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Indian River County File No . 06-5699 -4- 4 . 0 CONCLUSIONS AND RECOMMENDATIONS 4 . 1 General Soil Stratigraphy for Roadway The results of the field exploration and laboratory testing programs are presented on the Soil Boring Profiles sheet , Figure 5 . The stratification of the soil boring profiles represents our interpretation of the field boring logs and the results of the laboratory examination of the recovered samples . The stratification lines represent the approximate boundary between soil types . The actual transitions may be more gradual than implied . The results of our borings indicate the following general soil types : - v A rwlassificatian Strata '. a Index- AAS1 ?J ' � O 505 Dark brown to dark gray slightly silty fine sand to silty fine sand with -- -- organics (topsoil ) 2 Light brown to very dark brown fine sand to fine sand with silt A-3 S Dark brown to very dark brown weakly-cemented fine sand to fine 3 sand with silt [hardpan-type] A-3 S 4 Light gray to dark brown fine sand with clay A-2-4 S 5 Light brown to very dark gray clayey fine sand A-2-6 P Soils encountered in the borings performed along the proposed alignment of 20' Avenue SW typically included suitable sandy soils with variable amounts of clayey and ' silty fine sands (AASHTO Classifications A-3 and A-2-4 , Soil Strata Nos . 2 through 4 ) overlying plastic clayey fine sand soils (A-2-6 , Soil Stratum No . 5 ) . Soil Strata Nos . 2 through 4 (A-3 and A-24 ) may be considered as select materials based on FDOT criteria ( Index 505 ) . The use of these soils relative to embankment construction should be in accordance with FDOT Standard Index 505 . We note that , while Soil Stratum No . 4 (A-24 ) is considered as select material based on FDOT criteria , it is our opinion that this soil type can be problematic for roadway construction . The clay content is sufficient that this stratum will retain moisture resulting in compaction difficulties . Recommendations relative to the use of clayey soils are presented below in Section 4A . Organic material or "topsoil" was encountered at the surface along the majority of the project site to depths of about 6 to 12 inches . The topsoil should be stripped from the proposed alignment and not be used for roadway construction or utility backfill . The removal of topsoil and any other organic soils as encountered ( i . e . , muck) should be accomplished in accordance with FDOT Standard Index 500 , unless otherwise noted on the plans .