CWD Quality Assurance & Improvement 3

Question 1

Which well development method is most effective for removing drilling fluid invasion from a fine-grained sand aquifer?

Accepted Answer

Chemical polyphosphate treatment followed by surging

Answer

Polyphosphate dispersants break down drilling mud filter cake in fine sands, and subsequent surging removes the loosened material from the formation.

Question 2

What is the minimum annular space required between the drill hole and casing for proper grouting under most state regulations?

Accepted Answer

2 inches

Answer

Most state codes require a minimum 2-inch annular space to allow complete grout emplacement without bridging or voids.

Question 3

During well construction QA, a borehole caliper log shows the drilled diameter is 2 inches smaller than specified at 80 feet depth. What is the correct response?

Accepted Answer

Ream the borehole to the required diameter before casing

Answer

The borehole must be reamed to the specified diameter to ensure proper annular space for grouting and casing installation.

Question 4

A well's specific capacity drops 40% six months after installation. Which cause should be investigated first?

Accepted Answer

Biofouling or incrustation of the screen

Answer

A significant specific capacity decline in a relatively new well most commonly results from iron bacteria or mineral incrustation blocking the screen openings.

Question 5

What does a sand content test using a Rossum sand tester measure in a water well?

Accepted Answer

Parts per million of sand in the pumped water by volume

Answer

The Rossum sand tester captures sand settling in a graduated tube over a timed flow to determine sand concentration in ppm by volume.

(CWD) Certified Well Driller Practice Test

(CWD) Certified Well Driller Practice Test

CWD Quality Assurance & Improvement 3