Multi-criteria analysis of alternative tunnel corridors in Göteborg A geosystem services perspective Master’s thesis in Master Program in Infrastructure and Environmental Engineering (MPIEE) ABDUL REHMAN Department of Architecture and Civil Engineering CHALMERS UNIVERSITY OF TECHNOLOGY Gothenburg, Sweden 2024 www.chalmers.se www.chalmers.se Master’s thesis 2024 Multi-criteria analysis of alternative tunnel corridors in Göteborg A geosystem services perspective ABDUL REHMAN Division of Geology and Geotechnics Chalmers University of Technology Gothenburg, Sweden 2024 Multi-criteria analysis of alternative tunnel corridors in Göteborg A geosystem services perspective ABDUL REHMAN © ABDUL REHMAN, 2024. Supervisor: Yevheniya Volchko, Geology and Geotechnics, Department of Archi- tecture and Civil Engineering Examiner: Professor Jenny Norrman, Geology and Geotechnics, Department of Architecture and Civil Engineering Master’s Thesis 2024 Department of Architecture and Civil Engineering Division of Geology and Geotechnics Chalmers University of Technology SE-412 96 Gothenburg Telephone +46 31 772 1000 Cover: GIS based map of three possible railway routes. Stretches are included in the city of Gothenburg’s plan. Gothenburg, Sweden 2024 iv Multi-criteria analysis of alternative tunnel corridors in Göteborg A geo-system services perspective ABDUL REHMAN Department of Architecture and Civil Engineering Division of Geology and Geotechnics Chalmers University of Technology Abstract The comprehensive plan of Gothenburg’s municipality, Sweden suggests to extend the railway network in the southern part of the city. There exist three poten- tial railway routes, some of which pass through underground tunnels. This report specifically investigates all three tunnel routes, focusing on the subsurface resources. The evaluation is centered on geo-system services along the tunnel corridors, a novel concept that elucidates the resources and services available for human utilization be- neath the surface. geo-system services can be categorized into four distinct groups: supporting, cultural, regulating, and provisioning. Initially, an assessment is con- ducted to evaluate the current quality of these geo-system services and their potential for exploitation. Additionally, any potential conflicts that could have adverse effects on these at- tributes are examined as part of this evaluation, with Geographic Information Sys- tems (GIS) serving as a key tool in the assessment process. The process utilized for this study is multi-criteria analysis. All three tunnel routes are poised to have a great impact on different geo-system services. The services at high risk are geo- energy wells, groundwater resources, and the mobilizing of pollutants. However, in some parts, the excavation could synergistically extract geo-material through tunnel corridors. But a comparative study is needed to facilitate compre- hensive decision-making. Such a study would compare impacts of potential routes on geo-system services. Careful consideration is required to balance extraction ben- efits against impacts to other underground services and systems. The comparative study aims to support route selection by assessing how alignments may positively or negatively affect the geo-system. This ensures the most suitable choice weighing all relevant factors. Keywords: Geo-system services, Subsurface, GIS, Multi-criteria analysis. v Acknowledgements This master’s thesis was completed at Chalmers University of Technology in the Department of Architecture and Civil Engineering from January 2023 to March 2024. The thesis is worth 30 credits. The thesis intends to create a roadmap for selecting the best tunnel corridor with the least impact on geo-system services using risk assessment and decision support criteria. I am grateful to my supervisor Yevheniya Volchko and my examiner Jenny Norrman for evaluating my work, providing comments and feedback that strengthened the quality of my masters thesis. Furthermore, I am also thankful for the assistance from Emrik Lundin Frisk during various stages. He generously shared his time to discuss challenges the I faced with my risk assessment methodology and mapping of Geosystem services on GIS. I also appreciate Victoria Svahn taking the time to attend my thesis presentation and share her expertise and feedback which strengthened my work. I want to acknowledge the Department of Architecture and Civil Engineering for providing me an opportunity and resources to complete this masters thesis. Abdul Rehman, Gothenburg, 2024 vii Contents List of Figures xi List of Tables xiii 1 Introduction 1 1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1.1 Aim and Objectives . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1.2 Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 Theory 3 2.1 Geosystem Services as a Concept . . . . . . . . . . . . . . . . . . . . 3 2.1.1 Provisioning Services . . . . . . . . . . . . . . . . . . . . . . . 5 2.1.2 Cultural Services . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1.3 Regulating Services . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1.4 Supporting Services . . . . . . . . . . . . . . . . . . . . . . . . 6 2.2 Supporting Geosystem Services . . . . . . . . . . . . . . . . . . . . . 6 2.2.1 Bearing Capacity and Soil Stability . . . . . . . . . . . . . . . 6 2.2.2 Space for Horizontal and Vertical Constructions . . . . . . . . 6 2.2.3 Space for Cables and Pipes . . . . . . . . . . . . . . . . . . . . 7 2.2.4 Underground Storage . . . . . . . . . . . . . . . . . . . . . . . 7 2.3 Cultural Geosystem Services . . . . . . . . . . . . . . . . . . . . . . . 7 2.3.1 Known and Unknown Heritage . . . . . . . . . . . . . . . . . 7 2.3.2 Geological Heritage . . . . . . . . . . . . . . . . . . . . . . . . 8 2.4 Regulating Geosystem Services . . . . . . . . . . . . . . . . . . . . . 8 2.4.1 Geoenergy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2.4.2 Clean and Safe Soil . . . . . . . . . . . . . . . . . . . . . . . . 8 2.4.3 Water Retention in Soil and Rock . . . . . . . . . . . . . . . . 9 2.4.4 Water Filtration Capacity . . . . . . . . . . . . . . . . . . . . 9 2.5 Provisioning Geosystem Services . . . . . . . . . . . . . . . . . . . . . 9 2.5.1 Geothermal Energy . . . . . . . . . . . . . . . . . . . . . . . . 9 2.5.2 Drinking and Process Water Resource . . . . . . . . . . . . . . 9 2.5.3 Groundwater Resource . . . . . . . . . . . . . . . . . . . . . . 10 2.5.4 Geomaterials and Minerals . . . . . . . . . . . . . . . . . . . . 10 3 Methodology 11 ix Contents 3.1 Multi-criteria analysis as a method of assessment . . . . . . . . . . . 12 3.1.1 GS Categories and Data Collection . . . . . . . . . . . . . . . 13 3.1.2 Evaluation and Conflict Analysis of Geosystem Services using GIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4 Case Study 19 5 Results 25 5.1 Supporting Geosystem Services . . . . . . . . . . . . . . . . . . . . . 25 5.1.1 Bedrock and Structure . . . . . . . . . . . . . . . . . . . . . . 25 5.1.2 Soil Depth and Bearing Capacity . . . . . . . . . . . . . . . . 26 5.1.3 Space for Horizontal and Vertical Construction . . . . . . . . 28 5.1.4 Space of Utilities (Wire, cables, pipes) . . . . . . . . . . . . . 31 5.1.5 Underground storage . . . . . . . . . . . . . . . . . . . . . . . 31 5.2 Cultural Geosystem Services . . . . . . . . . . . . . . . . . . . . . . . 31 5.2.1 Known and Unknown cultural heritage . . . . . . . . . . . . . 32 5.2.2 Geological heritage . . . . . . . . . . . . . . . . . . . . . . . . 32 5.3 Regulating Geo-system Services . . . . . . . . . . . . . . . . . . . . . 34 5.3.1 Geo-Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 5.3.2 Clean and Safe Soil . . . . . . . . . . . . . . . . . . . . . . . . 35 5.3.3 Water Retention . . . . . . . . . . . . . . . . . . . . . . . . . 43 5.3.4 Water Filtration Capacity . . . . . . . . . . . . . . . . . . . . 43 5.4 Provisioning Geo-system Services . . . . . . . . . . . . . . . . . . . . 44 5.4.1 Geothermal Energy . . . . . . . . . . . . . . . . . . . . . . . . 45 5.4.2 Drinking and Process Water Resource . . . . . . . . . . . . . . 45 5.4.3 Ground Water Resource . . . . . . . . . . . . . . . . . . . . . 46 5.4.4 Minerals and Geomaterials . . . . . . . . . . . . . . . . . . . . 51 5.4.5 Multi-criteria Analysis . . . . . . . . . . . . . . . . . . . . . . 51 6 Discussion 59 7 Conclusion 61 Bibliography 65 A Appendix 1 I x List of Figures 4.1 GIS based map of three possible railway routes. Stretches are included in the city of Gothenburg’s plan . . . . . . . . . . . . . . . . . . . . 20 4.2 Elevation profile of Tunnel Route 1 (Source: Google Earth) . . . . . . 21 4.3 Elevation Profile of Tunnel Route 2 (Source: Google Earth) . . . . . 21 4.4 Elevation Profile of Tunnel Route 3(Source: Google Earth) . . . . . . 22 4.5 GIS Map of surface soil types along the possible tunnel routes . . . . 23 4.6 Land use Map of the Study Area . . . . . . . . . . . . . . . . . . . . 24 5.1 Map of bedrock along the possible tunnel stretches . . . . . . . . . . 26 5.2 GIS map of the soil depth along the possible tunnel sections . . . . . 28 5.3 The figure reports the overall load-bearing capacity of rocks . . . . . 30 5.4 Map of geological heritage along the tunnel stretches . . . . . . . . . 33 5.5 Map showing the present energy wells with color depicting error in position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 5.6 This figure reports the quality of geo-energy and where existing energy wells are located. The map is based on figure 5.1, 5.3 and 5.5 . . . . 36 5.7 Uranium content map along the tunnel stretch (SGU Website) . . . . 38 5.8 GIS Map of the potential pollution along the possible tunnel routes . 39 5.9 Risk potential of pollution spread along the possible tunnel routes . . 41 5.10 Map showing groundwater storage capacity along the possible tunnel routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 5.11 GIS based Map of Ground water stability levels before tunnel con- struction based on 4.5, 5.1 and 5.10 . . . . . . . . . . . . . . . . . . . 49 5.12 GIS based map of Groundwater levels after tunnel construction based on 4.5, 5.1, 5.10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 xi List of Figures xii List of Tables 3.1 Geosystem Services Data Sources . . . . . . . . . . . . . . . . . . . . 14 3.2 Assesment based on Geographic Information System (GIS) maps . . . 15 5.1 Geo-system services assessment with Multi Criteria Analysis (MCA) . . . 52 5.1 Geo-system services assessment with Multi Criteria Analysis (MCA) . . . 53 5.1 Geo-system services assessment with Multi Criteria Analysis (MCA) . . . 54 5.1 Geo-system services assessment with Multi Criteria Analysis (MCA) . . . 55 5.1 Geo-system services assessment with Multi Criteria Analysis (MCA) . . . 56 5.1 Geo-system services assessment with Multi Criteria Analysis (MCA) . . . 57 5.1 Geo-system services assessment with Multi Criteria Analysis (MCA) . . . 58 A.1 Assessment of the potential of geosystem services before and after construction of possible tunnel route 1 . . . . . . . . . . . . . . . . . I A.2 Assessment of the potential of geosystem services before and after construction of possible tunnel route 2 . . . . . . . . . . . . . . . . . III A.3 Assessment of the potential of geosystem services before and after construction of possible tunnel route 3 . . . . . . . . . . . . . . . . . V xiii List of Tables xiv 1 Introduction 1.1 Background The benefits that humans derive from the subsurface are known as geosystem ser- vices (GS) (Frisk et al., 2022). These include the use of the subsurface for building and construction both inside and outside of it, the extraction of groundwater, en- ergy, and materials, the storing of resources like water, energy, and carbon dioxide, the provision of habitat for ecosystems and support for surface life, and the preserva- tion of cultural and geological heritage. Sustainable management of the subsurface is hampered by sectorial management, which promotes the first-come-first-served approach without careful consideration of competing or complementing subsurface uses (de Mulder et al., 2012). This affects inter-generational equity. Geosystem services, such as clean water, natural resources, and climate regulation, are advantages that humans obtain from the subsurface. These services are essential to the planning and decision-making process for sustainable municipal planning, particularly when it comes to subterranean development (Bartel, 2016). Finally, taking into account the potential effects on the city’s geosystem, this analysis will offer useful insights for decision-makers about the selection of the most viable and sustainable tunnel corridor for Gothenburg’s railway infrastructure. The subsurface may also contain significant artifacts and locations that contribute to our understanding of the history of the planet, such as archaeological discoveries, geological history, and contaminated groundwater or soil that needs to be cleaned up. Ecosystems can develop habitats in the subsurface. This new idea called geosystem services seeks to highlight the value of underground resources to people. Increasing the capacity of public transportation south of the city center is the rail- way’s main objective. These passageways, however, present various difficulties in terms of the geology, above- and below-ground conditions, and existing structures. The municipality will suggest fewer viable routes after the master plan becomes enforceable, based on a location analysis. 