EPA/600/B-18/320 I October 2018
www.epa.gov/homeland-security-research
United States
Environmental Protection
Agency
&EPA
Evaluation of Stormwater Detention
Basins to Improve Water Quality
and Enable Emergency Response
During Wide-Area Contamination
Incidents

Office of Research and Development
Homeland Security Research Program

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EPA/600/R-18/320
October 2018
Evaluation of Stormwater Detention Basins
To Improve Water Quality and
Enable Emergency Response During
Wide-Area Contamination Incidents
By
Rajib Sinha, P.E.
Trihydro Corporation
2702 E. Kemper Road
Cincinnati, OH 45241
James A. Goodrich and John S. Hall
U.S. Environmental Protection Agency
Cincinnati, OH 45268
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Disclaimer
The U.S. Environmental Protection Agency (EPA) through its Office of Research and
Development funded and managed the research described herein under contract EP-C-14-012
with APTIM Federal Services, LLC. It has been subjected to the Agency's review and has been
approved for publication. Note that approval does not signify that the contents necessarily
reflect the view of the Agency. Any mention of trade names, products, or services does not
imply an endorsement by the U.S. Government or EPA. The EPA does not endorse any
commercial products, services, or enterprises.
The contractor role did not include establishing Agency policy.
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Table of Contents
Disclaimer	ii
Table of Contents	iii
List of Tables	iv
List of Figures	v
Abbreviations	vii
Acknowledgements	viii
Executive Summary	ix
1.0 Introduction	12
1.1	The Effects of Urbanization on Stream Flow	12
1.2	The Purpose and Design of Detention Ponds	13
1.3	Detention Basins as Containment and Mitigation Barriers for Homeland Security	14
1.4	Research Objective	15
2.0 Detention Pond Retrofit Devices	17
2.1	Detention Basin Design and Modifications	18
2.2	Benefits from Retrofit Devices	20
2.3	Retrofit Device at Toyota Motor Sales Distribution Warehouse Detention Basin	21
2.4	Retrofit Device Installed at Boone County Schools Bus Lot Detention Basin	25
3.0 Contamination Treatment for Homeland Security Incidents	31
3.1	T&E Media Testing Apparatus	31
3.1.1	Pilot-Scale Stormwater Detention Basin Simulation	31
3.1.2	Bench-Scale Apparatus for Media Testing	34
3.2	Media Tested at the T&E Facility	35
3.3	Permeability Estimates from Media Testing	39
3.4	Contaminant Treatment Performance for Tested Media	40
3.5	Costs and Selection Criteria for Media	43
4.0 Performance Monitoring of Detention Basin Devices	45
4.1	Performance Monitoring of TMS Detention Basin Retrofit Device	45
4.2	Performance Monitoring of BCSD Detention Basin Retrofit Device	52
4.3	Measure Plugging of Media in the Field Using Falling Head Tests	57
5.0 Data Quality Assurance/Quality Control	60
5.1	Quality Metrics (QA/QC)	60
5.2	QA/QC Acceptance Criteria	60
5.2.1	Accuracy	60
5.2.2	Precision	60
5.3	Data Analysis, Interpretation, and Management	61
5.3.1	Data Reporting	61
5.3.2	Data Validation	61
6.0 Summary and Conclusions	73
7.0 References	75
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List of Tables
Table 1 - Media Tested at the T&E Facility
Table 2 - Contaminant Concentrations for Tests at the T&E Facility
Table 3 - Results of Falling Head Tests for Each Media Type
Table 4 - Results of Contaminant Testing for Each Media Type
Table 5 - Costs for Each Media Type
Table 6 - Comparison of Pre- and Post-Retrofit Peak Outflow for Measured Precipitation Events
Table 7 - Reporting Units by Analyte
Table 8 - Quality Metrics and Criteria by Analyte
Table 9 - QA/QC Summary for Ammonia, Total Nitrogen and Total Phosphorus Analysis
Table 10 - QA/QC Summary for Anions Analysis
Table 11 - QA/QC Summary for Cesium Analysis
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List of Figures
Figure 1 - Urbanization Causes Stream Degradation and Impacts Public Infrastructure
Figure 2 - Detention Ponds in Three Counties in Northern Kentucky
Figure 3 - Typical year rainfall and recurrence probabilities for Northern Kentucky
Figure 4 - Toyota Motor Sales Distribution Warehouse Site Vicinity Map
Figure 5 - Toyota Motor Sales Distribution Warehouse Detention Pond Showing Stormwater
Inlets and Retrofit Device Location
Figure 6 - Detention Pond Retrofit Device Schematic
Figure 7 - Before and After Photographs of Outlet Structure with Retrofit Device Installed
Figure 8 - Boone County School District Bus Lot Detention Pond Site Vicinity Map
Figure 9 - BCSD Bus Lot Detention Pond Showing Stormwater Inlets and Retrofit Device
Location
Figure 10 - Modified Detain H2O Device installed at the BCSD Bus Parking Lot
Figure 11 - Modified Detain H2O Device with Perforated Pipes Containing Media
Figure 12 - Before and After Photographs of BCSD Detention Pond Outlet Structure with Retrofit
Device Installed
Figure 13 - Pilot-Scale Testing Showing Storage Tanks
Figure 14 - Pilot-Scale Testing Unit Showing Test Media
Figure 15 - Pilot-Scale Test Media Chamber Containing Coated Gravel
Figure 16 - Switchgrass Sock Tested in Pilot-Scale Apparatus
Figure 17 - Bench-Scale Testing Unit.
Figure 18 - Contaminants Preparation for Use in Media Testing
Figure 19 - Correlation of Nitrogen and Phosphorous Removal
Figure 20 - E. coli Removal for Each Media
Figure 21 - Radioactivity Removal for Each Media
Figure 22 - Total Phosphorous Removal vs. Permeability
Figure 23 - Cost of the Media vs. Permeability of Media
Figure 24 - TMS Detention Basin Retrofit Device Monitoring Devices
Figure 25 - ISCO Flow Monitoring Gauge Installed at Stormwater Detention Basin Inlet
Figure 26 - TMS Detention Basin Retrofit Device with Staff Gauge (in feet) for Camera Scale
Figure 27 - Detention Basin Retrofit Device Under High Water Conditions
Figure 28 - Pre- and Post-Retrofit Outflow for Similar Precipitation Events
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Figure 29 - June 4, 2014 Post-retrofit Event with Hydrograph and Associated Photographs
Indicating a Clear Increase in Basin Storage and Restriction of the Outflow due to the Full
Submergence of the Restricted Low-Flow Pipe Outlet
Figure 30 - Pre-install Rainfall Event on May 11, 2015 and Maximum Height of Water Level
Figure 31 - Time Series Showing Estimated General Fall of Water Level Following May 11, 2015
Rain Event
Figure 32 - Post-Retrofit Install Rainfall Event on July 29, 2015 and Maximum Height of Water
Level
Figure 33 - Time Series Showing Estimated General Fall of Water Level Following July 29, 2015
Rain Event
Figure 34 - Media Chamber at BCSD Installation After Two Years of Operation
Figure 35 - Media Chamber Retrieved from BSCD Installation After Two Years
Figure 36 - Manhole Adapter to Insert Media Chamber in 5000 Gallon Tank
Figure 37 - Height of Water versus Time for Falling Head Test
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Abbreviations
A	cross-section area of the media chamber
a	cross-section area of the standpipe
Ag	silver
CFU	Colony Forming Units
cfs	cubic feet per second
Cs	Cesium
Cu	Copper
DRP	dissolved reactive phosphorous
E.coli	Escherichia Coli
EPA	Environmental Protection Agency
ft/min	feet per minute
GRO	gasoline range organics
ha	hectare
hi	height of water at the beginning of time increment in inches
h2	height of water at the end of time increment in inches
K	coefficient of permeability
km2	square kilometer
lb	pound
M	million
Mn	manganese
N	nitrogen
NH3	ammonia
NH3-N	ammonia-nitrogen
NHSRC	National Homeland Security Research Center
NO3"	nitrate
NO2"	nitrite
NOAA	National Oceanic and Atmospheric Administration
O&G	oil and grease
ORD	Office of Research and Development
P	phosphorous
PO4-P	phosphate-phosphorous
PVC	polyvinyl chloride
Qcriticai	Critical Flow
SD 1	Sanitation District No. 1 of Northern Kentucky
t	elapsed time increment
T&E Facility	Test and Evaluation Facility
TMS	Toyota Motor Sales
TN	total nitrogen
TP	total phosphorous
TPH	total petroleum hydrocarbons
TPH-DRO	total petroleum hydrocarbons diesel range organics
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Acknowledgements
Contributions from the following individuals to the work described in the report are
acknowledged: Radha Krishan, Greg Meiners, Don Schupp, Sue Witt, Nicole Sojda, LM
Narasimman, and Gune Silva of APTIM Federal Services, LLC. Robert Hawley and Katie
MacMannis of Sustainable Streams, LLC; Matt Wooten and Elizabeth Frye of Sanitation District
1 of Northern Kentucky; and Mark Jacobs of the Boone County Conservation District of
Northern Kentucky.
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Executive Summary
Detention ponds are stormwater management structures that temporarily collect runoff and then
release a reduced flow to decrease the risk of flooding. The U.S. Environmental Protection
Agency (EPA) National Homeland Security Research Center partnered with the Sanitation
District No. 1 of Northern Kentucky and the Boone County Conservation District of Northern
Kentucky to design and test detention pond outfall retrofit devices to determine the effectiveness
of these devices in eliminating stream erosion, improving receiving stream water quality, and
providing the capability to respond and mitigate wide area contamination incidents. Field studies
for this project were performed at two locations in Hebron, KY - the Toyota Motor Sales
distribution warehouse detention pond and the Boone County School District bus lot detention
pond. Bench and field-scale pilot testing for this project were performed at the EPA's Test and
Evaluation Facility in Cincinnati, OH.
Detention ponds are frequently used as a stormwater runoff best management practice to provide
general flood protection, lessen extreme floods, and improve water quality. Contaminants could
also enter the water bodies from the discharge of water used in cleanup or mitigation operations
during homeland security events (such as biological, chemical, or radiological incidents).
Concern for the intentional or unintentional contamination of water bodies have led to this report
on the removal of contaminants within detention basin structures prior to discharge to surface
water bodies or municipal wastewater treatment systems. Contaminated stormwater can be
generated as a result of intentional incidents (e.g., terrorist attacks) as well as unintentional
incidents (e.g., natural disasters, industrial spills, transportation accidents, etc.) from:
•	Washdown activities involving chemical, biological, or radiological agents from indoor-
outdoor areas;
•	Water from decontamination activities such as extinguishing industrial fires; and
•	Stormwater runoff during an incident or water infrastructure decontamination activities.
Field-scale, pilot-scale, and bench-scale tests were performed to evaluate the function of two
innovative detention basin devices that can be quickly deployed to control stormwater
contamination events within existing detention basin structures. The devices were designed with
the intention of long-term stream water quality improvements by reducing scouring of stream
beds, providing treatment of contamination that lead to stream impairment, and reducing the
spatial extent of large volumes of contaminated water from wide area contamination incidents
and mitigation efforts. A wide variety of media can be installed within the devices to remove the
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targeted contaminants expected to be in the stormwater. The media evaluated include: gravel
coated with an adsorptive media, switchgrass, granular activated carbon, natural zeolite, iron
composite metals, and ferric oxide coated media. A summary of the results obtained from both
field-scale and pilot-scale detention basin retrofit device evaluations to facilitate wide area water
quality decontamination and control of stormwater runoff flow rates is as follows:
•	A natural zeolite, switchgrass, ferric oxide powder, and coated gravel exhibited the best
removal (> 90% removal) of cesium (radioactivity surrogate).
•	Iron composite metal reduced E. coli (used as a bacterial contamination surrogate) levels
by 8 logs followed by ferric oxide powder and natural zeolite (6 logs). Switchgrass
exhibited an unexpectedly high removal capacity (4 logs).
•	All the media exhibited > 72% removal of nitrogen and >56% removal of phosphorous
which are typically related to harmful algal blooms in source waters.
•	The media exhibited a wide range of permeability which reflects how quickly the treated
water can exit the detention basin via the media. Most localities require detention basins
to be emptied within 48 hours to prevent vector growth. The coated gravel, switchgrass,
granular ferric oxide, activated carbon, and natural zeolite adequately allow flow to exit
the detention basin within that time frame. The iron composite metal and sintered metal
with copper may require an additional 24 hours whereas the ferric oxide powder and
powdered reagent mix are not likely to be able to meet these flow requirements.
•	Another practical consideration for the widespread use of media to treat contaminated
stormwater is the cost. The ferric oxide powder was, by far, the most expensive media at
$16.33/lb with switchgrass being the least expensive at $0.20/lb. The remaining media
were primarily around $3.00/lb with none exceeding $5.00/lb.
•	Full-scale installations of two variations of the detention basin retrofit prototype device
demonstrated that outlet flow rates were maintained below Qcriticai (the flow rate at which
erosion and down cutting of the receiving stream would begin) while doubling the
detention time within the basin without causing flooding of the adjacent area.
•	Post-retrofit detention basins safely detained storm events that exhibited more than twice
the total precipitation and rainfall intensity of pre-retrofit storm events.
The selection of which media to use for the mitigation of a wide area incident or traditional
stormwater runoff requires the consideration of multiple factors as described above:
1)	Identify the contaminant causing impairment or requiring treatment.
2)	Select the applicable media.
3)	Identify the detention period required to keep the discharge below Qcriticai. Narrow
your selection of appropriate media.
4)	Select the lowest cost media that meets the above requirements
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The retrofit device does not disturb the existing ground cover or require additional excavation. It
simply and cost-effectively optimizes the existing detention basin outlet to take greater
advantage of the basin's existing storage capacity. The device can be fabricated and installed
within days of an incident or as part of an emergency preparedness plan.
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1.0 Introduction
The U.S. Environmental Protection Agency (EPA), Office of Research and Development (ORD),
National Homeland Security Research Center (NHSRC) have partnered with the Sanitation
District No. 1 of Northern Kentucky (SD 1) and the Boone County Conservation District of
Northern Kentucky (BCCDKY) to design and test detention pond outfall retrofit devices to
determine the effectiveness of these devices in eliminating stream erosion, improving receiving
stream water quality, and providing the capability to respond and mitigate wide area
contamination incidents. Field studies for this project were performed at two locations in
Hebron, KY - the Toyota Motor Sales (TMS) distribution warehouse detention pond and the
Boone County School District (BCSD) bus lot detention pond. Bench and field-scale pilot
testing for this project were performed at the EPA Test and Evaluation (T&E) Facility in
Cincinnati, OH.
1.1 The Effects of Urbanization on Stream Flow
Urbanization typically results in the replacement of land features where rainwater can infiltrate
into the ground with impervious areas such as roads, parking lots, rooftops, driveways and
sidewalks, and compacted soils. These impervious areas alter the natural hydrology of a
watershed, leading to increased runoff volumes with more frequent, larger magnitude and shorter
duration peak flows. The higher runoff volumes can, in turn, result in accelerated stream bank
erosion, stream bed down cutting, and stream instability. These physical alterations to the stream
channel negatively impact water quality (e.g., increased suspended solids), and, biological
communities (through habitat disruption and/or loss). Further, these alterations can endanger
infrastructure (e.g., drinking water/wastewater pipes, power lines, roads, bridges) located
adjacent to streams necessitating costly repairs (Figure 1). The erosion of bridge supports, roads,
and pipes (wastewater, chemicals) can cause a spill or incident directly. Erosion also increases
the delivery of pollutants from the landscape to the stream. Pollutants commonly found in
stormwater runoff include sediment, nutrients, pesticides, metals, organic pollutants,
microorganisms, and oil and grease.
