Section 175.510  Corrosion Protection

In all situations, no matter which method is used to assess the integrity of the tank prior to addition of cathodic protection, the cathodic protection system being field installed in Illinois must be designed by a corrosion expert who is NACE certified in cathodic protection design or by a Licensed Professional Engineer with the state who has certification or licensing that includes education and experience in corrosion control of buried or submerged metal piping systems and metal tanks.  Those contractors installing the cathodic protection systems in Illinois must be licensed as cathodic protection installers. These contractors must successfully pass the International Code Council (ICC) certification exam module for cathodic protection. An installation/retrofitting ICC certified contractor may install wristband anodes or spike anodes on a flex connector without having a cathodic protection ICC certification.  

a)         Cathodic Protection. A tank may be upgraded by cathodic protection if the cathodic protection system meets the requirements of 41 Ill. Adm. Code 174 through 176, and the integrity of the tank is ensured using one of the following methods:

1)         To be suitable for upgrading by cathodic protection, the integrity of the tank must be ensured by one of the following methods:

A)        For tanks installed for less than 10 years, the following requirements apply:

i)          The tank is internally inspected and assessed to ensure that the tank is structurally sound and free of corrosion holes prior to installing the cathodic protection system;

ii)         The tank is monitored monthly for releases using a permanent method of leak detection as approved by OSFM. Monthly inventory control, manual tank gauging and Statistical Inventory Reconciliation (SIR) do not meet this requirement;

iii)        Two tank precision tests must be conducted that meet the requirements of OSFM precision tank tightness testing. The first precision test shall be conducted prior to the installation of the cathodic protection system. The second precision test shall be conducted between 3 and 6 months following the first operation of the installed cathodic protection system. Both tests must indicate tightness of the tanks;

iv)        Use of alternative methods approved by OSFM. These acceptable alternative methods are indicated in subsection (a)(1)(B) for tanks that are over 10 years old.

B)        For tanks installed for more than 10 years, the following methods apply:

i)          An invasive inspection method that ensures the tank is internally inspected and assessed to ensure that the tank is structurally sound and free of corrosion holes prior to installing the cathodic system. The internal inspection procedures shall follow the requirements of NLPA 631.

ii)         An invasive remote video camera test is conducted prior to the installation of the cathodic protection system. The video system must be capable of recording a video survey of the interior surface of the tank with a suitable lighting source.

iii)        A non-invasive tank life/corrosion model test is conducted to examine the soil environment in the immediate vicinity of the tank and the relationship of the metal UST to this environment. A statistical model is used to assess the relationship between the aggressiveness of the environment and the rate of corrosion and to predict the remaining life of the UST prior to corrosion failure. An example of a noninvasive test method is Mean Time to Corrosion Failure (MTCF).

iv)        The tanks are assessed for corrosion holes by other methods determined by OSFM, to prevent releases in a manner that is no less protective of human health and the environment than subsections (a)(1)(B)(i), (ii) and (iii).

2)         OSFM requires a tank integrity assessment even if both cathodic protection and interior lining systems are being installed. If the cathodic protection and interior lining are installed at the same time, only one approved integrity assessment is required. Even if both systems have been installed, OSFM requires routine inspection and maintenance of both systems to continue.

3)         If one of the non-invasive methods described in this Section has been used to assess tank integrity of a tank older than 10 years, the leak detection method used on these tanks after installing the cathodic protection system may not be the monthly inventory control method, SIR, or manual tank gauging method of leak detection. Acceptable leak detection methods that can be used are as follows: automatic tank gauging, vapor monitoring, groundwater monitoring, interstitial monitoring, fiber optics or tracer elements.

4)         USTs equipped with both interior lining and cathodic protection (sacrificial anodes or impressed current).

A)        The following maintenance procedures shall apply:

i)          Sacrificial anodes must be tested according to the requirements of subsection (f).  

ii)         Impressed current records of operation must be recorded every 30 days and records kept on site for 2 years. The system must be tested annually and records kept on site for 3 years.

iii)        As of September 1, 2010, some facilities may exist that had been previously granted an OSFM waiver for the UST lining maintenance requirements based upon original field notes from the initial lining, of an invasive method of initial tank integrity assessment verifying that there were no holes in the tank. For these systems, only the external cathodic protection system must be maintained and tested.

B)        For those USTs where a non-invasive tank integrity assessment method was used or if there were any holes present in the tank, regular interior lining inspections must continue as described in Section 175.500.

b)         ACT-100 Tanks Installed with Sacrificial Anodes.  Owners of ACT-100 tanks meeting STI F894.01, incorporated by reference in 41 Ill. Adm. Code 174.210, and able to produce ACT-100 warranty papers may choose the steel-FRP composite design as a sole method of corrosion protection instead of maintaining the sacrificial anodes.

c)         Upgrades to Combine Internal Lining with Cathodic Protection. For all permit applications received prior to January 1, 2011, a tank may be upgraded by both internal lining and cathodic protection if:

1)         The lining is installed in accordance with the requirements of Section 175.500; and

2)         The cathodic protection system meets the requirements of Section 175.400(b)(2)(B) and 175.510.

d)         Piping Corrosion Protection Requirements. All UST metal product piping that is in contact with backfill, ground or water shall be cathodically protected. All metal risers, vents and fills in contact with backfill, ground or water shall be dielectrically coated. Shrink-wrap or boots are not acceptable as a form of cathodic protection in a water environment.

e)         Wiring of all associated electrical equipment shall conform to the requirements of Section 175.425 and shall also conform to the following requirements:

1)         All wiring that is connected to any anode of an impressed current system shall be no less than No. 10 stranded, with jacketing that is suitable for direct burial and that is petroleum or hazard resistant for the product conveyed. Such jacketing is to have a thickness sufficient to cause the wiring to have a diameter of at least ⁵/₁₆ inch. Systems existing prior to May 1, 2003 may remain.

