over pressurized fuel storage tanks

We observed 75 bulk deliveries between December 24th, 2018 and January 1st, 2019.

A total of 75 deliveries being 25 in Metro Atlanta, Georgia, 25 in Metro Kansas City, Missouri and 25 in Metro St. Louis, Missouri.

24 out of 25 deliveries observed were being made in a condition considered Out of Compliance due to driver errors in configuring drop and stage 1 vapor recovery connections. During the out of compliance bulk fuel delivery and vapor recovery events open tank scenarios and driver bypassing Stage 1 in order to expedite deliveries were found to be the culprit causing excessive vent VOC releases.

The concerning issue was typically where a driver would vent negative pressure when connecting the Stage 1 vapor recovery hose to the tank before connecting to the delivery truck.

Logically thinking in most cases a receiving tank would ingest when relieving negative pressure pre delivery, extremely large volumes of outside atmosphere.

This mass volume of outside atmosphere ingested caused all kinds of obvious problems that would not normally be seen on a Stage 1 equipment certification test site.

Drivers using poor judgment and a "who cares lack of concern" for escape of massive amounts of VOC's when bypassing Stage 1 in order to expedite the delivery was even more concerning.

Adding to the bypass of Stage 1 problem observed in a number of fuel delivery events was the delivering tanker compartments being intentionally opened to atmosphere allowing increased out of dynamic balance fuel flows (drops). Exceeding vent pressure/vacuum relief valve flow rating during high ( exceeding 1,200 GPM ) speed drops caused extreme dynamic back pressures ( in excess of 10 PSI ) to build in receiving and associated tank(s) empty spaces. For a UL-58 rated tank these over pressurization events would normally be considered by the manufacture to be fatal regarding compartment bulkhead separation and primary tank boundary integrity.

"5.4. Fuel deliveries and accidental vent releases

Based on observations and interpretation of time series of the tank pressure data, it is likely that the peak vent emissions (e.g., Fig. 3b) were partly due to non-compliant bulk fuel drops where the Stage I vapor recovery system either was not correctly hooked up by the delivery driver or to hardware problems with piping and/or valves. This conjecture is consistent with typical US storage tank volumes (~10,000 to 30,000 gal). Assuming that Phase I vapor recovery did not work at all and that 10,000 gal (~38,000 L) of fuel were delivered, the working loss (volume of gasoline vapor/air mixture released to the atmosphere through the vent pipe) is 38,000 L. It is also reasonable to assume that delivery lasted less than 1 h. According to Table 2, the maximum hourly flow rate through the vent pipe was 250 L/min at GS-MW, which would result in a maximum cumulative vapor release of 15,000 L within this hour. The measured maximum cumulative release underestimates the assumed working loss of 38,000 L. This could be due to a fuel delivery, which involved dropping fuel from multiple compartments of a tanker truck, with the vapor return hose not being correctly hooked up for only some of the emptied compartments.

At GS-MW, UST pressure decreased after fuel delivery (causing vent emissions to cease for several hours) during the climatic conditions prevalent during the observation period, behavior not observed at GS-NW. In practice, it is possible to observe both positive and negative pressure excursions, even during the same fuel delivery (when multiple fuel compartments of tanker trucks are unloaded), when Stage I vapor recovery is in place

Interesting about the PV Valve failures here as I'm sure just about every where else as well. Exactly why they are simply and obviously failing probably worth further discussion.

Zane MillerAtlanta, Georgia

On Monday, October 28, 2019, 12:01:24 PM EDT, Watkins, Mark@ARB <[email protected]>