1 1. Introduction 1.1.1 Aim and Objectives The specific objectives of this study are: 1. To assess the current geosystem services within the tunnel corridor by utilizing map resources and databases. 2. To evaluate the present state of geosystem service utilization within the study area. 3. To examine the potential impact of construction proposed tunnel routes on the utilization of geosystem services, both presently and in the foreseeable future, through the application of GIS. This study will evaluate the effects of three different tunnel pathways that have been suggested for Gothenburg’s railway infrastructure on the environment, society, and the economy. By assessing the impacts on current geosystem services, and come up with the stretches with the least negative and most positive impacts in relation to effects on geosystem services. 1.1.2 Limitations The list of geosystem services listed in Chapter 2, which are based on the report "To incorporate subsurface services in the planning" (Norrman et al., 2021b), serves as the basis for this study’s examination. In the region of Gothenburg, these services are thought to be pertinent for subsurface planning. Chalmers created the SUB matrix in association with Luleå University and the City of Gothenburg (Norrman et al., 2021a). Depending on the geosystem service being researched, the study area is confined to a 100-meter-wide corridor along the possible tunnel, and the analysis is only done at ground level and the level at which the tunnel is expected to be built. 2 2 Theory 2.1 Geosystem Services as a Concept The primary goal of the review on geosystem services by (Frisk et al., 2022) was to identify articles with precise definitions or examples of geosystem services. Emrik’s review used as a general framework for understanding geosystem services. Later on using a SUB matrix categories as a specific framework originally based on subsurface qualities from flatosmotet report. Which explains the the idea of "geosystem ser- vices" and how crucial it is for using subsurface resources sustainably. It is said that subterranean development is prioritized first and is mostly unplanned these days. The need of recognizing the significance and application of geosystem services in society’s planning and decision-making is underlined. Abiotic (eco)system services from the subsurface, such as groundwater ecosystem services, must be considered in planning, and the study outlines how to do so. It is recommended that more research be done on the idea of "geosystem services" and its applicability to planning. This research highlights the need of subsurface planning for smaller towns as well as larger cities, and the necessity of integrating subsurface features for a sustainable use of the subsurface. The geology of the region is examined, and current and prospective subsurface resources are mapped using classifications of attributes including supply, supporting, cultural, and regulating which is explained in later sections (Norrman et al., 2020). Evaluations of the extent of use and prospects for future application of the subterranean resources are also included in the research. In addition, the analysis analyzes the current land use in the area and outlines the potential effects of future plans on various subsurface resources. For Articles were deemed eligible if they met at least one of these requirements. The review concentrated on journal papers about geosystem services or abiotic services that were written and published in the literature about geoscience, geo conservation, or ecosystem services. Only peer-reviewed English-language articles met the inclusion requirements. Three cru- cial actions were part of the review process: The research field is mapped by 1) locating and compiling pertinent research, 2) objectively assessing research articles, and 3) combining the results into a coherent thesis regarding geosystem services. Following the initial stage of locating relevant articles, a review of the literature was conducted to find examples of geosystem services and classify them. The authors used examples from the literature or their own ideas in the absence of examples to determine the associated advantages of the geosystem services. 3 2. Theory The concept of geosystem services is very crucial for the sustainable use of the subsurface. The subsurface refers to the region beneath the Earth’s surface, en- compassing both underground and underwater areas. On one hand, we can identify ecological systems, such as terrestrial biomass and marine ecosystems, which are influenced by factors like light, water, and oxygen availability, and involve vari- ous living communities and activities. On the other hand, the lithosphere and its geosystems have limited biological activity due to the absence of light and frequently anaerobic conditions. Geosystems are characterized by specific geological features, landscapes, rock types, minerals, and fossils. They are also affected by geophysical and geochemical factors, including the risk of natural disasters like earthquakes, landslides, liquefaction, and subsidence, as well as human activities like subsurface construction, mineral extraction, and pollution. Achieving sustainable development in the subsurface requires understanding abiotic resources, including three-dimensional space, and recognizing their significance for human well-being. However, there’s currently a lack of authoritative assessments re- garding the role of the subsurface and its associated environmental trade-offs. This gap exists because of the absence of a comprehensive and integrated framework for addressing the subsurface and its contributions to human welfare (de Mulder et al., 2012).The utilization of the novel concept of geosystem services, which complements the concept of ecosystem services, is embraced. This new concept is introduced to enhance our understanding and evaluation of the services provided by geological and geospatial systems. , we not only gain a better foundation for comprehending the intricate interplay of natural and human-related processes within the subsurface but also establish stronger connections with a community of geoscientists and stake- holders who may not have been closely aligned with the well-established ecosystem services movement (Armstrong et al., 2012). The geosystem services were divided into seven broader groupings with overlapping services after locating pertinent articles, such as Groundwater resources for drink- ing and Groundwater used as a material. These categories were listed as follows: A) Stable and safe environment; B) Groundwater; C) Underground space; D) Un- derground materials resources; E) Underground energy resources; F) Underground cultural heritage repository; and other (Gray, 2011). Thereafter, each group was independently searched using targeted keywords, followed by a generic search phrase associated with common economic valuation terminology and techniques. Geosystem services encompass the benefits and contributions to human well-being that originate from the subsurface. The term "geosystem services" was introduced by in 2005 (Gray, 2005) during a discussion about the relevance of abiotic components in defining ecosystem services and preserving geodiversity, building upon his earlier work in 2004 and 2011 (Gray, 2011). The categorization of geosystem services aligns with the framework established by the Millennium Ecosystem Assessment (MEA). 4 2. Theory 2.1.1 Provisioning Services This describes the tangible goods, materials, and products that ecosystems directly benefit humans with. The creation, acquisition, and distribution of natural re- sources—which are essential to both economic activity and human welfare—are included in these services (Highley & Bonel, 2004). The subsurface primarily serves as a source of essential materials and resources, which have been extracted for var- ious purposes over millennia. Natural resource management places significant em- phasis on the extraction of material resources from the subsurface. This becomes especially critical with the global population growth, where geosystem provisioning services, such as building materials, are increasingly valuable and, in some cases, scarce (Highley et al., 2004). Notably, the stocks and flows of rare earth materi- als have geopolitical significance, although such abiotic flows from construction and mining activities are often excluded from the conventional concept of ecosystem ser- vices. Following are some of these are : Geothermal Energy, Process water resources, Groundwater resources, Geomaterials and Minerals. 2.1.2 Cultural Services The non-material advantages that ecosystems offer to people, such as recreational, spiritual, and cultural activities, are referred to as cultural services. These services improve communities’ quality of life by supporting their cultural identity and general well-being. Following are some examples of this type. Archaeological Sites and Cultural Heritage: The subsoil is home to several archaeological sites and geological formations, as well as historic ruins. Due to their historical and cultural relevance, these locations draw tourists and encourage cultural tourism. Geographical and Geological Features: Special geological features offer aesthetic and recreational value. Examples of these characteristics include rock formations, canyons, and caves. They promote a sense of pride and a connection to the place by frequently acting as monuments and symbols of regional or national identity. More than 10 percent of World Heritage sites feature earthen structures, which can en- hance cultural prosperity. Examples include certain U.S. National Parks with cave systems (e.g., Mammoth Cave) and unique geological features such as the carbonif- erous rocks at the Heijmans quarry in the Netherlands or the cultural significance of locations like Ayers Rock for Indigenous people in Australia (UNESCO, 2015). 2.1.3 Regulating Services These include the natural processes that support and uphold the functions and con- ditions of the environment. The resilience, stability, and usefulness of ecosystems as well as human activity are enhanced by these services. These services are increas- ingly harnessed in energy systems, such as heat-cold storage systems that utilize the subsurface’s ability to regulate temperatures. The presence of permafrost and its potential responses to climate change are noteworthy examples that could impact subsurface regulating services. Systems in Sweden that extract and redistribute heat and cold stored underground rely on this regulating function of the subsurface, rather 5 2. Theory than geothermal heat derived from deeper earth processes. Thawing permafrost can impact existing infrastructure, leading to stability issues and environmental risks. On a broader scale, long-term geochemical cycles within the geosystem play a vi- tal role, including carbon sequestration and the implications of carbon capture and storage (CCS) as a technology for mitigating climate change. Following are some examples of this category: Geo Energy, Clean and safe soil, Water retention in soils and rock, water filtration capacity (Dahl & Stedman, 2013). 