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Hazardous Materials Program Guidance Document <br /> HMPG-025 — Underground Storage Tank Overfill Prevention <br /> A. Scope <br /> This document addresses issues associated with underground storage tank (UST) overfill prevention <br /> systems. For enforcement purposes, refer to the actual text of the regulations since the wording in this <br /> document summarizes the requirements. References to Title 23 California Code of Regulations (23 CCR) use <br /> citations in the updated regulations that are effective October 1, 2018. <br /> B. General <br /> The local agency may waive the requirement for overfill prevention equipment where the tank inlet exists <br /> in an observable area, the spill container is adequate to collect any overfill, and the tank system is filled by <br /> transfers of no more than 25 gallons at one time. [23 CCR§2635(c)(2)][Note: This provision allows, but does not <br /> require, the UPA to waive the requirement. In cases where the UST operator allows overfilling to occur, HMCD <br /> may withdraw such a waiver and require the UST owner/operator to retrofit the UST with approved overfill <br /> prevention equipment.] <br /> All USTs that are not exempted pursuant to 23 CCR§2635(c)(2) must be equipped with an overfill prevention <br /> system which does not allow for manual override and meets one of the following options: [23 CCR§2635(c)(1)] <br /> Al Alert the transfer operator Flow restrictor(ball float) oft <br /> when the tank is 901; full by installed below vent riser @ <br /> restricting the flow into the tank 90% <br /> [23 CCR§2635(c)(1)(A)] 6 <br /> A2 Or Alert the transfer operator External audible& visual <br /> when the tank is 901/,, full by alarm unit @ 90% <br /> triggering an audible and visual <br /> alarm. [23 CCR§2635(c)(1)(A)] <br /> B Restrict delivery of flow to the Flow restrictor(ball float) <br /> tank at least 30 minutes before installed below vent riser @ <br /> the tank overfills, provided the 595%and external audible Oft <br /> restriction occurs when the alarm unit <br /> tank is filled to no more than AND <br /> xHM1 <br /> 95%of capacity;and activate an <br /> audible alarm at least 5 minutes <br /> before the tank overfills. <br /> [23 CCR§2635(c)(1)(B)] <br /> C Provide positive shut-off of flow Mechanical overfill prevention <br /> to the tank when the tank is (flapper)valve @ 95"- <br /> filled to no more than 95% of <br /> capacity. [23 CCR§2635(c)(1)(C)] <br /> D Provide positive shut-off of flow Mechanical overfill prevention <br /> to the tank so that none of the (flapper)valve @ X95 <br /> fittings located on the top of the _ <br /> tank are exposed to product <br /> due to overfilling. <br /> [23 CCR§2635(c)(1)(D)] <br /> HMPG-025 Page 1 of 7 1/7—Rev.09/20/18 <br />