Hydrogeologisches Konzeptmodell von München: Grundlage für die thermische Grundwassernutzung

The Munich Gravel Plain has been studied under various aspects, but there has been no detailed hydrogeological underground model of the entire city area. As a result of the ??urban heat-island?? effect, groundwater temperatures reach 18?°C and locally exceed 20?°C. This aquifer is therefore suitable for systematic and large-scale near-surface geothermal energy exploitation. The goal of this study was to establish the first detailed hydrogeological model of the city of Munich, as a basis for estimating the geothermal potential. A database of more than 20,000 drill holes was available, of which 730 were selected, interpreted and processed. As a result, 26 east-west cross sections were constructed, showing the geometry and structure of the aquifer and the position of the unconfined water table during low, average and high-water conditions. Based on these profiles and basic hydraulic considerations, a groundwater flow rate of about 3?m³/s was established. Results of this study indicate a high potential for thermal groundwater use and corresponding reductions of heating oil consumption and CO₂ emissions. At the same time, thermal rehabilitation of the overheated urban groundwater could be achieved. The quantification of this geothermal potential and the space-time optimisation of thermal groundwater use for heating and cooling require a detailed analysis of groundwater temperatures and numerical groundwater flow and heat transport modelling.     

Geophysik für die hydrogeologische Praxis

Ohne Zusammenfassung     

FCKW als Tracer für die Ausbreitung von Altablagerungsemissionen im Grundwasser

Emissions from abandoned waste disposal sites into groundwater are difficult to trace further downstream because of their complexity. Typical tracers, for example, like chloride, boron and sulphate are likely to be influenced by several factors like saline waters, emissions from seepage pits and leaky sewers. These types of components are therefore not suitable to characterise groundwater contamination caused by abandoned waste disposal sites; they will thus not be further discussed in this paper. However, due to their special geochemical properties like negligible absorption and degradation rates, chlorinated fluorocarbons, especially difluoro-dichloromethane (F12), which are frequently emitted from abandoned waste disposal sites, are particularly suitable for the detection of maximum contaminant emissions to groundwater. These elements are crucial for the assessment of groundwater contamination and the employment of natural attenuation as a remediation measure.     

Additive Fertigung mit Beton – Leitfaden für die Planung und die Durchführung von Projekten

Additive manufacturing with concrete – guidance for planning and implementation of projects This guideline, created by the DAfStb Working Group “Digital Concrete Construction through Additive Manufacturing,” serves as a comprehensive resource to support the planning and implementation of additive manufacturing projects in concrete construction. It is intended for architects, planners, applicants, material manufacturers, construction companies, and other parties involved in construction. After a brief introduction to the classification, terminology, and methods of additive manufacturing, legal aspects and approval procedures are highlighted to ensure seamless integration of this technology into construction practice. The guide addresses the integration of additive manufacturing methods with concrete into construction law, explains the approval process, and offers assistance for coordinating responsibilities in projects. It addresses technical rules for the design and construction of structures, particularly for walls produced by additive manufacturing, and covers constructive aspects of reinforcement. An important component is concrete and component testing, including methods for sample preparation and testing procedures for fresh and hardened concrete, making the guide a useful tool for professionals in the field of digital concrete construction.     

Erhebungsmethoden von Kluftparametern für eine stochastische Kluftnetzgenerierung

This paper summarizes evaluation strategies and statistical methods to generate stochastic fracture networks used for the quantitative risk assessment of the subsurface storage of industrial residues in coal mines by means of numerical models. The well known length bias of observed fracture trace lengths could be directly corrected by fitting the Erlang-2-distribution to empirical fracture data obtained by scanline sampling. The geostatistical analysis of fracture spacing did not yield any spatial correlation for the investigated field scale. The latter fact in combination with the more or less observed relative constant orientation of preferred discontinuity orientations confirm the chosen approach of stochastically generated fracture networks.     

Direct-Push-Technologien – Effiziente Untersuchungsmethoden für die Untergrunderkundung

About ten years ago, Direct Push technologies were introduced in Germany as a “new” tool for subsurface characterization. Ever since, they have been frequently used in various fields of site investigations. However, despite over ten years of experience, their application potential is often perceived with scepticism. Closer consideration of the range of applications of this method shows that the technology is indeed being increasingly used, even though it does not seem to be completely accepted in the “consulting world”. This is surprising as Direct Push is already used in Germany in its simplest form—i.e. by percussion coring—on a routine basis. Nonetheless, the full potential of Direct Push has not yet been exploited. This article aims to provide a comprehensive overview on the state of the art of this technology and its various application potentials and limitations.     

Identifikation und Regionalisierung von Nitratabbauprozessen in einem Grundwasserleiter – Möglichkeiten und Nutzen für die Wassergewinnung

Denitrification with pyrite or organic carbon compounds in aquifers can lead to the release of ferrous iron, sulfate and bicarbonate into the groundwater. For the water catchment, Ortheide (Emsdetten, Germany), nitrate reduction with pyrite also causes an increased well clogging with iron hydroxides in some of the wells. With the help of hydrogeochemical modelling (PhreeqC), the main processes in the aquifer of the catchment area were identified and quantified. The presence or absence of pyrite in the aquifer sediments was determined based on groundwater compositions. This allowed the regionalization of autolithotrophic denitrification in the aquifer and the distinction of so called “origin zones” of nitrate, ferrous iron and bicarbonate. Based on these zones, the comparative sensitivity of agricultural areas towards nitrate concentrations in the raw water and the clogging tendency of the wells could be estimated.     