2)         All wiring connected to any anode of a sacrificial anode system shall be suitable for direct burial and shall be resistant to petroleum and/or hazardous substances.

3)         All structural lead wiring of any cathodic protection system shall be suitable for direct burial and shall be petroleum and/or hazard resistant.

4)         For installation of cathodic protection systems to facilities existing prior to May 1, 2003, anode wiring may be placed into pavement saw-cuts, provided that the following conditions are met:

A)        No part of the wiring is less than one inch below the finished pavement surface, and provided that the portion of the saw-cut groove above the wiring is filled with a combination of at least ⅜ inch of backerod and at least ½ inch of self-leveling caulk suitable as a concrete filler.

B)        Structure lead wiring of impressed current systems shall consist of at least 2 separate leads. Such leads running from the junction box or rectifier to the UST structures must be in separate saw-cuts, jumpering from one UST structure to the next. One lead shall connect to the first structure to be protected and continue on to all structures in the UST. The second lead will connect to the last structure to be protected. Such loop is to ensure that if one lead were to become cut or disconnected, the other lead would ensure the continued connection of the UST  structures and the junction box or rectifier.

C)        All wiring from anodes shall terminate and be identified (as to location per approved site plan), in strategically located junction boxes, placed in and around the protected field. This will facilitate the testing of each anode.

5)         Beginning May 1, 2003 for installation of cathodic protection systems, all wiring running outside of manholes or sumps shall be located at least 12 inches below the finished grade and installed in conduit approved for petroleum and/or hazardous installations.

f)         Operation and Maintenance of Cathodic Protection. Owners or operators of steel USTs with corrosion protection shall comply with the following requirements to ensure that releases due to corrosion are prevented for as long as the UST is used to store regulated substances:

1)         All corrosion protection systems shall be operated and maintained to continuously provide corrosion protection to the metal components of that portion of the tank and piping that routinely contain regulated substances and are in contact with the ground, backfill or water. STI-P3 tanks are to be tested every 3 years for proper corrosion protection operation.

2)         All USTs equipped with sacrificial anode or impressed current cathodic protection systems shall be tested and inspected for proper operation, when being put into operation, by a contractor that has successfully passed the International Code Council (ICC) certification exam module for cathodic protection. Such testing shall be in accordance with the following requirements:

A)        Frequency. All cathodic protection systems shall be re-tested no less than 24 weeks and no more than 28 weeks from the date of installation or repairs. All sacrificial anode systems shall be tested every 3 years by a tester that meets the qualifications of this subsection (f)(2). In the event that a reading of -875 millivolts or less is recorded with testing being conducted above the structure, on any type of corrosion protection system, then annual testing will be required thereafter. In the event that upgrading of the cathodic protection system results with readings greater than -875 millivolts with readings being conducted above the structure, then testing may be conducted every 3 years, unless the 6 month test after upgrading produces a reading of -875 millivolts or less, then annual testing will be required.

B)        Inspection Criteria. The criteria that are used to determine that cathodic protection is adequate as required by this subsection (f)(2)(B) shall be in accordance with NACE RP0285 and SP0169, incorporated by reference in 41 Ill. Adm. Code 174.210. Subject to the technical applicability of these criteria given actual site conditions, one or more of the following criteria shall apply for adequacy of cathodic protection.  Cathodic protection shall be repaired or replaced if it fails to meet the standards provided in this subsection (f)(2)(B).

i)          A negative (cathodic) potential of at least 850 millivolts with cathodic protection applied. This potential is measured with respect to a saturated copper/copper sulfate reference electrode contacting the electrolyte.

ii)         A minimum 100 millivolt of cathodic polarization between the structure and a saturated copper/copper sulfate reference electrode contacting the electrolyte. Such polarization shall be determined from the taking of a valid "instant-off" test, that, for each testing point, determines the voltage reading at the second drop in voltage following the interruption in cathodic protection being applied, and determines if the voltage reading is at least 100 millivolts higher than either the native reading or any other reading after the structure has had time to depolarize with no cathodic protection applied.

3)         USTs with impressed current cathodic protection systems shall also be tested and inspected, prior to being put into operation and every 30 days thereafter, to ensure the equipment is running properly and the entire system must be tested annually by a cathodic protection tester certified under the requirements of 41 Ill. Adm. Code 172.

4)         For USTs using cathodic protection, records of the operation of the cathodic protection shall be maintained to demonstrate compliance with the performance standards in this Section. These records shall provide the following:

A)        The results of testing for sacrificial anode systems, the 6-month test and annual tests must be maintained on site for 2 years;

B)        All records from the last 2 cathodic protection total system tests by a qualified cathodic protection tester pursuant to a 3-year cycle must be maintained on site; and

C)        Impressed current systems must be inspected every 30 days and reports or a log maintained that shows date of inspection, initials of inspector, hour, volt and amp readings, and power on verification. A minimum of 2 years of records shall be kept on site. Also, a certified corrosion protection contractor must check the total system annually after the date of installation and results shall be kept on site for 2 years.

5)         Alternative methods of corrosion protection may be used if approved in writing by OSFM, provided they are no less protective of human health or the environment.