5 Colo. Code Regs. § 1002-42.25
The provisions of C.R.S. 25-8-202; 25-8-203; and 25-8-204 provide the specific statutory authority for adoption of these regulatory provisions.
STATEMENT OF BASIS AND PURPOSE
The Commission has adopted, in compliance with section 24-4-103(4) C.R.S. the following statement of basis and purpose.
Background
As a result of this hearing, the Commission applied the classification of limited quality and use to the ground water contained within the following specified areas:
Larimer County (Figure 42) The Early Jurassic aged Entrada Sandstone and the Lower Cretaceous aged Muddy Sandstone (J Sand) of the Dakota Group within a specified area of Larimer County, Colorado in which extensive oil and natural gas exploration and development have occurred. The Muddy Sandstone is a stratigraphic equivalent to the J Sandstone of the Lower Cretaceous Dakota Group. Muddy Sandstone is the name used commonly in Wyoming and J Sandstone is the name used commonly in northeastern Colorado. The specified area includes approximately 135 square miles in northeast Larimer County, Colorado.
Jackson County (Figure 43) The Lower Cretaceous aged Dakota and Lakota Sandstones and the Upper Cretaceous aged Pierre B Sandstone Member of the Pierre Shale within a specified area of Jackson County, Colorado in which extensive oil and natural gas exploration and development have occurred. The specified area includes approximately 56 square miles in northern Jackson County, Colorado.
Jackson County (Figure 44) The Lower Cretaceous aged Dakota and Lakota Sandstones within a specified area of Jackson County. Colorado in which extensive oil and natural gas exploration and development have occurred. The specified area includes approximately 17 square miles in northern Jackson County, Colorado.
Moffat County (Figure 45) The Paleocene aged Fort Union Formation within a specified area of Moffat County, Colorado in which extensive oil and natural gas exploration and development have occurred. The specified area includes approximately 38 square miles in northern Moffat County, Colorado.
The adoption of this Limited Use and Quality classification by the Commission does not preclude the need for obtaining an aquifer exemption under the UIC program, if future applicants wish to inject fluids into portions of the subject formations within each specified area for which an aquifer exemption would be needed. That is, the adoption of this classification does not preclude the need for compliance with the specific requirements of the UIC program.
F Site-Specific Classifications
Site-specific classification of ground water begins with the identification of the use of the water within the four specified areas as follows:
Larimer County (Figure 42) The ground water in the Lower Cretaceous aged Muddy Sandstone (J Sand) of the Dakota Group is co-produced with oil and gas and is considered a waste. Within the specified area, ground water in both the Entrada Sandstone and Muddy Sandstone (J Sand) is not currently used nor can it reasonably be expected to be used in the future for domestic or agricultural purposes. The ground water is not in communication with any surface water bodies within the specified area so that the water quality standards of any classified surface water bodies are not affected by this ground water. More specific evidence of the limited use and quality of this ground water follows:
Within the specified area there are approximately 710 water wells permitted with the Office of the State Engineer. Division of Water Resources data indicates that there are no public water systems, or domestic, agricultural, commercial, or industrial water wells completed in the Entrada Sandstone or the Muddy Sandstone (J Sand) within the specified area.
The Entrada Sandstone and the Muddy Sandstone (J Sand) contain or have contained naturally occurring accumulations of crude oil and natural gas, in addition to ground water in many portions of this specified area. These oil and gas resources have been developed and produced since the 1920's.
Within the specified area approximately 183 oil and gas wells or tests have been drilled to or completed in the Muddy Sandstone (J Sand). Several of these wells were drilled deeper to the Entrada Sandstone.
Within the specified area the Colorado Oil and Gas Conservation Commission (COGCC) has granted four aquifer exemptions for UIC projects under Rule 324(B) of the Rules and Regulations, Rules of Practice and Procedure (2 CCR 404-1), pursuant to the Colorado Oil and Gas Conservation Act, Title 60, Article 34, C.R.S. (1982). The Clarks Lake Muddy Sand Unit is an enhanced recovery project that uses approximately 4 injection wells completed in the Muddy Sandstone. The South Clarks Lake Unit is an enhanced recovery project that uses approximately 3 injection wells completed in the Muddy Sandstone. The Wellington Muddy Sand Unit is an enhanced recovery project that uses approximately 5 injection wells completed in the Muddy Sandstone (J Sand). The Wellington Unit 27-3 is a disposal project that uses one injection well completed in the Entrada Sandstone. Two other injection projects also have been permitted within the specified area; however, these did not require aquifer exemptions, because the total dissolved solids (TDS) concentrations of the injection zone exceeded 10,000 milligrams per liter (mg/l). The Fort Collins Muddy Sand Unit is an enhanced recovery project that uses approximately 20 injection wells completed in the Muddy Sandstone. The Peterson 14-20 is a disposal project that uses one injection well completed in the Muddy Sandstone.
