Revisited: USCG FRP WCD volume, how does one calculate? – An OPA90 Discussion
John K. Carroll III
Associate Managing Director at Witt O'Brien's, LLC, Part of the Ambipar Group
In 2017, I published a similar article to today’s – updated somewhat here. As shown below, compliance with the requirement can be tricky, especially for those who do not do this for a living, so I have decided to revisit the conversation. Following this week’s article, I’ll also revisit my full mini-series, which focused on the Oil Pollution of Act of 1990 (OPA90) worst-case discharge (WCD) planning volume determinations for the three inland federal agencies: U.S. Coast Guard (USCG) (this week’s); Environmental Protection Agency (EPA); and the Department of Transpiration’s (DOT) Pipeline and Hazardous Materials Safety Administration (PHMSA).?
As always, let’s first see what the rule says:
(a) The response plan must use the appropriate criteria in this section to develop the worst case discharge.
(b) For the MTR segment of a facility, not less than—
(1) Where applicable, the loss of the entire capacity of all in-line and break out tank(s) needed for the continuous operation of the pipelines used for the purposes of handling or transporting oil, in bulk, to or from a vessel regardless of the presence of secondary containment; plus
(2) The discharge from all piping carrying oil between the marine transfer manifold and the non-transportation-related portion of the facility. The discharge from each pipe is calculated as follows: The maximum time to discover the release from the pipe in hours, plus the maximum time to shut down flow from the pipe in hours (based on historic discharge data or the best estimate in the absence of historic discharge data for the facility) multiplied by the maximum flow rate expressed in barrels per hour (based on the maximum relief valve setting or maximum system pressure when relief valves are not provided) plus the total line drainage volume expressed in barrels for the pipe between the marine manifold and the non-transportation-related portion of the facility; and
(c) For a mobile facility it means the loss of the entire contents of the container in which the oil is stored or transported.
Are you a visual person? Here’s an example of how it’s written out (fictional numbers just to show math):
{[ Maximum Discovery Time (Hrs.) + Maximum Shutdown Time (Hrs.)] * Maximum Flow Rate (Bbls. /Hr.)} + Total Line Fill (Bbls.) = WCD (Bbls.)
Potential simultaneous pumping operations (SO): 1????
Maximum pumping flow rate (MFR):??45,000 Bbls. /Hr.
Discharge discovery time (MDT):??????????0.5 Hrs.
Discharge shut downtime (MSDT):??????0.03 Hrs.
Maximum Line Fill Volume (LFV)
LFV = [(Pipeline Cross-Sectional Area X Length) X 7.48 Gal./ Ft.3] / 42 Gal./Bbls.
LFV = [(2.1806 Ft.2* X 391 Ft.) X 7.48 gal/Ft.3] / 42 Gal./Bbls.
LFV = 152 Bbls.
*20” Diameter
WCD= [(MDT+ MSDT)] X MFR] + LFV
WCD= [(0.5 Hr. + 0.03 Hr.) X 45,000 Bbls. / Hr.] + 152 Bbls.
领英推荐
WCD= 2,537 Bbls.
Still confused? Let’s try to simplify it a little further.
Line fill volume, LFV, is where many get confused while developing these, and simply put, it is a volume of a cylinder. Read here on jurisdictions if unsure where to determine the start and endpoint of USCG regulated pipelines. One needs the overall length and diameter in order to calculate drain-out volume. Furthermore, it is not uncommon for pipelines to reduce in size as they get closer to a dock manifold. In this case, one would treat each section based on diameter as a separate cylinder and simply add the two volumes (sections) together. Online interactive volume calculator tool.
Many also get confused with the requirement to address potential simultaneous pumping operations. This means, “Can you operate more than one transfer at a time?” If yes, you must replicate the above formula x number of times and then add the WCD numbers together to get your maximum release potential, WCD volume. ???????????????
Many companies run into problems when submitting new OPA90 plans or when acquiring new assets and trying to use the previous company’s OPA90 plan because the plans don’t show the math, so there’s no way to quantify the WCD value. One can’t put in a plan statement saying, “The terminal’s USCG WCD volume is X.”; instead, one must show all the data points required under the rule used to derive the WCD value one can show it was calculated correctly.
One last area we at Witt O’Brien’s see commonly done incorrectly are companies showing numerous calculations for every pipeline from their dock. Again, we’re looking for the largest line, so if you have one 10” line and one 12” line with the same pipe lengths, one will only do the math for the 12”. However, if one has multiple lines with varying lengths, it may be necessary to run multiple calculations to hard confirm which has the largest release potential; however, only the largest one is required to be shown in the plan – I’m with the mindset keep it simple and streamlined.
As a less common situation, the additional requirement to have all piping carrying oil between the marine transfer manifold and the non-transportation-related portion of the facility is not included above. What does that mean? If the lines from the first valve in secondary containment to the dock are kept full of oil, then the oil in these needs to be added to the WCD. To do this, one would do an LFV for each of these lines and then add it to the formula above.
Example:
{[ Maximum Discovery Time (Hrs.) + Maximum Shutdown Time (Hrs.)] * Maximum Flow Rate (Bbls. /Hr.)} + Total Line Fill (Bbls.) + Total Line Fill Volume (Bbls.) of all piping carrying oil between the marine transfer manifold and the non-transportation-related portion of the facility. = WCD (Bbls.)
Separate from, but along the same lines, are the possible oil group discussions.?If multiple oil groups are found on-site, or just one, and transferred over the dock, one would first figure out the facility’s WCD, then using it, enter the WCD volume into a spreadsheet to address the requirements of §154.1045?-Response plan development and evaluation criteria for facilities that handle, store, or transport Group I through Group IV petroleum oils. through the USCG Resource Planning. ?(or if group V, §154.1047)
It’s the math where people tend to get anxious when reading this rule; however, as with any math computation, set up your formulas, enter in the data, and one shouldn’t have any problems.
Would an easy-to-use spreadsheet help? WCD Calculator or Response Planning Volume Calculator. If yes, feel free to email me and request a copy of one or both.
Additional USCG articles I published earlier this year, which provide additional insights:
For a complete listing of archived blogs and compliance insights, click here. Past blogs cover training requirements, clarification on additional confusing elements within the above rules, and much more.
We are here to help solve your compliance questions and challenges. Need some compliance assistance, or have a question? Please email John K. Carroll III ([email protected]) Associate Managing Director – Compliance Services or call +1 281-320-9796.
Witt O’Brien’s:
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