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NY Well Driller practice questions

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Question 1Well Siting, Geology, and Hydrogeology

In New York, a drilled well serving a single-family home must be cased and grouted to a minimum depth of how many feet below land surface, unless a lesser depth is approved because of bedrock conditions?

  1. 20 feet Correct answer.
  2. 50 feet
  3. 100 feet
  4. 10 feet

Explanation

New York well construction rules require the upper portion of a drilled well to be cased and grouted to at least 20 feet below land surface for a single-family residence, with deeper casing where unconsolidated material or contamination risk requires it. A variance to a lesser depth is possible only where shallow bedrock or similar conditions make 20 feet impractical.

Question 2Well Siting, Geology, and Hydrogeology

A well is completed in a sand-and-gravel aquifer at 60 feet. The static water level sits at 18 feet and the pump sets at 50 feet. Which statement best describes the aquifer's confined or unconfined character?

  1. The aquifer is artesian because the static level is shallower than the pump setting.
  2. The aquifer is unconfined because the water level defines a free surface within the material. Correct answer.
  3. The aquifer is confined because the well is less than 100 feet deep.
  4. The aquifer is confined because the water rises above the screen.

Explanation

An unconfined aquifer has a water table that rises and falls freely within the saturated material, which matches a static level sitting inside the sand and gravel body. Confined conditions require a low-permeability layer above the aquifer that holds the water under pressure, so the static level would rise above the top of the aquifer.

Question 3Well Siting, Geology, and Hydrogeology

On a topographic map, groundwater flow in a shallow unconfined aquifer generally moves in which direction relative to surface-water features?

  1. Perpendicular to the water-table contours toward the nearest ridge
  2. From streams toward the uplands that recharge them
  3. Parallel to the contour lines and away from streams
  4. From higher water-table elevations toward lower elevations and discharge zones Correct answer.

Explanation

Groundwater flows down the hydraulic gradient, from higher water-table elevation toward lower elevation, and discharge typically occurs at streams, wetlands, and springs. Water-table contours roughly mimic topography, so flow crosses them at right angles toward the low points.

Question 4Well Siting, Geology, and Hydrogeology

A landowner wants a well on a lot where the only practical location is 40 feet from a septic tank and 60 feet from the absorption field. How should the driller respond?

  1. Proceed if the casing is grouted to 50 feet.
  2. Proceed, because the well is more than 25 feet from the tank.
  3. Relocate the well, because separation distances to on-site wastewater systems are not met. Correct answer.
  4. Proceed, because the absorption field is more than 50 feet away.

Explanation

New York isolation distances require a well to be set back substantially farther than 40 feet from a septic tank and generally at least 100 feet from absorption fields and other wastewater components. Grouting does not substitute for the required horizontal separation. The well must be relocated or the wastewater system reconfigured.

Question 5Well Siting, Geology, and Hydrogeology

Which bedrock type in New York is most likely to yield adequate water from fractures and bedding-plane openings rather than from intergranular pore space?

  1. Windblown silt
  2. Shale and sandstone bedrock Correct answer.
  3. Glacial till
  4. Sand and gravel outwash

Explanation

Consolidated sedimentary bedrock such as shale and sandstone stores and transmits water mainly through fractures, joints, and bedding planes because the rock matrix itself has little permeability. Unconsolidated deposits like outwash, till, and windblown silt hold water in the pore spaces between grains.

Question 6Well Siting, Geology, and Hydrogeology

A driller observes that the water level in a new well rises quickly during pumping and then recovers slowly after the pump shuts off. Which condition does this pattern most likely indicate?

  1. A low-permeability formation or a low-yield fracture Correct answer.
  2. A well completed above the water table
  3. A high-yield confined aquifer with strong recharge
  4. An artesian flowing well

Explanation

Slow recovery after pumping indicates that water enters the borehole slowly, which points to low hydraulic conductivity in the surrounding material or a limited fracture supply. A high-yield aquifer would show rapid drawdown and rapid recovery because water moves easily toward the well.