Within the specified area the Entrada Sandstone lies between 5,200 - 6,100 feet below the ground surface (fbgs) and the Muddy Sandstone (J Sand) lies between 4,200 - 6,200 fbgs.
Based on information available to the COGCC, within the specified area the TDS concentration of the Entrada Sandstone is 4,611 milligrams per liter (mg/l). The TDS concentration of the Muddy Sandstone (J Sand) ranges from 6,945 mg/l to 14,906 mg/l with an average of 10,025 mg/l.
Hydrogeologic data including produced water quality and depths of the Entrada Sandstone and Muddy Sandstone (J Sand) and other COGCC data indicate that the ground water in these formations meets the criteria in Regulation 41 for classification as "Limited Use and Quality" . The Commission, therefore, concluded that the application of the "Limited Use and Quality" classification to the ground water within the Entrada Sandstone and the Muddy Sandstone (J Sand) in the specified area is appropriate. This classification and the application of site-specific standards for organic chemicals assure consistency between implementation of the Underground Injection Control (UIC) Program requirements and WQCC Standards and Classification.
Jackson County (Figure 43) The ground water in the Lower Cretaceous aged Dakota and Lakota Sandstones and the Upper Cretaceous aged Pierre B Sandstone Member of the Pierre Shale is co-produced with oil and gas and is considered a waste. Within the specified area, ground water in both the Dakota and Lakota Sandstones and Pierre B Sandstone Member of the Pierre Shale is not currently used nor can it reasonably be expected to be used in the future for domestic or agricultural purposes. The ground water is not in communication with any surface water bodies within the specified area so that the water quality standards of any classified surface water bodies are not affected by this ground water. More specific evidence of the limited use and quality of this ground water follows:
Within the specified area there are approximately 16 water wells permitted with the Office of the State Engineer. Division of Water Resources data indicates that there are no public water systems, or domestic, agricultural, or industrial water wells completed in the Dakota and Lakota Sandstones. There are 9 commercial water well permits within the specified area. Three of these are former oil wells that have been recompleted in the Pierre Sandstone. Water from these wells is used as makeup water for the enhanced recovery injection project in the McCallum Unit. The remaining six commercial water wells are completed in shallower aquifers.
The Dakota and Lakota Sandstones and the Pierre B Sandstone Member contain or have contained naturally occurring accumulations of crude oil and natural gas, in addition to ground water in many portions of this specified area. These oil and gas resources have been developed and produced since the 1920's.
Within the specified area approximately 240 oil and gas wells or tests have been drilled to or completed in the Dakota and Lakota Sandstones or the Pierre B Sandstone Member.
Within the specified area the COGCC has granted 2 aquifer exemptions for UIC projects under Rule 324(B) of the Rules and Regulations, Rules of Practice and Procedure (2 CCR 404-1), pursuant to the Colorado Oil and Gas Conservation Act, Title 60, Article 34, C.R.S. (1982). The McCallum Unit is an enhanced recovery project that uses approximately 37 injection wells completed in the Pierre B Sandstone. The Dwinell 1 in the Battleship Field is a disposal project that uses one injection well completed in the Dakota and Lakota Sandstones.
Within the specified area the average depth to the Dakota and Lakota Sandstones is 4,700 fbgs in the Battleship Field, and 5,800 fbgs in the McCallum Field. The average depth to the Pierre B Sandstone is 1,000 fbgs in the McCallum Field.
Based on information available to the COGCC, within the specified area the TDS concentration of the Dakota and Lakota Sandstones ranges from 474 mg/l to 11,533 mg/l with an average of 4,327 mg/l. The TDS of the Pierre B Sandstone Member of the Pierre Shale is greater than 20,000 mg/l.
Hydrogeologic data including produced water quality and depths of the Dakota and Lakota Sandstones or the Pierre B Sandstone Member of the Pierre Shale and other COGCC data indicate that the ground water in these formations meets the criteria in Regulation 41 for classification as "Limited Use and Quality". The Commission, therefore, concluded that the application of the "Limited Use and Quality" classification to the ground water within the Dakota and Lakota Sandstones or the Pierre B Sandstone Member of the Pierre Shale in the specified area is appropriate. This classification and the application of site-specific standards for organic chemicals assure consistency between implementation of the UIC Program requirements and WQCC Standards and Classification.
Jackson County (Figure 44) The ground water in the Lower Cretaceous aged Dakota and Lakota Sandstones is co-produced with oil and gas and is considered a waste. Within the specified area, ground water in the Dakota and Lakota Sandstones is not currently used nor can it reasonably be expected to be used in the future for domestic or agricultural purposes. The ground water is not in communication with any surface water bodies within the specified area so that the water quality standards of any classified surface water bodies are not affected by this ground water. More specific evidence of the limited use and quality of this ground water follows:
Within the specified area there are approximately 12 water wells permitted with the Office of the State Engineer. Division of Water Resources data indicates that there are no public water systems, or domestic, agricultural, commercial, or industrial water wells completed in the Dakota and Lakota Sandstones.
