ORIGINAL PAPER

Site characterization and risk assessment in support of the designof groundwater remediation well near a hazardous landfill

Tajudeen M. Iwalewa & Mohammed H. Makkawi

Received: 30 August 2013 /Accepted: 22 January 2014# Saudi Society for Geosciences 2014

Abstract This study was undertaken to support a remediationtechnique that will be applied to contaminated groundwater inthe vicinity of Ghonan landfill, eastern Saudi Arabia. Prelim-inary field investigations involved hydrogeological character-ization of the entire area. The improved understanding of theunderlying geology and groundwater movement gained fromthe preliminary studies helped in determining a test site withinthe proximity of the landfill. One remediation well and fivemonitoring wells were constructed at the test site. Optimumpumping rate for the remediation well was determined torange from 2.642 through 7.926 gallons per minute (gpm)(0.01 m3/min through 0.03 m3/min) based on site-specifichydrogeological investigations and mathematical simulation.A concentration of 0.05 mg/L of methyl tertiary-butyl ether(MTBE) contaminated the aquifer in the test site. The simu-lated concentration of MTBE at the point of exposure after aperiod of 2 years was found to be higher than the maximumcontaminant level of 0.005 mg/L set by the United StatesEnvironmental Protection Agency (U.S. EPA). The results ofrisk assessment conducted revealed that domestic use ofgroundwater in the study area through any of the exposurepathways (ingestion, dermal contact, and inhalation in theshower) may lead to development of health risks to humanreceptors. The landfill, which is being operated as a hazardouslandfill and a dump site, may become a source of groundwaterpollution in its vicinity in the near future. As a potential health

risk, it should be controlled properly by remediating theaquifer and implementing environmental measures to thelandfill users.

Keywords Groundwater contamination .MTBE .Hazardouslandfill . Optimum pumping rate . Remediation . Riskassessment . Saudi Arabia

Introduction

This case study expounds the vulnerability of shallow ground-water to landfill/open-dump contamination. Interactions be-tween landfills/open dumps and shallow unconfined aquifershave been widely documented. Studies of landfills on uncon-solidated sand and gravel aquifers by Golwer et al. (1975);Palmquist and Sendlein (1975); Kimmel and Braids (1974,1975; 1980), andWexler (1988) have established that zones ofleachate contaminated groundwater can extend many hun-dreds of meters beyond the source zone. In most circum-stances, contamination can cause serious deterioration of aqui-fers used for groundwater supply (Apgar and Satherthwaite1975). Reyes-Lópeza et al. (2008) carried out geophysicalstudies that showed that the zone of leachate’s influencestretches for approximately 80 m of Guadalupe Victoria land-fill in Mexico with geochemical data corroborating the effectsof the landfill leachate on groundwater. The simulation resultof a study conducted by Jhamnani and Singh (2009) revealedthat leachate from Bhalaswa landfill site in Delhi, which isbeing operated as a dump site, was found to be having a highconcentration of chlorides. They found that the observedconcentration of chlorides in the groundwater within 75-mradius of the landfill facility was in consonance with thesimulated concentration of chloride in the groundwater. Tounderstand the aerial extent of groundwater contaminationdue to lead migrating from Richmond landfill in Bunawayo

M. H. MakkawiEarth Sciences Department, King Fahd University of Petroleum andMinerals, Dhahran, Saudi Arabia

Present Address:T. M. Iwalewa (*)Department of Earth Sciences, University of Cambridge, Cambridge,UKe-mail: tajudeen@kfupm.edu.sae-mail: tmi21@cam.ac.uk

Arab J GeosciDOI 10.1007/s12517-014-1300-7

into the underlying unconfined aquifer, Kubare et al. (2010)applied a one-dimensional advection-dispersion model to pre-dict the down-gradient migration of lead into the aquifer. Theydetermined 400 m as the safe distance for potable waterabstraction, and the model simulations showed that the aerialextent of the pollution would increase with time. By applyingthe aggregrate index method to assess groundwater qualityaround a municipal solid waste dumping site, Bhalla et al.(2012) found that groundwater quality improves as one movesaway from the landfill site. The study also revealed a decreasein groundwater quality with time.

