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i <br /> 1 <br /> I TA3LE 2: K FACTOR FOR UNIVERS,aII, SOIL LOSS EQUATION <br /> ( A�M� ��r �� � C�. : <br /> � � ��>� <br /> � �< , � <br /> �� „ `� ��F <br /> �•'_ <br /> � Advance Outwash 0.10 0.14 <br /> • Lodgement Till p.2p 0,28 <br /> � Pre-Vashon 0.32 0.32 <br /> IBased on our understanding of the proposed development azea, the on-site soil and slope <br /> condidons, the fine sediment transport potential would not be considered unusually high for the <br /> Puget Sound region. This rela[ive:y minor erosion potential, however, can be further mitigated <br /> � through crosion control measures as described in the Erosion 14tidgation section of tlas report. <br /> I � =,l y Erosion m,�a c <br /> Areas underlain by advance outwash (Qva) on low to moderate slopes aze considered to have a <br /> Imoderate to high susceptibility to gully erosion (Zone 2, Figure 3) if surface drainage were <br /> allowed to concentrau. The moderace to high gully erosion suscepdbility of these sediments can <br /> become severe in the steeply sluping ravine azeas of Zo� 3. <br /> � <br /> 8.0 I MI HA?ARnS <br /> � Earthquakes occur in the Puget Lowland with at re <br /> 8re gularity. The vast majority of these events <br /> I are sma11 and aze usually not felt by people. However, lazge earthqualces do occur as evidenced <br /> by the 1949, 7.2-magnitude event and the 1965, 6.5-magnitude event. The 1949 earthquaice <br /> appears to have been tne largest in this area during recorded history. Evaluation of earthqUake <br /> Iretum rates indicate tl�at an earthquake of the magnitude between 5.5 and 6.0 likely will occur <br /> , within t6e next 8 to 12 years. <br /> , Generally, there are four types of pocential geologic hazards associated with lazge seismic events: <br /> i 1) su�cial ground rupture; 2) seismically induced landslides; 3) liquefaction; and 4) ground <br /> motion. The potential for each of these hazards co aduersely impact t6e proposed project is <br /> � discussed below. <br /> I $•1 Surficial Ground Ri�t��re <br /> Generally, the largest earthquakes that have occurred in the Puget Sound area aze sub-crustal <br /> events with epicenters ranging from 50 to 70 kilometers in depth. For this reason, no sutficial <br /> � faulting, or earth rupture, as a result of deep, seismic acdviry has bcen dceumented, to dace, in <br /> this portion of Snohomish County. Therefore, it is our opinion, based on existing geologic data, <br /> � that the risk of surface rupture impacting the proposed project is low. <br /> 9 <br /> � <br /> � <br />