§ 98-55. Water well standards.

(a)

Scope. The water well standards in this section have been designed to meet or exceed the water well standards contained in the department of water resources' bulletins 74-81 and 74-90.

(b)

Well construction. Well construction shall be in accordance with the following:

(1)

Well location with respect to pollutants and contaminants and structures. The well location, with respect to pollutants and contaminants and structures, shall be in accordance with the following:

a.

Separation. All wells must be located an adequate horizontal distance from known or potential sources of pollution or contamination, as specified in the following table:

Pollution Source	Setback (in feet)
Any sewer line (sanitary, industrial, or storm; main or lateral)	50
Watertight septic tank	100
Leach lines	100
Deep trench	100
Leaching pit	150
Stream, ditch, drainage course	50
Animal/fowl enclosure	100
Pond or lake	50
Hazardous materials tank	150

 

Lesser separation distances may be approved by the enforcement agency.

b.

Gradients. Where possible, a well shall be located up the groundwater gradient from potential sources of pollution or contamination. Consideration should be given to the fact that the gradient near a well can be reversed by pumping (see bulletin 74-81, page 28, figure 3) or by other influences.

c.

Flooding and drainage. New water wells and related appurtenances should be located above the regulatory flood datum (RFD) as established by the county department of public works, water resources division. If the well must be installed below the RFD, the following conditions shall apply:

1.

The wellhead must be watertight. This includes chlorination ports, electrical connections, and any other connections or devices which may provide an avenue for entry of floodwater into the aquifer.

2.

The pressure tank, electrical box, air vent, and other devices subject to flood damage or floodwater intrusion shall be located above the RFD.

3.

To prevent floodwater from entering the aquifer if a water line break occurs, an approved checkvalve shall be installed on the main water line within three feet of the wellhead.

4.

Surface drainage shall be directed away from the well.

d.

Accessibility. All wells shall be located an adequate distance from buildings and other structures to allow access for well modification, maintenance, repair, and destruction, unless otherwise approved by the enforcement agency.

(2)

Sealing upper annular space. Sealing of the upper annular space shall be in accordance with the following:

a.

Minimum depth of annular surface seal. The annular surface seal shall extend from ground surface to a depth of at least 50 feet and shall anchor in a satisfactory, impervious stratum. This depth is referred to as the "minimum annular seal depth".

1.

Shallow groundwater. Exceptions to the minimum seal depth may be made for shallow wells at the approval of the enforcement agency, where the water to be produced is at a depth less than 50 feet. In no case shall an annular seal extend to a total depth less than ten feet below land surface.

2.

Vaults. At the approval of the enforcement agency, the top of an annular surface seal and well casing may be below ground surface where traffic or other conditions require, if the seal and casing extend to a watertight and structurally sound subsurface vault, or equivalent feature. In no case shall the top of the annular surface seal be more than four feet below ground surface. The vault shall extend from the top of the annular seal to at least ground surface.

b.

Sealing conditions. The following requirements are to be observed for sealing the annular space. For wells situated in circumstances different from those described as follows, the sealing conditions shall be as prescribed by the enforcement agency:

1.

Wells drilled in unconsolidated caving material. An oversized hole, at least four inches greater in diameter than the outside diameter of the well casing, shall be drilled and a conductor casing, such as hollow stem augers, temporarily installed to at least the minimum annular seal depth. Permanent conductor casing may be used if it is installed in accordance with subsections (b)(2)b.3, which pertains to wells drilled in soft consolidated formations, and (b)(2)b.5, which pertains to gravel packed wells with conductor casing, of this section and if it extends at least to the minimum annular seal depth.

Temporary conductor casing shall be withdrawn as sealing material is placed between the well casing and borehole wall (see bulletin 74-81, page 31, figure 4A). Sealing material shall be placed at least to the minimum annular seal depth. The sealing material shall be kept at a sufficient height above the bottom of the temporary conductor casing as it is withdrawn to prevent caving of the borehole wall.

Temporary conductor casing may be left in place in the borehole after the placement of the annular seal only at the approval of the enforcement agency on a case-by-case basis.

2.

Wells drilled in unconsolidated material with significant clay layers. An oversized hole, at least four inches greater in diameter than the outside diameter of the well casing, shall be drilled to at least the minimum annular seal depth, and the annular space between the borehole wall and the well casing shall be filled with sealing material in accordance with subsection (b)(2)a of this section, which pertains to minimum depth of annular surface seal (see bulletin 74-81, page 31, figure 4B). If a significant layer of clay or clay-rich deposits of low permeability is encountered within five feet of the minimum annular seal depth, the annular seal shall be extended at least five feet into the clay layer. If the clay layer is known to be less than five feet in total thickness, the clay layer shall not be fully penetrated.

If caving material is present within the minimum annular seal depth interval, a temporary conductor casing shall be installed to hold the borehole open during well drilling and placement of the casing and annular seal, in accordance with the requirements of subsection (b)(2)b.1 of this section, which pertains to wells drilled in unconsolidated caving material. Permanent conductor casing may be used if it is installed in accordance with subsections (b)(2)b.3, which pertains to wells drilled in soft consolidated formations, and (b)(2)b.5, which pertains to gravel packed wells with conductor casing, of this section and it extends to at least the minimum annular seal depth.

3.

Wells drilled in soft consolidated formations (extensive clays, sandstones, etc.). An oversized hole, at least four inches greater in diameter than the outside diameter of the well casing, shall be drilled to at least the minimum annular seal depth. The space between the well casing and the borehole shall be filled with sealing material to at least the minimum annular seal depth (see bulletin 74-81, page 31, figure 4C).

If a permanent conductor casing is to be installed to facilitate the construction of the well, an oversized hole, at least four inches greater in diameter than the outside surface of the permanent conductor casing, shall be drilled to the bottom of the conductor casing or to at least the minimum annular seal depth, and the annular space between the conductor casing and the borehole wall shall be filled with sealing material. In some cases, such as in cable tool drilling, it may be necessary to extend permanent conductor casing beyond the required depth of the annular surface seal in order to maintain the borehole. Sealing material is not required between conductor casing and the borehole wall other than the minimum annular seal depth or the depth specified in subsection (b)(6) of this section, which pertains to sealing-off strata.

