IWP&DC talked to a few of the companies exhibiting at the British Dam Society’s 13th Biennial conference to discover what they have in store for visitors
In 2003, Carpi was involved in California’s Olivenhain dam, the highest and largest RCC dam in the US. An exposed PVC geocomposite, anchored with Carpi patented tensioning system, was installed on the 94.5m high dam to ensure continuous uninterrupted impermeability in the event of major seismic activity.
2004 marks Carpi’s 40th anniversary of activity in waterproofing dams, canals, hydraulic tunnels and reservoirs. So far this year six new dam projects have been awarded to the company, details of which are:
Salt Springs, US
A 101m high concrete faced rockfill dam (CFRD) at 1209m elevation, Salt Springs dam has been damaged by frequent snow and ice. The CFRD will be rehabilitated in two campaigns, in 2004 and 2005, when the water level is at the minimum, to minimise impact on operation. Some 26,790m2 of geocomposite liner consisting of a flexible Polyvinylchloride (PVC) geomembrane, 2.5mm thick, coupled to a geotextile, will be installed at the dam. The geocomposite is exposed, and anchored with Carpi patented drained tensioning system.
A 50m high CFRD completed in 1981 and heightened in 1991, Midtbotnvatn is covered in winter by several layers of ice, 50 to 60cm thick. As a result, the most deteriorated older part of the dam, from the plinth to the elevation of the heightening, needs to be rehabilitated. Around 8000m2 of geocomposite liner, of the same specifications used at Salt Springs, is being used during the rehabilitation works.
Lechstaustufe Prem 2, Germany
Rehabilitation work is being carried out on the 15m high, 2700m long Lechstaustufe Prem 2 earthfill dam. The original bituminous concrete facing is being rehabilitated in the most deteriorated part, from elevation 742.3m to elevation 746.5m (wave break wall), with an exposed flexible polypropylene geocomposite, 1.8mm thick. Some 17,550m2 of the liner will be installed.
The arches and gravity abutments of this 28m high multiple arch dam will be lined with 4720m2 of geocomposite consisting of a flexible PVC geomembrane, 2.5mm thick, coupled to a geotextile. The geocomposite is exposed and anchored with Carpi patented drained tensioning system.
Burnett River, Australia
A 35m high RCC dam is to be constructed using as permanent formworks prefabricated concrete panels lined with a geocomposite consisting of a flexible PVC geomembrane, 2mm thick, coupled to a geotextile. Some 19,400m2 will be installed
Lago di Mezzo, Italy
The 31m high gravity dam will be rehabilitated with 2300m2 of exposed geocomposite consisting of a flexible PVC geomembrane, 2.5mm thick, coupled to a geotextile.
A paper will be presented in Session 2, on Wednesday 23 June, covering updated information on geomembrane systems, and including some case histories of Carpi projects. Further information on the latest developments of Carpi systems, including underwater installation, will be available at the exhibition.
HR Wallingford (HRW) offers help in: dambreak analysis; risk assessment/management; design/performance assessment; management of water supply/resources; and reservoir sedimentation.
Dambreak – collaborative research has an IMPACT
IMPACT (Investigation of Extreme Flood Processes and Uncertainty), an EC-funded collaborative research initiative,
focuses on five key topics: breach formation; flood propagation; sediment movement; geophysical investigation; uncertainty analysis. Results are due in 2004 (www.impact-project.net).
HRW has helped to develop and apply risk assessment procedures including those set out in CIRIA publication C542 ‘Risk Management for UK Reservoirs’ and, more recently, tools and techniques for flood risk management for the UK Environment Agency.
Assessing design and performance
Engineering, environmental and management issues need to be addressed when designing, maintaining and operating a dam. Physical and computational modelling can help – for example in prioritising maintenance and investigative works for a portfolio of dams to ensure optimal value from finite resources. Equally, analysis of specific design and operational parameters typically involves the client in an expenditure of between 0.1 and 1% of the total capital outlay for the project.
Securing water resources
HRW has worked with Southern Water to estimate reservoir yields, based on historical data and future climate change scenarios, for a proposed major new reservoir and smaller storage schemes in the South East of England.
Recent work has included evaluating sediment inputs to reservoirs in Sri Lanka and Algeria and advising on the impacts of a range of measures to extend the useful lives of the reservoirs.
If you would like more information, please contact Mark Morris at: email@example.com.
Survey and Engineering Projects
SURVEY and Engineering Projects (SEP) Ltd has been contracted by a number of water power companies and consultant engineers to produce quality, accurate data across the whole spectrum of surveying throughout the hydro industry.
As part of its on-going contract with United Utilities, SEP Ltd was asked to survey one of the company’s many dams and reservoirs in the Lake District using the very latest GPS systems. With a Leica GPS System 500, the company monitored the movement of the dam using three existing survey stations comprising two kern permanent reference plates drilled and secured on remote rock outcrops, and an existing concrete survey pillar constructed some years earlier.
There are a number of monitoring points along the dam which consist of stainless steel pins concreted into the structure and covered by small valve boxes. A minimum of four static GPS co-ordinated points were taken over the centre of each pin.
The position of each pin was calculated using the mean average of the six static GPS points taken over each monitoring pin and the co-ordinates were then compared with previous survey data to determine the movement or change of condition.
The latest GPS systems allied to SEP’s complimentary software capabilities and flexibility in the use of Static GPS and Real Time Kinematic (RTK) GPS provide a number of major benefits chief amongst these being speed and versatility in unfavourable conditions, for example in bad weather or low light conditions.
At the conference, the company will be showcasing its services and skills together with the very latest geo-systems which it uses to support the hydro industry.
Soil Instruments Ltd was formed in 1962 in response to a need for the monitoring of in-situ pore pressures in earthfill dams that had begun to show signs of failure. The company became involved with the monitoring of a number of large dams being designed by UK consultants in countries including Pakistan, Argentina, Nigeria and Malaysia.
The UK-based company now specialises in the design, development, manufacture and installation of a wide range of geotechnical instrumentation, designed to measure the parameters that govern elements of design, construction monitoring and the on-going safety of structures and environments.
The range includes equipment for monitoring: horizontal and rotational movements; changes in physical dimensions; changes in loading pressures; settlement and vertical movements.
Services provided include: installation assistance; repair; calibration; regular servicing; and rental.
Soil instruments has been involved in a number of international dam projects, including schemes in Algeria, Argentina, Cyprus, England, Greece, Iran, Lesotho, Malaysia and Morocco.
With the acquisition of Soil Instruments by ITM (Instrumentation, Testing and Monitoring) Ltd in 2002, the company has been strengthened by the commitment to increase its use of modern technologies. Amongst others, these include data
acquisition systems, wireless communications and data presentation software.
For more information on Soil Instruments and its products, see www.soil.co.uk.