34;Applicability of Local Soils as Support Materials for Sanitary Landfill Construction has been approved by the board of examiners in partial fulfillment of the requirements for the degree of Master of Science in Civil Engineering, Khulna University of Engineering &. 87 Figure 5.5 Grain size distribution curve of compacted clay 88 Figure 5.6 Grain size distribution curve of drainage collection layer 88 Figure 5.7 Grain size distribution curve of washed brick aggregate 89 Figure 5.8 Determination of the acceptable water content zone 90D.
General
To prevent the movement of leachate, clay liners are placed at the bottom of the landfill before solid waste is deposited into it. To prevent trash from blowing around and to reduce odors and the spread of disease, solid waste is covered with clean fill material during the day.
Background of this Study
Once the landfill is filled, it will be monitored and maintained by law for another 30 years. For this purpose, the landfill of size 50x50x6m, which is 3 meters below and 3 meters above the existing ground surface, has been constructed with necessary components, at Rajbandh, Khulna, at the final landfill site of MSW of Khulna City Corporation (KCC) ( Alamgir et al. 2009).
Objective of This Study
This research establishes minimum design requirements for sanitary landfill liners, provides engineering criteria for construction, and outlines recommended design practices and feasibility studies for the best use of local materials under tropical hydrogeological conditions based on experience with pilot sanitary landfills in LDAC countries such as Bangladesh. .
Research Framework
Investigate the applicability of local soils as a base material for the construction of a sanitary landfill in Khulna. Assess the achievement of objectives; draw conclusions from the findings and provide a summary to improve the design of sanitary landfills in this region.
General
History of Solid Waste Disposal
- Source storage to disposal
- Generation of Solid Waste
- MSW generation in major six cities of Bangladesh
- Characteristics of solid wastes in Bangladesh
- Ultimate Disposal Practices of Solid Wastes in Bangladesh
- Institutional Arrangement for Solid Waste Management
- Laws and Regulations
- Current Practice of SWM in Khulna
In most city corporations and municipalities there is no separate department for solid waste management. The Khulna City Corporation (KCC) is responsible for the operation and maintenance of municipal services, including solid waste management.
Sanitary Landfill
- Classification of Landfill Site
- Classification of Landfill Structure
I Landfill is a term used to describe the physical facilities for the disposal of solid waste and solid waste residues in the surface soil of the earth. Stabilization Time: The main advantage of a wet landfill is the increased rate of stabilization of the solid waste in the landfill.
Sanitary Landfill in Bangladesh
Properly designed and located wells also ensure that groundwater samples and water level measurements are representative of the groundwater beneath the site. With this semi-aerobic system, the life of the landfill is estimated at 20 years at the current incoming waste volume of approximately 1,700 tons/day (www.citynet-ap.org).
Landfill Liners
- Liner system
- Basic Liner Specifications
In general, the extent of this action depends on the characteristics of the soil, especially clay content. The reason for the additional clay is to protect the environment in case of some loss of effectiveness in part of the clay layer.
Engineering Parameters of Clay Lining Materials
- Hydraulic Conductivity
- Plasticity Characteristics
- Percent Fines and Percent Gravel
The liquid limit is defined as the minimum moisture content (in percent of oven-dried weight) at which a soil-water mixture can flow. The plasticity index is defined as the liquid limit minus the plastic limit and defines the range of moisture content over which a.
Conclusion
General
PotentialStudy of the Site
Surface water: The site is more than 300 meters from the stream, but allows for shorter distances through engineering measures. Agricultural land: The area has a small agricultural value, which will be more favorable.
Site Characteristics
- Location and Site Selection
- Topography of the Site
- Mineralogical Composition of Clay
The PSSL site is located in the northwest corner with an area of 1.1 hectares. The result shows that the clay minerals constitute more than two-thirds of the mineralogical composition.
Environmental Parameters
- Air and Surface Water Quality
- Ground Water Hydrology and Quality
- Ecological Environment
April & Mayare usually the hottest month in the country caries low humidity as shown in table 3.4. The quality of the groundwater in the project area (based on sample analysis next to the proposed area) indicates the presence of iron, chloride and traces of heavy metals.
Volume Minimization I'
Conceptual Designs of Landfill Components
- Capacity of PSSL
- Design of CCL
- Design of Leachate Collection Layer
The hydraulic conductivity of the collected soil samples was measured using a rigid wall permeameter under the condition of falling head. Tap water was used as the continuous fluid and permeation was performed on the samples until a steady state was reached. The measured hydraulic conductivity is then plotted against the mold water content as shown in Figure 3.10(b).
Base Liner of Pilot Scale Landfill
The amount of liquid in an LCS at a certain time can be expressed by the thickness of liquid on the liner or head on liner. In this PSSL, the base liner includes a leak detection pit system, 15m geological barrier of elayey soil, compacted clay liner (CCL), leachate collection pipe system with a leachate collection layer.
