DCPZP-2016-00721 - Laserfiche WebLink

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Page 4 of 5 At-Grade Construction Procedure prepared by Jeffrey L. Hammes 1. Check the moisture content of the soil to a depth of 8 inches. Smearing and compacting of wet soil will result in reducing the infiltration capacity of the soil. Proper soil moisture content can be determined by rolling a soil sample between the hands. If it rolls into a % inch wire, the site is too wet to prepare. If it crumbles, the site preparation can proceed. If the site is too wet to prepare, do not proceed until it dries. 2. Lay out the component area and distribution cell area on the site so that the distribution cell runs perpendicular to the direction of the slope. 3. For components in open, smooth topography, measure the average ground elevation along the upslope edge of the distribution cell. For components on uneven sites (rough terrain), till the surface before measuring the average ground elevation along the upslope edge of the distribution cell. The average elevation is referenced to a benchmark for future use. This is necessary to determine the bottom elevation of the distribution cell. 4. Determine where the sewer lateral from the septic tank will connect to the distribution piping in the distribution cell. Place the pipe after tilling. The sewer lateral will be split with an approved distribution box centered in the distribution cell. Set 4 inch distribution piping adjacent to the distribution box and 50% of the distance from distribution box to the cell ends to provide equal distribution of effluent to each portion of the cell. All sewer laterals must have a minimum of 18 inches of cover for frost protection and have no dips into the distribution cell. 5. Cut trees flush to the ground and leave stumps, removing surface boulders that can be easily rolled off, remove vegetation over 6 inches by mowing and removing cut vegetation. Prepare the site by breaking up, perpendicular to the slope, the top 8 inches so as to eliminate any surface mat that could impede the vertical flow of effluent into the in situ soil. Chisel type plowing is highly recommended especially in fine textured soils. No rototilling allowed or moldboard plowing recommended. The important point is that a rough, unsmeared surface be left. The aggregate will intermingle between the clods of soil, which improves the infiltration rate into the natural soil. Immediate application of bt least 6 inches of aggregate is required after tilling. All vehicular traffic is prohibited on the tilled area. For sites where the effluent may move laterally, vehicular traffic is not recommended for 15 feet downslope. If rainfall occurs after tilling is completed, wait until the soil has dried out before continuing construction and contact the local inspector for a determination of damage done by rainfall. 6. Install the required observation pipes with the bottom 6 inches of the observation pipe perforated. Installations of all observation pipes include a suitable means of anchoring. See figure. 7. Place the remaining distribution cell aggregate in the component. Shape the aggregate to obtain a uniform minimum depth of at least 6 inches above the original grade. 8. Place the effluent distribution laterals on the aggregate. Connect the laterals to the distribution box. Install "Dial-a-Flow" adjusters on the outlets of the distribution box and set for equal flow. Lay the effluent distribution laterals level. 9. Place at least 2 inches of aggregate over the laterals. WATER TIGHT CAP (REMOVABLE) 10. Place approved geotextile fabric over the aggregate. FINISHED a"MIN.DIAMETER.PVC, 11. Place soil cover* material on top of fabric and extend GRADE SCR 40 ASTM 200Z the soil cover to the boundaries of the� uvuiiucari @5 vi r�a2 vva°..rdll component. OR EQUIV. 12. Complete final grading to divert surface water drainage SLOT(1I4 1rz°WIDTH, away from the at-grade. Sod or seed and mulch the entire OPPOSITE SIDES) at-grade component. 318"MIN.STABILIZATION BAR 6"MIN. OR WATER CLOSET COLLAR *The cover material means fertile soil(topsoil) with < 15% IN'FILTRA TIVE SURFACE gravel and no rock fragments > 3". Soil cover texture and structure shall provide adequate water holding capacity to OPEN BOTTOM sustain grasses to prevent erosion, promote runoff and FIGURE OBSERVATION PIPE allow air diffusion to the cell below. Soil finer than silt loam is not recommended.