In the present study, a Phase I Environmental Site Assess-ment (ESA) conducted in the study area indicated a potentialfor contamination. The existence of a hazardous landfill and adump site in the area constitutes a “recognized environmentalcondition” and an area of risk. The ESA found that thehazardous landfilling has been occurring since 1979. Limitedgroundwater sampling during Phase II and on-site analysisconducted confirmed the presence of methyl tertiary-butylether (MTBE). Thus, the primary objective of this study isinvestigation of subsurface conditions, the pathways availableto transport MTBE in the study area, the rate at which it willmove, and its concentration when it reaches a receptor toprovide insight in the design of a groundwater remediationsystem close to the landfill.

The study area (Fig. 1) is located in Ghonan, an opendesert land along Dammam–Abqaiq Road, eastern SaudiArabia. Ghonan area, which is designated as hazardouswaste landfill site, is part of Jafoura Desert. The studylocation is covered by sand sheets and dunes. The sandsheets are flat sandy plains, mostly covered by scattered

perennial grasses and herbs (vegetation cover ranges from1 to 10 %).

The study area lies in the Arabian Platform, which has beenthe focus of attention of numerous numbers of previous liter-atures especially that the region is water stressed. The aquifersystem in the area was prominently studied by Italconsult(1969); BRGM (1977); GDC (1980); Backiewicz et al.(1982); Burdon (1982); Lloyd (1986, 1987, 1990, 1997),Lloyd and Miles (1986); Abderrahman and Rasheeduddin(1994); Abderrahman et al. (1995); Edgell (1997), andIwalewa et al. (2013a,b). The lithologic succession, basedon the hydraulic properties of various units, can be dividedinto aquifers and intervening aquitards, namely, from bot-tom to top, Umm Er Radhuma (UER) aquifer, the Rusaquitard, the Dammam aquifer, and the Neogene aquifer.The aquifers are composed of limestones, dolomitic lime-stones, and dolomites, while the aquitard is made up ofshales, marls, and anhydrites, except for infrequent localfacies variations (Rasheeduddin et al. 2001). The aquifers,being a carbonate aquifer system, are highly karstified (Al-Saafin et al. 1990; Benischke et al. 1991) which makesthem susceptible to contamination.

Preliminary field investigation

Ghonan landfill has been in operation for more than threedecades; however, very limited hydrogeological informationof the area exists. Thus, a preliminary investigation of the areawas crucial.

Fig. 1 Location map of the study area. The area is located north of Dammam–Abqaiq Road in eastern Saudi Arabia. The landfill (indicated by dashedpolygon) is in the southeast of the study area. The shaded area shows the potential location for installing the remediation system (test site)

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Five existing monitoring wells in the area were studied.The moni to r ing wel l s were u t i l i zed to obta inhydrogeological information and improve the understand-ing of groundwater flow system in the area. The improvedunderstanding is critical for prioritizing and implementingstrategic action to address groundwater contamination inthe study area.

Well borings were conducted with the use of rotary drillingand water flush. Maximum boring depth was 20 m belowground surface (bgs). Moderately weak, buff white, marl, andweathered limestone were prominently encountered. They areoverlain by small debris of loose, light brown, silty sand.Limestones are dominant in the aquifer. The features of thecore samples obtained suggest that the uppermost aquifer inthe study area is most probably Neogene aquifer. The aquiferis shallow, unconfined, and heterogeneous.

The hydraulic head above mean sea level in the monitoringwells ranges from 30.5 through 31.5 m (Fig. 2). Generally, thehead distribution appears to be decreasing prominently towardthe eastern, N-NE, and SE part of the area. The water tablesurface represented by head distribution reflects fairly thetopography of the site.