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Figure 1 - Urbanization Causes Stream Degradation and Impacts Public Infrastructure
12 The Purpose and Design of Detention Ponds
In practice, detention ponds serve multiple purposes. The ponds help manage the excess runoff
generated by constructed impervious surfaces such as roads, parking lots, and rooftops. To
mitigate the adverse effects of urbanization on stormwater flow, detention ponds are frequently
used as a stormwater best management practice (BMP) to provide general flood protection and
lessen extreme floods. Detention ponds can also lessen downstream erosion by storing water for
a limited period of a time. With the retrofitting of detention ponds, they can also be capable of
incorporating water quality filtration media.
However, detention ponds do not remove all risk of flooding and downstream erosion. Thus,
optimizing detention facilities to economically release runoff below the flow rate at which
erosion and down cutting of the receiving stream begins for small and intermediate storm events
would enable stormwater managers and sanitation districts nationwide to address multiple
objectives, including hydromodification, water quality, and flooding issues within the watershed.
When factoring in the economic benefits that more stable stream channels have on the life-
extension of adjacent infrastructure (roads, bridges, and pipes), this approach has the potential
for a high rate of return beyond that of water quality and habitat preservation.
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A detention pond functions by allowing large flows of water to enter the pond, but it limits the
outflow by having a small opening near the bottom of the structure. It is this outflow opening
that can provide the filtration function when retrofitted with a filtration device and media.
1.3 Detention Basins as Containment and Mitigation Barriers for Homeland
Security
Concern for the contamination of water bodies has led to this research on the removal of
contaminants within detention basin structures prior to discharge of the contained water to
surface water bodies or municipal wastewater treatment systems. Contaminated stormwater can
convey pollutants that can contaminate water sources and have tremendous effects including loss
of life, extensive contamination of infrastructure and environment, and fiscal strain from
recovery and remediation efforts.
The contamination can arise from numerous sources. Chemical, biological, and radiological
(CBR) contaminants could enter the stormwater infrastructure following an intentional (e.g.,
terrorist attacks) and unintentional (e.g., natural disasters, industrial spills, transportation
accidents) incident from:
•	Washdown activities involving chemical, biological, or radiological contaminants from
indoor-outdoor areas
•	Water from decontamination activities such extinguishing industrial fires, or
•	Stormwater runoff during an incident or following decontamination activities.
The stormwater infrastructure pipes and basins incorporating strategically located multiple large
detention basins could provide the volume necessary to contain and treat such amounts of
contaminated water limiting the spatial extent of contamination. Such watershed assets (with
retrofit devices) strategically located in a catchment area also contribute to the resilience of urban
and suburban land use mitigating and containing wide area incidents. The use of various media
has been considered as an effective and economical means for biological, chemical, and
radiological contaminant removal. The adsorption or treatment potential of filtering media could
enable the containment and removal of contaminants without generating environmentally large
volumes of hazardous byproducts.
This approach may also be one of the most cost-effective investments in water quality and
emergency response because of the abundance of traditional detention basins and their
cumulative potential to be retrofitted toward a less erosive flow regime for channel stability,
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habitat, and ecosystem functionality. Detention basins are ubiquitous stormwater management
facilities particularly in suburban areas that were developed as early as the 1980s (Hawley et al.,
2017). For example, Figure 2 shows that in one approximately 36-square mile suburban
watershed of Northern Kentucky with an average impervious cover of about 25%, there are an
estimated 535 detention basins or an average of 1 detention basin per 18 hectare (ha). Using
average values for basin size and present-day construction costs (Hawley et al., 2012b), the
order-of-magnitude value of these assets is scaled to approximately $60 M, or an average of
$600,000 in stormwater management assets per square kilometer within the watershed.
1.4 Research Objective
The objective of this research project is the development, deployment, and testing of a water
quality treatment system/apparatus that can be integrated into existing stormwater detention
basins as a retrofit device. The device design will utilize existing detention basin infrastructure
to hold stormwater runoff and control the release rate of stormwater to prevent erosion using an
orifice plate or by media that can also provide an effective and economical means for biological,
chemical, and radiological contaminant removal. This research project also tested the adsorption
or treatment potential of several such media materials with the goal of identifying low-cost
materials that can be handled easily, deployed quickly, and can be customized to match the
treatment needs of an impaired stream.
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Figure 2 - Detention Ponds in Three Counties in Northern Kentucky
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2.0 Detention Pond Retrofit Devices
Conventional stormwater management typically exacerbates channel erosion since BMPs
designed for peak flow detention typically has little to no attenuating effect on 97-99% of the
precipitation volume in a typical year (Emerson et al., 2003; Hawley, 2012). Runoff volumes
above the critical flow (Qcriticai) (the flow rate at which erosion and down cutting of the receiving
stream would begin) for the mobility (erosion) of stream bed material (e.g., cobbles, gravel,
sand) is both geomorphically and ecologically relevant (Poff, 1992; Townsend et al., 1997).
Figure 3 graphically illustrates the typical year rainfall and recurrence probabilities for Northern
Kentucky.
The initial goal of this research project was to develop simple devices that can reduce the
cumulative erosive power in a receiving stream by restricting the more frequent storm events (up
to the two-year storm) to be released below Qcriticai and achieving comparable flood control
performance of the pre-retrofit configuration during larger and more infrequent events (5-, 10-,
25-, 50-, and 100-year events). The device should also improve water quality and be relatively
easy to install, with minimal, if any need for heavy equipment. Due to the risks associated with a
failure of the device during a large event such as the 100-year storm, the device should also
minimize the reliance on moving parts to the extent possible, or have otherwise fail-safe controls
to ensure adequate performance during flood events (i.e., incorporate overflow or other high-
water relief methods). Furthermore, the device should be economical, with the design, materials,
and installation on the order of-$10,000 per detention basin, with potential opportunities for
additional cost savings if using a utility's in-house staff for design and/or installation.
To meet these goals, two devices were designed and field tested:
A prototype of the Detain FhO (patent pending) retrofit technology installed at the Toyota
Motor Sales distribution warehouse detention basin in Hebron, KY.
A prototype of a modified Detain FhO device with increased treatment capabilities
installed at the Boone County School District Bus Lot in Hebron, KY.
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Figure 3 - Typical year rainfall and recurrence probabilities for Northern Kentucky
2.1 Detention Basin Design and Modifications
Until as recently as the last decade, detention basins were almost exclusively designed to meet
flood protection criteria that typically involved managing stormwater runoff from new
developments such that peak discharges did not exceed those of the predeveloped conditions for
specific flood frequency recurrence intervals such as the 2-, 10-, 25-, 50-, and 100-year design
storms (Roy et al., 2008, Clar et al., 2004). Because conventional development practices
invariably create greater runoff volumes than predeveloped watersheds, the so-called "peak
matching" strategy nearly universally results in prolonged durations of flows with relatively high
magnitudes (Bledsoe, 2002). In many streams this results in increased durations of flows that
exceed the Qcriticai for bed particle mobilization because Qcriticai can be considerably less than the
two-year peak flow, particularly in streams with bed material composed of small cobbles,
gravels, or sand (Rohrer and Roesner, 2006; Pomeroy et al., 2008; Hawley and Vietz, 2016).
Indeed, conventional peak-matching designs can result in longer durations of flows that have the
power to erode the streambed in such gravel and sand-dominated streams (Bledsoe, 2002).
Furthermore, because the two-year flow tends to be the smallest discharge that conventional
detention basins are optimized to control, these stormwater facilities tend to have little
attenuating effects on more frequent precipitation events, with one study suggesting that up to
97% of the events in a typical year have essentially no attenuation (Emerson et al., 2003).
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As a consequence of this design philosophy, lesser storms such as the 3-mo or 6-mo event that
may not have caused stream erosion under predeveloped conditions may be amplified and
discharged at rates that exceed Qcriticai under post-developed conditions. The cumulative effect is
that conventional stormwater management policies tend to increase the frequency, duration,
and/or magnitude of flows that exceed the threshold for stream channel erosion in developed
watersheds (MacRae, 1997; Konrad and Booth, 2002; Rohrer and Roesner, 2006; Pomeroy et al.,
2008). These policies have also failed to preserve other elements of the natural flow regime that
can be important for stream integrity (Poff et al., 1997), with, for example, urban and suburban
streams almost universally exhibiting flashier flow regimes than rural streams from the same
hydroclimatic setting (Poff et al., 2006; Eng et al., 2013).
The widespread application of the peak-matching management strategy across North America
has allowed numerous researchers to point to its ineffectiveness in protecting stream integrity —
despite large investments in stormwater infrastructure, the biological, chemical, and physical
integrity of streams in urban and suburban watersheds substantially departs from those in
undeveloped watersheds (Booth, 2005; Walsh et al., 2005; NRC, 2009). For example, in
developed watersheds with widespread incorporation of peak-matching control strategies, urban
and suburban streams tend to have enlarged and more unstable channels with actively eroding
banks and more homogenous habitat than those in rural watersheds (MacRae, 1997; Hawley et
al., 2013a). These impacts have become so ubiquitous that "hydromodification," which among
other types of hydrologic modification includes urban-induced flow amplification and associated
channel erosion, is listed as the second most common source of impairment in U.S. rivers and
streams (EPA, 2009).
Another consequence of this hydromodification impacts roads, power utilities, and water/sewer
infrastructure that are commonly placed adjacent to and across streams. Urban-induced channel
erosion, downcutting, and widening can necessitate repairs, stabilization efforts, impair water
quality, and/or cause premature replacement/relocation. For example, using costs from Northern
Kentucky, Hawley et al. (2013b) estimated approximately $10,000, $1,000, and $350 per km2-yr,
in impacts to roads, sewers, and power utilities, respectively, that were attributable to channel
erosion.
For these and other reasons, there is a growing consensus that more effective stormwater
management is needed (Roy et al., 2008; NRC, 2009). This includes a need for more sustainable
strategies that preserve stream integrity downstream of new developments as well as cost-
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effective strategies that begin to reverse the trajectories of degradation in previously developed
watersheds. It follows that systematically retrofitting the ubiquitous, conventionally designed
detention basins to minimize the extent of channel erosion in receiving streams would be
beneficial to both the built and natural environment, would enable degraded streams to come into
compliance with the Clean Water Act (CWA), and in addition, would provide an emergency
response tool.
2.2 Benefits from Retrofit Devices
Future Federal or State stormwater regulations are likely to require some level of water quality
improvement. In terms of water quality criteria, the Kentucky Division of Water currently
requires a water quality volume approach in SDl's stormwater permit. In SDl's corresponding
Rules and Regulations for new development, the first 0.8 inches of rainfall (the 80th percentile
event) must pass through a water quality best management practice device before being
discharged from the site. Theoretically, there may be some level of water quality improvement
within a detention pond due to the stormwater being held promoting particle settlement and
biological uptake. Data collected under this project indicate that typical detention ponds provide
little detention time with stormwater passing quickly downstream for most storm events.
Although the retrofit devices will increase the residence time and reduce sediment in the water
column to some degree, there still exists the need to reduce dissolved water quality contaminants
such as synthetic and volatile organic contaminants from roads, vehicles, and emission exhaust
as well as pesticides and fertilizers from agricultural and residential application or chemicals
from industrial, transportation, or nuclear incidents.
The retrofit design approach recognizes the role of the geomorphic setting in connecting
watershed hydrology with stormwater infrastructure. For example, retrofitting a detention basin
that exceeds Qcriticai approximately two to four times per year under a conventional design to a
regime that does not exceed Qcriticai more frequently than once every two years would be a four-
to-eightfold decrease in disturbance frequency. A retrofit strategy that restores a more natural
disturbance regime may enable the transformation of an impaired aquatic community dominated
by fast-lived multivoltine organisms (i.e. those producing two or more broods per year) to a more
diverse community that included longer-lived species such as univoltine or semivoltine
organisms (Townsend et al., 1997). It may also provide enough time for vegetation to
successfully colonize recently deposited sediment at the toes of otherwise unstable streambanks,
increasing the probability of a shift from an erosional state of channel evolution as described in
the Channel Evolution Model (CEM) proposed by Schumm et al. (1984) to a recovered state of
equilibrium.
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Facilitating such changes to the flow regime that is stored, treated, and discharged from a
conventionally designed detention basin does not necessarily require expensive regrading or
additional excavation to make the storage volume larger. Indeed, retrofit strategies that are able
to meet ecologically and geomorphically relevant hydrologic design goals within the limits of the
existing facility have the potential to be much more cost-effective than those that require
additional excavation. For example, even relatively minor earthwork, such as excavating the
bottom -0.9 m of soil and replacing it with amended soil media that promotes infiltration could
cost -$50,000 to $100,000 on a small basin draining -6.5 ha, whereas simply reconfiguring the
outlet control structure in the absence of additional excavation would be more likely to cost -
$5,000 to $10,000 per basin. Furthermore, considering that these facilities are designed to have
stormwater runoff directed to them during nearly every storm, approaches that require earthwork
within the detention basin can create additional challenges by denuding existing vegetation
ground cover, which not only requires reestablishment after construction but poses risks to water
quality in terms of construction site sediment runoff. The scale of the problem as well as the
