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Question 1Well Construction and Compliance

Under Oregon well construction rules, a new well must be cased and the annular space sealed to prevent which of the following?

  1. Corrosion of the submersible motor windings
  2. Thermal expansion of the pump column
  3. Settlement of the pump base plate
  4. Migration of surface water and shallow groundwater along the borehole Correct answer.

Explanation

Casing and annular sealing exist primarily to prevent surface water and shallow, potentially contaminated groundwater from moving down the borehole and mixing with the producing aquifer. This protects both water quality and the hydraulic integrity of the well. Pump hardware issues are unrelated to the purpose of the annular seal.

Question 2Well Construction and Compliance

What is the primary purpose of the sanitary seal (well seal) at the top of a completed well?

  1. To prevent contaminants and surface water from entering the well at the casing head Correct answer.
  2. To support the weight of the entire casing string
  3. To increase the yield of the aquifer
  4. To measure the static water level in the well

Explanation

The sanitary seal closes the gap between the casing and the pump piping or wiring so that surface water, insects, and debris cannot enter the well. It is a contamination barrier at the wellhead. It does not carry the casing load, measure water level, or change aquifer yield.

Question 3Well Construction and Compliance

A driller is installing a pitless adapter. What is its main function?

  1. To anchor the drop pipe against torque
  2. To provide a watertight, frost-free connection through the casing below the frost line Correct answer.
  3. To filter sediment from the produced water
  4. To measure pump discharge pressure

Explanation

A pitless adapter passes the discharge line through the casing wall below the frost line, keeping the connection watertight and protecting it from freezing. It also allows the pump to be serviced without excavating a pit. It does not filter water or measure pressure.

Question 4Well Construction and Compliance

Why must the annular space between the borehole wall and the casing be grouted with an approved material rather than backfilled with drill cuttings?

  1. Grout forms a continuous low-permeability barrier, while cuttings can leave permeable channels Correct answer.
  2. Grout is required only to lubricate the casing during installation
  3. Grout increases the casing's collapse strength
  4. Cuttings are prohibited because they are too heavy for the casing

Explanation

Approved grout sets into a continuous, low-permeability seal that blocks vertical water movement along the annulus. Drill cuttings are permeable and can bridge, leaving channels that allow contamination to travel. Grout is not specified for lubrication or to strengthen the casing.

Question 5Well Construction and Compliance

A driller completes a well and must submit a well report (well log). Which information is required on that report?

  1. The homeowner's mortgage lender
  2. The retail price of the pump installed
  3. The driller's personal tax identification number
  4. Depth and diameter of the borehole, casing and screen details, and static water level Correct answer.

Explanation

The well report documents the construction record: borehole depth and diameter, casing and screen specifications, grout placement, and the static water level, among other construction details. These data let regulators and future owners understand the well's construction. Personal financial information is not part of the construction record.

Question 6Well Construction and Compliance

Which practice best protects a newly completed well from surface contamination before the pump is installed?

  1. Leaving the casing open to allow air circulation
  2. Removing the sanitary seal to speed installation
  3. Filling the casing with clean gravel
  4. Securing a temporary watertight cap over the casing Correct answer.

Explanation

A temporary watertight cap keeps surface water, debris, and small animals out of the casing until the permanent seal and pump are in place. Open casing is a direct pathway for contamination. Gravel fill and removing the seal would defeat the protective purpose.

Question 7Well Construction and Compliance

Oregon requires that a well be disinfected after construction. What is the purpose of this disinfection?

  1. To increase the well's specific capacity
  2. To dissolve mineral scale from the screen
  3. To neutralize hydrogen sulfide permanently
  4. To reduce bacterial contamination introduced during drilling and installation Correct answer.

Explanation

Construction activities introduce bacteria into the well, and disinfection reduces that contamination before the well is placed in service. It is a public health measure. Disinfection does not remove mineral scale, improve specific capacity, or permanently eliminate hydrogen sulfide.

