EVALUATING THE EFFECTIVENESS OF USING DREDGING MATERIAL FROM OLIYAMULLA RETENTION POND AS A LANDFILLING MATERIAL IN COLOMBO, SRI LANKA

Abstract

The Sri Lanka Land Development Corporation (SLLDC) has developed the Oliyamulla Storm Water Drainage & Environment Improvement Project, aiming to control flooding in enhance the physical properties of dredged soil for landfilling. While the dredged soil is chemically acceptable, it lacks desirable natural physical properties for direct the Wattala, Peliyagoda, Kelaniya, Wanawasala, and Kiribathgoda areas by dredging the Oliyamulla retention pond. However, the project faces challenges in space, storage, and disposal. This study observes quarry dust as a cost-effective, eco-friendly substitute for stabilization of soil in landfilling, which is an answer to the prohibitive cost of cement in environmental operations. And assesses the environmental value of dredged material as a disposal site for wastes and demonstrates it to be pH neutral, of low electroconductivity, chlorides, organic matter, minimal heavy metals, and free from harmful toxins. Also, the use of quarry dust as a low-cost and environmentally friendly stabilizing agent for weak and soft soils. Laboratory tests for particle size distribution, Atterberg's limits, and proctor compaction on Oliyamulla retention pond dredged soil showed that mixing quarry dust with soil showed good soil improvement with acceptable landfilling limits. The cost breakdown also established that quarry dust usage is economical compared to other methods of disposal, thus making it an efficient and environmentally friendly method of ground improvement. And research evaluates the feasibility of using quarry dust to use without treatment. Experimental findings show that a 40% quarry dust and 60% dredged soil mixture enhances some significant physical properties like density, particle size distribution, and plasticity index significantly in favour of landfilling.