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HomeMy WebLinkAboutBLD2006-00525 - Geotechnical Report Oct 17 06 11 :22a Gary Flower 206-3 -6545 p. 2 Gary A. Flowers, PLLC Geological&Geotechnical Consulting 19532 1.2"Avenue NE Shoreline,WA 98155-1106 October 17,2006 Project No.GF05078 Mr. Raymond Stelk 813 Thomdyke Road Port Ludlow,WA 98365 Subject: Geotechnical Report Addendum 813 Thomdyke Road Deck Addition Port Ludlow,Jefferson County, Washington Dear Raymond: As requested by Michelle Taylor, Jefferson County Department of Community Development, in her letter to you dated September 25, 2006, this letter provides our recommendations for construction of your planned deck on the east side of the existing residence. The existing residence is located near the top of a steep slope hazard area. As such, following the recommendations of the geotechnical engineer of record for the residential construction, Robert M. Pride, P.E., a 25 foot setback from the top of the slope was established for the residential foundations. The setback line was then physically staked to verify that the house construction did not extend into the setback zone. The setback stakes were still in place at the time of our last visit to the site in early September, 2006. Due to the top of slope angling in relation to the house, the house foundations vary from near 0 to about 6 feet away from the actual top of slope setback line. As per your plans submitted to us for review you are now planning on constructing a 10- deep by 20' wide deck extension off of the east side of the house. Foundation support will consist of two, 24" wide by 8" deep footings placed along the setback line. The deck will then cantilever beyond the footings. Based on your current plans, discussions with Mr. Pride, and on our observations while at the subject site, the deck construction will have no impact on the top of bank steep slope hazard or storm water impacts. Construction of decks that extend into setback zones is not an uncommon practice since they are independent of the residence. Furthermore, even though it is not your intention, it is our opinion that the foundations can be placed equal distance away from the residence without impacting the steep slope even though that would place one of the foundations a couple of feet within the setback zone. This will allow for more suitable support with less cantilevering and will result in a more stable deck. Gary A.Flowers,PLLC 19532 12th Avenue NE Shoreline,Washington 95155-1106 206-4�17-7640 I `Y�li v itc Oct 17 06 11 : 22a Gary Flower 206-31 6545 p. 3 • Raymond Stelk Drainage Letter 813 Thorndyke Road Geotechnical Services Letter Regardless of the footing configuration, the only requirement is that the footings must extend through any fill materials that may exist at the foundation location and must be placed only on medium dense or better,undisturbed,native sediments. Thank you for the opportunity to be of service on this project. Should you have any questions regarding this matter,please do not hesitate to contact our office. Sincerely, `�otWastiio io'° KIP 6(' 4'tI ,,e1Nrop,,4- wed Ge° Gary A.Flowers Gary A.Flowers,P.G.,P.E.G. Principal Engineering Geologist xc: Michelle Taylor,Jefferson County Department of Community Development 621 Sheridan Street,Port Townsend,WA 98368 R 1[4:,(TE.i VP T) JERE SON CCOtJNl OCO Gary A. Flowers,PLLC 19532 121'Avenue NE Shoreline,Washington 98155-1106 206-417_7640