Question 7Well Siting, Geology, and Hydrogeology

What is the primary purpose of a sanitary seal around the upper casing of a drilled well?

  1. To filter sediment from the pumped water
  2. To protect the casing from frost heave
  3. To increase the well's yield by improving recharge
  4. To prevent surface water and shallow contamination from entering the well annulus Correct answer.

Explanation

The sanitary seal, typically grout placed in the annulus around the upper casing, blocks the vertical pathway that would otherwise let surface runoff and shallow contaminated water travel down along the casing into the aquifer. It is a barrier against contamination, not a yield-enhancement or filtration device.

Question 8Well Siting, Geology, and Hydrogeology

A well is drilled on a slope below a barnyard and manure storage area. What siting concern is most significant?

  1. The well will be more likely to encounter bedrock.
  2. Surface runoff carrying contaminants will flow toward the well. Correct answer.
  3. The pump will require a larger pressure tank.
  4. The slope will reduce the static water level.

Explanation

A well located downslope of livestock or manure storage is at risk because runoff and shallow subsurface flow move contaminants toward the low point. Siting should place the well upgradient, with adequate isolation distances, so that drainage does not carry bacteria or nutrients to the wellhead.

Question 9Well Siting, Geology, and Hydrogeology

A well produces water with a noticeable rotten-egg odor. Which condition should the driller suspect first?

  1. Hardness caused by calcium and magnesium
  2. Excessive nitrate from fertilizer
  3. Hydrogen sulfide gas, possibly from sulfate-reducing bacteria or sulfur-bearing material Correct answer.
  4. High iron content in the aquifer

Explanation

A rotten-egg odor is the classic signature of hydrogen sulfide, which can come from sulfate-reducing bacteria in the well or from sulfur-bearing geologic material. Iron produces staining and metallic taste, nitrate is odorless, and hardness produces scale and soap-consumption problems rather than odor.

Question 10Well Siting, Geology, and Hydrogeology

A homeowner reports that the well yield drops sharply every summer while nearby surface streams also run low. Which explanation best fits this observation?

  1. The casing is too deep for the aquifer.
  2. The well is drawing from a deep confined aquifer unaffected by seasons.
  3. The well is hydraulically connected to a shallow aquifer recharged by precipitation. Correct answer.
  4. The pump is undersized for the well depth.

Explanation

Seasonal declines that coincide with low streamflow suggest the well depends on a shallow, unconfined aquifer whose recharge comes from precipitation and infiltration. Deep confined aquifers respond much more slowly to seasonal weather. Matching the well's behavior to surface-water lows is a standard hydrogeologic diagnostic.

Question 11Well Siting, Geology, and Hydrogeology

Which practice best protects a new well from contamination during and after construction?

  1. Sealing the wellhead with a vermin-proof cap and mounding the soil around it Correct answer.
  2. Leaving the annulus open to allow groundwater to drain
  3. Using a shallow pit around the casing to collect runoff
  4. Grading the ground around the wellhead so it slopes toward the casing

Explanation

A properly sealed, vermin-proof well cap and soil mounded to drain away from the casing keep surface water, insects, and small animals out of the well. The ground should slope away from the wellhead, and the annulus must be grouted rather than left open.

Question 12Well Siting, Geology, and Hydrogeology

In a fractured bedrock setting, which well location is most likely to intersect productive water-bearing fractures?

  1. A hilltop capped by dense till
  2. A sandy outwash plain far from bedrock
  3. A broad, flat upland with thick clay soil
  4. A topographic lineament or fault zone with visible surface fracturing Correct answer.

Explanation

In bedrock, water is stored and transmitted mainly in fractures, and fracture zones are often expressed at the surface as lineaments, faults, or joint sets. Siting on or near these features improves the chance of intersecting connected openings. Thick clay or dense till can also mask or seal the bedrock surface.

Question 13Well Siting, Geology, and Hydrogeology

What does a specific capacity value for a well represent?

