Evaluation Of Use of Stone Column in Unengineered Closed Landfill Soil

In the building industry, ground improvement techniques based on stone column are widely employed. It is a very successful approach for enhancing the engineering characteristics of soil in all aspects, as well as reducing the settling issue in poor-grounded soils including silt, clay, silty sand, and organic soil. The performance of stone columns, is determined by the confining pressure provided by the surrounding soils. Engineering constructions built on thick layers of soft soil strata face issues such as limited bearing capacity, excessive total and differential settlement, lateral spreading, and so on. To address such issues, many ground improvement techniques are available. In exceptionally soft soils, the lateral confining pressure may be inadequate, resulting in column bulging failure. Individual stone column encasement improves lateral resistance to bulging by adding restricting pressure. This research focuses on the geotechnical aspects of building on closed landfill sites. A total of 33 models were tested in a geotechnical engineering laboratory on virgin former landfill soil and stone column with and without encasement in this current study. The increased diameter, length and L/D ratio of the column has demonstrated that the load capacity has increased and soil settling has decreased. When an unreinforced stone column has been installed, the ultimate bearing capacity of landfill soil is increased by 75-112.50 per cent and 87.50-176 per cent respectively, for 10mm and 20mm diameter stone column. Furthermore, when a fully reinforced stone column has been installed, it had increased by 156.25-212.50 per cent and 200-298 per cent for 10mm and 20mm diameters respectively. The stiffness of soil is increased by the stone column, which contributes to increase in the load capacity. The geogrid layer confines an aggregate, which contribute to enhance shear stiffness and bearing capacity.

Temporal variability of methane emissions from a closed landfill at Denmark

<p>Methane (CH<sub>4</sub>) emissions from landfills contribute to global warming, impacting significantly the environment and human health. Landfill CH<sub>4</sub> emissions strongly depend on changes in barometric pressure, inducing short-term CH<sub>4</sub> emission variation of several orders of magnitude. Estimating the temporal variability of CH<sub>4</sub> emitted into the atmosphere could help us reducing the uncertainties of annual emission estimates from landfills. In this study, we focus on the temporal variability of CH<sub>4</sub> emissions under the impact of barometric pressure changes.</p><p>CH<sub>4</sub> emissions of a closed landfill (Skellingsted, Western Zealand, Denmark) were measured with two different methods from December 2019 to June 2020; continuously with the eddy covariance method (EC) and discretely with the dynamic tracer dispersion method (TDM). The EC method allows continuous measurements from a confined surface area, with most likely limited representativeness of the whole landfill site due to the considerable horizontal heterogeneity. The TDM method is able to quantify the emission from the whole site insensitive of the topography with the limited representativeness for the temporal variability.</p><p>CH<sub>4</sub> emissions to the atmosphere measured by the TDM and fluxes measured by the EC ranged from to 0 to almost 100 kg h<sup>-1</sup> and from 0 to 10 μmol m<sup>-2</sup> s<sup>-1</sup>, respectively. The CH<sub>4</sub> fluxes measured continuously using the EC method were highly correlated with the emissions from the periodic measurements using the TDM and fluctuated according to the pressure tendency. Under decreasing barometric pressure the highest CH<sub>4</sub> emissions where observed, while increasing barometric pressure suppressed them almost to 0.</p><p>Our results demonstrate the value of implementing two different complementary measurement techniques in parallel that will help to quantify total annual CH<sub>4</sub> emission from a landfill. EC method provides continuous measurements describing accurately the temporal variation of emissions, while TDM method is able to quantify emissions from the whole site.</p>

In Situ Characterization of Municipal Solid Waste Using Membrane Interface Probe (MIP) and Hydraulic Profiling Tool (HPT) in an Active and Closed Landfill

Municipal solid waste (MSW) landfills near a metropolitan area are renewable energy resources to produce heat and methane that can generate electricity. However, it is difficult to use those sources productively because disposed MSW in landfills are spatially and temporally heterogeneous. Regarding the prediction of the sources, the analysis of in situ MSW properties is an alternative way to reduce the uncertainty and to understand complex processes undergoing in the landfill effectively. A hydraulic profiling tool (HPT) and membrane interface probe (MIP) test measures the continuous profile of MSW properties with depth, including hydraulic pressure, temperature, electrical conductivity (EC), and the relative concentration of methane at the field. In this study, we conducted a series of the tests to investigate the MSW characteristics of active and closed landfills. MIP results showed that the methane existed closer to right below the top cover in the active landfill and several peak concentrations at different layers of the closed landfill. As the depth and age of the waste increased, the hydraulic pressure increased for both landfills. The average EC results showed that the electrical conductivity decreased with the landfill age. The results of hydraulic properties, temperature, and EC obtained from active and closed sites could be used to estimate the waste age and help designing energy recovery systems.

