Transactions on Ecology and the Environment vol 14, 1997 WIT Press, ISSN

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1 Quantitative and qualitative analysis of water pollution in a phreatic aquifer near Muribeca dumping site J. J. S. P. Cabral, G. S. Perrier Jr. & I. D. S. Pontes Fo Civil Engineering Department, Federal University ofpernambuco Abstract Since 1985, municipal waste from Recife Metropolitan Region has been dumped in Muribeca. This site was previously used for agricultural purposes, but in the last 10 years waste has been spread over a 60 hectare area. Soil thickness in the region varies from 3.0 to 15.0 metres over an impervious rock layer. Phreatic aquifer is being contaminated by leachate, and in nearby region several small farmers drink water from shallow dug wells. Geophisical methods have been used to analyse soil and geological layers. Water samples have been collected for several months and analysed in laboratories. Bacteria level were high and also concentration of some substances were above allowed levels. A project to remediate the area has started by building cells to confmate the waste, then recirculate the leachate and increase biodegradation activity.

2 Water Pollution Introduction Municipal solid waste from Recife Metropolitan Region has been dumped in Muribeca site since Solid waste come from Recife city itself and from two neighbour towns (Jaboatao and Moreno), total population is about 1,800,000 inhabitants. Muribeca is a 60 hectare site located 15 Km south of Recife city, on the northeastern coast of Brazil (fig. 1). RECIFE JABOATAO, > \ 'f /L MU»BEQUV4HA RIVER A/ "i4 V / X. MURIBECA LANDFILL / J /" JABOAT&0 RIVER y/ f-.^ f^j 8'10' 8'15' 35W 34'55' 34«50' Figure 1 - Muribeca landfill location. Daily contribution of solid waste is around 2,500 tons and residues are spread all over the place with 15 meter of average height. Solid waste mainly comes from residences, offices and shops, a small percentage comes from industries and hospitals. There is also residues of tree trimming, old house demolitions and septic tank sludge.

3 Water Pollution 297 For several years waste were diposed over soil surface without any technical care. Lack of planning and poor operation caused soil and water degradation, which changed the physical, chemical and biological characteristics of the area. Two years ago a programme has been set up to remediate the area. The first step includes the analysis of the contamination level and the second one includes the tasks for applying remediation techniques. Initially, field and laboratory tests were conducted in order to know the geological geotechnical conditions of the site and to determine the type, concentration and extent of ground and surface water contamination. Electrical resistivity test was also performed to full characterization of the subsoil. Remediation process is being carried out by recirculating the leachate enriched with microorganisms to accelerate the refuse stabilization(mccarty[8], Lima[6] ). Vertical clay liners are built to isolate the waste in a 200 m x 200 m cell and restrict the leachate flux. A system of drainage of gases and liquids is built in each cell. Two cells have already been built and six more will be built in the next few years. Groundwater contamination by municipal landfill has been a point of public concern in the last decades. Case histories, in different countries, have shown that leachate from municipal landfillds resulted in serious groundwater contamination. This paper presents the results of groundwater quality in the neighbourhood of Muribeca. Hydrology and geology Climate in the region is warm and humid, classified as Ams' following KOPPEN classification system. Average temperature is 26 C ranging from 18 C to 32 C. Relative humidity is high, ranging from 83% (May) to 74% (December). Rain season starts in March and finish in August, with monthly precipitation ranging from 170 mm to 360 mm. Total yearly precipitation is around 2000 mm.

4 Water Pollution Topography in Muribeca region shows small hills and flood plains Site's morphology was prospected using tridimensional GPS ( Global Positioning System). Elevation ranges from 10 m up to 70 m above sea level. Muribeca site is located over granitic pre-cambriam rocks that outcrops in some place and is covered by a two meter of non-consolidated quaternary sediments in other place These sediments presents low permeability because the high percentage of clay. Figure 2 shows the basement shield under the solid waste dumping site, the alluvial-fan at the terrace lands and the main fractures detected by photointerpretation. Taking in account the nature of the weathered layer, it is probable that the fractures are closed and impermeable to infiltration. GEOLOGICAL CONVENTIONS Quaternary alluvium Basement Shield x Elevation Point Geological Fracture MONITORING PROGRAM # Points of water collection 0 SPT A Electrical Resistivity Test Q Seismic Test Figure 2 - Geological map of Muribeca landfill On the other hand, alluvial land constituted by sand and gravel presents good aquifer properties. Alluvial layer is 3,0 meter thick near the landfill and the thickness varies up to 15,0 meter at the lower points. Run-off and leachate from the waste site drains to Muribequinha river. It's a small river whose minimum flow in dry season is less than 10 liter/second.

