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Riverbank Filtration Hydrology

Proceedings of the NATO Advanced Research Workshop on Riverbank Filtration Hydrology Bratislava, Slovakia September 2004

herausgegeben von: Stephen A. Hubbs

Verlag: Springer Netherlands

Buchreihe : NATO Science Series

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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Über dieses Buch

Riverbank Filtration (RBF) has gained popularity in the past decade as an excellent source of high quality water for public water supply. This text compliments the existing literature on RBF water quality, and provides much-need guidance in the design and operation of RBF facilities. RBF has proven effective in many hydrogeological settings worldwide, and can be an excellent solution to water supply problems in both developed and developing countries.

Topics covered include surface stream hydrology, particle clogging, and biological/geochemical processes. Data and case histories are provided from dozens of installations, providing much-needed practical information regarding RBF design, operation, and performance.

This book provides the necessary tools to evaluate potential RBF sites, and is a must-have if you are considering RBF as a source of water supply.

Inhaltsverzeichnis

Frontmatter

Significance of Hydrologic Aspects on RBF Performance

Everything is linked to everything else

Abstract

Clogging of the riverbed is still an important factor causing uncertainness in the planning stage of riverbank filtration plants. Several attempts have been made to develop tools, which are suitable to predict this process. But up till now, these tools are only a slight help for the engineering of riverbank filtration plants. On the other hand there exists a lot of experience about clogging from the operation of riverbank filtration plants. But to utilize this experience for a new plant, the hydrological and morphological aspects of the river and the aquifer have to be analyzed carefully to create a basis for the transfer of available knowledge. This paper deals with the relevant properties of rivers, concerning riverbank filtration: the runoff regime and the runoff dynamics, the river-aquifer interactions, the stream processes — erosion, transport and deposition — and the progress of the clogging process itself.

Jürgen Schubert

Evaluating Streambed Forces Impacting the Capacity of Riverbed Filtration Systems

Abstract

The static and dynamic forces at work on a riverbed impact both the clogging processes and the regenerative scouring processes in RBF systems. This chapter reviews shear forces exerted on a riverbed, and considers the additional forces developed under conditions of infiltration with saturated and unsaturated flow. Methods of measuring streambed shear stress are evaluated in relation to streambed scouring, and the relative impact of barge traffic on streambed shear stress is discussed. These measures help to define the suitability of a site for Riverbank Filtration.

Stephen A. Hubbs

Impact of Riverbed Clogging — Colmatation — on Ground Water

Abstract

Clogging in RBF systems is defined in hydrogeologic terms, and analytical methods of measuring reduction in riverbed conductivity are presented. Computer modeling techniques are presented, and a program for estimating the impact of clogging is provided. Water quality of the Danube river is presented in context of impact on infiltrated water.

Igor Mucha, L’ubomír Banský, Zoltán Hlavatý, Dalibor Rodák

New Approaches for Estimating Streambed Infiltration Rates

Abstract

Direct quantification of infiltration rates and darcy velocities at bank filtration sites by field measurements has been done only at sites that are well equipped with monitoring wells and is mostly based on the observation of changes in chloride or oxygen-18 concentrations in surface water and infiltrate. The main determinants of the interaction between surface water and groundwater are the distribution of areas with different infiltration rates, the thickness of sediment layers and the hydraulic head gradient. These conditions determine the volume and velocity of infiltrating water which, together with the direction of water flow, are required to model the interaction processes. Usually, due to difficulties with measurement, only the direction of water flow is determined and boundary conditions are estimated from simplified assumptions.

Field techniques have now been developed to help characterise surface water/groundwater interaction. Results from field experiments using a percussion probe and a large-scale laboratory column experiment set up to simulate infiltration processes are presented.

Owing to its differing concentrations in groundwater and river water, the naturally occurring isotope Radon-222 (²²²Rn) can be used as a natural tracer to determine the residence time of infiltrated water. The principle is based on the determination of ²²²Rn activity at defined points along the flow path. Investigations performed in a large-scale laboratory column experiment showed that different effects considerably influence infiltration measurements. Local sedimentary stratification has a substantial influence on the equilibrium concentration of ²²²Rn. Furthermore, investigations in zones with gas formation (e.g. in biologically active zones such as river beds) must consider diffusion of ²²²Rn into the gas phase and the reduction of permeability because of gas within the pore space. The volume of gas in the saturated, upper zone of the aquifer has an important influence on the results of ²²²Rn measurements. Advantages and limitations of the use of ²²²Rn measurements for the determination of infiltration rates are discussed based on results of laboratory experiments.

