Examensarbete vid Institutionen för geovetenskaper Degree Project at the Department of Earth Sciences

ISSN 1650-6553 Nr 334

Environmental Risk Assessment and Leachate Evolution at the Ekebyboda

Landfill Site, Uppland, Sweden Miljöriskbedömning och lakvattenutveckling

vid Ekebyboda deponi, Uppland, Sverige

Jonas Fors

INSTITUTIONEN FÖR GEOVETENSKAPER

D E P A R T M E N T O F E A R T H S C I E N C E S

Examensarbete vid Institutionen för geovetenskaper Degree Project at the Department of Earth Sciences

ISSN 1650-6553 Nr 334

Environmental Risk Assessment and Leachate Evolution at the Ekebyboda

Landfill Site, Uppland, Sweden Miljöriskbedömning och lakvattenutveckling

vid Ekebyboda deponi, Uppland, Sverige

Jonas Fors

ISSN 1650-6553 Copyright © Jonas Fors and the Department of Earth Sciences, Uppsala University Published at Department of Earth Sciences, Uppsala University (www.geo.uu.se), Uppsala, 2015

Abstract Environmental Risk Assessment and Leachate Evolution at the Ekebyboda Landfill Site, Uppland, Sweden Jonas Fors Ekebyboda is a closed landfill north west of Uppsala where the leachate water was studied to evaluate the status of the landfill for, the Uppsala environmental office. Leachate water has been measured continually for different parameters, during the period 1959-2007. The landfill differs from other landfills because of its mixed content of domestic and industrial waste. Close to the investigated area is a small number of residents with private water wells which enhances the importance of the investigation of the landfill. In this thesis, the period 1990 -2007 is the investigated with an additional measurement during 2014. Precipitation data is compared with leachate water composition, to evaluate correlations between leachate water and precipitation. Correlation between leachate water, and precipitation also gave an indication of the status of the cover on the landfill during, 2014. Due to the problematic history of Ekebyboda the aim of the thesis is to evaluate the status of the landfill and do a risk classification according to MIFO, which is a classification system for polluted sites from the Swedish Environmental Protection Agency. Measurements were made in four wells in the spring of 2014. These results showed a decline in eight analysed parameters and increase or stagnant trend for pH, NO3

- + NO2 and SO42-.

Most of the parameters have large fluctuations during the period. A field investigation is also show a non-functional culvert system with stagnant water and indications of water running in the direction of the residential area due to malfunctioning pumps. The stagnant water and problematic culvert system raised concerns for the quality of the datasets. The data analysis shows that the correlation between precipitation and leachate water was non-existent and the second covering of the landfill has reduced the amount of infiltrating water. Analysis of the leachate water and problematic management of leachate water were two major causes for a high risk classification. The MIFO classification of this landfill was set as one which is the highest possible which mainly was due to a possible risk for contamination for private water wells. Keywords: Landfill, waste disposal, leachate, environmental pollution, MIFO, Sweden, 2015 Degree Project E1 in Earth Science, 1GV025, 30 credits Supervisor: Christian Zdanowicz Department of Earth Sciences, Uppsala University, Villavägen 16, SE-752 36 Uppsala (www.geo.uu.se) ISSN 1650-6553, Examensarbete vid Institutionen för geovetenskaper, No. 334, 2015 The whole document is available at www.diva-portal.org

Populärvetenskaplig sammanfattning Miljöriskbedömning och lakvattenutveckling vid Ekebyboda deponi, Uppland, Sverige Jonas Fors Ekebyboda är en nedlagd deponi nordväst om Uppsala vars lakvatten studeras för att utvärdera deponins tillstånd på uppdrag av Miljökontoret i Uppsala. Lakvattenkvalitén från deponin har kontinuerligt blivit mätt under perioden, 1959-2007. Deponin skiljer sig från andra deponier främst på grund av sitt blandade innehåll av både hushållsavfall och industriavfall. Deponin stängdes 1970 och täcktes över i två omgångar först 1970 och senare även 1994. Ekebyboda har under den aktiva fasen orsakat en rad olika problem så som förorenade brunnar och vattendrag samt åkrar inom närliggande område. I när-heten av det undersökta området finns ett mindre antal privata hushåll med egna dricksvattenbrunnar vilket är en förhöjande faktor till att deponin undersöks. Uppsatsen fokuserar på åren 1990-2007 med en ytterligare mätning under 2014 som ligger till grund för utvärderingen av deponins rådande tillstånd. Lakvattensammansättningsmätningar under denna tidsperiod jämförs med nederbörden för att utvärdera hur stor inverkan nederbörden har på lakvatten sammansättning och uppmätta ämnen i det. Korrelationer mellan lakvattensammansättning och nederbörd gav även en indikation om deponins tillstånd idag. På grund av deponins problematiska historia ska detta området studerats men även riskklassificera enligt Naturvårdsverkets MIFO modell. MIFO står för Metod för Inventering av Förorenade Områden och är en mall för att riskklassificera förorenade områden. Fältprovtagning visade även ett ickefungerande kulvertsystem för transport av lakvatten. Stillastående vatten och problematiska lakvatten kulvertar ledde till att datasetets kvalité ifrågasätts. Korrelationen mellan nederbörden och lakvattenkvalitén var låg och en andra täckning av deponin minskade mängd infiltrerat vatten. Analysen av lakvattnet sammansättning och problematisk hantering av lakvatten var ytterligare två anledning för en hög risk-klassificering av deponin. För den fyrskaliga klassificeringen som metoden består av fick Ekebyboda den högsta riskklassificeringen som mestadels beror på en viss risk för spridning av lakvatten till när-liggande privata brunnar. Mätserien är en generell nedåtgående trend där ett flertal näringsämnen m.m. har minskat i koncentration samt att mängden infiltrerat vatten i deponin har minskat i mängd.

Nyckelord: Deponi, avfallshantering, lakvatten, miljöförorening, MIFO, Sverige, 2015 Examensarbete E1 i geovetenskap, 1GV025, 30 hp Handledare: Christian Zdanowicz Institutionen för geovetenskaper, Uppsala universitet, Villavägen 16, 752 36 Uppsala (www.geo.uu.se) ISSN 1650-6553, Examensarbete vid Institutionen för geovetenskaper, Nr 334, 2015 Hela publikationen finns tillgänglig på www.diva-portal.org

Abbreviations frequently used in the text BOD Biochemical Oxygen Demand COD Chemical Oxygen Demand IVL Svenska Miljöinstitutet, Swedish Enviromental Research Institute KEMI Kemikalieinspektionen, Swedish Chemicals Agency MIFO Methodology for Surveying of Contaminated Land MKB Miljökonsekvensbeskrivning, Environmental impact assessment PAH Polycyclic Aromatic Hydrocarbons S-EPA Swedish Environmental Protection Agency SFS Svensk författningssamling, Swedish Code of Statutes SGU Sveriges Geologiska Undersökning, Swedish Geological Survey

Table of Contents

1. Introduction and aims .......................................................................................................... 1

2. Specific work objectives ....................................................................................................... 3

3. Background ........................................................................................................................... 4

3.1. History of Ekebyboda ................................................................................................................... 4

3.2. Geography of the area .................................................................................................................. 7

3.3. Swedish environmental politics .................................................................................................... 8

3.4. Leachate from landfills ............................................................................................................... 10

3.4.1. Ageing process of landfill ................................................................................................... 10

3.4.2. Effect of precipitation on leachate ....................................................................................... 12

3.4.3. Leachate containment and treatment measures ................................................................... 13

3.5. Important physical and chemical properties of landfill leachates .............................................. 15

3.5.1 Chemical properties .............................................................................................................. 15

3.5.2 Major ions............................................................................................................................. 16

3.5.3 Ions commonly associated with organic matter ................................................................... 16

4. Data and methods ............................................................................................................... 18

4.1. MIFO environmental risk classification ..................................................................................... 18

4.2. Measurements of leachate quality .............................................................................................. 19

4.2.1. Leachate monitoring data ........................................................................................................ 19

4.2.2. Leachate sampling and measurements, April 2014 ............................................................. 20

Figure 8. Filtration equipment used prior to leachate analysis (Picture taken by the author). .............. 22

5. Results ................................................................................................................................. 23

5.1. MIFO risk level classification .................................................................................................... 23

5.2. Evolution of Ekebyboda leachate quality, 1990-2014 ............................................................... 25

5.2.1 Temporal trends .................................................................................................................... 25

5.2.3 Influence of precipitation on leachate quality ...................................................................... 29

Table of Contents (continued)

6. Discussion ............................................................................................................................ 33

6.1 Limitations and uncertainties in the leachate quality data ........................................................... 33

6.2. Temporal evolution of the landfill leachate ................................................................................ 35

6.3. Effect of precipitation variations on leachate quality ................................................................. 36

7. Conclusions ......................................................................................................................... 38

8. Acknowledgements ............................................................................................................. 40

9. References ........................................................................................................................... 41

Appendices 1 ........................................................................................................................... 45

Appendices 2 ........................................................................................................................... 47

Appendices 3 ........................................................................................................................... 48

1

1. Introduction and aims Landfill sites are a necessary infrastructure in modern societies to store and/or- treat waste

materials and substances. Environmental contamination from landfill sites is also one of the world’s

most common environmental problems. Leaching water (leachate) from a landfill site can adversely

impact the water and soil quality in the surrounding area. The environmental politics of a

country/region plays a major role in dealing with these issues, as they determine the legislation that

regulates waste handling and treatment. The environmental laws in Sweden have become significantly

stricter over the last 40 years as a result of continued development of environmental politics. This has

resulted in tighter regulations regarding landfill location and design. Older landfills usually constitute

higher environmental threats than newer landfills. In this thesis, an old (>50 years) landfill site situated

northwest of Uppsala was investigated. The Ekebyboda landfill site was originally created in 1953. It

closed for operation in the 1970s, and was completely covered in 1994.

The Aim of this thesis to evaluate Ekebybodas leachate evolution from 1990-2007 and

investigate how the precipitation is influencing the leachate. Additional measurementsis taken 2014 to

compare with precious measurements. Along with the leachate evaluation will the landfill be

evaluated and risk classified according to the MIFO methodology.

As a part of this thesis, an evaluation of the environmental risk level presented by the old

Ekebyboda landfill site was conducted following a protocol developed by the Swedish Environmental

Protection Agency (Naturvårdsverket) to classify contaminated lands. MIFO is a Swedish abbreviation

for “Method for Inventories of Contaminated Land” (Metodik för Inventering av Förorenad Områden).

This protocol is used both to make recommendations for waste management plans in a given area, and

also determine the environmental risk level for potentially contaminated land (Naturvårdsverket 2002).

This thesis also evaluated a long (1990-2007) series of measurements of leachate quality in

order to support the MIFO environmental risk level classification of the Ekebyboda landfill, but also to

obtain some insights on the biogeochemical evolution of the landfill. The leachate monitoring data

were provided by the Uppsala county environmental office, which is the authority responsible for

Ekebyboda. Various physical and chemical parameters measured in the leachate were compared with

local precipitation data provided by the meteorology group at the University of Uppsala. This was

done on order to assess the possible role of inter-seasonal /inter-annual changes in precipitation on the

leachate quality.

Conditions inside many domestic waste landfills sites follow characteristic “development

curves” over time. These curves are determined by the waste content of the landfill and the

biochemical evolution that accompanies the ageing of the waste heap. Documented development

curves are mainly based on landfills containing household waste products, which are mostly organic.

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Ekebyboda is a special case since it started as a household landfill, but changed into an industrial

waste landfill. Due to the relativity weak environmental legislations that were in place during the main

period of operation of the site (1950-1970s), there are few existing records to indicate exactly what

was dumped in the waste heap in these years. Only a rough estimation can be made. A lack of

historical information makes it difficult to compare the landfill development curve with the majority of

landfills documented in literature, which were typically used for domestic waste disposal. However

this subject is an important one to address, because old (closed) landfills are very common around

Sweden, and elsewhere in the world. New landfills will undoubtedly continue to be established in the

future. Information presented in this thesis therefore contributes to improve knowledge of the

biogeochemical evolution of landfills with mixed (domestic /industrial) composition. It also clarifies

the current environmental risk level of the Ekebyboda landfill site, which is information required by

the Uppsala county administrative board. This thesis could serve as a template for future investigations

of other old landfills in this or other regions.

