1920 MERRILL CREEK PKY 2018-01-01 MF Import

I i SHANNON F�WILSON.INC. I The influence of human activity is evident at the Intrawest Seaway site. The eastern slope � of the site uas ex loited for borrow materials in the p past, such that some areas of the excavated slopes have been left wersteepened and other areas replaced with fill. IAdditionally, Sll was noted both on the upper plateau and at the toe of the existing eastern slope. I �_ 5.0 SITE RECONNAISSANCE AND ��.�pF rFnT nr,v The geology of the slope, as described belaw, is based on our field reconnaissance Iconducted on February 28, 1994. In genecal, five different materials were observed: 1) i Vashon till, 2) Vashon advance outwash, 3) colluvium, 4) landslide deposits, and 5) fill. � � Fach of these units is briefly described below. An ezplanation of slope conditions along the property is summarized in Figure 1. No groundwater seepage was noted on the slope during � our reconnaissance. I I 5.1 Vashon 'I511 i In the northem two-thirds of the slope area, the dil appears to be 20 to 30 feet thick, with Ithe base of the 611 ranging from about elevation 550 to 560 feet. Hawe,wer, in the southern + one-third of the slope, the till thiclaens significantly, to 100 to 110 feet thick. The transition in the thickness of the till appears to be at about the middle of the proposed south building (finished floor elevadon of 620 feet), as shown on Figure 1. The base elevation of the dll in this area is as low as eleva6on 535 feet. Where exposed, the dll stands near vertical, with some signs of erosion or weachering. I5.2 Vashon Advance Outwash ! Outwash comprises the lawer portion of almost the endre length of the slope. As discussed abwe, the elevation of the contact with the averlying till changes from north to south. The � outwash is quite permeable; however, it does not appear to be water-bearing, as verified by the lack of observed seepage on the subject slope during our reconnaissance. Although Inamerous sideslopes in this material are standing near-vertical, the outwash is often gullied or mantled by a thick layer of colluvium. T'he lack of significant fines or cementadon I W-6693-01 I 4