By combining a sewer defect database and hydrogeological information, it has been attempted to assess sewer–groundwater interaction at the scale of the city of Rastatt (SW-Germany). Comprehensive hydrochemical samplings, including a series of new marker species, have been conducted in the urban aquifer and used for validation. The iodated X-ray contrast media, amidotrizoic acid and iothalamic acid, can be considered as highly specific for wastewater influence and have been found in several groundwater observation wells.

Wastewater from defect sewers can affect groundwater quality. An assessment of this environmental impact for a city of 50 000 inhabitants (Rastatt, SW Germany) was done using marker species distributions, condition monitoring of the sewer network, lab-scale analogy experiments, and specifically instrumented in-situ test sites near defect sewers. The studies revealed elevated concentrations of iodated X-ray contrast media (up to 360 ng/L amidotrizoic acid) and boron concentrations in the urban groundwater which are directly related to leaky sewers. Other common pharmaceuticals could not be detected in the groundwater. Observation wells were installed based on the information from a sewer defect database. These wells focusing on specific sewer leakages show significant changes in groundwater quality parameters.

With over 40% of the water supply of Western and Eastern Europe coming from urban aquifers, efficient and cost-effective management tools for this resource are essential to maintain the quality of life. However, the increasing concerns about the environmental impacts of water projects and their increasing economic costs mean that traditional planning concepts, which assume unlimited supplies of potable water, must be questioned. This includes the source of the water supply and its appropriate use. Urban transport systems and the provision of water have been identified as the most critical factors that determine the future of cities in this century. The objective of an interdisciplinary research project presented in this paper is to identify and develop systems and technologies and integrative processes and analytical tools, which are commercially valuable, scientifically robust and which improve the cost effectiveness of urban water services, in line with the program’s vision of ecological sustainability. As part of this program, a software tool has been developed to estimate the water flows and contaminant loads within the urban water system. This paper presents first modelling results of water and contaminant flows through the existing urban water, wastewater and stormwater systems, from source to discharge point.

Urban transport systems and the provision of water have been identified as the most critical factors that determine the future of cities in this century. The effectiveness of conventional technical urban water concepts has reached a Limit, and the sustainability of such practice is in question. Therefore as part of Australia's CSIRO urban water pro-ram (UWP), a tool has been developed to estimate the water flows and contaminant loads within the urban water system. This conceptual urban water and contaminant balance model is called UVQ (Urban Volume and Quality) and represents water and contaminant flows through the existing urban water, wastewater and stormwater systems, from source to discharge point. This model has been combined with a geographic information system and a groundwater model in order to simulate contaminant flows to and within the urban groundwater. This paper provides details of the contaminant balance model and initial results of a case study.

Maintaining pipelines is important to ensure the cost efficient transport of both water and waste- water. When sewer systems deteriorate, infiltration water enters the system, reducing the hydraulic capacity of sewer system, and adding additional costs to the system due to increased volumes of wastewater that require treatment. Pipeline rehabilitation will reduce the infiltration / inflow into the system, resulting in lower capital, operation and maintenance costs, as well as decrease the to- tal life cycle costs associated with operating the treatment facilities. Physical assessment of the pipeline must be carried out to find the best strategy for rehabilitation or replacement. A key issue governing the selection of correct rehabilitation technologies is the availability of adequate information concerning the condition of existing infrastructure. Current assessment technologies like closed-circuit television systems (CCTV) do not provide adequate detailed information of the entire interior pipe surface, wall damage and the condition of the soil surrounding the pipe. In order to overcome this problem a range of new sensors have been developed and mounted on the experimental platform SAM (Sewer assessment with multi-sensors) that is connected to a commer- cial CCTV. This paper presents new results for SAM and a comparison to other inspection sys- tems.

Leakage through pipeline joints in water supply and sewer networks in Australian water utilities is not accurately quantified. Discounting fire fighting, mains cleaning and burst mains, leakages from water supply pipelines are estimated at 8%. Net infiltration into sewers is estimated at about 15%, whilst there is little data quantifying the levels of sewer exfiltration. These statistics provide the extent of leakage through pipelines and an insight to leakage through joints. Currently the impact of leakage from the water supply systems is assessed purely from the viewpoint of the direct financial cost of non -revenue water and that of infrastructur e rehabilitation inputs. The environmental and social costs to the community are not taken into account. A similar situation exists with the wastewater systems, with the difference being that the environmental impact of leakage from sewers is far greater. This paper reviews the joints in water and sewer pipeline systems and their probable condition in networks with over 25 years of service. Quantitative estimates of losses are made and an overview presented on the environmental and other external factors that will drive future rehabilitation priorities.

Current urban water design in most countries has evolved from 19th century European experiences to control water borne disease transmission. This generally involves the large-scale transport of water into and out of major urban areas. This approach has effectively eliminated water borne disease in nearly all communities; however, it also has a number of problems such as a heavy demand on source water catchments, escalating costs for infrastructure investment and environmental problems caused by large-scale discharges of wastewater and contaminants back to the environment. Alternative approaches to the provision of urban water services do exist, but they have not been thoroughly investigated because of a reluctance to experiment with any system, which could in any way compromise human health. With population densities increasing (particularly in urban areas) and constraints on funding, it is becoming increasingly evident that present urban water systems will not be suitable models for service provision into the 21st century.

