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Home My WebLink About502104006 Geotech AssessmentO N 1 3 4 5 J O H N S T O N R E A L T Y ~. ..: • . :. C MC SQUAKED i\ E o A- O S A 7 E D October 12, 1994 b?r. John Dowd 130 Pleasant Harbor Road Hrinaon, Washingtors3 98320 RE: SLOPE STABILITY AND >ICSr2axxaxma w~zn. aasxam Dear Mr. Dowd: X62. ~o~{ PUoG2 7217 EAST 41n AVE SUttE 202 OLYMPU, WA 95508 (2081754•A739 FA1(1206)352.204a -. Caturday, 0etob~r 1, iP94, I vioitod your proporty lecatad on Pleaaant Harbor Road near Srinhon, waahington. You were present 3u~:irast my visit. The L>.ti yaee a£ this vS e:i.t was tv cveluete tIac soil and stability of the elope above your building site. in addition, I have reviewed the plans provided by Mike Martin. Zn addition to the site visit, I have reviewed the retaining wall plane provided by Mike Martin for your new workshop, xncludcd with thin lcttcr aro otalculatione and o]sctchce of a retaining wall and concrete wall for the workshop. In order to make the work®hop wall work propezly, the end walls of the wnrkFhop should have at least 6 feet of concrete wall. Please see ekBtohei 1 trirOUgri S for the work shop and aketah 6 tOr trie retaining wall. If you wish to include a door or window ink the concrete wall either end of the shop, extend the wal3 by a minimum of 2 feet. ~- door or window may then be included. You should have {2) #5 reinforcing bare on each Bide {tap, aides, and bottom) of the opening. Vertical bare should be full height. Horizontal bars should extend at least 2 feet past the corner of the opening. In additiexs, wo reootnmcrd that you hnvo at lcaot (i) k5 diagonal bar 4 feet long locates at each corner; elope the diagonal bar at 45 degrees. The re.,t of the details will remain unchanged. Mhn dA~ 1 a nl~eswrn,i ~• }r.~,.r 7.ak sire st+. nvet n._.n anli. d.:.r:eA F(.,q gravely, sandy, silt and silty sands. These sails are highly -- page 1 -- STRUCTURAL • FOUNDATION • CIVILENCINEERS O N 1 3 4 4 S O H N S T O N F2 E A L T Y F 0 3 consolidated and were observed to be holding slopes in excess aE 1 horizontal to 1 vertical. Examination of the road way above the slope found no evidence of slope instability. There wre~~e no cracks in the road beds there was no pattern of "pistol b'utting~~ in tlae traco~ aor wcrc say other typical signs of soil instability observed. Zt was evident that some surface movement is occurring. This is attributed to erosion, freeze thaw, and to some soil creep. ' I reaommand that you take the following provi3iono: 1. Design the conerate shop wall to carry a soil load of 4D pcf. (See the enclosed calculations and sketches.) ~. Limit thakhoight of fill L-ehind tlia wall Lv 5 LecL B inches. 3. Use level back fill from the shop wall to the existing hill side. 4. Treat the shop wall extensions as retaining walls and limit fill height to S feet a inches. to design ana detail are included.) 5. Back fill with a mix of clean sand and gravel. loots of the fill should be less than 2 inches in diameter. Not more than 1D1r of the material should pass a #100 sieve. Not more than 2& should pass a #200 sieve. C . Do r.ot plaoo any baok Sill until the S1oor is is place sad tho plywood io properly nailed. 7. Frovide good drainage. t3se a 6 inch diameter perforated pipe behind the wall. This pipe should be sloped to drain. ail oz the roof drainage should ne oollcoted in a separate tight line and routed to a disnoazl i7^P.A. A1~ nP tho Dir+AF +~ho+.t'1!1 he roate~ to a location where water may be disposed of without softening the hillside or causing erasion. The pipes should be staked to the ground 'at about 4 feet on centers to prevent movement or joint failure. The pipes should be inspected annually for leaks and promptly repaired as necessary. 8. Plant the existing slope with a drought resistant material and protect it from erosion. 9. zn the event that soil should slide from the face of the slope, remove 3t so as to maintain the clearance from the top of the fill to the top of the wall. -- page 2 -- O 1~ 1 S Z~~ 1 = J O M I~ I C T O! 1 R E n L T Y P ~ 13 10. Plant the £i11 with grs~oa or low growing chruba. Uo not plant trees in the.Ei3.l material. Ynu rhould uridoxeltAS-d Ghiie the ex'aa.iaeipioap azad judgmcritd m~ada in this report are :baeeki 'updn vis~ial' ,examination of the site and a single visit. IIt' gvalitati~Ye "i:l place soil density wscs estimated by probi,~g with a 0 5" . diameter. smooth rod with s laenwiesst>lilna~iurl Lly A'i:ii l:ula~vvlllu.xL~uu w:>b~Lncseaal c~aa +.inu,i.l died tactical manipulation of the so3,l. No calculatiana, monruromonta, 1abp;atom toatr, etc. 'hAVp:bCCri made except pia ry.escitieally aat~od' glxve. ,ilue :a a:eault this rcpoLt is isahcrorctly raa'~r3,o'ped Say tho t~~ c£ information available. xo rr111 be pia,e}oa3+"po" ~rapare n prbpbadi ' for a more detailed analysis if you~'a+i~h•, IC ib our optnoxa ;~baC ••Che plops ,im}us@i~1;e3.y adjacent ty your praposed work :shop b. rslatively rtab~s.' With adequa a pratection of th3 slaps 3n~ the"ties of 'the concrete wa1 s deaigl~,ed the structure ekould g4ve adequate aezvice. You a8ou d understand that:; the wallp :desigii~~ are ri•tended to provide protection to tYiel toe d~' the aYope; they'are not intended to +4+Nah:i7.i~a thw,~i-+ln~~n7.emw. Tn thq. f•v,~ni-,~;f•in ~nin}7 ornainn nr Qlideta, AdditSOX1Ai ~OrIC •Wlll Y1CCd tO bC 'dO11C. If you hmvr say qunatono, or £f I may b® of further help, rtawmlo t~n19 ma';IVt;, Z.^.46) 75d-giRA. Sincerely yours, MC'sQVARfib, INC. ' ~... Vince McClure, PE, Ph. fl. -- page 3 .. € '~ ~ ~ '.