Section 410. Construction; general

A. Casing.

1. Class IIIA wells shall be cased to a depth of at least 100 feet.

2. Class IIIB wells shall be cased to a depth of at least 50 feet.

3. Except as provided in subdivisions a through e below, all Class IIIC and IV wells shall be cased to a minimum depth of 20 feet or terminated not less than one foot in bedrock when bedrock is encountered at a depth less than 20 feet.

a. When in collapsing material, the casing shall terminate in the aquifer but in no instance be less than 20 feet.

b. Where an aquifer is encountered at less than 20 feet, Class IV wells may be cased to within one foot of the water bearing strata. In the instance of Class IV wells the intent of this chapter is to protect ground water quality, and not to ensure a potable water supply.

Exception: Class IV wells placed closer than 50 feet from a building foundation treated with a chemical termiticide or other pesticide shall comply with the minimum casing depth requirements of 12VAC5-630-380 F 2.

c. Alternate casing depths may be accepted for bored wells when the only aquifer lies between 11 and 20 feet provided the casing is placed within one foot of the aquifer and must not be less than 10 feet in depth from the ground surface.

d. Class III C driven wells shall be cased to the water bearing strata; however, in no case less than 10 feet. No minimum casing requirements apply to Class IV driven wells except that in order to protect ground water they shall be capable of meeting the minimum grouting requirements as described in subdivision C 5 e of this section.

e. Closed-loop ground-source heat pump wells do not have to be cased.

4. All private well casings shall be extended at least 12 inches above ground or 12 inches above a concrete floor in well house with a gravity flow drain. The following wells are exempted from this requirement; however, their location shall be permanently marked for easy location in the future:

a. Drilled shallow well suction pump systems that will not operate unless a vacuum is maintained. The casings for these wells are also the suction lines through which water is drawn.

b. Deep well ejector pump systems that utilize a casing adaptor and must maintain a vacuum to operate.

c. Closed-loop ground-source heat pump wells.

d. Heat pump return wells that are completely sealed.

5. All steel casings shall meet or exceed the material specifications found in 12VAC5-630-480.

6. No plastic well casing shall be installed which will exceed 80% of its RHCP (resistance to hydraulic collapse pressure). When experience has shown, in the division's opinion, that the prevailing geologic conditions are subject to collapse or shifting, or where heavy clay or unstable backfill materials occur, plastic well casings may not exceed 50% of the RHCP rating. It shall be the responsibility of the well driller to submit calculations to the division demonstrating that individual well casings do not exceed these ratings.

B. Screens. When used for the prevention of entry of foreign materials, screens shall be free of rough edges, irregularities, or other defects. A positive watertight seal between the screen and the casing shall be provided when appropriate.

C. Grouting.

1. General. All private wells shall be grouted. It is preferred that no openings are made in the side of the well casing.

2. Purpose. The annular space between the casing and well bore is one of the principal avenues through which undesirable water and contaminants may gain access to a well. The goal of grouting a well is to preclude the entrance of undesirable water and contaminants. Therefore, the annular space shall be filled with a neat cement grout, a mixture of bentonite and neat cement or bentonite clay grout specifically approved by the manufacturer for use as a grouting material.

3. Specifications. The grouting material used shall meet the appropriate specification listed below:

a. Neat cement grout shall consist of cement and water with not more than six gallons of water per bag (94 pounds) of cement.

b. Bentonite clay may be used in conjunction with neat Portland cement to form a grouting mixture. The bentonite used must be specifically recommended by the manufacturer as being suitable for use as a well grout material and cannot exceed 6.0% by weight of the mixture.

c. Bentonite clay used for grouting shall be sodium bentonite with a minimum of 20% clay solids by weight of water. The bentonite clay shall be specifically recommended by the manufacturer for use as a grouting material.

Exception: (i) When exceptional conditions require the use of a less fluid grout, to bridge voids, a mixture of cement, sand and water in the proportion of not more than two parts by weight of sand to one part of cement with not more than six gallons of clean water per bag of cement may be used if approved by the district or local health department, or (ii) for bored wells only, a concrete (1-1-2 mix with all aggregates passing a ½-inch sieve) grout with not more than six gallons of clean water per bag of cement may be used provided a minimum three-inch annular space is available and its use approved by the district or local health department.

