GENERAL GEOLOGY

Detailed explanation-1: -Groundwater in an unconfined aquifer (some-times called a “water table aquifer”) is more vulnerable to contamination from surface pollution than a confined aquifer because pollutants on the land surface can enter the unconfined aquifer as water infiltrates the soil.

Detailed explanation-2: -Unconfined sand and gravel aquifers are more vulnerable to contamination.

Detailed explanation-3: -Unconfined aquifers generally are much more vulnerable to contamination than confined aquifers. For a well in a confined aquifer, the farther the well is from the unconfined area, the less vulnerable it is to contamination. Generally, the deeper the well, the less vulnerable it is to contamination.

Detailed explanation-4: -Because unconfined aquifers are open to the atmosphere they carry a greater risk of contamination. Also, the presence of aquifer systems, or any other water-bearing formations, near a construction zone is a concern for drillers.

Detailed explanation-5: -Near-surface groundwater in areas of high urban density or intensive agriculture is more likely to be contaminated by chloride or nitrate. The overuse of groundwater threatens surface water quality, and draws contaminated near-surface water into our drinking water aquifers.