human viruses in deep groundwater in wisconsin: … viruses in deep groundwater in wisconsin:...
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Human viruses in deep groundwater in Wisconsin:
Implications for public health, water treatment, and groundwater protection
Kenneth R. BradburyWisconsin Geological and Natural History Survey
University of Wisconsin-Extensiony
Wisconsin Soil and Water Conservation SocietyAnnual Conference
2/9/12
Waterborne Disease Outbreaks in the USA
• From 1971 to 2002 there were 716 outbreaks associated with an infectious agent in drinking water
• 60% of the outbreaks were attributable to groundwater
• Pathogen in more than 50% of outbreaks is unknown and assumed viral
Summarized from CDC reports, e.g., MMWR, 2004, 53(SS08);23-45
Examples of Groundwater-borne Disease Outbreaks
• South Bass Island, OH 2004• Campylobacter jejuni,
Salmonella typhimurium, norovirus, and Giardia in private and municipal wells
• 1,450 persons ill
• Missouri 1999• Salmonella typhimurium in
municipal well• 124 persons ill
• Walkerton, Ont. 2000• E. coli O157:H7 in municipal
well• Of 4,800 residents, 2,300
became ill• 7 died
• Wyoming 2001• Norovirus in non-
community, transient well• At least 84 patrons ill
• Door County WI 2007• Norovirus in restaurant well• At least 229
patrons/employees ill• 6 hospitalized
Groundwater supplied from deep, confined bedrock aquifers is usually assumed to be protected from contamination and free of pathogenic organisms, but……the presence of viruses in deep wells in Madison, Wisconsin shows that pathogenic surface contaminants can reach deep aquifers over relatively short time spans.
Take-home messages…
furthermore…
• Viruses were found in every well tested• Leaky sewers are a likely virus source• Virus transport to wells appears to be much
more rapid than standard groundwater models suggest
• Rapid flow through discrete geologic features (fractures) might explain virus occurrence
Pathogens in Human WastewaterBacteria (e.g., Campylobacter,Salmonella, E. coli O157:H7, Aeromonas)
Viruses (e.g., adenovirus, enterovirus, rotavirus)
Protozoa, (e.g., Cryptosporidium,Giardia, Toxoplasma)
1,438 pathogens infect humans of which 32 are waterborne in the U.S.
Particulate transport
• Particulates and common diameters• Colloids (<0.2 um)• Bacteria (~.2 – 20 um)• Viruses (~50 nm) (1000 nm= 1um; 1nm is one billionth of
a meter)
• For comparison• Human hair (~50-100 um)• Rock fracture (1 um – 1 mm - ?)
Viruses are often much smaller than fracture apertures or rock pores.
Public supply wells in
Wisconsin
Currently, 66 municipal water systems in Wisconsin do not
disinfect water
Background• Initial virus sampling conducted as part of
AWWARF (now Water Research Foundation)- funded study of aquitards
• We wanted to find out whether viruses were present in a deep, confined bedrock aquifer
• We did not expect to find any because the travel times were supposedly much longer than the virus lifetimes
Acknowledgements: co-authors, field workers, and cooperators
• Madeline Gotkowitz, Dave Hart, Pete Chase, Andrew Aslesen, Jake Krause, Wisconsin Geological and Natural History Survey
• Mark A. Borchardt, Susan K. Spencer, Marshfield Clinic Research Foundation
• Chris Gellasch, Jean Bahr, University of Wisconsin-Madison
• Randy Hunt, U.S. Geological Survey
• John Cherry, Beth Parker, University of Waterloo, Ontario
• Madison Water Utility
• Madison Municipal Sewerage District
• Wisconsin DNR – Groundwater Joint Solicitation Program
Study Objective Evaluate the occurrence of human viruses in the Mount Simon aquifer, a confined, deep sandstone aquifer in south-central Wisconsin.
Wisconsin Geology
bedrock glacial
Wisconsin’s geologic history created important bedrock and glacial aquifers. Aquitards control groundwater flow and quality in both
settings.
Dane County geology...