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2. Specific work objectives Part of the work presented in this thesis was conducted for the Uppsala county environmental

office. This part consists of an evaluation of the current environmental risk level Ekebyboda landfill

site. The evaluation was partly done by integrating data from previous landfill leachate monitoring

reports, and from other archived documentation material about the Ekebyboda landfill. In addition, on

April 23, 2014. new measurements of current leachate quality were taken at Ekebyboda, which were

compared with the older data. Previous reports and published studies were used for interpreting the

leachate data. Based on these compiled results, a risk classification was performed for the Ekebyboda

site on a standard scale from 4 (lowest risk factor) to 1 (highest risk factor). Results were

communicated to the Uppsala county environmental office in a separate technical report and are only

summarized in the present thesis.

In the second part of the thesis, presented here, the leachate monitoring data provided by the

Uppsala county environmental office, as well as the new (2014) leachate measurements, were used to

investigate how the composition of the water leaching from the landfill changed over the period 1990-

2014. Previous case studies of landfill leachate indicate that there often is a gradual decline in the

concentrations of substances such as major ions, nutrients and trace metals in leachate, in years that

follow a landfill closure (e.g. Statom et al., 2004). These declines reflect changes in the bio-

geochemical conditions (e.g., redox state) inside the landfill over time. Redox conditions, however,

can follow different patterns over time, depending on the initial content of the waste heap (percentage

of organic matter). Redox states whether elements tend to be in in their higher (oxidized) or lower

(reduced) oxidation states, In the thesis, temporal trends observed in the leachate quality of the

Ekebyboda landfill site were evaluated, and interpreted in terms of bio-geochemical evolution of the

waste heap. Since the Ekebyboda landfill contains mixed domestic and industrial waste, the temporal

trends in selected physical and chemical properties of the leachate could differ from those observed in

landfills with domestic waste only.

Finally, the possible influence of inter-annual variations of precipitation in winter, spring, or

total annual precipitation on the concentration (by dilution) of various measured substances in the

leachate was investigated (e.g., Arora et al., 2013). This was done by comparing the time series of

leachate water quality data with precipitation records for the Uppsala region.

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3. Background

3.1. History of Ekebyboda Ekebyboda is an old disused landfill site situated northwest of Uppsala, with a total area of more

than 50 000 m2 se figure 1. Ekebyboda is situated in an area which was bought by the municipality in

1944 for the specific purpose of establishing a landfill. The location was favorable from a logistics

point of view, being only 9 km distant from the city center. Despite its closeness to Uppsala,

Ekebyboda was considered remote and isolated enough to host a landfill. Ekebyboda and the

surroundings were investigated some years later to gain better knowledge about the local geology in

order to assess if it was suitable for a landfill. Investigations by the Public Health office (Later called

Environmental office) revealed that ditching was required to drain the land, and accordingly the area

was ditched, and the drainage redirected towards Librobäck creek (Hälsovårdsnämnden VI:3). The

Ekebyboda landfill site opened in 1953 and at first was planned to receive domestic waste only.

Figure 1. Location map of the Ekebyboda landfill site. Uppsala Municipality 2014, used with permission.

But this changed in 1963 when the Uppsala waste incinerator was built. Aerial photograph of the

landfill could be seen in Figure 2. After the construction of the waste incinerator a large amount of

waste produced in Uppsala was used in the incinerator rather than being dumped directly in the

landfill. Ashes from the incinerator were then buried in the landfill instead of the waste. The

incinerator was used for a large variety of waste, and records state that at least once radioactive waste

was burned in it, and also as medical waste residues from the Pharmacia pharmaceutical company.

5

Ashes from the incinerator were dumped at Ekebyboda through the 1960s and beginning of the 1970s

(Hälsovårdsnämnden VI:4). Along with these ashes, industrial process waste, oil residues as well as

medical waste products such as needles were also disposed of at Ekeyboda. Unfortunately due to the

relatively weak environmental laws that were in place during the 1950-s 70s in Sweden, only a rough

estimation of the landfill waste content can be made, since no detailed records were kept of the

dumped materials (Hälsovårdsnämnden VI:3).

Under the active operation phase at Ekeyboda, a common waste disposal technique called the

“Bradford method” was used, which involved compacting and covering the waste heap continually

with clay as long as the waste accumulation continued. Two years after the opening of the Ekebyboda

Figure 2. Aerial photographs of Ekebyboda in 1963 (left) and in 2009 (right). Air photos from Lantmäteriet 2014, used with permission.

landfill site, the first complaint was registered regarding pollution of a nearby water well owned by a

local farmer. Hänbogård was the farm that raised these first complaints, which were soon followed by

two more from other farms. Complaints continued to come in to the health authorities through the

early 1960s, with reports of polluted wells for private households. A long series of investigations was

started to evaluate the source of the pollution. At the most affected farm, it was concluded that landfill

leachate had polluted the drinking water well, and a new well was drilled as compensation. This farm

was eventually bought by the Uppsala municipality and demolished following many problems during

which the landfill leachate resulted in poisoned farmland, pens, and a drinking water well

(Hälsovårdsnämnden VI:4).

Already by 1957, the Ekebyboda site was considered as "very unsuitable" for landfill usage by

the Swedish Geological Survey (SGU), and contamination levels of various substances in the leachate

were estimated to be 10-30 times higher than in ordinary household sewers. Therefore in the late

1950s drainage wells were installed to collect the leachate water and improve the situation around the

landfill site. These wells were drained through a culvert system and open ditch towards the south-

west. Of the total length of the landfill drainage system (2200 m), 300 m were through culverts, and

the remaining part was in an open ditch that drained into Librobäck creek (Hälsovårdsnämnden VI:4).

6

The leachate drainage system was soon proven to be inadequate, especially during times of high

precipitation, when the flow rate could reach 30-40 m3/h in the culverts. The culverts were found to be

leaking, which was thought to be one cause of the pollution of wells at nearby farms. Complaints were

also reported along Librobäck, as the water in the creek started to have a bad odor and taste. Farmers

could no longer use the creek for watering their fields or as drinking water for the animals. Further

complaints were also reported regarding the smell emanating from the drainage ditches and from the

landfill itself along with reports of problems with rats in nearby villages that came from the landfill.

Complaints were even registered from a church some kilometers away where there were problems to

perform the regular service due to the stench from the landfill (Hälsovårdsnämnden VI:3).

Leachate eventually started to accumulate north of the Ekebyboda landfill where marshes had

developed, and a drainage project was started along with new damming infrastructure to prevent the

contaminated water to cause further damage to the private wells north of the landfill. The houses there

have private water wells at depths of 14-112 m (SGU 2014). An electrical pump was installed north of

the Ekebyboda landfill to improve the pressure in the culvert system. This pump was ineffective,

however, had many breakdowns, and was eventually removed in 1990 (Hälsovårdsnämnden VI:4).

In the 1960s the Ekebyboda landfill had become a highly debated issue and was considered a

serious threat for the health of people living in the surroundings. Therefore, continued measurements

of leachate began to be performed in the early 1960s and continued thereafter over varying intervals.

The archived leachate quality data used in this thesis came from yearly monitoring measurements over

the period 1990-2007.

The covering of the Ekeyboda landfill was completed during two phases, with the first phase

taking place immediately after the landfill closure in the early 1970s. A later, improved covering

operation started in 1993 and was completed in 1994, when trees were planted on top of the landfill,

although with poor results. Today the Ekebyboda site landfill is partly overgrown by trees, and partly

an open field. The area around Ekebyboda has since the start of the landfill operations also hosted a

firearm shooting range. Since the closure of the landfill site, the shooting range has expanded into

Sweden’s biggest shooting range, and today overlays a small part of the former landfill area

(Hälsovårdsnämnden VI:3).

7

3.2. Geography of the area Uppland province is a relatively flat region, and the highest point is only 113 meters above sea

level (m asl). Surficial sediments in Uppland are mainly glacial sediments, such as glacial till,

glaciolacustrine and/glaciomarine clays, and postglacial outwash sediments which have made the

region particularly fertile for agriculture. The predominantly clay-rich soil is impermeable compared

to other sediments such as glaciofluvial sand or moraine (SNA 1996).

The local landscape in much of Uppland consists in a “mosaic” of fields, forest and lakes. The

area is mostly used for crops, cattle farming or forestry. This region is one of Sweden’s most densely

populated areas, especially around Lake Mälaren, and it hosts almost half of Sweden’s population.

Ekebyboda is situated 9 km north-west of Uppsala, within the drainage area of the Fyris river (Fig. 2).

The river, which drains a large part of Uppland, discharges into Lake Mälaren just south of Uppsala

and the lake itself drains into the Baltic Sea (SNA 1996).

The bedrock in the area consists of granite and, further north, of leptite gneiss. North of the

former Ekebyboda landfill site, the surficial geology is dominated by moraine deposits, flat or low-

relief bedrock exposures, while in low areas marshy ground and clay cover is common. South to

southwest of the landfill the subsoil is dominated by clay and moraine deposits, >5 m thick in places.

To the east and west are mostly thin layers of moraine deposits, till or flat bedrock. The soil layer in

the immediate surroundings of the former landfill site is <5 m in low laying areas, and 1 m on higher

grounds (SGU 1995).

The former Ekebyboda landfill site itself is located well outside both the outer and the inner

Uppsala water protection area and away from any local nature reserves. In the near surroundings of

Ekebyboda, the Jumkils creek runs within a small trench 300 m north of the landfill. Jumkils creek

discharges into the Fyris river which supplies water to around 200 000 people.

North of the former landfill are a few houses that have private drinking water wells. The water

in these wells was affected by the landfill leachate during the 1960s, but there is no currently reported

contamination problem (SNA 1996). According to SGU, the hydraulic conductivity of the local

bedrock is high, with an estimated volumetric flow rate between 600 and 2000 L hr-1 (SGU 1995).

Groundwater flow in the landfill area is primarily determined by the local topography,

and the dominant groundwater movement is from north to south. Under the landfill, however, the

general groundwater movement is diverted in to the west due to the groundwater extraction north of

the landfill, which maintains an artificial groundwater flow divide as long as pumping is active. The

ground water level varies depending on the season. High values of conductivity, chloride (Cl-) and

total nitrogen (N) concentration were measured in the small wetland north of Ekebyboda landfill in

1995, which indicate a slight leachate leakage from the landfill to this wetland (SGU 1995). These

high values gradually decrease northwards. Some leakage of leachate therefore appears to occur even

with a functioning groundwater pumping system, but this is diverted away by a trench and is therefore

8

not affecting the private drinking water wells nearby (SGU 1995). The leachate pumps in Ekebyboda

were removed in the 1990s due to high maintenance costs. The last sampling taken at Ekebyboda by

Uppsala environmental office were taken 2007 and 2014 was one additional sampling taken for this

thesis.

3.3. Swedish environmental politics The environmental question in Swedish politics has not always been on the political agenda.

Environmentally related questions were regulated by law in various forms since the end of 1800s. In

early times, environmental considerations were only subject to regulations if these had an obvious,

direct impact on the economy or on human health. An example is the law that regulated the hunting of

small birds, as these birds controlled populations of insects and of vermins in farmers’ fields. Other

examples are laws on the exploitation of natural resources which have existed for hundreds of years.

In contrast, there were no laws or regulations designed to benefit the natural environment for its

own sake. Historically, environmental laws were regulated following specific codes for different

categories of human activities such as farming, mining or forestry (Mahmoudi and Rubenson, 2004).

An early example of a law that was promulgated for the benefit of nature itself was the one that led to

the establishment of Swedish national parks and other protected nature reserves in 1909. Later in the

1950s, the growing conflict between natural resources exploitation activities and outdoor leisure

activities led to the Nature Conservation Act. This act regulated outdoor life, forestry and mining. This

new act created conflicts and confusion when different sets of laws contradicted each other. To resolve

these conflicts a new code of environmental laws came in effect in 1964. This code has continued to

evolve and develop since the 1960s.

As in most western countries, the start of modern environmental awareness movement

coincided with the release of the book “Silent Spring” by Rachel Carson. As a result of the public

debate that followed the publication of Carson´s book, a succession of changes were introduced to

regulate more strictly the release of man-made chemicals into the environment (Mahmoudi and

Rubenson 2004). Several chemicals of environmental concern became subject to regulations under the

new environmental protection law, which took effect in 1969. This law was continually updated with

new regulations which eventually resulted in the Environmental Code of 1999. A major reason for this

update was that environmental laws had become too numerous. This was changed and the Swedish

government collected all environmental laws under a unified environmental code. This is the most

complete environmental legislative code in Sweden so far, and it covers everything from toxic

chemicals to radiation and landfills (Mahmoudi and Rubenson, 2004).

