6300 MERRILL CREEK PKY BASE FILE 2018-01-01 MF Import

Quadrant JN 97092 August 13, 1997 Page 7 Dra(naae Considerations We recommend the use of footing drains at the base of footings where a slab is below the outside grade, or the outside grade does not slope downward from a building. Drains should also be piaced at the base of all backfilled, earth-retaining walls. These drains should be surrounded by at least 6 inches of 1-inch-minus, washed rock and then wrapped in non-woven, geotextile filter fabric (Mirafi 140N, Supac 4NP, or similar material). At its highest point, a perforated pipe invert should be at least as Iow as the bottom of the footing, and it should be sloped for drainage. All roof and surface water drains must be kept separate from the foundation drain system. A typical drain detail is attached to this report as Plate 10. For the best long-term performance, pertorated PVC pipe is recommended for all subsurtace drains. The excavation and site should be graded so that surtace water is directed off the site and away from the tops of slopes. Water should not be allowed to stand in any area where foundations, slabs, or pavements are to be constructed. Final site grading in areas adjacent to buildings should slope away at least 2 percent, except where the area is paved. Pavement Areas All pavement sections may be supported on competent, native soil or structural fill, provided these soils can be compacted to a 95 percent density and are in a stable, non-yielding condition at the time of paving. Native soil cannot be tested for a density percentage, but it should be in a non- yielding condition. As noted in the General section of this report, pit-run gravei and geotextile fabric may be needed if paving is not done in the normally dry summer and early fall. We recommend using Supac 5NP, manufactured by Phillips Petroleum Company, or a non-woven fabric with equivalent strength and permeability characteristics. Pit-run gravel can also be used to stabilize soft subgrade areas. In most instances where unstable subgrade conditions are encountered, 12 inches of gravel will stabilize the subgrade, except for very soft areas where additional fill could be required. The subgrade should be evaluated by Geotech Consultants, Inc., after the site is stripped and cut to grade. Recommendations for the compaction of structural fill beneath pavements are given in a later sub-section entitled General Earthwork and Structural Filt. The pertormance of site pavements is directly related to the strength and stability of the underlying subgrade. The pavement for lightly-loaded traffic and parking areas should consist of 2 inches of asphalt concrete (AC) over 4 inches of crushed rock base (CRB) or 3 inches of asphalt-treated base (ATB). We recommend providing heavily-loaded areas with 3 inches of AC over 6 inches of CRB or 4 inches of ATB. Heavily-loaded areas are typically main driveway�, dumpster sites, or areas with truck traffic. Where the subgrade is composed of silty, water-sensitive soil and irrigated landscaping is adjacent to and at an elevation higher than the pavement, we suggest installing perimeter drains to intercept the water lhat would otherwise saturate the pavement subgrade. The pavement section recommendations and guidelines presented in this report are based on our experience in the area and on what has been successful in similar situations. Some maintenance and repair of limited areas can be expected. To provide for a design without the need for any repair would be uneconomical. GE01'ECH CONSULTAMS,MC.