Title: Performancebased Monitoring Strategies for the SDWA
1Performance-based Monitoring Strategies for the
SDWA
A place-based approach
Ed Brands
Cooperative State Research, Education, and
Extension Service
Grant 2001-51130-11373
2Background/Rationale
- SDWA requires monitoring for a series of 86
contaminants (modified by IDNR waiver in 1997) - Many of these are never found in most supplies in
Iowa
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
3SDWA CONSTITUENTS
Toxaphene 2,4,5-TP (Silvex) 1,2,4-Trichlorobenzene
1,1,1-Trichloroethane 1,1,2-Trichloroethane Trich
loroethylene Vinyl chloride Xylenes (total)
cis-1,2-Dichloroethylene trans-1,2-Dichloroethylen
e Dichloromethane 1,2-Dichloropropane Di(2-ethylhe
xyl) adipate Di(2-ethylhexyl) phthalate Dinoseb Di
oxin (2,3,7,8-TCDD) Diquat Endothall Endrin Epichl
orohydrin Ethylbenzene Ethylene
dibromide Glyphosate Heptachlor Heptachlor
epoxide Hexachlorobenzene Hexachlorocyclopentadien
e Lindane Methoxychlor Oxamyl (Vydate) Polychlorin
ated biphenyls (PCBs) Pentachlorophenol Picloram S
imazine Styrene Tetrachloroethylene Toluene
Microorganisms (7) Cryptosporidium Giardia
lamblia Heterotrophic plate count Legionella Total
Coliforms Turbidity Viruses (enteric) Disinfect
ion Byproducts (4) Bromate Chlorite Haloacetic
acids (HAA5) Total Trihalomethanes
(TTHMs) Disinfectants (3) Chloramines (as
Cl2) Chlorine (as Cl2) Chlorine dioxide (as
ClO2) Inorganic Chemicals (16) Antimony Arsenic
Asbestos Barium Beryllium Cadmium
Chromium (total) Copper Cyanide (as free
cyanide) Fluoride Lead Mercury (inorganic) Nitrate
(measured as Nitrogen) Nitrite (measured as
Nitrogen) Selenium Thallium Organic Chemicals
(53) Acrylamide Alachlor Atrazine Benzene Benzo(a
)pyrene (PAHs) Carbofuran Carbon
tetrachloride Chlordane Chlorobenzene 2,4-D Dalapo
n 1,2-Dibromo-3-chloropropane o-Dichlorobenzene p
-Dichlorobenzene 1,2-Dichloroethane 1,1-Dichloroet
hylene
86 Contaminants
Radionuclides (4) Alpha particles Beta particles
and photon emitters Radium 226 and Radium
228 Uranium
4Background/Rationale
- SDWA requires monitoring for a series of 86
contaminants (modified by IDNR waiver in 1997) - Many of these are never found in most supplies in
Iowa - SDWA requires that samples be taken within
fixed-intervals - Many of the contaminants found in Iowa surface
water (e.g. nitrate and pesticides) do not occur
uniformly throughout the year
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
5Sampling Frequency for N03
6Background/Rationale
- SDWA requires monitoring for a series of 86
contaminants (modified by IDNR waiver in 1997) - Many of these are never found in most supplies in
Iowa - SDWA requires that samples be taken on a
fixed-interval schedule - Many of the contaminants found in Iowa surface
water (e.g. nitrate and pesticides) do not occur
uniformly throughout the year - SDWA monitoring strategies are not necessarily
appropriate for some contaminants, especially
those found in Iowa surface water - How might alternative monitoring strategies,
based on the processes that affect water quality,
perform in comparison to current SDWA strategies?