Another important step for environmental politics in Sweden was the creation of Miljöpartiet

(the Environmental Party) in 1981, and their first entrance in the parliament in 1988 (Mp 2014). This

9

was an important step because environmental questions then became subject of parliamentary debates

on the same public level as other prominent political subjects such as jobs, housing and health care. In

1995, Sweden joined the European Union, which also introduced new obligations and laws in many

areas, including the environment (Mahmoudi and Rubenson, 2004).

The main consequence of the evolution of Swedish environmental politics described above for the

management of public landfills is that regulations for maintaining and setting up landfills have become

much stricter than they used to be. Before the 1970s, landfills could be created almost anywhere that

seemed appropriate or convenient. The content of the landfills was not regulated either, which is now

done very strictly in modern landfills. Non-sorted, old landfills (containing both domestic and

industrial waste) were particularly problematic as the mixing of different types of waste could lead to a

toxic cocktail effect. The toxicity of the leachate could also remain elevated longer than if different

waste types were not mixed.

Nowadays, the operators of a waste disposal landfill site, regardless of its size, are obligated to

secure a permission by the County Administrative Board before the site can be established. There are

different requirements from the legislations to be satisfied depending on whether the landfill is closed

or open. Dumping on a landfill site is forbidden after its closure, and legislations state that covering of

the waste heap and treatment of the landfill leachate after closure must be performed (Avfall Sverige

2012). Once closed, a landfill does not have to be reported to authorities with a few exceptions, for

example if the landfill could be affiliated to a specific industry or similar. Also, if the closed landfill is

identified as a polluted site, it becomes subject to specific rules that apply to polluted sites.

Provisions by the Swedish environmental protection agency state that all municipalities should

have plans for waste management in the future, but also plans for the management of closed landfills.

These landfills should have leachate reducing measures, and information must be kept about where old

landfills are situated. Municipalities must evaluate the status of their landfills sites. Those who have

created the landfill and caused the environmental impact are responsible for the treatment and

management of it after closure (Naturvårdsverket 2008). Environmental law considers leachate water

as a byproduct of the landfill, which should be treated in a way such that it could be released without

interfering with current regulations (Miljöbalken 1998). If the landfill was closed before 30 June 1969

when the current environmental laws came into force, the individual responsibility for the site cannot

be established. Responsibility for the landfill then becomes the municipality’s. The environmental law

states that those who conduct environmentally harmful activities are obligated to take action to prevent

harmful substances from being dispersed into the environment (Naturvårdsverket 2008).

Treatments of leachate have the goal of reducing the levels of harmful substances entering the

environment from a landfill, at a ''reasonable cost''. This implies that there are a limits to the cost and

scope of the prescribed treatment. Environmental legislation exists that are specific for landfills, but

are also embraced under the general Swedish environmental law. Before a new landfill can be

stablished, an environmental impact assessment (“Miljökonsekvensbeskrivning” or MKB), must be

10

performed. This assessment must consider all potential effects of the project for environment and

health in the affected area. This MKB is then used in the decision making-process to determine if a

project like a landfill development will take place or not (Hedlund and Kjellander 2007).

3.4. Leachate from landfills When speaking of waste disposal sites, “leaching water” (leachate) refers to the water which has

percolated through the waste heap and has neither evaporated nor been permanently absorbed in the

heap. The substances that are leached from the waste are the components (or degradation products) of

the dumped waste material which are dissolved totally or partly in the percolating water. This leachate

can then enter into the groundwater or exit into nearby streams (IVL 2000). The quality (physical and

chemical properties) of leachate can vary depending on the content of waste heap. A leachate could for

example contain varying amounts of inorganic ions, like ammonium (NH4+), nitrate (NO3

-), carbonate

(CO32-) as well as some heavy metals (Pb, Cd, Zn) if conditions are favorable to dissolve and mobilize

these substances. Oil and other insoluble organic liquids can also be transported by the leachate if the

heap contains these types of waste products. Municipal waste disposal sites typically contain a high

percentage of organic waste products, which take a long time to decompose.

3.4.1. Ageing process of landfill

Studies of landfills conducted in different regions of the world have shown that leaching water

plumes can affect the groundwater for decades or even centuries after closure of a landfill (e.g.,

Flyhammer, 1997; Statom et al. 2004; Cozzarelli et al. 2011). This is partly due to biochemical

processes that take place in the waste heap, and depends on the sustainability of these processes over

time. Landfills that contain waste with a high organic content undergo an ageing process through a

series of steps which have an impact on leachate composition. These steps are mainly determined by

bacterial degradation of the waste. The duration of this ageing process is difficult to predict due to the

number of variables that can affect the efficiency of different bacterial degradation stages. Factors

such as the water percolation rate, heat supply, and oxygen availability can all contribute to modify the

composition and toxicity of the leachate over time. The degradation of organic waste in landfills

typically goes through the following phases (Naturvårdsverket 2008):

• Phase 1: Aerobic phase (a few days to a few weeks)

• Phase 2: Acidic anaerobic phase (a few weeks to a decade)

• Phase 3: Methanogeic phase (a few months to a few hundred years)

• Phase 4: Humus generation phase (>100 years, uncertain)

In the early stages of the landfill evolution (Fig. 3), waste degradation occurs under aerobic

conditions, which generates heat and may enhance leachate production (Flyhammar, 1997). Heat

11

supplied to the landfill can increase the fermentation rate, which in turn will affect the efficiency of

aerobic/anaerobic processes in the waste. This heat supply is controlled by natural conditions such as

weather. The next stage of landfill waste degradation is anaerobic, which also tends to develop acidic

conditions inside the landfill. This evolution is usually reflected by changes in the Chemical Oxygen

Demand (COD) in the leachate which in a newly-closed landfill is above 10 000 mg L-1, but 10 years

later is typically in the order of 3000 mg L-1. This decline reflects the microbial degradation of the

organic waste which gradually consumes most of the available oxygen (Kulikowska and Klimiuk

2007). As a consequence, younger landfills tend to contain larger amounts of volatile organic acids

produced by fermentation than older landfills.

Figure 3. Degradation phases in household waste, modified from Flyhammar (1997).

Under Phase 2, the leachate typically has a low pH, high Biological Oxygen Demand (BOD)

and low COD. It contains high levels of dissolved N and hydrogen sulfide (H2S), and may also contain

high levels of dissolved metals such as Zn, Fe and Mn. Phase 3 is characterized by increasing values

of pH and BOD, high dissolved N and Cl-, but lesser metal concentrations, except for Pb. During this

phase, particularly in landfills containing much organic and biodegradable material, large amounts of

carbon dioxide (CO2) and especially methane (CH4) gas can be produced. The gas can be burned, or,

as in some modern landfills, it can be collected and be re-used as biofuel for transportation. A

requirement for this is the installation of a pipe system in the landfill. In some cases, a simpler flaring

12

system is installed to burn the CH4 and convert it to the less potent greenhouse gas CO2. Phase 4 of the

ageing process is characterized by very low biological activity, when most of the organic material has

already been degraded and what remain is non-biodegradable material. Addition of oxygen in the

landfill during this phase could however trigger a renewed increase of bacterial activity and therefore

restart the landfill ageing process. This would lower the pH, and increase the risk for metal leaching

and renewed gas production.

The waste degradation process should eventually return conditions in the waste heap to neutral

to near alkaline, at which point the landfill is no longer a threat to the surrounding environment (Salem

et al. 2008). Different waste degradation phases can also occur simultaneously at several places in a

landfill since the ageing and conditions in the heap may differ locally (Naturvårdsverket 2008). To

control the rate of the degradation process, and also reduce the production rate of contaminated

leachate, a soilcover is usually placed over landfills.

3.4.2. Effect of precipitation on leachate

The amount of precipitation that falls in different seasons / years can affect both the quality

and the quantity of leachate from a landfill site. According to Statom et al. (2004), who conducted

research on a site in Florida (USA), there is a strong relationship between leachate concentration and

rainfall. However, the effects of rainfall on leachate could take up to 30 days or more to manifest

themselves, i.e. before any resulting differences in leachate can be measured. Statom et al. (2004)

observed, for example, a positive correlation between rainfall and Cl- concentration in the leachate

while the landfill still was in use. An opposite correlation was found after the closure of the landfill,

with lower Cl- levels following rainfall. The rainwater then had a dilutive effect: once addition of new

waste in the landfill was stopped, the amount of highly soluble Cl- quickly decreased in the leachate by

dilution. However, a separate study by Huan-Jung et al. (2006) at a landfill site in Taiwan showed that

the seasonal effects of precipitation can vary for different leachate properties. In Taiwan, the spring

and summer are the rainy seasons and winter and fall the dry seasons. The authors found a clear

seasonal effect of rainfall on pH and COD in the leachate, with higher values measured in the winter,

but for other parameters like conductivity, the seasonal effect was opposite, or sometimes not

noticeable. Studying a landfill site in Slovenia, Kalčíková et al. (2011) also found that during winter,

below-freezing temperatures in the ground greatly reduced biological activity in the waste heap and

limited water percolation and leachate production.

13

3.4.3. Leachate containment and treatment measures

To reduce leaching from a closed landfill waste heap, a coating of clay can be placed over it.

In modern landfills this method is applied continuously during landfill operations to limit the exposure

of the waste to open air. Nowadays when landfill sites are being planned, consideration is given to the

local geography and hydrology. This is particularly necessary in order to meet the strict regulations

concerning the closure of landfills. One of the requirements is that the waste deposit should be located

or designed in such a way that dispersion of leachate produced during and after the operational phase

is slowed down or preferably stopped by geological barrier. The nature of this barrier can differ but

usually consists of mud or of an equally low-permeability material.

Frequently-used leachate treatment methods in modern landfills include leachate ponds,

treatments plants, and specially-created wetlands. The type of method adopted varies partly depending

on the chemical characteristics of the leachate and on geographical factors. Other considerations are

local legislation and the sustainability of the method(s). Treatments at the landfill site should be as

simple and efficient as possible to avoid buildup of high volumes of leachates in case of a temporary

failure in the process. In Sweden, there are currently ten different methods to treat landfill leachates

Naturvårdsverket 2008), which are, in decreasing order of usage frequency:

• Aerated lagoon

• Treatment plant

• Irrigated ground plant system

• Repumping to landfill

• Infiltration

• Prematurity

• Soil filter

• Chemical precipitation

• Sequencing batch reactor

• Mechanical treatment

The majority of these treatment methods demand large land surface areas to be applied, which

is a very important factor to take into consideration when modern landfills are planned. Consideration

also has to be given to the technical requirements and cost of the treatment. The aforementioned

methods all have different costs for establishment and maintenance. The selection of the right leachate

treatment method for a landfill is therefore a choice that must take many parameters into consideration

(Naturvårdsverket 2008). The environmental law also takes into account economic risks. By law, a

14

landfill-operating company should have a certain amount of money available to fulfill its

environmental obligations after landfill closure.

Older landfills often lacked most of the precautionary measures used today, and therefore

present a bigger environmental risk than the more recently created landfills. An old landfill site that

had no leachate reduction or containment measures can result in more contaminants being released

from the waste heap and transported in to the surrounding environment. In older landfills, a trench was

sometimes dug around the waste heap. However such a system is usually insufficient to contain the

leachate. Unfortunately, in such old landfill sites, little or no consideration was given to the local

hydrology, which often led to contamination issues.

In the case of the Ekeyboda landfill site, as described earlier, a system of wells had been

created around the landfill. These wells and the associated culvert system enabled the leaching water

to be pumped, prevent it from flowing in an undesired direction or seeping into the groundwater (Fig.

4). In more recently-created landfills, the leachate can be directed through a culvert system to a

treatment pond, wetland or some other, more suitable outlet system. Some undesired consequences of

this type of system are changes to the local hydrology around the landfill site, for example an inflow

of groundwater to the pumps, or the drainage of streams. These consequences can however be avoided

with some careful planning and by installing double trenches. Modern landfills have stricter criteria

for discharge of leachate then older landfills. To achieve these criteria several treatment methods have

been elaborated. Older landfills have been covered with clay to reduce the amount of water that

percolates through the waste, but this is usually the only leachate-reduction measure that has been

taken (IVL 2000).