4.

Wells situated in hard consolidated formations (crystalline or metamorphic rock). An oversized hole shall be drilled to the minimum annular seal depth, and the annular space shall be filled with sealing material. If there is significant overburden, a conductor casing may be installed to retain it. If the well is to be open-bottomed (lower section uncased), the casing shall be seated in the sealing material (see bulletin 74-81, page 33, figure 5A).

5.

Gravel packed wells with conductor casing. An oversized hole, at least four inches greater in diameter than the conductor casing, shall be drilled to the minimum annular seal depth, and the annular space between the conductor casing and the borehole shall be 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 well casing (see bulletin 74-81, page 33, figure 5B).

6.

Gravel packed wells without conductor casing. An oversized hole, at least four inches greater in diameter than the well casing, shall be drilled to the minimum annular seal depth, and the annular space between the well casing and the borehole shall be filled with sealing material. If gravel fill pipes are installed through the seal, the annular seal shall be of sufficient thickness to ensure that there is a minimum of two inches between the gravel fill pipe and the borehole wall. The gravel pack shall terminate at the base of the seal (see bulletin 74-81, page 33, figure 5C). If a temporary conductor casing is used, it shall be removed as the sealing material is placed.

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 minimum annular seal depth and at the thickness described in subsection (b)(2)e of this section, which pertains to radial thickness of seal.

8.

Wells that penetrate zones containing poor-quality water, pollutants, or contaminants. If geologic units or fill known to contain poor-quality water, pollutants, or contaminants are penetrated during drilling, and the possibility exists that poor-quality water, pollutants, or contaminants could move through the borehole during drilling and well construction operations and significantly degrade groundwater quality in other units before sealing material can be installed, precautions (e.g., conductor casing, borehole liners, special drilling equipment, etc.) shall be taken to isolate zones containing poor-quality water, pollutants, or contaminants during drilling and well construction operations.

c.

Conductor casing. For community water supply wells, the minimum thickness of steel conductor casing shall be one-fourth inch for single casing, or a minimum of No. 10 U.S. standard gage for double casing. Steel used for conductor casing shall conform to the specifications for steel casing described in subsection (b)(5) of this section, which pertains to casing.

d.

Sealing material. Sealing material shall consist of neat cement, sand cement, or concrete. Cuttings from drilling, or drilling mud, shall not be used for any part of the sealing material.

1.

Water. Water used to prepare sealing mixtures should generally be of drinking water quality, shall be compatible with the type of sealing material used, be free of petroleum and petroleum products, and be free of suspended matter.

2.

Cement. Cement used in sealing mixtures shall meet the requirements of American Society for Testing and Materials C150, Standard Specification for Portland Cement, including the latest revisions thereof. Special cement setting accelerators and retardants and other additives may be used in some cases. Special field additives for Portland cement mixtures shall meet the requirements of ASTM C494, Standard Specification for Chemical Admixtures for Concrete, including the latest revisions thereof. Cement-based sealing materials shall be constituted as follows:

i.

Neat cement. Neat cement shall be mixed at a ratio of one 94-pound sack of Portland cement to five to six gallons of clean water.

ii.

Sand cement. Sand cement shall be mixed at ratio of not more than 188 pounds of sand to one 94-pound sack of Portland cement (two parts sand to one part cement, by weight) and about seven gallons of clean water. This is equivalent to a "10.3 sack mix."

iii.

Concrete. Concrete shall consist of Portland cement and aggregate mixed at a ratio of at least six 94-pound sacks of Portland cement per cubic yard of aggregate. In no case shall the size of the aggregate be greater than one-fifth the radial thickness of the annular seal.

iv.

Mixing. Cement-based sealing materials shall be mixed thoroughly to provide uniformity and ensure that no lumps exist.

v.

Variations. Ratios of the components of cement-based sealing materials can be varied, depending upon the type of cement and additives used. Enforcement agency approval of variations must be received prior to placement.

3.

Bentonite. Bentonite is allowed as an additive to cement-based sealing mixes, at a ratio of up to six percent by weight of cement used, or as a foundation or transition seal, as described in subsection (b)(2)f.3 of this section, which pertains to foundation and transition seals.

e.

Radial thickness of seal. A minimum of two inches of sealing material shall be maintained between all casings and the borehole wall, within the interval to be sealed, except where temporary conductor casing can not be removed, as noted in subsection (b)(2)b.1 of this section, which pertains to wells drilled in unconsolidated caving material. A minimum of two inches of sealing material shall also be maintained between each casing, such as permanent conductor casing, well casing, gravel fill pipes, etc., in a borehole within the interval to be sealed, unless otherwise approved by the enforcement agency. Additional space shall be provided, where needed, for casings to be properly centralized and spaced and allow the use of a tremie pipe during well construction, if required, especially for deeper wells.

f.

Placement of seal. The placement of the seal shall be in accordance with the following:

1.

Obstructions. All loose cuttings or other obstructions to sealing shall be removed from the annular space before placement of the annular seal.

2.

Centralizers. Well casing shall be equipped with centralizers to ensure the two-inch minimum radial thickness of the annular space is maintained. Centralizers need not be used in cases where the well casing is centered in the borehole during well construction by use of removable tools, such as hollow-stem augers.

Centralizers shall be metal, plastic, or other nondegradable material. Centralizers must be positioned to allow the proper placement of sealing material around the casing within the interval to be sealed.

Any metallic component of a centralizer used with metallic casing shall consist of the same material as the casing. Metallic centralizer components shall meet the same metallurgical specifications and standards as the metallic casing to reduce the potential for galvanic corrosion of the casing.

3.

Foundation and transition seals. A packer or similar retaining device, or a small quantity of sealant that is allowed to set, may be placed at the bottom of the interval to be sealed before the final sealing operations begin to form a foundation for the seal.

