| Title | Investigating the impact of a municipal solid waste facility on groundwater using environmental isotope and landfill gas analysis |
| Abstract | At an urban landfill facility located in central Italy, we investigate the processes leading to moderate amounts
of VOC in groundwater (benzene), at one downgradient monitoring well. Increased alkalinity and sulfates,
lower pH and high levels of redox-sensitive elements (Mn, Fe, As), might support both the hypothesis of
leachate loss to groundwater or landfill gas-to-water transfer.
In this study, we analyze the available information concerning geochemistry, organic contaminants, environmental isotopes and landfill gas in groundwater to shed light on the possible mass transfer processes. We test
the hypothesis that landfill gas migrating from the landfill at the downgradient end of the plant be responsible
for high dissolved organic carbon (from methane and other organic compounds), lower pH (due to CO2), and
the presence of limited amounts of VOCs transferred from the landfill gas to the groundwater.
Periodical groundwater monitoring campaigns have been conducted since 2016 at the site. Field parameters
(T, EC, pH, DO, ORP) are measured with probes in a flow-through cell. Groundwater sampling is performed
with an in-line device in order to minimize sample disturbance. Lab analysis are performed for major and
trace elements. Organic compounds include DOC, PAH, PCB, VOC. Ammonia and sulphide are measured in
the field with a portable UV-VIS. Environmental isotopes (18O, 2H, Tritium, 13C) have been assessed twice.
The pressure of CH4, CO2, O2 in the piezometer free gas phase are measured in situ with Draeger X-am 7000
(CO2, O2) and laser INSPECTRA® LASER (GAZOMATTM) (CH4); dissolved gas in groundwater is analyzed
by gas cromatography on the headspace.
Groundwaters are mostly anoxic (DO < 1 mg/L), with neutral to slightly basic pH and calcium-bicarbonate
facies. Iron, manganese and arsenic are above national standards for groundwater. PAH, PCB and VOC were
always below the standards except benzene at one downgradient well. The downgradient well stands out also
for high EC, high alkalinity, low pH, very high As, Fe and Mn, above average DOC. Preliminary results on
the landfill gas measurements indicate that methane is present both in the free phase in the wells' headspace
and as dissolved phase in groundwater.
The high values of methane support the hypothesis of a gas-phase transport of VOC localized at the downgradient end of the facility. Landfill gas CO2 might enhance the dissolution of carbonate minerals and increase
alkalinity. The reducing capacity of CH4 favours the high levels of redox sensitive elements in groundwater.
While the plant manager has already improved the gas extraction system, a sampling campaign is planned in
spring 2019 to further investigate the impact of landfill gas on groundwater and verify the efficacy of the gas
recovery measures. |
| Source | 46th IAH Congress "Groundwater Management and Governance", Malaga (Spain), 22-27/09/2019 |
| Keywords | Groundwater monitoringarsenicbenzenemethanecarbon dioxideDissolved Inorganic Carbonlandfill |
| Year | 2019 |
| Type | Abstract in atti di convegno |
| Authors | Elisabetta Preziosi, Eleonora Frollini, Daniele Parrone, Stefano Ghergo, Nicoletta Ademollo, Giancarlo Ciotoli, Luisa Patrolecco, Alessandra Sciarra |
| Text | 439901 2019 Groundwater monitoring arsenic benzene methane carbon dioxide Dissolved Inorganic Carbon landfill Investigating the impact of a municipal solid waste facility on groundwater using environmental isotope and landfill gas analysis Elisabetta Preziosi, Eleonora Frollini, Daniele Parrone, Stefano Ghergo, Nicoletta Ademollo, Giancarlo Ciotoli, Luisa Patrolecco, Alessandra Sciarra IRSA CNR Water Research Institute National Research Council , Monterotondo Rome , Italy IGAG CNR Institute of Environmental Geology and Geoengineering National Research Council , Monterotondo Rome , Italy INGV Istituto Nazionale di Geofisica e Vulcanologia , Rome, Italy Published version https //iah2019.adabyron.uma.es/event/1/contributions/605/contribution.pdf 46th IAH Congress Groundwater Management and Governance Malaga Spain 22 27/09/2019 Internazionale Contributo At an urban landfill facility located in central Italy, we investigate the processes leading to moderate amounts of VOC in groundwater benzene , at one downgradient monitoring well. Increased alkalinity and sulfates, lower pH and high levels of redox sensitive elements Mn, Fe, As , might support both the hypothesis of leachate loss to groundwater or landfill gas to water transfer. In this study, we analyze the available information concerning geochemistry, organic contaminants, environmental isotopes and landfill gas in groundwater to shed light on the possible mass transfer processes. We test the hypothesis that landfill gas migrating from the landfill at the downgradient end of the plant be responsible for high dissolved organic carbon from methane and other organic compounds , lower pH due to CO2 , and the presence of limited amounts of VOCs transferred from the landfill gas to the groundwater. Periodical groundwater monitoring campaigns have been conducted since 2016 at the site. Field parameters T, EC, pH, DO, ORP are measured with probes in a flow through cell. Groundwater sampling is performed with an in line device in order to minimize sample disturbance. Lab analysis are performed for major and trace elements. Organic compounds include DOC, PAH, PCB, VOC. Ammonia and sulphide are measured in the field with a portable UV VIS. Environmental isotopes 18O, 2H, Tritium, 13C have been assessed twice. The pressure of CH4, CO2, O2 in the piezometer free gas phase are measured in situ with Draeger X am 7000 CO2, O2 and laser INSPECTRA® LASER GAZOMATTM CH4 ; dissolved gas in groundwater is analyzed by gas cromatography on the headspace. Groundwaters are mostly anoxic DO < 1 mg/L , with neutral to slightly basic pH and calcium bicarbonate facies. Iron, manganese and arsenic are above national standards for groundwater. PAH, PCB and VOC were always below the standards except benzene at one downgradient well. The downgradient well stands out also for high EC, high alkalinity, low pH, very high As, Fe and Mn, above average DOC. Preliminary results on the landfill gas measurements indicate that methane is present both in the free phase in the wells headspace and as dissolved phase in groundwater. The high values of methane support the hypothesis of a gas phase transport of VOC localized at the downgradient end of the facility. Landfill gas CO2 might enhance the dissolution of carbonate minerals and increase alkalinity. The reducing capacity of CH4 favours the high levels of redox sensitive elements in groundwater. While the plant manager has already improved the gas extraction system, a sampling campaign is planned in spring 2019 to further investigate the impact of landfill gas on groundwater and verify the efficacy of the gas recovery measures. Abstract in atti di convegno nicoletta.ademollo ADEMOLLO NICOLETTA danieleparrone PARRONE DANIELE eleonorafrollini FROLLINI ELEONORA SCIARRA ALESSANDRA stefano.ghergo GHERGO STEFANO luisa.patrolecco PATROLECCO LUISA elisabetta.preziosi PREZIOSI ELISABETTA giancarlo.ciotoli CIOTOLI GIANCARLO |