Figure 4. Map showing the position of the Ekebyboda landfill leachate wells (red dots) and drainage culverts (black lines) in relation to the local hydrology (From information provided in Hälsovårdsnämnden VI:4).

15

3.5. Important physical and chemical properties of landfill leachates Under the Swedish environmental law, there are strict permissible limits for different physical

and chemical properties of landfill leachates. The toxicity of chemicals in leachate can be determined

by tests on algae or other small aquatic living organisms.

3.5.1 Chemical properties

pH is a measure of the ionic strength of an acidic or basic substance expressed on a logarithmic scale,

which measures the activity of hydrogen ions (H+). This is an important parameter to measure to

determine in what phase of waste degradation the landfill is. The pH strongly affects the solubility and

mobility of metals in the landfill leachate (EPA 2014, 1).

Alkalinity is a measure of the capacity of an aqueous solution to receive an addition of hydrogen ions

without increasing the pH. Hydrogen ions are created when an acid is dissolved in water. Alkalinity

therefore expresses the capacity of solutions to neutralize acidity (Naturvårdsverket 1999).

Conductivity is a measure of how well a material will lead an electrical current. In water, the amounts

of dissolved substances such as metals, nutrients and other ions largely determine how well the water

carries electricity. Major ions with a negative charge are nitrate (NO3-), sulphate (SO4

2-), and Cl-.

Major ions with a positive charge are sodium (Na+), calcium (Ca2+), magnesium (Mg2+), potassium

(K+), other metal ions (e.g., Cu2+, Fe3+). Substances such alcohols, sugars and phenols have weak or no

charge and therefore have a limited impact on conductivity. Leachate temperature will also impact its

conductivity (EPA 2014,2).

Redox is an abbreviation of reduction and oxidation that states whether elements tend to be in their

higher (oxidized) or lower (reduced) oxidation states. Oxidation reactions lead to a gain of one or

more electrons and an increase in oxidation state, while reactions that lead to a loss of free electrons

lower the oxidation state (reduced state). Redox state is dependent on pH, availability of oxygen, etc.

in water, soils and sediments, and strongly affects the mobility of contaminants in landfills. In

landfills, oxidation is commonly associated with bacterial consumption of organic matter, common

oxidizers being H2O, O2 and Cl2. Reducers are very diverse and consist of positively charged ions such

as Fe3+, Zn2+ and Na+. Under anaerobic conditions, metals can undergo a reduction from oxidation

states (III) to (II), the latter form being more mobile than the first. Reduction of SO42- is used in a

series of biogeochemical processes, for example by anaerobic bacteria which convert metal sulphates

to sulphides. Oxidation of scrap metal inside the landfill results in an easy recognizable orange rusty

coloring of leachate water (Sterner 2010).

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COD is a measurement of the amount of oxygen in complete chemical degradation of organic

substance in water. This measurements is used to determine the biological activity in a landfill

(Natuvårdsverket 2008).

3.5.2 Major ions

Magnesium (Mg2+) is a metal ion that is very abundant in the natural environment, as well as in water

due to its high solubility. Mg2+ is also one of several biologically essential metals for functions in the

human body and other organisms in nature (Jordbruksverket 2013).

Chloride (Cl-) in solution is highly oxidizing and is often used as a bleaching agent and disinfectant.

In landfills, Cl- could be derived from materials such as textiles, solvents, paint, petroleum, plastics,

medicines, etc. Due to its reactivity, Cl- typically occurs in nature in the form of compounds such as

salts (e.g., NaCl). Also because of its reactivity, it does not tend to accumulate readily in the human

body (Kemi 2010).

Potassium (K+) is an ionic salt often associated with name saltpeter. It is also one of the bio-essential

nutrients for humans, and can be found in most consumable organic products and is moderately

soluble in water which in increase with temperature (Jordbruksverket 2013).

Sodium (Na+) is another essential nutrient for humans. In high doses, Na+ can cause several heart-

related problems with humans. In landfills, Na+ exists in large amounts and is derived from materials

such as, soap, textiles, oils, chemicals and paper (Landskapsgrundammen 2014).

Sulphate (SO42-) is highly soluble in water. H2SO4 is one of the most utilized acids in industry today

for numerous purposes, including in electrolytic batteries. It is also commonly produced by

combustion of organic fuels such as coal, oil and gas. SO42- could have a harmful impact on humans

and nature especially in combination with other chemical compounds. Consequences for humans and

nature are therefore diverse (Naturvårdsverket 2006).

3.5.3 Ions commonly associated with organic matter

Nitrate (NO3-) and nitrite (NO2

-) these substances are essential nutrients for aquatic life and

biological production. The main consequence of NO2-and NO3

- pollution is the eutrophication effect in

aquatic systems, which lead to algal blooms and oxygen deficiency (hypoxia). Sources of NO2-and

NO3- in landfills are many and diverse and may include fertilizers, untreated sewage explosives,

toothpaste, pesticides and laundry detergents (Naturvårdsverket 2014).

17

Ammonium (NH₄⁺) is the ion formed when NH3 is dissolved in water and is a weak acid. NH3 is

produced by degrading organic matter. It was long used as a fertilizer and can also be found in

explosives and many other products (KEMI 2011).

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4. Data and methods

4.1. MIFO environmental risk classification

The classification of a landfill in terms of environmental risk level is a decision that must take

into account both the physical and human geography of the landfill area, and the potential for

contaminants to spread into nature and to inhabited sites. Specifically, the risk being investigated is

that of contaminants from the landfill infiltrating buildings, drinking water wells, soils used for food

production etc., such that they could constitute a threat to human health. The types of substances

leaching from the landfill and their chemical properties are therefore parameters which are essential to

take into consideration in the risk classification. Phase 1 of the MIFO protocol lays the foundation for

a possible phase 2, in which more comprehensive environmental sampling and measurements are

performed. The MIFO phase 1 mainly evaluates information about previous landfill history and related

processes. This information can be obtained through interviews with persons having insight on the

actual site history, or from reports, protocols, maps, etc. (Naturvårdsverket, 2002).

In the case of Ekebyboda, there is limited information on the history of the landfill (see previous

sections). The existing documentation is limited to few reports from SGU and the Uppsala county

environmental office. However, leachate quality measurements from the landfill were documented

from approximately the time of closing of the landfill in the 1970s, until 2007, when the last

measurements were performed (Naturvårdsverket, 2002). The MIFO risk assessment for Ekebyboda

which was performed as part of this thesis was based largely on archived data from the leachate

quality monitoring program over the period 1990-2007, supplement by new field sampling and

measurements performed in April 2014. These compiled measurements, together with background

information, formed the basis for the risk level classification. Published scientific case studies on the

evolution of landfill leachates, as well as literature from the Swedish Environmental Protection

Agency (Naturvårdsverket) provided an additional scientific foundation.

The MIFO system classifies levels of environmental risk on a scale of one to four (one being the

highest) using a two-axis grid, were the risk of spreading (migration) of pollutants is one of the axes,

and other factors such as the toxicity of substances, the present contamination level, and the sensitivity

and protection value of the investigated site define the other axis (Fig. 5). The estimated values of

these different criteria for an investigated site are then positioned in this space. The assignment of an

environmental risk level class is based on where the different factors are concentrated with respect to

the main criteria defining the axes of evaluation (Naturvårdsverket 2002).

19

Figure 5. MIFO risk classification diagram (Naturvårdsverket 2002).

4.2. Measurements of leachate quality 4.2.1. Leachate monitoring data

Over the period 1990-2007, the Uppsala county environmental office regularly monitored the

quality of leachate from the Ekebyboda landfill, and 33 physical and chemical parameters were

measured in samples, including selected metals, major ions, and nutrients. This was done to monitor

the chemical evolution of the landfill leachate. Samples were collected from four wells situated around

the landfill, once a year, typically in May, but somewhat later duringa few years (four times in June,

and once in August). The analyses were performed by different laboratories under contract with the

environmental office, because no adequate analytical facilities existed within the services of the

Uppsala municipality. Unfortunately, few or no details on how the various laboratories performed

their analyses were recorded or saved. For the field sampling conducted in 2014 (see below), the

samples were sent to ALS Scandinavia for analysis, and this laboratory provided all details on

procedures. In this thesis, 11 parameters in leachate were considered. For the MIFO categorization of

the landfill has additional measurements been considered for Pb, Cu, Zn and Cd for year 2014. These

parameters is used to determine the right MIFO risk classification. Archived printed reports obtained

from the Uppsala county environmental office were digitized, and the data compiled into a single

computer spreadsheet program for analysis. Because water quality analysis has been typically

performed by the same standard methods over the past decade, it was assumed, in this work, that the

analysis methods specified by ALS Scandinavia for the 2014 samples (Table 1) were comparable, in

terms of precision, to those used in the earlier period of monitoring (1990-2007). Correlation between

analysed parameters and precipitation is displayed in a diagram. Pairwise correlation has been

20

calculated using the Pearson’s product-movement correlation. This method is a way of calculating the

linear correlation between two variables and display the correlation in percentage were -1 is a negative

correlation and 0 is no correlation and 1 is a good positive correlation (Alm and Britton 2008).

Table 1. Methods and precision of leachate quality analyses performed by ALS Scandinavia. ICP-AES = Inductively Coupled Plasma Atomic Emission Spectrometry; ICP-SFMS = Inductively Coupled Plasma Sector Field Mass Spectrometry; AFS = Atomic Fluorescence Spectrometry; CDM = Conductivity meter; ABU93 = Radiometer. 2σ = Uncertainty of the analysis.

4.2.2. Leachate sampling and measurements, April 2014

Water samples were collected at Ekebyboda during the spring of 2014 and analyzed to reveal

the current quality of the landfill leachate and to complement the monitoring data from 1990-2007

provided by the Uppsala County environmental office. Field sampling at Ekebyboda was performed

on April 23, 2014, between 09:00 to 10:30, under sunny weather conditions with air temperature

around 10 °C. The four wells were visited in the following order: A3, A2, A1 and A1-4 (Fig. 4). Well

A3 was the first to be sampled. The lid of the well showed no signs of previous (recent) opening.

Organic debris such as twigs, leafs and several dead rats were found floating in the well. The water

seemed to be stagnant and no motion or mixing could be seen or heard. On top of the well is a small

ventilation pipe which could be a possible entrance for the rats. In Fig. 6a, a black hole can been seen

at the bottom of well. This hole is covered with a metal lid which protects the lower well chamber

where pumps were situated before. The metal lid was lifted and water samples were taken at

approximately 150 cm depth in this lower chamber. The water did not smell nor had any remarkable

coloration. Well number A1 (Fig. 6b) has a similar design to well A3 but is slightly larger. The water

in well A1 was also clear with no distinctive smell. There was very little organic debris in this well

21

compared to other wells. The metal lid in the bottom did not cover the lower chamber, and the water

sample was taken in the deeper part of the well at an approximate depth of 0.5 m. Well A2 contained

running water with a few twigs and leafs in it, and the water had a slightly dark color, but no

distinctive smell.

Figure 6: Pictures showing Ekebyboda leachate well A3 (left) and A1 (right). Pictures taken by the author.

In contrast to A1, A2 and A3, the water in well A1-4 (Fig. 7) had a pronounced yellow/orange

color, and a strong and distinctive smell of oil or diesel fuel. The smell of oil and diesel was so strong

that it could be detected a couple of meters from the well. A sediment deposit in the well was

approximately 5-8 cm deep, and the water samples were taken close to the outlet of the well were the

three pipes join into one. The depth of the moving water was barely 0.1 m.

Figure 7. Picture showing Ekebyboda leachate well A1-4. Pictures taken by the author.

In each of the sampled drainage wells, three separate water samples were taken, and the water

in one of the bottles was later filtered and analyzed for a suite of metals. The filtration was done in a

laboratory at the Department for Earth Sciences. Fig. 8 shows the filtration apparatus that was

employed. The filters used had a diameter of 0.45 µm and were made of polyethersulfone. The filtered

22

water was stored in acid-cleaned bottles, which were then sent to the ALS Analytica laboratory in

Täby for analysis.

Figure 8. Filtration equipment used prior to leachate analysis (Picture taken by the author).

