Geo-Hydrological Remediation of Hydrocarbon Contaminated Soil at Johannesburg International Airport Sylvia Raleru Master of Sc

GEO-HYDROLOGICAL REMEDIATION OF HYDROCARBON CONTAMINATED SOIL AT JOHANNESBURG INTERNATIONAL AIRPORT

SYLVIA RALERU

Mini-dissertation submitted in partial fulfilment of the requirements for the degree

MASTER OF SCIENCE

ENVIRONMENTAL MANAGEMENT

IN THE FACULTY OF SCIENCE AT THE

UNIVERSITY OF JOHANNESBURG

Supervisor: Prof J.T. Harmse

JANUARY 2005

Abstract

Title: Geo – hydrological remediation of hydrocarbon contaminated soil at Johannesburg International Airport

The objective of this investigation was to identify and evaluate the appropriate remediation technologies/ methodologies to rehabilitate the hydrocarbon affected zones on the in flight service areas at JNB airport well as to determine the costs associated with implementing such preventive and corrective measures. The following questions were formulated for this investigation, the location of the leak, the duration of the leak, method used to ascertain the pollution, chemical contents of the contaminants, availability of the preventative and proactive measures to prevent the reoccurrence.

• The methodology followed for the assessment included the identification of the source of pollution through soil vapour survey and soil sampling. The fuel hydrant line was also pressure tested. Contoured data were used to perform auger drilling to determine the lateral and vertical extent of pollution. • Identification of receptors such as soil and ground aquifers which may be affected by pollution by establishing any free product in the soil. • Thirty-three monitoring boreholes were drilled during this investigation. Twenty- nine of these holes were drilled to a depth of approximately 10m below surface and four were drilled to 32m below surface. The aim of the deep holes was to investigate the deeper aquifer and the shallow part of theses deep holes were thus cased off. • A risk based investigation was also conducted to determine the risk of contamination to health, safety and the environment. This was quantified by using Risk Based Corrective Action (RBCA, pronounced as Rebecca) framework. RBCA has continued to gain popularity with regulators and environmental professionals within South Africa and abroad.

ii The slug tests and hydrocensus methods/ tests were used during data gathering based on slug tests; these were performed on boreholes in order to determine the hydraulic conductivity of the saturated geological formation. The hydrocensus was used in order to identify possible receptors in the west of the site from the pollution area due to the topography, to establish groundwater quality. The groundwater quality was established so as to have a baseline to work from.

Chemical analysis was also conducted on water and soil samples to determine the presence of BTEXN i.e. Benzene, Toluene, Ethyl-benzene, Xylene and Naphthalene therein. These would also provide information to determine the presence of hydrocarbon products in the same media to establish whether hydrocarbon products were present or not. In the case of an unconfined aquifer, the hydraulic gradient is equal to the slope of the water table, measured at different points in the aquifer. The site topography can normally be used as a first approximation of the water level differences over distance, in other words, as an indication of the hydraulic gradient.

Ground water samples were collected from boreholes/ percussion holes, for the purpose of determining the groundwater quality. Eight pump water samples were collected. However no free phase products were detected in any of the boreholes. The major cation/ anion concentrations were compared with those of SABS defined drinking water standards. On the basis of these analyses, it was clear that groundwater of the surveyed boreholes is of good quality. All inorganic element concentrations are within the SABS drinking water a standard, therefore this groundwater water is fit for human consumption.

Based on the recommended remediation processes, Vacuum Enhanced Recovery (VER) subdivided into SVE and DPE (Dual Phase Extraction or bio-slurping) as well as MNA, may be viable options for hydrocarbon chemicals that are quite mobile in the subsurface environment and not amendable to microbial degradation. SVE and VER are technically suitable/ feasible and cost effective. Technical suitability takes into account things such as site constraints being met i.e. physical properties of contaminants, biodegradability, solubility, hydrogeology, location and power supply from the VER container to the nearest substation. Feasibility concerns increase with increase in innovation.

iii

The VER option is also based on the fact that it is locally based and the country is in a process of uplifting the proudly South African products and expertise. It is purely based on what is best available and practically viable by also taking cost implication into account. The use of African trained and experienced staff ensures that such solutions are locally appropriate and competitively priced.

In conclusion, the investigation had focused on the Best Practicable Environmental Options (BPEO) as well as Best Available Technology Not Exceeding Excessive Costs (BATNEEC). The main purpose of this investigation was to determine various technologies/ methodologies, their effect on controlling and remediation of the affected areas and at the same time being cost effective (Cost-to-benefit-analysis). All the technologies/ methodologies were compared and the one that meets the principles of (BATNEEC & BPEO) without compromising the environment has been recommended for the implementation process.

iv Acknowledgements

I would like to this opportunity to thank the persons below for their contributions and having provided me with guidance, support and information.

• Prof J.T. Harmse; (RAU)-my supervisor, mentor and inspiration; for his inputs, comments, direction, time and undivided attention on the review of my report • Gerhard van der Linde; Hydro-geologist; (Geo Technologies cc); Pretoria; for his assistance in data collection and analysis. Also assisting with identifying and investigating different methodologies which could remediate the contaminated soil of that nature. In addition, for providing information on impact studies conducted previously on petrochemical pollution • Dr Tsinonis ; Managing Director; (Thermopower); Olifantsfontein; for presenting information on thermopower process and legislations pertaining to that. • Theo Ferreira, Director; (Georem International); Johannesburg; for inviting me to the conference on Site Assessment and Remediation for soil and groundwater pollution. Also assisting with identifying and investigating different methodologies which could remediate the contaminated soil of that nature • Dr T. Davis; Liquid Pollution Control Specialists; (Integrated solutions) (Germany) for having demonstrated a modernised Airsparging process • D. Sanders; Business development Director; ( Churngold Remediation) (UK) for sharing most valuable information during the conference on Site Assessment and Remediation for soil and groundwater pollution • C. Sillars; Managing Director; (Churngold Remediation) (UK) for sharing most valuable information during the conference on Site Assessment and Remediation for soil and groundwater pollution • B. Usher; Researcher; (Institute on groundwater studies); UFS; for sharing a case studies of his research on groundwater pollution during the conference on Site Assessment and Remediation for soil and groundwater pollution • P. Aukamp; Environmental Geologist; (Kantey & Templer); Johannesburg/ Cape Town for having showed case studies and the methodology on groundwater assessment • D. Whitfield; Hydro-geologist; (Environmental Drilling and Remediation Services); Sub-Sahara for Africa; for assisting with the information on drilled holes and the positions thereof

Furthermore, I would like to thank the above specialists in their respective fields for their undivided attention and always making time to accommodate me in their busy schedule for the preparation of this investigation report.

v Table of Contents

1. Introduction 1 2. Characteristics and Background of the Study area 3 2.1. Location 3 2.2. Physical Characteristics 5 2.3. National and International Human/ Economic Characteristics 11 3. Problem Statement 15 3.1. Aims/ Objectives 16 3.2. Background and Investigation Methodology 16 3.3. Movement of Hydrocarbons in the Subsurface 24 4. Data Gathering and Analysis and Modelling Process 25 4.1. Data Gathering 25 4.1.1. Slug Tests 25 4.1.2. Hydrocensus Results 26 4.1.3. Chemical Analysis of BTEXN 31 4.2. Data Analysis 35 4.3. Modelling Process 41 4.3.1. GMS Software Model 41 4.3.2. Construction of the Finite Difference Mesh 42 4.3.3. Model Flow 43 5. Review of Available Remediation Technologies 45 5.1. The types of Available Hydrocarbon Remediation Technologies and Cost Implications 46 5.1.1. Physical Remediation Technologies 47 5.1.2. Biological Remediation Technologies 57 5.1.3. Chemical Remediation Technologies 65 5.1.4. Thermal Remediation Technologies 66 6. Syntheses 70 6.1 Conclusion and Recommendations 70 7. List of References 74

vi List of Tables

Table 1: Average weather conditions simplified for 2003 9 Table 2: Annual Traffic Data (2001-2003) for Passengers 14 Table 3: Summary of Slug Test Results 26 Table 4: Summary of Hydrocensus Organic Results 27 Table 5: Change in Static Water Level Depth in Auger Holes between Jan 2000 and December 2001 28 Table 6: Fluctuation of Product Thickness in Auger Holes between January 2001 and December 2001 29 Table 7: Summary of BTEXN concentration in the Sample from AH 8 and AH 10 during January 2001 31 Table 8: Summary of BTEXN concentration in the Sample from AH 1 to AH 8 during March 2001 32 Table 9: Summary of BTEXN concentration in the Sample from MW5 to MW21 during March 2001 32 Table 10: Summary of BTEXN concentration in the Sample from MW23 to MW27 during November 2001 33 Table 11: Summary of all Drilled Monitoring Holes 34 Table 12: Cost Estimate for VER Installation for 2003 @ 6% annual inflation rate 55 Table 13: Cost of Enhanced Bioremediation (MNA) of one Sampling event in 2002 @ 6% annual inflation. 61 Table 14: Costing Model for Phytoremediation 65 Table 15: Contamination Level in another soil pollution study area before Treatment 68 Table 16: Summary of emission test results in relation to standards/ guidelines 69

vii List of Figures

Figure 1: Site Map of Kempton Park shows Drilled Holes at In –Flight Service area 4 Figure 2: Geological Setting of the area 6 Figure 3: Topography of the Study area 8 Figure 4: Fauna – Bird Specie 10 Figure 5: Flora – Vegetation (Grass bales) 11 Figure 6: Position and number of Groundwater Monitoring Boreholes and Auger Holes in the Study area 19 Figure 7: Aerial overview of JNB Airport 20 Figure 8: Flow Diagram of Methodology Conducted 23 Figure 9: Depth of Groundwater in the Transect of Auger Holes 30 Figure 10: Free Product Thickness in MH1 toMH27 monitoring holes from Jan 2001 to December 2001 36 Figure 11: Trends in Depths to Groundwater Data for all Monitoring Holes during the Monitoring Period 37 Figure 12: Trends in Free Product Thickness for all the Monitoring Holes during the Monitoring Period 38 Figure 13: Free Product Thickness in Transect auger Holes 39 Figure 14: Apparent Free Product Thickness in a Well 40 Figure 15: Finite Difference Network of the investigated area 42 Figure 16: Approximate Location of the Plume 43 Figure 17 Modelling Process of Pollution Degradation 44 Figure 18: Airsparging and Monitoring Natural Attenuation 47 Figure 19: Airsparging Process 48 Figure 20: Airsparging Equipment in Process 49 Figure 21: Airsparging Water Analysis conducted before and after the Remediation Process 50 Figure 22: Process Flow Diagram of VER 52 Figure 23: VER System Container 53 Figure 24: Thermopower Treatment Process 66

viii Appendices

Appendix 1: LNAPL components floating on the water table capillary fringe and entering a monitoring well 80

Appendix 2: Processes that occur when hydrocarbons leak from an underground storage tank 81

Appendix 3: Residual oil left behind in the interstices of soil 82

Appendix 4: Soil Vapour Extraction Procedure 83

Appendix 5: Typical pump-and-treat groundwater remediation system using carbon to adsorb hydrocarbons 84

Appendix 6: Soil Vent System 85

Appendix 7: Soil Venting of Stockpiled Soil 86

Appendix 8: Bio-enhanced Soil Aeration 87

Appendix 9: Recovery well in a cut-off trench and optional injection gallery 88

ix Abbreviations used

AH – Auger Hole ARC – Agricultural Research Council BTEXN – Benzene, Toluene, Ethylene, Xylene and Naphthalene CBD – Central Business District DEAT – Department of Environmental Affairs and Tourism DWAF – Department of Water Affairs and Forestry EU EPA – European Union Environmental Protection Agency GPS – Global Positioning System GRO – Gasoline range organic HC - Hydrocarbons HPH – Hydrocensus percussion hole JNB – Johannesburg International Airport K/O 1 – Knockout 1 LNAPL – Light Non-Aqueous Phase Liquids DNAPL – Dense Non-Aqueous Phase Liquids MH – Monitoring holes MNA – Monitored natural attenuation M- Metres nd – Not detected PH – Percussion Hole RBCA (Rebecca) – Risk based corrective action SVE – Soil vapour extraction SVS – Soil vapour sample US EPA – United Sates Environmental Protection Agency VER – Vacuum enhanced recovery VOC – Volatile organic compound

x Glossary of terms used

Apron – An area on the airport airside where aircraft park and serve as a movement area for ground support equipment and vehicles

