C150073 Final Feasibility Study - Laserfiche WebLink

Home Browse Search

Feasibility Evaluation of the Arkansas Valley Pipeline Water Works! Committee June 2003 In general, the permitting process for Class I injection is rigorous and expensive and can reportedly approach $1 million for hazardous waste injection. Computer modeling is required for Class I wells to prove to EPA that the confining zone will not be breached by the injection fluid for 10,000 years. EPA recommends injection of waste into a formation that contains fluids with greater than 10,000 mg/L total dissolved solids (TDS). Formations with lower TDS levels are considered potential drinking water sources and injection into these formations would require an expensive exemption process. As discussed above, no Class I injection wells exist in the Lower Arkansas River Valley. Therefore, comparable cost information for drilling similar wells could not be obtained. However, information from other types of injection wells in other areas of Colorado was gathered and is discussed below. Cost Estimate for Developing an Underground Injection Well The lack of Class I underground injection wells in the Lower Arkansas River Valley makes cost estimation difficult. Cost estimates were obtained, however, for Class II injection wells from Mull Drilling Company, Wichita, Kansas. This firm has drilled several Class II injection wells in Kiowa County, Colorado. The following information was provided by Mr. Mark Shreve, President of Mull Drilling during a June 18, 2002 telephone conversation: The depth of the injection well and injection site (the formation into which the waste is to be injected) are dependent on the quality of the wastewater and the rate (gpm) of disposal. Using Las Animas' RO reject as an example (RO reject TDS = 6,000 mg/L, peak flows = I50 gpm), Mr. Shreve indicated that an injection well would need to be drilled into the Arbuckle formation. The Arbuckle Formation is a fractured dolomite formation approximately 5,500 feet beneath the surface in southeastern Colorado. This formation might be slightly shallower in the Lower Arkansas River Valley near Las Animas. The TDS levels in this formation are very high (magnitudes of 10,000 mg/L or more) and the fractured nature of this formation make it uniquely appropriate for high volumes of brine disposal. For Class II type wells, the permitting process for injection into this formation is relatively easy. In addition, this formation will accept this 150 gpm of wastewater under gravity, i.e. no pumping would be required. The cost of drilling and equipping a Class II injection well into the Arbuckle Formation is approximately $200,000 - $280,000. This cost is based on a well depth of 5,500 feet, with 8.5-9.5 inch casing with concrete grout surrounding the casing from the surface to a depth of 400 feet, and 5.5 inch casing from 400 to 5,500 feet. Concrete grout is also required at the bottom of the well, and through the Cheyenne and Dakota Formations, per State of Colorado 43 GEI Consultants, InC. 01284 03-06-30 Feasibility Evaluation Final