Free Exam H: Jetting and Driving Wells Practice Questions

Sample Practice Questions

Try these 10 sample questions from the Exam H: Jetting and Driving Wells practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1A crew is driving a steel wellpoint and casing string joined with drive couplings, and the driller keeps striking the drive cap after penetration has nearly stopped. If the string is overdriven, where is it most likely to fail?

   1. A. At one of the threaded couplings joining the casing sections
   2. B. Midway along one of the full-length casing sections in the hole
   3. C. At the drive cap that is seated on the uppermost section
   4. D. At the casing wall a short distance above the ground surface

   Answer: A

   Explanation: The EPA monitoring-well handbook states: "Drive couplings are specially designed to withstand the force of the blows used to drive the casing; however, if the casing is overdriven it will usually fail at a coupling." Even purpose-built drive couplings remain the weak point of a driven string, so continued hammering after refusal most often breaks the string at a joint rather than in the body of a pipe section or at the drive cap.

   Reference: Handbook of Suggested Practices for the Design and Installation of Ground-Water Monitoring Wells (EPA/600/4-89/034) — Section 4, Drilling Methods for Monitoring Well Installation, Driven Wells (pp. 35-36)

2. 2A screened drive point on steel pipe has been lowered to a few feet above caved material in an auger hole. The driller connects a pump hose to the top of the pipe to wash the point down through the cave-in. At what rate does USGS guidance suggest pumping clean water through the drive-point screen while lowering the pipe?

   1. A. About 20 to 25 gallons per minute
   2. B. About 2 to 3 gallons per minute
   3. C. About 115 to 125 gallons per minute
   4. D. About 300 to 350 gallons per minute

   Answer: A

   Explanation: USGS TWRI Book 2, Chapter F1 describes the wash-in method: "couple the pump-discharge hose to the top of the well pipe and pump in clean water at a rate of 20-25 gal/min through the drive-point screen, while, at the same time, lowering the pipe and screen." The water washes caved material away from the screen so it does not plug, and leaves a lubricated annulus for the pipe to follow.

   Reference: Application of Drilling, Coring, and Sampling Techniques to Test Holes and Wells (USGS TWRI Book 2, Chapter F1) — Auger Drilling, Installation of Well Casing and Screen in Solid-Stem Augered Holes, method 1 (pp. 14-15)

3. 3A drive point well with a suction pump at the surface is planned for a site at about 5,000 feet elevation. What practical limit on depth to water, including drawdown, applies to a suction pump at that elevation?

   1. A. About 17 feet
   2. B. About 22 feet
   3. C. About 14 feet
   4. D. About 25 feet

   Answer: A

   Explanation: The NRCS Engineering Field Handbook states: "Depth to water, including drawdown, must be less than the suction limit at the elevation of the well. The practical limit of suction lift for pumps is 22 feet at sea level, 17 feet at 5,000-foot elevations, and 14 feet at 10,000-foot elevations." At 5,000 feet the practical limit is therefore about 17 feet; 22 feet applies at sea level and 14 feet at 10,000 feet. The figure of 25 feet is the handbook's general statement that "The practical suction lift on most suction pumps is 25 feet or less", which does not account for the reduced lift at 5,000 feet.

   Reference: National Engineering Handbook, Part 650 Engineering Field Handbook, Subpart L - Spring and Well Design — 650.185 C.2.b, Drive Point Wells (text following Figure 650L-22)

4. 4A consultant must install a shallow monitoring well where a detailed stratigraphic log of the screened interval is a key project objective. What is the main drawback of building this well by driving a wellpoint or by jetting?

   1. A. It always requires an artificial filter pack placed around the well screen
   2. B. It cannot provide any water-level information once the well is completed
   3. C. It requires a borehole at least 4 inches larger than the nominal casing
   4. D. It severely limits the ability to collect detailed stratigraphic information

   Answer: D

   Explanation: The EPA handbook notes that "constructing wells by driving wellpoint or by jetting provides low-cost water-level information but severely limits the ability to collect detailed stratigraphic information." Driving and jetting give cheap water-level access, not a detailed log. The oversized borehole and artificial filter pack are assumptions the handbook applies to other methods, and it specifically excepts driven and jetted wells from them.

   Reference: Handbook of Suggested Practices for the Design and Installation of Ground-Water Monitoring Wells (EPA/600/4-89/034) — Section 4, Description and Selection of Drilling Methods, Introduction (PDF page 45)

5. 5A shallow monitoring well is being hand-augered, but the borehole collapses as soon as the auger reaches the water table. Which approach does the EPA handbook describe for getting the well intake below the water table in this situation?