In cases where an open borehole has been drilled below the depth to which the casing is to be grouted, the lower part of the hole must be backfilled, or a packer must be set in the hole, to retain the slurry at the desired depth. Backfilling the hole with gravel and capping with sand is an acceptable practice. Material ordinarily sold as plaster or mortar sand is usually satisfactory; more than half the sand should be of grain sizes between 0.012 inches and 0.024 inches.

4. Other materials. Other grouting materials may be approved by the division on a case by case basis. Review and approval shall be based on whether the proposed material can consistently be expected to meet the intent of grouting expressed in 12VAC5-630-410 C 2. The proposed material must be an industry acceptable material used for the purpose of grouting water wells.

5. Depth.

a. All Class IIIA wells shall be grouted to a minimum depth of 20 feet.

b. All Class IIIB wells shall be grouted to a minimum depth of 50 feet.

c. All Class IIIC and Class IV wells shall be grouted to a minimum depth of 20 feet when the casing depth is equal to or greater than 20 feet. When the casing depth is less than 20 feet, the casing shall be grouted in accordance with this subsection, from the lower terminus of the casing to the surface.

Exception: Class IV wells placed closer than 50 feet from a building foundation treated with a chemical termiticide or other pesticide shall comply with the minimum grouting depth requirements of 12VAC5-630-380 F 2.

d. Alternate grouting depths may be accepted for bored wells when the only aquifer suitable for a private well lies between 11 and 20 feet provided the grouting shall terminate at least one foot above the aquifer but must not be less than 10 feet in depth from the ground surface.

e. Driven wells shall be grouted to a minimum depth of five feet by excavating an oversize hole at least four inches in diameter larger than the casing and pouring an approved grout mixture into the annular space.

6. Installation. Grout shall be installed by means of a grout pump or tremie pipe from the bottom of the annular space upward in one operation until the annular space is filled, whenever the grouting depth exceeds 20 feet. Pouring of grout is acceptable for drilled wells whenever grouting depth does not exceed 20 feet. Pouring of grout is acceptable for bored wells whenever the grouting depth does not exceed 30 feet provided there is a minimum of a 3-inch annular space. Grouting shall be brought to the ground surface and flared to provide a one foot radius around the casing at least six inches thick. However, whenever pitless adapters are used, the grout shall terminate at the base of the pitless adapter. When an outer casing is necessary to construct a new well, where possible, the outer casing shall be pulled simultaneously with the grouting operation.

7. Annular space. The clear annular space around the outside of the casing and the well bore shall be at least 1.5 inches on all sides except for bored wells which shall have at least a 3-inch annular space.

D. Additional casing and grouting. When a well is to be constructed within 100 feet of a subsurface sewage disposal system, which has been or is proposed to be installed at a depth greater than five feet below the ground surface, the casing and grouting of the water well shall be increased to maintain at least a 15-foot vertical separation between the trench bottom and the lower terminus of the casing and grouting.

E. Well head.

1. General. No open wells or well heads or unprotected openings into the interior of the well shall be permitted. Prior to the driller leaving the well construction site, the owner shall have the driller protect the bore hole by installing a cover adequate to prevent accidental contamination.

2. Mechanical well seals. Mechanical well seals (either sanitary well seals or pitless adapters) shall be used on all wells and shall be water and air tight except as provided in 12VAC5-630-410 F 4.

3. Other. Wells greater than eight inches in diameter shall be provided with a watertight overlapping (shoebox) type cover, constructed of reinforced concrete or steel.

F. Appurtenances passing through casing.

1. General. All openings through well casings shall be provided with a positive water stop.

2. Pitless well adapters. Pitless well adapters shall be subject to approval by the division. All pitless adapters shall be installed according to the manufacturers recommendations.

3. Sanitary well seals. Sanitary well seals shall be subject to approval by the division. All sanitary well seals shall be installed according to the manufacturers recommendations.

4. Venting. Venting, where necessary as determined by the district health department, shall be provided in such a manner as to allow for the passage of air, but not water, insects, or foreign materials, into the well.

Historical Notes

Derived from VR355-34-100 § 3.7, eff. April 1, 1992.

Statutory Authority

§§ 32.1-12 and 32.1-176 of the Code of Virginia.