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12/22/2010
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Microbial Groundwater Quality and the Importance of y pEffective Well Maintenance
Neil Neil MansuyMansuyWell Rehabilitation SpecialistWell Rehabilitation SpecialistWell Rehabilitation SpecialistWell Rehabilitation Specialist
NGWA December 2010NGWA December 2010
4-Foot Stickup
100 Feet
1-Foot Stickup
8-inch LCS Surface Casing (0.25-inch wall thickness)
Cement Grout Seal (Acid Resistant)
7 7/8 -inch Borehole
12.25-inch Surface Borehole
Type II Portland Cement Grout (Acid Resistant)
10 Feet above SWL
Example of Good Well Design Diagram
4.5-inch LCS Blank Casing (0.25-inch wall thickness)
Bentonite Slurry Seal
4.5-inch LCS Slotted Casing
280 Feet275 Feet
Fine #60-grade Sand
300 Feet
SWL
400 Feet410 Feet
Not To Scale Figure 1PRELIMINARY WELL DESIGN TEMPLATE – 400 foot
Domestic Well Upper Pinal Creek, Arizona
(0.030-inch slots)
Silica Sand Filter Pack (8-12 mesh)
Notes: LCS = low carbon steelAll casing diameters are O.D. except the well screen, which is nominal
LCS Well Cap
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Groundwater Contamination
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7
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AquaGard Mantenance of WellsAquaGard AquaGard AquaGard AquaGard AquaGard AquaGard AquaGard AquaGard AquaGard AquaGard
1 3
0
1
2
3
4
5
6
Series1Series2
Rehabilitation of Well
Rehabilitation of Well Rehabilitation of
Well
3 5 7 9
11 13 15 17 19 21 23 25 27 29 31 33 35
S1
Rehabilitation of Well
Years
Detail of Corrosion and Encrustation
Well screen
Soft EncrustationEncrusted Gravel
Semi Hard Encrustation
Corrosion of Well Screen
VolumeReduction of Pore
Volume
Hard Encrustation
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Longevity of Successful Treatment, factors
• During Rehabilitation, 100% of the deposited mass is often not g , premoved therefore the original pore volume has not been achieved. Therefore it does not take as long to plug the remaining pore volume.
• Bacteria can regrow very quickly on organic material left behind after treatment
• Key to increasing time between treatments is:EFFECTIVE DEPOSIT REMOVAL
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Problem : Lost Capacity
Maximum 2 feet
Variability in Bedrock AquifersVariability in Bedrock Aquifers
Vertical Bedrock Fracture Zone Interbedded Sandstone & Shale
Closed Fractures
Open Bedrock FractureOpen Karst Void
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Rate of Lost Capacity or Biofouling• Rate of deposition most significantly
determined by organics oxygen and waterdetermined by organics, oxygen, and water chemistry
• Biological active zone often takes years to filter enough material from the groundwater
Causes of Corrosion
• Electrolysis – stray currents, high voltage electric field• Electrochemical – establishment of electrochemical cell due to
dissimilar metalsdissimilar metals• Microbial induced corrosion –Most often caused by Sulfate Reducing
Bacteria
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Tuberculation Scale GrowthIron-related bacteria grows in the aerobic environment on the casing surface. No oxygen beneath the scale nodule, due to metabolic activity.
Sulfate-reducing bacteria grows in the anaerobic environment beneath the scale nodule
Steel Well Casing Corrosion pit
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Problem:Mineral Encrustation
Down hole photo
of a mineral
encrusted well
• Evaluate the possibility of mineral or scale deposition
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Mineral EncrustationType 1:
Fe++ Fe+++
(Ferrous) (Ferric)
Red or Brown Deposits
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Mineral EncrustationsType 3:
CO2
CaCO3
CO2
MgHCO3+
CaHCO3
MgCO3
White or Yellow Deposits
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Mineral EncrustationType 2:
Mn++ Mn++++Mn++ Mn++++
(Mangannous) (Mangannic)
Brown and Black Deposits
Cause:Biological
Mi l ftMinerals are oftenBiologically Precipitated
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Mineral Encrustation is most often caused by Iron Related, Slime Forming and Sulfate Reducing Bacteria
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Biological Accumulationof Minerals
SIO2FeOCaCO2
FeOH MnOHECPS (Slime)
Slime-Forming
Bacteria
CaCO2
MgCO2
Subsurface Bacteria
• Indigenous populations typically contain 108
