ATCP 93.520(2)(b)4.4. After an inspection under this paragraph, if the tank is not closed under subd. 3. a., a precision tightness test shall be performed on the tank system in accordance with s. ATCP 93.515 (4). In addition, a tightness test shall be performed on the ullage portion of the tank in accordance with s. ATCP 93.515 (10). ATCP 93.520(3)(a)1.1. Equipment for impressed current systems shall be served by a dedicated and clearly marked electrical circuit that remains energized at all times. ATCP 93.520(3)(a)2.2. All new and existing impressed current systems shall maintain either of the following standard protection levels: ATCP 93.520(3)(a)2.b.b. A 100 millivolt or greater negative shift in polarization between the instant-off reading and the native soil reading or a 100 millivolt or greater positive shift in the depolarized structure potential from the instant-off reading. ATCP 93.520(3)(a)3.3. When a new impressed current system is installed or an existing system is replaced in whole or in part, an ammeter shall be installed, along with an hour meter that totals the number of hours during which electric current flows through the system. ATCP 93.520(3)(b)(b) Failing impressed current systems. If impressed current corrosion protection readings taken in accordance with sub. (1) (d) 2. indicate the system is not maintaining adequate continuous protection, the system shall be analyzed by a certified corrosion expert for site corrosion potential and qualification of system functionality. ATCP 93.520(3)(c)1.1. Impressed current systems that have been inoperative for 120 days or less shall comply with all of the following requirements: ATCP 93.520(3)(c)1.a.a. Power shall be restored and the system shall be tested by a certified cathodic protection tester for system functionality. ATCP 93.520(3)(c)1.b.b. If the impressed current system is damaged or inoperable, a certified corrosion expert shall repair, survey, and recommission the system. ATCP 93.520(3)(c)2.2. Impressed current systems that have been inoperative for 121 to 180 days shall comply with all of the following requirements: ATCP 93.520(3)(c)2.b.b. Power shall be restored and the system shall be tested for system functionality by a certified cathodic protection tester. ATCP 93.520(3)(c)2.c.c. If the impressed current system is damaged or inoperable, a certified corrosion expert shall repair, survey, and recommission the system. ATCP 93.520(3)(c)3.3. Impressed current systems that have been inoperative for 181 to 365 days shall comply with all of the following requirements: ATCP 93.520(3)(c)3.b.b. A certified corrosion expert shall assess, survey, and recommission the impressed current system and perform any necessary repairs. ATCP 93.520(3)(c)4.4. Impressed current systems that have been either inoperative or not tested for more than 365 days shall comply with all of the following requirements: ATCP 93.520(3)(c)4.b.b. If the tank fails the internal inspection, the tank owner shall either have the tank repaired and lined, or have the lining repaired in accordance with s. ATCP 93.530, or have the tank permanently closed and removed in accordance with s. ATCP 93.560. ATCP 93.520(3)(c)4.c.c. If the tank is not closed under subd. 4. b., a certified corrosion expert shall assess, survey, and re-commission the impressed current system and perform any necessary repairs. ATCP 93.520(3)(c)4.d.d. If the tank is not closed under subd. 4. b., a precision tightness test shall be performed on the tank system in accordance with s. ATCP 93.515 (4). In addition, a tightness test shall be performed on the ullage portion of the tank in accordance with s. ATCP 93.515 (10). ATCP 93.520 HistoryHistory: CR 17-092: cr. Register October 2019 No. 766, eff. 11-1-19; correction in (1) (d) 3. (intro.), (e) 3., (2) (b) 2., (3) (c) 4. c., d. made under s. 35.17, Stats., Register October 2019 No. 766. ATCP 93.530ATCP 93.530 Tank lining of underground storage tanks. ATCP 93.530(1)(a)(a) The installation of interior tank lining for underground storage tanks shall comply with API 1631 and this section.