Mississippi Administrative Code › Title 11 - Mississippi Department of Environmental Quality › Part 5 - Underground Storage Tank Regulations › Chapter 2 - Mississippi Commission on Environmental Quality Underground Storage Tanks Regulations Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks (UST) (Adopted March 22, 1989; Amended August 25, 2011, Last Amended August 23, 2018) › Appendix 11-5-2-280.1 - GUIDELINES FOR THE EVALUATION OF UNDERGROUND STORAGE TANK CATHODIC PROTECTION SYSTEMS › Section 11-5-2-280.1-6 - CATHODIC PROTECTION TESTING › Section 11-5-2-280.1-6.8 - Reference Electrode Placement › Section 11-5-2-280.1-6.8.3 - Remote Placement

Current through June 25, 2024
The remote potential represents the average potential
						  of the entire surface of the protected structure. The purpose of remote
						  placement is to eliminate any effect that raised earth may be contributing to
						  the measurement of the structure-to-soil potential and to overcome any effects
						  shielding may have.
Placement of the reference electrode is considered
						  remote when it is placed in the soil a certain distance away from the structure
						  that is being tested. There are several different factors that determine the
						  distance necessary in order to reach remote earth and a full discussion is
						  beyond the scope of this document. However, a remote condition can normally be
						  achieved when the reference electrode is placed between 25 and 100 feet away
						  from any protected structure. Depending on the conditions specific to the
						  particular location where the cathodically protected structure is, the minimum
						  distance to remote earth may be considerably more than 25 feet. Therefore, it
						  is important that you establish that the reference electrode is truly remote
						  when obtaining a structure-to-soil potential. In order to ensure that remote
						  earth has been achieved, place the reference electrode at least 25 feet away
						  from the protected structure and observe the potential. Move the reference
						  electrode out away from the protected structure another 10 feet or so and
						  observe the potential. If there is no significant difference in the two
						  potentials, it can be assumed that remote earth has been achieved. If there is
						  a significant difference, continue moving the reference electrode out away from
						  the protected structure until no significant difference is observed.
When selecting a location to place the reference
						  electrode to establish remote earth, it is essential that there are no other
						  cathodically protected structures (e.g. natural gas lines) in proximity to the
						  reference electrode. Foreign cathodically protected structures can cause an
						  abnormally high (more negative) potential that is not indicative of the remote
						  potential of the structure you are measuring. It is also important that there
						  are no other buried metallic structures in the vicinity of the reference
						  electrode. Any metallic structure that is buried near the reference electrode
						  could possible affect the structure-to-soil potential that is observed on the
						  protected structure. In addition to the above considerations, you should
						  attempt to select the remote placement such that the reference electrode can
						  "see" the structure you are testing. This means that there should not be any
						  buried metallic structure between the remote reference electrode placement and
						  the protected structure. If you suspect that shielding may be affecting the
						  observed potential, place the reference electrode away from the protected
						  structure in a different direction.