Atlantic Richfield Co. has agreed to pay $45.8 million to the state of California to resolve the state's charges that the company failed to replace or upgrade leaking underground storage tanks (USTs) at ARCO service stations throughout the state. The $45.8 million includes $25 million in penalties and another $20.8 million in expenditures for service-station upgrades that are not required by law, according to the California Environmental Protection Agency.