Calderdale Catchment Plan and its development. The latest workshop held on Saturday 2nd July

We’d like to keep you up to date with the Calderdale Catchment Plan and its development. The latest workshop held on Saturday 2nd July in Halifax focusing on Governance arrangements. Please find attached the notes written up from the work on the day that will directly inform how the Catchment Plan process is run and provide an agenda for the first meetings of the different Catchment Plan working strands. They are Resilience taking place on the 9th July at Hebden Bridge town hall, Natural Flood Management, Strengthening defences, Using existing infrastructure taking place on the 16th July at Hebden Bridge Town hall and maintenance taking place on the 23rd July at Hebden Bridge Town Hall..  

Following the initial work strand meetings, these working groups will continue to invite people to get involved. If you are interested in getting involved please email avril.south@environment-agency.gov.uk to register. 

We look forward to working with you:

Notes from governance group

Governance group decisions

CCP revised principles

On Saturday 16 July, another workshop is planned to focus on traditional flood defences

Following the first catchment plan workshop on the 18 June and a second group exercise on the 2 July which defined the governance arrangements for the Calderdale Catchment Partnership, a further series of workshops have now been organised to identify issues and related actions that will be included in the initial catchment plan.

The workshop held on the 9 July focussed on household, business and community resilience and a follow on meeting took place on the evening of the 11 July. The next meeting on resilience will take place on the 21 July.

On Saturday 16 July, another workshop is planned to focus on traditional flood defences, natural flood management, dredging and channel clearance, land drainage and use of heritage assets / historical infrastructure, urban drainage and use of reservoirs and canals.
The maintenance of assets will be discussed at a workshop on the 23 July and will cover discussions on Stewardship, Highways maintenance and volunteering involvement in maintenance.

The timescales for the production of the first draft of the catchment plan are short but since the plan is effective for 25 years there will be many opportunities in the future to contribute to it.
Shortly after each workshop the output is placed on www.eyeoncalderdale.gov.uk and www.slowtheflo.or.uk web sites so please take a look. There are also updates on the Environment Agency Facebook page – www.facebook.com/environmentagency, the UCVSG Facebook group and you can follow us on Twitter @EnvAgencyYNE #calderplan.

We will disseminate information through our own and our partner’s networks in an attempt to reach as many people in the community as possible and ask for your support and contribution at these groups.

If you are interested in being involved in the creation of the catchment plan please email avril.south@environment-agency.gov.uk to arrange your invitation.
In order to ensure efficient running of these groups, the Environment Agency will provide technical expertise, relevant data, organise facilitation (where needed), note taking, room hire and overall coordination across all the work strands and planning.

Draft actions

PowerPoint

Helping ourselves, how a miniature flood alleviation scheme helps protect a local community

You may well think to yourself, “What can I do to help”, and “The Government should sort this out”.

The answer to questions or statements like this is “a little contribution can amount to a lot if everybody did it” and of course the government has to prioritise.  Larger Metropolitan areas will get priority over rural communities as that makes economic sense as there is a limited pot of money for managing nationwide flood risk.

So what can you do that is cheap and easy?

The first thing you can do is disconnect your downspouts from your drains and allow them to discharge onto your garden or yard.  Better still, you can create an attenuation pond for the water that runs off your roof using a water butt, at each of your downspouts.  Leave the tap open, the water fills the butt and it drains out slowly from the tap onto the ground perhaps into a flower bed and not into a drain.

In this small way you have slowed the flow to the river by following ether of these two simple steps.  If you are paving your garden use a permeable membrane below it rather than using plastic, or leave several paving stones out and fill with plants or gravel.  Better still leave gaps between the paving stones and gaps in the mortar between them.

All of these measures increase the infiltration of water to the ground and prevent flow to the drains which eventually discharge your water to the rivers.

If you have got some land, even a small plot or garden take a look at your land when it is raining heavily how is it draining?  Where does all that water go?  If it is running quickly off your land downhill then it is going to give your downhill neighbours a problem possibly.

With this in mind here is an example of what can be done at small expense.

I own a smallholding above Pecket Well.  The land backs onto Wadsworth Moor and falls from here downslope to a bridleway also used to access smallholdings further along this same lane.  A field drain crosses my land which feeds into along with other field drains, a small brook which continues downhill to Far Shawcroft Hill, from here the brook crosses below Ackroyd Lane and then into Keighley Road (A6033) to join Hebden Water in Midgehole.

