MD Well Driller cheat sheet

Casing must extend at least 50 ft below grade and be grouted to a minimum depth of 50 ft; where the first confining layer is deeper, grout must extend at least 10 ft into that confining unit.

Minimum annular grout thickness is 1.5 in. for boreholes up to 10 in. diameter and 2 in. for larger boreholes; neat cement or bentonite grout is required, and drill cuttings or native material may not be used as grout.

A well must terminate at least 10 ft from a property line, 50 ft from a septic tank or absorption field, 100 ft from a sewage lagoon or manure storage, and 25 ft from a building foundation unless the casing is grouted to the required depth.

The well casing must be new steel meeting ASTM A53 or A589, or NSF/ANSI 14 PVC, with minimum wall thickness of 0.188 in. for steel and SDR 21 or heavier for PVC.

A pitless adapter must be installed with the discharge line below the frost line (typically 42-48 in. in Maryland) and the casing must be sealed watertight at the adapter.

Static water level is the level of water in a well when the pump is off and equilibrium is reached; pumping water level is measured while the pump is running at design capacity.

Drawdown equals pumping water level minus static water level; specific capacity equals pumping rate divided by drawdown, expressed in gallons per minute per foot (gpm/ft).

A well must be capped with a sanitary well seal and a vent that is screened and turned downward, with the vent opening at least 18 in. above grade.

Rotary air drilling is preferred in hard rock; foam or water injection controls dust and stabilizes the borehole where air alone causes caving.

Mud rotary drilling uses bentonite or polymer mud to cool the bit, carry cuttings, and maintain hydrostatic pressure against formation fluids; mud weight is monitored to prevent blowout.

Cable tool (percussion) drilling uses a heavy bit and a bailer; it is suited to unconsolidated sand and gravel and produces a clean borehole but slower penetration in hard rock.

Auger drilling (flight or bucket) is limited to unconsolidated materials above the water table; hollow-stem augers can drill below the water table with a plug and casing.

Air rotary hammer drilling uses a down-the-hole hammer for hard rock; penetration rate depends on air volume (cfm), bit pressure, and rock hardness.

Reverse circulation drilling pumps fluid down the annulus and up the drill pipe, allowing large-diameter holes and continuous sample recovery.

Bit selection: tricone roller bits for soft to medium formations, drag bits for soft clay and sand, and diamond or button bits for hard rock.

Drilling fluid velocity in the annulus must exceed the settling velocity of cuttings; insufficient uphole velocity causes cuttings to accumulate and the drill string to stick.

Well development removes drilling fluid and fines from the formation near the borehole; methods include surging, jetting, air-lifting, and overpumping.

Development is complete when the discharge is clear, sand content is below 5 ppm, and specific capacity stabilizes.

A yield (pump) test should run at a constant rate for at least 2 hours, or until drawdown and pumping level stabilize, with measurements recorded every 15-30 minutes.

A step-drawdown test uses successively higher pumping rates to determine well efficiency and the well-loss coefficient; specific capacity declines as the rate increases.

Disinfection requires a chlorine concentration of at least 50 mg/L (ppm) in the well, with a contact time of at least 12 hours, before the well is put into service.

Chlorine demand of the formation and casing reduces free chlorine; the dose must be checked and re-established if free chlorine falls below 50 mg/L during contact time.

After disinfection, the well must be pumped to waste until the chlorine residual is gone and the water is clear before sampling for coliform bacteria.

A bacteriological sample must be collected in a sterile container, transported chilled, and analyzed within 30 hours of collection for total coliform and E. coli.

The Maryland Department of the Environment (MDE) regulates well construction under COMAR 26.04.04; a permit from the local health department is required before drilling a new well.

A Maryland Well Driller license is issued by the State Board of Well Drillers; a journeyman or master driller must be on site or directly supervise the work.

Well completion reports must be filed with MDE within 30 days of completion, documenting location, depth, casing, grout, yield, and static water level.

A notice of intent to drill must be filed with MDE at least 3 business days before drilling begins; emergency repairs may proceed with notice within 24 hours.

The Board may suspend or revoke a license for gross negligence, falsifying a completion report, or abandoning a well without proper sealing.

A well that is no longer in use must be properly abandoned: the casing is removed or perforated, the borehole is filled with grout or approved material, and a report is filed with MDE.

Continuing education is required for license renewal; the Board sets the credit hours and approves the courses.

A driller must maintain at least the minimum liability insurance and post a bond as required by the Board before a license is issued or renewed.