2 CCR 402-2
DEPARTMENT OF NATURAL RESOURCES Board of Examiners of Water Well Construction and Pump Installation Contractors RULES AND REGULATIONS FOR WATER WELL CONSTRUCTION, PUMP INSTALLATION, CISTERN INSTALLATION, AND MONITORING AND OBSERVATION HOLE/WELL CONSTRUCTION 2 CCR 402-2 [Editor’s Notes follow the text of the rules at the end of this CCR Document.] ______________________________________________________________________ Rule 1 Title 1.1 The title of these rules and regulations is “Rules and Regulations for Water Well Construction, Pump Installation, Cistern Installation and Monitoring and Observation Hole/Well Construction.” The short title for these rules and regulations is “Construction Rules” and they may be referred to herein collectively as the “Rules” or individually as a “Rule.” Rule 2 Authority 2.1 These Rules are promulgated pursuant to the authority granted the State Board of Examiners of Water Well Construction and Pump Installation Contractors (the “Board” or “Board of Examiners”) in sections 37-91-104(1)(b), (c), (j) & (k); 37-91- 106(3) & (4); 37-91-109(1) & (2); and 37-91- 110(1) & (2), C.R.S. Rule 3 Scope of Rules Basis and Purpose: The statutory authority for this Rule is found in sections 37-91- 101(1); 37-91-102; 37- 91-104(1)(c), (j), & (k); 37-91-106(3) & (4); and 37-91-110(2), C.R.S. The purpose of this Rule is to identify the activities and individuals to which these Rules apply.
3.1 These Rules apply to the construction and repair of water wells, test holes, dewatering wells, monitoring and observation holes and wells; well plugging, sealing, and abandonment; and pump and cistern installation and repair, as those terms are defined by these Rules and section 37-91- 102, C.R.S.
3.2 These Rules do not apply to excavations made for the purpose of obtaining or prospecting for minerals or to those wells subject to the jurisdiction of the Oil and Gas Conservation Commission as provided in Article 60 of Title 34, C.R.S., or to those wells subject to the jurisdiction of the Mined Land Reclamation Board as provided in Article 32 of Title 34, C.R.S. (Minerals), and Article 33 of Title 34, C.R.S. (Coal). See section 37-91-102(16)(b)(I), C.R.S.
3.3 These Rules apply to licensed well construction and pump installation
3.4 Reference Materials - Information on examining or acquiring reference materials referred to in these rules, including American Society for Testing and Materials
3.5 These Rules shall not be construed to establish or alter the jurisdiction of either the State of Colorado or the Southern Ute Indian Tribe over the construction and repair of water wells, test holes, dewatering wells, monitoring and observation holes and wells; well plugging, sealing, and abandonment; and pump and cistern installation and repair within the boundaries of the Southern Ute Indian Reservation as recognized in Pub. L. No. 98-290, S 3, 98 Stat. 201 (1984) Rule 4 Purpose of Rules Basis and Purpose: The statutory authority for this Rule is found in sections 37-91- 104(1)(c), (j), & (k); 37- 91-106(3) & (4); and 37-91-110(2), C.R.S. The purpose of this Rule is to identify the broad purposes for the Rules.
4.1 To enable the Board to carry out the provisions of Article 91 of Title 37, C.R.S.
4.2 To safeguard the public health of the people of the State of Colorado and to protect the groundwater resources of the State of Colorado.
4.3 To set minimum standards for the construction, repair, plugging, sealing, and abandonment of all wells, test holes, monitoring and observation holes and wells, and dewatering wells.
4.4 To allow certain types of monitoring and observation holes, monitoring and
4.5 To set minimum standards for the installation and repair of pumping equipment and cisterns.
4.6 To set minimum standards for the reporting, testing, sampling, measuring, and disinfection of all wells and associated water well supply systems, to the extent such standards are required for the proper construction and repair of water wells. Rule 5 Definitions Basis and Purpose: The statutory authority for this Rule is found in sections 37-91- 101(1); 37-91-102; 37- 91-104(1)(c), (j), & (k); 37-91-106(3) & (4); and 37-91- 110(2), C.R.S. The purpose of this Rule is to identify the terms used throughout the Rules.
5.1 Statutory Definitions - Certain terms used in these Rules have the identical meaning as provided in section 37-91-102, C.R.S., as quoted and cited in Rule 5.2.
5.2 Specific Definitions - Unless expressly stated otherwise, the following terms when used in these Rules have the meaning indicated in this Rule. Terms used in the singular include the plural.
Figure 1 Administrative Denver Basin Figure 1. Administrative Denver Basin and Denver Basin Aquifer Extents. Note Boulder Complex Area is in the Administrative Denver Basin but are not considered Denver Basin Aquifers.
Figure 2. Annular Space” is the distance marked “x”
Figure 3. Boundaries of the High Plains Aquifer, the Northern High Plains Designated Basin, and the Southern High Plains Designated Basin
A dewatering system is not the same as a “dewatering well” defined by section 37-91-102(4.5), C.R.S.
Dry holes constructed under a valid well permit are not Test Holes as defined in Rule 5.2.57.
Temporary wells completed for environmental groundwater investigations are monitoring and observation holes. A monitoring and observation hole may only be constructed upon a notice of intent. See Rules 6.3 & 14.2.1. A monitoring and observation hole must be plugged, sealed, and abandoned in less than eighteen (18) months from the date it was constructed unless a permit for a monitoring and observation well has been obtained from the State Engineer. See Rule 14.2.1. A monitoring and observation hole is not a test hole (see Rule 5.2.57 for definition of “test hole”).
C.R.S., 2023).
5.3 Other Definitions All other words used herein must be given their usual,
Rule 6 General Rules Basis and Purpose: The statutory authority for this Rule is found in sections 37-91- 101(1); 37-91-102; 37- 91-104(1)(c), (j), & (k); 37-91-106(3); and 37-91-110(2), C.R.S. The purpose of this Rule is to implement general statutory provisions that apply to well construction and the installation of pumping equipment.
6.1 The process for obtaining and maintaining a license for the construction of wells or the installation of pumping equipment or cisterns, or any special licenses issued pursuant to the Board’s authority in section 37-91-105(2.5), C.R.S., is codified in the Board’s Rules and Regulations for Administration of Licensing, Financial Responsibility, Continuing Education and Remedial Action, 2 CCR 402- 14.
6.2 Compliance with Well Permits
6.3 Prior Notice of Dewatering Well, Monitoring and Observation Hole, and Test Hole In accordance with the requirements of the State Engineer, the Division of Water Resources must be provided with a Notice of Intent (see Rule 5.2.36) no less than three (3) days, including at least one standard business day, prior to the construction of the following:
6.4 Emergency Authorization - Pursuant to the procedures of the State Engineer, the State Engineer or their designee may approve the construction of dewatering wells or monitoring and observation holes with less than the required notice upon the State Engineer’s determination that such approval is warranted based on certain conditions, such as public safety, practical difficulties, or unusual hardship.
6.5 Requests for Well Site Information - Upon request by the State Engineer or their staff, all water well construction and pump installation contractors, authorized individuals, private drillers, and private pump installers must identify the permit number or other authorization and the location of any wells, test holes, cisterns connected to a water well supply system, or monitoring and observation holes or wells which that person expects to work on within a specified five (5) day period.
6.6 Compliance with Regulations - All well construction and pump and cistern
6.7 Products Containing Toxic Materials - Products, such as solder and fluxes that contain any more than 0.20% lead, and materials, such as pipes, fittings, fixtures or pipe joint compounds, that are not considered “lead free” (per 40 CFR 143.12(a) of the Safe Drinking Water Act) are prohibited from being used in the construction, repair, rehabilitation, hydraulic fracturing of a water well, or abandonment of wells and holes. Known toxic materials must not be used in well construction.
6.8 Disposal of Fluids Resulting from Well Construction, Development and
6.9 Water Used for Well Construction and Stimulation - All water used during the construction, development, and stimulation, including hydraulic fracturing, of a well must be obtained from an approved public supply.
6.10 Fluids and Additives– The use of fluids and additives must comply with all
TABLE 1: SUMMARY OF LICENSING AND CONSTRUCTION AUTHORIZATION REQUIREMENTS STRUCTURE WHO MAY CONSTRUCT REQUIRED AUTHORIZATION Type of Well or Licensed Authorize Special Approved Approved Borehole d License Well Notice of Individual Permit Intent BOREHOLE DOES NOT PENETRATE THROUGH A CONFINING UNIT* Water well X X Gallery/infiltration X X X well Monit./observ. well, recovery well, & X X X X certain dewatering system Monit./observ. holes X X X X & dewatering wells Test holes X X X BOREHOLE DOES PENETRATE THROUGH A CONFINING UNIT* Water well X X Monit./observ. well, recovery well & X X X certain dewatering system Monit./observ. hole and X X X dewatering well Test holes X X X *As defined in Rule 5.2.13 Notes:
Rule 7 Licensing For rules and regulations concerning the Board’s licensing procedures, see Rules and Regulations for Administration of Licensing, Financial Responsibility, Continuing Education and Remedial Action (BOE Rules) 2 CCR 402-14. Rule 8 Financial Responsibility For rules and regulations concerning the Board’s bonding and financial responsibility requirements, see Rules and Regulations for Administration of Licensing, Financial Responsibility, Continuing Education and Remedial Action (BOE Rules) 2 CCR 402-14. Rule 9 Wells and Holes Which May Be Constructed by Persons Other Than Licensed Well Construction Contractors Basis and Purpose: The statutory authority for this rule is found in sections 37-91- 101(1); 37-91-104(1)(c), (j), & (k); 37-91-106(3); and 37-91-110(2), C.R.S. The Purpose of this Rule is to identify the basic types of activities that may be completed by persons that are not licensed for water well construction or pump installation, as well as notification and reporting requirements. Additionally, this Rule identifies certain structures that do not have minimum construction standards.
9.1 This Rule 9 applies to those wells and holes which may be constructed by
9.2 Excavations Authorized by this Rule The following types of excavations that do not penetrate through a confining unit between aquifers recognized by the State Engineer may be designed, constructed, used, and plugged, sealed and abandoned by authorized individuals (see Table 1 for a summary of who is authorized to construct each type of well):
9.3 Construction Standards The excavations authorized under this Rule 9 must be
9.4 If during construction of an excavation authorized by this Rule 9, the borehole penetrates through a confining unit into a lower aquifer, the hole must be plugged back through the confining unit with at least twenty (20) feet of cement or cement-bentonite grout or through the entire confining unit, whichever is greater, or the hole must be plugged, sealed and abandoned pursuant to Rule 16 within twenty-four (24) hours.
9.5 Plugging, Sealing and Abandonment - Excavations authorized by this Rule 9
9.6 Conversion to Water Wells Prohibited - A monitoring and observation hole,
Rule 10 Minimum Construction Standards for Water Wells Basis and Purpose: The statutory authority for this rule is found in sections 37-91- 101(1); 37-91-102; 37- 91-104(1)(c), (j), & (k); 37-91-106(3); 37-91-109(1); and 37-91- 110(2), C.R.S. The purpose of this Rule is to identify the minimum construction standards for water wells or other excavations constructed in different types of aquifers in Colorado, in order to ensure that such construction prevents harm to the public health, will not impair water quality or cause contamination of shared groundwater resources, and will ensure the safety of groundwater resources for Colorado’s existing and future populations.
10.1 General - To assist in the orderly development of the groundwater resources of Colorado, to insure the protection of the public health, and to prevent degradation of the groundwater resource, all wells constructed to withdraw or inject water must be constructed, maintained, or repaired in such a manner that will:
10.1.1 The contractor is responsible for constructing the well using standards that are more stringent than the minimum specified in these Rules, if necessary to ensure the adequate integrity of the well and protection of the aquifer. If conditions on the well permit specify standards that exceed the minimum standards of these Rules, the well construction contractor must comply with the conditions specified on the well permit.
10.2 Well Location - When selecting a well location, consideration must be given to topography, drainage, sources of contaminants, underground utility locations, and other onsite conditions in order to promote sanitary conditions and prevent contamination of the well and aquifer. The ground surface in the vicinity of the well should be sloped to prevent the concentration of, and discourage the infiltration of, surface water at or near the wellhead.
Figure 4a Minimum Distance from a Source of Contamination Figure 4a. Schematic of the minimum distance (A) to a well from a leach field or other source of contaminants (Rule 10.2.2). Exceptions to Rule 10.2.2 may be granted through a variance request; if distance A is less than 100 ft., distance C must equal 100 feet or more.
Grout depth calculation:
Figure 4b Minimum Distance from a Vessel Containing Contaminants Figure 4b. Schematic of the minimum distance (A) to a well from a sewer line, septic tank, or other above or below ground vessel containing contaminants (Rule 10.2.2). Exceptions to Rule 10.2.2 may be granted through a variance request; if distance A is less than 50 ft., distance C must equal 50 feet or more. Grout depth calculation:
10.3 Well Casing Well casing must consist of materials that will ensure adequate protection against failure for the intended use of the well.
10.4 Construction Procedures The excavation of the borehole, selection and
FIGURE 5 WELLS WITH DRIVEN CASING THAT ARE NOT GROUTED WITH AN OPEN ANNULUS OUTSIDE THE CASING Figure 5. Schematic diagram for grout placement in wells with driven steel casing. In each aquifer type, the minimum continuous grout interval must extend a minimum of 10 feet into the annulus between the driven casing and the production casing.
FIGURE 6 TYPE 1 AQUIFER WELLS PENETRATING ONE OR MORE CONFINING UNITS Figure 6.Schematic diagram for wells that penetrate through one or more confining units and are constructed into a Type 1 (confined) aquifer.
b. If no surface casing is installed, grout must be placed in the annular space between the production casing and the borehole wall from a depth of at least thirty-nine (39) feet up to the depth required by Rule 10.5.2.1.
