A poorly developed monitoring well can lead to which of the following?

• A. Low production rate
• B. High turbidity
• C. Non-representative ground water samples
• D. Sample contamination by surface water

Answer: (C)

The key idea is that developing a monitoring well properly establishes a clean, hydraulically connected path between the well and the surrounding aquifer so samples reflect the true groundwater rather than water left in the borehole. If development is poor, drilling fluids and fines stay in the screen and vicinity of the well, and stagnant or disturbed water from the borehole can mix with the formation water. This means any sample drawn from the well may be biased by materials and conditions that don’t represent the aquifer as a whole, giving you non-representative groundwater samples.

While higher turbidity can occur if fines are not cleared, and low production can happen in other drilling or pumping scenarios, the primary consequence for a poorly developed monitoring well in terms of the data you collect is that the samples won’t accurately reflect the aquifer.