Figure 1. Water balance of a vegetated plot. Plants extract water from throughout the soil profile, to depths that may exceed 2 m in deep soils. In contrast, most water lost by direct evaporation comes from the upper 0.2 m of soil. The combined loss of water by direct evaporation and transpiration by plants is called evapotranspiration. For level, vegetated plots having deep soils in semiarid regions, run-on, runoff, and drainage are negligible, and evapotranspiration will equal precipitation on average over yearly intervals. F-1
30 INEEL (1500) [45] 5.6 C 217 mm 60 Temperature (oc) 20 10 0 40 20 0 Precipitation (mm) -10 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Month Figure 2. Climate diagram (sensu Walter et al. 1975) for the Idaho National Engineering and Environmental Laboratory (INEEL) based on data for 46 years from the Central Facilities Area (U.S. National Oceanic and Atmospheric Administration, Idaho Falls, Idaho, unpublished data). Solid curve depicts mean monthly precipitation; dashed curve shown mean monthly temperatures. Vertical hatching indicates periods when precipitation generally exceeds potential evapotranspiration. Stippled area indicates periods when potential evapotranspiration generally exceed precipitation. F-2
400 Water-Year: October - September Precipitation (mm) 300 200 100 Growing season: April - July 0 1900 1920 1940 1960 1980 2000 Figure 3. Precipitation data for the Idaho National engineering and Environmental Laboratory (INEEL). Data for years prior to 1950 were estimated using correlations between data from the INEEL Central Facilities Area and nearby locations (see Methods, Precipitation Data and Estimates). Upper curve shows water-year (October September) precipitation; lower curve shows early growing season (April July) precipitation. Horizontal lines depict long-term means for water-year or growing season precipitation. F-3
Figure 4. Layout (not to scale) of the Protective Cap/Biobarrier Experiment at the Experimental Field Station, Idaho National Engineering and Environmental Laboratory. The 12 main plots are three replicates of the four cap configurations depicted in Figure 5. Each main plots is divided into six subplots representing the two vegetation types and three irrigation treatments (see section 2.0). The position of six caissons is shown as a bold circle between plots. Soil texture data corresponding to each main plot is shown to the right of the layout. cwg = crested wheatgrass vegetation; native = native vegetation. F-4
SUBPLOT NUMBERING 1 3 5 2 4 6 IRRIGATION ambient summer fall/spring Soil Particle Size Distribution (%) Sand Silt Clay PLOT 1 native cwg native 17 43 40 RCRA cwg native cwg PLOT 2 native native cwg 18 45 37 0.5 m barrier cwg cwg native PLOT 3 cwg native native 18 47 35 soil only native cwg cwg PLOT 4 cwg native cwg 19 49 32 1 m barrier native cwg native PLOT 5 cwg native native 18 45 37 soil only native cwg cwg PLOT 6 cwg cwg native 19 48 33 1 m barrier native native cwg PLOT 7 cwg native cwg 21 52 27 RCRA native cwg native PLOT 8 native native cwg 19 48 33 0.5 m barrier cwg cwg native PLOT 9 native cwg native 18 48 34 1 m barrier cwg native cwg PLOT 10 cwg native cwg 23 52 25 0.5 m barrier native cwg native PLOT 11 native cwg cwg 21 55 24 soil only cwg native native PLOT 12 native cwg native 17 45 38 RCRA cwg native cwg F-5
Figure 5. Schematic diagram of vertical sections of the four cap configurations in the Protective Cap/Biobarrier Experiment at the Idaho National Engineering and Environmental Laboratory. Biological intrusion barriers (biobarriers) consisted of a 0.3- m depth of cobble sandwiched between 0.1-m depths of gravel. F-6
0.5 m 2 m 0.1 m 1 m 1 m 0.3 m 0.1 m 0.1 m 0.3 m 0.6 m 1.5 m 0.1 m 1 m Soil Only Cap Shallow Biobarrier Cap Deep Biobarrier Cap RCRA Cap Soil Cobble Gravel Compacted Clay 30 mm Impervious Liner F-7 F-5
Figure 6. Cumulative precipitation for the seven water-years (October- September) during which the Protective Cap/Biobarrier Experiment (PCBE) was conducted. Data are from the Idaho Nuclear Technology and Engineering Center (INTEC), the NOAA weather station closest to the PCBE site (4 km south) or from the PCBE site when available. F-8
Figure 7A. Soil moisture in the entire soil profile under ambient precipitation for the four cap configurations in the Protective Cap/Biobarrier Experiment at the Idaho National Engineering and Environmental Laboratory during seven years of study. Upper panel shows soil moisture dynamics on subplots planted to crested wheatgrass; lower panel shows soil moisture dynamics on subplots planted with native species. Error bars are ± 1 S.E. F-10