The project area covers Benin City and its environs in Edo State , South-South Nigeria. The area lies from Latitudes 60 15' to 60 27' N, and from Longitude 5030' to 5 045'; and covers an area of 610Km2. The area falls within 1:100,000 Sheet 298 (Benin City).\r\n\r\nThe purpose of the project is to study the effects of waste dumps on the quality of surface and groundwater in Benin City and environs. The methods adopted were geological mapping, hydrogeological mapping, soil sampling, geophysical studies and laboratory analysis of water samples. \r\n\r\nThe area is underlain by the Benin Formation. The formation is recognized by upper horizon of reddish brown to yellowish brown sand, and at the base by yellowish to white loose gravely to pebbly sand with discontinuous beds of clay. Its maximum thickness is about 1829m, and about 800m in Benin City. The formation has a single aquifer system and it is highly permeable, porous and prolific in water yield. \r\n\r\nA total of one hundred and two (102) samples were collected and analyzed for the study. Results for physiochemical parameters showed that the pH ranges from 5.79 to 7.26 with the highest value recorded in the rain-water and the lowest in the borehole water. This indicates that the waters in the area are moderately acidic to neutral. Conductivity ranges from 5µS/cm to 663 µS/cm. TDS values range from 2mg/l to 330mg/l. The values for conductivity corresponded to the values for TDS. The colour of the river waters were pale yellow, while those of the rain, borehole and well waters were colourless. The pale yellow colour of the river waters indicates impurities which could be from waste dumps. Chemically, all the values of the major cations and anions fell within the World Health Organization (WHO) permissible limits for potable water. \r\n\r\nThe dominant cation is calcium while the dominant anion is chloride. Concentration of Nitrate was observed in the waters with relative high values in the well waters. This is because effluent easily attenuates before reaching the deep aquifers. Similarly, coliforms were detected in the water samples except in rain-water. The presence of nitrate and coliform in water indicates some measure of contamination. Concentrations of some trace elements were above the WHO (2006) permissible limits. The trace elements include Fe, AS, Cd, Mn, and Pb. The high values of these trace elements in the waters indicate some measure of contamination. This contamination could be as a result of leachate from waste dumps in the area. The leachate from the waste dumps infiltrates into the groundwater as a result of the porous and permeable nature of the sandstone underlying the area.\r\n\r\nIt was however recommended that surface and groundwater monitoring should be done regularly in the area and that the dumpsites should be converted to concrete landfills for easy control of leachate infiltration into the surface and ground waters in the area.\r\n

Determination of in-situ soil conditions

Hydrogeology, geology and geophysics were used to study the groundwater potentials of Ibadan and its environs. These potentials include quantity, quality and availability of groundwater to the masses of the people. Due to the factor of affordability, hand dug wells are more in use than deep bore holes which are exclusively for the rich. \r\n\r\nRecords from 690 sample points such as wells, bore holes, streams and the results from ninety-three (93) analyzed water samples form the basis of conclusion and recommendations in this report.\r\n\r\nChemical analysis shows HCO3+CO3 dominated water with low to medium salinity hazard. Nitrate is too low there by allaying the fear of present level of contamination. \r\n\r\nIncident of groundwater contamination by leachates could be a problem in the immediate future because of indiscriminate dumping of solid wastes in unauthorized locations and river system. Lowering of groundwater level due to over extraction should be prevented with appropriate laws. The quality of water is fair as more than half of respondents claim they only use the water for domestic chores except drinking. Microbial contamination is average as most wells lack proper hygiene. \r\n\r\nContinuous monitoring and education is necessary to safe guard the groundwater resources of Ibadan and environs.\r\n