The next slide shows a cross
section along this line...
glacial geology
Granite
Mt Simon &Eau Claire sandstones
Eau Claireshale
Sandstone& dolomite
BlueMounds
Mt Horeb Verona MadisonGlacial deposits
sandstone aquifer
water table
citywell
Hydrogeologic Cross Section
Groundwater moves downward and laterally through Dane County’s aquifers...
Domestic wells
the lakes
16
aquifer
aquifer
aquitard
Units in the “sandstone”
aquifer
Core of Cambrian sandstone from the Madison area. Sand
is clean, well-sorted, well rounded, predominately
quartz.
Microscope image of sandstone from a Madison supply well. Clean, well-rounded quartz grains are
generally non-reactive.
18
Core sample of the Eau Claire shale (aquitard)
1919
Eau Claire aquitard
Wells sampled
2007-2009We began with 10 wells in a variety of locations to be sure we had virus-positive wells to work with.
We later reduced the sampling to 6 wells due to budget and logistic considerations.
Virus Sampling
• Virus samples collected monthly. All samples taken prior to chlorination
• qRT-PCR/qPCR detection of enterovirus,rotavirus, hepatitis A virus, norovirus, and adenovirus
•Enterovirus and adenovirus serotype determined by nucleic acid sequencing; infectivity determined by cell culture
• Isotopes (3H, 2H, 18O) analyzed at the University of Waterloo Environmental Isotope Lab
Study Methods
Construction of Madison supply wells
deep aquifer
aquitard
shallow aquifer
glacial materials
casi
ngop
enho
lewell
crystalline rock
50
300
320
800
rela
tive
dept
hs,f
eetb
elow
surfa
ce
not to scale
water table
potentiometricsurface
Typical (newer wells)
deep aquifer
aquitard
shallow aquifer
glacial materials
casi
ngop
enho
le
well
crystalline rock
50
220230
730
rela
tive
dept
hs,f
eetb
elow
surfa
ce
not to scale
water table
potentiometricsurface
147
Some older wells (1928)Note shallow casing
rela
tive
dept
hs,f
eetb
elow
surfa
ce
casi
ngop
enho
le
well 7
30
215225
725
237.6
not to scale
casi
ngop
enho
le
well 30
23
266277
800
312
casi
ngop
enho
le
well 19
15
255
718
260
245
casi
ngop
enho
le
well 13
60
780
260
370
casi
ngop
enho
le
well 12
35
404418
986
260
rela
tive
dept
hs,f
eetb
elow
surfa
ce
well 11
18
752
casi
ngop
enho
le
111
deep aquifer
aquitard
shallow aquifer
glacial materials
casi
ngop
enho
le
well
crystalline rock
50
300
320
800
rela
tive
dept
hs,f
eetb
elow
surfa
ce
not to scale
water table
potentiometricsurface
Construction details of the municipal wells sampled throughout the project. Diagram at upper left shows typical hydrostratigraphy and well construction for the Madison area.
Wells sampled
2007-2009We began with 10 wells in a variety of locations to be sure we had virus-positive wells to work with.
We later reduced the sampling to 6 wells due to budget and logistic considerations.
Overall findingsWe found viruses in every well sampled in 2007-2009, though not every time sampled
Summary of virus detections by water source, wells 7, 11, 12, 13, 19, 30 only.
virus detection (gc/l)
water source number of samples percent positive min max mean
wells148 46.6 0.00 6.27 0.65
Lake Mendota17 82 0.00 532 44
sewage influent26 100.0 12,900 36,310,000 2,010,000
Most frequently detected viruses, by rank. Number of detections in parentheses. Multiple
viruses indicate a rank tie.
