Testing New Wells for Coliform

Testing
New Wells
for
Coliform
Bacteria
HELPING ENSURE DRINKING WATER SAFETY
Why Test Well Water for Coliform Bacteria?
Ensure
Safety of
Drinking
Water
Maintain
Consumer
Confidence
in
Groundwater
Waterborne Pathogen
Exposure Routes
INGESTION
AEROSOL
INHALATION
FOOD
DERMAL CONTACT
What are Coliform Bacteria?
AEROBIC AND FACULTATIVE ANAEROBIC
GRAM-NEGATIVE
NONSPORE-FORMING
ROD-SHAPED
FERMENTS LACTOSE
WITH
GAS PRODUCTION
WITHIN
48 HOURS @
35 DEGREES CELSIUS
MEMBRANE FILTER ANALYSIS
Coliform Bacteria are
Indicator Organisms
Positive coliform test indicates
potential presence of pathogenic
(disease-causing) microbes
Testing for pathogens requires
large volumes of water and
complex lab procedures
Coliforms are found in greater numbers than pathogens
E.coli bacteria live longer than fecal coliforms
Coliform testing is easier, more economical
and safer than pathogen testing.
TOTAL COLIFORMS
FECAL COLIFORMS
E. COLI
PATHOGENIC
E. COLI
Sources of Coliform Bacteria
INTESTINES
OF
WARM-BLOODED
ANIMALS
SOIL
&
VEGETATION
SURFACE
WATER
&
FLOODWATER
ON-SITE SEWAGE
SYSTEMS &
SEWERLINE
LEAKS
GROUNDWATER
AGRICULTURAL
WASTE RUNOFF
Etiologies of Waterborne Illness Outbreaks
(1991 – 2002)
LEGIONELLA
3%
CAMPYLOBACTERIOSIS
3%
SHIGELLOSIS
4%
OTHER
DISEASES
6%
ACUTE
GASTROINTESTINAL
ILLNESS (AGI), UNIDENTIFIED
38%
AGI – E. COLI 0157:H7
5%
AGI – NOROVIRUS
6%
CRYPTOSPORIDIOSIS
7%
GIARDIASIS
12%
CHEMICAL
POISONING
16%
Burden of Illness Pyramid
(From: Journal of Water and Health, Estimating Disease Risks Associated With Drinking Water
Microbial Exposures, Vol. 4, Supplement 2, 2006)
Deaths
Persons who are
hospitalized
Persons who visit physician
or health care facility
Persons who exhibit symptoms
Person is exposed to pathogen in water and becomes infected
Cryptosporidium
WATERBORNE
PATHOGENS
E. coli
ACUTE GASTROENTERITIS SYMPTOMS:
STOMACH
CRAMPS
DIARRHEA
NAUSEA
VOMITING
Symptomatic
Host
FEVER
Cryptosporidium
WATERBORNE
PATHOGENS
E. coli
FECAL
TO ORAL
TRANSFER
OF
PATHOGEN
Asymptomatic
Host
Secondary
Host
MICHIGAN GROUNDWATER
IS GENERALLY FREE OF:
• COLIFORM BACTERIA
• DISEASE-CAUSING MICROBES
Exceptions: Shallow carbonate
bedrock (Karst)
Very shallow coarse
sand & gravel
Faulty well construction
Unplugged abandoned
wells
Unsealed, Abandoned Well Causes Bacteria Problems
for Noncommunity Public Water-Supply Well
Reported by Minnesota Dept. of Health, Minnesota Well Management News
Fall 2006 / Winter 2007, Volume 26, No. 2
PERSISTENT COLIFORMS IN NCPWS (>2 YRS.)
