Wells

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In San Diego County:

In limited access spaces:
http://www.pacdrill.com Pacific Drilling Co. Tod Clark, President: 619-294-3682 can access spaces only 36" (or less) wide to bring in the drilling rig. $850 to start, $215 per hour. They do not install water production wells, but can turn the well over for someone else to install the pump, etc... Due to the light weight of the smaller rig, some soils may be impractical to drill through.

http://www.sdcounty.ca.gov/deh/wells.html

http://www.sdcounty.ca.gov/deh/lwq/sam/wells_chapter_4.html

http://www.sdcounty.ca.gov/deh/lwq/land_use/services.html#water_wells

http://www.dpla2.water.ca.gov/publications/groundwater/CA_Well_Standards_Bulletin74-81_1981.pdf

Section 7.

A. All wells shall be located and adequate horizontal distance from potential sources of contamination and pollution... {sewers, sanitary or storm sewage leaching fields from septic tanks, sewage and industrial ... ponds, barnyard and stable areas, feedlots, ... disposal sites, takes and pipelines (both above ground and buried) for storage and conveyance of petroleium productions or chemical, etc...}

Most of the factors involved in determining safe distances in a particular area are usually not known. Based on past experience and general knowledge, the following horizontal distances are considered safe where dry upper unconsolidated formations, less permeable than sand, are encountered: {Becuase of the many variables involvedin the determination of the safe horizontal distance of a well from potential sources of contamination and pollution, no one set of distances will be adequate and reasonable for all conditions. In areas where the adverse conditions exist, the distances listed should be increased. Conversely, where especially favorable condidtions exist or where special means of protection, particularly in construction of the well are provided, lesser distances may be acceptable if approved by the enforcing agency.} {If the well is a radial collector well, these distances apply to the furthest extended points of the well. } Sewer, watertight septic tank, or pit privy: 50 feet. Subsurface sewage leaching field: 100 feet. Cesspool or seepage pit: 150 feet. Animal or fowl enclosure: 100 feet. Where in the opinion of the enforcing agency adverse conditions exist, the above distances shall be increase or special means of protection, particularly in the construction of the well, shall be provided.

B. In addition, if possible, the well shall be located up the ground water gradient (upstream) from the specified sources of contamination. By doing so this provides assurance that potential contamination would be moving naturally away from the area of production. However, in an unconfined awuifer consideration shall also be given to the possibility of reversal of gradient near the well due to general decline of the water table. {When water is pumped from a well a drawdown "cone of depression" is formed in the water surface surrounding the well and ground wtaer in the area of th cone flows toward the well. Similar cones formed by nearby wells can influence the shape of the cone or enlarge the area being drawn upon resulting in a chance the in the direction of flow.}

C. The top of the casing shall terminate above grade or above any known conditions of flooding by drainage or runoff from the surrounding land. For community water supply wells this level is defined as above the "...floodplain of a 100 year flood..." or above "...any recorded high tide..." (Section 64417, "Siting Requirements", Title 22 of the California Administrative Code) 1/ If compliance with this requirement for community water supply wells is not possible, the enforcing agency should be contacted reguarding alternative means for protection.  

In addition, the area around the well shall slope away from the well and surface drainage shall be directed away from the well.

D. Where a well is to be near a building, the well shall be far enough from the building so that the well will be accessible for repair, maintenance, etc.

Section 9. Sealing the Upper Annular Space.

The space between the well casing and the wall of the drilled hole (the annular space) shall be effectively sealed to protect it against contamination or pollution by entrance of surface and/or shallow, subsurface waters. 2/ Annular seals are also installed to provide protection for the casing against corrosion, to assure structural integrity of the casing, and to stabilize the upper formations.

A. Minimum depth of seal below ground surface for various uses of wells: Types, Minimum Depth 3/ In those cases where it is not possible to meet or, when necessary, increase, the lateral distances from pollution sources described in Section 8 of these standards, an alternative (or special) means of protection for the well is to increase the depth of the seal. of Seal (below ground surface) Community Water Supply Wells: 50 Feet. Individual Domestic Wells: 30 Feet 4/Exceptions are shallow wells where the water to be developed is at a depth less than 20 feet. In this instance the depth of seal may be reduced but in no case less than 10 feet and special precautions taken in locating the well with respect to sources of pollution. Industrial Wells 50 feet 4/ Agricultural Wells: 20 feet 4/ 5/ The annular space shall be sealed to a depth of 50 feet from the surface when the well is close to sources of pollution listed in Section 8. Air-Conditioning Wells: 20 feet 4/ Observation and Monitoring Wells: 20 feet 6/ Beause the are constructed to measure specific conditions, the annular space in such wells is usually sealed to the intake section "depth-discrete". Depending on the the circumstances, this depth may be very shallow.