abundance of conventional detention basins underscore the potential benefits of developing a
simple, cost-effective strategy for achieving the retrofit performance goals (i.e., with limited
funds for stormwater investments, low cost strategies have the potential to restore much greater
stream lengths than higher costing alternatives). Stormwater treatment is not a new concept (Pitt
et al., 1999) by large scale buried media vaults or regrading of the site which are very expensive
and limited by site constraints and adjacent land use. The proposed retrofit device strategy does
not disturb the existing ground cover or require additional excavation, but simply optimizes the
existing outlet to take greater advantage of the basin's existing storage capacity and can be
fabricated and installed within days of an incident. The retrofit device would also be available to
serve as a washwater containment or treatment facility as part of a wide area emergency response
mitigation effort.
2.3 Retrofit Device at Toyota Motor Sales Distribution Warehouse Detention Basin
The TMS Distribution Warehouse is located in Hebron, KY near the Cincinnati/Northern
Kentucky International Airport (Figure 4). The site is a large Industrial Property of
approximately 31 acres, with more than 52% impervious cover.
Figure 5shows the location on the retrofit installation in the detention pond. The device is
comprised of an orifice plate that reduces the size of the outlet opening, thus reducing the flow
rate exiting the detention basin (Figure 6 and Figure 7). The snorkel passively bypasses high
levels of detained water from within the basin to prevent flooding under extreme storm events.
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^Imagery Date; 4/11/2017 39°03'59.65" N 84'"41'06.62\"W eiev . 863 ft eve alt^.25107 ft
Figure 4 - Toyota Motor Sales Distribution Warehouse Site Vicinity Map
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Inlets
Small Receiving Stream
Detention
Pond
Detain H2O
Device
Map data @2018 Google
Figure 5 - Toyota Motor Sales Distribution Warehouse Detention Pond Showing
Stormwater Inlets and Retrofit Device Location
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Figure 6 - Detention Pond Retrofit Device Schematic
Figure 7 - Before and After Photographs of Outlet Structure with Retrofit Device Installed
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2.4 Retrofit Device Installed at Boone County Schools Bus Lot Detention Basin
The BCSD Bus Lot is located in Hebron, KY and also near the Cincinnati/Northern Kentucky
International Airport (Figure 8). The site is a large paved impervious area where school buses
are parked when not in use. The parking lot also includes a 2,000-gallon diesel tank for fueling
the buses. Figure 9Figure 8 shows the location of the retrofit installation in the detention pond.
Figure 10 shows the new retrofit device designed for this location. The device consists of a base
structure with three flanged inlet openings capable of accepting a 4-inch PVC pipe. A solid or
perforated PVC pipe 3 feet in length or longer can then be filled with an appropriate media and
attached to these flanges. The center opening is fitted with a float attached to a flapper valve.
This opening allows a variable volume to pass depending on the level of water in the basin thus
modulating the length of time water stands in the detention basin. Finally, the device includes an
overflow to avoid flooding should the rate of water flow through the other openings in the device
prove to be too slow. The center float valve can be replaced with another pipe containing media
based on the circumstances of the installation. Figure 11 shows the device outfitted with
perforated PVC pipes containing media. Figure 12 shows the stormwater outflow structure
before and after the installation of the retrofit device.
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¦MgatewaV"
tone Count^ySchi
is Parking Lot
. ^PfiheelofHBi
Figure 8 - Boone County School District Bus Lot Detention Pond Site Vicinity Map
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Modified
Detain H;0
Device
%
Inlets
Small Receiving Stream
©2018 Google
Figure 9 - BCSD Bus Lot Detention Pond Showing Stormwater Inlets and Retrofit Device
Location
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Valve to Release
Base Device with
Three Flanged
Ports
Figure 10 - Modified Detain H2O Device installed at the BCSD Bus Parking Lot
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llilfiil
• • " ''^4 ' ' ; : q1
mm
Figure 11 - Modified Detain H2O Device with Perforated Pipes Containing Media
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Figure 12 - Before and After Photographs of BCSD Detention Pond Outlet Structure with
Retrofit Device Installed
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3.0 Contamination Treatment for Homeland Security Incidents
The detention basin retrofit devices are effective in reducing the outflow rates below the flow-
critical values to reduce downstream erosion of the channel bed and bank and reduce the spatial
extent of contaminated stormwater. These units are also capable of incorporating water quality
filtration media. Stormwater will not only be temporarily detained, but multiple stormwater
pollutants (e.g., nutrients, pesticides, microorganisms, and roadway runoff) will be mitigated as
well. During emergency response mitigation/recovery efforts for biological, chemical, or
radiological contaminated water could be fully retained within a detention basin by retrofit
devices that to treat all the water for discharge, disposal, or further treatment at a wastewater
treatment plant. Potential filtration media range from natural products such as mulch,
switchgrass, sand, and gravel to various grades of granular activated carbon and other
manufactured media designed for specific classes of contaminants. Additionally, for a more
expeditious evaluation of water quality filtration media relative to real-world flow rates,
pressures, and contact times, a pilot-scale experimental apparatus was constructed at the EPA
T&E Facility.
3.1 T&E Media Testing Apparatus
3.1.1 Pilot-Scale Stormwater Detention Basin Simulation
An experimental system was installed at the T&E Facility to simulate a stormwater basin and
associated detention basin retrofit device as shown in Figure 13 through Figure 16. The
experimental device was intended to simulate the field installation while enabling controlled
flow rate and media performance evaluations.
The flow rate through the pipe was initially determined as a function of pressure (10 ft. of water
maximum pressure) with no restriction (media) in the outlet pipe. The flow/pressure control
valves were then gradually closed to reduce the pressure in the pipe while the flow rate was
recorded. Following the generation of the flow rate vs. pressure curve, treatment media was
inserted into the Test Media section of the pilot-scale device. Different types of media detailed
in Section 3.2 were evaluated in this experimental system. Flow rate vs. pressure curves (10 ft.
of water maximum pressure) were generated for each of the media in the same manner as the
initial testing.
The system is capable of testing two types of media (or run a duplicate test simultaneously). The
parameters to be measured during the tests are the following:
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•	Flow rate
•	Pressure
•	Influent/effluent water quality
The flow rate and the pressure were measured for each retrofit media. The flow meter is a
Toshiba (Tokyo, Japan) 3-inch magmeter (Model No. 335-379 80) and the pressure gauge is an
analytical gauge.
For each test, the pressure was ini tially set at 10 ft. of water and the flow rate was measured.
The pressure was then reduced using the flow/pressure control valves, and the flow rate
measured when the pressure and flow stabilized for 15 minutes.
Each media was packed into a 4-inch by 48-inch pipe designed to serve as the vessel to hold the
media during flow simulations (essentially the same size as the Bus Lot media installation).
Prior to testing for removal of contaminants, the flow rate through the system was evaluated to
estimate the percent occlusion provided by each device by utilizing a falling-head permeability
test in which a known volume of water flowed through the selected media housed within a
perforated pipe with a calculated equivalent cross-sectional area.
Figure 13 - Pilot-Scale Testing Showing Storage Tanks
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Meters
Test
Media
Simulated
Detention
Flow/Pressure
Control Valves
Figure 14 - Pilot-Scale Testing Unit Showing Test Media
'a
Figure 15 - Pilot-Scale Test Media Chamber Containing Coated Gravel
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Figure 16 - Switchgrass Sock Tested in Pilot-Scale Apparatus
3.1.2 Bench-Scale Apparatus for Media Testing
Figure 17 shows the bench-scale burette testing apparatus for media that could not be tested in
the pilot-scale apparatus either because insufficient quantities of the test media were available or
because the permeability was too low such that the flow rate could not be practically measured in
the falling head tests.
Figure 17 - Bench-Scale Testing Unit.
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3.2 Media Tested at the T&E Facility
The generic contaminants tested to determine the adsorption/absorption potential of different
media included:
1)	Petroleum hydrocarbons in the diesel range (C10-C20),
2)	Motor oil,
3)	Nitrogen (N) and Phosphorus (P) containing soluble fertilizer (Scott's Miracle Gro),
4)	Escherichia Coli (E. coll), and
5)	Cesium (Cs), a surrogate for radioactive material.
The tested media are shown in Table 1 which also shows the apparatus used to test each media as
well as the contaminants that are assumed to be targeted by each media. The media-contaminant
combinations for testing were based upon the applicability of the respective media for removing
various contaminants and thus not all media were evaluated for all contaminants.
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Table 1 - Media Tested at the T&E Facility
Media
Description
Target Contaminants
Apparatus
Reference -1.5"
Rock
Reference -1.5" Rock
Baseline Reference
Pilot Test
Osorb
#4 gravel coated with an organo-
silica adsorptive media from
ABS Materials, Wooster, OH
Oil & Grease
Nutrients (N &P)
Pilot Test
Switchgrass
Switchgrass, chopped into
~6inch strips and placed in a
mesh sock. From BEG Group,
Cambridge, OH
Nutrients (N&P)
Oil & Grease
Radioactive compounds
Pilot Test
Activated Carbon
Filtrasorb® 400 Granular
Activated Carbon placed in a
sock. From Calgon Carbon.
Moon Township, PA.
Oil & grease
Nutrients (N&P)
Organic compounds
Radioactive compounds
Pilot Test
Clinoptiolite
Microporous arrangement of
silica and alumina tetrahedral.
Natural Zeolite from Bear River
Zeolites, Preston, Idaho.
Metals
Pilot Test
Cleanlt LC Plus
Iron composite metal with high
internal porosity placed in a
sock. FromHoganas
Enviromnent Solutions LLC,
Cary, NC.
Metals
Burette
Cleanlt CU
A sintered metal with silver and
copper disinfectant media placed
in a sock. From Hoganas
Environment Solutions LLC,
Cary, NC.
Bacteria
Burette
Coarse E33
Iron oxy hydroxide powder
coated media from AdEdge
Water Technologies, Atlanta,
GA.
Metals (e.g., arsenic)
Bacteria
Pilot Test
Granular E3 3
Granular Ferric Oxide media
from AdEdge Water
Technologies, Atlanta, GA.
Metals (e.g., arsenic)
Bacteria
Burette
Powdered Rembind
Mix of activated carbon,
aluminum hydroxide from
Tersus Enviromnental, Wake
Forest, NC.
Organic
Pilot Test and Burette
N - nitrogen; P - phosphorus
Influent concentrations of each contaminant/contaminant source for a typical media test are
outlined in Table 2 and Figure 18 shows the preparation of a contaminant solution. Each
contaminant was mixed either separately or as a mixture in tap water dechlorinated using
granular activated carbon (GAC) water to achieve the specific contaminant concentration. Due
to the low solubility of diesel, a pre-prepared petroleum diesel saturated water was used to obtain
influent solution based on Total Petroleum Hydrocarbon Diesel Range Organics (TPH-DRO)
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concentration. The proposed influent concentrations for fertilizer and diesel were based on TN
and TPH concentrations, respectively. Respective concentrations of fertilizer and Cs were
prepared by mixing both components in water. E. coli influent solution of 106 CFU/100 mL was
prepared by mixing 40mL of stock is. coli at 1011 CFU/100 mL grown at the T&E facility in a
nutrient broth at 37°C into 40 L of dechlorinated tap water. Two gallons of motor oil (Mobil
SAE 10W-30) purchased from Walmart was mixed with 18 gals of water to achieve the desired
influent concentration of 15 mg/L. In order to prepare a solution of TPH, 1 part of commercially
purchased diesel from a local fuel station was mixed with 9 parts of water and the resultant
mixture was stirred for 24 hours (Irwin 1997). This diesel-saturated water (drained from the
bottom of the separator funnel) typically resulted in a solution containing 20 mg/L of TPH. Grab
samples of each influent solution (Petroleum diesel, Motor oil, Fertilizer, Cs and E.coli in water)
were analyzed to verify the application rates (Table 2).
Table 2 - Contaminant Concentrations for Tests at the T&E Facility
Contaminant Sources
Types of
Contaminants
Proposed Influent Concentration (mg/L)
Petroleum diesel
TPH
0.5
DRO
As measured as a component of TPH
GRO
As measured as a component of TPH
Motor Oil
O&G
15
Miracle-gro fertilizer
TN
25
nh3
As measured as a component of fertilizer
N03-
As measured as a component of fertilizer
N02"
As measured as a component of fertilizer
TP
As measured as a component of fertilizer
DRP
As measured as a component of fertilizer
Cs
Cs
0.1
E. coli
E. coli
106 CFU/100 mL
The water used for the falling head tests was spiked with various contaminants so that the same
tests could also be used to estimate contaminant removal in accordance with Table 2. The
prepared influent solution was transferred into the water tower to conduct the falling head test.
These tests, designed to evaluate the flow rate through the system to estimate the percent
occlusion provided by each device, utilized a known volume of water that flowed through the
selected media housed within the test apparatus with a calculated equivalent cross-sectional area.
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A grab sample of the effluent water (after passing through the media) was collected at the water
discharge port 30 seconds after the initiation of the falling water head test. Each contaminant
and each media were tested in duplicate.
It is important to maintain a similar coefficient of permeability and contact time among media
for a better comparison of contaminant adsorption. To achieve a similar coefficient of
permeability, media was packed in the test media pipe or in the burette. After determining the
coefficient of permeability of respective media, dechlorinated tap water was run as a control test
prior to running contaminated water through the media. Influent and effluent samples were
collected from both control and contaminated water tests to determine the adsorption capacity.
Figure 18 - Contaminants Preparation for Use in Media Testing
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3.3 Permeability Estimates from Media Testing
The permeability for the falling head tests were computed using the equation:
K = (aL/At) In (hi l\\i)
Where:
K = coefficient of permeability [feet/minute (ft/min)]
a = cross-sectional area of the standpipe (ft2)
L = Length of media chamber (ft)
A = cross-sectional area of the media chamber (ft2)
t = elapsed time increment (min)
hi = height of water at the beginning of time increment [inches (in)]
h2 = height of water at the end of time increment (in)
Table 3 shows the results for each media in descending order of permeability as well as a
calculation of drainage time versus the reference media. The 'time to drain' is an important
factor in that most localities (under normal operation) require detention basins to hold water no
longer that 48-72 hours to reduce the potential for mosquito or other vector growth. Thus, as an
example, if a basin requires 1 hour to drain through a media bed of rock, that same basin will
require 6 hours to drain if switchgrass was uses as the media.
The 'time to drain' also represents the relative permeability of each media. As seen in Table 3,
media with larger particles (such as coated gravel) have high permeability whereas powdered
material exhibits a high resistance to water flow (i.e., low permeability). The Rembind media,
which is marketed as a soil amendment for the adsorption of organic compounds, proved to be
practically impermeable.
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Table 3 - Results of Falling Head Tests for Eac
l Media Type




