The Field Lysimeter Test Facility (FLTF) at the Hanford Site: Installation and initial tests [report]

G.W. Gee, R.R. Kirkham, J.L. Downs, M.D. Campbell
1989 unpublished
3. twice average precipitation, vegetated soil (1.5 m deep) 4. twice average precipitation, bare soil (1.5 m deep) 5. ambient precipitation, surface gravel admix/vegetation (1.5 m deep) 6. ambient precipitation, vegetated soil (1.0 m deep) 7. precipitation-to-breakthrough, bare soil (1.5 m deep). These treatments are replicated in both the drainage and weighing lysimeters. Details of the construction, backfill, instrumentation, and initial testing for the FLTF are provided in this document. The
more » ... experimental design of the FLTF allows drainage to be measured directly from each of the 18 lysimeters by gravimetric weighing of the outflow water. Water balance components are also measured. A neutron probe is used to measure storage changes in the top 1.5 m of each lysimeter. The four weighing-lysimeters are used to measure both precipitation and evapotranspiration with a precision of + 0.02 mm water. Additional climate data (e.g., solar radiation, air temperature, humidity, wind speed, etc.) for the FLTF are avail able from the adjacent Hanford Meteorological Station. In November 1987, tests were begun to measure water infiltration, evapotranspiration (ET), redistribution within the soil profile and drainage. These water balance tests are planned to continue through 1995. Vegetation representative of the native pl ant communi ty was seeded and transpl anted onto 10 of the 18 lysimeters. The report documents the water balance for each of the 18 lysimeters. Surface evaporation and ET rates in irrigated and nonirrigated lysimeters were significant in the winter months. Water losses by ET during the winter and early spring were sufficiently high to maintain a water deficiency in the surface soil, thus preventing drainage. The vegetated lysimeters exhibited more water loss for the 8-month (November 1987 through June 1988) test period than the bare surface (nonvegetated) lysimeters. Only the two lysimeters treated to breakthrough (D09-7 and Dll-7) yielded drainage during the 8-month test period. The expected precision of replicated drainage tests is f 1 L (equivalent to k0.04 cm water). Data on the hydraulic properties of the materials used as the soil cover in the FLTF are required as input to simulate the FLTF barrier tests using computer modeling. These data include saturated hydraulic conductivity, ACKNOWLEDGMENTS The f a c i l i t y described i n t h i s r e p o r t was b u i l t w i t h funding from t h e Hanford S i t e P r o t e c t i v e B a r r i e r Development Program sponsored by t h e U.S.
doi:10.2172/6518216 fatcat:reigywmrgrfctj6kw3udnov3d4