Which of the following practices does not align with proper monitoring-well installation practices described in the material?

• A. Not decontaminating the gear before setup
• B. Using a Shelby tube and/or split spoon sampler
• C. Matching slot size to filter pack material
• D. Installing with care to avoid contamination from drilling

Answer: (A)

In monitoring-well installations, keeping gear decontaminated before setup is essential to prevent cross-contamination and ensure that samples reflect the actual aquifer conditions. If gear isn’t decontaminated, residual contaminants from prior work or drilling fluids can be introduced into the borehole, the screen, and the surrounding filter pack, leading to skewed analytical results and mischaracterization of groundwater quality. The other practices align with proper methods: using a Shelby tube or split spoon sampler is a standard approach for obtaining soil samples; matching the slot size to the filter-pack material helps maintain proper hydraulic communication and prevents clogging or sand intrusion; and installing with care to avoid contamination from drilling minimizes introducing drilling fluids or cuttings into the well and aquifer.