Wells shall be constructed and tested according to the following:
(a) Well Development. The permittee shall develop a well in accordance with the following requirements:
(1) Well development shall consist of cyclic or intermittent pumping, surging, or both, either mechanically or by using water or air under pressure. Development shall continue until all formation cuttings, mud, drilling fluids and additives are removed from the well.
(2) Every well shall be developed by the well driller in order to obtain the full yield of the well and a water quality that meets all of the following requirements.
(b) Well Testing. The well driller shall conduct yield and, when appropriate, drawdown tests as specified in “Rules for the Construction of Groundwater Wells,” Virginia Water Control Board, and shall report results on Form GW2 to the Health Director.
(c) Pumping Equipment.
(1) The pump capacity shall be consistent with the intended use and yield characteristics of the well.
(2) A lightning protective device shall be provided for submersible pumps.
(3) Installation of the pump shall be in accordance with the manufacturer's recommendations and in accordance with “Water Systems Handbook, “ Water Systems Council.
(4) The well shall be vented at the well head to allow for pressure changes within the well due to pumping. Well vents shall be positioned to prevent the entrance of surface water, dust, insects or other foreign material.
(5) Upon completion of installation, the person installing the pump (i.e. the well driller, pump installer or plumber) should disinfect the well, pump and water supply system in accordance with Section 1040.15. The water supply system shall be disinfected in accordance with Section 1040.16 immediately upon completion of construction.
(d) Observation Wells. The Health Director may specify special construction standards for wells installed for the sole purpose of monitoring water quality or water levels.
(e) Domestic Water Supply System Standard.
(1) A well or double well system shall produce at least one gallon per minute.
(2) The water supply system shall produce not less than 500 gallons of water in a two- hour period at least once each day.
(3) If the sustained yield of the well is not capable of meeting the total water supply standard, sufficient storage shall be provided.
(4) Well storage shall conform to the following standards:
A. If well storage is selected, the amount of storage is calculated by subtracting the well yield, as determined in paragraph (e)(2) hereof, over a two-hour period, from 500 gallons.
B. The quantity of water in storage in the well is equal to the number of feet between the unpumped static water level and the level of drawdown as determined in the pump test, as provided in paragraph (f)(2)C. hereof, multiplied by 1.5 gallons per foot for a six-inch well or 0.65 gallons per foot for a four-inch well.
C. If a six-inch well produces a constant one gallon per minute, it will produce 120 gallons in a two-hour period. Therefore, the well storage shall provide 380 gallons (500 gallons - 120 gallons = 380 gallons). To provide this quantity the well shall contain 253 feet of water in storage (380 gallons - 1.5 gallons per foot = 253).
D. Table I has been provided to assist in determining the number of feet of water required in well storage to meet the well water supply standard.
(f) Minimum Yield for Domestic Wells.
(1) Each well shall be tested and approved for yield in accordance with paragraph (f) (2) hereof. Replacement wells servicing an existing improved property are exempt from this requirement.
(2) All wells drilled with a yield determined to be less than five gallons per minute, according to subsection (b) hereof, shall be tested as follows:
A. The pump and related equipment shall be placed in the well and the static water level measurement recorded.
B. Pumping shall begin at a rate of withdrawal greater than five gallons per minute until the water level drops to a point close to the bottom of the well.
C. When the water level reaches this point, the pump rate shall be adjusted so that the water level remains constant (in effect, pumping out any water which is flowing into the well).
D. The volume of water discharged (flow meter reading) and the water level (with an electric tape) shall be measured and recorded at fifteen-minute intervals throughout the test.
E. Water shall be discharged at least fifty feet from the well and on-site disposal systems.
F. A single interruption of pumping of up to fifteen minutes due to equipment failure or other unusual circumstances will be permitted, but the amount of downtime shall be made up by additional pumping at the end of the test.
(3) The criteria for approval shall be a minimum yield of one gallon per minute for six hours of continuous pumping after the well has been pumped out as provided in paragraph (f)(2)B. hereof.
(4) The pump test can be terminated early and the well yield will be considered adequate if:
A. A well cannot be pumped out after three hours of pumping as provided in paragraph (f)(2)B. hereof; and
B. A well yields an average of 2.5 gallons per minute or greater for three hours of continuous pumping, after the well has been pumped out as provided in paragraph (f)(2)B. hereof.
(5) The Health Director may permit two wells to be connected to meet the minimum yield requirement. The well to be connected shall be tested in accordance with the procedure described in paragraph (f)(2) hereof, and each well shall demonstrate a yield of 0.5 gallons per minute or greater throughout the entire uninterrupted drawdown phase.
(6) The person conducting the test shall collect a sample to be analyzed for constituents described in Appendix III.
Table I*
Feet of Storage Required in Well to Meet Total Well Water Supply Standard
Feet of Storage Required in Well to Meet Total Well Water Supply Standard
Nominal Well Sizes (in.) | |||||||
2 | 3 | 4 | 5 | 6 | 7 | 8 | |
Nominal Well Sizes (in.) | |||||||
2 | 3 | 4 | 5 | 6 | 7 | 8 | |
1.0 | --- | --- | --- | 375 | 255 | 190 | 150 |
1.5 | --- | --- | --- | 315 | 220 | 160 | 125 |
2.0 | --- | --- | 400 | 255 | 180 | 130 | 100 |
2.5 | --- | --- | 310 | 200 | 140 | 100 | 80 |
3.0 | --- | 380 | 220 | 140 | 95 | 70 | 55 |
3.5 | --- | 220 | 125 | 80 | 55 | 40 | 35 |
4.0 | 125 | 53 | 35 | 15 | 15 | 10 | 10 |
* Caution: Table I is intended to aid in determining minimum well storage requirements. Additional storage may be necessary to adequately protect the pump during normal operation.
(Ord. 88-14. Passed 9-19-88.)