Surface Water Treatment Rule

Bob ClementDrinking Water

ProgramU.S. EPA Region 8

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) _______________________________________________________________________________

DETERMINATION ACTION

Direct influence Meet avoidance criteria within of surface water 18 months or

Install filtration within 18 months 40 CFR 141.71

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))

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

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.

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.

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.

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 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))

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% ofmeasurements) (40 CFR 141.73(a))

Diatomaceous earth filtration - < 1 NTU 95% of measurements (40 CFR 141.73 (c))

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))

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 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

Disinfection RequirementsEntry Point to Distribution System

1-4 samples / day allowed for systems serving < 3301 peopleSIZE # OF SAMPLES< 500 1501-1000 21001-2500 32501-3,300 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 > 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

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 2.0Filtration

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

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.