3321 52ND PL SW 2016-01-01 MF Import

. -'t Geotechnical �ngineering [nvestigation � , Schwab Residence July 13, 2001 NGA File No. 329401 Page 6 the site, although we did not observe recent indications of this. The potential for sloughing may be reduced by routing surface water away from the top of slope, maintaining vegetation on the slope, and replacing vegetation removed during construction. With the recommended effective setback,these sloughing events should notadversely impactlhe residence. RECOMMENDATIONS AND CONCLUSIONS General It is our opinion that the soils, which underlie the site and form the core of the slope, are considered stable with respect to deep-seated earth movements, due to their inherent strength and slope geometry. There is potential for shallow sloughing and erosion events to occur on ihe steeper portions of the slope. We have provided recommendations to reduce the potential of such events and a minimum foundation effective setback distance to reduce the risk of adverse impacts to the residence should such events occur. The residence could be supported on conventional shallow spread footings, provided that the foundation excavation is advanced through any surficial fill, topsoil, or loose material and extended down to medium dense or Ixtter native soils. In addition to this criterion, the downhill footing line should be embedded a minimum of three feet into the competent native material and at the same time satisfy a minimum horizontal setback distance of 15 feet between the face of the slope and the bottom of the footing line. It will be important to maintain the vegetation on the slope to reduce the erosion potential. The occurrence of sloughing on the slope can be reduced by routing storm run-off into appropriate stormwater lines away from the slope or piping storm water to the base of the slope. The silry soils likely to be exposed during construction are considered moisture-sensitive and may disturb when wet. We recommend that construction take place durin� the drier summer months, if possible. If construction takes place during the wet season, additional expenses and delays should be expected due to the wet conditions. Additional expenses could include the need to esport on-site soil, the import of clean, granular soil for fill, and the need to place a blanket of rock spalls or crushed rock in the construction traffic areas and exposed subgrades prior to placing structural fill or structural elements. The on-site soils may be used as structural fill provided they could be compacted to plan specifications. We should be retained to determine if the on-site soils could be used as structural ill at the time of conshuction. After grading, the NELSON GEOTECHN/CAL ASSOC/ATES, /NC. $I/q