Combined sewer overflows (CSO) can have a strong impact on the quality of surface waters. A common measure to reduce CSO is the construction of storage tanks. The objective of this study was to determine the required volume of a storage tank by means of a numerical long-term simulation and to assess uncertain input data. Particularly, the influence of the considered rain series’ length on the calculated storage volume was investigated. Engineering standards usually recommend the use of at least 10 to 15 years of rain series. Here, the hydraulic behaviour of the studied sewer system was simulated in a 30 year hydrodynamic simulation. Special effort was made to calibrate an available model by use of currently measured data. The quality of calibration was evaluated by means of the Nash-Sutcliffe model efficiency coefficient. The analysis of input data uncertainty revealed that applying a 10 year series results in tank volumes that differ between -12 % and +19 %, respectively from the dimensioning result achieved by applying the 30 year rain series.

Management models for aquatic systems can be used to determine which measures in the watershed or in the water body have been effective and/or which one should be used in future. The newly developed management models presented in the following for Lake Tegel and Schlachtensee are empirical and lake specific. The values for the unknown factors are estimated by an iterative process using optimisation routines and sensitivity analysis methods. The resulting models describe the water and phosphorus balance of each lake. The Lake Tegel water balance model calculates the unknown water inflow from the River Havel depending on the other main in- and outflows with very good validation results. The phosphorus models of both lakes quantify mixing of the upper and lower water body as well as sedimentation and release from the sediment as functions of measured variables. For Lake Tegel, management scenarios were run indicating effective management interventions. For Lake Schlachtensee, the phosphorus model captured the variations in the hypolimnion well but produced poorer results for the epilimnion because of unknown external phosphorus loads. For these the model indicated possible sources and magnitudes.

Bei der Planung von Strategien für ein „Integriertes Wasser-Ressourcen-Management in urbanen Räumen" kommt der Berücksichtigung von niederschlagsbedingten Einflüssen auf die Qualität der als Ressource verfügbaren Gewässer eine zunehmende Bedeutung zu. Unter den Gewässereinleitungen aus urbanen Gebieten stellen Mischwasserüberläufe (engl. combined sewer overflows, CSO) aufgrund ihres dynamischen Charakters eine besondere Belastung für die Gewässer dar. Für eine integrierte Modellierung von Kanalnetz und Gewässer werden Mengen- und Qualitätsdaten von der Schnittstelle Mischwasserüberlauf benötigt. Ein Monitoring-Konzept für Mischwasserüberläufe in Berlin wurde im Rahmen des Projektes Monitor-1 vom KompetenzZentrum Wasser Berlin erstellt. Dieses dient der Vorbereitung einer Messphase im Folgeprojekt Monitor-2. Ein wichtiger Aspekt bei der Planung und Vorbereitung eines Monitorings ist neben der Bewertung möglicher Standorte die Auswahl geeigneter Messtechnik. Hierzu wurden umfangreiche Tests verschiedener Produkte aus dem Bereich Online-Messtechnik namhafter Hersteller an der TU Berlin an einem Versuchsstand analog zur DIN EN ISO 15839 durchgeführt. Mit den Tests sollten Fragestellungen zur Vorbereitung des Mischwassermonitorings geklärt werden. Daher wurde das Hauptaugenmerk nicht auf eine Standardisierung der Tests gerichtet, sondern versucht, die Mischwasseranforderungen nachzubilden. Getestet wurden Sensoren, die auf photometrischer Basis das UV- bzw. UV/VISSpektrum analysieren, sowie ionensensitive Sensoren. Ein Hauptaugenmerk lag dabei auf in situ einsetzbaren Sensoren. Im Wesentlichen wurden die Parameter Ammonium, Nitrat und CSB betrachtet. Für die Messung von Orthophosphat stehen am Markt derzeit keine kompakten Geräte zur Verfügung, daher wurden hier klassische Analysatoren (mit z. T. sehr kompakter Bauform) verglichen. Der Versuchsstand wurde mit Rohabwasser, Flusswasser und daraus hergestellten Mischungen beschickt. Alle Sensoren wurden parallel getestet, so dass eine gute Vergleichbarkeit der erzielten Ergebnisse gegeben ist. Neben Fragestellungen wie Genauigkeit, Ansprechverhalten bei plötzlich auftretenden Belastungspeaks bzw. Verdünnungen und verfügbaren Messintervallen wurden insbesondere die Aspekte Kalibrierung, Reinigung und Handhabbarkeit der Sonden bewertet. Der Einfluss der Kalibrierung wurde insbesondere bei den ionenselektiv arbeitenden Sonden untersucht. Dabei wurde der Fragestellung nachgegangen, wie die Sonden kalibriert werden müssen, um sowohl bei den zu erwartenden sehr niedrigen Konzentrationen im Gewässer als auch bei plötzlichem sprunghaftem Anstieg der Konzentration im Fall des Anspringens des Mischwasserüberlaufes die größtmögliche Genauigkeit zu bieten. Neben der Aufstockung mit Abwasser wurden Ammonium und Nitrat auch mit Chemikalien aufgestockt. Die Fragestellung der Datenerfassung und Weiterverarbeitung wurde mit untersucht. Zur Bewertung der Sonden wurden die Anforderungen in die Gruppen quantitative (=direkte aus den Versuchen bewertbar), qualitative (=Literatur- und Herstellerangaben sowie eigene Erfahrungen) und zusätzliche Kriterien(=Herstellerangaben zu Messeigenschaften) unterteilt. Die Ergebnisse aller Sonden lagen dicht beieinander. Eine wichtige Erkenntnis der Untersuchungen ist, dass die getestete Onlinemesstechnik grundsätzlich für den Einsatzzweck in Frage kommt. Zu beachten sind allerdings die jeweiligen Anforderungen und Hinweise der Hersteller zur geeigneten Platzierung der Geräte. Eine große Bedeutung zur Erzielung der gewünschten Genauigkeit kommt der Auswahl und richtigen Durchführung der geeigneten Kalibriermethode zu.