  1. The total volume of water stored in the aquifer
  2. The pumping rate divided by the drawdown produced by that pumping Correct answer.
  3. The maximum pressure the pump can develop
  4. The depth from land surface to the bottom of the well

Explanation

Specific capacity is calculated as pumping rate divided by drawdown, usually in gallons per minute per foot, and it indicates how efficiently a well produces water for each foot the water level is lowered. Higher values mean the aquifer or fracture system transmits water readily to the well.

Question 14Well Siting, Geology, and Hydrogeology

A driller notes that the static water level in a well is 25 feet below grade and the pumping level stabilizes at 40 feet while producing 15 gallons per minute. What is the approximate specific capacity?

  1. 0.6 gallons per minute per foot
  2. 1.7 gallons per minute per foot
  3. 15 gallons per minute per foot
  4. 1 gallon per minute per foot Correct answer.

Explanation

Drawdown is the difference between the static level and the pumping level, or 40 minus 25 equals 15 feet. Specific capacity is the pumping rate divided by drawdown, so 15 gallons per minute divided by 15 feet equals about 1 gallon per minute per foot.

Question 15Well Siting, Geology, and Hydrogeology

Why is it important to know the direction of groundwater flow before siting a well near a known contamination source?

  1. Flow direction controls the depth to bedrock.
  2. Groundwater always flows toward the nearest property line.
  3. A well placed downgradient of the source is more likely to draw contaminated water. Correct answer.
  4. Flow direction determines the pump horsepower needed.

Explanation

Contaminants travel with groundwater, so a well located downgradient of a source can intercept the plume and pull contaminated water toward the intake. Siting upgradient or outside the capture zone reduces that risk. Flow direction is determined from water-table or potentiometric-surface maps, not from property boundaries.

Question 16Well Siting, Geology, and Hydrogeology

A well is completed in a confined sand aquifer beneath a continuous clay layer. Which observation would confirm the confined condition during drilling?

  1. The water level rises in the casing above the top of the sand. Correct answer.
  2. The well produces less than 5 gallons per minute.
  3. The sand is saturated but the water level stays below the clay.
  4. The clay layer is thin and sandy.

Explanation

In a confined aquifer, the potentiometric surface lies above the top of the aquifer, so water rises in the casing once the confining layer is penetrated. If the water level stays below the top of the sand, the aquifer is behaving as unconfined.

Question 17Well Siting, Geology, and Hydrogeology

Which factor most strongly controls how much drawdown occurs around a pumping well in an unconfined aquifer?

  1. The hydraulic conductivity and saturated thickness of the aquifer Correct answer.
  2. The length of the drop pipe
  3. The diameter of the pump intake
  4. The color of the aquifer material

Explanation

Drawdown for a given pumping rate depends mainly on how readily the aquifer transmits water, which is governed by hydraulic conductivity and saturated thickness, along with boundary conditions and storage. Coarse, thick, permeable material produces less drawdown than fine or thin material.

Question 18Well Siting, Geology, and Hydrogeology

A well site is underlain by limestone with solution channels. What construction concern is most characteristic of this setting?

  1. The aquifer will always be unconfined and shallow.
  2. Rapid movement of surface contaminants through solution openings with little natural filtration. Correct answer.
  3. The water will be uniformly high in hardness but free of bacteria.
  4. The casing will be difficult to drive because limestone is always soft.

Explanation

Solutioned limestone can transmit water rapidly through enlarged fractures and conduits, giving contaminants little chance to be filtered or diluted. Wells in such karst settings require careful siting, casing, and grouting because the same openings that yield water also provide fast pathways from the surface.

Question 19Well Siting, Geology, and Hydrogeology

What is the main hydrogeologic reason to avoid placing a well in a wetland or poorly drained depression?

  1. The water table is too deep there.
  2. The area collects surface water and shallow contamination, and the wellhead may be flooded. Correct answer.
  3. The soil there is too permeable for a well.
  4. Wetlands always overlie bedrock.

