Koholalele Hamakua EA PBR Final TMK No. 4-2-005:001

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HAMAI<UA LAND SALE: I<OHOLALELE FINAL ENVIRONMENTAL ASSESSMENT 3.2 TOPOGRAPHY AND GEOLOGY Located on the slopes of Mauna Kea, the Site has an average slope of 12 %. Rocky gulches run from south to north, the length of the site. Soils within the Site derive from Mauna Kea Holocene and Pleistocene era volcanic rocks (Wolfe and Morris 1996). Soils are discussed in more length in Section 3.4 of this report. Potential Impacts and Mitigation Measures No significant impacts to the regional geology and topography are anticipated as a result of the proposed sale or any subsequent use of the Site. 3.3 DRAINAGE & SURFACE WATER RESOURCES The Site is bound to the east by Kainehe Gulch and to the west by Kawaili Gulch. Koholalele Gulch runs roughly down the center of the Site. Koholalele Gulch is also the name of the perennial stream that flows through that gulch with a perennial tributary that flows through Kawaili Gulch and an intermittent tributary also named Koholalele Gulch that flows through the middle of Parcel 5. The perennial stream that flows through Kainehe Gulch is a tributary to the perennial stream flowing through Kalapahapuu Gulch (see Figure 5) The Site is designated Zone X by the Flood Insurance Rate Map, indicating that the lands beyond the gulches are not floodplains (Figure 6). The lands contain no known drainage improvements. Potential Impacts and Mitigation Measures Clearing, grubbing, and use of the land for agriculture will likely alter the drainage patterns. As the Site becomes subdivided and populated by multiple owners, the "upstream" owner could have an impact on the "downstream" owner. The mitigation of such drainage impacts could be better coordinated if each owner diligently develops a conservation program "acceptable to the applicable soil and water conservation district directors ... providing: (A) Such operations do not alter the general and localized drainage patterns with respect to abutting properties. (B) A conservation program for the affected properties acceptable to and approved by the applicable soil and water conservation district directors is filed with the soil conservation district. (C) The conservation program, with appropriate modifications is reviewed and re- approved by the soil and water conservation district directors periodically but not less than once every five years." (Hawai`i County Code §10- 3(b)(5)). 3 -3