THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
U.S. Environmental Protection Agency
NSF International
ETV Joint Verification Statement
TECHNOLOGY TYPE:
APPLICATION:
TECHNOLOGY NAME:
TEST LOCATION:
COMPANY:
ADDRESS:
WEB SITE:
EMAIL:
STORMWATER TREATMENT TECHNOLOGY
SUSPENDED SOLIDS AND ROADWAY POLLUTANT
TREATMENT
THE STORMWATER MANAGEMENT STORMFILTER®
USING ZPG FILTER MEDIA
MILWAUKEE, WISCONSIN
STORMWATER MANAGEMENT, INC.
12021-B NE Airport Way
Portland, Oregon 97220
http://www.stormwaterinc.com
mail@ stormwaterinc.com
PHONE: (800)548-4667
FAX: (503)240-9553
NSF International (NSF), in cooperation with the EPA, operates the Water Quality Protection Center
(WQPC), one of six centers under ETV. The WQPC recently evaluated the performance of the
Stormwater Management StormFilter® (StormFilter) using ZPG filter media manufactured by Stormwater
Management, Inc. (SMI). The system was installed at the "Riverwalk" site in Milwaukee, Wisconsin.
Earth Tech, Inc. and the United States Geologic Survey (USGS) performed the testing.
The U.S. Environmental Protection Agency (EPA) has created the Environmental Technology
Verification (ETV) Program to facilitate the deployment of innovative or improved environmental
technologies through performance verification and dissemination of information. The goal of the ETV
program is to further environmental protection by accelerating the acceptance and use of improved and
more cost-effective technologies. ETV seeks to achieve this goal by providing high quality, peer-
reviewed data on technology performance to those involved in the design, distribution, permitting,
purchase, and use of environmental technologies.
ETV works in partnership with recognized standards and testing organizations; stakeholder groups, which
consist of buyers, vendor organizations, and permitters; and with the full participation of individual
technology developers. The program evaluates the performance of innovative technologies by developing
test plans that are responsive to the needs of stakeholders, conducting field or laboratory tests (as
appropriate), collecting and analyzing data, and preparing peer-reviewed reports. All evaluations are
conducted in accordance with rigorous quality assurance protocols to ensure that data of known and
adequate quality are generated and that the results are defensible.
04/17/WQPC-WWF
The accompanying notice is an integral part of this verification statement.
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TECHNOLOGY DESCRIPTION
The following description of the StormFilter was provided by the vendor and does not represent verified
information.
The StormFilter installed at the Riverwalk site consists of an inlet bay, flow spreader, cartridge bay,
overflow baffle, and outlet bay, housed in a 12 foot by 6 foot pre-cast concrete vault. The inlet bay serves
as a grit chamber and provides for flow transition into the cartridge bay. The flow spreader traps
floatables, oil, and surface scum. This StormFilter was designed to treat stormwater with a maximum
flow rate of 0.29 cubic feet per second (cfs). Flows greater than the maximum flow rate would pass the
overflow baffle to the discharge pipe, bypassing the filter media.
The StormFilter contains filter cartridges filled with ZPG filter media (a mixture of zeolite, perlite, and
granular activated carbon), which are designed to remove sediments, metals, and stormwater pollutants
from wet weather runoff. Water in the cartridge bay infiltrates the filter media into a tube in the center of
the filter cartridge. When the center tube fills, a float valve opens and a check valve on top of the filter
cartridge closes, creating a siphon that draws water through the filter media. The filtered water drains into
a manifold under the filter cartridges and to the outlet bay, where it exits the system through the discharge
pipe. The system resets when the cartridge bay is drained and the siphon is broken.
The vendor claims that the treatment system can remove 50 to 85 percent of the suspended solids in
stormwater, along with removal of total phosphorus, total and dissolved zinc, and total and dissolved
copper in ranges from 20 to 60 percent.
VERIFICATION TESTING DESCRIPTION
Methods and Procedures
The test methods and procedures used during the study are described in the Test Plan for Verification of
Stormwater Management, Inc. StormFilter® Treatment System Using ZPG Media, "Riverwalk Site, "
Milwaukee, Wisconsin (NSF International and Earth Tech, March 2004) (VTP). The StormFilter treats
runoff collected from a 0.19-acre portion of the eastbound highway surface of Interstate 794. Milwaukee
receives an average of nearly 33 inches of precipitation, approximately 31 percent of which occurs during
the summer months.