FIGURE 7a TYPE 2 AQUIFER WELLS COMPLETED IN TYPE 2 (UNCONFINED BEDROCK) AQUIFER NOT OVERLAIN BY TYPE 3 AQUIFER Figure 7a. Schematic diagram for wells constructed into Type 2 (unconfined bedrock) aquifers, not overlain by a Type 3 (unconsolidated) aquifer. FIGURE 7b TYPE 2 AQUIFER WELLS COMPLETED IN TYPE 2 AQUIFER (UNCONFINED BEDROCK) AQUIFERS OVERLAIN BY TYPE 3 AQUIFER Figure 7b. Schematic diagram for wells constructed into Type 2 (unconfined bedrock) aquifers, overlain by a Type 3 (unconsolidated) aquifer.
FIGURE 9 LARAMIE-FOX HILLS AQUIFER WELLS COMPLETED IN LARAMIE-FOX HILLS AQUIFERS Figure 9. Schematic diagram for wells constructed into Laramie-Fox Hills aquifers inside and outside the Denver Basin.
FIGURE 10 CONFINED SAN LUIS VALLEY AQUIFER WELLS COMPLETED IN THE CONFINED SAN LUIS VALLEY MATERIALS Figure 10. Schematic diagram for wells constructed into the Confined San Luis Valley aquifer
10.5 Grout and Grout Placement - All wells must be grouted to prevent contaminants from entering the borehole, to separate groundwater in different aquifers, and to seal off water bearing zones known or suspected to contain contaminants. To achieve these objectives, the selection, mixing, and placement of all grout is the responsibility of the person authorized to construct the well. All grout seals must be installed before completion of the well and the installation of the production equipment.
TABLE 2: GROUT MATERIALS Approved Grouts A. Neat Cement: a slurry of cement and water with no more than six (6) gallons of water per 94-pound sack (Portland cement ASTM C150 or Portland Limestone Cement Type IL, ASTM C595).
B. Cement-Bentonite: a slurry of cement (ASTM C150 or ASTM C595), bentonite and water. The amount of bentonite added must not exceed 8% bentonite per dry weight of cement. The volume of additional water used in preparing these slurries is limited to three quarters (0.75) of a gallon per 94-pound sack of cement for each 1% of bentonite added.
C. Cement, Fly-Ash, Bentonite: a slurry of cement (ASTM C150 or ASTM C595), fly ash, bentonite, and water. The amount of bentonite must not exceed the ratio to be considered high solids grout and the mixture must adhere to manufacturer’s recommendations.
D. Non-shrinking Cementitious Grouts of differing composition may be reviewed and approved by the Board.
Prior to the use of other grout materials or other combination of the above approved grout materials, a written request must be submitted to and written approval obtained from the Board.
Bulk Grouts - restricted use (see Rule 10.5.3.5)
A. Cement-Sand: a slurry of cement, sand and water. The amount of sand added must not exceed 140 pounds for each 94-pound sack of cement. Not more than six (6) gallons of water per 94-pound sack of cement may be used in the preparation of these slurries. These slurries should be used where extra strength or bulk is required.
B. Concrete: a slurry of cement, sand and gravel aggregate. The amount of aggregate added must not exceed 400 pounds for each 94-pound sack of cement. Not more than seven (7) gallons of water per 94-pound sack of cement may be used in the preparation of these slurries. These slurries should be used where extra strength and bulk is required and the annular space allows the placement of the slurry.
Bentonite - restricted use pursuant to Rule 10.4.5.2.e or 10.5.3.6. The Board may approve the following types of bentonite products.
Only bentonite products that are intended for use in water wells may be used. Mixing of bentonite grouts must strictly adhere to the manufacturer's recommendations and must achieve a slurry of not less than 20% solids by volume and a density of not less than 9.4 pounds per gallon.
A. Bentonite Slurry: a slurry of bentonite clay (powder, chips, granules or pellets) and water. Mixing of bentonite grouts must strictly adhere to the manufacturer's recommendations and must achieve a slurry of not less than 20% solids by volume and a density of not less than 9.4 pounds per gallon. The density must be measured using a “mud balance” and reported on the well construction and test report.
B. Granular Bentonite: Except as allowed in Rule 10.4.5.2.e, solid granular bentonite (pellets, granules and chips) may only be used as grout material in saturated zones and must be placed directly into the appropriate interval. Fill Materials: Fill material, such as clean native clay, clean drill cuttings, or other inert rock material may be used to fill the annular space in any interval where grout is not required by these Rules. These materials are not grouts and must not be placed where grout is required. Fill materials placed in the annulus near the land surface must be less permeable than the surrounding soil and must be adequately compacted to prevent settling.
11.1 General Rules- All permanent pump installations and cistern installations in or connected to a new or existing water well supply system must be completed by a licensed pump installation contractor or a private pump installer (see sections 37- 91-102(12.5) and 37-91-109(2), C.R.S.). Pumping equipment may be installed in wells constructed and used solely for purposes of aquifer remediation (recovery well) or temporary dewatering (dewatering well) by authorized individuals or anyone directly employed by or under the supervision of an authorized individual. It is the responsibility of the person installing the pumping equipment to ensure that a valid well permit authorizing such installation exists in accordance with the requirements of Rule 6.2.2.1 and 6.2.2.2.
11.2 Installation Standards - Pumps, cisterns, pitless units and adapters, and
11.3 Cistern Installation and Location - When selecting a cistern location,
11.4 Location Variance - A cistern installed below ground level must not be located closer than one hundred (100) feet horizontally to the nearest existing source of contaminants or fifty (50) feet horizontally from a septic tank, sewer line or other above or below ground vessels containing contaminants (but excluding properly- maintained vessels for permitted chemigation products; properly-maintained vessels mounted on vehicles; and properly-maintained vessels mounted or carried on equipment used in the construction or development of wells or installation of pumping equipment), at the time of well construction. A request for variance must be submitted and written approval from the Board must be obtained prior to the construction of a cistern that cannot meet this spacing requirement. The variance request must be prepared in accordance with Rule
11.5 Seals and Vents -
11.6 Well Vaults - New well vault installations are not permitted unless the Board approves a specific variance request. If a variance is granted by the Board, provisions must be made to prevent contaminants from entering the well and for gravity drainage of the vault through a floor drain or by an automatic sump pump.
11.7 Water Level Measurement Devices - A water level sounding tube must be
11.8 Compliance with Applicable Law All persons authorized to install pumps and
1. Well casing 2. Well head 3. Metal nipple 4. Approved weatherproof junction box. The electrical junction between the electrical conductor from the supply and the pump wire must be made in the weatherproof junction box located at the well seal.
5. Approved electrical conduit 6. Conductors approved for direct burial. Size of conductors to be determined by size of pump motor and distance. Well casing shall be bonded to the pump circuit equipment grounding conductor in junction box on well casing 7. Controller – licensed electrical contractor or licensed well contractor 8. Disconnect – installed by licensed electrical contractor or licensed well contractor 9. Foundation – all wiring through or under foundation, or under concrete floor, to be installed in approved electrical conduit Note: Electrical conduit must extend 18 inches below finished grade from well junction box
11.9 Pressure Relief Valve All water well supply systems capable of producing
11.10 Backflow Prevention Pump installations and cistern installations must have check valves, backflow prevention devices or suitable air gap cross-connection controls, as necessary to prevent damage to the pumping equipment and contamination of the aquifer.
11.11 Disinfection After installing a pump or cistern, and prior to placing the well in service, the person authorized to install pumping equipment must disinfect according to the provisions of Rule 15.
Rule 12 Well Testing Basis and Purpose: The statutory authority for this Rule is found in sections 37-91- 106(4), and 37-91- 110(1)(b) & (2), C.R.S. The purpose of this Rule is to establish minimum standards for the testing of water wells.
12.1 General - The provisions of this Rule establish minimum standards for the testing of water wells. Every well constructed for the purpose of producing groundwater must undergo:
12.2 Well Yield Estimate - The yield of a well must be tested and estimated as a stabilized production rate where the withdrawal rate does not change by more than 10% during the last hour of the test. A well yield estimate may be established by procedures such as air-lifting or bailing. Well yield estimates may be performed at rates that exceed the permitted pumping rates. If the yield is estimated via test pumping, report final pumping water level, the test duration in hours and the mean pumping rate in gallons per minute.
12.3 Responsibility for Well Yield Estimate - Well construction contractors are
12.4 Production Equipment Test - The permanent production equipment installed in wells must be tested to ensure it is functioning as designed. The test must demonstrate the production capacity of the equipment as actually installed in the well. The production equipment test must not be conducted at rates that exceed the permitted pumping rates 12.5 Responsibility for Production Equipment Test - Pump installation contractors are responsible for testing the production equipment installed in a well upon completion of their work. The pump installation contractor is also responsible for ensuring that the production from the well complies with the conditions of the well permit. Production equipment test data must be submitted to the State Engineer on the Pump Installation and Production Equipment Test Report.
12.6 Well Yield Test - A well yield test (also known as a pumping test or aquifer test) may be performed instead of, or in addition to, a well yield estimate. If a well yield test is performed, the test must be performed with equipment that is capable of determining both drawdown and pumping/production rate. Well yield tests may be performed at rates that exceed the permitted pumping rates. If a well yield test is performed, well yield test data must be submitted to the State Engineer on the Well Yield Test Report form.
Rule 13 Sampling, Measuring, and Test Pumping Basis and Purpose: The statutory authority for this Rule is found in section 37-91- 106(4), C.R.S. The purpose of this Rule is to provide minimum standards for sampling, measuring, or test pumping groundwater to ensure that shared groundwater resources are protected from contamination.
13.1 Well Owner's Knowledge Sampling, measuring, and test pumping must be
13.2 Measuring Devices All measuring and sampling devices and equipment must be
13.3 Removal of Well Seal Only a licensed well construction contractor, licensed pump installation contractor, authorized individual, or the well owner may remove a well seal. Whenever the seal is removed from a well and the equipment being used in the well is not disinfected pursuant to Rule 15.6, the well must be disinfected according to Rule 15.3. The person removing the well seal is responsible for disinfecting the well and reinstallation of the seal.
13.4 Measuring, Sampling and Test Pumping Registered professional engineers,
13.5 Lost Equipment It is the responsibility of the person doing the testing, sampling, or measuring to inform the well owner in writing of any equipment malfunction, equipment loss in the well, or difficulties encountered. Rule 14 Minimum Construction Standards for Monitoring and Observation Wells, Monitoring and Observation Holes, Dewatering Wells, and Test Holes Basis and Purpose: The statutory authority for this Rule is found in sections 37-91- 101(1); 37-91- 104(1)(c), (j) & (k); 37-91-106(4). The purpose of this Rule is to establish minimum construction standards for certain types of holes and wells that may be constructed by authorized individuals who are not specifically licensed by the Board.
14.1 General - Monitoring and observation wells and monitoring and observation holes are primarily used for observing groundwater levels and flow conditions, obtaining samples for determining groundwater quality, and for evaluating hydraulic properties of water-bearing strata. Dewatering wells are primarily used for temporary dewatering for construction only. Test holes are primarily used for conducting geotechnical or geological investigations. See section 37-91- 102(10.5) and (15.7), C.R.S., and Rule 5.2 for definitions and authorized uses for each type of structure.
14.2 Monitoring and Observation Holes - Monitoring and observation holes
14.3 Monitoring and Observation Hole/Well Construction Standards - Monitoring and observation holes or wells must be constructed to maintain existing natural protection against contamination of aquifers; prevent the entry of contaminants from the surface through the borehole; and prevent the intermingling of groundwater from different aquifers through the borehole. The construction of monitoring and observation holes or wells must meet the minimum standards presented in Rule 14.3 and must be consistent with the examples of acceptable construction shown on Figure 13, unless the monitoring and observation well will be converted to a production well in which case refer to Rule 14.2.2 and the minimum construction standards presented in Rule 10.
14.4 Installation of Pumping Equipment - Aquifer testing and/or test pumping of any monitoring and observation hole or well must not exceed a cumulative total of two hundred (200) hours unless prior written approval for additional testing is obtained from the State Engineer. The well owner or their agent are responsible for obtaining appropriate permits and complying with all rules and regulations pertaining to the discharge of all fluids produced during the testing.
14.5 Dewatering Wells – Dewatering wells may be converted to another type of well as allowed by Rule 9.6 and 14.5.1, if they are constructed in vertical boreholes, and if they comply with the requirements of Rule 14 for the particular type of well they are to be converted to.
14.6 Test Holes - Test holes are defined at section 37-91-102(15.7), C.R.S., in Rule 5.2.57, and Table 1 and are administered in accordance with the requirements of the State Engineer.
FIGURE 13.a MONITORING AND OBSERVATION HOLES/WELLS Figure 13.a. Schematic diagrams of typical monitoring and observation hole/well designs.
FIGURE 13.b (CONTINUED) MONITORING AND OBSERVATION HOLES/WELLS Figure 13.b (continued) Schematic diagram of typical monitoring and observation hole/well designs Rule 15 Minimum Disinfection Standards 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 are exempt from this disinfection requirement. Monitoring and observation holes and wells, dewatering wells, and recovery 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
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. When a new pump or well water supply system is connected to, or a replacement pump is installed in, an existing municipal or commercial water distribution system that has been disinfected in the past, the disinfection solution must be distributed up to the point of isolation between the new/replacement pump and the rest of the 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.
15.5 Flushing of Disinfectant After disinfection by the pump installer in accordance with Rule 15.3 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. Rule 16 Standards for Plugging, Sealing, and Abandoning Wells and Boreholes Basis and Purpose: The statutory authority for this Rule is found in sections 37-91- 101(1); 37-91- 104(1)(c), (j), & (k); 37-91-106(3); 37-91-109(1); and 37-91-110(2), C.R.S. The purpose of this Rule is to identify the minimum standards for the proper abandonment of water wells and other excavations constructed into the ground that, if not adequately sealed and abandoned, present a risk to the health and safety of Colorado’s shared groundwater resources.
16.1 General - The plugging, sealing, and abandonment of all wells, monitoring and observation wells, monitoring and observation holes and test holes that are no longer intended for use, and the plugging, sealing, and abandonment of collapsed or unusable boreholes, and other incomplete wells or excavations is necessary to prevent contamination of groundwater and the migration of water through the borehole. It is the ultimate responsibility of the well owner to have an existing well properly plugged, sealed, and abandoned. The well construction contractor or authorized individual is responsible for notifying the well owner in writing of these plugging requirements. Proof of this written notification must be provided to the State Engineer, if requested.