Adsorbed phase – chemical bound into surface or body of soils/ media

Dissolved phase – chemical dissolved in groundwater in saturated areas of subsurface

Exudates – release of soluble organic matter from the roots of plants to enhance availability of nutrients or as a by-product of fine root degradation

Fauna –Animal Species

Flora – Plant Species

Free phase – (plume/ hydrocarbon in liquid phase) Light Non-Aqueous Phase Liquids (LNAPL’s) are chemicals less dense than water and will float on top of the water table; and Dense Non-aqueous Phase Liquids (DNAPL) are more dense than water and will sink through the water in the saturated zone until a barrier is reached, such as an impermeable layer and this acts as primary source LNAPL

Hot-spots – A areas of great concern, based on the fact that there is a high presence of hydrocarbon substances in the zone

Lignification – the synthesis of lignin and woody tissue of plants which may incorporate chemical contaminants and immobilize them from the environment

Plume – Ground pockets which result in collection of hydrocarbon substances (fuel) into one area which is deeper in relation to the rest of the surrounding site.

xi Phytoextraction – the use of plants to accumulates metals into harvestable, above- ground portion of the plant and, thus, to decontaminate the soils

Phytostabilization – the use of plants to immobilize contaminants in situ by decreasing soil erosion and curtailing vertical migration of contaminants to groundwater by transpiration (hydraulic control)

Phytotransformation – the uptake and transformation (metabolism) or volatilization of organic chemical contaminants by plants as an in situ treatment technology

Product thickness – The thickness layer of the chemical/ hydrocarbon floating on top of the watertable

Radioactive forcing – Spontaneous disintegration of atomic nuclei with the emission of usual penetrating particles

Rhizofiltration – the use of plant roots and rhizosphere to sorb, concentrate, transform, and precipitate organic and metal contaminants from surface water, groundwater, or wastewater

Rhizosphere – the soil profile in close contact with roots of plants, usually taken to the soil within 1 mm of roots and fine roots.

Rhizosphere bioremediation – the microbial transformation of organic contaminants by bacteria, fungi, and protozoan within the biologically-rich zone of the immediate vicinity around plant roots

Vapour Phase – volatile chemical released/ trapped in unsaturated areas in the subsurface

xii Chapter 1: Introduction

In South Africa, environmental management is often regarded as being focused on the prevention rather than the correction of environmental pollution. This approach was reflected in the old Environment Conservation Act 73 of 1989, where much attention was given to new activities that may impact on the environment. This changes were brought by the National Environmental Management Act 107 of 1998 (NEMA, 1998a) and National Water Act 36 of 1998 (NWA, 1998b). These Acts require owners of properties to ensure that they take reasonable measures to assess and prevent pollution and also to correct environmental degradation.

This applies not only to the person responsible for the pollution, but also persons in control of land or premises on which a situation exists, which has caused, or has the potential to cause significant pollution or environmental degradation. Through a number of legal actions and landmark cases, government and civil society are becoming more aware of the environmental impact of polluted soil and groundwater (Ferreira, 2004).

Human beings understand that their diverse activities have or can have a significant impact on the environment, therefore every human understands that his/ her health and longevity depend on their concern attitude towards nature. We rely entirely on the environment for our survival. However, attempting to make our lives better we have a great impact to the soil, water and air. Thus soil pollution and water contamination are serious problems today.

Soil is one of the most important natural resources we have, because it plays a central role in food production and in the major biogeochemical cycles. It forms the main interface between atmosphere, hydrosphere, lithosphere and biosphere, so that any changes in any of these environmental systems are likely to have knick-on effects on soil and soil development. The stability and future of many soils is under threat from a wide variety of human activities which degrade soils and alter its structure, fertility and usefulness. These include pollution, i.e. fallout of air pollutants such as acid rain, deposition of water pollutants, particularly in times of flood, leaching of material from

1 waste dumps and sanitary landfill sites, and contamination with toxic heavy metals and other pollutants from local industries (Park, 2001).

When soil or water is affected by hydrocarbon substances, it loses its quality of use. Soil degradation results due to the fact that the soil structure, soil composition and its use is degraded to a lesser useful medium. The contamination sometimes causes some clogging in the soil due to the viscosity of the pollution substance. Therefore, the soil is rendered useless unless it gets remediated physically, biologically or mechanically (Keller et al., 1997). The movement of groundwater, be it in the form of a floating lense or a sinking plume, will be affected by discontinuities in the stratigraphy. Although such discontinuities can greatly complicate remediation design, ignorance of their presence in much worse than not knowing that they exist (Eslinger et al., 1994).

In 2000/1, a geo-hydrologist consultant was appointed to undertake the environmental impact assessment at the JNB airport pertaining to the fuel hydrant line facilities. This assessment was conducted based on the suspected ground contamination which was brought up by the fact that no fuel hydrant line was subject to an EIA before and it was also suspected that there were some emissions being released along the apron area. Firstly it is imperative to explain the background and give an understanding of what the airport or rather aviation industries particularly, consist of.

Aviation industries comprise of tenants, operators, concessionaires and contractors rendering diverse services. Extended infrastructures are provided by the airport authorities to accommodate different business sectors to operate together in delivering world class services. Such infrastructures include: terminal buildings, runways, taxiways, aprons, parking stands, car parking facilities, office accommodation, fire stations, retail facilities, property listed areas as well as property development areas. However this study will concentrate on the apron facilities which include fuel hydrant lines that supply fuel from underground pits into the aircraft wings. The following chapter will address the characteristics and the background information of the study area.

2 Chapter 2: Characteristics and background of the study area

2.1 Location

The study area is situated towards the north western side of the JNB airport (Figure 1). The topography dips gently to the northwest and southwest from where the source of pollution was discovered. The source is approximately 80-100 away from where the contamination-plume was discovered (Van der Linde, 2002).

The airport elevation is 1 679m above mean sea level. The location of the airport is: latitude; 26º08'02" N and longitude; 28º14'34" E. The JNB airport area covers 1 600ha (JIA Statistics, 2003). The distance from major centres i.e. JNB airport to Johannesburg CBD is approximately 30km, Pretoria is 40 km and Sandton is 35 km away. The distance from heavy and light industrial areas i.e. Isando & Spartan is approximately 5-10km away respectively. It is indicted that the route network entering and leaving the JNB airport is one of the most complex and highly sophisticated road network systems in Africa (Figure 1). The major access routes are the R21 from Pretoria to Boksburg and R24 from Johannesburg to and from the airport (JIA Statistics, 2003).

Figure 1: Site Map showing the airport in relation to Kempton Park (Geo-Science, Pretoria)

4 The circled area on Figure 1 represents the area where the free product plume is situated. The green lines indicates the interlinking route network system adjoining the airport from Pretoria to Boksburg i.e. R21, Johannesburg i.e. R24 freeways. The redlines showing a network system on the left side of the airport indicated the streets lines in the Rhodesfield residential area and the far left is Spartan and Isando Industrial areas. The black and white staggered lines indicates railway lines The whole infrastructure on the right is the JHB airport precinct, indicating the 4 aprons, i.e. Alpha, Bravo, Charlie and Delta aprons/ parking stands.

2.2 Physical Characteristics

2.2.1 Geological Setup

The site is underlain (Figure 2) by shale and mudstone of the Vryheid Formation, which forms part of the Karoo Super Group. The Karoo Super Group is underlain by lava of the Klipriviersberg Group of the Ventersdorp Super Group.

A short summary of the typical soil profiles developed in situ on the lava and the shale is given below. This soil summary only concentrated on the area affected next to the in-flight services area and the apron identified on figure 2 (Van der Linde, 2002).

Figure 2: Geological Setting of the Area (Geo-Science, Pretoria)

Symbols on Figure 2

Pv – Vryheid Formation Rk – Klipriviersberg Formation (Venterdorp Supergroup) Rvp – Platberg Group (Venterdorp Supergroup) Zh – Halfway House Granites C-Pd – Dwyka Formation (Ecca Group) The circled area is where the contamination of free product is situated.

6 Typical soil profile and regolith developed on lava of the Kliprivier Group (Figure 2)

0,0-2,0m Slightly moist, dark red brown, clayey sand with abundant course, medium and fine grained ferricrete nodules; colluviums 2,0-4,0m Moist, dark red brown clayey sand to sandy clay with occasional medium and fine grained ferricrete nodules: residual lava 4,0-6,0m Moist, dark yellow brown clayey silt; residual lava 6,0-9,0m Moist, yellow brown silt; residual lava 9,0-10,0m: Slightly moist, yellow brown silt; residual lava

Typical soil profile and regolith developed on shale of the Vryheid Formation (Figure 2)

0,0-1,0m Slightly moist, dark brown, clayey sand with abundant course, medium and fine grained ferricrete nodules; colluviums 1,0-2,0m Slightly moist, pale red brown becoming pale yellow brown with depth, slightly sandy clay; residual shale 2,0-5,0m Slightly moist, pale red brown clay; residual shale 5,0-6,0m Moist, pale red brown lay; residual shale 6,0-10,0m Saturated, red brown clay; highly weathered shale

2.2.2 Relief (topography)

The topography dips (figure 3) gently to the northwest from the eastern side of the contaminated area at the in-flight services. The polluted area under investigation forms a wide, open valley from the north east to the south western side of the main apron area (Van der Linde, 2002).

Figure 3: Topography of the study area (Geo-Science, Pretoria)

The circle area indicated the plume area where the free product is situated. The flow takes place along the bedding planes of different geological layers, as a continuous pollution emanating from the contaminated soil in the close vicinity of the polluted source with a slow lateral velocity. Rainwater falling onto the contaminated soil can infiltrate the subsurface and dissolve some of the soluble compounds of the jet fuel into solution. The direction of groundwater flow can mimic the overall surface topography and the flow in a down slope direction towards low-lying watercourses (Van der Linde, 2002).

8 2.2.3 Temperature and Precipitation

The temperature and precipitation around the airport is influenced by various factors such as the type of vegetation and the site layout. When an airport site is identified, the area selected is based on a flat-terrain well removed from residential areas as well as waste disposal sites. However with development, there will always be urban encroachment towards the airport. In many instances, the land zoning matters are not dealt with appropriately to ensure that such urban encroachment are discouraged and prevented before taking place. A wind sock and a weather monitoring station are located on the south east and north west side of the airport. The Weather Data are collected on a daily basis to provide information to the pilots so as to ensure that there is safe landing and correct take off of aircrafts on either on the two runways.

Table 1 indicates that there is high runoff volume at the airport due to high precipitation during the hot summer season.

Table 1: Average weather conditions simplified for 2003 (JIA Statistics, 2003)

Months Mean maximum Mean minimum Mean temperature (ºC) temperature (ºC) precipitation (mm) January 25.6 14.7 125 February 25.1 14.1 90 March 24 13.1 91 April 21.1 10.3 54 May 18.9 7.2 13 June 16 4.1 9 July 16.7 4.1 4 August 19.4 6.2 6 September 22.8 9.3 27 October 23.8 11.2 72 November 24.2 12.7 117 December 25.2 13.9 105

9 2.2.4 Fauna and Flora

The predominant vegetation at this airport is Port Jackson (Acacia Saligna), blue gum trees i.e. (Myrtaceae and Genus Eucalyptus) and weeds. There are also some bird species such as Helmeted Guineafowl (Numida Meleagris), Hadeda Ibis (Botrychia Hagedash), Crowned Plover (Vanellus Coronatus) and Greyheaded Gulls (Larus Cirrocephalus) which are regarded a safety risk to the aviation industry. Helmeted Guineafowl were of particular concern during 2003 with large flocks often crossing the main runway i.e. O3R 21L, during the winter season (Froneman, 2002).

There are programmes in place which address bird presence at the airport. These are international practices e.g. scaring of birds using Border Collie dogs. These are specially trained to scare birds away from runways and taxiways so as to safeguard the lives of the passengers onboard the aircraft. This method is considered as nature conservation programme since no shooting or killing of birds is condoned. Trapping and removal of guinea fowl is conducted, and these are handed over to the Endangered Wildlife Trust as well as to farmers in Benoni area (Froneman, 2002).

