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The well shall be sounded immediately before it is destroyed to make sure that no obstructions exist that will interfere with filling and sealing. The well shall be cleaned before destruction, is as needed,to ensure that all undesirable materials,including obstructions to filling and sealing, debris,and pollutants and contaminants that could interfere with well destruction are removed for disposal. The enforcing agency shall be notified as soon as possible if pollutants and contaminants are known or suspected to be in a well to be destroyed. Well destruction operations may then proceed only at the approval of the enforcing agency. The enforcing agency should be contacted to determine requirements for proper disposal of materials removed from a well to be destroyed. B. Filling and Sealing Conditions. The following minimum requirements shall be followed when various conditions are encountered. 1. Wells that only penetrate unconsolidated material and a single"zone"of ground water. At a minimum, the upper 20 feet of the well casing and the annulus between the well casing and borehole wall(if not already sealed)shall be completely sealed with suitable material. Sealing material shall extend to a minimum depth of 50 feet below land surface if the well to be destroyed is located in an urban area,or is within 100 feet of any potential source of pollution or contamination. Additional sealing material may be needed if adverse conditions exist. The remainder of the well below the minimum surface seal shall be filled with suitable granular fill material,such as clean sand or pea gravel, or with sealing material. 2. Wells that penetrate several water-bearing strata.The upper portion of the well casing and annular space shall be filled with sealing material as described in Item 1, above. Strata encountered below the surface seal that contain poor-quality water, pollutants, or contaminants that could mix with and degrade water in other strata penetrated by the well, shall be effectively isolated by sealing the well bore and annulus within intervals specified in Section 10,above. The remainder of the well shall be filled with suitable granular fill or sealing material. 3. Wells penetrating fractured rock. Sealing material shall be installed as outlined in Items 1 and 2,above. Cement-based sealing material shall be used opposite fractured rock. The remainder of the well shall be filled with fill or sealing material, as appropriate. 4. Wells in nonfractured consolidated strata. Sealing material shall be installed as outlined in Items 1 and 2,above. The remainder of the well shall be filled with fill or sealing material, as appropriate. 5. Wells penetrating water-bearing zones or aquifers of special significance. The enforcing agency may require that specific water-bearing zones be sealed off for well destruction. C. Placement of Material. The placement of sealing materials for cathodic protection well destruction is generally described in Section 23 and Appendix B of the Water Well Standards. The following additional requirements shall be observed in destroying cathodic protection wells. Casing, cables, anodes, granular backfill, conductive backfill, and sealing material shall be removed as needed,by redrilling, if necessary,to the point needed to allow proper placement of sealing materials within required sealing intervals.Removal of some or all well materials will likely be required for cathodic protection wells that were not constructed in accordance with -72-