5 Water Pollution 293 Muribequinha discharges into Jaboatao river, which covers an area of 82 and flows more than 200 liter/second in dry season. ( Cabral et al, [1]) Electrical resistivity test were used to provide information about the extent and movement of the leachate in the subsurface and to improve geological information of the site. The apparent resistivity tests were used to provide information about the extent and movement of leachate in the subsurface and to improve geological information of the site. The apparent resistivity of soil was measured in situ using the four-probe electrodes, which were aligned evenly spaced, as described in ASTM G57. Four tests were performed in different location. Table 1 shows the test results. The resistivity of the contaminated regions contrasts with the water resistivity, and so polluted areas can be located and mapped out (Juca it al, [4]). Table 1- Electrical resistivity test results TEST RESULTS SE1 Presents a lateral descontinuity which can be explained by a pronounced moviment of crystalline basement. The apparent resistivity values are compatible with the lithology of a sand saturated alluvium of low salinity. SE2 The soil layer is 2.0 m deep, covering the crystalline basement. Low resistivity values found are due to the soil contamination caused by the leachate. SE3 Performed 700 m far from Jaboatao River, and the results revealed a 12 m deep alluvium layer. SE4 15 m alluvium layer over the crystalline basement. Resistivity values were high, does not indicating any contamination of the subsoil. The weathered soil cover presents low permeability and low porosity; the basement shield has no aquifer properties. So the point of concern becomes the alluvial layer over which Muribequinha and Jaboatao Rivers flow. Several small farmers get water, for domestic purposes, from shallow dug wells in the alluvium. Monitoring wells have been dug on the weathered layer and on the alluvium, water samples have been collected for laboratory analyses.

6 Groundwater quality Water Pollution Landfill leachate forms primarily from rain water that infiltrates through the residues. The amount of leachate could be increased by surface drainage, water from underground springs, and dewatering of wet refuse during compaction and settling. The microbial degradation of biodegradable organics can also generate water that will contribute to leachate generation (Lu et al[7], Roy[9]). The specific composition of the leachate of course depends on the type of waste present. Muribeca solid waste composition presents a wide variety of materials from putrescible organic waste (such as food products and green waste) to relatively inert, non-biodegradable materials (such as demolition debris, glass and plastic). Table 2 presents the average gravimetric composition of the domestic solid waste of Muribeca (Juca et al, [4]) and Table 3 presents leachate composition. Table 2 - Muribeca waste gravimetric composition COMPONENT AVERAGE WEIGHT (%) Organic waste 60 Paper 15 Plastic 8 Metals 2 Glass 2 Others (stones, woods, soils, ceramics, etc) 15 Table 3- Muribeca leachate composition. CONSTITUENT PH Alkalinity as CaCOs Conductivity (u,s/cm) Chloride (mg/1 Cl) COD (mg/1 02) BOD (mg/1 02) Calcium (mg/1 Ca) Magnesium (mg/1 Mg) Sodium (mg/1 Na) Potassium (mg/1 K) RANGE AVERAGE

7 Water Pollution Pollution of groundwater by landfill leachate is well-known. Over 80% of 300 landfills investigated in California have been found to be polluting groundwater (Lee and Jones, [5]). Once contaminants reach grondwater, their concentration can be reduced by dispersion and dilution, depending on the degree of leachate-groundwater mixing. Sometimes the situation becomes more complex if geochemical interations influence the fate of contaminants. Griffin et al [2] found that Cl and Na in landfill leachate were not attenuated by calciun-saturated clay, although several other constituents are. Chloride is not adsorbed significantly by most subsurface materials and has long been used as an indicator of groundwater contamination. Chloride concentration on Muribeca leachate ranges from 1,100 to 2,150 mg/1 of Cl. Figure 3 shows the chloride concentration in PI, P8, and P9. Figure 2 shows the location of water sample points. Samples from surface water, groundwater and leachate have been collected every 3 months or 6 months to laboratory analysis. PI is on Muribequinha river befor receive leachate flow; P8 is a shallow dug well and P9 is a spring on the botton of a small valley. These three points do not receive leachate directly but could receive through soil percolation. CHORIDE X TIME Time Figure 3 - Chloride concentration in time.

