FIRE IMPACTS ON AN ENGINEERED BARRIER’S PERFORMANCE: THE HANFORD BARRIER ONE YEAR AFTER A CONTROLLED BURN
A critical unknown for long-term engineered barrier performance is the effect of wild fire during a post-institutional control environment where routine maintenance may be limited or non-existent. In September 2008, a controlled burn was conducted on one half of a vegetated, multilayered capillary barrier emplaced over a Hanford waste site. The effects on barrier performance have been monitored and documented over the past year. Soil physical, chemical, and hydrologic properties; plant floristics and density; and animal-use were characterized before and after the fire with the unburned half of the barrier serving as a control. Temperatures during the controlled burn ranged from 250 oC at 1.5 cm below the surface to over 700 oC at 1 m above the surface. Significant decreases in hydraulic conductivity and surface-soil wettability were observed immediately after the fire due primarily to hydrophobic conditions created by the fire. Major soil nutrients, pH, and electrical conductivity remain elevated post-fire. Up until June 2009, post-burn soil moisture content in the 0-1 m depth interval was significantly lower on the burned section than the unburned section and is attributed to differences in surface evaporation. Higher soil moisture contents in the 1-2 m interval on the burned section are attributed to insignificant water uptake owing to the absence of deep-rooted shrubs. Moisture profiles reversed after June to show lower water contents throughout the profile on the unburned section. Dense stands of sagebrush were destroyed from the fire allowing many more species to emerge thereby increasing species diversity. Seed sources contributing to this species diversification were from either the existing seedbank and/or wind-blown sources. Measurements are ongoing and the results are expected to help close a knowledge gap about barrier recovery after major disturbances.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1024094
- Report Number(s):
- PNNL-SA-69750; 830403000; TRN: US201119%%90
- Resource Relation:
- Conference: WM2010: Improving the Future by Dealing with the Past, March 7-11, 2010, Phoenix, Arizona, Paper No. 10472
- Country of Publication:
- United States
- Language:
- English
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