Investigation of River Flow Failure at Sleaford

The River Slea through Sleaford is fed by groundwater emanating from the Lincolnshire Limestone. In recent years, the springs have dried up periodically, causing failure of river flow through the town. The Slea is a main feature of the town and, when flowing, a valuable visual amenity. Conversely, when it is not flowing, progressive water quality deterioration in ponded sections reduces the river corridor to an eyesore. The paper describes investigations into the cause of the problem and how to overcome it.     

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.     

Diffuse Sources of Pollution by Heavy Metals

Significant reductions in the amount of heavy metals released to the aquatic environment have been achieved by applying strict controls on point source industrial discharges. Because of these tight controls, diffuse pollution sources have increased in importance as a contribution to the total load. Diffuse inputs originate mainly from the use of chemical products. Thus control of these inputs can be achieved by refraining from or limiting the use of these products or by restricting the amount of heavy metals permitted in such products. Control of diffuse sources of heavy metals could be based on a 'positive approval'system, permitting only those uses which do not lead to environmental harm and which could not be replaced by less harmful alternatives. Assessing the environmental impact of the alternatives will require the introduction of a 'cradle to grave'approach.     

KNOWLEDGE-BASED SYSTEM ON WATER-RESOURCE MANAGEMENT IN COASTAL WATERS

Computers which are used conventionally in numerical models for problem-solving and fast number-crunching are not user-friendly and lack knowledge transfer in model interpretation. Recent advances in artificial intelligence make it possible to systemise the experience and decision-making procedures of human experts. This paper describes the development of a prototype knowledge-based system (an advanced technique of artificial intelligence) as a knowledge-transfer tool for water-resource planning and management in coastal waters. The system can (a) run on a desktop computer and (b) act as a design aid, to assist in numerical modelling to simulate flow and/or water quality. Using the application in Hong Kong coastal waters, it was verified that the prototype system had the capability to undertake the reasoning process to select the model and associated parameters, equivalent to a human expert.     

OPERATIONAL EXPERIENCE FROM A SMALL FOOTPRINT LAMELLA AND BAFF PLANT IN ABERDEEN.

The city of Aberdeen has a population of 265,000 people, which was previously served by a preliminary sewage treatment facility, Including screening and grit removal prior to discharge to the North Sea.
The Nigg Waste Water Treatment Works (WwTW) was designed and built to treat the sewage from Aberdeen as part of a Private Finance Initiative (PFI) in order to achieve Urban Waste Water Treatment Directive (UWWTD) standards for BOD (25mg/l 95%ile) and COD (125mg/195%ile). A small footprint plant was required and involved lamella tube settlers for primary treatment followed by a Biological Aerated Flooded Filter (BAFF) plant for secondary treatment.
The plant received loads above the design and chemical closing was applied to increase the capacity for treatment. Constant monitoring through the plant was put in place in order to optimise the performance. This paper gives details of the performance of the plant over the first year of operation.     

Supervision of Sewers for Adoption

The Water Authorities Association guide 'Sewers for Adoption' has achieved considerable success in unifying practice and establishing well-understood and recognized standards for the design and construction of sewers by developers under Section 18 of the Public Health Act 1936. However, the supervision provided by the adopting authorities — particularly in relation to supervision fees — has been an area of dispute for some time.
The Construction Industry Research and Information Association (CIRIA) has recently completed a study on the optimum levels of supervision for sewer construction. The study included a national survey on the nature and extent of problems occurring during the course of Section 18 work and the supervision practices presently being undertaken. The study puts forward recommendations on the nature and timing of periodic inspections undertaken during construction. Several specific problem areas are discussed, ranging from measures required to ensure that design submissions are of an adequate standard, to the timing of any pre-adoption closed-circuit television inspection. This paper draws upon the contents of the report and discusses some of the principal findings and recommendations of the study.     

A Standardized Low-Cost Low-Flow Gauging Station

This paper describes the origins and development of a simple, low-cost, low-flow stream gauging station to meet the operational requirements of a major water resource management system. The utilitarian design uses standardized, prefabricated components in order to achieve maximum economy and ease of construction without sacrificing durability or hydrometric accuracy.     

South West Water's 'Clean Sweep' Programme: Some Engineering and Environmental Aspects

The requirements of environmental legislation demand a massive clean-up of coastal discharges for Devon, Cornwall and West Dorset. South West Water Services Limited have developed a marine improvement programme which (a) is the largest of its type in Europe and (b) seeks to address the requirements of legislation incorporating town planning policies together with the increasing public awareness of environmental issues. The pressures around the region's coastline within the foregoing framework set the challenge of achieving the required understanding of coastal processes, together with the implementation of engineering solutions to meet with society's expectations. These have to be achieved at least cost and provide the most innovative and effective engineering solutions for the efficient implementation and management of such a programme.     

Flood Generation Modelling

This paper summarizes recent research and development of a particular process-based runoff generation model, the Institute of Hydrology Distributed Model. Surface and subsurface flow equations are linked in a hydrologically appropriate system to allow simulation of catchment runoff processes. Predictions can be made of channel flow, surface runoff and subsurface flow, pressure potentials and water contents. The structure and methods of the model are described and its data and computing requirements are outlined. Field and systematic applications are discussed, together with the work carried out on providing guidelines for use for the wider hydrological community.