2.1.4 Supporting Services While not separately identified in the CICES framework (Common International Classification of Ecosystem Services), supporting services from the subsurface are essential. They create a stable environment for construction and habitation. The urban growth and increasing resource demands underline the growing importance of geosystem services concerning subsurface use and the impacts of human activities on current and future uses. These supporting services involve utilizing underground spaces for living, tunnels, and infrastructure for public services. Additionally, they encompass addressing potential hazards, both natural and human-induced, from the subsurface, such as earthquake risks. De Groot (2006) (Groot, 2006) distinguished the carrier function, which could be labeled as carrier services, emphasizing the vital role played by the subsurface in providing a stable platform for various activities. 2.2 Supporting Geosystem Services 2.2.1 Bearing Capacity and Soil Stability One of the most important parts in the construction of any structure is to have a well and calculated knowledge of the stability of soil and its capacity to bear the weight of the structure, i.e., bearing capacity. Different types of soils and rocks exist in the world, having different properties and they show different types of behaviors towards construction whether above or below the ground surface. Clay and rocks are examples of two different types of material. The soil-type clay is very soft and is a very unstable material as compared to the rock, e.g., Schist, which is very hard and considered a very stable rock type. In Sweden, there are rocks having high zones of fracturing and due to this, they show high deformations (Allen, 2002). Such behaviors cause an impact on the bearing capacity of the soil on which structures are to be made. For the safe construction of tunnels, buildings, dams, and roads, the bearing capacity and stability of soil are very highly significant. 2.2.2 Space for Horizontal and Vertical Constructions There are two types of underground infrastructure constructions, i.e., horizontal and vertical constructions. Vertical constructions that can be constructed below the surface level include buildings, garages, storage tanks, etc. They are very useful in forming a secure environment and maximizing the space on the ground surface 6 2. Theory (Taromi Sandström et al., 2021). These constructions can also help in storing dan- gerous materials, and thus their depth can be decided according to the nature of the material. Similarly, horizontal structures are constructed underground the surface, such as tunnels, audits, subways, etc. The purpose of having horizontal constructions is to lower the transit time, and people can reach their destination on time without any traffic blockages. Such constructions also provide a safe passage with a clean and secure environment (Zargarian et al., 2016). Nowadays, it has become a new fashion to build underground infrastructures. 2.2.3 Space for Cables and Pipes During underground construction, there are some wires, pipes, and cables. Wires, pipes, and cables are used for providing electricity, water, and sewage through pipes for the infrastructures. These things were generally placed below the ground surface because they occupy massive space and cause trouble for the public above ground (Kuchler et al., 2024). Cables, wires, and pipes are often placed below the Earth’s surface commonly 2-6 meters below so that structures could have easy access to them for the facilities they provide (Noon, 1997). Moreover, wires, cables, and pipes below the surface of the Earth are very secure and they are protected during war or any bomb attacks on the surface. 2.2.4 Underground Storage Another important structural feature that can be found underground is the storage places. These storage areas/cavities can be either for water storage purposes or for storing different types of gases, e.g., carbon dioxide or natural gases. These tanks can help collect rainwater so that it can further be used for various commercial as well as domestic purposes. Underground storages were usually built on rocks having high porosity and permeability so that the Earth’s surface could capture the gases and water and store it (Taromi Sandström et al., 2021). The most common types of rocks that can be utilized for underground storage are sedimentary rocks, because of their porous and permeable nature (Kuchler et al., 2024). 2.3 Cultural Geosystem Services 2.3.1 Known and Unknown Heritage Before starting any underground construction in the cities’ area, there are historical sites that can be termed to be known and unknown heritage sites. Known heritages are those historical sites that are discovered and preserved by the archaeological department to signify the cultural importance to the people, while unknown heritage sites are those sites that have not been investigated archaeologically yet but can be labeled as cultural heritage in the future (Henderson, 2019) (Körner & Wahlgren, 2015). It is a very complicated task to build underground structures having these 7 2. Theory heritages as they are protected by the laws of the country. Permission must be taken from the relevant authorities to construct the structure under such sites because of the danger of collapsing during construction beneath them. 2.3.2 Geological Heritage Geological heritage also plays an important role and should be taken under serious consideration during underground construction. It deals with the past of Earth’s making and the habitat that lived millions and billions of years ago. It can be further classified into extremely important geological formations such as older rocks having wide information about geology and geological features (Körner & Wahlgren, 2015). It should be taken under serious care as it gives major resources for different types of species (Gray, 2011). So during the planning phase of any construction, the geological heritage land must be considered so that it cannot be exploited because of being a rare resource. These geological heritages can also be termed as Geodiversity and Geotope. 2.4 Regulating Geosystem Services 2.4.1 Geoenergy Geoenergy is an example of utilizing the underground energy trapped in between the rocks, groundwater, and soils when the sunlight causes the ground to be heated up. This geoenergy is present at shallow depth. Shallow geothermal systems use the relatively constant temperature of the ground just a few meters below the surface to provide heating and cooling for buildings. This underground energy due to sunlight can be used for different purposes, including the major one for electricity purposes. There are many sources in which Geoenergy can be stored like groundwater heat, etc. Geoenergy itself can be used for the storage of heat and energy directly from the sun (Taromi Sandström et al., 2021). There are many Geoenergy facilities, approximately in millions, installed in Sweden as they are eco-friendly and provide an alternative for other heating devices. 2.4.2 Clean and Safe Soil Clean and safe soil is also an important part of construction on underground surfaces. Ground that is polluted with human or industrial waste is dangerous and risky for underground construction as it poses serious health and life threats to the people (P. Andersson, 2022). This pollution can be due to the human activities and industrial waste that can be dumped into the water which seeps into the soil while some of the waste that pollutes the soil is the medical waste from the hospital and the explosives that were left unchecked on the ground which later goes into the soil and pollutes it. In this way, the soil under the Earth’s surface becomes toxic and becomes a serious threat for constructing in such ground. For the safe construction of underground structures, it is a must to evaluate the soils in which structures are to be made so 8 2. Theory that they will be safe and clean for the people who go on a routine basis (SPIMFAB, 2014). 2.4.3 Water Retention in Soil and Rock Soils and rocks have a very unique property of water retention. The intensity of water retention depends upon the nature of soils and rocks and their properties like porosity, permeability and retention against water. In order to retain the water, the material of soil must be capable of storing water either through storage tanks or groundwater formation (Bartel, 2016). Materials having excellent water retention properties can help in reducing the effect of flooding. Water retention can be lower when there are large holes and cracks in the rocky formation and also have less intensity of precipitation which causes infiltration in the materials. Geomaterials are also considered to have poor water retaining capacities due to continuous weathering and erosion (Stråhle, 2001). 2.4.4 Water Filtration Capacity Water filtration is also a property that can be exhibited during the construction of any underground structure. The material in which the construction is going to be done must be able to infiltrate the water. This can help in infiltrating the water and make it cleaner by removing the impurities (P. Andersson, 2022). This water can then be used for drinking purposes for people. During any construction, there will be a layer for waterproofing that can be installed which can lower the capacity of infiltration, thus causing a lessening of filtering capacity. 2.5 Provisioning Geosystem Services 2.5.1 Geothermal Energy Geothermal energy is a renewable form of energy that is derived from the heat that is naturally produced within the Earth’s crust. This heat is generated by the decay of radioactive isotopes, as well as residual heat from the formation of the planet (Geological Survey of Sweden, 2022b). Geothermal energy can be harnessed for a variety of applications, including electricity generation, space heating, and cooling. There are two main types of geothermal systems used in Sweden: shallow and deep geothermal systems. Deep geothermal systems, on the other hand, use the high temperature of the Earth’s crust several kilometers below the surface to generate electricity (Li et al., 2015). 2.5.2 Drinking and Process Water Resource For drinking and cleaning purposes, it must be necessary to store the water either on the surface or below the surface of the Earth. The water is usually stored in between the cracks and pores of soils and rocks. Sedimentary rocks are excellent for storing water because of their porous and permeable behavior while glacial sediments are 9 2. Theory the best example in the case of soils (Geological Survey of Sweden, 2021a, 2022c). Crystalline rocks can also be able to store the groundwater but they are not as good as that of other sedimentary rocks. A high amount of salt and iron can impure the soil and decrease the quality of groundwater. 2.5.3 Groundwater Resource During the construction, it is necessary to maintain the groundwater resource. Groundwater is an important resource not only for drinking purposes but also to sta- bilize the environment and ecosystem for animals, plants, and humans. Increasing and decreasing groundwater levels cause different types of problems on the surface (Gray, 2011). For example, an increase in the groundwater level causes floods and landslides while a lowering in the groundwater level causes the plants to decay be- cause of the low water level. An increase in the pore pressure leads to low slope stability. Observing all the factors, if an underground tunnel is going to be con- structed, it must be ensured that it will be fully tight and make no new pathways for the water to drain so that groundwater level should be maintained (Hjerne, 2021). Changes in groundwater levels can influence the stability of the surrounding soil and rock layers. A sudden drop in groundwater levels may lead to subsidence, which can damage surface structures and infrastructure. Alterations in groundwater levels can affect ecosystems dependent on groundwater, such as wetlands or vegetation. Fluc- tuations may harm aquatic life and impact the balance of local ecosystems. For tunneling projects, maintaining groundwater levels at a consistent level is crucial to ensure the stability of the tunnel and prevent water infiltration into the tunnel, which can lead to maintenance issues (Hjerne, 2021). 