Botrychia Hagedash Numida Meleagris Vanellus Coronatus Larus Cirrocephalus

Figure 4: Fauna - Bird Species (MacLean, 1993)

The species switch is a programme implemented to inhibit the excessive growth of grass at the airport and encourage the resurface of a “kweek” grass which does not grow longer than 150 mm. Long grasses provides a habitat for bird species which causes a safety risk to the aircraft. This programme assist in reducing costs associated with conventional mowing and other issues incurred in grass maintenance methods and logistical difficulties (Froneman, 2002). These issues are:

10 Risk of dust and other debris transferred to runway and in-bound aircraft Attraction of unwelcome bird life feeding on insects, millipedes, moths and maggots behind a mowing machine Fire risk associated with the storage and disposal of compressed grass cuttings (grass bales).

Figure 5: Flora -Vegetation (harvested grass bales from the airfield area)

Weed control or vegetation management aims at inhibiting, accelerating or retarding the process of plant succession so that the most desirable plant communities are established to meet the requirement of the situation i.e. kweek grass (Froneman, 2002). It is important that continuity in application of specie switch over the entire period is established in order to afford the best possible opportunity of success in the shortest possible period. Currently, only two registered products i.e. Outspace Super and Double Edge are registered with Department of Agriculture for use in the species switch process. Commercially these products are known as Outspace Super (Reg No: L4769) and Double Edge (Reg No: L5824) (Conservation of Agricultural Resources Act 43 of 1983)

2.3 National and international human/ economic characteristics

The JNB is the largest airport in Africa and serves as an international gateway/ hub into the rest of the world including the African continent. The airport is situated near the major metropolitan area of Johannesburg CBD to serve the country’s aviation requirements (JIA Statistics, 2003).

11 2.3.1 Importance and impacts of the aviation industry

Air transport brings substantial social and economic benefits and underpins the global economy, but it also has a local and global impact on the environment. The aviation industry has grown rapidly and has become an integral and vital part of modern society (Meredith, 2003). Future projections suggest that demand for air travel will continue to rise, in line with the growth in the world economy. Aviation is by necessity an efficient industry. Efficiency is an essential first step on the road to sustainability and this is the key to minimising aviation’s environmental impact (Meredith, 2003). Some of the environmental impacts are as follows: a) Energy consumption Aviation consumes about 12% of the oil supplies used by the entire transport industry (Meredith, 2003). b) Climate change Aviation industry contributes about 3,5% of the total radioactive particles forcing climate change by all human activities (Meredith, 2003). c) Fuel efficiency Airlines have doubled their fuel efficiency over the past 30 years. Further improvements in efficiency are expected to reduce emissions growth to around 3% a year compared to forecast of 5% growth in traffic (Meredith, 2003). d) Emissions The clean technology of modern aircraft engines has almost eliminated emissions of carbon monoxide (CO) and hydrocarbons (CHC) (Meredith, 2003). e) Noise Aircraft entering the fleet today are typically quieter than comparable aircraft of 30 years ago, which in practice corresponds to a reduction in noise pollution (Meredith, 2003).

12 For nearly five decades, air transport has provided significant public benefits. It has brought work, prosperity, increased trade and new travel and tourism opportunities. Air transport is one of the fastest growing industries in the world and by 2010 will be responsible for 33 million jobs and an annual gross output of US$1800 billion. Despite these benefits, the only land area that air transports use is the land occupied by airports themselves. Proper management of the environmental impact on this land is important if air transport is to protect its future development (Meredith, 2003).

2.3.2 Air Traffic Movement (ATM’s) and Passenger Movement

The JNB airport operates for 24 hours 7 days a week. An equivalent of one in four persons or 25% of the world’s population travels by air each year, and at least one third of the world’s manufactured exports is shipped by air. Worldwide demand for air service will double before 2010 (Meredith, 2003).

Table 2 indicates a significant growth in passengers to South Africa between 2001 and 2003. There were more domestic departures/ arrivals as compared to the regional ones i.e. to the neighbouring countries of Botswana, Mozambique, Zimbabwe, Swaziland, Lesotho and Namibia. South Africa has been the most preferred destination since the 9/11 World Trade Centre incident. People want to go on a holiday or go tour a place which is tranquil and safe. The total passenger numbers in 2002/3 has almost doubled compared to that in 2001/2.

13 Traffic Data (2001-2003) for JNB Airport Table 2: Annual Traffic: Passenger Apr 2001-Mar 2002 Apr 2002-Mar 2003 Domestic Arrival 134 514 425 131 Departure 251 123 242 335 Total 385 637 667 466 Arrival 127 340 139 407 Regional Departure 123 113 145 121 Total 250 453 534 981 Arrival 1 011 321 1 311 252 International Departure 1 014 231 1 213 234 Total 2 025 552 4 550 038 Arrival 1 132 151 1 250 481 International & Departure 1 122 221 1 358 325 Regional Total 2 254 372 2 608 806 Total Passenger 4 916 014 7 361 271 (JIA Statistics, 2003)

The characteristics and background information of the study area was provided to give an understanding of where is the airport situated in relation to the nearest town or city within a specific municipal boundary. The background information also assists in understanding what other environmental activities might have contributed or can be attributed to the problem in the study area. The next chapter will deal with the problem statement, which will address some of the following questions i.e. what happened; how long has the leak been there i.e. pollution duration; what is the suspected cause of the leak; which method or tools were used to ascertain the pollution; what substances were identified as being contained in the pollution; what are preventive or remedial measures that can curb the problem from reoccurring.

14 Chapter 3: Problem Statement

The objective of this investigation is to identify and evaluate the appropriate remediation technologies/ methodologies to rehabilitate the hydrocarbon affected zones on the in flight service areas at JNB airport as well as to determine the costs associated with implementing such preventive and corrective measures. Furthermore, the following questions were formulated to give the background understanding of the origin of the pollution:

¾ How the leak was first detected? ¾ Where the leak was identified i.e. source of pollution? ¾ How long has the leak been there i.e. pollution duration? ¾ What is the suspected cause of the leak? ¾ Which method or tools were used to ascertain the pollution? ¾ What substances were identified as being contained in the pollution? ¾ What are preventive or remedial measures that can curb the problem from reoccurring? ¾ What are proactive measures to ensure that no similar incident re-occurs again?

In the study area, hydrocarbon contamination was caused by the spillage from the fuel hydrant line connecting the refuelling pipe to the aircraft wings. A fuel hydrant line is a pipe with a diameter of about 90-95cm. Strong jet fuel odours were noted in stormwater manholes at the in-flight service car park by employees and reported to management. An inspection of the drain revealed the presence of jet fuel. The area assessed was initially confined to the storage areas and to the car park south of the freight terminal and later extended to Delta apron (Figure 1, 2 & 3). An Ecoprobe 5 gas analyzer was located at the affected areas and was used to measure the concentration of vapours. The samples were extracted with the aid of a 2m probe to ensure that any vapours trapped in the base of the drains were measured. (Aukamp, 2003)

15 The fuel hydrant line had a leak which was due to wear and tear as a result of corrosion on the underground piping system over the years. It is of the utmost importance to ensure that once a leak such as this one has been identified, it must be dealt with as soon as possible to prevent further contamination and possible migration of the pollution plume to non-affected areas, reason being that the underground aquifers can be severely affected by the hydrocarbon substances presence in the subsurface. Hydrocarbons prevent the free flow of water during rainy season to underground areas and cause some clogging due the viscosity of the hydrocarbon material. (Aukamp, 2004)

Simultaneously, the best available technologies or methodologies must be selected and recommended to solve the situation at hand. These technologies/ methodologies are to be chosen based the Best Available Technologies Not Entailing Excessive Costs (BATNEEC) and Best Practicable Environmental Options (BPEO) concepts without compromising the integrity and values of the Airports Authority in anyway. It is purely based on what is best available and practically viable by also taking cost implication into account.

3.1 Aim/ Objectives

The following are the objectives pertaining to the problem statement: • To determine the environmental risks associated with this hydrocarbon pollution • To recommend or propose appropriate remediation methods taking into account the cost to benefit analysis.

3.2 Background and Investigation Methodology

The purpose of this study was firstly to determine the pollution level in the soil and groundwater in the affected in-flight services areas. Secondly, to determine the extent of the pollution in the soil as well as the risks associated with such pollution. Thirdly and most importantly was to recommend a remediation methodology that is cost effective. The first scope of the study was undertaken, for the purpose of gathering the following information: (Van der Linde, 2002).

16 A soil vapour survey was conducted along the length of the fuel hydrant line on the apron which is used for refuelling wide-bodied aircrafts. The soil vapour survey is a direct method that is used to delineate the lateral extent of a hydrocarbon pollution plume. Since the pollutant exhibits a volatile character, it is possible to measure this vaporised fraction when soil vapours are polluted. Detection of the pollutants takes place by extracting soil gas from the unsaturated zone and analysing it on site. The analysis characterises the nature of any volatile organic compound (VOC) found in the soil gas and assists in the effective placement of monitoring positions (Burris et al., 1988).

The objectives of a soil vapour survey are: • The identification of possible unsaturated zone source areas of VOC’s thus areas of historical leakages. • To aid in the optimal placing of monitoring holes. (Aukamp, 2003)

The extraction and analysis of soil vapour from the water unsaturated soil zone is termed a soil vapour study. Extracted vapours can be either from HC located above or below the water table, or both. Often, soil vapour study is done preliminary for the installation of monitoring wells, i.e. the results of the soil vapour study guides the location of monitoring wells. Soil vapour monitoring is done by pushing, pounding, or augering a hollow metal rod onto the ground. The rods come in sections so that once the first segment is installed, a second can be screwed to the top of the first, and then it continues (Eslinger et al., 1994). Once the rods are at the desired depth, a measuring or collection device is connected to the top of the uppermost rods. Measurements can be made directly in the field with a photoionization (Eslinger et al., 1994).

This technique is an indirect method and determines the presence of high VOC vapour concentrations in the unsaturated soil zone. The position of highest VOC vapours is an indication of hydrocarbon accumulation and can be interpreted as the position of a possible leak. Furthermore, it should be noted that the soil conditions could have an effect on the SVS results:

17 • Contour soil vapour datum was used in the application of auger/ percussion drilling to determine the extent of the pollution. The holes were appropriately equipped to serve as future monitoring holes. • A hydrocensus was undertaken for the purpose of identifying and locating all boreholes and water points within one kilometre radius. Current groundwater use and potential future usage was identified. • Water levels were measured in the boreholes and recorded using a GPS. Water samples were taken from eight of the identified holes and submitted to a laboratory for hydrocarbon, cation and anion analyses. • Coordinates of all the holes drilled during the investigation were surveyed (Van der Linde, 2002).

In terms of surface water, biotic condition were found to exist in the Swartspruit which is situated at about 3-4 kilometres away from the source. Although the pollution has undoubtedly contributed to the reduced water quality, it must be noted that other human activities are similarly impacting on the Swartspruit via a storm water drainage system from Kempton Park town, Isando and Spartan industrial areas, as well as the residential areas in and around Kempton Park from the South East and South West (Van der Linde, 2002). No dissolved phase hydrocarbons were recorded in the surface water. Two soil samples collected in close proximity to the Swartspruit were found to be polluted with hydrocarbons at a depth of approximately 0.3m below surface (Van der Linde, 2002).

The methodology (Figure 8) was chosen and conducted based on the type of pollution and the degree of pollution which was suspected of being contained underground. The rise in watertable which had a direct influence on the free product increasing and reaching the water aquifers and ensuring easier detection was also used. A series of environmental impact assessment of water, soil, slug test and hydrocensus sample were conducted to establish the extent of the vertical and lateral hydrocarbon contamination.

• The methodology followed for the environmental impact assessment included the identification of the source of pollution through soil vapour survey and soil sampling.

18 The fuel hydrant line was also pressure tested. Contoured data were used to perform auger drilling to determine the lateral and vertical extent of pollution. • Identification of receptors such as soil and ground aquifers which may be affected by pollution by establishing any free product in the soil. • Thirty-three monitoring boreholes were drilled during this investigation (Figure 6) Twenty- nine of these holes were drilled to a depth of approximately 10m below surface and four were drilled to 32m below surface. The aim of the deep holes was to investigate the deeper aquifer and the shallow part of theses deep holes were thus cased off.

Figure 6: Positions and number of groundwater monitoring boreholes and auger holes in the study area

19 Figure 7: Aerial overview of JNB Airport

20 The yellow boreholes on figure 6 represent the auger holes and the blue colour represents the percussions boreholes. The red circle area indicates were the plume is situated. Figure 6 relates to the data depicted in Table 11, and it indicates all of the thirty three holes which were drilled on the apron. These holes include both auger and percussion monitoring holes of the study area i.e. the in-flight service area at JNB airport. There is some kind of a conglomeration of monitoring holes on the eastern side of the in-flight services.

