recreational wq standards and wastewater disinfection jim davenport monitoring & assessment...
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Recreational WQ Standards and Recreational WQ Standards and Wastewater DisinfectionWastewater Disinfection
Jim Davenport
Monitoring & Assessment Section
Water Quality Planning Division
Office of Water
Texas Commission on Environmental Quality
[email protected] tel. 512/239-4585
April 26, 2011
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Table of Contents for This Presentation
▸Characteristics of indicator bacteria▸Historical linkage of indicators, disinfection▸Notes on disinfection requirements▸Notes on dechlorination requirements▸Development of recreation criteria in U.S.▸Recreation criteria in Tx WQ Standards (2010)▸Bacteria limits in discharge permits (EPA, TCEQ)▸EPA re-evaluation of recreation criteria
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Waterborne Diseases/Pathogens
Bacteria Viruses Protozoa
Shigella Enteric viruses Crypto-Salmonella -(gastroenteritis) sporidiumE. coli O157:H7 Adenovirus: EntamoebaCampylobacter -(colds, etc.) Giardia:Cholera PolioTyphoid: Hepatitis A:
Photos: 1 & 3 from primewater.com from 2 from OlarMed.com
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Indicator Bacteria
▸E. coli, Fecal coliform, Total coliform, Enterococci, etc.▸Surrogate of potential pathogens in water▸Ideal characteristics:- Occur at detectable concentrations- Easy to monitor and assess- Well-correlated with actual pathogens- Provide quantifiable risk of disease▸Important uses of indicator bacteria:- Indicator of suitability of treated drinking water- Instream criterion for aquatic recreation- Indicator of seafood consumption safety (oysters)
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Historical Notes on Pathogens/Indicators
▸1854 – John Snow documented cholera outbreak from sewage-contaminated well in London▸1856 – William Budd made a similar
demonstration for waterborne typhoid▸1883 – Robert Koch microscopically identified
bacteria causing cholera & typhoid▸1891 – E. coli tube tests used to indicate fecal
origin of typhoid bacteria in Hudson River, NY
From Indicators for Waterborne Pathogens, 2004, National Research Council of the National Academy of Sciences.
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Indicators in Early Disinfection Studies
Field demonstration of chlorine dosing (“available chlorine”)Side stream from City of Boston trickling filter WWTPFrom: Earle B. Phelps, 1909, USGS Water Supply Paper 229
Avg. “total bacteria” removal over time at ~ 5 mg/L chlorine:10 min – 95% 15 min – 99.8% 60 min – 99.9%
Initial chlorine mg/L E. coli per mL
Monthly mean Before ~ 2 hours % removal2.5 mg/L (Nov, N=3) 41,500 720 98.36.1 mg/L (Apr, N=4) 135,300 8 99.9
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Disinfection Requirements in TexasTexas Administrative Code, Chapter 30, Section 309.3(g)
▸Chlorine requirements for domestic discharges:- Chlorine residual > 0.5 mg/L- Detention time > 20 minutes- Chlorine (mg/L) X Time (minutes) > 20- Maximum chlorine < 4 mg/L▸Exempt: Stabilization ponds > 21 days retention▸Alternative disinfection such as UV is allowed:- If supported by engineering report- Additional monitoring or limits as needed
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Dechlorination
▸Advocated by EPA in: Disinfection of wastewater – Task Force Report” MCD-21, EPA-430/9-75-012 1976
▸EPA 1984 criteria for total residual chlorine to protect aquatic life: 0.019 mg/L acute: 0.011 mg/L chronic
▸In 1990, dechlor by two large discharges at Dallas & Fort Worth substantially improved fish in the Trinity River
(TPWD, River Studies Report No. 10, 1992)
▸Dechlor and whole-effluent toxicity testing required in Tx for domestic discharges > 1 MGD since early 1990’s
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Dechlorination – Revisions
▸On 6/30/10, TCEQ approved revisions of the Standards Implementation Procedures▸Revised procedures are not in effect until approved by EPA, and EPA’s review is still in progress▸The revised procedures require dechlor for domestic discharges > 0.5 MGD (1.0 MGD previously)▸For discharges > 0.5 to < 1.0 MGD, dechlor is required only for new and amended permits (not renewals)▸EPA comment letter on 12/2/10 indicated that dechlor should apply to discharges < 0.5 MGD
