THIS IS A RESPONSE ACTION AGAINST THE RESPONDENTS UNDER SECTION 106(A) OF CERCLA, ORDER THE RESPONDENTS TO PLAN, IMPLEMENT, PERFORM, AND ALL ACTIONS NECESSARY TO PROTECT PUBLIC HEALTH AND WELFARE AND THE ENVIRONMENT. EPA HAS DETERMINED THAT THE ACTUAL OR THREATENED RELEASE OF HAZARDOUS SUBSTANCES FROM THE YAK TUNNEL MAY PRESENT AN IMMINENT AND SUBSTANTIAL ENDANGERMENT.