§ 13.52.050. Well standards.

A.

Standards Adopted. Excepted as otherwise specified, the standards for the construction, repair, reconstruction, or abandonment of wells published in the Department of Water Resources Bulletins 74-81 and 74-90, "Water Well Standards, State of California" and subsequent revisions and addendums are incorporated and made a part of this chapter. Standards for monitoring wells shall be those adopted by the director in conformance with requirements of the Department of Water Resources.

B.

Well Location. All wells shall be constructed to prevent the entrance of surface water and contaminated groundwater into the well or into the producing aquifer, and shall be separated a safe distance from potential sources of contamination and pollution. The following minimum horizontal distances shall be maintained for all wells furnishing potable water for human consumption:

	Agricultural Well (in feet)	Domestic Well (in feet)	Public Well (in feet)*
Agricultural wells		300	300
Areas of intense animal confinement	100	100	100
Leach line or disposal field	150	100	150
Seepage pit or cesspool	150	150	150
Septic tank	150	100	150
Sewer line	50	50	50

 

* The above separation distances are for wells with adequate annular seals drilled in dry upper consolidated formations that are less permeable than sand. Wells drilled in fractured rock formations need to have much greater separation distances.

C.

Well Seals. Wells shall have a sanitary seal, surface seal, and an annular seal. An access opening in the well cap, well casing, or pump base for the purpose of disinfecting the well or measuring the water level shall be protected with a threaded, watertight plug or cap. Air vents shall be installed in an approved manner.

D.

Casing Perforations. Perforation of monitoring well casings shall conform to standards and conditions common to the industry and prescribed by the director.

E.

The well shall be located upstream of the groundwater gradient from potential sources of contamination. If this is not possible, additional permit conditions may apply.

F.

The top of the casing shall be extended a minimum of twelve inches above ground level and/or twelve inches above the one hundred year floodplain to prevent flooding by drainage or runoff from the surrounding land. If the proposed well location appears to be within the one hundred year floodplain as shown on the appropriate Federal Emergency Management Agency (FEMA) flood maps, the applicant shall either provide documentation to show the site is above the floodplain or request an on-site inspection.

G.

All wells shall be accessible for repair and maintenance.

H.

All pump discharge pipes not discharging to the atmosphere shall be equipped with an approved check valve to prevent backflow or back-siphonage into the well when the pump shuts down. The check valve shall be installed between the pump head and the connection to the distribution system or standpipe.

I.

Annular Seal. The annular space between the well casing and the wall of the drilled hole shall be effectively sealed with cement grout or other approved sealant material to protect against contamination or pollution by surface or shallow subsurface waters. The following minimum annular seal depths shall be required:

Type of Well	Minimum Depth of Annular Seal Below Ground Surface (in feet)
Agricultural wells	20
Air conditioning wells	20
Cathodic protection wells	20
Dairy wells	100
Domestic wells	20
Drainage wells	20
Industrial wells	50
Observation and monitoring wells	20
Public wells (community water supplies)	50

 

J.

Sealing Conditions. The following are the requirements to be observed in sealing the annular space:

1.

The sealing material shall consist of neat cement, cement grout, concrete, or bentonite clay, and shall conform to the specifications given in the standards (Department of Water Resources Bulletins 74-81 and 74-90) and subsequent revisions and addendums.

2.

Gravel-Packed Wells. The width of the annular seal space between the wall of the drilled hole and the well casing, where applicable, shall be at least two inches. 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 two inches between the gravel fill pipe and the wall of the drilled hole. If a temporary conductor casing is used, it shall be removed as the sealing material is placed. Where the well is to be gravel packed, a watertight cover shall be installed between the conductor pipe and the inner casing at the top of the well.

K.

Surface Seal.

1.

A concrete surface seal or slab shall be constructed on the ground surface around the top of the well casing and shall be free from cracks or other defects likely to detract from its weathertightness. The slab shall be monolithically poured on thoroughly compacted native earth and shall have a minimum thickness of four inches, and shall be extended at least two feet in all directions from the well casing and four feet or more in one direction if the storage tank is to be at the well location.

2.

