Tehama County Municipal Code Art. IV Destruction of Wells

A. A well that is no longer useful (including exploration and test holes) shall be destroyed in order to:

1. Assure that the groundwater supply is protected and preserved for future use;

2. Eliminate potential physical hazard.

B. Observation or test wells used in the investigation or management of groundwater basins by government agencies or engineering or research organizations are not considered abandoned so long as they are maintained for this purpose. However, such wells shall be covered with an appropriate cap, bearing the label, "Observation Well," and the name of the agency or organization, and preferably shall be locked when measurements are not being made. When these wells are no longer used for this purpose, or for supplying water, they shall be considered abandoned.

(Ord. 1707 § 1(part), 1999)

All persons owning an abandoned well as defined in this chapter, except those excluded by California Health and Safety Code Section 24440, shall destroy it according to the standards contained in this article.

(Ord. 1707 § 1(part), 1999)

All abandoned wells and exploration or test holes shall be destroyed. Destruction of a well shall consist of the complete filling of the well in accordance with the procedures described in Section 9.42.430.

(Ord. 1707 § 1(part), 1999)

A. Preliminary Work. Before the well is destroyed, it shall be investigated to determine its condition, details of construction, and whether there are obstructions that will interfere with the process of filling and sealing. This may include the use of downhole television and photography for visual inspection of the well.

1. If there are any obstructions, they shall be removed, if possible, by cleaning out the hole.

2. Where necessary, to ensure that sealing material fills not only the well casing but also any annular space or nearby voids within the zone(s) to be sealed, the casing should be perforated or otherwise punctured.

3. In some wells, it may be necessary or desirable to remove a part of the casing. However, in many instances, this can be done only as the well is filled. For dug wells, as much of the lining as is possible (or safe) should be removed prior to filling.

B. Filling and Sealing Conditions. The requirements set forth in this subsection are to be observed when certain conditions are encountered:

1. Well Wholly Situated in Unconsolidated Material in an Unconfined Groundwater Zone. If the groundwater supplies are within fifty feet (fifteen meters) of the surface, the upper twenty feet (six meters) shall be sealed with impervious material and the remainder of the well shall be filled with clay, sand, or suitable inorganic material (see subsection (D) of this section).

2. Well Penetrating Several Aquifers or Formations. In all cases the upper twenty feet (six meters) of the well shall be sealed with impervious material. In areas where the interchange of water between aquifers may result in a significant impairment of the quality of water in one or more aquifers, or will result in a loss of artesian pressure, the well shall be filled and sealed so as to prevent such interchange. Sand or other suitable inorganic material may be placed opposite the producing aquifers and other formations where impervious sealing material is not required. To prevent the vertical movement of water from the producing formation, impervious material must be placed opposite confining formations above and below the producing formations for a distance of ten feet (three meters) or more. The formation producing the deleterious water shall be sealed by placing impervious material opposite the formation, and opposite the confining formations for a sufficient vertical distance, but no less than ten feet (three meters) in both directions, or in the case of bottom waters in the upward direction. In locations where interchange is in no way detrimental, suitable inorganic material may be placed opposite the formations penetrated. When the boundaries of the various formations are unknown, alternate layers of impervious and pervious material shall be placed in the well.

3. Well Penetrating Creviced or Fractured Rock. If creviced or fractured rock formations are encountered just below the surface, the portions of the well opposite this formation shall be sealed with neat cement, sand- cement grout or concrete. If these formations extend to considerable depth, alternate layers of coarse stone (one-quarter to four inches) and cement grout or concrete may be used to fill the well. Fine-grained material shall not be used as fill material for creviced or fractured rock formations.

4. Well in Noncreviced, Consolidated Formation. The upper twenty feet (6.1 meters) of a well in a noncreviced consolidated formation shall be filled with impervious material. The remainder of the well may be filled with clay or other suitable inorganic material.

5. Well Penetrating Specific Aquifers, Local Conditions. Under certain local conditions, the enforcing agency may require that specific aquifers or formations be sealed off during destruction of the well.

C. Placement of Material. The requirements set forth in this subsection shall be observed in placing fill or sealing material in wells to be destroyed.

1. The well shall be filled with the appropriate material (as described in subsection D of this section) from the bottom of the well up.

2. Where neat cement grout, sand-cement grout or concrete is used, it shall be poured in one continuous operation.

3. Sealing material shall be placed in the interval or intervals to be sealed by methods that prevent free fall, dilution, and/or separation of aggregates from cementing materials.

4. Where the head (pressure) producing flow is great, special care and methods must be used to restrict the flow while placing the sealing material. In such cases, the casing must be perforated opposite the area to be sealed and the sealing material forced out under pressure into the surrounding formation.

5. In destroying gravel-packed wells, the casing shall be perforated otherwise punctured opposite the area to be sealed. The sealing material shall then be placed within the casing, completely filling the portion adjacent the area to be sealed and then forced out under pressure into the gravel envelope.

6. When pressure is applied to force sealing material into the annular space, the pressure shall be maintained for a length of time sufficient for the cementing mixture to set.

7. To assure that the well is filled and there has been no jamming or bridging of material, verification shall be made that the volume of material placed in the well installation at least equals the volume of the empty hole.

D. Materials. Requirements for sealing and filling materials are as set forth in this subsection:

1. Impervious Sealing Materials. Sealing materials shall have such a low permeability that the volume of water passing through them is of small consequence. Suitable impervious materials include neat cement, sand-cement grout, concrete, and bentonite clay, all of which are described in Section 9.42.340C of this chapter; and well-proportioned mixes of silts, sands, and clay (or cement).

2. Filler Material. Many materials are suitable for use as a filler in destroying wells. These include clay, silt, sand, gravel, crushed stone, native soils, mixtures of the aforementioned types, and those described in subdivision 1 of this subsection. Material containing organic matter shall not be used.

E. Additional Requirements. In all incorporated areas or unincorporated areas where the local enforcement agency deems it necessary, the following additional requirements must be met:

1. A hole shall be excavated around the well casing to a depth of five feet (1.5 meters) below the ground surface and the well casing removed to the bottom of the excavation.

2. The sealing material used for the upper portion of the well shall be allowed to spill over into the excavation to set, the excavation shall be filled with native soil.

F. Temporary Cover. During periods when no work is being done on the well, such as overnight or while waiting for sealing material to set, the well and surrounding excavation, if any, shall be covered. The cover shall be sufficiently strong and well enough anchored to prevent the introduction of foreign material into the well and to protect the public from a potentially hazardous situation.

(Ord. 1707 § 1(part), 1999)