I-17_FieldMeterCalibrationAndMaintenanceSOP_Draft_20190325

CITY OF
DURHAM
City of Durham, North Carolina
Department of Public Works
Stormwater and GIS Services
Water Quality Unit
Title: Standard Operating Procedures for Water Quality Field Meter
Calibration and Maintenance
Version: 1.0
Date: [Enter date finalized and signed]
Approvals
Author: Date:
Christine Cailleret, Senior Water Quality Technician
Approved by: Date:
Susan Gale, Water Quality Specialist, Monitoring & Assessment
Approved by:
Approved by:
Date:
Michelle Woolfolk, Water Quality Manager
Date:
Paul Wiebke, Assistant Director for Stormwater & GIS Services
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT Page 1 of 29
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Revision Record
Revision
Date
I Updated by
I Description of change
1.0
1 03/25/2019
1 Christine Cailleret
I Initial draft
Distribution
Current copies of this approved SOP should be provided to the following positions with the City of
Durham Stormwater and GIS Services:
• Water Quality Manager
• Assistant Water Quality Manager
• Water Quality Specialist, Monitoring and Assessment
• Senior Water Quality Technicians, Monitoring and Assessment
• Water Quality Technicians, Monitoring and Assessment
• Temporary Water Quality Technicians or other staff assigned to this task
The current SOP should also be provided to any contractors performing these procedures on behalf of
the City of Durham Stormwater & GIS Services.
Abbreviations
µS/cm
Microsiemens per centimeter (Measure of conductance)
COD
City of Durham
DI
Deionized
DO
Dissolved Oxygen
IDDE
Illicit Discharge Detection and Elimination
mg/L
Milligrams per liter
NTU
Nephelometric Turbidity Unit
ODO
Optical Dissolved Oxygen
SC
Specific Conductance
SDS
Safety Data Sheet
SW Lab
Stormwater Laboratory
WQ M&A Specialist
Water Quality Monitoring and Assessment Specialist
WQU
Water Quality Unit
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Table of Contents
Title: Standard Operating Procedures for Water Quality Field Meter Calibration and Maintenance .......... 1
Approvals..................................................................................................................................................1
RevisionRecord........................................................................................................................................
2
Distribution...............................................................................................................................................
2
Abbreviations...........................................................................................................................................2
Tableof Contents..........................................................................................................................................3
Procedures....................................................................................................................................................4
Purposeand scope...................................................................................................................................4
Methodsummary.....................................................................................................................................4
Healthand safety warnings......................................................................................................................4
Cautions and interferences......................................................................................................................5
Personnel qualifications and responsibilities...........................................................................................5
Equipmentand supplies...........................................................................................................................5
Equipment Specific for the YSI Pro Plus...............................................................................................
6
Equipment Specific for the YSI ProDSS.................................................................................................
6
HACH 2100QTurbidimeter (for measuring turbidity)..........................................................................6
GeneralLab Supplies............................................................................................................................6
Methods...................................................................................................................................................7
YSI Pro Plus Calibration, Post -Check, and Storage Methods................................................................7
YSI ProDSS Calibration and Post -Check Methods...............................................................................14
HACH 2100QTurbidimeter Calibration..............................................................................................21
Troubleshooting Calibration and Post -Check Issues..........................................................................23
EquipmentMaintenance....................................................................................................................23
Data and records management..............................................................................................................24
Quality assurance and quality control(QA/QC)..........................................................................................24
References..................................................................................................................................................24
Appendix 1. YSI Pro Plus Meter Calibration/Post-Check Sheet Example....................................................25
Appendix 2. Dissolved Oxygen Concentration Table Related to Barometric Pressure and Temperature .26
Appendix 3. pH Temperature Reference Table..........................................................................................27
Appendix 4. YSI ProDSS Meter Calibration/Post-Check Sheet Example.....................................................28
Appendix 5. HACH Turbidimeter Maintenance and Calibration Sheet.......................................................29
Table of Figures
Figure 1 Diagram of the YSI Pro Plus.............................................................................................................7
Figure 2 Sensors Installed on the YSI Pro Plus..............................................................................................8
Figure 3 Diagram of the YSI Pro DSS...........................................................................................................14
Figure 4 Sensors installed on the YSI Pro DSS.............................................................................................15
Figure 5 Diagram of the HACH 2100Q Turbidimeter.................................................................................. 21
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Procedures
Purpose and scope
The purpose of this Standard Operating Procedure (SOP) is to provide specific procedures for calibrating,
post -checking, and maintaining field meters used by the Water Quality Unit (WQU) to collect field water
quality measurements. Field measurements are collected for many WQU projects and programs, such as
ambient water quality monitoring, special studies, and IDDE work. The main meters used by the WQU
are manufactured by YSI (a Xylem brand) and HACH. The standard water quality field measurements
include:
• Temperature
• Dissolved oxygen saturation and concentration
• pH
• Specific conductance
• Depth
• Turbidity
This SOP ensures high — quality data are collected in a consistent manner by WQU staff for all projects.
Method summary
All field meters used by the WQU must be calibrated prior to sampling and checked post monitoring
using the designated Calibration/Post-Check form (Appendix 1 and 4). The specific methods for
calibration and post -checking vary depending on the specific meter used. Additionally, all meters are
maintained on a monthly and quarterly basis. Troubleshooting of meters takes place in a timely matter
for any meter showing issues with reliability and/or accuracy of data.
This SOP outlines the proper calibration and post -check methods for the following meters:
• YSI Professional Plus (Pro Plus)
• YSI Professional Digital Sampling System (ProDSS)
• HACH 2100QTurbidimeter
Health and safety warnings
General safety considerations
All employees should receive a copy of the Department of Public Work's Safety Operating Procedures
(City of Durham 2017) and current Safety Policies (City of Durham Employee Policies S-201— S-208)
upon hire. Any injuries or incidents should be documented and recorded in accordance with City and
Department policies. The first priority should be to provide appropriate care (First Aid or emergency
treatment) to the injured employee; the second priority is to notify the appropriate supervisor.
While the remainder of this section summarizes some of the more common hazards encountered, all
employees are expected to review and comply with all City procedures and policies.
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Chemical safety
City staff must follow any applicable City guidance and/or policies for activities such as chemical storage
and handling and the storage of preserved specimens. Chemical handling, storage, and disposal should
comply with requirements in associated Safety Data Sheets (SDS). When sampling unknown substances
in the field, staff should assume they are hazardous and wear appropriate PPE, such as disposable nitrile
gloves. Stormwater Laboratory (SW Lab) is located in the Annex Building in City Hall and is equipped
with safety equipment such as eyewash stations and fully stocked first aid kits in case of emergency.
Cautions and interferences
All meters used by WQU staff must be properly calibrated using fresh reference standards before
sampling occurs. Errors in the calibration process can result in loss or unreliability of data collected.
Therefore, the calibration methods documented in this SOP must be followed.
All meters must also be post -checked after field measurements are complete. Post -checks are
performed to ensure the data collected has an insignificant standard of error when compared to the
actual value.
The pH, dissolved oxygen, and conductivity sensors all use temperature compensation. Therefore, it is
important to allow meters appropriate time to cool down or warm up before beginning calibrations or
post -checks as extreme heat and cold can cause inaccurate readings from the sensors.
When operating the HACH turbidimeter a lens wipe should be used to wipe the standard cell clean of
any residual water or fingerprints as they can cause invalid readings. Also when inverting the sample cell
before inserting it into the cell compartment of the turbidimeter, staff should be careful not to shake
the cell as air bubbles can cause invalid readings as well.
All meters must be properly stored when not in use, as improper storage can result in damage to the
entire unit and/or the individual sensors on the meter. Staff are to follow the manufacturer's guidelines
for short-term and long-term storage of meters.
Finally, all meters should be properly maintained as a lack of maintenance and repair of faulty meters
can result in loss or inaccuracy of data collected. Staff will perform monthly and quarterly maintenance
on all meters following the maintenance recommendations of the manufacturer. All maintenance
performed on WQU meters should be documented in designated maintenance logs.
Personnel qualifications and responsibilities
Meter calibrations and post -checks should be performed by experienced staff members who are fully
trained on COD procedures outlined in this SOP. New staff members will perform calibrations and post -
checks only under the supervision of trained full — time staff until they are determined to be competent
in the procedures. Meter use is limited to WQU staff and others assigned to field data collections.
