24-hr composite definition
24-hr composite means a series of, at least, four individual samples collected over a 24-hour period at selected intervals based on an increment of either flow or time, and combined into a single container to be subsequently analyzed as one sample.
24-hr composite sample means a flow-proportioned mixture of not less than eight discrete aliquots. Each aliquot shall be a grab sample of not less than 100 mL and shall be collected and stored in accordance with procedures prescribed in the most recent edition of Standard Methods for the Examination of Water and Wastewater.