FT 2000. FIELD MEASUREMENT OF RESIDUAL CHLORINE

FT 2000. FIELD MEASUREMENT OF RESIDUAL CHLORINE Use in conjunction with: FT 1000 General Field Testing and Measurement FQ 1000 Field Quality Control Requirements FS 1000 General Sampling Procedures FD 1000 Documentation Procedures Chlorinating water supplies and polluted waters at treatment facilities is a common practice to destroy or deactivate disease-producing microorganisms. This SOP describes the most commonly used field procedures for measuring the residual chlorine that remains after chlorination. FT 2010. DPD COLORIMETRIC METHOD 1. SCOPE AND APPLICABILITY: FDEP recommends this method if the testing levels that must be met are between 0.2 to 4.0 mg-cl/l. This method only measures total residual chlorine as opposed to the titrimetric and iodometric-electrode methods that can distinguish between free and combined forms of chlorine. The DPD-colorimetric is best suited for polluted waters (e.g., wastewater effluents) because it is the least affected by the presence of organic matter in the sample. 2. EQUIPMENT AND SUPPLIES 2.1. Field Instruments: 2.1.1. Photometric equipment: 2.1.1.1. Spectrophotometer, for use at a wavelength of 515 nm and a light path of 1 cm or longer; or 2.1.1.2. Filter Photometer, equipped with a filter having maximum transmission in the wavelength range of 490 to 530 nm and providing a light path of 1 cm or longer. 2.1.1.3. The instrument must allow calibration using at least one standard and a blank. 2.1.2. Color Wheel Comparator (only approved for drinking water compliance). 2.2. Sample Cells (cuvettes): Use sample cells or tubes of clear, colorless glass or plastic. 2.2.1. Keep cells scrupulously clean, both inside and out, and discard if scratched or etched. 2.2.2. Never handle them where the light beam strikes the sample. 2.2.3. Clean sample cells by thorough washing with laboratory soap (inside and out) followed by multiple rinses with distilled or de-ionized water, and let air-dry. 2.2.4. Mask minor imperfections or scratches in the cells with a very thin layer of silicone oil on the outside surfaces. Use silicone oil with the same refractive index of the glass; making sure the cell appear to be nearly dry with little or no visible signs of oil. Page 1 of 20 Revision Date: January 1, 2002

2.2.5. Because small differences between cells significantly impact measurement, use either matched pairs or the same cell for standardization and sample measurement. 2.3. Reagents and Standards: 2.3.1. DPD reagent powder pillows (from commercial supplier) or 2.3.2. Phosphate buffer solution and DPD indicator solution (prepared according to EPA 330.5 or SM 4500-Cl-G). 2.3.3. Standard Potassium Permanganate solutions ( Chlorine Standards ) prepared in the appropriate concentration range of interest according to method EPA 330.5 or SM 4500-Cl-G. 2.3.4. If used, two sets of secondary standards from a commercial vendor. 2.3.5. Chlorine-demand-free water and appropriate glassware. 2.4. Recordkeeping and Documentation Supplies: Field notebook (w/ waterproof paper is recommended) Field/Lab record forms (e.g., forms FD 9000-12, FD 9000-13 and FD 9000-14) Indelible pens 3. CALIBRATION AND USE 3.1. Interferences: Sample color and turbidity may interfere in all colorimetric procedures applied to natural and treated waters. Other possible interferences are from: bromine, chlorine dioxide, iodine, permanganate, hydrogen peroxide, and ozone. Bromine will always interfere when measuring residual chlorine in estuarine and marine waters. 3.2. Instrument Calibration (spectrophotometer or photometer): These procedures apply to photometric instruments; the color wheel comparator is factory calibrated. 3.2.1. See FT 1000, section 2.2 for specific quality control measures that must be observed. 3.2.2. Follow the manufacturer s operating instructions. 3.2.3. Initial Calibration: Use the chlorine standards (see 2.3.3 above) for initial calibration of the photometers. 3.2.3.1. Use as many standards as allowed by the instrument. FDEP recommends 4 standard concentrations and a blank, however the instrument must have the ability to be calibrated with at least one standard and a blank. 3.2.3.2. If the sample concentration range is unknown, calibrate with standards in the 0.05 to 4.0 mg-cl/l range. 3.2.3.3. The correlation coefficient of the standard curve must be greater than or equal to 0.995. 3.2.3.4. If only one standard is used to calibrate, the standard must be greater than the highest expected sample concentration. Check the accuracy of the curve by measuring a standard like a sample, and comparing the result with the known standard value. This check standard must be near the expected concentration of the majority of the samples and the instrument reading must be within 10% of the standard value. 3.2.4. Continuing Calibration: Page 2 of 20 Revision Date: January 1, 2002