16.2 Abandonment of Wells, Boreholes, or Dry Hole in Type 1 Aquifers (confined
16.3 Abandonment of Wells or Boreholes in Type 2 (unconfined bedrock aquifers),
16.4 Abandonment of Wells or Boreholes in the Confined San Luis Valley Aquifer - Wells, boreholes or dry holes which penetrate into the Confined San Luis Valley Aquifer must be plugged and sealed by placing approved grout in a manner that will fill the well casing and/or borehole throughout the entire interval beginning 10 feet below the top of the Confined San Luis Valley aquifer and extending up to the top of the well. The base of the grouted interval must extend deeper below the top of the Confined San Luis Valley aquifer if necessary to withstand the maximum potential hydrostatic pressure differential between the aquifers. If well construction records do not show that the casing opposite the Unconfined San Luis Valley Aquifer was appropriately grouted to isolate the Confined San Luis Valley aquifer when originally constructed, the casing must be either completely removed from the hole, or perforated or ripped beginning at least 10 feet below the top of the Confined San Luis Valley aquifer up to the ground surface or up to the originally grouted interval documented on the construction records, prior to grouting. The well casing or borehole, except for the grout plug intervals, must be completely filled with clean native clays, approved grout, or high-solid bentonite grout. A watertight cover must be permanently welded or attached to the top of the casing.
16.5 Abandonment of Other Structures:
16.6 A well for which a replacement well has been permitted and constructed must be plugged, sealed, and abandoned within sixty (60) days after the completion of the replacement well, unless otherwise stated on the original well permit or if the original well is re-permitted by the State Engineer.
Rule 17 Reporting Requirements Basis and Purpose: The statutory authority for this Rule is found in section 37-91- 110(2), C.R.S. The purpose of this Rule is to require the submittal of reports concerning the construction of certain excavations as necessary for documenting the location of such excavations, gathering information about hydrogeological conditions of Colorado, and for ensuring compliance with permits and water rights requirements.
17.1 Work Reports - Reports must be submitted to the State Engineer on prescribed forms that describe where, when, and how all wells and certain holes have been constructed, the pumping equipment has been installed in water wells, a cistern connected to a water well supply system has been installed and a description of how boreholes, wells, dry holes, and incomplete wells are plugged, sealed, and abandoned.
17.2 Format of Reports Work reports must be submitted on forms provided by the
17.3 Timely Submittal Complete work reports must be submitted to the State Engineer within sixty (60) days after completion of the well construction, pump installation, or other work required to be reported or within seven (7) days after the expiration of the permit or other authorization, whichever is sooner.
17.4 Certification Work reports must be signed and certified as to accuracy and
17.5 Unsanitary or Non-Compliant Conditions A licensed contractor who repairs an existing well or pump must report to the Board of Examiners any unsanitary or noncompliant conditions that he or she is unable to correct.
17.6 Copy of Report to Owner Well construction and pump installation contractors must provide a copy of all work reports to the well owner in accordance with Rule 17.3.
17.7 Water Quality Reports If water quality analyses for newly constructed wells are obtained by or are available to the well or pump installation contractor, a copy of that analysis must be provided to the State Engineer upon request by the State Engineer. The well location, date of analysis, and the permit number or other identifying authorization must be shown on the report.
17.8. Data Confidentiality In the event that the information provided contains trade secrets, privileged information, or confidential commercial, financial, geological, or geophysical data, and upon written request by the well owner, the information will be kept confidential pursuant to section 24- 72-204(3)(a)(IV), C.R.S. Rule 18 Variances Basis and Purpose: The statutory authority for this rule is found in sections 37-91- 101(1); 37-91-104(1)(c), (j), (k) & (2); 37-91-106(3); 37-91-109(1); and 37-91-110(2), C.R.S. The purpose of this Rule is to allow the Board to approve alternate methods of construction or abandonment of an excavation over which it has jurisdiction, in the event that the individual requesting such alternative to the minimum standards can adequately demonstrate that the variance will protect the health and safety of the public and prevent contamination to Colorado’s groundwater.
18.1 General When the strict application of any provision of these Rules presents practical difficulties or unusual hardship, the Board may grant a variance for a specific instance or method of construction and may impose any conditions deemed necessary to protect the groundwater and aquifers from contamination.
18.2 Written Request Required - Any request for a variance must be submitted to the Board of Examiners in writing and must be signed by the well owner or his or her agent. Such request must specify:
18.3 Written Decision - The Board will respond in writing to each variance request, and must include reasons for its decision. The Board may impose terms and conditions to protect public health and safety or prevent aquifer contamination.
18.4 Appeal - The Board’s written decision on the request for variance is final agency action. The individual who requested the variance may request the Board’s reconsideration of the Board’s written decision at the next regularly scheduled Board meeting following issuance of the written decision. Any appeal of the Board’s written decision must be pursuant to the State Administrative Procedures Act, Article 4 of title 24, C.R.S.
Rule 19 Emergencies Basis and Purpose: The statutory authority for this rule is found in sections 37-91- 101(1); 37-91-102; 37- 91-104(1)(c), (j), & (k); 37-91-106(3); 37-91-109(1); and 37-91- 110(2), C.R.S. The purpose of this Rule is to ensure that, even in the case of an emergency, excavations under the Board’s jurisdiction must still be constructed upon approval of the State Engineer.
In accordance with the procedures of the State Engineer, in the event of an emergency, construction of replacement wells, monitoring and observation holes, temporary dewatering wells, or recovery wells may begin only after approval has been granted by the State Engineer. The well construction contractor or authorized individual that has received approval from the State Engineer must comply with all conditions of such approval.
Rule 20 Petitions for Declaratory Orders Basis and Purpose: The statutory authority for this rule is found in section 24-4-105(11). The purpose of this Rule is to comply with the requirement of section 24-4-105(11) and provide the Board’s procedures for entertaining, in its discretion, any petitions for declaratory orders to terminate controversies or to remove uncertainties as to the applicability to the petitioners of any statutory provision or of any rule or order of the agency.
20.1 General – pursuant to section 24-4-105(11), C.R.S., this rule provides
20.2 Petition for Statement of Position – Any person may petition the Staff for a statement of position concerning the applicability to the petitioner of any provision of these Construction Rules, or any regulation of the Board. The Staff shall respond with a written statement of position within 30 days of receiving a proper petition.
20.3 Petition for Declaratory Order – Any person who has properly petitioned the Staff for a statement of position, and who is dissatisfied with the statement of position, or who has not received a response within 30 days of the petition, may petition the Board for a declaratory order pursuant to section 24-4-105(11), C.R.S. Such petition must be submitted to the Chief Well Inspector or a member of his or her staff within 30 days of the date of the Staff’s written statement of position. A petition for declaratory order must include the following:
20.4 Board’s Exercise of its Discretion to Entertain a Petition – The Board will determine, in its discretion and with no prior notice to the petitioner, whether to entertain any petition. If the Board decides it will not entertain a petition, it shall promptly notify the petitioner in writing of its decision and the reasons for that decision. Any of the following grounds are sufficient reason to refuse to entertain a petition:
20.5 If Board Entertains a Petition – If the Board determines that it will entertain the petition for declaratory order, it must notify the petitioner within 30 days of making such determination, and the following procedures will apply:
20.6 Records of Petitions and Declaratory Orders – Files of all petitions, requests, statements of position, and declaratory order will be maintained by the Board. Such files will be available for public inspection, except for any material required by law to be kept confidential. The Board will post a copy of all statements of position and declaratory orders constituting Final Agency Action on the Board’s web site.
Rule 21 Severability If any portion of these Rules is found to be invalid, the remaining portion of the Rules shall remain in force and unaffected.
Rule 22 Revisions The Board may revise these Rules in accordance with section 24-4-103, C.R.S. Rule 23 Effective Date These revised Rules shall become effective January 1, 2026. Rule 24 Statement of Basis and Purpose The Statement of Basis and Purpose for these Rules is incorporated herein by this reference.
Editor's Notes History Entire rule eff. 01/01/2005.
Entire rule eff. 09/01/2016.
Rule 6.3 eff. 07/01/2018.
Entire rule eff. 01/01/2026 STATEMENT OF BASIS AND PURPOSE RULES AND REGULATIONS FOR WATER WELL CONSTRUCTION, PUMP INSTALLATION, CISTERN INSTALLATION, AND MONITORING AND OBSERVATION HOLE/WELL CONSTRUCTION 2 CCR 402-2 ______________________________________________________________________ RULE 1 TITLE These Rules have been referenced by different titles over the years. Generally, the Rules apply to those structures over which the Board has jurisdiction, which are referenced in the title of the Rules.
RULE 2 AUTHORITY The authority of the Board of Examiners of Water Well Construction and Pump Installation Contractors (“Board”) to promulgate these Rules arises from the general assembly’s creation of the Board to ensure protection of the groundwater resources of the State of Colorado and public health and safety. See § 37-91-101, C.R.S. This Rule cites the specific statutory authority of the Board to promulgate minimum standards for certain activities and for the construction of certain types of structures, and to revise such regulations in accordance with the Board’s statutory authority and the State Administrative Procedure Act of article 4 of title 24, C.R.S. RULE 3 SCOPE OF RULES The statutory authority for this Rule is found in sections 37-91-101(1); 37-91-102; 37-91- 104(1)(c), (j), & (k); 37-91-106(3) & (4); and 37-91-110(2), C.R.S. The purpose of this Rule is to identify the activities and individuals to which these Rules apply. Rule 3.4 identifies all materials incorporated by reference in these Rules as authorized by section 24-4-103(12.5), C.R.S, and explains how copies of such materials may be obtained.
Rule 3.5 clarifies the jurisdiction of these Rules are limited to the State of Colorado and not necessarily the Southern Ute Indian Reservation.
RULE 4 PURPOSE OF RULES The statutory authority for this rule is found in sections 37-91-104(1)(c), (j), & (k); 37-91- 106(3) & (4); and 37-91-110(2), C.R.S. The purpose of this Rule is to identify the broad purposes for the Rules as a whole. These Rules specify minimum standards for construction materials and methods. As required by Rule 10.1.1, when mandated by geologic, hydrogeologic, or well construction conditions, a licensed contractor must apply or use higher standards, higher grade construction materials, and more thorough site-specific construction and installation methods to comply with the purpose of these Rules.
Rule 4.6 was added to the Rules under the authority of section 37-91-106(4). RULE 5 DEFINITIONS The statutory authority for this Rule is found in sections 37-91-101(1); 37-91-102; 37-91- 104(1)(c), (j), & (k); 37-91-106(3) & (4); and 37-91-110(2), C.R.S. The purpose of this Rule is to identify the terms used throughout the Rules. Section 37-91-102, C.R.S. defines nineteen terms used in these Rules and provides verbatim the statutory language of all terms defined by the General Assembly. This Rule also defines additional terms to ensure that their meanings and usage are clearly understood.
The definitions of the different aquifer “types” in Rule 5.2 include two particular aquifers (Laramie-Fox Hills and Confined San Luis Valley) and three other specific administratively-defined aquifers (Unconfined San Luis Valley, High Plains, and Southern High Plains). In order to properly regulate construction of wells drilled into different geological formations in Colorado, it is necessary to classify and define distinct aquifer types according to their hydrogeological characteristics. Although Colorado has distinct, named aquifers, these aquifers may be found with localized or regional geologic features. For example, certain Denver basin aquifers may be a Type 1 or Type 2 aquifer, depending on the specific subsurface position of the aquifer. Therefore, these Rules designate five types of aquifers, and specific construction standards for each type, in order to ensure that a well constructed in a particular location will be constructed to protect the groundwater resources of the State of Colorado based on the characteristics of the aquifer at that location.
Rule 5.2.1 describes the geographic area which includes the Denver Basin Aquifers (referenced in Figure 1)
Rule 5.2.2 clarifies annular space also includes the space between the inner and outer casing strings when those casings overlap.
Rule 5.2.3: Aquifer Type numbers were changed from Roman to Arabic for clarity. The Rules provide different construction requirements for three general classifications of aquifers (Types 1-3) and two particular aquifers (Laramie-Fox Hills and Confined San Luis Valley). Three other aquifers (Unconfined San Luis Valley, High Plains and Southern High Plains) are defined within the Rules for clarity, but the construction requirements for Unconfined San Luis Valley, High Plains and Southern High Plains follow the Rules for other defined aquifer types or are prescribed by permit condition. Rule 5.2.3.1 defines those hydrogeologic units described in State Engineer rule, well permit, decree, or an annually-updated list of aquifers approved by the Board. Rule 5.2.3.2: Type 1 aquifer refers to an aquifer overlain by a confining geologic layer, regardless of whether the aquifer is confined based on hydrostatic pressure. In some cases, Type 1 aquifers may become ‘unconfined’ based on changing water levels, thereby affecting the hydrostatic pressure of the aquifer. Rule 5.2.3.3: Type 2 aquifers, while not overlain by a confining layer, may or may not underlie a Type 3 (unconsolidated aquifer).
Rule 5.2.3.4: Type 3 wells are those drilled into unconsolidated materials and identifies that impermeable layers that do not act as hydraulic boundaries may exist within these deposits, and not as a confining unit as defined in these Rules. Rule 5.2.3.5 defines the Laramie-Fox Hills aquifer as a separate aquifer type, because of unique issues of poor water quality found in this aquifer and adjacent geologic units. There is an increasing reliance by homeowners and communities on this aquifer in areas without other viable water supplies. These Rules identify specific minimum construction standards for wells drilled into the Laramie-Fox Hills aquifer. The Laramie- Fox Hills aquifer is also administratively defined in the Denver Basin Rules, 2 CCR 402- 6 (1985) See Rule 10.4.8 Rule 5.2.3.6 is the administratively-defined Unconfined San Luis Valley aquifer above the Blue Clay (confining layer) and identified as Layer 1 in the RGDSS Groundwater Model. It is a Type 3 aquifer for the purposes of well construction and abandonment (previous BOE Policy 2003-3).
