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 › Appendix 11-5-2-280.1-F

Current through June 25, 2024
STRUCTURE-TO-SOIL TEST PROCEDURE FOR GALVANIC
							 CATHODIC PROTECTION SYSTEMS
1. Place voltmeter on 2 volt DC scale.
2. Connect voltmeter negative lead to reference
							 electrode.
3. Place reference electrode in clean soil directly
							 over the structure that is being tested to obtain local potential. At least one
							 local potential is required for each tank - the preferred test point is at the
							 approximate midpoint along the centerline of the tank. Piping may require
							 measurement at each end of the pipe and at the middle depending upon anode
							 configuration (see Section 6.10.2 of MDEQ guidance document).
* The reference electrode may not be placed on
							 concrete or other paving materials.
* Ensure that the reference electrode is placed in a
							 vertical position (tip down).
* Ensure that the soil where the reference electrode
							 is placed is moist - add tap water if necessary.
* Ensure that the soil where the reference electrode
							 is placed is not contaminated with hydrocarbons.
* Ensure that the reference electrode window is not
							 exposed to direct sunlight.
4. Connect voltmeter positive lead to structure that
							 is to be tested.
* If a test lead wire is utilized to make contact with
							 the tested structure you must ensure that continuity exists between the test
							 lead wire and the structure. This may be accomplished by conducting a
							 point-to-point continuity test as described in Appendix E.
* Ensure that good metal-to-metal contact is made
							 between the test lead clip/probe and the structure.
* Ensure that no corrosion exists where the test lead
							 makes contact with the structure.
* Ensure that your body does not come into contact
							 with the electrical connections.
* Ensure that test leads are not submerged in any
							 standing water.
* Ensure that test lead insulation is in good
							 condition.
* sti-P3* tanks
* If the test lead wire is not continuous or is not
							 present, contact with the inside bottom of the tank is necessary. This may be
							 accomplished by connecting the voltmeter lead wire to a test prod mounted onto
							 the bottom of a wooden gauging stick and lowering the stick into the tank fill
							 riser. Be sure that firm contact is made with the tank bottom. Care should be
							 taken to ensure that any drop tube that may be installed in the tank does not
							 prohibit contact with the tank bottom. If a metallic probe bar is utilized to
							 contact the tank bottom, ensure that the probe bar does not contact the fill
							 riser or any other metallic component of the UST system.
* If a sti-P3 tank is equipped
							 with a PP4 test station, the PP4 test station is disregarded and potentials
							 must be obtained with a portable reference electrode placed in the soil (both
							 local and remote) as described in Section 6.10.1 of the MDEQ guidance document.
5. Obtain voltage and record in the local column on
							 the MDEQ galvanic survey form.
6. Place reference electrode in clean soil remote from
							 the protected structure. (Refer to Section 6.10.3 for a discussion of remote
							 reference electrode placement.)
7. Obtain voltage and record in the remote column on
							 the MDEQ galvanic cathodic protection form. (Note: if the fixed cell-moving
							 ground method was used to conduct continuity survey, the potential obtained
							 during the continuity survey for each corresponding structure may be transposed
							 to the appropriate column.)
Data Interpretation
(for a more complete
							 discussion refer to Appendix C of this guidance document)
* If both the local and the remote potential are -850
							 mV or more negative, the 850 on criterion is satisfied and it is judged that
							 adequate cathodic protection has been provided.
* If either the local or the remote potential is more
							 positive than -850 mV the test result is inconclusive and further testing
							 and/or repairs are necessary. Alternatively, a person qualified as a corrosion
							 expert could evaluate/conduct the survey and declare a pass or fail based on
							 their interpretation and professional judgement.