|
7. To assure that the well is filled and there
<br /> 3. Well penetrating- creviced or fractured has been no jamming or "bridging" of the material, verifica-
<br /> rock. If creviced or fractured rock formations are tion shall be made that the volume of material placed in the
<br /> encountered just below the surface, the portions of the well well installation at least equals the volume of the empty hole.
<br /> oposite this formation shall be sealed with neat cement,
<br /> sand-cement grout, or concrete. If these formations extend D. Materials. Requirements for sealing and fill
<br /> to considerable depth, alternate layers of coarse stone materials are as follows:
<br /> and cement grout or concrete may be used to fill the well.
<br /> Fine grained material shall not be used as fill material for 1. Impervious Sealing Materials. No material
<br /> creviced or fractured rock formations. is completely impervious. However, sealing materials shall
<br /> have such a low permeability that the volume of water passing
<br /> 4. Well in noncreviced, consolidated formation. through them is of small consequence.
<br /> The upper 20 feet (6.1 metres) of a well in a noncreviced,
<br /> consolidated formation shall be filled with impervious Suitable impervious materials include neat cement,
<br /> material. The remainder of the well may be filled with clay sand-cement grout, concrete, and bentonite clay, all of which
<br /> or other suitable inorganic material. are described in Section 9, paragraph D, "Sealing Material"
<br /> of these standards; and well-proportioned mixes of silts,
<br /> 5. Well penetrating specific aquifers, local sands, and clays (or cement), and native soils that have a
<br /> conditions. Under certain local conditions, the enforcing coefficient of permeability of less than 10 feet (3 -metres)
<br /> agency may require that specific aquifers or formations be per year.f Used drilling muds are not acceptable.
<br /> sealed off during destruction of the well.
<br /> 2. Filler Material. Many materials are suit-
<br /> C. Placement of Material. The following require- able for use as a filler in destroying wells. These include
<br /> ments shall be observed in placing fill or sealing material clay, silt, sand, gravel, crushed stone, native soils,
<br /> in wells to be destroyed: mixtures of the aforementioned types, and those described in
<br /> the preceding paragraph. Material containing organic matter
<br /> 1. The well shall be filled with the appro- shall not be used.
<br /> priate material (as described in item D of this section)
<br /> from the bottom of the well up. E. Additional Requirements for Wells in Urban Areas.
<br /> 2. Where neat cement grout, sand-cement grout, In incorporated areas or unincorporated areas
<br /> or concrete is used, it shall be poured in one continuous developed for.multiple. habitation, to make further use of the
<br /> operation. well site, the following additional requirements must be met
<br /> 3. Sealing material shall be placed in the (see Figure 9C):
<br /> interval or intervals to be sealed by methods that prevent
<br /> 1. A hole shall be excavated around the well
<br /> free fall, dilution, and/or separation of aggregates from casing to a depth of 5 feet (1.5 metres) below the ground
<br /> cementing materials.' surface and the well casing removed to the bottom of the
<br /> 4. Where the head (pressure) producing flow is excavation.
<br /> great, special care and methods must be used to restrict the 2. The sealing material used for the upper
<br /> flow while placing the sealing material. In such cases, the portion of the well shall be allowed to spill over into the
<br /> casing must be perforated opposite the area to be sealed and excavation to form a cap.
<br /> the sealing material forced out under pressure into the
<br /> surrounding formation. 3. After the well has been properly filled,
<br /> including sufficient time for sealing material in the excava-
<br /> 5. In destroying gravel-packed wells, the tion to set, the excavation shall be filled with native soil.
<br /> casing shall be perforated or otherwise punctured opposite
<br /> the area to be sealed. The sealing material shall then be F. Temporary Cover. During periods when no work
<br /> placed within the casing, completely filling the portion is being done on the well, such as overnight or while waiting
<br /> adjacent to the area to be sealed and then forced out under for sealing material to set, the well and surrounding excava-
<br /> pressure into the gravel envelope. tion, if any, shall be covered. The cover shall be
<br /> sufficiently strong and well enough anchored to prevent the
<br /> 6. When pressure is applied to force sealing introduction of foreign material into the well and to
<br /> material into the annular space, the pressure shall be protect the public from a potentially hazardous situation.
<br /> maintained for a length of time sufficient for the cementing
<br /> mixture to set. Examples of materials of this type are: very fine sand
<br /> with a large percentage of silt or clay, inorganic silts,
<br /> The limiting dimensions of coarse stone are usually con- mixtures of silt and clay, and clay. Native materials
<br /> sidered to range between 1/4 and 4 inches (6.3 to should not be. used when the sealing operation involves the
<br /> 100 millimetres). use of pressure.
<br />
|