In areas 1/ Defined here as those areas in which the mean length of freeze-free period as described by the National Weather Services is less than 100 days, i.e., temperatures at our below 32'F are likely to occur on any day during a period of 265 or more days each year. In general geographic terms, these areas are the northeastern part of the State (parts of Modoc, Lassen and Siskiyou Counties), the north Lahontan area (essentially the eastern slopes of the Sierra Nevada and subsidiary valleys north of Mount Whitney and Mono Lake) and the lake Arrowhead in the San Bernardio Mountains. where freezing is a potential problem. The top of the seal may be below ground surface but in no case more than 4 feet (1.2 meters) below ground surface.

Sealing Conditions. 2/ Methods of sealing are described in Appendix B. Following are requirements to be observed in sealing the annular space:

1. Wells situated in unconsolidated, caving material. An oversized hole, at least 4 inches (100 millimetres) greater in diameter than the production casing, shall be drilled and a conductor casing installed to the depth or seal specified in Part A of this section. The space between the conductor casing and the production casing shall be filled with sealing material. The conductor mar be withdrawn as the sealing material is placed (see Figure 4A).

2. Wells situated in unconsolidated material stratified with significant clay layers. If a clay formation is encountered within 5 feet 1.5 meters) of the bottom of the seal described in Part A of the section, the seal should be extended 5 feed int othe clay formation (thus the depth of seal could be as much as another 10 feet or 3 metres) greater in diameter than the production casing, shall be drilled and the annular space filled with sealing material (see Figure 4B)

If caving material is present, a conductor casing shall be isolated in the annular space sealed as described in 1, above.

3. Wells situated in soft consolidated formations (extensive clays, sandstones, etc.). An oversized hole, at least 4 inches (100 millimeters) greater in diameter than the production casing, call be drilled to the depths of seal specified in Part A of this section and the space between the production casing and the drilled hole shall be filled with sealing material (see Figure 4C).

If a conductor casing is to be installed (to establish a foundation for the construction of the remainder of the well) the oversized hole shall be at least 4 inches greater in diameter than the conductor casing and the annular space between the conductor casing and the drilled hole filled with sealing material to the depth specified in Part A of this section.

4. Wells situated in "hard" consolidated formations (crystaline or metamorphic rock). An oversized hole shall be drilled to the depth specified in Part A of this section and the Annular space filled with sealing material. If there is significant overburden. a conductor casing may be installed to retain it. If the material is heavily fractured, the seal should extend into solid material. If the well is to be open-bottomed (lower section uncased) the casing shall be seated in the sealing material (see Figure 5A).

5. Gravel packed wells.

a. With conductor casing. An oversized hole, at least 4 inches (100 millimeters) greater than the diameter of the conductor casing, shall be drilled to the depth specified in Part A of this section and the modular space between the conductor casing and drilled hole filled with sealing material. (In this case the gravel pack may extend to the top of the well but to prevent contamination by surface drainage, a welded cover shall be installed over the top in the space between the conductor casing and the production casing, see Figure 5B).

b. Without conductor casing. An oversized hole at least 4 inches (100 millimeters) greater in diameter than the production casing, shall be drilled to the depth specified in Part A of this section and the annular space between the casing and drilled hole filled with sealing material. If gravel fill pipes are installed through the seal, the annular seal shall be of sufficient thickness to assure that there is a minimum of 2 inches (50 millimeters) between the gravel fill pipe and the wall of the drilled hole. The gravel pack shall terminate at the base of the seal (see figure 5C). If a temporary conductor casing is used, it shall be removed as the sealing material is placed.

6. For wells situated in circumstances differing from those described above, the sealing conditions shall be as prescribed by the enforcing agency.

7. Converted wells. Wells converted from one use to another particularly those constructed in prior years without annular seals shall have annular seals installed to the depth required in Part A of this section and at the thickness described in Part E. Where it is anticipated that a well will be converted to another use, the enforcing agency may require the installation of a seal to the depth specified for community water supply wells. 1/ This statement presumes that land use planning has taken place and that zoning requirements are in effect.

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