Explanation

Wetlands and poorly drained depressions are low points that gather runoff and shallow groundwater, which raises the risk that floodwater and contaminants reach the wellhead. A wellhead should be above expected flood levels and on ground that drains away from the casing.

Question 20Well Siting, Geology, and Hydrogeology

A driller encounters a thick layer of dense glacial till above bedrock. How does till typically affect well siting and yield?

  1. Till is always saturated and acts as a confined aquifer.
  2. Till dissolves readily to form solution channels.
  3. Till is highly permeable and usually yields large quantities of water.
  4. Till is poorly sorted and low in permeability, so it often yields little water and may need to be cased through. Correct answer.

Explanation

Glacial till is an unsorted mixture of clay, silt, sand, and gravel that generally has low permeability and limited water yield. A well may need to be cased through the till to reach a more productive sand-and-gravel unit or bedrock fractures below.

Question 21Well Siting, Geology, and Hydrogeology

Which statement correctly describes the relationship between a cone of depression and nearby wells?

  1. Overlapping cones of depression can cause interference and reduce yield in neighboring wells. Correct answer.
  2. Cones of depression form only in confined aquifers.
  3. The cone of depression is unaffected by pumping rate.
  4. A cone of depression increases the yield of nearby wells.

Explanation

Pumping creates a cone of depression around a well, and where two wells are close enough that their cones overlap, they compete for the same water and experience interference. This can lower water levels and reduce yield in both wells. The size of the cone grows with pumping rate and duration.

Question 22Well Siting, Geology, and Hydrogeology

A driller is asked to site a well on a property where a buried fuel oil tank was removed years ago. What is the most appropriate action before finalizing the location?

  1. Assume the contamination has degraded and proceed.
  2. Evaluate the site for residual contamination and place the well away from and upgradient of the former tank area. Correct answer.
  3. Place the well directly over the former tank to intercept the plume.
  4. Increase the casing depth and ignore the tank location.

Explanation

Former tank sites can leave residual petroleum contamination in soil and groundwater, so the well should be located away from the source and, where possible, upgradient so the capture zone does not draw the plume toward the well. Additional assessment may be needed to confirm safe placement.

Question 23Well Siting, Geology, and Hydrogeology

Two wells are drilled 200 feet apart in the same sand aquifer. Well A produces 20 gallons per minute with 5 feet of drawdown, while Well B produces 20 gallons per minute with 20 feet of drawdown. What does this comparison most likely indicate?

  1. Well B is completed in more permeable material than Well A.
  2. Well B has a larger pressure tank.
  3. Well A is in more permeable material or a more favorable part of the aquifer. Correct answer.
  4. Both wells have identical specific capacity.

Explanation

Specific capacity is rate divided by drawdown, so Well A has about 4 gallons per minute per foot while Well B has about 1 gallon per minute per foot. The higher specific capacity at Well A indicates more permeable material or a more favorable position in the aquifer.

Question 24Well Siting, Geology, and Hydrogeology

A well is planned near a stream that is a gaining stream. What does this imply for groundwater and well siting?

  1. The stream and aquifer are not hydraulically connected.
  2. The well will always be artesian.
  3. Groundwater discharges to the stream, so the water table slopes toward the stream. Correct answer.
  4. The stream loses water to the aquifer, so the well should be placed close to the streambed.

Explanation

A gaining stream receives groundwater discharge, which means the water table near the stream slopes toward it and groundwater flows into the channel. This matters for siting because pumping near the stream can capture stream water and induce infiltration, so the well should be set back appropriately.

Question 25Well Siting, Geology, and Hydrogeology

A driller is evaluating a site where the static water level is 8 feet below grade and the well must be cased to 20 feet. What does the shallow static level most likely suggest about the aquifer?

  1. The aquifer is confined and under high pressure.
  2. The aquifer has no recharge.
  3. The well is dry and will need to be deepened.
  4. The water table is shallow and the well is likely completed in an unconfined aquifer. Correct answer.