23

5. Results

Results of the work conducted in this thesis consist in two parts. The first part was the actual

risk level characterization of the Ekebyboda landfill, conducted site in accordance with the MIFO

protocol. This evaluation was presented in a separate report to the Uppsala County environmental

office, and is only summarized below (section 5.1). The second part of the results, which occupy the

remainder of this chapter, concerns trends in landfill leachate quality obtained by monitoring over the

period 1990-2007, which were interpreted in terms of biogeochemical evolution of the landfill, and

possible correlations with precipitation (section 5.2).

5.1. MIFO risk level classification

The MIFO evaluation protocol consists in several parts, which together provide the foundations

for the environmental risk level classification, as summarized in Fig. 10.

Figure 10. MIFO classification of the Ekebyboda landfill site (Naturvådsverket 2014)

24

The leachate itself, which was sampled in wells, is regarded as contaminated groundwater. In

the case of Ekebyboda, the category “risk of contamination to buildings” is not represented because

there are no affected buildings in the immediate vicinity of the landfill site.

Different landscape elements (ground, surface water, sediments, etc.) are considered during

the evaluation, which are represented by horizontal lines with letters on the figure. The point where

these lines intersect the vertical axis reflects the estimated risk of contaminant dispersion (slight to

very great) for each particular landscape element. Many different landscape elements can play a role in

an assessment, but they will only appear on the MIFO classification diagram if they are represented,

and considered relevant, at the contaminated site being evaluated site. The diamond symbols with

letters (H, C, S, P) on the horizontal lines represent different parameters (e.g., toxicity, contamination

level) which should be taken into consideration in each landscape element. These symbols are

positioned along the lines according to the perceived risk level (slight to very great) associated with

each parameter and landscape element. When each relevant landscape element and parameter has been

assessed and plotted on the MIFO diagram, the field that holds the most diamond symbols indicates

the suggested comprehensive risk classification level, from 4 (lowest) to 1 (highest). A landfill is

considered in the MIFO protocol to be ''land'', as opposed to a construction, and is evaluated as such.

Determination of the toxicity (H; ''hazard assessment'') and contamination level (C) of the

landfill leachate should be based on the identification and measurement of as many of the

contaminants present as possible. Types of pollutants that are, according to the MIFO protocol,

classified as ''high risk'' for toxicity are metals such as Cu, Ni and Al, and various types of oil, oil

residues and other petroleum-derived products. Pollutants regarded as presenting ''very high risk'' in

terms of toxicity are As, Pb, Cd, Hg, Cr, Na (metal form), and persistent organic pollutants such as

polycyclic aromatic hydrocarbons (PAHs), chlorinated solvents, and chlorophenols. Identification and

measurement of these pollutants are an important part of the MIFO process for the risk classification

of the landfill. In the most recent Ekebyboda leachate sample analyzed, taken on April 23, 2014,

concentrations of several trace metals were measured that correspond to the following MIFO risk

categories for ground water: slight (Pb), moderate (Cu), great (Zn) and very great (Cd). However, the

comprehensive MIFO classification also took into consideration the strong likelihood that other,

unmeasured chemical substances, such as oil residues and solvents, may be present at high levels in

the leachate as well, as suggested by the strong smell of petrol/oil detected in well A1-4. Accordingly,

the estimated risk classes for toxicity and for contamination level in groundwater were considered to

be 2 (great) and 1 (very great), respectively.

The risk level for protective value (P; the level of environmental protection required) that

applies to ground and groundwater at Ekebyboda was rated as 4 (low), because the land and water in

the landfill area and its surroundings do not have any special status (e.g., a natural reserve) and are not

protected by any special environmental law(s). Water-courses near Ekeyboda such as Jumkilsån is

more than 1 km away from the landfill leachate water is therefore considered to have minor affect on

25

it. However, the risk level for ''human sensitivity to exposure'' (S) around Ekebyboda was rated as 1

(very great) because there are several persons in the area who use drinking water from local wells.

Leachate from the landfill could also affect nearby farmland and cultivated fields. Previous reports

documenting polluted wells, the displacement of farms, contamination of streams, as well as estimates

of leachate volumes produced when the landfill was in operation, also contributed to assigning a

sensitivity risk level classification 1 to Ekebyboda. Although the landfill has been closed for almost 40

years, these documents contribute to a picture of a landfill with a long history of severe environmental

impacts which must be taken into account when evaluating the present-day risk level. The shooting

range near Ekebyboda is not, by itself, a sensitive area, but it attracts many people to the areas affected

(or potentially affected) by the landfill.

With regards to the migration potential of contaminants from the landfill (vertical axis on the

MIFO diagram), this was rated as a ''very great'' risk for groundwater. The culvert system around

Ekebyboda was set up to transport leachate from the landfill away from the groundwater table and

from nearby wells and towards the south of the landfill, and also, by dilution, to reduce the threat of

leachate contamination in surface waters and soils. However, as discussed earlier, the wells

experienced frequent problems with groundwater pumps for a long time, which resulted in their

removal. There has been no active pumping in these wells since the beginning of the 1990s, and

consequently risks of leachate spreading away from the landfill have increased. Interruption of

pumping at the northern part of the landfill led to the diversion of the leachate flow towards the north,

rather than the south, which resulted, by 1995, in the formation of a small wetland with anomalously

elevated water conductivity (total solutes), and high levels of chloride (Cl-) and total nitrogen (N).

Measurements of Cl- and nutrients done by SGU in 1995 revealed continued minor leaching from the

landfill towards the north and into the wetland. The leachate sampling performed on April 23 2014

also established that wells A1 and A3 contained large amounts of stagnant water. The efficiency of

leachate transport in the culverts near these wells is therefore questionable. Wells A2 and A1-4,

however, showed that a certain amount of active flow exists in the nearby part of the culvert system.

The risk for leachate spreading to nearby water wells north of the landfill is a realistic threat which

should be taken seriously. The MIFO risk classification level of 1 for the Ekebyboda could possibly be

reduced to 2 if the current state of the culvert system and the volume of leachate flowing northward of

the site could be clarified.

5.2. Evolution of Ekebyboda leachate quality, 1990-2014

5.2.1 Temporal trends

As described earlier, most of the landfill leachate quality data used in the thesis are based on

sampling conducted by the Uppsala County environmental office as part of a monitoring program of

the Ekebyboda landfill which ended in 2007. Additional measurements of leachate were performed in

26

Parameter Slope Units R2 F

Cond. -11 mS m -1 a -1 0.6 < 0.01pH < 0.1 a -1 0.3 0.002Alk -19 mg L -1 a -1 0.2 0.008Mg2+ -1 mg L -1 a -2 0.5 < 0.01Cl- -12 mg L -1 a -3 0.4 < 0.01Na+ -11 mg L -1 a -4 0.6 < 0.01K+ -4 mg L -1 a -5 0.7 < 0.01NO3-+NO2- 0 mg L -1 a -6 0.0 0.48SO4

2- 0 mg L -1 a -7 0.0 0.89

NH4+ -3 mg L -1 a -8 0.3 0.02

COD -9 mg L -1 a -9 0.6 < 0.01

the spring of 2014 to compare present-day conditions with those during the monitoring period. The

data consist of measurements of leachate physical and chemical properties from four wells around the

landfill over the period 1990-2014. In order to investigate temporal trends in the leachate quality over

the period 1990-2014, data from these wells were averaged for each individual year. For several

chemical properties, the reported values for individual wells were often been below analytical

detection limits (D.L.). This made it impossible to calculate meaningful averages for certain years or

temporal trends in the data for these properties. If leachate quality data were reported with different

precisions in different years, the most conservative (lowest) precision was used in the trend analysis.

Chemical properties for which trends could not be determined due to too many values being < D.L.

were Al, Cd, Hg, Zn and PO43-. Properties for which trends could be analyzed were conductivity, pH,

alkalinity, Cl-, K+, Na+, Mg2+, NO3-+NO2

-, NH4+, SO4

2- and the chemical oxygen demand (COD).

Temporal trends in the leachate quality data were quantified using three statistical measures: (1)

The actual value of the linear trend (slope), obtained by least-squares linear regression. The coefficient

of determination R2, which quantifies how well the linear regression model accounts for the variance

in the data. How well the data fits to the slope. F statistic, which is a measurement of the significance

of the R2. This is an estimation how the uncertainty of a data series described in percentage. In this

analysis, the significance level for the F statistic was 0.05 (95 % confidence level). Results of the trend

analysis are summarized in Table 2. Of the 11 properties investigated in the Ekeyboda leachate, 9 of

them (conductivity, alkalinity, Cl-, K+, Na+, Mg2+, NO3-+NO2

- and NH4+) show an overall decreasing

trend from 1990 to 2014, while pH and SO42- show an opposite trend over this same period. However,

because of the large interannual variability in the data, only 8 properties have linear trends that can be

considered statistically significant at the 95 % level of confidence.

Table 2. Linear trends, coefficients of determination (R2) and corresponding p-values of Fisher's F-statistic

(significance) for physical and chemical properties measured in Ekebyboda landfill leachate over the years 1990-

2005, 2007 and 2014.

27

Alkalinity has the steepest overall declining trend of all (-19 mg L-1 a-1) but this trend is only

marginally meaningful (R2 = 0.18; p = 0.08). A general decline in alkalinity should normally

correspond to an overall increase in pH, since alkalinity is an indicator of the ability of the leachate to

neutralize acidity. However pH shows a weak positive trend (< 0.1 a-1) and an increase of variability

between the different wells over time. A decrease in alkalinity accompanied by a rising pH is,

however, an expected result in landfills that are moving into the humus generation phase of their

evolution. Remarkably, the latest measurements of alkalinity performed at Ekebyboda in spring 2014

show an increase relative to 2007 (the year of the most recent previous measurement) that is as large

as was the decline over the period 1999-2005. Like alkalinity, conductivity shows a steep declining

trend (-11 mS cm-1 a-1), which is one of the strongest and most significant ones (R2 = 0.6; p < 0.01)

among the variables. This trend is also expected if the landfill evolution is moving into the humus

generation phase. COD shows an equally strong and statistically significant negative trend of -9 mg L-

1 a-1 (R2 = 0.6; p < 0.01). This decline in COD suggests an evolution towards conditions inside the

landfill with lesser and lesser biological activity and organic decomposition.

The four major ions K+, Cl-, Na+ and Mg2+ all show similar temporal patterns with decreasing,

significant trends (0.4 ≤ R2 ≤ 0.7; p < 0.01) in the leachate over the period of monitoring. The steepest

trends are for Cl- and Na+: -12 and -11 mg L-1 a-1, respectively. Small increases were seen in the mean

levels of some of these ions between 2007 and 2014, but these increases were very small compared to

the overall decline during the whole monitoring period. Of the few nutrients that were examined, only

NH4+ had a statistically significant decline in the leachate over time (-3 mg L-1 a-1). Other nutrients like

NO3-+NO2

- and NH4+ showed interannual fluctuations but no significantly meaningful linear trend. The

same was true for SO42-.

5.2.2 Pairwise correlations

Pairwise values of the Pearson product-moment correlation coefficient (R) were calculated from

the different leachate quality properties in order to highlight the most significant relationships between

these parameters. Results are presented in Table 3. Red figures denote a relatively high degree of

linear correlation (│R│ ≥ 0.40), green figures indicate moderate linear correlations (0.40 >│R│ ≥

0.20) and blue figures a low degree of linear correlation (│R│< 0.20). The strongest and most

significant positive correlations observed (R ≥ 0.80) were those between major ions (Mg2+, Cl-, Na+,

K+) or between conductivity and some of these ionic species (e.g., Na+). Weaker, but significantly

positive correlations (0.60 ≥ R > 0.80; p < 0.01) were also found between conductivity, alkalinity,

COD, K+ and NH4+. Variations in the pH of the leachate showed significant negative correlations with

conductivity, alkalinity as well as with most ionic species (-0.53 ≥ R ≥ -0.41; p < 0.01), except for

28

SO42- and NO3

-+NO2- (no significant correlation). COD is strongly and positively correlated with most

other parameters (0.48 ≥ R ≥ 0.90; p < 0.01) with the notable exception of pH (R = -0.41) and of SO42-

(R = -0.10), and SO42- has the lower overall correlations to other physical or chemical properties,

except with alkalinity (R = -0.41; p < 0.01).

Table 3. Pairwise Pearson product-moment correlation coefficients (R) between leachate properties, and with

seasonal or total precipitation in the Uppsala area (SMHI data).

