THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
SERA
U.S. Environmental Protection Agency
Bairene
Ttiii Business ti/Innovation
ETV Joint Verification Statement
TECHNOLOGY TYPE: MULTI-PARAMETER WATER QUALITY PROBE
APPLICATION:
MEASURING WATER QUALITY
TECHNOLOGY NAME: 6600 Extended Deployment System
COMPANY: YSI Incorporated
ADDRESS:
WEB SITE:
E-MAIL:
15 Brannum Lane
PHONE: 937-767-7241
Yellow Springs, OH 45387 FAX: 937-767-1058
http://www.ysi.com
environmental@ysi.com
The U.S. Environmental Protection Agency (EPA) supports 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 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, financing, permitting, purchase, and use of environmental technologies. Information and ETV
documents are available at www.epa.gov/etv.
ETV works in partnership with recognized standards and testing organizations, with stakeholder groups
(consisting of buyers, vendor organizations, and permitters), and with 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 pre-
paring peer-reviewed reports. All evaluations are conducted in accordance with rigorous quality assurance (QA)
protocols to ensure that data of known and adequate quality are generated and that the results are defensible.
The Advanced Monitoring Systems (AMS) Center, one of seven technology areas under ETV, is operated by
Battelle in cooperation with EPA's National Exposure Research Laboratory. The AMS Center has recently
evaluated the performance of multi-parameter water quality probes. This verification statement provides a
summary of the test results for the YSI Incorporated 6600 Extended Deployment System (EDS).
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VERIFICATION TEST DESCRIPTION
The 6600 EDS was evaluated by determining calibration check accuracy and by comparing 6600 EDS
measurements with standard reference measurements and measurements from handheld calibrated probes. Two
6600 EDSs were deployed in saltwater, freshwater, and laboratory environments near Charleston, South Carolina,
during a 3 !/2-month verification test. The saltwater site was in a tributary of Charleston Harbor, the freshwater site
was a wetlands on the campus of the National Oceanic and Atmospheric Administration Center for Coastal
Environmental Health and Biomolecular Research (CCEHBR), and the laboratory site was the CCEHBR mesocosm
facility. Water quality parameters were measured both by the 6600 EDSs and by reference methods consisting of
collocated field-portable instrumentation and analyses of collected water samples. During each phase, performance
was assessed in terms of calibration check accuracy, relative bias, precision, linearity, and inter-unit reproducibility.
Test parameters included dissolved oxygen (DO), conductivity, temperature, pH, turbidity, and chlorophyll.
The saltwater test lasted for 28 days, during which time the 6600 EDS monitored the naturally occurring range of the
target parameters, collecting data every 15 minutes, 24 hours a day. For the duration of the test, the 6600 EDS was
deployed at depths between approximately one and 10 feet, varying according to the tide. Samples were collected at
intervals throughout the test. Freshwater testing was conducted at the wetlands on the CCEHBR campus. Because
the salinity and stratification of the wetlands increased during this portion of the deployment, an extended freshwater
period was added to the end of the mesocosm deployment to provide data from a freshwater deployment. For the
mesocosm tests, the mesocosm tanks were filled with saltwater/freshwater and drained daily, simulating a tide.
Water samples were collected during each test day throughout the normal operating hours of the facility (nominally
6 a.m. to 6 p.m.). During this period, the mesocosm was manipulated to introduce variations in the measured
parameters. The turbidity of the system was varied by operating a pump near the sediment trays to suspend
additional solids in the water. Conductivity was varied by adding freshwater to the saltwater during the last three
weeks of testing. Variations in temperature, pH, DO, and chlorophyll were driven by natural forces and the changes
in the other test parameters. The table below provides a summary of the water conditions at the test sites.
Test Site Water Conditions
Saltwater
Parameter
DO
Specific
conductivity
Temperature
pH
Turbidity
Chlorophyll
(total fluorescence)
Low
3 milligrams
(mg)/liter(L)
31mS/
centimeter (cm)
20°C
7.2
8 nephelometric
turbidity units
(NTU)
2 micrograms
(Hg)/L
High
6 mg/L
41 mS/cm
28°C
7.8
37 NTU
5 |ig/L
Freshwater
Low
6.8 mg/L
0.27 mS/cm
11°C
6.9
1.7 NTU
0.0 |ig/L
High
11. 2 mg/L
29.3 mS/cm
27°C
7.5
3. 6 NTU
16 |ig/L
Mesocosm
Low
9.3 mg/L
0.5 mS/cm
9°C
7.1
0.4 NTU
0.2 |ig/L
High
12.1 mg/L
28 mS/cm
16°C
8.5
15 NTU
1.4jig/L
During this verification test approximately 8,000 data points were collected for each of the three parameters tested,
and 127 sets of reference measurements were made.
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QA oversight of verification testing was provided by Battelle and EPA. Battelle QA staff conducted a technical
systems audit, a performance evaluation audit, and a data quality audit of 10% of the test data. This verification
statement, the full report on which it is based, and the test/QA plan for this verification are all available at
www.epa.gov/etv/centers/centerl.html.
