Sediment – Causes & PreventionSediment – Causes & PreventionImproving Water Quality- Well Rehab &Improving Water Quality- Well Rehab &

Downhole Camera ApplicationsDownhole Camera Applications

Michael L. Vaught, PGMichael L. Vaught, PG

HydrogeologistHydrogeologist

Certified Well ContractorCertified Well Contractor

EGISEGIS

Downhole Video, & Well RepairsDownhole Video, & Well Repairs

441 Northside Drive441 Northside Drive

Chapel Hill, NC 27516Chapel Hill, NC 27516

Phone: Phone: 919-929-8363919-929-8363

Fax: Fax: 419-858-9118419-858-9118

Email: Email: gwinvest@juno.comgwinvest@juno.com

IntroductionIntroduction

This presentation shows examples This presentation shows examples of using downhole equipment to of using downhole equipment to limit microbial contaminants and limit microbial contaminants and achieve the highest quality water achieve the highest quality water from supply wells.from supply wells.

Rock TypeRock Type

Hard to crystalline rock and Hard to crystalline rock and granular type aquifer systems. granular type aquifer systems.

Sedimentary, Metamorphic, and Sedimentary, Metamorphic, and Igneous rocks.Igneous rocks.

Reference the Reference the Ground Water Atlas Ground Water Atlas of the United Statesof the United States and the and the Geological Surveys Maps.Geological Surveys Maps.

Well ConstructionWell Construction

Geographic or Physiographic locationGeographic or Physiographic location– Coastal PlainCoastal Plain– PiedmontPiedmont– MountainsMountains

Type of WellType of Well– large or small diameterlarge or small diameter– shallow or deepshallow or deep– cased or “open hole”cased or “open hole”

Poor Water QualityPoor Water Quality

Near surface - Rapid InfiltrationNear surface - Rapid Infiltration Biofouling (iron, mineral, slime Biofouling (iron, mineral, slime

growth)growth) Faulty well constructionFaulty well construction Geologic strata and formationGeologic strata and formation Natural or manmade disturbancesNatural or manmade disturbances

Analysis of ProblemAnalysis of Problem

Well RecordsWell Records Borehole Camera SurveyBorehole Camera Survey

– passive well inspectionpassive well inspection– active well investigationactive well investigation– identify source of well problemidentify source of well problem– verify resultsverify results

Slim-line downhole cameraSlim-line downhole camera

CasingCasing Unconsolidated Unconsolidated formationsformations

100GPM Withdrawal 100GPM Withdrawal

15’15’ Static WLStatic WL

45’45’ Pumping WLPumping WL

100gpm / (45-15)ft100gpm / (45-15)ft = specific capacity of= specific capacity of 3.3 gpm/ft of drawdown3.3 gpm/ft of drawdown

Specific Capacity of Specific Capacity of a newer wella newer well

65 GPM 65 GPM WithdrawalWithdrawal

15’15’ Static WLStatic WL

65’65’ Pumping WLPumping WL

65gpm / (65-15)ft65gpm / (65-15)ft = specific capacity of= specific capacity of 1.3 gpm/ft of 1.3 gpm/ft of

drawdowndrawdown

Specific Capacity Specific Capacity after 15 yearsafter 15 years

Unconsolidated formationsUnconsolidated formations Confined AquiferConfined Aquifer

Sealing the AnnulusSealing the Annulus– Bentonite, Cement, Concrete, MixturesBentonite, Cement, Concrete, Mixtures

CasingCasing Consolidated formationsConsolidated formations

Reasons For Contaminated Reasons For Contaminated WaterWater

Distribution system Distribution system Well configurationWell configuration Shallow rapid infiltrationShallow rapid infiltration Poor well head protectionPoor well head protection Surface water influenceSurface water influence

Microbial Contamination Microbial Contamination SourcesSources

Shallow rapid infiltrationShallow rapid infiltration Nutrient rich waterNutrient rich water Biofouling within the wellBiofouling within the well Distribution system backflowDistribution system backflow

Well MaintenanceWell Maintenance

Exercise (water usage)Exercise (water usage) ChlorinationChlorination

– 200 ppm 200 ppm Record keepingRecord keeping Testing for BacteriaTesting for Bacteria

– Chlorination not recommended for Chlorination not recommended for coliformcoliform

Well MaintenanceWell Maintenance

Landscape so surface water drains away Landscape so surface water drains away from the wellhead from the wellhead