The Dakota and Lakota Sandstones contain or have contained naturally occurring accumulations of crude oil and natural gas, in addition to ground water in many portions of this specified area. These oil and gas resources have been developed and produced since the 1920's.
Within the specified area approximately 42 oil and gas wells or tests have been drilled to or completed in the Dakota and Lakota Sandstones.
Within the specified area the COGCC has granted 1 aquifer exemption for UIC projects under Rule 324(B) of the Rules and Regulations, Rules of Practice and Procedure (2 CCR 404-1), pursuant to the Colorado Oil and Gas Conservation Act, Title 60, Article 34 C.R.S. (1982). The Spaulding 4-B in the Lone Pine Field is a disposal project that uses one injection well completed in the Dakota and Lakota Sandstones.
Within the specified area the average depth to the Dakota and Lakota Sandstones is 2,400 fbgs in the Lone Pine Field.
Based on information available to the COGCC, within the specified area the TDS concentration of the Dakota and Lakota Sandstones ranges from 1,053 mg/l to 11,892 mg/l with an average of 4,612 mg/l.
Hydrogeologic data including produced water quality and depths of the Dakota and Lakota Sandstones and other COGCC data indicate that the ground water in these formations meets the criteria in Regulation 41 for classification as "Limited Use and Quality" . The Commission, therefore, concluded that the application of the "Limited Use and Quality" classification to the ground water within the Dakota and Lakota Sandstones in the specified area is appropriate. This classification and the application of site-specific standards for organic chemicals assure consistency between implementation of the UIC Program requirements and WQCC Standards and Classification.
Moffat County (Figure 45) The ground water in the Paleocene aged Fort Union Formation is co-produced with oil and gas and is considered a waste. Within the specified area, ground water in the Fort Union Formation is not currently used nor can it reasonably be expected to be used in the future for domestic or agricultural purposes. The ground water is not in communication with any surface water bodies within the specified area so that the water quality standards of any classified surface water bodies are not affected by this ground water. More specific evidence of the limited use and quality of this ground water follows:
Within the specified area there are approximately 6 water wells permitted with the Office of the State Engineer. Division of Water Resources data indicates that there are no public water systems, or domestic, agricultural, commercial, or industrial water wells completed in the Fort Union Formation.
The Fort Union Formations contains naturally occurring accumulations of crude oil and natural gas, in addition to ground water in many portions of this specified area.
Within the specified area approximately 29 oil and gas wells. Many of these wells were drilled to and/or completed in the Fort Union Formation.
Within the specified area the COGCC has permitted two injection projects. These did not require aquifer exemptions, because the TDS concentration of the injection zones exceeded 10,000 milligrams per liter (mg/l). The Big Hole Federal 10-1 is a disposal project that uses one injection well completed in the Fort Union Formation. The Shell Creek #4 is a disposal project that uses 1 injection well completed in the Fort Union Formation.
Within the specified area the Fort Union Formation lies between 2,500 - 5,900 fbgs.
Based on information available to the COGCC, within the specified area the TDS concentration of the Fort Union Formation ranges from 8,177 mg/l to 32,120 mg/l with an average TDS of 23,080 mg/l.
Hydrogeologic data including produced water quality and depths of the Fort Union Formation and other COGCC data indicate that the ground water in this formation meets the criteria in Regulation 41 for classification as "Limited Use and Quality" . The Commission, therefore, concluded that the application of the "Limited Use and Quality" classification to the ground water within the Fort Union Formation in the specified area is appropriate. This classification and the application of site-specific standards for organic chemicals assure consistency between implementation of the UIC Program requirements and WQCC Standards and Classification.
Consistent with the "Limited Use and Quality" classification, the ground water quality standards in Tables 1 through 4 of the Basic Standards for Ground Water, 41.0 will not apply within the specified area. Additionally, the ground water organic chemical standards included in Table A of Section 41.5.C.3 of the Basic Standards for Ground Water (5 CCR 1002-41) for benzene, toluene, ethylbenzene, xylenes, and benzo(a)pyrene will not apply to certain oil and gas producing formations within the specified areas. However, to provide some protection of the potential future use of water resources in the specified area, the Commission's action provides that the statewide standard for radionuclides, as well as the statewide organic chemical standards (other than those for benzene, toluene, ethylbenzene, xylenes, and benzo(a) pyrene) will continue to apply to this ground water.
PARTIES TO THE RULEMAKING HEARING
5 CCR 1002-42.25