Rank wells sewage lakes
1 A41 (38) A41 (18) A41 (12)
2 A31 (12) A31 (15) A2, E3 (3)
3 A2 (11) A2, E3 (5) A31, E11, E30 (2)
4 E3 (5) E9 (4) --
5 E30, A7 (4) A6, E11 (3) --
6 Cox A16, Cox B3, Cox B4, E11 (3) Cox A16, Cox B4 (2) --
7 A5, E6, E9, E71 (1) A5, A7, E6, E30, E71, E? (1) --
2007-2009 was an unusually wet period; large storms in August 2007 and June 2008
Coincidence with time The coincidence of virus detections in wells, lakes, and
sewage is surprising.sewage is surprising.g g
Well Virus Concentrations - Coincidence with Time
percentages indicate positive detections
note scale changes
Coincidence of peaks in wells miles apart
suggests a regional problem
16 different species (serotypes) of viruses were identified in wells, sewage, and lake water during this study, and in many cases wells and sewage contained identical virus serotypes. Detected viruses include Enteroviruses echovirus 3, echovirus 11, Coxsackie A16, B3, and B4, Adenoviruses 2, 7, 31, and 41.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
14-S
ep-0
7
24-O
ct-0
7
26-N
ov-0
7
19-D
ec-0
7
24-J
an-0
8
26-F
eb-0
8
24-M
ar-0
8
28-A
pr-0
8
27-M
ay-0
8
7-Ju
l-08
28-J
ul-0
8
25-A
ug-0
8
17-S
ep-0
8
29-S
ep-0
8
13-O
ct-0
8
27-O
ct-0
8
10-N
ov-0
8
2-D
ec-0
8
16-D
ec-0
8
7-Ja
n-09
23-J
an-0
9
3-Fe
b-09
16-F
eb-0
9
11-M
ar-0
9
31-M
ar-0
9
27-A
pr-0
9
A41 x x x x x x NS x x x x x x x x x x x x xA31 x x x x NS x x x x x x x x x x x xA2 x x x x x NS xE3 x x NS x x xE30 NS x xA7 x NSE11 x x x x NSCoxA16 x NS xCoxB3 NSCoxB4 x NS x
A41 x x x x x x x x x x x x x x x x x xA31 x x x x x x xA2 x x x x x x xE3 x x xE30 x xA7 x x x xE11 x x xCoxA16 x xCoxB3 x xCoxB4 x
A41 x NS NS NS NS NS NS NS x NS x x x x x x x xA31 NS NS NS NS NS NS NS NS x xA2 x NS NS NS NS NS NS x NS x NSE3 NS NS NS NS NS NS NS x NS x xE30 NS NS NS NS NS NS NS x NSA7 NS NS NS NS NS NS NS NSE11 NS NS NS NS NS NS NS NS x xCoxA16 NS NS NS NS NS NS NS NSCoxB3 NS NS NS NS NS NS NS NSCoxB4 NS NS NS NS NS NS NS NS
Sample round
all
wel
lsla
kes
sew
age
med
ian
sam
ple
date
There is coincidence between serotypes present in sewage and serotypes present in groundwater.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
14-S
ep-0
7
24-O
ct-0
7
26-N
ov-0
7
19-D
ec-0
7
24-J
an-0
8
26-F
eb-0
8
24-M
ar-0
8
28-A
pr-0
8
27-M
ay-0
8
7-Ju
l-08
28-J
ul-0
8
25-A
ug-0
8
17-S
ep-0
8
29-S
ep-0
8
13-O
ct-0
8
27-O
ct-0
8
10-N
ov-0
8
2-D
ec-0
8
16-D
ec-0
8
7-Ja
n-09
23-J
an-0
9
3-Fe
b-09
16-F
eb-0
9
11-M
ar-0
9
31-M
ar-0
9
27-A
pr-0
9
A41 x x x x x x NS x x x x x x x x x x x x xA31 x x x x NS x x x x x x x x x x x xA2 x x x x x NS xE3 x x NS x x xE30 NS x xA7 x NSE11 x x x x NSCoxA16 x NS xCoxB3 NSCoxB4 x NS x
A41 x x x x x x x x x x x x x x x x x xA31 x x x x x x xA2 x x x x x x xE3 x x xE30 x xA7 x x x xE11 x x xCoxA16 x xCoxB3 x xCoxB4 x
A41 x NS NS NS NS NS NS NS x NS x x x x x x x xA31 NS NS NS NS NS NS NS NS x xA2 x NS NS NS NS NS NS x NS x NSE3 NS NS NS NS NS NS NS x NS x xE30 NS NS NS NS NS NS NS x NSA7 NS NS NS NS NS NS NS NSE11 NS NS NS NS NS NS NS NS x xCoxA16 NS NS NS NS NS NS NS NSCoxB3 NS NS NS NS NS NS NS NSCoxB4 NS NS NS NS NS NS NS NS
Sample round
all
wel
lsla
kes
sew
age
med
ian
sam
ple
date
Sewers are ubiquitous in urban areas.
