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Comprehensive Plan Sanitary Sewer Sub -Element There are also other soil conditions that hinder the use of septic tank systems. Overall, though, most of the land area within the county is poorly drained and has severe septic tank system limitations. There are, however, two areas of the county in which the soils are better suited for the installation of septic tank systems. These areas are as follows: • Areas of South Florida Coastal Strand on the barrier island; and • Areas on the mainland in the vicinity of the Atlantic Coastal Ridge. The areas of the county having "Excessively Drained Soils" and "Moderately Drained Soils" are better suited for septic tank systems. As shown on Figure 3.E.1 of the Stormwater Management_ Sub -Element, even these two soil types have limitations with respect to septic tank system suitability. While moderately drained soils have a severe limitation rating for septic tank system suitability, excessively drained soils percolate so rapidly that they provide very poor filtration. Septic tanks on these soils have a potential for causing groundwater contamination. Currently, the IRCHD requires that a septic tank system have a minimum of 42 inches of well draining soil below the infiltrating surface of the drainfield. During the months of June through October, the season of greatest rainfall, the water table in much of the county may be only 24 inches below this infiltrating surface. Therefore, fill material is often placed on top of existing soil. This fill material, which provides the depth necessary for the proper operation of the septic tank system, is usually a highly porous sand that can purify the liquids discharged into the drainfield. In low density areas with adequate soils where septic tanks are appropriate, there can still be problems if septic tanks are not maintained. Generally, septic thanks need to be pumped on a regular basis. While there are private septic tank service companies which empty septic tanks and haul away septage, it is the septic tank owner who is responsible for initiating maintenance activities. Even when fill material is placed on a residential lot, there are still areas of the county in which there are problems with septic tank systems. Besides soil and groundwater conditions, these problems may be due to inadequate separation between septic tank drainfields and wells. Without adequate separation, the potential of contamination from septic tanks seeping into wells is greatly increased. Presently, the IRCHD requires a minimum separation of 75 feet between wells and septic tanks. Generally, the IRCHD requires that new lots utilizing well and septic tank systems be a minimum of 1/2 acre (approximately 20,000 square feet). If a lot is served by a public water system, a septic tank may be used even if the lot is as small as 1/4 acre (approximately 10,000 square feet). Community Development Department Indian River County 20