Test YieldTest YieldSpecific CapacitySpecific Capacity

100GPM Withdrawal 100GPM Withdrawal

15’15’ Static WLStatic WL

45’45’ Pumping WLPumping WL

100gpm / (45-15)ft100gpm / (45-15)ft = specific capacity of= specific capacity of 3.3 gpm/ft of drawdown3.3 gpm/ft of drawdown

Specific Capacity of Specific Capacity of a newer wella newer well

65 GPM 65 GPM WithdrawalWithdrawal

15’15’ Static WLStatic WL

65’65’ Pumping WLPumping WL

65gpm / (65-15)ft65gpm / (65-15)ft = specific capacity of= specific capacity of 1.3 gpm/ft of 1.3 gpm/ft of

drawdowndrawdown

Specific Capacity Specific Capacity after 15 yearsafter 15 years

Well CharacterizationWell Characterization

Construction methodConstruction method Water levelsWater levels Casing amount Casing amount Well depthWell depth Pump locationPump location Pumping ratesPumping rates

Well CharacterizationWell Characterization

Water bearing fracturesWater bearing fractures Cascading water zoneCascading water zone Geological structure Geological structure Surface infiltrationSurface infiltration Circulation cell sizeCirculation cell size Dead or non-circulating zonesDead or non-circulating zones

Downhole Video & Downhole Video & PumpingPumping

Observe All Three StagesObserve All Three Stages– Static rest.Static rest.– Pumping stress.Pumping stress.– Recharge.Recharge.

Characterize wellCharacterize well– Construction (leaky casing?)Construction (leaky casing?)– Borehole stabilityBorehole stability– Water zonesWater zones

Video ClipsVideo Clips GeologyGeology BiofoulingBiofouling Oxygen EnrichmentOxygen Enrichment Pumping EffectPumping Effect

Repairs/RehabRepairs/Rehab Cleaning, flow sleeves, recirculation Cleaning, flow sleeves, recirculation

– BiofoulingBiofouling– Mud and SandMud and Sand– Eliminate Eliminate dead zonesdead zones..– Prevent concentration within the well.Prevent concentration within the well.

Liners Liners – Seal out shallow water veins. Seal out shallow water veins. – Pathogenic ContaminatesPathogenic Contaminates– Stabilize the well.Stabilize the well.

Minimize Storage and Enlarge Flow CellsMinimize Storage and Enlarge Flow Cells

Excess storage generates uncontrolled growth of Excess storage generates uncontrolled growth of naturally occurring biofilms naturally occurring biofilms

Enrichment of excess or retained storage Enrichment of excess or retained storage accelerates biofouling from the top downaccelerates biofouling from the top down

Set the pumping depth in a wellSet the pumping depth in a well– based on based on actual maximum demandactual maximum demand– generate 3/4 drawdown or to the water veingenerate 3/4 drawdown or to the water vein

Well StorageWell Storage

Stored water lies Stored water lies – above the intake above the intake – above the highest water zoneabove the highest water zone

Well storage is the zone of a water column within or Well storage is the zone of a water column within or draining to the bore-hole draining to the bore-hole – above the pumpabove the pump– above the most shallow production zoneabove the most shallow production zone– called the called the Storage CellStorage Cell

Water level in a storage type well falls continuously Water level in a storage type well falls continuously during the stress testduring the stress test

Wellhead ProtectionWellhead Protection

Wellhead ProtectionWellhead Protection

– WHPA Delineation MethodsWHPA Delineation Methods Arbitrary fixed or calculated fixed radius methodArbitrary fixed or calculated fixed radius method

ReferencesReferences Anderson, K.E. (1998) Anderson, K.E. (1998) Ground Water Ground Water

Handbook, Handbook, National Ground Water AssociationNational Ground Water Association Driscoll, F.G. (1986) Driscoll, F.G. (1986) Ground Water and WellsGround Water and Wells, ,

Second Edition, Jonhson ScreensSecond Edition, Jonhson Screens Smith, S. A., Borch, M. A., and Noble, L. N. Smith, S. A., Borch, M. A., and Noble, L. N.

(1993(1993) Evaluation and Restoration of Water ) Evaluation and Restoration of Water Supply WellsSupply Wells, AWWA Research Foundation, AWWA Research Foundation

Waller, R.M. (1994) Waller, R.M. (1994) Ground Water and the Ground Water and the Rural HomeownerRural Homeowner, U.S. Geological Survey, U.S. Geological Survey

Presented by Mike VaughtPresented by Mike Vaught

Groundwater and Well Service.Groundwater and Well Service.

441 Northside Drive, Chapel Hill, NC 27516441 Northside Drive, Chapel Hill, NC 27516

Telephone 919-929-8363 Telephone 919-929-8363

Fax 509-278-5724Fax 509-278-5724