12 Va. Admin. Code § 5-590-840

Current through Register Vol. 40, No. 22, June 17, 2024

Section 12VAC5-590-840 - Groundwater sources

A. A groundwater source includes all water obtained from drilled wells and springs. Wells and springs shall be protected from contamination during construction. All wells intended to serve a waterworks shall be constructed by a certified water well system provider. All wells shall be constructed in a manner to protect groundwater resources by preventing contaminated water or water having undesirable physical, chemical, or radiological characteristics from entering aquifers.

B. All wells located within the Eastern Virginia or the Eastern Shore Groundwater Management Areas shall be constructed in a manner to protect groundwater resources by preventing blending or cross contamination of the aquifers.

1. Wells shall not be constructed with screens in multiple aquifers.

2. Geophysical logging and formation sampling shall be required for all wells during construction, in addition to submitting a Uniform Water Well Completion Report, Form GW-2.

3. Observation and production wells shall be constructed with gravel packs and grout in a manner that prevents movement between aquifers. Gravel pack shall be terminated close to the top of the well screens and shall not extend above the top of the screened aquifer. The remainder of the annular space shall be filled with grout material.

4. Pump intake setting shall be documented and the pump intake shall not be set below the top of a confined aquifer or the bottom of an unconfined aquifer that supplies water to the well.

C. All groundwater sources must be analyzed for chemical, physical, radiological, and bacteriological quality as described in 12VAC5-590-840 K.

D. Wells intended for use as a community waterworks shall be located on a well lot meeting the following minimum requirements:

1. The well lot shall provide a distance of at least 50 feet from the well to all property lines;

2. The owner shall consider the need for a larger well lot for future expansion, the need to provide security measures such as lot fencing, and the need to establish additional well lots for future use;

3. If the well lot does not adjoin a public road, then an access road shall be provided and an access easement recorded as part of the well lot;

4. The well lot shall be graded to divert surface runoff away from the well and to prevent ponding on the well lot; and

5. The well lot and access to the lot shall be located by a survey, and a final plat plan and dedication document prepared and recorded as described in 12VAC5-590-200.

E. Minimum well location requirements:

1. The horizontal distance from the well to any septic tank, sanitary drainfield, pit privy, cesspool, barnyard, animal feed lot, cemetery, geothermal well or source of similar contamination, and all surface runoff from actual or potential sources of contamination shall be at least 50 feet.

2. The horizontal distances from the well to any pipe carrying sewage or pipe in which sewage can back up shall be at least 50 feet.

3. A minimum separation distance of 50 feet shall be maintained between a fuel storage tank and a well; however, a lesser distance may be allowed if the fuel is propane or natural gas, or if it is liquid fuel meeting the following requirements:

a. Liquid fuel tanks shall be located above grade.

b. Liquid fuel tanks shall be double-walled with an inner wall leak-detection alarm or single-walled with a full-capacity containment system constructed of compatible material.

c. Liquid fuel lines shall be located above grade or enclosed in a protective casing if below grade, and liquid fuel tanks shall be provided with a paved and curbed parking pad at the tank filling location.

4. The department shall require a spill response plan if the fuel is stored within 50 ft of the well.

F. The class of well to be constructed shall be determined by the department. A Uniform Water Well Completion Report, Form GW-2, shall be completed and submitted to the department with the project documents, in accordance with procedures in 12VAC5-590-200.

1. Minimum construction requirements for Class I wells:

a. The well shall be drilled and cased to a depth sufficient to exclude undesirable groundwater, but in no case shall this depth be less than 100 feet below finished grade.

b. The diameter of the drill hole shall be at least three inches greater than the outside diameter of the couplings of the casing to be used.

c. For wells constructed in consolidated formations, the lower end of the casing shall terminate in solid rock or other impervious formation when practical to do so.

d. The annular space around the casing shall be grouted to a depth of at least 100 feet in a manner satisfactory to the department. When the outer casing cannot be removed, the annular spacing between the drill hole and the outer casing shall also be sealed in a manner approved by the department.

