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otherwise approved by the enforcing agency. The base shall have a lift-out section,or + equivalent, to allow access to the well. The lift-out shall facilitate inspection and repair of the well. B. Well Pits or Vaults. The use of well pits,vaults, or equivalent features to house the top of a well casing below ground surface shall be avoided,if possible,because of their susceptibility to the entrance of poor-quality water,contaminants and pollutants. Well pits or vaults can only be used if approval is obtained from the enforcing agency. A substitute device,such as a pitless adapter or pitless adapter unit (a variation), should almost always be used in place of a vault or pit. Pitless adapters and units were developed for use in areas where prolonged freezing occurs,and below ground (frost line) discharges are common. Both the National Sanitation Foundation and Water Systems Council have developed standards for the manufacture and installation of pitless adapters and units. (See Appendix E, Bibliography, page 85 of Bulletin 74-81.) If a pit or vault is used it shall be watertight and structurally sound. The vault shall extend from the top of the annular seal to at least ground surface. The vault shall contact the annular seal in a manner to form a watertight and structurally sound connection. Contacts between the vault and the annular seal,and the vault and the well casing, if any, shall not fail or cause the failure of the well casing or annular seal. Where cement-based annular seal materials are used,the vault shall be set into or contact the annular seal material before it sets, unless otherwise approved by the enforcing agency. If bentonite-based sealing material is used for the annular seal, the vault should be set into the bentonite before it is fully hydrated. Cement-based sealing material shall be placed between the outer walls of the vault and the excavation into which it is placed to form a proper,structurally sound foundation for the vault, and to seal the space between the vault and excavation. The sealing material surrounding a vault shall extend from the top of the annular seal to ground surface unless precluded in areas of freezing. If cement-based sealing material is used for both the annular seal and the space between the excavation and vault,the sealing material shall be emplaced in a'continuous pour'. In other words,cement-based sealing material shall be placed between the vault and excavation and contact the cement-based annular seal before the annular seal has set. The vault cover or lid shall be watertight but shall allow the venting of gases. The lid shall be fitted with a security device to prevent unauthorized access. The outside of the lid shall be clearly and permanently labeled'WATER WELL'. The vault and its lid shall be strong enough to support vehicular traffic where such traffic might occur. The top of the vault shall be set at, or above, grade so that drainage is away from the vault. The top of the well casing contained within the vault shall be covered in accordance with requirements under Subsection A,above,(page 36,Bulletin 74-81)so that water,contaminants, and pollutants that may enter the vault will not enter the well casing. The cover shall be provided with a pressure relief or venting device for gases. -23-