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13t Street SW Bridge at 58th Avenue -4- File No. 07-5535 Measured Groundwater Level The groundwater level was measured in each of the boreholes on the day drilled, after stabilization of the downhole water level. As shown in Appendix II, groundwater was encountered in the borings at approximate depths ranging from 9 to 9.3 feet below the existing ground surface on the date indicated. Fluctuations in groundwater levels should be anticipated throughout the year primarily due to seasonal variations in rainfall, water level in the canal, and other factors that may vary from the time the borings were conducted. Groundwater may also temporarily "perch" atop the shallow clayey soils during or immediately following periods of heavy or prolonged rain. ENGINEERING EVALUATION AND RECOMMENDATIONS General Based on the findings of our site exploration, our evaluation of subsurface conditions, and judgment based on our experience with similar projects in the area, we conclude that the soils underlying the site are satisfactory to support the proposed bridge on a deep foundation system consisting of conventional driven, prestressed, square concrete piles. Based on our review of the information provided by the project Bridge Engineer, the approximate elevation of the ground surface at the boring locations adjacent to the canal is about +24 feet NGVD, and the canal bottom is located at approximately +11 feet NGVD. Our borings were performed at the canal banks (Le., ata ground surface elevation of approximately +24 feet NGVD). We anticipate the bridge deck will be relatively level and roughly the same elevation as the ground surface at the canal banks. We understand that the existing canal will not be significantly deepened or widened. We further understand that the preliminarily selected pile size is 14 inches square. We recommend driving the intermediate 14 -inch square prestressed concrete driven piles to a minimum depth of 40 feet below the existing ground surface at the location of our borings. Capacities for 14 -inch square and 18 -inch square, prestressed concrete piles installed to depths of 40 and 45 feet are provided in Table 1 below. We note that our recommendations do not include any consideration for scour or erosion of the foundation soils. If scour is an issue, we should be contacted to re-evaluate the recommendations in this report. We could perform this analysis if requested by the client. Static pile capacities were estimated following procedures utilizing SPT N -values from the borings for this study. Specifically, the computer software, "SPT -97", developed by FDOT was used which utilizes procedures developed by Dr. Schmertman which were originally outlined in Research Bulletin No. 121-B, dated September, 1967.