Code of Colorado Regulations
400 - Department of Natural Resources
402 - Division of Water Resources
2 CCR 402-2 - RULES AND REGULATIONS FOR WATER WELL CONSTRUCTION, PUMP INSTALLATION, CISTERN INSTALLATION, AND MONITORING AND OBSERVATION HOLE/WELL CONSTRUCTION
15 - MINIMUM DISINFECTION STANDARDS

Universal Citation: 2 CO Code Regs 402-2 ยง 15

Current through Register Vol. 47, No. 17, September 10, 2024

Basis and Purpose: The statutory authority for this Rule is found in sections 37-91-101(1); 37-91-104(1)(c); 37-91-106(3); and 37-91-110(1)(b) & (2), C.R.S. The purpose of this Rule is to require completed groundwater excavations be properly decontaminated for the use for which they were constructed.

15.1 General Rule - All materials installed in wells or cistern must be thoroughly and carefully cleaned and disinfected to ensure that all harmful or disease-carrying or causing organisms are eliminated. All areas of the well or cistern, including the full casing length and filter pack, must come in contact with the disinfecting solution as provided for in this Rule. Gravel pit or pond/lake wells, dewatering wells, and recovery wells are exempt from this disinfection requirement. Monitoring and observation holes and wells, where the use of a disinfectant may interfere with the purpose of the hole or well, are exempt from this Rule.

15.2 Disinfection Solution

a. Disinfection of wells must be accomplished with chlorine solution or chlorine compounds in solution.

b. Compressed or pelletized chlorine tablets must not be introduced directly into the well or cistern. Such tablets may be used if mixed into a liquid solution prior to placement into the well or cistern. After initial well disinfection, chlorine tablets may be used as part of regular disinfection or maintenance of the well.

c. Prior to the use of other disinfectants, a written request must be submitted and written approval obtained from the Board.

d. Sufficient disinfectant must be used to produce a minimum concentration of one hundred (100) mg/l (milligrams per liter or parts per million) chlorine in the well (see Table 3).

e. Dry disinfectants used in the preparation of solutions must not be outdated, must be full strength, and must be prepared to the required concentration in accordance with the manufacturer's directions for mixing.

TABLE 3

APPROXIMATE QUANTITIES OF CHLORINE FOR PREPARING DISINFECTING SOLUTIONS

One ounce, of dry HTH or equal powder (70% available Chlorine) dissolved in 52.2 gallons of water makes a 100 ppm strength disinfectant solution. One cup of liquid household bleach (5% available Chlorine) mixed into 31.2 gallon? of water makes a 100 ppm strength disinfectant solution. Various proportions can be calculated using the following approximate quantities:

Approximate amount of dry powder or liquid bleach required for a 100 ppm chlorine solution

Diameter of water column (inches)

Volume of water m 100 feet of column (gallons)

Cups of dry powder 1)

Cups of liquid bleach 2)

4

65.5

1/4

3

6

147

1/2

5

8

261

3/4

9

10

408

1

14

12

587

1-1/2

19

1) The volume of dry powder, based on 70% available chlorine, has been rounded up to the next 1/4 cup marking on a standard measuring cup

2) The volume of liquid bleach, based on 5% available chlorine, has been rounded up to the next full cup marking on a standard measuring cup

Cistern Disinfecting Salurian

The approximate amount of dry powder or liquid bleach required for a 100 ppm chlorine solution consists of 1-1/4 cup of dry powder or 16 cups of liquid bleach per 500 gallons

15.3 Placement All wells and cisterns must be disinfected after completion of well construction, cistern installation, and after installation of production equipment. After completion of construction of the well, agitation of the solution is best accomplished through use of a pump and recirculation. If no pump is available, a bailer or plunger must be used. After installation of the pumping equipment, the disinfectant solution must be thoroughly circulated through the entire well and installed water well supply system.

15.4 Contact Time The disinfection solution must be in contact with the well, cistern, pump and distribution system for sufficient time to eliminate any harmful bacteria.

15.4.1 Decontamination of newly-installed wells and cisterns must be accomplished by adding and mixing enough disinfectant to reach a concentration of at least one hundred (100) milligrams per liter. The disinfectant must be left in the well for a minimum ten (10) hours, and must not be intentionally disturbed after that time until the pump is installed.

15.4.2 Following the installation of a new pump in an existing well or cistern, the well, cistern, pump, and the distribution system must be disinfected. After placement, mixing, and circulation, the disinfectant solution must remain undisturbed in the well and distribution system for as long as possible, but not less than three (3) hours, after which time, the residual chlorine concentration must be at least twenty five (25) milligrams per liter.

15.5 Flushing of Disinfectant After disinfection of the entire water system by the pump installer and prior to the use of water, the remaining disinfectant solution must be thoroughly flushed from the well and water supply system and disposed of properly. The disinfectant solution must not be discharged into the surface waters of the State (see Rule 6.8).

15.6 Test Equipment Disinfection All equipment inserted into wells for sampling, measuring, and test-pumping must be disinfected prior to being used in a well unless the entire well will be disinfected after completion of the testing operations. Disinfection of the test equipment must consist of contact with a solution having a minimum concentration of three hundred (300) milligrams per liter total chlorine for a period of not less than fifteen (15) minutes.

15.7 Tanks and Vessels for Hauling and Storing Water for Drilling - Tanks used for hauling water to the drilling site and any vessel used to store water for drilling purposes must be constructed of a material approved for use with potable water and must be regularly decontaminated. Tanks or vessels used for hauling and/or storage of hydrocarbons, waste materials, chemicals, or other contaminants may not be used for hauling or storing water for drilling purposes.

Disclaimer: These regulations may not be the most recent version. Colorado may have more current or accurate information. We make no warranties or guarantees about the accuracy, completeness, or adequacy of the information contained on this site or the information linked to on the state site. Please check official sources.
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