A transition seal, up to five feet in length, consisting of bentonite or fine sand, must be placed in the annular space to separate filter pack and cement-based sealing materials.

Transition seals shall be installed by use of a tremie pipe or equivalent. Water shall be added to the bentonite transition seal prior to placement of cement-based sealing materials where bentonite is dry in the borehole. Water shall be added to the bentonite at a ratio of one gallon for every two pounds of bentonite to allow for proper hydration. A minimum of one-half hour shall be allowed for bentonite transition seals to properly hydrate before cement-based sealing materials are placed.

4.

Timing and method of placement. The annular space shall be sealed as soon as practical after completion of drilling or a stage of drilling. In no case shall the annular space be left unsealed longer than 14 days following the installation of casing.

As a minimum, the uppermost 50 feet of sealing material shall be placed in one continuous operation.

Sealing material shall be placed by methods, such as the use of a tremie pipe or equivalent, that prevent freefall, bridging, or dilution of the sealing material, or separation of sand or aggregate from the sealing material. Annular sealing materials shall not be installed by freefall unless the interval to be sealed is dry and no deeper than 30 feet below ground surface.

5.

Groundwater flow. Special care shall be used to restrict the flow of groundwater into a well boring while placing material, where subsurface pressure causing the flow of water is significant.

6.

Verification. The applicant shall verify to the enforcement agency that the volume of sealing material placed at least equals or exceeds the volume to be sealed.

(3)

Surface construction features. Surface construction features shall be as follows:

a.

Openings. Openings into the top of the well which are designed to provide access to the well, i.e., for measuring, chlorinating, adding gravel, etc., shall be protected against entrance of surface waters or foreign matter by installation of watertight caps or plugs. Access openings designed to permit the entrance or egress of air or gas (air or casing vents) shall terminate above the ground and above the regulatory flood datum and shall be protected against the entrance of foreign material by installation of downturned and screened U-bends (see bulletin 74-81, pages 37 and 38, figures 6 and 7). All other openings (holes, crevices, cracks, etc.) shall be sealed.

A sounding tube, taphole with plug, or similar access for the introduction of water level measuring devices shall be affixed to the casing of all wells. For wells fitted with a well cap, the cap shall have a removable plug for this purpose.

1.

Where the pump is installed directly over the casing, a watertight seal or gasket shall be placed between the pump head and the pump base (slab), or between the pump base and the rim of the casing, or a well cap shall be installed to close the annular opening between the casing and the pump column pipe (see bulletin 74-81, pages 37 and 38, figures 6 and 7).

2.

Where the pump is offset from the well or where a submersible pump is used, the opening between the well casing and any pipes or cables which enter the well shall be closed by a watertight seal or well cap.

3.

If the pump is not installed immediately or if there is a prolonged interruption in construction of the well, a watertight cover shall be installed at the top of the casing.

4.

A watertight seal or gasket shall be placed between the pump discharge head and the discharge line, or, for a belowground discharge, between the discharge pipe and the discharge line (see bulletin 74-81, pages 37 and 38, figures 6 and 7).

5.

A concrete base or pad, sometimes called a pump block or pump pedestal, shall be constructed at ground surface around the top of the well casing and contact the annular seal, unless the top of the casing is below ground surface, as provided by subsection (b)(3)b of this section, which pertains to well pits or vaults.

The base shall be free of cracks, voids, or other significant defects likely to prevent water tightness. Contacts between the base and the annular seal, and the base and the well casing, must be watertight and must not cause the failure of the annular seal or well casing. Where cement-based annular sealing material is used, the concrete base shall be poured before the annular seal has set, unless otherwise approved by the enforcement agency.

The upper surface of the base shall slope away from the well casing. The base shall extend at least two feet laterally in all directions from the outside of the well boring, unless otherwise approved by the enforcement agency. The base shall be a minimum of four inches thick.

6.

Where the well is to be gravel packed and the pack extends to the surface, a watertight cover shall be installed between the conductor casing and the inner casing. See subsection (b)(2)b.5 of this section, which pertains to gravel packed wells with conductor casing; subsection (b)(2)b.6 of this section, which pertains to gravel packed wells without conductor casing; and bulletin 74-81, page 33, figure 5.

b.

Well pits or vaults. Well pits or vaults may only be used if approval is obtained from the enforcement agency. If a pit or vault is used, it shall be watertight and structurally sound. The vault shall extend from the top of the annular seal to at least ground surface.

The casing shall extend at least six inches above the top of the annular seal.

The vault shall contact the annular seal in a manner to form a watertight and structurally sound connection. Contacts between the vault and the annular seal, and the vault and the well casing, if any, shall not fail or cause the failure of the well casing or annular seal.

Where cement-based annular seal materials are used, the vault shall be set into or contact the annular seal material before it sets, unless otherwise approved by the enforcement agency.

Cement-based sealing material shall be placed between the outer walls of the vault and the excavation into which it is placed to form a proper, structurally sound foundation for the vault, and to seal the space between the vault and excavation.

The sealing material surrounding a vault shall extend from the top of the annular seal to ground surface. If cement-based sealing material is used for both the annular seal and the space between the excavation and vault, the cement-based sealing material shall be placed between the vault and excavation and contact the cement-based annular seal before the annular seal has set

The vault cover or lid shall be watertight. The lid shall be fitted with a security device to prevent unauthorized access. The outside of the lid shall be clearly and permanently labeled "water well". The vault and its lid shall be strong enough to support vehicular traffic where such traffic might occur.

The top of the vault shall be set at, or above, grade so that drainage is away from the vault. The top of the well casing contained within the vault shall be covered in accordance with requirements under subsection (b)(3)a of this section, which pertains to openings, so that water, contaminants, and pollutants that may enter the vault will not enter the well casing. The cover shall be provided with a pressure relief or venting device for gases.

c.

Enclosure of well and appurtenances. In community water supply wells, the well and pump shall be located in a locked enclosure to exclude access by unauthorized persons.

d.

