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Geothermal Rules Statement of Basis and Purpose Rule 8.5.2 requires that all boreholes constructed in a loop field for a Type A-CLV geoexchange system be completely filled with an approved grout material. The Rule specifies that grout must be pumped through a tremie pipe lowered to the bottom of the hole so that any fluid in the hole will be displaced by the grout material as the hole is filled. Materials specifically prohibited from use as grout material are identified in the Rule. To achieve the necessary grout seal through the entire length of a borehole, the grout must be placed before there is any collapse of material within the borehole. Rule 8.5.3 requires the placement of grout in a borehole as soon as possible after drilling and the installation of the loop. Rule 8.5.4 addresses the grouting requirement in a borehole that penetrates a confining layer or confining layers. The installation of a cement grout plug across the confining layer is to ensure that the grout material will achieve and maintain a seal between aquifers that may contain fluids under differing hydrostatic pressures. Rules 8.6 and 8.7 are developed to minimize the potential for leakage of the circulating fluid into the subsurface. Rule 8.6 requires a pressure test and visual inspection of the pipe or tubing to be installed in the loop field to determine if leaks exist that must be fixed. An additional pressure test is required after installation of the loops to ensure the structural integrity of the pipe/tubing and connections. Rule 8.7 requires that a pressure shutdown switch be installed so that fluid circulation will cease when a pressure change results from a ruptured pipe in the loop field. In the event a geothermal fluid with an unanticipated temperature exceeding 2120 Fahrenheit is encountered during the construction of a Type A geothermal well, Rule 8.8 requires that all construction activities cease until authorization has been obtained from the State Engineer to complete the well as a Type B geothermal well. Construction must cease to allow the State Engineer an opportunity to consult with the Oil and Gas Conservation Commission and Water Quality Control Division prior to authorizing construction of a Type B geothermal well as required by law. RULE 9 MINIMUM STANDARDS FOR TYPE B GEOTHERMAL WELLS The bases for defining Type B geothermal wells and providing for additional construction standards are: a. Section 37-90.5-106(4) requires that the Oil and Gas Conservation Commission be advised of all applications for these types of geothermal wells and that their comments be considered in issuing permits; and b. oil field equipment, drilling technology and experience is required to construct and complete a deep well or a well with high temperature and pressure. 10