Municipal solid waste landfill age and refuse-derived fuel

Landfill sites are hard to obtain in Taiwan. Municipal solid waste (MSW) in the closed landfill sites has high combustible content and calorific value (CV). Therefore, activating the closed landfill sites as municipal mine sites to prolong their service life will promote a sustainable environment. This study transforms combustibles from the closed municipal landfill sites of different landfill ages (LAs) into refuse-derived fuel (RDF) through pretreatment and squeeze forming equipment, so to investigate the characteristics of the MSW of different LAs, and the manufacturing conditions and firing behaviour of RDF. The results indicate that the proportion of the combustibles in MSW declines as the LA grows, and therefore the proportions of both incombustible materials and soil and debris correspondingly increased. The LA of the MSW is thus negatively correlated with the CV. The MSW at the LA of 10 years still has high potential as fuel material. The fixed carbon initiation temperatures (i.e. ignition temperatures) of combustibles of the MSW at the LAs of 1 year, 5 years and 10 years are 259°C, 256°C and 245°C, respectively. The CV and flame temperature of the RDF increase slightly with the increasing squeeze temperature (ST) at 100–120°C, but it will decrease when the ST reaches 130°C. Therefore, this study recommends the squeeze pressure of the RDF as 41.65 ± 8.24 kg cm−2, ST 110°C and combustible size 10–20 mm.

Treatment of Landfill Leachate at a Remote Closed Landfill Site on the Isle of Wight

Safe treatment and disposal of leachates is an important issue at many old landfill sites, where the ingress of rainfall or groundwater is a significant issue requiring consideration. Such leachates may typically be relatively weak, but flows are often characterised by large seasonal variations, in response to winter rainfall. This paper compiles and presents long-term data from a case study on the Isle of Wight, UK. This paper highlights how a successful treatability trial using representative leachates can help predict the effectiveness of a large-scale treatment plant when treating landfill leachates biologically. Bleakdown leachate treatment plant effectively removes all concentrations of ammoniacal-N within the weak leachate generated by the site, ensuring that the discharge consent set by the Environment Agency is achieved consistently. The site is completely unmanned and remote, where monitoring technicians are only required to attend site twice per month in order to assess the success of the biological process. Through an online SCADA control system, operation of the treatment plant can be monitored and controlled remotely, trends in results can be observed, and daily data and treatment records downloaded. This treatment plant is an example of how leachate from old closed landfills can be effectively managed, with very low costs of operation, maintenance and site attendance. This paper presents comprehensive analytical and volumetric treatment data from the Bleakdown LTP, before presenting practical steps that would enable this success to be replicated at similar remote closed landfill sites.

Soils of abandoned industrial wastes disposal sites: properties, processes, functioning

<p>Soils formed at once abandoned and recultivated industrial waste dumping sites are key research objects both as models of soil-forming processes in underdeveloped soils and indicators of persistent or potential environmental hazards of dumps themselves. Our studies of technogenic surface-like soil formations (TSF) and soils were conducted on a closed landfill and two abandoned filtration fields from sugar factories  in Kursk region, central part of European Russia.</p><p>Key properties of TSF and soils were defined with the assessments of their ecological, microbiological state and gas-geochemical condition. Set of methods (mesomorphological and micromorphological analysis, soil chemical and physico-chemical analysis, comparatively geographical method) was used for the detection of current elementary soil processes. Seasonal dynamics of carbon dioxide, methane and nitrous oxide emissions from soils to the atmosphere was also under consideration. Main used methodology is a research of sustainable properties of soil solid-phase (“soil memory”) together with soil functioning.</p><p>Long-term time series of high-detailed remote sensing data (from archive aerial photos of 1950s to actual satellite images and UAV optical photogrammetry) provided the possibility for the retrospective remote monitoring of the all abandoned dumps in study and reconstruction of their life cycles and land cover patterns.</p><p>As a result for the three industrial waste dumping sites of different types and the varying age of abandonment and recultivation history there were elaborated schemes of chrono-functional zoning. Each chrono-functional zone is characterized by the specific set of TSF and soils. Among them, it was described technogenic surface-like soil formations of closed landfill, calcareous technosols with several thick organic layers at the bottom of abandoned field filtration cells, calcic anthrosols of field filtration cells spontaneously used for agriculture after the abandonment of sugar factories.</p><p>The study is financially supported by RFBR project № 19–29–05025–mk.</p>

Level of Pollution on Surrounding Environment from Landfill Aftercare

This work examines how the pollution from landfill aftercare effect the surrounding area and water basins. The subject of the study was a closed landfill where waste was disposed of without any accounting and operation of the landfill. During the study, soil, surface water, and sediment samples were taken over a two-year period. The data obtained compared with the maximum allowable concentrations established in the Northern part of Lithuania. The water sampling sites were selected taking into account the direction of the water flow, and the landfill was found to influence the water quality. Within 500 meters before the landfill, heavy metals and metalloid concentrations did not exceed the maximum allowable concentrations (Pb ≤ 20 µg/L; Ni ≤ 40 µg/L; Cr ≤ 100 µg/L; Cu ≤ 100 µg/L and As ≤ 20 µg/L). Soil and water sediment contamination factor and contamination level were determined for each metal and metalloid individually, which showed that as a single chemical element and its compounds none of them pose any danger to the environment. A different situation can be seen when calculating the total level of contamination, taking into account all pollutants classified as very hazardous, Zd > 10. The results showed that monitoring (of surface water, including soil) and investigations, helping to reduce negative environmental impact, should be continued in the closed landfill.