2.5.4 Geomaterials and Minerals During the construction below the surface of the Earth, there are many different types of geomaterials and minerals encountered in the ground. These geomateri- als and minerals are sometimes very rare and need to be protected and must be extracted according to the laws of that country. These geomaterials include soils, sands, gravels, minerals, and rocks. These materials are used for the infilling of the foundation along with various other purposes for stabilizing the ground surface (Geological Survey of Sweden, 2022a) (B. Andersson, 2022). The extraction of these materials and minerals must be done in accordance with laws, and special permits must be taken to build any structure along these sites. Tunnel construction and shaft making are examples of the structures that cause serious concerns to these materials as the construction of these structures requires drilling and blasting which causes major damage to the Earth’s surface so they must abide by the rules and laws of extraction of geomaterials and minerals from the soil of that areas (Allen, 2002). Minerals, on the other hand, are formed by different geological processes and contain a special physical and chemical composition. They are usually very rare and have a significant importance in daily life. So, there is no construction allowed to be done at those sites having geomaterials and minerals of high importance according to the environmental codes. 10 3 Methodology The possible effects of tunnel construction on subsurface ecosystems in three separate corridors are assessed using a multi-criteria analysis as a technique approach. The investigation took into account which include economic, social, and environmental factors (Sutcliffe et al., 2021). In order to accomplish this, the study will look into the current land use and existing geosystem services along the corridors for the proposed tunnels, assess the viability of utilizing the geosystem services already present in the study areas, define the environmental, social, and economic aspects of those services, and assess the effects of tunnel construction using multi-criteria analysis. Establishing a precise definition of the issue or choice that must be decided is the first stage in conducting an MCA (Belton & Stewart, 2002). This includes deciding on the objectives and criteria that will be applied to the evaluation of the options. The criteria are created and defined next. These standards must be relevant, quantifiable, and directly tied to the decision-making issue. Also, each criterion should have a distinct weight or level of importance assigned to it, and they should be independent of one another (Taha, 2007). Finding the options that will be assessed is the third phase. These options should illustrate the various approaches that can be taken to solve the choice problem, and they should be practical and realistic (Zaraté et al., 2021). For every option and standard, data is gathered. This can involve gathering pri- mary data through surveys or interviews or secondary data from published reports or databases. Many techniques are used to examine the data, including pairwise comparisons, decision trees, and weighted scoring. By comparing each choice to one another and identifying their advantages and disadvantages, this analysis can aid. Based on the criteria and objectives, the analysis’s findings are presented together with a recommendation for the most appropriate action. A description of the anal- ysis’s limitations and recommendations for further study should be included in the conclusions (Wang et al., 2022). 11 3. Methodology 3.1 Multi-criteria analysis as a method of assess- ment MCA is a helpful tool for making decisions because it can assess several options ac- cording to different standards. Setting goals and determining pertinent assessment elements are the steps in the process that determine how well each alternative satis- fies the goals (Lootsma, 1997). The criteria that will be taken into consideration are first defined by the decision makers and might be either quantitative or qualitative in nature. Aspects that are social, technical, environmental, and economic are some examples (Belton & Stewart, 2002). The performance of several options in relation to each criterion is then recorded. Each alternative’s overall value is determined by MCA using weighted scores. The procedure makes it possible to visualize option trade-offs (Belton & Stewart, 2002). MCA has become more and more popular when it comes to public sector investment decisions that need to balance a lot of intricate aspects. The decision problem is precisely defined at the outset of the MCA process, and a collection of viable options or solutions is produced (Belton & Stewart, 2002). The performance of each alternative is then evaluated by identifying pertinent assessment criteria (Wallenius et al., 2008). Environmental, social, economic, and aspects may be included in these requirements. The degree to which each option meets each specific condition is then measured. The relative importance of each criteria to the stakeholders determines how heavy it is. MCA then uses mathematical methods like weighted summing or outranking to determine an overall score for each solution (Ishizaka & Labib, 2011). This makes it possible to compare alternatives directly even when they are measured on various scales. In this research, each tunnel route is analyzed for different geosystem services, keep- ing in view the subsurface factors. Every tunnel route is analyzed by overlay analysis of multiple layers of factors and each factors contribution is observed. Each factor is given an impact rate based on its importance. This overlay analysis is performed in GIS Software. Then further the social, environmental and economic impact is analyzed for each route. MCA table is designed on the basis of good,neutral and bad impact of tunnel routes on geosystem services. MCA was used to analyze each tunnel routes on the basis of number of factors in the context of following effects: Social Impact: Geosystems can pose significant safety and risk challenges in tun- neling. Using MCA, the consideration of various safety criteria, such as risk of collapses, groundwater infiltration, lowering of groundwater levels, damage to na- tional heritages was made. By assessing these risks alongside other project goals, during construction informed decisions can be made to enhance safety measures. Environmental Impact: Tunneling projects can have a substantial environmental footprint. Using MCA, the environmental impact of tunnel construction in terms of factors like habitat disruption, pollution, and noise was also assessed. By considering these factors alongside social and economic criteria, a balance between project goals 12 3. Methodology and environmental sustainability was considered. Economic Impact: The economic aspect is crucial in tunneling. MCA is used to evaluate the cost-effectiveness of different geosystems and what effect does the tunneling cause due to change in the present geosystem. For example, in terms of bearing capacity, the MCA was helpful to chose the path where least reinforcement and lining is required to keep the project economical. By quantifying and comparing costs and benefits, decisions that optimize the return on investment could be made. The methodology applied in this research was a multicriteria analysis to evaluate each proposed tunnel corridor. The potential effects of each corridor were assessed on the basis of the following scales: Negligible: No known effect anticipated. Minor: Small change from current conditions anticipated. Moderate: evident change from current conditions anticipated. Major: Large change from current conditions anticipated. This evaluation was conducted using a "do nothing" concept, which considered what effects tunnel construction would have on geosystems if no mitigation or management measures were implemented. Potential impacts were identified by analyzing how geosystem services may fluctuate or be influenced from baseline conditions with the introduction of each tunnel corridor option. 3.1.1 GS Categories and Data Collection The idea of geosystem services offers a framework that is both appealing and dif- ficult. On the one hand, it acts as a thorough description and classification of the advantages humans derive from abiotic resources in the subsurface, highlighting resources that could otherwise go unreported and promoting interaction between professionals and laypeople. Yet, it oversimplifies a complicated and interdependent world. The literature research on geosystem services also shows that the definition of the term changes depending on the readership and goal of the authors. The geological systems beneath the surface of the earth provide several crucial func- tions to people and society. Hence, the subsurface is a resource with several uses that offer so-called geosystem services. Undefined as of yet, geosystem services refer to the benefits that the earth’s geological system provides to humans in terms of well-being and quality of life (Gray, 2011). Four categories of geosystem services are distinguished: supporting, cultural, regulating, and provisioning. The study "Inte- grating subsurface services into planning" served as the basis for the list of geosystem services mentioned in this chapter (Norrman et al., 2021b). The information used to create the map materials is sourced from publicly available data provided by various organizations, including the Geological Survey of Sweden, the Land Survey, the County Administrative Board, and the Riksantikvarieämbetet. Additionally, data from the City Planning Office in Gothenburg is included and 13 3. Methodology detailed in Table 3.1. Table 3.1: Geosystem Services Data Sources Geosystem Services Data Source Bearing Capacity • Assessment based on maps with bedrock and soil types obtained from SGU’s open data (source) SUPPORTING SERVICES Space for sewerage, ca- bles and utility lines • Data sourced by (source) Space for underground Construction • No Data Space for Underground disposal and storage • SGU’s open data source (source) Groundwater resources for drinking and as a material (industrial and irrigation purposes) • Assessment based on maps with bedrock and soil types obtained from SGU’s open data (source) PROVISIONING SERVICES Extraction of geomateri- als • Soiltype and Bedrock map data obtained from SGU’s open data source Fossil energy resources • No Data Geothermal resources • No Data Regulation of erosion • Assessment based on maps with bedrock and soil types obtained from SGU’s open data (source) REGULATING SERVICES Regulation of groundwa- ter quantity and quality • Assessment made on the ba- sis Hydrological data, Soil type and bedrock maps obtained from SGU’s open data source (source) 14 https://www.sgu.se/produkter-och-tjanster/geologiska-data/vara-data-per-amnesomrade/ https://www.ledningskollen.se/ https://www.sgu.se/produkter-och-tjanster/geologiska-data/vara-data-per-amnesomrade/ https://www.sgu.se/produkter-och-tjanster/geologiska-data/vara-data-per-amnesomrade/ https://www.sgu.se/produkter-och-tjanster/geologiska-data/vara-data-per-amnesomrade/ https://www.sgu.se/produkter-och-tjanster/geologiska-data/vara-data-per-amnesomrade/ 3. Methodology Geosystem Services (Continued) Data Source Regulation of temper- ature by underground thermal storage capacity • Assessment made through Ura- nium Map and Geoenergy well data obtained from SGU’s open data source (source) Regulation of soil and bedrock chemistry, in- cluding contamination potential • Uranium content map obtained from SGU’s open data (source) • Potentially contaminated areas obtained from the County Ad- ministrative Board’s open data (source) • Radon risk map data is unavail- able however assessment is made using a literature review Historical, recreational and sacred sites • Assessment based on maps with bedrock and soil types obtained from SGU’s open data (source) CULTURAL SERVICES Geological Heritage • SGU’s open data source (source) 3.1.2 Evaluation and Conflict Analysis of Geosystem Ser- vices using GIS The evaluation of the feasibility of utilizing geosystem services and identifying po- tential conflicts related to these services is conducted through