Explanation

A static level only 8 feet below grade indicates a shallow water table, which is typical of an unconfined aquifer near a recharge area or low-lying ground. Confined aquifers would show a potentiometric surface that may rise above the top of the aquifer, but the shallow depth alone does not prove confinement.

Question 26Well Siting, Geology, and Hydrogeology

In an unconfined sand-and-gravel aquifer, which property most directly determines how much water the sediment can store and release to a well?

  1. Storativity
  2. Specific yield Correct answer.
  3. Hydraulic conductivity
  4. Transmissivity

Explanation

In an unconfined aquifer, specific yield is the volume of water that drains by gravity from a unit volume of saturated material, and it governs how much water is actually released as the water table declines. Hydraulic conductivity describes ease of flow rather than drainable storage, and transmissivity combines conductivity with saturated thickness. Storativity of an unconfined aquifer is numerically close to specific yield but is a dimensionless aquifer-scale term.

Question 27Well Siting, Geology, and Hydrogeology

A driller is siting a well in a valley underlain by fractured metamorphic bedrock with only a thin soil cover. Which setting offers the best chance of intersecting a productive water-bearing fracture zone?

  1. A broad flat hilltop capped by clay-rich soil
  2. A uniform gentle slope with no visible surface lineaments
  3. A thick, homogeneous till plain far from any bedrock outcrop
  4. A lineament or topographic saddle aligned with a regional fracture trend Correct answer.

Explanation

In fractured crystalline bedrock, groundwater is stored and transmitted almost entirely in fractures, and fracture zones commonly follow regional joint and fault trends that appear as lineaments or as topographic saddles and swales. Siting on or near such a mapped lineament improves the odds of hitting an open, connected fracture. Uniform slopes and thick till plains lack these structural clues and often yield poorly.

Question 28Well Siting, Geology, and Hydrogeology

A well is completed in a sand aquifer confined beneath a continuous clay layer, and the driller notes that the water level in the casing stands well above the top of the sand. Which interpretation of this observation is correct?

  1. The well has been over-pumped and the water level is still recovering
  2. The clay layer is leaking and the casing is hydraulically short-circuited
  3. The well is artesian because the confined aquifer's potentiometric surface stands above the confining layer Correct answer.
  4. The aquifer is unconfined and the water table lies above the sand

Explanation

When a sand is confined by a continuous low-permeability layer, the water in the aquifer is under pressure and rises in a well to the potentiometric surface. If that surface stands above the top of the aquifer, the well is artesian and may flow if the surface is above land. The observation reflects confining pressure, not pumping recovery or aquifer leakage.

Question 29Well Siting, Geology, and Hydrogeology

A property owner wants a well placed in a poorly drained wetland depression at the foot of a slope. What is the primary hydrogeologic reason to avoid this location?

  1. A wetland guarantees that the aquifer is confined
  2. Wetland soils are too hard to drill through
  3. Wetlands always overlie bedrock with no fractures
  4. Standing surface water indicates the water table is at land surface, so the well would be shallow and highly vulnerable to surface contamination Correct answer.

Explanation

In a wetland or poorly drained depression the water table is at or near land surface, so a well there is shallow, low-yield, and in direct hydraulic connection with surface water and any contaminants it carries. Shallow groundwater also responds quickly to rainfall and drought. Better siting moves the well upslope and away from surface water ponding.

Question 30Well Siting, Geology, and Hydrogeology

A driller must set a well screen in a stratified sand and gravel aquifer where two layers differ sharply in grain size. Which screen placement best limits pumping-induced movement of fine sediment into the well?

  1. Across the finest layer only, so the screen is fully surrounded by fine material
  2. Across the boundary between layers, so both zones contribute equally
  3. Across the coarsest layer only, so the well draws from the most permeable zone regardless of fines
  4. In the coarse layer, with a filter pack graded to the finer adjacent material to prevent fines from migrating Correct answer.