to 109 bacterial cells per gram• Approximately 90% are attached and form
biofilms
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Subsurface Microbiology• Depth has no influence• Higher numbers are found at the water table• Highly transmissive zones have 2 to 4 orders of magnitude higher
numbers than low permeable zones• Culturable vs. nonculturable are 4 to 5 orders of magnitude higher
numbers• 95% of the isolates are aerobic • 95% of the isolates are chemoorganoheterotrophs• 4,500 different types of bacteria have been isolated from 60
samples in 4 wellsp
Subsurface Microbiology, Bacterial Groups
• 95% nonstreptomycete• 3.5% streptomycetep y• 1.6% fungi• 81% rod shaped• 86% gram negative• 67% pseudomonads• 3% overlap between aquifer mo’s and soil mo’s
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Unsafe Bacterial Samples• Total coliforms• Fecal coliforms• TNTC (to numerous to count)• Overgrown• Atypical
Occasional or Persistent Bacterial Problems Sources
Surface Water InfiltrationSampling TechniquesEarthquake BiofilmNatural Indigenous Bacteria
Enterobacter sp.Citrobacter sp.Klebsiella sp.A h d hilAeromonas hydrophila
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CDC 1993 Private Well Study (5520 wells)
State % Total Coliform
% E Coli Positive
% NO3 N>10mg/lColiform Positive N>10mg/l
Illinois 46.0 15.3 15.3
Kansas 49.2 16.9 24.1
MN 26.8 4.3 6.3
Missouri 57.1 22.7 10.6
Nebraska 37.4 2.6 15.2
N Dakota 35.6 8.2 13.5
S Dakota 39.7 8.0 10.6
WI 23.3 2.4 6.5
Illinois Department of Health
• May 15 1995• Private well study finds nearly one third of all wells are contaminated• 130 000 private well samples from 1986 to 1994• 130,000 private well samples from 1986 to 1994• 129,257 private well samples over this nine year period, 27 percent or
34,829 tested positive for total coliforms
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Viruses in Groundwater
• Recognition of pathogenic viruses date to poliovirus from Michigan well in 1972 (Mack et al., 1972)
• EPA recently evaluated 16 studies that samples for viral pathogensEPA recently evaluated 16 studies that samples for viral pathogens and fecal indicator such as coliphage
• 12 studies evaluated pathogens such as human enterovirus• 12 studies evaluated coliforms and coliphages• 3 other studies evaluated coliphage and bacteria
Enterovirus Results
• 600 samples 460 wells 36 wells positive(8%)• 7 wells (23%) in PWS wells• 12 (15%) wells in a study on 81 PWS wells along Mississippi river• 12 (15%) wells in a study on 81 PWS wells along Mississippi river• 16 wells (7%) in 246 wells for PCR analysis• 1 (4%) in 24 private wells in Karst
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Viruses
• Represent a more serious risk than Total coliforms• Are a better indicator of true contamination• Are often not used due to difficulty and cost of tests• Are often not used due to difficulty and cost of tests
Virus Occurrence
• One study in Public Water System 38% of 246 wells with PCR analysis showed
• EnterovirusEnterovirus• Rotavirus• Hepatitis A virus• PCR does not distinguish between viable or non viable
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Factors: Well Hydraulics• Production profiles change as wells age
Water quality changes can result from changes in the production• Water quality changes can result from changes in the production profile
• Well hydraulics influence the effectiveness of well rehabilitation• Excess production capacity exists in many wells
Well Hydraulics• The bottom part of many wells are stagnant
zones This is similar to the “dead ends” inzones. This is similar to the dead ends in distribution systems
The lack of adequate “up-hole” velocity leads to water quality problems including “unsafe” bacterial samples
The pump needs to be pulled for proper well rehabilitation
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Flow Rate Before and After
• BEFORE• Total Flow 3000 gpm
• AFTER• Total Flow 3000 gpm
• 600 gpm• 568 gpm• 793 gpm• 481 gpm• 314 gpm• 244 gpm
• 1,074 (+79%)• 1,002 (+76%)• 267 (-64%)• 150 (-69%)• 194 (-38%)• 313 (+28%)
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Downhole Video Inspections
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Diagnosis:
Bacterial TestingI l t d b t i (IRB)
g• Iron-related bacteria (IRB)
• Slime forming bacteria (SLYM)
• Sulfate-reducing bacteria (SRB)
BARTS
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3. orrectingC the cause of the problem.