Equipment and supplies
Equipment needed for meter calibrations, post -checks, maintenance, and troubleshooting includes:
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Equipment Specific for the YSI Pro Plus
• YSI Pro Plus with sensors for temperature, dissolved oxygen, specific conductance, and pH
• YSI Pro Plus Calibration Cup
• YSI Pro Plus Sensor Guard and Rubber Sleeve
• YSI Replacement DO Cap Membrane Kit for Polarographic sensors (Yellow)
• YSI Pro Series Replacement pH Sensor
• C Batteries
Equipment Specific for the YSI ProDSS
• YSI ProDSS with sensors for temperature, dissolved oxygen, specific conductance, and pH
• YSI ProDSS Calibration Cup and Guard
• Replacement ProDSS pH Module
• Replacement ProDSS ODO Sensor Cap
• Rechargeable Lithium -ion battery back
HACH 2100Q Turbidimeter (for measuring turbidity)
• HACH Turbidimeter Sample Cells
• StablCal°Stablized Turbidity Standards (values are project dependent)
• AA Batteries
General Lab Supplies
• Conductivity Calibration Standards (exact values are project dependent)
• pH Calibration Standards (exact values are project dependent)
• Phillips head screwdriver
• DI Water
• Kimwipes (lens wipes)
• Q-Tips
• Barometer
• Calibration/Post-Check Sheets (specific for each meter)
• pH Slope Test Forms
• pH Reference Tables
• Dissolved Oxygen Reference Table
• Maintenance Logs
• Meter User Manuals
• Stand and Adjustable Clamp
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Methods
YSI Pro Plus Calibration, Post -Check, and Storage Methods
Display Screen
Handheld with Keypad
CQuatro Cable
YSI Pro Plus
Sensors
4
Sensor Bulkhead
P
35
irso
Figure 1 Diagram of the YSI Pro Plus
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Temperature probe
DO Senso
r
pH Sensor
Temperature probe
Figure 2 Sensors Installed on the YSI Pro Plus
Conductivity Sensor
Dissolved Oxygen Calibration Method
The Dissolved Oxygen sensor must be calibrated before the meter is used in the field. DO is calibrated by
performing a 1 point calibration in water -saturated air, as recommended by YSI. To perform a 1 point
calibration in water -saturated air, the sensor needs to be placed in a 100% humid environment.
1. Leaving the calibration cup attached to the sensor bulkhead, remove the cap from the
calibration cup. Check the DO sensor and ensure it is in proper working condition with no
obvious damage.
2. Using a lens wipe, carefully dab the DO sensor as it must be completely dry for calibration.
3. Carefully fill the calibration cup with room temperature tap water to just below the yellow
membrane of the DO sensor. Dab the DO sensor with a lens wipe again to ensure no water got
on the sensor during this process.
4. Place the sensor bulkhead in the clamp attached to the meter stand with the sensors facing up
and set the cap for the calibration cup upside down on top of calibration cup to allow for some
air exchange between inside and outside the calibration cup.
5. Wait 5 to 15 minutes to allow the air in the calibration cup to become completely water -
saturated and for the DO sensor to stabilize.
6. While the DO sensor is stabilizing, begin to fill out the YSI Pro Plus Meter Calibration/Post-Check
Sheet (Appendix 1. YSI Pro Plus Meter Calibration/Post-Check Sheet Example). This sheet must
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be filled out every time a YSI Pro Plus meter is calibrated for field sampling. Once the DO sensor
has stabilized, read the Barometric Pressure (InHg), Temperature (°C), DO saturation (%), and
DO concentration (mg/L) from the display and record in the Initial row on the calibration sheet.
7. After recording the initial readings, hit the Cal key, use the arrow keys to highlight DO, and press
Enter.
8. Highlight DO% and press Enter.
NOTE: Dissolved oxygen should always be calibrated using % DO saturation.
9. Observe that the measurement readings are stable, then highlight Accept Calibration and press
Enter to calibrate Dissolved Oxygen.
"Calibrating channel..." and then "Saving configuration..." will be displayed at the bottom of the
calibration screen before returning to the main screen.
10. In the Adjusted row on the calibration sheet, record the displayed values for DO (%) and DO
(mg/L).
11. Using the recorded barometric pressure and temperature values, find the Chart DO value on the
Dissolved Oxygen Table (Appendix 2. Dissolved Oxygen Concentration Table Related to
Barometric Pressure and Temperature) and record it on the calibration sheet.
NOTE: When finding the DO value from the Dissolved Oxygen Table round to the nearest
0.5°C for temperature and the nearest 0.10 inHg for pressure.
12. Confirm that the Chart DO value and Adjusted DO (mg/L) value are within ±0.5 mg/L of each
other. Circle Yes (Y) or No (N) accordingly. If the values are not within ±0.5 mg/L of each other,
attempt to re -calibrate the sensor. If the values continue to be outside of the acceptable range
flag the meter and bring it to the attention of the Water Quality Monitoring and Assessment
Specialist (WQ M&A Specialist). Begin the calibration process with a different meter.
Dissolved Oxygen Post -Check Method
1. Repeat calibration steps 1-5 to create 100% humid environment for the sensor.
2. Record the Barometric Pressure and Temperature readings in the Post -Check box on the same
Calibration/Post-check sheet that was used for calibrating the meter.
3. Record the DO (%) and DO (mg/L) in the Initial box under the Post -Check section.
4. Repeat calibration step 11.
5. NOTE: The Chart DO value and the Initial DO (mg/L) value should be within ±0.5 of each other.
If the values are not within ±0.5 mg/L of each other, bring it to the attention of the WQ M&A
Specialist.
Specific Conductance Calibration Method
As recommended by YSI, specific conductance (temperature compensated conductivity at 25°C) is
calibrated instead of conductivity or salinity because of its ease and accuracy. Specific conductance (SC)
calibration should be performed using fresh, certified conductivity standards that reflect the anticipated
range of SC for the samples to be collected that day. The WQU usually performs a one -point calibration
using 1000 µS/cm standard and uses 1— 2 additional standards to confirm accuracy across the entire
calibrated range. While the calibration is performed with fresh standard, lightly used conductivity
standard, stored in bottles labeled "RINSING ONLY", is used for rinsing the sensor before completing the
calibration. This is done in an effort to reduce the amount of standard wasted and reduce costs.
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1. Record in the Specific Conductance Calibration section of the YSI Pro Plus Meter
Calibration/Post-Check Sheet the Lot Number and Expiration Date of each standard being used.
Ensure that all standards being used for calibration and post -check are not expired.
2. Rinse the sensors with Deionized (DI) water.
3. With the calibration cup attached, pour in a small amount of 1,000 [IS/cm SC standard from the
RINSING ONLY bottle and shake gently with the cap on to rinse the sensor. Discard rinse in the
sink. Repeat two more times for a total of 3 rinses.
4. After the third rinse, place the sensor bulkhead with calibration cup in the meter stand with
sensors facing up and fill the calibration cup with fresh 1000 µS/cm SC standard so the standard
completely covers the entire conductivity sensor and temperature probe. Wait for the meter
readings to stabilize.
5. Read the Temperature and Initial SC value and record it in the Specific Conductance (µS/cm at
25 °C) Calibration box on the calibration sheet.
6. Press the Cal key, highlight Conductivity, and press Enter.
7. Highlight Sp. Conductance and press Enter.
8. Highlight Calibration Value and press Enter. Input 1000 for the value of conductivity standard.
Highlight <<<Enter>>>, and press Enter.
9. Highlight Accept Calibration and press Enter to calibrate the meter.
"Calibrating channel..." and then "Saving configuration..." will be displayed at the bottom of the
calibration screen before returning to the main screen.
10. Wait for readings to stabilize. Record the displayed SC value in the Adjusted box in the Specific
Conductance section of the calibration sheet.
11. After accepting a calibration, navigate to the GLP file by pressing the File key and selecting View
GLP. Scroll down to view the conductivity sensor constant. Record the conductivity sensor
constant value in the green box under the Specific Conductance Calibration section.
NOTE: The acceptable range for cell constant after calibration is 5 ±1.0. A cell constant outside
this range indicates that a questionable calibration was accepted. If this is the case, attempt to
re -calibrate the same meter or select a new meter to calibrate if the issue persists.
After the meter is successfully calibrated with 1,000 µS/cm conductivity standard, it is then checked
with one additional SC standard and dry air to check if the calibration was successful. The WQU uses
200 µS/cm standard for the check and is described below, but selection of an actual value should be
based on the range of values expected in the field.
12. Pour the 1,000 VS/cm SC standard from the calibration cup into the RINSING ONLY bottle and
rinse the calibration cup and sensors with DI water.