3.2.4.1. Use at least two standards at two different concentrations in the field for continuing calibration checks. 3.2.4.2. The standards may be secondary standards or chlorine standards (see 2.3.3 above). 3.2.4.3. If the stated manufacturer s accuracy of any secondary standard is greater than 10% of the true or stated value, the standard cannot be used for a calibration check. 3.2.4.4. At least one of the standards must be greater than the highest expected sample concentration. The second standard must be near the expected concentration of the majority of the samples. 3.2.4.5. Each check must be within 10% of the true or manufacturer s stated value. 3.3. Sample Analysis (spectrophotometer or photometer): 3.3.1. Rinse the cuvette with a small amount of sample. 3.3.2. Discard the rinsing, and fill the cuvette with sample. 3.3.2.1. If samples are colored or turbid, compensate for these interferences by zeroing the meters with the sample before adding the chemicals for color development. 3.3.3. Add the reagents (DPD, buffer, etc.) to the sample according to the manufacturer s instructions. 3.3.4. Invert the container to mix. 3.3.5. Gently wipe the sides with a lint-free tissue and insert the cuvette into the instrument. 3.3.6. Follow the instrument s instructions for obtaining the sample value (either by direct read-out or by using a plot of the calibration curve). 3.3.7. After recording the sample reading, remove the cuvette, discard the sample and rinse the cuvette 3 5 times with de-ionized or distilled water. 3.3.8. Repeat steps 3.3.1 through 3.3.7 until all samples have been tested. 3.4. Color Wheel Comparator: Follow the manufacturer s instructions for obtaining the sample value from a color wheel when used for drinking water sample analysis. 4. PREVENTIVE MAINTENANCE: Refer to FT 1000, section 3. 5. RECORDS: See FT 1000, section 4 for additional details. 5.1. Calibration: Record all calibration information (initial and continuing) in the field notebook or on a form specifically designed for this purpose (e.g. FD 9000-8). This information must be recorded: 5.1.1. The calibration method (or SOP) and the type of standard(s) (including the concentrations) used. 5.1.2. Record each calibration check (initial, continuing or final) in the permanent field records (or calibration logs). At a minimum, these records must include: 5.1.2.1. Date, time and location (e.g., monitoring well MW-X; laboratory; etc.) of each calibration check; Page 3 of 20 Revision Date: January 1, 2002

5.1.2.2. Individual performing the check; 5.1.2.3. Results of each check, including the concentration/type of standard, expected reading, and the actual reading; 5.1.3. Whether the check met or failed acceptance criteria; 5.1.4. Readings associated with a failed check; and 5.1.5. Corrective actions associated with failed check (such as recalibration, removal from use, etc.). 5.1.6. Optionally, enter the meter name, model number, and identification number (if applicable). 5.2. Samples: Record the sample results on the appropriate field parameter sheets (e.g., Form FD 9000-7) or in a field notebook. For each sample record the following information: Project Name Date and time the measurement was collected Location of the sample (description, monitor well number, etc.) Analyte Name Reporting Units Sample Value Initials of the person taking the measurements 5.3. Reagent and Standards Documentation: Maintain documentation on calibration standards (e.g., permanganate, gel standards) and other reagents. FT 2011. 5.3.1. At a minimum, note the date of receipt, expiration dates (on the bottle label), and date of first use (on the standard container). 5.3.2. Follow expiration dates: If any standard or chemical is used after the expiration date, there must be documentation showing that the reagent is providing an acceptable response. SPECIFIC REQUIREMENTS FOR WASTEWATER FACILITIES USING SECONDARY STANDARDS NOTE: FT 2011 ONLY APPLIES TO DOMESTIC WATEWATER FACILITIES WITH A RESIDUAL CHLORINE REQUIREMENT EQUAL TO OR GREATER THAN 0.5 mg-cl/l. EPA 330.5 and SM 4500-Cl G require the use of chlorine or potassium permanganate solutions to calibrate the spectrophotometer. These must be prepared on a daily basis, and require skill in preparing the volumetric dilutions. Secondary standards, such as gel or dyes, are usually marketed in three dilutions, plus a blank. These can be used without additional preparation and are much easier to use and handle. The problem is that the low level standard does not have sufficient accuracy to be used if low-level chlorine measurements are required. Secondary standards may be used if a plant must meet basic level disinfection requirements and must maintain a residual chlorine level of at least 0.5 mg/l. Use secondary standards for daily calibration checks only if the procedures discussed below are Page 4 of 20 Revision Date: January 1, 2002