29

5.2.3 Influence of precipitation on leachate quality

The conditions inside a landfill, and the amount and quality of leachate that issues from it, can

be influenced by the regional climate, and the covering of a landfill is a measure designed to reduce

this influence. Covering reduces the availability of oxygen and limits water infiltration through the

waste heap. Infiltration is rarely completely stopped but can be significantly reduced. In this study, the

possible influence of seasonal (spring, winter) and total annual precipitation on the quality of leachate

issuing from Ekebyboda was investigated by examining linear correlations between interannual

variations of leachate properties and seasonal or annual precipitation amounts. Mean seasonal

precipitation amounts were calculated for winter (December, January and February) and spring

(March, April, May) only, as these are the wettest seasons and should have the largest impact on

leachate measurements made in the springtime.

Results are summarized in the last three columns of Table 3. As before, red figures denote a

relatively high degree of correlation (│R│ ≥ 0.4), green figures indicate moderate correlations

(0.4>│R│ ≥ 0.2) and blue figures a low degree of correlation (│R│ < 0.2). Overall, interannual

variations of seasonal or total precipitation are poorly correlated with variations in the leachate

properties, and only account for less than 20 % of the variance in the leachate data. Only two strong

anti-correlations were observed, one between spring precipitation and NO3-+NO2

- (R = -0.41) and one

between winter precipitation and Cl- (R = -0.40). Some moderate positive correlations were also found

between total annual precipitation and NO3-+NO2

-, SO42- and NH4

+.

Plots of the interannual variations of these variables for the Ekebybody leachate over the

monitoring period 1990-2014 are presented on Fig. 11 to 21. Error bars on these plots indicate the

standard deviation for each parameter during a specific year based on the four Ekebyboda wells and

the eleven analysed parameters.

30

Figure 11 and 12. Variations of the mean conductivity (blue) and pH (Blue) in leachate from the Ekebyboda landfill, compared with total annual precipitation in Uppsala (orange) over the period 1990-2014. Vertical bars for the conductivity and pH give the standard deviation of measured values in different wells. The blue stippled line is a least-squares linear model fitted to the data.

Figure 13 and 14. Variations of the mean Alkalinity (blue) and Mg2+ (Blue) in leachate from the Ekebyboda landfill, compared with total spring precipitation in Uppsala (orange) over the period 1990-2014. Vertical bars for the Alkalinity and Mg2+ give the standard deviation of measured values in different wells. The blue stippled line is a least-squares linear model fitted to the data.

31

Figure 15 and 16. Variations of the mean Cl- (blue) and Na+ (Blue) in leachate from the Ekebyboda landfill, compared with total annual precipitation in Uppsala (orange) over the period 1990-2014. Vertical bars for the Cl-

and Na+ give the standard deviation of measured values in different wells. The blue stippled line is a least-squares linear model fitted to the data.

.

Figure 17 and 18. Variations of the mean K+ (blue) and mean NO3- + NO2 (Blue) in leachate from the

Ekebyboda landfill, compared with total annual precipitation in Uppsala (orange) over the period 1990-2014. Vertical bars for the K+ and NO3

- + NO2 give the standard deviation of measured values in different wells. The blue stippled line is a least-squares linear model fitted to the data.

32

Figure 19 and 20. Variations of the mean SO42-

(blue) and NH₄⁺ (Blue) in leachate from the Ekebyboda landfill, compared with total annual precipitation in Uppsala (orange) over the period 1990-2014. Vertical bars for the SO4

2- and NH₄⁺ give the standard deviation of measured values in different wells. The blue stippled line is a least-squares linear model fitted to the data.

Figure 21. Variations of the mean COD (blue) in leachate from the Ekebyboda landfill, compared with total annual precipitation in Uppsala (orange) over the period 1990-2014. Vertical bars for the NH₄⁺ give the standard deviation of measured values in different wells. The blue stippled line is a least-squares linear model fitted to the data.

33

6. Discussion

6.1 Limitations and uncertainties in the leachate quality data The leachate quality data from Ekebyboda used in this thesis were obtained as part of a

programme initiated by the Swedish Environmental Protection Agency to monitor conditions of old

landfills across Sweden. Under law, the Uppsala county environmental office is obligated to monitor

landfill sites such as Ekebyboda for 30 year after their closure. Leachate sampling and testing at

Ekebyboda was performed approximately once a year between 1990 and 2007, following prescribed

guidelines. These guidelines specify that measurements have to be taken in the same wells every year,

under the same conditions, at the same time of the year, and that samples must be analysed by certified

water quality labs. However, important uncertainties in the dataset exist because these guidelines were

not always followed.

First, the monitoring guidelines state that sampling should be performed every year in May,

which was done until 2002, but afterwards the sampling was performed in June (2003-2006) and in

August (2007). Annual sampling was then interrupted until 2014. These changes introduced

uncertainties in the calculation of temporal trends in the leachate quality data, and also likely affected

the reliability of correlations with precipitation data for years after 2003. For example, the limited

correlation strength (R) between certain leachate properties (e.g., conductivity) and precipitation could

simply be due to the fact that measurements were taken in different months over the years. Most

published studies on leachate evolution in landfills use monitoring data for a relatively short number

of years, but with multiple measurements taken during that year. For example, in studies performed at

a landfill site in France by Khattabi et al. (2002), leachate quality measurements were performed

hourly, monthly and annually. Sampling to detect long-term trends was performed annually over five

years, and in order to detect shorter-term variations, sampling was also conducted hourly and monthly

over one year. In a related study in Slovenia, Kalčíková et al. (2011) analysed seasonal variations in

municipal landfill leachate quality by collecting samples at different monthly intervals during over a

three year period. The situation with Ekebyboda is different as the data series span over 14 years, but

with only one measurement occasion per year. This makes it harder to resolve possible seasonal

variations in the leachate quality, and also make it difficult to compare results of this study with those

of others.

Secondly, the sampling of leachate at Ekebyboda suffered from some problematic factors that

could affect the quality of measurements. During the sampling performed in April 2014, it was

discovered that flow conditions in some wells had changed since prior sampling. Specifically, wells

A1 and A3 did not show any visible movement of water. How long the water had been stagnant in

these wells can’t be specified, possibly since the last sampling in 2007, or even longer. Wells A1 and

A3 are the deepest wells and there leachate pipes is at a depth of at least 5 m in a lower chamber.

34

Leachate water in these wells did not have any visible movement and could therefore be diluted by

groundwater (Hälsovårdsnämnden VI:4). Wells A2 and A1-4 are smaller than the others and showed a

steady flow of water in 2014. Because of this water movement, analytical results of leachate samples

taken from these wells are probably more reliable than those from wells A1 and A3.

As mentioned earlier, groundwater pumps that were initially installed in the wells broke down

several times, and were eventually removed due to their high maintenance cost. This resulted in an

ineffective flow of leachate water in the culvert drainage system. According to an investigation by

SGU, removing the pump created a new separation in the groundwater flow under the landfill, with

water under the, northern part flowing northwards, and water under the southern part flowing

southwards (SGU 1995). This implies that water from the northern wells A1 and A2 may not reach the

collecting well A1-4 in the southern part of the landfill. The culvert system around the landfill site

presently shows a constant flow through of water in all inspection wells, but the status of the pipes

themselves is unknown. Further investigations are needed to establish their condition and define the

flow rate of water through them. Leakage from the culvert system is also likely since small marshes

around the landfill were sampled in 1995 and found to have anomalously high conductivity, Cl-, and

total N (SGU, 1995). Taking all these factors into consideration, is it likely that variations in the flow

rate between and through different wells over the years could account for some of the variance

observed in the leachate quality measurements.

Another difficulty arises from the fact that from 1990 to 2007, Ekebyboda leachate samples

were analyzed by different laboratories, possibly with different methods and/or instruments, but these

differences in protocol were not been properly documented. Changes in labs/methods have resulted in

data series that have different detection limits (DL) for the same parameters from year to year. Since

the DL varied between different years, in this thesis only the most conservative (highest) values were

adopted. In addition, for some leachate properties the analytical results provided by the various

contracted assay laboratories were reported with different precisions (number of significant digits) in

different years. For some variables, for example the concentration of trace metals (Al, Cd, Hg, Pb, Zn)

or PO43- in the leachate, the data contained so many disparities (imprecise or exceedingly different

measurements in separate years) that these data had to be excluded from any trend or correlation

analyses.

There is also a large amount of variability in the leachate quality data between different wells.

For trend and correlation analyses, the mean values of different parameters in each year were used for

convenience. While the derived trends and correlation indices may give an overall good indication of

the general evolution trend in the landfill leachate, they do not take into consideration the fact that

some wells (like A 1-4) often had much higher solute concentrations than others. These discrepancies

of leachate quality between wells may be related to the fact that the waste distribution and composition

in the landfill was not homogenous, as shown in old Uppsala municipality reports and other

documents. Using a mean value of leachate quality variables in the four wells hides the highest and

35

lowest values of these variables and do not reflect the fluctuations between individual wells. The

highest values (for example, of conductivity) or lowest values (for example, of pH), are, however,

important to take into consideration for the MIFO risk level classification since a particularly high (or

low) value for one important variable could make the difference between a risk classification level of 1

or a level of 2.

6.2. Temporal evolution of the landfill leachate The Ekebyboda landfill site is a particularly interesting case study because it is a very mixed

landfill. It was used for dumping a very wide range of both industrial and domestic waste. It is

therefore unlikely that the landfill will follow a leachate evolution curve that is typical of household

waste landfills. For some leachate properties, such as for most major ions, trends observed at

Ekebyboda are comparable to those reported for other monitored landfill sites (e.g., Statom et al.

2004; Kulikowska and Klimiuk, 2008). In contrast to other sites, however, the leachate pH only shows

a very minor net increase over time, while SO42- seems to vary with an approximate pseudo-cycle of 7

years.

The initial aerobic phase at Ekebyboda probably ended when the landfill was first closed and

covered in the 1970s, since this phase requires a constant supply of organic matter and oxygen to be

maintained. The aerobic phase is normally continued by an anaerobic acidic phase. The trend for COD

after 1990 indicates that there was continued biological activity in the landfill after the first

(inadequate) coating had been applied in the 1970s, but this activity gradually decreased after the

second coating was installed in 1993-1994, as the amount of biodegradable material in the waste heap

declined. Statom et al. (2004) observed a similar trend in both COD and total organic carbon (TOC) of

leachate in a closed municipal waste landfill site in Florida, USA. After the closure of a landfill, the

fluctuating pattern of COD measured from leachate is expected to decrease in amplitude. Evidence of

the efficiency of the second cover at Ekebyboda is shown by the fact that most major ion

concentrations also show a declining trend after 1994. However other monitored properties of the

leachate, such as pH, SO42- and NO3

-+NO2-, show little or no trend. Statom et al. (2004) also reported

variable trends in leachate properties in the Florida landfill, and they attributed part of these disparities

to the effect of rainfall and water infiltration rates. They suggested that minor gaps in the cover or

lining of the landfill could allow for continued oxygenation of the heap. This is less likely to have

happened at Ekebyboda since it was coated twice, however. Another possible explanation for some of

the odd variations, or the lack of clear trends, observed in the Ekebyboda leachate quality, is the fact

that much of the landfill contains industrial waste which is likely made of poorly or non-biodegradable

materials, and such materials continue to contribute various chemical substances to the leachate

composition for a long time after the closure of the landfill.

36

Important changes in redox conditions certainly occurred inside the landfill after its closure. The

decrease in COD indicates a gradual exhaustion of available oxygen in the heap. An apparent

pronounced drop in NO3-+NO2 after 2004 to < 5 mg L-1 suggests that by that year, O2 levels may have

declined to a point where denitrification started to take place in the waste heap (e.g., Cozzarelli et al.

2011). However, the lack of a clear trend in SO42- in the leachate also indicates that significant

reduction of sulfate has probably not begun to take place in the heap. A gradual transition to

predominantly reducing conditions in the waste heap could account for the present (2014) levels of

some dissolved metals in the leachate, such as Zn or Cd, which are considered high according to the

Canadian water quality criteria used in the MIFO categorization (Table 4). Reducing, acidic conditions

tend to favor the mobility of metals in the aqueous phase. Unfortunately, temporal trends for the

metals could not be established due to the discrepancies in the analytical methods and reported

precisions in the monitoring data over the years.

Table 4. Comparison between the highest Pb, Cu, Zn and Cd concentrations measured in the Ekebyboda leachate in April 2014 (left column), and Canadian water quality guidelines used in the MIFO risk classification protocol for landfills (central columns).

