MD Well Driller common mistakes
MD Well Driller · Understand the traps and how to avoid them.
Treating the 100-foot regulatory casing minimum as a single universal number and applying it to every well, instead of distinguishing the statutory minimum from the site-specific casing depth the permit requires (e.g., full casing through unconsolidated overburden to competent rock, or deeper where shallow water is degraded).
Candidates memorize one headline number from the regulations and stop reading, so they miss that the approved permit and the geology can require casing deeper than the minimum, and that certain well types and settings carry different requirements.
What to do instead
Build a one-page casing decision tree: statutory floor, permit-specified depth, depth to competent bedrock, and any water-quality or setback-driven extra casing. Practice with scenarios where the minimum is inadequate and be able to state which authority governs each layer.
Answering grouting questions with a generic 'seal the annulus' response, without specifying the approved grout material, the placement method (tremie/positive displacement from the bottom up), or the required annular seal depth and thickness.
Grouting is learned on the job as a practical step, so candidates know it matters but never drill into the material specifications and placement mechanics that the exam tests.
What to do instead
Memorize the grout material list (neat cement, bentonite, sand-cement mixes as allowed), the prohibition on dumping grout from the top, and the seal-depth rules. Rehearse a written grouting procedure end to end, including verification and what to do if the seal fails.
Confusing well development with well disinfection or with drilling completion, describing development as 'adding chlorine and pumping until clear' rather than a separate mechanical/hydraulic process to remove drilling fluid, fines, and filter-cake and restore formation permeability.
On real jobs, development, disinfection, and pump testing often happen in the same visit, so the boundaries blur and candidates merge the three into one mental step.
What to do instead
Create a four-column table: purpose, method, endpoint/criteria, and common failure for development, disinfection, and pumping test. State development endpoints (turbidity, sand content, specific capacity stabilization) explicitly and keep chlorine out of the development answer.
Selecting a drilling method by habit (e.g., always air rotary or always mud rotary) without matching it to the formation, intended use, and contamination risk, and without explaining the tradeoffs of each method.
Candidates learn one method thoroughly at their own shop and generalize it, rather than reasoning from formation characteristics, hole stability, sample quality, and water-quality protection.
What to do instead
Study each method (cable tool, mud rotary, air rotary, down-the-hole hammer, auger, jetting) against a matrix of formation type, depth, casing/gravel pack needs, and contamination sensitivity. Practice justifying a method choice in two or three sentences with formation-specific reasons.
Miscalculating or misapplying well yield and drawdown relationships, such as treating specific capacity as a fixed property, ignoring pumping-level stabilization, or confusing static water level, pumping water level, and total drawdown.
The terminology sounds interchangeable in casual use, and candidates have not practiced the arithmetic or the interpretation of a pumping test under exam conditions.
What to do instead
Drill the definitions and units until automatic: static level, pumping level, drawdown, specific capacity (gpm per foot of drawdown), and safe yield. Work practice problems computing each from a test data set and explain what a changing specific capacity implies about well condition.
Missing the notification, reporting, and recordkeeping obligations that attach to drilling a well, such as when the permitting authority must be notified before work, what the well completion report must contain, and the deadline for filing it.
These are administrative details buried in regulation text, and candidates focus their study on technical drilling content because that is what they do daily.
What to do instead
Make a regulatory calendar and checklist: pre-construction notice, permit conditions, log/report contents (depth, casing, grout, screen, yield, water quality), and submission deadlines. Quiz yourself on who receives copies and what happens when a report is late or incomplete.
Assuming a license or permit issued elsewhere, or a general contractor credential, authorizes well drilling in Maryland, instead of recognizing the state-specific licensing requirement and its scope, exemptions, and renewal conditions.
Experienced drillers from other states or adjacent trades assume reciprocity or that their practical experience substitutes for the Maryland credential.
What to do instead
Study the Maryland licensing framework directly: who must hold a license, what activities are covered, what exemptions exist, continuing education and renewal rules, and the consequences of unlicensed practice. Write out the exemption list and test yourself on borderline scenarios.
Answering disinfection questions with a vague 'shock the well with bleach' and omitting the required chlorine concentration, contact time, pH considerations, and the need to verify with a bacteriological sample before the well is placed in service.
Field practice is often informal and based on habit, so candidates never learn the specified concentration-contact-time relationship or the sampling protocol that confirms success.
What to do instead
Memorize the concentration and contact-time standard, the procedure for introducing and mixing the solution, the flushing step, and the sampling requirements including who collects the sample and what result clears the well. Practice a full written disinfection protocol.
Treating setback distances and separation requirements as rough rules of thumb, rather than precise measured distances from specific sources of contamination (septic systems, animal enclosures, property lines, other wells, surface water).
Distances get estimated in the field and vary by local health department practice, so candidates carry approximate numbers instead of the regulated values.
What to do instead
Build a setback reference sheet with each source and its required distance, and note where local rules may be stricter. Practice scenario questions where the measured distance is just inside or just outside the limit and the answer turns on which source is involved.
Describing gravel pack and screen selection generically ('size the screen to the formation') without applying the formation-sample analysis, uniformity considerations, slot-size relationship to the gravel pack, and the effect of a poor match on sand production and well efficiency.
Design choices are often inherited from a prior well design or a supplier recommendation, so candidates never work through the sizing logic themselves.
What to do instead
Learn the sieve-analysis workflow: determine formation grain-size distribution, select gravel pack gradation, then select screen slot opening relative to the pack. Work two or three sample problems and connect a mismatched design to its observable symptoms (sand entry, reduced specific capacity, pump wear).