Calculus directional derivative in Surfer software (GSI2002) was used to estimate the hydraulic gradients of thestudy area based on the calculated piezometric heads. Thefirst derivative grid option was used to produce the hydraulicgradients. The estimated average hydraulic gradient in the areais 0.0003.

Slug tests were conducted to estimate the hydraulic con-ductivities (K) of Wells 2 and 4, using Hvorslev’s (1951)procedure. The choice of slug test is because the monitoringwells were of small diameters and it is relatively cheap toconduct. Slug test field data used include the volume ofinitially added water, well geometry including casin radius(r), length of open screen (L), and filter pack radius (R), andinformation on the hydrogeological setting adjacent to thewell screen. Estimated saturated hydraulic conductivities fromslug tests and well information are 9.26372×10−6 m/s for well2 and 5.02676×10−6 m/s for well 4.

The estimated hydraulic conductivity values indicate slightheterogeneity of the aquifer material in the study area. Thiscan be attributed to presence of karst, facies, and thicknessvariations which characterize the Neogene aquifer. The fairlyhigh hydraulic conductivity values reflect that the aquifer

Fig. 2 Piezometric head contourmap of the study area. Theexisting monitoring wells aredenoted by blue triangles. Notethat the head contours weresuperimposed on Google map(base map) of the study area toreflect the piezometric heads asthey relate to every point in thestudy area

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material is mainly made up of karstified limestone, whichmeans that the groundwater is highly susceptible tocontamination.

Groundwater flow rate was estimated by utilizing headdistribution, hydraulic gradient, groundwater flow direction,and hydrogeologic section. K value was taken as 4.8832×10−6 m/s (average K for Wells 2 and 4). The width of theconsidered part of the aquifer in the general direction ofgroundwater flow was estimated as 3,000 m, while saturatedthickness of the aquifer was taken as 4 m. Groundwater flowrate (Q) in the study area was estimated by applying theDarcy’s law to be equal to 1.758×10−5 m3/s.

For water budget, transpiration (T) was considered to bezero due to negligible amount of vegetation in the area. Withincompressibility assumed, due to absence of pumping activ-ities, inflow (RI) and outflow (R0) were both taken as thegroundwater flow rate earlier estimated as 1.758×10−4 m3/s (i.e., 5,540 m3/year). Values of precipitation (P) and evap-oration (E) were derived from past study by Presidency ofMeteorology and Environment (PME), Saudi Arabia, in year2010 and the values were 70 mm/year and 2500 mm/year,respectively. Change in storage (ΔS) is expressed as an equa-tion relating these components (Schwartz and Zhang 2003)and was estimated as ‐2.9×107m3/year. This result indicatesnegative change in storage which implies a decrease in storagetermed as deficit due to dryness of the region.

Site-specific investigations

The preliminary field investigation provided a generalizedhydrogeological framework and an improved understandingof the study area. This served as a guide in determining a testsite (the shaded area in Fig. 1) within the study area where thepresent study was focused. The test site was subjected tofurther hydrogeological investigations in order to install aremediation system at a later stage.

Five groundwater samples were collected from the wells inthe test site in July 2012. The samples were analyzed todetermine the groundwater characteristics and concentrationsof the major ions. Analyses were also conducted to determineconcentrations of benzene and MTBE in the study site. Theseanalyses were carried out using gas chromatography-massspectrometry (GC-MS), turbidimeter, pH, and conductivitymeters.