followed. Facilities having permit requirements with chlorine residual standards of less than 0.5 mg/l cannot use secondary standards, but must use a titration method if the permit limit is less than 0.2 mg/l or standardize the instrument using either chlorine or permanganate standards as discussed in FT 2010. These procedures are divided into two sections: Section 1 deals with the activities that are associated with the storage, and use of standards in the field. Section 2 deals with the procedures, tests and calibrations that must be performed by: A laboratory with certification for residual chlorine in water from the Florida Department of Health Environmental Laboratory Certification Program (DoH ELCP) or A certified operator holding an A or B wastewater operator's license in the State of Florida. 1. FIELD PROCEDURES 1.1. Calibration Verification: 1.1.1. Verify all new standard sets before first use (see section 1.3.2 below). 1.1.2. On each day of use check the instrument calibration: 1.1.2.1. Zero the meter using the blank provided by the manufacturer. 1.1.2.2. Read the mid-range standard as if it was a sample and record the reading. The standard must be within 10% of the stated manufacturer s value. 1.1.2.3. Read the high and low standards as if they were samples and record the readings. The values must be within the tolerances allowed by the manufacturer. 1.1.2.4. If the standards do not meet these criteria, the meter is not usable. Either recalibrate the meter or return to the manufacturer. In addition, re-verify the standards to ensure accuracy. DO NOT ATTEMPT to adjust the calibration. 1.1.2.5. Perform this calibration check at intervals of no greater than 24 hours. Perform an additional check at the end of the day, after the last sample measurement has been taken. 1.1.2.6. Unacceptable calibration checks during, or at the end of the day mean that the standards and/or the meter are no longer functioning properly. Do not use the standards and the meter until the standard concentrations have been re-verified and the working condition of the meter has been checked (see 1.1.2.4 above). All measurements taken between the last acceptable calibration check and the failed calibration check may not be accurate, and if reported, the letter J must follow each value. 1.1.3. At least once a week, check a blank, prepared with chlorine-free water and the DPD reagent after the meter has been checked as described above. This blank must read no more than 0.05 mg/l. If the blank is greater than 0.05 mg/l, discard the DPD reagent because it is no longer producing the expected result. 1.2. Required documentation for the daily calibration verification: 1.2.1. Lot number of standards. Page 5 of 20 Revision Date: January 1, 2002

1.2.2. Acceptance range for each of the standard concentrations. Example: if the mid standard is 0.7 mg/l, then calculate the acceptance range by taking 10% of 0.7 (0.07) and adding and subtracting the value from the original concentration. The acceptance range for a 0.7 mid-range standard would be 0.63 to 0.77 mg/l. 1.2.3. Values for the low, medium and high standards. 1.2.4. Indication of whether the standards meet the acceptance criteria. 1.2.5. Value for the water blank (see 1.1.3 above). 1.3. Care of Secondary Standards: Protect standards from direct sunlight, heat and scratches. 1.3.1. Store the standards in the upright position. The most convenient way is to keep the standards in the original storage box provided by the manufacturer. 1.3.2. During transport to and from the field, keep the standards in an air-conditioned vehicle away from the sun (not on the dashboard or in the trunk). 1.3.3. If the vehicle is not air conditioned, the standards may be placed in a watertight plastic bag and stored on ice or on a cold blue ice pack in a cooler. 1.3.3.1. When not in use, store the standards in an upright position in air conditioning or in ambient air not to exceed 90 o F. 1.3.3.2. Avoid getting fingerprints on the glass vial by handling the standards only by the plastic cap. 1.3.4. Before each day s use, inspect the secondary standard vials and clean the outside of the standard vials with a dilute solution of soapy water, followed by a tap water rinse. Wipe dry with lint-free paper or cloth. 1.3.5. Discard the standard set when: You notice scratches in the glass vial; You notice that a secondary standard has melted, and/or has melted and solidified in a different position from the original standards; and The standards have exceeded the manufacturer s expiration date. 1.4. Equipment and Standard Maintenance: 1.4.1. Instrument: At least once a quarter, perform the following maintenance tasks on the spectrophotometer/colorimeter. These tasks must be performed by a laboratory with DoH ELCP certification for residual chlorine or by a certified operator holding an A or B wastewater operator's license in the State of Florida. Request the following: 1.4.1.1. Check the instrument to ensure proper working condition including performing any maintenance tasks necessary to ensure proper operation. 1.4.1.2. Perform an initial calibration using primary (chlorine or permanganate) standards. 1.4.1.3. Issue a statement certifying that the instrument is in proper working condition, and has been calibrated using primary standards. The statement must bear the signature of the laboratory director (or certified A or B operator), the date that the instrument was calibrated, and the certification number of the laboratory (if performed by a laboratory). Page 6 of 20 Revision Date: January 1, 2002