13. Rinse the sensors 3 times with 200 VS/cm SC standard as done in step 3.
14. After the third rinse, place the sensor bulkhead on the meter stand with sensors facing up and
fill the calibration cup with fresh standard so the standard completely covers the entire
conductivity sensor and temperature probe.
15. Wait for meter to stabilize, and then record the readings for Temperature and Initial SC on the
calibration sheet in the 200 Std. Value column.
16. Confirm that the recorded reading for specific conductance is within 10% of the conductivity
standard (for 200 µS this is 180.0 — 220.0). Circle Yes (Y) or No (N) accordingly. If the value is not
within the acceptable range, attempt to re -calibrate the sensor. If the value continues to be
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outside of the acceptable range flag the meter and bring it to the attention of the WQ M&A
Specialist. Begin the calibration process with a different meter.
17. Pour the 200 µS conductivity standard that is in the calibration cup into the correct RINSING
ONLY bottle and rinse the sensor calibration cup with DI water.
18. Carefully shake the meter dry and place in the meter stand.
19. Wait for the meter to stabilize and record the current reading for Initial SC in the ***Dry Air***
column.
20. Confirm that the recorded reading is < 3.0 and circle Y or N accordingly. If the value is not < 3.0,
attempt to re -calibrate the sensor. If the value continues to be outside of the acceptable range
flag the meter and bring it to the attention of the WQ M&A Specialist. Begin the calibration
process with a different meter.
Specific Conductance Post -Check Method
1. Repeat calibration steps 2 through 4.
2. Once the meter has stabilized record the Temperature and Specific Conductance reading in the
1,000 column of the Specific Conductance Post -Check section on the Calibration/Post-Check
Sheet.
3. Confirm that the recorded value is within 10% of the standard (for 1000 µS this is 900 —1100)
and circle Y or N accordingly. Repeat this process for 200 µS and dry air, confirming each
standard is reading within the acceptable range. If any of the values are not within the
acceptable range, flag the meter and bring it to the attention of the WQ M&A Specialist.
pH Calibration Method
The pH sensor must be calibrated and checked prior to taking measurements in the field. A two -point
pH calibration is all that is required when the range of in -situ pH values are known. The expected in -situ
values should be bracketed, and pH 7 buffer standard should always be used regardless of how many
calibration points there are. Therefore, for a two -point calibration, 4 and 7 or 7 and 10 can be used. The
majority of surface waters sampled in the City of Durham can be bracketed between pH 7 and pH 10
under normal conditions. If pH values are unknown or are expected to be on both sides of the pH scale,
consult with the WQ M&A Specialist on the proper calibration method as a three-point calibration may
be necessary.
1. Record the Lot Number and Expiration Date of each buffer used for calibration in the pH
calibration section on the YSI Pro Plus Meter Calibration/Post-Check Sheet. Ensure that all
buffers being used for calibration and post -check are not expired.
2. Rinse the sensors and calibration cup with DI water and discard in the sink.
3. Starting with pH 7, pour a small amount of 7 buffer from the RINSING ONLY bottle in the
calibration cup and shake gently with the cap on to rinse for a total of 3 times. Discard the buffer
in the sink each time.
4. After the third rinse, use fresh buffer to fill the calibration cup with enough buffer to cover the
pH glass blub and temperature probe.
5. Press Cal and highlight ISE1 (pH) and press Enter. Once on the calibration screen, the prompt at
the bottom should read "Ready for point 1".
6. Record the temperature and initial pH reading in the pH 7 column of the calibration sheet.
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7. Using the current temperature, find the Theoretical (Theo.) pH value using the Reference pH
Chart (Appendix 3. pH Temperature Reference Table) and record it on the calibration sheet.
8. Check the Calibration Value at the top of the screen; this should match the Theo. pH value. If
the value on the screen does not match the Theoretical pH value, highlight Calibration Value
and press Enter. Input the Theo. pH value, highlight <<<Enter>>> and press Enter.
9. Highlight Accept Calibration, and press Enter.
10. The prompt on the bottom of the screen should now read "Ready for point 2".
NOTE: If you accidentally leave the pH calibration screen before the second (or final) point is
calibrated you must start the calibration process over. For a successful pH calibration, remain
on the calibration screen until all points are calibrated.
11. Pour the pH 7 buffer into the correct RINSING ONLY bottle.
12. Rinse the sensors and calibration cup with DI water and discard the water into the sink.
13. Using the second buffer (normally 10), pour a small amount of the buffer from the RINSING
ONLY bottle into the calibration cup, shake gently with the cap on, and discard the buffer into
the sink each time for a total of 3 rinses.
14. After the third rinse, fill the calibration cup with enough fresh buffer to cover the pH glass blub
and temperature probe.
15. Once the readings have stabilized, record the temperature and initial pH readings.
16. Using the recorded temperature reading, find the Theo. pH on the Reference pH Chart and
record in on the calibration sheet.
17. Check the Calibration Value at the top of the screen. This should be the same as the Theo.
Value. If it is different, highlight Calibration Value and press Enter. Input the correct value and
highlight <<<Enter>>>, and press Enter.
18. Highlight Accept Calibration and press Enter.
19. The prompt at the bottom should now read "Ready for point 3". If only performing a two -point
calibration, press Cal to finish the calibration process.
NOTE: If performing a three-point calibration, do NOT press Cal, repeat steps 12 —18 with
another buffer and then press Cal to finish.
20. Once the displayed measurements have settled, record the pH value in the Adjusted box on the
calibration sheet.
21. After accepting a good calibration, navigate to the GLP file on the meter by pressing the File key
then View GLP and scroll down to check the pH Slope (mV) and Slope % of ideal. Record these
values in the green boxes under the pH Calibration section of the calibration sheet.
NOTE: The acceptable range for Slope (mV) is between 55 and 60 mVs, and the acceptable
range for Slope % of ideal is between 93% and 102%.
22. Pour the buffer from the calibration cup into the correct RINSING ONLY bottle.
After the meter is successfully calibrated it is then checked with pH 7 buffer to ensure the calibration was
successful.
23. Rinse the sensors and calibration cup with DI water and discard into the sink.
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24. Using pH 7 buffer, pour a small amount of buffer from the RINSING ONLY bottle into the
calibration cup and shake gently with the lid on to rinse for a total of 3 times. Discard buffer into
the sink each time.
25. After the third rinse, pour enough fresh pH 7 buffer into the cup to cover the pH glass bulb and
the temperature probe.
26. Wait 1 to 3 minutes for the sensor to stabilize.
27. Record the displayed Temperature and Initial pH values in the confirmation column on the
calibration sheet.
28. Using the recorded temperature value find the Theo. value on the Reference pH Chart and
record it on the calibration sheet.
29. Confirm that the Initial value and the Theo. pH value are within ±0.1 of each other. Circle Y or N
accordingly. If the values are not within ±0.1 of each other, attempt to re -calibrate the sensor. If
the values continue to be outside of the acceptable range flag the meter and bring it to the
attention of the WQ M&A Specialist. Begin the calibration process with a different meter.
pH Post -Check Method
1. Starting with pH 7 buffer, repeat steps 23 — 28 from the calibration process.
2. Confirm that the Initial and Theo. pH values are within ±0.2 of each other. Circle Y or N
accordingly.
3. Using the second buffer (usually pH 10), repeat steps 23 — 28 from calibration process again.
4. Confirm that the Initial and Theo. pH values are within ±0.2 of each other. Circle Y or N
accordingly. If the value is not within the acceptable range, flag the meter and bring it to the
attention of the WQ M&A Specialist.
NOTE: If a pH of <6.9 was measured in the field, then the meter must be post -checked with pH
4.0 buffer. If this is the case, repeat steps 23 -28 from the calibration method and confirm that
the Initial and Theo. pH values are within ±0.2 of each other.
Meter Storage
For short-term storage (less than 30 days between uses) the meter should be powered off and stored
with all sensors attached in a temperature -controlled (between 0 and 45°C) secure location. The sensors
should also be stored with a very small amount (less than 1/8 of an inch) of pH 4 buffer inside the
calibration cup. The sensors should not be submersed in liquid. This is done to keep the sensors clean
and maintain a 100% saturated air environment which is ideal for short-term sensor storage.
For long-term storage, follow the recommendations of the manufacturer for each separate sensor as
some sensors should be stored wet while others can be stored dry. These recommendations can be
found in the YSI Pro Plus User Manual.