This graphic shows only regional connector sewers. There are hundreds of miles of local sewers.
The older sewers are nearly 100 years old.
Source: http://www.surrey.ca
Cross sections showing the possible locations of a sewer relative to the water table. A: gravity-drain sewer below water table; B: gravity-drain sewer above water table; C: force main above water table; D: force main below water table. H1 and H2 represent hydraulic head inside and outside the sewer. Arrows show directions of potential sewer leakage.
Sewers are a potential virus source. Some Madison sewers are in hydraulic positions that allow them to leak to groundwater.
Sewer Locations Relative to the Water Table
Is t1 + t2 + t3 < Virus survival time (~ 2 years) ?
How Did the Viruses Reach the Deep Aquifer? (assume continuous aquitard)
Kbulk-vert ~ 2 x 10-4 cm/s
� �
Kbulk-vert ~ 2 x 10-4 cm/s
�
� �
Kbulk-horiz ~ 3.5 x 10-3 cm/s
�
� �
Is t1 + t2 + t3 < Virus survival time (~ 2 years) ?
If we pick the right parameters, transport to the aquifer could occur with the virus lifetime
But, other transport pathways are also possible
Possible Transport Pathways Through Aquitard
1) fractures
2) depositional or erosional stratigraphic windows
3) down cross-connecting open wells or boreholes
4) along damaged, deteriorated, poorly sealed well annulus or breaches in well casings
We still have not determined the pathway – research continues!
Not to scale
UnitWell 7
Mt. Simon aquifer (confined)
Eau Claire aquitard
sanitary sewer (nonpoint source)
monitoring wells
water table
open borehole
well casing
6m
Wonewoc Formation
Tunnel City Group
glacial sediments
CURRENT WORK
Geophysical logs of monitoring well adjacent to Madison well #7
A major fracture exists at 80 feet.
Large horizontal fracture at 80 ft
Dipping fracture at 165 ft
Installing a FLUTE liner at well 7Installing a FFLUTE liner at wwell 7
So what, do viruses matter?Consider-
In a recent (2006-2007) evaluation of 14 Wisconsin communities using untreated water, viruses were found in wells from every system.
And…
Using a crossover-control study design, Dr. Mark Borchardt and colleagues (Marshfield Clinic) estimate that about 15% of the annual gastro-intestinal illness in these communities can be attributed to consuming untreated water.
Should communities be required to disinfect public water??
• Following our studies in 2009, the DNR decided to require all communities to disinfect public water supplies.
• Last year (2011) the Legislature voted to make it illegal to require disinfection.• Reasons given included cost, taste, and a desire for local
decision-making• Cost of illness was not considered
Implications/Recommendations
Human viruses can be commonly present in groundwater in deep bedrock wells.
Communities that use groundwater for a drinking water source should ensure that chlorination or other disinfection levels are sufficient to deactivate viruses.
Sampling for viruses requires a time series approach because virus concentrations, and virus species, vary with time in individual wells.
Untreated sewage contains very high concentrations of viruses and should be considered a source of groundwater contamination.
Human enteric viruses potentially represent a powerful new tracing tool for hydrogeologic studies. Fundamental and applied research on the use and effectiveness of viruses as tracers should be undertaken.
Recent Publications
Borchardt, M. A.; Bradbury, K.R.; Gotkowitz, M. B.; Cherry, J. A.; Parker, B. L.. 2007. Human enteric viruses in groundwater from a confined bedrock aquifer. Environmental Science and Technology. 41(18); 6606-6612
Bradbury, K.R., M.A. Borchardt, M. Gotkowitz, and R.J. Hunt. 2008. Assessment of Virus Presence and Potential Virus Pathways In Deep Municipal Wells. WGNHS Open-File report 2008-08. 48 p.
Bradbury, K.R., M.A. Borchardt, M. Gotkowitz, and S. Spencer. 2010. Human viruses as tracers of wastewater pathways into deep municipal wells. Final report to the Wisconsin Department of Natural Resources. 47 p.
Thank You
Questions?