Verification testing consisted of collecting data during a minimum of 15 qualified events that met the
following criteria:
• The total rainfall depth for the event, measured at the site, was 0.2 inches (5 mm) or greater
(snow fall and snow melt events do not qualify);
• Flow through the treatment device was successfully measured and recorded over the duration of
the runoff period;
• A flow-proportional composite sample was successfully collected for both the influent and
effluent over the duration of the runoff event;
• Each composite sample was comprised of a minimum of five aliquots, including at least two
aliquots on the rising limb of the runoff hydrograph, at least one aliquot near the peak, and at least
two aliquots on the falling limb of the runoff hydrograph; and
• There was a minimum of six hours between qualified sampling events.
Automated sample monitoring and collection devices were installed and programmed to collect composite
samples from the influent, the treated effluent, and the untreated bypass during qualified flow events. In
addition to the flow and analytical data, operation and maintenance (O&M) data were recorded. Samples
were analyzed for the following parameters:
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Sediments
Metals
• total suspended solids (TSS)
• total dissolved solids (TDS)
• suspended sediment
concentration (SSC)
• particle size analysis
VERIFICATION OF PERFORMANCE
total and
dissolved
cadmium, lead,
copper and zinc
Nutrients Water Quality Parameters
• total and • chemical oxygen
dissolved demand (COD)
phosphorus • dissolved chloride
• total calcium and
magnesium
Verification testing of the StormFilter lasted approximately 16 months, and coincided with testing
conducted by USGS and the Wisconsin Department of Natural Resources. A total of 20 storm events
were sampled. Conditions during certain storm events prevented sampling for some parameters. However,
samples were successfully taken and analyzed for all parameters for at least 15 of the 20 total storm
events.
Test Results
The precipitation data for the 20 rain events are summarized in Table 1.
Table 1. Rainfall Data Summary
Event Start
Number Date
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
6/21/02
7/8/02
8/21/02
9/2/02
9/18/02
9/29/02
12/18/02
4/19/03
5/4/03
5/30/03
6/8/03
6/27/03
7/4/03
7/8/03
9/12/03
9/14/03
9/22/03
10/14/03
10/24/03
1 1/4/03
Start
Time
6:54
21:16
20:08
5:24
5:25
0:49
1:18
5:39
21:21
18:55
3:26
17:30
7:25
9:49
15:33
5:22
2:28
1:03
16:46
16:14
Rainfall
Amount
(inches)
0.52
1.5
1.7
1.2
0.37
0.74
0.37
0.55
0.90
0.54
0.62
0.57
0.53
0.33
0.22
0.47
0.27
0.25
0.71
0.60
Rainfall
Duration
(hnmin)
0:23
2:04
15:59
3:24
4:54
7:54
3:47
10:00
11:44
4:06
11:09
13:25
40:43
3:37
1:55
6:35
2:09
2:07
15:07
2:09
Peak
Runoff Discharge
Volume Rate
(ft3)1 (gpm)1
420
1,610
1,620
1,180
350
730
300
340
540
320
450
460
550
260
150
340
270
220
410
560
447
651
671
164
136
70.9
61.0
96.9
73.2
83.9
140
107
143
62.8
21.5
264
104
56.5
75.8
906
04/17/WQPC-WWF
1 Runoff volume and peak discharge volume was measured at the outlet
monitoring point.
The accompanying notice is an integral part of this verification statement.
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July 2004
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The monitoring results were evaluated using event mean concentration (EMC) and sum of loads (SOL)
comparisons. The EMC or efficiency ratio comparison evaluates treatment efficiency on a percentage
basis by dividing the effluent concentration by the influent concentration and multiplying the quotient by
100. The efficiency ratio was calculated for each analytical parameter and each individual storm event.
The SOL comparison evaluates the treatment efficiency on a percentage basis by comparing the sum of
the influent and effluent loads (the product of multiplying the parameter concentration by the precipitation
volume) for all 15 storm events. The calculation is made by subtracting the quotient of the total effluent
load divided by the total influent load from one, and multiplying by 100. SOL results can be summarized
on an overall basis since the loading calculation takes into account both the concentration and volume of
runoff from each event. The analytical data ranges, EMC range, and SOL reduction values are shown in
Table 2.
