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Cesar Ruvalcaba [EH] <br /> From: Rosen, Stephan <Stephan.Rosen@nustarenergy.com> <br /> Sent: Wednesday, August 16, 2017 12:51 PM <br /> To: Cesar Ruvalcaba [EH] <br /> Cc: Habets, Todd; Smith, Ray; Hufman,Joe <br /> Subject: RE: Underground Storage Tanks for CERS ID 10180861 Not Accepted By Regulator <br /> Hello Cesar. <br /> We will work to update CERS. <br /> Regarding the material which enters the subject UST and its use, it is not petroleum, but tank bottoms water and storm <br /> water. More explicitly, the water is sourced from the bottom of diesel fuel floating-roof tanks. It accumulates through <br /> time primarily as the rain water which enters the open top of the tanks, does not get captured by roof drains, migrates <br /> past floating roof seals, and into the shell of the tanks, where it settles at the bottom due to the greater specific gravity <br /> of the water, and it's immiscibility with diesel fuel. The UST will also contain a percentage of storm water sourced from <br /> a containment area for diesel fuel additives, as that drains into the same tank. <br /> The de minimis volume which enters the tank will accumulate through time before it is periodically removed in what is <br /> known as a "water draw." Water in contact (at the water/product interface) with diesel will be subject to chemical <br /> dissolution and therefore contain some dissolved-phase diesel constituents; however, separate-phase diesel will not be <br /> present in the water draw. Only water is removed from the bottom of the tank;similarly, only water is present in the <br /> containment area. Water from both sources is temporarily stored in the subject tank before being removed. It is for <br /> this reason that BOE concurred with our interpretation and now recognizes it as an "exempt tank non petroleum <br /> product." <br /> Given the information above, do you have sufficient information to determine whether or not the tank actually falls <br /> under the regulations you enforce? Please advise. <br /> Thank you for your patience and helping to work through this. <br /> Stephan Rosen <br /> Senior HSE Manager-West Region <br /> dg <br /> 9 Phone: (510)787-1076 x3507 <br /> 2 Mobile: (925)212-2894 <br /> R Fax: 210 918-5737 <br /> 1 ► U <br /> FA 000a0sa <br />