Time to Drain

Media
Generic Reference
K

(vs.
Reference)/
Relative
Permeability
Apparatus
Reference - 1.5"
Reference - 1.5"




Rock
Rock
28.90
ft/min
1
Pilot Test
Osorb
Coated Gravel
11.55
ft/min
3
Pilot Test
Switchgrass
Switchgrass
4.82
ft/min
6
Pilot Test

Granular Ferric




Granular E33
Oxide
0.89
ft/min
32
Burette
Activated Carbon
Activated Carbon
0.68
ft/min
43
Pilot Test
Clinoptiloite
Natural Zeolite
0.63
ft/min
46
Pilot Test
Cleanlt LC Plus
Iron composite
metal
0.44
ft/min
66
Burette

Sintered Metal with




Cleanlt CU
Cu
0.39
ft/min
74
Burette

Ferric Oxide




E33
Powder
0.15
ft/min
193
Pilot Test
Powdered
Powdered Reagent




Rembind
Mix
Very small

Very Long
Pilot Test
Acronyms: ft, foot; K, coefficient of permeability; min minute
3.4 Contaminant Treatment Performance for Tested Media
Table 4 shows the performance of each media for the removal of challenge contaminants. The
data shows that the tested media performed well for the removal of nutrients and radioactivity.
Media geared towards the removal of microorganisms also performed well.
Figure 19 shows the correlation of Nitrogen and Phosphorous removal. Clinoptiolite
demonstrated the highest removal of both nutrients although most media performed well in this
regard.
Figure 20 illustrates the performance of media in removing bacterial contamination (with /•]. coli
as the surrogate). The Cleanlt LC Plus performed the best, but the copper-based Cleanlt CU
demonstrated the lowest disinfection percentage. Switchgrass exhibited an unexpectedly high
removal capacity.
Figure 21 shows the performance of each media in removing radioactivity as represented by
Cesium. Clinoptiolite, switchgrass, and Osorb performed the best for these tests.
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Table 4 - Results of Contaminant Testing for Each Media Type


