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North County Library Addition Geotechnical Exploration Report 1001 County Road #512, Sebastian, Florida April 24, 2020 GFA Project No. 20-9197.00 Page 6 of 10 The subsurface soil conditions encountered at the boring locations generally consisted of very loose to medium dense fine sand (SP), fine sand with silt (SP -SM), and silty fine sand (SM) to the termination depths. 2.5 Hydrogeological Conditions On the date of our field exploration (April 21, 2020), groundwater was recorded in the borings at depths of approximately 6.2 and 7.1 feet below the existing ground surface. Note that the groundwater table will fluctuate seasonally depending upon local rainfall and other site specific and/or local influences. Brief ponding of stormwater may occur across the site after heavy or extended rainfall events. No additional evaluation was included in our scope of work in relation to the wet season high groundwater table or any existing well fields in the vicinity. Well fields may influence water table levels and cause significant fluctuations. If a more comprehensive water table analysis is necessary, please contact our office for additional guidance. 3.0 ENGINEERING EVALUATION AND RECOMMENDATIONS 3.1 General Our geotechnical engineering evaluation of the site and subsurface conditions at the property, with respect to the planned construction, and our recommendations for site preparation and foundation support, are based upon (1) our site observations, (2) the field data obtained, and (3) our understanding of the project information and structural conditions as presented in this report. If the stated conditions are incorrect, or if the project description is revised, please inform GFA so that we may review our recommendations with respect to any modifications. We note that the applicability of geotechnical recommendations is very dependent upon project characteristics, specifically (1) improvement locations, (2) grade alterations, (3) and actual applied structural loads. For that reason, GFA must be provided with and review the preliminary and final site and grading plans, and structural design loads to validate all recommendations provided in this report. Without performing this review, our recommendations should not be relied upon for final design or construction of any site improvements. 3.2 Site Preparation GFA recommends the following compaction requirements for this project: ➢ Proof Roll ... ➢ Building Pad ➢ Footings ..... ......................................................... Fill.................................................... 95 percent of modified Proctor 95 percent of modified Proctor 95 percent of modified Proctor The compaction percentages presented above are based upon the maximum dry density as determined by the modified Proctor test (ASTM D 1557). All density tests should be performed to a depth of 2 feet below stripped surface and bottom of footings. Density testing should be performed using either the nuclear method (ASTM D 6938) or the sand cone 6FF