2. Minimum construction requirements for Class II wells.

a. The well shall be drilled and cased to a depth sufficient to exclude undesirable groundwater, but in no case shall this depth be less than 50 feet below finished grade.

b. The diameter of the drill hole shall be at least three inches greater than the outside diameter of the couplings of the casing to be used.

c. For wells constructed in consolidated formations, the lower end of the enlarged portion of the drill hole should terminate in solid rock or other impervious formation when practical to do so.

d. The annular space around the casing shall be grouted to a depth of at least 50 feet in a manner satisfactory to the department. When the outer casing cannot be removed, the annular spacing between the drill hole and the outer casing shall be sealed in a manner approved by the department.

G. Well construction materials and development.

1. Water used in well construction shall be from a potable water source or from the well under construction.

2. Casing and liner pipe.

a. Steel casing and liner pipe shall meet ASTM, NSF/ANSI/CAN, or AWWA specifications and standards applicable to wells. Steel pipe dimensions shall conform to Table 840.1.

TABLE 840.1Steel Well Casing Pipe
STEEL PIPES
SIZE (inches)	DIAMETER (inches)		THICKNESS (inches)	WEIGHT PER FOOT (pounds)
	External	Internal		Plain Ends	With Threads and Couplings
4	4.5	4.026	0.237	10.79	11.0
6	6.625	6.065	0.280	18.97	19.18
8	8.625	7.981	0.322	28.55	29.35
10	10.750	10.020	0.365	40.48	41.85
12	12.750	12.000	0.375	49.56	51.15
14	14.000	13.250	0.375	54.57	57.00
16	16.000	15.250	0.375	62.58
18	18.000	17.250	0.375	70.59
20	20.000	19.250	0.375	78.60
22	22.000	21.000	0.500	114.81
24	24.000	23.000	0.500	125.49
26	26.000	25.000	0.500	136.17
28	28.000	27.000	0.500	146.85
30	30.000	29.000	0.500	157.53
32	32.000	31.000	0.500	168.21
34	34.000	33.000	0.500	178.89
36	36.000	35.000	0.500	189.57

b. Plastic well casing shall be PVC meeting ASTM F480-14, NSF/ANSI/CAN Standard 61-2020, or AWWA Standard A100-20. Depths shall not exceed the published resistance to hydraulic collapse pressure of the PVC casing, taking into account the installation techniques and grouting methods. Well casing wall thickness shall be sufficient to withstand anticipated formation and hydrostatic pressures and mechanical forces imposed during installation, well development, and use. PVC well casing shall meet the requirements of ASTM, NSF/ANSI/CAN, and AWWA, as applicable.

c. Heavyweight casing pipe may be required under certain geologic and hydrostatic conditions.

d. Where corrosive conditions exist, materials such as coated casings, stainless steel, bronze, or plastic may be used as casings or linings subject to approval by the department, and meeting the requirements of NSF/ANSI/CAN Standard 61-2020.

3. Packers or other well construction materials shall be of a material that will not impart taste, odors, toxic substances, or bacterial contamination to the water in the well. No lead is to be used in packers, flux, piping, etc.

4. Screens, where required, shall:

a. Be constructed of material that will not be damaged by chemical action of groundwater or future cleaning operations;

b. Have size of openings to be based on sieve analysis of the formation to be screened, and shall be adequate to pass flows at a velocity of 0.1 ft/sec or less; and

c. Be installed so that exposure above the pumping level will not occur.

5. Grouting requirements.

a. Neat cement grout shall consist of Portland cement and water with not more than six gallons of water per 94-pound sack of cement, and shall be in place within 48 hours of well construction. A maximum of 6.0%, by weight, bentonite and 2.0%, by weight, calcium chloride, may be added. Other grout mixes may be approved by the department where special conditions warrant.

b. Application.

(1) Grout shall be installed by means of continuous pressure grouting from the bottom of the annular opening upward in one continuous operation until the annular opening is filled.

(2) Sufficient annular opening shall be provided to permit a minimum of 1-1/2 inches of grout around the protective casing, including couplings, if used.

(3) Before grouting wells, suitable fill material such as bentonite, low-strength cement and sand mix, or similar materials that have been approved by the department shall be added to the annular opening below the grout zone to seal and stabilize these areas. Instead of this requirement, the casing may be grouted for its entire depth.

c. Casing shall be provided with sufficient centralizers attached to the casing to allow unobstructed flow and uniform thickness of the grout.

d. Where plastic well casing is used, the heat of hydration of cement mixtures and the hydraulic collapse pressure of the casing shall be taken into consideration when choosing grout composition and placement in accordance with DEQ guidelines.

