New Mexico Administrative Code › Title 19 - NATURAL RESOURCES AND WILDLIFE › Chapter 27 - UNDERGROUND WATER › Part 4 - WELL DRILLER LICENSING; CONSTRUCTION, REPAIR AND PLUGGING OF WELLS › Section 19.27.4.30 - WELL DRILLING - NON-ARTESIAN (UNCONFINED) WELL REQUIREMENTS

Current through Register Vol. 35, No. 13, July 16, 2024
A well driller shall ensure that the well drilling
				  activities associated with the drilling of non-artesian wells are made in
				  accordance with
				  19.27.4.29
				  NMAC and the following requirements:
A.
Annular seal:
All wells shall
				be constructed to prevent contaminants from entering the borehole from the
				ground surface by sealing the annular space around the outermost casing. If
				surface casing (outer casing) is used then there must be a seal between the
				surface casing and the production casing at the ground surface. When necessary,
				annular seals will be required to prevent inter-aquifer exchange of water, to
				prevent the loss of hydraulic head between hydrogeologic zones, and to prevent
				the flow of contaminated or low quality water. Sealing operations shall be made
				with an office of the state engineer approved sealant. Casings shall be
				centralized within the interval to be sealed so grout or sealing materials may
				be placed evenly around the casing.
(1)
Annular space:
The diameter of the borehole in which the annular
				seal is to be placed shall be at least four inches greater than the outside
				diameter of the outermost casing. The diameter of the borehole in which the
				annular seal is to be placed may be reduced to three inches greater than the
				outside diameter of the outermost casing if pressure grouting from the bottom
				up is used for grout placement and the well casing is centralized in the
				borehole. If surface casing is used, the inside diameter of the surface casing
				shall be at least three inches greater than the outside diameter of the
				production casing.
(2)
Annular seal completed to ground surface:
Annular seals shall
				extend from ground surface to at least 20 feet below ground surface.
(a) If a well is completed less than 20 feet
				below ground surface, the seal shall be placed from ground surface to the
				bottom of the blank casing used. However, if a monitoring well is completed
				less than 20 feet below ground surface, the seal shall be placed for the
				maximum length practical in order that the well is constructed to prevent
				contamination, to prevent inter-aquifer exchange of water, to prevent flood
				waters from contaminating the aquifer, and to prevent infiltration of surface
				water.
(b) The annular seal shall
				extend to ground surface unless a pitless adapter is installed. For wells
				completed with a pitless adapter, the top of the seal shall extend to one foot
				below the pitless adapter connection.
(c) All sealing materials placed deeper than
				20 feet below ground surface shall be placed by tremie pipe or by
				pressure-grouting through the well casing and up the annulus.
(d) If in the event the water level in the
				annular space is less than 20 feet from surface, all sealing material shall be
				filled from the bottom upwards to ground surface using a tremie pipe. Time
				release bentonite pellets maybe used without a tremie pipe where standing water
				is above 20 feet.
(3)
Annular seals to prevent inter-aquifer exchange of water or loss of
				hydraulic head between hydrogeologic units:
Sufficient annular seal
				shall be placed to prevent inter-aquifer exchange of water and to prevent loss
				of hydraulic head between hydrogeologic units. Sufficient annular seal shall be
				placed to prevent loss of hydraulic head through the well annulus, through
				perforated or screened casing, or through an open bore interval.
(4)
Annular seals to prevent the
				contamination of potable water:
Wells which encounter non-potable,
				contaminated, or polluted water at any depth shall have the well annulus sealed
				and the well properly screened to prevent the commingling of the undesirable
				water with any potable or uncontaminated water. The use of salt-tolerant
				sealing materials may be required by the state engineer in wells that encounter
				highly mineralized water.
(5)
Annular seal requirements for community water supply wells:
Community water supply wells shall also be completed with annular seals in
				accordance with other regulatory agencies' applicable ordinances or rules. Well
				drillers may be subject to other applicable federal, state, or local
				regulations.