custom Geographic Information System (GIS) maps. These GIS maps are specifically created for geosys- tem services that exhibit varying requirements along the route or may be influenced by the construction of a potential tunnel. This assessment employs a color-coded system, which is documented in Table 3.2. The color coding used is tailored to the specific site being investigated. Table 3.2: Assesment based on Geographic Information System (GIS) maps Geosystem Services Label Colors Description Poor Bearing Ca- pacity • The soil is mostly clay 15 https://www.sgu.se/produkter-och-tjanster/geologiska-data/vara-data-per-amnesomrade/ https://www.sgu.se/produkter-och-tjanster/geologiska-data/vara-data-per-amnesomrade/geofysiska-data/geofysiska-flygmatningar-gammastralning-uran/ https://extgeodatakatalog.lansstyrelsen.se/GeodataKatalogen/GetMetaDataById?id=e5f8c5ca-62a9-41d6-900c-43f2837a8757 https://www.sgu.se/produkter-och-tjanster/geologiska-data/vara-data-per-amnesomrade/ https://www.sgu.se/produkter-och-tjanster/geologiska-data/vara-data-per-amnesomrade/ 3. Methodology Geosystem Services Label Colors Description Supporting Bearing Capacity Moderate Bearing Capacity • Stable bedrock with fractured zones Good Bearing Ca- pacity • Bedrock with good load bearing capacity Geological Heritage • Geological heritage within tunnel section Cultural Services Geological Heritage Geological Heritage • Geological heritage near tunnel section Geological Heritage • No Geological Her- itage Very Unstable Lev- els • Measured levels are unstable and below normal over a certain period Provisioning Groundwater Qual- ity and Quantity Unstable Levels • Measured ground- water levels are below normal above a cer- tain period of time Stable Levels • Measured ground- water levels are stable up to a certain period of time Very Unstable Lev- els • Measured levels are unstable and below normal over a certain period Geothermal Re- sources Moderate Potential • There are extensive clay layers that exist between the bedrock and the ground sur- face. Good Potential • There are substan- tial clay layers that extend relatively deep between the bedrock and the surface of the ground. 16 3. Methodology Geosystem Services Label Colors Description Provisioning No Potential • It is situated near the bedrock with minimal presence of deep clay layers or obstructions. The tunnel is positioned between the ground surface and is at a depth suitable for ac- commodating energy wells. High Risk • Elevated levels of both radon and ura- nium, or the presence of activities such as gas stations that have the potential to con- taminate areas. Regulating Clean and Safe Soil Moderate Risk • There are moder- ate levels of uranium or areas that may po- tentially be contami- nated. Low Risk • There are no recorded elevated levels of uranium, and there are no areas that are potentially contaminated. 17 3. Methodology 18 4 Case Study The case study focuses on a specific tunnel section as part of a potential railway project between Järnbrott and Änggården. Figure 4.1 (Berndtsson & He, 2022) illustrates various potential routes and represents the area of study. The study area is situated in Gothenburg and extends from Radiovägen in the south to Änggården in the north. The land use within the survey area primarily consists of residential areas, although industrial areas and forests are also present along the corridor. The southern part of the area is characterized by extensive forest coverage, followed by the presence of a preschool and Flatåsskolan after Marconigatan (City of Gothen- burg, 2022a). Apart from these, the corridor mainly comprises residential areas. It is well observed in the Landuse map attached below (Figure 4.6) (Eriksson, 2015). Figure 4.2, 4.3, 4.4 shows the elevation profile of all three tunnel routes. The use of elevation profiles in tunnel construction provides critical information for alignment selection, tunnel depth determination, groundwater management, vertical clearance assessment, and ongoing monitoring. By considering the existing ground elevation and potential variations, designers can determine the minimum height required for the tunnel to accommodate vehicles, equipment, and any overhead infrastructure such as utilities or rail lines. The geosystems are assessed at the surface and at the depth where tunnels will be constructed. The soil types found in the Gothenburg area have primarily developed during the Quaternary period, which commenced around 2.5 million years ago and continues to the present day (City of Gothenburg, 2022b). The majority of these soils were formed during and after the last ice age, which started approximately 115,000 years ago and concluded around 10,000 years ago when Sweden became largely devoid of ice. During the ice age, the region was blanketed by a thick ice sheet that exerted immense pressure on the land, resulting in subsidence of the ground level (Allen, 2002). As the ice melted, a process of land uplift commenced, with the area experiencing a rise of about 2-3 mm per year. Soil type is a crucial factor to consider in tunnel excavation due to its impact on the stability and safety of the tunneling process. Different soil types possess varying properties that can influence excavation techniques, support systems, and overall tunnel design. 19 4. Case Study Figure 4.1: GIS based map of three possible railway routes. Stretches are included in the city of Gothenburg’s plan 20 4. Case Study Figure 4.2: Elevation profile of Tunnel Route 1 (Source: Google Earth) Figure 4.3: Elevation Profile of Tunnel Route 2 (Source: Google Earth) 21 4. Case Study Figure 4.4: Elevation Profile of Tunnel Route 3(Source: Google Earth) Based on Figure 4.5 (Geological Survey of Sweden, 2022e), the map depicts that soils in the coastal areas of Gothenburg are often influenced by marine deposits, with sandy and silty soils being common. These soils are relatively well-drained and are suitable for agriculture and horticulture. The archipelago and coastal zones also feature rocky outcrops and shallow soils, which provide a unique habitat for specialized flora and fauna. Moving inland, the soils are influenced by glacial activity and the subsequent land uplift. Glacial till, a mixture of clay, silt, sand, and gravel, is a prevalent soil type in the area. Glacial till soils can vary in texture, drainage, and fertility, depending on the composition and sorting of the sediment deposited by the retreating glaciers. Along river valleys, alluvial soils are found, which are formed by the deposition of sediment carried by rivers. These soils tend to be fertile and well-drained, making them suitable for agriculture. Furthermore, the presence of moraines, which are accumulations of glacial debris, contributes to the soil diversity in Gothenburg. Moraine soils can range from sandy and gravely to clay-rich, and their characteristics depend on the composition of the underlying glacial material (Knappett & Craig, 2019). 22 4. Case Study Figure 4.5: GIS Map of surface soil types along the possible tunnel routes 23 4. Case Study Figure 4.6: Land use Map of the Study Area 24 5 Results The collection of map data followed in order to visualize the potential of differ- ent geosystem services within the tunnel corridor using GIS technology. Subse- quent analyses were conducted to assess potential conflicts and synergies among the geosystem services, with consideration given to the possible construction of the tun- nel. Additionally, evaluations were carried out to determine the potential impact of the tunnel on the geosystem services. 5.1 Supporting Geosystem Services 5.1.1 Bedrock and Structure The soil is present at shallow depths except for tunnel route 2. (Figure 5.14.5). Specifically, the bedrock along the tunnel stretch comprises tonalite-granodiorite and granodiorite-granite. These rocks contain various minerals, including quartz, plagioclase, and potassium feldspar. The rock material presents an opportunity for valuable resource utilization. However, there is no national interest in extracting minerals from the area (Geological Survey of Sweden, 2021b). The quality of the rock varies slightly, but it is generally suitable for use in road construction (quality class 2), as well as for railway and concrete applications (qual- ity classes 1) (Eriksson, 2015). This means that the excavated rock material from the potential tunnel construction could potentially be utilized for these purposes. Bedrock and structural maps help in identifying favorable routes for the tunnel alignment. By analyzing the geological features, such as faults, fractures, and rock types, engineers can select the most suitable path that offers stability and min- imizes potential hazards. Bedrock and structural maps provide insights into the hydrogeological conditions and potential water inflows within the rock mass. This information assists in designing effective dewatering systems, drainage channels, and waterproofing measures to mitigate water-related risks. Rock formations with high levels of faulting, squeezing ground, or potential for rock- bursts can pose significant challenges during excavation and may require specialized engineering techniques and support systems. Identifying potential geotechnical haz- ards associated with different rock types is crucial for minimizing risks during tunnel 25 5. Results construction. Based on Figure 4.4, tunnel route 1 cuts a plastic shear zone perpen- dicularly which means the tunnel requires proper reinforcement measures, such as rock bolts, shotcrete, or steel ribs, to ensure the stability and safety of the tunnel (Bartel, 2016). Tunnel route 2 and 3 contains brittle deformation zone which is a possible risk of rockfall hazard during excavation.Rockfall hazard is a big risk if it happens during tunnel construction. This proactive approach helps in developing strategies to minimize risks and implement appropriate mitigation measures during tunnel excavation. The tunnel routes pass through igneous rock formations. Granite and Tonalite- granodiorite are considered competent rocks suitable for tunnel excavation in stable conditions. They offer good strength and integrity, which contribute to stable tun- nel walls and reduce the need for extensive support systems. However, as with any rock type, the specific characteristics of the tonalite or granodiorite deposit, such as jointing, fracture patterns, and potential weaknesses, should be thoroughly eval- uated. Figure 5.1: Map of bedrock along the possible tunnel stretches 5.1.2 Soil Depth and Bearing Capacity The soil in the area generally exhibits good bearing capacity and long-term stability, while the potential for underground storage is limited. The rock formations consist of diverse granites such as tonalite-granodiorite and granodiorite-granite, which are stable and possess favorable bearing capacity. 26 5. Results Along tunnel route 1, three deformation zones are observed: one exhibiting brittle deformation, and the other two displaying plastic deformation. In the brittle defor- mation zones, cracks and fracture zones are present in the rock, whereas the plastic deformation zones contain features like shear zones, folds, and veins (Stråhle, 2001). Additional reinforcement of the rock may be necessary in the deformation zones located in the middle and northern parts of the stretch. The surface materials along the tunnel alignment primarily consist of post-glacial clay, glacial clay, and ancient rock. As depicted in Figure 5.1 (Eriksson, 2015), all three route traverses mountainous terrain with a relatively good bearing capacity. The bearing capacity is not signif- icantly influenced by other geosystem services, although it is comparatively weaker in areas with fracture zones. Consequently, extra reinforcement might be required in the tunnel sections passing through these fracture zones due to their lower bearing capacity. Bearing capacity also depends on soil depth and soil types. Glacial clay have lower bearing capacities and are problematic due to their swelling properties. Based on Figure 4.5, 5.1, 5.2 (Geological Survey of Sweden, 2021d), and 5.3. The red zones are the sections with poor bearing capacity which are very small sections. Overall all three proposed routes are considered good in terms of bearing capacity due to the large spread of bedrock at the surface level however at entry points, there is high reinforcement cost at tunnel section 1 and 2 as compared to tunnel section 3. Tunnel section 3 has bedrock at surface so no tunnel lining will be required for shaft and tunnel opening (Fig. 4.5). 