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• Sent by: STRUCTURES LAB,CSULB 562 985 4406 03126/99 13:38 Job 721 Page 3/3 <br /> evaluated t2►r proper cure and/or degradation of the surlacc resin. f=irst, the acetone test was <br /> performed in which a cloth wetted with acetone was rubbed on the inner surface of the tank at 3 <br /> or 4 locations as prescribed by ASTM. No tackiness was evident in any of these locations. in <br /> addition to acetone,a more severe chemical was applied to the inner surface consisting of V3 <br /> iso-octane, 113 toluene, and 1/3 ethyl alcohol by volume. This chemical is one of the standard <br /> mixtures prescribed by Underwriters Laboratories in the evaluation of fiberglass laminates for <br /> underground tanks. As with acetone, no sensitivity ofthe inner surface to this chemical was <br /> observed. Therefore, it can be concluded that the inner surface of the tank has not leen <br /> chemically degraded by the storage of gasoline. Further evidence of this fact is the shiny <br /> appearance of the inner surface of the tank shell and the end domes. Therefore,the West tank is <br /> structurally acceptable and has experienced virtually no chemical degradation due to the storage <br /> of the gasoline. <br /> For the Last tank, my measurements of the diameter were very similar to those of Fluid <br /> containment(this data has also been given to Mr. Wilson for his analysis). The measured <br /> diameters are all within 112 in. of the original manufacturing diameter,and thus well within the <br /> I ON,requirement. Regarding visual inspection for the East tank, the same observations were <br /> made as for the West tank_ Under chemical exposure of acetone,and the more severe mixture of <br /> toluene, iso-octane,and ethyl alcohol,there was no tackiness or sensitivity of the inner surface of <br /> the tank from both of these chemicals. The inner surface still has a shiny appearance which is a <br /> clear indication of little or no chemical degradation. Therelbre, the East tank is structurally <br /> acceptable and has experienced little or no chemical degradation from the stored gasoline. <br /> In addition to the above conclusions, minor alterations recommended below are designed <br /> to enhance: the performance of the tank over an extended period of time. <br /> 1. The interior center seam for both tanks should be provided with a bond which is currently <br /> lacking.. <br /> 2. Me: bonds over plates at the bottom of both tanks should be enhanced with additional <br /> layers of mat. However,close inspection of these areas indicated that no degradation or <br /> cracking has been caused by past usage of dipsticks. <br /> 3. At the interface between the dome and the shell, a relatively rough transition surface is <br /> evident for both tanks and at both domes of each tank. Close visual inspection of this <br /> region indicated no chemical or physical degradation_ However,it is my opinion that it <br /> would be prudent to apply one or two layers of mat approximately 6 in. wide followed by <br /> one layer of C-veil. <br /> Recently, it has been customary for Fluid Containment to perform Items 1 and 2 above <br /> when entering any single wall tanks. Item No. 3 is a suggestion which your company may or <br /> may not choose to adopt. If you have any questions, please call me at(562) 955-4406. <br /> £O-d OSZ9 tF89 916 -07 S10f1OOUd ODUV VVS=01 66-8Z--4RW <br />