Pump blowoff. When there is a blowoff or drain line from the pump discharge, it shall be located above any known flood levels and protected against the possibility of backsiphonage or backpressure. The blowoff or drain line shall not be connected to any sewer or storm drain except when connected through an air gap.

e.

Air vents. In community water supply wells to minimize the possibility of contamination caused by the creation of a partial vacuum during pumping, a casing vent shall be installed (see bulletin 74-81, page 38, figure 7). In addition, to release air trapped in the pump column when the pump is not running, air release vents shall be installed (see bulletin 74-81, page 38, figure 7). Air vents are also recommended for other types of wells except those having jet pump installations requiring positive pressure, which cannot have a vent.

f.

Backflow prevention. All pump discharge pipes not discharging or open to the atmosphere shall be equipped with an automatic device to prevent backflow and/or backsiphonage into a well. Specific backflow prevention measures are required for drinking water supply wells, as prescribed in title 17, Public Health, California Code of Regulations (sections 7583—7585 and 7601—7605, effective June 25, 1987).

Irrigation well systems, including those used for landscape irrigation, and other well systems that employ, or which have been modified to employ, chemical feeders or injectors shall be equipped with a backflow prevention device approved by the enforcement agency.

All irrigation wells discharging to a standpipe shall be protected by air gap separation. Air gap separation shall mean a separation of at least two pipe diameters between the well discharge pipe and the rim of the standpipe.

(4)

Disinfection and other sanitary requirements. Disinfection and other sanitary requirements are as follows:

a.

Disinfection. All wells producing water for domestic use, i.e., drinking or food processing, should be disinfected following construction, repair, or when work is done on the pump, before the well is placed in service (see bulletin 74-81, appendix C, for a disinfection procedure).

b.

Gravel. Gravel used in gravel packed wells shall come from clean sources and shall be thoroughly washed before placement into the well. Gravel purchased from a supplier shall be washed at the pit or plant prior to delivery to the well site.

During placement of the gravel in the annular space, disinfectants (usually calcium hypochlorite in tablet or granular form) shall be added to the gravel at a uniform rate (two tablets per cubic foot or one pound of the granular form per cubic yard).

c.

Lubricants. Mud and water used as a drilling lubricant shall be free from sewage contamination. Oil and water used for lubrication of the pump and pump bearing shall also be free from contamination.

(5)

Casing. Standards for casing shall be as follows:

a.

Casing material. All casing material used in well construction shall be new. The following table is a minimum guideline for steel casing (the minimum gage pipe to be used in any well shall be 12 gage):

_____

MINIMUM THICKNESS FOR STEEL WATER WELL CASING

	Diameter
Single Casing Depth of Casing (feet)	6″	8″	10″	12″	14″	16″	18″	20″	22″	24″	30″
0—100	12	12	12	10	10	8	8	8	8	8	3/16
100—200	12	12	10	8	8	8	3/16	3/16	3/16	3/16	¼
200—300	10	10	8	8	8	3/16	3/16	3/16	¼	¼	¼
300—400	10	8	8	3/16	3/16	3/16	¼	¼	¼	¼	5/16
400—600	10	8	3/16	3/16	3/16	¼	¼	¼	5/16	5/16	5/16
600—800	3/16	3/16	3/16	3/16	¼	¼	¼	5/16	5/16	3/8	3/8
>800	3/16	3/16	3/16	¼	¼	¼	5/16	5/16	3/8	3/8	7/16

 

NOTE: Integers are United States standard gage; fractions are thickness, in inches

_____

1.

Steel: standard and line pipe. This material shall meet one of the following specifications, including the latest revision thereof:

i.

API Std. 5L, Specification for Line Pipe.

ii.

API Std. 5LX, Specification for High-Test Line Pipe.

iii.

ASTM A53, Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated Welded and Seamless.

iv.

ASTM A120, Standard Specification for Pipe, Steel, Black and Hot-Dipped Zinc-Coated (Galvanized) Welded and Seamless, for Ordinary Uses.

v.

ASTM A134, Standard Specification for Electric Fusion (Arc)-Welded Steel Pipe (Sizes NPS 16 and over).

vi.

ASTM A135, Standard Specification for Electric-Resistance-Welded Steel Pipe.

vii.

ASTM A139, Standard Specification for Electric Fusion (Arc)-Welded Steel Pipe (Sizes 4 inches and over).

viii.

ASTM A211, Standard Specification for Spiral-Welded Steel or Iron Pipe.

ix.

AWWA C200, AWWA Standard for Steel Water Pipe 6 Inches and Larger.

2.

Structural steel. This material shall meet one of the following specifications of the American Society of Testing and Materials (ASTM), including the latest revision thereof:

i.

ASTM A36, Standard Specification for Structural Steel.

ii.

ASTM A242, Standard Specification for High Strength Low Alloy Structural Steel.

iii.

ASTM A283, Standard Specification for Low and Intermediate Tensile Strength Carbon Steel Plates of Structural Quality.

iv.

ASTM A441, Standard Specification for High-Strength Low Alloy Structural Manganese Vanadium Steel.

v.

ASTM A570, Standard Specification for Hot-Rolled Carbon Steel Sheet and Strip, Structural Quality.

3.

High strength carbon steel sheets (well casing steel). At present, there are no standard specifications concerning this material. However, the major steel producers market products the chemical and physical properties of which are quite similar. Each sheet of material shall contain mill markings which will identify the manufacturer and specify that the material is well casing steel which complies with the chemical and physical properties published by the manufacturer.

4.

Stainless steel. This casing shall meet the provisions of ASTM A409, Standard Specification for Welded Large Diameter Austenitic Steel Pipe for corrosive or High Temperature Service.

5.

Plastic casing.

i.

Thermoplastics. Thermoplastic well casing shall meet the requirements of ASTM F480, Standard Specification for Thermoplastic Well Casing Pipe and Couplings Made in Standard Dimension Ratios (SDR), SCH 40 and SCH 80, including the latest revision thereof.