Explanation

Screen and filter-pack design must account for the finest material the well will draw from, because pumping gradients move fines toward the screen. A pack graded to the finer adjacent layer stabilizes that material and still admits water from the coarse zone. Screening the finest layer alone or straddling the boundary concentrates fines and encourages clogging and sand production.

Question 31Well Design and Construction

Under New York well construction rules, what is the minimum required thickness of the annular seal (grout) around the casing of a new drilled well?

  1. 3 inches
  2. 2 inches Correct answer.
  3. 1 inch
  4. 6 inches

Explanation

New York requires a minimum annular seal thickness of 2 inches between the borehole wall and the well casing for a drilled well. The seal must extend continuously from the bottom of the casing up to the ground surface or to the pitless adapter seal. This thickness is intended to prevent surface and shallow groundwater from migrating down the annulus.

Question 32Well Design and Construction

What is the primary purpose of the grout seal in a newly constructed water well?

  1. To support the weight of the drop pipe
  2. To increase the well yield by widening the borehole
  3. To prevent contamination from entering the well along the casing annulus Correct answer.
  4. To lubricate the pump during operation

Explanation

The grout seal forms a continuous, impermeable barrier in the annular space between the casing and the borehole wall. Its purpose is to stop surface water, shallow groundwater, and contaminants from traveling down the annulus into the producing zone. Grout does not increase yield or perform any mechanical support function for the pump.

Question 33Well Design and Construction

A driller completes a well in a bedrock aquifer and installs casing to a depth of 60 feet through overburden. What is the required minimum length of the grout seal in this situation?

  1. 20 feet
  2. 10 feet
  3. 100 feet
  4. 60 feet Correct answer.

Explanation

Where casing is set into bedrock, the annular seal must extend from the bottom of the casing to the ground surface, so the full cased interval of 60 feet must be grouted. A partial seal would leave the lower annulus open to shallow water and contamination. Sealing the entire cased length is the standard practice for bedrock wells.

Question 34Well Design and Construction

Which casing material is generally prohibited for use in potable water wells in New York because it cannot reliably form a watertight, durable seal?

  1. Corrugated metal pipe Correct answer.
  2. Stainless steel
  3. Galvanized steel
  4. Polyvinyl chloride (PVC)

Explanation

Corrugated metal pipe has seams and corrugations that make it very difficult to seal and it corrodes rapidly, so it is not accepted as well casing for potable supplies. PVC, galvanized steel, and stainless steel are all recognized casing materials when properly installed. The key issue is the ability to maintain a watertight barrier over the life of the well.

Question 35Well Design and Construction

For a well with 6-inch diameter casing, what is the minimum required height that the casing must extend above the finished ground surface (or floor of a pit) to prevent surface water entry?

  1. 6 inches
  2. 18 inches
  3. 36 inches
  4. 12 inches Correct answer.

Explanation

Well casing must extend at least 12 inches above the finished grade or the floor of a well pit so that surface water cannot flow into the well. The extension also protects the wellhead from shallow flooding. This minimum height is a standard wellhead protection requirement.

Question 36Well Design and Construction

What is the function of a pitless adapter in a well installation?

  1. To increase the pumping rate by reducing friction in the drop pipe
  2. To allow the driller to measure static water level
  3. To filter sediment from the water before it enters the pump
  4. To provide a watertight connection through the casing below the frost line while allowing the well to be sealed at the top Correct answer.

Explanation

A pitless adapter makes a watertight connection through the well casing below the frost line so the discharge line can run underground to the building. It allows the top of the well to be sealed with a sanitary well cap, eliminating the need for a pit. It does not filter water, boost pumping rate, or serve as a measuring device.

Question 37Well Design and Construction

Which well screen slot size is most appropriate for a uniform fine sand aquifer where the goal is to retain most of the formation material?

