S.C. Code Regs. 61-71.H - MONITORING WELLS

1. Requirements For All Permanent and Temporary Monitoring Wells.

a. Due to the nature and purpose of a monitoring well, the depth and location requirements in respect to surface water bodies, potential contamination sources, etc., are variable, and shall be approved on a case-by-case basis by the Department. All monitoring wells shall have Department approval prior to installation or abandonment. Prior to the construction of any monitoring well, the following information shall be completed on a form provided and/or approved by the Department and shall be submitted to the Department:

(1) Proposed well location(s) on a scaled map or plat;

(2) Proposed well construction details;

(3) Intended purpose of the well(s);

(4) Well owner's name and mailing address;

(5) Property owner's name and mailing address, if different from the well owner;

(6) Mailing address and county of location where monitoring wells are to be installed, if different from the well owner's or property owner's address;

(7) Proposed parameters to be analyzed; and,

(8) Proposed drilling date.

If any of the information provided to the Department changes, the Department shall be notified at least 24 hours prior to well construction.

b. All monitoring wells shall be drilled, constructed, maintained, operated, and/or abandoned to ensure that underground sources of drinking water are not contaminated.

c. All monitoring wells shall yield water samples and water levels that are representative of the zone monitored.

d. The well owner shall submit all analytical data and water levels obtained from each monitoring well to the Department within 30 days of receipt of laboratory results unless another schedule has been_approved by the Department.

e. Any monitoring well which is destroyed, rendered unusable, or abandoned, shall be reported to the Department, and shall be properly abandoned, revitalized, or replaced as appropriate or as required by permit or regulation.

f. A Water Well Record Form 1903 or other form provided and/or approved by the Department shall be completed and submitted to the Department within 30 days after well completion or abandonment. At a minimum, the form shall contain the following information:

(1) Name and address of facility/owner;

(2) Surveyed or global positioning system location, in latitude and longitude or Universal Transverse Mercator coordinates, of monitoring well(s) on a scaled map or plat;

(3) Driller and certification number;

(4) Date drilled;

(5) Driller's or Geologist's log;

(6) Total depth;

(7) Screened interval;

(8) Diameter and construction details;

(9) Depth to groundwater with date and time measured;

(10) Surveyed elevation of measuring point with respect to an established benchmark.

(11) Monitoring well approval number issued by the Department.

g. Monitoring wells constructed and reported to satisfy permitting or other regulatory requirements are not required to submit duplicate reports under this regulation.

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

2. Additional Requirements for Permanent Conventionally Installed Monitoring Wells

a. Grouting.

(1) These monitoring wells shall be grouted from the top of the bentonite seal to the land surface.

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

(a) 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

(b) 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.

(c) 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.

(3) 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.

(4) 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.

(5) A cement or aggregate reinforced concrete pad at the ground surface of appropriate durability and strength, considering the setting and location of each well, that extends six inches beyond the borehole diameter and six inches below ground surface is required. The pad shall be capable of preventing infiltration between the surface casing and the borehole to the subsurface.

b. Construction and Materials

(1) Casing shall be of sufficient strength to withstand normal forces encountered during and after well installation and be composed of material so as to minimally affect water quality analyses.

(2) Casing shall have a sufficient diameter to provide access for sampling equipment.

(3) A properly hydrated bentonite seal with a minimum thickness of twelve inches directly above the filter pack shall be used, if the well has a filter pack.

(4) The monitoring well intake or screen design shall minimize formational materials from entering the well. The filter pack shall be utilized opposite the well screen as appropriate so that parameter analyses will be minimally affected.

(5) A locking cap or other security devices to prevent damage and/or vandalism shall be used.

(6) Monitoring wells completed below grade shall be in a watertight vault with a well cap to prevent infiltration of surface water into the well.

c. Well Identification.

All monitoring 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:

(1) Company name and certification number of the driller who installed the well;

(2) Date well was completed;

(3) Total depth (feet);

(4) Casing depth (feet);

(5) Screened interval;

(6) Designator and/or identification number.

d. Development.

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

e. Abandonment

Abandonment shall be by forced injection of grout or pouring through a tremie pipe starting at the bottom of the well and proceeding to the surface in one continuous operation. The well shall be filled with either with neat cement, bentonite-cement, or 20% high solids sodium bentonite grout, from the bottom of the well to the land surface.