Nutrients
Radioactive
Bacteria
Parameter

Total N
NHj-N
Total P
P04-P
Cesium
E. coli
Media
Description
Description
% Removal
% Removal
% Removal
% Removal
% Removal
Log
Removal
Osorb
Coated Gravel
90.0
78.0
100.0
86.0
92.0
0.0
E33
Ferric Oxide Powder
76.0
78.0
100.0
98.0
94.0
6
Switch
Grass
Switchgrass
92.0
76.0
64.0
90.0
94.0
4
Activated
Carbon
Activated Carbon
94.0
76.0
90.0
84.0
80.0
4
Clinoptiolite
Natural Zeolite
94.0
80.0
88.0
86.0
96.0
6
Granular
E33
Granular Ferric
Oxide
66.0
74.0
100.0
100.0
NT
2
Cleanlt CU
Sintered Metal with
Cu
72.0
78.0
56.0
54.0
NT
2
Cleanlt LC
Plus
Iron Composite
Metal
80.0
80.0
100.0
100.0
NT
8
NUTRIENTS
(NITROGEN AND PHOSPHOROUS REMOVAL)
100.0%
90.0%
80.0%
_ 70.0%
10
>
^ 60.0%
-------
E.COLI TREATMENT






1



T~







¦







Mm











|0QU|y

1






o


o
















o o








Granular Ferric Oxide
Sintered Metal
/	wfth Cu	



Activated Carbon


(E33)
—o— —o—


Coated Gravel
//-»	LI








>







Figure 20 - E. coli Removal for Each Media
RADIOACTIVITY REMOVAL (CESIUM)
r
9 c



ft
	ri

BMIiHMiE
Sintered Metal with Cu
(Cleanlt Cu)
Granular Ferric Oxide
(E33)
Iron Composite Metal
(Cleanlt LC PLus)
Figure 21 - Radioactivity Removal for Each Media
Page 42
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3.5 Costs and Selection Criteria for Media
Table 5 presents the costs for each tested media. There is a wide range in costs ranging from the
cheapest (Switchgrass) at $0.20/lb to E33 at $16.33/lb. Thus, the selection of media for a
specific application should be examined through the following criteria:
1)	Identify the contaminant causing impairment or requiring treatment (as part of an
emergency preparedness plan).
2)	Select the appropriate media from Table 4 and from charts such as Figure 22 (which
shows the total phosphorous removal versus the permeability).
3)	Identify the detention period required to keep the discharge below Qcriticai. Select
appropriate media from Table 3.
4)	Use Table 5 to determine the lowest cost media that meets other requirements for
treatment.
Future research will identify the expected time the various media will perform well until needing
to be replaced. Media contaminated with dangerous contaminants would have to be disposed
appropriately. Figure 23 shows the correlation between permeability and cost. This graph can
also help in visually identifying the cost-effectiveness of each media depending on the retention
desired.
Table 5 - Costs for Each Media Type
Media
Generic Reference
K
Apparatus
Cost/lb
Osorb
Coated Gravel
11.55
fit/min
Pilot Test
$2.92
Switchgrass
Switchgrass
4.82
fit/min
Pilot Test
$0.20
Granular E33
Granular Ferric Oxide
0.89
fit/min
Burette
$16.33
Activated Carbon
Activated Carbon
0.68
fit/min
Pilot Test
$3.02
Clinoptiloite
Natural Zeolite
0.63
fit/min
Pilot Test
$2.12
Cleanlt LC Plus
Iron composite metal
0.44
fit/min
Burette
$2.72
Cleanlt CU
Sintered Metal with Cu
0.39
fit/min
Burette
$5.00
E33
Ferric Oxide Powder
0.15
fit/min
Pilot Test
$16.33
Powdered Rembind
Powdered Reagent Mix
Very small

Pilot Test
$4.44
Acronyms: ft, foot; K, coefficient of permeability; lb, pound; min, minute
Page 43
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TOTAL PHOSPHOROUS REMOVAL VS PERMEABILITY
100
90
80
0
1	70
cc
3 60
o
2. 50
Q.
w
2	40
Q.
» 30
£
S? 20
10
0
0	50	100	150	200	250
Relative Permeability vs. Reference (from Table 3)
Osorb r Granular E33 - Cleanlt LC Plus
o o
	H
o
Activated Carbon
o





Clinoptiloite



O Switchgrass
Cleanlt
: CU



6




























Figure 22 - Total Phosphorous Removal vs. Permeability
COST VS PERMEABILITY
i r "3—
Granular E33
o a








































O Cleanlt CI
Activated Carbon



Osorb

Cleanlt LC Plus


o

J
Clinoptiloite Switchgrass
1 Q



6.00	8.00
Permeability ft/min
12.00	14.00
Figure 23 - Cost of the Media vs. Permeability of Media
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4.0 Performance Monitoring of Detention Basin Devices
4.1 Performance Monitoring of TMS Detention Basin Retrofit Device
Monitoring of the retrofit performance of the Detain H20 device was conducted using a suite of
time-series data including:
(1)	time-series photographs of basin stage;
(2)	outflow and inflow pipe discharge (via area-velocity meters); and
(3)	rain gages
Figure 24 shows the TMS detention basin with devices installed to monitor the performance of
the system. Trail cameras were mounted to capture photographs at 10-minute intervals of the
inlet and the outlet of the system. A staff gage was mounted at the inlet to the retrofit device to
provide a scale (in feet) for the photos (Figure 26).
Flow into the detention basin included two pipe inlets and one swale, along with direct
precipitation and local drainage. The outflow of the basin was routed through a network of
staged pipes that were connected to a single 81-cm-diameter outflow pipe on the downstream
side of the berm. The basin was designed for flows greater than the 100-year design event to
discharge through a concrete spillway. Three pipe-flow meters (ISCO model 2150) were
donated to the project by Teledyne ISCO and recorded measurements at 15-min intervals.
Figure 25 shows one of the ISCO gauges installed at an inlet location. The gauges were installed
according to the manufacturer's specifications and data were downloaded and processed using
their software (Flowlink® 5.1, Teledyne ISCO, Lincoln, Nebraska) and protocols. These data are
typically considered to have precision of-2%, with the exception of extremely low flows, which
go unrecorded due to minimum depths that are required for accurate area-velocity measurements
to register. Access to monitoring equipment was limited by project funding phases and by the
timing of equipment donations; equipment was deployed as it became available. The initial pipe
monitoring deployment included installations on the downstream side of the 81-cm outflow pipe
and on one of the two inflow pipes to the basin. When the third gauge became available, the
second inflow pipe was also gaged. All other inputs into the basin, including the swale and local
drainage remained ungauged.
Data were screened for outliers, and values that were determined to be erroneous, such as points
that were recorded during data downloads when the transducers were out of the water, were
Page 45
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systematically removed. An ISCO 4150 Flow Logger, also from Teledyne ISCO, was installed
at the site and collected incremental rainfall at 10-min intervals. Hourly precipitation data from a
NOAA station located at the Cincinnati/Northern Kentucky International Airport, which was less
than about 2 km away from the site, served to validate the site data.
Figure 27 shows the retrofit device under high water conditions. This photograph shows the
device holding back water within the containment basin thus utilizing a greater volume of the
existing infrastructure.
Table 6 presents the pre- and post-retrofit peak outflow for two comparative precipitation events
and demonstrates that the peak outflow is similar up to a doubling of rainfall thus demonstrating
significant detention within the basin.
Figure 28 shows the pre- and post-retrofit flows for similar precipitation events. The pre-retrofit
event (October 31, 2013) had a smaller peak rainfall intensity (1 in/h) but larger peak discharge
[6 cubic feet per second (cfs)] than the post-retrofit event (April 2, 2014, peak intensity 1.2 in/h,
peak discharge 5.3 cfs). The post-retrofit event also received more than twice the total rainfall
than the pre-retrofit event (2 inches compared 0.9 inches), adding to the weight of evidence of
the restrictive effect of the retrofit device.
A detailed depiction of the post-retrofit event from June 4, 2014 is provided in Figure 29 with
corresponding real-time photographs that highlight the 3 hours of ponding that was induced by
the retrofit device, resulting in a prolonged release of a peak discharge that was over five times
less than the peak inflow (3.88 ft3/s compared to 20.5 ft3/s).
In summary, the post-retrofit events had greater rainfall depths, peak intensities, and shorter
durations than the pre-retrofit events, but were discharged at less than or equal to the peak
discharge of the pre-retrofit events.
Page 46
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Stream Flow &
Hydrogeomorphic Surveys:
•	Spur
•	Upstream
•	Downstream
Precipitation
•	Site Rain Gage
•	NWS Gage (Northern
Kentucky/Cincinnati
-
Inflow 2
inflow 1
("~^J ^ Site Rain Gage
Outflow
A Spur
Downstream
A
Upstream
Map data ©2018 Google
NWS Rain Gage < 1 mile
(Airport)
ISCO Flow Monitoring: *
•	Inflow 1
•	Inflow 2
•	Outflow
Cameras: *
•	Retrofit Device Inflow
•	Retrofit Device Outflow
Figure 24 - TMS Detention Basin Retrofit Device Monitoring Devices
Page 47
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Figure 25 - ISCO Flow Monitoring Gauge Installed at Stormwater Detention Basin Inlet
Page 48
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Figure 26 - TMS Detention Basin Retrofit Device with Staff Gauge (in feet) for Camera
Scale
Figure 27 - Detention Basin Retrofit Device Under High Water Conditions
Page 49
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25
20
15
CO
a
10
i.
Device installed
12/20/2013
October 31, 2013
Precip < 1 inch/hr
Outflow = 6 cfs
8/16/2013
9/15/2013
v
L
April 2, 2014
Precip =1.2 in/hr
Outflow = 5.3 cfs
jL
25
20
o.
15 %
c
5
ai
10
10/15/2013 V/ 11/14/2013 12/14/2013
1/13/2014
2/12/2014
3/14/2014
ijj
^4/13/2014
Outflow
¦Inflow (Pipes 1 & 2)
Inflow (Pipe 1 Only)
Rainfall at Airport (1-hrtimestep)
¦Rainfall at Basin (10-min timestep)
Figure 28 - Pre- and Post-Retrofit Outflow for Similar Precipitation Events
Page 50
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10:45
14:07
Figure 29 - June 4, 2014 Post-retrofit Event with Hydrograph and Associated Photographs Indicating a Clear Increase in
Basin Storage and Restriction of the Outflow due to the Full Submergence of the Restricted Low-Flow Pipe Outlet
HCO UOVISION
OIBX 061'F cm9
HCO UOVISION
Page 51
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Table 6 - Comparison of Pre- and Post-Retrofit Peak Outflow for Measured Precipitation
Events
Pre- or Post-
Total
Peak
Peak Inflow
Peak Outflow
Retrofit
Precipitation
Event (date)
Precipitation
(in)
Precipitation
Intensity
(in/hr)
(ft3/sec)
(ftVsec)
Pre-Retrofit




(October 31,
0.9
0.94
Not Measured
6.0
2013)




Post-Retrofit
2.0
1.18
11.1
5.3
(April 3, 2014)
Pre-Retrofit




(December 5,
0.6
0.94
Not Measured
4.0
2013)




Post-Retrofit
1.3
2.6
20.5
4.0
(June 4, 2014)
Acronyms: hr, hour; ft, feet; in, inch(es); sec, second
4.2 Performance Monitoring of BCSD Detention Basin Retrofit Device
There were no flow monitoring devices installed at this location and so the performance of this
device was approximated using photographs from onsite cameras. Cameras were placed at the
inlet and at the outlet of the device and the water levels were estimated from photographs taken
at an interval of 10 minutes.
Figure 30 shows a rainfall event on May 11, 2015 that occurred before the retrofit device was
installed. Figure 31 shows the time series photographs of the fall of water level following this
event as well as the time required for the water level to fall as a percentage of the maximum
height of the water level. The photographs demonstrate that approximately 60 minutes was
required for the detention basin to drain.
Figure 32 shows a rainfall event on July 29, 2015 that occurred after the retrofit device with
media in perforated pipes was installed. Figure 33 shows the time series photographs of the fall
of water level following this event as well as the time required for the water level to fall as a
percentage of the maximum height of the water level. The photographs demonstrate that
approximately 120 minutes was required for the detention basin to drain thus doubling the time
from the pre-install drainage time again demonstrating significant detention within the basin.
Page 52
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HCO UOVISION	05.11.2015 14:39:12 323 024°C 075°F C3D7
Rain Event - 5/11/2015
Hour
Figure 30 - Pre-install Rainfall Event on May 11, 2015 and Maximum Height of Water
Level
Page 53
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	109—j







w


"33
>
01
w


5
•s
c
01


0)
Q.