Question 8Well Construction and Compliance

A well is being constructed in an area with a known shallow contamination plume. Which construction element most directly limits downward migration of that contamination along the borehole?

  1. A longer drop pipe
  2. A larger pump motor
  3. A properly placed annular seal extending above the contaminated zone Correct answer.
  4. A pressure tank with greater capacity

Explanation

The annular seal must extend above the contaminated zone to block vertical migration along the outside of the casing. The seal is the barrier that isolates the borehole from the shallow plume. Pump, piping, and tank choices do not affect contaminant migration.

Question 9Well Construction and Compliance

A driller is setting casing through a confining layer to seal off a shallow aquifer. Which installation detail is most important to achieving an effective seal?

  1. Grouting only the upper five feet of the annulus
  2. Using the largest available drill bit for the borehole
  3. Pulling the casing back slightly after grouting
  4. Centering the casing in the borehole so grout forms a uniform annular thickness Correct answer.

Explanation

Centering the casing with centralizers helps ensure a continuous, uniform grout column with no thin or missing sections. A non-centered casing can leave a wide channel on one side that compromises the seal. Over-sizing the borehole, pulling casing, or grouting only the top do not achieve a full seal.

Question 10Well Construction and Compliance

During grouting with a positive-displacement pump, the driller observes grout returning at the surface before the calculated volume is placed. What is the most appropriate response?

  1. Stop grouting and backfill the annulus with cuttings
  2. Add water to the grout to make it flow farther
  3. Assume the seal is complete and proceed to pump installation
  4. Investigate for a bridge, lost circulation zone, or casing break before accepting the seal Correct answer.

Explanation

Early grout return can indicate bridging, a lost-circulation zone taking grout, or a breach in the casing. These conditions mean the intended annular column may not exist, so the driller must diagnose the cause before accepting the seal. Proceeding, thinning the mix, or backfilling with cuttings would leave an inadequate barrier.

Question 11Well Construction and Compliance

A well screen is selected for a sand-and-gravel aquifer. Which screen slot size is generally appropriate?

  1. A slot smaller than the finest silt particles present
  2. The largest slot available to maximize open area
  3. A slot equal to the median grain size of the formation
  4. A slot size that retains most of the formation material while allowing adequate flow Correct answer.

Explanation

Screen slot size is chosen so the formation (or gravel pack) is retained while water flows freely, typically based on sieve analysis of the formation sample. This prevents sand production and pump damage. Oversized slots pass formation material, while an extremely fine slot can plug or restrict flow.

Question 12Well Construction and Compliance

What is the purpose of a gravel pack around a well screen?

  1. To reduce the depth required for the borehole
  2. To increase the collapse strength of the casing
  3. To provide a reservoir of chlorinated water for disinfection
  4. To stabilize the formation and filter finer particles before they reach the screen Correct answer.

Explanation

A properly sized gravel pack supports the formation and acts as a filter, holding back fines so the screen and pump are protected. It improves well efficiency in many unconsolidated formations. It does not strengthen casing, store disinfectant, or reduce required depth.

Question 13Well Construction and Compliance

A driller must abandon a well that is no longer usable. Which approach satisfies the intent of well abandonment rules?

  1. Fill the borehole with an approved sealing material across all permeable zones and seal the top Correct answer.
  2. Fill only the top ten feet with soil
  3. Remove the pump and leave the casing in place unsealed
  4. Cap the casing and leave the borehole open below

Explanation

Abandonment requires sealing the borehole so it cannot serve as a vertical pathway for water between aquifers. Approved sealing material placed across permeable zones, plus a surface seal, accomplishes that. Capping, shallow soil fill, or leaving casing unsealed leaves a conduit.

Question 14Well Construction and Compliance

Why must a driller avoid connecting two aquifers of different water quality through a single wellbore without proper sealing?

  1. It reduces the pump's electrical efficiency
  2. It increases the casing's thermal expansion
  3. It makes the well report harder to complete
  4. The connection can allow poorer-quality water to migrate into the better aquifer Correct answer.