6. To prevent tampering and contamination of the source water, unused wells shall be capped and locked. Watertight welded metal plates, set screw caps, or screw-on caps are acceptable for temporarily capping a well until the pumping equipment is installed.

H. A well yield and drawdown test shall be performed in accordance with requirements of this subsection. The department may require additional pumping wells, observation wells, or longer duration tests where site conditions warrant.

1. The yield and drawdown test duration shall be a minimum of 48 hours. Data to be collected during the yield and drawdown test shall be recorded on the Well Yield and Recovery Report form provided by the department. When the source water requirements for a noncommunity waterworks are determined to be three gpm or less over normal hours of operation, the 48-hour minimum drawdown test may be reduced to no less than 12 hours. Any reduction shall be approved by the department before conducting the test.

2. Discharge from the pumping well shall be conveyed away from the test site to avoid recharge.

3. Where multiple wells are intended to be used, the location and geology of each well in the vicinity shall be evaluated. The department shall require that:

a. The yield and drawdown test be performed simultaneously on the multiple wells, or

b. During the yield and drawdown test of the pumping well, the water levels of the neighboring wells shall be monitored. If the water level of the neighboring wells declines in response to the pumping well, then additional evaluation shall be required by a professional engineer or a professional geologist with experience in groundwater source evaluations.

4. The department may consider alternative testing methods and analyses as proposed by professional engineers or professional geologists with experience in groundwater source evaluations. Where geological conditions exist that prohibit an accurate determination of well yield using methods prescribed in this subsection, additional testing procedures shall be required on an individual basis and approved by the department.

5. When an aquifer test is required by DEQ for a well located in a GWMA, the yield and drawdown test may be incorporated into the aquifer test plan protocol if approved by the department before conducting the test.

I. Well appurtenances.

1. A sanitary seal shall be provided on the top of the well casing, or a watertight well cap shall be provided when a pitless adapter is installed.

2. The well casing shall extend at least 12 inches above the concrete floor or apron.

3. Where aprons are used, they shall be centered on the well and measure at least six feet by six feet by six inches thick.

4. Provisions shall be made for venting the well casing to the atmosphere. Where vertical turbine pumps are used, vents into the side of the casing may be necessary to provide adequate venting.

5. Each well casing shall be provided with equipment and appurtenances for measuring the water level elevation in the well. Corrosion-resistant materials shall be used. Where necessary, the appurtenances shall be attached firmly to the drop pipe or pump column and in a manner as to prevent entrance of foreign materials.

6. All pitless well units, adapters, and watertight caps shall be listed by the Water Systems Council as certified products, or as approved by the department.

J. Every new, modified, or reconditioned groundwater well or spring shall be disinfected after placement of the final pumping equipment. Wells shall be disinfected in accordance with AWWA Standard C654-13.

K. Water quality tests. Water quality sampling and analysis shall be conducted for every new, modified, or reconditioned well or spring to determine what treatment, if any, is required. All samples shall be analyzed by DCLS or a testing laboratory certified by DCLS. Water quality analytical methods shall conform to requirements contained in 12VAC5-590-440.

1. Bacteriological quality.

a. Bacteriological samples for new or deepened wells shall consist of a series of 20 samples collected at a minimum of 30-minute intervals during the last 10 hours of the yield and drawdown test. These samples shall be analyzed for both total coliform density and E. coli density. See 12VAC5-590-380 G for groundwater disinfection treatment requirements, and see 12VAC5-590-430 for surface water influence determinations.

b. Bacteriological samples for modified or reconditioned wells shall consist of two samples collected at least 30 minutes apart, at a minimum, while the pump is in continuous operation. These samples shall be analyzed for both total coliform density and E. coli density. More samples may be required by the department, depending on the work performed.

