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I 1r 71 1 ' d F ; G aai 4 IF Oslo Road Improvement Project Page 5 File No . 11 -5420 4 . 2 Results of Field Permeability Tests The results of the six field permeability tests performed within the proposed dry detention pond areas are presented in the table below . Test No. Station* Offset* Coefficient of Horizontal Permeability, (feet) K„ (feet/day) Perm = 1 56+00 95 L 1 . 07 Perm-2 63+40 105 L 0.30 Perm-3 74+00 105 L i . 04 Perm =4 83+90 120 L 1 . 02 Perm -5 91 +50 100 L 0. 87 Perm-6 99+80 95 L 1 .27 [Eand offset are approximate and referenced from the baseline of construction of the "Oslo Roadements" sheets prepared by Indian River County. It is noted that a suitable factor of safety should be used with these values . In addition , for the type of soils tested, a transformation ratio to 1 horizontal to 1 vertical is appropriate (i . e . , the estimated ratio of horizontal to vertical permeability) . 4. 3 Groundwater Control The groundwater level was measured in the boreholes on the date drilled after stabilization of the downhole water level . As shown on Figures 4 and 5 , the encountered groundwater level in the auger borings was measured at approximate depths ranging from 3 .5 to 6. 5 feet below existing grade . Fluctuations in groundwater levels on this site should be anticipated throughout the year primarily due to seasonal variations in rainfall and other factors that may vary from the time the borings were conducted . Some form of groundwater control (dewatering) will likely be required during construction , particularly for utility installation and roadway construction during the wet season . Means and methods of groundwater control should be the responsibility of the contractor. We recommend that the contractor be made aware of the presence of the clayey soils present throughout the project corridor. Such material may Influence the dewatering methods used during the project. 4 . 4 Normal Seasonal High Groundwater Table I < i The normal seasonal high groundwater level each year is the level in the August- September period at the end of the rainy season during a year of normal (average) rainfall . The water table elevations associated with a flood would be much higher than the normal seasonal high groundwater level . The normal high water levels would more approximate the normal seasonal high groundwater levels . , I Rr IV I