Section 465.04 - Compliance date for PSES(a) For subparts A, B, and C the compliance date for Pretreatment Standards for Existing Source (PSES) is December 1, 1985.(b) For subpart D, the compliance date for Pretreatment Standards for Existing Sources will be as soon as possible, but in no case later than November 17, 1986.48 FR 52399, Nov. 17, 1983