(24 YR. OLD WELL - 57 FT. DEEP - 4 IN. CASING)
REPEAT WELL DISINFECTIONS UNSUCCESSFUL
INVESTIGATION OF FACILITY HISTORY FOLLOWED BY
METAL DETECTOR SEARCH BY MDH - ABANDONED WELL
WITHIN 10 FT. OF ACTIVE WELL IS SUSPECTED
EXCAVATION FINDS OLD WELL UNCAPPED 7 FT. BELOW GRADE,
10 FT FROM ACTIVE WELL - UNSEALED – SAND & DEBRIS FROM
35 FT. TO BOTTOM OF 60 FT. WELL
STATIC WATER LEVEL SAME AS ACTIVE WELL – HYDRAULIC
CONNECTION BETWEEN WELLS
AFTER OLD WELL PROPERLY PLUGGED – CONSISTENT
NEGATIVE COLIFORM BACTERIA SAMPLES
Potential Sources of
Microbial Contamination
from Well Drilling Practices
OBTAINING DRILLING WATER
FROM SURFACE WATER
SOURCE
USING BIODEGRADABLE
DRILLING FLUID OR
LOST CIRCULATION ADDITIVES
IRON BACTERIA
IN SURFACE
WATER
Introducing Contaminants During
Well Construction
FAILURE TO MAINTAIN
MINIMUM 10 PPM
CHLORINE RESIDUAL
IN DRILLING WATER
TRANSFERRING CONTAMINANTS
FROM GROUND SURFACE
INTO WELL BOREHOLE
ENCOURAGE DRILLERS
TO USE TEST STRIPS
DOWNWARD LEAKAGE AROUND
UNGROUTED CASING
INFILTRATION OF
SURFACE CONTAMINANTS
CONTAMINANT PLUME
STATIC WATER LEVEL
UNSEALED ANNULAR
SPACE AROUND
CASING
DOWNWARD
LEAKAGE
UNCONFINED
AQUIFER
GROUT
PIPE
UNSEALED
ANNULUS
BETWEEN
CASING &
BOREHOLE
DIRECT PATHWAY
TO AQUIFER
IF LEFT
UNGROUTED
OR IMPROPERLY
GROUTED
Would this temporary cap keep contaminants
out of the well?
Sanitary & Preventive Practices
During Well Completion
CLEAN
DRILLING TOOLS
BETWEEN WELLS
TO PREVENT
CROSS-CONTAMINATION
KEEP WELL COMPONENTS
ELEVATED OFF GROUND…..
USE SANITARY HANDLING
PRACTICES
SANITARY
WELL
COMPLETION
PRACTICES
PROPER
WELL
CONSTRUCTION
MATERIALS
TRAINED
PROFESSIONAL
WATER WELL
CONTRACTORS
COMPONENTS
OF A
SAFE & RELIABLE
WATER WELL
TARGET
AQUIFER HAS
AMPLE YIELD
&
SAFE WATER
SUFFICIENT
SEPARATION
FROM
CONTAMINATION
SOURCES
ROUTINE
MONITORING
OF
WATER
QUALITY
PROPER
WATER
SYSTEM
MAINTENANCE
DEFICIENT WELL HEAD
(CRACKED WELL CAP
OR OPEN VENT)
OLD WELLS WITH
CORRODED
WELL CASING
SHALLOW DEPTH
(OR SHORT CASING
IN BEDROCK)
POOR CONSTRUCTION
(UNSEALED ANNULUS
OR DUG WELL)
WELLS
MOST VUNERABLE
TO MICROBIAL
CONTAMINATION
FLOODING,
BURIED WELL HEAD
OR SUBMERGED
IN WELL PIT
TOO CLOSE TO
SEPTIC SYSTEM,
AGRIC. RUNOFF OR
ABANDONED WELL
SEWER LINE BREAK,
SEWAGE OVERFLOW
OR CROSSCONNECTION
LHD Water Sampling Activities
COLLECT BACTI SAMPLES
OR PROVIDE SAMPLE BOTTLES
TO WELL DRILLER OR
OWNER
USE WELL PERMIT PROGRAM
TO NOTIFY WELL OWNER
OF NEED TO
COLLECT SAMPLE
TRACK TEST RESULTS TO
ENSURE ALL NEW
WELLS ARE TESTED
PROMPT FOLLOW-UP ON
POSITIVE COLIFORM
RESULTS, ESPECIALLY
E. COLI POSITIVES
WITHHOLD ISSUANCE
OF WELL APPROVAL UNTIL
SAFE BACTERIOLOGICAL
SAMPLES ARE
ATTAINED
Why Should Well Contractors Collect
Bacteriological Water Samples?
•
•
•
•
Reduce public health risk
Enhance industry professionalism
Validate quality of contractors’ work
Reduce contractor liability
Why Should Well Contractors Collect
Bacteriological Water Samples?
• Improve customer confidence in
groundwater
• Reduce customer anxiety over positive
test results
• Gain better understanding of public health
within water well industry
Why Should Well Contractors Collect
Bacteriological Water Samples?
• Current practice leaves customers with
sense of purchasing incomplete product
• Contractor knows when water system is
complete and ready for sampling.
• Well owners are unfamiliar with sampling
protocol – prone to false positives.
Why Should Well Contractors Collect
Bacteriological Water Samples?
• Contractor ownership of sampling protocol
• Fewer disputes over sampling location and
technique
• Reduction of complaints over validity of
sample results
• Encourages more sanitary
drilling practices
WORK WITH
LOCAL BUILDING
CODE OFFICIAL
WATER
SUPPLY
APPROVAL
BY LHD
BUILDING
INSPECTOR
CERTIFICATE
OF
OCCUPANCY