27 5. Results Figure 5.2: GIS map of the soil depth along the possible tunnel sections 5.1.3 Space for Horizontal and Vertical Construction Because all three tunnel sections are located in the subsurface of a metropolitan area, there is limited access to information regarding confidential horizontal or ver- tical constructions. Thus, it has been challenging to gather data on underground structures. Although no public information is available on known horizontal con- 28 5. Results structions like tunnels, it is reasonable to assume the presence of piling in areas with deep clay layers to support large buildings. Tunnel route 1 and 2 have clay with greater soil depth in southern portions and the piling likely extends to the bedrock at its deepest point 4.55.2. As there is a lack of information on subsurface construc- tions, it is difficult to determine potential conflicts with other existing geosystem services s. However, conflicts between underground structures and utilities such as wires, cables, and pipes could arise as a significant concern especially at entry and exit of all tunnel routes otherwise the tunnels corridors goes much deeper than the space for horizontal pipes and wires. Coordination with local utility providers must be ensured before tunneling considering the need for future expansion of the utility services. If the tunnel is constructed, space conflicts could likely arise if there are plans to build additional underground structures at the same depth. The presence of the tunnel could impede the construction of other structures in that area. As a result, any new horizontal or vertical constructions would need to be adjusted to accommodate the existing tunnel. They may be built either above or below the tun- nel to avoid interference and ensure proper functionality of both the tunnel and the additional structures. This adaptation is necessary to optimize the use of space and minimize conflicts between the tunnel and any future underground developments. 29 5. Results Figure 5.3: The figure reports the overall load-bearing capacity of rocks 30 5. Results 5.1.4 Space of Utilities (Wire, cables, pipes) Typically, lines, cables, and pipes are situated within the uppermost layers of clay and at relatively shallow depths ranging between 1 to 7 meters. Based on Figure 4.1, which indicates that the tunnel section extends deeper than 7 meters and passes through mountainous terrain, it can be inferred that there are no wires, cables, or pipes present in the potential tunnel construction area. At all proposed tunnel en- tries and exits, there are a few electrical wires and cables which must be taken care of during construction. These wires are at shallow depth however tunnel construction is initiated at the surface. Proper planning, risk assessment, and proactive measures are essential to minimize potential damage and ensure the continued operation of utility lines, cables, and pipes in the vicinity of the tunnel. However, it is important to consider the potential impact on existing lines, cables, and pipes after the tunnel is built. Careful monitoring and mitigation measures would need to be implemented to prevent such subsidence-related damage and ensure the integrity of the lines, cables, and pipes. 5.1.5 Underground storage The bedrock along tunnel route 1, as indicated in Figure 5.1, is composed of granite, which is a metamorphic rock. Granite, being a crystalline and relatively imperme- able rock, does not possess the necessary high porosity typically found in sedimen- tary rocks that are suitable for underground storage of substances. Therefore, the bedrock in the area does not offer favorable conditions for underground storage. Similarly, the rocks along the tunnel section of routes 2 and 3 are also impermeable and less porous rock with no utilization for storage purposes. So in this context, the surroundings of all three routes do not possess the capability of underground storage. Considering this, the potential for underground storage in the area would not be affected by the construction of a tunnel. The unsuitable properties of the bedrock, such as low porosity, make it impractical for underground storage regardless of tunnel construction. 5.2 Cultural Geosystem Services The tunnel line’s 1 known cultural heritage encompasses two stone deposits, which hold significance as they represent cultural elements from prehistoric times. These stone deposits consist of both large and small stones. However, it’s important to note that there could potentially be undiscovered cultural heritage sites in the vicinity of the proposed railway route, as indicated in Figure 5.2. According to the Fornsök database, there are records of two possible cultural heritage sites along tunnel line 1: a potential archaeological find site and a potential rock carving (National Museum of Natural History, 2021). The presence of both known and potential cultural heritage sites raises the possi- 31 5. Results bility of conflicts when considering construction activities such as building facilities, underground constructions, or laying pipes and cables along the railway route. These conflicts may arise due to the need to balance infrastructure development with the preservation of these heritage sites. Decisions regarding how to proceed with con- struction in these areas must carefully weigh the importance of preserving cultural heritage against the necessity of infrastructure development. This often involves consultations with cultural heritage authorities, archaeologists, and other relevant experts to find solutions that minimize the impact on these valuable historical sites while still meeting the project’s objectives (Norrman et al., 2021a). 5.2.1 Known and Unknown cultural heritage It’s reassuring to hear that the construction of the railway section is not expected to bring about significant changes to the known cultural heritage, particularly because these heritage sites are situated on the ground surface. However, the possibility of undiscovered cultural heritage sites is acknowledged, although the likelihood of encountering such sites is considered limited. This understanding underscores the importance of conducting thorough surveys, as- sessments, and monitoring during the construction process. By employing careful planning, archaeological assessments, and adherence to cultural heritage preserva- tion protocols, it’s possible to mitigate the impact on any unknown cultural heritage sites that may be encountered. This approach allows for responsible development while safeguarding the potential historical and archaeological significance of the area. 5.2.2 Geological heritage The area where the railway is planned to run does not appear to have any particularly unique or unusual soil or rock types, as indicated in Figures 4.5 and 5.1. Similarly, the soil types found in the area are also typical and commonly found throughout Sweden. However, it’s worth noting the presence of a geotope, specifically a sandstone pas- sage, in relatively close proximity to the tunnel section, as depicted in Figure 5.4. Sandstone is not typically considered a geotope, suggesting that this feature may have some unique or distinctive geological characteristics compared to the surround- ing granite and soil formations (Geological Survey of Sweden, 2021c). Further ge- ological investigation and assessment may be necessary to better understand the significance of this sandstone passage in the context of the railway project. If the tunnel route 1 construction takes place, the geological heritage will be damaged due to the blasting operation. Controlled blasting or the use of tunnel boring machines for the construction of tunnels, it is possible to save some of these heritages. Tunnel route 2 and 3 are safe to construct in this specific concern. 32 5. Results Figure 5.4: Map of geological heritage along the tunnel stretches 33 5. Results 5.3 Regulating Geo-system Services 5.3.1 Geo-Energy According to Figure 5.5, there is a notable presence of energy wells in the area, indicating a potential good for utilizing geo-energy along the entire stretch of the tunnel. This is attributed to the relatively close proximity to the bedrock without extensive layers of clay above it. So using Figures 5.5 and 5.6, a potential for utilization of geo-energy is estimated using GIS. The maps in Figure 5-6 show the quality of Geoenergy along the tunnel routes and also highlight the present geo- energy wells (Geological Survey of Sweden, 2021e). However, conflicts can arise when energy wells intersect with underground construc- tions or with existing lines, cables, and pipes. In the case of constructing the tunnel, the existing energy wells that fall within the tunnel’s path would likely need to be relocated or decommissioned. Additionally, drilling wells vertically to a depth of 200m or greater can be challenging, raising the possibility of nearby wells being affected due to the construction activities The problem is more prominent along tunnel routes 1 and 2, however, tunnel route 3 has drill well with depths less than 200m. Moreover, Figure 5.5 indicates that it would be impractical to utilize geo-energy with wells located above the tunnel. The difficulty in drilling wells completely straight into the ground also poses challenges for utilizing geo-energy in close proximity to the tunnel. Considering these factors, the construction of the tunnel would likely require addressing the presence of existing energy wells along the tunnel route and carefully evaluating the potential impact on nearby wells. Furthermore, utilizing geo-energy near the tunnel may face limitations due to drilling constraints and potential disruptions caused by the tunnel construction. Construction activities may have environmental impacts, such as soil disturbance, which could affect the surrounding area and potentially impact the groundwater quality or contaminate energy well sites. Energy wells may limit access to certain areas for construction equipment and workers. Coordination is needed to ensure access requirements for both construction and energy maintenance are met. Devel- oping effective mitigation strategies to address conflicts, such as reinforcing energy well protection, can be challenging but necessary to resolve conflicts without com- promising energy supply or construction progress. To manage these conflicts effectively, careful planning, collaboration between energy providers and construction teams, thorough risk assessments, and compliance with relevant regulations are essential. It is crucial to prioritize the safety and function- ality of energy infrastructure while meeting the infrastructure needs of the project. 34 5. Results Figure 5.5: Map showing the present energy wells with color depicting error in position 5.3.2 Clean and Safe Soil According to Figure 5.7, the uranium content along the tunnel cover does not appear to be particularly high. However, the rock in the Änggården area, which is situated after the tunnel corridor, contains an elevated level of uranium. This is noteworthy 35 5. Results (a) (b) Figure 5.6: This figure reports the quality of geo-energy and where existing energy wells are located. The map is based on figure 5.1, 5.3 and 5.5 36 5. Results because granite, the type of rock found in Änggården, is known to have relatively high levels of uranium, as indicated by the Swedish Geological Survey in 2022. The risk of radon gas exposure varies along the route, initially ranging from low to normal. Generally, the radon risk is classified as low, but there is a high-risk area in Änggården. The source map was not available so this information is gathered from the literature review. Figure 5.8 serves as the basis for identifying potentially contaminated areas. The risk identification is based on using the Methodology for Inventorying Contaminated Areas (MIFO method). It is shown as very high, high risk, moderate risk, and low-risk pollution areas. The areas with no risk are also mapped in Figure 5.8. Figure5.8 serves as a contamination map for the risk assessment of pollution of soil in the vicinity of tunnel stretches. This information highlights the importance of considering uranium and radon risks in the construction and planning of the tunnel, particularly in areas with elevated levels (Geological Survey of Sweden, 2022f). Mitigation measures and safety proto- cols should be in place to address potential health and safety concerns associated with radon exposure and uranium content during the construction and operation of the tunnel. The soil and rock in the area are generally considered to have good potential in terms of being clean and safe. According to Figure 5.5, there are only three locations along the tunnel stretch where potential contamination is a concern. But 5.9 shows that soil along tunnel route 2 and 3 are at very high risk of contamination due to presence of high risk contamination.. Tunnel route 1 is safe along maximum path of route. These areas are believed to be contaminated due to various activities that have taken place along the tunnel route. Specifically, the contamination is associated with two dry cleaners and a former gas station (Eurofins, 2017). 