The surface of the concrete slab shall be smooth-troweled and shall be graded away from the well casing in all directions for a distance of at least one foot from the casing, at a fall of at least one-fourth inch per foot to provide sufficient fall to drain water away from the casing. The concrete slab shall be poured in contact with the sealant material in the annular space.

L.

Sanitary Seal. A sanitary seal shall form a durable, weatherproof, and watertight seal on top of the well, between the pump base and the top of the well casing. When a pump is offset or submerged, the opening between the well casing and any pipes or cables which enter the well shall be closed by a watertight seal or cap.

M.

Backflow Prevention. All pumping equipment shall be installed with protective devices to prevent the entrance of foreign matter or back siphonage into the well casing. A properly designed air gap may be considered an acceptable protective device for agricultural wells. No person shall install any equipment or mechanism, or use any water-treating chemical or substance, if such equipment, mechanism, chemical or substance may cause pollution or contamination of the domestic water supply. Such equipment or mechanism may be permitted only when equipped with an approved backflow prevention device.

N.

Building Code Compliance. All electrical, plumbing and appurtenant structural work relating to the water well installation or repair shall be performed in conformity with all applicable building code requirements.

O.

Disinfection. All wells and associated equipment furnishing or in contact with potable water for domestic purposes, shall be disinfected after the construction, installation, or repair of the well, pump, or storage equipment and prior to its use or return to operation. The minimum concentration of the disinfectant solution shall be equivalent to at least one hundred ppm (parts per million) of available chlorine, with a minimum contact time of twelve hours.

P.

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 strong and well enough anchored to prevent the introduction of foreign material into the well and to protect the public from a hazardous situation.

1.

Whenever there is an interruption in work on the well (i.e., overnight shutdown during inclement weather, or waiting periods required for the setting up of sealing materials, testing or the installation of the pump), the well opening shall be closed with a cover to prevent the introduction of undesirable material into the well and to protect the public safety.

2.

During interruptions of 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 permitted.

3.

Observation and monitoring wells must meet all standards with exception of the cement surface pad requirement.

Q.

Inactive or Out-of-Service Well. The owner shall continuously maintain any well which is inactive or out of service, so as to be safe and to prevent pollution of any aquifer. A properly maintained inactive or out-of-service well shall not be considered to be an abandoned well. As evidence of intentions for future use, the owner shall properly maintain the well in such a way that:

1.

The well has no defects which shall impair the quality of the water in the well or in the aquifers penetrated;

2.

If the pump has been removed, the well casing shall be covered with a durable, weatherproof, and watertight seal to prevent unauthorized access and entrance of surface contaminants into the well;

3.

The well is covered with a locked watertight cap or other secured means;

4.

The well is marked so that it can be clearly seen;

5.

The area surrounding the well is kept clear of brush or debris.

An inactive well shall not be used for the disposal of any liquid or solid waste.

R.

Abandoned Well. Every abandoned well shall be considered the property owner's responsibility and shall be destroyed in accordance with the methods prescribed in the standards (Department of Water Resources Bulletin 74-81 and applicable revisions and addendums). Abandoned wells must be destroyed to promote and protect the public welfare by preventing pollution of the groundwater and physical injury to persons or damage to property. An abandoned well shall not be used for the disposal of any liquid or solid waste.

If the pump has been removed for repair or replacement, the well shall not be considered abandoned, provided that evidence of repair can be shown. During the repair period, the well shall be adequately covered to prevent injury to people and to prevent the entrance of undesirable water or foreign matter. Observation or test wells used in the investigation or management of groundwater basins by governmental agencies or other appropriate 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. When these wells are no longer used for this purpose or for supplying water, they shall be considered abandoned.

S.

Sampling Faucet. For domestic and public wells, a faucet shall be located on the discharge line ahead of the storage tank.

T.

Water Level Measurements. A sounding tube of at least one and one-half inches in diameter or a sounding port/tap hole of at least one-half inches in diameter, or as approved by the environmental health director, shall be installed on all wells to allow for water level readings to be conducted and reported per Chapter 13.101.050 of Madera County Code

(Ord. No. 674B, § 1, 2-3-15; Ord. 492B § 5, 2007: Ord. 492 (part), 1985).