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disinfectants used in the preparation of solutions must not be outdated, must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.