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YSI ProDSS Calibration and Post -Check Methods
Sensor Bulkhead
Sensors
YSI Pro DSS
Display Screen
Handheld with Keypad
Cable Port
Figure 3 Diagram of the YSI Pro DSS
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Tempe
Conductivity Sensor
I
pH Sensor
Figure 4 Sensors installed on the YSI Pro DSS
DO Sensor
Optical Dissolved Oxygen (ODO) Calibration Method
DO is calibrated by performing a 1 point calibration in water -saturated air, as recommended by YSI.
Optical Dissolved Oxygen (ODO) calibration requires the current "true" barometric pressure.
1. Remove the calibration cup from the sonde and check the ODO sensor for any signs of damage
or scratches.
2. Add a small amount (about 1/8 inch) of room temperature tap water into the calibration cup.
3. Carefully dry the ODO sensor cap and temperature probe with a lens wipe.
4. Attach the sensor guard to the bulkhead and carefully place the guard/sensor into the
calibration cup with sensors facing downward. When doing so, ensure to:
a. Only partially tighten the calibration cup to the bulkhead (twist no more than one to
two threads). Atmospheric venting is required for accurate calibration.
b. Make sure the ODO and temperature probes are not immersed in water.
5. Wait approximately 5 to 15 minutes for the air in the calibration cup to be completely saturated
with water, and to assure thermal equilibration between the temperature and optical DO
sensor.
6. While the DO sensor is stabilizing, begin to fill out the YSI ProDSS Meter Calibration/Post-Check
form (Appendix 4. YSI ProDSS Meter Calibration/Post-Check Sheet Example). Once the ODO
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sensor has stabilized, record the Barometric Pressure (InHg), Temperature (°C), DO saturation
(%), and DO concentration (mg/L) in the Initial row on the calibration sheet.
7. After recording the initial concentrations, push the Cal key, and select ODO and then select DO%
to calibrate DO%.
NOTE: Dissolved Oxygen should always be calibrated using % DO saturation.
8. Observe the actual measurement readings for stability (white line on graph shows no significant
change for 40 seconds), then select Accept Calibration. "Calibration successful!" will be
displayed in the message area.
9. In the Adjusted row on the calibration sheet, record the displayed values for DO (%) and DO
(mg/L).
10. Using the recorded barometric pressure and temperature values, find the Chart DO value on the
Dissolved Oxygen Table (Appendix 2. Dissolved Oxygen Concentration Table Related to
Barometric Pressure and Temperature) and record it on the calibration sheet.
NOTE: When finding the DO value from the table, round to the nearest 0.5°C for Temperature
and the nearest 0.10 InHg for pressure.
11. Confirm that the Chart DO value and Adjusted DO (mg/L) value are within ±0.5 mg/L of each
other. Circle Yes (Y) or No (N) accordingly. If the values are not within ±0.5 mg/L of each other,
attempt to re -calibrate the sensor. If the values continue to be outside of the acceptable range
flag the meter and bring it to the attention of the Water Quality Monitoring and Assessment
Specialist (WQ M&A Specialist). Begin the calibration process with a different meter.
12. After accepting the calibration, navigate to the GLP menu by pressing File, then View GLP.
Record ODO gain on the calibration sheet.
NOTE: The acceptable ODO gain range is 0.75 - 1.50. If the value is outside of the acceptable
range flag the meter and bring it to the attention of the Water Quality Monitoring and
Assessment Specialist (WQ M&A Specialist). Begin the calibration process with a different
meter.
Optical Dissolved Oxygen Post -Check Methods
1. Repeat calibration steps 1-5 to create 100% humid environment for the sensor.
2. Record the Barometric Pressure and Temperature readings on the meter in the Post -Check box
on the same Calibration/Post-Check sheet that was used for calibrating the meter.
3. Record DO (%) and DO (mg/L) in the Initial box under the Post -Check section.
NOTE: The Chart DO value and the Initial DO (mg/L) value should be within ±0.5 of each other
for post -checking. Circle Y or N accordingly. If the values are not within ±0.5 of each other,
bring it to the attention of the WQ M&A Specialist.
Specific Conductance Calibration Method
As recommended by YSI, specific conductance (temperature compensated conductivity at 25°C) is
calibrated instead of conductivity or salinity because of its ease and accuracy. Specific conductance (SC)
calibration should be performed using fresh, certified conductivity standards that reflect the anticipated
range of specific conductance for the samples to be collected that day. The WQU usually performs a
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT Page 16 of 29
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one -point calibration using 1000 µS/cm standard and uses 1-2 additional standards (usually 50 µS/cm or
200 µS/cm) to confirm accuracy across the entire calibrated range.
1. Record the SC standards' Lot Number and Expiration Date in the Specific Conductance section
on the YSI ProDSS Meter Calibration/Post-Check Sheet. Ensure that the standards being used for
calibration are not expired.
2. Prior to rinsing the sensors, record the specific conductance in dry air by removing the
calibration cup. The sensor should read <_ 1.0 VS/cm in room temperature. Record the value on
to the YSI ProDSS Meter Calibration/Post-Check Sheet.
3. Rinse the meter by filling DI water to the first line on the calibration cup, tighten cap, shake, and
discard rinse.
4. Next rinse the sensor and calibration cup with 1000 VS/cm SC standard from the RINSING ONLY
bottle and discard rinse in the sink. Repeat rinse with standard a total of 3 times.
5. After the third rinse, fill the calibration cup to the top line with fresh 1000 µS conductivity
standard.
6. Place sensors pointing downward with sensor guard on, into calibration cup making sure the
conductivity and temperature probes are submerged.
NOTE: Make sure solution is above the vent holes on the side of the conductivity sensor.
7. Gently move the sensor up and down a couple of times to remove any bubbles from the
conductivity sensor. Allow one minute for temperature equilibration before calibration.
8. Record the Temperature and Initial SC value in the Specific Conductance (µS/cm at 25°C)
Calibration box.
9. Push Cal, select Conductivity, then select Specific Conductance and scroll up to make sure the
calibration value is the standard being used (i.e. 1000 µS).
10. Select Calibration Value (1000 µS/cm at 250C). Observe the actual measurement readings for
stability (white line on graph shows no significant change for 40 seconds), then select Accept
Calibration. "Calibration successful!" will be displayed in the message area.
11. Record the displayed SC value in the Adjusted box in the specific conductance section of the
calibration sheet.
12. After successful calibration, navigate to the GLP file and record the cell constant on the
calibration sheet.
NOTE: Acceptable range for ProDSS cell constant sensors is 4.5 to 6.5.
13. Pour the 1,000 µS/cm conductivity standard from the calibration cup into the correct RINSING
ONLY bottle and rinse the calibration cup with DI water.
14. Rinse the meter 3 times with the second conductivity standard from the RINSING ONLY bottle.
Discard rinse into the sink.
15. After the third rinse, fill cup to the top line with fresh conductivity standard of the second
standard and carefully place the calibration cup so the standard completely covers the entire
conductivity sensor and temperature probe.
16. Wait for meter to stabilize (40 seconds or more), then record the readings for Temperature and
Initial SC on the calibration sheet.
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT Page 17 of 29
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NOTE: If the data is not stabilized after 40 seconds, gently rotate the sensor or adjust
calibration cup to make sure that no air bubbles are in the conductivity sensor.
17. Confirm that the recorded reading for specific conductance is within 10% of the conductivity
standard (for 50 µS this is 45.0-55.0). Circle Y (Yes) or N (No) accordingly. If the value is not
within the acceptable range, attempt to re -calibrate the sensor. If the value continues to be
outside of the acceptable range flag the meter and bring it to the attention of the WQ M&A
Specialist. Begin the calibration process with a different meter.
18. Pour the conductivity standard that is in the calibration cup into the correct RINSING ONLY
bottle and rinse the calibration cup with DI water.
19. After successful calibration, navigate to the GLP file and record the cell constant on the
calibration sheet.
NOTE: Acceptable range for ProDSS cell constant sensors is 4.5 to 6.5. A cell constant outside
this range indicates that a questionable calibration was accepted. If this is the case, attempt to
re -calibrate the same meter or select a new meter to calibrate if the issue persists.
Specific Conductance Post -Check Methods
1. Repeat calibration step 2. SC should read <_ 1.0 VS/cm in room temperature, and circle Y or N
accordingly.
2. Repeat calibration steps 3 — 7 using 1000 µS/cm standard.
3. Once the meter has stabilized record the Temperature and Specific Conductance reading in the
1,000 column of the Specific Conductance Post -Check box on the Calibration/Post-Check Sheet.
