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Birchwood, United Kingdom

Coombs R.,MWH
Dams and Reservoirs | Year: 2016

This paper covers a technical comparison of results from two physical scale models and a computational fluid dynamics (CFD) model that was undertaken for a masonry stepped spillway at Grassholme reservoir. The spillway is known to be deficient in terms of the depth of the collection channel and the size of the stepped spillway. Using the performance of the spillway during a flood in 1991 as a benchmark, the two modelling methods are compared. It is found that the physical scale models cannot match the full scale behaviour of spillway. The CFD model was undertaken in a way so as to account for air entrainment and flow bulking, and this formed a better estimate of the chute behaviour witnessed during 1991. © ICE Publishing. Source

Eddleston M.,MWH
Dams: Engineering in a Social and Environmental Context - Proceedings of the 17th Conference of the British Dam Society | Year: 2012

Historically many aspects of geotechnical design have tended in favour of the deterministic methods of analysis based on the concept of Factors of Safety over probabilistic methods. This is particularly the case when considering the slope stability of dams. In recent years, with the introduction of Eurocode 7, the geotechnical community in the UK has been coming to terms with the use of the Limit State approach to geotechnical design which defines the relationship between design parameters and performance criteria. This generally involves factoring up loads and factoring down calculated soil parameters such as shear strength. The factors are statistically calculated to produce a design that has an acceptably low probability of failure although the approach gives no indication of what the value might actually be. Using statistical methods to determine the characteristic values may only be performed effectively when data comes from sufficiently homogenous identified populations or when sufficient data is available. It is rarely possible and relevant to adopt statistics particularly when investigating old embankment dams where it is sometimes suggested that the actual process of undertaking major intrusive investigations with boreholes could have a detrimental effect on the performance of the dam and where internal erosion could have an influence on overall slope stability. The paper explores the potential application of a risk based approach, assisted by the use of quantified risk profiles used in flood risk management, to better understand the current performance of the slopes of old embankment dams. Source

Kovacevic N.,Geotechnical Consulting Group | Hight D.W.,Geotechnical Consulting Group | Potts D.M.,University of London | Carter I.C.,MWH
Geotechnique | Year: 2013

An existing 15.5 m high main dam embankment at Abberton Reservoir in Essex was completed in August 1938, since when its performance has been satisfactory. However, the upstream embankment shoulder of the original dam suffered a deep-seated failure through its foundation towards the end of construction in July 1937, 9 days before a similar and well-known failure occurred at Chingford Reservoir in close proximity to Abberton. Whereas the failure at Chingford became an important case in the history of soil mechanics through the involvement of Karl Terzaghi and marked one of the first applications of modern soil mechanics principles, the failure at Abberton has remained largely unknown, until recently when raising of the existing dam started to be considered. This paper describes advanced finite-element analyses which were carried out to investigate the failure of the original dam at Abberton and the stability of the existing main dam. The parameters used in the constitutive models were derived on the basis of the available site investigations and laboratory testing and on experience in the back-analysis of other failures in London Clay. The analyses demonstrated that the upstream shoulder of the original embankment failed through the mechanism of progressive failure, which involved the top of the stiff plastic London Clay rather than the overlying alluvium in the foundation. The relatively rapid rate of embankment filling, achieved by using modern earthmoving equipment, contributed significantly to the original dam failure. The analyses also demonstrated satisfactory behaviour of the existing dam during reconstruction, the first impounding and in the long term, with its response being similar to that observed. Thus the constitutive models used and parameters derived were successfully calibrated against the observed behaviour of both the original and existing main dams at Abberton, and could be used in predicting the behaviour of the dam during and after its proposed raising. Source

Edwards J.,MWH
Journal / American Water Works Association | Year: 2010

What started as an informal effort to provide better technical training for a group of engineers in one office of MWH has blossomed into a companywide effort to engage and develop its young professionals. Nearly two decades after its initial inception, the Young Professionals Group (YPG) is a key component of MWH's global efforts to recruit, retain, and engage so-called "MiIlennials," who bring specific needs and talents to the workplace. This article provides specific information about how companies can effectively engage and retain their young employees by providing them with the flexibility to initiate programs that address their different needs in the marketplace while also allowing them an outlet to improve and engage their communities. This information will be important for human resource departments and the youth leadership within the water industry as the sector experiences the anticipated rise in employment of young professionals and the simultaneous retirement of Baby Boomers over the next 10-20 years. Source

The present disclosure provides a methodology that incorporates real-time measurement of conductor temperatures and ground clearances using a transmission line monitor, coupled with information technology and data analytics, to allow utility operators to manage their transmission systems using a dynamic line rating process. Dynamic line ratings may incorporate real-time or near-real-time data of transmission line conditions in lieu of conservative assumptions, in order to more accurately assess actual transmission line performance such that more of the power conveying capacity of the existing transmission infrastructure can be accessed with continued compliance with safety requirements applicable to the transmission line system.

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