W. Macheleidt, T. Grischek, W. Nestler

Bioclogging in Porous Media: Tracer Studies

Abstract

Tracer studies show that the flow regime may transform from near uniform flow at the starting conditions to non-uniform flow under conditions with severe bioclogging. The mode of observation (flux averages or point measurements) thus becomes important. It is proposed that bioclogging may lead to changes in transport patterns as well. A first phase, where the dispersivity increases approximately linearly as the hydraulic conductivity decreases is explained as the result of an increase in the number of microcolonies located strategically in pore throats. A second phase follows, where the capacity for diffusion between the mobile water phase and the immobile biophase has increased, leading to significant tailing in solute breakthrough. A third phase may develop, where preferential flow paths results in fracture-like breakthrough. The results show that calculated changes in bulk hydraulic conductivity may be reproducible from experiment to experiment, while, in some cases, and especially those involving point injection of nutrients, the initial heterogeneous distribution of bacteria will affect the development of bioclogging patterns.

Peter Engesgaard, Dorte Seifert, Paulo Herrera

Riverbank Filtration in the Netherlands: Well Fields, Clogging and Geochemical Reactions

Abstract

River Bank Filtration (RBF) contributes ca. 7% (80 Mm³/a) to the national drinking water supply in the Netherlands, through a total of 26 well fields. These RBF well fields are classified on the basis of (1) the main driving mechanism of flow (polder or pump driven); (2) RBF periodicity (flow direction temporarily reversing or not), (3) type of riverbed (sand or gravel), and (4) type of contact of river with aquifer (with or without intercalated aquitard(s)).

Three case studies are reviewed which demonstrate the water quality, geochemical reactions and clogging phenomena in differing systems. The mass balance approach, also called ‘reverse modeling’, is applied to identify and quantify the extent of the most important hydrogeochemical reactions at the three case study sites.

Clogging of the river bed seems to be a problem in the Netherlands only in RBF systems with a true gravel bed such as Roosteren along the Meuse River, and on sites where sludge is strongly accumulating due to structurally reduced river flows, as in the Hollandsch Diep estuary which was dammed in 1971 as part of the Delta Works.

Pieter J. Stuyfzand, Maria H. A. Juhàsz-Holterman, Willem J. de Lange

Clogging-Induced Flow and Chemical Transport Simulation in Riverbank Filtration Systems

Abstract

Riverbank filtration is a low cost treatment technology which is effective in removing various chemical, and biological contaminants from the surface water. In the United States, utilities that employ horizontal collector wells, have reported clogging of the riverbed in vicinity of the wells, particularly around the laterals that go toward the river. In this paper, we show the impact of clogging and associated reduction in leakage on flow and transport simulations.

Chittaranjan Ray, Henning Prommer

Use of Aquifer Testing and Groundwater Modeling to Evaluate Aquifer/River Hydraulics at Louisville Water Company, Louisville, Kentucky, USA

Abstract

In 1999, the Louisville Water Company completed construction of a radial collector well adjacent to the Ohio River in Louisville, Kentucky at their B. E. Payne Water Treatment Plant. The well was completed in a sand and gravel aquifer to a depth of 105 feet as part of a pilot study to evaluate the feasibility of converting their surface water supply to riverbank infiltration. One of the objectives of the study was to estimate the total yield capacity available along the shoreline on the Payne Plant property. It was hoped that the supply developed at this location could supply 25 percent or more of the water company’s requirement of 240 million gallons per day.

Beginning in August 1999, a 70-day constant-rate pumping test was conducted on the well to evaluate aquifer properties. The parameters of interest included aquifer transmissivity, leakance between the Ohio River and the aquifer, and vertical anisotropy ratio of the aquifer sediments. The aquifer coefficients determined from the pumping test were applied in a groundwater flow model to predict yields of various extraction facilities designs for the site.

Three design options were considered for the Payne Plant site. One design incorporated two or more new collector wells in addition to the pilot well, connected by a subterranean tunnel drilled in the shale and limestone bedrock beneath the sand and gravel aquifer. The second option was to install a large diameter tunnel within the sand and gravel aquifer and extend well screen laterals from the tunnel to produce water. The third option was to drill conventional vertical wells, but connect them to a subterranean tunnel drilled in the bedrock.

Modeling showed that all three of the design options could produce the desired yield. This meant that the design and construction decision could be driven by the economics of the project. Modeling was used further to track the decline in yield of the pilot collector well over time caused by clogging and compaction of the riverbed sediments. Modeling showed average riverbed leakance reductions of approximately an order of magnitude.

