MODELING OF VERTICAL FLOW AND MASS TRANSFER OF WATER-LNAPL-GAS IN VADOZE ZONE WITH CASE STUDIES CONTAMINATED LAND OF B3 LANDFILL BABELAN, BEKASI DISTRICT

• Main Author: VALERI (NIM: 22716005), GIAN
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/27514
• Institution: Institut Teknologi Bandung

<p align="justify"> The objective of this study is to obtain saturation relationship curve model with capillary pressure (S-P model), water and gas saturation profile model, and water-LNAPL-gas saturation distribution model in vadoze zone which is mostly unsaturated zone, so that it can be used to describe the flow and mass transfer of LNAPL from ground surface to groundwater table. This study was conducted following a spill of petroleum hydrocarbon in an open dumping sanitary landfill (TPA) of Babelan Sub-district, Bekasi District and accordingly, the spill was classified as hazardous and toxic materials (B3) wastes which are accumulative and difficult to degrade in vadoze zone. The presence of contamination of organic compounds and other chemical compounds that are difficult to degrade and are toxic in the soil to disrupt the growth of plants and other organisms that live in it. In addition, contamination of organic compounds in the soil is also source of major contaminants for the underlying groundwater. Therefore, the spread of LNAPL in the vadoze zone can then be a major source of contaminants that needs to be modeled. <br /> <br /> The modeling of water dan gas saturation distribution profile and (water-LNAPL-gas) saturation distribution profile in the vadoze zone is carried out using a NAPL Simulator. Meanwhile, modeling of relationship of saturation curve with capillary pressure (S-P model) was modeled using Excel spreedsheet designed by Anlauf, and S-P curve model in NAPL Simulator. The NAPL simulator input parameters was obtained from soil physical properties test, permeability test, water retention test (pF test), and previous research data. The results of physical soil properties such as bulk density, water content, and porosity. The result of permeability test is hydraulic conductivity value (K). While, the results of water retention test (pF test) such as the relationship of pF value with water content. In addition to the above parameters, additional parameters are required in the NAPL Simulator, namely density (water-LNAPL-gas), viscosity (water-LNAPL-gas), interfacial tension of inter-phase, and pore-connectivity parameters of inter-phases. These additional parameters were obtained from previous research data. <br /> <br /> Based on SP curve model, it is known that drainage capillary pressure (&#119867;&#119862;&#119889;) amounted 4,2 pF and imbibition capillary pressure (&#119867;&#119862;&#119894;) amounted 2,1 pF can decrease water saturation level in unsaturated zone with water residual saturation value (&#119878;&#119908;&#119903;) of 3.1% in porous media. This residual water saturation value, then used as the input parameter for modeling the water and gas saturation profile. From the water and gas saturation profile modeling, it is known that the height of capillary zone is at a depth of 275 cm from the ground level or 25 cm above groundwater table (GWT), and it is also known that the hydrostatic condition for flow and evaporation of water is achieved at t = 2 days. The profile of water and gas saturation during these hydrostatic conditions, representing the initial water and gas saturation profile model before the LNAPL spill is released in unsaturated zone. Meanwhile, based on multifase (water-LNAPL-gas) saturation profile model, it is known that LNAPL reaches the top of capillary zones for t = 9 days. After reaching the top of the capillary zone, most of the LNAPL accumulates at the top of the capillary zones and some of them spread laterally in the capillary zone or float just above groundwater table (GWT). The explanation states that the spread of LNAPL in the vadoze zone with the constituent material is loamy clay, caused LNAPL settle more in an unsaturated zone than capillary zone within a period of more than 9 days after LNAPL spill is released. <p align="justify">