INVITATION TO BID 24-07-01 CONSTRUCTION OF INTRACOASTAL SPORTS PARK

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Mr. Mark Castano, P.E. February 21, 2024 Keith & Associates, Inc. . Page 5 Geotechnical Study – Intra Coastal Sports Complex – 15800 Collins Avenue NV5 Project No.: 17990 CONSTRUCTION QUALITY ASSURANCE - INFRASTRUCTURE - ENERGY - PROGRAM MANAGEMENT - ENVIRONMENTAL stabilized groundwater at the site will generally be encountered within the upper five (5) to 10 feet of the existing ground surface elevation. 5.2 FIELD PERMEABILITY The result of the open-hole field permeability (drainage) test performed at the site is presented in the table below: TABLE 2 – SUMMARY OF FIELD PERMEABILITY TEST RESULT Test ID Test Depth (ft.) Hydraulic Conductivity (cfs/ft2-ft. head) P-1 15 2.59 x 10-04 It should be noted that the above result is un-factored and represents the conditions at the test location at the time of the test. To account for potential variations in hydraulic conductivity across the site the designer should apply an appropriate safety factor to the reported value. The permeability test data are presented in Appendix B. 6.0 EVALUATION AND DISCUSSION 6.1 FOUNDATION SUPPORT Based on the results of the field exploration and our engineering analyses, we consider the site suitable for the proposed construction from a geotechnical engineering perspective. The primary concerns for foundation design and construction includes support of the proposed new structures loads without unacceptable settlement. Given the presence of the compressible peat and silt near the surface, we consider that deep foundation system is appropriate for the proposed new construction. Consistent with current practice in the South Florida area we consider augered, cast-in-place (ACIP) piles are appropriate for this project. Other deep foundation systems such as driven piles and drilled shafts are not considered to be appropriate. In addition to the noise nuisance, vibrations from driven pile foundations could adversely impact existing buildings on the site as well as those on adjacent properties. Additionally, it could be difficult to penetrate the hard zones in the limestone rock at the site to sufficient depths to provide adequate uplift capacity on the driven piles. Drilled shafts are typically economically feasible and attractive only where they are used to carry very large loads that sufficiently justify the slower installation rates and other installation difficulties attendant with such foundations. We conclude that the proposed development can be supported on 14-inch-diameter piles on the order of 30 feet long below existing grade. As an alternative method to transfer the loads to the competent bearing layer, helical piles can also be used. The helical piles would be on the order of 26 feet below grade and securely screwed into Layer 4 limestone. Our recommendations for foundation design and construction are presented in Section 7 of this report.