surface water treatment rule
DESCRIPTION
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: CWS6/29/94 NCWS6/29/99 - PowerPoint PPT PresentationTRANSCRIPT
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.