Pensionskassenleistungen; Zuschlagsentscheidung; Voraussetzungen für die Zuschlagserteilung

Das Vorliegen einer Betriebsvereinbarung ist bei Pensionskassenvertr?gen eine Voraussetzung für die Zuschlagserteilung.     

Phenolindex – ein sinnvoller Parameter für die Altlastenbewertung?

Der Phenolindex reagiert unterschiedlich empfindlich auf verschiedene Phenolhomologe. Insbesondere die in Verkokungsprozessen entstehenden Alkylphenole lassen sich mit diesem Summenparameter schlecht quantifizieren. Daher wurde ein toxischer Bestandteil von Teeren und Schwelereirestprodukten bisher in seiner Bedeutung über den Phenolindex nicht richtig eingesch?tzt und aus umweltgeologischer Sicht wenig betrachtet. Darüber hinaus existiert keine standardisierte chemische Targetanalytik, weil die Alkylphenole mit einer Ausnahme nicht zu den EPA-Phenolen geh?ren. In diesem Artikel wird die Empfindlichkeit des Phenolindex für Alkylphenole charakterisiert und quantifiziert. Die individuellen Alkylphenole tragen mit 0 bis 76% relativer Empfindlichkeit gegenüber Phenol zum Phenolindex bei. Die so gefundenen Laborergebnisse wurden mit realen Feldproben verglichen. Es zeigte sich, dass neben den Phenolen weitere Verbindungen zum Phenolindex beitragen. Damit k?nnen bei einem derzeitigen Orientierungswert von 50 μg/l tats?chlich Konzentrationen zwischen der Nachweisgrenze und 250 μg/l vorliegen. Es wird deutlich, dass eine alleinige Anwendung des Phenolindex zu einer Fehleinsch?tzung der Phenolbelastung führt.     

Phenolindex – ein sinnvoller Parameter für die Altlastenbewertung?

Alkyl phenols are toxic, water soluble organic compounds with a possible low biodegradation potential under reducing conditions. They are by-products of coking processes and main components of tars and creosote. However, they have been widely neglected to be a problem. The alkyl phenols do not belong to the EPA-phenols, except for 2,4-Dimethyl phenol. This means, that no standard analytical procedures are currently available. The often applied sum parameter “Phenolindex” does not fully account for those compounds. For a typical contamination case only a fraction of the total phenols are recovered by this parameter. On the other hand the index is positive for other coexisting organic compounds. The threshold level of phenolindex is 50 μg/l, which means that the actual concentration of phenols can range from the detection limit up to 250 μg/l. As a consequence, the use of the parameter as the only indicator for a plume will lead to a wrong estimation of the contamination problem.     

Lebensdauerbemessung. Baustein für die Instandsetzungsplanung am Beispiel eines Parkhauses

Service Life Design. A Module for Repair Planning Exemplified for a Multi-storey Car Park By the example of a multi-storey car park it is demonstrated how a full-probabilistic model for the estimation of the probability of reinforcement corrosion induced by de-icing salts can be combined with a harmonized investigation strategy in order to develop a tailor made and thus cost-efficient repair concept.     

Gestaltung,Validierung und Optimierung von Messprogrammen für geotechnische Aufgabenstellungen

Layout, validation and optimization of measuring campaigns for geotechnical applications. Comprehensive measurement instrumentation is nowadays an integral part of almost all geotechnical projects. Not at least because of more and more demanding projects the use of measurement data expands from an pure monitoring and securing evidence to an important indicator for decision-making under operational execution. To enable this field of utilization, the correct aspects or system response of the project must be given in sufficient quality and completeness. Therefore in general a monitoring program has to be chosen, which gives sufficient data in a most cost-effective way. Since the planning and definition of such a measurement program usually has to be completed before the start of the work, this step must be considered as non-trivial. A solution which is proposed herein can be the numerical modeling of the project, where both the scheduled work steps and the monitoring instrumentation can be investigated numerically. In this paper, a strategy for an investigation of monitoring programs in combination with an objective evaluation criterion is presented.     

Verlaufsgesteuerte Trinkwasserbrunnen als neues Fassungsorgan für die Grundwassererschlie?ung

Die Grundwassererschlie?ung zur Trinkwassergewinnung wird mit leistungsstarken und langlebigen Brunnenbauformen durchgeführt. In den 90er Jahren wurde zur Sanierung von kontaminierten Standorten eine neue Brunnenbauform entwickelt, die als verlaufsgesteuerter Horizontalfilterbrunnen bezeichnet wird. Ziel war h?ufig die schichtspezifische Entnahme kontaminierten Wassers über einen begrenzten Zeitraum.