2. Samples for new wells shall be collected for chemical, physical, and radiological contaminants listed in Tables 340.1 through 340.4. SOC tests may be waived by the department if supported by the source water assessment of vulnerability to contamination. Chemical sampling analysis for a TNC may be limited to nitrate and nitrite only. Samples shall be collected at the end of the yield and drawdown test and after the well water has shown no further change in the clarity of the water. Chemical, physical, and radiological constituent testing for modified or reconditioned wells shall be determined on an individual basis by the department.

L. Observation wells:

1. Shall be constructed in accordance with the requirements of DEQ if they are constructed in a GWMA. Otherwise, they shall be constructed in accordance with 12VAC5-630-420 if they are to remain in service as observation wells after completion of the groundwater study.

2. Shall be protected to preclude the entrance of contamination.

M. Sealing of select zones. All zones containing water of undesirable quality or zones to be protected but excluded from final well completion shall be grouted from a point at least five feet above the zone to a point at least five feet below the zone.

N. Gravel packed wells:

1. The gravel utilized shall be free of foreign material, properly sized, washed, and then disinfected before or during placement.

2. The gravel refill pipes, when used, shall be incorporated within the pump foundation or concrete apron and terminated with screwed or welded caps at least 12 inches above the pump house floor or concrete apron.

3. The gravel refill pipes in the grouted annular opening shall be surrounded by a minimum of 1-1/2 inches of grout.

4. A means for the prevention of leakage of grout into the gravel pack of the screen shall be provided.

5. The minimum protective casing and grouted depth shall be acceptable to the department.

6. Wells located in a GWMA shall have gravel packing installed in accordance with 12VAC5-590-840 B 3.

O. Radial water collector systems shall be considered on an individual basis by the department.

P. Flowing artesian wells located outside a GWMA will be considered on an individual basis by the department.

1. The well shall be equipped with a pitless adapter specifically designed for pressurized artesian wells.

2. Special well construction, casing, and sealing may need to be considered for flowing artesian wells.

Q. Capacity determination of wells used for community waterworks shall meet the daily water demand.

1. Capacity of wells located in consolidated rock formations shall be determined by the well sustainable yield, and the actual installed (production) well pump capacity, whichever value is less. The sustainable yield shall be calculated as follows:

(A x 1440 min/day) / 1.8 = gpd well sustainable yield, where A = well yield (gpm) determined by the yield and drawdown test conducted in accordance with 12VAC5-590-840 H.

2. Capacity of wells located in unconsolidated formations shall be determined by the well yield and the actual installed (production) well pump capacity, whichever value is less.

R. Waterworks serving 50 or more residential connections employing only wells providing the source water shall include at least two wells. If only two wells are provided, then the second well shall be rated for at least 30% of the waterworks permit capacity.

S. The owner of a waterworks serving fewer than 50 residential connections with a single well providing the source water shall provide or have ready access to a replacement pump and other components and materials needed for pump replacement. Instead of this requirement, the owner may provide 48 hours of total finished water storage volume based on the maximum daily water demand.

T. Springs.

1. The water quality of spring sources shall be established by obtaining samples over a period of time agreeable to the department to assess the bacteriological, physical, chemical, and radiological characteristics.

2. Springs shall be housed in a permanent structure and protected from entry of surface water.

3. The amount of land required for protection of the spring source shall be determined by the owner and approved by the department.

4. The design of spring sources shall provide for continuous disinfection.

5. The capacity of spring sources shall be determined using actual flow data.

a. Sufficient daily flow data shall be collected to conduct a frequency distribution analysis. The capacity of a spring source is defined as the low flow rate for one day with a projected recurrence period of 30 years (i.e., 30-year, one-day low flow).

b. The Log-Pearson Type III method of frequency distribution analysis shall be used to make the determination, with a minimum of 1,000 daily flow measurements.

c. If sufficient data is not available to conduct the analysis specified in this subsection, then the lowest recorded daily flow rate may be considered to be the spring capacity. Sufficient flow records shall be available to capture the spring flow during drought conditions, and shall be acceptable to the department.

12 Va. Admin. Code § 5-590-840

Derived from VR355-18-008.03 § 3.21, eff. August 1, 1991; amended, Virginia Register Volume 9, Issue 17, eff. June 23, 1993; Amended, Virginia Register Volume 37, Issue 20, eff. 6/23/2021.

Statutory Authority: §§ 32.1-12 and 32.1-170 of the Code of Virginia.