CWD Well Maintenance & Rehabilitation Flashcards

What is the primary purpose of well redevelopment after installation?

Answer: Remove drilling fluid and fine particles to restore natural permeability

Well redevelopment removes residual drilling fluids and fine particles that clog the formation, restoring the natural permeability around the well screen.

Which surging method uses a tight-fitting piston to alternately push and pull water through the screen?

Answer: Mechanical surging with a surge block

Mechanical surging with a surge block uses a tight-fitting piston (surge block) that is moved up and down to force water back and forth through the well screen, dislodging fine particles.

A well experiencing gradual decline in yield over several years most likely indicates:

Answer: Biofouling or mineral encrustation of the screen

Gradual yield decline over years is a classic sign of biofouling (iron bacteria) or mineral encrustation (calcium/manganese deposits) plugging the well screen and formation.

What chemical is commonly used to treat iron bacteria fouling in a domestic water well?

Answer: Sodium hypochlorite (chlorine bleach)

Sodium hypochlorite (chlorine bleach) is the most common chemical used to shock-chlorinate wells to kill iron bacteria and other biological fouling organisms.

The specific capacity of a well is defined as:

Answer: Pumping rate divided by drawdown

Specific capacity is the pumping rate (gpm) divided by the drawdown (ft), expressing how many gallons per minute the well yields per foot of drawdown.

When rehabilitating an old well, which test should be performed BEFORE chemical treatment to establish a baseline?

Answer: All of the above

Before rehabilitation, a video inspection, pumping test for specific capacity, and water chemistry/pH testing together establish a complete baseline to measure the success of rehabilitation.