4. Confirm that the recorded value is within 10% of the standard (for 1000 µS this is 900 —1100)
and circle Y or N accordingly. If the values are not within the acceptable range, bring it to the
attention of the WQ M&A Specialist.
5. Repeat this process for the second standard used for calibration.
pH Calibration Methods
A two -point pH calibration is all that is required when the range of in -situ pH values are known and will
all be > 7.1 or all will be < 6.9. The expected in -situ values should be bracketed, and pH 7 should always
be used regardless of how many calibration points there are. Therefore, for a two -point calibration, 4
and 7 (when all readings will be > 6.9) or 7 and 10 (when all readings will be > 7.1) can be used. If pH
values are unknown or are expected to be on both sides of the pH 7, consult with the WQ M&A
Specialist on the proper calibration method as a three-point calibration may be necessary.
1. Record the Lot Number and Expiration Date of each buffer used for calibration and post -check
in the pH calibration box on the YSI ProDSS Meter Calibration /Post -Check Sheet. Ensure that all
buffers being used for calibration and post -check are not expired.
2. Rinse the meter by filling DI water to the first line on the calibration cup, tighten cap, shake, and
discard rinse.
3. Next rinse the sensor and calibration cup with pH 7 buffer from the RINSING ONLY bottle and
discard rinse in the sink. Repeat rinse with buffer a total of 3 times.
4. After the third rinse, fill calibration cup to the bottom line with fresh pH 7 buffer.
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT Page 18 of 29
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5. Carefully immerse the sensor end of the sensors in the buffer solution. Allow at least one
minute for temperature stabilization.
6. Push Cal, then select pH and press Enter.
7. Record the Temperature and Initial pH reading in the pH 7 column of the calibration sheet.
8. Using the current temperature, find the Theoretical (Theo.) pH value using the Reference pH
Chart (Appendix 3. pH Temperature Reference Table) and record it on the calibration sheet
(example: the value of pH 7 buffer at 20°C is 7.02).
9. Check the Calibration Value at the top of the screen; this should match the Theo. pH value. If
the value on the screen does not match the Theoretical pH value, highlight Calibration Value
and press Enter. Input the correct Theoretical pH value and press Enter.
10. Observe the actual measurement readings for stability (white line on graph shows no significant
change for 40 seconds), then select Accept Calibration. "Ready for cal point 2" will be displayed
in the message area.
NOTE: If you accidentally leave the pH calibration screen before the second point is calibrated
you must start over at point 1. For a successful pH calibration, remain on the calibration
screen until all points are calibrated.
11. Pour the pH 7 buffer into the correct RINSING ONLY bottle.
12. Repeat steps 2 — 8 with the second buffer (usually pH 10). Observe the actual measurement
readings for stability (white line on graph shows no significant change for 40 seconds), then
select Accept Calibration. "Ready for cal point 3" will be displayed in the message area.
13. If performing a 2-point calibration, select Finish Calibration and pour the buffer into the correct
RINSING ONLY bottle. If performing a 3-point calibration repeat steps 2 — 8 with the third buffer
(usually pH 4). Observe the actual measurement readings for stability (white line on graph
shows no significant change for 40 seconds), then select Accept Calibration. "Calibration
successful!" will be displayed in the message area. Pour the buffer into the correct RINSING
ONLY bottle.
14. After accepting the calibration, navigate to the GLP file and record the pH slope and slope %.
NOTE: The acceptable range for pH slope is 55 to 60 mV/pH and for pH slope % of the ideal is
93% - 102%.
After the meter is successfully calibrated it is then checked with pH 7 buffer to ensure the calibration
was successful.
15. Rinse the sensors and calibration cup with DI water and discard the water into the sink.
16. Using pH 7 buffer, pour a small amount of buffer from the RINSING ONLY bottle into the
calibration cup and rinse for a total of 3 times, discard buffer into the sink each time.
17. After the third rinse, pour fresh pH 7 buffer to the top line on the calibration cup and make sure
the sensors and the temperature probe are immersed in the buffer solution.
18. Wait 1 to 3 minutes for the sensor to stabilize.
19. Record the displayed Temperature and Initial pH values in the Confirmation column on the
calibration sheet.
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT Page 19 of 29
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20. Using the recorded temperature value find the Theo. value on the Reference pH Chart and
record it on the calibration sheet.
21. Confirm that the Initial value and the Theo. pH value are within ±0.1 of each other. Circle Y or N
accordingly. If the values are not within ±0.1 of each other, attempt to re -calibrate the sensor. If
the values continue to be outside of the acceptable range flag the meter and bring it to the
attention of the WQ M&A Specialist. Begin the calibration process with a different meter.
pH Post -Check Method
1. Starting with pH 7 buffer, repeat steps 15 —19 from the calibration process.
2. Confirm that the Initial and Theo. pH values are within ±0.2 of each other. Circle Y or N
accordingly.
3. Using the second buffer (generally pH 4.0 or 10.0), repeat steps 15 —19 from the calibration
process.
4. Confirm that the Initial and Theo. pH values are within ±0.2 of each other. Circle Y or N
accordingly.
5. Finally, if using a third buffer (generally pH 10.0 or 4.0), repeat steps 15 —19 from the calibration
process again.
6. Confirm that the Initial and Theo. pH values are within ±0.2 of each other. Circle Y or N
accordingly. If any of the pH values are not within the acceptable range, bring it to the attention
of the WQ M&A Specialist.
Depth Calibration, Air Method
The depth sensor on the YSI ProDSS is located where the cable connects to the bulkhead. For calibration
make sure the depth sensor is clean and in the air.
1. Write the initial depth reading from meter on the YSI ProDSS Meter Calibration/Post-Check
Sheet.
2. Push the Cal key, and then select Depth.
3. Observe the actual measurement readings for stability (white line on graph shows no significant
change for 40 seconds), and then select Accept Calibration "Calibration successful!" will be
displayed in the message area.
NOTE: There is no Post -check procedure necessary for depth
Meter Storage
For short-term storage (less than 4 weeks) the meter should be powered off and stored with all sensors
attached in a temperature -controlled (between 0 and 45°C) secure location. The sensors should also be
stored with a very small amount (less than 1/8 of an inch) of pH 4 buffer inside the calibration cup with
the guard attached. The sensors should not be submersed in liquid. This is done to keep the sensors
clean and maintain a 100% saturated air environment which is ideal for short-term sensor storage.
For long-term storage, YSI recommends uninstalling the sensors from the bulkhead and following each
sensor's respective long-term storage instructions. These recommendations can be found in the YSI Pro
DSS User Manual.
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT Page 20 of 29
03/25/2019

HACH 2100Q Turbidimeter Calibration
HACH 2100Q Turbidimeter
Lid
Cell Compartment
Alignment Arrow
• Sample Cell
C
Display Screen
Q
Calibration Key Q Data Management Key
r
Settings Key
W
On/Off Button
Figure 5 Diagram of the HACH 2100Q Turbidimeter
As recommended by the manufacturer, the HACH Turbidimeter is calibrated every three months using
StablCal Stabilized Standards. Calibration of the turbidimeter is recorded on the HACH 2100Q
Turbidimeter Quarterly Calibration/Maintenance Sheet (Appendix 5. HACH Turbidimeter Maintenance
and Calibration Sheet).
1. Fill out the date, time, and staff sections on the calibration sheet and make note of the serial
number of the turbidimeter that is being calibrated.
2. Push the CALIBRATION key to enter Calibration mode and follow the instructions on the display.
3. Starting with the 20 NTU Standard cell, record the lot number and expiration date written on
the cell.
4. Using a lens wipe, wipe the standard cell clean of any residual water or fingerprints.
5. Holding the standard cell by the lid, gently invert the standard cell a couple of times to
homogenize the contents of the cell.
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT Page 21 of 29
03/25/2019

6. Insert the standard cell into the turbidimeter cell compartment so that the alignment arrow on
the outside of the cell aligns with the alignment arrow on the front of the turbidimeter cell
compartment. Close the lid.
7. Push Read. "Stabilizing" will be displayed on the screen, and then the result will be shown.
8. Record the displayed result on the calibration sheet in the Value box under the corresponding
standard column.
9. Repeat steps 3 —8 with the 100 NTU standard and then again with the 800 NTU standard.
10. Once all three standards have been calibrated, press Done to review the calibration details.
11. Push Store to save the results.
12. The meter automatically goes into Verify Cal mode to confirm that the calibration was
successful. Using the 10 NTU standard repeat steps 3 — 8 to complete the calibration
confirmation.