Firstly these holes were drilled so close to one another to ensure that no hotspots were missed in between them during the determination of the lateral and vertical extent of the hydrocarbon contamination. Secondly, this was done to be as close to the source as possible i.e. where the odours were detected. Therefore, since the leak was from a fuel hydrant line, the concentration and conglomeration of the monitoring had to be identified and drilled as such.

The execution of the drilling program had the following as its goals: (Van der Linde, 2002). ¾ To obtain exact geological information ¾ To verify the soil vapour results ¾ To establish the following geohydrological information: i. Aquifer characteristics ii. Ground quality information iii. Water level information

¾ To refine the conceptual geological/ geohydrological model in terms of preferred pathways and the associated risks ¾ For future monitoring purpose (Whitfield, 2002).

21 • A risk based investigation was also conducted to determine the risk of contamination to health, safety and the environment. This was quantified by using Risk Based Corrective Action (RBCA, pronounced as Rebecca) framework. RBCA has continued to gain popularity with regulators and environmental professionals within South Africa and abroad (Van der Linde, 2002).

The RBCA process represents a streamlined approach for the assessment and response to subsurface contamination associated with hydrocarbon. It integrates the risk assessment practises with traditional site investigation and remedy selection activities in order to determine cost-effective measures for the protection of the environmental resources (Van der Linde, 2002).

22 Pollution Source: hydrocarbon contamination

SVS & soil sampling conducted

Pressure test conducted on fuel hydrant line

Auger drilling done on lateral & vertical extent of pollution

Identification of pollution receptors to identify the free product

33 Monitoring holes are drilled

4 drilled to 32 m below surface (to 29 drilled to 10 m below surface investigate deeper aquifer & the shallow part cased off)

RBCA conducted to determine risk based on

safety, health & environmental effects

Identification of Jet A1 leak along the fuel hydrant line

Figure 8: Flow diagram of the methodology conducted

23 After several investigations, it was concluded that the source of the pollution was a leak from a fuel line which was suspected to have been occurring over a period of 15-20 years. This indicated to Airports Authority that the leak was an inherent risk from the previous regime which was to be accepted and rectified (Van der Linde, 2002).

3.3 Movement of Hydrocarbons in the subsurface

HC will be carried to the watertable with percolating meteoric waters. However, some of the HC may migrate upward due to capillary action. Also all of the HC will not move away from the immediate surroundings because the soils will have a residual HC saturation, which is the amount stuck to the soil matrix. This means that even if the soil is flushed via saturating waters, some of the HC will remain within the matrix (Eslinger et al., 1994). (Appendix 2 and Appendix 3)

LNAPL’s (Light Non-Aqueous Phase Liquid) will generally move in the direction of groundwater movement. The interface between the LNAPL layers with the watertable will not be a smooth surface because the water table surface in the absence of LNAPL is not a smooth surface. When a monitoring well casing is installed into the zone of saturation, the water inside the casing no longer is in contact with matrix grains, so there are no capillary forces to pull the water up the side of mineral grains (Eslinger et al., 1994).

The following chapter will address issues on the information or data was gathered and analysed. Data gathering and analysis was conducted to determine the presence and concentration of the free phase products in the groundwater and boreholes. At the same time, this would give an indication as to where the hotspots were and to find reason why there were high concentrations of the free product in one area as opposed to other areas. The modelling process on the other hand addresses the migration path of the plume, the volume and direction it is possible to follow in case no remediation process takes place.

24 Chapter 4: Data gathering, analysis and modelling process

4.1 Data Gathering:

The slug tests and hydrocensus methods employed in this study are presented below. These methods and tests were used during data gathering based on slug tests; these were performed on selected holes in order to determine the hydraulic conductivity of the saturated geological formation. The hydrocensus was used in order to identify possible receptors in the west of the site from the pollution area due to the topography, to establish groundwater quality. The groundwater quality was established so as to have a baseline to work from (Van der Linde, 2002).

4.1.1 Slug Tests

Slug tests (Table 3) were performed on selected boreholes in order to determine the hydraulic conductivity of the saturated geological formation. In a slug test, a slug (pipe, closed at both ends) is added to or removed from the borehole after which the rate of recovery of the water level to its static position is measured (Marks & Singh, 1990). From these measurements, the aquifers hydraulic conductivity can be calculated. The results of these tests show that it is evident that the conductivity of the saturated zone varies between 1,75m - 8,98m/day. This emphasises the heterogeneity of the aquifer system (Van der Linde, 2002).

25 Table 3: Summary of Slug test results (Figure 6 for boreholes positions) Borehole Number Saturated hydraulic conductivity (m/day) AH 1 2.87 x 10 AH 2 3.75 x 10 AH 3 8.98 x 10 AH 4 1.75 x 10 AH 5 6.37 x 10 AH 6 3.41 x 10 AH 7 6. 97 x 10 AH 8 1.82 x 10

In the case of an unconfined aquifer, the hydraulic gradient is equal to the slope of the water table, measured at different points in the aquifer. The site topography can normally be used as a first approximation of the water level differences over distance, in other words, as an indication of the hydraulic gradient (Van der Linde, 2002).

4.1.2 Hydrocensus Results

In order to identify possible receptors of the soil and ground aquifers at the area northwest of the airport as well as to establish groundwater potential and quality, a hydrocensus was conducted. In addition, the hydrocensus was conducted to establish background water quality to have a baseline to work from (Marks & Singh, 1990). Ground water samples were collected from the percussion and auger boreholes for the purpose of determining the groundwater quality. The groundwater may potentially be contaminated due to the hydrocarbon pollution. Eight pump water samples were collected. However no free phase products were detected in any of the boreholes (Van der Linde, 2002).

26 Table 4: Summary of hydrocensus organic results Sample date 20 Nov 2001 Sample no: MO1 MO2 MO3 MO4 Benzene 0.0 0.0 0.0 0.0 Tame 0.0 0.0 0.0 0.0 Toluene 0.0 0.0 0.0 0.0 Ethyl benzene 0.0 0.0 0.0 0.0 Mixed Xylene 0.0 0.0 0.0 0.0 Naphthalene 0.0 0.0 0.0 0.0 Total hydrocarbons 0.0 0.0 0.0 0.0 Sample date 20 Nov 2001 Sample no: MO5 MO 6 MO7 MO8 Benzene 0.0 0.0 0.0 0.0 Tame 0.0 0.0 0.0 0.0 Toluene 0.0 0.0 0.0 0.0 Ethyl benzene 0.0 0.0 0.0 0.0 Mixed Xylene 0.0 0.0 0.0 0.0 Naphthalene 0.0 0.0 0.0 0.0 Total hydrocarbons 0.0 0.0 0.0 0.0 All concentration values in mg/l (0.0mg/l represents below detection limit)

The major cation/ anion concentrations (MO1 to MO8) were compared with those of SABS defined drinking water standards. On the basis of these analyses, it is clear that groundwater of the surveyed boreholes is of good quality. All inorganic element concentrations are within the SABS drinking water a standard, therefore this groundwater water is fit for human consumption (Van der Linde, 2002).

All water samples were submitted to the Independent Laboratory of Dr van Rossum in Pretoria for the analysis of Benzene, Toluene, Ethyl benzene, Xylene and Naphthalene. Two water samples were submitted to the Agricultural Research Council (ARC) laboratory for inorganic element (major cation/ anion) analysis. It is normal practice to evaluate the cation/ anion results in terms of consumable water standard. The hydrocarbon pollution could not be seen impacting negatively onto the watercourse and underground water aquifers (Van der Linde, 2002).

27 Table 5: Change in static water level depth in auger holes between Jan 2000 and Dec 2001 DEPTH OF WATER TABLE in (m) Jan-00 Mar-00 May-00 July-00 Sept-00 Nov-00 AH 5 6.32 5.57 5.86 6.32 7.07 6.01 AH 6 5.75 5.19 6.04 6.16 6.25 6.14 AH 7 6.25 5.19 5.70 6.32 6.31 6.12 AH 8 6.14 5.66 4.91 6.87 7.07 7.03 AH 10 4.09 4.13 5.19 4.33 4.40 5.64 AH 11 4.07 4.09 4.17 4.40 4.47 4.69 AH 12 4.28 4.30 4.30 4.44 5.54 4.78 AH 13 4.39 4.42 4.33 4.58 5.69 4.96 AH 14 4.4.1 4.64 4.42 4.51 5.22 4.85 AH 15 4.48 4.46 4.52 5.02 5.15 5.48 Feb-01 Apr-01 June-01 Aug-01 Oct-01 Dec-01 AH 5 6.56 7.96 7.42 8.38 7.05 6.57 AH 6 7.22 7.17 7.30 7.28 7.17 5.99 AH 7 7.04 7.71 7.48 7.19 6.04 6.25 AH 8 7.48 7.73 7.57 7.63 5.89 5.85 AH 10 5.87 5.11 6.10 5.10 4.67 4.50 AH 11 4.90 5.10 5.17 5.08 4.75 4.68 AH 12 4.98 5.24 5.27 5.15 4.96 4.81 AH 13 nd nd nd nd 4.97 4.90 AH 14 5.13 5.66 5.41 5.19 4.94 5.00 AH 15 5.18 5.71 5.63 5.31 5.05 5.07

From Table 5 and figure 9, water extraction from the auger holes started to increase due to the fact that when the extraction process is enhanced in one area, other aquifers supply water to the diminishing borehole. A large volume of water is then experienced in the areas which were not identified as being hotspots.

28 Table 6: Fluctuation of product thickness in auger holes between January 2000 and December 2001 PRODUCT THICKNESS Jan-00 Mar-00 May-00 July-00 Sept-00 Nov-00 AH 5 1.06 0.01 0.29 0.72 1.39 0.23 AH 6 0.78 0.01 0.93 0.96 0.93 0.61 AH 7 1.39 0.01 0.58 1.06 0.96 0.57 AH 8 1.37 0.01 0 1.86 1.96 1.66 AH 10 0 0 0 0 0 0 AH 11 0 0 0 0 0 0 AH 12 0 0 0 0 0 0 AH 13 0 0 0 0 0 0 AH 14 0 0.23 0.01 0 0 0 AH 15 0 0 0 0.44 0.52 0.56 Feb-01 Apr-01 June-01 Aug-01 Oct-01 Dec-01 AH 5 1.12 1.55 1.05 1.96 0.82 0.46 AH 6 0.76 0.93 1.05 1 0.02 0.01 AH 7 1.14 1.49 1.25 0.96 0.3 0.53 AH 8 1.8 1.7 1.52 1.55 0.73 0.4 AH 10 0 0 0 0 0 0 AH 11 0 0 0 0 0 0 AH 12 0 0 0 0 0 0 AH 13 0 0 0 0 0 0 AH 14 0.03 0.3 0 0.09 0.1 0.12 AH 15 0.06 0.31 0.26 0.16 0.15 0.15

The thickness of the hydrocarbon on top of the water table decrease when there is water extraction from the holes. Water is removed simultaneously with the HC from underground aquifers. Therefore the LNAPL floating on top of the water is removed (Appendix 1)

Figure 9: Depth of groundwater in the transect of auger holes

30 From Figure 9 a general decrease in product thickness is still evident in auger holes AH5, AH6, AH7 and AH8. Data depicted here are a direct mirror of what is taking place when the thickness of the product decreases as a result of the water extraction (Van der Linde, 2002). There was however another increase between November 2000 and Jan 2001 in auger hole number AH10 up to AH15 due to high volumes of rainfall during that summer season.

4.1.3 Chemical Analysis of BTEXN

Two water samples were obtained from auger holes AH8 & AH10 and the chemical analytical results are listed in Table 7.

Table 7: Summary of BTEXN concentration in the sample of AH8 & AH10, in January 2001

Constituents AH 8 AH 10 Benzene nd nd Toluene nd nd Ethanol nd nd Ethyl benzene nd nd Mixed Xylene nd nd Naphthalene 1.01 nd Tame nd nd Other GRO 6.44 nd GRO = Gasoline range organics Nd = Not detected

From Table 7, the two chemical water samples only indicated the presence of Naphthalene and Gasoline Range Organics in AH8. In AH10 no BTEXN were detected in January 2001 which was indication that the water extraction was being effective by reducing the product thickness on top of the water table resulted in the decreasing of the BTEXN.