Explanation

An unsealed borehole can act as a conduit that lets water from one aquifer move into another, degrading water quality. Sealing between aquifers preserves the natural separation. Electrical efficiency, thermal expansion, and reporting are not the concern.

Question 15Well Construction and Compliance

A well produces noticeable sand shortly after development. Which condition is most likely responsible?

  1. The static water level is too high
  2. Screen slot size or gravel pack is too coarse for the formation Correct answer.
  3. The sanitary seal is too tight
  4. The pump is set too shallow

Explanation

Sand production usually indicates that the screen or gravel pack does not retain the formation material, so fines and sand enter the well. The fix involves reviewing the sieve analysis and screen selection. Water level, pump setting depth, and seal tightness do not cause sand entry in this way.

Question 16Well Construction and Compliance

Which factor most directly determines the required casing diameter for a new domestic well?

  1. The color of the casing
  2. The pump and drop pipe size plus clearance needed for installation and future service Correct answer.
  3. The size of the pressure tank
  4. The depth of the frost line

Explanation

Casing diameter must accommodate the pump, drop pipe, wiring, and any future service needs while leaving adequate clearance. This is a hydraulic and mechanical sizing decision. Casing color, frost depth, and tank size do not set the casing diameter.

Question 17Well Construction and Compliance

A driller is developing a new well after completion. What is the purpose of well development?

  1. To increase the casing wall thickness
  2. To sterilize the well permanently
  3. To set the final pump depth
  4. To remove drilling fluids and fines and improve the hydraulic connection to the aquifer Correct answer.

Explanation

Development removes drilling mud, cuttings, and fines from the screen and near-well formation, improving flow into the well. It is a hydraulic and mechanical cleaning process. It does not sterilize the well, change casing thickness, or determine pump depth.

Question 18Well Construction and Compliance

A driller encounters a lost-circulation zone while drilling and plans to grout the casing. What is the most significant risk to the seal?

  1. The casing may become magnetized
  2. Grout may flow into the formation instead of filling the annulus Correct answer.
  3. The pump may run backward
  4. The water level may rise permanently

Explanation

In a lost-circulation zone, grout can escape into the formation rather than rising up the annulus, leaving gaps in the seal. The driller must account for this with appropriate grout volume, methods, or additives. Magnetism, pump rotation, and permanent water-level rise are not the concern.

Question 19Well Construction and Compliance

Which wellhead arrangement best prevents surface water from ponding against the casing?

  1. Casing terminated below grade with no seal
  2. A concrete apron sloped away from the casing with the casing extending above grade Correct answer.
  3. A flat apron sloped toward the casing
  4. A loose-fitting cap resting on the casing

Explanation

A sloped concrete apron sheds surface water away from the wellhead, and casing extending above grade keeps the seal above ponding water. Together these details protect the wellhead from contamination. Sloping toward the casing, terminating below grade, or using a loose cap does the opposite.

Question 20Well Construction and Compliance

A driller is asked to deepen an existing well. Which consideration is most important before proceeding?

  1. Verifying that the existing casing and seal can be extended without leaving an unsealed annulus Correct answer.
  2. Measuring the pressure tank precharge
  3. Confirming the pump warranty remains valid
  4. Checking the color of the existing casing

Explanation

Deepening requires extending the casing and re-establishing the annular seal so the well does not become an unsealed conduit between zones. The construction integrity of the seal is the controlling concern. Warranty, casing color, and tank precharge do not govern the construction decision.

Question 21Well Construction and Compliance

A driller observes that the static water level in a new well is significantly higher than the level recorded during drilling. Which explanation is most plausible?

  1. The well was drilled under artesian or confined conditions and equilibrated after completion Correct answer.
  2. The aquifer was completely dewatered
  3. The casing was installed upside down
  4. The grout increased the aquifer's permeability

Explanation

In a confined or artesian aquifer, the water level rises after drilling as the aquifer equilibrates, sometimes above the ground surface. A dewatered aquifer would show a lower level, and casing orientation or grout permeability do not explain a rising level.

