Abstract: In order to evaluate acid mine drainage in Okpara Coal Mine, Enugu, seasonal shallow groundwater and surface water sampling in the wet and dry seasons in nine water sample locations was carried out. Coalmine spoil dumps in 4 locations along the Orob stream and Nyaba river banks and 4 soil samples were collected across the study area. The level of acidity, turbidity, temperature, conductivity, and total dissolved solids (TDS) were measured in the field using standard equipment. Anions were determined in the laboratory by titration while heavy metals were assayed using ICP-MS. Results of the analysis indicated that  the quality of water samples in both seasons ranged from acidic to very acidic (2.84-6.05). The TDS values reflect fresh water condition (TDS<1000mg/l). The mean values of F (5.08mg/l), NO₃ (567.67mg/l), PO₄^3- (1.08mg/l), K (12.00mg/l), Al (4.30mg/l), Fe (5.14mg/l), and Mn (3.35mg/l), recorded especially in the wet season slightly exceeded stipulations by WHO (2006) for potable water. Maximum permissible limits of F (1.5mg/l), NO₃^- (50mg/l), PO₄^3- (1.08mg/l), K (12.00mg/l), Al 0.05-0.2mg/l), Fe (0.2mg/l) and Mn (0.4mg/l) are recommended standards by WHO (2006) for potable water. The mean concentrations of heavy metals obtained from analysis of mine spoil (Fe 8871.4ppm, Mn 38.8ppm, Cu 64.14ppm, and Cr 47.14ppm) and in soil (Fe 7.18ppm, Mn 2.95ppm, Cu 1.15ppm, and Cr 1.14ppm) were above background values (Fe 3.05ppm, Mn 38.8ppm, Cu 0.71ppm and Cr 0.50ppm) obtained from coal in this study. Low pH condition (≤6) which is due to acid mine drainage, dissolves heavy metals, which is pernicious to aquatic biota. Water sources in the area are benign for irrigation purposes. Remediation of mine spoil, soil, and water of heavy metals and other pollutants using lime carbonate neutralization, ion exchange, and construction of wetland is apposite to reduce the effect of mine drainage on water sources. 

Abstract: This paper presents the experimental results of the re-investigation of the compressive strength of ordinary portland cement (OPC) concrete and lime concrete (LC) using five selected mix ratios. Materials used in concrete production were ordinary portland cement, hydrated lime, granite chippings as coarse aggregates and river sand for fine aggregate. Optimum values of compressive strength recorded for OPC concrete at 7 days and 28 days of curing were 11.55N/mm² and 26.96N/mm² respectively. These corresponded with mix numbers M₁ and M₅ respectively. Also, optimum values of compressive strength for LC at 28 days and 90 days of curing were 6.12N/mm² and 13.15N/mm² respectively and both corresponded to mix number M₅. The results obtained showed that the compressive strengths at 90 days curing for LC are approximately half of the compressive strength values of OPC concrete at 28 days. Compressive strength values at 90 days for the LC were close to that of the 7 days strength values for OPC concrete. The compressive strength values of LC increased with increasing curing age which informs non-deterioration of concrete. Compressive strengths at 7 days curing of LC showed no results of strength gain. The initial and final setting time for OPC paste were 60mins and 430mins respectively, while that of lime paste were 2880mins (2 days) and 4320mins (3 days) respectively. Grain size distribution for the river sand and granite chippings, showed that the fine aggregates used was poorly graded containing non uniform range of particles, while the coarse aggregate used was poorly graded and contains uniform range of particles. The use of lime concrete for constrcuction purpose results to very low strength of the concrete, therefore this concrete will require the addition of other pozzolanic material to increase its rate of gain of strength.