1506 GRAND AVE 2018-01-02 MF Import

� March 14. 2010 I Addition to Stccvcs Rcsidcncc I_RtA .lob No. ]0-008 Pagc 4 � "I'hc Vashon till soil unit is dcposited dirccUy by glacial icc during thc most rcccnt glacial � period as il advanccd ovcr an croded, irreeular surface of older formations and sedim�nts. � lt is a vcry dcnsc mixture of unsortcd clay, silt, sand. gravcl. and scattered cobblcs and i boulders. ol'tcn referred to as "hard pan". The Vashon till over the top two to four fcet is normally wcathercd to a mediunrdense statc, and is moderately pcnncable and compressihlc. 'l�hc undcrlying Iresh till is vcry Jcnsc and is practically impcn�ious t�, stormwatcr intiltration. 'fhc frcsh till has thc strcngth of low-gradc concretc and can stand in a stccp nalural or cut slopc for a long period. If rcmains undisturbcd and wcll- draincd. Ihc fresh till can pru�idr exccllcnt Ii�unJatiun support ��ith littic sctllcmcnt cspcctr�i. 'I'hc ad�ancc uut��ash soil unit undcrl�ing thc Vashon till is comp�,scJ uf stratilicd sand anci gravcl with minor amounts of silt and clay, dcpositcd by thc mclt�vatcr of advancing glacial icc. Duc to thcir grncrally granular composition, thc ad��ancc out�vash dcposits arc of modcratcly high permcability and gcncrally drains fairly wcll. 'I'hc advancc outwash deposits are elacially overriddcn and arc gencrally densc to very dense in its natural, undisturbcd statc, except thc top 2 to 4 fect whcre exposed on slopes which ma�� bc ��cathcrcd to a loosc to mcdium-dcnsc statc. Thc advancc out�vash Jeposits can stand in slccp culs or natural slopcs liir cxtcndcd period ��hcn undisturbed. Whcrc cxposcd on ��opcs ��ith poor vcgctation cover and su�jcct to stonn runoff or groundwatcr sccpaec. tlic advance out�eash Jeposits can be gradually eroded and tnay sloueh and redcposit to a IlaUcr inclination. 'I�hc undcrlyine �i�csh ad��ancc out��ash deposits in thcir nativc. -_.. LIU & ASSOCIATES, INC. � �,�,; � > �