Question 22Well Construction and Compliance

A well completed in a fractured bedrock aquifer is being evaluated. Which construction feature is most important for preventing surface water from moving down along the outside of the casing?

  1. A larger pressure tank
  2. A grouted annular seal from the surface down to competent bedrock Correct answer.
  3. A higher-capacity pump
  4. A longer screen section in the bedrock fractures

Explanation

In bedrock wells, the critical barrier is a grouted seal from the surface to competent rock, which blocks surface water from traveling down the annulus into fractures. Screen length, tank size, and pump capacity affect production, not the surface-water barrier.

Question 23Well Construction and Compliance

A driller is evaluating whether a proposed grout mix will provide an adequate annular seal in a borehole with a large washout. Which property is most relevant?

  1. The grout's electrical conductivity
  2. The set grout's permeability and its ability to remain stable and not shrink Correct answer.
  3. The grout's color after curing
  4. The grout's odor

Explanation

An effective seal depends on the set grout having low permeability and remaining stable without shrinking or cracking, which could open a channel. Color, conductivity, and odor do not indicate sealing performance.

Question 24Well Construction and Compliance

A driller must decide between a naturally developed well and a gravel-packed well in a fine, uniform sand aquifer. Which reasoning is most defensible?

  1. A gravel pack should be avoided because it increases sand entry
  2. Natural development is always preferred regardless of formation
  3. A gravel pack with properly sized filter material is generally preferred because fine uniform sand is difficult to stabilize by natural development Correct answer.
  4. The choice depends mainly on the pressure tank size

Explanation

Fine, uniform sands are prone to sand production and are hard to stabilize by natural development alone, so an artificial gravel pack with filter material sized to the formation is typically preferred. Natural development is not universally superior, gravel packs reduce rather than increase sand entry, and tank size is irrelevant.

Question 25Well Construction and Compliance

A well report shows a screen set across two aquifers separated by a thin clay layer. Why is this design potentially problematic?

  1. It eliminates the need for a sanitary seal
  2. It increases the screen's open area, which is always undesirable
  3. The screen may allow the two aquifers to mix, and the thin clay layer may not provide a reliable natural seal Correct answer.
  4. It reduces the pump's head requirement

Explanation

Screening across a thin confining layer can hydraulically connect two aquifers and allow mixing of waters of differing quality, and the thin clay may not seal reliably. Open area is generally beneficial, head requirements are unrelated, and the sanitary seal is still required.

Question 26Well Construction and Compliance

Under Oregon well construction rules, which party is responsible for submitting the well report (well log) for a newly drilled water supply well?

  1. The licensed water well constructor who drilled the well Correct answer.
  2. The local county sanitarian who inspects the site
  3. The pump installer who later sets the pump
  4. The property owner who contracted the work

Explanation

Oregon requires the licensed well constructor who performs the drilling to file the well report with the state water resources agency, typically within a set number of days after completion. The obligation follows the drilling contractor, not the landowner or a later pump installer, because the driller holds the construction records.

Question 27Well Construction and Compliance

What is the minimum required separation distance in Oregon between a new water supply well and a septic tank absorption field (drainfield)?

  1. 100 feet Correct answer.
  2. 200 feet
  3. 50 feet
  4. 25 feet

Explanation

Oregon sets a 100-foot minimum horizontal separation between a water supply well and a septic system absorption field to reduce the risk of bacteriological and nitrate contamination. Lesser distances apply to some other sanitary facilities, but drainfields require the larger buffer.

Question 28Well Construction and Compliance

A driller is about to grout the annular space of a cased well. Which grout placement method is generally required to ensure a continuous seal from the bottom of the seal upward?

  1. Dumping bentonite pellets from the top in stages
  2. Pouring dry cement from the surface into the annulus
  3. Backfilling with drill cuttings and tamping them
  4. Tremie or positive-displacement pumping from the bottom up Correct answer.

