Total Organic Carbon (TOC) Guidance Manual

3m ago
20 Views
0 Downloads
845.40 KB
84 Pages
Transcription

September 2002RG-379 (Revised)Total Organic Carbon (TOC)Guidance ManualW ater Supply Divisionprinted onrecycled paperTEXAS COMMISSION ON ENVIRONMENTAL QUALITY

Total Organic Carbon (TOC)Guidance ManualPrepared byWater Supply DivisionRG-379 (Revised)September 2002

Robert J. Huston, ChairmanR. B. “Ralph” Marquez, CommissionerKathleen Hartnett White, CommissionerJeffrey A. Saitas, Executive DirectorAuthorization to use or reproduce any original material contained in thispublication—that is, not obtained from other sources—is freely granted. Thecommission would appreciate acknowledgment.Copies of this publication are available for public use through the TexasState Library, other state depository libraries, and the TCEQ Library, in compliance with state depository law. For more information on TCEQ publications call512/239-0028 or visit our Web site at:www.tceq.state.tx.us/publicationsPublished and distributedby theTexas Commission on Environmental QualityPO Box 13087Austin TX 78711-3087The Texas Commission on Environmental Quality was formerly calledthe Texas Natural Resource Conservation Commission.The TCEQ is an equal opportunity/affirmative action employer. The agency does not allow discrimination on the basisof race, color, religion, national origin, sex, disability, age, sexual orientation or veteran status. In compliance with theAmericans with Disabilities Act, this document may be requested in alternate formats by contacting the TCEQ at512/239-0028, Fax 239-4488, or 1-800-RELAY-TX (TDD), or by writing P.O. Box 13087, Austin, TX 78711-3087.

Contents1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Applicability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Monitoring Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Monitoring Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Compliance Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76Step 1 TOC Removal Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87Step 2 Alternative TOC Removal Requirement . . . . . . . . . . . . . . . . . . . . . . . . 97.1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97.2Frequency of Step 2 Jar Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107.3Step 2 Jar Test Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118Alternative Compliance Criteria (ACCs or “Outs”) . . . . . . . . . . . . . . . . . . . . 288.1ACC 1: Raw Water TOC 2.0 mg/L . . . . . . . . . . . . . . . . . . . . . . . . . . . 298.2ACC 2: Treated Water TOC 2.0 mg/L . . . . . . . . . . . . . . . . . . . . . . . . . 298.3ACC 3: Raw Water TOC 4.0 mg/L; and Raw Alkalinity 60 mg/L(as CaCO3); and TTHM 40 µg/L; HAA5 30 µg/L . . . . . . . . . . . . . . 298.4ACC 4: TTHM 40 µg/L and HAA5 30 µg/L, Chlorine Only . . . . . . 308.5ACC 5: Raw Water SUVA 2.0 L/mg-m . . . . . . . . . . . . . . . . . . . . . . . . 308.6ACC 6: Treated Water SUVA 2.0 L/mg-m . . . . . . . . . . . . . . . . . . . . . 318.7ACC 7: Treated Water Alkalinity 60 mg/L (as CaCO3)(Softening Systems) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318.8ACC 8: Magnesium Removal 10 mg/L (as CaCO3)(Softening Systems) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329Compliance Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3310Public Notification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3511Laboratory Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3611.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3611.2 Analytical Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37iii

