THIS IS A RESPONSE ACTION AGAINST THE RESPONDENTS UNDER SECTION 106(A) OF CERCLA, ORDER RESPONDENTS TO PERFORM RI/FS AT THE MARTIN MARIETTA DENVER AEROSPACE WATERTON FACILITY. EPA HAS DETERMINED THAT THE ACTUAL OR THREATENED RELEASE OF HAZARDOUS SUBSTANCES AND HAZARDOUS WASTES AND CONSTITUENTS FROM THE FACILITY MAY PRESENT AN IMMINENT AND SUBSTANTIAL ENDANGERMENT TO THE PUBLIC HEALTH OR THE EN- VIRONMENT.