Pipe made in schedule 40 and 80 wall thicknesses and pipe designated according to certain pressure classifications are listed in ASTM F480, as well as casing specials referencing the following ASTM specifications:

ABS pipe: ASTM D1527, Standard Specification for Acrylonitrile-Butadiene-Styrene (ABS) Plastic Pipe, Schedules 40 and 80.

PVC pipe: ASTM D1785, Standard Specification for Polyvinyl Chloride (PVC) Plastic Pipe, Schedules 40, 80, and 120.

Pressure-rated PVC pipe: ASTM D2241, Standard Specifications for Polyvinyl Chloride (PVC) Pressure-Rated Pipe (SDR Series).

Thermoplastic well casing that may be subject to significant impact stress during or after installation shall meet or exceed the requirements for impact resistance classification set forth in section 6.5 of ASTM F480. Casing that may be subject to significant impact forces includes but is not limited to casing that is installed in large diameter, deep boreholes; and casing through which drilling tools pass following installation of the casing in a borehole.

ii.

Thermoset plastics. Thermoset casing material shall meet the following specifications, as applicable, including the latest revisions thereof:

Filament wound resin pipe: ASTM D2996, Standard Specification for Filament Wound Reinforced Thermosetting Resin Pipe.

Centrifugally cast resin pipe: ASTM D2997, Standard Specification for Centrifugally Cast Reinforced Thermosetting Resin Pipe.

Reinforced plastic mortar pressure pipe: ASTM D3517, Standard Specification for Reinforced Plastic Mortar Pressure Pipe.

Glass fiber reinforced resin pressure pipe: AWWA C950, AWWA Standard for Glass-Fiber-Reinforced Thermosetting-Resin Pressure Pipe.

iii.

Drinking water supply. All plastic casing used for drinking water supply wells, including community supply wells and individual domestic wells, shall meet the provisions of National Sanitation Foundation Standard No. 14, Plastic Piping Components and Related Materials, and any revision thereof. The casing shall be marked or labeled following requirements in NSF Standard No. 14, which includes the requirements of ASTM F480.

iv.

Storage, handling, and transportation. Plastic casing shall not be stored in direct sunlight or subjected to freezing temperatures for extended periods of time. Plastic casing shall be stored, handled, and transported in a manner that prevents excessive mechanical stress. Casing shall be protected from sagging and bending, severe impacts and loads, and potentially harmful chemicals.

v.

Large diameter wells. Because large diameter plastic casing has not been used extensively at depths exceeding 500 feet, special care shall be exercised with its use in deep wells.

6.

Concrete casing. Concrete pipe used for casing should conform to the following specifications, including the latest revision thereof:

i.

ASTM C14, Standard Specification for Concrete Sewer, Storm Drain, and Culvert Pipe.

ii.

ASTM C76, Standard Specification for Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe.

iii.

AWWA C300, AWWA Standard for Reinforced Concrete Pressure Pipe Steel Cylinder Type, for Water and Other Liquids.

iv.

AWWA C301, AWWA Standard for Prestressed Concrete Pressure Pipe, Steel Cylinder Type, for Water and Other Liquids.

7.

Unacceptable casing materials. Galvanized sheetmetal pipe such as downspout, tile pipe, or natural wood shall not be used as well casing.

8.

Other materials. Materials in addition to those described in this subsection may be used as well casing, subject to enforcement agency approval.

b.

Casing installation. All well casing shall be assembled and installed with sufficient care to prevent damage to casing sections and joints. All casing joints above intervals of perforations or screen shall be watertight. Any perforations shall be below the minimum annular seal depth.

Watertight construction of the cased portion of the well shall be carried into an impervious subsurface formation which caps the aquifer. The casing may penetrate more than one aquifer.

The casing shall extend a minimum distance of 12 inches above grade or 12 inches above the regulatory flood datum, except on prior approval of the enforcement agency.

Casing shall be equipped with centering guides or centralizers to ensure the even radial thickness of the annular seal and filter pack.

1.

Metallic casing. Metallic casing may be joined by welds, threads, or threaded couplings. Welding shall be accomplished in accordance with the standards of the American Welding Society or the most recent revision of the American Society of Mechanical Engineers Boiler Construction Code. Metallic casing shall be equipped with a drive shoe at the lower end if it is driven into place.

2.

Plastic casing. Plastic casing may be joined by solvent welding or mechanically joined by threads or other means, depending on the type of material and its fabrication. Solvent cement used for solvent welding shall meet specifications for the type of plastic casing used. Solvent cement shall be applied in accordance with solvent and casing manufacturer instructions. Particular attention shall be given to instructions pertaining to required setting time for joints to develop strength.

The following specifications for solvent cements and joints for PVC casing shall be met, including the latest revisions thereof:

i.

ASTM D2564, Standard Specification for Solvent Cements for Polyvinyl Chloride (PVC) Plastic Pipe and Fittings.

ii.

ASTM D2855, Standard Practice for Making Solvent-Cemented Joints with Polyvinyl Chloride (PVC) Pipe and Fittings.

Plastic casing or screen shall not be subjected to excessive stress during installation and shall not be driven into place. Care shall be taken to ensure that plastic casing and joints are not subjected to excessive heat from cement-based sealing material.

A specifically designed adapter shall be used to join plastic casing to metallic casing or screen.

(6)

Sealing-off strata. In areas where a well penetrates more than one aquifer, and one or more of the aquifers contains water that, if allowed to mix in sufficient quantity, will result in a significant deterioration of the quality of water in the other aquifers or the quality of water produced, the strata producing such poor-quality water shall be sealed off to prevent entrance of the water into the well or its migration to other aquifers.

a.

Strata producing the undesirable quality water shall be sealed off by placing impervious material opposite the strata and opposite the confining formation (see bulletin 74-81, page 47, figure 8). The seal shall extend above and below the strata no less than ten feet, even should the confining formation be less than ten feet in thickness. For bottom waters, the seal shall extend ten feet in the upward direction. The sealing material shall fill the annular space between the casing and the well of the drilled hole in the interval to be sealed and the surrounding void spaces which might absorb the sealing material. The sealing material shall be placed from the bottom to the top of the interval to be sealed.