Dave C. Schafer

Changes in Riverbed Hydraulic Conductivity and Specific Capacity at Louisville

Abstract

The Louisville Water Company constructed a 76,000 m³/day capacity radial collector well and started pumping from the alluvial aquifer in July, 1999. After start-up, the specific capacity of the wellfield was measured to be much greater than was predicted during the design phase, and after one year of pumping additional riverbank filtration (RBF) capacity was planned using these higher estimates of specific capacity. Subsequent years of pumping indicated a steady decrease in specific capacity, and designs for additional RBF capacity was adjusted based on more reliable estimates of long-term sustainable yield. This paper reviews the data collected from this site, provides calculations of specific conductance over a 5 year period, and interprets data into values for riverbed conductivity at start-up and after 5 years of operation.

Stephen A. Hubbs

Experience with Riverbed Clogging Along the Rhine River

There is no such thing as a free lunch

Abstract

Clogging of the riverbed caused by the operation of riverbank filtration wells is a highly dynamic process, governed not only by varying pumping rates, but by the runoff dynamics of the river and by the quality of the river water. Investigations of the riverbed and the river-aquifer interactions at two RBF sites in the Lower Rhine region will be presented. The different behavior of both RBF plants confirms the importance of stream processes and the adaptation of pumping rate for sustainable yield.

Jürgen Schubert

Heat as a Ground-Water Tracer at the Russian River RBF Facility, Sonoma County, California

Abstract

Temperature is routinely collected as a water quality parameter, but only recently utilized as an environmental tracer of stream exchanges with ground water (Stonestrom and Constantz, 2003). In this paper, water levels and seasonal temperatures were used to estimate streambed hydraulic conductivities and water fluxes. Temperatures and water levels were analyzed from 3 observation wells near the Russian River RBF facility, north of Forestville, Sonoma County, CA. In addition, 9 shallow piezometers were installed in 3 cross-sections across the stream near a pair of collector wells at the RBF facility. Hydraulic conductivities and fluxes were estimated by matching simulated ground-water temperatures to the observed ground-water temperatures with an inverse modeling approach. Using temperature measurements in the shallow piezometers from 0.1 to 1.0 m below the channel, estimates of infiltration indicated a distinct area of streambed clogging near one of the RBF collector wells. For the deeper observation wells, temperature probes were located at depths between 3.5 m to 7.1 m below the channel. Estimated conductivities varied over an order of magnitude, with anisotropies of 5 (horizontal to vertical hydraulic conductivity) generally providing the best fit to observed temperatures.

Jim Constantz, Grace W. Su, Christine Hatch

Monitoring Clogging of a RBF-System at the River Enns, Austria

Abstract

This presentation comprises hydraulic aspects of a research project at a bank filtration site at the oligotrophic alpine river Enns in Austria. The project was started in order to deepen the understanding of filtration and transformation processes which take place, where they take place and how stable they are throughout the year. Extensive monitoring equipment has been installed in the river bank focusing on the first meter of the flow-path from the river to the well. During the start-up period of well production the built-up of a clogging layer is monitored. Due to the dynamic interrelation between infiltration rate and hydraulic conductivity of the riverbed, clogging shows a balancing effect on infiltration along the bank stretch.

B. Wett

Managing Resources in an European Semi-Arid Environment: Combined use of Surface and Groundwater for Drinking Water Production in the Barcelona Metropolitan Area

Abstract

Barcelona’s public water supply depends on surface water, groundwater, riverbank filtration, and artificial recharge. The semi-arid climate provides challenges to supplying water, and methods have been developed to manage the riverbed/aquifer interface at the point of infiltration of the riverbank filtration site. The hydrogeology, water quality, and operational elements of the Barcelona water supply are presented

Jordi Martín-Alonso

Presentation of Data for Factors Significant to Yield from Several Riverbank Filtration Systems in the U.S. and Europe

Abstract

Yield in riverbank filtration (RBF) systems is affected by a variety of factors including the geology, hydraulics, site layout, and operational characteristics of each site. This paper identifies key parameters that affect yield in riverbank filtration systems and presents data for these parameters from RBF sites in the U.S. and Europe.

Tiffany G. Caldwell

Titel: Riverbank Filtration Hydrology
herausgegeben von: Stephen A. Hubbs
Verlag: Springer Netherlands
Electronic ISBN: 978-1-4020-3938-6
Print ISBN: 978-1-4020-3936-2
DOI: https://doi.org/10.1007/978-1-4020-3938-6