Surface Water Treatment Rule

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Surface Water Treatment Rule

• Bob Clement
• Drinking Water Program
• U.S. EPA Region 8

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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
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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))

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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

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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.
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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.
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Cryptosporidium

• It would take up to 29,000 mg/l of CL2 to
  inactivate crypto.
• Traditional chlorination doesnt work. Physical
  removal by treatment is the only method of
  reduction for crypto.

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

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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 lt 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))

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Turbidity Performance RequirementsFiltered
Systems

• All systems - never exceed 5 NTU (40 CFR 141.73)
• Conventional treatment, direct filtration lt
  0.5 NTU 95 of measurements
• (State may allow up to lt 1 NTU 95
  of measurements) (40 CFR 141.73(a))
• Diatomaceous earth filtration - lt 1 NTU 95 of
  measurements (40 CFR 141.73 (c))

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Turbidity Performance RequirementsFiltered
Systems

• Slow sand and other filtration technologies
• lt 1 NTU 95 of measurements (State may allow up
  to lt 5 NTU 95 of measurements but cannot
  exceed 5 NTU)
• (40 CFR 141.73 (b) and (d))

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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))

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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)

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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)(12)

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Disinfection RequirementsEntry Point to
Distribution System

• Residual entering distribution system
• cannot be lt 0.2 mg/L for gt 4 hours
• gt 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 lt
  3301 people
• If residual is lt 0.2 mg/L, must notify the State
  before end of next business day

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Disinfection RequirementsEntry Point to
Distribution System

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

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Distribution System Disinfection Requirements

• Residual cannot be absent or HPC gt 500ml in gt 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)(iii)
• Above requirements do not apply if HPC monitoring
  not feasible and State determines adequacy of
  disinfection

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Recommended Removal and Disinfection Levels
Assumed Log Recommended Log Removals Disinfe
ction 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
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Recommended Removal and Disinfection Levels
Assumed Log Recommended Log Removals Disinfe
ction 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
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Disinfection Contact Times
Contact time calculations will be easy when a
spreadsheet is published in the American Water
Works Associations OpFlow in the summer of 1999.