Appeal 33566

2022 OSSC section1613 and ASCE 7-16 sect 12.13.9 and 15.4.10

The code requires considering the effects of lateral and liquefaction in the design of non-building structures (deep foundations are required).

This request is to is to appeal the enforcement of 2022 OSSC section 1613 in its reference to ASCE 7 in 1613.1 scope. Specifically, the sections in Chapter 15 and 12 mentioned above regarding deep foundations and lateral spreading mitigation. Note that all other requirements for seismic design will be met.

Based on mitigating circumstances provided by operational procedures and product flow control valves and specific attributes of the proposed structures and support soils, the proposed design provides for a reasonable degree of safety under liquefaction/lateral spread conditions. In general, liquefaction and lateral spread effects on the pipe support structures are greater at the riverbank/dock itself and decreases in landward direction toward NW Front Ave (Ref PSI Geotech Memo attached).

The existing dock and piping, as well as the new pipes, is more likely to rupture at or near the dock due to liquefaction/ lateral spread effects. To help mitigate this, additional “normally closed” valves have strategically been located further inland to limit any potential release. The valves will only be opened during vessel product transfer operations and only one pipe may be operated at a time.

For informational purposes, the existing flow control measures are as follows (will be same for new pipes). As required by Coast Guard regulations, 33 CFR 154, all vessel transfer operations are manned continually at the hose connection itself by the “PIC” (person in charge). During transfer operations, in the event of an emergency, the PIC can stop the product flow by manually closing the shut off valve at hose connection. For hazardous materials transfers at docks operated after October 4, 1990, this is within 30 seconds (60 seconds for existing pipes operated before 10/4/1990). The current design and operations of the facility meets or exceeds these requirements for the new pipes and existing pipes. Each new/existing product line has a valve inside the secondary containment wall. When a product line is not transferring product at the dock, these valves are closed.

The requirements of ASCE 7-16, 12.13.9/ 15.4.10 have not been considered and the design assumes the piping system will fail at or near the dock under conditions where liquefaction and lateral spread is greatest. This note will be included on the plans as part of the design criteria submitted at time of plan review.
As noted above under CODE MODIFICATION, documentation and calculations submitted as part of the permit submittal will demonstrate that the proposed design will meet all other appropriate requirements of the 2022 OSSC.

Much of the new and existing piping is supported by the existing dock structure. The existing dock structure has been shown to meet OSSC Chapter 34 seismic requirements, however it would likely experience some level of failure under liquefaction/lateral spread condition. The existing dock is exempt from section ASCE 7-16, 12.13.9/ 15.4.10 seismic requirements. For this reason, it is impractical to use deep foundations for the new non-building structures that extend landward from riverbank/dock. The effects of liquefaction /lateral spread decreases in landward direction from dock as noted in PSI Geotech Memo.