The overall project WellMa, which stands for well management, aims at the optimization of the operation and maintenance of drinking water abstraction wells. For this purpose, in addition to a statistical analyses of well data (report D 1.2) and first field investigations to compare various diagnosis methods (report D 1.3), a review of literature during the preparatory phase WellMa1 should answer the following questions: (1) Which processes affecting the well performance and conditions can occur? (2) Which correlation exists between well ageing and well characteristics? (3) How can such well ageing be recognized at an early stage? (4) What is the state of the practice to restore a good performance and condition? (5) What can be done during well design and construction to prevent well ageing? (6) How can well operation be adjusted to slow-down well ageing processes? Based on textbooks, standards and professional articles published in large number since the middle of the nineties, the state of the art was gathered and compared to current practice at BWB and Veolia to identify possibilities for improvement and specify the need for further investigations to be proposed for WellMa2. 1) Three well ageing types involving different processes could be identified. These are chemical, biological and physical clogging. They are closely linked to the characteristics of the exploited aquifer, such as the physical properties of the formation or the chemical composition of the groundwater. 2) The evaluation of these site-specific aquifer characteristics, the impacts from well design and the observed effects on the well performance and condition and their development with time of operation should be used to specify the individual ageing potential for each well site. 3) The early recognition of well ageing implies the need to monitor wells (1) regularly and (2) with comparable methods. As suitable indicators, the development of water levels and discharge rates to calculate the specific drawdown and specific capacity, the pump surveillance and the visible condition of the well interior could be identified. 4) Both, the assessment of the ageing potential and the monitoring of a reference value describing the state of the well lead to the specification of maintenance requirements. Generally, three strategies could be identified, ranging from sheer operation, over reactive maintenance to regular condition assessment and preventive treatment. Concerning the choice of maintenance method, key criteria must always be the well design, its state of construction, the well ageing type and location. Up to now, patterns linking well characteristics and the success of maintenance could not be identified. Thus, maintenance relies on practical experience and the willingness to discuss limitations and disadvantages of methods as open as the advantages on side of the rehabilitation companies. 5) For well design and construction, the technical standards were summarized, describing the necessary steps for proper dimensioning, drilling, choice of materials and final well development. Not only the avoidance of nonconformities and the careful evaluation of the advantages, but also the restrictions of different well design alternatives, e.g. for the accessibility of rehabilitation, assure an optimal well ageing prevention and well operation. 6) Furthermore, well operation could be identified as a key element and critical factor codetermining the lifetime, but at the same time the economic efficiency of a well. It is always a compromise between demand, technical possibilities and economic considerations, for which reason general standards or technical guidance are not available so far. They need to be developed individually considering present well ageing processes and the quantification of impacts. Comparing the state of the art with current practice at BWB and Veolia, room for improvement could primarily be identified for monitoring and subsequent data processing for both, operational parameters (to assess well performance and condition), and maintenance (to evaluate the success of applied treatments). Based on the recommendations derived on this state of the art review, within WellMa2 the effects of measures for preventing and treating well ageing shall be quantified so that the benefits can be assessed for future optimized well management.

