SBCT Final EIS - Govsupport.us

Chapter 3 ⎯ Affected EnvironmentThe trail continues upslope over Kawaihae extremely stony very fine sandy loam on slopes of 6 to12 percent, eventually crossing the former Lalamilo Firing Range, just below a rock wall, and followsthe western boundary of the Puu Pa Military Maneuver Area (Earth Tech 2002). Kawaihae extremelystony very fine sandy loam also lines the gulches along the portion of the trail near Kamakoa Gulchthat turns upslope along the southern boundary of the Puu Pa Maneuver Area toward the Saddle RoadJunction. Kawaihae soils have a very weak structure and crumble easily. The soils are used primarilyfor grazing and occur at elevations of up to 1,500 feet amsl on the leeward side of Hawaii, where rainfalllevels range from 5 to 20 inches.The trail crosses about 1 mile of Puu Pa extremely stony very fine sandy loam on 6 to 20 percentslopes at about the 1,600-foot amsl elevation contour. Although Puu Pa soils are similar in characteristicsto the Kawaihae soils, they are distinguished from Kawaihae soils primarily by their occurrenceat higher elevations on steeper slopes in areas receiving higher annual rainfall. Permeability is moderatelyrapid and runoff is medium. At an elevation of about 1,900 feet amsl, the trail turns abruptlysouth again for about 4 miles, following an existing unpaved track for about 2 miles, and then continuesabove the 1,800-foot amsl contour, where there is no existing track, until it intercepts a pavedroad. The trail continues upslope along the paved road for a distance of about 4 miles alongside AuwaiakeakuaGulch, to the Auwaiakeakua Water Tank at Highway 190. The soil along about the last7 miles of this segment is mainly Waikaloa very fine sandy loam on 6 to 12 percent slopes, interspersedwith Puu Pa and Kamakoa very fine sandy loam on 6 to 12 percent slopes, and encountering ashort segment underlain by Kaimu extremely stony peat on 7 to 25 percent slopes. A strongly cementedlayer containing calcium carbonate occurs in most locations at a depth of about 4 feet. Waikaloasoils also exhibit characteristics similar to those of Kawaihae soils, but occur on slightly steeperslopes where rainfall levels are slightly lower. The Kaimu soil is formed in organic material mixedwith minor amounts of basic volcanic ash in aa lava, occurring in areas where the mean annual rainfallis about 35 inches.About 3 miles downslope from the 1010 Parcel, at an elevation of about 4,300 feet amsl, the trailcrosses Kilohana loamy fine sand on 12 to 20 percent slopes formed in material weathered from volcanicash, interspersed with very stony land. Kilohana soils are very highly permeable, runoff is slow,and outcrops of aa lava flows are common. In the 1010 Parcel, the trail intercepts Keekee Road, anunpaved road that runs along the northwest side of Puu Keekee cinder cone, where the soils are classifiedas cinder land.Erosion ManagementAs described previously for SBMR, USAG-HI conserves and manages soil resources on PTA bymanaging for natural rates of runoff, erosion, and sedimentation. The INRMP for PTA for 2002 to2006 identifies installation-specific goals and management objectives of the ITAM Program for PTA(USARHAW 2001b). Erosion management strategies are similar to those implemented under theINRMP for Oahu, with the exception that site hardening involves putting down crushed lava to allowuse of the area without degradation of the surrounding area. Restoration of artillery firing points hasbeen the major area of emphasis for the LRAM program on PTA since 1996. Some of the firingpoints have become denuded, resulting in vegetation loss and subsequent major erosion and dust issues.PTA soil substrates are primarily fine, volcanic ash prone to wind erosion and dust generation.Chemical Constituents in SoilsThe USACE, Sacramento District, conducted a surface soil and surface water investigation at PTAbetween November 12 and November 14, 2002 (USACE 2002d). Samples were taken to collect datain order to establish baseline conditions for human health assessments for range exposure. Similar toFebruary 2008 3–15 2/25th SBCT Final EIS