AWWA 1943-2016 Water Distribution Grades 1 & 2.pdf

1、 #MBOL1BHFGrades 1 therefore, all laboratory analyses must be performed by experienced technicians under carefully controlled conditions. For this reason, compliance sample analyses are acceptable to the state only if they have been performed by a certifi ed laboratory. The only exceptions are measu

2、rements for turbidity, chlorine residual, tempera-ture, and pH, which may be performed by a person acceptable to the state, using approved equipment and methods.Most states operate certifi ed laboratories that can accept some or all of the samples from water systems. The states also certify private

3、laboratories that may be used for performing water analyses. Most large water utilities have their own certifi ed laboratories because of the great number of samples that must be processed.Consumer Confi dence ReportsOne of the very signifi cant provisions of the 1996 SDWA Amendments is the consumer

4、 confi dence report (CCR) requirement. The purpose of the CCR is to provide all water customers with basic facts regarding their drinking water so that individuals can make decisions about water consumption based on their personal health. This directive has been likened to the requirement that packa

5、ged food companies disclose what is in their food products.The reports must be prepared yearly by every community water system. Water systems serving more than 10,000 people must mail the report to customers. Smaller systems must notify customers as directed by the state primacy agency.A water syste

6、m that distributes only purchased water (satellite system) must prepare the report for their consumers. Information on the source water and chemical analyses must be provided to the satellite system by the system selling the water (parent system).USEPA Drinking Water Regulations 9Some states are pre

7、paring much of the information for their water systems, but the system operator must still add local information. Water system operators should keep in mind that CCRs provide an opportunity to educate consumers about the sources and quality of their drinking water. Educated consumers are more likely

8、 to help protect drinking water sources and be more understanding of the need to upgrade the water system to make their drinking water safe.USEPA Regulation InformationCurrent information on USEPA regulations can be obtained by contacting the Safe Drinking Water Hotline at 800-426-4791. Also see the

9、 Office of Ground Water and Drinking Water webpage at http:/water.epa.gov/drink.State RegulationsUnder the provisions of primacy delegation, each state must have requirements applying to public water systems that are at least as stringent as those set by USEPA. States occasionally establish requirem

10、ents that are more stringent. Fed-eral requirements are only for factors that USEPA considers directly related to public health. So, in addition to the federal requirements, each state establishes other requirements to ensure proper water system operation.Operator CertificationOne requirement of the

11、 1996 SDWA Amendments is that USEPA must establish minimum standards for state operator certification programs. Most states have had some form of certification for water system operators, but, unfortunately, each state has its own idea of how operators should be classified, so there has been little

12、national consistency.Among the more important requirements are that each water system must at all times be under the direct supervision of a certified operator, operators must have a high school or equivalent education and pass an examination to receive certification, and the state must establish tr

13、aining requirements for certification renewal. Most states have a separate certification class for distribution system operators.Cross-Connection ControlThe states also generally promote cross- connection control programs for all water systems. Many states have their own cross- connection control ma

14、nuals and assist water systems in setting up local programs. Cross- connection control is covered in detail in Chapter 19.Construction ApprovalThe SDWA requires states to review plans for water system construction and improvements. In general, plans and specifications for the proposed work must be p

15、repared by a professional engineer and submitted for approval before work begins. State engineers review the plans for suitability of materials, conformance with state regulations, and other factors.Some states allow small distribution system additions without approval or allow approval after constr

16、uction. State regulations should be reviewed to ensure compliance with requirements.10 WSO Water Distribution, Grades 1 haloacetic acids (HAA5)0.060 mg/L; and two inorganic DBPschlorite (1.0 mg/L) and bromate (0.010 mg/L)H18546 A treatment technique for removal of DBP precursor material (enhanced co

17、agulation)USEPA Drinking Water Regulations 13Stage 2 Disinfectants and Disinfection By- products Rule (Stage 2 DBPR)The rule tightened requirements for DBPs, but compliance is not achieved by modifying the numerical value of the MCLs or by requiring monitoring of new constituents. Instead, the rule