Highest pollution level 2014 Low Moderate High Very High UnitsPb = 0.195 < 1 1-3. 3-10. >10 µg/LCu = 6.47 < 4 4-12. 12-40. >40 µg/LZn = 256 < 30 30-90 90-300. >300 µg/LCd = 0.641 > 0.01 0.01-0.03 0.03-0.1 > 0.1 µg/L

A possibility also exists that the evolution of conditions inside the waste heap, and of the

leachate quality, was perturbed when the second cover was installed in the landfill in 1993-94.

Disturbance and mixing in the upper part of the landfill caused by heavy machinery during installation

of the cover could have led to addition of oxygen inside the heap. This added oxygen could then have

restarted the degradation process, and increase the release of some substances in the leachate again,

while other parts of the landfill, unaffected by the machinery, would have continued to evolve towards

an anaerobic phase. This again points out the fact that the landfill is very heterogeneous in

composition, which is reflected in the large differences in leachate quality observed between the

different monitoring wells.

6.3. Effect of precipitation variations on leachate quality The correlation results presented in Table 3 suggest that seasonal to interannual variations in

precipitation have relatively little impact on the long-term variations in the leachate quality parameters

that were analyzed at Ekebyboda. This could be due to a number of reasons. One possible reason

37

could be the cover of Ekebyboda has fulfilled its purpose of preventing infiltration of water into the

landfill waste heap. Since the landfill was covered twice, one may conclude that the protective layer of

clay and earth is now thick enough to filter out the influence of precipitation changes on the landfill

leachate discharge rate or quality. However, it remains possible that the low correlations found

between leachate properties and precipitation variations may be simply due to the low temporal

resolution and uncertain quality of the historical leachate quality dataset (see section 6.1).

Unfortunately, at present, the possible impact of precipitation variations (or spring snowmelt) on the

leachate quality remains highly uncertain,

In the future, more regular measurements of leachate quality in all seasons would greatly increase the

reliability of any correlation analysis with precipitation variations. Also it would be useful to obtain

measurements of groundwater level fluctuations in the vicinity of the landfill site, as these could

provide an indirect measure of the effect of water infiltration in the soil following precipitation events

or spring snowmelt.

38

7. Conclusions Part of the work presented in this thesis performed for the Uppsala county environmental office

and aimed at evaluate the risk level presented by the decommissioned Ekebybioda landfill site near

Uppsala using the MIFO classification system. As a result of this investigation, the Ekebyboda landfill

site was classified as risk level one, which is the highest possible level. This was mainly due to high

concentrations of toxic metals (Pb, Cu, Zn and particularly Cd), and the suspected presence of

polycyclic aromatic hydrocarbons (PAHs), chlorphenols and chlorinated solvents in the leachate

water. Furthermore, one of the monitoring wells was found to emit a strong smell of petrol, suggesting

the presence of oil residues leaching out of the landfill. This, in combination with the know presence

of industrial waste (and incineration ash from such material) in the landfill suggests a high risk of

toxicity for surface or ground water in the surrounding area. Furthermore, a malfunctioning and

possibly leaky culvert system increases the risk for leachate water to discharge northward and infiltrate

privately-owned water wells.

A more comprehensive assessment of the environmental risk level associated with the

Ekebyboda landfill would require measurements of PAH, chlorphenols, chlorinated solvents and other

chemical compounds in the leachate water, as the history of waste disposal at this site makes it likely

that such substances may be present at toxic levels. From a risk prevention point of view, some form

of containment action is required on the north side of the landfill to prevent leachate to enter private

water wells. One possibility would be to excavate a trench that would direct the contaminated water

currently leaching into the nearby wetland into another, less harmful direction. The integrity of the

drainage system of culvert and wells should also be investigated and repairs effected. Ultimately, the

appropriate measures are for the Uppsala municipality too decide. Also, a useful step to ensure the

water quality of the nearby water wells would be to do an extended water quality testing, currently

performed only for the leachate, to these wells. Ensuring the safety and integrity of drinking water

should be regarded as a high priority even if there just might be a small risk for contamination.

In addition to the MIFO risk classification itself, the long-term evolution of the landfill site was

investigated using historical data on 11 physical and chemical properties of the leachate that have been

regularly monitored over the period 1990-2007. New measurements of leachate quality were

performed in April 2014, to provide a basis for comparison between the historical leachate monitoring

data series and the current composition of the leachate from the landfill.

The leachate monitoring data suggests that the bio-geochemical evolution of the Ekebyboda

landfill did not follow the typical evolution curves observed during maturation of domestic waste

landfills, although there are some similarities. The COD data from the leachate indicates that the initial

aerobic phase of waste degradation at Ekebyboda likely ended when the landfill was finally covered in

1994. After this date, the conductivity and the concentration of most of the major ions measured in the

39

leachate decreased significantly with only minor fluctuations since 2000, and this follows the

expected trend in domestic landfill sites after an initial aerobic degradation phase. A reduction in NO3-

+NO2 in the leachate after 2004 suggests that by then, the availability of oxygen in the waste heap had

declined to a point where denitrification started to take place. However in contrast to other

documented sites, the pH of the Ekeyboda leachate seems to have hardly increased over the period

1990-2014, while SO42- concentration in the leachate seems to have varied at a multi-annual time

scale, but without a definite trend. The lack of a clear trend in SO42- suggests that significant reduction

of sulfate has probably not begun to take place in the heap, but a gradual transition to reducing

conditions could account for the relatively high levels of some dissolved metals in the leachate (e.g.,

Zn, Cd) measured in the April 2014 leachate samples, as increasingly reducing conditions would favor

the mobilization of these metals in solution. Unfortunately, long-term temporal trends of metals in the

leachate could not be established due to the discrepancies in the historical monitoring data. The

interpretation of the leachate data from Ekebyboda is complicated by the fact that the normal order of

waste degradation in the waste heap may have been perturbed when the second coating was installed

in the landfill in 1993-94, because heavy machinery used in this process may have disturbed the

original coating from the 1970s and allowed air to penetrate into the waste heap. In addition, the

Ekebyboda landfill contains industrial waste made of poorly or non-biodegradable materials, and these

materials would not degrade following the predicted evolution curves typical of landfills used

primarily for domestic waste, most of which is organic. Altogether, however, the available evidence

from the leachate trends suggest that the landfill is moving towards an inactive degradation phase with

decreasing concentrations of dissolved substances in the leachate issuing from it.

Finally, the generally low correlations observed between interannual fluctuations of

precipitation (seasonal or total) in the Uppsala area and most the leachate properties over the period

1990-2014 suggest that the current cover of the landfill is largely watertight, such that variations in

precipitation have relatively little impact on the quality of the leachate.

This study is an addition to the ingoing research on landfills and there evolution and hazards.

Landfills are a well-studied area and with lots of ongoing research. This thesis contributes to a

perspective of landfills were fewer studies has been done. The contribution is mainly about providing

additional insight about possible leachate water problems in landfills which has been closed for a long

period. This study has as well contributed with an unusually long dataset compared to other similar

studies. A perspective of the possible issues coming from a mixed landfill of industrial and domestic

content is also the addition of future assessment of old landfill sites.

40

8. Acknowledgements I would like to express my appreciation to my supervisor professor Christian Zdanowitcz who

had provided me with very valuable insights, support and critique. I also wish to express my gratitude

to the Uppsala environmental office that provided me with this thesis subject and the necessary data

and as support to complete the research. I particularly want to thank Ebba Tiberg for supporting me

and patiently taking the time to answer my many questions. I also thank Andreas Sidenqvist for field

assistance and Staffan Grönholm at Uppsala Vatten for proving me with information and field

guidance.

Finally would I like to thank my parents Bo and Gunilla Fors for supporting me during under all

years, their support was absolute essential and without them would I not been studying at this level. A

big thanks should also be expressed to my girlfriend Julia Erkers for her support during hard times.

41

9. References

Books and articles

Alm, S & Britton T, 2008; Stokastik Sannolikhetsteori och statistikteori med tillämpningar, Liber, Stockholm, 544 p. Arora, B B, Mohanty, P, McGuire, J T & Cozzarelli, I M 2013, 'Temporal dynamics of biogeochemical processes at the Norman landfill site', Water Resources vol. 49, pp. 1-18. Cozzarelli I M , Böhlke J K , Masoner J, Breit, G N, Lorah M M, Tuttle M L & Jaeschke J B, 2011, 'Biogeochemical evolution of a landfill leachate plume, Norman, Oklahoma', Ground Water vol. 49, no. 5, pp. 663-87. Flyhammar, P, 1997, Heavy metals in municipal solid waste deposit. Ph. D. Dissertation, Lund University, 128 p. Gabriela, K, Milada, V, Zagorc-Končan, J & Zgajnar Gotvajn, A, 2001, 'Seasonal variations in municipal landfill leachate quality', Management of Environmental Quality: An International Journal vol. 22, no. 5, pp. 612-619. Hedlund, A & Kjellander, C, 2007, Mkb: Introduktion till miljökonsekvensbeskrivning, Studentlitteratur AB, Lund, 197 p. Huan-Jung, F, Hung-Yee, S, Hsin-Sin, Y, & Wen-Ching, C, 2006, 'Characteristics of landfill leachates in central Taiwan', Science of the Total Environment vol. 361, pp. 25-37. Kalčíková, G, Vávrová, M, Zagorc‐Končan, J & Žgajnar Gotvajn, A, 2010, 'Seasonal variations in municipal landfill leachate quality' Management of Environmental Quality: An International Journal vol. 22, pp. 612-619. Khattabi, H, Aleya, L & Jacky M, 2002, 'Changes in the quality of landfill leachates from recent and aged municipal solid waste', Waste Management Research vol. 20, pp. 357-364. Kulikowska, D & Klimiuk, E, 2008, 'The effect of landfill age on municipal leachate composition.', Bioresource Technology vol. 99, no. 13, doi: 10.1016/j.biortech.2007.10.015. Mahmoudi, S & Rubenson, S, 2004, Miljörättensgrunder: Svenska och europeiska regler i ett internationellt perspektiv. Norstedts Juridik AB, Stockholm, 256 p. Salem, Z, Hamouri, K, Djemaa, R & Allia K, 2008, 'Evaluation of landfill leachate pollution and treatment', Desalination vol. 220, no 1-3, pp. 108–114. Sveriges Nationalatlas (SNA), 1996, Sveriges geografi, Stockholm, 176 p. Statom, R, A, Thyne, J, D & McCray, J E, 2004, 'Temporal changes in leachate chemistry of a municipal solid waste landfill cell in Florida, USA', Environmental Geology vol. 45, pp. 982-991.