AppendicesAppendix 1:Appendix 2:Appendix 3:Appendix 4:Appendix 5:Appendix 6:Appendix 7:Appendix 8:Appendix 9:Total Organic Carbon Monthly Operating Reports . . . . . . . . . . 45Side Effects (for Alum or Ferric Coagulation) . . . . . . . . . . . . . . 51Calculating Chemical Feed Rates . . . . . . . . . . . . . . . . . . . . . . . . 55Process Control Jar Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Unregulated Disinfection By-Products . . . . . . . . . . . . . . . . . . . . 65Acronyms and Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67Formulas and Conversions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73Lab Approval Form and Instructions . . . . . . . . . . . . . . . . . . . . . . 74Densities and Equivalent Weights of Commercial Alum . . . . . . 79List of FiguresFigure 3-1:Figure 5-1:Figure 7-1:Figure 7-2:Figure 7-3:Figure A2-1:TOC Sample Set Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Compliance Determination Flowchart . . . . . . . . . . . . . . . . . . . . . . 7Example of PODR Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Example of PODR Determination (When PODR Occurs Twice) 26Water “Not Amenable to Treatment” . . . . . . . . . . . . . . . . . . . . . . 27Example of Increased Turbidity with Enhanced Coagulation . . . 52List of TablesTable 6-1:Table 7-1:Table 7-2:Table 7-3:Table 7-4:Table 7-5:Table 7-6:Table 8-1:Table 11-1:Table 11-2:Table A2-1:Table A5-1:Table A5-2:Step 1 Matrix of Required TOC Removal Percentage . . . . . . . . . . . 8Example of PODR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Coagulant Dosage Equivalents . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Step 2 Target pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Step 2 Jar Test Procedure Summary . . . . . . . . . . . . . . . . . . . . . . . . 12Step 2 Dosing Solution Recipes for Dry Chemical . . . . . . . . . . . . 14Example of Step 2 Jar Test Data Sheet . . . . . . . . . . . . . . . . . . . . . 22Summary of Alternative Compliance Criteria (ACCs or ‘Outs’) . . 28Analytical Methods for Demonstration of Compliance . . . . . . . . . 36Necessary Analytical Methods for TOC Compliance Strategies . . 37Additional Sludge Production Equations . . . . . . . . . . . . . . . . . . . . 52Impact of Changing Disinfection Strategy on DBPs . . . . . . . . . . . 65Health-Based Values for Unregulated Disinfection By-Products . 66List of ExamplesExample 4-1: Determining Raw Water TOC for a Blended Source . . . . . . . . . . . 6Example 6-1: Step 1 Removal Requirement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Example 7-1: Converting from Percent to Grams Per Liter . . . . . . . . . . . . . . . . 16Example 7-2: Preparing a 20 g/L Dosing Solution . . . . . . . . . . . . . . . . . . . . . . . 17Example 7-3: Determining Number of Jars for Water 60 Alkalinity . . . . . . . . 19Example 7-4: Determining Number of Jars for Water 60 Alkalinity . . . . . . . . 21Example 7-5: Determining the PODR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25iv

1 IntroductionTOC removal is required for certain plants under the Stage 1 Disinfectants andDisinfection By-Products Rule (DBP1R). The Texas regulations relating to TOCremoval are contained in Title 30, Texas Administrative Code (30 TAC), Chapter290, Subchapter F, Section 290.112. The TOC requirements apply only to plantsthat treat surface water or groundwater under the direct influence of surface water(GUI) using coagulation and sedimentation for treatment.Disinfection is a crucial way to protect the public from pathogens. Unfortunately,at the same time that disinfectants are inactivating pathogens, they are alsoreacting with naturally occurring disinfection by-product precursors (DBP-Ps) toform disinfection by-products (DBPs). Some of the DBPs, such astrihalomethanes (THMs), are a health concern. Total organic carbon (TOC) isused as a surrogate measurement for DBP-Ps. The treatment technique forremoval of TOC lessens the concentration of DBP-Ps available to form DBPsduring disinfection.If you are a treatment plant operator, you will find clear, easy-to-readguidance on how to comply with the TOC rules in this manual. If you havequestions, call the TCEQ Public Drinking Water Section (Drinking Water QualityTeam) at 512/239-4691.The material presented here is adapted from the EPA’s Enhanced Coagulationand Precipitative Softening Guidance Manual. The EPA publication number forthis guidance manual is EPA 815-R-99-012. The EPA guidance document isavailable from the EPA Safe Drinking Water Hotline: 1-800-426-4791. The EPAOffice of Groundwater and Drinking Water (OGDW) Web site is:www.epa.gov/OGWDWThe wording in this manual has been changed from the EPA’s to make it morereadable, but the requirements are intended to be identical with EPA’s. Thismanual is available from TCEQ Publications, 512/239-0028. TCEQ publicationscan also be requested on the Web. Go to the TCEQ Web site and click on“Publications” at:www.tceq.state.tx.usThe TCEQ Web site also has a great deal of other information on public drinkingwater and links to the 30 TAC Chapter 290 rules for public water systems.Page 1 of 79