In areas where deep subsidence may occur, provision shall be made for maintaining the integrity of the annular seal if subsidence occurs. Such preventative measures may include the installation of a sleeve or a slip joint in the casing, which will allow vertical movement in the casing without its collapse.

b.

Sealing material shall consist of neat cement or sand cement, as described in subsection (b)(2)d of this section, which pertains to sealing material.

c.

Sealing shall be accomplished by a method approved by the enforcement agency (see bulletin 74-81, appendix B, for suggested methods).

(7)

Well development. Development, redevelopment, or reconditioning of a well shall be performed with care, by methods that will not damage the well structure or destroy natural barriers to the movement of poor-quality water, pollutants, and contaminants. Acceptable well development, redevelopment, or reconditioning methods include the following:

a.

Overpumping;

b.

Surging or swabbing by use of plungers;

c.

Surging with compressed air;

d.

Backwashing or surging by alternately starting and stopping a pump;

e.

Jetting with water;

f.

Introducing specifically formulated chemicals into a well; and

g.

Combinations of subsection (b)(7)a through (b)(7)f of this section.

Hydraulic fracturing (hydrofracturing) is sometimes an acceptable well development and redevelopment method when properly performed. Good quality water shall be used in hydrofracturing. The water shall be disinfected prior to introduction into a well. Material used as propping agents shall be free of pollutants and contaminants, shall be compatible with the use of the well, and shall be thoroughly washed and disinfected prior to placement in the well.

Development, redevelopment, or reconditioning by use of specially designed explosive charges is, in some cases, another acceptable development method. Explosives shall be used with special care to prevent damage to the well structure and to any natural barriers to the movement of poor-quality water, pollutants, and contaminants. Explosives shall only be used by properly trained personnel.

Wells subjected to chemicals or explosives during development, redevelopment, or reconditioning operations shall be thoroughly pumped to remove such agents and residues immediately after the completion of operations. Chemicals, water, and other wastes removed from the well shall be disposed of in accordance with applicable local, state, and federal requirements. The enforcement agency should be contacted regarding the proper disposal of waste.

(8)

Water quality sampling. Water quality sampling shall be in accordance with the following:

a.

Community water supply wells and certain industrial wells. The water from all community water supply wells and industrial wells which provide water for use in food processing shall be sampled immediately following development and disinfection, and appropriate analysis made.

Rules and regulations governing the constituents to be tested, type of testing, etc., for community water supply systems are contained in chapter 15, Domestic Water Quality and Monitoring, of title 22, California Code of Regulations. Water analysis shall be performed by a laboratory certified by the state department of health services. A copy of the laboratory analysis shall be forwarded to the state department of health services or to the enforcement agency. Approval of the enforcement agency must be obtained before the well is put into use.

Except where there is free discharge from the pump (i.e., no direct connection to the water delivery system such as to a sump), a sample tap (see bulletin 74-81, page 38, figure 7) shall be provided on the discharge line so that water representative of the water in the well may be drawn for laboratory analysis. The tap shall be located so as to prevent backsiphonage to the pump discharge when the pump is shut off (e.g., on the system side of the checkvalve).

b.

Other types of wells. To determine the quality of water produced by a new well, it should be sampled immediately following construction and development. Appropriate analyses shall be made based upon the intended uses of the water.

(9)

Special provisions for large diameter shallow wells. Special provisions for large diameter shallow wells are as follows:

a.

Use as community water supply wells. Because shallow groundwaters are often of poor quality and because they are easily contaminated, the use of bored or dug wells, or wells less than 50 feet deep, to provide community water supplies shall be avoided, unless there is no other feasible means for obtaining water. When used for this purpose, these wells shall be located at least 250 feet from any underground sewage disposal facility.

b.

Bored wells. All bored wells shall be cased with concrete pipe or steel casing the joints of which are watertight from six inches above the ground surface to the minimum annular seal depth. Except where corrugated steel pipe is used as casing, the minimum thickness of the surrounding concrete seal shall be three inches. Where corrugated steel pipe is employed, the joints are not watertight, and a thicker annular seal (no less than six inches) shall be installed.

c.

Dug wells. All dug wells shall be curbed with a watertight curbing extending from above the ground surface to the minimum annular seal depth. The curbing shall be of concrete poured in place or of casing, either precast concrete pipe or steel, surrounded on the outside by concrete.

If the curbing is to be made of concrete, poured in place, it shall not be less than six inches thick. If precast concrete pipe or steel casing is used as part of the curbing, the space between the wall of the hole and the casing shall be filled with concrete to the minimum annular seal depth. The minimum thickness of the surrounding concrete shall be three inches.

d.

Casing material. Either steel, including corrugated steel pipe, or concrete may be used for casing bored or dug wells.

1.

Steel used in the manufacture of casing for bored and dug wells should conform to the specifications for casing material described in subsection (b)(5) of this section, which pertains to casing. Minimum thickness of steel casing for bored and dug wells shall be as follows:

Diameter (inches)	U.S. Standard Gage or Plate Thickness
18	8 gage
24	¼ inch
30	¼ inch
36	¼ inch
42	¼ inch
48	¼ inch

 

Corrugated steel pipe used as casing shall meet the specifications, including the latest revision, of ASTM A444, Standard Specification for Steel Sheet, Zinc Coated (Galvanized) by the HOT-DIP Process for Culverts and Underdrains. The minimum thickness of sheet used shall be 0.109 inch.

2.

Concrete casing can consist of either poured-in-place concrete or precast concrete pipe. Poured-in-place concrete should be sufficiently strong to withstand the earth and water pressures imposed on it during, as well as after, construction. It should be properly reinforced with steel to furnish tensile strength and to resist cracking, and it should be free from honeycombing or other defects likely to impair the ability of the concrete structure to remain watertight. Aggregate small enough to place without bridging should be used. Poured-in-place concrete shall be class A (six sacks of Portland cement per cubic yard) or class B (five sacks per cubic yard).