1.4.2. Standards: Each of the standards in a set must be clearly identified as belonging to that set, and may not be mixed with standards from other sets. 1.4.2.1. On a monthly basis, check one of the two sets of standard standards against primary standards. These checks must be performed by a certified laboratory or a certified operator holding an A or B wastewater operator's license in the State of Florida. These tasks must be performed: 1.4.2.2. Check the secondary standards to ensure that: The standards have not expired; The standards have not been mishandled (e.g., stored so that the gel has melted into a different form); and The glass cuvettes are free from fingerprints or scratches. If the standards have exceeded the expiration date, gel standards appear to be deformed, the standards appear to be discolored, or the cuvettes are damaged, discard the standard set. 1.4.2.3. Check the accuracy of the secondary standards by: Testing each of the secondary standards with a properly calibrated spectrophotometer as if they were samples and record the value. The standard at the high end and low end must meet manufacturer specifications. The mid level standard (~ 0.78 mg/l) must be within 10% of the stated value to be acceptable. If any of the standards do not meet the stated criteria, the user must be notified that a new set of standards must be purchased. Standards that do not meet the calibration acceptance criteria must be discarded. 1.4.2.4. Issue a statement signed by the laboratory director (or certified A or B operator) certifying that: The standard cuvettes and standards are in acceptable condition; and Each individual standard meets the acceptance criteria in 1.3.2.3 above. The certificate must also report the manufacturer s value and the value obtained by the laboratory (or A or B operator), the date that the test was performed and if performed by a laboratory, the environmental certification number. 1.5. Retain all certificates (both instrument and standard calibration) from the laboratory (or operator) in a permanent file for a period of five years after they have been issued. 1.6. Records: Maintain the following records: 1.6.1. Daily Calibration Checks: 1.6.1.1. Date and time of calibration check. 1.6.1.2. The true value and the instrument value of each standard. 1.6.1.3. Lot number of calibration standards. Page 7 of 20 Revision Date: January 1, 2002

1.6.1.4. Acceptance range for each standard (may be listed when the standards are newly purchased). 1.6.2. Secondary Standard Records: 1.6.2.1. Date standards were originally received. 1.6.2.2. Expiration date of standards (per manufacturer). 1.6.2.3. Original certificate of tolerance provided by the manufacturer. 1.6.2.4. Dates standards were sent to the laboratory (or Class A or B operator) for certification. 1.6.2.5. The laboratory name and DoH certification number used for certification or the name of the Class A or B operator. 1.6.2.6. The laboratory (or operator) results and certification statement for each recertification. 1.6.3. Instrument Records: 1.6.3.1. Date instrument was originally received. 1.6.3.2. Dates instrument was sent to the laboratory (or Class A or B Operator) for certification. 1.6.3.3. The laboratory name and DoH certification number used for certification or the name of the Class A or B operator. 1.6.3.4. The laboratory (or operator) results and certification statement for each certification. 1.6.3.5. Preventative maintenance and repairs performed on the instrument. 1.7. Retain all records for a period of at least five (5) years from the date that the information was generated. 2. LABORATORY OR CLASS A AND B OPERATOR RESPONSIBILITIES: 2.1. When the spectrophotometer is received: 2.1.1. Check the instrument to ensure proper working condition; 2.1.2. Perform an initial calibration using primary (chlorine or permanganate) standards and make adjustments necessary to ensure that the instrument is properly calibrated. 2.1.3. If the initial calibration is acceptable (see FT 2010, section 3.2.3), issue a statement certifying that the instrument is in proper working condition, and has been calibrated using primary standards. The statement must bear the signature of the laboratory director (or A or B operator), the date that the instrument was calibrated, and the certification number of the laboratory (if performed by a laboratory). 2.2. On a monthly basis, one of the two sets of standards must be submitted to check against primary standards: 2.2.1. Check the standards to ensure that: 2.2.1.1. The standards have not expired; 2.2.1.2. The standards have not been mishandled (e.g., stored such that the gel has melted into a different form); and Page 8 of 20 Revision Date: January 1, 2002

