3313 OAKES AVE 2020-07-14 - Laserfiche WebLink

GeoTest Services,Inc. December 9,2016 3313 Oakes Avenue,Everett,WA Job No. 16-0659 temporary shoring, or if an easement can be obtained from the adjacent southern property owners to remove the retaining wall and thus acquire more room on the adjacent property to make the necessary excavation. We have provided geotechnical parameters for shoring design in a subsequent section of this report. Please note that our report is not intended to provide a formal design for any specific shoring type, and that ultimately the governing municipality or jurisdictional body that will accept the design. Along the northern part of the excavation for the proposed western building, the excavation would be removing soil from behind the adjacent northern retaining wall. As mentioned previously, we understand that the owner of the subject property also owns the adjacent northern property. At this point, it is not known as to whether or not the existing retaining wall will be removed as part of the new construction. If the existing wall will remain in place, it appears that the area behind the wall will be partially backfilled as the new building is constructed, in order to construct stairs along the northern side of the new building. If this is the case, it may be necessary to retain a structural engineer to evaluate the suitability of the adjacent wall to handle the additional surcharge (if any) based on the new construction. Regarding the proposed eastern building, the new foundations for this building would need to be extended into the native till soils such that the footings for the new structures would not exert a surcharge on the existing retaining wall on the eastern side of the subject property. To accomplish this, the footings should be extended such that a 1 H: 1V imaginary slope (or flatter) exists between the outside edge of the new foundation and the inside edge of the existing retaining wall foundation. A structural engineer should be retained to evaluate the existing condition of the retaining wall, and the adequacy of the wall for supporting additional lateral loads. Site Preparation and Earthwork The portions of the site to be occupied by proposed foundations and floor slabs should be prepared by removing any existing topsoil, old foundation elements (as found in TP- 3), deleterious material and significant accumulations of organics from the area to be developed. Prior to the placement of any foundation elements or structural fill, the exposed subgrade under all areas to be occupied by soil-supported floor slabs and spread or continuous foundations should be recompacted to a dense and unyielding condition and proof rolled with a loaded dump truck, large self-propelled vibrating roller, or equivalent piece of equipment applicable to the size of the excavation. The purpose of this effort is to identify possible loose or soft soil deposits and recompact the soil exposed during site excavation activities. Proof rolling should be carefully observed by qualified geotechnical personnel. Areas exhibiting significant deflection, pumping, or over-saturation that cannot be readily compacted should be overexcavated to firm soil. Overexcavated areas should be backfilled with compacted granular material placed in accordance with subsequent recommendations for structural fill. During periods of wet weather, proof rolling could damage the exposed subgrade. Under these conditions, qualified geotechnical personnel should observe subgrade conditions to determine if proof rolling is feasible. Page 5 of 17