Incrustation and corrosion in wells and pipelines Which of the following statements is correct regarding well/pipeline problems due to water chemistry?

Introduction / Context:
Operational issues in wells and pipelines commonly stem from two mechanisms: incrustation (chemical deposition) and corrosion (electrochemical attack). Both impair system performance and service life if not controlled through water chemistry management and maintenance.

Given Data / Assumptions:

• Groundwater with dissolved minerals like calcium and bicarbonate.
• Steel or iron components exposed to varying pH, dissolved oxygen, and carbon dioxide.

Concept / Approach:
Incrustation results from precipitation of mineral scales (e.g., CaCO3) when conditions favour reduced solubility (e.g., CO2 loss, pH rise). Scale narrows flow passages and clogs screens, lowering yield. Corrosion is driven by acidity, dissolved oxygen, CO2, and galvanic effects, leading to metal loss and leaks. Sand pumping erodes mechanically but does not cause chemical corrosion.

Step-by-Step Solution:

Verification / Alternative check:
Well redevelopment records often show yield recovery after descaling/acid treatment, confirming scale-driven loss. Corrosion coupons and pH/DO monitoring correlate with corrosion rates.

Why Other Options Are Wrong:

• Incrustation does not increase capacity; it reduces effective area.
• Corrosion is strongly linked to acidity and oxidants; high alkalinity is generally protective.
• Sand withdrawal causes abrasion, not chemical corrosion.
• “All the above” cannot be true because multiple statements are false.

Common Pitfalls:
Assuming any deposition is beneficial; ignoring that slight pH shifts can drastically change scaling tendencies (Langelier index).

Final Answer:
Deposition of calcium carbonate inside well screens and pipes leads to incrustation, which reduces discharge over time