Rule 5.2.3.7 is the administratively-defined Confined San Luis Valley aquifer, as defined in the Rules Governing New Withdrawals of Ground Water in Water Division 3 Affecting the Rate or Direction of Movement of Water in the Confined Aquifer System (Confined Aquifer New Use Rules for Division 3), and is identified as Layers 2, 3, 4, and 5 in the RGDSS Groundwater Model. See Rule 10.4.9 Rule 5.2.3.8 describes the administratively-defined Northern High Plains aquifer, as described in Rule 5.2.2 of the Rules and Regulations for the Management and Control of Designated Ground Water (Designated Basin Rules, 2 CCR 410-1). It further clarifies the distinction that within the Northern High Plains Designated Basin the alluvium is also included with the High Plains aquifer and they are therefore considered a single hydrogeologic unit, considered a Type 2 aquifer (previous BOE Policy 2021-2). Rule 5.2.3.9 describes the administratively-defined Southern High Plains aquifer, as described in Rule 5.2.3 of the Rules and Regulations for the Management and Control of Designated Ground Water (Designated Basin Rules, 2 CCR 410-1), and clarifies it is a Type 2 aquifer (previous BOE Policy 2017-3).
Rule 5.2.4, the definition of “Authorized individual,” was modified in order to allow for an individual not registered as a professional geologist or professional engineer to request designation by the Board as an Authorized Individual based on unique qualifications and experience, and on a case-by-case basis.
Rule 5.2.8 added three sub-definitions of casing to describe the difference between temporary surface casing, surface casing, and production casing, as typically described in well construction. Temporary surface casing (Rule 5.2.8.1) is used on a short-term, non-permanent basis to hold back shallow unstable materials to allow the placement of permanent casing and construction of the well. Surface casing (Rule 5.2.8.2) is nonperforated, steel casing permanently installed in the well. Production casing (Rule 5.2.8.3) is installed through the production zone and may either extend up into surface casing or be driven as the only casing string.
In Rule 5.2.10, the definition of “Cistern” was modified in order to distinguish cisterns used for domestic water supply from an “artificial reservoir” such as livestock storage tanks or other device not intended for public or domestic use. Rule 5.2.13: this definition was changed from confining layer to confining unit to better describe the performance of the overall zone acting to impede groundwater flow. Confining layers are administratively defined for the Denver Basin and for Designated Ground Water Basins. Confining layers between aquifers outside of these administratively-defined areas are those as mapped in geologic literature. The definition of Contracting was removed from these Rules because it was not used and better belongs in the Administration Rules (BOE Rules, 2 CCR 402-14). Rule 5.2.28: a definition for “hydraulic fracturing of a water well” was added to the Rules in 2016 because of the increasing use of hydraulic fracturing techniques to stimulate water production for certain wells. Such techniques, if performed in certain hydrogeologic settings, may present a risk to the integrity of confining layers that bound aquifers. See Rule 10.1.6.
In Rule 5.2.33, monitoring and observation holes are distinguished from test holes as those boreholes constructed for the purpose of observing, measuring, or sampling groundwater. Because monitoring and observation holes will be used for monitoring and observing groundwater (and thus will be open holes, presenting a risk of groundwater contamination if not constructed and abandoned properly), they must be registered with the State Engineer and constructed only by an authorized individual. This includes environmental boreholes constructed for repeated observations of groundwater. These are distinguished from “test holes” as defined in Rule 5.2.57. Monitoring and observation holes include holes constructed as air sparge wells that encounter the water table and piezometers.
Monitoring and observation holes/wells include fully-grouted vibrating wire piezometers, but such piezometers are exempted from the requirements to provide notice and the construction standards of Rule 14 if they do not penetrate a confining layer because of the minimal risk for the migration of groundwater given the borehole and instrumentation is fully-grouted at the time of the completion of construction and is not an “open hole” piezometer. Inclinometers and soil vapor extraction wells, and air sparge structures that do not intersection the groundwater and are constructed with an intent/purpose other than to observe, measure, or sample groundwater and are therefore considered test holes.
5.2.54: The definition of “static water level” is meant to limit the potential for reporting a water level on the construction report that has not yet reached equilibrium. The static water level is an important data point for pump installers and scientists researching aquifer conditions and this definition will hopefully result in better reporting. Rule 5.2.57: The definition of “test hole” was expanded to distinguish such holes, used exclusively for geotechnical, geophysical, or geologic investigation, or soil/rock sampling, from monitoring and observation holes used for observations of groundwater. Holes drilled with the intent of investigating or measuring groundwater are not test holes. Test holes include inclinometers and soil vapor extraction holes. Rules 5.2.64.3 through 5.2.64.6 were included to distinguish certain specific structures that are not “wells” because they are under the jurisdiction of other entities and agencies (carbon dioxide injection wells and deep geothermal operations) or are part of other construction (recharge and infiltration basins). Though previously included in the 1988 through 1996 versions of the well construction Rules cathodic protection wells are not under the jurisdiction of the Board of Examiners.
Rules 5.2.69 and 5.2.70 define and distinguish between a “well yield estimate” and a “well yield test,” which are two types of procedures designed to estimate or test the stabilized production rate of a well. See Rules 10.8 and 12. RULE 6 GENERAL RULES The statutory authority for this Rule is found in sections 37-91-101(1); 37-91-102; 37-91- 104(1)(c), (j), & (k); 37-91-106(3); and 37-91-110(2), C.R.S. Rule 6 implements general statutory provisions that apply to well construction and the installation of pumping equipment. Rule 6 also advises contractors of certain State Engineer’s notice and permitting requirements.
Rule 6.1 explains that the licensing process and those functions associated with obtaining and maintaining a license, previously explained in the Construction Rules, are now found in the BOE Rules, 2 CCR 402-14.
Rule 6.2 clarifies well permit requirements by identifying the types of work for which the State Engineer requires the issuance of a new well permit and specifying that a contractor must determine that a valid well permit exists prior to and during all phases of well construction and installation of pumping equipment. For enforcement purposes, this Rule also requires a copy of the well permit to be available at the well site at all times such work is being performed.
Rule 6.2.2.1 requires all contractors or their direct employees to possess, make available, and post at the well site a copy of the well permit for the well on which work is being performed. This rule also requires compliance with all conditions of approval of well permits, including advance notification of well construction or pump installation. If the applicable well permit includes such a condition, details for compliance with the advance notification requirement will be included in the well permit. Rule 6.2.2.2 allows a contractor who is unable to verify that a well permit exists or is required for the work being requested on a well or the pumping equipment, to notify the State Engineer of certain work performed and to provide information about repairs to the well, or to pumping equipment involving the replacement of a pump or change in depth, on forms prescribed by the State Engineer. While this Rule recognizes the practical difficulties that a contractor may encounter when performing emergency repairs on an existing well, it does not relieve a contractor of the responsibility for complying with statutory requirements and Rule 6.2.2.
Rule 6.2.3 addresses situations where the State Engineer has issued a well permit authorizing construction of a well at any point within a specified tract of land and provides that the well construction contractor must identify within 60 days of completion the location of the constructed well pursuant to the conditions of the well permit. Rule 6.3 sets forth the notice requirements of the State Engineer for the construction of dewatering wells and monitoring and observation holes, and for the construction of test holes that will penetrate through a confining layer between aquifers. Rule 6.3.3 clarify who is responsible for providing such notice, and Rule 6.3.4 establishes time periods for completing construction of structures for which notice was given under this Rule. Table 1 lists the general types of wells and holes, identifies who may construct such wells and holes, identifies when a permit or notice is required prior to construction, and indicates what types of excavations can be constructed and plugged and sealed by a person with a special license. This table was revised to clarify license, permit, and notice requirements.
Rule 6.4 sets forth the conditions under which the State Engineer has deemed that approval of the construction of dewatering wells or monitoring and observation holes with less than the required notice may be obtained.
Rule 6.5 requires all licensed contractors, private drillers, private pump installers and authorized individuals, upon request by the State Engineer or his staff, to identify any well, test hole or monitoring and observation hole/well that they intend to construct or work on within a specified five-day period. This Rule was modified to change the time period from three days to five days in order to allow the Chief Well Inspector to request advance notice of anticipated activities over a longer time period. Such notifications will assist the State Engineer in enforcement and monitoring efforts. Rule 6.6 establishes that the construction standards of these Rules are minimum standards that contractors must comply with for all hole/well construction, pump installation, and cistern installation. If more stringent or comprehensive standards that apply to the work being performed are set forth in federal, state, county, local or municipal laws, regulations or codes, the contractor must comply with such standards. It is the contractor’s responsibility to know if such more stringent or comprehensive standards exist and to comply with such standards. Under no circumstances will the minimum standards of the Rules serve to insulate a contractor or other individual from complying with the valid and existing requirements of a local, state, or federal jurisdiction.
Rule 6.7 prohibits the use of products and materials which may be health hazards and is patterned after and complies with similar standards established for drinking water regulations. Pipe thread compounds are used on drilling equipment and may commonly be applied generously to ensure an excess amount remains on tools after tightening. Therefore, where such compounds contain hazardous or toxic substances, excess amounts could be left in the well after drilling, which causes a serious risk to public health. The purpose of this rule is to prevent use of materials or products that may pose a risk to public health and safety and to the groundwater resources of Colorado. The concentration of lead allowed in products such as solder and fluxes and requirements for “lead free” materials in Rule was updated in 2025 to conform to the requirements of 40 CFR 143.12(a) of the Safe Drinking Water Act.
Rule 6.8 addresses the disposal of fluids generated during well construction, development or disinfection. The improper disposal of such fluids into the surface or ground waters of the state may contaminate those waters and is therefore prohibited unless authorized by the appropriate agency. The purpose of this Rule is to alert well construction contractors and pump installation contractors so that they can avoid these potential hazards and obtain proper authorization if necessary. The discharge of water to the ground surface as addressed in Policy 2020-3 was left as a policy so that the Board and the Water Quality Control Division (WQCD) of the Colorado Department of Public Health and Environment (CDPHE) may revisit concurrence on the proper methods to handle such discharges.
Rule 6.9. The water used in drilling fluids, developing and cleaning, or hydraulically fracturing or stimulating a well can potentially contaminate both the well and the aquifer. To minimize such hazards, Rule 6.9 requires contractors to obtain such water from an approved public supply and sets forth disinfection requirements for water obtained from a surface or ground water source when an approved public supply is not available. Contractors and authorized individuals must comply with local regulations, and the prior appropriation system, when obtaining water from flowing streams. Information on requirements for using water from rivers and streams can be obtained from the water commissioner or Office of the Division Engineer in the water district at issue. Rule 6.10 Drilling fluid additives should be specifically approved by the Board. A list will be maintained on the Board’s website. The approval process for new additives will require that information about an additive be brought before the board for review at their regularly scheduled meeting.
RULE 7 LICENSING Previous versions of these Rules included licensing and bonding requirements in Rule 7 and Rule 8. Those Rules are now found in the Rules and Regulations for Administration of Licensing, Financial Responsibility, Continuing Education, and Remedial Action (BOE Rules), 2 CCR 402-14. To avoid any confusion, and to maintain a consistent Rule numbering system for these Construction Rules, Rule 7 and Rule 8 have been left blank.
RULE 8 FINANCIAL RESPONSIBILITY Previous versions of these Rules included licensing and bonding requirements in Rule 7 and Rule 8. Those Rules are now found in the Rules and Regulations for Administration of Licensing, Financial Responsibility, Continuing Education, and Remedial Action (BOE Rules), 2 CCR 402-14. To avoid any confusion, and to maintain a consistent Rule numbering system for these Construction Rules, Rule 7 and Rule 8 have been left blank.
RULE 9 WELLS AND HOLES WHICH MAY BE CONSTRUCTED BY PERSONS OTHER THAN LICENSED WELL CONSTRUCTION CONTRACTORS The statutory authority for this rule is found in sections 37-91-101(1); 37-91-104(1)(c), (j), & (k); 37-91-106(3); and 37-91-110(2), C.R.S. The Purpose of this Rule is to identify the basic types of activities that may be completed by persons that are not licensed for water well construction or pump installation, as well as notification and reporting requirements. Additionally, this Rule identifies certain structures that do not have minimum construction standards.
Thousands of test holes are drilled each year in Colorado to investigate the subsurface geology and to obtain data needed to design buildings, bridges, highways, dams and other structures. The majority of these holes are constructed by soil engineering firms, consultant engineers or geologists with their own equipment, or by specialized firms providing equipment and operators for hire. Generally, these individuals and/or firms do not have experience with water well construction, and thus are unable to qualify to take the examination for a well construction contractor's license. Large numbers of monitoring and observation holes/wells are constructed every year to monitor fluctuations of the water table and to collect aquifer data or water quality samples. Many of these are located around or within known or suspected locations of contaminated groundwater. Some are required to be located at solid or hazardous waste disposal sites, and wells are now required to monitor for potential contamination from underground storage tanks. Many of these are being constructed by other than licensed contractors, because quite often, licensed water well contractors do not have the specialized equipment necessary to construct test holes and/or monitoring and observation holes/wells.
Rule 9.1 identifies the individual responsibility for compliance with the provisions of the Rules for those holes or wells that can be constructed by persons not licensed for water well construction. Rule 9.1 was reworded to clarify the meaning of the rule. Three specific type of individuals are authorized to construct the structures identified in Rule 9, and those individuals are identified in Rule 9.1.
After consideration of the many different types of excavations which are constructed, the Board determined that the excavations listed in Rule 9.2 could be constructed and otherwise worked on by persons other than a licensed contractor, provided that the excavation does not penetrate through a confining layer between two adjacent aquifers. Where such excavations may penetrate through a confining layer between aquifers, adequate experience, equipment, knowledge, and training is necessary to ensure protection to the aquifers and prevent contamination or interconnection. Therefore, any excavation that penetrates a confining layer must be constructed by an individual licensed for water well construction, unless a person with requisite knowledge, skill, and training requests and receives a special license issued by the Board under the procedures identified in the BOE Rules, 2 CCR 402-14. The Board recognizes that certain individuals possess the ability to properly construct and abandon wells so as to prevent cross-contamination, who are not licensed contractors or do not have the water well construction experience needed to take the examination for a license. The Board’s intention is to issue a special license to persons meeting the requirements of Section 37-91-105, C.R.S. and the requirements of the BOE Rules, 2 CCR 402-14, who can demonstrate that they know how to properly construct monitoring or observation holes/wells or test holes through a confining layer between adjacent aquifers. This provision should allow geological, geotechnical, and engineering consulting firms to continue their current normal business after obtaining the special license.