2.2.1.3. The glass vials are free from fingerprints or scratches. 2.2.2. If the standards have exceeded the expiration date, gel standards appear to be deformed, the color is not correct, or the cuvettes are damaged, notify the user that a new set of standards must be purchased. 2.3. Check the accuracy of the secondary standards by testing each of the standards as if they were samples with a spectrophotometer calibrated according to the analytical method (i.e. permanganate or chlorine standards). The standard at the high and low end must meet manufacturer specifications. The mid-level standard (~ 0.78 mg/l) must be within 10% of the stated value to be acceptable. 2.3.1. If any of the standards do not meet the criteria in 2.3 above, notify the user that a new set of standards must be purchased. 2.4. Issue a certification signed by the laboratory director (or Certified A or B operator) that certifies that: 2.4.1. The standards (vials or cuvettes and the gel or dye) are in acceptable condition; and 2.4.2. Each individual standard meets the acceptance criteria in 2.3 above. 2.5. The certificate should also report the manufacturer s value and the value obtained by the laboratory, the date that the test was performed and the environmental certification number of the laboratory. 2.6. In addition to the analytical records associated with the secondary standards, laboratories (or A or B operators) must retain records on the initial calibration and maintenance that are performed on the meter and the clients to whom the instrument and standard calibration services are provided. 3. RECORDS 3.1. Record all calibrations (initial and continuing) in the field notebook or in a form specifically designed for this purpose. 3.2. Record field measurements in the appropriate field/lab parameter sheets (e.g., forms FD 9000-12, FD 9000-13 and FD 9000-14) or in the field notebook. FT 2020. TITRIMETRIC METHODS Residual chlorine can be measured using several different titrimetric methods. These methods take more time, require some skill in making chemical measurements, require several different reagents and must be done in the field. Unless the expected concentration levels are below the detectability of colorimeters, FDEP recommends using the DPD colorimetric method (FT 2010). If a titrimetric method must be used, select one of the following methods: EPA Methods 330.1, 330.2, 330.3, or 330.4, or SM 4500-Cl B, SM 4500-Cl C, SM 4500-Cl D, or SM 4500-Cl F. The following general discussions deal with using the titrimetric equipment only. 1. The volumetric glassware that is used to transfer and to titrate must be thoroughly clean. 1.1. Use class A pipets for transferring samples and reagents; use a class A buret for titration. 1.2. The volumetric pipets and the buret must be free flowing. This means that there cannot be any droplets remaining on the sides of the glassware when the liquid is dispensed. Page 9 of 20 Revision Date: January 1, 2002

1.3. Check the glassware before use by filling with de-ionized or distilled water and allowing to drain. Do not use the glassware if droplets appear. 1.4. Clean by using hot sudsy water, and a buret brush or soaking in sudsy water. 1.5. Rinse with tap water to remove the soap. 1.6. Rinse with de-ionized water and check for water droplets. 1.7. Additional cleaning with chromic acid, or alcoholic potassium hydroxide may be needed to remove stubborn oil or films. 2. Rinse all glassware with a small amount of the solution to be dispensed/titrated, and discard the rinse. 2.1. Carefully fill (or pipet) with the solution. 2.2. Read the volume from the bottom of the meniscus [figure ]. 2.3. After filling the buret, record the initial volume. 3. When performing the titration, add the titrant slowly. 3.1. Swirl the flask gently while adding the titrant. 3.2. As the solution comes closer the endpoint, the color change will last for a longer period of time. When this occurs, add the titrant dropwise and mix thoroughly between drops. 3.3. The reaction is complete when the color change is permanent. Take the reading on the buret at the completion of the titration and record the reading. 4. Titrate at least two aliquots of each sample. 5. Titrate at least one blank. 6. Record the preparation of all reagents in the field notebook or in a form specifically designed for this purpose. 7. For each sample and blank, record the volume of each sample, and the beginning and ending readings on the buret. FT 2030. SELECTIVE ION ELECTRODE METHODS 1. INTRODUCTION AND SCOPE: Adapted from the Orion Research Instruction Manual, Residual chlorine Electrode Model 97-70, 1997. This method may be used if a method detection limit study verifies that the method can achieve the desired permit limits. This is not recommended for on-site use. 2. EQUIPMENT AND SUPPLIES 2.1. Instrument 2.1.1. ph-millivolt meter capable of an expanded 0.1 mv reading. 2.1.2. Platinum-iodide combination electrode (recommended) or 2.1.3. A platinum and an iodide ion selective electrodes. 2.1.4. Magnetic Stirrer 2.2. Reagents and Standards Page 10 of 20 Revision Date: January 1, 2002