Explanation

Placing grout from the bottom upward by tremie or positive-displacement pump displaces the drilling fluid and prevents voids, bridging, and dilution. Surface pouring or dumping allows the material to bridge and leaves unsealed intervals.

Question 29Well Construction and Compliance

Which casing material is most commonly required for a public water supply well in Oregon when corrosion resistance and structural strength are both priorities?

  1. Steel casing meeting specified wall thickness Correct answer.
  2. Concrete tile casing
  3. Corrugated metal culvert pipe
  4. PVC casing of any schedule

Explanation

Oregon requires steel casing of a specified minimum wall thickness for public water supply wells, providing the strength and durability needed for long-term service. PVC is allowed in some settings but is not the specified material where the rules call for steel.

Question 30Well Construction and Compliance

A driller finishes a well and must disinfect it before the pump is installed. Which chlorine concentration and contact approach is typically used for a new well?

  1. A 500 mg/L solution held for 1 hour
  2. A 200 mg/L solution held for 24 hours Correct answer.
  3. A 50 mg/L solution held for 30 minutes
  4. A 100 mg/L solution held for 2 hours

Explanation

New well disinfection commonly uses a strong chlorine dose of about 200 mg/L held for at least 24 hours, allowing the solution to contact the casing, screen, and gravel pack. Shorter or weaker exposures may not adequately disinfect the well components.

Question 31Well Construction and Compliance

Which document must a licensed well constructor keep and make available that records the details of each well drilled, including depth, casing, and formations encountered?

  1. A water right certificate
  2. A building permit
  3. A property deed
  4. A well report (well log) filed with the state Correct answer.

Explanation

The well report, often called the well log, records construction details such as total depth, casing size and depth, screen settings, and formations penetrated. It is the driller's required record and is filed with the state water resources agency.

Question 32Well Construction and Compliance

When a well is completed, the casing must extend a minimum height above the finished ground surface to prevent surface water from entering. What is the typical required height?

  1. 24 inches
  2. 48 inches
  3. 6 inches
  4. 12 inches Correct answer.

Explanation

Oregon requires the well casing to extend at least 12 inches above the finished ground surface, and the ground should slope away from the casing. This height and slope keep surface water from running into the well.

Question 33Well Construction and Compliance

Which of the following is a required element of a well's sanitary seal at the surface?

  1. A concrete or bentonite seal around the casing at the ground surface Correct answer.
  2. A layer of gravel placed around the casing
  3. An open annular space to allow groundwater to drain
  4. A metal cap left loose to vent the well

Explanation

A sanitary seal of concrete or bentonite around the casing at the surface blocks surface water and shallow contamination from moving down the annulus. The seal must be continuous and properly sloped to shed water.

Question 34Well Construction and Compliance

A driller is constructing a well near a river and must maintain a required setback from the surface water body. Which distance is typically required in Oregon between a well and a stream or river?

  1. 25 feet
  2. 100 feet Correct answer.
  3. 200 feet
  4. 50 feet

Explanation

Oregon generally requires a 100-foot setback between a water supply well and surface water such as a river or stream to reduce contamination risk and protect the well from floodwater. The distance is measured horizontally from the high-water mark.

Question 35Well Construction and Compliance

During construction, a driller encounters an artesian condition where water flows at the surface. Which construction measure is most important to control the flow and protect the well?

  1. Allow the well to flow freely until the aquifer drains
  2. Install a flow control valve and extend casing above the piezometric level Correct answer.
  3. Cap the well and stop construction permanently
  4. Backfill the well with gravel to slow the flow

Explanation

An artesian well must be controlled with a valve and casing extended above the pressure level so the flow can be managed and the well sealed properly. Allowing uncontrolled flow wastes water and can undermine the seal and neighboring wells.

Question 36Well Construction and Compliance

A driller is installing a pitless adapter. What is the primary purpose of this device?

