C.M.R. 06, 096, ch. 691, app 096-691-A
1. For Galvanic Cathodic Protection Systems
A. All measurements must be made by placing a saturated copper/copper sulfate reference electrode in direct contact with the soil electrolyte.
B. The copper/copper sulfate electrode must be placed over the center line of each tank and within 1 foot of each piping run. For single-walled tanks a minimum of three (3) measurements are to be made over the center line of each tank, one at each end and one at the tank's midpoint. For double-walled tanks, a minimum of one voltage measurement over each tank's midpoint is required.
C. All measurements must be recorded using a direct current voltage measuring device with a minimum of 10 megohms input impedance, accurate to at least + 1 percentat 1 volt.
D. A measurement of at least negative 0.85 volts must be recorded for each test location and each metallic facility component, including tanks, piping, and connectors that are cathodically protected.
E. When a negative voltage of at least 0.85 volts is not achieved upon installation of the tank or piping, the measurement must be repeated within 6 months. Upon failing to achieve a negative voltage of at least negative 0.85 volts after the 6-month period, the tank owner shall comply with paragraph F, below.
F. The tank owner shall repair or replace the system in accordance with the recommendations of the National Association of Corrosion Engineers, Standard Practice 0285-or STI Recommended Practice for the Addition of Supplemental Anodes to STI-P3® USTs, R972 and section 5(D)(14) of this Chapter whenever the system does not register a negative voltage reading of at least 0.85 volts for each tank or piping run within six (6) months of the first failed measurement, or properly abandon in accordance with section 11, except as provided for in paragraph E for a new installation.
G. The frequency of cathodic protection monitoring must be consistent with the requirements outlined in section 5(D)(3) and (4).
H. A cathodically protected steel tank or piping that continues to fail to achieve the minimum level of adequate corrosion protection of at least 0.85 volts within six (6) months of repair or replacement in accordance with paragraph F shall be properly abandoned in accordance with section 11.
2. For Impressed Current or Galvanic Cathodic Protection Systems
Test methods and criteria as described in the NACE TM 0101, Measurement Techniques Related to Criteria for Cathodic Protection on Underground or Submerged Metallic Tank Systems, or TM 0497, Measurement Techniques Related to Criteria for Cathodic Protection on Underground or Submerged Metallic Piping Systems, are to be used to monitor impressed current systems. These methods for testing galvanic systems may be used with prior written approval of the Commissioner.
NOTE: Structure to soil potentials measured when the soil is frozen may be inaccurate because of the increased resistance of the soil electrolyte. Cathodic protection monitoring schedules should be planned to avoid frozen soil conditions.
C.M.R. 06, 096, ch. 691, app 096-691-A