26.04.04.23

.23 Construction Standards and Special Requirements for Specific Types of Wells.

A. The following special requirements for specific types of wells based on the intended use of the well are as follows:

(1) Irrigation Wells.

(a) Wells in unconfined aquifers in Hydrogeologic Areas 1 and 2 used solely for irrigation shall have an annular space grouted to a minimum depth of 20 feet below land surface.

(b) All other irrigation wells shall meet the grouting requirements of Regulation .19 of this chapter.

(2) Monitoring Wells.

(a) The well driller shall submit to the Approving Authority the construction specifications that are proposed for a monitoring well as an attachment to the permit application.

(b) The Approving Authority may approve, as a special condition of a permit, special construction standards for wells installed for the purpose of monitoring ground water.

(c) If the Approving Authority does not approve special construction standards, then well construction shall comply with the provisions of this chapter.

(d) For an at-grade or below-grade well terminal, the well terminal shall be water tight and enclosed in a well vault.

(3) Injection Wells.

(a) The well driller for an injection well shall submit to the Approving Authority the construction specifications that are proposed as an attachment to the permit application.

(b) The Approving Authority may not issue a permit to construct an injection well unless a State Discharge Permit has been issued by the Department.

(4) Geothermal Wells — Closed Loop.

(a) The pipe material, jointing, pressure testing, and anti-freeze solutions for a closed loop geothermal well shall conform to the standards of COMAR 09.15.05.

(b) The anti-freeze solution shall be environmentally safe.

(c) The borehole of a closed-loop geothermal well shall be grouted from the bottom of the borehole to the ground surface.

(d) The upper terminal of a closed-loop geothermal well may terminate below grade if:

(i) The well location is marked by a metal plate so that the location can be found by a metal detector; or

(ii) The manifold and horizontal lines are marked with detection tape.

(e) When the closed-loop geothermal well is terminated below grade, the well tag shall be attached to the flow center.

(f) If using copper as an exchange medium a maintenance agreement must be recorded in the County land records.

(5) Cathodic Protection Wells.

(a) The borehole of a cathodic protection well shall be grouted from the bottom of the borehole to the ground surface.

(b) The well driller shall submit to the Approving Authority the construction specifications that are proposed for a cathodic protection well as an attachment to the permit application.

(6) Dewatering Wells.The annular space of a dewatering shall be grouted to a depth of 5 feet below the static water level.

B. The following specific construction standards for specific wells, based on construction method, are as follows:

(1) Driven Wells.

(a) Driven wells may not be used for a potable water supply.

(b) In a driven well an oversize hole for grout, at least 4 inches greater in diameter than the casing, shall be constructed to a depth of at least 10 feet, and the annular space between this hole and the casing shall be grouted to land surface.

(c) The upper terminal of a driven well and pitless adapter or pitless unit installation shall be in accordance with this chapter.

(a) Bored, augered, and dug wells shall have a borehole with a minimum diameter of 6 inches larger than the outside diameter of the casing.

(b) The annular space shall be filled with grout to a depth of at least 30 feet below land surface, unless otherwise approved by the Approving Authority.

(c) The annular space below the grout shall be filled with a sand or gravel pack.

(d) Joints in the concrete casing shall be sealed with an impervious seal, such as cement and o-rings, to a depth of at least 20 feet.

(e) The casing shall extend to a depth of at least 2 feet below the lowest seasonal water table.

(f) The minimum depth of the casing shall be 20 feet.

(g) The well shall be protected with either:

(i) A precast, overlapping, steel-reinforced concrete cover; or

(ii) A metal cover at least 3/16 of an inch thick and fitted with a watertight gasket; and

(iii) Be at least 8 inches above grade.

(3) Jetted and Jetted-Driven Wells.

(a) Jetted and jetted-driven wells shall be grouted to a minimum depth of 20 feet. This will necessitate construction of an oversize hole for grout to this depth.

(b) Jetted and jetted-driven wells may not be used for potable water supplies.

(4) Horizontal Wells. The well driller shall submit plans with the Application for a Permit to Drill that provide details on how the horizontal well is to be constructed and identify the materials to be used.