-40 -20

20 40 60 80 100 120
Time Elapsed (minutes)
Figure 31 - Time Series Showing Estimated General Fall of Water Level Following May
11, 2015 Rain Event
Page 54
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Rain Event - 07/29/2015
Hour
Figure 32 - Post-Retrofit Install Rainfall Event on July 29, 2015 and Maximum Height of
Water Level
Page 55
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Highest Water Level
023"C 073"F <1109
50 minutes
)14 023°C 073°F «D9
Figure 33 - Time Series Showing Estimated General Fall of Water Level Following July 29,
2015 Rain Event
120 minutes
:14 034°C 093 F 4BD9
Page 56
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4.3 Measure Plugging of Media in the Field Using Falling Head Tests
A concern for detention devices equipped with media is the potential rate at which the media can
blind and slow down the water flow sufficiently to cause excessive detention volumes and
overflow conditions. This data is also useful to determine the meantime between maintenance
events which, in turn, would determine operating costs. The media chambers from the unit at the
BCSD detention basin shown in Figure 34 was removed after nearly two years of operation and
brought back to the T&E Facility as shown in Figure 35. The media chamber was then placed in
to a 5,000-gallon tank though a device fabricated to fit over the manhole as shown in Figure 36.
The valve was then opened and the time for the fall of the height of water was measured for
comparing with the baseline. Figure 37 shows the graph of the height of water versus time for
one falling head test. The calculated permeability from this test was 56.9 ft/min versus a
permeability of 11.55 ft/min calculated at the T&E Facility. The higher permeability in this test
is reflective of the perforated pipe used as the media chamber (i.e., the water has a shorter flow
path through the media). This falling head test demonstrates that even after two years in the
field, there is no noticeable plugging in the system.
Figure 34 - Media Chamber at BCSD Installation After Two Years of Operation
Page 57
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Figure 35 - Media Chamber Retrieved from BSCD Installation After Two Years
7///"/"
ft"'!!'
//m"
in"!
ft ill*
Figure 36 - Manhole Adapter to Insert Media Chamber in 5000 Gallon Tank
Page 58
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Height of Water (inches) vs. Time (mins)
Time (minutes)
Figure 37 - Height of Water versus Time for Falling Head Test
Page 59
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5.0 Data Quality Assurance/Quality Control
5.1 Quality Metrics (QA/QC)
Instalments/equipment were maintained in accordance with the EPA ORD Policies and
Procedures Manual, Section 13 A Minimum Quality Assurance (QA)/Quality Control (QC)
Practices for ORD Laboratories Conducting Research. The quality metrics for this study are
summarized below and shown in Table 8.
5.2 QA/QC Acceptance Criteria
5.2.1 Accuracy
Percent Recovery was calculated using the following equation:
For controls:
/M\
o/o R= — * 100
-Q
For matrix spike:
o/or =	* 100
Where,
R = percent recovery
M = Measured analyte concentration
K = Known analyte/spike concentration
Xs = Measured concentration of analyte in spiked sample
Xu = Measured concentration of analyte in un-spiked sample
5.2.2 Precision
Duplicates- Relative Percent Difference (RPD):
The RPD between duplicate samples was calculated as follows:
\d1-d2\
RPD = ,* f-wo * 100
(Ifli + Dzl)/2
Where,
RPD = relative percent difference
D1 = first sample value
D2 = second sample value (replicate)
Page 60
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Replicates- Relative Standard Deviation (RSD):
The RSD between replicates was calculated as follows:
RSD = ^ * 100
Where,
S = standard deviation
y = Mean of the replicates
5.3 Data Analysis, Interpretation, and Management
5.3.1 Data Reporting
Sample analytical data were obtained from instruments, notebooks, and log sheets as appropriate.
Data that were not generated electronically will be entered into Microsoft Excel spreadsheet for
subsequent evaluation. All data were compiled into a comprehensive Excel spreadsheet for
submission.
All results were reduced to the appropriate reporting units by the analyst performing the test. The
reporting units for each analysis are summarized in Table 7. Results for replicates were reported
as means.
Table 7 - Reporting Units by Analyte
Annlyle
1 nil
DRO
mg/L
GRO
mg/L
O&G
mg/L
TN
mg/L
nh3
mg/L
N03-
mg/L
N02"
mg/L
TP
mg/L
DRP
mg/L
Cs, Ag, Cu, Mn
mg/L
E. coli
CFU/100 mL
5.3.2 Data Validation
Calculations were carried out on a computer and were checked initially by the analyst for gross
error and miscalculation. The calculations and data entered into computer spreadsheets were
checked by a second analyst for accuracy. QC parameters from instrumental methods satisfied the
stated criteria (see Tables 9, 10, and 11) or analyses were repeated. Instrumental and experimental
Page 61
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replication and blanks assessed whether the methodologies used were valid. When the
aforementioned repeated analyses were not possible, data were qualified. Additional data review
was performed by WA leader prior to report preparation.
Comprehensive details of sample collection, sample analysis, QA/QC requirement and data
review/validation can be found in EPA approved QAPPs entitled "Evaluation of Media for
Treatment of Contaminated Water" and "Detention Pond Retrofit Technology".
Page 62
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Table 8 - Quality Metrics and Criteria by Analyte
Parameter/Method
QC Checks
Frequency
Acceptance Criteria
TN
Ongoing precision and
recovery (OPR)
One per batch
80-120%
Hach Method 10208
Matrix Spike/Matrix
Spike Duplicate
One per batch
70-130%
<20% RPD
TP
Ongoing precision and
recovery (OPR)
Prior to sample
analysis
80-120%
Hach Method 10210
Matrix Spike/Matrix
Spike Duplicate
One per batch
70-130%
<20% RPD
nh3
Ongoing precision and
recovery (OPR)
One per batch
80-120%
Hach Method 10205
Matrix Spike/Matrix
Spike Duplicate
One per batch
70-130%
<20% RPD

Initial calibration
Once per sequence,
after initial
calibration check or
continuing
calibration check
failure, or whenever
fresh eluent is
prepared
Initial calibration needs to be
verified with an initial calibration
check and the QCS

Initial calibration check
Analyzed
immediately after
the calibration curve
±25 % of true value (QL to lOx
QL)
±15% of true value (>10x QL)
(N03- + N02)
Quality control sample
(QCS)
After initial
calibration
±15 % of true value
EPA Method 300.1
Instrument Performance
Check (IPC)
One per batch
0.8-1.15

Continuing and end
calibration check
After every 10
samples
±25 % of true value (QL to lOx
QL)
±15 % of true value (Greater
than lOx QL)