Table 2. Analytical Data, EMC Range, and SOL Reduction Results
Parameter1
TSS
ssc
TDS
Total phosphorus
Dissolved phosphorus
Total magnesium
Total calcium
Total copper
Total lead
Total zinc
Dissolved copper
Dissolved zinc
COD
Dissolved chloride
Units
mg/L
mg/L
mg/L
mg/L as P
mg/L as P
mg/L
mg/L
Mg/L
Mg/L
Inlet
Range
29
-780
51-5,600
<50
0.05
0.01
4.0
9.4
15
<31
-600
-0.63
-0.20
-174
-430
-440
-280
Hg/L 77-1,400
Mg/L
Mg/L
mg/L
mg/L
<5
26
18
3.2
-58
-360
-320
-470
Outlet EMC Range
Range (percent)
20-
12-
<50-
0.03
0.01
1.1
4.0
7.0-
<31
28-
<5
16-
17-
3.3-
-380
-370
4,2002
-0.30
-0.19
-26
-68
-140
-94
-540
-42
-160
- 190
2,6002
-33
3-
-600
0-
-35
53-
26-
8.3
33-
20-
-47
-86
-91
-740
-95
99
- 10
-70
-38
-96
-93
-96
-91
-89
-64
-56
-47
-24
SOL
Reduction
(percent)
46
92
-1702
38
6
85
79
59
64
64
16
17
16
-2422
1 Total and dissolved cadmium and dissolved lead concentrations were below method detection
limits for every storm event.
2 Dissolved chloride and TDS results were heavily influenced by a December storm event when road
salt was applied to melt snow and ice.
Based on the SOL evaluation method, the TSS reductions nearly met the vendor's performance claim,
while SSC reductions exceeded the vendor's performance claim of 50 to 85 percent solids reduction. The
StormFilter also met or exceeded the performance claim for total and dissolved phosphorus, total copper,
and total zinc. The StormFilter did not meet the performance claim for dissolved copper or dissolved zinc,
both of which were 20 to 40 percent reduction, and had no performance claims for any other parameters.
The TDS and dissolved chloride values were heavily influenced by a single event (December 18, 2002),
where high TDS and dissolved chloride concentrations were detected in the effluent. The event was likely
influenced by application of road salt on the freeway. When this event is omitted from the SOL
calculation, the SOL value is -37 percent for TDS and -31 percent for dissolved chloride.
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Particle size distribution analysis was conducted on samples when adequate sample volume was collected.
The analysis identified that the runoff entering the StormFilter contained a large proportion of coarse
sediment. The effluent contained a larger proportion of fine sediment, which passed through the pores
within the filter cartridges. For example, 20 percent of the sediment in the inlet samples was less than
62.5 (am in size, while 78 percent of the sediment in the outlet samples was less than 62.5 (im in size.
System Operation
The StormFilter was installed prior to verification testing, so verification of installation procedures on the
system was not documented.
The StormFilter was cleaned and equipped with new filter cartridges prior to the start of verification.
During the verification period, two inspections were conducted as recommended by the manufacturer.
Based on visual observations, the inspectors concluded that a major maintenance event, consisting of
cleaning the vault and replacing the filter cartridges, was not required. After the verification was
complete, a major maintenance event was conducted, and approximately 570 pounds (dry weight) of
sediment was removed from the StormFilter's sediment collection chamber.
Quality Assurance/Quality Control
NSF personnel completed a technical systems audit during testing to ensure that the testing was in
compliance with the test plan. NSF also completed a data quality audit of at least 10 percent of the test
data to ensure that the reported data represented the data generated during testing. In addition to QA/QC
audits performed by NSF, EPA personnel conducted an audit of NSF's QA Management Program.
Original signed by Original Signed by
Lawrence W. Reiter, Ph. D. September 21, 2004 Gordon E. Bellen September 23, 2004
Lawrence W. Reiter, Ph. D. Date Gordon E. Bellen Date
Acting Director Vice President
National Risk Management Laboratory Research
Office of Research and Development NSF International
United States Environmental Protection Agency
NOTICE: Verifications are based on an evaluation of technology performance under specific,
predetermined criteria and the appropriate quality assurance procedures. EPA and NSF make no expressed
or implied warranties as to the performance of the technology and do not certify that a technology will
always operate as verified. The end user is solely responsible for complying with any and all applicable
federal, state, and local requirements. Mention of corporate names, trade names, or commercial products
does not constitute endorsement or recommendation for use of specific products. This report is not an NSF
Certification of the specific product mentioned herein.
Availability of Supporting Documents
Copies of the ETV Verification Protocol, Stormwater Source Area Treatment Technologies Draft
4.1, March 2002, the verification statement, and the verification report (NSF Report Number
04/17/WQPC-WWF) are available from:
ETV Water Quality Protection Center Program Manager (hard copy)
NSF International
P.O. Box 130140
Ann Arbor, Michigan 48113-0140
NSF website: http://www.nsf.org/erv (electronic copy)
EPA website: http://www.epa.gov/etv (electronic copy)
Appendices are not included in the verification report, but are available from NSF upon request.
04/17/WQPC-WWF The accompanying notice is an integral part of this verification statement. July 2004
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