Assessment of the Performance of Engineered Waste Containment Barriers (2007) / Chapter Skim
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3 Monitoring Barrier Performance
3 Monitoring Barrier Performance
Pages 21-36
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From page 21... ...
In approved states, is required to develop a conceptual site model for barrier both state and local governments are generally involved in system design and analysis, to establish a baseline for evalu- overseeing monitoring programs. ating the effectiveness of the engineered barrier system, and, RCRA Subtitles C and D prescribe minimum standards in the case of a barrier system for preexisting contamination, for monitoring hazardous waste treatment, storage, and disto establish boundary conditions and geometric constraints posal facilities and municipal solid waste (MSW)
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From page 22... ...
Both the hydraulic potential (phreatic surface, hydraulic head) and the groundwater chemical composition Monitoring systems at waste containment sites may in the pore water recovered from saturated soil beneath the target a variety of media, including soil, groundwater, sur phreatic surface are measured.
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From page 23... ...
; hydraulic profiling head, pressure, temperature; detection of some chemicals Surface Water Grab samples Laboratory characterization of Easy; inexpensive; laboratory Discreet samples; requires care to ensure chemical composition characterization possible representative sampling; sample degradation issues; sample transportation/chain of custody Vadose Zone Tensiometers Soil suction Permanent installation; simple; robust Invasive; risks cross-contamination; vacuum gauge calibration; can develop air leaks; ceramic cup may plug; limited to –1 atm by cavitation Gas monitoring probes; Methane; oxygen; carbon Permanent or temporary installation; Discrete samples; seasonally variable; does borehole and well dioxide; hydrocarbons; simple; robust; can identify migration not include emissions from other sources headspace monitoring; nonmethane organic pathways (e.g., composting) ; not quantitative passive landfill vents compounds Flux box Methane; oxygen; carbon Quantitative evaluation of gas transport Seasonably variable; may alter flow dioxide; hydrocarbons; out of covers boundary conditions nonmethane organic compounds Lysimeters Liquid flux; samples (some Can allow sampling and combined Slow; cannot distinguish effects of liner designs)
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From page 24... ...
Vadose zone monitoring systems measure hydraulic poFiber-optic sensors, which have been used to study dynamic tential (soil suction) , soil pore gas constituent concentrations, hydrologic processes (Selker et al., 2006)
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From page 25... ...
An active vadose zone gas In situ moisture measurements can be made using elec- monitoring program for a closed hazardous waste landfill site trical probes, including capacitance probes, which directly in California is described in Box 3.1. measure the electrical capacitance of a representative volume of soil; time domain reflectometry probes, which indirectly 3.2.4 air Quality monitoring measure soil capacitance; and thermal probes, which measure the rate at which heat is dissipated by the soil.
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From page 26... ...
aSSESSmENT Of ThE pERfORmaNCE Of ENgiNEEREd waSTE CONTaiNmENT baRRiERS BoX 3.1 Vadose Zone monitoring for the mccoll superfund site This case history describes a vadose zone monitoring program for a closed hazardous waste site. The McColl Superfund site, located in Fullerton, California, was an 8.8-ha hazardous waste disposal site with 12 unlined pits, or sumps, containing approximately 60,150 m3 of petroleum waste sludge generated from high-octane aviation fuel production.
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From page 27... ...
. Furthermore, electrical nents monitored in practice include compacted clay barriers, leak detection methods are being used with increasing fregeomembrane barriers, leachate collection layers, vertical quency to detect defects in geomembranes.
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From page 28... ...
Although leak detection layers and transport across the liner and degradation of liner system pan lysimeters are advantageous for monitoring large areas components. of barriers, data collection is slow and it is difficult, if not im- The leachate collection layer monitoring system and other possible, to distinguish the effects of liner consolidation from monitoring systems used at a low-level radioactive waste induced flow in systems where the pan lysimeter underlies repository are described in Box 3.3.
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From page 29... ...
10000 Primary Leachate Collection System 1000 100 Finish Below Identify Correct Grade Filling - Flow Meter 10 Flow Meter Interim Cover Problem Secondary Leachate Collection Problem (or Leak Detection) System 1 0 5 10 15 20 25 30 35 40 45 50 Time from Initial Filling (months)
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From page 30... ...
. grout barriers and thick-wall polymer barriers (i.e., an ap However, with the exception of electrical leak detection proximately 1-m-thick wall constructed by injecting colloi in geomembranes, the use of geophysical methods to assess dal silica into fine- and coarse-grained sands; see Box 3.5; barrier integrity has not generally found its way into routine Daily and Ramirez, 2000)
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From page 31... ...
mONiTORiNg baRRiER pERfORmaNCE DOE design criteria called for the containment system to maintain its integrity for longer than 200 years and up to 1,000 years to the extent achiev able. The cover system is designed with a low profile for "geomorphologic conformity" with the surrounding terrain (Figure 3.4)
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From page 32... ...
aSSESSmENT Of ThE pERfORmaNCE Of ENgiNEEREd waSTE CONTaiNmENT baRRiERS BoX 3.4 case history on the Puente hills landfill canyons 1 and 3 Vertical Barriers This case study illustrates the effective use of vertical barrier walls and an extraction system to control offsite migration of organic contamination. The Puente Hills Sanitary Landfill, owned and operated by the County Sanitation Districts of Los Angeles County (the Districts)
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From page 33... ...
mONiTORiNg baRRiER pERfORmaNCE BoX 3.5 case history on geophysical imaging of engineered hydraulic Barriers This case history illustrates the potential of using geophysical imaging techniques during emplacement of two prototype engineered barriers: a thin-wall grout barrier and a thick-wall polymer barrier. Electrical resistance tomography (ERT)
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aSSESSmENT Of ThE pERfORmaNCE Of ENgiNEEREd waSTE CONTaiNmENT baRRiERS FIGURE 3.9 (a) Plan and schematic views of the viscous liquid barrier.
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From page 35... ...
measurements of this frequency are rarely required to assess barrier performance or to monitor environmental protection because subsurface contaminant migration patterns rarely 3.3.5 geosynthetic clay liner Barrier monitoring change rapidly over scales in excess of tens of meters. Where Because geosynthetic clay liners (GCLs)
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From page 36... ...
have been conducted to the committee's knowledge. In situ Indirect monitoring of engineered barrier performance moisture content monitoring of soil layers in caps above, in, by monitoring for contaminant migration downstream of the and below the barrier system can also provide an indication waste containment system is commonplace, as it is mandated of cap performance.
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