The groundwater temperature, pH, conductivity, turbidity,dissolved oxygen (DO), total dissolved solid (TDS), and totalhardness were measured on-site, and the average values weredetermined as 31.72 °C, 7.17, 3.65 dS/m, 1.35 UTV, 7.19 m/L, 2,257 mg/L, and 916, respectively. The average concentra-tion of sodium (Na) in the groundwater is 556 mg/L. Magne-sium (Mg) and calcium (Ca) concentrations are 78 and226 mg/L, respectively, while potassium concentraion is

18.1 mg/L. The average chloride concentration in the ground-water is 987 mg/L, and that of sulphate is 363 mg/L. Nitrateconcentrtion is about 16.4 mg/L. Concentrations of benzeneare very low and in some wells below detection level. How-ever, average concentration of MTBE is approximately0.057 mg/L. This concentration is in excess of ten times themaximum contaminant level set by U.S. EPA. Therefore,MTBE was considered as the contaminant of interest.

Application of noninvasive geophysical methods

Geophysical methods provide a rapid and cost-effectivemeans of understanding subsurface hydrogeology. The useof these methods for groundwater exploration has increaseddramatically over the last decade as a result of rapid advancesin electronic technology and the development of numericalmodeling solutions (Muchingami et al. 2012). For this study,the noninvasive electrical resistivity and ground-penetratingradar (GPR) methods were utilized to determine the watertable position at the test site.

As recommended by ASTM D6431-99 (2010), use of elec-trical resistivity involves placing four-electrode arrays in con-tact with soil or rock. In this study, the profile was made up of24 electrodes, and the system used was Syscal R1 Plus bySchlumberger. The electrodes were arranged in four-electrodearrays in sequence of set A, M, N, and B. Electric current wasapplied to electrodes A and B and electric potential (V) wasmeasured between the inner electrodes M and N. The elec-trodes were spaced 5 m apart covering a total distance of 115 m.

From the pseudo cross section of apparent resistivity(Fig. 3), the lowest resistivity layer is around 16.1 m bgs. Thislayer was observed in the horizontal direction between 65 and78-m distance. Lowest resistivity corresponds to highest con-ductivity region, since both have an inverse relationship. Highconductivity is associated with the presence of water table.

To support previous electrical resistivity findings, ground-penetrating radar (GPR) was utilized and pulled through adistance of 25.6 m to the north and 25.6 m back to the south ofthe test site. Reflection measurements in the to-fro directionswere taken for quality control. The data obtained were proc-essed using RADAN version 6.5 (GSSI 2012).

Figure 4 shows the real-time radar image of the profile.First good reflection occurred between 15 and 16 m bgs. Thewave started from the ground surface (0 m) and traveleddownward with very low amplitude up to 15 m bgs. Beyond15 m, there was a change in the wave shape into a wiggle-likeform signifying higher amplitudes. The change in wave be-havior continued to the lowest depth (40 m bgs). The wave’scontact with the phreatic zone accounts for the change in thewave motion. The point at which this change markedly oc-curred was 16.2m, which signifies the water table position. Ofinterest is that this water level position corroborates the resultobtained by Al-Shuhail and Al-Shaibani (2012) using seismic

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refraction profiling at a site about 7 km east of the presentstudy area. They reported a water table value of 15 m bgs incontrast to 16.2 m bgs obtained in the present study. Thedifference in the water table values is attributed to water tablegradient because the general flow direction is towardthe east.

Construction of new wells in the test site

Cable tool drilling, also known as percussion drilling or spud-ding, was used to construct one remediation and five moni-toring wells. The positioning of the wells (Fig. 5) was deter-mined based on the best knowledge of hydrogeological con-ditions of the site and geophysical investigations.

Figure 6 illustrates the hydraulic head profile of the testsite. The locations, total depths, and positions of screens foreach well are clearly depicted. The trend of hydraulic headsreflects a general flow pattern fromwest to east. The trend alsoindicates small differences in the values of heads between theneighboring wells, which supports the previously obtainedvalue of hydraulic gradient.

Hydraulic conductivity of the test site was determinedusing falling head approach. Slug tests were conducted atthe remediation well and monitoring well 1 (M1) to providemore appropriate estimates of the hydraulic conductivity ofthe site.