18、makes compliance more difficult than under the Stage 1 DBPR by (1) changing the way the compliance value is calculated and (2) changing the compliance monitoring locations to sites representative of the greatest potential for THM and HAA formation. These changes were incorpo-rated to attempt to acco

19、unt for peak spatial occurrence in the system. This change in focus reflects concerns of utilities and regulators caused by the potential for reproductive and developmental health effects associated with repeated exposure over a 12-month period at peak locations within the system.The compliance valu

20、e in the Stage 2 DBPR is called the locational running annual average (LRAA), and it is calculated by separately averaging the four quarterly samples at each monitoring location. Compliance is based on the max-imum LRAA value (see Table 1-1). Furthermore, the Stage 2 DBPR includes sev-eral interim s

21、teps that led to the replacement of many existing Stage 1 DBPR monitoring locations with new locations representative of the greatest potential for consumer exposure to high levels of TTHM and HAA5.The Stage 2 DBPR requires that facilities maintain compliance with the Stage 1 DBPR using the existing

22、 monitoring locations during the first three years after the final version of the Stage 2 DBPR was published. In the time period between the third and sixth year after the Stage 2 DBPR was published, compliance con-tinued to be based on maintaining 80/60 (TTHM and HAA5) or lower for the running annu

23、al average; it also included a requirement for maximum LRAA at existing Stage 1 monitoring locations. These time periods during the Stage 2 DBPR transition were called “Stage 2A” and “Stage 2B.”The long- term goal of the Stage 2 DBPR is to identify locations within the distribution system with the g

24、reatest potential for either TTHM or HAA5 forma-tion and then base compliance on maintenance of LRAA at or below 80/60 for each of these locations. Many of these locations were identified during the initial distribution system evaluation (IDSE). Consequently, the IDSE and the Stage 2A were actually

25、just transition phases between the Stage 1 DBPR and the eventual long- term requirements of Stage 2B.The IDSE included monitoring, modeling, and/or other evaluations of drink-ing water distribution systems to identify locations representative of the greatest potential for consumer exposure to high l

26、evels of TTHM and HAA5. The goal of the IDSE was to evaluate a number of potential monitoring locations to justify selection of monitoring locations for long- term compliance (i.e., Stage 2B) with the Stage 2 DBPR.One item to note regarding the Stage 2 DBPR as it applies to TTHM and HAA5 is that the

27、 goal is to find the locations in the distribution system where average annual levels of these DBPs are highest. TTHM formation increases as contact time with free or combined chlorine increases, although formation in the presence of combined chlorine is limited. Therefore, establishing points in th

28、e dis-tribution system with highest potential for TTHM formation is related to points with maximum water age. Utilities that have not performed a tracer study in the distribution system to determine water age should consider doing so.By contrast, peak locations for HAA5 are more complicated because

29、micro-organisms in biofilm attached to distribution system pipe surfaces can biode-grade HAA5. Consequently, increasing formation of HAA5 over time is offset 14 WSO Water Distribution, Grades 1 check with your local regulatory agency for additional clarifications.After identifying sampling locations

30、 and determining initial tap water lead and copper levels at each of these locations, utilities must also monitor other water quality parameters (WQPs) at these same locations as needed to moni-tor and evaluate corrosion control characteristics of treated water. The only USEPA Drinking Water Regulat

31、ions 17exemptions from analysis of these WQPs are systems serving less than 50,000 people for which lead and copper levels in initial samples are below action levels. Lead, copper, and WQPs are initially collected at 6-month intervals, and then this frequency can be reduced if action levels are not

32、exceeded and optimal water treatment is maintained. Systems that are in noncompliance and are performing additional corrosion- control activities must continue to monitor at 6-month inter-vals, plus they must collect WQPs from distribution system entry points every 2 weeks.Each utility must complete

