Agenda - 08-27-2012 - C1 - Laserfiche WebLink

Browse Search

Soil Services,PLLC Proj ect No. 1 ll 6-1 systems are more expensive and may not be an economical option. Soil Services can provide additional information regarding these system types if requested. Areas with potentially suitable soils are shown on the attached soil/site evaluation map. The diagonally hatched unit represents areas with at least 24 to 48 inches or more of potentially suitable soil. These areas are typically useable for conventional, modified conventional, innovative, and/or low pressure pipe (LPP) systems. The cross hatched unit represents areas with at least 24 inches or more of potentially suitable soil. These areas are typically useable for innovative, alternative and/or low pressure pipe (LPP) systems. The brick hatched unit represents areas that may be suitable if existing structures/impact are removed and the underlying soil is not impacted. The "LTN"unit represents areas with less than 24 inches of potentially suitable soil. These areas are typically considered unsuitable for conventional system types. As mentioned above, these areas may be suitable for alternative system types. Unit "NE" represents areas not evaluated due to vegetation thickness or existing structures (barn, workshop, gazebo, deck, etc). Site planning should allow for adequate suitable soil for the septic system and repair. Septic areas should be unaffected by all site elements (house, driveway, garage, well, deck, etc.), setbacks from those site elements, and land disturbing practices (heavy traffic, mechanical clearing, excavation, etc). The local County and/or State regulating agencies will ultimately designate the septic system and repair areas to be permitted. If these areas are compromised during the permitting process, then they may be deemed inadequate or unsuitable for final permitting. All septic areas should be properly protected and remain undisturbed unless approval is first obtained from the local County and/or State authorities. General Considerations The utility of potentially useable soils depends on the size and configuration of the useable soil area and the orientation of the wastewater system within that area. The wastewater disposal lines are to be on contour(i.e. uniform elevation throughout a single disposal line). Therefore, topographical irregularities can increase the area needed for a given wastewater disposal system. The size of a wastewater treatment system is based on the design flow for a specific use(120 gallons per bedroom per day for single family residential dwellings) and the long-term acceptance rate (LTAR) assigned to the site. The LTAR is based on the soil characteristics (texture, structure,porosity, mineralogy, etc.) and site conditions found at the time of the evaluation. Setbacks from wells,property lines, top of embankment, basement, etc. should also be considered (refer to 15A NCAC 18A .1950 as attached). A field layout of the system and repair can be used to determine whether a useable soil area(s) can potentially support a proposed use (such as a four-bedroom residence). The system type along with the factors discussed above can also affect the size of the wastewater disposal field. A four-bedroom, single-family residence with a design flow of 480 gallons per day (120 gallons per bedroom per day)requires 12,000 to 16,000 square feet of useable soil area or 1,350 to 1,6001inear feet of conventional drain line(system and repair) or 1,280 to 2,000 linear feet of low pressure pipe (LPP) drain line (system and repair). Estimates reference the "Laws and Rules for Sewage Treatment and Disposal Systems" and are based on an LTAR range of 0.25 to 030 gallons per day per square foot(gpd/ft�) for conventional and modified conventional drain line and 0.10 to 0.15 gpd/ft�for LPP drain line. Actual drain field may require more area and/or 2of5