Master Thesis TVVR 19/5011 Flooding at Karlshamnsverket Analysis and Recommendations ________________________________________________ Daniel Wirtz Division of Water Resources Engineering Department of Building and Environmental Technology Lund University Flooding at Karlshamnsverket Analysis and Recommendations By: Daniel Wirtz Source: Mynewsdesk (2019) Master Thesis Division of Water Resources Engineering Department of Building & Environmental Technology Lund University Box 118 221 00 Lund, Sweden Water Resources Engineering TVVR-19/5011 ISSN 1101–9824 Lund 2019 www.tvrl.lth.se Master Thesis Division of Water Resources Engineering Department of Building & Environmental Technology Lund University Title: Flooding at Karlshamnsverket - Analysis and Recommendations Author: Daniel Wirtz Supervisor: Magnus Larson Assistant supervisors: Bo Martinsson & Johan Thomsson Examiner: Rolf Larsson Language English Year: 2019 Keywords: Karlshamnsverket, Blekinge, flooding, drainage pipe system, mitigation measures, extreme value analysis i ii Acknowledgements This work would not have been possible without the help of a large number of persons. Thus, i would like to thank: My father and my mother for always supporting and believing in me. My supervisor, Prof. Dr. Magnus Larson, for his guidance and advices throughout the thesis project, around the clock when needed. Without his invaluable support and input this study would not have been half as good. My assistant supervisor, Bo Martinsson, for his patience, support and essential inputs throughout the thesis project, providing me with whichever information I needed about the area as long as it was available. Everybody at Karlshamnsverket, notably: • The employees in the maintenance department for their continuous support, may it be help when i needed it, additional information or working material. Special thanks are given to Henrik Pagels for enabling me to do this master thesis and to Johan Thomsson for his organizational guidance, as well as to Benny Thuresson for his help with the pipe systems investigation. • The employees in the laboratory for helping me out with Conductivity and pH measurements. • The employees in the operation department for helping me whenever needed, especially Torbjörn Ericson for providing me with groundwater data and information about the rock caverns. Caroline Hallin and Johanna Sörensen at the Department of Water Resources Engineering, Lund University, for guiding me through necessary statistics and deepening my understanding of coastal processes. Jan-Erik Rosberg at the Department of Technical Geology, Lund University, for his guidance concerning the construction of boreholes, as well as Gerhard Barmen for his insights in groundwater questions. Additionally, I would like to thank Peter Jonsson and Conny Svensson for their additional input concerning specific questions I had. Per Nyström, visiting lecturer at the Department of Biology, Lund University, for identifying a frog and clarifying at which salt concentrations it can survive. Per Johan Gustafsson, Professor at the Department of Construction Sciences, Lund University, for his advice on determining the instability of fill. iii iv Abstract Karlshamnsverket is a power plant located at the Baltic Sea in southern Sweden. Due to the coastal location this important infrastructure already experienced flooding in its basement in the past. The objective of this study is to conduct an initial analysis to determine the underlying reasons for the flooding and to provide suitable measures to increase the resilience of the power plant, also with regards to the future. For that reason, an initial analysis of sea water levels and rainfall data was performed and altered for a prospective climate scenario. Further information was gathered from measurements, original construction documents and literature to obtain a better understanding of the hydro(geo- )logical situation in the area. Based on this information suggestions were developed. Recommendations also include a maintenance plan for the drainage pipe system, developed after international standards. Flooding in the basement mostly stems from the stormwater pipe system, which is susceptible to high water levels in the surge basins and downpour events. Flooding is to be expected frequently and thus it is recommended to alter the current pipe system layout. Significant surface flooding of the power plant area, that constitutes a fill made of friction soil and blast rock, is unlikely. Most of the fill surface is located 265 cm above mean sea level, while the highest water level to be expected is 233 cm in the year 2100. Sea water is instead thought to enter the fill through a permeable seawall, which needs to be confirmed by constructing observation wells. v vi Sammanfattning Karlshamnsverket är ett kraftverk som ligger vid Östersjön i södra Sverige. På grund av placeringen vid kusten har denna viktiga infrastruktur redan tidigare varit utsatt för översvämningar i källaren. Syftet med föreliggande studie är att genomföra en första analys för att fastställa de bakomliggande orsakerna till översvämningarna och att föreslå lämpliga åtgärder för att öka kraftverkets motståndskraft, även när det gäller framtida förändringar i olika påverkansfaktorer. Av den anledningen utfördes en första analys av havsvattennivåer och nederbördsdata med hänsyn till möjliga förändringar vid olika framtida klimatscenario. Bakgrundsinformation samlades in från mätningar, ursprungliga konstruktionsdokument och litteratur för att få en bättre förståelse för den hydro(geo-)logiska situationen i området. Baserat på denna information utvecklades förslag till åtgärder. Dessa rekommendationer inkluderar också en underhållsplan för dräneringssystemet, utvecklat efter internationella standarder. Översvämningarna i källaren härrör mestadels från dagvattensystemet i samband med skyfall; detta system påverkas också av höga vattennivåer i svallbassängerna som i sin tur bestäms av havsvattennivån. Översvämningar kan förväntas ske oftare i framtiden och därför rekommenderas det att ändra den aktuella layouten av rörsystemet. Betydande översvämning av kraftverkets område, som utgör en fyllnad av friktionsjord och sprängsten, är osannolik. Det mesta av fyllningsytan ligger 265 cm över medelvattenytan, medan den högsta vattennivån som kan förväntas är 233 cm år 2100. Havsvattnet antas istället komma in i fyllnaden genom en permeabel jordvall, vilket dock måste bekräftas genom att konstruera observationsbrunnar och genomföra mätningar. vii viii Table of contents Acknowledgements ........................................................................................ iii Abstract ............................................................................................................ v Sammanfattning............................................................................................. vii Table of contents ............................................................................................. ix 1. Introduction .................................................................................................. 1 1.1 Background and Problem Formulation .................................................. 1 1.2 Goals and objectives ............................................................................... 3 1.3 Limitations.............................................................................................. 3 2. Methodology ................................................................................................ 5 2.1 Literature Study ...................................................................................... 5 2.2 Review of available site documentation ................................................. 5 2.3 Data compilation and analysis ................................................................ 5 2.4 Field measurements and tests ................................................................. 6 2.4.1 Field measurements and inspections ............................................... 6 2.4.2 Tracer test ........................................................................................ 6 3. Overview over the power plant .................................................................... 9 3.1 General ................................................................................................... 9 3.2 Description of the power plant ............................................................. 10 3.3 Description of the basement ................................................................. 12 3.4 Flooding problem ................................................................................. 15 4. Drainage systems for near-coastal large-scale installations ....................... 19 4.1 Coastal flooding and landward inflow ................................................. 19 4.2 Evaluating and coping with flooding and inflow ................................. 21 4.2.1 Evaluation ...................................................................................... 21 4.2.2 Coping with flooding..................................................................... 22 4.3 Construction and Maintenance of drainage systems ............................ 22 4.3.1 Construction of near coastal drainage systems.............................. 22 ix 4.3.2 Maintenance of drainage system ................................................... 23 5. Study area ................................................................................................... 27 5.1 Geography