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Sent by: STRUCTURES LAB,CSULB 562 985 4406 03/31/99 12:18 Job 750 Page 2/5 <br /> MEMORANDUM ,r:�t,,,:'.•�'�.' ;�� <br /> Ir'•�`y "'j inti�;=,,,t�;: <br /> 1 U Sill Merchant <br /> ARCO <br /> FROM: J.M. Plccnik * , <br /> Consultant <br /> 1880 San Anselinc n• C �I��' <br /> Long Beach,CA 00815 F C:'� <br /> �` !' <br /> (562)985-4406 <br /> March 26. 0199 <br /> S[li3.lfsC'1': inspection of Two Underground Fiberglass'tanks at the ARCO Gas Station at the <br /> Intersection of'Freeway 99 and Route 120 in Manteca.California <br /> On March 25, iq99, 1 inspected two fiberglass tanks,both 8 ft.diameter single wall tanks, <br /> manufactured by Owens Corning prior to 1985. The purpose for inspecting the tanks was to <br /> evaluate their structural integrity as well as any degradation of the interior surface. The <br /> longitudinal axis of the two tanks are in the North/South direction. Therefore.the tanks referred <br /> to herein will be referred to as either the East or the West tank. Fluid Containment repair crew <br /> also labeled these tanks as Tank No. 1, which I would refer u)as the West tank,and Tank Nei. 2 <br /> as the East tank. Manways were installed on the northern end of the two tanks to allow I'm <br /> access. The tanks had been previously cleaned by Fluid Containment personnel_ On the date of <br /> my inspection,the oxygen level within both tanks was approximately 20.9%and the I.E1. levels <br /> were near or at zero. in the following, I will descrihc the results of my evaluation for each of the <br /> tanks individually. <br /> For the West tank. both Fluid Containment and 1 measured the internal diameters of the <br /> tank at six locations(Data provided to Mr. Wilson), from one end of the tank to the other. These <br /> measurements were in the vertical,horizontal,and two diagonal directions. Therefore.a total of <br /> twenty-tour diameter readings were obtained on each tank. 'lire readings obtained by Fluid <br /> Containment personnel were nearly identical to mine with a variation of no more than I/16 to <br /> I/R in. 'i'lte most critical reading was at Location 5,which measured the vertical diameter of <br /> 9I-5/8 in. and a diagonal diameter of 91-5/16 in. Since the diameter of the tank is 92 in. <br /> (probably plus or minus U16 in.)at the time of manufacturing,the largest amount of ovalling <br /> based on the original diameter of 92 in.is thus 11/16 in.,which represents a relative deformation <br /> of 0.75%, which is less than the I%allowed by most specifications and federal regulations. The <br /> other diameter readings were generally within 1/2 in.of the 92 in.original manufacturing <br /> diameter. Visual inspection of the tank interior surface indicated no chemical or mechanical <br /> degradation. No cracking was observed on either the shell or the doines. Discoloration of the <br /> resin i5 evident on the lower half of the tank, but this is typical for gasoline tanks of this age. <br /> Microscopic inspection was also performed at a number of locations. 7'hese indicted no <br /> degradation of the glass below the resin rich layer or any extensive penetration of the gasoline <br /> into the laminate. In addition to visual inspection,the inner surface of the tank was evaluated lir <br /> £O-d 09Z9 V139 916 -00 s-L3nG0bd 03UV V91 :80 66-1 O-•4dV <br />