4937 SEA BREEZE WAY 2017-01-13 - Laserfiche WebLink

� � Geotechnical Engineering Evaluation NGA File No. 916915 Pepe Retaining Wall April 27, 2015 Everett, Washington Page 9 The site soils are generally considered to be very moisture-sensitive and will disturb when wet. We reco�mnend that earthwork take place during dry weather if possible. However, if construction takes place dw�ing the wet weather, additional expenses and delays should be expected due to the wet conditions. Additional eYpenses could include the need for placing a blanket of rock spalls on exposed subgrades, constr�iction traffic areas, and paved areas prior to placing structural fill. NGA should be ret�tined to evaluate the suitability of all on-site and imported structural till material during construction. Temporary Slopes 'Teinporary cut slope stability is a function of many factors, including the type and consistency of soils, deptll of the cut, surcharge loads adjacei�t to the excavatioil, length of time a cut remains open, and the presence of surface or groundwater. It is exceedingly difficult �mder these variable conditions to estimate a stable, temporary, cut slope angle. Therefore, it should be the responsibility of the contractor to maintain safe slope configurations since he is continuously at the job site, able to observe the subsurface materials and groundwater conditions encountered and able to monitor the nature and condition of the cut slopes. The following information is provided solely for the benefit of the owner and other design consultants and should not be construed to imply that Nelson Geotechnical Associates, Inc. assumes responsibility for job site safety. Job site safety is the sole responsibility of the project contractor. For planning purposes. we recommend that temporary cuts in the on-site soils be no steeper than 1.5 Horizontal to 1 Vertical ( I.SH:1 V). If signiticant groundwater seepage or surfiace water flow were encountered, we would expect that flatter inclinations would be necessary. We recommend that cut slopes be protected from erosion. The slope protection measures may include covering cut slopes with plastic sheeting and diverting surface runoff away from the top of cut slopes. We do not recommend vertical slopes for cuts deeper than four feet, if worker access is necessary. We recommend that cut slope heights and inclinations conform to appropriate OSHn/WISHI-� regulations. Structural Fill General: After the wall has been repaired and the loose soils found behind the wall have been over- excavated, baekfill should consist of pit run placed as struct�iral till. Structural fill, by defiinition, is placed in accordance with prescribed inethods and standards, and is inonitored by an experienced NELSON GEOTECHN/CAL ASSOC/ATES, INC.