Section 2646.1 - Statistical Inventory Reconciliation(a) When approved by the local agency, statistical inventory reconciliation may be used as part of a non-visual monitoring program, set forth in section 2643(b)(2), for existing underground storage tanks which contain motor vehicle fuel.(b) Each underground storage tank shall be individually monitored using a method that incorporates the following procedures: (1) Separate daily measurements shall be taken and recorded for both the motor vehicle fuel and any water layer. For the purpose of this section, "daily" means at least every day that motor vehicle fuel is added to or withdrawn from the tank, but no less than five days per week. The number of days may be reduced by the number of public holidays that occur during the week if there is no input to or withdrawal from the tank on the holiday. Local agencies may reduce the frequency of monitoring to not less than once every three days at facilities that are not staffed on a regular basis provided that the monitoring is performed every day the facility is staffed. The number of days may be reduced only if consistent with the independent third party certification required by section 2643(f). Measurements shall be:(A) Taken when no substance is being added to or withdrawn from the tank;(B) Performed by the owner, operator, or other designated persons who have had appropriate training;(C) Based on the average of two readings if dipstick or tape measurements are used;(D) Determined by equipment capable of measuring the level of the product over the full range of the tank's height to the nearest one-eighth of an inch. If a dipstick is used to determine the product level, a substance capable of rendering the readings legible shall be applied to the dipstick before use, if necessary to obtain accurate readings;(E) Determined by equipment capable of measuring, to the nearest one-eighth of an inch, water present in the bottom of the tank. If a dipstick is used, water-finding paste shall be applied to the dipstick. If the tank is not level, and the measurements are taken manually, the measurements shall be taken at the lowest end of the tank;(F) Measured at the center of the longitudinal axis of the tank if access is available or measured at the lowest end of the tank with a calibration measurement at both ends, if possible, to determine if any tank tilt exists, and, if so, its magnitude; and(G) Converted to volume measurements based on a calibration chart for the tank. This chart shall, where feasible, take into account the actual tilt of the tank.(2) Daily readings shall be taken for input and withdrawals. The amount of product inputs indicated by delivery receipt shall be compared with measurement of the tank inventory volume before and after delivery. Product input shall be determined by a method that introduces the least amount of error in the 30 day inventory reconciliation calculations. Underground storage tanks that are connected by a manifold may require time for the level to stabilize before a measurement is taken. Product shall be delivered to the tank through a drop tube that extends to within 12 inches of the bottom of the tank.(c) The tank owner or operator must provide the minimum number of data records to the statistical inventory reconciliation provider as required by that provider. Previously submitted data may be included with the current data to total the minimum number of records necessary to complete the statistical inventory reconciliation. Data submissions to the statistical inventory reconciliation provider and subsequent receipt of reports from the provider shall be completed at least once every 30 days. To give the owner or operator an opportunity to become proficient in the use of statistical inventory reconciliation, the requirements in subdivision (d) below do not apply if any of the first three reports are inconclusive. The owner or operator shall inform the local agency of the results of the first three reports, regardless of the results.(d) If the results of a report are inconclusive or indicate a possible unauthorized release, the owner or operator shall, within 24 hours of receipt of the report: (1) Notify the local agency of the possible unauthorized release, and within 10 days, submit a copy of the report to the local agency. The local agency may allow up to 10 additional days in which to submit the report;(2) Inspect the inventory records for errors to determine if data were collected properly; and(3) Inspect all accessible portions of the underground storage tank system for leakage by appropriately trained persons.(A) If an unauthorized release is detected, the owner or operator shall comply with the requirements of Article 5.(B) If no unauthorized release is detected, the owner or operator shall have dispenser meters, which determine the amount of product withdrawn from the tank, checked and recalibrated if necessary within 48 hours of receipt of the report. Meters shall be recalibrated by the County Department of Weights and Measures or a device repair person as defined in the California Business and Professions Code, Division 5, Chapter 5.5. This subparagraph applies to all meters used for determining withdrawals, including those at non-retail facilities. Dispenser meters shall comply with California Code of Regulations, Title 4, Division 9, "Division of Measurement Standards, Department of Food and Agriculture."(e) Daily readings shall continue to be taken and recorded during the investigation specified in subdivision (d) above. If the second statistical inventory reconciliation report does not indicate a tight system, the owner or operator shall comply with the release reporting requirements of Article 5.(f) The owner or operator who reports a suspected release in accordance with subdivision (e) above, shall conduct additional tests or investigations as required by the local agency and, if necessary, replace, repair, upgrade, or close the tank in accordance with the applicable provisions of this chapter.(g) A tank integrity test meeting the requirements of section 2643.1 is also required at least once every 24 months when statistical inventory reconciliation is used. The first tank integrity test shall be conducted within the first 12 months of implementation of a monitoring program which includes statistical inventory reconciliation.(h) The owner or operation shall conduct a piping tightness test and, if necessary, a tank integrity test within 15 days of receipt of two successive reports which are inconclusive or which indicate a possible unauthorized release. The local agency may also require a piping tightness test and, if necessary, a tank integrity test if frequent inconclusive results are reported.(i) Piping connected to a tank which is monitored using statistical inventory reconciliation shall be tested in accordance with section 2643(c), (d), or (e).(j) At least once every 12 months, the owner or operator shall submit a written statement to the local agency which indicates the results from the statistical inventory reconciliation reports for the previous 12 months.(k) Dispenser meters which determine the amount of product withdrawn from the tank shall comply with the provisions of Title 4, Division 9, "Division of Measurement Standards, Department of Agriculture." Meters shall be inspected and recalibrated by the County Department of Weights and Measures or a device repair person as defined in Division 5, Chapter 5.5 of the Business and Professions Code.Cal. Code Regs. Tit. 23, § 2646.1
1. New section filed 4-5-94; operative 5-5-94 (Register 94, No. 14).
2. Amendment of section and NOTE filed 8-27-2018; operative 10-1-2018 (Register 2018, No. 35). Note: Authority cited: Sections 25299.3 and 25299.7, Health and Safety Code. Reference: Sections 25291 and 25292, Health and Safety Code; and 40 CFR §§ 280.41 and 280.43.
1. New section filed 4-5-94; operative 5-5-94 (Register 94, No. 14).
2. Amendment of section and Note filed 8-27-2018; operative 10/1/2018 (Register 2018, No. 35).