Performancebased Monitoring Strategies for the SDWA

1
Performance-based Monitoring Strategies for the
SDWA
A place-based approach
Ed Brands
Cooperative State Research, Education, and
Extension Service
Grant 2001-51130-11373
2
Background/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
3
SDWA 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
4
Background/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
5
Sampling Frequency for N03
6
Background/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
7
Monitoring 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

American Water Resources Association Agricultural
Hydrology Conference Spring 2003
8
Chronic 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)
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
9
Viable 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
10
Research 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
11
Research 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

12
CWS Selection Process
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
13
Characteristics 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

American Water Resources Association Agricultural
Hydrology Conference Spring 2003
14
Location 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
16
Data 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
17
Alternative 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
18
Performance 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
19
Preliminary 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
20
Number of Contaminants of Concern in 19 CWSs
American Water Resources Association Agricultural
Hydrology Conference Spring 2003
21
Which 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
22
Expectations

• 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