A glossary at the back of this publication explains the terminology used. State well regulations require that petroleum storage tanks be at least 100 feet from a water well. Minimum separation distances regulate only new well installation. Existing wells are required by law only to meet separation requirements in effect at the time of well construction. However, making every effort to meet current regulations whenever possible will further reduce the risk of contamination.
Every site has unique geologic and hydrologic conditions that affect ground water movement.
The time it takes petroleum products to reach ground water also will depend upon local soils. You may choose to locate a new tank more than 100 feet away from a well to provide reasonable assurance that subsurface flow or seepage of contaminated ground water will not reach the well. If possible, the tank should be located down-slope from the well. Figure 1 illustrates petroleum product seepage into soils. Petroleum product seepage into soils.