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Home My WebLink About938100430 Geotech Assessment~ - ~ a~Qa~-y,~ STRATUM GROUP 145 ! Grath Strezi, Bet!!nglwn, WA ~ Phone (360) 714-9409 March 7, 2005 Mary j>eVeneau 141 Sunset Blvd. Part Townsend, W A 98368 ite: F.agine+er~` Ceuloey Evttluatian Block 4, Lot 30 and 27, Sunset Btvd, E`.apc fteorge Port Townsend, Washington Hear Ms DeVeneau: t visited the above lots on February 1t5, 2405 w ctunlitativ+~ly c:v drainage issues on the slope of ~e pt~posed hoc site. It is my has been permitted an the so+rth lot and would be utilised by tt+~ purpose of the site visit was to assess the slope and soil s-tabitit; lot and provide recomrnetdations for devclopraent of the site. Dasod on my assessment of geologic conditions, the lot is not a failures. Fill soils and organic soils beneath the fill potentially i for a home on the site. This can be avoided by founding the hog the till and buried organic soils, It is my unclrrstanding that a d. being considered for this sits. 't'his type of foundation will be a f 11 soit and organic rich soit buried beneath the fill is removed foundation. Because of shallow gmund water within the soils az the site, nt be particularly important. I suggest that the daylight basement carefully designed to allow for complete drainage from behind daylight basc:tnent. This rgn bt accomplished in a variety of w~ fowsdation and slab walls and well draining gravel artci druinal the watts and beneath the stab fouutdation. As 1 suggested w yc my opinion that some over design of the drainage system wool may be entailed to ensure that the foundation remains dry. The additional drain rock and drain lines, snd I suggest thaz clean c lines so that they can be readily maintained in case of clogging (EULOGY 'Ibis geology description of the area is to provide scone Z~eck the site and why shallow ground water is present un the site. Northwestern Washington has been cx~c;upied by continental _ _. ___-- ._ y k F ^~~. ` ~ ~ a~ . ~i; .. -- ~,~ '~~ duate the slope stability and 4wclerseandin~r that a septic site. home on the north lot. The acrd drainage issues on the north risk of being impacted by slope told cause settlement problems e oa good bearing u~ils beneath yiight hr~.~ement foundation. is ~abte ai this site as tong as all rriOf to l~flSd't~tion Of ihC ~tiun to foundation drainage will undation drainage system be ~ back wall and slab floor of the s inc;tuding well sealed lines placed along the outside of at the tune o€ my site visit, it is be well worth the extra vests that xtra design could include l risers be provided for the drain rcgenling the. conditions at ten at feast four times during ..~ . Mich ~, 2005 Sunset t3ivd i:ak cotta (;eorge, Wk (ie6lOgy /l35{C5~11~IIt ~e Pleistocene Epoch (1:6 million to 14,ta00 ycars agci}. During interglacial periods, the underlying bedrex;k was deeply eroded: the Port Townsend 30- by 6t1•--Mi>vute Quadrangle, Puget Soumc! pethicr, Boot and Muiard, 1911;9) aqd the Geologic Map of Nort (Gayer, 1976) indicate that the subject property is located neat t outwash deposits and underlyi»g glacial and nonglacial sodima on the sub~cct property and in the vicinity are wnsistent with th The slopes above the property appur to be uruitxlain ~imariJy deposits. Sand and gravel and silt iri a very compact condition ~ No silt or clay layers were obsetwod within the ditch on the sub very compact clays on along the shoreline below the subject pr the vicinity. Advance outwash deposits were deposited by melt water stn We area. The outwash exposed in th$ area is predominantly outwush deposits tend w grade finer towards the bast of the ~~ ~{~ ~ --- -'~ ;t.~' ~ :i~':~~ .. . base glacial ~ ai;s:tiinpanyint 'lte Surficial Geologic flap of region, VVashingtan (f'essl, ~a,tsrn leffersun Bounty e contact betw~eea advance u'Y depocity. Site abscrvations above-descr+t~ed mapping. sand. and grout! outwash pr~esa~t can the subject p*~>~y t proP~y. but 1 have observed ;riy and on c>ihEr properties in as the glacial ice advanced over and gravel. However, acivarx:e Layered sibs and cif and some fine sand layers all in a vety c pact conditicxc underlay the advance outwash on the steep sharcfirre slope to the- south of subject property and silts and clays in a very compact condition are present along the slxxnii ~ below tha subject property. 'i'hc silts and clays are consistent with the descriptions of'thc Kitsap P~ormation. 7"he prew~nct of sibs and clays within the either the lower part f the outwash deposits or the upper portions of the preglacial depaa~its is the likely cause of s !low ground w,slCr bt;ing present at the site. The well drairicd sand and gravel outwash deposits the slopes above the subject property allow for hydrostatic head sorb that the water caa re the proposed building site even though a cut offtrench lias been excavMed behind the :..building site area. We appreciate the opportunity to be o!'servicc to you. Should our reeonnaissanc:e please contact our olTcc at (~60) 714-9409 Sincerely yours, tt~ Grvnp . G~,~~~ t>an McShane, l...ir.G., M.Sc. Licensed Engineering Geologist timrwn troop have any questions regarding Fik: ~.iy.us 2