“(a) The Administrator of the Environmental Protection Agency (hereinafter referred to as the ‘Administrator’) shall increase the number of criminal investigators assigned to the Office of Criminal Investigations by such numbers as may be necessary to assure that the number of criminal investigators assigned to the office—“(1) for the period October 1, 1991, through September 30, 1992, is not less than 72;
“(2) for the period October 1, 1992, through September 30, 1993, is not less than 110;
“(3) for the period October 1, 1993, through September 30, 1994, is not less than 123;
“(4) for the period October 1, 1994, through September 30, 1995, is not less than 160;
“(5) beginning October 1, 1995, is not less than 200.
“(b) For fiscal year 1991 and in each of the following 4 fiscal years, the Administrator shall, during each such fiscal year, provide increasing numbers of additional support staff to the Office of Criminal Investigations.
“(c) The head of the Office of Criminal Investigations shall be a position in the competitive service as defined in 2102 of title 5 U.S.C. or a career reserve [reserved] position as defined in 3132(A) [3132(a)] of title 5 U.S.C. and the head of such office shall report directly, without intervening review or approval, to the Assistant Administrator for Enforcement.