b) A representative sample of leachate extracted from the waste by a laboratory procedure may be used to model the expected constituents and concentrations of the leachate. The laboratory test shall meet the following standards:

1. 1) The procedure shall be designed to closely reproduce expected field conditions; and
2. 2) The test shall utilize an extraction fluid representative of the physical and chemical characteristics of the liquid expected to infiltrate through the waste.

c) Actual samples of leachate from an existing solid waste disposal unit or a test fill may be utilized under the following conditions:

1. 1) The waste in the existing unit is similar to the waste expected to be disposed;
2. 2) The conditions under which the leachate was formed are similar to those expected to be encountered; and
3. 3) Leachate is sampled so as to be representative of undiluted and unattenuated leachate emanating from the unit.