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Home My WebLink About721043009 Geotech Assessment (2005) AddendumMay 16, 2006 John Nisbet 4817 Eaglemont Road Chimicum, WA 98325 STRATUM GROUP 1451 Grant Street, Bellingham, WA 98225 Phone (360) 714-9409 Re: Drain Field Issues on Slope Stability Proposed Development Lots APN 721-043-010, -001, -009, -014, -015, and -016 Jefferson County, WA Dear Mr. Nisbet: E ~: ., JEFfEflSOn~,UUNIr~I:~ In a previous report dated May 16, 2005 I provided you with a number of recommendations regarding development of the above referenced property located on South Point Road in Jefferson County on regards to slope stability. At the time of my writing the report there were no specific home development plans or septic drain field plans. This letter is a follow up on those recommendations in regards to the septic drain field above the northwestern limb of a deep- seated landslide complex described in my May 16, 2005 report. The building setback for the northwestern limb of the slide is 40 feet. It is my understanding that due to other constraints on the site a portion of the drain field will be within the 40-foot building setback. It is also my understanding that a pipe will be installed within the setback area above the northwestern limb of the landslide area. I visited the site in early May 2006 and assessed the slope and soils in the area of the proposed drainfield area and pipe. Due to soil types and slope, the installation of a drain field and pipe partially within the building setback area above the northern limb of the landslide area will not cause an increase in the risk of the slide movement. The slopes on this upland area above the northwestern limb of the landslide are towards the northeast to northwest away from the slide area. Therefore any storm water and drain field water generated will not be directed to the slide area. In addition the slope is such that any clearing in this area will not cause an increase of water impacting that landslide complex. Sincerely yours, Stratum Group ~' ~^ Dan McShane, M.S., L.E.G. Licensed Engineering Geologist