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'�1 Michael Jundt, SE From: kept baucher <kentb@technicon.net> Sent: Tuesday, May 10, 20113:10 PM To: Michael Jundt, SE Subject FW: Swift Transportation FYI Kent From: stephen plauson Sent:: Tuesday, May 10, 201111:40 AM To: kent baucher Subject: RE: Swift Transportation Kent, As requested, I have reviewed the subject draft report from a geotechnical perspective and provide my comments in the following paragraphs. Calculations by Associated Design and Engineering, Inc, attached to the referenced draft report indicate the subject tank is supported on two steel saddles welded to the tank with a steel plate bearing surface of 6" in width and 4.7 feet in length. According to the draft report, the steel saddle and bearing plate rest on 3" of asphalt and 6" of aggregate base assumed to be underlain by the native subgrade soil. The calculations utilize a stress distribution through the asphalt and aggregate resulting in a bearing width of 18" and a static bearing pressure at the aggregate base and subgrade interface of 1,360 psf. The peak dynamic bearing pressure at the aggregate base and subgrade interface was estimated in the calculations to be 4,160 psf due to overturning (full condition) during a seismic event. Swift Transportation provided a Geotechnical Investigation Report for the subject facility prepared by Kleinfelder, Inc. (reference file 20-4161-01.G01/2018R336, dated May 12, 1998). Based upon review of the report, the average blow count in the upper 0 to 4 feet is approximately N=20 utilizing 2.5" OD split barrel sampler. The equivalent SPT blow count is estimated to be approximately N=15 , which correlates to a shear strength value �=38°. The average density based on unit weight tests conducted in the upper 4 feet of the site is estimated to be 122.5 pcf. These values were utilized in the Terzaghi bearing equation along with bearing surface geometry of B=18" and D=9". The analysis indicates an available allowable bearing (DL+LL) of 4,300 psf and total combined bearing pressure (DL+LL+ transient loading) of 6,450 psf. The available allowable bearing pressure of the asphalt and aggregate base was also checked using an assumed shear strength value Q --45°. Due to the high shear strength characteristics, the allowable bearing pressure of the asphalt and aggregate base is significantly greater than the bearing pressure for the native subgrade soil. As such, the design bearing pressure is governed by the lower strength silty sand subgrade soil. In summary, based on the analysis of the data contained in the referenced report, the available bearing pressure due to the estimated shear strength of the asphalt, aggregate base, and underlying silty sand soil results in available bearing pressures that exceed the calculated bearing pressures generated by the tank during static and dynamic conditions. Therefore, it appears that the tank from a geotechnical standpoint is stable in both static and dynamic loading conditions. Stephen P. Plauson, PE, GE TECHNICON Engineering Services, Inc. 4539 N. Brawley, Suite 108 Fresno, California 93722 Phone: (559) 276-9311 Fax: (559) 276-9344 From., kent baucher Sent: Tuesday, April 26, 20113:58 PM