This report attempts to give a survey from literature on the microorganisms involved, on the factors and mechanisms potentially relevant for the susceptibility of drinking water wells to health related microbial contamination. The habitat groundwater accommodates a rich diversity of microorganisms, which has only begun to be identified since the development of molecular detection methods in addition to the conservative cultivation techniques. Characteristics of the subsurface are darkness, low spaces, low nutrient and low oxygen content. Indigenous microorganisms have adapted to these oligotrophic conditions and are able to proliferate in this environment permanently. Other incoming microorganisms generally cannot reproduce under these conditions, but have developed strategies to survive. They can grow only, when the parameters turn favourable. Pathogenic microorganisms comprise bacteria, viruses, and protozoa, which can also survive a certain time in groundwater. Most microorganisms in the subsurface are attached to surfaces and survive best within biofilm populations. Pathogenic microorganisms originate from human or animal faeces. These organisms are not easily detected. The methods are very time and labour consuming. Therefore, other microorganisms regularly present in the faeces are used for detection. Their presence indicates the possibility of a contamination with pathogens. As indicator microorganisms mostly coliform bacteria, E. coli, enterococci and clostridia are used. Contamination with pathogens is reported to derive essentially from communal sources: defects in wastewater treatment plants, sewage tanks, pipes, and waste deposits; from agricultural sources: animal wastes, liquid manure, and grazing; and from point sources like faeces from animals, birds, and humans. Entrance into the subsurface occurs via rainwater and surface waters, as well as by direct contamination of wells. The transport of the microorganisms into the subsurface is influenced by the geologic conditions of a specific site: soil and rock type, presence of fissures, heterogeneity. In sand, microbial movement is less far than e.g. in Karst regions, thus the susceptibility to contamination of groundwater and wells is lower. Pore sizes are crucial for sedimentation and filter efficiency of the soil. Also important is the extent of the unsaturated zone, the flow velocity of the groundwater, the geochemistry and mineralogy of the site. Wells receive their water from the groundwater reservoir of the surrounding soil. The quality of the well water is therefore essentially dependent on the properties of the groundwater and all the factors influencing the groundwater may also be relevant for the well water. The wells represent, in addition, a separate complex system with specific conditions and influencing parameters. This specific habitat involves additional variable adsorption surfaces, more space, higher flow velocity of the water, a mixing of waters from different groundwater layers and thus a different chemical composition. Contamination may also arise from microbial introduction at the open wellhead. Two main processes have been identified which are essentially responsible for the elimination of pathogens during their pathway from top of the soil to the extraction well: inactivation of the microorganisms and their adsorption to the soil particles in the subsurface. Both processes are influenced by a variety of factors and conditions present at a given site. To mention are here properties of (i) The soil: consistence and texture of surfaces, electric charge, hydrophobicity, degree of moisture, coating with organic material. (ii) The groundwater: temperature, pH, presence of cations and ionic strength, presence of organic substances, dissolved oxygen content, activity of indigenous microorganisms. (iii) The microorganisms: forming of flagella, fimbria, hydrophobicity of the cell surface, forming of extracellular polymeric substances, forming of cysts and spores as survival strategies. In addition to the description of the microbial diversity in the subsurface, the sources of pollution and the factors controlling the microbial pathways into groundwater and wells, main methods for the detection of a variety of contaminating microorganisms are given at the end of the report.