31 Table 8: Summary of BTEXN concentration in the samples taken from AH1 to AH8, during March 2001

Constituents AH1 AH2 AH3 AH4 AH5 AH6 AH7 AH9 Benzene nd nd nd nd nd nd nd nd Toluene nd nd nd nd nd nd nd nd Ethanol nd nd nd nd nd nd nd nd Ethyl nd nd 0.03 nd nd nd nd nd benzene Mixed nd nd 0.84 nd nd nd nd nd Xylene Naphthalene nd nd 1.55 nd nd nd nd nd Tame nd nd nd nd nd nd nd nd Other GRO nd nd 112.07 nd nd nd nd nd Sample type water water water water water water water water GRO = Gasoline range organics Nd = Not detected

In Table 8, chemical samples were collected from AH1 to AH8, and Ethyl benzene, mixed Xylene, Naphthalene and GRO were only detected in AH 3. This is an indication that the decrease of HC in AH3 is slow and the borehole serves as a hotspot.

Table 9: Summary of BTEXN concentration in the samples taken from MW5 to MW21 during March 2001

Constituents MW5 MW7 MW9 MW11 MW13 MW15 MW17 MW19 MW21 Benzene nd nd nd nd nd nd nd nd nd Toluene nd nd nd nd nd nd nd nd nd Ethanol nd nd nd nd nd nd nd nd nd Ethyl nd nd nd nd nd nd nd nd nd benzene Mixed nd nd nd nd nd nd nd nd nd Xylene Naphthalene 1.14 nd nd nd nd nd nd nd nd Tame nd nd nd nd nd nd nd nd nd Other GRO 16.78 nd nd nd nd nd nd nd nd Sample type water water water water water water water water water GRO = Gasoline range organics nd = Not detected

32 In Table 9, the chemical analysis was conducted in the monitoring borehole MW5 to MW21 and only MW5 indicated the presence of mixed Xylene and GRO.

Table 10: Summary of BTEXN concentration in the samples taken from MW23 to MW27 during November 2001 Constituents MW23 MW25 MW26 MW27 Benzene nd nd nd nd Toluene nd nd nd 1.03 Ethyl benzene nd nd nd nd Mixed Xylene nd nd 0.77 nd Tame nd nd nd nd Sample type water Soil Soil Soil GRO = Gasoline range organics Nd = Not detected

In Table 10, three soil samples and one water samples were taken from the MW23 to MW27, Toluene and Mixed Xylene were evident in soil analysis of MW26 and MW27, water analysis was clear i.e. no presence of the HC. Therefore, it is clear that no detectable levels of HC were found in any of the water samples for the percussion holes.

33 Summary of the drilled monitoring boreholes with their depth. Table 11: Summary of all drilled monitoring holes Borehole/ Percussion/Auger Depth Purpose hole no: AH1 36m Monitoring of the deeper aquifer on the western boundary (inside the secondary source area) AH2 10m Monitoring of the shallow aquifer on western boundary (inside the secondary source area) AH3 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found AH4 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found AH5 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found AH6 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found AH7 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found. AH8 31m Monitoring of the deeper aquifer in the area where high soil vapour concentration were found. Free phase encountered but was not found in this hole AH10 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found AH11 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found AH12 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found AH13 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found AH14 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found AH15 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found MO1 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found MO2 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found MO3 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found MO4 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found MO5 26m Monitoring of the deeper aquifer in the area where high soil vapour concentration were found MO6 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found MO7 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found MO8 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found MO9 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found MW5 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found MW7 10m Monitoring of the shallow aquifer in the area where high soil vapour

34 concentration were found MW9 10m Monitoring of the shallow aquifer in the area where high soil vapour concentration were found MW11 10m Monitoring of the shallow aquifer. This hole was drilled to outline the western boundary of the pollution plume MW13 31m Monitoring of the deeper aquifer. This hole was drilled to outline the western boundary of the pollution plume MW15 10m Monitoring of the shallow aquifer. This hole was drilled to outline the western boundary of the pollution plume MW17 10m Monitoring of the shallow aquifer. This hole was drilled to outline the western boundary of the pollution plume MW19 10m Monitoring of the shallow aquifer. This hole was drilled to outline the western boundary of the pollution plume MW21 10m Monitoring of the shallow aquifer. This hole was drilled to outline the western boundary of the pollution plume MW23 10m Monitoring of the shallow aquifer. This hole was drilled to outline the western boundary of the pollution plume

It must however be noted that some of the soil samples taken during the drilling were polluted but no pollution was found in the watercourse itself (Table 11). The monitoring borehole, percussion holes, auger holes were drilling to their different specifications. A percussion hole and a monitoring hole can each be drilled up to 10m deep. Only in special cases can they be drilled for 10 -30m deep but this is very rare. Percussion is drilled to obtained samples from the subsurface. An auger hole can be drilled from 10 - 60m deep. These holes are used for analysis of both water and soil.

4.2 Data Analysis

In the data analysis phase as Figure 10, 11, 12 and 13 indicates the groundwater level and free product thickness increase respectively between February 2001 and December 2001. The groundwater level was low in MO1 to MO9 with an increase from MO5 to MW17. There was another notable decrease in MW 21 to MW 25, with yet another increase in MW26 and MW27. Figure 11 indicates a significant decrease of the free product thickness in the water table. MW16, MW17 and MW26 show an alarming increase of the free product in those monitoring holes. Other holes indicate no presence of free products.

Figure 10: Free product thickness in MO1 to MW27 monitoring holes from Jan 2001 to Dec 2001

From figure 10 it can be concluded that a pulse of Jet fuel has moved through this area. Using this data, the inferred groundwater flow direction, a porosity of 0.05 and a flow gradient of 0.002 a hydraulic conductivity of 2.3m/ day was calculated for the Jet fuel. It can thus be concluded that the hydraulic conductivity of the groundwater in an order of magnitude smaller than that of the Jet fuel.

Figure 11: Trends in depths to groundwater data for all monitoring holes during the monitoring period

Figure 12: Trends in free product for all monitoring holes during the monitoring period

Figure 13: Free product thickness in transect auger holes

Figure 14: Apparent free product thickness in a well

The solid grey part indicates the depth of Plunging and the hatched grey part is the watertable in relation to the depth of plunging. To be able to estimate the true free product thickness in the surrounding environment of a monitoring well, a bail test can be done. Firstly a short explanation on the thickness of free product measured in monitoring well and why it is always more than what is present in the aquifer. The hydrocarbon accumulates on the capillary fringe. When a well is installed, the product will flow into it onto the water level where the fluid pressure in the pores equals atmospheric pressure. As it can be seen from Figure 14, the thickness measured in the well will always be more than the real thickness in the surroundings. (Blake & Hall, 1984) suggested a method to determine the real free product thickness in the surrounding environment.

Figure 14 shows the situation in a well where free product is situated above the capillary zone. As petroleum migrates downwards it encounters the zone above the water table where due to capillary attraction the soil contains water. The pores are 100% saturated but capillary forces hold water. The petroleum cannot displace the water due to interfacial forces of the two immiscible fluids (Blake & Hall, 1984).

40 4.3 Modelling Process

During the modelling process, more information was obtained via samples and other methods i.e. geophysical methods that can be used to construct a three-dimensional model for the affected area and for developing a remediation strategy that will be effective (Eslinger et al., 1994). Hydrogeologic model solutions have the following purpose: to define the extent of the problem so that remedial action can be taken and groundwater movement can be interpreted. If the water in the formation is contaminated with hydrocarbons, air stripping and activated carbon treatment are possible remedial solutions (Walton, 1989b).

Different scenarios are considered during the modelling process and the spread of hydrocarbons are simulated. These results are then compared to field observations. Changes are made to the input and the model is consequently executed until the results estimate the field data. Several assumptions have to be made during modelling. The first set pertains mostly to the natural environment and were thus kept constant. The second set of assumptions relates to the details of the spill. With the EPA HSSM model it is not possible to model anything else than a point source (Van der Linde, 2002).

Constant assumptions for the model were:

¾ Recharge to the area of the plume was zero due to the surface covering ¾ Depth to groundwater was taken as 5m ¾ Porosity of the subsurface environment was estimated to be 20% ¾ Groundwater gradient was set at 0.02 based on topographical data

4.3.1 GMS Software Model

The groundwater modelling software (GMS) package was used to approximate the groundwater flow as well as the advection-dispersion equations and to provide numerical solutions for the concentration values in the aquifer in time and space.

41 Input to the software is: ¾ The finite difference grid data ¾ Input concentrations of contaminants ¾ Horizontal hydraulic conductivities ¾ Porosity value for the saturate portion of the aquifer ¾ Longitudinal dispersivities ¾ Hydraulic heads in the aquifer over time ¾ Transversal dispersivities (Van der Linde, 2002).

4.3.2 Construction of the finite difference mesh

In general, the compilation of a finite difference model necessitates the construction of a cell centred rectangular grid over the area of investigation incorporating groundwater levels, geology, borehole positions and boundaries. The GMS element grid generator was used to construct the network shown in Figure15 (Van der Linde, 2002)

Figure 15: Finite difference network of the investigated area

Figure 16: Approximate location of the plume

The blue colour on figure 15 and figure 16 shows the migration of the plume. The area of the plume was calculated to be 640m². For the purpose of the model this was approximated with a circular plume with equivalent radius of 108m. Using the bail test data, the free phase thickness was taken to be about 30cm (Van der Linde, 2002) The x;y wire mesh axis interception represents were the plume will be plotted during the modelling process for the migration of the plume.

4.3.3 Model flow

The geometry of most aquifers is such that they are of little depth relative to their horizontal dimensions. The assumption can be made that the flow in the aquifer is essentially horizontal, or that it may be approximated as such. This is strictly true for flow in a horizontal, homogenous, isotropic, confined aquifer of constant thickness and with fully penetrating wells. The approximation is good when the thickness of the aquifer varies, but in such a way that the variations are much smaller than the average thickness (Bear and Verruijt, 1992).

43 However, if the opposite applies namely that the aquifer extents to great depth relative to its horizontal distribution, the vertical flow components can no longer be neglected. It is important to collect the appropriate three-dimensional data such as piezometric pressure for each aquifer as well as hydraulic conductivities and specific yield for each modelled layer (Van der Linde, 2002).

Figure 17: Modelling process of pollution degradation

The migration flow of the plume is towards the western side from where the source was identified at the in-flight service area (Figure 17). Topography influences the direction flow of the plume. The flow takes place along the bedding planes of different geological layers, as a continuous pollution from the contaminated soil in the close vicinity of the polluted source with a slow lateral velocity. The direction of the groundwater flow can mimic the overall surface topography and the flow in a down slope direction towards low-lying watercourses (Van der Linde, 2002).

44 Chapter 5: Review of the available Remediation Technologies

In most cases, soil gas surveys should be the first step in an investigation so that adequate information is available for planning subsequent portions of a programme (Tillman et al., 1989). Shallow probing is subject to certain interferences inherent in soil conditions, particularly variations in vertical vapour conductivity due to: • Top soil texture • Subsurface freezing • Water content • Vapourclude

Field installations often encounter variation in repeatability due to: • Insufficient penetration • Inadequate purging • Improper sealing of vapour monitoring (Kerfoot, 1988)

The physical factors are presence of confining layers or structures between the contaminant source and the soil vapour point, failure to adequately seal the sampling point to the atmosphere, and non-homogeneity of the effective porosity of the soil matrix (Reisinger et al., 1986). A second physical factor with the potential to significantly affect soil vapour survey data is soil moisture. The presence of moisture in the soil can serve to decrease the rate of vapour migration (Reisinger et al., 1986).

Frequently, soil gas responses observed in the field are reduced immediately following rainfall. In those cases where contamination is limited to low levels in the groundwater, there may be insufficient volatilization into the overlying soil pores to obtain measurable readings in the vadose zone (Crockett and Taddeo, 1988). The results indicated that, while not a panacea, soil gas is a good technique but one that requires careful data interpretation (Marks and Singh, 1990).

45 A means by which soil heterogeneity and deeply sourced contamination can be addressed in vertical profiling. Generally, one or several vertical profiles can be conducted to determine the best sampling depth to complete the remainder of the site (Burris et al., 1988).

