Foundations for Housing on Reclaimed Mined Lands
Ground conditions in coal-mining regions require special attention when residential development is considered. Today, surface-mining operations can alter landforms through mining and reclamation, thus increasing land suitability for housing and related development. Such “made land,” however, is typically composed of deep soil and rock fills. Such fills undergo long-term settlement under their own heavy weight. Subsurface-mining operations can also affect surface structures by causing land subsidence.
Geotechnical Investigation into the Causes of Cracks in Building: A Case Study of Dr. Egbogha Building, University of Ibadan, Nigeria
The study examined the geotechnical properties of soil supporting Egbogha building that has been revealing deep cracks around its wall. Soil samples were collected around the building for laboratory study. The properties determined were natural moisture content, particle size, Atterberg limits, compaction, and consolidation. The results of the tests show that the site is dominated with poorly graded soil with specific gravity (2.482.63), liquid limit (26%-53%), optimum moisture content (13.50%-26.20%) and maximum dry density (1.50kN/m 3 -1.94kN/m 3 ). According to the soil settlement estimated, the result indicated insignificant settlement at 1.5m depth. According to the classification of potential swell of the soil, the soil has medium potential for shrinkage or swelling. This could be attributed to high clay content in the soil. Hence, the soil has tendency for expansion. This therefore suggested that the cause of the noticed cracks on the structure under study could be as a result of the expansive soil supporting the structure’s foundation. Massive infiltration of water into the foundation occurs during raining season, and on dying up results into differential heave and the effect is pronounced on the wall through cracks.
Soil and Minespoil Fill as Media for Renovation of Nitrogen and Phosphorus in Domestic Wastewater
Development of Appalachian coal mining regions of the USA has been severely hampered by lack of domestic waste disposal technologies suited to fills. The suitability of on-site wastewater treatment and disposal systems (OSWTDS) in fill material is uncertain due to the effects of surface mining on soil physical properties. This research was conducted to evaluate the potential for renovation of N and P present in domestic wastewater by fills produced from mining operations. Nitrogen and P were chosen because of their potential adverse environmental impacts. Soil-fill (a mixture of Jefferson, fine-loamy, siliceous, mesic Typic Hapludult and Muskingom, fine-loamy, mixed, mesic Typic Dystrochrept soils) and minespoil (spoil)-fill (blasted rock material associated with the Taggart Marker and Low Splint Bench coal seams of the Upper Middle Wise Formation) were used in this study. Septic tank effluent (STE) and sand filter effluent (SFE) were applied to spoil-fill columns at four loading rates (0, 5.4, 10.8, and 21.6 L m-2d-1) and spoil-fill columns at one loading rate (21.6 L m-2d-1) for a period of 20 wk. Renovation of wastewater was assessed by determining the concentration of N and P present in column leachate. Reduction of inorganic N (NO3- + NH4+), based on N/Cl ratios, ranged from 14.9 to 32.1% after the varying application rates of STE and SFE passed through the soil columns. However, leachate NO3--N concentrations were still above the 10 mg-1 drinking water standard. The quantity of P emerging from the spoil-fill columns (3.0 mg P L-1) was higher than anticipated and may be related to the indigenous P present in the minespoil. Sorption of P in the soil-fill column decreased with increased STE and SFE application (reductions ranged from 99.1 to 74.4%). Results from this study indicate that there is potential for renovating wastewater in OSWTDS in selected soil-fill areas in reclaimed minelands.