Hi TD, is this link any use: http://environment-agenc...e%20regulations&rk=1

The issue is perhaps not the tanks themselves, but how any spillage is designed to be contained? They are presumably bunded in some way and, in the event of a large leak, the diesel should be retained within the bunded area - but how would it then be recovered, and how long would that take? I suggest you review the emergency scenarios for the tanks (also under your control, or by another organisation?) to check whether the proposed office location conflicts with any plans or spill consequences, including fumes from a large contained spill entering the new building.

Thanks to all for the valuable information. TD

This might be what your after: Model Code of Safe Practice Part 2: Design, construction and operation of petroleum distribution installations This publication replaces the second edition of Part 2, published in 1998. Its purpose is to provide a general guide to safe practice in the layout, design, construction and operation of distribution installations and their equipment. It aims to recommend basic standards and practice in this regard. and Model code of safe practice Part 19: Fire precautions at petroleum refineries and bulk storage installations: Section 2 EI Fire precautions at petroleum refineries and bulk storage installations (EI 19) provides guidance on selecting, implementing and monitoring the continuing performance of installation-specific justified risk reduction measures – from prevention through detection, protection systems to mitigation measures – to reduce the risk from design event fires at installations that process and store crude oil, petroleum, intermediates and refined products: Section 4.8 Reading from the 1992 version (googled) with your flash point being below 66 Deg C, making it a class 2 product, it has specific requirements on distance from depending on your tank size, which you dont give. Des