Pre -Trip Check
The turbidimeter should be checked prior to taking measurements in the field to confirm it has
remained calibrated, which validates the sampling data. This Pre -Trip Check is recorded on the YSI Pro
Plus or YSI ProDSS Meter Calibration/Post-Check Sheet (Appendix 1 and 4).
1. Record when the turbidimeter was last calibrated on the YSI Pro Plus or ProDSS
Calibration/Post-Check Sheet. This date can be found in the maintenance log under the HACH
turbidimeter tab or labeled on the turbidimeter case.
2. Fill a clean sample cell with DI water.
3. Complete steps 4 — 7 from the calibration process.
4. Record the displayed value in the corresponding box on the calibration sheet.
5. Confirm the recorded value is < 0.4 NTU. Circle Y or N accordingly. If the value is not within the
acceptable range, repeat steps 4-7 in the calibration process. If the value continues to be
outside of the acceptable range, flag the meter and bring it to the attention of the WQ M&A
Specialist. Begin the calibration process with a different turbidimeter.
6. Using the 100 NTU StablCal° Stabilized Standard complete steps 3 — 7 from the calibration
process.
7. Record the displayed value in the corresponding box on the calibration sheet.
8. Confirm the recorded value is between 90 — 110 NTU. Circle Y or N accordingly. If the value is
not within the acceptable range, repeat steps 4-7 in the calibration process. If the value
continues to be outside of the acceptable range, flag the meter and bring it to the attention of
the WQ M&A Specialist. Begin the calibration process with a different turbidimeter.
9. If readings > 100 NTU are anticipated during field measurements, repeat steps 3 -7 from the
calibration process using the 800 NTU StablCal° Stabilized Standard to demonstrate that the
meter is accurate across the full range of readings for the day. Record reading on the calibration
sheet below the "Turbidity Pre -Trip Check" section. Confirm the recorded value is between 720 -
880 NTU. If the value is not within the acceptable range, repeat steps 4-7 in the calibration
process. If the value continues to be outside of the acceptable range, flag the meter and bring it
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT Page 22 of 29
03/25/2019

to the attention of the WQ M&A Specialist. Begin the calibration process with a different
turbidimeter.
NOTE: There is no Post -Check procedure necessary for turbidity (NTU).
Troubleshooting Calibration and Post -Check Issues
If a meter does not pass a calibration or calibration check do not take it out in the field. Flag the meter
with a description of the issue and calibrate another meter to take out in the field. Additionally, if an
error message is displayed on the meter during calibration, the calibration should be declined, as
accepting it may result in erroneous data. All issues that occur during calibration should be noted in the
maintenance log and staff should attempt to troubleshoot the issues. Tips for troubleshooting can be
found in meter user manuals and the calibration tips guide from the manufacturer.
If a meter does not pass the post -check, make a note on the calibration/post-check form and bring it to
the attention of the WQ M&A Specialist. Staff should attempt to troubleshoot the issue in a reasonable
amount of time.
Any equipment that is repeatedly having issues with calibrations or post -checks, is damaged, or
otherwise not operating correctly should be brought to the attention of the lab manager for more in-
depth troubleshooting.
Equipment Maintenance
All meters are maintained on a monthly and quarterly schedule. The specific maintenance tasks
performed on each meter can be found in the Maintenance Logs stored on the COD server and in the
SW Lab. The monthly maintenance involves more general maintenance including the following tasks:
• Visual inspections
• Checking O-Rings
• Wiping/cleaning of the meter handheld and cables
• Changing batteries as needed
Quarterly maintenance involves more in-depth tasks such as:
• Performing pH slope tests
• Changing DO membrane caps
• Removing all sensors and checking for dampness in the connections
• Brushing the conductivity sensor
• Carefully cleaning pH bulb
• Calibrating the Turbidimeter
However, the specific maintenance tasks are different for each meter and are in accordance with the
recommendations of the manufacturer. Maintenance Logs are reviewed for completeness and accuracy
by the WQ M&A Specialist.
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT Page 23 of 29
03/25/2019

Data and records management
Calibration and Post -Check data are recorded on individual Calibration/Post-Check Sheets. The hard
copies of the Calibration/Post-Check Sheets are stored in the office of the WQ M&A Specialist. Scans of
the Calibration/Post-Check Sheets are stored on the COD server.
All maintenance performed on a meter is recorded on meter -specific Maintenance Logs. These
Maintenance Logs are stored in a binder that can be found in the SW Lab. Hard copies of user manuals
for all meters can also be found in the Stormwater lab and in digital form on the COD server.
Quality assurance and quality control (QA/QC)
Once Calibration/Post-Check Sheets are completed, WQ staff should check the sheets for completeness
and errors. All Calibration/Post-Check Sheets are reviewed for completeness and accuracy by the WQ
M&A Specialist on a monthly basis. Once the check is complete the WQ M&A Specialist scans the sheets
and stores them on the COD server for WQ staff to review any errors that might have occurred. On any
data where meter calibrations or post -sampling checks did not meet stated criteria for one or more
parameters, field data should be appropriately qualified (flagged) in the data warehouse to indicate
readings are of questionable quality. Field measurements should also be qualified if they are outside of
the range of the standards used for calibration or post -check on that day. For more information on
flagging results and data qualifiers, see Standard Operating Procedures for Use of the Water Quality Web
Portal (City of Durham 2018).
References
City of Durham. 2017. Safety Operating Procedures. Department of Public Works. Durham, North
Carolina.
City of Durham. 2018. Standard Operating Procedures for Use of the Water Quality Web Portal (DRAFT).
Stormwater and GIS Services, Water Quality Unit.
Hach Company.2017. Hach 2100Q and 2100Qis User Manual. https://www.hach.com/2100q-portable-
turbidimeter/product-downloads?id=7640450963&callback=pfb
YSI Incorporated. 2009. YSI Professional Plus User Manual.
https://www.ysi.com/File%20Library/Documents/Manuals/605596-YSI-ProPIus-User-Manual-RevD.pdf
YSI Incorporated. 2010. Professional Plus Calibration Tips, Rev A.
https://www.ysi.com/File%20LibrarV/Documents/Tips/YSI-Professional-Plus-Calibration-Tips.pdf
Xylem Incorporated. 2018. ProDIGITAL User Manual.
https://www.ysi.com/File%20Library/Documents/Manuals/YSI ProDSS User Manual English.pdf
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT Page 24 of 29
03/25/2019

Appendix 1. YSI Pro Plus Meter Calibration/Post-Check Sheet Example
CALI BRAT ON
Date:
T me:
Initials
POST CHECK
Date:
Time:
Initials
Monitoring pH Data
Min:
Max:
.. IfpH is r69, post di do with pH40
YSI Pro Plus Meter Calibration / Post Check Sheet
S/N: Hadi Turbidity Meter S/N
Fie I d Crew: Stu dy: cou�orra°Fr
Turbidity Pre -Trip Check*
Dissolved Oxygen (DO) Calibration
DO Post Check
Turbidity (NTLI)
Temperature I°Cj:
Temp (°C):
DI HBO �m-1j
c 0-4 NTu?
Y N
Ba ram et ric Pressure (InHg):
BP (I nHg):
DO%}
DO (mg/L}
DO (%)
DO (mg/L)
Std, 100NTtl
Initial
Lot#
90-III) NTu?
Y N
Adjusted
Std Exp- Date:
Chart DO jxxx mE DO I%j
Chart DO
urbidity me ter las t calibrated
Within±0-5?
Y N
Within±0-5?
Y N
5p. Conductance Standard (pS/cm at
25°C)
Std
tat No.
Erpiratbn
20D
low
Post Chedc-SameStd? Y N
pH 5ta ndard Is. u.I
Std
lot No-
Erpirotbn
7
10
4
Post Chedc- Some Std? Y N
Sp e c if i c Co n d u it a n ce jµS/cm at 25°Cj Cal ib rati on
SpeoficConductance PostCheck
Std. Value
1,000
200
•••Dry Air•••
1,01DO
200
••D ry Air•••
Temp
Initial
Adjusted
Aft -Calibrations
Cell Constant
180.0-220.0?
Y N
r3-0?
Y N
900-1100?
Y N
180-0-220-(P
Y N
r3-0?
Y N
Acceptobk Cell Constontronge 4.0-6.0
PH is-u -) Cal i bration
Confirmation
pH PostCheck
Optional
Std. Value
7
in
7
7
10
4
Temp
Initial
Theo- pH
Adjusted
After Ca I brationi
S1ape jmvj
Slope %of ideal
Wit hin±0-1?
