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Geothermal Rules <br />Statement of Basis and Purpose <br />While the well construction principles and methods for a Type B well do not differ from <br />that of a Type A -OS well, most licensed water well construction contractors do not have <br />the necessary equipment or experience to construct a Type B geothermal well. On the <br />other hand, oil field contractors usually lack the statutory qualifications for a licensed <br />water well contractor. In order to provide flexibility for a geothermal well owner to select a <br />qualified contractor and equipment, Rule 9.1 exempts, but does not preclude, a Type B <br />geothermal well from being constructed by a contactor licensed by the State Board of <br />Examiners of Water Well Construction and Pump Installation Contractors. <br />Due to the potential for encountering higher pressures in a Type B geothermal well, Rules <br />9.2, 9.2.1 and 9.2.2 specify different minimum casing and grouting standards than are <br />required by the Water Well Construction Rules, 2 CCR 402-2. The use of steel surface <br />casing, cement grout and blow-out preventers are necessary for controlling any high <br />pressured fluid encountered during the construction of a geothermal well. <br />Rule 9.3 specifies that the construction contractor is responsible for selecting and <br />installing casing and grout material that will contain fluids in the aquifers in which they are <br />encountered and that are sufficient to prevent collapse, rupture, or failure from exposure <br />to the subsurface environment. <br />Rule 9.4 and its subsections address the type, interval, placement, and testing of grout <br />required in the construction of a Type B geothermal well. The information regarding these <br />parameters must be reported to the State Engineer upon completion of construction of <br />the well. The purpose of Rule 9.4 and its subsections is to protect the ground water <br />resources, public health and the environment by ensuring that construction of a <br />geothermal well contains geothermal fluid within the aquifer or interval in which the fluid is <br />encountered. <br />The use of blowout preventers in the construction of a Type B geothermal well is required <br />by Rule 9.5. Blow out prevention is necessary to ensure that geothermal fluids are <br />completely controlled at all times during construction of the well. The Rule provides for <br />obtaining a waiver by variance from the State Engineer of this requirement when it can be <br />shown that such equipment is not needed. <br />RULE 10 MINIMUM STANDARDS FOR GEOTHERMAL REINJECTION WELLS <br />The construction of a geothermal reinjection well does not differ significantly from that of <br />other geothermal wells. Therefore, Rule 10.1 applies the respective construction <br />standards for Type A -OS and Type B wells to a geothermal reinjection well. However, <br />the use and operation of a geothermal reinjection well, especially at higher flow rates and <br />pressures, has a greater potential for contaminating aquifers and ground water. <br />11 <br />