Laboratory reagent
blank (LRB)
After every 10
samples and at the
end
-------
Table 8 - Quality Metrics and Criteria by Analyte (Continued)
Parameter/Method
QC Checks
Frequency
Acceptance Criteria
Metals
(Cs, Ag, Cu, Mn)
EPA Method 60IOC
Initial calibration
Prior to each batch
of analysis or after
ICV failure
Second order curve r2 > 0.998
Initial calibration
verification (ICV)
After initial
calibration
±10 % of the analytes true value
Low-level initial
calibration verification
(LLICV)
After initial
calibration
±30 % of the analytes true value
Calibration Blanks (ICB
&CCB)
Following ICV
(ICB) and following
each continuing
calibration
verification (CCB)
< low-level calibration standard
(QL)
Continuing calibration
verification (CCV)
CCV after every 10
samples and at the
end of the sample
batch
±10 % of the analytes true value
for CCV
Method Blank (MB)
One per batch of
sample preparation
< low-level standard
concentration (QL), or < 10% of
the lowest sample concentration
for each analyte in a given
preparation batch, whichever is
greater
Laboratory control
sample (LCS)
One per batch of
sample preparation
For liquid, ±20 % of the analytes
true value;
For solid (commercially
prepared), manufacturer's
established acceptance criteria
Matrix Spike (MS)/
Matrix Spike Duplicate
(MSD)
One per sample
matrix
±25 % of the analytes true value
for MS and 20% RPD for MSD
Laboratory duplicate
One per batch
<20% RPD for sample values
Page 64
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Table 9 - QA/QC Summary for Ammonia, Total Nitrogen and Total Phosphorus Analysis
Media Tested
Standard Check
Matrix Spike Recovery
Measured
Recovery
Recovery 1
Recovery 2
RPD
Ammonia
E33
10.3
103
105
105
0
Osorb
10.6
106
115
113
2
Switch Grass
10.1
101
106
106
0
Granular Activated Carbon
10.2
102
101
101
0
Clinoptiolite
9.89
99
97
96
1
E33 and Cleanlt
9.94
99
96
96
0
Total Nitrogen
E33 and Osorb
11.5
115
130
122
6
Switch Grass
11.4
114
121
121
0
Granular Activated Carbon
9.72
97
133
106
23
Clinoptiolite
10
100
99
94
5
E33 and Cleanlt
9.55
96
99
96
3
Total Phosphorus
E33
2.98
99
104
103
1
Osorb
3
100
89
89
0
Switch Grass
3.02
101
47
46
2
Granular Activated Carbon
3.01
100
59
41
36
Clinoptiolite
3.05
102
71
70
1
E33 and Cleanlt
3.03
101
102
97
5
Page 65
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Table 10 - QA/QC Summary for Anions Analysis
Samples from E33 media
evaluation
Anions in mg/L
Surrogate
% Recovery
Criteria
NO2
NOs
PO4
DCAA
ICB
ND
ND
ND
4.71
94.2
90-115%
Calibration
Standards
0.2 mg/L
0.14
0.18
0.13
4.75
95
90-115%
0.5 mg/L
0.39
0.49
0.44
4.89
97.8
90-115%
2 mg/L
2.16
2.32
1.93
4.51
90.2
90-115%
5 mg/L
4.97
4.8
5.04
4.73
94.6
90-115%
10 mg/L
9.96
9.79
10.15
5.26
105.2
90-115%
20 mg/L
20.01
20.11
19.94
5.6
112
90-115%
QCS
Measured
1.12
1.13
1.14
4.56
91.2
90-115%
Actual
1
1
1.5
% Recovery
112
113
76.00
Criteria
85-115%
85-115 %
85-115%
ICV 0.2 mg/L
Measured
0.22
0.153
0.125
4.64
92.8
90-115%
Actual
0.2
0.2
0.2
% Recovery
110
76.5
62.5
Criteria
75-125 %
75-125 %
75-125 %
ICY 0.5 mg/L
Measured
0.44
0.52
0.46
4.64
92.8
90-115%
Actual
0.5
0.5
0.5
% Recovery
88
104
92
Criteria
75-125 %
75-125 %
75-125 %
LRB
ND
ND
ND
4.97
99.4
90-115%
E33- Conl - Blank 1-Inf
ND
0.21
0.337
4.87
97.4
90-115%
E33- Conl - Blank 1-Eff
ND
0.38
ND
4.55
91
90-115%
E33- Conl - Test 1-Inf
ND
2.17
11.25
4.94
98.8
90-115%
E33- Conl - Test 1-Eff
ND
0.65
ND
4.94
98.8
90-115%
E33- Conl - Blank 2- Inf
ND
0.25
0.34
4.94
98.8
90-115%
E33- Conl - Blank 2- FIT
ND
0.39
ND
4.84
96.8
90-115%
E33- Conl - Test 2-Inf
ND
2.05
11.36
4.85
97
90-115%
E33- Conl - Test 2-Eff
ND
0.58
ND
4.54
90.8
90-115%
E33- Conl - Test 2-Eff (DUP)
ND
0.69
ND
4.67
93.4
90-115%
LFB (Blank + 2 mg/L spike)
2.07
1.99
ND
4.53
90.6
90-115%
LFM
2.06
3.97
12.95
4.77
95.4
90-115%
ECV 10 mg/L
Measured
9.93
9.93
10.39
5.73
114.6
90-115%
Actual
10
10
10
-
% Recovery
99.3
99.3
103.9
-
Criteria
85-115%
85-115 %
85-115%
-
LRB
<0.2
ND
<0.2
4.86
97.2
90-115%
Page 66
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Table 10 - QA/QC Summary for Anions Analysis (continued)
Samples from Switch Grass
media evaluation
Anions in mg/L
Surrogate
% Recovery
Criteria
NO2
NOs
PO4
DCAA
ICB
ND
ND
nd
4.553
91.06
90-115 %
Calibration
Standards
0.2 mg/L
0.229
0.218
0.131
4.62
92.4
90-115 %
0.5 mg/L
0.464
0.487
0.347
4.649
92.98
90-115 %
2 mg/L
1.931
2.022
1.86
4.69
93.8
90-115 %
5 mg/L
4.964
4.964
5.089
4.964
99.28
90-115 %
10 mg/L
10.209
10.036
10.332
5.228
104.56
90-115 %
20 mg/L
19.925
19.99
19.856
5.47
109.4
90-115 %
QCS
Measured
1.106
1.004
1.493
4.526
90.52
90-115 %
Actual
1
1
1.5
% Recovery
110.6
100.4
99.53
Criteria
85-115 %
85-115 %
85-115 %
ICV 0.2
mg/L
Measured
0.238
0.21
0.21
4.57
91.4
90-115 %
Actual
0.2
0.2
0.2
% Recovery
119
105
105
Criteria
75-125 %
75-125 %
75-125 %
ICV 0.5
mg/L
Measured
0.504
0.462
0.426
4.546
90.92
90-115 %
Actual
0.5
0.5
0.5
% Recovery
100.8
92.4
85.2
Criteria
75-125 %
75-125 %
75-125 %
LRB
ND
ND
ND
4.54
90.8
90-115 %
SG- Conl - Blank 1- Inf
ND
0.41
2.412
4.743
94.86
90-115 %
SG- Conl - Blank 1- Eff
ND
3.368
13.736
4.895
97.9
90-115 %
SG- Conl - Test 1- Inf
ND
ND
32.325
5.275
105.5
90-115 %
SG- Conl - Test 1-Eff
ND
0.401
0.343
4.887
97.74
90-115 %
SG- Conl - Blank 2- Inf
ND
0.256
4.868
4.993
99.86
90-115 %
SG- Conl - Blank 2- Eff
ND
3.473
14.353
4.674
93.48
90-115 %
SG- Conl - Test 2- Inf
ND
ND
8.242
4.576
91.52
90-115 %
SG- Conl - Test 2-Eff
ND
0.434
1.458
4.983
99.66
90-115 %
SG- Conl - Test 2-Eff
(DUP)
ND
0.314
1.194
4.639
92.78
90-115 %
LFB (Blank + 2 mg/L
spike)
2.05
2.062
2.036
4.753
95.06
90-115 %
LFM
2.796
2.488
6.633
5.03
100.6
90-115 %
ECV 10
mg/L
Measured
10.548
10.27
10.651
5.285
105.7
90-115 %
Actual
10
10
10
-
% Recovery
105.48
102.7
106.51
-
Criteria
85-115 %
85-115 %
85-115 %
-
LRB
<0.2
ND
<0.2
4.504
90.08
90-115 %
Page 67
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Table 10 - QA/QC Summary for Anions Analysis (continued)
Anions results from Granular
Activated Carbon Media evaluation
Anions in mg/L
Surrogate
%
Recovery
Criteria
NCfc
NO3
PO4
DCAA
ICB
ND
ND
<0.2
4.553
91.06
90-115 %
Calibration
Standards
0.2 mg/L
0.22
0.214
0.179
4.64
92.8
90-115 %
0.5 mg/L
0.497
0.513
0.404
4.729
94.58
90-115 %
2 mg/L
1.92
2.018
1.946
4.828
96.56
90-115 %
5 mg/L
5.032
5.038
5.147
4.533
90.66
90-115 %
10 mg/L
10.081
9.898
10.037
4.759
95.18
90-115 %
20 mg/L
19.966
20.035
19.962
5.251
105.02
90-115 %
QCS
Measured
0.901
0.961
1.584
4.519
90.38
90-115%
Actual
1
1
1.5
% Recovery
90.1
96.1
105.6
Criteria
85-115 %
85-115 %
85-115 %
ICV 0.2 mg/L
Measured
0.238
0.172
0.161
4.569
91.38
90-115%
Actual
0.2
0.2
0.2
% Recovery
119
86
80.5
Criteria
75-125 %
75-125 %
75-125 %
ICV 0.5 mg/L
Measured
0.472
0.491
0.508
4.547
90.94
90-115%
Actual
0.5
0.5
0.5
% Recovery
94.4
98.2
101.6
Criteria
75-125 %
75-125 %
75-125 %
LRB
ND
ND
<0.2
4.853
97.06
90-115 %
AC- Conl - Blank 1- Inf
ND
0.176
5.881
5.103
102.06
90-115 %
AC- Conl - Blank 1- Eff
ND
ND
2.6
4.929
98.58
90-115 %
AC- Conl - Test 1- Inf
ND
2.398
18.343
4.61
92.2
90-115 %
AC- Conl - Test 1-Eff
ND
ND
2.756
4.925
98.5
90-115 %
AC- Conl - Blank 2-Inf
ND
ND
1.178
5.638
112.76
90-115 %
AC- Conl - Blank 2- Eff
ND
ND
0.629
5.552
111.04
90-115 %
AC- Conl - Test 2-Inf
ND
2.377
14.526
4.542
90.84
90-115 %
AC- Conl - Test 2-Eff
ND
ND
2.233
5.188
103.76
90-115 %
AC- Conl - Test 1- Inf (dup)
ND
2.317
18.722
5.039
100.78
90-115 %
LFB (Blank + 2 mg/L spike)
2.234
1.983
2.095
5.239
104.78
90-115 %
LFM
3.673
2.194
12.724
5.695
113.9
90-115 %
ECV 10 mg/L
Measured
10.688
9.992
10.361
5.315
106.3
90-115%
Actual
10
10
10
_
% Recovery
106.88
99.92
103.61
_
Criteria
85-115 %
85-115 %
85-115 %
_
LRB
<0.2
ND
<0.2
4.53
90.6
90-115 %
Page 68
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Table 10 - QA/QC Summary for Anions Analysis (continued)
Vial#
QA/QC summary for Anions
analysis E33 and Cleanlt media
samples

NO2
NOs
PO4
#3-8
Calibration Range

0.2 - 20.0
0.2-20.0
0.2 - 20.0
#3-8
Calibration Correlation

0.9974
0.9987
1
9
Variable cone QCS 1:20
# Recovery
1.0805
0.9925
1.4253

Quality Control Standard / 2nd
Source Standard Sec 9.2.2
Prep. Cone.
5.00
5.00
5.00

% Recovery
22%
20%
29%

Acceptable Range
85 - 115%
85 - 115%
85 - 115%
10
0.2 mg/L anions ICS
# Recovery
0.1897
0.2015
0.1815

Calibration Verification Sec 10.5
and Instrument Performance Check
Solution Sec 9.3.3
Prep. Cone.
0.20
0.20
0.20

% Recovery
95%
101%
91%

Acceptable Range
75 - 125%
75 - 125%
75 - 125%


PGF is 0.809
11
LRB
# Recovery
n.a.
n.a.
n.a.

LRB Sec 9.3.1
Acceptable Range
<0.044
<0.040
<0.036
12
LFB 2 mg/L
Validate
2.0314
1.9541
2.0457

Lab Fortified Blank Sec 9.3.2
Fort. Cone.
2.00
2.00
2.00

% Recovery
102%
98%
102%

Acceptable Range
85 - 115%
85 - 115%
85 - 115%
19
E33-Cl-Ts2-Eff
Replicate 1
4.5826
1.22
n.a.
20
E3 3 -C1 -T s2-Eff LD
Replicate 2
4.5829
1.1964
n.a.

Sample Replicates / QAPP
requirement
RSD%
0%
2%
NA

Acceptable Range
<10%
<10%
<10%
19
E33-Cl-Ts2-Eff
Replicate 1
4.5826
1.22
n.a.
21
E3 3 -C1 -T s2-Eff LFM
Fortified Sample
6.4802
3.093
1.7031

Lab Fortified Matrix Sec 9.4.1
# Recovery
1.898
1.873
1.703

Fort. Cone.
2.00
2.00
2.00

% Recovery
95%
94%
85%


Acceptable Range
75 - 125%
75 - 125%
75 - 125%
23
LRB
Blank
n.a.
n.a.
n.a.

LRB Sec 9.3.1
Acceptable Range
<0.044
<0.040
<0.036
24
20.0 mg/L anions CCV
# Recovery
20.1644
19.8907
19.6492

Calibration Verification Sec 10.5
Prep. Cone.
20.00
20.00
20.00

% Recovery
101%
99%
98%

Acceptable Range
85 - 115%
85 - 115%
85 - 115%
30
ClCU-Cl-Ts2-Eff
Replicate 1
n.a.
0.1108
4.3896
31
C1CU-C1 -Ts2 -Eff LD
Replicate 2
n.a.
0.0792
4.4149

Sample Replicates / QAPP
requirement
RSD%
NA
33%
1%

Acceptable Range
<10%
<10%
<10%
30
ClCU-Cl-Ts2-Eff
Replicate 1
n.a.
0.1108
4.3896
32
C1CU-C1 -Ts2 -Eff LFM
Fortified Sample
1.9483
1.7332
6.2602

Lab Fortified Matrix Sec 9.4.1
# Recovery
1.948
1.622
1.871

Fort. Cone.
2.00
2.00
2.00

% Recovery
97%
81%
94%


Acceptable Range
75 - 125%
75 - 125%
75 - 125%
Page 69
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Table 10 - QA/QC Summary for Anions Analysis (continued)
35
LRB
Blank
n.a.
n.a.
n.a.

