Louisiana Administrative Code
Title 56 - PUBLIC WORKS
Part I - Water Wells
Chapter 3 - Water Well Construction
Section I-329 - Methods and Standards for Cementing the Annular Space

1. The methods and materials employed to cement the annular space between the well casing and the borehole generally depend upon:

2. The primary reasons for sealing, cementing or grouting the annular space are as follows:

1. Annular space shall be sealed with cement-bentonite slurry, which is a mixture of cement, bentonite and water, consisting of not more than 8 percent bentonite by dry weight of the cement, and a maximum of 10 gallons of water per sack (94 pounds) of cement. Additives, in the approved and proper ratio, may be added to the slurry if required. If the slurry is to be prepared in the field, it is recommended that the bentonite be added after cement and water are thoroughly mixed. Sodium bentonite with a minimum porosity of 10-8 may also be used.

2. Neat cement, which is a mixture of cement and water consisting of not more than 5 gallons of water per sack (94 pounds) of cement, may be used in lieu of cement-bentonite slurry.

3. Cement-bentonite slurry shall be placed in the annular space in a continuous operation from bottom of the space to be cemented, up to the ground surface. Slurry shall be placed by the circulation or pump-down method unless specified otherwise. The pump-down method may include the "Halliburton" method, inner string cementing, or positive placement-exterior method. The selected method should ensure uniform coverage of slurry throughout the annular space.

4. A suitable cement retainer, packer, shale trap, boot or plug shall be secured to the casing at the appropriate depth to prevent leakage or migration of the slurry into the bottom of the well.

5. The cement-bentonite slurry shall fill a minimum annular space of 1 1/2 inches for 4-inch and smaller wells, and a minimum of 2 inches for 6-inch and larger wells. For cementing methods using a "tremie" or "grouting pipe" placed in the annular space, sufficient space should be provided to accommodate the tremie pipe.

6. If a conductor pipe is used, it shall be cemented in place and the annular space between the well casing and the conductor pipe shall be made watertight by grouting with cement-bentonite slurry from bottom of the conductor pipe to the ground surface.

7. If one or more sands between the ground surface and the production sand contain saline water and/or water of objectionable quality, the annular space between the well casing and the hole shall be sealed with cement-bentonite slurry, at a minimum, to a depth of not less than 20 feet below the deepest sand containing the water of objectionable quality unless full depth cementing is required by §329 C

1. Community public supply wells shall be cemented to their full depth from the top of the producing aquifer to the ground surface.

2. Noncommunity public supply wells shall be cemented from a minimum depth of 50 feet to the ground surface.

3. Industrial and power generation wells shall be cemented to their full depth from the top of the producing aquifer to the ground surface.

4. Observation wells shall be cemented from a minimum depth of 50 feet to the ground surface.

5. Irrigation/agricultural wells shall be cemented from a minimum depth of 10 feet to the ground surface, using the pump-down or the gravity method with or without the tremie pipe.

6. Rig-supply wells shall be cemented from a minimum depth of 50 feet to the ground surface.

7. Monitoring wells shall be cemented along the entire length of the casing unless specified otherwise by the Department of Environmental Quality.

8. Dewatering wells, other than drive-point type, shall be cemented from a minimum depth of 50 feet to the ground surface.

9. Domestic wells shall be cemented from a minimum depth of 10 feet to the ground surface using the pump-down or the gravity method with or without the tremie pipe. A suitable cement retainer, such as a shale trap or boot, as required by §329. B 4, shall be attached to the casing at the 10-foot minimum depth. The use of empty cement sacks in lieu of shale trap or boot shall not be allowed. A long metal rod shall be used to rod the cement slurry to ensure uniform coverage around the casing.

10. Heat pump supply wells for private homes shall be cemented in accordance with requirements for domestic wells; for apartment buildings and other commercial establishments, in accordance with requirements for noncommunity public supply wells, and for industrial plants, in accordance with requirements for industrial wells.