Florian Kretschmer

A novel method for rapid inspection of sewer networks: combining acoustic and optical means

Abstract Operation and maintenance of the public sewer system represent key tasks for an operator. Condition assessment is usually conducted by conventional closed circuit television (CCTV) inspection. However, alternative tools such as manhole-zoom cameras (MZCs) and the acoustic technology SewerBatt® are available today. The INNOKANIS project investigates structural and operational condition assessment in the sewer system by means of three MZC models and SewerBatt® to develop a combined optical and acoustic device as a cost-effective alternative to conventional CCTV inspection. The first field trials of the ongoing project were conducted in Austria in 2011. 640 conditions according to EN 13508-2/A1 were investigated and compared against conventional CCTV reports. Individual and combined detection rates for both devices were calculated. Based on the current findings, both MZC and SewerBatt® are effective alternatives to conventional CCTV inspection. In addition, performance is significantly enhanced when both devices are used in combination.

Analysing the Cause of Urban Pluvial Flooding in a Hillside Settlement

Pluvial flood risk is increasing in urban and rural areas due to changes in precipitation patterns and urbanization. Pluvial flooding is often associated with insufficient capacities of the sewer system or low drainage efficiency of urban areas. In hilly areas hillside runoff additionally affects the risk of pluvial flooding. In the presented case study the cause of pluvial flooding at two selected sites in a settlement is investigated. To investigate all effects of pluvial flooding a coupled 1D-2D model of the whole catchment of the settlement is necessary. The results show that even though bottlenecks in the sewer system are important the effect of low drainage efficiency and hillside runoff greatly influence pluvial flooding. The knowledge of different causes of flooding can be further used for selecting and positioning appropriate adaption measures.

Thermal use of wastewater – Policy instruments for initialization and potential operating models / Thermische Nutzung von Abwasser – Instrumente zur Verbreitung und mögliche Betreibermodelle

Summary The heat content of wastewater presents a great but still widely unused potential for energy supply. The thermal energy recovered through heat exchangers and heat pumps can be used for the heating (and cooling) of buildings and even for hot water production. At the moment, at least about 500 installations are operated on a global scale, and most experiences are available in Switzerland. In Austria, some wastewater heat recovery systems are also already under operation, for instance in Amstetten and in Weiz. However, due to the lack of superordinate strategies for planning, implementing, and operating wastewater heat recovery systems on federal and provincial level, the Austrian installations are primarily the result of personal initiatives of local stakeholders. This paper gives a general overview of different policy instruments for initializing and further promoting wastewater heat recovery as well as potential operating models for related heat supply systems and conducts a related comparison with the current Austrian situation. The information gained can serve as an input for the development of an initialization program for wastewater heat recovery on Austrian national level.

Der Hausanschluss – Ein kritischer Punkt bei der Instandhaltung von Kanalisationen

SummaryThe house connection as the interface between house sewer and main pipe as well as the house sewer itself have substantial technical, organisational, economic and environmental effects on sewerage management in a drainage district. The total length of house sewers in Austria is not known exactly, but is estimated at about twice the length of the public drainage system. Despite these facts, the importance of the house sewer was long neglected by many decision-makers. This is why many persons with authority for this area are no longer aware of their own responsibilities and duties with respect to the house sewer. The authors discuss the main legal, technical and organizational questions relating to the house connection and sewer. They conclude by formulating two urgent quality assurance recommendations for sewerage systems: New house connections need to be constructed with great care by certified enterprises and the performance should be checked by the sewerage utility. Existing house sewers need to be included in a routine maintenance and inspection system. Since most of the effects caused by house sewers fall within the competence of the sewerage utility anyway, it would appear logical for the public utility to assume responsibility for the sections that have so far been in private hands. The technical standard for drainage systems outside of buildings (ON EN 752, 2008) has laid the basis for this. The authors recommend that this should be translated into organisational practice.ZusammenfassungDer Hausanschluss als Schnittstelle zwischen Hauskanal und Hauptkanal sowie der Hauskanal per se haben enorme technische, organisatorische, ökonomische und umweltrelevante Auswirkungen auf das Kanalmanagement eines Entsorgungsgebietes. Die genaue Länge der Hauskanäle in Österreich ist nicht bekannt, aber sie kann ca. mit der doppelten Länge des öffentlichen Kanalnetzes angenommen werden. Trotz dieser Fakten spielte der Hauskanal im Bewusstsein vieler EntscheidungsträgerInnen lange nur eine untergeordnete Rolle. Dies führte u. a. dazu, dass heute vielen Verantwortlichen ihre eigene Zuständigkeit sowie die damit verbundenen Pflichten in Bezug auf den Hauskanal nicht mehr bewusst sind. In diesem Beitrag werden die wichtigsten rechtlichen, technischen und betrieblichen Themen rund um den Hausanschluss bzw. Hauskanal erläutert und in ihrer Bedeutung diskutiert. Als Schlussfolgerungen für eine funktionsfähige Kanalisation können zwei dringende Empfehlungen zur Qualitätssicherung ausgesprochen werden: Einerseits müssen neue Hausanschlüsse von nachgewiesen fachkundigen Unternehmen mit hoher Sorgfalt errichtet und die Ausführung vom Kanalisationsunternehmen überprüft werden. Andererseits müssen die bestehenden Hauskanäle in eine laufende Wartung und Überprüfung mit eingebunden werden. Da die meisten Auswirkungen, die der Hauskanalisation zuzuschreiben sind, ohnehin das entsprechende Kanalisationsunternehmen zu behandeln hat, scheint es nur logisch, die Verantwortung für die Instandhaltung der bisher privaten Teile seitens des öffentlichen Betreibers mit zu übernehmen. Die technische Norm für die Entwässerungssysteme außerhalb von Gebäuden (ON EN 752, 2008) hat dafür bereits die Basis gelegt. Die Autoren empfehlen, dies auch in organisatorischer Form umzusetzen.