Y N
Within±0-2?
Y N
Within±0-2?
Y N
Within±0-2?
Y N
AcceptobkpHsbpe (mV/pH): 55-60mV/pHslope(%ofide1),%%to ID2% 1den1pHs1ope=99-V
--bidity meters are calibratedquart-ly, see-Lrbioity Calibration Book fordetails
- xr Calibration, DID sensor val ue, sp. conductance cell mnsm nt and the pH s lope/ %slope is recorded from the rmeter's GI-P fi le
*NOTE: This is only an example of Pro Plus Calibration/Post-Check Sheet. The most updated version of this form can be found on the COD server.
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT Page 25 of 29
03/25/2019

Appendix 2. Dissolved Oxygen Concentration Table Related to Barometric Pressure and
Temperature
solubility of oYVgen in fresh water at various tempe ratu nm and pressures
[solubility Sawn in milligrams per ita. Values based on published equations by Benson and 6lause (IM0and 196 deg C - degrees Celsius; "n Hg - aches of n-t y]
ResultsfromD9 ABLMprogamathttp://water.usgzgw(5oflwaFe 0MABLE5/.
Table g-ted Friday n-n n-w t7 m m EST -
original resdts in {nlig}; these values were converted to r g [elm/ a0 371 and added to the -1u hearings
re mp
Barometric Pressure -as it Hg (top w I u m n I able) and m m Hg (botm m column lab lei
I
[9U)
28.70 1 29M
28.90
29.00
1 29.10
29.20
29.30
1 29A0 1 2950 1 29.60 1 29.70 1 29.80 1 29.90 1 30,00 1 30.10 1 30.20 1 30.30 30A0
3050
1 30.60
30.70
30.80
30.90 1
31.001
15.0
9.67 ! 9.70
9.73
9.77
9.80
9-84
9.87
9.91 ! 9.94 ! 9.97 ! 10.01 ! 10.04 ! 10.08 ! 10.11 ! 10.15 ! 10.18 ! 10.21 ! 10.25
1028
10.32
10.35
10.38
10.42
10-45 1
155
9.56 9.60
9.63
9.66
9.70
9.73
9.77
9.90 9.83 9.87 9.90 9.93 9.97 10.00 10.04 10.07 10.10 10.14
10.17
10.21
10.24
10.27
10.31
10.34
16.0
9.46 9.49
9.53
9.56
9.59
9.63
9.66
9.70 9.73 9.76 9.80 9.83 9.86 9.90 9.93 9.96 i 10.00 10.03
10.06
10.10
10.13
10.17
10.20
1023 1
165
9.36 i 9. 39
9.43
9.46
9.49
9.53
9.56
i
9.59 i 9.63 i 9.66 i 9.69 i 9.73 i 9.76 i 9.79 i 9.83 i 9.86 i 9.89 i 9.93
9.96
9.99
10.03
10.06
10.09
10.13 1
17.0
9.26 ! 9-30
933
936
939
9-43
9.46
9.49 ! 953 ! 9.56 ! 9.59 ! 9.62 ! 9.66 ! 9.69 ! 9.72 ! 9.76 ! 9.79 ! 9.82
9.86
9.89
9-92
9.95
9.99
10-02
175
9.17 ! 9.20
923
9.26
9.30
9.33
9.35
9.40 ! 9.43 ! 9.46 ! 9.49 ! 9.53 ! 9.56 ! 9.59 ! 9.62 ! 9.56 ! 9.69 ! 9.72
9.75
9.79
9.82
9.85
9.88
9.92
18.0
9.07 9-11
9.14
9.17
920
9.23
9.27
9.3❑ 9.33 9.36 9.40 9.43 9.46 9.49 9.52 9.56 i 9.59 9.62
9.65
9.69
9.72
9.75
9.78
9.82
185
9.99 9.01
9.04
9.08
9.11
9.14
9.17
9.20 9.24 9.27 9.30 9.33 9.36 9.40 9.43 9.46 i 9.49 i 9.52
9.56
9.59
9.62
9.65
9.68
9.72 I
19.0
8.89 ! 8.92
8.95
8.99
9.02
9.05
9.08
9.11 ! 9.14 ! 9.17 ! 9.21 ! 9.24 ! 9.27 ! 9.30 ! 9.33 ! 9.36 ! 9.40 ! 9.43
9.45
9.49
9.52
9.55
9.59
9.52 1
195
8.80 ! 8.83
8.86
8.89
8.93
8.96
8.99
9.02 ! 9.05 ! 9.08 ! 9.11 ! 9.15 ! 9.18 ! 9.21 ! 9.24 ! 9.27 ! 9.30 ! 9.33
9.37
9.40
9.43
9.45
9.49
9.52 I
20.0
8.71 8-74
8.77
8.81
8.84
8-87
8.90
8.93 8.96 8.99 9.02 9.05 9.09 9.12 9.15 9.18 i 9.21 9.24
927
930
933
9.37
9.40
9.43
205
9.63 i 9.66
8.69
8.72
8.75
8.79
8.81
8.94 i 8.97 i 8.90 i 9.93 i 8.97 i 9A0 i 9.03 i 9.06 i 9.09 i 9.12 i 9.15
9.18
9.21
9.24
9.27
9.30
9.34 I
21.0
8.54 i 8-57
8.60
8.63
8.66
8-69
8.73
8.76 i 8.79 i 8.82 i 9.85 8.88 8.91 8.94 8.97 9.00 i 9.03 9.06
9.09
9.12
9.15
9.18
921
924 I
215
8.46 ! 8.49
9.52
9.55
9.59
861
8.64
8.67 ! 8.70 ! 9.73 ! 8.75 ! 8.79 ! 8.82 ! 8.85 ! .9.88 ! 9.91 ! 8.94 ! 8.97
9.00
9.03
9.06
9.09
9.12
9.15 1
22.0
8.38 ! 8.41
8.44
8.47
8.50
8.53
8.56
8.59 ! 8.62 ! 8.65 ! 9.68 ! 8.71 ! 8.74 ! 8.77 ! 8.go ! 8.83 ! 8.86 ! 8.89
8.92
8.95
8.98
9.01
9.04
9.07
225
9.30 9.33
8.35
9.39
9.42
9.45
8.48
9.51 9.54 9.56 8.59 8.62 9.65 8.69 9.71 9.74 i 9.77 8.80
9.93
8.86
8.89
8.92
8.95
8.98
23.0
8.22 8.25
828
8.31
834
837
8.40
8.42 8.45 8.48 831 8.54 8.57 9.60 8.63 8.66 i 8.69 8.72
8.75
8.78
8-81
8.84
8.87
8.90 1
235
8.14 9.17
i
9.20
9.23
9.26
8.29
8.32
8.35 8.37 8.40 8.43 8.46 8.49 8.52 .9.55 8.58 8.61 8.64
i i i i i i i i i i
8.67
8.70
8.73
8.75
8.78
8.81
24.0
8.06 ! 8-09
8.12
8.15
8.18
8.21
824
8.27 ! 8.30 ! 8.33 ! 8.35 ! 8.38 ! 8.41 ! 9.44 ! 8.47 ! 8.50 ! 8.53 ! 8.56
839
8.61
8-64
8.67
8.70
8.73
245
7.99 9.02
8.05
8.08
9.10
8.13
8.15
9.19 8.22 8.25 8.28 8.31 a.33 8.36 8.39 9.42 i 9.45 9.49
9.51
9.54
8.56
8.59
8.62
8.65 1
25.0
7.92 7.94
7.97
8.00
8.03
8.06
8.09
8.11 8.14 8.17 9.20 823 8.26 9.29 8.31 8.34 i 8.37 8.40
8.43
8.46
8.49
8.51
8.54
8.57
255
7.84 7.97
7.90
7.93
7.96
7.98
8.01
9.04 9.07 8.10 8.13 9.15 9.19 8.21 .9.24 9.27 i 8.29 8.32
9.35
9.39
9.41
8.44
9.46
8.49 1
26.0
7.77 ! 7.80
7.83
7.86
7.88
7-91
7.94
7.97 ! 8.00 ! 8.02 ! 9.05 1 8.08 1 8.11 1 9.14 1 .9.16 1 8.19 ! 8.22 ! 8.25
828
830
8.33
8.36
839
8.42
265
7.70 ! 7.73
7.76
7.79
7.91
7.94
7.97
7.90 1 7.92 1 7.95 1 7.98 1 8.01 1 9.03 1 8.06 1 9.09 1 9.12 ! 9.15 ! 8.17
9.20
9.23
8.26
8.28
8.31
8.34
27.0
7.63 i 7-66
7.69
7.71
7.74
777
7.80
7.82 i 7.85 i 7.88 i 7.91 i 7.94 i 7.96 i 7.99 i 8.02 i 8.05 i 8.07 8.10
8.13
8.16
8-18
821
824
827 1
275
7.56 i 7.59
7.62
7.65
7.67
7.70
7.73
7.75 i 7.79 i 7.91 i 7.94 i 7.86 i 7.89 i 7.92 i 7.95 i 7.97 i 8.00 8.03
