ON APRIL 10, 1992 EPA RECEIVED ARCO'S RESPONSE TO THE INFORMATION REQUEST. THE RESPONSE INDICATED THAT ARCO PREVIOUSLY INSTALLED A CEMS AT THE REFINERY TO MEASURE H2S IN THE FUEL GAS, HOWEVER, THE ANALYZER DID NOT MEET THE REQUIREMENTS IN 40 CFR. IN 1992, ARCO MODIFIED THE CEMS TO MEET THE REQUIREMENTS OF THE NEW SOURCE PERFORMANCE STANDARDS.