Monitoring wells - Minimum requirements

In determining the number, location, and construction of monitoring wells, and the frequency of sampling from monitoring wells, the following must be considered: 1. Whether any person relies on the underground source of drinking water affected or potentially affected by the injection operation; 2. The proximity of the injection operation to points of withdrawal of drinking water; 3. The local geology and hydrology; 4. The operating pressures and whether a negative pressure gradient is being maintained; 5. The toxicity and volume of the injected fluid, the formation water, and the process byproducts; and 6. The spatial distribution of the injection wells.