S.C. Code Regs. 61-71.F - INDIVIDUAL RESIDENTIAL AND IRRIGATION WELLS

1. Drilling.

a. The drilling process or use of drilling fluid additives shall not contaminate any aquifer.

b. Water used in the drilling process shall be obtained from a source that will not result in chemical or biological contamination of any aquifer. Water taken directly from ponds, lakes, streams or other surface water sources shall not be used.

2. Grouting.

a. The diameter of the drilled hole shall be large enough to allow for a minimum of 1.5 inches of annular space on all sides of the casing for forced injection of grout through a tremie pipe.

b. Grout is to be composed of neat cement, a bentonite cement mixture, or high solids sodium bentonite grout.

(1) Neat cement grout shall be composed of Class A, Type I Portland Cement mixed with not more than seven (7) gallons of clean water per bag (one cubic foot or 94 pounds) of cement with a density of 15 to 16 pounds per gallon, or to manufacturer's specifications.

(2) Bentonite-cement grout shall be composed of powdered bentonite (less than 5% by weight) mixed at not more than 8 gallons of water to the bag, with a density of 14 to 15 pounds per gallon, or to manufacturer's specifications.

(3) High solids sodium bentonite grout shall have a minimum of 20% solids and be mixed per manufacturer's specifications with water and/or other required additives.

c. Grout shall fill the entire annular space from a minimum depth of twenty feet from the land surface at the time of well completion, unless otherwise approved by the Department. While the Department discourages wells less than 20 feet to be used for human consumption, it is recognized that due to differing hydrogeologic conditions across the state, some wells may need to be screened or completed at depths less than 20 feet to obtain potable water in the shallow aquifer. Therefore, wells less than 20 feet in depth, but no less than 15 feet in depth, are allowed. In these cases, in Type II and Type III wells, grout shall extend from one foot above the screen to the land surface and, in Type I and Type IV wells, the entire annular space shall be filled with grout. Any other minimum well depths may only be allowed per the variance procedure outlined in this regulation.

d. All grouting shall be accomplished using forced injection to emplace the grout. When emplacing the grouting material, the tremie pipe shall be lowered to the bottom of the zone to be grouted. The tremie pipe shall be kept full continuously from start to finish of the grouting procedure, with the discharge end of the tremie pipe being continuously submerged in the grout until the zone to be grouted is completely filled.

e. Wells shall be grouted in-place within five (5) days after borehole completion.

f. When high solids sodium bentonite grouts are used, a vapor barrier at the land surface at least the width of the annular space made of suitable materials, as approved by the Department, such as native soils, gravel, sand, or thermoplastic material, is required for public safety and structural stability of the well.

3. Plumbness and Alignment.

Wells shall be constructed sufficiently plumb and straight so as to cause no interference with intended use.

4. Development.

a. Wells shall be properly developed. In a screened well, development shall be by a method that ensures that water is forced to flow into and out of the screen.

b. Development shall be complete when the well produces water typical of the aquifer being utilized.

5. Well Tested for Yield.

If a yield test is conducted, it shall be by a standard method and accurately measure flow. Results are to be included with the well record to be sent to the Department.

6. Backflow Prevention.

Approved backflow prevention devices are required on all wells that utilize a chemical feed system for any purpose other than water treatment. The backflow prevention device shall be installed so as to preclude any direct pathway for any contaminant to enter an underground source of drinking water.

7. Disinfection.

All individual residential wells and irrigation wells shall be disinfected upon well completion. The well shall also be disinfected upon any well maintenance, repair, pump repair, pump installation, or testing. Disinfectants shall be placed in the well in order to provide a chlorine residual from 50 ppm (milligrams per liter) to 250 ppm for a minimum of four hours before being flushed from the well. The method of chlorination shall be one that insures that the chlorine is uniformly distributed in the well. The well shall be flushed sufficiently after disinfection to remove the disinfectant and to condition the well for use.

8. Well Identification.

These wells shall be properly labeled with an identification plate immediately upon well completion. The identification plate shall be constructed of a durable, weatherproof, rustproof, material. The identification plate shall be permanently secured to the well casing or enclosure floor around the casing where it is readily visible. The identification plate shall be permanently marked to show:

a. Company name and certification number of the driller who installed the well;

b. Date well was completed;

c. Total depth (feet); and,

d. Casing depth (feet).

9. Materials.

a. Casing.

(1) Casing may be driven, lowered, or installed in any manner that will effect a continuous water tight and plumb installation.

(2) A well point, drive pipe, or drive shoe shall be structurally suitable to prevent rupture during the driving of the casing.

(3) Permanent well casing shall be new, seamless, or electric-resistance welded steel or galvanized pipe or thermoplastic pipe.

(4) Casing shall have watertight joints that shall be glued or threaded and coupled if plastic, or electrically welded or threaded and coupled with heavy recessed-type couplings of steel, if metal.

(5) Casing shall be of standards classified by the American Society for Testing and Materials (ASTM) and shall be NSF approved.

(6) New steel casing which bears mill markings and which conforms to the standard and specifications ASTM A-53, ASTM A-120, or American Petroleum Institute (API-5L) for water well pipe shall be used.

(7) Casing weighing less than "standard weight" steel pipe is allowed by the Department for water wells when the following requirements are met:

(a) The casing shall have a minimum nominal wall thickness of 0.188 inches;

(b) Casing meets the requirements of American National Standards Institute and ASTM (ANSI/ASTM) for water well casing.