LRB Sec 9.3.1
Acceptable Range
<0.044
<0.040
<0.036
36
LFB 2mg/L
Validate
2.028
1.978
1.7766

Lab Fortified Blank Sec 9.3.2
Fort. Cone.
2.00
2.00
2.00

% Recovery
101%
99%
89%

Acceptable Range
85 - 115%
85 - 115%
85 - 115%
37
10.0 mg/L anions CCV
# Recovery
10.3685
9.8536
9.8739

Calibration Verification Sec 10.5
Prep. Cone.
10.00
10.00
10.00

% Recovery
104%
99%
99%

Acceptable Range
85 - 115%
85 - 115%
85 - 115%
42
C1LC-Cl-Ts2-Eff
Replicate 1
n.a.
n.a.
n.a.
43
C1LC-Cl-Ts2 -Eff LD
Replicate 2
n.a.
n.a.
n.a.

Sample Replicates / QAPP
requirement
RSD%
NA
NA
NA

Acceptable Range
<10%
<10%
<10%
42
C1LC-Cl-Ts2-Eff
Replicate 1
n.a.
n.a.
n.a.
44
C1LC-Cl-Ts2 -Eff LFM
Fortified Sample
1.9776
1.7478
0.6711

Lab Fortified Matrix Sec 9.4.1
# Recovery
1.978
1.748
0.671

Fort. Cone.
2.00
2.00
2.00

% Recovery
99%
87%
34%


Acceptable Range
75 - 125%
75 - 125%
75 - 125%
45
E33-Cl-Bll-Eff 1:10
Replicate 1
8.4796
2.1134
n.a.
46
E33-Cl-Bll-Eff 1:10 LFM
Fortified Sample
10.3019
3.8775
1.455

Lab Fortified Matrix Sec 9.4.1
# Recovery
1.822
1.764
1.455

Fort. Cone.
2.00
2.00
2.00

% Recovery
91%
88%
73%


Acceptable Range
75 - 125%
75 - 125%
75 - 125%
48
LRB
Blank
n.a.
n.a.
n.a.

LRB Sec 9.3.1
Acceptable Range
<0.044
<0.040
<0.036
49
5.0 mg/L anions CCV
# Recovery
5.1123
4.894
4.7043

Calibration Verification Sec 10.5
Prep. Cone.
5.00
5.00
5.00

% Recovery
102%
98%
94%

Acceptable Range
85 - 115%
85 - 115%
85 - 115%
47
E33-C1-B12-Eff 1:10
Replicate 1
7.9212
1.8571
n.a.
50
E33-C1-B12-Eff 1:10 LFM
Fortified Sample
9.8027
3.8426
1.7406

Lab Fortified Matrix Sec 9.4.1
# Recovery
1.882
1.986
1.741

Fort. Cone.
2.00
2.00
2.00

% Recovery
94%
99%
87%


Acceptable Range
75 - 125%
75 - 125%
75 - 125%
51
LRB
Blank
n.a.
n.a.
n.a.

LRB Sec 9.3.1
Acceptable Range
<0.044
<0.040
<0.036
52
2.0 mg/L anions CCV
# Recovery
2.0262
1.914
1.6609

Calibration Verification Sec 10.5
Prep. Cone.
2.00
2.00
2.00

% Recovery
101%
96%
83%

Acceptable Range
85 - 115%
85 - 115%
85 - 115%
Page 70
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Table 11 - QA/QC Summary for Cesium Analysis
Sample ID
Sample
Type
Mean Cone
(Hg/L)
Expected
Result
Recovery/
Result
Acceptance
Criteria
Cal Zero
Zero
0.0000
0.00


Standard 1
Cal
20
20.00
Abs=
,00001C2X
.00256C
r=0.9999
r2>0.998
Standard 2
Cal
40
40.00

Standard 3
Cal
60
60.00

LRB
LRB
-0.2400
0.00
-0.24
<20ppb (QL)
40ppb ICV
ICV
46.1700
40.00
115%
±10%
40ppb QCS
QCS
48.6000
40.00
122%
±20%
40ppb LFB
LFB
42.9200
40.00
107%
±25%
AC -Con 1 -Blank 1 -Inf
Sample
7.8500



AC -Con 1 -Blank 1 -Eff
Sample
2.3400



AC-Conl-Testl-Inf
Sample
50.9200



AC-Conl-Testl-Eff
Sample
8.0900



AC-Con 1 -Blank2-Inf
Sample
0.7600
0.00
0.76
<20ppb (QL)
AC-Con 1 -Blank2-Eff
Sample
0.7600
40.00
2%
±10%
AC-Conl-Test2-Inf
Sample
52.7900



AC-Conl-Test2-Eff
Sample
11.8400



AC-Conl-Test2-EffLD
LD
11.2800
%RPD=
4.84%
<20%RPD
AC-Con 1 -Test2-Eff LFM
LFM
55.1700
40
108%
±25%
LRB
LRB
1.9900
0.00
1.99
<20ppb (QL)
40 ppb CCV
CCV
40.1100
40.00
100%
±10%
SG-Con 1 -Blank 1 -Inf
Sample
2.5800



SG-Con 1 -Blank 1 -Eff
Sample
1.2000



SG-Con 1 -Te st 1 -Inf
Sample
44.8200



SG-Con 1 -Te st 1 -Eff
Sample
2.3400



SG-Con 1 -Blank2-Inf
Sample
1.7600



SG-Con 1 -Blank2-Eff
Sample
1.1100



SG-Con 1 -Te st2-Inf
Sample
1.0500



SG-Con 1 -Te st2-Eff
Sample
1.4900



SG-Con l-Test2-EffLD
LD
1.0300
%RPD=
36.51%
<20%RPD
SG-Con 1 -Test2-Eff LFM
LFM
1.2600
40
-1%
±25%
Cal Zero
Zero
0.0000



Re slope
Cal
40.0000
40
96%
±25%
Page 71
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Table 11 - QA/QC Summary for
Cesium Analysis (continued)
Sample ID
Sample
Type
Mean
Cone
(Hg/L)
Expected
Result
Recovery/
Result
Acceptance
Criteria
Cal Zero
Zero
0.0055
0.00


Standard 1
Cal
0.0458
20.00
Abs=
.00002C2 X
.00182C
r=0.9999
r2>0.998
Standard 2
Cal
0.1041
40.00

Standard 3
Cal
0.1833
60.00

LRB
LRB
1.5200
0.00
1.52
<20ppb (QL)
40ppb ICV
ICV
31.5800
40.00
79%
±10%
40ppb QCS
QCS
48.0500
40.00
120%
±20%
40ppb LFB
LFB
44.0900
40.00
110%
±20%
BRZ -Con 1 -Blank 1 -Inf
Sample
4.9800



BRZ -Con 1 -Blank 1 -Eff
Sample
2.7800



BRZ-Con 1 -Blank2-Inf
Sample
0.5900



BRZ-Con 1 -Blank2-Eff
Sample
-1.0800



BRZ -Con 1 -Test 1 -Inf
Sample
102.0100



BRZ -Con 1 -Test 1 -Eff
Sample
1.5200



BRZ-Con 1 -Test2-Inf
Sample
97.4400



BRZ-Con 1 -Test2-Eff
Sample
2.0200



BRZ-Con 1 -Test2-Eff LD
LD
1.0300
%RPD=
64.92%
<20%RPD
BRZ-Con 1 -Test2-Eff LFM
LFM
26.2500
40
61%
±25%
LRB
LRB
0.8800
0.00
0.88
<20ppb (QL)
40ppb CCV
CCV
44.1500
40.00
110%
±10%
Page 72
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6.0 Summary and Conclusions
Stormwater detention basins are nearly ubiquitous infrastructure, particularly in areas that were
developed since the 1980s. It follows that systematically retrofitting these extensive stormwater
management facilities would be beneficial to both the built and natural environment as well as
provide an additional emergency response tool for mitigation and decontamination of wide area
contamination incidents such as a nuclear accident, terrorist attack, industrial spill, or
transportation accident. This study examined the cost and performance of multiple types of
media to remove a radiological surrogate, nutrients, and bacteria as well as ensure that flows
within a stormwater application do not violate flood protection requirements. The media
evaluated include: gravel coated with an adsorptive media, switchgrass, granular activated
carbon, natural zeolite, iron composite metals, and ferric oxide coated media. A summary of
results are as follows:
•	A natural zeolite, switchgrass, ferric oxide powder, and coated gravel exhibited the best
removal (> 90% removal) of cesium (radioactivity surrogate).
•	Iron composite metal reduced E. coli (used as a bacterial contamination surrogate) levels
by 8 logs followed by ferric oxide powder and natural zeolite (6 logs). Switchgrass
exhibited an unexpectedly high removal capacity (4 logs).
•	All the media exhibited > 72% removal of nitrogen and >56% removal of phosphorous
which are typically related to harmful algal blooms in source waters.
•	The media exhibited a wide range of permeability which reflects how quickly the treated
water can exit the detention basin via the media. Most localities require detention basins
be emptied within 48 hours. The coated gravel, switchgrass, granular ferric oxide,
activated carbon, and natural zeolite adequately allow flow to exit the detention basin
within that time frame. The iron composite metal and sintered metal with copper may
require an additional 24 hours whereas the ferric oxide powder and powdered reagent
mix are not likely to be able to meet these flow requirements.
•	Another practical consideration for the widespread use of media to treat contaminated
stormwater is the cost. The ferric oxide powder was by far, the most expensive media at
$16.33/lb with switchgrass being the least expensive at $.20/lb. The remaining media
were primarily around $3.00/lb with none exceeding $5.00/lb.
•	Full-scale installations of two variations of the detention basin retrofit prototype device
demonstrated that outlet flow rates were maintained below Qcriticai while doubling the
detention time within the basin without causing flooding of the adjacent area.
•	Post-retrofit detention basins safely detained storm events that exhibited more than twice
the total precipitation and rainfall intensity of pre-retrofit storm events.
Page 73
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The selection of which media to use for the mitigation of a wide area incident or traditional
stormwater runoff requires the consideration of multiple factors as described above:
1)	Identify the contaminant causing impairment or requiring treatment.
2)	Select the applicable media.
3)	Identify the detention period required to keep the discharge below Qcriticai. Narrow
your selection of appropriate media.
4)	Select the lowest cost media that meets the above requirements.
Future research will investigate the longevity and the time to breakthrough of the various media
and optimizing the retrofit design to facilitate the replacement of the media. Greater guidance on
the location and type of retrofit is needed to provide a targeted response. For example, for
"transportation", a retrofit of a highway detention pond should be able to completely capture the
complete contents of tanker truck. An industrial watershed serviced by rail cars should have
detention to complete capture of a tanker car, or cars. This could be for any potentially harmful
liquid product. For a wide area contamination, there is a need for quickly deployable systems
that can be installed to totally prevent outflows and facilitate treatment to minimize the spatial
extent of contamination.
Page 74
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