AQTESOLV software (HydroSOLV Inc. 2007) used thedesign of the wells with the results of the slug test to calculatethe hydraulic conductivities of the area surrounding the wells.

Fig. 3 Observed apparent resistivity and calculated data resistivity obtained within the study site with Res2Dinv software

Fig. 4 Radar image of the studysite up to 40 m bgs. The solid lineindicates the point where changein wave behavior was observed.This point represents water tableposition

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Figure 7 shows an example of the graph of normalized headagainst time for the remediation well. The software estimatedthe hydraulic conductivity (K) of the area of the aquifersurrounding the remediation well and M1 as 6.318×10−6m/sand 8.337×10−7m/s, respectively.

Determination of optimum pumping rate for the proposedremediation well

Optimum pumping rate is one of the considerations that mustbe addressed in the design and installation of the remediation

well. The well has to operate continuously as contaminantscontinue to arrive. Therefore, it is of paramount importance todetermine a pumping rate that can extract maximum amountof contaminated water without inducing an excessive draw-down in the remediation well. This is important to prevent thesystem from shutting off to avert contaminant rebound anddamage to the equipment.

PC-based computer code, WELLz 2.0 (Schwartz andZhang 2003), was utilized to estimate the optimum pumpingrate for the remediation well. Wellz 2.0 facilitates the predic-tion of drawdown caused by pumping wells in various typesof aquifers and is suited for complex situations involvingseveral wells and bounded aquifers.

The assumed pumping rates (Q) used range between 0.001and 1 m3/min (0.2642 and 264.2 gpm). The assumed pumpingtimes (t) range from 1 h through 180 days. Vertical hydraulicconductivity was taken as one-tenth of the horizontal hydrau-lic conductivity bearing in mind that the aquifer materials areanisotropic, allowing horizontal flows more readily thanvertical flows. By using the estimated aquifer parame-ters, WELLz 2.0 was applied to simulate the draw-downs (s) induced by each pumping rate for everypumping time (t). The results were used to plot hygro-graphs of s against t.

Hydrographs of the simulation results are shown inAppendix. From the simulation results, considering a draw-down that should not exceed 2.5 m in the remediation well,optimum pumping rate ranges between 2.642 and 7.926 gpm(0.01 m3/min and 0.03 m3/min). Higher Q values could

Fig. 5 A photo of the test site (looking westward) showing the positionsof the wells

Fig. 6 Water table profile of the study site. Note that elevation between 25 m and the mean sea level (0) is not to scale

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seriously lower the water table in the test site below the pumplevel, which could lead to contaminant rebound and damageto the remediation system that is to be installed.

Analytical modeling and risk assessment

Contaminant properties and site-specific conditions imposeconsiderable complexities on fate and transport of contami-nants in the subsurface. It is important to consider these factorsin risk assessment as they have the potential to affect themobility and toxicity of contaminants (Cushman et al. 2001).

The hydrogeological data obtained during the site-specificinvestigations were utilized to conduct an analytical aquifermodeling and a risk assessment of the study location. Thepositions of monitoring well 1 (M1) and remediation wellwere considered as the contamination point and point ofexposure, respectively, as shown in Fig. 8. Groundwater wasassumed to flow under the natural gradient of the study site,and the estimated flow velocity between the two wells, basedon local hydraulic conductivity and porosity values, was 3.7×10−6m/s.

As the aquifer is mainly used for domestic purpose, sus-ceptibility of the study site to contamination and possiblehealth risk was assessed with RISC Workbench (SSG 2010).Field assessment and laboratory analysis showed the presenceof MTBE in the test site. A concentration of 0.05 mg/L of

MTBE contaminated the aquifer at the contamination point.Saturated zone degradation rate for MTBE was 1.9×10−3day−1. This value was used together with the estimatedaquifer parameters to simulate the concentration of MTBE atthe point of exposure for the next 2 years.

