IL Well Driller cheat sheet

Rotary drilling uses a circulating fluid (mud, water, or air) to cool the bit, carry cuttings to surface, and stabilize the borehole wall; cable-tool drilling breaks rock by percussion and removes cuttings with a bailer.

Casing must extend at least 12 inches above the finished ground surface (or above the floor of a pit), and the annular space outside the casing must be sealed to prevent surface water entry.

Grout is placed by the pump-and-treat method from the bottom of the annular space upward; free-fall dumping of grout is prohibited because it bridges and leaves voids.

A well screen or perforated interval is set opposite the producing formation; screen openings are sized to retain formation material while passing water, commonly using the sieve analysis of the aquifer sand.

Drilling fluid density and viscosity must be controlled: excessive mud weight can fracture shallow formations, and excessive sand content accelerates pump wear.

Temporary casing is removed as grout is placed, or the annulus is tremied in stages, so that the seal is continuous from the bottom of the seal to the surface.

Well construction records must document borehole diameter, casing size and depth, screen setting, grout type and volume, and static water level for the completion report.

Artesian (flowing) wells require a control valve and a sealed casing annulus to prevent uncontrolled discharge and cross-contamination between aquifers.

Illinois requires a minimum horizontal separation of 50 feet between a private water well and a septic tank, and 75 feet between a well and a septic absorption field (soil absorption system).

A well must be at least 50 feet from a sanitary sewer line and at least 25 feet from a storm sewer or drainage ditch, with the casing extended above flood level where flooding is possible.

Minimum setback from a privy, cesspool, or pit latrine is 75 feet; from a livestock yard or animal confinement area the minimum is 50 feet.

Grout seals must extend from the top of the well down to at least 25 feet below the ground surface, and deeper where the well passes through a shallow aquifer that must be protected from surface contamination.

Neat cement grout is mixed at no more than 6 gallons of clean water per 94-pound sack of cement; bentonite grout is mixed per manufacturer specification and must not be diluted below the specified density.

Grout volume is calculated from the annular volume between borehole wall and casing, multiplied by an excess factor (commonly 1.1 to 1.5) to account for washouts and lost circulation.

A well may not be located in a floodway, in a pit that can collect surface water, or within 10 feet of a building foundation or property line where local ordinance is stricter.

Where a well is completed in a bedrock aquifer overlain by a shallower aquifer, the casing and grout must seal off the shallow aquifer so that the two are not hydraulically connected.

Well development removes drilling fluid, fines, and filter-cake from the borehole and screen; methods include surging, jetting, air-lifting, and overpumping until the discharge runs clear.

A developed well should produce sand-free water at the design pumping rate; development continues until turbidity and sand content stabilize, not merely until the water first clears.

New wells are disinfected with a chlorine solution producing at least 50 mg/L free chlorine throughout the water column, held for a minimum contact time of 12 hours (24 hours is common practice) before pumping to waste.

After disinfection, the well is pumped to waste until chlorine residual is gone, and a bacteriological sample is collected only after the residual has dissipated.

Pump capacity is selected from the well yield, static water level, pumping water level, and total dynamic head; the pump intake is set above the screen or above the bottom of the well to avoid drawing sand.

A pitless adapter allows the discharge line to pass through the casing below the frost line so the well can be sealed at the surface with a sanitary well cap.

Abandonment of an unusable well requires removal of obstructions where practicable, disinfection, and filling the entire borehole with grout or clean impermeable material placed from the bottom up.

Abandoned wells must be sealed by a licensed well driller and the sealing record filed with the state; an open, unsealed well is a direct pathway for surface contamination to reach the aquifer.

The Illinois Water Well Construction Code is administered by the Illinois Department of Public Health; the code sets construction, sealing, and pump installation requirements for water wells in the state.

Water well drilling and pump installation are licensed activities: a Water Well Driller license and a Water Well Pump Installation license are separate credentials, and work must be performed under the responsible licensee.

A well completion report (driller's log) must be filed with the Department for each well, recording location, depth, geology, casing, grout, and yield.

The code requires a sanitary well cap, a watertight casing, and a grouted annular seal; a well lacking any of these is a construction deficiency subject to correction.

Public health protection focuses on preventing cross-connections and backflow: the well discharge must not be connected to a system carrying nonpotable water without an approved backflow prevention device.

Bacteriological samples are collected in sterile containers after disinfection and chlorine dissipation; a confirmed total coliform positive result triggers investigation and corrective action.

The licensee is responsible for ensuring that equipment and materials contacting drinking water meet NSF/ANSI Standard 61 or an equivalent health-effects standard.

Violations of the code can result in license suspension or revocation, and the Department may order a well sealed or repaired when it poses a contamination risk to the aquifer.