  1. To filter sediment from the produced water
  2. To provide a watertight connection through the casing below the frost line Correct answer.
  3. To measure the static water level in the well
  4. To increase the pumping rate of the well

Explanation

A pitless adapter makes a watertight connection through the well casing below the frost line, allowing the discharge line to exit without a pit. This protects the water from surface contamination and prevents freezing.

Question 37Well Construction and Compliance

A driller plans to grout the annular space of a well with a large washed-out borehole. Which grout property is most important to ensure a complete seal in this situation?

  1. Low viscosity so it flows easily through the annulus
  2. High sand content to reduce cost
  3. High density and low water loss to resist dilution and bridging Correct answer.
  4. Rapid set time to harden before the drill string is removed

Explanation

In a large or washed-out borehole, grout must be dense and resistant to water loss so it does not dilute or bridge and can fill the entire annulus. A properly designed mix maintains volume and continuity throughout the seal.

Question 38Well Construction and Compliance

A driller must decide whether to use a surface seal or a full-length annular seal for a well completed in a confined aquifer. Which factor most directly determines the required seal length?

  1. The depth and number of aquifers to be isolated Correct answer.
  2. The type of pump to be installed
  3. The owner's preference for casing material
  4. The color of the formation cuttings

Explanation

Seal length is governed by the need to isolate aquifers and prevent cross-contamination between water-bearing zones. Where multiple aquifers or a confining layer must be protected, the seal must extend to the required depth.

Question 39Well Construction and Compliance

A driller is completing a well in a bedrock formation and must decide how to seal the annular space above the bedrock. Which approach best protects groundwater?

  1. Install a screen above the bedrock and leave it open
  2. Grout the annulus from the top of the bedrock seal to the surface Correct answer.
  3. Leave the annulus open to allow bedrock fractures to drain
  4. Fill the annulus with drill cuttings only

Explanation

In bedrock wells, the annular space above the bedrock seal must be grouted continuously to the surface to prevent surface water and shallow groundwater from entering. An open annulus would allow contamination to travel down to the producing fractures.

Question 40Well Construction and Compliance

A driller is asked to install a well for a public water system. Which approval must be obtained before construction begins?

  1. A building permit from the county only
  2. A septic system permit from the local health department
  3. A water right permit from the irrigation district
  4. A water supply well construction permit from the state Correct answer.

Explanation

Public water supply wells require a construction permit from the state before drilling, ensuring the design meets public health standards. Other permits may apply but do not substitute for the state well construction approval.

Question 41Well Construction and Compliance

A driller observes that the casing is not centered in the borehole, leaving a wide annulus on one side. Which consequence is most likely if grouting proceeds without correction?

  1. An incomplete seal on the wide side that may allow contamination to migrate Correct answer.
  2. Reduced casing strength from the offset
  3. A higher static water level in the well
  4. Improved grout coverage because more space is available

Explanation

An off-center casing creates a wide annulus on one side that may not be completely filled with grout, leaving a channel for contamination. Centralizers help keep the casing centered so grout forms a continuous seal.

Question 42Well Construction and Compliance

A driller is developing a well in a sandstone aquifer and notices the water remains turbid after development. Which action is most appropriate?

  1. Add more gravel to the annulus
  2. Increase the chlorine dose and seal the well
  3. Continue development until the water clears or the yield stabilizes Correct answer.
  4. Stop development immediately and install the pump

Explanation

Turbidity that persists may mean development is incomplete, and continued surging or pumping can remove fine material and stabilize the well. Stopping too early can leave the well producing sediment.

Question 43Well Construction and Compliance

A driller must abandon a well that penetrates multiple aquifers. Which abandonment method best protects groundwater?

  1. Leave the well open and mark it with a sign
  2. Fill the well with gravel and cap the top
  3. Fill the entire wellbore with an approved sealing material such as grout or bentonite Correct answer.
  4. Pump the well dry and remove the casing

Explanation

Proper abandonment requires filling the wellbore with an approved low-permeability seal, often grout or bentonite, to prevent cross-contamination between aquifers and surface water. Gravel or an open wellbore would allow water to move between zones.