Rule 9.2. identifies common types of excavations that may be constructed by an authorized individual. A “horizontal drain” is a type of dewatering system, so it was eliminated in this list to avoid redundancy. Should there be any question as to whether a person is qualified or allowed to construct a particular type of excavation, it is the responsibility of that person to contact the Board of Examiners for a determination as to whether the person is authorized to construct the structure. Rules 9.2.1 and 9.2.2 set forth the State Engineer’s required notice prior to construction of dewatering wells and monitoring holes and the requirements for filing construction reports for such structures.
Rule 9.3 identifies the specific construction Rules that apply to the construction and the plugging, sealing and abandoning of excavations included in Rule 9. Rules 9.3.2 and 9.3.3 were added to the Rules. Rule 9.3.2 concerns dewatering wells and dewatering systems that do not penetrate a confining layer and are not constructed in a vertical borehole in order to address confusion concerning the relevant construction standards applicable to such excavations. Dewatering wells and systems are commonly constructed as part of home or commercial construction to eliminate or minimize the presence of shallow groundwater for proper construction, on a temporary or permanent basis. Individuals constructing such excavations must ensure that such excavations prevent contamination of nearby surface water or groundwater, and must comply with any relevant local, state, or federal requirements. Abandonment of such excavations, however, must be performed in accordance with Rule 16.5.1 in order to ensure that such excavations will prevent the rapid infiltration to groundwater of any surface contamination in the future.
Rule 9.3.3 concerns pond or lake “wells,” which will intercept and use groundwater for beneficial use and therefore require well permits from the State Engineer. However, such excavations, to the extent that they do not penetrate a confining layer between aquifers, present minimal risk to groundwater. Therefore, this rule provides no minimum universal construction standards for ponds or lakes permitted as wells by the State Engineer. However, construction of such excavations must ensure that contaminants are prevented from entering the pond or lake.
Rule 9.4 details the requirements for plugging accidental penetrations through a confining layer, in order to prevent the interconnection or cross-contamination of water from different aquifers.
Rule 9.6 prohibits the conversion to a production water well of any excavation constructed pursuant to a notice of intent as provided in Rules 6.3 and in accord with the requirements of Rule 9. This provision stems from the Board’s concern that unlicensed contractors have neither the knowledge, skill, or equipment needed to properly construct excavations that will be eventually converted into water supply wells. The adoption of Rule 9.6 also ensures consistency with Rule 6.1 and Section 37-90- 138(3), C.R.S., (which require a permit be obtained from the State Engineer prior to constructing a new well or performing work on an existing well under the authority of the State Engineer) while allowing for the construction of test holes and monitoring and observation holes without engaging the permit process prior to their construction. RULE 10 MINIMUM CONSTRUCTION STANDARDS FOR WATER WELLS The statutory authority for this rule is found in sections 37-91-101(1); 37-91-102; 37-91- 104(1)(c), (j), & (k); 37-91-106(3); 37-91-109(1); and 37-91-110(2), C.R.S. The purpose of this Rule is to identify the minimum construction standards for water wells or other excavations constructed in different types of aquifers in Colorado, in order to ensure that such construction prevents harm to the public health, will not impair water quality or cause contamination of shared groundwater resources, and will ensure the safety of groundwater resources for Colorado’s existing and future populations. In general, Rule 10 establishes minimum construction standards for production water wells, injection wells and all other wells, in order to provide for the reasonable life of a well, to produce an adequate supply of groundwater when such water is available, to prevent the intermingling of water between aquifers, and to prevent contamination of the aquifer and the groundwater. These minimum standards do not relieve a contractor from employing more stringent practices or standards in response to specific geologic, hydrologic or construction situations. These construction standards apply to all wells as that term is defined in Section 37-91-102(16), C.R.S., except for those wells that are described in Rule 9.
Rule 10.1 summarizes common industry practices and objectives necessary to prevent injury to humans and livestock and to protect a well from the entry of contaminants. Rule 10.1.1, requires a licensed contractor to apply or use higher standards, higher grade of materials and/or more thorough and protective, site-specific construction and installation methods to comply with the purpose of these Rules when mandated by geologic, hydrologic or particular construction conditions. Rules 10.1.2 through 10.1.4 establish the responsibility of the contractor to be informed of potential hazards prior to well construction and set forth requirements that are intended to safeguard humans, animals, and groundwater during the well construction process. Rule 10.1.2 was amended to ensure the contractor is familiar with the geology of all aquifers AND confining layers he/she will encounter and require the contractor to advise well owners of the potential for encountering known poor water quality or contamination.
Rule 10.1.3 clarifies what constitutes a secure cover, seal or cap. Practices of covering boreholes or casing with buckets while not onsite, or the top of casing with tape are not secure.
Rule 10.1.5 requires that nested wells be grouted to prevent intermingling of water from different aquifers in the borehole and thereby prevent the cross-contamination of groundwater from different aquifers.
A rule that previously concerned “gravel pit wells,” was removed from the Rules. A related rule, concerning construction standards for pond or lakes permitted as wells, was added at Rule 9.3.3. The Board does not have jurisdiction over excavations made for the purpose of obtaining or prospecting for minerals, including sand and gravel, even where such excavations are later permitted by the State Engineer as “wells”. See 37- 91-102(16)(b)(I).
Rule 10.1.6 addresses hydraulic fracturing of water wells. This rule ensures the fracturing and ensures a more complete well record process does not damage the confining layer between two aquifers.
Rule 10.2 addresses well locations. In selecting well sites, it is important to consider topography, surface drainage, floodplain, and proximity to leach fields, feedlots and corrals, surface water courses, septic tanks, and sewer lines as potential sources for contamination. It is necessary for the contractor to comply with local (city, county, etc.) spacing requirements for distances from potential sources of contamination that may exceed the distances stated in this Rule. Compliance with the Board’s Rules in no way insulates or exempts a contractor from complying with more strict requirements of local jurisdictions. In choosing a well site, consideration must also be given to the accessibility of the location for the construction equipment and for any future repairs to and plugging of the well. The current rules are promulgated to maximize the distance between the well and contaminant sources, but within the practical limits of lot size. In the event a well must be constructed less than 100 feet horizontally from a potential source of contaminants, or less than 50 feet from a septic tank, sewer line, or other vessel containing contaminants, this Rule establishes a procedure for a greater minimum grouting depth near the surface to provide additional protection from contamination. Figures 4a and 4b are included in Rule 10.2 to illustrate the construction requirements for wells less than 100 feet from a contaminant source or 50 feet from a vessel. The Rule explains procedure and requirements for obtaining a variance from the minimum spacing and/or grouting requirements when those standards present practical difficulties or unusual hardship. The minimum grouting depth requirements of Rule 10.2.3 are based on ensuring protection to the groundwater from sources of contamination nearby for replacement wells.
Rule 10.3 describes well casing criteria. The diameter, wall thickness, and materials of the well casing affect the life of the well and the size of the pump equipment that may be installed. In selecting casing materials, a contractor must consider the type of formations penetrated by the borehole, depth of well, corrosive conditions known or anticipated, and purpose for which the well is constructed. Only steel casing may be used where well casing will be exposed at the surface and/or where substantial weight will be attached to the well casing.
Rule 10.3.1 describes the condition of well casing to be used. Oil field pipe, including gas-line pipe, may be contaminated with residual hydrocarbons and is not suitable for water wells, its use is prohibited. This Rule eliminated the use of used surface casing. Only new casing should be installed in wells because used casing may be corroded or contaminated, even though it may not immediately appear so. Rule 10.3.2 describes how contractors may use temporary surface casing that is other than steel but that the temporary casing must be removed from the borehole prior to the completion of grouting to allow adequate grout placement between the borehole wall and the outside of the permanent casing.
Rule 10.3.3 addresses minimum well casing diameter requirements. To be more definitive in describing casing diameters, these Rules refer to inside diameter (ID) instead of outside diameters (OD). Minimum steel well casing diameter was increased to 4.5 inches ID to reduce the number of pumps becoming stuck in a well due to biofouling or corrosion. Steel casing with an ID of at least 4.5 inches is available for use by contractors, according to contractors and suppliers. Pumps can commonly become stuck in older steel-cased wells that have an ID of less than 4.5 inches, due to corrosion or other issues. Stuck pumps prevent proper abandonment of wells and may lead to a risk of groundwater contamination. Corrosion is not a concern with PVC casing, and wells constructed using 4-inch ID PVC casing have been shown to be acceptable for wells constructed in certain locations. PVC casing may not be exposed above the ground surface, as required in Rule 10.3.1.
Rule 10.3.4 presents well casing thickness requirements. Adequate casing wall thickness is required to prevent collapse due to hydrostatic pressures. This rule was adjusted in 2025 to allow other schedules (SCH 80, 120) and types (SDR) of PVC casing conforming with ASTM F480 to be used in well construction provided that the strength of the casing is not less than an equivalent diameter Sch 40 casing. This will allow the continued use of Sch 40 PVC casing commonly used by contractor but also allow the selection of higher strength PVC casing to better ensure protection to groundwater resources and provide a longer-lasting well for Colorado well users. Rule 10.3.5 was added to the Rules to prohibit certain casing perforation methods or designs that leave debris on the inside of the well casing, such as “torch-cut slots.” Debris or protrusions in the inside of the well casing has caused difficulties with removing pumps for service or replacement. Stuck pumps, which may lead to well abandonment procedures that include leaving the pump in place, present a danger to the quality of groundwater resources. Oxygen-acetylene torches are prohibited on well casings less than 5 inches in diameter because they often result in debris left inside the casing. Plasma torches are allowed in all cases because the cuts do not leave debris inside the well casing.
Rule 10.4 outlines required construction procedures for wells. The size of the borehole and casing, and the amount, type and placement method of the grout are construction components important in achieving an effective seal to prevent the entry and/or migration of contaminants into and through the borehole and to confine groundwater production to the specified aquifer or authorized producing interval. This Rule requires that certain minimum depths of steel casing be used at ground surface to protect against breakage and to provide resistance to degradation by sunlight. Rule 10.4.1 requires centralizers to be installed in all grouted intervals of the production casing in order to maintain the natural seal between aquifers. Casing lengths typically run over 40 feet long, so the minimum distance between centralizers should be no more than 50 feet to allow the well constructor to determine where the centralizers should properly be located on the casing. For grouted intervals that span less than 50 feet, the interval must be centralized at the top and bottom of the grouted interval. Unless centralizers are properly installed to center the production casing in a borehole, grout may not adequately flow around the casing or set at a minimum thickness in order to properly seal the well between aquifers, thereby presenting a risk of aquifer cross- contamination. Further, properly-grouted surface casing is the most important protection against surface contamination. Therefore, this rule was amended in 2016 to require centralizers be installed within five feet of the base of the surface casing, to ensure that the annular space outside of the surface casing is grouted uniformly and the casing is centered in the borehole.
Centralizers can only perform their intended function if they survive placement and can maintain the separation between the well casing and the borehole wall or other casing strings. This Rule was further amended in 2025 to clarify the type of materials the centralizers may be constructed of and that the devices must be suitable for the intended purpose. Contractor fabricated centralizer devices must be fabricated of materials that will not be deleterious to or reactive with the casing materials that would accelerate casing corrosion. Centralization of the casing in a single plane within the borehole is not recognized as sufficient centralization to achieve the intent of this Rule; centralization in multiple planes around the circumference of the casing are necessary for proper centralization.
Rule 10.4.2 identifies minimum requirements for wells constructed using surface casing, to ensure that surface contamination will be prevented from migrating into groundwater.
10.4.2.1 clarifies that in certain circumstances where the surface casing is driven below an interval where adequate open annulus exists to properly grout the well in accordance with other minimum requirements near the surface or in intervals required to isolate one aquifer from another, that grout overlapping the base of the driven surface casing surface casing is not required. Restrictions to the maximum distance driven surface casing can penetration from one aquifer to another or into a confining layer were added in 2025 to prevent excessive driven casing lengths that could allow unmitigated vertical movement of groundwater or contaminants from the surface or between aquifers through the possible annulus resulting from the difference in diameter between the driven casing and the drive shoe or bit while providing a adequate distance for a contractor to confirm the material change.
Rule 10.4.3 addresses minimum grout and casing requirements for wells constructed without surface casing.
Rule 10.4.4 discusses minimum annular space requirements for grouted intervals of wells. The size of the annular space is an important factor in obtaining an effective and permanent seal in a well. In general, a larger annular space, in conjunction with the use of casing centralizers, is much more likely to result in an effective seal in the borehole than a smaller annular space that allows the casing to be in contact with the borehole wall during grouting. Rule 10.4.4.3 was added in 2025 to differentiate annular space requirements for tremie placed grout in Type 1 (confined) aquifer and Laramie-Fox Hills wells from other placement methods and aquifer types. This rule increases the annular space to 1.5 inches for specific intervals of tremie placed grout, but does not increase the annular space from that defined in other Rules for poured grout or for grout pumped via positive displacement through the inside of the casing to the outside of the casing (“Halliburton method”). The purpose of this Rule is to provide a greater chance to accomplish the tremie grouting program in wells where confined aquifers exist that represent the highest risk to impact the administration of the groundwater resources if separation of groundwater from different sources is not maintained, and to acknowledge the increase in difficulty to successfully accomplish grouting at increasing depths using tremie placement methods especially when the measurement of annulus does not include couplings and where “practical minimums” for borehole plumbness and alignment as established elsewhere in the Rules are ambiguous and difficult to enforce. It is not the intent of the Rules to allow use of any tremie pipe with an outside diameter larger than the annulus in which it is inserted such that the well casing would not properly centralized due to the size of the tremie pipe. Rule 10.4.4.4 describes an exception to Rule 10.4.4.1 and 10.4.4.2 where grout is poured from the surface and the casing is not vibrated. This method of placement requires a larger annular space.