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
7Monitoring Requirements Recent Developments
- 1996 SDWA amendments monitoring relief
- Opportunity for PWSs to apply for, and states to
grant waivers (SDWA 1418) - 1997 IDNR Statewide Monitoring Waiver
- Monitoring no longer required for 27 contaminants
that have never (or very rarely) occurred in Iowa
Public Water Systems - 2002 EPA Alternative Monitoring Guidelines
- How to apply for monitoring relief
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Hydrology Conference Spring 2003
8Chronic Chemical Contaminants
- Alternative monitoring applies to
- Synthetic Organic Chemicals (SOCs, e.g.
pesticides) - Volatile Organic Chemicals (VOCs, e.g. toluene,
benzene) - Inorganic Chemicals (IOCs, e.g. barium, nitrate)
- Alternative monitoring does not apply to
- Microbiological Contaminants
- Disinfectants
- Disinfection Byproducts
- Corrosion Byproducts
US EPA (2002)
SDWA 1418(b)(1)
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Hydrology Conference Spring 2003
9Viable Alternatives to Current Compliance
Monitoring Strategies?
- Natural and human processes affect the
occurrence/concentrations of chronic chemical
contaminants - Monitoring strategies can be developed to address
processes affecting contaminant occurrence - How to integrate this knowledge within the
context of SDWA? - How will alternative monitoring strategies
compare to current compliance schemes? In what
context(s)?
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
10Research Approach
- Select a sample of Iowa community water systems
dependent on surface influenced water - Obtain and review available data
- Design alternative monitoring strategies
- Construct truth datasets
- Implement alternative and current compliance
monitoring strategies - Evaluate monitoring strategies based on a series
of performance measures
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
11Research Plan Overview
Alternative Strategies
Test Data
- 1995-2001
- Ambient and drinking water data from Iowa Surface
Water CWSs - Constructed datasets
Historical data (until 1994) and prior research
- Historical
- Seasonal
- Event-based
- Comprehensive
Test Strategies
Fixed Cost
Compare Strategies
SDWA Strategy
Performance Criteria
Current Monitoring as Required by IDNR
- Detection captures
- MCL captures
- Estimation of average and daily values
12CWS Selection Process
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Hydrology Conference Spring 2003
13Characteristics of 19 Selected CWSs
- Size
- 7 small (lt 3300)
- 4 medium (3300-10,000)
- 8 large (gt 10,000)
- Predominant Source Water
- 2 Reservoirs
- 5 Lakes
- 6 Rivers
- 6 Alluvial aquifers
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Hydrology Conference Spring 2003
14Location of 19 Community Water Systems, Sources,
and Influences
15 Source Water History for Selected Iowa CWSs
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
16Data Sources
- SDWA Data- Center for Health Effects of
Environmental Contamination (CHEEC) - Ambient data
- - CHEEC
- - U.S. Geological Survey (WATSTORE)
- - Iowa Geological Survey Bureau (Iowa STORET)
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
17Alternative Monitoring Strategies
- Historical occurrence target contaminants that
have historically been present in significant
amounts (subsequent strategies will focus on
contaminants identified for this strategy) - Seasonal knowledge take samples in seasons when
high concentrations are most likely to occur - Event based allocate samples according to
hydrological events (i.e. high flow or rainfall
events) - Comprehensive combination of strategies 1-3
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
18Performance Criteria
- Detection captures
- How many samples contain contaminant(s) of
interest? - MCL captures
- How many samples exceed the water quality
standard? - Parameter estimation
- How well do strategies estimate the average
concentration? - How closely do strategies mimic the true
concentration?
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
19Preliminary Results
- Most contaminants have never been detected, or
have occurred only in insignificant
concentrations. - Less than 10 contaminants of concern (i.e. they
have occurred at greater than 20 of the MCL at
least once in the available data) in any one
water system
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
20Number of Contaminants of Concern in 19 CWSs
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
21Which contaminants are consistently of concern?
- Nitrates-all 19 CWSs
- Atrazine
- Radiological measurementsespecially systems
blending with deep GW - Occasionallybarium, cadmium, carbon
tetrachloride, xylenes
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
22Expectations
- Are some strategies superior
- In particular systems?
- For particular contaminants?
- For certain performance measures?
- Does incorporating historical knowledge represent
a significant improvement over existing
practices? - Does incorporating seasonal and event-based
knowledge provide a significant improvement over
historical knowledge only?
American Water Resources Association Agricultural
Hydrology Conference Spring 2003