Oregon Administrative Rules › Chapter 340 - DEPARTMENT OF ENVIRONMENTAL QUALITY › Division 150 - UNDERGROUND STORAGE TANK RULES › Section 340-150-0435 - Statistical Inventory Reconciliation Method of Release Detection

Current through Register Vol. 63, No. 7, July 1, 2024
(1) An owner and
			 permittee using statistical inventory reconciliation (SIR) as a release
			 detection method must meet the requirements of this rule. SIR cannot be used as
			 a release detection method for pressurized underground piping.
(2) The method must be capable of detecting a
			 least a 0.2 gallon per hour leak rate from any portion of the UST that
			 routinely contains a regulated substance with a probability of detection of at
			 least 95 percent and a probability of false alarm of no more than 5
			 percent.
(3) The SIR method used
			 must be an approved leak detection method that meets the requirements of
			 section (2) of this rule as listed by a national organization (e.g., the
			 National Work Group on Leak Detection).
(4) Daily inventory control regulated
			 substance measurements and data gathering must be performed in accordance with
			 OAR
			 340-150-0430(4)
			 through (9).
(5) An UST system must be monitored for
			 releases on a monthly basis when the SIR method is used. To meet the monthly
			 monitoring requirements, an owner and permittee must, within 22 days after each
			 calendar month or 30-day period, submit the daily inventory records to and
			 receive the SIR results back from the SIR vendor they have hired to perform the
			 statistical analysis. An owner and permittee must follow up with the SIR vendor
			 if there are delays and make any changes necessary to their service agreement
			 or contract to prevent late report submittals.
(6) The results of a SIR analysis that shows
			 a 0.2 gallon per hour or greater leak rate in any single month is considered to
			 be a release detection failure.
(7)
			 An owner and permittee must report to the department any single release
			 detection failure and any two inconclusive results (as reported by the SIR
			 vendor) obtained within a consecutive two-month period within 24 hours as a
			 suspected release (OAR
			 340-150-0500) and immediately begin investigation in accordance with
			 340-150-0510;
			 additionally,
(a) An owner and permittee must
			 investigate and attempt to remedy or repair the cause of inconclusive results;
			 and
(b) SIR must be discontinued as
			 the release detection method and immediately substituted with one of the
			 release detection methods listed in OAR
			 340-150-0450  through
			 340-150-0470  if:
(A) An owner and permittee is unable to
			 correct the cause of the inconclusive results after tank and piping tightness
			 testing results or other investigation methods confirm that the UST system is
			 not leaking; and
(B) More than four
			 inconclusive results are recorded within a consecutive 12-month
			 period.
(c) An owner and
			 permittee must immediately investigate all larger-than-normal, unusual 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.