§11-23-10 - Provision for artesian aquifer protection.

§11-23-10 Provision for artesian aquifer protection.

(a) Where an injection well is located in a caprock formation which overlies volcanic USDW under artesian pressure, the following conditions shall be applied:

(1) A buffer zone of at least fifty feet of the confining materials (caprock) or other impermeable substance, shall remain between the bottom of the injection well and the top of the volcanic aquifer, and

(2) Injection pressure, as measured at the feed elevation or well head, shall remain below the hydrostatic pressure of the volcanic aquifer (the artesian head) or two p.s.i., whichever is greater.

(b) The locations of artesian aquifer areas are described generally. The major areas, which have an extensive caprock formation, include:

(1) The southern coastal plains of Oahu, from Kahe Ft. (West Beach) to Wailea Pt. (Lanikai);

(2) The windward (eastern) coastal plains of Oahu, from Makalii Pt. (Punaluu) to Waialee;

(3) The northern coastal plains of Oahu, from Haleiwa to Mokuleia; and

(4) The Mana Plain on western Kauai, from Polihale to Kekaha.

Other artesian aquifer areas are found in valleys, where alluvium or other sedimentary material has been deposited to significant depths.

(c) If the ratio of the depth of the proposed injection well, to the estimated depth of caprock less fifty feet, is 1:2 or less, the applicant need not extend the depth of the injection well or wells in order to verify caprock thickness, prior to completion at the shallower proposed depth. The department shall estimate the depth of caprock by comparing lithology from logs of borings in the vicinity. If, however, artesian aquifer conditions are encountered, the applicant shall have the options as set forth in subsection (f). The following is a table showing the depths needed to achieve the 1:2 ratio:

Proposed depth of

injection well: 10 15 20 25 30 40 50 60 70 80 90 100

Minimum depth . 70 -80 90 100 110 130 150 170 190 210 230 250 of caprock:

(d) If the ratio of the depth of the proposed injection well, to the estimated depth of caprock less fifty feet, is greater than 1:2, the applicant shall have the depth of the injection well temporarily extended by fifty feet to verify that artesian aquifer conditions are not encountered within that range. The fifty feet of extended hole shall be properly sealed by the tremie method, with a cement slurry that contains no more than five gallons of water per ninety-four pound sack of cement.

(e) Where a test well is planned for either a single injection well or a multiple well field, the depth of the test well shall be extended fifty feet into confining materials beyond the proposed depth of the deepest well. If the test well is intended to be operational, the lower fifty feet shall be properly sealed as detailed in subsection (d) of this section.

(f) Where artesian aquifer conditions are unexpectedly encountered, the applicant may choose to:

(1) Abandon and properly seal the injection well with neat cement and request approval for a new location; or

(2) Modify the depth of the injection well or wella so that it conforms with subsection (a)(1).

         [Eff. 7/6/84; am and comp NOV 1 2 1992 ] (Auth: HRS S340E-2) (Imp: HRS §340E-2, 40 CFR §§144.11 and 144.12)

The following state regulations pages link to this page.