1921 W MUKILTEO BLVD 2018-01-02 MF Import

Preliminary Geotechnical Engineering Evaluation I 1919 Mukilteo Boulevard October 20, 2005 NGA File No. 718805 Page 14 We recommend the use of footing drains around structures and behind retaining walls. Footing drains should be installed at least one foot below planned finished floor elevation. The drains should consist of a minimum four -inch -diameter, rigid, .slotted or perforated, PVC pipe surrounded by free -draining material wrapped in a filter fabric. We recommend that the free -draining material consist of an 18-inch-wide zone of clean (less than three -percent fines), granular material placed along the back of walls. Pea gravel is an acceptable drain material or drainage composite may be used instead. The free -draining material should extend up the wall to one foot below the finished surface. The top foot of soil should consist of impermeable soil placed over plastic sheeting or building paper to minimize surface water or fines migration into the footing drain. Footing drains should discharge into tightlines leading to an appropriate collection and discharge point with convenient cleanouts to prolong the useful life of the drains. Roof drains should not be connected to wall or footing drains. USE OF THIS REPORT NGA has prepared this report for Mr. Philip Johnson and his agents for use in the planning and design :,f the development planned on this site only. The scope of our work does not include services related to construction safety precautions and our recommendations are not intended to direct the contractors' methods, techniques, sequences, or procedures, except as specifically described in our report for consideration in design. There are possible variations in subsurface conditions between the explorations and also with time. Our report, conclusions, and interpretations should not be construed as a warranty of subsurface conditions. A contingency for unanticipated conditions should be included in the budget and schedule. All people who own or occupy homes on hillsides should realize that landslide movements are always a possibility. The landowner should periodically inspect the slope, especially after a winter storm. if distress is evident, a geotechnical engineer should be contacted for advice on remedial/preventative measures. The probability that landsliding will occur is substantially reduced by the proper maintenance of drainage control measures at the site (the runoff from the roofs should be led to an approved discharge point). Therefore, the homeowner should take responsibility for performing such maintenance. Consequently, we recommend that a copy of our report be provided to any future homeowners of the property if the home is sold. NELSON GEOTECHNICAL ASSOCIATES, INC.