Remediation means cleanup. Remediation activities generally take place once it is certain that a site has been contaminated. A variety of technologies/ methodologies are available and constant research into new technologies is being undertaken. Every site is unique and only appropriate methodology will be applied accordingly. Methods are decided upon through consideration of the subsurface matrix, contaminant and cost implications. Some of the methods of soil remediation include the following:

5.1 The types of available hydrocarbon remediation technologies

1. Physical remediation technologies a) SVE and Air sparging b) Vacuum Enhanced Recovery (VER) c) In Situ Soil Venting d) Bio-enhanced Soil Aeration e) Pump and Skimmers f) Recovery Wells and Cut-off Trench 2. Biological remediation technologies a) Bioremediation (MNA) b) Phytoremediation 3. Chemical remediation technologies a) Pump and Treat – Carbon Adsorption 4. Thermal Technologies a) Thermal treatment

46 5.1.1 Physical Remediation Technologies a) SVE and Air Sparging

Soil vapour extraction and air sparging is generally used on volatile substances. Air sparging is a relatively new remediation technique that sometimes can be used as a means of recovering dissolved hydrocarbons from the zone of saturation. This refers to compressing air into the saturated zone where contamination exists (Figure 18) (Appendix 4). A B C D E F

Figure 18: Air sparging and Monitored Natural Attenuation (ABU GmbH Bad Saulgau –Germany)

Symbols as per the above Figure 18 A- Airflow monitor B- Airsparging main motor C- Air compressor D-Air inlet pipes E- SVE pipe (outlet pipe) F- Sparging point

47 Figure 18 and 19 show how the air sparging container unit looks like from a cross section point of view. Compressed air is forced into the contaminated aquifer using sparging points. A small-diameter PVC pipe is installed vertically from the surface to the depth where compressed air is to be forced into the aquifer.

A B C

Figure 19: Air sparging process (ABU GmbH Bad Saulgau –Germany)

A-Compressed air in B-Air out C-Air/ water molecules centrifuge in the watertable

The pressure of the compressed air must exceed the water pressure due to the hydrostatic head of the aquifer (Marley et al, 1992). The air then rises as bubbles through the water column and this causes dissolved HC to volatilize into the air bubbles. The bubbles rise to the top of the groundwater column, along with the entrained volatilized HC and emerge at the water table where they can be picked up by a soil vapour extraction system.

Figure 20: Air sparging equipment in use (ABU GmbH Bad Saulgau –Germany)

Figure 19 and 20 indicate the soil vapour extraction system where compressed water comes out from the underground to the surface area. The water in the two water beakers/ bottles in Figure 21 show how the darker material on the left is hydrocarbon contaminated before the remediation process. The clearer water on the right is cleaned compressed water from the underground vapours from the soil vapour extraction system.

Figure 21: Air sparging analysis conducted before and after the remediation process (ABU GmbH Bad Saulgau –Germany) b) Vacuum Enhanced Recovery System (VER)

VER is a commonly used and proven technology for the in-situ remediation of soils and groundwater in specific geological settings. VER of both liquid and vapour phases of the contaminant is generally undertaken when there are substantial volumes of free phase present. VER is undertaken by installing a drop tube (Slurp tube) into the free product/ air interface and applying a vacuum enhanced pumping technique. VER has several benefits over free product recovery method, (Van der Linde, 2002) namely:

• Vapour phase and free product recovered simultaneously • There is no induced drawdown and smearing effect at the well • Microbial degradation is enhanced due to aeration of the subsurface

The success of VER depends on the nature, extent and depth of the contamination as well as the nature of the sub surface-vadose and saturated zone.

50 A VER remedial system is most successful under the following conditions: • Groundwater elevations between 2-10m below the surface • Medium to low permeability media • Volatile free product plumes floating on the water table under paved areas.

The information below pertains to the VER Containerised Remediation Unit:

Container 1. 3m steel frame construction with lifting and securing points 2. Secure container housing all equipment 3. Container has interior lights and extraction fans for continuous ventilation

Power supply Mains electrical supply -380/220V 16kW is required at the site of the container (Van der Linde, 2002).

Equipment Required 1. Vacuum to be generated by Liquid Ring Pump (oil sealed) capable of yielding 200m³/hr. The pump is to be manifold to extract liquid and vapour from three wells simultaneously 2. Complete Electrical Control Panel with two tow away telemetry output (4 IN – 8 OUT) 3. Automatic Safety Shutdown and Re-start controls via GSM telemetry. 4. Air/ liquid separated within unit and liquid discharged to existing separator. The process is continuous and liquid discharge (diaphragm pump – 50 l/min) occurs during Multi Phase Extraction without shutting off the system 5. Volatile emissions exhausted to atmosphere via stack. Emissions will be monitored and discussed with the authorities for necessary corrective actions required. 6. The unit has a wide operating range, low noise, low maintenance and high efficiency. 7. Extraction of free-phase product and vapour at the same time 8. Monitoring of extraction rate (vapour), extraction rate liquid) and total vapour extraction and time of operation.

51 9. Drop tubes and header lines are to be installed below grade. Manholes with well- heads and site glasses to be installed level with grade over each well. (Figure 22 Process flow and diagram Figure 23 shows the inside of a containerised VER unit) (Van der Linde, 2002).

Figure 22: Process Flow Diagram of VER (Whitfield, 2002)

Figure 23: VER System (Whitfield, 2002)

Explanation for the Process Flow

Each well will have a drop tube installed to the oil/ water interface depth. The well-head is then sealed thereby allowing a vacuum to be created within the well. A transparent glass at the well-head would allow for visual observation of the abstraction. This would normally be a good place to install a valve. However due to the possibility of tampering, it would be recommended that the valve be installed within the container just before the K/O 1 vessel (Figure 22). Knockout 1 separates the liquid and vapour phases. The well- head would be situated below grade (in a manhole) and each well will have its own independent transfer pipe connecting well and K/O 1 (Van der Linde, 2002).

The wells will be manifold to discharge into K/O 1, which will have three level controls, which will regulate the discharging of the liquid from K/O 1. The liquid will be discharged to the existing liquid separators on site through an in-line flow meter. The liquid discharge pump is a fuel resistant diaphragm pump capable of yielding 50 l/min. A 3kW 15 CFM compressor powers the diaphragm pump. A Liquid Ring Pump- using oil

53 as the sealing liquid will generate vacuum. The pump is very quiet, efficient and can generate high vacuums required in the clayey soils typical of the area site (Van der Linde, 2002).

The vapour stream passes though Vacuum Pump and is exhausted into a condensate vessel-K/O 2. This collects any condensate that occurs due to temperature and pressure changes as the vapour passes through the pump. This vessel also has liquid level controls. The vapour phase is then discharged to the atmosphere without via a stack located ± 5m from ground level.

The VER unit has a GSM telemetry link to four outside cell phones (SMS) to notify operating conditions of the system especially if there are any operational problems (power outages/ equipment failure). In some instances the unit may be re-started by the GSM telemetry (Van der Linde, 2002).

Table 12 show the cost estimate of a VER installation. The cost estimate include all the information which has to be incorporated when a VER is installed until its utilised and the follow up thereof. Once a VER system is installed, continuous monitoring has to be conducted to determine if the system is producing the desired result and the effectiveness thereof.

54 Table 12: Cost Estimate for VER Installation for 2003 @ 6% annual inflation rate Description Rate Quantity Amount Mobilisation R3.50/km 2000km R7,000.00 Field monitoring & supervision R125.00/hr 40hrs R5000.00 Project management costs R10350.00/unit 1unit R10,350.00 Data interpretation + report R175.00/hr 48hrs R8,400.00

Sub Total R30,750.00 Containerised VER remediation R156871.25/unit 1 unit R156,871.25 unit R2750.00/unit 1 unit R2,750.00 Site establishment R4500.00/unit 1 unit R4,500.00 Installing and commissioning R11163.50/unit 1 unit R11,163.50 Drilling of three additional monitoring wells Laboratory Organic analyses of water R390.00/sample 12 samples R4,680.00 VOC vapour measurements R250.00/measurements 20 measurement R5,000.00 Total Costs R215,364.75 VAT (14%) R35,260.13 Total R250,624.88 c) In Situ Soil venting

Soil venting is accomplished by burying a slotted or perforated pipe or hose in the contaminated soil and then connecting a pipe to a fan or blower located on the surface so that soil gas is removed from the volume of soil surrounding the pipe (Angell, 1992). Typical soil vent systems for small sites of about 200m² and a contamination level which is of primary nature, might be installed for US$2,000 to US$10,000 i.e. SA currency @ R6,50 on 11 June 2004 were R13 000 to R65 000. Monitoring for such sites where the hydrocarbon contamination occurs consists of taking periodic photoionization detector reading from the downstream side of the blower. Ideally, the vapour should decrease with time (Appendix 6 and Appendix 7) (Eslinger et al., 1994). d) Bio-enhanced Soil Aeration

This method involves excavation of the soil and then spreading it on an impermeable material to a depth of no more than about 2m. Fertilizer in then added to the soil

55 periodically (19-3-3 with no herbicides has been recommended NYSDEC spill engineers and the soil is tilled periodically, at least every three months. The contaminated soil is usually placed on an impermeable stiff liner or a plastic poly liner covered with a layer of sand. The liner is beamed to prevent runoff. The goal is to accelerate natural bioremediation via aeration and nutrient supply. A combination of evaporation and bioremediation stimulated by fertilizer nutrients results in both destruction and volatilization of the contaminants (Appendix 8) (Eslinger et al., 1994). e) Pump and Skimmers

This refers to the pumping of water from the subsurface to the surface for treatment. Pumps are either submersible or located on the surface. Various types of submersible pumps exist. Some result in less agitation of the water than others, and if the formation of emulsions is to be minimised, selection of a pump that minimises agitation should be a priority. An advantage to locating the pump on the surface is that it can be serviced easily because it does not need to be pulled from a well (Eslinger et al., 1994). A common type of pump located on the surface is a double diaphragm pump. This type of pump is operated using compressed air, so a compressor is needed on site.

If a free product is present, a skimmer pump can be used. These systems pump only the floating product. The hose is usually fed into a storage tank on the surface. When a storage tank nears full, a vacuum truck is brought to the site to vacuum off the product and take it to a recycling area. Pumps also exist which are dual purpose: free product is pumped from above the water to the surface, and water with dissolved hydrocarbons is simultaneously pumped to the surface from below the free product layer. The water pump causes a drawdown which accelerates the movement of free product into the well (Eslinger et al., 1994).

56 f) Recovery Wells and Cut-off Trenches

A recovery well is a well containing a submersible pump or water line leading to a pump on the surface. The purpose of the pump is to pump groundwater to the surface for treatment. The recovery well must be positioned so that the contamination plume does not spread and so that the contaminated water is captured within the drawdown cone of depression (radius of influence). Typically, the recovery well will be close to, but slightly down gradient from, the location of maximum contamination. When a submersible pump is used, the diameter of the well must be larger enough to accept the pump along with any necessary controls. A hole excavated with backhoe can be made into a recovery well by installing a large-diameter PVC well casing or a culvert pipe into the hole with appropriate gravel packing. Since the recovery well will be pumping water, it needs to be deep enough to produce a sufficient cone of depression to capture the contamination plume (Eslinger et al., 1994).

In situations where it is imperative that the contamination be prevented from spreading offsite, an interceptor or cut-off trench might be constructed. The purpose of the trench is to intercept groundwater, and then to pump the intercepted groundwater to the surface for treatment. Thus in this situation, a recovery pump is placed in the trench (Appendix 9) (Eslinger et al., 1994).

5.1.2 Biological Remediation Technologies

a) Enhanced Bioremediation (Monitored Natural Attenuation)

When considering bioremediation, there are many unanswered questions regarding the catabolic capabilities of indigenous microorganisms towards aromatic contaminants (e.g. Which aromatic hydrocarbons are more frequently degraded? Which ones are the most recalcitrant? Are microbes that degrade a given compound also capable of degrading homologous contaminants? Are microbes that degrade polyaromatic hydrocarbons also capable of degrading simpler monoaromatic hydrocarbons, but not vice versa) (Gulensoy & Alvarez, 1997).

57 Answers to such questions are needed to understand microbial degradation capabilities and limitations and to explore the evolution and prevalence of different catabolic pathways. We hypothesize that the relaxed substrate specificity of many oxygenize enzymes allows for some correlations on ability or inability of indigenous microorganisms to degrade different aromatic hydrocarbons (Gulensoy & Alvarez, 1997).

