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4.3.4 Geotechnic:al Program <br />• <br />Sonar surveys were taken of the cavity from Recovery well 88-1 on 1/20/92 and <br />12/3/92. Results of the survey tend to confirm that the cavity is being mined <br />uniformly, though not in the profile previously predicted. The sonar survey shows <br />the lower section of the mineable Boies Bed mining faster than predicted. In <br />addition, the insolubles being formed on the floor of the cavity are of a much <br />greater bulking factor than anticipated, probably due to the honeycomb nature of <br />the oil shales within the Boies Bed. To date, the size of the cavity has remained <br />within the dimensions necessary to maintain roof stability, prevent pillar failure and <br />protect the aquifers and oil shale beds above the mining zone. <br />4.3.5 Lease Modit'ication/Land Exchange <br />In the Spring of 1992, the project met with the BLM State Office to initiate <br />assignment or transfer of the four Sodium Leases from NaTec to WRNM. In July, <br />NaTec formally requested transfer of the leases. Bonding transfer was complete in <br />October. After lengthy negotiations netween NaTec and NACC, the joint venture <br />agreement was completed November 20, 1992. NaTec sold 50°!0 of the project to <br />North American Chemical Co. (NACC) and NACC became the operator (WRNM). <br />The effective date for transfer was retroactive to the first of the month, November <br />1, 1992. WRNM is responsible for all Lease obligations including rent and <br />royalties. <br />In December, the BLM approved a sodium unit agreement for all four leases to be <br />managed as one mining unit identified as Wolf Ridge Mining Unit. Lease rental and <br />production royalties were not effected, but minimum annual production and <br /> <br />28 <br />