Section 144-232-4-401.0 - STANDARD PRACTICE FOR CONSTRUCTION OF WELLS DRILLED IN BEDROCK401.1Well casing and liner material: Well casings and liners shall be made of a material and weight appropriate to assure adequate performance of the functions for which they are used. The minimum characteristics of well casing and liners are as follows: 401.1.1Contaminants from casing and liners: Casing and liner material shall not be a source of pollution.401.1.2Steel casing or liners: Steel well casing or liners shall have a minimum wall thickness of .250 inches.401.1.3Plastic casing or liners: Plastic well casing or liners shall be schedule 40 or heavier and National Sanitation Foundation approved for potable water use, including but not limited to Polyvinylchloride (PVC), Chlorinated polyvinyl chloride (CPVC), or Acrylonitrile butadiene styrene (ABS) or a Commission approved substitute.401.2Well casing placement: Well casing placement shall be as follows: 401.2.1General: Casings shall prevent intrusion of contaminants from the ground surface or unconsolidated soil layers into the well.401.2.2Soil particles: Casings shall prevent entrance of soil particles into the well.401.2.3Termination above ground: Well casings shall extend above ground surface a minimum of eight inches. Additional height or a vented water tight cap may be required to prevent entrance of surface water in areas prone to flooding. (see 402.0)401.3Covers: Well casings shall have a cover to prevent the entrance of foreign matter into the well.401.4Drive shoe or coupling: Drive shoe or coupling shall be used for all rotary drilled wells to assist in sealing the casing into bedrock when steel casing is used. A coupling may be used in an open hole setting.401.5Casing extension into bedrock: It shall be the responsibility of the Water Well Contractor to install a sufficient length of well casing into bedrock, and to affect a proper seal in order to prevent surface water and shallow ground water from transmitting gravel, sand, silt, clay, and coliform bacteria into the wellbore at the bottom of the casing or anywhere along the length of the casing. The below requirements shall not preclude the use of additional protective measures if approved by the Commission. 401.5.1Twenty (20) foot minimum: For any drilled bedrock well, in addition to the requirements of 401.5, a contractor is responsible for the installation of a minimum of 20 feet of casing. At least 10 feet of casing extending into the bedrock is recommended.401.5.2Plastic casing seal: When plastic casing is used, the seal shall be created by using a "jaswell" type seal tip, shale packer or equal, and the casing shall be placed in an open hole.401.5.3Steel casing seal: "Jaswell" type seal tips, shale packers or their equal may be used on steel casing when the casing is placed in an open hole.401.5.4Void area seal: The void area outside the casing shall be filled with cement grout, bentonite or ledge cuttings.401.5.5Bit size: All wells shall be started with a bit at least .5 inches larger than the drive shoe or coupling being used, except when a casing underreamer is used.401.5.6Cable tool wells: For cable tool wells, a tapered hole with ledge drilling or bentonite grout is an acceptable substitute for a drive shoe.401.5.7Placement of liners: All liners mustbe installedin such a manner that they will stay permanently in place, unless intentionally removed at a later date.401.5.8"Jaswell" type seals installed on liners: When "Jaswell" type seal tips are installed on liners, they shall be water-tight and leak-free.401.5.9Additional protective measures: The above requirements shall not preclude the use of additional protective measures. When the annulus of a well casing is grouted, it is recommended that the materials, methods and procedures in the "Manual of Water Well Construction, Second Edition, published in 1998 by the National Groundwater Association", chapter 4 be used.10-144 C.M.R. ch. 232, § 4-401.0