33、 a survey and evaluate materials that comprise their distribution system, in addition to using other available information, to target homes that are at high risk for lead or copper contamination.Revisions to the LCR were enacted in 2007. These clarifications to the exist-ing rule were made in seven

34、areas:1. Minimum number of samples required2. Definitions for compliance and monitoring periods3. Reduced monitoring criteria4. Consumer notice of lead tap water monitoring results (Within 30 days of learning the results, all systems must provide individual lead tap results to people who receive wat

35、er from sites that were sampled, regardless of whether the results exceed the lead action level.)5. Advanced notification and approval of long- term treatment changes6. Public education requirements (Community water systems must deliver materials to bill- paying customers and post lead information o

36、n water bills, work in concert with local health agencies to reach at- risk popula-tions children, pregnant woman, deliver to other organizations serving “at-risk” populations, provide press releases, and include new outreach activities.)7. Reevaluation of lead service lines (A sample is required fr

37、om any lead ser-vice lines not completely replaced to determine impact on lead levels.)The local regulatory agency can be consulted for those revisions that are applica-ble to a particular system.Ground Water Rule (GWR)USEPA promulgated the final GWR in October 2006 to reduce the risk of expo-sure t

38、o fecal contamination that may be present in public water systems that use groundwater sources.The GWR establishes a risk- targeted strategy to identify groundwater systems that are at high risk for fecal contamination. The rule also specifies when correc-tive action (which may include disinfection)

39、 is required to protect consumers who receive water from groundwater systems from bacteria and viruses.A sanitary survey is required, by the state primacy agency, at regular intervals depending on the condition of the water system as determined in the initial sur-vey. Systems found to be at high ris

40、k for fecal contamination are required to pro-vide 4-log inactivation of viruses. Increased monitoring for fecal contamination indicators may be required by the regulatory authority. Federal regulations do not currently require disinfection of groundwater unless the well has been designated by the s

41、tate as vulnerable to contamination by surface water (termed “ground-water under the direct influence of surface water”). These are generally relatively shallow wells. Many states, though, have their own requirements for required disinfection of various sizes, types, or classes of well systems.18 WS

42、O Water Distribution, Grades 1 & 2National Secondary Drinking Water RegulationsA National Secondary Drinking Water Regulation is a nonenforceable guide-line regarding contaminants that may cause aesthetic effects such as taste, odor, and color. Some states choose to adopt them as enforceable standar

43、ds. Table 1-3 lists the secondary MCLs, and Table 1-4 lists the adverse effects of secondary contaminants.Table 1-3 National Secondary Drinking Water RegulationsContaminant Secondary StandardAluminum 0.050.2 mg/LChloride 250 mg/LColor 15 color unitsCopper 1.0 mg/LCorrosivity NoncorrosiveFluoride 2.0

44、 mg/LFoaming agents 0.5 mg/LIron 0.3 mg/LManganese 0.05 mg/LOdor 3 threshold odor numberpH 6.58.5Silver 0.10 mg/LSulfate 250 mg/LTotal dissolved solids 500 mg/LZinc 5 mg/LNote: For more information, read Secondary Drinking Water Regulations: Guidance for Nuisance Chemicals.Table 1-4 Adverse Effects

45、of Secondary ContaminantsContaminant Adverse EffectChloride Causes tasteAdds to total dissolved solids and scaleIndicates contaminationCan accelerate the corrosion of some metalsColor Indicates dissolved organics may be present, which may lead to trihalomethane formationUnappealing appearanceCopper

46、Undesirable metallic tasteCorrosivity Corrosion products unappealing to consumers. Corrosion causes tastes and odors. Corrosion products can affect health. Corrosion causes costly deterioration of water system.Fluoride Dental fluorosis (mottling or discoloration of teeth)Foaming agents Unappealing appearanceIndicates possible contamination