37 5. Results Figure 5.7: Uranium content map along the tunnel stretch (SGU Website) 38 5. Results Figure 5.8: GIS Map of the potential pollution along the possible tunnel routes The pollutants that pose the greatest risk of spreading in this context are chlori- nated hydrocarbons, which are commonly used as detergents in dry cleaners. These 39 5. Results hydrocarbons are characterized by their liquid nature and their limited ability to dissolve in water (Eurofins, 2017). The potential for pollutant spread depends on several factors, including the char- acteristics of the soil and rock layers. When pollutants that are water-soluble are released onto a thick layer of soil, this layer can act as a barrier, preventing con- tamination from reaching deeper groundwater reservoirs. However, when pollution occurs on a thin layer of soil with underlying rock, the contamination may have a more direct pathway to reach the groundwater, especially through cracks in the rock. Chlorinated solvents, in particular, have the ability to penetrate deep into the ground due to their heavy nature compared to water. In the case mentioned, where dry cleaners are situated on a thin layer of soil with a maximum depth of five meters (as per soil depth map Figure 5.3), there is a risk of groundwater contamination. These chlorinated solvents can potentially seep into the bedrock and spread to considerable depths, reaching up to a hundred meters or even farther, depending on the extent of the release (Körner & Wahlgren, 2015). Furthermore, during tunnel construction, there is a risk of mobilizing and spreading pollutants. This can occur when groundwater or even chlorinated hydrocarbons are drained into the tunnel, potentially leading to further contamination concerns. Given the potential risks associated with these pollutants, careful planning, envi- ronmental assessments, and appropriate mitigation measures are essential to protect groundwater quality and prevent the spread of contaminants during and after tunnel construction. Figure 5.9 shows the potential of pollution spread along the tunnel stretch. Based on the figure, it is assumed that tunnel routes 2 and 3 are more prone to pollution spread as compared to tunnel route 1. Because high-risk pollution areas are present near these tunnel routes. If tunnel route 2 and 3 are constructed, protective lining should be installed to ensure safety against contamination which a big economic concern for the project. 40 5. Results Figure 5.9: Risk potential of pollution spread along the possible tunnel routes The current situation presents several potential conflicts between pollution and other geosystem services, primarily related to the spread of contamination. Here are some 41 5. Results key points highlighting these conflicts: • Spread of Pollution: One of the primary concerns is the potential spread of pollution, especially during tunnel construction. Blasting rocks with high levels of radon can release this radioactive gas into the surrounding environ- ment, posing risks to the health and safety of individuals working on the tunnel project. Contaminated air can also affect nearby communities. • Impact on Geomaterial Reuse: Contaminated geomaterials, such as rock and soil, may have limited potential for reuse, especially in construction projects. The presence of pollutants can hinder the use of these materials as building materials or for other purposes, affecting the sustainability and efficiency of construction projects in the area. • Changes in Rock Quality: The construction of the tunnel may alter the quality of the rock in several ways. For instance, pollution risks may increase after tunnel blasting, particularly in areas like the mountain near Änggården where radon levels are high. Additionally, the transportation and deposition of blasted rock masses may lead to changes in the distribution of rock containing uranium and radon, potentially affecting the geosystem. • Mobilization of Chlorinated Hydrocarbons: During tunnel construction or if the tunnel is not adequately sealed, there is a risk that chlorinated hy- drocarbons, which may be present due to prior activities in the area (e.g., dry cleaners), could be mobilized and spread. This can have adverse effects on groundwater quality and environmental health. To address these conflicts and mitigate their impacts, it’s essential to imple- ment comprehensive risk assessment, management, and prevention strategies (Kuchler et al., 2024). This may include: – Rigorous monitoring of air quality during and after tunnel blasting. – Proper disposal and containment of contaminated geomaterials. – Ensuring the tunnel is well-sealed to prevent the spread of pollutants. – Implementing effective measures to prevent the mobilization of chlori- nated hydrocarbons. – Continual groundwater monitoring to detect any contamination risks. Additionally, strict adherence to environmental regulations and safety proto- cols is imperative to minimize the adverse effects of these conflicts on both human health and the surrounding environment. 42 5. Results 5.3.3 Water Retention The water retention capacity of the soil layers along the intended railway route is considered to be moderate. This assessment takes into account the geological characteristics of the area as depicted in Figures 4.5, 5.1, and 5.3. The predominant features of the area include hard surfaces, rocks exposed at the surface during the day, connecting postglacial sand or moraine, and deep clay layers. In areas with natural soil, postglacial sand, and moraine, it is assumed that the water retention capacity is sufficiently good to retain moderate amounts of water (Geological Survey of Sweden, 2022c). This information suggests that the geological composition of the region is such that it can retain a reasonable amount of moisture, which is important for managing groundwater and surface water in the context of railway construction. It’s essential to consider these characteristics when planning drainage systems, erosion control measures, and other aspects of infrastructure development to ensure effective water management along the railway route. The soil type known as "friction soils" is noted for its significantly better water retention capacity compared to clay and hard surfaces (Knappett & Craig, 2019). However, there is an interesting dynamic at play here. Despite having good water retention abilities, the poor permeability of clay makes it difficult for friction soils’ water retention capacity to be fully utilized. In other words, the water held by the friction soil cannot easily penetrate or flow through the adjacent clay layers. To optimize the water retention capacity of the area and potentially enhance the geosystem services related to water management, the presence of pipelines, conduits, cables, and pipes that have been buried in the region can be leveraged. If these in- frastructure elements are designed with proper drainage systems, they can facilitate water infiltration into the ground and channel excess water away from the area. It’s worth noting that the overall water retention potential of the area is assessed as moderate. Even if a tunnel is constructed in the future, this assessment is unlikely to change significantly. Tunnels are typically not completely sealed, and they may have some level of permeability that allows water to pass through. This feature could potentially contribute to managing water bursting within the tunnel and preventing excessive water buildups insite the tunnel corridor. In summary, understanding the complex interplay between different soil types, permeability, and infrastructure can help optimize water retention and drainage in the area. Leveraging buried infrastructure with proper drainage systems can be a valuable strategy for managing water resources effectively. 5.3.4 Water Filtration Capacity The water filtering capacity along the possible tunnel route 1 is assessed as poor. This assessment is based on the geological characteristics of the area, as described in Figures 4.5, 5.1 and 5.3. 43 5. Results The primary geological features of the area include hard surfaces, exposed rocks, and clay. These materials are known for their very low permeability, which means that they do not allow water to pass through easily (Eriksson, 2015). Additionally, the presence of thick clay layers further exacerbates the poor filtration capacity (Geological Survey of Sweden, 2021d). One potential conflict in the area is the presence of buried pipelines, cables, wires, and pipes. These buried infrastructure elements can have a negative impact on natural infiltration, which, in turn, worsens the already poor water filtering ability. The presence of such infrastructure can restrict the movement of water through the soil and rock layers (Geological Survey of Sweden, 2022e). It’s important to note that if a tunnel is constructed in the future, it is unlikely to lead to a significant change in the water filtering ability of the area. This is because the natural permeability of the geological materials in the region is already very low. Given the poor water filtering capacity, managing water resources effectively in the area is challenging. Mitigation measures, such as proper stormwater management, drainage systems, and erosion control, should be carefully planned and implemented to address potential water-related issues during railway construction and operation. Additionally, minimizing further disruptions to natural infiltration caused by buried infrastructure is essential to maintain the area’s hydrological balance. Tunnel route 3 is also poor in terms of water filteration capacity due to bedrock at the surfece. Tunnel route 2 has good water filteration due to presence of soils, sandy soils of greater depths (Fig. 4.5, 5.1, 5.3). 5.4 Provisioning Geo-system Services The available geosystem services in the area are underutilized, with only one ser- vice, groundwater, being indirectly used. This service is employed to maintain pore pressure and prevent clay settlement. However, the utilization of other geosystem services in the area is limited for several reasons: • Limited Potential: Some geosystem services may not have the potential to be effectively utilized in the specific geological and environmental conditions of the area. For example, if the natural conditions do not support the reliable use of a particular service, it may not be feasible to employ it. • Financial Sustainability: The implementation of certain geosystem services may require significant groundwork, investment, and ongoing maintenance. If the cost of implementing and maintaining a service outweighs the benefits it provides, it may not be financially sustainable for the project. • Environmental Constraints: Environmental considerations, such as poten- tial ecological impacts or regulatory restrictions, can limit the use of certain geosystem services. These constraints may discourage or prohibit the utiliza- 44 5. Results tion of specific services. • Technical Challenges: Some geosystem services may pose technical chal- lenges that make their implementation complex or unfeasible given the avail- able resources and expertise. It’s important to carefully evaluate the feasibility and benefits of utilizing geosystem services in any project. While some services may be underutilized in the area, the decision to use or not use them should be based on a comprehensive assessment of factors such as cost-effectiveness, envi- ronmental impact, technical feasibility, and project objectives. In some cases, alternative strategies or technologies may provide more practical solutions to address the project’s needs and challenges. 