ENVIRONMENTAL FINAL GOVERNING STANDARDS ITALY

ITALY - APPENDIX C Determination of Worst Case Discharge Planning Volume
APC1. APPENDIX C
DETERMINATION OF WORST CASE DISCHARGE PLANNING VOLUME
APC1.1. This appendix provides criteria to determine, on an installation-specific basis, the
extent of a worst-case discharge (WCD).
APC1.2. This Appendix provides criteria to determine the volume of oil or hazardous
substance to be used in planning for a WCD. Installations should calculate both WCD volumes
that apply to the installation’s design and operation and use the larger volume as the WCD
planning volume.
APC1.3. For installations transferring oil to and from vessels with tank capacities of 10,500
gallons (250 barrels) or more, the WCD planning volume is calculated as follows:
APC1.3.1. 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
APC1.3.2. The discharge from all piping carrying oil between the marine transfer manifold
and the valve or manifold adjacent to the POL storage container. 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 installation) multiplied by the
maximum flow rate expressed in gallons 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 gallons for the pipe between the marine transfer manifold and the valve or
manifold adjacent to the POL storage container.
APC1.4. For installations with POL Storage Containers:
APC1.4.1. Single POL Storage Container Facilities. For facilities containing only one
aboveground oil or hazardous substance storage container, the WCD planning volume equals the
capacity of the oil or hazardous substance storage container. If adequate secondary containment
(sufficiently large to contain the capacity of the above ground oil or hazardous substance storage
container plus sufficient freeboard to allow for precipitation) exists for the oil storage container,
multiply the capacity of the container by 0.8.
APC1.4.2. Multiple POL Storage Container Facilities
APC1.4.2.1. Facilities having no secondary containment. If none of the above ground
storage containers at the facility have adequate secondary containment, the worst case planning
volume equals the total above ground oil and hazardous substance storage capacity at the facility.
APC1.4.2.2. Facilities having complete secondary containment. If every above ground
storage container at the facility has adequate secondary containment, the WCD planning volume
September 2012 Italy FGS APPENDIX C.1-1
Revision 0