The assessment of methods for the diagnosis and distinction of well ageing types and processes with the aim to recommend methods and tools for further fieldwork was part of work package 1 of the preparatory phase WellMa1. Therefore, field tests were carried out at selected well sites with a variety of methods covering standard monitoring methods to assess the constructive state of a well (TV inspections, borehole geophysical methods) and its performance (pump tests) as well as methods aiming at a better process understanding such as the hydrochemical and microbiological analysis of the raw water and clogging deposits. Altogether ten methods were applied at 21 different wells of the Berliner Wasserbetriebe (BWB) covering (i) exposure of object slides during operation and rest periods for microbiological investigations, (ii) BART with test kits for iron-related bacteria (IRB) and slime-forming bacteria (SLYM), (iii) water sampling for the investigation of pristine groundwater organisms, (iv) online measurements of chemical parameters O2, Eh, pH and T and water sampling for chemical analyses (main cations and anions), (v) TV inspections, (vi) three-step pumping tests, (vii) borehole geophysics with Gamma-Gamma-Density scan (GG.D), NeutronNeutron log (NN), Flowmeter (Flow) and Packer-Flowmeter measurement and (ix) Particle countings. The assessment and comparison should originally be completed by a horizontally directed core sampling from different depths from the screen sections of three of the chosen wells. Due to technical difficulties, this was not achieved during this phase of the project. The investigations led to a development and refinement of the methods and approaches. Because of their limited accessibility to the different parts of a well, a combination of methods is always necessary. Especially for the indirect methods like borehole geophysics, an initial assessment of the well condition directly subsequent to construction is essential to provide a basis for the assessment of the well performance development. Generally, the applied standard monitoring methods and diagnosis tools provided the expected identification of a performance deterioration and evidence for the presence of starting materials for clogging processes such as iron, oxygen, iron-related bacteria and particles. Room for improvement could be identified with regard to the reliability, information value and comparability of the tested methods, e.g. by a stepwise combination and extension of the methods to determine the interacting processes from the composition of the deposits. Further investigations should aim at method validation, especially for well monitoring during routine operation (e.g. use of delta h, development of standards for Qs-measurements and TV inspections), and further method development for the ongoing project with scientific investigations to obtain deeper process understanding, e.g. investigating shares of deposits resulting from the different processes (chemical, biological, physical) and relations between the rate of clogging or the location of deposits to well characteristics and site conditions to separate the different well ageing processes. This will then lead to the identification of key parameters that may be influenced to slow down well ageing and keep the well performance and water quality at an optimum.

The Aquisafe project aims at mitigation of diffuse pollution from agricultural sources to protect surface water resources. The first project phase (2007-2009) focused on the review of available information and preliminary tests regarding (i) most relevant contaminants, (ii) system-analytical tools to assess sources and pathways of diffuse agricultural pollution, (iii) the potential of mitigation zones, such as wetlands or riparian buffers, to reduce diffuse agricultural pollution of surface waters and (iv) experimental setups to simulate mitigation zones under controlled conditions. The present report deals with (i), providing information on trace substances, which enter surface water predominantly via diffuse sources in rural or semi-rural environments. In particular, it provides a priority list of relevant substances to aid planning of monitoring programs at waterworks, which abstract surface water from rural watersheds, for which information on substance use is sparse. As this ranking is limited to substances for which broad data sets are available from literature, it is compared to actual screening programs in predominantly rural catchments in Brittany (France) and Indiana (USA). The literature review identified pesticides as the dominant known diffuse contaminant group in rural and semi-rural settings (section 2.1). This is confirmed for the agriculturally dominated Ic Catchment in France and Upper White River Watershed in the USA, where pesticides were found to dominate the diffuse source compounds (section 3). Seven agricultural pesticides were detected in the Ic Catchment with AMPA and atrazine being the most common compounds, detected in 54 % and 41 % of all the samples, respectively. In the White River Basin 26 of the 38 detected compounds were pesticides making them the largest group of chemicals detected. Based on literature values on pesticide detection in surface waters in Germany, France and the USA, a priority list was established in section 2.2 of this report (see Table on page vi). Only seven substances were among the 20 most relevant pesticides, both in the USA and in Europe. Accordingly, US and European substances are distinguished in the priority list. Most frequently detected substances were atrazine, metolachlor and simazine for the USA, AMPA (metabolite of glyphosate), diuron and atrazine for France and diuron, atrazine and isoproturon for Germany. The importance of atrazine in Europe is interesting, since it was already banned at the time of the monitoring, indicating the high persistency of atrazine in groundwater. In some cases in Germany, concentrations in surface waters were found to follow typical seasonal application patterns, indicating illegal use (pers. Comm.. M. Bach). Although the list of substances in the USA and in Europe differ, there is an agreement to the fact that many of the pesticides applied in agriculture find their way into surface waters. The concentrations found are often beyond 0.1 µg/L. For the EU this level already corresponds to the drinking water limit. Thus, if surface water is used for drinking water production pesticides seem to be of high relevance. In finished drinking water, frequently-used Isoproturon and Bentazon were most frequently detected in Germany and France. The importance for drinking water production is emphasized by frequent detections above 0.1 µg/L in