Rule 10.4.4.5 was added in 2025 to differentiate annular space requirements for granular bentonite used in Type 1 (confined) aquifer wells to the be larger of either the annulus required for other tremie placed grouts defined in Rule 10.4.4.3 or the outside diameter of the tremie having an inside diameter at least 4 times larger than the size of the pellet, granule or chip of bentonite. The minimum interior diameter of the tremie is intended to reduce the potential for clogging/bridging of the tremie during grout placement.
Rule 10.4.5 establishes minimum standards for the intervals of grout and watertight casing in wells constructed into Type 1 (confined) aquifers. Continued and accelerated development of groundwater resources of deeper confined aquifers, and the likelihood that aquifers will increasingly be used for underground storage and recovery, require minimum construction standards that will ensure that wells are constructed to withdraw water from only the authorized zone of production and to prevent leakage to and from the surface and between aquifers through the borehole. Different ownership of waters in adjacent aquifers, the associated administration of separate water sources, and the potential for cross-contamination of adjacent aquifers through the borehole dictate that the construction of wells into and through Type 1 aquifers must be accomplished using appropriate materials installed according to specified procedures. Obtaining a permanent grout seal between aquifers is essential in preventing the unnecessary loss of hydrostatic pressure in a confined aquifer and is necessary for the administration of water rights from the confined aquifer. In addition to the larger annular space explained above, grouting materials and intervals are specified in this Rule to achieve the necessary separation of aquifers. Information that would allow drillers to accurately determine the depth of confining layers is not always available, therefore the best approach to protect groundwater resources is to grout from the top of the production zone back up to the depth required by Rule 10.4.5.2. In addition, grouting through overlying aquifers and confining layers protects the integrity of the casing from poor water quality and corrosion. Figure 6 is included in this Rule to illustrate the necessary elements of well construction in Type 1 aquifers.
In 2025 the Rules were simplified to remove differences between Type 1 aquifers that penetrate only one (1) confining layer and Type 1 aquifers that penetrate more than one (1) confining layer. A grout seal is required from the base of the lower-most confining layer up to the depth required by Rule 10.4.5.2. Greater flexibility has been provided in the Rules to allow contractors to choose a casing type other than steel casing for Type 1 wells where more than one (1) confining layer is penetrated and the option to consider using granular bentonite grout in specific intervals that had previously required a cement-based grout. Contractors and individuals constructing wells are responsible for selecting the proper casing materials and grout to maintain adequate material integrity for their construction methods to resist collapse or damage from the heat from hydration and weight of grout or other fluids.
Rule 10.4.5.3 prohibits compromising the integrity of a confining layer through hydraulic fracturing or artificial stimulation of Type 1 water wells. For the reasons stated above, wells drilled into Type 1 aquifers must protect against cross-contamination between different aquifers and the loss of hydrostatic pressure of a confined aquifer. Rules 10.4.6, 10.4.6.1 and 10.4.6.2 establish minimum standards for the intervals of grout and watertight casing in wells constructed into Type 2 (unconfined bedrock) aquifers; such as the unconfined portion of a Denver Basin aquifer, the fractured granite common in mountain locations, and other water bearing formations that are neither under confined conditions nor consist of recently deposited unconsolidated alluvial and/or colluvial materials. These Rules designate two distinct Type 2 aquifers; those overlain by an alluvial/colluvial aquifer and those not overlain by an alluvial/colluvial aquifer. The required minimum depths of watertight casing and grout placement will afford reasonable protection from surface and near surface contamination of wells constructed into unconfined bedrock.
Rule 10.4.6.3 addresses the issue of intermingling of water between unconfined bedrock and overlying alluvial aquifers. Figures 7a and 7b are included in this Rule to illustrate the necessary elements of well construction in Type 2 aquifers. Rule 10.4.7 establishes minimum standards for wells constructed into Type 3 aquifers (unconfined, unconsolidated material) such as recently deposited material located adjacent to river and stream channels or unconsolidated materials emplaced by gravity (slope wash). The vulnerability to contamination of wells constructed into Type 3 aquifers is well-recognized. The standards adopted in this Rule recognize that most wells constructed into Type 3 aquifers are shallow with a static water level near the land surface and that often, little natural protection from contamination is found between the land surface and the water table. The minimum depth of steel casing, solid casing, and grout interval reflect consideration of these factors. Contractors are encouraged to exceed these minimum standards in instances where the installation of additional grout is practical and may afford the well a greater degree of protection from contamination. Figure 8 is included in this Rule to illustrate the necessary elements of construction of wells completed into Type 3 aquifers.
Rule 10.4.8 sets out minimum construction standards for all wells that are constructed in the aquifer identified by the State Engineer’s office as the Laramie-Fox Hills aquifer. Because of the number of wells drilled in the aquifer, and the expected future wells that will be drilled, the Board has identified minimum standards to ensure that wells constructed in the Laramie-Fox Hills aquifer will be protected from known sources of poor groundwater quality. The Laramie-Fox Hills aquifer is a large aquifer that, in certain locations, was previously categorized as either Type 1 or Type 2. However, the aquifer has known zones of poor water quality, especially near the surface in some regions. Because of the need to ensure that Laramie-Fox Hills aquifer wells will protect the existing groundwater resource and will provide quality water to customers, Rule 10.4.8.2 requires contractors to grout all Laramie-Fox Hills aquifer wells from the top of the permitted production zone up to ten feet above the base of the surface casing, or to the depth required by Rule 10.5.2.1if no surface casing is installed. Rule 10.4.8.2.c was added in 2025 to address the uncommon but potential situation where driven surface casing might be constructed through a portion of a confining layer, but more critically the Laramie Formation above the Laramie-Fox Hills aquifer. The Laramie is known to contain coal seams where low quality water, potentially aggressive to steel, is present. Isolation of the Laramie confining unit with a single layer of steel casing as the only protection is not allowed by these Rules. Rule 10.4.8.2.d describes how any confining layer encountered by driven casing must be sealed by steel casing and grout.
Rule 10.4.9 addresses the construction requirements for the Confined San Luis Valley aquifer, a new aquifer type identified in the 2025 Rules. Previously the construction requirements for the base of the required intervals for solid casing and grout were dictated by permit condition determined by DWR Division 3 engineers and correlated to the top of the confining series of the San Luis Valley aquifer. Such grouted intervals conflicted with the requirements for Type 1, confined aquifers. In acknowledgement that the administration of the Confined San Luis Valley aquifer is handled uniquely for this aquifer, these Rules were established to require solid casing and cement grout be used to isolate the entire interval of the unconfined portion of the San Luis Valley aquifer from the Confined San Luis Valley aquifer at the top of the confining series. The solid casing and grout must extend at least 10 feet below the top of the confining clay and not less than the base of the unconfined San Luis Valley identified by DWR Division 3 engineers on the well permits or the depth of solid casing and grout necessary to resist hydrostatic pressures between the aquifers.
Rule 10.4.10 describes an alternative construction method whereby the inner casing is extended above the land surface and the outer casing is cut off at the surface. Of primary concern in this Rule is the necessity of obtaining a watertight seal to prevent contaminants from entering or moving in the annulus between the casings. Rule 10.4.11. Filter packs requiring the periodic replenishment of additional pack materials must be equipped so that the material can be inserted through an approved filler tube.
Rule 10.4.13 provides requirements for obtaining approval of plans for the construction of infiltration galleries and gallery-type wells. Figures 11.a through 11.c illustrate some of the essential elements of construction of gallery-type wells and provide some acceptable examples of their construction. Due to the high potential for contamination of these types of wells, it is necessary that the construction plans be approved prior to construction so that conditions may be imposed, if necessary, to reduce the risk of such contamination.
Rule 10.4.13 was clarified to describe certain minimum requirements that had generally be enforced for gallery well construction materials. By including these minimum standards in Rules the Board hopes to reduce confusion of individuals who request variances for gallery type wells and to promote the use of long lasting materials, suitable for use in potable water systems and to promote aspects of gallery well construction that separate surface water from groundwater.
Rules 10.4.14 and 15 express the necessity of maintaining a vertical (or near vertical) borehole. A vertical borehole allows casing to be more easily installed and centered within the hole for proper grouting. Vertical wells also minimize wear on casing and pumping equipment due to gravity induced contact of the components within the borehole. Although the State Engineer may allow directional drilling, the minimum well construction standards in these Rules were developed for conventional drilling and construction methods. It is necessary that the Board specifically review and approve well construction procedures that include directional drilling methods that do not comply with the minimum standards of these Rules. Where a contractor, or private driller, desires to construct a well using directional drilling techniques, the contractor must first obtain a permit from the State Engineer for the specific well construction sought, before requesting a variance from the Board under the procedures of Rule 18. Rule 10.4.16 addresses the practice of the construction of sumps or ratholes below the base of an aquifer into a confining unit below the permitted aquifer to allow for the accumulation of sediment, to facilitate the placement of perforated casing through the entire permitted aquifer, or to provide some storage for water where the saturated aquifer interval is thin to promote pump function and cycling. Though previously common, the practice was not specifically addressed in the previous Rules; this Rule now clarifies a maximum depth for sumps and ratholes that do not encounter aquifer materials of another geologic unit below the permitted aquifer and that do not penetrate a confining layer. Should aquifer materials be encountered in the sump/rathole below the permitted aquifer or production zone be encountered in the sump/rathole interval must be filled to maintain separation between the permitted aquifer and the underlying aquifer materials that may have naturally existed and to prevent production from more than one aquifer.
Rule 10.5 addresses minimum grouting standards for wells. Grouting is the only means by which the annular space between the casing and the borehole wall can be artificially sealed with a permanent obstruction that prevents the downward flow or percolation of contaminants from the surface or known zones of subsurface contamination through the borehole into the well and aquifer. Grouting is also the only means by which a permanent seal can be placed between aquifers to ensure that the penetration of the confining layer or layers does not become a conduit for the exchange of groundwater in different aquifers and a potential avenue for cross-contamination of aquifers. Grouting between aquifers is also necessary to prevent the unnecessary loss of hydrostatic pressure in a confined aquifer and is essential for the administration of water rights and entitlements to withdraw water from a specific aquifer. As explained above, the placement of grout is crucial to proper well construction in two primary categories, i.e., 1) near surface to prevent contamination from entering the well from the surface and 2) between aquifers to prevent intermingling of waters from different aquifers. Achieving an adequate grout seal depends on several factors which include the type of grout material used, the means of placement of the grout, the ability to place grout so that voids and intervals of contact between the well casing and borehole wall are eliminated or minimized, and the overall length of the grouted interval. Rule 10.5, in conjunction with Table 2, is intended to set standards for all water wells for the type of grout that may be used, to explain mixing and placement standards, and to establish standard depths below the land surface to the top of near surface grout seals. Standards for grout material, grout interval, and placement procedure for sealing between aquifers are set forth in Rule 10.5.
Table 2 outlines the standards for achieving an acceptable grout mixture of common grouts, depending on the material used and the placement method employed. The table also categorizes commonly used grout materials and identifies those areas in the Rules that address or may restrict the use of certain materials. Table 2 allows for the use of bentonite and alternative grouts in water wells upon written request and approval from the Board. As described in Table 2’s “Approved Grouts” section, a maximum of 6 gallons of water per 94-pound bag of cement is necessary to allow for adequate mixing of cement for neat cement and cement-sand grouts in accordance with guidelines published by the National Groundwater Association (NGWA), the American Water Works Association (AWWA) and Environmental Protection Agency (EPA). Rule 10.5.2.1 sets standards for the depth to the top of the uppermost grouted interval in all wells. In some instances, pitless adapters or pitless units must not be installed if such installation would cause the destruction of a minimum continuous grout interval. Parts a and b of this Rule describe the depth to the top of the uppermost grout interval according to different construction methods (with or without a pitless adapter or pitless unit).
Rule 10.5.3 describes methods of placement for various grout mixtures and establishes standards for the maximum depth to which grout can be poured from the surface. A maximum depth and an adequate annular space are required to properly pour grout to ensure that it reaches the bottom of the interval and to prevent the alteration of the proportions and consistency of the grout mixture during placement. The method of grout placement is important in assuring that the borehole annulus is completely sealed as intended. Positive displacement of the grout mixture from the bottom of the interval upward is the best and recommended placement method. If necessary, grout can be placed in stages to prevent excessive grout loss into the formation. Also if necessary grout can be placed in stages to limit hydrostatic pressures generated during placement.
Rules 10.5.3.1 and 10.5.3.2 establishe the conditions for which the placement occurs via positive displacement.
Rule 10.5.3.3 describes restrictions to the placement of baskets, packers or shale traps above the base of the required grouted interval where the use of those devices will prevent observation of settlement of grout or the loss of grout that could make individual aware that additional grout is necessary to complete grouting to the minimum standards of the Rules. Opportunity remains to place additional baskets, packers or shale traps below the required grouted interval where they will not interfere with the ability to evaluate the success of the grout placement.
Rules 10.5.3.4 and 10.5.3.5 establish the conditions for which the placement grout poured from the surface is sanctioned. Due to the uncertainty in borehole geometry, pouring is restricted to forty feet below ground surface and only in a dry annulus. Cement-sand or concrete grout mixes can only be poured into a hole with a minimum annular space of 6 inches because of its high viscosity. Rule 10.5.3.6, in conjunction with Table 2, sets forth the general limitations for the use of bentonite grouts in water wells and specifies the method of grout placement when the use of bentonite grout has been approved by the Board (see “Bentonite” in Table 2). Because of the numerous considerations involved in the appropriate use, mixing and placement of the various bentonite grout products available, the Board requires that a variance from grout requirements of Rule 10.5 be obtained to ensure that an adequate and permanent grout seal will be achieved. Bentonite grouts may achieve a good annular seal only where the interval remains hydrated. Also, the shear strength of bentonite grouts is insufficient to allow it to be used to separate aquifers where different hydrostatic pressures may exist.
Rule 10.5.4 specifies the required minimum setting time for cement grout prior to the resumption of well construction and/or cleaning and development. To determine the appropriate set times required for neat cement and cement with additives, contractors or private drillers should refer to the grout tables published by Halliburton Services. The Setting time for bentonite grout will be specified in the conditions of approval of the written variance granted for its use and will be in accordance with the manufacturer's recommendations.