Precast concrete pipe is usually composed of concrete rings from one to six feet in diameter and approximately three to eight feet long. To serve satisfactorily as casing, these rings should be free of blemishes that would impair their strength or serviceability. Concrete pipe shall conform to the specifications listed in subsection (b)(5)a.6 of this section, which pertains to concrete casing.

e.

Covers. All bored or dug wells shall be provided with a structurally sound, watertight, cover made of concrete or steel.

(10)

Special provisions for driven wells. Special provisions for driven wells (well points) are as follows:

a.

If the well is to be used as an individual domestic well, an oversize hole with a diameter at least three inches greater than the diameter of the pipe shall be constructed to a depth of six feet, and the annular space around the pipe shall be filled with neat cement or sand-cement.

b.

The minimum wall thickness of steel drive pipe shall be not less than 0.140 inch.

c.

Well points made of thermoplastic materials shall not be driven but jetted or washed into place.

(11)

Rehabilitation, repair, and deepening of wells. Rehabilitation, repair, and deepening of wells shall be in accordance with the following:

a.

Rehabilitation is the treatment of a well by chemical or mechanical means, or both, to recover lost production caused by incrustation or clogging of screens or the formation immediately adjacent to the well. The following methods used for rehabilitating a well, when done with care, are acceptable:

1.

Introduction of chemicals designed for this purpose;

2.

Surging by use of compressed air;

3.

Backwashing or surging by alternately starting or stopping the pump;

4.

Jetting with water;

5.

Sonic cleaning;

6.

Vibratory explosives; and

7.

Combinations of subsection (b)(11)a.1—6 of this section.

Methods which produce an explosion, in addition to the use of vibratory explosives mentioned in subsection (b)(11)a.6 of this section, are also acceptable; provided, however, they are used with great care, particularly where aquifers are separated by distinct barriers to the movement of groundwater.

When chemicals or explosives have been used, the well shall be pumped until all traces of them have been removed.

b.

In the repair of wells, material used for casing shall meet the requirements specified in subsection (b)(5) of this section, which pertains to casing. In addition, the requirements contained in subsection (b)(4)a of this section, which pertains to disinfection, and subsection (b)(6) of this section, which pertains to sealing-off strata, shall be followed, when applicable.

c.

Where wells are to be deepened, the requirements of subsection (b)(4) of this section, which pertains to disinfection and other sanitary requirements; subsection (b)(5) of this section, which pertains to casing; subsection (b)(6) of this section, which pertains to sealing-off strata; subsection (b)(7) of this section, which pertains to well development; and subsection (b)(8) of this section, which pertains to water quality sampling, shall be followed.

(12)

Temporary cover. Whenever there is an interruption in work on the well such as overnight shutdown, during inclement weather, or waiting periods required for the setting-up of sealing materials, for tests, for installation of the pump, etc., the well opening shall be closed with a cover to prevent the introduction of undesirable material into the well and to ensure the public safety. The cover shall be held in place or weighted-down in such a manner that it cannot be removed except with the aid of equipment or through the use of tools.

During prolonged interruptions (i.e., one week or more), a semipermanent cover shall be installed. For wells cased with steel, a steel cover, tack-welded to the top of the casing, is adequate.

(c)

Destruction of wells. Standards for the destruction of wells shall be as follows:

(1)

Purpose of destruction. A well that is no longer useful, including exploration and test holes, must be destroyed in order to:

a.

Ensure that the groundwater supply is protected and preserved for further use; and

b.

Eliminate the potential physical hazard.

(2)

Definition of abandoned well. A well is considered "abandoned" or permanently inactive if it has not been used for one year, unless the owner demonstrates intention to use the well again. In accordance with Health and Safety Code § 115700, the well owner shall properly maintain an inactive well as evidence of intention for future use in such a way that the following requirements are met:

a.

The well shall not allow impairment of the quality of water within the well and groundwater encountered by the well.

b.

The top of the well or well casing shall be provided with a cover, that is secured by a lock or by other means to prevent its removal without the use of equipment or tools, to prevent unauthorized access, to prevent a safety hazard to humans and animals, and to prevent illegal disposal of wastes in the well. The cover shall be watertight where the top of the well casing or other surface openings to the well are below ground level, as in a vault, or below known levels of flooding. The cover shall be watertight if the well is inactive for more than five consecutive years. A pump motor, angle drive, or other surface feature of a well, when in compliance with such provisions, shall suffice as a cover.

c.

The well shall be marked so as to be easily visible and located, and labeled so as to be easily identified as a well.

d.

The area surrounding the well shall be kept clear of brush, debris, and waste materials.

If a pump has been temporarily removed for repair or replacement, the well shall not be considered "abandoned" if the conditions of this subsection are met. The well shall be adequately covered to prevent injury to people and animals and to prevent the entrance of foreign material, surface water, pollutants, or contaminants into the well during the pump repair period.

(3)

General requirements. General requirements shall be as follows:

a.

All abandoned wells and exploratory holes (borings) shall be destroyed. Destruction shall consist of the complete filling of the well or exploratory hole in accordance with the procedures described in subsection (c)(4) of this section, which pertains to requirements for destroying wells.

b.

Upon determination that a well is polluted or contaminated, and if reasonable efforts to clear the contamination have been unsuccessful, the enforcement agency shall have the authority to require the permanent destruction of the well.

(4)

Requirements for destroying wells. Requirements for destroying wells shall be as follows:

a.

Preliminary work. Preliminary work shall be conducted in accordance with the following:

1.

Before the well is sealed, it shall be investigated to determine its condition, the details of construction, and whether there are obstructions that will interfere with the sealing process.

2.

The well shall be cleaned, as needed, so that all undesirable materials, including obstructions to filling and sealing, debris, oil from oil-lubricated pumps, or pollutants and contaminants that could interfere with well destruction, are removed for disposal.