The study area lies between latitudes 100 26' to 100 40'N and longitudes 70 19' to 70 33'E with a total surface area of 630km2. The major town in the study area is Kaduna, which is the capital of Kaduna State.\r\n\r\nThe area is underlain by the Nigerian Basement Complex. The dominant rock types are the migmatite-gneiss complex and the Older Granites, which intruded the host gneissic rocks. Prolonged in-situ weathering of the crystalline Basement Complex rocks under tropical conditions has produced a sequence of unconsolidated material (laterites) whose thickness and lateral extent vary extensively. \r\n\r\nThere are three major aquifers in the study area namely weathered overburden aquifer, fractured bedrock aquifer and the stream alluvial deposits aquifer. The three aquifers are interconnected and form one hydraulic system with unconfined water table. \r\n\r\nEighty-eight (88) hand-dug wells, with depths ranging from 0.2 to 11.6m, were studied and thirty-four (34) representative water samples were analyzed in the laboratory. The results were compared with WHO (2006) and NAFDAC standards for drinking water. \r\n\r\nResults of physical parameters showed pH ranged from 4.83 to 7.80, electrical conductivity from 20-980µS/cm and TDS from 10-490mg/l. Results of the cations showed Na+ varied from 1.66-221.20mg/l, Ca2+ from 0.23-92.00mg/l, Mg2+ from 0.12-154.00mg/l, K+ from 0.72-71.48mg/l, Fe2+ from 0.02mg/-0.22mg/l and Pb2+ from 0.18-0.95 mg/l. Results of the anions showed Cl- ranged from 2.67-176.94 mg/l, SO42- from 1.00-250 mg/l, NO3-from 0.05-55.00mg/l ,CO32- from 4.80-50.40mg/l and HCO3- from 2.40-62.00mg/l. Result of the microbial analysis showed Cfu/ml varied from 80-240. The concentration values of the cations and anions (except Fe2+ and SO42-) exceeded the WHO (2006) and NAFDAC recommended limits for drinking water in some places. The dominant cation and anion in the groundwater are magnesium and chloride respectively. The water types are Mg-Cl, Ca-Mg-SO4 and Na- K waters. \r\nThe high concentration of sodium and chloride in the water samples from some places in the study area could be from contamination by saline effluents or leachates from waste dumps. The relative high concentration of nitrate in the study area could be as a result of pollution from septic tanks. \r\nWaste dumps of serious environmental concern were observed at Fire Brigade, Tudun Nupewa, Tudun Wada, Hayin Banki, Ungwan Dossa, and Kawo. Kaduna River around the factories at Kakuri and downstream of River Kaduna are polluted with industrial waste. \r\nIt is recommended that the factories located in Kaduna South should process their industrial wastes before discharging them into the river. In addition, the water from hand-dug wells in the area should be treated before drinking.\r\n

The study area, Katsina town and its environs, is located in Katsina State, northwestern Nigeria. It is defined by longitudes 7° 30'E to 7° 45'E and latitudes 12° 52' 10"N to 13° 07' 10"N with a total area of 625km2.\r\n\r\nThe objective of the project was to study the hydrogeochemical characteristics of water in the area and the impact of waste dumps on the water quality. The methods adopted for the project were geological mapping, geophysical studies, hydrogeological mapping and waste management assessment coupled with laboratory analyses of water and soil samples.\r\n\r\nThe area is underlain by both Crystalline Basement rocks and sedimentary rocks and it lies at the eastern periphery of the Iullemmeden (Sokoto) Basin. The conglomeratic sandstone of Gundumi formation constitute the aquifer in the sedimentary area while the weathered overburden, fractured and jointed zones constitute the aquifers in the basement underlain areas as revealed by geophysical studies.\r\n\r\nThe water type in the project area is earth-alkaline (calcium and magnesium) and predominantly chloride (Cl-) and bicarbonate (HCO3-) water species.\r\n\r\nThere is no officially-designated waste dumpsite(s) in the project area, which resulted in indiscriminate dumping of wastes in unapproved sites such as road sides, drains, streams and river channels. Handdug wells, hand pump boreholes and deep boreholes are located indiscriminately close to dumpsites, latrines, septic tanks and drains.\r\n\r\nThe physical and chemical parameters of the water samples particularly those of the groundwater conformed with international standards of potable water except groundwater in the vicinity of dumpsites, that had electrical conductivity, total dissolved solids, nitrate, chloride and Coliform Counts exceeding the WHO and SON maximum permissible limits in drinking water, which rendered the water unfit for human consumption, unless treated.\r\n\r\n\r\n