3. Additional Requirements for Permanent Direct Push Monitoring Wells

a. Direct Push Wells cannot be installed below a confining layer unless it can be demonstrated to the satisfaction of the Department that cross-contamination of the aquifer systems can be prevented.

b. Grouting.

(1) These monitoring wells shall be grouted from the top of the bentonite seal to the land surface.

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

(a) 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

(b) 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.

(c) 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.

(3) The diameter of the annular space shall be large enough to allow for forced injection of grout through a tremie pipe.

(4) 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.

(5) A cement or aggregate reinforced concrete pad at the ground surface of appropriate durability and strength, considering the setting and location of each well, that extends six inches beyond the borehole diameter and six inches below ground surface is required. The pad shall be capable of preventing infiltration between the surface casing and the borehole to the subsurface.

c. Construction and Materials

(1) Casing shall be of sufficient strength to withstand normal forces encountered during and after well installation and be composed of material so as to minimally affect water quality analyses.

(2) Casing shall have a sufficient diameter to provide access for sampling equipment.

(3) The monitoring well intake or screen design shall minimize formational materials from entering the well. The well screen or intake shall be designed so that parameter analyses will be minimally affected.

(4) A locking cap or other security devices to prevent damage and/or vandalism shall be used.

(5) Monitoring wells completed below grade shall be in a watertight vault with a well cap to prevent infiltration of surface water into the well.

d. Well Identification.

All monitoring 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:

(1) Company name and certification number of the driller who installed the well;

(2) Date well was completed;

(3) Total depth (feet);

(4) Casing depth (feet);

(5) Screened Interval;

(6) Designator and/or identification number.

e. Development.

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

f. Abandonment

(1) Permanent Direct Push Wells that do not penetrate a confining layer shall be abandoned by removing all casing from the subsurface and be grouted by forced injection through a tremie pipe from the total depth to the land surface, or by forced injection or pouring of neat cement, bentonite-cement, or 20% high solids sodium bentonite grout through a tremie pipe starting at the bottom of the well and proceeding to the surface in one continuous operation.

(2) Direct Push Wells that penetrate a confining layer shall be abandoned by forced injection or pouring of neat cement, bentonite-cement, or 20% high solids sodium bentonite grout through a tremie pipe starting at the bottom of the well and proceeding to the surface in one continuous operation.

Additional Requirements For Temporary Monitoring Wells

a. Construction and Materials

(1) Casing shall be of sufficient strength to withstand normal forces encountered during and after well installation and be composed of material so as to minimally affect water quality analyses.

(2) Casing shall have a sufficient diameter to provide access for sampling equipment.

(3) The monitoring well intake or screen design shall minimize formational materials from entering the well. The filter pack or intake shall be utilized opposite the well screen as appropriate so that parameter analyses will be minimally affected.

b. Operation and Maintenance

All temporary monitoring wells shall be sealed with a watertight cap or seal until abandoned. Temporary monitoring wells shall be maintained such that they are not a source or channel of contamination before they are abandoned.

c. Abandonment.

(1) All temporary monitoring wells shall be abandoned within 5 days of borehole completion.

(2) A conventionally drilled temporary well shall be abandoned by forced injection of neat cement, bentonite-cement, or 20% high solids sodium bentonite grout through a tremie pipe starting at the bottom of the well and proceeding to the surface in one continuous operation.

(3) A Temporary Direct Push Well that does not penetrate a confining layer shall be abandoned by forced injection of neat cement, bentonite-cement, or 20% high solids sodium bentonite grout through a tremie pipe after the sampling device has been removed.

(4) A Temporary Direct Push Well that penetrates a confining layer shall be abandoned by forced injection of neat cement, bentonite-cement, or 20% high solids sodium bentonite grout through the sampling device as the sampling device is removed from the sub-surface. Abandonment shall occur during the initial withdrawal from the original push borehole and not by a separate tremie tool after the sampling device has been removed to ensure the breech in the confining layer is permanently sealed.

Use of Water Wells as Monitoring Wells.

Due to the variability involved, the use of a potable water well as a monitoring well shall be approved by the Department on a case-by-case basis.

Non-Standard Monitoring Wells

Due to the variability involved, the use of construction methods, techniques, or monitoring well designs not covered in this regulation shall be approved by the Department on a case-by-case basis.

Notes

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