8 Water Pollution Although chloride concentration is high in ieachate, it is low in these points perhaps because the percolation through the weathered layer is small. The soils of Muribeca were studied both in situ and in laboratory. Hydraulic conductivity was found 1.2xlO~ m/s and the soil presents 32% of clay in average. Pollutant propagation through the alluvium is higher than in Muribeca soil. A Hvorslev Piezometer Test (Hvorslev, [3]), also called Slug Test, was performed in point PM1, and results are presented in figure 4. Hydraulic conductivity was computed as 5.4 x 10"^ m/s. SLUG TEST o 0,37 0, Time (seconds) Figure 4 - Slug Test on Muribeca alluvium. Some wells were drilled to collect water samples from the alluvium to laboratory analyses. Results are presented on Table 4. Concentration of almost all the constituents are high on wells PM-2 and PM-3, because of infiltration of leachate from surface flow into the alluvium.

9 Water Pollution 297 Table 4 - Constituent concentration on alluvial aquifer, a) March 1996 b) July 1996 CONSTITUENTS ph Alkalinity as CaCOg Conductivity (fis/cm) Chloride (mg/1 Cl) COD (mg/1 02) BOD (mg/1 Oz) Total solids (mg/1) Volatiles solids (mg/1) Calcium (mg/1 Ca) Magnesium (mg/1 Mg) Sodium (mg/1 Na) Potassium (mg/1 K) PM March 1996 PM-2 PM b) July 1996 PM PM PM Conclusions Muribeca dumping site is located over an impervious bedrock with only a very thin soil layer. This bedrock is not fractured and provides a natural barrier to contaminant plume. Soil layer in Muribeca surroundings presents low permeability and high clay percentage. Pollutant propagation through soil layer is not high. Leachate produced by dumping site flows on surface to the rivers and could infiltrate somewhere on places of higher hydraulic conductivity. Alluvial aquifer downstream Muribeca site presents high concentration level of leachate constituent. Analyses of groundwater contamination requires a multidisciplinary approach. Climatic variables, geological parameters, geochemical interactions are important to achieve a better understanding of leachate propagation and water pollution.

10 298 Water Pollution Acknowledgments The experimental program described previously was performed by a multidisciplinary group from Federal University of Pernambuco, with the support of CNPq and EMLURB/PCR. The authors are also indebted to Professors and Engineers A.A.Santos (Cartography), J.F.T. Juca (Geotechnics), W.D.Costa (Geology), E.Feitosa (Geophysics), S.Calado (Chemistry), A.Menelau, A.E.C.Juca and L.M.Q.Lima (Sanitary). References 1. Cabral, J.J.S.P.; Juca, J.F.T.; Menelau, A L (1995), Surface and groundwater quality near a urban solid waste dumping site, Environtech 95, Rio de Janeiro, pp Griffin,R.A, Shimp,N.F., Steele,J.D., Ruch,RR, White,W.A and Hughes,G.M. (1976), Attenuation of pollutants in municipal landfill leachate by passage through clay, in Environmental Science and Technology, 10, pp Hvorslev, M.J. (1951), Time lag and soil permeability in ground water observations, US Arm Corp of Engineers Waterways, Experimentation Station, Bulletin 36, 50 pp. 4. Juca, J.F.T.; Mariano, M OH; Barreto Campello, EM (1996), Ground and surface water contamination due to municipal solid waste in Recife, Brazil, 2nd Int. Congress on Environmental Geotechnics, Osaka, Japan. 5. Lee, G.F. and Jones,R A (1991), Landfill and groundwater quality, in Groundwater, Vol 9, N 4, pp Lima, L.M.Q. (1994), Bioremediation of the contaminated sites by solid waste disposal, Geoambiental'94, COPPE/UFRJ (in Portuguese). 7. LuJ.C.S., Eichenberger,B. and Stearns,RG. (1985), Leachate from municipal landfills, in Pollution Technology Review, N 119, Noyes Publications, Park Ridge, NJ. 8. McCarty, PL (1964), Anaerobic waste treatment fundamentals, Public works, Vol 95, N9,l 0,11, Roy, W.R. (1994), Groundwater contamination from municipal landfills in the USA, in Contamination of groundwaters, Ed. by DC Adriano, A.K. Iskander and ID Murarka, Science Reviews, pp

Groundwater and Surface Water Overview of the Lochend Area, Alberta

Groundwater and Surface Water Overview of the Lochend Area, Alberta The Lochend Industry Producers Group (LIPG) conducted a hydrogeological / hydrological study in the Lochend operating field. The objectives