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1 __.. <br /> I January 14, 1998 <br /> (, <br /> ProJect No. G95103A <br /> � II. POTENTIpI, IMpACTS FROM GECILOGIC H4ZARDS <br /> � Our assessment of the potendal impacts of geologic and hydrogeologic hazards to the proposed <br /> ( commercial development is based on our presenc understanding of the proposed development and <br /> the existing site condidons. The pountial hazards presented by site development aze dependent, <br /> to a lazge degree, upon slope gradier�ts, ground water condidons, and the stratigraphy at the site. <br /> IBased upon the differences in slope, ground water, and straagraphy, we have subdivided the site <br /> into three geologic hazard zones as shown on Figure 3, and these zones are discusscd further <br /> below. Our;eoloeic hazards porrion of this siudy was limited to the impact of pountiai landslides <br /> i or mass-wasting, erosion hazazds, seismic hazazds and potential impacts to ground waur sources. <br /> f <br /> I6.0 LANDSLIDR HA7eRflC <br /> � The property has }rigfily differing landslide risks dependent primariiy upon t�slope gradients and <br /> waur condidons. Zone 1 (Figure 3) encompasses the upland areas where the commercial <br /> development is proposed. This zone is considered to have a low landslide risk potential. T7�is <br /> . upland area is characterized by gende to moderate slopes that are underlain by glacially <br /> ( conso:idated sediments at reladvely shallow depths. <br /> IZone 2 represents areas of moderate to high.landslide potendal and is located on the slopes <br /> adjacenc to the East Fork Powder Mill Creek drainage. Development in this area will be limiud <br /> to the upper portians of several drainage ravines in the western portian of the site which are <br /> Itributary to the East Fork of Powder Mill Creek. It is our understanding that preliminary <br /> development plans cail for filling the upper portions of these ravices in order to enlarge the <br /> developable portion of the site. It is our opinion thac the potential risk of impacts to tlse proposed <br /> ' development by landsliding that would result by filling in these areas is low provided that our <br /> recommenda6ons are properly followed. Preliminary conceptuat recommendations for placement <br /> of fill in these areas was provided in our letter entided 'Ravice Fill Concepts", dated December <br /> � 30, 1997. No other commercial development will occur in this area; therefon, no significant <br /> adverse unpacts due to development would be anticipated. <br /> IZone 3 comprises the steeply sloping areas adjacent to the Nazbeck Creek drainage ravine where <br /> abundant spring acuvity, soil creep, and evidence of past landslides were observed. These areas <br /> 1 aze considered to have a lugh to severe risk of landslides. Zone 3 is not coasidered f�r <br /> development. Therefore, significant adverse impacts co this zo�enviro�ent or to the proposed <br /> development are unlikely. <br /> � <br /> i <br /> 7 <br /> � <br />