OAR 690-240-0525: Piezometers

It is prohibited to construct a piezometer in an area of known or reasonably suspected contamination. NOTE: The Water Resources Department and the Department of Environmental Quality have information sources to use in determining if contaminants are present. Customary drilling practice as conducted by licensed professional must be included as part of the appropriate inquiry to determine if contaminants are present or reasonably suspected. (1) A piezometer is defined in OAR 690-240-0010(59). Piezometers are a type of monitoring well and shall meet current monitoring well rules except for the following: (a) Borehole size with depth requirements: (A) For piezometers with a sealing depth less than 50 feet deep, the borehole diameter shall be at least two and one half inches (2.5") larger than the nominal casing diameter. If the piezometer is constructed using a hollow stem auger drilling machine, the inside diameter of the auger must be at least 2.5 inches larger than the nominal diameter of the casing to be installed; (B) For piezometers with a sealing depth greater than 50 feet deep, the borehole diameter shall be at least three inches larger than the nominal casing diameter. If the piezometer is constructed using a hollow stem auger drilling machine, the inside diameter of the auger must be at least 3 inches larger than the nominal diameter of the casing to be installed. (b) Surface Completion: (A) Piezometers shall be protected as described in OAR 690-240-0420 concerning monitoring wells. (c) If an artesian piezometer flows at land surface, it shall be equipped with a control valve or a watertight mechanical cap, so that all flow of water from the well can be completely stopped. Flowing artesian piezometers are not required to be equipped with a pressure gauge placed on a dead-end line or a petcock valve; (d) The special cleaning and drill cutting storage requirements in OAR 690-240-0450 shall not apply to piezometers because they may not be constructed in areas of known or reasonably suspected contamination. However, all equipment and materials used in the construction of a piezometer shall be free of foreign materials and contaminants prior to entry into the well; (e) Use of commercially fabricated screens are not required for piezometers. The screens installed shall be in new or like new condition, being free of pits or breaks, and shall be free of foreign materials and contaminants prior to installation; (f) The filter pack requirements of OAR 690-240-0460(5) shall not apply to piezometers because they are not constructed in areas of known or reasonably suspected contamination; (g) A minimum three foot annular seal is required. If a grout slurry is used, the filter pack seal requirements of 690-240-0460(6) apply. If a piezometer is completed with a flush monument, the annular seal shall extend a minimum of three feet below the monument seal. (2) Piezometer well abandonment: Piezometer wells shall be abandoned as described in OAR 690-240-0510 concerning monitoring wells.