Rule 10.6 describes minimum standards for well development and cleaning. Once constructed, and allowing adequate time for any grout that has been placed to set, the completed well must be cleaned of drilling fluids and cuttings and developed to ensure that the well is ready for installation of the pumping equipment. Proper well cleaning and development is necessary to ensure public health for the consumer of the water and to prevent contamination to aquifers. Cleaning and development is required by the well construction contractor, so that a constructed well is prepared for pump installation. Well development is a necessary step in the construction of a water well and is directly related to well design and aquifer characteristics. Well development should establish optimal hydraulic contact between the well and the geologic formation that supplies water, provide an acceptable level of sand and turbidity, and provide for an appropriate level of drawdown at the production pumping rate.
Rule 10.8 requires contractors to measure, and report, a completed well’s static water level. Such information is necessary to provide the well owner, pump installer, and the State Engineer's office with information on groundwater levels. Rule 10.9 requires flowing wells to be equipped with a device that completely controls the flow from the well. Uncontrolled flowing wells waste water, create disposal problems and must be properly equipped to control and stop the flow prior to completing the well construction.
RULE 11 MINIMUM PUMP INSTALLATION AND CISTERN INSTALLATION STANDARDS The purpose of this Rule is to establish the minimum standards for installing pumping equipment and cisterns that are connected to water well supply systems in order to ensure that such installation prevents harm to the public health, will not impair water quality or cause contamination of shared groundwater resources, and will ensure the safety of groundwater resources for Colorado’s existing and future populations. To prevent the contamination of wells and to protect the aquifers and the public health, only individuals authorized by the Board may install pumping equipment and/or cisterns connected to water well supply systems. Standards for pump installations are necessary to assure that pumping equipment is installed to meet the intended purpose of the well and is compatible with the yield of the well. Fittings and connections must be selected and installed to allow water to discharge from the well while providing a watertight seal to prevent leakage of water or the entry of contaminants. Cistern installation standards are necessary to ensure that cistern installations connected to a water well supply system are accomplished in a manner that maintains sanitary conditions for the water supply and prevents backflow contamination to groundwater resources.
Rule 11.1 identifies the limited conditions under which an authorized individual may install pumping equipment, authorizes well construction contractors to install temporary pumps solely for well development and testing. The Rule reflects the statutory requirement that only a licensed pump installation contractor (or private pump installer) can install a cistern or other water storage tank between the wellhead and pressure tank. See § 37-91-109(2), C.R.S. This Rule also emphasizes a pump installation contractor’s responsibility for ensuring that a valid well permit authorizing pump installation exists and cross-references Rules 6.2.2.1 and 6.2.2.2, which address how to fulfill this responsibility. Rule 11.1.2 identifies the limited conditions under which a pump installation contractor may remove and install casing or liners. Rule 11.1.3 prohibits licensed pump installers from installing grout in the annular space of a well, or between well casing; grout installation in a water well at depth is a task for which a water well construction license is required. However, a pump installation contractor may install grout as necessary to install a pitless adapter (assuming the required minimum continuous grout interval is maintained) and to abandon a well pursuant to Rule 16. Rule 11.2 establishes pump installation and cistern installation standards intended to prevent the entry of foreign matter and contaminants into all wells, regardless of whether water withdrawn from a well is used for human consumption. Rules 11.2.1 and 11.2.2. address the installation of pitless adapters or pitless units and of well seals. Where installation of such devices will require some grout removal, any such alteration of grout must still maintain the minimum continuous grout interval required by Rule 10.4 and Rule 10.5. Rule 11.2.4 provides for the penetration of cisterns to install water lines and electrical wires.
Rule 11.3 identifies considerations for locating a cistern to promote sanitary installations that protect the water in the well and aquifer from contamination. Rules 11.3.1 through 11.3.4 address the standards for installing a cistern below ground level. The standards are adopted to prevent rupture or structural failure of the cistern and to prevent contamination from entering the cistern. Rule 11.3.5 addresses the need for all penetrations above and below ground to be watertight to maintain sanitary conditions but does not disallow the use of vents. Rule 11.3.6 addresses the placement of cisterns above interior grade within a building and the need for the supporting structure to carry anticipated loads. Rule 11.3.7 identifies the need for cistern placement at a location that is accessible for maintenance and repair. Rule 11.3.8 identifies persons qualified to connect existing cisterns to water well supply systems. Only persons qualified to install pumps may connect existing cisterns to water well supply systems because of the risk of contamination to the water supply and aquifer from improperly connected systems. Rule 11.3.9 clarifies that materials used to make the cistern watertight must be intended for use in potable-water systems as intended by the manufacturer. Rule 11.4 restricts the location of a cistern to at least 100 feet from a leach field and at least 50 feet from a septic tank or other above or below ground vessel containing contaminants. As with the location of a well, the location of a cistern may be closer than the specified distances only if prior approval of a variance is obtained from the Board. Rule 11.4 also provides the procedure for obtaining a variance to the distance requirements.
Rule 11.5 specifies that a sealed cover or cap is required for all wells and cisterns. After recent experience with forest fires in areas of Colorado where wells were equipped with PVC caps, this rule was clarified to require metal well seals and well caps to protect groundwater from serious contamination caused by fires and subsequent failing of plastic or PVC well caps and well seals. The intent of the Rule is that no well is left open or is equipped with a lid or cover that does not prevent the entry of organisms and fluids into the well.
Rule 11.5.2 addresses well or cistern vents, which, when needed, allow the water level in the well to move freely in response to the operation of the pump or changes in atmospheric pressure. It is the responsibility of the pump installation contractor to determine whether a vent is required.
Rule 11.6 establishes standards for well vaults to minimize the possibility of contamination of the well and aquifer from the presence of insects or animals and improper drainage in existing wells where the casing terminates below ground level. Rule 11.6.2 charges contractors who encounter unacceptable well vaults with the responsibility of either bringing such vaults into compliance with these Rules or with notifying the Board of Examiners of such well vaults. A contractor may install a new well vault only if specifically approved by the Board as part of a variance. Rule 11.7 addresses the installation of water level sounding tubes intended to allow the measurement of the water level. Air lines easily tangle or become slack, leading to incorrect measurements and stuck pumps. Sounding tubes are more reliable and sturdy measurement devices. These devices minimize lost probes and damage to the pumping equipment and facilitate the use of these wells for scientific, engineering and regulatory studies as provided for in Section 37-91-106(4), C.R.S. Rule 11.8 clarifies which aspects of the installation of electrical and plumbing connections between the well and the water system a licensed pump installation contractor may perform, and informs contractors that electrical and plumbing connections are governed by other rules and regulations and are subject to permitting and inspection by other regulatory agencies.
Rules 11.9 and 11.10 are intended to provide for the safe operation of pressurized water systems and to prevent damage to the pump and contamination of the aquifer from the backflow of water in the system. Rule 11.10.1 informs the contractor of other rules and regulations that govern the installation of pumping systems that supply irrigation water where chemicals are injected into the water. Because materials used during the installation of a pumping system may accidentally introduce bacteria or other contaminants into the well, Rule 11.11 requires a contractor to disinfect the well and pumping system after installing the pump and prior to leaving the work site.
RULE 12 WELL TESTING The statutory authority for this rule is found in sections 37-91-106(4), and 37-91- 110(1)(b) & (2), C.R.S. The purpose of this rule is to establish minimum standards for the testing of water wells.
Every well must be tested to obtain an estimate of what the well will produce and to determine if the well produces sufficient water to serve the purpose for which it was constructed. Well yield estimates can be conducted using a variety of procedures of variable accuracy. The well yield estimate approximates the amount of water the well will produce at the time of well construction and assists the well owner and pump installer in determining the size of pumping equipment to be installed. Well owners or contractors who desire or need a more reliable estimate of long-term well yield should arrange for a sustained pump test (well yield test) to be conducted on the well. After installation of the permanent pumping system, the equipment must be tested to ensure the proper operation of the equipment installed and to verify the production rate of the well under normal operating conditions. Rule 12 establishes what the tests should show and clarifies which contractor is responsible for performing and reporting well yield estimates and production equipment tests.
RULE 13 SAMPLING, MEASURING AND TEST PUMPING The statutory authority for this rule is found in section 37-91-106(4), C.R.S. The purpose of this rule is to provide minimum standards for sampling, measuring, or test pumping groundwater to ensure that shared groundwater resources are protected from contamination.
Because inserting probes and sampling equipment potentially may contaminate wells, Rule 13 mandates that all equipment used for sampling, measuring and test-pumping must be disinfected prior to its use in wells. Rule 13 identifies who may remove a well seal, who may perform sampling, measuring or test-pumping, and the purposes to which sampling, measuring and test-pumping are limited, and requires that the well owner know that such activities will be performed. Rule 13 also requires a person conducting such activities to notify the well owner, in writing, of any problems encountered and directs the person who removed the well seal to ensure its proper reinstallation.
RULE 14 MINIMUM CONSTRUCTION STANDARDS FOR MONITORING AND OBSERVATION WELLS, MONITORING AND OBSERVATION HOLES, AND TEST HOLES The statutory authority for this rule is found in sections 37-91-101(1); 37-91-104(1)(c), (j) & (k); 37-91-106(4). The purpose of this rule is to establish minimum construction standards for certain types of holes and wells that may be constructed by authorized individuals who are not specifically licensed by the Board. Such holes and wells must be constructed up to these minimum standards to ensure protection to shared groundwater resources, especially shallow groundwater and alluvial aquifers near the surface.
Rule 14.1 discusses general authorized uses of monitoring and observation holes/wells, dewatering wells, and test holes and provides information and reference regarding who may construct certain monitoring and observation holes/wells. The purpose for which such holes are constructed defines the type of hole or well and thus the minimum standards and authorization required. Rules 14.1.3 to 14.1.10 summarize industry practices necessary to prevent injury to humans and animals and to ensure that the construction and maintenance of such structures is consistent with their intended purpose.
Rule 14.2 explains the differences between a monitoring and observation “hole” and monitoring and observation “well”. Essentially, a monitoring and observations hole is a type of monitoring and observation well that is intended to be a temporary structure (in existence less than eighteen months) and is constructed pursuant to proper notice provided to the State Engineer, while a monitoring and observation well is a more permanent structure that has been granted a permit by the State Engineer. Although often constructed for similar purposes, the duration of each type of structure’s intended use differs. Because monitoring and observation wells will be in place for more than 18 months, it must meet certain construction standards, and be registered accordingly with the State Engineer’s Office, in order to ensure that it will adequately prevent groundwater resources from contamination. Rule 14.2.1.3 identifies the person responsible for ensuring proper permitting or abandonment of a monitoring and observation hole.
Subsequent or alternative use of a monitoring hole also differs from that of a monitoring well. Current procedures of the State Engineer allow a monitoring and observation hole, that was constructed pursuant to the proper notice required by the State Engineer, to be converted only for use as a long-term monitoring and observation well or as a recovery well for remediation of the aquifer. However, a monitoring and observation well that was constructed subsequent to obtaining a monitoring and observation well permit may be re-permitted for other uses, including the withdrawal of water to provide a water supply. Conversion of a monitoring and observation well that was constructed pursuant to a monitoring and observation well permit to a production well may occur only if the structure has been constructed by a licensed well construction contractor in accordance with the minimum construction standards for water wells adopted in these Rules and upon obtaining the appropriate well permit to withdraw and use groundwater from the State Engineer. This requirement ensures that the well will be constructed by individuals with requisite knowledge of well construction standards necessary to protect groundwater and to ensure an adequately-functioning well for the ultimate users of such water supply.
Whether the construction of a monitoring and observation hole or well is for short term testing and monitoring or for long term use, consideration must be given to the location of the structure for maintenance, repair, and ultimately the plugging, sealing, and abandonment of the structure. The Rule also specifies that construction reporting requirements are the same for these structures as they are for water wells. Rule 14.3 sets forth the minimum construction standards for monitoring and observation holes and wells and provides some examples of acceptable design and construction (see Figures 13.a and 13.b) and provide clarification to minimum standards for annular space, acceptable grout materials, method of placement for grout materials, required intervals to be sealed and approved casing materials whereas previous “general” examples in the 2016 version of the Rules left the standards open for significant interpretation. The standards contained in Rule 14.3 afford the greatest possible flexibility for methods of construction while maintaining the safeguards necessary to protect the potable water supply and to prevent the structures from becoming a hazard to public health. The intent of the monitoring and observation hole and well construction standards are to limit the interval being monitored to a single aquifer interval or single geologic unit unless provisions for nested holes/wells are provided. This is accomplished in accordance with the requirements of Rule 14.3.5 requiring an annular seal material in the interval above the filter pack or interval that is intended to be monitored but where the base of the surface for “shallow” seal starts no shallower than 2 feet below the ground surface. Rule 14.3.5 also addresses how to isolate an unconsolidated aquifer from underlying consolidated bedrock materials to preserve any natural protection that might exist between the two. Rule 14.3.6 prohibits the use of PVC casing for completing above-ground wellheads due to the potential for groundwater contamination from PVC failures, especially in areas with forest fire risks. Rule 14.3.6.3 and 14.3.6.4 addresses requirements for the placement of annular seal material at the surface and adjacent to protective steel casing and vaults. Rule 14.4 explains the conditions and limitations of placing pumping equipment in a monitoring and observation hole or well and explains the current requirements of the State Engineer with regard to withdrawing water from a monitoring and observation hole or well.
Rule 14.5 addresses the construction standards for dewatering wells in vertical boreholes. Temporary construction dewatering wells that are in excavated pits or trenches that are not vertical boreholes are not included in the scope of Rule 14.5. Temporary dewatering wells constructed in vertical boreholes require measures to isolate groundwater from surface water or different sources of groundwater similar to monitoring and observation holes/wells with the exception that the shallow seal need not consist of cement grout to facilitate removal of the dewatering well casing upon completion, if desired.
