40 CFR §147.1655

1. (a)The owner or operator of a Class I well authorized by permit shall install or shall ensure that the well has:
   1. (1)Surface casing present;
      1. (i)Extending from the surface to a depth at least 50 feet below the base of the lowermost USDW; and
      2. (ii)Cemented back to the surface by recirculating the cement; and
   2. (2)Long string casing and tubing;
      1. (i)Extending to the injection zone; and
      2. (ii)Cemented back to 50 feet above the base of the next largest casing string.
2. (b)The owner or operator of a new Class II well authorized by permit shall:
   1. (1)Install surface casing from the surface to at least 50 feet below the base of the lowermost USDW.
   2. (2)Cement the casing by recirculating to the surface or by using no less than 120% of the calculated annular volume.
   3. (3)For new enhanced recovery wells, install tubing or long string casing extending to the injection zone.
   4. (4)For new salt water disposal wells, install long string casing and tubing extending to the injection zone.
   5. (5)Isolate any injection zone by placing sufficient cement to fill the calculated volume to a point 50 feet above the injection zone.
3. (c)The Regional Administrator may specify casing and cementing requirements other than those listed in paragraphs (a) and (b) of this section on a case by case basis as conditions of the permit.