STAKEHOLDER INVOLVEMENT IN WATER-RESOURCES PLANNING

This paper discusses experiences of consultation and participation in water-resource planning studies in the Thames catchment. Two different case studies are presented and the challenges which were encountered are discussed. The authors conclude that, whilst the inclusion of stakeholders in the decision-making process has clear benefits, the answers to questions such as (a) who to involve, (b) when to involve them, and (c) how to present information to them, are not always clear.     

Groundwater Resources: Balancing Perspectives on Key Issues Affecting Supply and Demand

Sustainable groundwater management requires (a) maximizing the use of aquifer storage to reduce water-supply costs while limiting environmental impacts, and (b) maximizing groundwater protection to reduce water-supply treatment needs while not unduly restricting land-use activities. These key issues are evaluated from the experience of a recent and comprehensive national strategic study, involving detailed consultation with many stakeholders with an interest in groundwater resources. Such balances are not easy to achieve because groundwater systems are complex to analyse and slow to respond to change, resulting in considerable uncertainty in assessment and prediction without in-depth research and high-resolution monitoring. Current institutional and regulatory arrangements for the water sector in England and Wales do not appear to be achieving the best possible use of aquifer storage and optimal investment in groundwater protection.     

Ozone and the Formation of Bromate in Water Treatment

The ozonation of water is widely used within the drinking-water industry. The improvement of the performance of the Barcombe water-treatment works is envisaged. An ozonation stage and granular activated carbon filtration are being considered as an addition to the existing plant. As part of the investigation work, the influence of ozone on bromate formation was studied using a 3 m³/h pilot plant. The bromate production was found to depend upon (a) the applied ozone dose, (b) the contact period, and (c) the pH.
Using ozone in an appropriate way will be of benefit to the treatment process as well as meeting the new World Health Organization health guidelines for drinking water.     

Use of Cement Kilns in Managing Solid and Hazardous Wastes: Implementation in Australia

The use of cement kilns for managing solid and hazardous wastes is facilitated by the high temperature, long gas retention periods, natural alkaline environment, minimum amount of waste produced and high thermal capacity. The main benefits include energy recovery, conservation of fossil fuels, reduction in cement production costs and the use of already existing facilities.
The test burns conducted in cement kilns worldwide have demonstrated very high destruction efficiencies for most stable organic compounds, with toxic contaminants barely above the background levels.
There are several cement plants in the US and Europe presently using solid and hazardous wastes as supplementary fuel. The application of this technology in Australia has been ignored in the past. An international conference (Kilnburn'92) on the role of cement kilns in waste management was held recently in Australia and has enhanced the implementation of this technology in Australia.     

Integrated Catchment Modelling as a Water Resources Management Tool

Groundwater models are becoming increasingly important in water resources management. Most aquifers in the UK are closely linked with river systems, to which they contribute baseflow from seepages and springs. As a result, major groundwater abstractions almost inevitably affect river flows. To assess with confidence the effect of utilizing ground-water resources, an aquifer and river system has to be linked within an integrated model which can simulate varying hydrogeological conditions throughout the catchment.
The main features of an integrated catchment management model, which links aquifer and river systems, are described in this paper. The model has been applied to a number of catchments in southern England including the River Darent in Kent, which is probably the most well-known and worst-affected of all rivers identified nationally as suffering from over-abstraction.
The process of model preparation and calibration is illustrated with reference to the River Darent. Twenty years of river flow and groundwater hydrograph records were used in producing a close simulation of modelled and actual hydrological conditions. The model was then operated to assess a large number of possible options for restoring flows to the river. Examples of various management strategy simulations are given, leading to formulation of a water resources management plan for the Darent. This involved (a) reductions in selected abstractions, (b) flow augmentation using river support boreholes, and (c) meeting peak groundwater supply demands in drought periods.     

King's Lynn Sewer Improvements

King's Lynn is a typical English port and market town, located at the edge of the very flat fenland area in East Anglia. The town doubled in size to its present population of 40000 from the end of the Second World War. Although the sewerage system expanded with the growth of the town, the prevailing flat gradients gave rise to much sedimentation and loss of capacity, while tide-locked outfalls restricted freedom of flow from the storm-overflow facilities. The result was widespread flooding in many areas of the town during relatively minor storms. This paper describes the studies which were carried out using computer simulation methods to identify the weaknesses and deficiencies of the complex sewerage system, and the innovative tunnelling solution which was adopted to overcome the problems. An indication is also given of the benefits of good public relations when working across the urban environment.     

Low-Cost Remote-Sensing Techniques Applied to Drainage Area Studies

The paper describes a project in which colour and infra-red video images were used as the basis for assessing the percentage impermeability of subcatchments for a WALLRUS model. The imagery was obtained from helicopter-mounted video cameras. Computer processes were developed to convert raw data, which were in analogue format, into a format which could be manipulated and displayed by the computer. The computer was able to assess the total permeable and impermeable areas in each subcatchment. These data were used in the WALLRUS model and compared with the results obtained using manually derived data and results from the flow verification survey.     

Locating Outfalls on Meandering Channels to Optimise Transverse Mixing

Many sources of river pollution approximate steady-state conditions and, under such conditions, the rate of transverse mixing is critical in determining the impact of pollutants. Results are presented from transverse-mixing experiments which were carried out on a large-scale laboratory channel with meander planform geometry of natural cross-section, generated by flow over a mobile bed. Dye-tracer measurements below three point sources within one cross-section are presented and compared, together with hydrodynamic measurements. The results show the importance of locating outfalls to maximise mixing rates, hence minimising pollution impact (depending on the environmental need). A release on the outside of a bend is shown to result in a faster rate of transverse mixing than a release on the inside of a bend.     

Assessment of Microbial Populations in Activated Sludge Using an Organism Diversity Index

An organism diversity index for use with mixed liquor or wastewater samples was developed to assess the species richness and diversity of activated sludge. The index was used in several studies and was found to be fast and simple to perform using basic laboratory equipment. Two bench-scale and two pilot-scale studies found that the resulting 'organism diversity index'value was a good indicator of process performance and was not influenced by the total concentration of the mixed-liquor suspended solids but by their nature alone. The technique rapidly yielded pertinent information about the health of the sludge and could be used instead of genetic investigations to obtain population information quickly enough for wastewater-treatment plant process control.     

Foam Formation, Anaerobiosis and Microthrix Parvicella

Microscopic examinations of the sludges associated with two incidents of foam formation in anaerobic digesters are described. In both cases, the dominant filamentous species was Microthrix parvicella. Preliminary growth studies with this species indicated that it could grow in both aerobic and anaerobic environments, but that in an anaerobic regime it did not produce polyphosphate granules. This suggests that M. parvicella may be involved in the luxury uptake of phosphate and, under strict anaerobic conditions, could compete with acetoclastic methanogens for acetate.