The study area, Daura and its environs, is located in Katsina State, northwestern Nigeria. It is defined by longitudes 008° 12' to 008° 26.30'E and latitudes 12° 55' to 13° 09'N with total area of 625km2.\r\n\r\nThe area is underlain by both Crystalline Basement rocks and sedimentary rocks and it lies at the eastern periphery of the Iullemmeden (Sokoto) Basin.\r\n\r\nThe water type in the project area is predominantly alkaline (sodium and potassium) and predominantly chloride (Cl-) and (SO42-) water species.\r\n\r\nGeophysical investigation of Daura town and environs was able to map the groundwater distribution and the extent of infiltration of contaminant plumes from Kwargwam dumpsite, some 250m east of the famous Kusugu well. Geophysical investigation using the electrical method was able to map the groundwater distribution and the extent of infiltration of contaminant plumes from Kwargwam dumpsite, some 250m east of the famous Kusugu well and these conductive plumes have ability to contaminate wells around the dumpsite and even the Kusugu well since contaminant plumes have been reported to infiltrate the subsurface to a depth of 15m into the saturated zones below the water table and could be traceable for over 760m away from dumpsite.\r\n\r\nThe investigations revealed that Daura is endowed with huge industrial and metallic mineral potentials, which can be categorized into four broad groups: aggregate materials (construction); glass sand (silica sand); clays/kaolin and Iron ore. However, it is recommended that the appropriate technology should be employed to effectively harness these mineral potentials so as to enhance the socio-economic well-being of the inhabitants of Daura and its environs.\r\nThe physical and chemical parameters of the water samples conformed to international standards of potable water except for a few water samples having concentrations of certain constituents exceeding the WHO and NSDWQ maximum permissible limits in drinking water, which rendered the water in those localities unfit for human consumption. \r\n\r\nSummary of the recommendations are:\r\n(a) To carry out detailed geotechnical investigation to determine the strength of the clay potential.\r\n(b) Kwagwan dumpsite should be covered up with bentonitic clay or locally sourced clay to prevent further contamination of the groundwater.\r\n(c) The drinking water should be treated with water softening materials in order to reduce its hardness.\r\n\r\n

The study area covers Ilesha and its environs in Osun State, south-western Nigeria. It is defined by latitudes 7°31' to 7° 44' N and longitudes 4° 37' to 4° 51'E and falls within 1:100,000 Sheet 243 Ilesha and covers an area of 625km2.\r\n\r\nThe objective of the project area is to study the hydrogeological characteristics of the area and the impact of waste dumps on the water quality.\r\n\r\nThe methods adopted were geological mapping, geophysical studies, hydrogeological mapping and laboratory analyses of water and soil samples.\r\n\r\nThe rock types in the area in order of abundance are mica schist, quartzite/quartz schist and granite gneiss within these rocks are intrusions of pegmatite and quartz veins.\r\n\r\nThere are peculiar wells that were dry during raining season and have water during the dry season. The clayey nature of the overburden was adduced to have caused delayed recharge of the aquifer due to the low permeability of the overburden materials.\r\n\r\nThe results showed that the waste dumps in the project area have affected the water quality. This is induced by the high nitrate content, high coliform counts and high proportions of trace elements like Iron (Fe), Copper (Cu), Chromium (Cr), Lead (Pb), Nickel (Ni), Cadmium (Cd) and Arsenic (As) which have values that exceed the World Health Organization (W.H.O.) recommended limits. All these are indicators that both the surface and ground waters in the area are polluted (contaminated).\r\n\r\nThe concerned authorities should as a matter of urgency embark on the supply of potable water to the people of Ilesha and environs.\r\n