The results indicate that concentration in the first year wouldbe 2.61×10−2mg/L. At the end of the second year, the concen-tration would be 1.30×10−2mg/L. These results imply that

Fig. 7 Graph of normalized headagainst time for the remediationwell

Fig. 8 Schematic map of the test site showing the new monitoring wellsand the remediation well. Note that the well point marked 7 is the positionof the existing well 2

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concentrations at the point of exposure for MTBE at the end ofthe first and the second year would be above the maximumpermissible limit of 0.005 mg/L set by the U.S. EPA.

Utilizing the RISC Workbench, human health risk fromconsumption of the contaminated aquifer at the exposure pointin the study site was assessed. Exposure pathways were as-sumed through ingestion, dermal contact and inhalation in theshower. Exposure duration was 2 years. The receptor is anadult with body weight of 72 kg.

Groundwater ingestion rate was 1.271 day−1, and lung re-tention factor was considered as 1. Flow rate of shower was 8 L/min, while 18,400 cm2 was taken as the total skin surface area.Inhalation rate in shower was considered as 0.6 m3/h.

Based on the aquifer parameters, concentration ofMTBE, andreceptor specific data, assessment of risk of the receptor wascarried out. Results show that if the frequency of exposure ismaximum, risk for groundwater ingestion would be 7.74×10−4,while risk for dermal contact during shower and inhalationduring shower would be 3.74×10−6 and 5.91×10−5, respec-tively. This shows that groundwater ingestion has the highest riskamong the exposure routes, followed by inhalation during show-er. Dermal contact during shower has the lowest risk. Total risk atmaximum frequency of exposure is 1.24×10−4.

The cumulative distribution function (Fig. 9) clearly showsthat risk is proportional to frequency of usage of the ground-water. However, at frequency of exposure between 0 and79 %, there would be no significant risk. This implies thatthe most probable risk would only be possible at the maxi-mum frequency of exposure (i.e., 80–100 %).

Conclusions

The combination of preliminary and site-specific investiga-tions has proven to be a suitable approach for site character-ization for groundwater remediation purpose. Both

investigations provided appropriate data sets for analyzingspatial variability and subsurface hydrogeologic conditionsthrough application of fundamental hydrogeologicalconcepts.

The noninvasive geophysical methods proved to be usefulin terms of detecting and mapping groundwater table position,especially in this case that there was paucity of priorhydrogeological information of the study area. Thesemethods do not require drilling and so avert the riskof further contamination of the groundwater. Geologicaland hydrogeological data obtained through the ground-water wells complement the geophysical results by pro-viding a more complete interpretation. The successfuldetermination of optimum pumping rate for the remedi-ation well that is to be installed at the site has set areference foundation for the subsequent aquifer cleanupwork plan.

It is evident from the theoretical risk assessment results thatGhonan landfill may be a cause of environmental and healthconcerns in the near future. With the expected continualgeneration of large volume of industrial wastes in the future,the disposal of such wastes in Ghonan landfill poses obviousthreat to the groundwater resource in the area. It would beadvisable that a groundwater environmental quality monitor-ing program should be supported. The program could bebased on implementing a hierarchical site investigation ap-proach for future targeted measures. Moreover, an activeremediation measures should be taking place to restore theshallow contaminated aquifer.

Acknowledgments The authors acknowledge the financial supportfrom King Abdulaziz City for Science and Technology (KACST) andKing Fahd University of Petroleum and Minerals (KFUPM) under theProject 09-WAT776-04. The authors wish to thankMr. Mohammed Aqeland Mr. Mushabab Bin Qassem Yahya for their field technical assistance.The authors also wish to thank two anonymous reviewers for theirconstructive comments.

Fig. 9 CDF showing risk againstfrequency of exposure

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Appendix

Simulation results showing hydrographs of drawdown(s) against time (t) for the remediation well. It is clear

from the hydrographs that the optimum pumping ratefor efficient performance of the remediation system thatis to be installed in the study site lies between 2.642and 7.926 gpm.

