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the effects of aquifer storage (specific yield) are taken into account. A duration of 25 days <br />was selected as being a reasonable time period of flood conditions. <br />b. Increases in the water table elevation were recorded at several distances between 5 feet and <br />200 feet from the pond. The maximum rise during the modeled period was selected for <br />plotting. <br />The U.S. Geological Survey's groundwater modeling code, MODFLOW, was used for this analysis. <br />How to Determine if a Variance is Warranted <br />In order to determine if a proposed lowest floor elevation is acceptable, the following need to be <br />known: <br />1. Depth to the water table and an estimation of the water table's seasonally high elevation. <br />2. Type of aquifer materials — e.g., clay, silt, sand, gravel <br />3. Information as to whether or not the water table is perched or is part of a deeper, thicker <br />aquifer system. <br />4. An estimate of the flood elevation of the pond. <br />5. The distance of the proposed floor to the pond. <br />Depth to the water table and the type of aquifer material needs to be determined through the <br />installation of soil borings. The other information should be estimated from other sources. <br />Once this information is obtained, the minimum depth to the water table from the bottom of the <br />proposed floor slab can be determined from one of six plots, attached to this memorandum. Which of <br />the six plots to use depends on the depth of the water table with respect to the pond's bottom and the <br />type of aquifer material (e.g., clay, silt, sand, gravel). The following steps should be used: <br />1. Determine the closest distance of the proposed floor to the pond (if the pond size increases <br />during flooding, the distance should be from the flooded perimeter of the pond to the <br />proposed floor). <br />2. Using Plot 1, determine the minimum permissible' depth to the water table for the specified <br />distance from the pond. If the actual depth to the water table (see discussion below for <br />determining this) is greater than the value on Plot I, no further evaluation is necessary — the <br />floor is sufficiently high with respect to the water table that the water table will not reach the <br />