Effect of rock-water interactions in Calabar area

The study area is approximately 625 km2 , which includes Kaduna town at the centre with large settlements like Tudun Nupawa, Kurmin Mashi, Mondo and Rigasa to the west; Kabala and Barnawa to the south; Malali and Unguwan Rimi to the east; and Unguwar Kanawa, Badarawa and Rigachukun to the east. The major river channel is the River Kaduna which cuts the area from west to east. Other rivers are River Gora to the south and River Kura to the north. There are many streams in the area. The topography is virtually flat lying and the relief of the area ranges from 590m and 653m.\r\n The entire project area is underlain by Precambrian migmatite-gneiss complex which constitutes a greater part of the project area; the Pan Africa granitoids which constitute the second largest suit of rocks in the area; and lastly Metasediments/metavolcanics; mostly schists. The soils derived from these rocks are gravelly clays, sandy clays, clays and clayey gravels. Gravelly clays cover about 33% (208km2 ) of the area, sandy clays cover about 6% (37km 2 ) of the area, clays cover about 41% ( 256km2 ) of the area, clayey gravels cover about 6% (37km2 ) and alluvial silty clays cover about 12% (80 km2 ) of the area. \r\n Eight geotechnical factors were evaluated for the project area: soil bearing capacity, soil compressibility, soil expansivity, soil permeability, slope instability, soil erodibility, flooding and soil acidity.\r\nReddish-brown to red, stiff to hard, residual lateritic gravelly clays cover about 33% (208km2) of the study area. They have high bearing capacities at shallow depth, low compressibility, and they are virtually free from highly expansive clays. They are therefore good founding materials at shallow depth. They have medium permeability and they are of low to medium plasticity.\r\nReddish-brown to red, stiff to hard residual lateritic sandy clays cover about 6% (37km2) of the study area. They have high bearing capacities at shallow depth, low compressibility and they are virtually free from highly expansive clays. They are therefore good founding materials at shallow depth. They have medium permeability and they are of low to medium plasticity.\r\nReddish-brown to red, stiff to hard residual lateritic clays cover about 41% (256km2) of the study area. They have high bearing capacities at shallow depth, low compressibility and they are free from highly expansive clays. They are therefore good founding materials at shallow depth. They have low permeability and they are of low to medium plasticity.\r\nReddish brown to red, medium dense to dense residual lateritic clayey gravels cover about 6% (37 km2) of the area. They have high bearing capacities at shallow depth, low compressibility and they are free from highly expansive clays. They are therefore good founding materials at shallow depth. They have high permeability and they are of low to medium plasticity.\r\nGrey to brown, soft to firm, alluvial silty clays cover about 12% (80km2) of the area. They have low bearing capacities at shallow depth. They are therefore not good founding materials at shallow depth, especially for heavy loaded structures. They have low compressibility and they are free from highly expansive clays. They also have low permeability and they are of low to medium plasticity.\r\nThe area is flat lying; there are no slopes or erosion sites which will pose a problem in the study area.\r\nThe streams constitute the main flood paths during the rainy season when they overflow their channels and the flood zones are the flood plains and the fadama areas along Rivers Kaduna, Gora, Kura and their tributaries. Flooding is expected for about 10% (65 km2 ) of the study area.\r\nThe entire soils are slightly acidic (pH = 5 or 6 ). The acidity is not strong enough to course any environmental, agricultural or engineering problem.\r\nA total of six geotechnical maps have been produced: (i) suitable and unsuitable sites for housing estate development map (ii) suitable areas for waste disposal map (iii) potential flood zone map (iv) Land form map (v) structural map and (vi) documentation map.\r\nThe geotechnical map showing suitable and unsuitable sites for housing estate development shows that 79% (495 Km2 ) of the area is suitable for light loaded housing estate development (like simple houses with wall load of up to 100 KN /m and 1 or 2 storey houses with column load of up to 250 KN) because the soils have high bearing capacities at shallow depth, low compressibility and they are virtually free from highly expansive clays. The areas are not susceptible to erosion or flooding. The map also shows that about 21% (130 Km2)of the area is not suitable for housing estate development because the soils have low bearing capacities at shallow depth and the areas are susceptible to flooding. \r\nThe geotechnical map showing suitable areas for waste disposal shows that about 5% (32km2 ) of the area is suitable for waste disposal because the soils have low permeability, the areas are flat lying or slightly elevated and far away from settlements. Water tables are also very low.\r\nThe geotechnical map showing potential flood zones area shows that about 10% (65km2) of the study area is susceptible to flooding because the areas are the flood plains and fadama areas of Rivers Kaduna, Gora, Kura and their tributaries. \r\nThe land form map shows elevated flat lying lands, low lying flood plains, fadama areas and water courses.\r\nThe structural map shows fractures, joints and faults in the study area. \r\nThe documentation map shows the positions of 93 trial pits (TP) dug and 16 drill holes ( BH) drilled on a geological map. \r\n