The enforcement agency should be contacted to determine requirements for proper disposal of materials removed from a well to be destroyed.

If an obstruction is hardware that cannot be removed, a tremie pipe must be passed below the obstruction to place sealing material to the full depth of the well, leaving the obstruction sealed inside the well.

3.

When necessary, to ensure that sealing material also fills any voids in the annular space, the casing shall be perforated at the appropriate depth.

4.

A hole, at least one foot larger in diameter than the drilled hole, shall be excavated around the well casing to a depth of five feet below ground surface. The well casing shall be cut off, six inches above the bottom of the excavation, and removed. The sealing material shall spill over into the excavation, forming a cap. After the sealing material has set, the excavation shall be filled with compacted native soil.

5.

For dug wells, as much of the lining as possible, or safe, should be removed prior to filling.

6.

Alternatively, a water well may be destroyed by removing all material within the original borehole, including the well casing, filter pack, and annular seal, and the created hole completely filled with appropriate sealing material.

b.

Filling and sealing conditions. All wells shall be sealed so as to prevent interaquifer flow, either through the well or around the outside of the casing. Following are additional requirements to be observed when certain conditions are encountered:

1.

Wells situated in unconsolidated material in an unconfined groundwater zone. In all cases, the upper 50 feet of the well shall be sealed with suitable sealing material, and the remainder of the well shall be filled with suitable fill, or sealing material (see bulletin 74-81, page 55, figure 9A).

2.

Wells penetrating several aquifers or formations. In all cases, the upper 50 feet of the well shall be sealed with impervious material.

In areas where the interchange of water between aquifers will result in a significant deterioration 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 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, in both directions or, for bottom waters, in the upward direction (see bulletin 74-81, page 55, figure 9B).

In locations where the 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.

Wells 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-fourth 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.

Wells in noncreviced, consolidated formations. The upper 50 feet 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.

Wells penetrating specific aquifers under local conditions. Under certain local conditions, the enforcement agency may require that specific aquifers or formations be sealed off during destruction of the well.

c.

Placement of material. Placement of material shall be in accordance with the following:

1.

The well shall be filled with the appropriate material from the bottom of the well up.

2.

As a minimum, the uppermost 50 feet of sealing material shall be placed in one continuous operation.

3.

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

4.

Where the head (pressure) producing flow is great, special care 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 or otherwise punctured opposite the area to be sealed. The sealing material shall then be placed within the casing, completely filling the portion adjacent to 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 ensure that the well is filled and there has been no jamming or bridging of the material, the applicant shall verify 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 fill materials are as follows:

1.

Acceptable impervious sealing materials include neat cement, sand cement grout, and concrete, as described in subsection (b)(2)d.2.iii of this section, which pertains to concrete. Up to six percent, by weight of cement used, bentonite may be added to these cement-based mixes.

2.

Acceptable filler materials include sand and pea gravel.

3.

Drill cuttings or drilling mud shall not be used for any part of the sealing process.

4.

Water shall be clean and free of suspended matter and contaminants.

5.

Cement shall meet ASTM C150, Standard Specification for Portland Cement.

6.

Sand and pea gravel shall be washed and free of organic matter.

7.

Bentonite shall be naturally mined (nonpelletized) sodium montmorillonite, listed by NSF, and shall be contained within the original manufacturer's container or sack.

8.

Cement-based materials shall be constituted as described in subsection (b)(2)d.2 of this section, which pertains to cement.

e.

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. During prolonged interruptions (i.e., one week or more), a semipermanent cover shall be installed.

(d)

Pump standards. All pumps shall be constructed and installed so as to provide protection against contamination and pollution of the aquifers.

(1)

Externally mounted pumps. Standards for externally mounted pumps shall be as follows:

a.

The pump head shall be mounted on a concrete pedestal which slopes away from the pump head.

b.

The pump head shall be sealed to the pedestal.

c.

A concrete slab shall be poured to slope away from the pedestal. It shall extend at least two feet laterally in all directions from the outside of the well boring. The slab shall be a minimum of four inches thick and shall be continuous to the pedestal.

d.

An air relief vent, when needed, shall be constructed of metal tubing or pipe. The vent shall extend at least six inches above the pump base. The end of the vent shall open downward and be protected by 16 or greater mesh screen.

e.

A chlorination tube shall be installed into the casing with a continuous welded bead. This tube shall not protrude into the casing and shall have a screw cap at the exposed end.

f.

A sampling tap shall be installed on the discharge line within three feet of the pump and between the checkvalve and well so that water representative of the water in the well may be drawn for laboratory analysis. A sample tap need not be installed on a single-family residence installation.

g.

Any blowoff or drain lines from the pump discharge shall be so located that there is no hazard to the safety of the underground aquifers by reason of flooding or backsiphonage.

(2)

Internally located pumps. Standards for internally located pumps shall be as follows:

a.

The top of the casing shall be covered by a steel plate or other fixture which may be secured to the casing with a watertight seal. The openings in this plate or fixture, through which the water conductor pipe and electrical wires may enter the well, shall also have a watertight seal.

b.

A chlorination port with screw plug shall be located in the plate or fixture, or a chlorination tube with a screw cap shall be installed in the casing.

c.

A sampling tap shall be installed on the discharge line within three feet of the well and between the checkvalve and well so that water representative of the water in the well may be drawn for laboratory analysis. A sample tap need not be installed on a single-family residence installation.

d.

A concrete slab shall be poured to slope away from the casing. It shall extend at least two feet laterally in all directions from the casing. The slab shall be a minimum of four inches thick and shall be continuous to the casing.

e.

Any blowoff or drain lines from the pump discharge shall be so located that there is no hazard to the safety of the underground aquifers by reason of flooding or backsiphonage.

(Ord. No. 97-01, § 2(6.28.040), 1-2-1997; Ord. No. 97-13, § 2, 3-26-1997; Ord. No. 97-17, § 2, 9-24-1997)