CWD Well Maintenance & Rehabilitation Flashcards

Acid treatment of a water well is most effective for which type of fouling?

Answer: Calcium carbonate and mineral scale deposits

Acid treatment (typically hydrochloric or muriatic acid) is most effective at dissolving calcium carbonate and mineral scale deposits that block well screens and the surrounding formation.

A step-drawdown test is used primarily to:

Answer: Evaluate well efficiency and identify non-linear head losses

A step-drawdown test pumps a well at sequentially increasing rates to separate aquifer losses from well losses, determining well efficiency and identifying turbulent (non-linear) head losses.

What is the minimum waiting period after shock chlorination before a well can be returned to domestic service according to standard US practice?

Answer: At least 24 hours, plus a clear bacteriological test

Standard practice requires waiting at least 24 hours for the chlorine to dissipate and then passing a clear bacteriological test (absent for total coliform and E. coli) before returning the well to service.

Which indicator best signals that a submersible pump is wearing out rather than the well declining?

Answer: Pump amp draw increases while yield decreases

Increasing amp draw combined with decreasing yield indicates pump impeller wear, as a worn pump draws more current to overcome internal bypass while producing less water.

Polyphosphate sequestering agents added to well water are used to:

Answer: Prevent iron and manganese from staining fixtures

Polyphosphate sequestering agents chemically bind iron and manganese ions, keeping them in solution and preventing oxidation that causes staining on fixtures and laundry.

When a well screen is corroded beyond rehabilitation, the recommended remedy is:

Answer: Install a liner or sleeve, or construct a replacement well

A corroded well screen that cannot be rehabilitated requires either installing a well liner/sleeve to bypass the damaged section or constructing a new replacement well.