a) Natural gas ("gas"), as defined in Section 1.07 of "AN ACT to provide for the use of gas transmission facilities by energy entities," (Ill. Rev. Stat. 1985, ch. 111 ⅔, par. 571.07) produced from wells in Illinois (including methane produced from the anaerobic decomposition of municipal refuse) for use in Illinois and to be transported by a gas public utility in Illinois must meet the following standards before the gas may be placed into the utility's gas system. These standards do not apply to contracts existing prior to the effective date of this Part.

1. 1) The gas shall be commercially free from dust, gum, gum forming constituents, and other solid and/or liquid matter.
2. 2) The gas shall contain not more than 5 pounds of water per one million standard cubic feet.
3. 3) The gas shall not contain products in amounts that will result in detrimental corrosion which would cause premature failure of pipe, equipment or customer appliances over the normal life span of the pipe, equipment, or appliances.
4. 4) The gas shall not contain more than .25 grain of hydrogen sulphide per 100 cubic feet and not more than 1 grain of total sulfur per 100 cubic feet.
5. 5) The gas shall not contain more than 3% by volume of carbon dioxide.
6. 6) The gas shall not contain more than .5% by volume of oxygen.
7. 7) The gas shall not contain more than 5 parts per million by volume of halogenated hydrocarbons at any time.
8. 8) The gas temperature shall be between the limits of 40° and 110° Fahrenheit when delivered to the utility for transportation.
9. 9) The gas shall not cause a reduction in the Btu content of the gas delivered to the utility's customers unless the blended gases delivered to the individual customers are fully compensated by a Btu correction factor stated in the utility's tariffs.
10. 10) The transported gas must be interchangeable with the utility's system gas so that the gas will burn in customers' equipment without any adjustments to the customers' equipment being required. Interchangeability will be determined in accordance with the American Gas Association's Research Bulletin 36, "Interchangeability of Other Fuel Gases with Natural Gases" (1952, Second Edition). No later amendment or edition is incorporated by this subsection.