Worldwide, pipeline systems differ in age, manufacture, length and system configuration. However, in all cases they require a large infrastructure investment, which for many cities and towns is one of their largest capital investments. Pipe leakage for these towns and cities can be a major problem, both from an environmental point of view, as well as the costs that are incurred due to overdesign of the sewerage systems and the treatment of additional potable water, lost due to leakage. It is essential to maintain pipelines to guarantee that they operate correctly and that external costs (i.e. contamination of ground water) associated with exfiltration and infiltration are minimised. To minimise these problems, damaged pipelines have to be replaced or repaired. Pipeline repair and rehabilitation methods can provide utility owners with cost effective alternatives to total replacement. However, making the correct choice of a repair or rehabilitation method is critical as it can significantly affect the total lifecycle cost of the system. A key issue governing the selection of correct rehabilitation technologies is the availability of adequate information concerning the condition of existing infrastructure. Current assessment technologies like closed-circuit television systems (CCTV) do not provide adequate detailed information of the entire interior pipe surface, wall damage and the condition of the soil surrounding the pipe. In order to overcome this problem a range of new sensors have been developed and tested for pipeline leakage detection and sewer assessment. These sensors have been mounted on the experimental platform SAM (Sewer assessment with multi-sensors) and connected to a commercial CCTV. This paper presents the first results for SAM and a comparison to other inspection systems.

Pipe leakage in Australia is perceived to be a major problem by many water authorities, both from an environmental point of view, as well as the associated costs that are incurred due to overdesign of our sewerage systems (to cope with wet weather loads) and the treatment of additional potable water that is lost due to leakage. This paper discusses the state of our reticulation systems, design and environmental concepts to allow us to categorise the problem, methods of leakage detection, solution concepts to solve leakage and finally methods to allow planning to occur to prioritise asset management solutions.

In many urban areas, grout injections have been used to seal porous soil within the last decades, Silica hydrogels have been particularly applied in foundation engineering practice due to their wide applicability and economic advantages. For example in the City of Berlin between 1990 and 1995 about 100 000 m(3) of silicate gels were injected into porous aquifers. Therefore the environmental authority of Berlin insisted on detailed investigations of potential groundwater contamination risks. This paper presents the results of detailed investigations on an excavation site over a period of two years. Two main topics are the use of artificial and natural tracers as well as transport modelling to quantify potential changes in groundwater chemistry and to predict both longevity and toxicity of silica grouts.

Transport and fate of contaminants from leaky landfills in karst areas have been investigated by soil gas surveys and geophysical methods. One investigation area was a municipal landfill above karstified Limestones of Triassic age, Northern Black Forest, South Germany. Research work was focused on the detection of hypothetical contaminant flow paths from the landfill to a karst spring north of the landfill, which is subject to severe pollution. Therefore detailed hydrogeological and geophysical investigations were carried out in different investigation profiles above the supposed contaminant flow paths. In combination of soil gas screenings and geophysical investigations, two inclined fault zones were detected. Within the fault zones the leachates from the damaged landfill are transported to the groundwater. The detailed soil gas screenings on the selected investigation profiles allowed, in combination with geophysical methods, the detection of fault zones as well as the further run of preferential now paths of leachate and contaminated groundwater in the karstic limestones.

In many urban areas grout injections have been used to seal porous soil within the last decades. Especially the silica hydrogels have been applied in foundation engineering practice due to their various applicabilties and economical advantages. For example in the City of Berlin from 1990 to 1995 about 100.000 m3 of silica gels have been injected within porous aquifers. Therefore the environmental authority of Berlin insisted on detailed investigations of potential groundwater contamination risks. This paper presents the use of artificial and natural tracers as well as transport modelling to quantify potential changes in groundwater chemistry and to predict both longevity and toxicity of silica grouts.

Delineation and remediation of subsurface contamination have become a major focus of environmental science during the past five years. Conventional technologies available for subsurface investigations (e.g. monitoring wells) always will. be required to confirm and monitor subsurface contamination; however, quicker and less expensive techniques are useful for preliminary site evaluations. Soil-gas surveying is a technique that is applicable to a wide range of volatile organic compounds (VOCs) and other contaminants under a variety of geologic and hydrologic settings This paper presents the results of the use of soil-gas surveys for evaluation of the magnitude and lateral extent of a BTEX contamination at a former gas plant in Southwest Germany.

Natural redox processes and terminal electron acceptors (oxygen, nitrate, iron, sulfate) have been identified responsible for hydrocarbon degradation in different contaminated aquifers (porous, fissured, karstic). This paper details and compares the results of the most recent investigations at 3 different sites in Germany: 1) The fate of benzene, toluene, ethylbenzene and xylenes (BTEX), phenols and polyaromatic hydrocarbons (PAHs) have been investigated in a Quaternary porous aquifer below a former gas plant. The groundwater is contami- nated with more than 20 mg/L total BTEX. About 250 m downgradient from the center of contamination, a rapid de- crease of these compounds to less than 0.1 mg/L is observed. Microbial degradation of some organic compounds leads to partly prevailing anoxic conditions. A dominant control over BTEX biodegradation at this site was the availability of sulfate and iron, which determines to significant degree the extent of anaerobic biodegradation of BTEX. 2) The transport and fate of contaminants from a leaky landfill in a karst area have been investigated by soil gas sur- veys, geophysical methods, as well as by hydrochemical and tracing techniques. The leachates from this old landfill above karstified limestones of Triassic age typically contains specific organic pollutants, as well as a substantial content of organic matter. Leachates and dissolved gases percolate downwards, dilute and attenuate passing through the 30 m thick unsaturated zone. Such processes include both biological and physicochemical reactions. 3) In the framework of the implemented monitoring scheme for groundwater control frequent hydrochemical analyses proved a significant reduction in the content of organic contaminants of the leachate plume of a hazardous waste deposit. Several mechanisms such as biodegradation under aerobic environment as well as enhanced sorption are the responsible factors for the fate of the organic compounds in this self-attenuated plume. At all investigation sites contaminant concentrations, availability of electron acceptors, subsurface geochemistry and hydrogeology strongly affect the pathways and rate of natural attenuation.