energy pipeline and related properties, uses Marathon Oil Company (Marathon) to manage its operations in Casper, Wyoming. In 1994, Marathon entered into a service contract with Steel Structures, Inc. (SSI). The purpose of the contract was not to specify actual work SSI would perform for Marathon, but rather to establish a contractual relationship between the two companies for any work SSI might perform at Marathon's request. One of the terms of the contract required SSI to have insurance that would indemnify Platte or Marathon for any liability arising from SSI's work performed on Platte's and Marathon's behalf.
During the summer of 1996, Marathon asked SSI to hire Justis Berg, a high school student looking for seasonal employment between his junior and senior year. Under this scheme, Mr. Berg wouldappear on SSI's employment books, but Marathon would reimburse SSI for all employment costs under the service contract, including wages and workers compensation premiums. However, Marathon would be responsible for Berg's training and for any equipment he would operate. All of Berg's work would be under Marathon's supervision.
On June 28, 1996, Justis Berg was severely injured when the mowing tractor he was driving overturned. As a result of the accident, Berg eventually lost a leg.
On the day of the accident, defendant Maryland Casualty Co. (Maryland) insured SSI. This insurance included a Commercial General Liability (CGL) policy augmented with a Supplemental Employer's Liability coverage. In addition to its own coverage under the policy, SSI had asked for and had received endorsements, which included both Platte and Marathon as additional