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P PART 3: ENVIRONMENTAL SETTING, IMPACTS AND PROPOSED MITIGATION MEASURES 3.1 Basic Geographic Settiniz Land use /cover in the area proposed for the park currently consists mainly of lawn, trees, and streets with asphalt -paved through lanes and diagonal parking stalls. Weedy trees immediately border the river for most of the project's length, most of which have grown during the last several decades. Plans call for removal of most of this vegetation in order to provide space for the park and to open up views of the river. However, several outstanding trees including coconuts and the large banyan immediately mauka (southwest) of the Keawe -Puueo Bridge will not be removed, as they contribute to the scenery of the river front. Figures 3a -d are photographs of the proposed park from the Keawe -Puueo Bridge; Figure 3e is a photograph from viewpoint of the Hilo Armory, with the section of Wailuku Drive proposed for closure in the foreground and the vegetated river bank in the background, revealing how the banyan and octopus trees block views of the river. The long, narrow site is adjacent to and perched above the estuary of the Wailuku River, at elevations between 10 and 60 feet above mean sea level. It is bordered by Wailuku Drive, and has moderate slopes facing inland and steep slopes (including sheer cliffs) facing towards the river. The surface geology of the site consists of prehistoric basalt flows of the Kahuku Series from Mauna Loa. In places the surface is covered with weathered Pahala Ash of variable thickness (MacDonald et aI 1983:350) . The soil that has developed on the ash - mantled lava is classified Hilo Silty Clay Loam. This soil has a dark - brown, highly acidic surface layer about 12 inches thick overlying a subsoil that may be as deep as 48 inches. Rock outcrops are also present. On areas of steeper slopes, the soil erosion hazard changes from slight to moderate. Permeability is rapid and runoff is medium (U.S. Soil Conservation Service 1973). Annual rainfall is approximately 130 inches (Giambelucca et al 1986). 3.2 Physical Environment 3.2.1 Drainage Environmental Setting According to Flood Insurance Rate Map (FIRM) Panel No. 155166 0880C, essentially all of the site makai (seaward) of the Keawe -Puueo Bridge is located within Flood Zone VE (see Fig. 2). This zone is the Special Flood Hazard. Area inundated by the 100 -year coastal flood with velocity hazard (wave action); base flood elevations are determined.