ENVIRONMENTAL TECHNOLOGIES OF NEVADA, INC. ( ET ) BUILT AND BEGAN OPERAION OF A NOMETALLIC MINERAL PROCESSING PLANT IN APEX, CLARK COUNTY, NEVADA IN 1994. BY THIS REFERRAL, EPA SEEKS SOURCE PERFORMANCE STANDARDS AS WELL AS ET'S VIOLATION OF SECTION 15 AND 16 OF THE NEVADA CLARK COUNTY STATE IMPLEMENTATION PLAN.