The first step in the remediation process is to break the contamination cycle and to re- establish the biological activity in the soil, or to bioremediate the soil. After removing or remediating the contaminant, this is accomplished by introducing beneficial bacteria, actinomycetes and fungi into the soil. They will protect the plants from pathogenic microorganisms (soil & foliar), minimize nutrient leaching, aid in nutrient cycling and absorption, improve soil structure, solubize minerals (including phosphorus) for plant availability, produce natural plant growth hormones, enhance plant growth, increase soil buffering properties and reduce the negative effects of environmental stress (Van der Linde, 2002).

The older organic methods relied on composted manure to provide the necessary biological activity in the bioremediated soil. Today, with the advances in soil management, these beneficial bacteria and fungi are available in scientifically formulated, highly effective, easy to use products (Van der Linde, 2002).

Naturally occurring organisms in soil and groundwater break down a large range of organic contaminants. Through enhanced bioremediation, these organisms are provided with an environment where they can grow and break down contaminants at a higher rate. This is done by the addition of oxygen (either through sparging or oxygen releasing compounds) and nutrients. A variety of other environmental factors may be manipulated to enhance the natural process breaking down pollutants. Natural attenuation is however recommended with specific reference to the dissolved pollution plume and not the free phase plume (Van der Linde, 2002).

58 Bioremediation designs can be divided into indigenous and exogenous systems, and into in situ and ex situ systems. An indigenous system uses the native bacterial population, whereas an exogenous system introduces bacteria that have been collected or cultured specific for the contaminant present. In situ means treatment of contaminated soil in place and ex situ means that contaminated soil removed and treated elsewhere of its natural site (Eslinger et al., 1994). According to Testa and Winegardener (1991) ex situ can be divided into two categories i.e. suspended growth and fixed-film system. In a fixed-film system, the bacteria are not suspended in water but are fixed to an inert framework through which the water flows.

In order to assess whether natural processes are in fact degrading the hydrocarbon substance, it is necessary to sample the groundwater in a certain way. During the breakdown of hydrocarbons, organisms use compounds as electron acceptors to change the groundwater environment in such a way that their presence can become known by tracking changes (Van der Linde, 2002). The most important ones are nitrate, sulphate and ferric iron. Some elements are used up as nutrients, e.g. ferrous iron, manganese, phosphorus (Cobb et al., 1997).

Thus depletion of the nutrients and an increase in the electron acceptors can be used to gauge the bacterial activity. As the aerobic bacteria are usually much more efficient in using hydrocarbon as food source, their numbers grow rapidly and a consequent depletion of dissolved oxygen is observed in a plume where active degradation is taking place (Van der Linde, 2002).

The sampling of natural attenuation in a well over time becomes stagnant and changes composition, notably with regards to inorganic compounds. It is of the utmost importance that the groundwater sample that is collected from the well will be representative of the aquifer system. Therefore each hole has to be purged until the temperature, pH, EC and dissolved oxygen stabilise. Only then can a water sample be collected and submitted for analyses. DWAF prescribes this method of groundwater sampling for inorganic compounds. The DWAF specification for drinking water (SABS

59 241 Gr 7, 2001), outlines the recommendations contained in SABS ISO 5667-1, to be used for the establishment as well as the basis for implementing the sampling programme. Thus as opposed to sampling for hydrocarbon substance, which is usually done by collecting a floating sample, the method for indicating natural attenuation entails groundwater sampling first by purging wells. The chemistry of water that enters well changes as it comes into contact with oxygen in the well. Purging thus ensures that the water sample is representative of the surrounding aquifer (Van der Linde, 2002).

Through a risk based approach, it may be decided not to take any specific action on contamination. A variety of contaminants such as hydrocarbons are broken down through natural process. If the risks posed by contaminants on site are not high and contaminants are contained it may be decided that no external remediation actions will be taken. Contaminants concentrations are then monitored regularly to ensure that natural attenuation is taking place. This remediation option is re-evaluated on a constant basis and further action is taken if the monitoring results are not satisfactory (Van der Linde, 2002).

Cost of sampling event

Thus the work entails purging each well until the mentioned parameters stabilise and then collecting a number of groundwater samples. One set of samples will be analysed for hydrocarbon and the second set for inorganic ion distribution. From the data to be obtained, the efficiency of natural attenuation can be determined on site (Van der Linde, 2002).

Table 13 outlines the cost for one sampling event. Four sampling events are recommended over a twelve months period to obtain sufficient data for analyses. The results of the four events can be pursued to determine future actions.

60 Table 13: Cost Enhanced Bioremediation (MNA) of one sampling event in 2002 @ 6% annual inflation. Qty Unit Total Groundwater Sampling Mobilisation 400 samples R3.00 R1,200.00 Sampling field work 32 samples R225.00 R7,200.00 Reporting 10 R300.00 R3,000.00 Laboratory Organic analyses 30 (tests) R650.00 R9,750.00 Inorganic analyses 30 (tests) R350.00 R5,250.00 Subtotal R26,400.00 VAT R3,696.00 Total R30,096.00

Four sampling runs are recommended, thus R105 600.00 excluding VAT can be budgeted for a one year period. These will be used for 30 selected boreholes after in this study which the schedule and amount of boreholes will be re-evaluated (Van der Linde, 2002). b) Phytoremediation

Phytoremediation is the use of vegetation for in situ treatment of contaminated soils, sediments and water. It is best applied with shallow contamination of organic nutrient, or metal pollutants that are amendable to one of five applications (Gatliff, 1994).

Phytotransformation, rhizoshere bioremediation, phytostabilization, phytoetraction or rhizofiltration. Phytoremediation is well-suited for use at very large field sites where other methods of remediation are not cost-effective or achievable (Gatliff, 1996). Phytotransformation depends on the direct uptake of contaminations from soil water and the accumulation of metabolites in plant tissue. For environmental application, it is important that the metabolites in vegetation be non-toxic or at least significantly less toxic than the parent compound.

Plants are able to take up contaminants directly from the soil water release exudates that help to degrade organic pollutants via cometabolism in the rhizosphere. Direct uptake of organics is a surprisingly efficient removal mechanism from sites contaminated at a shallow depth with moderately hydrophobic organic chemical. This includes most BTEX chemicals, chlorinated solvents and short chain aliphatic chemicals. Hydrophobic chemicals are bound so strongly to the surface of roots and soils that they cannot be easily translocated within the plant and chemicals.

The direct uptake of chemicals into the plant through roots depends on the uptake deficiency, transpiration rate, and the concentration of chemical in soil water uptake (Burken and Schnoor, 1997a), while efficiency depends on physical-chemical properties, chemical speciation and the plant itself. Transpiration is key variable that determines the rate of chemical uptake for a given phytoremediation. It depends on the plant type, soil moisture, temperature, wind conditions and relative humidity.

Once an organic chemical is translocated, the plant may store the chemical and its fragments into new plant structure via lignification or it can volatize, metabolize or mineralize the chemical completely to carbon dioxide and water (Newman et al., 1997). The transfer of contaminants from the soil or groundwater to the atmosphere is not as desirable as in situ degradation, but it may be preferable to prolonged exposure in the soil environment and the risk of ground-water contamination.

Detoxification mechanisms may transform the parent chemical to non-phytotoxic metabolites that are stored in plant tissues (Schnoor & Nair, 1995). A thorough understanding of pathways and end-products of enzymatic processes will simply toxicity investigations on in-situ phytoremediation.

Phytoremediation of the rhizosphere increase soil organic carbon, bacteria and mycorrhizal fungi, all factors that encourage degradation of organic chemicals in soil. Rhizosphere bioremediation is also known as phytostimulation or plant assisted

62 bioremediation (Entry, 1996). Also, plants may release exudates to the soil environment that help to stimulate the degradation of organic chemicals by inducing enzyme systems of exiting bacterial populations, stimulating growth of new species that are able to degrade the waste, and/ or increasing soluble substrate concentrations for all microorganisms.

Anderson (1993) has demonstrated the importance of biodegradation in the rhizosphere. Plants help with microbial transformations in many ways:

• Mycorrhizae fungi associated with plant roots metabolize the organic pollutants • Plants exudates stimulate bacterial transformations (enzyme induction) • Build-up of organic carbon increases microbial mineralization rates (substrate enhancement) • Oxygen is pumped to roots ensuring aerobic transformations

Phytostabilization is especially applicable for metal contaminants where the best alternative is often to hold contaminants in place (Kumar et al, 1995). Metals do not ultimately degrade, so capturing them in situ is sometimes the best alternative at sites with low contamination levels (below risk threshold) or vast contaminated areas where a large-scale removal action or other in situ remediation is not feasible. Phytoextraction has bee used effectively for contaminated soil to bring them below action levels (McGinty, 1996). For phytoextraction to be effective, one need vigorously growing plants, an easily harvestable above ground portion, and a plant that accumulates large amounts of contamination in above ground biomass (Licht, 1990).

To achieve clean-up within three to five years, the plant must accumulate about ten times the level in soil (e.g. if the level in soil is 500mg/kg, then the concentration in the plant must be almost 5000mg/kg to clean-up the soil pollutants in a few years (Clarkson, 1991).

63 Rhizofiltration indicates that the roots of plants are capable of absorbing large quantities of lead and GRO from the soil or water that is passed through the root zone of densely growing vegetation. VOC’s may be transpired by the plant, and simple air toxics models can be used to determine if they may pose an unacceptable risk to the atmosphere (Briggs et al., 1982).

Aerobic rhizosphere bioremediation is thought to be effective for aromatic hydrophobic chemicals such as BTEX and phenols (Hedge and Fletcher, 1996) at sites with shallow contamination (Hsu et al., 1992). For applications involving groundwater remediation, a simple capture zone calculation (Domenico and Schwartz, 1997) can be used to estimate whether the phytoremediation “pump” can be effective at entraining the plume of contaminants. If the contaminant plume is not taken-up by the vegetation, the plume that emerges will be evapoconcentrated, i.e. the mass of contaminant in the plume will be less due to uptake by vegetation, but the concentration remaining will actually be greater.

Phytoremediation is a newly developed technology for soil remediation. In South Africa such remediation process are not in place and still has to be researched further before they can be introduced. The type of climate, soil and trees has a great influence on the successes of the phytoremediation process.

The costing model on table 14, was changed to the SA currency @ R6.50; on the 11 June 2004, the cost was R1 170 000. 00. Such huge cost in SA economy of scale can results in the liquidation of an organization.

64 Costing Model

Table 14: Costing model for Phytoremediation Process Costs Design & implementation US$ 50.000 Monitoring equipment US$ 20.000 Installation US$ 40.000 Replacement US$ 20.000 Travel & administration US$ 10.000 Data collection US$ 10.000 Sample analysis US$ 10.000 Consulting US$ 10.000 Reports (bi-annual) US$ 10.000 Total US$ 150.000

5.1.3 Chemical Remediation Technologies

a) Pump and Treat – Carbon Adsorption

Hydrocarbon contaminants dissolved in water (or present in a vapour) can be adsorbed by carbon. GAC (Granular Activated Carbon) is fine-grained carbon that has been “activated” so that it has a high surface area and so will have excellent absorption properties. The adsorption capacity of a particular grade of carbon for a given hydrocarbon compound is determined from adsorption isotherms. Adsorption onto GAC is internal to the GAC; i.e. the GAC has a sponge-like internal network of pathways that effectively give the GAC a very large surface area. The contaminated groundwater is pumped to the surface and then through a container that holds the activated carbon (Appendix 5) (Eslinger et al., 1994).

The up-stream GAC container can be replaced after breakthrough to the second container is detected by sampling. The second container is then moved to the upstream position, and the first container replaced with fresh GAC and placed in the number 2 position. The sediment filter prevents clogging of the GAC chamber. The separator aids in two ways: it prevents known or unknown free product pulse from entering the GAC chamber, and it separates low density emulsions from entering the GAC chamber. The iron filter prevents the clogging of the carbon in the carbon drums with iron precipitates (Eslinger et al., 1994).

65 5.1.4 Thermal Remediation Technologies a) Thermal Treatment

Thermal treatment has distinct advantage of a permanent destruction of hazardous material. This uses specialized retorting/ desorption technology. It’s an approved technology and is accepted by US EPA as a mature and demonstrated technology.

Figure 24: Thermopower Treatment Process

i. The functionality of thermal treatment Plant

A gas clean-up is used to remove heavy metals, particulates and unwanted pollutants from the gas stream. The thermal power plants are relatively small and mobile. They can be transported to the contaminated site. This enables compliance with Basel Convention on the Control of Transboundary Movements of Hazardous Material to which South Africa is a signatory. The Convention’s article 4 No 9(a) specifically refers “The state shall take appropriate measures to ensure that the transboundary movement of hazardous material only be allowed if (it) does not have the technical capacity and the necessary facilities in order to dispose of the products/ material/ waste in question in an environmentally sound and efficient manner” (Tsinonis, 2003).