Thirty-seven (37) bulk samples taken from a depth of 1.5 meters were analyzed for the determination of Atterberg Limits, Linear Shrinkage, Grain Size Distribution, compaction, and California Bearing Ratio (CBR).\r\n\r\nSixteen (16) borings were made to a depth of 10 meters or to refusal. Standard Penetration Test (SPT) was carried out at every 1.5 meter depth interval and undisturbed samples were collected at the same depth or change of material for Triaxial Compression Test, Grain Size Distribution analysis, and Consolidation. All boreholes stopped at between 1.1m and 5.3 m except borehole 16, cell 056 at NYSC Zonal Office, which went to a maximum depth of 10 meters. \r\n\r\nTen (10) Dynamic Cone Penetrometer (DCP) tests were carried out using a 25mm thin walled pipe with 600 cone. Due to the fine grained nature of the dominantly clayey material, particle size distribution analysis by hydrometer method was employed.\r\n\r\nResults of field and laboratory tests reveal that the entire area on the average is overlain by a 2.5m thick sand, silt, and clay, with spot clay deposits notably at cells 056 (NYSC Zonal office) and 047 (Railway quarters). Soils of Gombe can be classified into nine groups, A-3, A-4, A-5, A-6, A-7, A-1-b, A-2-4, A-2-6, and A-2-7. Of the 37 samples analyzed, 18 are sands and hence non-plastic, 2 are silts and plotted below the A-line on the plasticity chart, while17 others are clays and plotted above the A-line.\r\nResults of SPT tests at cell 001 to 060 gave blow count (N) values of between 2 and 100 with calculated corrected N-values (N?) of between 2 and 58, at 0.5m, 1.5m, 3.0m, with maximum depth of 10m at NYSC Zonal Office. Apart from the boring at NYSC Zonal office, all borings terminated at between 1.1m to 5.3m.\r\nFrom the bulk samples recovered at 1.5m depth, bearing capacity computations based on Triaxial Compression test gave values between 277kN/m2 and 2545 kN/m2. \r\nConsolidation test results show that the materials are of medium to high compressibility. About 90% consolidation occurred within 40-120 metres, indicating secondary settlement upon application of load. The 24-hour soaked California Bearing Ratio (CBR) values between 5.1% and 11.2% shows the materials are good to be used for road subgrade. Values of maximum Dry Density (MDD) ranging between 1.09Mg/m3 and 2.17Mg/m3 with optimum moisture content (OMC) ranging from 9.5% to 19.8% were recorded. Linear shrinkage test shows low shrinkage for the sandy material, and shrinkage of up to 14% for the dominantly clayey materials. \r\n\r\nCivil constructions in Gombe require strict adherence to building standards and the findings of this work in the light of the thick clay that underlies most part of the state capital. This can go a long way in reducing incidence of multiple cracked buildings that are scattered all over the area. \r\n