ph 4.0 Buffer Acetic acid Potassium Iodide Solution: Dissolve 42 g potassium iodide and 0.2 g sodium carbonate in 500 ml chlorine demand-free deionized/distilled water. Potassium iodate (Primary Standard 0.00281 N): Dissolve 0.1005 g potassium iodate (KIO 3 ) in chlorine demand-free deionized/distilled water. Dilute to 1000 ml. 2.3. Recordkeeping and Documentation Supplies: Field notebook (w/ waterproof paper is recommended) Field/Lab record forms (e.g., forms FD 9000-12, FD 9000-13 and FD 9000-14) Indelible pens 3. CALIBRATION AND USE 3.1. Standard Preparation: prepare standards by volumetrically pipetting 0.2, 1.0 and 5.0 ml pf the potassium iodate into 100 ml volumetric flasks. 3.1.1. Add 1 ml of the buffer and 1 ml potassium iodide solution to each. 3.1.2. Swirl and let stand for 2 minutes. 3.1.3. Bring to 100 ml, stopper and invert several times to mix. 3.1.4. Prepare a blank by adding all reagents except the potassium iodate to a 100 ml volumetric and bring the volume to 100 ml. 3.2. Initial Calibration: Follow Manufacturer s instructions on the use of the instrument. Use the three standards and the blank to calibrate. Plot the curve on semilogarithmic graph paper or enter values into a direct-reading ion meter. 3.3. Continuing Calibration: Use at least one of the standards to check the stability of the standard curve at the end of the analytical day. 3.4. Follow the quality control requirements for calibration (see FT 1000, section 2.2). 3.5. Sample Analysis: 3.5.1. Adjust the ph of the sample with acetic acid to 4 5 ph units. 3.5.2. Pipet 1 ml buffer and 1mL potassium iodide into a 100 ml volumetric flask. Swirl to mix and let stand for at least 2 minutes. 3.5.3. Bring to the volume to 100 ml with the ph-adjusted sample, stopper and invert several times to mix. 3.5.4. Follow manufacturer s instructions for the use of the instrument. 3.6. Calculations: 3.6.1. Read the mg chlorine/l (R) from the calibration curve: 3.6.1.1. mg chlorine/l = R X 100/mL sample used 4. PREVENTIVE MAINTENANCE: Refer to FT 1000, section 3. 5. RECORDS: See FT 1000, section 4 for additional details. Page 11 of 20 Revision Date: January 1, 2002

5.1. Calibration: Record all calibration information (initial and continuing) in the field notebook or on a form specifically designed for this purpose (e.g. FD 9000-8). This information must be recorded: 5.1.1. The calibration method (or SOP) and the type of standard(s) (including the concentrations) used. 5.1.2. Record each calibration check (initial, continuing or final) in the permanent field records (or calibration logs). At a minimum, these records must include: 5.1.2.1. Date, time and location (e.g., monitoring well MW-X; laboratory; etc.) of each calibration check; 5.1.2.2. Individual performing the check; 5.1.2.3. Results of each check, including the concentration/type of standard, expected reading, and the actual reading; 5.1.3. Whether the check met or failed acceptance criteria; 5.1.4. Readings associated with a failed check; and 5.1.5. Corrective actions associated with failed check (such as recalibration, removal from use, etc.). 5.1.6. Optionally, enter the meter name, model number, and identification number (if applicable). 5.2. Samples: Record the sample results on the appropriate field parameter sheets (e.g., Form FD 9000-7) or in a field notebook. For each sample record the following information: Project Name Date and time the measurement was collected Location of the sample (description, monitor well number, etc.) Analyte Name Reporting Units Sample Value Initials of the person taking the measurements 5.3. Reagent and Standards Documentation: Maintain documentation on calibration standards (e.g., [potassium iodate) and other reagents. FT 2040. 5.3.1. At a minimum, note the date of receipt, expiration dates (on the bottle label), and date of first use (on the standard container). 5.3.2. Follow expiration dates: If any standard or chemical is used after the expiration date, there must be documentation showing that the reagent is providing an acceptable response. USING THE METHOD OF STANDARD ADDITIONS TO VERIFY THE ABSENCE OF ANY RESIDUAL CHLORINE 1. INTRODUCTION AND SCOPE: In some cases, wastewater treatment plants may need to determine the complete absence of residual chlorine after dechlorination. Some metered Page 12 of 20 Revision Date: January 1, 2002