finished drinking water in nine waterworks in the US. Regarding drinking water regulation, the thresholds in the USA are substance-specific and generally more than one magnitude higher than 0.1 µg/L. As a result threshold exceedance was mainly found for Atrazine. In terms of treatability in water works, the priority list includes the efficiency of classical treatment (flocculation, filtration, ozonation) and of powdered activated carbon (PAC), which is often added in emergency situations. Particularly problematic are triazines (such as atrazine), phenoxy-type substances (such as 2,4-D and Mecoprop) and Anilides/Anilines (such as Metolachlor and Acetochlor). The pesticides found in the screenings are in good agreement with the priority list of most problematic pesticides for the US and Europe. AMPA and atrazine, the substances detected most frequently in the Ic catchment, as well as 2,4-D and dichlorprop, which were found in high concentrations > 0.1 µg/L in one sample are all included in the Europe top 20 of the priority list. Other substances on the list may not have been found because they were not measured, because of relatively high analytical detection limits of the screening or simply because they are not used in the basin, dominated by corn and wheat cultures. In the White River Basin, atrazine, acetochlor and simazine were detected at concentrations exceeding early warning levels utilized by several states in the United States, indicating their high relevance concerning drinking water production. They are also included in the US top 20 of the priority list. The priority list is a reliable basis for potentially problematic pesticides. It can thus be used as a starting point for monitoring programs in rural catchments, where no specific information on pesticide use are available. If looking for pesticides in surface water, it is important to take times of application of regarded pesticides into consideration, as shown by strong fluctuations in atrazine concentrations in the source water of a waterworks in Indiana (Figure 12 of this report). The screening results indicate that also other contaminants than pesticides may play a role in rural catchments. In the screening in the semi-rural catchments in Indiana, twelve of the detected 38 substances were not pesticides, but belonged to other groups, such as domestic use products, manufacturing additives or gasoline hydrocarbons. Of these twelve substances, seven were only found in one of the two catchments, showing a strong catchment-specific relationship. The findings indicate that other substances than pesticides may be of local importance, though in the case study all 12 substances were at least 50-fold below human health benchmarks (if defined). We conclude that the pesticide priority list given below is a good starting point for diffuse pollution screening even though it may possibly not be sufficient if major local influences, such as factories, large roads with stormwater discharges, CSO or specific local pesticide uses are present.

The Aquisafe project aims at mitigation of diffuse pollution from agricultural sources to protect surface water resources. The first project phase (2007-2009) focused on the review of available information and preliminary tests regarding (i) most relevant contaminants, (ii) system-analytical tools to assess sources and pathways of diffuse agricultural pollution, (iii) the potential of mitigation zones, such as wetlands or riparian buffers, to reduce diffuse agricultural pollution of surface waters and (iv) experimental setups to simulate mitigation zones under controlled conditions. The present report deals with (ii) and aims at identifying numerical modelling tools that can assess the origin of contaminants as well as the impact of different mitigation measures regarding water quality aspects on a catchment scale. In order to test the identified modelling tool in the further course of the Aquisafe project a case study was found in Brittany (France) in agreement with Veolia Eau: the small watershed of the river Ic. Due to intensive agricultural land use the nitrate concentration exceeds the threshold for surface water used for drinking water purpose (which is the main concern of Veolia Eau). Additionally, trace contaminants (pesticides) were detected in the surface water ever since measurements have been carried out. Therefore modelling shall mainly support the water supplier in actions aiming at reducing the nitrate concentration in the surface water. An additional task could later on be the application of the model in order to assess the effectiveness of mitigation measures against trace contamination. In order to choose the most appropriate model a model comparison was carried out using a three step approach. The first step was a screening of different information sources and resulted in the identification of 44 existing models. The second step was a pre-selection according to essential criteria in order to identify models that fulfil the basic requirements for a) the Ic nitrate issue and b) the Aquisafe trace contaminant issue. In a third step a multicriteria analysis was carried out using 6 additional criteria followed by a final recommendation. The essential criteria used for the pre-selection of the models were a) the inclusion of major hydrological processes, b) the inclusion of the nitrogen cycle (for the Ic nitrate issue) or the inclusion of trace contaminants (for the Aquisafe trace contaminant issue) c) the size of catchments that can be modelled, d) the temporal and spatial resolution and e) the possibility to include management options and/or mitigation measures. For the Ic nitrate issue this resulted in the selection of the models: HBV-NP, HSPF, SWIM, SWAT, WASMOD and Mike She. For the Aquisafe trace contaminant issue only four models remained after the pre-selection process: DRIPS, HSPF, SWAT and Mike She. Additional criteria were then applied and resulted in the recommendation to use the model SWAT for further investigations in both cases due to sufficient accuracy and included processes (full hydrological model with water quality simulation (nutrients and trace contaminants) as well as a wide range of successful applications (amongst others). This report presents a wide range of models with their capabilities and limits. It contains criteria which were identified with the stakeholders in order to choose the most appropriate model. The approach presented in this report shall support the decision process of selecting a model for a certain problem regarding water quality and includes only a recommendation. The final decision on which model shall be applied, will be taken in agreement with the stakeholders Veolia Eau and Goel’Eaux.