500 LAUREL DR 2016-01-01 MF Import

Geotechnical Erigineering Study 00-2267 Three Story Addition - 500 Laurel Street, Everett January 31, 2001 Page 3U considered low. It is, therefore, also our professional opinion that, on the basis of our observations and these analytical results, slope stability does not pose a significant threat either to the construction of the proposed addition, the existing residence, or to the long term in�egrity of the site or residence. Mitigative Measures: From the mitigative perspective, it is important that the drainage control measures described later in this report are installed as part of both design and construction a�id 4hat an appropriate long term maintenance program be set in motion on completion of construction. Wherever possible the site grades should be developed to drain away from the crest of the westem bluf` slope, as those in the area of the proposed addition do now. Any �vater c�llected in foundation excavations should be collected in a shallow sump pit and then be pumped to a positive and permanent discharge system such as a neart�y storm drain catch basin downgrade of the site. Additionally, any disturbed areas along t;�e crest of the western slope, or areas where "bare" soil is exposed, should be rapidly revegetated with a hydroseed mixture (grass seed and mulch with a tackifier). A.Itematively, these areas, if they occur, may be landscaped with an appropriate vegetative cover. One option for enhancing the long term seismic sta5ility of the addition is to install a series of small diameter, driven-in-place steel pin-piles. These pin-piles will help transfer the buildi��c, loads further de�� to the deeper :.nd generally more competent soils. Thus, in the event that a"catastrophic" landslide were to occur and the wedge of soil between the existing bluff crest and the house were to fail the support of the addition �vill not be detrimentally affected. For informational purposes we have provided geotechnical recommendations for the instaliation of a supplemental pin-pile foundation support system in Appendix C to this report. Buildin�Setback Distance Based on the subsurface data generated by our exploratory boring, and as suppiem�nted by ourgeotechnical data review, it is evident that the soils underlying the area of the proposed addition (as well as the existing residence) are generally firm, competent and unyielding in-place. Currently, the nearest point of the existing residence is twer,ty-three (23) feet away (roughly to the east) of the crest of the westem bluff slope. :+fter construction of the addition, as currently proposed, the