8.06
8.08
8.11
8.14
9.17
8.19
28.0
7.50 ! 7.52
7.55
7.59
7.60
7.63
7.66
7.69 ! 7.71 ! 7.74 ! 7.77 ! 7.79 ! 7.82 ! 7.85 ! 7.89 ! 7.90 ! 7.93 ! 7.96
7.98
8.01
8-04
8.07
8.09
8.12
285
7.43 ! 7.46
7.48
7.51
7.54
7.56
7.59
7.62 ! 7.65 ! 7.67 ! 7.70 ! 7.73 ! 7.75 ! 7.79 ! 7.91 ! 7.83 ! 7.86 ! 7.89
7.91
7.94
7.97
8.00
8.02
8.05
29.0
7.36 7.39
7.42
7.44
7.47
7.50
7.53
7.55 7.58 7.61 7.63 7.66 7.69 7.71 7.74 7.77 7.79 7.82
7.85
7.87
7.90
7.93
7.95
7.98
295
7.30 7.33
7.35
7.38
7.41
7.43
7.46
7.49 7.51 7.54 7.57 7.59 7.62 7.65 7.67 7.70 i 7.73 7.75
7.79
7.80
7.83
7.85
7.88
7.91 1
30.0
7.24 i 7-26
729
732
734
737
7.40
I
7.42 i 7.45 i 7.47 i 750 i 753 i 755 i 758 i 7.61 i 7.63 i 7.66 i 7.68
7.71
7.74
776
7.79
782
7.84
-H9
729 732
734
-137
-139
742
-144
747 749 752 754 7,71759 762 765 767 770 772
775
777
780
782
785
787
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT Page 26 of 29
03/25/2019

Appendix 3. pH Temperature Reference Table
Theoretical pH Values
Temp buffer buffer buffer
in °C 4.01 7.00 10.01
0
4,dv
7.11
10.32
1
4.0D
7.11
10.31
2
4.a )
7.10
10.29
3
4 oe
7.09
10.28
4
4.vO
7.09
10.26
5
4, o b
7.08
10.25
6
4 vv
7.o8
10.23
7
4,oc:
7.07
10.22
8
41do
7.07
10.21
9
4.0a
7.o6
10.20
10
4,vd
7.06
10.18
11
4.00
7.05
10.17.
12
4,vd
7.05
lo.16
13
4 ov
7.04
10.14
14
4 vv
7.04
10.13
15
4,B0
7.03
10.12
16
4 00
7.03
10.11
17
4. Dd
7.02
10.10
18
4,vr)
7.02
10.09
19
4,dO
7.02
10.08
20
4'dC)
7.01
10.06
21
4.01
7.01
10.05
22
4.01
7.01
10.04
23
4.01
7. do
10,03
24
4.01
7 "
10.02
25
4.01
7 do
10.01
26
4.01
6.99
10,00
27
4.01
6.99
9.99
28
4.01
6.99
9.98
29
4.01
6.99
9.98
30
4.02
6.98
A.Q7
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT Page 27 of 29
03/25/2019

Appendix 4. YSI ProDSS Meter Calibration/Post-Check Sheet Example
CA LI B RATi ON
Date:
Time:
Initials
PO ST CH EC K
Date:
Time:
Initials
Mon itori ng pH Data
Min:
Max:
Sp.Canductance Standard(p5/vn at
2-S-C)
Std
tot No.
Ex iration
50
10m
Post Check -Some Std? Y N
pH Standard[s.u.}
Std
tot Af.-
Expiration
7
10
4
Post Check -Same Std? Y N
YSI ProDSS Meter Calibration / Post Check Sheet
S/N : Hach Turbidity Me to r S/N IN
Field Crew: Study: In' -
Guiiii N1
Turbidity Pre Trip Check"
Dissolved Oxygen (DO) Calibration
❑O Post Check
TurbidityNTLI
Barometric Pressure(InHgl:
BP (In i<04NII
DI HiO (m.lj
Y IN
Temperature ('Cl:
Temp(°C):
1X7(1)
DO(mg/L}
DO I%)
❑O(mg/L}
Sid: 1001
Initial
lot#
90-110 NTIJI
Y N
Adjusted
Std Ex . Date:
Chart ❑O (xxx mg/L)
Chart DO
Turbidity Meter last calibrated
OQO gain
After Cali 6ration`
Within±O.SP
Y N
Within I0.5P
Y N
Acceptable O!]O range is 0.75 to 1.50
SperificConduct an[ e(p5/cm at 27C) Ca l ibratlon
Confi me at ion
Sp ecifi c C on du at a nice Past Check
Std. Value
Dry Ai r'•'
S0
1,000
•••Dry Air'•'
50
xx
Tema
Initial
Adjusted
After Cal i bra b on`
Cell Constant
a 107
Y N
45-557
V N
900-11007
Y N
a107
V N
45-557
Y N
Acceptable Cell Cons rant range: 4.5-&S
❑epth (m} A1r Ca 11 b ration
Initial
Adjusted
pH (s.u.}calibration
Confirmation
pH Post C heck
Sid. Value
7
7S1
4
7
7
1!
4
Temp
Initial
ihea-pH
Adjusted
a Ca brati on
Slope (mV)
lope(%of itleal
Within±017
Y N
Within±0.27
Y N
Within±G2�
V N
Within±0-27
Y N
Acceptohle pHslope (mV/pN): SS- GO mV /p Nsbpe (9S ofidenlJ: 9396 to 10296 Id-1 pH slope = 59 mV
'lurb id i ty meters are zal i bratez aza—rl Y. see —zr bi z ity Ca I bratior book For zeta i I s
`After Ca li bra tior, 0DO gair, sp Zor zz Z. r Z. Zell zor start arz tYe ph slope; A slope Is repo rz ez from tYe meter's GLP file
NOTE: This is only an example of the YSI ProDSS Meter Calibration/Post-Check Sheet. The current version of the form is located on the COD
server.
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT Page 28 of 29
03/25/2019

Appendix S. HACH Turbidimeter Maintenance and Calibration Sheet
HACH 2100Q Tubidimeter Quarterly Calibration/ Maintenance Sheet
(January, April, July & October)
CALIBRATION
Date:
Time:
Staff:
Batteries Changed:
Y / N
Visual Inspection:
Y / N
Metercleaned:
Y / N
CALIBRATION
Date:
Time:
Staff:
Batteries Changed:
Y { N
Visual Inspection:
Y { N
Metercleaned:
Y { N
CALIBRATION
Date:
Time:
Staff:
Batteries Changed:
Y / N
Visual Inspection:
Y / N
Metercleaned:
Y { N
CALIBRATION
Serial #6500
Turbidity (NTU) Calibration
ConfIrmatlor
Vial Clarity
Standard
20 NTU
100 NTU
800 NTU
10 NTU
(< 0.5 NTU)
Value
y / N
Lot #OEM
Exp, Date
Comments:
Serial #6605
Turbidity(NTU)Calibration
CorCrmatioi
Vial Clarity
Standard
20 NTU
100 NTU
800 NTU
10 NTU
(< 0.5 NTU)
Val ue
Y / N
Lot #
Exp. Date
Comments:
Serial #6500
Turbidity(NTU) Calibration
Corflrmatioi
Vial Clarity
Standard
20 NTU
100 NTU
800 NTU
10 NTU
(¢ 0.5 NTU)
Value
Y { N
Lot #
Exp. Date
Comments:
Serial #6605
Date: Turbidity (NTU) Calibration
Time: Standard 20 NTU I 100 NTU I 800 NTU
Staff:
Value
Batteries Changed:
Y / N
Lot #
Visual Inspection:
Y / N
Exp. Date
Metercleaned:
Y / N
Comments:
City of Durham, WQ Unit, Field Meter Calibration and Maintenance SOP, v. 1.0 DRAFT
03/25/2019
Confirmatio VialCla(r
10 NTU (<0.5NT1
Y / N
Page 29 of 29