  1. A slot size that retains the formation material while allowing fines to be developed out Correct answer.
  2. A slot size larger than the majority of the sand grains
  3. A slot size selected only by casing diameter
  4. A slot size equal to the largest grain in the formation

Explanation

Screen slot size is selected so that the screen retains the aquifer material while finer particles are removed during well development, creating a natural filter pack around the screen. Choosing a slot larger than most grains would allow the formation to pass into the well. Slot size is based on grain-size analysis, not casing diameter or the largest grain alone.

Question 38Well Design and Construction

A driller is designing a well in an unconsolidated sand and gravel aquifer. Which design element is used to prevent fine formation material from entering the well?

  1. A gravel pack placed around the screen Correct answer.
  2. An oversized pump intake
  3. A shorter casing string
  4. A larger drop pipe

Explanation

A gravel pack is placed in the annulus around the screen to create a graded filter that holds back fine formation material while allowing water to enter. The pack is sized relative to the aquifer grain size so the formation is stabilized. Drop pipe size, casing length, and pump intake have no filtering function.

Question 39Well Design and Construction

What is the purpose of developing a newly constructed well after drilling and screen installation?

  1. To raise the static water level
  2. To remove drilling fluid and fines from the aquifer and screen so the well produces clear water at design capacity Correct answer.
  3. To increase the well's structural strength
  4. To sterilize the aquifer permanently

Explanation

Well development removes drilling mud, additives, and fine particles from the screen and surrounding formation so water can flow freely into the well. Proper development yields clear water and improves specific capacity. It does not strengthen the structure, sterilize the aquifer permanently, or raise the static water level.

Question 40Well Design and Construction

Which method is commonly used to develop a well completed in a consolidated rock formation with a low yield?

  1. Surge blocking with a plunger only
  2. High-pressure water jetting or hydraulic fracturing of the borehole Correct answer.
  3. Backfilling the borehole with gravel
  4. Increasing the casing diameter after completion

Explanation

In consolidated rock, development often relies on high-pressure water jetting or hydraulic fracturing to open and clean fractures that supply water. These methods dislodge drilling cuttings and debris from fractures and can improve yield. Surge blocking is used mainly in screen wells, and backfilling or resizing casing after completion is not a development method.

Question 41Well Design and Construction

What is the required minimum diameter of the borehole relative to the casing when a 2-inch annular seal is specified?

  1. Casing diameter plus 1 inch total
  2. Equal to the casing diameter
  3. Casing diameter plus 4 inches total Correct answer.
  4. Casing diameter plus 2 inches total

Explanation

A 2-inch annular seal all around the casing requires 2 inches of clearance on each side, so the borehole must be 4 inches larger in diameter than the casing. For example, 6-inch casing requires a 10-inch borehole. A borehole equal to casing diameter would leave no room for grout.

Question 42Well Design and Construction

What is the purpose of a sanitary well cap on a completed well?

  1. To provide a vermin-proof and watertight seal at the top of the casing while allowing a screened vent Correct answer.
  2. To increase the pressure in the well
  3. To allow surface water to drain into the well
  4. To vent the well to the atmosphere freely

Explanation

A sanitary well cap seals the top of the casing against insects, rodents, and surface water while including a screened vent to equalize pressure. It must be watertight but vented so the well can breathe. It does not increase pressure or permit water to drain in.

Question 43Well Design and Construction

A driller encounters a confining layer and must case off an upper contaminated aquifer to complete the well in a deeper clean aquifer. Which construction approach best accomplishes this?

  1. Set casing through the confining layer and grout the annulus to the surface Correct answer.
  2. Install a screen across both aquifers
  3. Leave the borehole uncased below the contaminated zone
  4. Set a short surface casing only to 10 feet

Explanation

Casing must extend through the contaminated zone and the confining layer, with the annulus grouted to the surface, to isolate the upper aquifer from the completed interval. This prevents the contaminated water from migrating down the borehole. Short surface casing, uncased borehole, or a screen spanning both zones would allow cross-contamination.

Question 44Well Design and Construction

What does the term 'static water level' refer to in well design and testing?