Cross Section of Pilot Scale Landfill
Introductrnn
Excavation of soil was completed successfully by maintaining proper slope of the cell as per design and specification. Very close monitoring was done by the project engineer for proper execution of the works.
Reservation technique of Compacted Clay Liner Material
In PSSL, clay soils collected from 0 to 2 m depth of the site were used for CCL construction as the test results indicated the suitability of the clay. Figure 4.3 shows the clay stockpile that was used to construct the CCL and its subsequent spreading over the compaction bed.
Compacted Clay Liner (CCL)
- Quality Control Assurance
- Liner Requirements
- Sub-Grade Preparation
- Material Selection
- Preprocessing of Material
- Protection
- Final Surface Preparation
After an earth lift has been placed, CQA tests must be carried out for final verification of the suitability of the materials. Each completed lift of the soul-liner as well as the finished liner should be protected.
Preparation of Compacted Clay Liner
The thickness of the layer was maintained such that the resulting thickness of the CCL was 400 mm. The degree of compaction of the CCL was checked in the field using the sand cone test method, as shown in Figure 4.6, which is commonly used as a field compaction test.
Leachate Detection Pipe System
To ensure the gravity flow of the collected leachate, 1% slope to the well was maintained as shown in Figure 4.8. A vertical pipe of larger diameter is connected to the outlet end of the pipe, which is just at the inner surface of the tank, so that the leachate can be collected and the flow can be measured by removing leachate from the top.
Leachate Collection System
To collect the runoff by gravity, the bed was constructed maintaining a 3° slope and the runoff collection pipe is placed in the middle of the cell. The 200 mm thick drainage collection layer was constructed to accommodate a drainage collection pipe with 100 mm diameter holes.
Ground Water Monitoring Well
The sand pack was placed in an annular space around the well screen and extended two feet (or 20 percent of the length of the screen, whichever was greater) above the top and six inches below the bottom of the screen. Fine-grained sand, six inches thick, was placed on top of the sand between the sand and the concrete seal.
Construction Costs
Well screens are slotted plastic tubes and the size of the screen slot was smaller than the surrounding sand. Concrete was placed over the concrete seal to form a seal at least three feet thick, and 6 to 12 inches of fine sand was placed over the concrete seal to reduce grout infiltration.
Introduction
- Design Criteria
- Construction Process
- Waste Deposition
An overview of the location, location, subsurface conditions, and nature of the solid waste to be disposed of at the PSSL is discussed in the following sections. The PSSL consists of the main components of a standard landfill such as (i) a waste disposal cell, (ii) a compacted clay liner on a geological barrier with a drainage layer on top (iii) a top cover with a compacted clay liner, a drainage layer, top soil as vegetation cover, surface runoff and seepage collection system, (iv) gas measurement and management facility, (v) leachate detection and collection system with leachate holding tank, (vi) leachate basin with leachate treatment facility of water, (vii) Vehicle inspection and washing facility, (viii) Access road and site office, (ix) On-going and post-closure monitoring facilities.
Compacted Clay Liner
- Properties of CCL
- Construction of Compacted Clay Liner
- Construction Method
- Leachate collection system
These systems usually consist of a perforated leachate collection pipe evenly spaced in a continuous layer of granular material. The primary function of a leachate collection system is to control the head of leachate acting on the line system.
Water Balance Data
For gravity collection of leachate, the bed was built with an inclination of 30°, and the leachate collection pipe was placed in the middle of the cell. The landfill is 'flat' with a slope of 3%, the collection pipe for leachate has a slope of 2%.
Performance of Clay Liner
- Composition of Leachate and leak detection through CCL
- Observation of monitoring well
From there it moves through the lower layers, although lateral movement may also occur depending on the characteristics of the surrounding material. In general, the extent of this action depends on the characteristics of the soil, especially the clay content.
Summary
PSSL consists of the main components of a standard landfill as (i) waste disposal cell, (ii) CCL in a geological barrier with a drainage layer on top (iii) CCL top cover, drainage layer, topsoil as vegetation cover , Flow surface and infiltrated water collection system, (iv) Gas metering and management environment, (v) Leachate detection and collection system with leachate retention tank, (vi) Leachate pond with facility for drainage treatment, (vii) Facility vehicle inspection and washing, (viii) Access road and site office, (ix) Ongoing and post-closure monitoring facilities. To examine the performance of the CCL, the effluents collected from both the collection and detection pipelines were characterized in the laboratory through the necessary routine tests.
Conclusion
The amount of leachate collected in the leachate collection and detection systems was measured and thereby controlled. Laboratory leachate test results obtained by leachate detection &. collection system shows that the base coat significantly protected contaminant migration.
