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reservoir spillway under construction

New Year’s Bridge reservoir spillway under construction

(Well, I did the hydrualic calculations that sized the weir, the spillway and the stilling basin)

[Confidential] WwTW is failing – it starts to spill to storm at 62% of FTFT. On top of this, we need to add 4 or 5 filters for a Supply and Demand project. To get the flow to he new process units, we need to fix the hydraulic problems on the main works. This requires a complex model of the seven feed pipes to twnety four filters. The model didn’t match the real water levels, and so we did a calibration exercise. This was complicated by the absense of reliable flow measurement on the site, and was limited by the need to turn off the humsu return and recirculation pumps while we did the flow survey. The calibration revealed that there is a serious air entrainment problem at the filter distribution weirs. So we are proposing that the distribution weirs be converted to Ogee weirs, which will entrain less air and can sustain more submergence than conventional weirs. We are also recommending replacement of the distributors on the twenty four filters, which have been subject to blockage and aggravate the lack of capacity at the works. Based on all of this we have maged to reduce the required flow split to the new filters from 30% to 20% of the main flow, and this drops us form 5 filters to 4 filters. And this is a big saving for our client!

TopWater Limited is embarking on new projects to design new and improved spillways for flows up to 90 m3/s on impounding reservoirs in the Pennines and in Cumbria.

TopWater Limited is currently looking at a confidential scheme to close down two small rural wastewater treatment works and transfer the flows to another local small works by two pumped mains and a length of gravity sewer.  The receiving works will be upgraded to received the new flows.  The upgrade comprises the provision of a new duty/standby Huber rotamat package screen installation, a storm weir, a hydro-brake, an air release chamber, an MCERTs magflow, a distribution chamber, two new PSTs, the conversion of an existing PST to a storm tank with a pumped return and an emergency overflow, relaying of the main outfall, a new CSO in the catchment upstream of the works, and all associated pipework and sludge systems.  Topwater’s role is to develop the hydraulic calculations, the hydraulic profile, and reports and contributions to the project scope book.  Hydraulic considerations are a key factor in establishing the layout, requiring a significant input from TopWater towards the layout of the project and to the general arrangements of the storm weir, the CSO, and the screen package.

TopWater Limited as renewed its presence on the internet with a new website –

This follows the failure of our previous web hosting provider – Weycrest – to respond to maintenance issues.

The new hosting provider is Pathway UK.

The site is still under construction, but is expected to be complete by the end of the month

TopWater Limited has won a contract to supply the services of Simon Bisset to United Utiities, via Rullion Engineering Personnel.

The contract is to provide hydraulic engineering services, primarily comprising the preparation of hydraulic profiles (ie water levels) through existing and proposed water and wastewater treatment plant.

The TopWater Limited website – – is currently down. Company email addresses are also affected.

This is believed to be a result of maintenance work at the web hosting provider,

Until further notice, please contact the company via:

Simon Bisset
TopWater Limited
46 Princes Street

Land line 01704 512470
Mobile 07931 390823


Earlier this year Simon Bisset attended a five day flood risk management course at Cranfield University. THe course covered general policy and economics as well as technical detais such as the use of FEH.

(This course is run as part of their MSc programme and is worth 10 points towards an MSc if the final assessment is taken)

TopWater is beating the recession with an extension of an existing contract with Sefton MBC. The work comprises the preparation of an integrated map of the surface water drainage system, including private and public systems, pipes, watercourses, etc using MapInfo. The current phase includes site visits to confirm details raised during the previous desk study.

As workload changes from PR09 to AMP5, TopWater is seeking new contracts for the new season. If you think we have the skills you need, let us know!