instruments may not have sufficient sensitivity to measure below 0.2-mg/L chlorine. This procedure was developed by Region 4 of the Environmental Protection Agency to be used to verify, but not report the absence of residual chlorine. 2. METHOD: Use any residual chlorine method. If a colorimetric method (FT 2010) is used, the spectrophotometer or colorimeter must be able to distinguish between 0.02 and 0.05 mg/l chlorine. To document the sensitivity, perform a method detection limit study to verify that the method detection limit is at least 0.02 mg/l. 3. PROCEDURE: 3.1. If used, calibrate the meter following FT 2010. Otherwise, use a titrimetric method (FT 2020). 3.2. Perform all tests within 15 minutes of collecting the samples. 3.3. Collect a grab sample at a point just before dechlorination or the effluent of the chlorine contact basin. This is sample A. 3.4. Collect a second grab sample after dechlorination. This should correspond to the final effluent monitoring point (sample B). 3.4.1. Sample A and Sample B must differ only by the dechlorination treatment. There cannot be any waste streams that enter the system between the two collection points. 3.5. Measure and pour equal volumes of Sample A and Sample B into a clean container that can be sealed. Use a container that leaves little or no headspace when filled. This is sample C. 3.5.1. Cap and gently invert the container (sample C) several times to mix the contents. Do not shake vigorously. 3.6. Measure the total residual chlorine in samples A and C. 3.7. Calculate the concentration in sample B: Residual Chlorine in B (mg/l) = [C*2] A 3.8. The absence of residual chlorine is verified if the residual chlorine in B is less than or equal to ½ A*1.10. Refer to figure FT 2000-1 for illustrative examples. 3.9. If the value results in a negative number and a sulfite salt (e.g., sodium bisulfite, sodium metabisulfite) was used to dechlorinate the effluent, less dechlorination agent can be added. FT 2050. REFERENCES 1. U.S. Environmental Protection Agency, EPA 330.1, Methods for the Chemical Analysis of Water and Waste, EPA-600/4-79-020, Revised 1983. 2. U.S. Environmental Protection Agency, EPA 330.2, Methods for the Chemical Analysis of Water and Waste, EPA-600/4-79-020, Revised 1983. 3. U.S. Environmental Protection Agency, EPA 330.3, Methods for the Chemical Analysis of Water and Waste, EPA-600/4-79-020, Revised 1983. 4. U.S. Environmental Protection Agency, EPA 330.4, Methods for the Chemical Analysis of Water and Waste, EPA-600/4-79-020, Revised 1983. Page 13 of 20 Revision Date: January 1, 2002

5. U.S. Environmental Protection Agency, EPA 330.5, Methods for the Chemical Analysis of Water and Waste, EPA-600/4-79-020, Revised 1983. 6. American Public Health Association, American Water Works Association, Water Pollution Control Federation, SM 4500-Cl B, Standard Methods for the Examination of Water and Wastewater, 20 th Edition, 1999. 7. American Public Health Association, American Water Works Association, Water Pollution Control Federation, SM 4500-Cl C, Standard Methods for the Examination of Water and Wastewater, 20 th Edition, 1999. 8. American Public Health Association, American Water Works Association, Water Pollution Control Federation, SM 4500-Cl D, Standard Methods for the Examination of Water and Wastewater, 20 th Edition, 1999. 9. American Public Health Association, American Water Works Association, Water Pollution Control Federation, SM 4500-Cl F Standard Methods for the Examination of Water and Wastewater, 20 th Edition, 1999. 10. Florida Department of Environmental Protection Environmental Assessment Section, The Use of Secondary Gel Standards for Residual Chlorine Calibration, DEP-QAS-99-02, September 22, 1999. 11. U.S. Environmental Protection Agency, Region 4, Monitoring Chlorine and Sulfur Dioxide at Wastewater Treatment Plants, undated Paper. 12. Thermo-Orion, Orion Research Instruction Manual, Residual Chlorine Electrode Model 97-70, 1997. Page 14 of 20 Revision Date: January 1, 2002

