729 100TH ST SE 2018-01-02 MF Import

�� Pare T�•to Storn water currently enter3 the site frorn a compacted road and parY.in�� area to the north ( See photos "A^ and "B" ) . Upon entering the site, this water percolates into the ground and emer�ee at the pond ].evel after followin� a till contact under- lying the slope . (See attache�? topo€raphic w�� and �eneralized crose sections) , Additional water entera the siia from down- epouts on a:i ad3acent buil.ding (See photo "C" ) , Soi�Ls rr.cowr�ercd on �the s3te ?urin� exploration varied from �'ill Ri3!rrig18 on the fill terrace to the north to glacial out- vrash so� ls underlyin@ the ma�or portion of the proposed buildin site, a;•d to lacustrine deposits of silty fine sand overlain by peaty muck near the 3outhea.st corner of tne pro��osed buildin� site. Deep r.nd generally well drained loamy eandF and �ravels vrere encountered underlyine t!:e natural slope which trende nort - I easterly throuE;i the �enter cf the proposed building site. This slope is probably a tapo�raphic exprr.esion of this genarnlly � ] oose and es3ily e� odable unit. Pheto "D" ehovis surface condii- � I ions along this slot�e. Detailed ;s�il lopr• are appended to thie � report, as well as photograp}�e o^ sewe c� the test pite, The loamy sar.d and �anriy loam soile underlying the ma�ority o.f the eite are residuul, er"weathered oiit" soils vi',ich were de- rt� ed `rom the underlyir�g till. The til]. varies locally in tex- ture, tut �ener•ally exhibits a hi�h coarse frar.tion consistin� o� € ac.lally compacted stream deposits, The extent of weatherin in tlie ':ill depoeit is �imite��, su�gesting that it was deposite during tihe Vashon Stade of the Fraser Glncteti�n. The structure of the kil] depooit indicates that the p,laciEr overrode and com,,acted ite uut�u-3sh rlain in this area. It can te assumed that the er.fotine, trrraced topography r�=aulted from crvstal rebound durin� 9eg].aciatl.on. Ve€.etation encouritexcd on the site va.ries directly with soil and �roundwater corn'itions. Yiell drained end deeper soils eupp- orted fir and hemlo��ic, with ,n understory of bracken and salal. • b;ouerately drained soils with a hieh sea§onal water table supF•• orted elder an�l cedar Nith an understory of salmonber.~y and vit� maple. Foorly drqined soils supported cottonwood and willow, witt� an underotory of salmonberry. Di3turbed or fili soils supperted alder,cherry and an underotory of scotch broom and bleckberry (Rubis Diccolor) , P'ield Investigatior. � A field investigation was conducted on February �,12,14 and 19, � 19E5, and consieted of a tran�it and �tadia survey of relevant • featuree for refer.ence locations and elevations. Contour� were located and delinee, ;.ed at one foot intervals, and �pot elevatio ns were dete^mined at test pit locations usin� the sta�iia rud ir. cor�3unction v�ith a bub'�le level (See att-ach� d topo€ruphic map showing test pit locr�tions) . Teat pits were du@ with a Case SFOB �ehber tired backhoe et lo- — E'�Ai:� AMILYS/S l