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Temporal and spatial pore water pressure distribution surrounding a vertical landfill leachate recirculation well.

Kadambala R, Townsend TG, Jain P, Singh K - Int J Environ Res Public Health (2011)

Bottom Line: While the impact of vertical well leachate recirculation on landfill pore water pressures has been mathematically modeled, measurements of these systems in operating landfills have not been reported.After liquid addition stopped, measured pore pressures did not immediately drop, but slowly decreased with time.The spatial variation of the pressures recorded in this study suggests that waste permeability is anisotropic and decreases with depth.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Engineering Sciences, University of Florida, PO BOX 116450, Gainesville, FL 32611, USA. kadambalar@cdm.com

ABSTRACT
Addition of liquids into landfilled waste can result in an increase in pore water pressure, and this in turn may increase concerns with respect to geotechnical stability of the landfilled waste mass. While the impact of vertical well leachate recirculation on landfill pore water pressures has been mathematically modeled, measurements of these systems in operating landfills have not been reported. Pressure readings from vibrating wire piezometers placed in the waste surrounding a liquids addition well at a full-scale operating landfill in Florida were recorded over a 2-year period. Prior to the addition of liquids, measured pore pressures were found to increase with landfill depth, an indication of gas pressure increase and decreasing waste permeability with depth. When liquid addition commenced, piezometers located closer to either the leachate injection well or the landfill surface responded more rapidly to leachate addition relative to those far from the well and those at deeper locations. After liquid addition stopped, measured pore pressures did not immediately drop, but slowly decreased with time. Despite the large pressures present at the bottom of the liquid addition well, much smaller pressures were measured in the surrounding waste. The spatial variation of the pressures recorded in this study suggests that waste permeability is anisotropic and decreases with depth.

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Cross Sectional View of the liquids addition well (Well 2) and the piezometer wells (Cross-section X-X’ in Figure 1).
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f2-ijerph-08-01692: Cross Sectional View of the liquids addition well (Well 2) and the piezometer wells (Cross-section X-X’ in Figure 1).

Mentions: The well was connected to a lateral polyethylene pipe (7.6 cm in diameter) that extended to the side slope of the landfill, and connected to the main leachate recirculation system. Eighteen multi-level piezometers (Model 52611199, Durham Geo-Slope Enterprises, Mukilteo, WA, USA) were placed 1.5 m away from each other as shown in Figure 1. Each multi-level piezometer consisted of five vibrating wire (VW) piezometers placed three meters apart from each other for a total length of 15 m (Figure 2). The entire multi-level piezometer assembly was placed inside a 20-cm diameter borehole. This bore hole was then grouted with a grout machine (ChemGrout, LaGrange Park, IL, USA) using a mix of cement and bentonite following the piezometer manufacturer instructions. Another 4.8-m lift of waste was placed on top of the experimental area; the vertical wells and the multi-level piezometer wells were buried. All of the piezometers were connected to a datalogger (CR10X, Campbell Scientific, Logan, UT, USA) to record the pore pressure and temperature registered by the buried instruments.


Temporal and spatial pore water pressure distribution surrounding a vertical landfill leachate recirculation well.

Kadambala R, Townsend TG, Jain P, Singh K - Int J Environ Res Public Health (2011)

Cross Sectional View of the liquids addition well (Well 2) and the piezometer wells (Cross-section X-X’ in Figure 1).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3108135&req=5

f2-ijerph-08-01692: Cross Sectional View of the liquids addition well (Well 2) and the piezometer wells (Cross-section X-X’ in Figure 1).
Mentions: The well was connected to a lateral polyethylene pipe (7.6 cm in diameter) that extended to the side slope of the landfill, and connected to the main leachate recirculation system. Eighteen multi-level piezometers (Model 52611199, Durham Geo-Slope Enterprises, Mukilteo, WA, USA) were placed 1.5 m away from each other as shown in Figure 1. Each multi-level piezometer consisted of five vibrating wire (VW) piezometers placed three meters apart from each other for a total length of 15 m (Figure 2). The entire multi-level piezometer assembly was placed inside a 20-cm diameter borehole. This bore hole was then grouted with a grout machine (ChemGrout, LaGrange Park, IL, USA) using a mix of cement and bentonite following the piezometer manufacturer instructions. Another 4.8-m lift of waste was placed on top of the experimental area; the vertical wells and the multi-level piezometer wells were buried. All of the piezometers were connected to a datalogger (CR10X, Campbell Scientific, Logan, UT, USA) to record the pore pressure and temperature registered by the buried instruments.

Bottom Line: While the impact of vertical well leachate recirculation on landfill pore water pressures has been mathematically modeled, measurements of these systems in operating landfills have not been reported.After liquid addition stopped, measured pore pressures did not immediately drop, but slowly decreased with time.The spatial variation of the pressures recorded in this study suggests that waste permeability is anisotropic and decreases with depth.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Engineering Sciences, University of Florida, PO BOX 116450, Gainesville, FL 32611, USA. kadambalar@cdm.com

ABSTRACT
Addition of liquids into landfilled waste can result in an increase in pore water pressure, and this in turn may increase concerns with respect to geotechnical stability of the landfilled waste mass. While the impact of vertical well leachate recirculation on landfill pore water pressures has been mathematically modeled, measurements of these systems in operating landfills have not been reported. Pressure readings from vibrating wire piezometers placed in the waste surrounding a liquids addition well at a full-scale operating landfill in Florida were recorded over a 2-year period. Prior to the addition of liquids, measured pore pressures were found to increase with landfill depth, an indication of gas pressure increase and decreasing waste permeability with depth. When liquid addition commenced, piezometers located closer to either the leachate injection well or the landfill surface responded more rapidly to leachate addition relative to those far from the well and those at deeper locations. After liquid addition stopped, measured pore pressures did not immediately drop, but slowly decreased with time. Despite the large pressures present at the bottom of the liquid addition well, much smaller pressures were measured in the surrounding waste. The spatial variation of the pressures recorded in this study suggests that waste permeability is anisotropic and decreases with depth.

Show MeSH
Related in: MedlinePlus