Appendix FT 2000 Tables, Figures and Forms Figure FT 2000-1 Scenario for Total Chlorine Analysis Form FD 9000-12 Maintenance and Calibration Log for Residual Cl Spectrophotometer Form FD 9000-13 Field Calibration Check Log for Residual Cl Spectrophotometer Form FD 9000-14 Residual Cl Secondary Standard Calibration Log Page 15 of 20 Revision Date: January 1, 2002

Figure FT 2000-1 SCENARIO FOR TOTAL CHLORINE ANALYSIS (TRC) SO 2 DECHLORINATION FINAL DISCHARGE CHLORINE CONTACT BASIN * TRC = 0.5 MG/L * TRC =0.0 MG/L * Sample A Sample B A = Grab sample collected just prior to dechlorination. Sample C = TRC = 0.25 MG/L B = Grab sample collected downstream of dechlorination at final discharge point. C = Equal volumes of A & B mixed without aeration and the expectant TRC concentration mg/l = A + B = 0.5 + 0.0 = 0.25 2 2 If 1/2 A = C, then the TRC at Sample B = <0.01 or the MDL value determined on the instrument whichever was greater. If 1/2 A > C, then excess SO 2 was added. The TRC concentration would be <0.25 mg/l at Sample C and the TRC for Sample B = 0.0 mg/l and would be reported as a < value. If C > 1/2 A, then Sample B would have TRC present in final effluent. To calculate the Sample B value: [C * 2] - A = TRC concentration. Example: If the TRC concentration of C = 0.27 and A = 0.5, then 0.27 * 2 = 0.54, and the TRC at Sample B = [0.54-0.50] = 0.04 mg/l. Page 16 of 20 Revision Date: January 1, 2002

Page of Maintenance and Calibration Log for Residual Chlorine Spectrophotometer FACILITY NAME: INSTRUMENT MAKER: INSTRUMENT MODEL #: DATE RECEIVED (YY/MM/DD) BY FDEP PERMIT #: DATE PURCHASED: SERIAL NUMBER: CALIBRATED BY (LABORATORY / OPERATOR NAME) DOH CERT # ACCEPTABLE CONDITION? YES NO NOTE: IN ADDITION TO THIS LOG, THE FOLLOWING DOCUMENTS MUST ALSO BE RETAINED BY THE FACILITY: THE LABORATORY CERTIFICATION STATEMENTS, AND THE MANUFACTURER S MANUAL AND WARRANTIES. Page 17 of 20 Form FD 9000-12 (June 1, 2001) Revision Date: January 1, 2002

ENTER ALL MAINTENANCE AND REPAIR ACTIVITIES ON THIS PAGE Page of DATE NAME/SIGNATURE DESCRIPTION OF ACTIVITY Page 18 of 20 Form FD 9000-12 (June 1, 2001) Revision Date: January 1, 2002

Field Calibration Check Log for Residual Cl Spectrophotometer Page of CALIBRATION CHECKS MUST BE PERFORMED AT THE BEGINNING OF EACH WORKING DAY AND AT FOUR- HOUR INTERVALS THEREAFTER. A FINAL CALIBRATION CHECK MUST BE PERFORMED AFTER THE LAST MEASUREMENT HAS BEEN MADE IN THE DAY OF USE. DATE YY/MM/DD TIME HR:MIN OPERATOR SIGNATURE LOT # OF STANDARDS TRUE VALUE (MG/L) METER VALUE (MG/L) ACCEPTANCE RANGE ACCEPTABLE? YES NO Page 19 of 20 Form FD 9000-13 (June 1, 2001) Revision Date: January 1, 2002

Residual Cl Secondary Standard Calibration Log Page of A DOH-CERTIFIED LABORATORY (OR A CERTIFIED A OR B OPERATOR) MUST, ON A MONTHLY BASIS, CHECK SECONDARY STANDARDS. COMPLETE ONE PAGE OF THIS LOG FOR EACH SET OF STANDARDS. RETAIN THE MANUFACTURER S CERTIFICATIONS AND REPORTS FROM THE LABORATORY (OR A OR B OPERATOR) ON THE RESULTS OF THE STANDARD CHECKS. VENDOR: LOT #: PURCHASE DATE: EXPIRATION DATE: DATE CHECKED YY/MM/DD CHECKED BY (LABORATORY NAME OR A OR B OPERATOR) DOH ACCEPTABLE? CERTIFICATION NUMBER YES NO INITIALS Page 20 of 20 Form FD 9000-14 (June 1, 2001) Revision Date: January 1, 2002