Surface Water Treatment Rule Bob Clement Drinking Water

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

Surface Water Treatment Rule Ground Water Reclassification PWS TYPE: STATE DETERMINATION BY: CWS 6/29/94 NCWS 6/29/99 40 CFR 142. 16 (b)(2)(B) ________________________________________ DETERMINATION Direct influence of surface water ACTION Meet avoidance criteria within 18 months or Install filtration within 18 months 40 CFR 141. 71

Surface Water Treatment Rule General 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 CFR 141. 70(a))

Surface Water Treatment Rule General Requirements * Applies to surface supplies and groundwater supplies under the influence of surface water *Regulates for Giardia, viruses, Legionella, heterotrophic bacteria, and turbidity

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.

Cryptosporidium In almost all cases, wherever Giardia was present, Cryptosporidium was also present. (Le. Chevallier et al. , 1991 a) 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.

Cryptosporidium *It would take up to 29, 000 mg/l of CL 2 to inactivate crypto. *Traditional chlorination doesn’t work. Physical removal by treatment is the only method of reduction for crypto.

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

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

Turbidity Monitoring Requirements Filtered 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))

Turbidity Performance Requirements Filtered 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)) *

Turbidity Performance Requirements Filtered Systems * Slow sand 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))

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))

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)

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)

Disinfection Requirements Entry 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

Disinfection Requirements Entry 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)

Distribution System Disinfection Requirements *Residual cannot be absent or HPC > 500 ml 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

Recommended Removal and Disinfection Levels Assumed Log Removals Treatment Recommended Log Disinfection Giardia Viruses _ Giardia Viruses Conventional 2. 5 2. 0 0. 5 2. 0 Direct Filtration 2. 0 1. 0 3. 0 Slow Sand Filtration 2. 0 1. 0 2. 0

Recommended Removal and Disinfection Levels Assumed Log Removals Treatment Recommended Log Disinfection Giardia Viruses _ Giardia Viruses Diatomaceous Earth Filtration 2. 0 1. 0 3. 0 Bag/Cart 2. 0 0. 0 1. 0 4. 0 Membranes As determined by the State

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