1. a) Twelve grab samples, each 550 milliliters in size, must be taken from the end-product compost at the facility, in the following manner:

   1. 1) Four grab samples from points both equidistant throughout the length and at the center of the windrow or other pile, at a depth not less than one meter from the surface of the windrow or other pile;
   2. 2) Four grab samples from points both equidistant throughout the length and one quarter the width of the windrow or other pile, at a depth not less than half the distance between the surface and the bottom of the windrow or other pile; and
   3. 3) Four grab samples from points both equidistant throughout the length and one eighth the width of the windrow or other pile, at a depth not less than half the distance between the surface and the bottom of the windrow or other pile.
   4. 4) The twelve grab samples must be thoroughly mixed to form a homogenous composite sample. Analyses must be of a representative subsample. The sample holding times, sample container types and minimum collection volumes listed in Section 830.Table B shall apply; or
2. b) Sampling methods set forth in Test Methods for Evaluating Solid Waste, Physical/Chemical Methods (SW-846), incorporated by reference at 35 Ill. Adm. Code 830.103.

Sample collection, preservation, and analysis must be done in a manner which assures valid and representative results. A composite sample must be prepared by one of the following methods: