less TN loading removal occurred in the summer than in the fall and spring periods.
Figure 4.3: Construction and Flume Installation at the Inlet
(Picture taken on May 29, 2008)
4.3 Total Phosphorus
Phosphorus is found in CSWs as it is a major plant nutrient, but unlike nitrogen, high
levels of long term phosphorus removal are not seen in CSWs due to the lack of a metabolic
pathway. CSWs can significantly remove phosphorus, however, through a combination of
biological, chemical and physical processes. (DeBusk, 1999)