(8) In consolidated formations, the well casing shall be set into the formation so as to provide a watertight seal between the casing and the top of the consolidated formation.

(9) In unconsolidated material, well casing shall be set into the first confining layer or to twenty feet, whichever is greater.

(10) Casing installed shall extend a minimum of one foot above the land surface at the time of construction. If an above ground pump is used, the casing may extend less than one foot above the land surface or below the land surface with a protective wellhead cover that allows access to the wellhead if the piping connecting the well casing to the pump is glued or threaded and is watertight.

(11) Thermoplastic casing may be used provided the casing:

(a) Conforms to requirements of American National Standards Institute/American Society of Testing and Materials (ANSI/ASTM), specification F480-77 for thermoplastic water well casing pipe and couplings made in standard dimension ratios (SDR);

(b) Has minimum wall thickness and tolerances to meet or exceed requirements for SDR 26 thermoplastic water well casing pipe and couplings made in standard dimension ratios;

(c) Has wall thickness and tolerances to meet or exceed requirements for Schedule 40 thermoplastic water well casing pipe for nominal sizes three inches or smaller;

(d) Can be installed without interference from formational material or other objects that may cause physical damage to the casing during emplacement.

b. Screens.

(1) The well, if constructed to obtain water from an unconsolidated formation, shall be equipped with a screen that will prevent the entrance of formation material into the well after the well has been developed and completed.

(2) The well screen shall meet standards classified by the American Society for Testing and Materials (ASTM) and shall be National Sanitation Foundation (NSF) approved material, and shall be of a strength to satisfactorily withstand chemical or physical forces applied to it during and after installation.

(3) Thermoplastic well screens shall:

(a) Have a minimum wall thickness and tolerance which meet or exceed requirements for schedule 40 thermoplastic water well casing pipe for nominal sizes three inches and smaller;

(b) Have a minimum wall thickness and tolerance which meet or exceed requirements for SDR 26 thermoplastic water well casing for nominal sizes greater than three inches, and;

(c) Be installed in wells without interference from formation material or other objects that may cause physical damage during emplacement and do not exceed manufacturers recommendations for depth placement.

(d) Multi-screened wells shall not connect aquifers or zones that have documented differences:

(1) In water quality that would result in contamination of any aquifer or zone such that any State Primary Drinking Water standard is exceeded;

(2) In static water levels that would result in depletion of water from any aquifer or zone, or significant loss of head in any aquifer or zone.

(e) The bottom of the lower-most well screen shall be plugged or capped.

10. Filter Pack.

When a filter pack is used, the following criteria shall apply:

a. The filter pack shall be composed of uniformly sized, quartz sand or gravel being free from clay, silt, or other deleterious material.

b. The filter pack shall be installed using a method that ensures placement into the annular space around the screens.

c. The filter pack shall be disinfected prior to or during installation.

d. The filter pack shall not connect aquifers or zones that have documented differences:

(1) In water quality that would result in contamination of any aquifer or zone such that any State Primary Drinking Water standard is exceeded;

(2) In static water levels that would result in depletion of water from any aquifer or zone, or significant loss of head in any aquifer or zone.

11. Sanitary Seal.

a. A sanitary seal shall be provided on the top of the well casing.

b. If a vent is used, it shall be of a type to prevent the entrance of contaminants, insects, or rainwater into the well.

12. Reporting.

a. The Water Well Record Form 1903, or other approved form, shall be completed and submitted to the Department by the contractor within thirty days after well completion. In addition to the water well record, the driller shall submit additional information as available such as chemical or bacterial results, if taken, and pumping information.

b. A Form 1903 shall also be submitted for individual residential and irrigation wells that are abandoned.

13. Operations and Maintenance.

a. All wells shall be operated and maintained at all times in such a manner so as to protect underground sources of drinking water from contamination and to protect public health. The well owner may be required to provide additional security against vandalism as appropriate. The well owner is responsible for routine maintenance and operation of the well.

b. The well driller is responsible for ensuring wells are constructed in accordance with this regulation. Once the well driller has provided a properly constructed well to the well owner, the well driller is not responsible for normal wear of the well.

c. A sampling spigot shall be installed on the wellhead.

14. Abandonment.

a. When any well is removed from service or prior to putting in service, the well shall be sealed with a watertight cap or seal. The well shall be maintained such that it is not a source or channel of contamination while it is not in service. Until a well is abandoned, all provisions for protection of the water against contamination and for maintaining sanitary conditions around the well shall be carried out to the same extent as though the well were in routine use. This goal shall be met when conducting repair or maintenance on the well, surrounding structures, or pumps.

b. Any well removed from service for longer than thirty-six months shall be permanently abandoned unless a variance from the Department is requested.

c. Any well that acts as a source of contamination shall be repaired or permanently abandoned immediately after receipt of notice from the Department.

d. Abandonment shall be by forced injection of grout or pouring through a tremie pipe starting at the bottom of the well or fill material and proceeding to the surface in one continuous operation.

e. When an individual residential well or irrigation well is permanently abandoned, at a minimum, the well may be filled with either bentonite-cement, neat cement, 20% high solids sodium bentonite grout, sand, or gravel to no closer than twenty feet below the ground surface. The remaining twenty feet to the ground surface shall be filled with neat cement, bentonite-cement, or 20% high solids sodium bentonite grout.

Notes

S.C. Code Regs. 61-71.F