4704 HARBOR LN 2018-01-02 MF Import

r erosion channels next to them and described in the Nelson report, it appears that much water came down the hillside from these broken i The hmmg question is were t t�tpes ro en by t e landsh a or was rt the f tree falling staff that damaged them so that when the irrigation pipe began leaking, the subsurface water collection system only brought the excess water to a middle point on the slope? If this was the case, then the Anderson directed tree cutters created the landslide as well as the leak. • Report says "...erosion hazard for the on -site soils is listed as high, but the actual hazard will be dependent on how the site is graded and how water is allowed to concentrate..." (p 15), there is no plan or discussion of how this is being performed. Where are the design drawings for the site restoration and the wall? The Restoration plan does not contain drawings or details. • On pages 19 and 20, the report says to '...remove the vegetative cover and slide debris directly below the wall to a depth of four to six feet, benching the slope below the wall to a gentle inclination, placing rock spalls to buttress the slope in selected locations, placing erosion control matting on all exposed surfaces on the slopes, installing shallow drains to control surface and subsurface water flow, and re-pla(n)ting the slope with deep-rooted vegetation... areas of sloughing and slide debris would be over -excavated down to competent material and 4-foot wide benches created in these area.' My question: is this to be done on the adjacent Chase properties and if yes, how? This recommendation / requirement appears to remove much of the slide debris. Is this true? Is this work needed to allow for the stability of the soldier pile wall? More explanation is needed. • On page 20, the report states that drainage pipes should be "...routed to the bottom of the slope or to an appropriate discharge location." This is an interesting; requirement since the Professional engineer does not point out that muting water to the bottom requires obtaining access agreements or illegally trespassing on adjacent property. No discussion of the collection the water and routing it toward the public storm drainage in the street on the opposite side of the Anderson's house is ever presented or discussed. • Also, none of the pipes down the hillside had any form of energy dissipaters at the end. We agree with the gcotechnical engineer that this feature is mandatory. • The tenn "...deep-rooted drought -resistant plants..." is used several times in the recommendation / requirement section of the report yet, if the loose unstable soil, "...below the wall..." is removed then why is the requirement of the deep rooting plants? • Where are the civil / structural drawings of the wall and its relationship to the property roes. at are the setbacks and the :trial grading? How does the designer treat tie ends of the proposed wall so that additional or progressive failures do not occur beyond the ends because surface water is being directed around the ends'? The design must detail how the ends are stabilized and how the elements tic smoothly into the existing hillside. r-Wfty is a wall the only repair � There was no wall before the slide and there are no other walls in the inmiediate neighborhood, so why is restoring the hillside with a soldier pile wall the only proposed repair option? The placing of stabilizing rock riprap, like the highway department does, could also be an option 1109 1" Avenue, Suite 501, Seattle, Washington 98101 Phone: (206)588.6200 Fax: (206)588-8201 Page 2 7/16