Well RehabilitationandMaintenanceMaintenance
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History of Well Maintenance
• Heat Treatments• Heat with Chemical• Aquifer Sterilization• Aquifer Sterilization• Chemical Treatments• Injection of Chlorine
Well Maintenance Treatments• Can involve many different strategies• Must achieve effective deposit removalp• Must be custom tailored, based upon cause of problem, well
construction details, and type of formation• Must have penetration into the surrounding formation• Must have good agitation
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Steps for EffectiveWell Rehabilitation
Pretreatment
Various Treatment Applications
Development or Redevelopment
Pretreatment of Well
• Wire Brushing making sure to select brush appropriatelyappropriately
• Determine depth before and after wire brushing
• Bail or airlift if significant fill in the bottom of well
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Rehabilitation Options
• Many different approaches
Percussive ExplosivesPercussive Explosives
a)a) Ability to remove hard encrusted materials on the Ability to remove hard encrusted materials on the inside of the casinginside of the casing
b)b) Some fracturing of cemented gravel pack and Some fracturing of cemented gravel pack and formation materialformation material
c)c) Extremely aggressive in natureExtremely aggressive in nature
d)d) Short term fixShort term fix
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Solution: Chemical TreatmentSite-Specific Customization and Chemical Treatment Considerations
• Volume• Concentration• Sequence• Combination• Above-ground premixing
Step 1 : DisinfectantsSodium Hypochlorite (bleach)Calcium Hypochlorite (HTH)Chlorine GasChlorine DioxideHydrogen PeroxideSodium Hydroxide (lye)
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Disinfection Efficiency
• pH is very important• Concentration• Contact time• Contact time• Use of surfactants• Method of application
AQUA FREED
Before After
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AQUA FREED®
Mode of Action:R id E i Reduction ofRapid Expansion
(570 Times)
Reduction of Surface Tension
Formation of
H2CO3
Pore Water Freezing
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FIRST STAGE:
Seal off the well and inject CO2 in the gaseous state.
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SECOND STAGE:
CO2 injection in liquid state at controlled pressures.
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Before Aqua Freed
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After Aqua Freed
Well DevelopmentInvolves removal of dislodged or disrupted depositsIs one of the most important steps in effective rehabilitationCan involve many different techniquesCan involve many different techniquesMust be able to achieve transfer of energy into the surrounding formationMust pay “Special attention to detail”
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CABLE TOOL Development METHOD
WELL DEVELOPMENT
The Pump-and-Surge process is often the final step in well development but is not the most effective method
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THIRD STAGE:
Development with double surge block and airlift.
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Well Development
• MVI_0755.AVI
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Shifting the Paradigm
R ti ProactiveReactive Proactive
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Well Maintenance
• Shock chlorination is ineffective• Well Hydraulics limits chemical
applications• Can be effective in maintaining
it d litcapacity and quality
Well Maintenance with Aqua Gard™
• In well maintenance deviceAllows wells to be effectively• Allows wells to be effectively maintained without pulling the pump
• Targeting keeping surfaces clean• Equipment allows effective energy to
be delivered into a well• Patented
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Applications
• New Wells• Retrofitting existing wells after rehabilitation• ASR wells• ASR wells• Injection wells• Recovery wells
Aqua Gard™ Pilot
Aqua Gard Pilot - T1AG AGAG
0.000.100.200.300.400.500.600.700.800.901.00
Spec
ific
Cap
acity
AG
AGAG
Pre
Post AF
AGAG
AG
11-S
ep-0
1
15-O
ct-0
1
13-N
ov-0
1
09-J
an-0
2
06-F
eb-0
2
11-A
pr-0
2
25-N
ov-0
2
14-M
ar-0
3
01-A
ug-0
3
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Animal Breeding Facility Savings
Rehabilitation Aqua Gard Savings Well rehabilitation $9,200 Aqua Gard installation $2,595 Per well cleaning cost $2,520 $6,000 Water treatment cost $65,600 $13,600 36 Month per well total $68,120 $31,395 $36,725 36 Month Site total $613,080 $156,975 $456,105
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Well #3 Specific Capacity
Forest County Well # 3Specific Capacity
Pre and Post Aqua-Freed
0 8
Aqua-Freed
Aqua-Gard
0.3
0.4
0.5
0.6
0.7
0.8S
peci
fic C
apac
ity
0
0.1
0.2
Jun-01
Aug-01
Oct-01
Dec-01
Feb-02
Apr-02
Jun-02
Aug-02
Oct-02
Nov-02
Jan-03
M ar-03
M ay-03
Jul-03
Sep-03
Nov-03
Jan-04
M ar-04
M ay-04
Jul-04
Sep-04
Nov-04
Jan-05
M ar-05
M ay-05
Jul-05
Sep-05
Nov-05
Jan-06
M ar-06
M ay-06
Jul-06
Sep-06
Nov-06
Jan-07
Date
30.000 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75
Aqua OhioMassillon, OH
Stark Well #5 Step-Rate Pumping Test Pre-Post Aqua Freed and Pre-Post Aqua Gard Comparison
2088 GPM
Pump Test Time (Minutes)
40.00
50.00
60.00
Pum
pim
g W
ater
Lev
el (F
eet)
70.00
Pre Aqua Freed 2006 Post Aqua Freed 2006Pre Aqua Gard 2007 Post Aqua Gard 2007Pre Aqua Gard 2009 Post Aqua Gard 2009
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Treatment Unit:
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Example of results – Before & After
Before After
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Verification Code
• Contact Information• 816 221 7770• nmansuy@subsurfacetech com
10WR01