  1. The level at which water overflows the casing
  2. The level of water in the well when the pump is running at full capacity
  3. The level of water in the well when it is not being pumped and has stabilized Correct answer.
  4. The depth at which the pump intake is set

Explanation

Static water level is the stabilized water level in a well when no pumping is occurring and the water has recovered to equilibrium. It is measured from a reference point such as the top of the casing. Pumping water level, by contrast, is the drawn-down level during operation.

Question 45Well Design and Construction

A well has a static water level of 40 feet and a pumping water level of 70 feet at a yield of 10 gallons per minute. What is the specific capacity of the well?

  1. 0.33 gallons per minute per foot of drawdown Correct answer.
  2. 2 gallons per minute per foot of drawdown
  3. 3 gallons per minute per foot of drawdown
  4. 0.5 gallons per minute per foot of drawdown

Explanation

Specific capacity equals yield divided by drawdown. Drawdown is 70 minus 40, or 30 feet, so 10 gpm divided by 30 feet equals 0.33 gpm per foot of drawdown. This value indicates how efficiently the well produces water per unit of drawdown.

Question 46Well Design and Construction

Which condition most strongly indicates that a well screen should be installed with a filter pack rather than as a natural-pack screen?

  1. A fine, poorly sorted sand formation with significant fines Correct answer.
  2. A uniform coarse gravel formation with minimal fines
  3. A hard, fractured granite formation
  4. A formation composed of large cobbles

Explanation

A filter pack is used when the formation is fine and poorly sorted, because a natural-pack screen alone cannot retain the material effectively. A properly graded gravel pack stabilizes the formation and prevents sand production. Coarse uniform gravel, fractured granite, and cobble formations do not require a filter pack.

Question 47Well Design and Construction

What is the minimum required thickness of the grout seal for a well constructed in unconsolidated material where the casing is not set into bedrock?

  1. 6 inches
  2. 8 inches
  3. 4 inches
  4. 2 inches Correct answer.

Explanation

The annular seal must be at least 2 inches thick around the casing in unconsolidated formations, just as in bedrock wells. This thickness ensures a continuous barrier against vertical migration of water. Greater thicknesses may be used but are not the minimum requirement.

Question 48Well Design and Construction

Which of the following best describes the purpose of a well casing in a drilled well?

  1. To increase the natural yield of the aquifer
  2. To measure the pumping rate of the well
  3. To filter sediment from the water before it reaches the pump
  4. To keep the borehole open and prevent collapse while providing a sealed conduit for the pump and water Correct answer.

Explanation

Casing holds the borehole open, prevents the formation from collapsing into the well, and provides a sealed conduit that protects the water from contamination. Filtration is the role of the screen and gravel pack, not the casing. Casing does not increase aquifer yield or measure pumping rate.

Question 49Well Design and Construction

When grouting a well with neat cement, what is a key reason to place the grout from the bottom up using a tremie pipe?

  1. To speed up the grouting process
  2. To prevent voids and bridging by displacing water upward as grout rises Correct answer.
  3. To allow the grout to cure faster
  4. To reduce the amount of grout needed

Explanation

Pumping grout from the bottom up through a tremie pipe displaces water and fills the annulus continuously, preventing voids, bridging, and dilution. Pouring grout from the top can trap water and create gaps in the seal. The method is about seal integrity, not speed or material savings.

Question 50Well Design and Construction

A driller plans a well in an area where the static water level is 15 feet below grade and the pump must be set 100 feet deep. Which pump type is generally best suited for this deep setting?

  1. A deep-well submersible pump Correct answer.
  2. A hand pump
  3. A shallow-well jet pump
  4. A centrifugal pump mounted at the surface

Explanation

A deep-well submersible pump is designed to be set below the water level at significant depths and pushes water to the surface. Shallow-well jet pumps and surface centrifugal pumps lose suction capacity beyond about 25 feet. A hand pump is not suited to a 100-foot setting for normal supply.