Effect of acidic leachate on material degradation of slurry trench cutoff walls
Conference
·
OSTI ID:576484
- August Mack Environmental, Inc., Baltimore, MD (United States)
The use of low permeability slurry trench cutoff walls has increased since the early 1980`s. This permeability requirement is necessary to minimize the seepage rate of the contaminated groundwater (leachate) through the cutoff wall. The selection of the cutoff wall material (e.g. soil-bentonite, soil-treated bentonite, soil-attapulgite, soil-cement-bentonite, cement-bentonite, etc.) is primarily dependent on the chemical properties of the leachate and construction requirements. To investigate the effect of low pH effluent on wall materials, short and long term compatibility studies were assessed on different wall material mixes. A leachate with a pH of 2.4 was used in this study. In addition, water with a pH of 6.8 was used for comparison of test results. In order to assess the applicability of wall materials in a cost effective and timely manner, filter press, chemical desiccation, and sedimentation tests were selected to assess the short term effect of the leachate on eighteen slurry samples. These tests were performed on 90 bbl Fed Jel bentonite and 125 bbl Fed Jel treated bentonite (manufactured by M-1 Drilling Fluids), and attapulgite slurry samples prepared first with leachate and then with water. The duration of each test varied from 30 minutes to 7 days. Test results obtained from the short term compatibility study indicate that the 90 bbl Fed Jel bentonite slurry degraded under exposure to the leachate, and therefore, the 125 bbl Fed Jel bentonite and attapulgite slurries were selected for the long term compatibility study. Rigid wall permeability testing was selected to assess the long term effect of the leachate on four soil-125 bbl Fed Jel bentonite and four soil-attapulgite samples. The samples were saturated, consolidated, and subjected to permeation using first water and then leachate. The duration of each test varied from 40 days to 60 days.
- Research Organization:
- USDOE, Washington, DC (United States)
- OSTI ID:
- 576484
- Report Number(s):
- CONF-970208--Proc.; ON: DE98001967
- Country of Publication:
- United States
- Language:
- English
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