Happy New Year and Welcome to 2021
Many people would say that 2020 has been a most terrible year and wish it had just been a bad dream. I guess that on a personal note, the members of Congleton Hydro would agree but from a Project viewpoint, 2020 has been a great year with many achievements not to be forgotten.
The share offering was a great success with the target sum of £730K being overachieved, key contracts placed and the project on track to an illuminating success (sounds better than generating!!) before Easter. The COVID restrictions and the first lockdown could have wrecked all our plans but like all good organisations we quickly adapted and found new ways of working to minimise the impact on the project. The share offering launches were supplemented by Zoom Seminars/Presentations/Q&A sessions and to be honest we achieved much more geographically widespread interest and participation than if we had held them as planned, physically in Congleton Town Hall. Project Team meetings were quickly switched to Skype (supplemented by WhatsApp, emails and phone calls as required) and worked very well—only thing missing was the regular monthly meeting over a Curry and a few beers. The civils contractor CTC has a work force bubble, which has worked very well and with a two-man team the Boardwalk contractor Redfox has made great progress. Maybe the biggest regret and possible risk was not being able to witness test the Archimedes Screw before it was shipped, however rucks of data were exchanged electronically. Our thanks to Siemens for making a “COVID secure” space for us to configure the control system. A positive impact has been OFGEM extending the FITs “start-up “timescale by one year.
We had originally planned to start work end of April but because of the COVID impact on the progress of the Congleton Relief Road construction (a planning condition to harmonise our site access with their work phases) we did not start on site until September. Credit to all involved with the Project, that despite some horrible weather conditions some of these four months start up delay, have been recovered.
Sadly, perhaps the biggest impact of the COVID restrictions is that we have not been able to host visitors on site to view progress and some of the impressive constructional achievements. To have done so would have seriously jeopardised the integrity of the Civils Bubble. Our apologies to all for this but hopefully the openness of information in the regular newsletters and our Website information has given you a good overview of the project and its progress (warts and all!!)
Last month we shared some of the frustrations caused by our Georgian Engineer forebears!! and our inability to bash at least one of the piles down to the required depth. Well, just to finish the story, when the screw channel was finally excavated the reason became clear, as shown in the photograph below—a big hunk of “Georgian Stone” just where we wanted the pile to go!!! (stone subsequently removed and pile depth completed)
The errant “Georgian Stone” foiling the Pile!!
The weather during much of December has not been kind to us with the incessant rain making the site very boggy indeed. Despite this and the consequential streams running down the hillside, Redfox has made good progress with the Boardwalk construction.
As a reminder, this is about 1.5m wide and runs for approx. 80metres from Havannah Lane, through the woods and finishes just above the Archimedes Screw. Wheelchair and Restricted Mobility access friendly, the Boardwalk will contain several Interpretation Panels that will give headline descriptions of the operation of the Screw, The Geography/Geology of the site, Rivers and Flora and Fauna. QR codes will allow suitably enabled ‘phones etc to access the Congleton Hydro website for a greater depth and breadth of relevant information.
The above-ground construction (decking, rails etc) of the Boardwalk uses C24 Timber. C24 timber is kiln-dried to reduce the moisture content and is structurally sounder and more resilient compared to the more common C16 treated timber. C24 timber also tends to be more uniform and neater in appearance. C24, also because of its greater strength, means that smaller deck boards can be used on the same centres.
The main Piles or supports for the boardwalk are made from reconstituted recycled plastic that generally is not suitable for any other form of recycling—some manufacturers call them “upcycled” posts. Inserted into approx. 0.5metre deep boreholes, they are weatherproof, resistant to decay and have an expected lifetime more than 30years. Taste and toughness mean no biting by animals, even beavers—not that we have any beavers on site! In accordance with our planning requirements, the final 80metres or so of the power cable connecting the Hydro to the consumer will be strung under the boardwalk. Dutton Contractors will do this once the boardwalk is complete. Details of the boardwalk under construction are shown in the photographs below, decking etc is only temporary until the main construction is substantially completed.
As mentioned above, the weather during large parts of December has not been conducive to unhindered and speedy progress of the main civil works. As you will be aware from previous newsletters, the River Dane is one of the highest Spate Rivers in the UK. (Spate in this instance meaning a sudden rise in water levels). Whilst our overall design accommodates this, during the construction phase, foundation holes time consumingly dugout get flooded, and then a further time-consuming process is needed to pump them dry! Notwithstanding this, and the “leftovers” from our Georgian forebears! some good progress has been made on Screw channel and foundations. In summary, this has included:
- Excavation of the screw channel from the outfall (to the river) to the base of the screw, including over 25 cubic metres of rock.
