330 ELM ST VIEW RIDGE ESTATES 2022-04-04

• Geotechnical Engineering Evaluation NGA File No. 1085419 View Ridge Estates 330 Building Settlement March 22,2019 Everett,Washington Page 5 Erosion Hazard The criteria used for determination of the erosion hazard for affected areas include soil type, slope gradient, vegetation cover, and groundwater conditions. The erosion sensitivity is related to vegetative cover and the specific surface soil types, which are related to the underlying geologic soil units. The Natural Resources Conservation Service (NRCS) lists the erosion hazard unit as Alderwood-Urban land complex, 2 to 8 percent slopes for the subject area in Snohomish County. The erosion hazard rating is listed as slight. We would interpret this site as having a low to moderate erosion hazard where the surficial soils are exposed. It is our opinion that the erosion hazard for site soils should be low in areas where the site is not disturbed. CONCLUSIONS AND RECOMMENDATIONS General In our opinion,based on our observations and our understanding of the prevailing building conditions,the settlement and distress to the building is a result of long-team consolidation (settlement) of the undocumented fill that was encountered in our explorations and is interpreted to underlie portions of the building foundations. It appears that this fill was likely placed during the initial development of this property. Due to the varying nature of the overall density of the fill encountered in our explorations, it is likely that some of the fill material was placed in a loose condition at the time of building construction, and throughout the years has been settling under the building loads. Some of the most significant building settlement was observed within the eastern portion of the building. It is likely that the foundations will continue to experience some subsidence under the current conditions resulting in additional settlement, which could lead to more distress to the foundation and the structure if this condition is not mitigated. To mitigate future settlement we recommend that the eastern and portions of the northern and southern building foundations be underpinned with driven 2-inch pipe piles or helical anchor piles. The extent of the northern and southern underpinning should at a minimum include the western portion of the structure where the crawlspace area begins. The piles should support the exterior and interior foundation elements. Your structural engineer should determine the extent of foundation areas to be underpinned and overall layout of the underpinning system. Portions of the residence may be able to be re-leveled during construction under the direction of the structural engineer and the contractor, however this may cause significant disturbance to structural features of the building such as the exterior brick veneer, windows, doors, etc. We did not observe the conditions of the slab or soil conditions below the slab, however, slab settlement could also be mitigated using pipe or helical piles. Alternatively, if some future slab settlement could be tolerated,the upper 12-inches of soil directly below the slab could be removed and replaced with granular structural fill. The slab would have to be replaced under this scenario. These recommendations 8119 NELSON GEOTECHNICAL ASSOCIATES, INC.