3206 WAVE DR 2016-01-01 MF Import

GeoTesl Services,Inc. June 3,2005 Baldwin Residence, 3206 Wave Dnve, Everett.WA Job No.5233 Wall Design Essentially one wall design was completed using AB Walls 2000, which can be applied to both the upper and lower wall locations. Due to the variabiiity of the sile condilions both walis were designed as a mechanically stabilized earlh (MSE) system. This system combines both the block units and a geogrid reinforced soil zone. Based on our interpretations of the existing site conditions the majority of both walis will need to be overexcavated in order to renove the previous wail backfill and any unsuitable soils or debris, hence the need for a MSE system. The southern portion of the planned wall localions will probably encounter medium dense to dense native soils within the designed reinforced zone of the wall. These areas will �eed to be overexcavated and replaced as designed in order to keep the wall sections consislent and in a stable orientation. Tapering out and termination oi the actual wall locations, into the native hill slope at the southern end, will need to be field fit as appropriate. A�ticipated lengths of the both the upper and lower walls are approximately 55 to 65 feet in the north south direction, Site and Exploration Plan, Figure 3. The backslope behind the walls was assumed to be level during design. We understand that the level bench between the lower and upper walis wili be landscaped. We recommend that watering of landscape plants with:n this area be restricted to controlied periods and performed by hand. We recommend against installing a sprinkler system or soaker hoses that can leak or be inadvertently left on. Native plants that do not need a significant amount additional watering are recommended. N'e also understand that a small Iandscaped area will be created at the top of the upper wall location as well. The same landscape recommendations as mentioned above would apply to the upper landscaped area. In addition this landscaped area will prevent direct vehicle loads at the top of the wall location. Therefore, vehicle loads (or surcharges) were not included in ihe parameters (or the compleled wall design. The wall batler is determined by the physical configuration of the blocks used. We understand that a three-degree block was originally purchased and will be reused in the new wall construction. Stability Analysis Stability analyses were preformed for the walls using limit equilibrium techniques to analyze the margin of safety against sliding, overturning, and global stability. The methods of analyses compute the ratio of forces (or moments) resisting movement, as compared to forces (or moments) tending to cause movement. We determinec, that the safety factors for sliding and overturning were in excess of 1.5 and 2.0, respeclively, which represents the minimum safety factors normally used for stability against sliding and overturning. Bearing capacity, assuming both walls are founded in suitable native soils or on a properly compacted import structural fill pad, was also analyzed and found to be sufficient for wall supporl. The resulting stable wall configuration is presented in the Allan Block wall design sheets attached with this report. Global stability anaiyses were also preformed on the two-tiered wall configuration as described within this report. The configuratio� assumed the lower wall at the same location as the existing lowest wall and the upper wail set back a minimum of 12 feel from the (ace of the lower wall at a height of approximately 10 feel. A computer slope stability program, WinSlabl, was used to determine factors of safety for the global slability of the proposed wall sections under both static and seismic conditions. The cornputer stability program was used to randomly generate and evaluate circular and Page:i oF 7 � �