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References

AbderrahmanWA, RasheeduddinM (1994) Groundwater budgeting for amulti-aquifer system using numerical techniques, Arab Gulf. J SciRes 12:29–40

Abderrahman WA, Rasheeduddin M, Ibrahim MH, Esuflebbe JM,Eqnaibi B (1995) Impacts of management practices on groundwatercondition in Eastern Province, Saudi Arabia. Hydrogeol J 3:32–41

Al-Saafin AK, Bader TA, Hötzl H, Shehata W, Wohnlich S, Zötl JG(1990) Groundwater recharge in an arid karst area in Saudi Arabia,Selected papers on hydrogeology, vol 1. Heise, Hannover, pp 29–41,6 Abb., 2 Tab

Al-Shuhail AA, Al-Shaibani AM (2012) Characterization ofSabkhaJaybUwayyid, eastern Saudi Arabia using seismic refractionprofiling. Arab J Geosci. doi:10.1007/s12517-011-0366-8

Apgar M, Satherthwaite WB (1975) Groundwater contamination associ-ated with the Llangollen landfill, Newcastle County, Delaware.Proceedings of Research Symposium, Gas and leachates from land-fills: formation, collection and treatment, New Brunswick, NewJersy, 15–18 March 1975

ASTM D6431 – 99 (2010) Standard guide for using the direct currentresistivity method for subsurface investigation. http://www.astm.org/Standards/D6431.htm. Accessed 12 October 2012

Backiewicz W, Milne DM, Noori M (1982) Hydrogeology of Umm ErRadhuma aquifer, Saudi Arabia, with reference to fosil gradients. JEng Geol 15:105–126

Benischke R, Fuchs G, Weissensteiner V (1991) Karst phenomena of theArabian Shelf Platform and their Influence on UndergroundAquifers. Fourth Report. Speleological Investigations in theShawyah-Ma'aqla Region, Eastern Province, Saudi Arabia, Vol. I,pp 70, 1 fig.; Vol. II, 14 maps, Graz

Bhalla G, Swamee PK, Kumar A, Bansal A (2012) Assessment ofgroundwater quality near municipal solid waste landfill by anAggregate Index Method. Int J Environ Sci 2:1492–1503

BRGM (Bureau de Recherches Géologiques et Minières) (1977) AlHassa development project. Groundwater development studies andmanagement programme. Final report, vol. 3, App II-7, Results ofisotopic analysis, BRGM, Paris

Burdon DJ (1982) Hydrogeological conditions in the Middle East. Q JEng Geol 15:71–82

Cushman DJ, Driver KS, Ball SD (2001) Risk assessment for environmen-tal contamination: an overview of the fundamentals and application ofrisk assessment at contaminated sites. Can J Civ Eng 28:155–162

Edgell HS (1997) Aquifers of Saudi Arabia and their geological frame-work. Arab J Sci Eng 22:3–31

GDC (Groundwater Development Consultant) (1979) Final draft ofUmm-Er-Radhuma, Ministry of Agriculture and Water, Riyadh

Golwer A, Matthess G, Schneider W (1975) Effects of waste deposits ongroundwater quality. In Groundwater Pollution, Proceedings of theMoscow Symposium, 1971, 159–166: 1AHS Publ. no.103

GSI (Golden Software Inc.) (2002) Surfer8 user’s guide. Contouring and3D surface mapping for scientists and engineers. http://www.wi.zut.edu.pl/gis/Surfer_8_Guide.pdf. Accessed 16 August 2012

GSSI (Geophysical Survey Systems Inc.): RADAN® 7: Optimized forWindows® 7. http://www.geophysical.com/software.htm. Accessed11 September 2012

Hvorslev (1951) Time lag and soil permeability in groundwater observa-tions, Waterways Experiment Station Corps of Engineers. U. S.Army, Vicksburg

