340-150-0440 Manual Tank Gauging Release Detection Method (1) An owner and permittee may use manual tank gauging as a release detection method for USTs that are less than 2,001 gallons in size. (a) For USTs of 550 gallons or less nominal capacity and USTs with a nominal capacity of 551 to 1,000 gallons that meet the tank diameter criteria in the table may use this as the sole method of release detection. (b) For USTs of 551 to 2,000 gallons in size, this method may be used instead of manual inventory control (OAR 340-150-0430). This method is allowed for a period of: (A) Ten years after the installation of the UST system; or (B) Ten years after the UST system achieved compliance with corrosion protection requirements; except (C) In no case may manual tank gauging be used as a primary release detection method after December 22, 2008. (c) After the period of use has expired as listed in paragraph (1)(b)(C) of this section, an owner and permittee of an UST between 551 and 2,000 gallons in size must use one of the release detection methods in OAR 340-150-0435 through 340-150-0470. (2) An owner and permittee must use the following procedures for the manual tank gauging release detection method: (a) Tank liquid level measurements must be taken at the beginning and ending of a minimum 36-hour test period, during which time no liquid (i.e., regulated substance) may be added to or removed from the UST; (b) Level measurements must be based on an average of two consecutive measuring stick or automatic tank gauge readings at both the beginning and ending of the period in which the UST is tested; and (c) The equipment used to measure the level of regulated substance in the UST (e.g., stick or automatic tank gauge) must be capable of measuring the level of the regulated substance over the full range of the UST's height to the nearest one-eighth of an inch. (3) An owner and permittee must monitor the UST system for releases at least weekly and record and reconcile the results of each week's readings for each month. (4) In addition to any other requirements of this rule, an owner and permittee must conduct tightness testing (OAR 340-150-0445) of USTs of 1,001 to 2,000 gallons in size at least once every five years. (5) An owner and permittee must report to DEQ any variation between beginning and ending measurements that exceeds either the weekly or monthly standards in the table in 340-150-0440(1)(a) within 24 hours as a suspected release (OAR 340-150-0500) and immediately begin investigation as 340-150-0510 specifies. (6) An owner and permittee must immediately investigate all larger-than-normal or reoccurring variations in results and report such variations to DEQ as a suspected release if the variation cannot be accounted for, without waiting to obtain a second week of data. (7) An owner and permittee must retain at a minimum the most current 12 consecutive months of release detection records and the last two tightness test results. [ED. NOTE: To view attachments referenced in rule text, click here to view rule.] Statutory/Other Authority: ORS 466.706 - 466.835, 466.994 & 466.995 Statutes/Other Implemented: ORS 466.746 & 466.765 History: DEQ 188-2018, amend filed 05/14/2018, effective 06/01/2018 DEQ 6-2003, f. & cert. ef. 2-14-03