All grout shall be emplaced in one continuous operation upward from the bottom of the casing or depth specified in these regulations. Pouring, dumping, or shoveling of grout slurries into the annular space or well bore are prohibited. The drilling fluids in the annular space shall be thinned before grouting to a density less than that of the intended grout density. Grout shall be emplaced so that it completely displaces the fluid in the annular space from the bottom of the interval being grouted to the ground surface. The following are approved methods of grouting when performed in accordance with the conditions specified: Grout Pipe Outside of Casing (Tremie Pipe). The annular space shall be a minimum of 1½ inches. All grout shall be placed by pumping through the grout pipe. The entire interval to be grouted shall be open and without obstructions; washing or jetting with water is recommended for cleaning the borehole and may serve to remove obstructions caused by caving which otherwise would prevent a proper grout. The grout pipe shall extend from the surface to the bottom of the interval to be grouted. The grout pipe may remain extended to the bottom of the interval during and after grouting, or it may be raised slowly as the grout is placed provided that the discharge end of the grout pipe remains submerged in the emplaced grout at all times until grouting is completed. In the event of interruption in the grouting operations, the bottom of the grout pipe shall be raised above the grout level and should not be resubmerged until the air and water have been displaced from the grout pipe. Grouting Depths of 20 feet or Less. Grout may be placed by a grout pipe inserted only 10 feet into the annular space, provided that: The entire interval to be grouted is clearly visible from the surface and is dry; and An annular space larger than the minimum 1½ inches may be required to assure visibility from the surface. Grout Pipe — Inside Casing. The bottom of the casing is fitted with a cementing shoe or float shoe and the casing is placed in the borehole a short distance off the bottom; The grout pipe is placed in the casing a short distance from the float shoe or is mechanically attached to the float shoe; and Grout is pumped through the grout pipe until grout appears at the land surface. Grouting with Bentonite Chips or Pellets. A well may be grouted using bentonite chips or pellets under the following conditions: The grouting depth is 20 feet or less; The annular space is open and free of obstruction; The annular space is at least 1½ inches; The drilling fluid, if present, is thinned to a viscosity of less than 30 seconds and the weight is less than 9 pounds per gallon; The bentonite chips or pellets may be poured down the annular space; and The annular space is continuously measured to assure proper filling without bridging. If bridging occurs and the annular space cannot be completely filled then: The annular space shall be jetted to remove the bentonite; or The well shall be abandoned and sealed in accordance with this chapter. The Approving Authority may approve other grouting methods not specifically identified by this regulation.