340-150-0450 Automatic Tank Gauging Release Detection Method (1) An owner and permittee using equipment for automatic tank gauging (ATG) that tests for the loss of a regulated substance and conducts inventory control as a release detection method must use equipment that meets the requirements of this rule. The ATG system must: (a) Be able to detect a 0.2 gallon per hour leak rate with a probability of detection of at least 95 percent and a probability of false alarm of no more than 5 percent for all portions of the UST that routinely contain a regulated substance; and (b) The ATG system must be an approved leak detection method or equipment as listed by a national organization (e.g., the National Work Group on Leak Detection). (2) For USTs, an owner and permittee must monitor and test for releases at least once every 30 days and record the results for each month. (3) For underground piping, an owner and permittee must monitor and test for releases if the ATG system is designed to detect a release from any portion of the underground piping that routinely contains a regulated substance and record the results for each month as follows: (a) Daily for pressurized piping. (b) Once every 30 days for suction piping. (4) An owner and permittee must: (a) Report to DEQ any leak test results indicating the possibility of a release (i.e., test failure) within 24 hours as a suspected release (OAR 340-150-0500) and immediately begin investigation under OAR 340-150-0510; and (b) Immediately investigate all larger-than-normal or reoccurring variations in results, including widely fluctuating water levels in the tank and report such variations as a suspected release if the variation cannot be accounted for, without waiting to obtain a second month of data. (5) An owner and permittee must retain at a minimum the most current 12 consecutive months of release detection records. (6) ATG systems installed before December 22, 1990, are exempt from the leak rate quantities, probability limits and third party evaluation requirements of this rule, except: (a) The ATG system must be able to detect a 0.2 gallon per hour leak rate from any portion of the UST that routinely contains a regulated substance; and (b) The ATG equipment must meet the inventory control (or other test of equivalent performance) requirements of 340-150-0430 and the test must be performed with the system operating in one of the following modes: (A) In-tank static testing conducted at least once every 30 days; or (B) Continuous in-tank leak detection operating on an uninterrupted basis or operating within a process that allows the system to gather incremental measurements to determine the leak status of the tank at least once every 30 days. (c) An owner and permittee may only use the ATG system to obtain daily regulated substance volumes for the inventory control release detection method (OAR 340-150-0430) if the ATG does not meet the requirements of section (1) of this rule. Statutory/Other Authority: 466.994, 466.995 & ORS 466.706 - 466.835 Statutes/Other Implemented: ORS 466.746 & 466.765 History: DEQ 188-2018, amend filed 05/14/2018, effective 06/01/2018 DEQ 3-2008, f. 2-29-08, cert. ef. 3-10-08 DEQ 6-2003, f. & cert. ef. 2-14-03