42

Technical reports & governmental/legislative documents Avfall Sverige, 2012, Avfall Sveriges deponihandbok: Reviderad handbok för deponering som en del av modern avfallshantering. Avfall Sverige rapport D 2012:02 , Malmö, 180 p. Hälsovårdsnämnden VI:3; Ekebyboda 2:1. Stadsarkivet Uppsala stad. Hälsovårdsnämnden VI:4; Ekebyboda 2:1. Stadsarkivet Uppsala stad. Jordbruksverket, 2013, Riktlinjer för gödsling och kalkning, Jordbruksverket informationsrapport 12,2012, Jönköping, 90 p. Natuvårdsverket, 1998, Avfall och producentansvar

Natuvårdsverket, 2008, Lakvatten från deponier 8306. Naturvårdsverket, 1999, Avfallsdeponering-trender, strategier och hållbar utveckling. Naturvårdsverket, 2006, Metallers mobilitet i mark. Naturvårdsverket rapport 5536. Naturvårdsverket, 2002, Metodik för inventering av förorenade områden rapport. Naturvårdsverket Rapport 4918, Fälth & Hässler, Värnamo. Svenska Geotekniska Föreningen (SGF), 2013, Fälthandbok – undersökningar av förorenade områden. SGF Rapport 2:2013. Sveriges Geologiska Undersökning (SGU), 1995, Ekebyboda avfallsanläggning, förundersökning avseende förutsättningar för lokal lakvattenhantering norr om Ekebyboda avfallsupplag. Öman, C, Malmberg, M & Wolf-Watz, C, 2000, Handbok för lakvattenbedömning. Metodik för karakterisering av lakvatten från avfallsupplag, IVL Svenska miljöinstitutet AB, Rapport 00:7, Stockholm, 102 p. Electronic resources consulted EPA 2014,1; Introduction to pH. http://www.epa.gov/caddis/ssr_ph_int.html (Viewed 2014-05-15) EPA 2014,2: 5,9; Conductivity what is conductivity and why is it important?. http://water.epa.gov/type/rsl/monitoring/vms59.cfm (Viewed 2014-03-14) Kemi; 2007; Aluminiumföreningar, oorganiska. http://apps.kemi.se/flodessok/floden/kemamne/oorganiska_aluminiumforeningar.htm (Viewed 2014-08-31) Kemi; 2011; Kadmiumhalten måste minska – för folkhälsans skull En riskbedömning av kadmium med mineralgödsel i fokus Rapport från ett regeringsuppdrag. http://www.kemi.se/Documents/Publikationer/Trycksaker/Rapporter/KemI_Rapport_1_11.pdf (Viewed 2015-01-18) Kemi; 2010; Klor. http://apps.kemi.se/flodessok/floden/kemamne/klor.htm (Viewed 2014-08-31)

Krisweb; 2014; Water Quality: pH, Alkalinity, and Conductivity. http://www.krisweb.com/stream/ph.htm (Viewed 2014-03-26)

43

Landskapsgrundammen; 2014; Natrium. http://www.landskapsgrundamnen.se/gramnen/natriumbott.htm (Viewed 2014-03-14) Lenntech; 2014; Aluminium – A´l. http://www.lenntech.com/periodic/elements/al.htm (Viewed 2014-03-14) Miljöpartiet; 2014; Miljöpartiet historia. http://www.mp.se/om/historia (viewed 2014-01-02) Naturvårdsverket; 2014; Kväve (N-tot). http://utslappisiffror.naturvardsverket.se/Amnen/Organiska-amnen/Kvave/ (Viewed 2014-03-14) SGU; 2014; Brunnsarkivet 2014. http://www.sgu.se/kartvisare/kartvisare-brunnar-sv.html (Viewed 2014-05-05)

44

Dataset references: ALS Scandinavia; 2014; Rapport T1407073 över mätpunkter A1, A2, A3 och A1-4. ALS Scandinavia AB. Bergström; 2014; Precipitation in Uppsala 1990-2007. Department of Earth Sciences, Meteorology. Uppsala University. Miljökontoret; 2010; Ekebyboda avfallsupplag kontrollprogram 2007 Ekebyboda 1:2. Diarienummer 2010-000412. Miljökontoret; 2007; Miljörapport 2006 Ekebyboda avfallsupplag Ekebyboda 1:2. Diarienummer 2007-001520. Miljökontoret; 2006; Miljörapport 2005 Ekebyboda avfallsupplag Ekebyboda 1:2. Diarienummer 2006-000920. Miljökontoret; 2005; Miljörapport Ekebyboda avfallsupplag Ekebyboda 1:2. Diarienummer 2005-000876. Miljökontoret; 2003; Miljörapport 2003 Ekebyboda avfallsupplag Ekebyboda 1:2. Diarienummer 2004-000871. Miljökontoret; 2002; Miljörapport år 2002 Ekebyboda avfallsupplag Ekebyboda 1:2. Diarienummer 2003-000993. Miljökontoret; 2001; Miljörapport 2001 Ekebyboda avfallsupplag Ekebybod 1:2. Diarienummer 2002-000744. Miljökontoret; 2000; Miljörapport 2000 Ekebyboda avfallsupplag, Ekebyboda 1:2. Diarienummer 2001-000855. Miljökontoret; 1999; Miljörapport 1999 Ekebyboda avfallsupplag, Ekebyboda 1:2. Diarienummer 2000-000634. Miljökontoret; 1999; 1999 års miljörapport Ekebyboda avfallsupplag, Ekebyboda 1:2. Diarienummer 2000-000634. Miljökontoret; 1998; Miljörapport 1997 Ekebyboda avfallsupplag, Ekebyboda 1:2. Diarienummer 1998-000402. Miljökontoret; 1996; Miljörapport 1996 Ekebyboda avfallsuppsala, Ekebyboda 1:2. Diarienummer 1997-000525. Miljökontoret; 1995; Miljörapport 1995 Ekebyboda avfallsupplag, Ekebyboda 1:2. Diarienummer 1996-000718. Miljökontoret; 1995; Miljörapport 1994 Ekebyboda avfallsupplag, Ekebyboda 1:2. Diarienummer 1995-000486. Miljökontoret; 1991; Tillsyn avfallsdeponi Ekebyboda kommunen, Ekebyboda 1:2. Diarienummer 1991-000012. Miljökontoret; 1990, 1992, 1993, 1994; Lakvattenprotokoll Ekebyboda, Ekebyboda 1:2. Pärm Vedyxa. Ekeyboda, Vickeby.

45

Appendix 1 Leachate evolution data set of well A1, A2, A3 and A1-4

19901991

19921993

19941995

19961997

19981999

20002001

20022003

20042005

20072014

Variableunits

ConductivmS/m

A1-4331

432271

318118

267281

211264

302254

193105

238207

289Conductivm

S/m

A1442

14789

430392

152255

367165

258275

7486

5959

5464

53Conductivm

S/m

A2130

8466

7192

7279

13797

6350

81104

7789

75110

27Conductivm

S/m

A3609

411461

442427

247308

333282

388419

3324

136150

116124

91Conductivm

S/m

Average394

243262

304307

147227

279189

243262

103177

94134

11399

115Conductivm

S/m

Std. dev. 199

133185

150130

6488

8867

116133

9294

2968

5925

103Conductivm

S/m

Average394

243262

304307

147227

279189

243262

103177

94134

11399

115pH

A1-47,1

6,87,4

7,67,5

7,07,5

7,06,9

7,06,9

7,37,5

6,87,0

7pH

A17,3

7,37,5

7,07,1

7,47,4

7,27,5

7,37,6

7,68,0

7,57,3

7,68

8pH

A27,0

7,07,0

7,37,0

6,97,4

6,87,2

7,38,0

7,07,2

6,96,8

7,57

7pH

A37,4

7,27,4

7,27,6

7,67,7

7,57,4

7,27,4

7,37,6

7,77,7

8,08

8pH

Average7,2

7,27,2

7,27,3

7,47,4

7,37,3

7,27,5

7,27,5

7,47,2

7,58

7pH

Std. dev. 0,2

0,10,3

0,10,3

0,30,2

0,30,2

0,20,4

0,30,3

0,30,4

0,40

1

Alkalinitym

g/LA1-4

12002000

831809

620927

1026181

11001100

970730

500990

8603400

Alkalinitym

g/LA1

310580

3501687

886660

8701250

6731300

940350

410350

290260

329280

Alkalinitym

g/LA2

390440

380387

364290

230347

417370

160390

430290

290230

454140

Alkalinitym

g/LA3

27001900

19002236

8861200

9481284

2491800

13001500

1400580

700460

569460

Alkalinitym

g/LAverage

11331030

11581285

736693

744977

3801143

875803

743430

568453

4511070

Alkalinitym

g/LStd. dev.

1108578

793721

217326

298377

190514

432472

400116

296251

981350

Mgm

g/LA1-4

5165

59

2275

3433

3739

3227

1633

2852

Mgm

g/LA1

1222

1579

7726

3951

2949

5111

1410

98

109

Mgm

g/LA2

189

38

107

815

158

513

1712

1411

202

Mgm

g/LA3

9672

7785

8250

4956

5368

7252

6533

3630

3819

Mgm

g/LAverage

4239

4057

5726

4339

3341

4227

3118

2319

2320

Mgm

g/LStd. dev.

3825

3239

2815

2416

1422

2417

209

1210

1119

Clm

g/LA1-4

340440

509560

49470

500310

84470

370260

96340

270134

Clm

g/LA1

2683

25718

55092

270380

140240

34026

3513

1513

1610

Clm

g/LA2

1612

1616

1712

1628

209

1510

1411

1512

177

Clm

g/LA3

600360

430423

390161

270300

250350

400230

27043

3134

1918

Clm

g/LAverage

214199

228417

37979

257302

180171

306159

14541

10082

1742

Clm

g/LStd. dev.

273153

207255

22055

161173

111133

174150

12134

139109

153

Nam

g/LA1-4

290370

318360

67270

320190

253290

230172

86229

191144

Nam

g/LA1

45070

33496

41081

180300

95165

26931

3819

1517

2215

Nam

g/LA2

1511

1214

1612

1228

218

1613

1815

1416

256

Nam

g/LA3

490290

330393

330130

220250

170243

288175

20352

4239

3220

Nam

g/LAverage

318165

186305

27973

171225

119167

216112

10843

7566

2646

Nam

g/LStd. dev.

215126

165180

15542

97116

6798

11693

8129

9073

557

46

19901991

19921993

19941995

19961997

19981999

20002001

20022003

20042005

20072014

Km

g/LA1-4

110130

3239

3826

3543

3825

2620

1229

2576

Km

g/LA1

7044

25132

12041

76101

4167

9131

2513

1013

1712

Km

g/LA2

128

76

66

58

108

118

87

58

111

Km

g/LA3

200370

260226

210110

180190

150175

193138

18061

6260

6534

Km

g/LAverage

94133

10699

9449

7284

6172

8051

5823

2626

3131

Km

g/LStd. dev.

79142

10187

7938

6870

5363

7251

7022

2220

2428

NO3 +NO

2 mg/L

A1-42

00

13

01

00

12

1

NO3 +NO

2 mg/L

A19

20

2311

044

2310

385

71

23

2

NO3 +NO

2 mg/L

A22

00

10

00

01

15

31

NO3 +NO

2 mg/L

A341

202

4048

185

7437

21130

2934

1411

1115

NO3 +NO

2 mg/L

Average17

61

1624

81

3015

1043

1720

85

63

5

NO3 +NO

2 mg/L

Std. dev. 17

81

1724

72

3116

853

1214

75

40

6

SO4

mg/L

A1-46

6220

1964

2212

2115

2014

1316

1214

SO4

mg/L

A14

1690

1026

11099

39140

3624

4540

1939

3244

40

SO4

mg/L

A2420

1551

120210

150230

530200

3883

97200

150230

180240

8

SO4

mg/L

A36

1550

3850

100120

9563

4537

3441

170240

170190

99

SO4

mg/L

Average143

1363

4776

106118

169106

4040

4974

88131

99158

40

SO4

mg/L

Std. dev. 196

416

4378

3174

21169

426

2974

72104

7783

36

NH4

mg/L

A1-468

132

1512

1721

3226

1915

102

1915

116

NH4

mg/L

A194

140

881

239

5123

5030

03

01

NH4

mg/L

A20

00

00

00

00

00

00

06

NH4

mg/L

A3210

200320

1880

7269

8586

14094

8791

00

01

NH4

mg/L

Average101

7183

704

2231

3935

5448

2635

1031

NH4

mg/L

Std. dev. 86

79137

776

2926

3231

5333

3640

949

CO

Dm

g/LA1-4

140210

90300

6555

11095

160430

9575

90160

13020

CO

Dm

g/LA1

450110

60420

240100

120170

100200

14055

70150

8055

5514

CO

Dm

g/LA2

6070

4035

4555

6055

7030

5580

7090

5060

CO

Dm

g/LA3

390300

310410

260190

140200

170240

210230

19070

8450

406

CO

Dm

g/LAverage

300155

155239

211103

105135

105168

203109

10495

10471

5213

CO

Dm

g/LStd. dev.

17187

111177

9853

3654

4163

14672

5033

3334

86

47

Appendix 2 Precipitation data used in this thesis (Source: SMHI)

19901991

19921993

19941995

19961997

19981999

20002001

20022003

20042005

2007Annual pre

mm

total644

611567

447504

551478

661612

509600

561554

521517

574582

Winter premm

total126

10076

52107

14835

95132

150137

138155

55146

12085

Spring pre

mmtotal

94122

13370

111171

9590

103140

8377

92117

9379

120

48

Appendix 3 Heavy metal analysis results in Ekebyboda leachate sampled in spring 2014

2014Pb mg/L A1-4 0.0877

mg/L A1 0.195mg/L A2 0.0704mg/L A3 0.0845

Cu mg/L A1-4 1.21mg/L A1 6.47mg/L A2 3.75mg/L A3 7.56

Zn mg/L A1-4 10.0mg/L A1 148mg/L A2 119mg/L A3 256

Cd mg/L A1-4 0.0961mg/L A1 0.641mg/L A2 0.162mg/L A3 0.0530

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