HydroSOLV Inc. (2007) AQTESOLVmanuals, all-in-one software pack-age for the analysis of pumping tests, slug tests and constant-head

tests. http://www.aqtesolv.com/manual.asp. Accessed 26 August2012

Italconsult (1969)Water and agriculture development studies for Area IV,Final Report, Ministry of Agriculture and Water, Riyadh

Iwalewa TM, Makkawi MH, Elamin AS, Al-Shaibani AM (2013a)Groundwater management case study, eastern Saudi Arabia: PartI—Flow simulation. Eur J Sci Res 109:633–649

Iwalewa TM, Makkawi MH, Elamin AS, Al-Shaibani AM (2013b)Groundwater management case study, eastern Saudi Arabia: PartII—Solute transport simulation and hydrochemistry. Eur J Sci Res109:650–667

Jhamnani B, Singh SK (2009) Groundwater contamination due toBhalaswa landfill site in New Delhi. Int J Environ Sci Eng 1:121–125

Kimmel GE, Braids OC (1974) Leachate plumes in a highly permeableaquifer. Ground Water 12:388–392

Kimmel GE, Braids OC (1975a) Preliminary findings of a leachate studyon two landfills in Suffolk County, New York. US Geol Surv J Res3:273–280

Kimmel GE, Braids OC (1980) Leachate plumes in ground water fromBabylon and Islip landfills, Long Island, New York. US Geol SurvProf Pap 1085:38

Kubare M, Mutsvangwa C, Masuku C (2010) Groundwater contamina-tion due to lead (Pb) migrating from Richmond municipal landfillinto Matsheumhlope aquifer: evaluation of a model using fieldobservations. Drink Water Eng Sci Discuss 3:251–269

Lloyd JW (1986) A review of aridity and groundwater. HydrogeologicalProcess 1:63–78

Lloyd JW (1987) The hydrogeological of complex lens conditions inQatar. J Hydrol 89:239–258

Lloyd JW (1990) Groundwater resources development in the easternSahara. J Hydrol 119:71–87

Lloyd JW (1997) The future use of aquifers in water resources manage-ment in arid areas. Arab J Sci Eng 22:33–46

Lloyd JW, Miles JC (1986) An examination of the mechanisms control-ling groundwater gradients in hyper-arid regional sedimentary ba-sins. Water Resour Bull Am Water Res Assoc 22:471–478

Muchingami I, Hlatywayo DJ, Nel JM, Chuma C (2012) Electricalresistivity survey for groundwater investigations and shallow sub-surface evaluation of the basaltic-greenstone formation of the urbanBulawayo aquifer. Phys Chem Earth 50:44–51

Palmquist R, Sendlein LVA (1975) The configuration of contaminationenclaves from refuse disposal sites on floodplains. GroundWater 13:167–181

Rasheeduddin M, Abderrahman MA, Lloyd JW (2001) Management ofgroundwater resources in eastern Saudi Arabia. Water Resour Dev17:18–210

Reyes-Lópeza JA, Ramírez-Hernándeza J, Lázaro-Mancillaa O, Carreón-Diazcontia C, Garridob MM (2008) Assessment of groundwatercontamination by landfill leachate: a case in México. WasteManag 28:S33–S39

Schwartz FW, Zhang H (2003) Fundamentals of groundwater. Wiley,New Jersy

SSG (Scientific Software Group) (2010) RISC WorkBench, softwarepackage for fate and transport modeling and human health riskassessments for contaminated sites. http://www.scisoftware.com/environmental_software/detailed_description.php?products_id=86.Accessed 17 November 2012

Wexler EJ (1988) Groundwater Flow and Solute Transport at a MunicipalLandfill Site on Long Island, New York-Part 1, Hydrogeology andWater Quality, U. S.Geological Survey Water ResourcesInvestigations Report 86-4070, p 53

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