2 ApplicabilityAll surface water treatment plants that use conventional treatment must complywith the TOC requirements. Conventional systems are those that use coagulation,flocculation, sedimentation, and filtration to treat the water. Each treatment plantmust meet the TOC requirements. The requirements include monthly monitoring,monthly reporting, and quarterly compliance determinations. You can find theexact rule language and applicability requirements in Title 30 of the TexasAdministrative Code (30 TAC), Chapter 290, Subchapter F: Drinking WaterQuality and Reporting Requirements for Public Water Supply Systems. The TOCrequirements are located in Section 290.112(a).Two ways to find the TOC rule follow:!See Drinking Water Standards Governing Drinking Water Quality andReporting Requirements for Public Water Systems. Go towww.tceq.state.tx.us, click on “Publications,” and enter the publicationnumber (RG-346) to print a copy. This publication covers therequirements for harmful or potentially harmful constituents for watersystems that supply potable water to the citizens of Texas.!Go to the Secretary of State’s Web site to view the rules online. There is alink from the TCEQ Web site when you click on “Rules” and then use thelinks to view the rules online.Each system must do its own sampling and report the results to the TCEQ eachmonth. The Total Organic Carbon Monthly Operating Report (TOC-MOR)reporting forms are shown in Appendix 1 of this document. There, you will alsofind instructions on when and where to send the reports. After the TCEQ receivesthe reports, we will determine if the plant has met the monitoring, reporting, andtreatment technique requirements.Systems serving 10,000 people or more must start monitoring in January 2001 andcompliance will be calculated starting in January 2002. Data collected during2001 will not be used for compliance. Systems serving less than 10,000 peoplemust start monitoring in January 2003. Compliance for these smaller systems willbe calculated starting in January 2004. Data collected by small systems during2003 will not be used for compliance.Page 2 of 79

3 Monitoring LocationsFigure 3-1: TOC Sample Set LocationsRaw water TOC and treated water TOC mustbe monitored at locations that comply with TOCmonitoring requirements established in 30 TACSection 290.112(c). This page describesacceptable locations.Raw Water Sampling LocationRaw water must be sampled before anychemicals are added. Raw water TOC andalkalinity samples should be taken at the samelocation.The samples may be taken from the lake, fromthe raw water pump station, from an influenttrough or head tank before the rapid mix, or anyplace that accurately represents raw waterquality before chemical addition.Any of the locations labeled (1) in Figure 3-1are okay for taking raw water samples.Treated Water Sampling LocationTreated water samples for TOC analysis must betaken after sedimentation, but may be taken afterfiltration. Any sampling point after the effluentof the sedimentation basin up to the point ofcombined effluent filter turbidity sampling isacceptable. (From a regulatory standpoint, itdoes not matter where the treated water samplepoint is in relation to any in-plant chemicalinjection points.)Any of the locations labeled (2) in Figure 3-1are okay for taking treated water samples.Note on Monitoring Plan: The raw- and treatedwater sampling points must be shown on theplant schematic in the system’s monitoring plan.Page 3 of 79

4 Monitoring FrequencyEvery plant must sample the raw water TOC, the raw water alkalinity, and thetreated water TOC at least once a month. This group of samples is called a TOCsample set. The results of the TOC sample set are used to calculate the percent ofthe TOC in the raw water that is removed by sedimentation, known as the actualpercent TOC removal. You can find the exact rule language for the TOCmonitoring requirements in 30 TAC Section 290.112(b).A plant is required to do at least one TOC sample set every month. If samplesmust be sent to a lab, you should consider how long it takes to get samples backfrom the lab when scheduling sample collection. For instance, if it takes the labthree weeks to return sample results, you should probably sample early in themonth, so the results will be back in time to fill out the TOC-MOR.A plant may choose to do more than one TOC sample set in a month. If youchoose to, you may take more than one TOC sample set in a month; the