Surface Water Treatment Rule

1. Surface Water Treatment Rule Bob Clement Drinking Water Program U.S. EPA Region 8

2. Surface Water Treatment RuleGround Water Reclassification PWS TYPE:STATE DETERMINATION BY: CWS 6/29/94 NCWS 6/29/99 40 CFR 142.16 (b)(2)(B) _______________________________________________________________________________ DETERMINATIONACTION Direct influence Meet avoidance criteria within of surface water 18 months or Install filtration within 18 months 40 CFR 141.71

3. Surface Water Treatment RuleGeneral Requirements • All surface water systems must disinfect(40 CFR 141.70 (a)) • Minimum 99.9 / 99.99% removal or inactivation of Giardia cysts / viruses(40 CFR 141.70(a)(1 & 2)) • System operated by qualified personnel(40 CFR 141.70(c)) • Treatment specified by primary agency (source water quality, site specific factors)(40 CFR141.70(a))

4. Surface Water Treatment RuleGeneral Requirements • Applies to surface supplies and groundwater supplies under the influence of surface water • Regulates for Giardia, viruses, Legionella, heterotrophic bacteria, and turbidity

5. Cryptosporidium Cryptosporidium can survive for months in soil under cool, dark conditions and for up to a year in low turbidity water. (Badenoch et al., 1990) Cryptosporidium is ubitquitous. It is found even in the most pristine watersheds.

6. Cryptosporidium In almost all cases, wherever Giardia was present, Cryptosporidium was also present. (LeChevallier et al., 1991a) We simply did not look for both at the same time in previous studies. The highest level at a single site was 484 oocysts/L in Missouri.

7. Cryptosporidium • It would take up to 29,000 mg/l of CL2 to inactivate crypto. • Traditional chlorination doesn’t work. Physical removal by treatment is the only method of reduction for crypto.

8. Cryptosporidium In an immuno-compromised individual, cryptosporidium can cause a debilitating condition and may be fatal.

9. Surface Water Treatment Benefits • 90,000 illnesses per year avoided • Waterborne disease outbreaks avoided • Improved consumer confidence, more aesthetic water • Removal of precursors to disinfection by-products • Removal of inorganic and synthetic organic chemicals

10. Turbidity Monitoring RequirementsFiltered Systems • One measurement every 4 hours of operation by grab sample, or continuous monitoring • States may reduce monitoring to one grab sample / day in systems < 501 people regardless of treatment technology • Slow sand filtration and other technologies • State may reduce monitoring to one grab sample / day regardless of population size (40 CFR 141.74(c)(1))

11. Turbidity Performance RequirementsFiltered Systems • All systems - never exceed 5 NTU (40 CFR 141.73) • Conventional treatment, direct filtration: < 0.5 NTU 95% of measurements (State may allow up to < 1 NTU 95% of measurements) (40 CFR 141.73(a)) • Diatomaceous earth filtration - < 1 NTU 95% of measurements(40 CFR 141.73 (c))

12. Turbidity Performance RequirementsFiltered Systems • Slow sand and other filtration technologies < 1 NTU 95% of measurements (State may allow up to < 5 NTU 95% of measurements but cannot exceed 5 NTU) (40 CFR 141.73 (b) and (d))

13. Turbidity Standards • Systems using a technology other than conventional, direct, slow sand or diatomaceous earth filtration are in compliance if: system demonstrates to the State that alternative filtration technology in combination with disinfection … (40 CFR 141.73(d))

14. Turbidity Standards • … alternative filtration technology in combination with disinfection consistently achieves removal and/or inactivation of: • 99.9% of Giardia lamblia cysts (filtration + disinfection) • 99.99% of viruses (filtration + disinfection) • 99% of Cryptosporidium (filtration alone) (Interim Enhanced SWTR 12/16/98)

15. Disinfection Requirements for Filtered Systems • Entry point to distribution system 40 CFR 141.74(c)(2) • Distribution system 40 CFR 141.74(c)(3) • Filtration and disinfection achieves at least 3/4 Log removal / inactivation (State determination) 141.70 (a)(1&2)

16. Disinfection RequirementsEntry Point to Distribution System • Residual entering distribution system cannot be < 0.2 mg/L for > 4 hours • > 3300 people - continuous monitoring (grab sample allowed every 4 hours up to 5 days if monitoring equipment fails)40 CFR 141.74(c)(2) • 1-4 samples / day allowed for systems serving < 3301 people • If residual is < 0.2 mg/L, must notify the State before end of next business day

17. Disinfection RequirementsEntry Point to Distribution System • 1-4 samples / day allowed for systems serving < 3301 people SIZE # OF SAMPLES < 500 1 501-1000 2 1001-2500 3 2501-3,300 4 • If residual is < 0.2 mg/L, must notify the State before end of next business day 40 CFR 141.74(c)(2)

18. Distribution System Disinfection Requirements • Residual cannot be absent or HPC > 500ml in > 5% of samples/month for 2 mo. • Monitoring locations / frequency (same as total coliform samples) • For systems receiving groundwater and surface water, States may allow monitoring at surface water sites 40 CFR 141.74(c)(3)(i&ii) • Above requirements do not apply if HPC monitoring not feasible and State determines adequacy of disinfection

19. Recommended Removal and Disinfection Levels Assumed Log Recommended Log Removals Disinfection Treatment Giardia Viruses _ Giardia Viruses Conventional 2.5 2.0 0.5 2.0 Direct Filtration 2.0 1.0 1.0 3.0 Slow Sand 2.0 2.0 1.0 2.0 Filtration

20. Recommended Removal and Disinfection Levels Assumed Log Recommended Log Removals Disinfection Treatment Giardia Viruses _ Giardia Viruses Diatomaceous 2.0 1.0 1.0 3.0 Earth Filtration Bag/Cart 2.0 0.0 1.0 4.0 Membranes As determined by the State

21. Disinfection Contact Times Contact time calculations will be easy when a spreadsheet is published in the American Water Works Association’s OpFlow in the summer of 1999.