TECHNOLOGY DESCRIPTION
The following description of the 6600 EDS was provided by the vendor and does not represent verified information.
The 6600 EDS is a multi-parameter water probe/sonde capable of measuring dissolved oxygen (DO), conductivity,
temperature, pH, turbidity, and chlorophyll. The 6600 EDS is maintained free of fouling by the Clean Sweep™
universal wiper assembly, as well as by individual optical wipers. 6600 EDS sensors are field-replaceable and
integrate with data collection platforms. Flash memory prevents data loss, and C-cell battery power allows long-term
deployment. The tested 6600 EDS was coated with YSFs optional anti-fouling paint. The outer diameter of the 6600
EDS is 8.9 cm (3.5 inches). It is 52 cm (20.4 inches) long and weighs 2.7 kilograms (six pounds). The 6600 EDS
sells for approximately $10,000. The range, resolution, and accuracy of the 6600 EDS, as indicated by the vendor,
are listed below for the parameters tested.
Vendor-Provided Range, Resolution, and Accuracy
Parameter Range Resolution Accuracy
DO% 0 to 500% 0.1% 0 to 200% ±2%; 200 to 500% ±6%
Saturation of reading
DO 0 to 50 mg/L 0.01 mg/L 0 to 20 mg/L ±0.2 mg/L;
20 to 50 mg/L ±0.6 mg/L
Conductivity 0 to 100 millisiemen (mS)/cm 0.001 to 0.1 mS/cm ±0.5% of reading +0.001 mS/cm
Temperature -5 to+45°C 0.01°C ±0.15°C
pH Otol4 0.01 ±0.2
Turbidity 0 to 1,000 NTU 0.1 NTU ±5% of reading or 2 NTU, whichever
is greater
Chlorophyll 0 to 400 |ig/L 0.1 |ig/L chlorophyll NA
0 to 100% fluorescence 0.1% fluorescence
NA = not applicable (measures total fluorescence)
VERIFICATION OF PERFORMANCE
The table below summarizes the performance of the 6600 EDS. The two 6600 EDSs collected data without
interruption at 15-minute intervals from October 1, 2003, until January 5, 2004, and 100% of required data was
collected.
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Performance Results
Statistical
Measure Parameter
DO (%)
Specific conductivity (%)
Calibration check pH (%)
accuracy (a) Turbidity at 120 NTU (%)
Turbidity at 0 NTU (NTU)
Chlorophyll (total in vivo)
DO (%)
Specific conductivity (%)
Average relative Temperature (%)
bias ^ pH (%)
Turbidity (%)
Chlorophyll (%)
DO (%RSD)
Specific conductivity
(%RSD)
Average Temperature (%RSD)
Precision pH (%RSD)
Turbidity (%RSD)
Chlorophyll (%RSD)
Linearity
Inter-unit DO (mg/L)
reproducibility Specific conductivity
(mS/cm)
Temperature (°C)
pH
Turbidity (NTU)
Chlorophyll (total)
YSIAA
Saltwater Freshwater Mesocosm
99.6 87.0 97.0
100 101 96.8
100-101 98.3-101 102-101
100 99 99
0.3 -0.2 0.2
-0.5 0.9 0.8
-7.4 -(c) 0.3
-8.7 -(c) 12.8
-0.1 -(c) -0.2
7.5 -(c) 0.39
-33.6 -(c) -17.4
-98.0 -(c) -72.1
YSIAA
0.44
0.14
0.74
0.62
29.6
19.8
YSIAB
Saltwater Freshwater Mesocosm
101 105 99.1
99.5 102 98.1
101-102 100-101 100-101
98 100 101
0.2 -0.2 0.2
-0.3 -0.1 -0.1
-5.7 -(c) 1.7
-7.6 -(c) 10.2
-0.1 -(c) -0.2
8.1 -(c) 0.35
-184 -(c) -30.1
-133 -(c) -131
YSIAB
0.46
0.53
0.75
0.76
19.4
24.6
Linearity and regression coefficients indicated better agreement between the
6600 EDS readings and reference values for the parameters that do not use
optical measurements, such as DO, conductivity, temperature, and pH.
Average Difference Between YSI AA and AB Readings
Saltwater Freshwater Mesocosm
0.14 0.48 0.19
0.05
0.42 0.38
0.03 0.02 0.02
0.01 0.08 0.03
10.5 0.29 0.27
0.78 1.95 0.48
RSD = relative standard deviation
(a) The closer the percentage is to 100, the better.
^ The closer the percentage is to zero, the better.
^ Stratificaion; no data reported.
Original signed bv Gabor J. Kovacs 7/27/04 Original signed bv Gary J. Folev 9/13/04
Gabor J. Kovacs Date Gary J. Foley Date
Vice President Director
Energy and Environment Division National Exposure Research Laboratory
Battelle Office of Research and Development
U.S. Environmental Protection Agency
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NOTICE: ETV verifications are based on an evaluation of technology performance under specific, predetermined
criteria and the appropriate quality assurance procedures. EPA and Battelle 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 commercial product names does not imply endorsement.
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