66 The thermal de-sorption plant is operated at a temperature of 95ºC to 600ºC (sometimes even higher) so that contaminants with low boiling points will vaporise and separate from the solid matrix.

Soil can be heated to volatilize HC’s. The essential components are a kiln, an afterburner, and a system for particulate collection. The latter is usually accomplished with a baghouse, although a quench chamber can be used. Soil is fed into a kiln and heated up and semi-volatile HC’s are vaporised. The vapours and any entrained clay and silt-sized soil matrix pass through a baghouse where particulates are collected and transported back into the kiln. The vapours then pass into an afterburner where temperatures of 800ºC to 1000ºC destroy the HC vapours. The gaseous by-products are emitted into the atmosphere i.e. soil pollution becomes air pollution. This means that a phase of the pollution has been merely changed from the liquid to the gaseous phase. Therefore, the problem is not entirely resolved in term of the Atmospheric Pollution Prevention Act 45 of 1965 (APPA, 1965). The treated soil passes out of the kiln and is then placed back into the hole from which it was excavated.

Water is sprayed on the gases and air-entrained particulates in the quench chamber causing them to settle and the liquid is pumped back to the water supply. The slightly cooled vapours continue to a centrifuge where they are separated from any remaining liquids. The vapours pass into the atmosphere and the liquids cycle back into the quench chamber. The throughput of these systems varies greatly with high temperature unit, but typically ranges from 5 to 30 kg per hour. The throughput depends on the type of soil, the nature of the contamination (readily volatilized contaminants take less energy to volatilize and thus require less time in the kiln), and the design of the equipment. Cost for treating hydrocarbon fuel contaminated soils typically varies between U$ 40 and U$80, converted to SA currency on the 11 June 2004 i.e. R2 600 and R5 200 per 1000kg using this method. Direct soil return to the original excavated site saves transportation and backfilling costs (Eslinger et al., 1994).

67 ii. Contamination levels before treatment

With reference to table 15, the major hazardous constituent in another soil pollution study at Petrol and Pesticides manufacturing industry, was Dieldrin with Aldrin also being present in significant concentrations. Several metals were also present in high quantities (Table 15) Average total contamination in the soil was 714 mg/kg (0.07%), with a maximum concentration of 21 430 mg/kg (2.1%) (Tsinonis, 2003 and Eklund et al., (1992). Also in terms of the (APPA Act 45 of 1965), emission levels have to be in accordance to acceptable standard before the release into the environment, taking into account the chimney/ stack height, soot, and prevailing climatic condition in the study area etc.

Table 15: Contamination level in another soil pollution study area before treatment Determinant - Metals (mg/kg) EU Action Value mg/kg (ppm) Concentration mg/kg Barium 625 1200 Chromium 380 320 Lead 530 67 Aldrin - 120 Dieldrin 4 >550

iii. Contamination level after treatment

While the soil was thermally treated, there was regular monitoring by independent companies including the CSIR, Ecoserve, C&M consultants and NECSA. This proved that no contamination was detected in the treated soil. The emissions from the thermal processing plant tested by the CSIR and Ecoserve, complied with DEAT guidelines and US EPA and European emission standards (Tsinonis, 2003 and Eklund et al., (1992).

68 Table 16 shows the particulate matter of various contaminants after treatment with a thermal process. According to the table 16, the first four contaminants, indicates that they are within if not way below the recommended or acceptable level of DEAT guidelines.

Table: 16: Summary of emission test results in relation to standards/ guidelines Determinant Average result EU US EPA DEAT Guidelines Guidelines Guidelines Particulate 4.35 10.00 120.00 Copper (Cu) <0.096 - - 0.50 (mg/dsm³) Lead (Pb) 0.041 - - 0.50 (mg/dsm³) Chromium (Cr) 0.013 - - 0.50 (mg/dsm³) Cobalt (Co) 0.002 - - 0.50 (mg/dsm³) Sulphur dioxide <0.40 50 - 25 (SO2) (mg/dsm³) Carbon monoxide 14 50 - - (CO) (mg/dsm³) Total organic 0.31 10 30 - carbon (TOC) (mg/dsm³) ds implies dry standard conditions (0ºC, 101.3kPa)

69 Chapter 6: Syntheses

6.1 Conclusion and Recommendations

Other issues taken into account are certainty versus sustainability, process technology versus civil engineering. The remediation process has been tried and tested and is not only a science experiment (Sanders 2004 and Sillars, 2004). The selected remediation measures are appropriate and are also based on case by case with possible mixture or combination of remediation. It is better to be approximately right than precisely wrong. It’s wise to be aware of the silver bullet concept therefore, there is no single remediation measure that can solve the contamination problem without the intervention of others.

Phytoremediation is very competitive with other treatment alternatives. It is aesthetically pleasing and its public acceptability is high. It is far less expensive and versatile but it requires five years of operation rather than shorter periods for the competing technologies. It is most comparable to in situ bioremediation and natural attenuation. In

70 these technologies, mathematical modelling and monitoring are necessary to demonstrate the effectiveness of the technology to regulatory agencies. There are also fewer disturbances to the environment because there is no ground excavations and infrastructural mechanisms required. The process is, however, too new to be approved by regulatory agencies in pro forma reviews. The main question that regulators might want to establish is whether phytoremediation can remediate the site to standards and reduce risk to human health and the environment. The questions that remain mostly are the same as those for bioremediation or natural attenuation:

• Can it clean-up the site to below acceptable level? On what time scale? • Does it create any toxic intermediates or products? • Is it as cost-effective as alternative methods? • Does the public accept the technology?

The answer to the latter two questions appears to be positive because phytoremediation has large impetus at the present time. The answer to the first two questions will determine whether phytoremediation will become a major new technology in the future. It is not for hazardous substances/ waste problems, but it shows tremendous potential in several applications for treatment of metals and BTEX organics and VOC’s at sites where contamination is shallow. Plants have the ability to withstand relatively high concentrations of pollutants, they can sometimes absorb the chemicals and convert them to lee toxic products, and they are known to stimulate degradation of organics in the rhizosphere. The technology has not been demonstrated conclusively at many sites to date, and it remains to be seen if it is effective at full scale.

Thermal treatment causes fugitive dust, with a high moisture content which requires more treatment because the soil water absorbs heat in the kiln. Contaminants which do not readily volatilize at high temperature result in high clay content which usually make soil so sticky that it forms large clogs. Typical requirement is that a certain percentage reduction of HC’s present in the contaminated soil be attained. The amount of reduction varies depending on the situation, but a typical efficiency required would vary between 95% and 99, 9% reduction in total VOC’s (Eslinger et al., 1994).

71 A Soil venting system might take months to years to remove sufficient contaminants from the soil. Therefore, the cost of routine maintenance and monitoring needs to be considered when deciding whether or not to install such a system.

GAC has the disadvantage of a container rusting if it is not made up of a rustproof metal and clogging of GAC by bacteria if a sediment filter is not used. Carbon is not selective therefore, it will adsorb whatever is in the water solution even the solute is not considered to be a contaminant. Thus, for instance, a high concentration of calcium in the water will decrease the effectiveness of the carbon in adsorbing any benzene in the water because a lot of the carbon adsorption sites will be taken by adsorbed calcium. Therefore, the main drawback of using GAC is the expense involved.

Expenses include the continued cost of the GAC, the maintenance of the system, the analyses to detect breakthrough, and the cost of disposing or regenerating the carbon. The drums may require changing each week, every two weeks, or once a month. Typically, a 55L drum will hold 100kg of carbon. Once saturated with contaminant, the carbon must be recycled or disposed of. Disposal costs may be five times the original cost of the carbon, depending on the contaminant adsorbed. Air sparging does not bring water to the surface for treatment. It will most effectively remove those compounds that are most readily volatilized.

To be proactive in future, the monitoring of environmental aspects that may lead to the occurrence of significant impacts is a critical component of risk management. Management of these aspects through an appropriate and regular monitoring programme reduces the business risk associated with undetected releases. Through an early warning system, these risks may be reduced by means of quick and effective actions which could also reduce the environmental liability and litigations.

In addition and conclusion, ASTM (American Society for Testing and Materials) standard 1527, 1528, 1903, must be applied in all future land / property acquisition. This process has to be pursued to ensure that processes or method to investigate environmental

72 issues are conducted prior to taking over even if the land is acquired from the State. Purchasing a company or buying or leaving a property that has environmental liabilities means that the buyer acquires at least a share in the liabilities as well. The Environmental Site Assessment (ESA) must be initiated by the buyer or the seller on the request from a buyer. Although an ESA is not required by the law, it provides the buyer of a new property the assurance that future legal action will not be directed at him/ her as a result of site-pollution.

Based on ASTM Standards, ESA’s are traditionally divided into three phases i.e. Phase I which consists of gathering preliminary information to determine the probability of environmental contamination and the possible extent of environmental liabilities; Phase II involves undertaking a detailed site investigation including air/ soil/ water sampling and analysis for possible contamination identified during Phase I; Phase III takes place when certainty exists as to the intensity and extent of specific contaminants. In this phase various remedial options are explored. Hazard and risk assessments are undertaken to determine cumulative impacts of the aspects identified. Remediation planning and execution can be undertaken in this phase.

With the above ASTM Standard, the leak which was indicated to have taken place over the past 15 -20 years by the modelling process could have been detected. However since the airports and other parastatal sectors were all previously state owned, no such assessments probably took place.

Key findings of this technologies evaluation show that these remediations have been successfully applied at various sites in the United Sates of America i.e. Brownfield sites for remediation of soil contaminated with lead; a small pond at Chernobyl with uranium contamination; a riparian zone buffer strip at Amana and Tennessee for TNT removal. Degradation of organics may be limited by mass transfer i.e. desorption and mass transport of chemicals from soil particles to the aqueous phase may become the rate determining step. Therefore, remediation may require more time to achieve clean-up standards than other more costly alternatives such as excavation and treatment or disposal, especially for hydrophobic pollutants that are tightly bound to soil particles.

73 Chapter 7: List of References

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75 Gatliff, E.G. 1994: Vegetative Remediation Process Offers Advantages over Pump-and- Treat. Remediation, Summer Journal/ 1994. 343-352.

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76 Marley, M.C., D.J. Hazerbrouck., and M.T. Walsh. 1992: The Application of in Situ Air Sparging as Innovative Soils and Groundwater Remediation Technology. Ground Water Monitoring Review, Spring. 137-145

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79 Appendix 1

LNAPL Components floating on the Water table Capillary Fringe and entering a Monitoring Well

Zone of aeration (with residual oil)

. Water capillary fringe

(Enslinger e/ a/, 1994)

80 Appendix 2

Processes that occur when Hydrocarbons leak from an underground Storage Tank

Volatilization

Residual HC's LNAPL "pancake = "free product" , Water

Table Dissolved Hydrocarbons

Ground Water Flow

Impermeable strata

(Enslinger et al, 1994)

81 Appendix 3

Residual oil left in the interstices of soil

Soil or rock Mineral grains

“Free"pores space

= effective porosity

(Enslingere/a/,1994)

Appendix 4

Soil Vapour Extraction Procedure

Vapours monitored at surface With instruments or collected And taken to laboratory

Rod sections driven or augered into soil

Water table

Flexible tubing

(Enslinger et at, 1994)

Soil Retractable Vapours access to Enter hollow tube and slots Then enter flexible tubing

Point 83 Appendix 5

Pump and Treat groundwater remediation system using Carbon to adsorb Hydrocarbons

Iron

Oil — water &1 Carbon Separator drum J #2 Carbon drum

Recove Filter

(Enslinger et al, 1994)

Appendix 6 Soil Vent System

Soil Vapour System exhaust

Contaminated soil

(Enslinger et a/, 1994) 85 Appendix 7

Soil Venting of a Stockpiled Soil

Stockpiled Contaminated soil

Cutaway View

Soil Vapour /System \Exhaust

Blower Carbon drums

86 Appendix 8

Bioenhanced Soil Aeration

Addition of Frequent Fertilizer Tilling Bacteria

Soil placed on bermed liner

(Enslinger etal, 1994)

87 Appendix 9

Recoyery Well in a Cut-Off Trench and Optional Injection Gallery

Injection gallery (Optimal)

Source

Remediation Building

(Enslinger et alt

\ Submersible pump