Question 44Well Construction and Compliance

A driller is constructing a well and encounters a shallow, contaminated aquifer above the target aquifer. Which construction feature most directly prevents the contamination from reaching the target aquifer?

  1. A deeper screen setting only
  2. A higher pump setting
  3. A continuous annular seal through the contaminated zone Correct answer.
  4. A larger diameter borehole

Explanation

A continuous annular seal through the contaminated zone blocks the pathway for contamination to move down the outside of the casing. Without the seal, contaminated water can migrate to the producing aquifer.

Question 45Well Construction and Compliance

A driller is evaluating a grout mix for a well with a high water table. Which property most affects the mix's ability to displace water and form a seal?

  1. Density and water-cement ratio Correct answer.
  2. Setting time of the drill bit
  3. Bag weight only
  4. Color of the cement

Explanation

Density and water-cement ratio control how well the grout displaces water and resists dilution in a high water table. A properly proportioned mix maintains its volume and forms a continuous seal.

Question 46Well Construction and Compliance

A driller is designing a well in a fractured bedrock aquifer where the water level is deep. Which construction detail is most important for protecting water quality?

  1. Using the largest possible casing diameter
  2. Leaving the annulus open for venting
  3. Installing a screen across the entire bedrock interval
  4. Sealing the annular space to the top of the bedrock and grouting to the surface Correct answer.

Explanation

In fractured bedrock, sealing the annulus to the top of bedrock and grouting to the surface prevents surface water and shallow groundwater from entering the fractures. This protects the deep water from contamination.

Question 47Well Construction and Compliance

A driller is reviewing a well design where the screen spans two aquifers separated by a thin clay layer. Why is this design potentially problematic?

  1. It can allow mixing of waters of different quality and reduce the clay layer's confining effect Correct answer.
  2. It makes the casing easier to install
  3. It increases the well's yield beyond the pump capacity
  4. It reduces the need for a sanitary seal

Explanation

Screening across a confining layer can allow waters from separate aquifers to mix and can compromise the clay layer's ability to isolate zones. Proper design places the screen within a single aquifer or uses a seal to separate zones.

Question 48Well Construction and Compliance

A driller must grout the annular space of a well with a large diameter casing and a deep setting. Which placement method best ensures a complete seal?

  1. Pumping grout through a tremie pipe from the bottom of the seal upward Correct answer.
  2. Using a dump bailer from the top
  3. Pouring grout from the surface in stages
  4. Mixing grout with drill cuttings and backfilling

Explanation

Pumping grout from the bottom upward through a tremie pipe displaces the drilling fluid and prevents voids, ensuring a continuous seal in deep or large-diameter wells. Surface placement methods tend to bridge and leave gaps.

Question 49Well Construction and Compliance

A driller is evaluating whether a proposed well location meets Oregon setback requirements near a barnyard and a fuel storage tank. Which action is most appropriate?

  1. Rely on the owner's assurance that the sources are not a problem
  2. Verify the required separation distances for each source and relocate the well if needed Correct answer.
  3. Proceed because barnyards and fuel tanks are not regulated sources
  4. Install a larger pump to dilute any contamination

Explanation

Oregon sets required separation distances from potential contamination sources such as barnyards and fuel storage, and the driller must verify compliance before drilling. If the setbacks cannot be met, the well must be relocated.

Question 50Well Construction and Compliance

A driller is completing a well and must decide how to seal the annulus where the casing passes through a confining layer. Which approach best satisfies the intent of the rules?

  1. Leave the annulus open to allow pressure relief
  2. Install a screen across the confining layer
  3. Fill the annulus with sand to filter water
  4. Grout the annulus continuously across the confining layer to prevent vertical migration Correct answer.

Explanation

Grouting continuously across a confining layer preserves the layer's ability to prevent vertical movement of water between aquifers. An open or permeable annulus would defeat the confining layer's purpose.