CO Well Driller cheat sheet

Casing must extend from land surface to at least the top of the producing formation and be grouted the full annular length unless a state-approved alternate method is specified in the permit.

Neat cement grout is mixed at no more than 6 gallons of clean water per 94-lb sack; bentonite grout is mixed per manufacturer ratio, typically 1.5 lb per gallon of water for a 12-15% solids slurry.

Annular seal must be placed by the pump-and-tremie method from the bottom up; free-fall placement is prohibited because it bridges and leaves voids.

Minimum grout annulus thickness is typically 2 inches; a 6-inch borehole with 4-inch casing yields a 1-inch annulus and does not comply.

Well casing must be new or reconditioned steel or NSF/ANSI 61-certified thermoplastic; used pipe is prohibited for potable supply wells.

Sanitary well seal or vented cap must be watertight and vermin-proof; the seal must be installed before the well is placed into service.

A minimum 8-hour pump test or bailer test is required to establish yield; record static level, pumping level, drawdown, and recovery rate on the well log.

Setback distances: typically 50 ft from septic tanks and sewer lines, 100 ft from septic drainfields, and 50 ft from property lines unless a variance is granted.

Well log must be filed with the state within the required period (commonly 30 days) and include lithology, casing depth, screen interval, grout volume, and yield.

Grout for closed-loop boreholes must provide low permeability and high thermal conductivity; thermally enhanced bentonite grout typically achieves 0.85-1.4 BTU/hr-ft-F.

Borehole diameter minus U-bend pipe diameter determines grout volume; a 5-inch borehole with 1.25-inch pipe holds roughly 0.11 cubic feet of grout per linear foot.

Grout must be placed by tremie from the bottom up in a single continuous pour; voids or bridging require reaming and re-grouting.

Loop pipe pressure test at 1.5 times maximum system operating pressure (minimum typically 100 psi) for at least 15 minutes before grouting and again before backfilling the header trench.

Borehole depth and spacing are set by the loop-field design; typical vertical boreholes are 150-500 ft deep with 15-20 ft spacing.

Thermal conductivity of the formation should be determined by in-situ thermal response test (TRT) for commercial systems; default conductivity values are used only for small residential designs.

Header trenches below frost line must be backfilled with sand or fine material free of sharp rock, and pipe must be protected from UV and physical damage.

Abandoned boreholes must be grouted full length with the same low-permeability grout used for active loops to prevent cross-contamination of aquifers.

Submersible pump setting depth must keep the pump at least 5-10 ft above the top of the screen or well bottom and below the pumping water level to avoid cavitation.

Pump capacity should match well yield; a pump rated above well yield will draw the water level to the pump intake and cause cycling, overheating, and motor failure.

Pressure tank precharge is set 2 psi below the pump cut-in pressure (e.g., 28 psi precharge for a 30/50 switch).

Total dynamic head = static lift + drawdown + friction loss + discharge pressure head; size the pump from the TDH and required flow on the pump curve.

Wire sizing must account for voltage drop: keep drop under 5% on the run; use the pump manufacturer's ampacity and distance tables rather than generic wire charts.

Pitless adapter must be installed so the drop pipe and service line connect below the frost line; a leak at the adapter is a common cause of lost prime and pressure loss.

Check valve should be installed on the pump discharge; a second check valve may be required on deep settings to protect against water hammer.

Torque arrestor or centralizers protect the drop pipe and wire in deep settings; the safety rope or cable must be rated for the wet weight of the pump, pipe, and water column.

License renewal is typically required every 2 years; continuing education hours must be completed before the renewal deadline or the license lapses.

A surety bond or financial assurance instrument must be maintained in the amount set by the state (commonly $10,000-$25,000) and remain in force while the license is active.

Notify the state within the required period (commonly 30 days) of any change in business name, address, or responsible managing employee.

Work performed without a valid license is unlicensed practice; both the individual and the contracting business may be subject to separate penalties.

A license is not transferable; a new license or registration is required when ownership of the contracting business changes.

Record retention: well logs, grout records, and pump installation records must be kept for the period specified by rule (commonly 3-5 years) and made available on request.

Insurance: general liability and, where required, pollution/environmental liability coverage must be maintained and certificates provided to the state on request.

Disciplinary actions range from a letter of reprimand to suspension or revocation; the licensee is entitled to notice and a hearing before revocation.

Continuing education credit is typically 1 hour per contact hour; a 2-year renewal cycle commonly requires 16-24 hours, with a set minimum in well construction or safety topics.

Carryover of excess CE hours is limited; typically no more than 50% of the requirement may be carried to the next cycle.

Approved providers must issue a certificate of completion showing licensee name, course title, date, hours, and provider approval number; keep certificates for audit.

Remedial action for a failed well or contamination finding begins with notification to the state and the affected water user within the required time (commonly 24-48 hours for contamination).

Corrective options for a contaminated well include re-grouting, extending casing, disinfection with shock chlorination, or abandonment and replacement with a new well at a compliant location.

Shock chlorination: use a chlorine concentration of 100-200 ppm in the well, hold at least 12-24 hours, then flush until chlorine residual is below the potable limit before sampling.

Bacteriological samples must be collected after disinfection and flushing, using a sterile bottle, and submitted to a certified lab; a single negative result may not clear a repeat-positive well.

Abandonment requires filling the entire well bore with approved grout or sealing material and capping; the abandonment record must be filed with the state.

Continuing education credit is typically 1 hour per contact hour; a 2-year renewal cycle commonly requires 16-24 hours, with a set minimum in well construction or safety topics.

Carryover of excess CE hours is limited; typically no more than 50% of the requirement may be carried to the next cycle.

Approved providers must issue a certificate of completion showing licensee name, course title, date, hours, and provider approval number; keep certificates for audit.

Remedial action for a failed well or contamination finding begins with notification to the state and the affected water user within the required time (commonly 24-48 hours for contamination).

Corrective options for a contaminated well include re-grouting, extending casing, disinfection with shock chlorination, or abandonment and replacement with a new well at a compliant location.

Shock chlorination: use a chlorine concentration of 100-200 ppm in the well, hold at least 12-24 hours, then flush until chlorine residual is below the potable limit before sampling.

Bacteriological samples must be collected after disinfection and flushing, using a sterile bottle, and submitted to a certified lab; a single negative result may not clear a repeat-positive well.

Abandonment requires filling the entire well bore with approved grout or sealing material and capping; the abandonment record must be filed with the state.