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Bacteria Criteria for Recreation
▸Fed. criteria for fecal coliform published in 1968:- From U.S. Public Health Service epidemiology studies- 200 FC/100 mL as geometric mean- 400 FC/100 mL for single samples (< 10%) - Already in TCEQ WQ Standards in 1967
▸New studies & revised EPA criteria in 1986:- E. coli for freshwater: 126/100 mL geo mean- Enterococci for saltwater: 35/100 mL geo mean- Adopted in TCEQ standards in 2000
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Revised Recreational Standards (6/30/10)
Previously: Almost all water bodies primary contact > 300 water bodies not meeting bacteria criteria (2010) Expand recreational categories Implement new use-attainability analyses
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Recreation Uses Indicator Bacteria (#/100 ml)Geometric Mean Criteria
Single-sample Max Criteria in BracketsE. coli (FW) Enterococci (SW)
Previous Standards: Contact recreation 126 [394] 35 [89] Noncontact rec. 605 168Revised Standards:(Adopted 6/30/2010)
Primary contact 126 [399] 35 [104] Secondary contact 1
630 175
Secondary contact 2
1030 --
Noncontact rec.
2060 350
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Recreational Use-Attainability
▸Uses other than primary contact may be appropriate for some water bodies▸TCEQ has new recreational UAA procedures▸Surveys include physical & flow characteristics, + observed evidence of recreation▸Local input (interviews) important▸Initiated 90 recreational UAAs▸Involves major coordination effortand public participation
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Bacteria Limits in Permits
▸1973 – EPA included fecal coliform in performance requirements for domestic wastewater [40 CFR Part
133]▸1976 – EPA deleted these fecal coliform requirements▸EPA current reg. requires effluent limits for permits
that could “cause or contribute” to WQ impairment – for pollutants of concern [40 CFR Part 122.44] ▸In 2007, EPA objected to permits to impaired waters – unless bacteria limits included [~24 by Sept 2007]▸TCEQ provided documentation for using effluent limits for minimum chlorine residual to regulate disinfection
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Effluent Bacteria: Houston TMDL StudiesEffluent Bacteria: Houston TMDL Studies
Minor municipal facilities(114 data points)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 5 10 15 20
Residual chlorine (mg/L)
E. c
oli
(lo
g o
f #
/10
0 m
l)
Log E. coli / 100 ml
Single sample max log (2.6) = 394 / 100 ml
Geometric mean log (2.1) = 126 / 100 ml
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TCEQ Effluent Limits for Bacteria
▸Adopted 11/4/09; Effective 11/26/09- 30 TAC §§ 309, 319, 210▸Required for domestic discharge permits - §309.3(h)▸Effluent limits = most stringent criteria in WQ
standards:- Monthly avg limit = geometric mean criterion in stds- Daily max limit = single sample criterion in stds ▸Sampling frequency of bacteria effluent limits - §319.9▸Bacteria effluent limits for reclaimed water - §210.33
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EPA Review of Existing Recreation Criteria
▸EPA is re-evaluating bacteria indicators for coastal waters & Great Lakes; for Federal Beach Act of 2000▸Lawsuit settlement (w/ NRDC, NACWA, LA County):- Requires conducting numerous specific studies- Requires publishing criteria by October 15, 2012; as
indicated by new studies▸Results could amend EPA’s 1986 recreation criteria▸Examples of studies:- Additional epidem. studies (e.g., tropical, marine)- Evaluating alternative indicator organisms- Developing rapid tests for indicators (e.g., DNA)
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Summary
▸Bacterial indicators used > 100 years▸Current indicators are “imperfect”▸TCEQ revised recreation WQ Standards -
6/30/10▸Bacteria effluent limits required as of 11/26/09▸Dechlor for smaller dischargers under EPA
review▸EPA reviewing recreation criteria – by 10/15/12▸Questions?