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B. MOUND SYSTEM SITE PREPARATION The following calculations are for a mound system to serve the People of Christ Church facility. Pursuant to EHD requirements, the um in s stem for the of l P P g Y uent dis osal will con i p s st of a duplex pump arrangement, with the pumps alternating back and forth. General Construction Notes for the mound installation are found in the California State Water Resources Control Board- Guidelines for the Desire Installation and Operations of Mound Sewage Disposal Systems and the EPA Design Manual- On Site Wastewater Treatment and Disposal Systems. The location of the mound system is outlined on the Site Plans, and is proposed to be in the northeast comer of the subject property. Additionally, the mound must be constructed perpendicular to the general contour of the land and groundwater flow direction, which is assumed to be in a north-northeast direction. A 100%replacement area is designated to be directly south of the constructed mound system. Prior to the commencement of any and all construction activities, the proposed mound disposal area shall be cordoned off to prevent soil compaction by equipment driving over the area. At the start of mound construction, the native soil/sand media interface must be properly prepared. The native soil basal area must stripped of all native vegetation and then ripped to a depth of S inches. Soil moisture content at the time of ripping is critical and the soil should not be too wet or too dry. Ripping must be perpendicular to the surrounding land contour, which will be east-to- west, and only within the area of the sand/native soil interface. After plowing and before emplacement of the sand media, it is imperative that no equipment be driven over this area. C. CALCULATION OF MOUND DIMENSIONS BASAL LOADING RATE Due to the long-term acceptance rate anticipated, a conservative basal rate will be employed for design purposes. Consequently, a basal loading rate figure of 0.2 gallons/ftz/day will be used. HYDRAULIC LINEAR LOADING RATE From the percolation tests and direct observation of the soil from the infiltrometer test, it was evident that there was both vertical and lateral flow of water. Consequently, a linear loading rate of 6 gallons/lineal foot/day will be used. This linear loading rate will also allow for gaseous linear transfer of oxygen to meet the oxygen demand. SAND MEDIA/ GRAVEL BED SPECIFICATIONS AND LOADING RATE The filter media is typically a sand soil material that underlies the gravel bed. The sand media should be tested by an engineering laboratory, or be certified by the sand supplier before emplacement. A sieve analysis (ASTM C-33 Specifications) should demonstrate the sand media material must not have more than 20% (by wt.) of material greater than 2 mm dia. and no more than 2% (by wt.)passing the No. 200 sieve. Effective Diameter(d,o) should be 0.20 to 0.30 mm with a Uniformity Coefficient (D60/D10) of approximately <_4. The sand media loading rate complying with the specifications above will be 0.6 gpd/ftZ. 16 Chesney Consulting