HYDRO31424 - Laserfiche WebLink

Home Browse Search

Permit conditions may differ because the geological and hydrological conditions are not identical. In this case, one difference involves the requirement for the amount of casing set below the Dissolution Surface. The requirement for the minimum amount of casing between the Dissolution Surface and the top of the cavity at Yankee Gulch Lease is ] 50 feet while the minimum amount of casing between the Dissolution Surface and the top of the cavity at the Rock School Lease is 200 feet because the non-productive interval between the Dissolution Surface and the mining interval is larger at the Rock School Lease. Another difference is the maximum injection pressure (700 psig for the Yankee Gulch Lease and 800 psig for the Rock School Lease), which differs between sites mainly because of the depth of the mining interval. A review of the overall construction requirements of the Rock School Lease Draft Permit indicates they are similar to those in the recently issued Yankee Gulch Lease Permit. The Rock School Lease Permit requires that the production casing be cemented to the surface as does the Yankee Gulch Permit. The Yankee Gulch Permit and the Rock School Lease Draft Permit both required that a cement bond or cement evaluation tool be run to ensure that adequate cement is behind the casing to prevent fluid movement out of the cavities. Based on recent experience, however, the language in the Rock School Lease Final Permit has been modified slightly to require that a cement bond log and/or a cement evaluation log be run in the production and injection casings. This broader flexibility will ensure that the logging results provide sufficient information to evaluate the cement placement, bonding to the casing and strength. Depending on the type of cement utilized and the configuration of the casing, it maybe necessary to run both logs. In addition, the casing must be pressure tested prior to commencement of injection, and a temperature, noise or radioactive tracer survey must be run after at least 60 days of operation, as also required by the Yankee Gulch Lease Permit. A review of the operating requirements in the Draft Permit indicate that the requirements are consistent with those in other previously issued Class III sodium extraction permits. As a result of the review, however, the section covering information required prior to injection was modified to clarify the list of specific data and logs that must be submitted to obtain authorization to inject. A review of the ground-water monitoring program in the Rock School Lease Draft Permit reveals some differences from that issued for other sites such as Yankee Gulch. These differences are primarily due to the smaller scale of the initial stage of injection activity authorized by this Permit which includes only three cavities. The Rock School Lease Draft Permit requires at least five quarters of monitoring (on a monthly basis), as was required by the Yankee Gulch Lease. Although the water quality sampling requirements are similar to those at other sites, there are some differences which were approved by the various regulatory agencies as a result of a review of the Regional water quality data in the vicinity. The operator is analyzing a shorter list of constituents than at the Yankee Gulch Lease on a monthly basis, but a comprehensive analysis is required once a quarter for the baseline period. Ground-water monitoring will continue after baseline monitoring is complete. As a result of this review, minor changes have been made in the Permit to clarify requirements for monitoring the dissolution surface during the baseline period (monthly monitoring for the short list of constituents and quarterly monitoring for the long list)