5.4.1 Geothermal Energy The potential for geothermal energy in the area is relatively poor due to the thick crust in Sweden, which requires very deep drilling to access geothermal heat. As of now, there are no facilities extracting geothermal energy along the tunnel stretch, and therefore, there are no conflicts affecting geothermal energy in the area. In Gothenburg, there is a trial planned for a geothermal energy system, which is investigating the depth required for accessing geothermal energy. It’s important to note that a tunnel constructed along the potential route may restrict the ability to build geothermal energy wells directly above or near the tunnel. Drilling straight down through the tunnel may not be feasible or practical (B. Andersson, 2022) (Geological Survey of Sweden, 2022b). As a result, geothermal energy boreholes will need to be drilled in alternative lo- cations to utilize this geosystem service effectively. This underscores the need for careful planning and coordination when considering the construction of tunnels and their potential impact on the development and use of renewable energy sources like geothermal energy (Geological Survey of Sweden, 2022b). Ensuring that infrastruc- ture projects do not impede opportunities for sustainable energy generation is an important aspect of responsible planning and development. 5.4.2 Drinking and Process Water Resource The use of groundwater as a resource for drinking water or industrial processes along the tunnel stretch is currently minimal, with no groundwater wells near the stretch. The geological conditions, as indicated in Figure 5.10, suggest that the area contains smaller groundwater reservoirs rather than large ones. Consequently, the potential for using groundwater as a drinking or process water resource for municipal systems is very low in the area. While there might be some potential for individual wells, the urban environment in the area typically discourages such practices. Furthermore, the utilization of groundwater as a geosystem service is essentially non-existent along the route. Groundwater quality could be at risk in areas where contamination potential exists. 45 5. Results If the tunnel is constructed, several changes may occur regarding the use of ground- water: • Deterioration of Drinking Water Potential: The construction process, which may involve blasting away rocks, could potentially disrupt groundwater collection in fracture systems. This disruption could reduce the already limited potential for using groundwater as a source of drinking water. • Increased Drainage: Tunnels are challenging to make completely watertight. As a result, the tunnel construction could lead to the drainage of water from the surrounding geological formations into the tunnel. This may further reduce the availability of groundwater resources in the vicinity of the tunnel. • Impact on Water Quality: The tunnel construction process and the po- tential for contamination in the area may have implications for groundwater quality. Careful management and monitoring of water quality are essential to mitigate any adverse effects. Given the low potential for using groundwater as a resource in the area, the pri- mary focus should be on minimizing any negative environmental impacts related to groundwater quality and availability during and after tunnel construction. Addi- tionally, it’s important to consider alternative sources of water for municipal and industrial needs in the region to ensure a sustainable water supply. 5.4.3 Ground Water Resource In Chapter 5.4.2, it is noted that the groundwater reservoirs in the area are rel- atively small and not directly utilized by humans for consumption or industrial processes. Instead, groundwater indirectly contributes to various functions, includ- ing providing stability through pore pressure (as discussed by Tremblay in 1990). While plants and animals in the region primarily rely on surface groundwater, some of the precipitation seeps down and becomes stored as groundwater. The groundwater situation, as presented in Figure 5.10 and documented by (Hjerne, 2021), varies along the length of all three tunnel routes at the southern part. Ground- water levels are within the normal range at the beginning and end of the stretch but fall below the usual levels in the middle. It is crucial to actively maintain groundwa- ter levels, primarily to mitigate the risks associated with subsidence, as emphasized by the Swedish Geological Survey (Geological Survey of Sweden, 2022c). The presence of buried lines, cables, and pipes may have a slight impact on the groundwater resource as these can potentially drain water away. Furthermore, there is a potential risk that the groundwater resource could deteriorate after the tunnel’s construction due to a lowering of groundwater levels. To address this concern, it is imperative to ensure that the tunnel is adequately sealed to prevent water drainage. This issue requires careful consideration and proactive measures, as a declining groundwater resource can lead to settlement problems, particularly in the 46 5. Results middle of the stretch where groundwater levels are already lower than usual. The instability of groundwater levels due to tunneling refers to fluctuations or changes in the depth and behavior of groundwater within an area caused by the con- struction and operation of tunnels. This instability can have various consequences and impacts on both the environment and the tunneling project itself. During tunnel construction, the excavation process can disrupt the natural flow of groundwater. As tunnels are dug, the surrounding geological formations may be disturbed, poten- tially causing shifts in groundwater levels and flow. Figure 5.11 shows the stability of current groundwater levels along the tunnel routes. Figure 5.12 shows the insta- bility in groundwater levels after tunnel construction based on figures 4.5, 5.1, and 5.3. Rock permeability is an important factor in changing GW levels. The blasting during tunnel construction propagates present fractures and creates new openings in the rocks, this results in a prominent change in groundwater level after construc- tion. Legal obligations in country code should be follow to reduce these risks during construction. The instability of groundwater levels due to tunneling is a complex issue that re- quires careful planning, monitoring, and mitigation efforts to ensure the safety of the tunnel, protect the environment, and minimize any adverse impacts on the local hydrogeology. 47 5. Results Figure 5.10: Map showing groundwater storage capacity along the possible tunnel routes 48 5. Results Figure 5.11: GIS based Map of Ground water stability levels before tunnel construction based on 4.5, 5.1 and 5.10 49 5. Results Figure 5.12: GIS based map of Groundwater levels after tunnel construction based on 4.5, 5.1, 5.10 50 5. Results 5.4.4 Minerals and Geomaterials According to Figures 4.5 and 5.1, the material that the potential tunnel routes will traverse is composed of rock. Specifically, the bedrock along the tunnel route 1 consists of tonalite-granodiorite and granodiorite-granite. These types of rock contain various minerals, including quartz, plagioclase, and potassium feldspar, as documented by the Naturhistoriska Riksmuseet in 2021. This rock material holds the potential to serve as a valuable resource. However, it’s important to note that there is no national interest in mining the minerals found in this area, as indicated by the Swedish Geological Survey (Geological Survey of Sweden, 2022d). The quality of the rock may vary slightly, but it is predominantly suitable for use in road construction (quality class 2), railway construction (quality class 1 and 2), and concrete production (quality class 1), as determined by the Swedish Geological Survey in 2000. Therefore, there is indeed the possibility of utilizing the excavated rock material in the event of tunnel construction. In summary, the rock material in the area offers the potential for reuse and utilization in various construction applications, aligning with the quality standards set for road, railway, and concrete projects. This consideration can be valuable in the planning and sustainability aspects of potential tunneling activities. The material encountered in the remaining part of the tunnel section is assessed to be of high quality, and the excavated rock material resulting from blasting can be effectively repurposed and put to good use. This presents a valuable synergy or advantage in the project, as it allows for a reduction in the need to extract rock material from either an existing quarry or a newly constructed one (Geological Survey of Sweden, 2021c) (Geological Survey of Sweden, 2021b). Tunnel route 2 is almost in the same situation as tunnel route 1 according to 5.1 but some of its part is passing through Granite which is a competent rock and used as a construction material (quality class 1). So this is an economical resource. The entire Tunnel route 3 is passing through granite which offers the potential for reuse and utilization in various construction projects, fulfilling the quality standards set for road, railway, and concrete projects. In other words, the high-quality rock material is found during tunneling of all routes can serve as a sustainable resource that minimizes the environmental impact of quarrying operations. This practice aligns with principles of resource efficiency and environmental conservation by reducing the demand for new excavation sites and conserving natural resources. It also contributes to the overall sustainability and cost-effectiveness of the tunnel construction project. 5.4.5 Multi-criteria Analysis An impact assessment of the tunnel route alternatives on geosystem services is shown in Table 5.1. A multicriteria analysis method was applied to evaluate the effects. 51 5. Results The scale used represented impact strengths in a qualitative manner using emojis: GOOD captured positive influence, NOT GOOD signified negatives, with NEU- TRAL and QUESTION MARK denoting neutral/uncertain consequences. This ap- proach provided a uniform means to compare each route’s projected impacts across geosystem services. The table that follows presents the outcomes of the analysis, with theemoji scale visually portraying the determined impact classification for each route-service pairing. Table 5.1: Geo-system services assessment with Multi Criteria Analysis (MCA) Geosystem Services Type of effect Corridor 1 Corridor 2 Corridor 3 Effect de- scription Effect scale Effect de- scription Effect scale Effect de- scription Effect scale Social It is expected less traffic, less noise, less acci- dents etc. There will be more traffic due to the highway cross- ing overhead. More noise and vibrations. Relatively low traffic, but more noise and vibrations. Supporting Service Stable platform to build on and within Environmental No need to transport a lot of material for reinforcement, not much emissions compared to the base case of ‘do nothing’. More rein- forcement material will be required, hence, more emissions. Less reinforce- ment material will be required and less emis- sions. Economical There is no need for substantial reinforcement that is associ- ated with large costs. Great rein- forcement is required to stabilize the surface structures and buildings. There is no need for substantial reinforcement that is associ- ated with large costs. Social Longer com- mutes, reduced access to public traffic Shorter com- mutes, reduced traffic, and in- creased access to other public transports. Reduced access to public trans- port and com- munities Supporting Service Underground space for construction Environmental Increased underground construction can affect nat- ural diversity and the local ecosystem. Due to the presence of al- ready existing structures on the surface, less effect on natural diversity and ecos