Rule 14.6 provides an explanation of the current requirements of the State Engineer with regard to when notice for the construction of a test hole is required and establishes the duration that test holes may remain open. This Rule distinguishes between test holes that penetrate through a confining layer, and those that do not, because any drilling into or through confining layers presents a risk of aquifer cross-contamination, reduction of hydrostatic pressure, or other contamination to shared groundwater resources. As defined by the Colorado General Assembly, test holes are only those excavations intended for geotechnical, geophysical, or geologic investigation, such as soil or rock-sampling. If such a hole will be used for environmental observations of groundwater levels, it is a monitoring and observation hole. Test holes may not be used for repeated observation, measurement, or sampling of groundwater. RULE 15 MINIMUM DISINFECTION STANDARDS 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.
Materials and equipment used to construct, repair or modify wells, install production equipment, install cisterns and for sampling, measuring and test-pumping of wells frequently becomes contaminated. To protect the groundwater and aquifers from contamination, each well, cistern and any equipment subsequently used in the well or cistern must be disinfected.
This Rule provides minimum standards for the mixing and strength of the disinfectant solution and contact times to assure the proper disinfection of the well, materials and equipment.
Chlorine compounds in solution ensure thorough disinfection while compressed or pelletized chlorine tablets introduced directly into the well can be ineffective for the initial disinfection of a well if they do not completely dissolve. However, as provided in Rule 15.2.2, chlorine tablets are appropriate for use as part of regular disinfection or well maintenance, and are commonly used for this purpose. Disinfection contact times are commensurate with ANSI/NGWA-01-14 Section 9 standards.
Table 3 is intended to assist in the preparation of the minimum strengths of disinfectant solutions. Concentrations are specified in units of mg/l (milligrams per liter), which are approximately equivalent to ppm (parts per million) for the values used in these Rules. Rule 15.3 was modified to allow existing commercial or municipal water well supply systems that maintain disinfection of the overall system to limit the portion of the water well system requiring disinfection following work on the well or pumping equipment that trigger the requirements for disinfection per these Rules. Rule 15.3 clarifies the requirement to circulate disinfectant solution through the well and water well supply system may be limited to the well and water supply system up to a point of isolation within the existing system. The mechanism or arrangement of equipment used to establish that point of isolation must allow the disinfection solution to contact and circulate through the system up to at least that point of isolation.
15.4.3 was modified in 2025 to clarify that disinfection of the well and water supply distribution system was necessary not only after the installation of new pumps in wells or cisterns, but also after existing pumps are pulled and reinstalled in the same well or cistern, or after moving a pump from one well or cistern to another. This change acknowledges that contaminants could contact the pumping equipment during repairs as well as during new installation of equipment and provides requirements for disinfection of the water supply system following repairs and new installation. Rule 15.7 recognizes that the water used in the drilling process potentially may introduce contaminants into a well and restricts the types of containers in which such water can be transported for drilling purposes. Monitoring and observation wells, where the use of a disinfectant will interfere with the purpose of the well, are exempt from Rule 15.
RULE 16 STANDARDS FOR PLUGGING, SEALING, AND ABANDONING WELLS AND BOREHOLES The statutory authority for this rule is found in sections 37-91-101(1); 37-91-104(1)(c), (j), & (k); 37-91-106(3); 37-91-109(1); and 37-91-110(2), C.R.S. The purpose of this Rule is to identify the minimum standards for the proper abandonment of water wells and other excavations constructed into the ground that, if not adequately sealed and abandoned, present a risk to the health and safety of Colorado’s shared groundwater resources.
Wells that are not being used or that are incapable of being used are safety hazards to people and livestock and present potential avenues for contamination of aquifers and groundwater. Rule 16 addresses procedures to assure that unused wells are properly plugged, sealed, and abandoned by persons having the necessary equipment and training. Whenever the surface area of a well site will be reclaimed, the plugged wells should be cut off sufficiently deep to allow normal activity to proceed on the land surface.
Wells that were constructed through more than one aquifer (Type 1 aquifers and Laramie Fox Hills aquifers) must be plugged, sealed, and abandoned by a licensed well construction contractor to ensure that the necessary watertight plug is properly placed at the first confining layer on top of each aquifer. If grout was placed at a confining layer and in accordance with the Rules in place at the time of construction, a minimum cement grout plug no less than 60 feet in length must be placed and should overlap the grouted interval placed outside the casing. Where evidence of grout outside the casing across the confining layer does not exist, to assure that no hydraulic connection between aquifers exists through the borehole, the casing opposite confining layers must be either grouted in the borehole casing annulus and inside the casing, or the casing must be removed, ripped or be perforated so that when grout is placed it may fill the entire borehole across from the confining layer (or a minimum 60-foot interval if the confining layer is less than 60 feet) or fill the casing and any remaining annulus outside the casing through the same intervals. The intervals between grout plugs must be filled with clean materials. Well owners who abandon their own well must consult with a licensed water well construction contractor or Board staff prior to abandoning their well because understanding the hydrogeology of the aquifer(s) is important in applying proper techniques for well abandonment and protection of the groundwater resources of the State of Colorado.
The Confined San Luis Aquifer is also “confined” but it has historically been administered by isolating the unconfined San Luis Aquifer from the confined portion of the aquifer by grouting to a specific depth as required by permit condition. That depth does not represent the base of the confining layer as it would for other “confined aquifers”
Individuals licensed to install pumping equipment have the requisite knowledge and ability to properly plug, seal, and abandon wells that do not require removal of casing that penetrates a confining layer.
Rule 16.5 was modified to define a means to plug and abandon all types of holes, wells and structures addressed by the Rules. If modifies the methods from those allowed in prior Rules, and now requires that any hole, well or other structure under the jurisdiction of the Board that penetrates a confining layer be abandoned per the requirements of Rule 16.2 save for those wells constructed into the Confined San Luis Valley that have their own requirements for abandonment as presented in Rule 16.4. Such a change is necessary to maintain natural protections against movement of water from one aquifer to another when a hole or well penetrates a confining layer. The Rule was further clarified that abandonment of monitoring and observation holes and wells must consider what aquifer type the hole/well were constructed into to determine the proper method for abandonment.
Rule 16.5.4 was included to address how a cistern should be abandoned. If the cistern will be disconnected from the water well supply system and continue to be used, such a change in use is acceptable provided it meets the standards of other governing State or Local agencies having authority over such a structure. If the cistern will no longer be used, abandonment of the structure is required to protect the groundwater resources and public health by removing pathways form the surface to the subsurface where contamination could migrate by the methods described in the Rule. Any waterlines between the cistern and the well or other portions of the water supply system should be removed or properly sealed to prevent contamination through such waterlines. RULE 17 REPORTING REQUIREMENTS The statutory authority for this rule is found in section 37-91-110(2), C.R.S. The purpose of this Rule is to require the submittal of reports concerning the construction of certain excavations as necessary for documenting the location of such excavations, gathering information about hydrogeological conditions of Colorado, and for ensuring compliance with permits and water rights requirements.
Work reports are essential in documenting where wells, test holes, and monitoring and observation holes and wells are constructed, the lithology of geologic formations and aquifers encountered, details of methods and materials used in constructing the well, test hole, or monitoring and observation hole or well, the measurement of the estimated yield of the well, and reporting the type of pumping equipment installed and the tested production of the equipment.
Rule 17.1.1 describes the driller’s requirement to complete a well construction and yield estimate report. This form will more accurately represent the drilling contractor’s estimate of well yield and ensure construction specifications meet the minimum standards.
Rule 17.1.2 describes the driller’s requirements to complete a dry hole construction report. Work reports for dry holes that will not be completed as water wells are another important source of lithology for use by DWR and by contractors, and is an important record for the owner should the construction contractor not be allowed to abandon the hole at the time of construction.
Rule 17.1.3 requires a pump installation report every time a new pump is installed or the depth setting is changed. These reports become part of the structure’s permanent record for future reference should repair, replacement, or plugging of the well become necessary and to ensure the moved or replaced pumps are in compliance with the original permit. The reports are also necessary for administrative purposes mandated by the provisions of Articles 90 and 91 of Title 37, C.R.S., and to verify compliance with these Rules. A contractor’s submittal of a completed work report initiates the period of liability for the contractor for the subject well construction and/or pump installation and is instrumental in preventing the expiration of a well permit. The data submitted on work reports provides the well owner with documentation for water rights proceedings and real estate transactions and enables the Board to monitor and ensure public health and safety.
17.1.4 Well Yield Test Report is the form where pumping test or aquifer test data are reported. The form will include instructions for the submission of pressure transducer data in spreadsheet form. This report must be submitted if the well yield test is performed during the process of well construction.
Rule 17.1.5 addresses Well Abandonment Reports. When any well, monitoring and observation hole/well, dewatering well, or a test hole penetrating a confining layer is taken out of service, it is important to identify and document the equipment removed from the structure, the amounts and types of materials used to plug the structure, and the placement method and intervals of all plugs installed in the structure. This information is necessary to verify the status of a structure and compliance with the provisions of these Rules and regulatory requirements.
Rule 17.1.6 requires individuals responsible for the abandonment of a dry hole must submit a dry hole abandonment report to verify the status of the hole. Rule 17.1.8 Cistern Installation Report. Cisterns filled from a water well are required to be installed by a licensed pump installation contractor. An installation report has not been required so with the implementation of the reporting requirement we now have a means to track cistern installations, the installer and inspection of the installation if needed.
Rule 17.1.9 Post-Construction Well Inspection Report. Form GWS-68 used to verify the construction of an existing well for permitting purposes must be completed or verified by a licensed water well construction contractor. This will help identify if any wells that are contamination sources and need repaired or abandoned and if it meets the description of a well.
To provide a minimum of necessary data and a uniform presentation of the required information, Rule 17.2 provides that the reports must be submitted on a form provided by or approved by the State Engineer. Rue 17.3 establishes criteria for the timely submittal and certification as to the truthfulness of the reports. Rule 17.4 underscores the importance of accurate reports by establishing that such reports are deemed to be completed, signed and certified under oath.
Rule 17.5 Prior to regulation of well construction, numerous wells were constructed or pumping equipment installed without regard to protecting the well from damage and preventing the entry of contaminants. Persons authorized to repair wells and pumping equipment need to correct any such unsanitary conditions encountered. If unable to bring the well into compliance with the standards of these Rules, the person doing the work should provide the information to the Board, or include on the work report any non- compliant conditions not corrected. Such notice will inform the well owner of the non- compliant conditions and will provide the Board and, if necessary, other regulatory agencies with an opportunity to order remedial actions necessary to protect the groundwater supplies of the State.
Rule 17.7 Previously, no records were collected and maintained for the many bacteriological, organic and inorganic chemical analyses performed on newly constructed wells. Knowledge and recording of such water quality data are necessary to locate and identify potable and contaminated groundwater. This information is necessary for the proper design and construction of new wells so that contaminated groundwater can be identified, avoided, and/or contained to protect the public health. Submission to the State Engineer of available water quality data for newly constructed wells becomes part of a data base for statewide ground water quality information. RULE 18 VARIANCES The statutory authority for this rule is found in sections 37-91-101(1); 37-91-104(1)(c), (j), (k) & (2); 37-91-106(3); 37-91-109(1); and 37-91-110(2), C.R.S. The purpose of this Rule is to allow the Board to approve alternate methods of construction or abandonment of an excavation over which it has jurisdiction, in the event that the individual requesting such alternative to the minimum standards can adequately demonstrate that the variance will protect the health and safety of the public and prevent contamination to Colorado’s groundwater.
These Rules establish the minimum standards for common well construction and plugging, sealing, and abandoning methods, equipment and materials used, types of pump installation, cistern installation, and the submission of work reports. However, given the diversity of conditions encountered in the state, Rule 18 recognizes the occasional need for different standards and use of alternative materials, equipment or techniques, provided that such proposals meet the statutory requirements for protecting the groundwater and the aquifers from contamination.
Rule 18.2.1 provides that, to be able to deviate from the minimum standards, a request must be submitted in writing and approved prior to performing such work. Recognizing that conditions or circumstances may arise during well construction that necessitate varying from the minimum standards, this Rule also authorizes variance requests by telephone or fax under such conditions or circumstances, provided that approval of the variance is obtained prior to completing such well construction. Rule 18.2.2 allows the Board to delegate the authority to issue certain categorical variance requests pursuant to specific direction. Such delegation is explicitly authorized and contemplated by section 37-91-104(2), C.R.S.
Rule 18.4 clarifies the finality of the Board’s decision on a variance request and the right to appeal such decision under the Colorado State Administrative Procedures Act. RULE 19 EMERGENCIES The statutory authority for this rule is found in sections 37-91-101(1); 37-91-102; 37-91- 104(1)(c), (j), & (k); 37-91-106(3); 37-91-109(1); and 37-91-110(2), C.R.S. The purpose of this Rule is to ensure that, even in the case of an emergency, excavations under the Board’s jurisdiction must still be constructed upon approval of the State Engineer. Because contamination to groundwater from improper construction practices may cause permanent or costly damage to Colorado’s groundwater resources, emergency circumstances do not negate the requirement to receive necessary approvals and comply with any conditions imposed.
In certain instances, health considerations or sudden well failures may require the construction of a well prior to being able to obtain the required permit. This Rule sets forth the State Engineer’s requirement for obtaining approval to proceed in such situations.
RULE 20 PETITIONS FOR DECLARATORY ORDERS The statutory authority for this rule is found in section 24-4-105(11). The purpose of this Rule is to comply with the requirement of section 24-4-105(11) and provide the Board’s procedures for entertaining, in its discretion, any petitions for declaratory orders to terminate controversies or to remove uncertainties as to the applicability to the petitioners of any statutory provision or of any rule or order of the agency. RULE 21 SEVERABILITY The statutory authority for this rule is found in sections 37-91-104(1)(c), (j), & (k); and 37-91-110(2), C.R.S. The purpose of this Rule is to clarify that each rule is independent of the others, so that if any one Rule is found to be invalid, the remainder will remain in effect.
RULE 22 REVISIONS The statutory authority for this rule is found in sections 37-91-104(1)(c), (j), & (k); and 37-91-110(2), C.R.S.
Entire rule eff. 09/01/2016.
Rule 6.3 eff. 07/01/2018.
Entire rule eff. 01/01/2026.