   1. A. Keep augering dry while bailing out the water as it enters the open hole
   2. B. Change to a larger auger head so the saturated hole will stay open longer
   3. C. Drive a wellpoint into the augered hole to advance it below the water table
   4. D. Pour bentonite chips into the hole to firm up the saturated sand at bottom

   Answer: C

   Explanation: The handbook states: "Another option to overcome borehole collapse below the water table is to drive a wellpoint into the augered hole and thereby advance the wellpoint below the water table." The wellpoint can then be used to measure water levels and collect samples. A larger auger head, bentonite chips, or bailing do not keep a caving saturated hole open.

   Reference: Handbook of Suggested Practices for the Design and Installation of Ground-Water Monitoring Wells (EPA/600/4-89/034) — Section 4, Drilling Methods for Monitoring Well Installation, Hand Augers (PDF page 45)

6. 6In the EPA handbook's description of driven monitoring wells, what diameter range is typical for the wellpoint and casing?

   1. A. 0.5 to 0.75 inch
   2. B. 1.25 to 2 inches
   3. C. 4 to 6 inches
   4. D. 8 to 10 inches

   Answer: B

   Explanation: The handbook states: "Wellpoints and casing are usually 1.25 to 2 inches in diameter and are made of steel to withstand the driving process." Driven wells are small in diameter because a larger string meets much more resistance when driven.

   Reference: Handbook of Suggested Practices for the Design and Installation of Ground-Water Monitoring Wells (EPA/600/4-89/034) — Section 4, Drilling Methods for Monitoring Well Installation, Driven Wells (PDF page 45)

7. 7Before a driven well's screen and casing are pounded into the ground, which fitting is placed on top of the uppermost casing section to receive the blows?

   1. A. Well seal
   2. B. Vented well cap
   3. C. Pitless adapter
   4. D. Drive cap

   Answer: D

   Explanation: The EPA handbook describes the sequence: "When constructing a well, a drive cap is placed on top of the uppermost section of casing, and the screen and casing are driven into the ground." A well seal, vented well cap, or pitless adapter is a finished-well fitting and is not meant to take driving blows.

   Reference: Handbook of Suggested Practices for the Design and Installation of Ground-Water Monitoring Wells (EPA/600/4-89/034) — Section 4, Drilling Methods for Monitoring Well Installation, Driven Wells (PDF page 46)

8. 8No cuttings or samples come to the surface while a wellpoint is being driven. What can the driller record during driving to obtain crude stratigraphic information?

   1. A. The volume of water lost per foot of depth
   2. B. The color of the water returned at the surface
   3. C. The number of blows per foot of penetration
   4. D. The torque needed to turn the drill string

   Answer: C

   Explanation: The EPA handbook states: "Crude stratigraphic information can be obtained by recording the number of blows per foot of penetration as the wellpoint is driven." Water loss, return color, and rotary torque are observations from fluid-circulating or rotary methods. A driven wellpoint has no circulation and no rotary drive.

   Reference: Handbook of Suggested Practices for the Design and Installation of Ground-Water Monitoring Wells (EPA/600/4-89/034) — Section 4, Drilling Methods for Monitoring Well Installation, Driven Wells (PDF page 46)

9. 9A wellpoint is to be driven by hand in sands containing thin clay seams. According to the EPA handbook, roughly what depth can be achieved by hand driving under these conditions?

   1. A. Up to about 50 feet
   2. B. Up to about 30 feet
   3. C. Up to about 100 feet
   4. D. Up to about 150 feet

   Answer: B

   Explanation: The handbook states that depths up "to 30 feet can be achieved by hand in sands or sand and gravel with thin clay seams; greater depths of 50 feet or more are possible with hammers up to 1,000 pounds in weight." Fifty feet is therefore the heavy-hammer figure, not the hand-driving one. Depths of about 100 feet are associated with power-driven direct-push equipment, and about 150 feet with jet-percussion wells; neither applies to driving by hand.

   Reference: Handbook of Suggested Practices for the Design and Installation of Ground-Water Monitoring Wells (EPA/600/4-89/034) — Section 4, Drilling Methods for Monitoring Well Installation, Driven Wells (PDF page 45)

10. 10A wellpoint is being driven down through coarse sand and gravel deposits. According to the EPA handbook, what most frequently ends penetration in such coarser materials?

    1. A. Thin clay seams
    2. B. Saturated fine sand
    3. C. Loose dry silt
    4. D. Boulders

    Answer: D

    Explanation: The handbook states: "In the coarser materials, penetration is frequently terminated by boulders." Thin clay seams can still be driven through (the handbook gives hand-driving depths for sands with thin clay seams), and loose sand and silt offer little resistance compared with a boulder in the path of the point.

    Reference: Handbook of Suggested Practices for the Design and Installation of Ground-Water Monitoring Wells (EPA/600/4-89/034) — Section 4, Drilling Methods for Monitoring Well Installation, Driven Wells (PDF page 46)