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6 Indian River County Page 2 Project-No . 0041 - 893 r - The height and construction type of the observation tower was not provided to us . We ' presume that the tower's platform will be supported by either timber or concrete columns with a shallow foundation, system, or may be pile supported, depending on the subsoil conditions . Generally, ' our work involved subsurface exploration, field permeability testing, laboratory review and testing, engineering analysis and- preparation of this report which presents the factual information obtained and our geotechnical recommendations related to design , of the project components . ' SITE CONDITIONS The site settings -are mostly citrus grove with . open grassed areas, and densely wooded vegetation at the Pelican - Island and Cairns Site respectively . Reference to. the . S . G. S . Quadrangle . Map Sebastian, Fla. (dated 1949, photo revised 1970) shows both Pelican Island . and the - Cairns Site to be relatively flat and at an elevation of approximately +3 feet NGVD . Per Indian River County requirements, the . minimum; elevation of the road surface will be at +5 . feet (i . e . , about .2 feet of filling will be needed) : At Pelican Island north- o s uth an . d . east-west trending drainage ditches transect the area. These were presumably excavated . at some prior time tocontrol water table elevations within the citrus grove . The . Soil Survey of IndianRiver County, Florida (SCS) published by the U. S . Department of Agriculture in January 1987 maps the , pre dominant shallow subsoils - within both Pelican Island and the Cairns Site as Captiva sands. Soils at. the southern end of Pelican Island along the Indian River Lagoon are mapped as McKee mucky clay loam. Captiva sand is described ' as a, nearly level, poorly drained soil that is found in ,narrow, - elongated sloughs that are between low, dunelike ridges and mangrove swamps . Typically, these areas are mantled by about 1 /2 foot of very - dark gray fine sand mixed with about 2 percent shell fragments . The ' underlying soil to a . de th of 6- 1 /2 feet or 'more is described as a fine sand mixed with p gray about 2 to 15 percent shell fragments . . McKee mucky clay loam is described as level; very poorly drained soil that is found in mangrove islands and. swamps at, or near sea level, in, or adjacent to , the Indian River, Typically, the surface layer is very dark grayish brown mucky I loam about 1 inch in thickness. It is followed by dark 'gray clay loam, sandy clay, and sandy loam to a depth of,about 64 /2 feet or more . Under natural conditions; the SCS reports that the water table in areas of Captiva sand is between the depths of 10 and 40 inches for 6 to 9 months during most years; and at a depth of less than 10 inches' for 1 to 3 months during the wet season. However, standing water reportedly covers the soil for about 1 month in some years. According to the SCS , McKee ' mucky clay loam remains saturated throughout the year.