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Monitoring large diameter sewers
Marine Pollution Bulletin
measurements of nutrients and the report includes details of a proposed intercomparison exercise to resolve these latter difficulties. This will commence in 1989. ICES has continued to be active in other aspects of analytical intercomparisons and the 1988 report mentions several exercises that are either in progress or have been completed. Interestingly the results of some of these exercises are now being applied to assessing the extent to which differences in contaminant levels are likely to be detectable over time. For sea water and surficial sediments the conclusion is that, in most situations and for most contaminants, this will not be possible, unless the change involved is large, i.e. of the order of at least a factor of two.
Monitoring Large Diameter Sewers A prototype flow monitoring and telemetry system devised by Golden River Water Ltd in conjunction with the Sewer Systems group of the Thames Water Authority has been permanently installed in a sewer in London. Measurements underground are cabled back to a street-level pavement box which houses a DOLPHIN data logger (manufactured by Golden River for operation in field conditions) and communications equipmerit. This will be interrogated regularly by an officebased PC and modem via the standard telephone network to download data and then processed using one of Golden River's standard software modules for numerical and graphical analysis. This module has the capability of 'zooming' in on any area of particular interest where required. It also provides data in a form which can be processed using a proprietary spreadsheet/graphics package. The flow monitoring system provides a number of opportunities for monitoring and control of the whole of any city's sewer system once extended to a number of sites. For instance, acting on the information gathered in real-time to operate penstock valves and sluice gates, it is possible to control the system far more accurately and to divert water away from areas of high demand. This can reduce the chance of flooding with its consequent social and financial costs and provide a more regulated flow into treatment works to eliminate the occasional need to discharge untreated liquid into watercourses, In the prototype installation, depth of the flow is being measured with pressure gauges fixed to the floor of the sewer pipe. Velocity is measured by timing two 194
Again in response to questions raised by the Cornmissions, the report addresses the topic of assessing inputs of contaminants to the environment via rivers. This review includes some comments on the Paris Commissions proposals for a gross river input study in 1990 and advice on how to assess net river inputs via estuaries to coastal waters and the open ocean. ICES has been involved in a number of regional assessments or quality status reports in recent years. In the light of its experiences in the course of producing these reports it has reviewed its earlier guidelines on the conduct of such studies and the production of reports. The 1988 report includes these revised guidelines.
sets of ultrasonic pulses passing through the liquid from one side of the sewer to another in each direction at around 45 ° to the direction of flow. As the transmission time for the pulse varies in relationship to the rate of flow and its direction, the two values can be fed into a simple equation which eliminates the velocity of sound in the fiquid. This factor is used by the way in which the pulses are timed and processed virtually to cancel out any density effects. The system promises to be extremely cost-effective and incorporates a series of back-ups in the event of power or telephone failure. More information on this and other equipment for logging and transmitting water flow data can be obtained from: Golden River Water Ltd., 3 Wedgewood Road, Bicester, Oxon. OX6 7LU, UK.
Seawater Desalination Plant The Reliable Water Company have recently introduced their RW-2 seawater desalination plant. The plant is totally automatic being run by twin computers and no operator is required for normal operation. Maintenance instructions are given to local service personnel by the computers. A proprietary energy recovery system based on standard hydraulic technology reduces the energy required for seawater desalination to less than 4 kWh m -3. The RW-2 plant employs the best reverse osmosis membranes available with high quality components and advanced design to minimize corrosion problems. For additional information contact: Marketing Department, Reliable Water Company, 35 Dunham Road, Billerica, MA 01821, USA.
measurements of nutrients and the report includes details of a proposed intercomparison exercise to resolve these latter difficulties. This will commence in 1989. ICES has continued to be active in other aspects of analytical intercomparisons and the 1988 report mentions several exercises that are either in progress or have been completed. Interestingly the results of some of these exercises are now being applied to assessing the extent to which differences in contaminant levels are likely to be detectable over time. For sea water and surficial sediments the conclusion is that, in most situations and for most contaminants, this will not be possible, unless the change involved is large, i.e. of the order of at least a factor of two.
Monitoring Large Diameter Sewers A prototype flow monitoring and telemetry system devised by Golden River Water Ltd in conjunction with the Sewer Systems group of the Thames Water Authority has been permanently installed in a sewer in London. Measurements underground are cabled back to a street-level pavement box which houses a DOLPHIN data logger (manufactured by Golden River for operation in field conditions) and communications equipmerit. This will be interrogated regularly by an officebased PC and modem via the standard telephone network to download data and then processed using one of Golden River's standard software modules for numerical and graphical analysis. This module has the capability of 'zooming' in on any area of particular interest where required. It also provides data in a form which can be processed using a proprietary spreadsheet/graphics package. The flow monitoring system provides a number of opportunities for monitoring and control of the whole of any city's sewer system once extended to a number of sites. For instance, acting on the information gathered in real-time to operate penstock valves and sluice gates, it is possible to control the system far more accurately and to divert water away from areas of high demand. This can reduce the chance of flooding with its consequent social and financial costs and provide a more regulated flow into treatment works to eliminate the occasional need to discharge untreated liquid into watercourses, In the prototype installation, depth of the flow is being measured with pressure gauges fixed to the floor of the sewer pipe. Velocity is measured by timing two 194
Again in response to questions raised by the Cornmissions, the report addresses the topic of assessing inputs of contaminants to the environment via rivers. This review includes some comments on the Paris Commissions proposals for a gross river input study in 1990 and advice on how to assess net river inputs via estuaries to coastal waters and the open ocean. ICES has been involved in a number of regional assessments or quality status reports in recent years. In the light of its experiences in the course of producing these reports it has reviewed its earlier guidelines on the conduct of such studies and the production of reports. The 1988 report includes these revised guidelines.
sets of ultrasonic pulses passing through the liquid from one side of the sewer to another in each direction at around 45 ° to the direction of flow. As the transmission time for the pulse varies in relationship to the rate of flow and its direction, the two values can be fed into a simple equation which eliminates the velocity of sound in the fiquid. This factor is used by the way in which the pulses are timed and processed virtually to cancel out any density effects. The system promises to be extremely cost-effective and incorporates a series of back-ups in the event of power or telephone failure. More information on this and other equipment for logging and transmitting water flow data can be obtained from: Golden River Water Ltd., 3 Wedgewood Road, Bicester, Oxon. OX6 7LU, UK.
Seawater Desalination Plant The Reliable Water Company have recently introduced their RW-2 seawater desalination plant. The plant is totally automatic being run by twin computers and no operator is required for normal operation. Maintenance instructions are given to local service personnel by the computers. A proprietary energy recovery system based on standard hydraulic technology reduces the energy required for seawater desalination to less than 4 kWh m -3. The RW-2 plant employs the best reverse osmosis membranes available with high quality components and advanced design to minimize corrosion problems. For additional information contact: Marketing Department, Reliable Water Company, 35 Dunham Road, Billerica, MA 01821, USA.