Ill. Admin. Code tit. 83, § 535.200 – Work Performed on Regulators and Manometers

a) Prior to performing work at a customer location on a mercury-containing regulator or manometer used in providing natural gas service, a public utility shall test the air for mercury vapor in at least two locations: one location one foot above or away from the regulator or manometer and another location within three to five feet above the floor for indoor meters, or three to five feet above ground level for outdoor meters, immediately adjacent to the regulator or manometer.
b) After performing the work on a mercury-containing regulator or manometer used to provide natural gas service, a public utility shall test the air for mercury vapor at the same locations used for air sampling prior to performing the work on the regulator or manometer.
c) A public utility shall consider a confirmed reading at, or in excess, of the following levels as a positive indication of mercury.
1. 1) 0.003 milligrams (3 micrograms) per cubic meter of air for mercury vapor air sample tests conducted inside of a residential customer location.
2. 2) 0.010 milligrams (10 micrograms) per cubic meter of air for mercury vapor air sample tests conducted at non-residential locations and outside of a residential customer location.
d) When testing for mercury vapor, a public utility shall use mercury vapor testing equipment capable of detecting the presence of mercury at the levels required by subsection (c).
e) A public utility shall use mercury vapor testing equipment in accordance with the guidelines set forth by the manufacturer of the equipment.
f) A public utility shall not perform any mercury vapor air sample tests under conditions that would counter the manufacturer’s recommendations for use of the mercury vapor test equipment except for the following reasons:
1. 1) A public utility may perform work on mercury-containing regulators or manometers located outdoors without conducting the required mercury vapor test if conditions are not suitable for accurate readings from its mercury vapor test equipment, but shall return to the work site and test for mercury vapor as soon as conditions are favorable for accurate readings from its mercury vapor test equipment; or
2. 2) In an emergency, as defined in Section 535.10, a public utility may perform work on mercury-containing regulators or manometers without conducting the required mercury vapor test, if conditions are not suitable for accurate readings from its mercury vapor test equipment, but shall return to the work site and test for mercury vapor as soon as conditions are favorable for accurate readings from its mercury vapor test equipment.