Waipi'o Lookout Draft Environmental Assessment

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PART 3: ENVIRONMENTAL SETTING,IMPACTS AND MITIGATION MEASURES Basic Geographic Setting The parcel proposed for purchase is referred to throughout this EA as the Rice Property. The term project area is used to describe the general environs of Waipi`o Valley, Kukuihaele and the Hamakua District. The Rice Property is Iocated at approximately 910 feet in elevation near the Waipi`o Valley Lookout along Waipi`o Road,in the ahupua`a of Lalakea and the community of Kukuihaele of the Hamakua District(see Figs. 1-2). The site is a short distance from the shoreline pall(cliff), on the eastern rim of Waipi`o Valley, a dramatic"cathedral"valley. The vegetation of the project area has been previously disturbed by sugarcane farming,residential and other uses,and the Rice Property is covered with ornamental plants and secondary,weedy trees and shrubs. The average maximum daily temperature is approximately 78 degrees F,with an average minimum of 65 degrees, and annual rainfall averages about 40 inches(U.H. Hilo-Geography 1998:57). Adjacent land is primarily residential, with scattered agricultural uses and undeveloped lots. 3.1 Physical Environment 3.1.1 Geology,Soils and Geologic Hazards Environmental Setting Geologically,the Rice Property is located on highly weathered terrain of the Kohala Volcano, astride the steeply sloping side of Waipi`o Valley and near the shoreline pali. The surface consists of weathered basalt soils of Pleistocene epoch(approximately 60,000 years old) lava flows from Mauna Kea(Wolfe and Morris 1996). The Rice Property soil is classified by the National Resources Conservation Service(formerly Soil Conservation Service)as Kukaiau silty clay loam, a red soil of 20 to 30 inches thickness above highly weathered basalt. Erosion hazard is moderate for this soil,which was formerly used for sugarcane cultivation(U.S. Soil Conservation Service 1973). The entire Big Island is subject to geologic hazards, especially lava flows and earthquakes. Volcanic hazard as assessed by the United States Geological Survey in this area is 8 on a scale of ascending risk 9 to 1 (Heliker 1990:23). This relatively low risk rating is based on the long time since the area has been affected by vulcanism from either Mauna Kea or Kohala volcano. Volcanic hazard zone 8 areas have had only a few percent of their land area covered by lava or ash flows in the last 10,000 years. In terms of seismic risk,the entire Island of Hawaii is rated Zone 4 Seismic Probability Rating (Uniform Building Code, 1997 Edition, Figure 16-2). Zone 4 areas are at risk from major earthquake damage, especially to structures that are poorly designed or built, as the 6.7- 6 Environmental Assessment, Hawai`i County Purchase of Rice Property at Waipi`o Lookout