After petitioner tested positive for drugs for a third time, respondent properly accepted petitioner's resignation from his position as a sanitation worker pursuant to a last chance agreement that he had signed at a prior disciplinary proceeding, and that had provided for automatic resignation upon any subsequent positive test. In the agreement, petitioner, in lieu of termination, knowingly relinquished the right to appeal or otherwise challenge the test results or testing procedures ( see Montiel v. Kiley, 147 AD2d 402). In any event, petitioner's chain of custody argument concerning his drug test is without merit.