- Pouring of the concrete to form the plinths in the screw outfall as well as new concrete benching to guide the exiting water flow (as mentioned last month we have had to put a “bobsleigh run” curve into the channel so we can avoid the old “Georgian retaining wall”
- Amending the design of the screw channel waler beams (that aid the stiffening of the screw channel piles so that they hold back evenly across the entire length of the structure) to allow them to be raised by 0.5metre, thus reducing the depth of the excavation on the outside of the piles.
- Amending the design of the pile structure which will support the “hillside” above the screw channel. This allows lower specification and hence lower cost trench sheets to be used.
- Re-organising the design and layout of the Power Shed to facilitate a less expensive construction.
For those of you who like to see these civil details visually, we hope the diagrammatic view below will be of interest.
Weather and overall site conditions permitting, activities in January will focus on finishing the screw channel and construction of the water beams. Also, the excavation and shuttering of the forebay tank and hopefully pouring the forebay tank concrete (the forebay tank is the chamber that essentially connects the 1.5metre inlet pipe (this is the Weholite pipe described in a previous newsletter) to the input of the Archimedes screw via the penstock pipe. In the tank, the water is basically slowed down sufficiently for any remaining suspended particles to settle out and be prevented from entering the turbine.
During February, again weather and site conditions permitting, the Archimedes screw will be lifted in place (either by the tandem digger method or maybe by crawler crane—depends on site conditions at the time). Powerhouse can then be constructed, and the Gearbox, Generator and Variable Speed Drive/Control Cabinet installed (again weather and site condition dependent and this may well be a March activity). The last 80metres or so, of cable can then be installed and ducted into the powerhouse for termination onto the incomer breaker. One of the last core civil items to be completed is the insertion and “welding up” of the Weholite inlet pipe into its prepared channel and covering up and making good (this is one of the last activities as we want to minimise any machinery driving over the pipe channel. We are then into the commissioning phase (including the installation and connecting key peripherals such as level gauges, penstock gate motorised connections etc, but more about that next month when we get a better handle on the progress made during these dark and dismal winter months. We then need to get our heads around finalising the detail and programme for the “non-operational” but project essential peripherals such as railings, ladders, tree planting, site security and so on.
So, a long list of activities still to be started, let alone completed but we reckon we’ve broken the back of the project and can see the end in sight. In absolute months, project duration has been really what was planned but of course calendar wise we are 2-3 months from where we thought we would be.
As regular newsletter readers will know, we try to include a more detailed “topic of interest” with each issue.
This month the “Topic of Interest” is:
The Hydro site is designated as a non-statutory Grade C Site of Biological Importance (SBI), for its riparian deciduous woodland and ground flora species indicative of Ancient Woodland.
Before we could satisfy and get approval from the Statutory Authorities (Cheshire East and the Environment Agency) we commissioned several studies to determine the overall ecology of the site and what mitigation measures would need to be undertaken to meet the statutory needs and indeed our own wishes to champion the environment in which we live and its sustainability. These studies (and their subsequent revisions at the request of the authorities) are incredibly detailed and comprehensive but are perhaps too “heavyweight” to include with the newsletter. (we intend to publish them on our website, along with other studies, investigations etc as part of our “as designed and built” documentation package. In the meantime, we hope that you will find the summary information in the attached report to be of interest.
Our Civil Construction partner CTC prepared a detailed Environmental operations Plan before any site work commenced and a copy of Dane Valley Community Energy’s Environmental Policy is attached for your information.
Once the system has been commissioned, we can get to grips with the finalisation of the Site’s Woodland Plan. This will cover not only cover any suitable replacements for trees and plants but a suitable vegetation “screening” programme to help nature camouflage elements of the civil constructions. To help maintain the sites eco and woodland structure the enthusiastic support of volunteers will be needed and many thanks to those who have already registered a volunteering interest. Interest in volunteering can be registered via email@example.com. We would hope that we can be proactive in providing these volunteering opportunities once we have commissioned the system and need to get our collective arms around the overall schemes support and maintenance. But and it is a BIG BUT we live in these days of COVID restrictions and as such we just do not know when we will be able to enjoy the unrestricted site freedoms that we all wish to enjoy.
We hope you have found this newsletter to be informative and of interest and gives you a picture of how the scheme is proceeding and the obstacles that sometimes need to be overcome. We would welcome your feedback on this newsletter and any topics that you might like to see covered in future issues. Please, drop us a line at firstname.lastname@example.org
Again, Best Wishes for a Really Good 2021
Please stay Safe and Take Care