Variation to planning application 16/0438/VRC

Our latest blog provides details on our most recent update on our planning application variation which we recently submitted.

Dear Members and Supporters,

As we mentioned in previous announcements, we have now submitted a variation to our previously approved planning application.  As this is a variation, and not a new application, the supporting documentation is the same before.

Here is a link if you would like to make a comment on the re-design:
http://www2.richmond.gov.uk/PlanData2/Planning_CASENO.aspx?strCASENO=16/0438/VRC&DocTypeID=51#docs

Please note the deadline for comments is imminent – it is on Wednesday 23rd March.

We would be grateful if you could post message of support. The key areas that feel make this a good variation to the approved design are as follows:

– THH have clearly listened to the community, taken on board feedback where it’s been possible.
– the community welcomes the significantly increased flood mitigation
– we like the look of the new design
– we like its smaller overall footprint, and reduced height
– the noise conditions provide comfort that the scheme won’t be noisy
– the scheme will be operated under strict licence from the EA to prevent ecological damage, indeed we’d expect the ecology to improve with the addition of two additional fish and eel passes.

In addition to the positive reasons for supporting the variation application, we think we should try to address some misconceptions:

Some people seem to think it is a new application. It’s not. It’s a variation application to the approved scheme. If this is rejected, we still have permission to build the existing approved scheme.

There have been questions over the lack of reports.  Since this is a variation, all the previous supporting materials are still valid.

Noise report
There is no requirement for a new noise report, given that the previous noise report was based on measurements taken from the Romney scheme. Our design is now more similar to this scheme rather than less, so the previous noise report is now even more relevant.

Furthermore, the current planning sound level conditions apply to the new design and the system must still be below baseline sound levels at all receptor points assigned by the Council.

Operating the lifting system
The Environment Agency will always have the right to instruct us to fully open the channels to floods, or expected floods.

The system will be designed with a high level of redundancy. We are utilizing standard, common sluice gate opening methods and equipment. However, the system we are deploying has far more backup systems than any Environment Agency sluice gate – furthermore, because they are continuously in use, monitored and automatically tested, the gates are much more likely to be out of the way in the event of a flood. For example, during normal operations the system will continuously monitor upper and lower water levels and adjust the height and angle of the turbines for best power. This action uses the turbine lifting and angle systems in small increments, thus simultaneously verifying the system’s operational health and helping to ensure that the turbines can be lifted clear of flood waters when needed. This operational method alone results in more assurance that the bays will be clear during a flood than the EA’s sluice gates, since they sometimes sit idle for months at a time.

In addition, we will build several backup power systems, including a manual hand pump method to ensure the bays we occupy are more likely to be clear in flood events than a standard sluice gate.

During a flood the sluice gates and safety screens will drop with gravity (no external power required) into pockets in the concrete apron in the river bed. Even if a large log or boat gets past the safety boom and the safety screen, and strikes the hydraulic rams that operate the gates/screens, there will be no effect on the position of the gates/screens once dropped out of the bays and into the pockets. The turbines will be mechanically locked in the up position above the 100 year plus climate change level.

Data for modelling
Updated 2014 flood data has been used in the flood modelling we have undertaken for the planning variation.

We have designed our system to reduce flooding well beyond the 2014 flood levels and to 100 year plus climate change flood levels. When the river is in flood, the revised scheme passes 109% more water than the current capacity of that section of the weir. This improved flood risk impact of our scheme will align with the EA’s plans for weir capacity improvements.

Regards

Team at Teddington & Ham Hydro