Transcript Jim Davenport / TCEQ

Recreational WQ Standards and
Wastewater 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
Table of Contents for This Presentation
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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
Waterborne Diseases/Pathogens
Bacteria
Shigella
Salmonella
E. coli O157:H7
Campylobacter
Cholera
Typhoid:
Viruses
Protozoa
Enteric viruses
Crypto-(gastroenteritis) sporidium
Adenovirus:
Entamoeba
-(colds, etc.)
Giardia:
Polio
Hepatitis A:
from
Photos: 1 & 3 from primewater.com
2 from OlarMed.com
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)
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.
Indicators in Early Disinfection Studies
Field demonstration of chlorine dosing (“available chlorine”)
Side stream from City of Boston trickling filter WWTP
From: Earle B. Phelps, 1909, USGS Water Supply Paper 229
Initial chlorine mg/L
Monthly mean
2.5 mg/L (Nov, N=3)
6.1 mg/L (Apr, N=4)
E. coli per mL
Before
41,500
135,300
~ 2 hours
720
8
% removal
98.3
99.9
Avg. “total bacteria” removal over time at ~ 5 mg/L chlorine:
10 min – 95% 15 min – 99.8% 60 min – 99.9%
Disinfection Requirements in Texas
Texas 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
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
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
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
Revised Recreational Standards (6/30/10)
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Previously: Almost all water bodies primary contact
> 300 water bodies not meeting bacteria criteria (2010)
Expand recreational categories
Implement new use-attainability analyses
Recreation Uses
Indicator Bacteria (#/100 ml)
Geometric Mean Criteria
Single-sample Max Criteria in Brackets
E. coli (FW)
Enterococci (SW)
Previous Standards:
Contact recreation
126 [394]
35 [89]
605
168
126 [399]
35 [104]
Secondary contact 1
630
175
Secondary contact 2
1030
--
Noncontact rec.
2060
350
Noncontact rec.
Revised Standards:
(Adopted 6/30/2010)
Primary contact
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 effort
and public participation
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
Effluent Bacteria: Houston TMDL Studies
Minor municipal facilities
E. coli (log of #/100 ml)
(114 data points)
5
4.5
4
3.5
Log E. coli / 100 ml
3
2.5
Single sample max
log (2.6) = 394 / 100 ml
2
1.5
Geometric mean
log (2.1) = 126 / 100 ml
1
0.5
0
0
5
10
15
Residual chlorine (mg/L)
20
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
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)
Summary
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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?