The field drain has been problematic for many years leaking water onto the lower field which is boggy with rushes growing.  An attempt ten years ago to fix the problem which cost a considerable sum appeared to have no effect.  The drain was excavated and reconstructed but with no improvement.  On Boxing Day 2015 the water rushed out of the ground onto the fields and then onto the bridleway causing damage to the bridleway surfacing.  Similar, less severe rainfall events than Boxing Day having similar effects.

In the 2012 summer floods a property at Far Shawcroft Hill narrowly escaped flooding from the adjacent brook only by intervention by the property owner who was home at the time.

Following the Boxing Day flooding I decided to investigate an idea I had regarding slowing the flow in brooks or ditches using letterbox slot plate weirs (see pictures) and I began installing a few experimental ones here on this very same brook.

I wrote about this in January 2016 in my “Pound for pound” article:

There are eight of them installed here now and they are working well attenuating water in small ponds within the brook channel during heavy flows (See Pictures).   I then turned my attention to the field drain and I employed my neighbouring farmer to do some initial digging to see if we could locate the problem.

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I was expecting to find the pipe I had replaced some ten years earlier with a 150 mm diameter pipe to be broken or blocked at the point from where the water was issuing.  In fact I discovered the pipe to be intact and running freely. However, further excavations revealed an old square stone drain running obliquely into the new drains which ten years previously I was not aware of.  This meant that the new 150 mm diameter pipe had combined flows at this point from another roughly 200 mm square stone drain.  Clearly in heavy flows there was insufficient capacity and this was the reason the water was breaking to surface flooding the lower field.

The obvious solution was to replace the 150 mm diameter pipe with a larger pipe of say 300 mm diameter, but over a distance of 75 metres that was going to prove expensive, bearing in mind this pipe was only ten years old and in good condition.

The solution was to employ my neighbour a while longer and excavate and construct an attenuation pond on the drain.  I calculated the size of the pond needed to be 200 m3, a pond roughly 14 x 14 x 1.0 metre deep would provide that volume and this would provide a 1 in 30 year return period level of protection.

The pond is now dug and grass re-sown (See pictures).  In normal circumstances it is a dry pond that can be used for grazing. It only begins to fill during heavy downpours when the 150 mm diameter pipe cannot take the combined flows.  Upon cessation of the storm the pond gradually empties.

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There are five positive outcomes from these small interventions, in order of importance these are:

  • Reduced flood risk for the wider community by slowing the flow to the valley floor
  • Reduced flood risk for the nearer community at Far Shawcroft Hill
  • Reduced risk of flood damage to the bridleway
  • A dryer lower field that can be returned to productive grazing
  • A cost saving over replacing the 150 mm diameter pipe with a larger pipe

All at a cost of under £500 for the pond and the eight plate weirs, such a process applied across the catchment makes good economic sense for slowing the flow into the Calder.

All we are doing is skimming the top off the flood peak. If enough of us can do what I have done here then we might just make a difference!!

Stuart Bradshaw C.Eng.

 

Flooding report released 08/06/2016 criticises government’s ‘reactive rather than proactive’ approach to flood prevention

“Despite sustainable urban drainage systems being widely acknowledged to be an efficient way of dealing with surface water, successive governments have been reluctant to mandate them as the default option in new developments. 

We are disappointed that the Government has kicked this into the long grass by commissioning another review. This is an issue that now requires action.”

(Flooding: Cooperation across Government. House of Commons Environmental Audit Committee June 2016)

We are pleased that the report published yesterday by the Environmental Audit Committee recognises the importance of SuDS and Natural Flood Management (NFM), and questions the need for further review.

The benefits of SuDS and NFM are well-established. Further review is simply procrastination – we should be getting on with Slowing the Flow by legislating effectively and promptly.

Hugh Ellis from the TCPA puts it well when he says:

“Do your customers want to pay money to pay your insurance bills, or do they want to pay money for a better built environment?”

However, we disagree with his view that “…the difficulty with the new process was the economics, because the benefits of sustainable urban drainage are long term to end users but the costs, of course, fall on developers.”

Many studies have shown that properly-integrated SuDS need not cost more than conventional drainage. For new developments, the cost of implementing SuDS can actually be significantly lower than the cost of traditional drainage systems. In one development we were involved in, we were able to show that by replacing the traditional drainage scheme with our SuDS design, the cost of the drainage for the project would have decreased by almost 1/3! (And they would have saved ongoing maintenance costs, of course, because landscapes need maintenance anyway, and they would have had no conventional drainage system to maintain…)

The report acknowledges the successful NFM scheme of our friends in Pickering:

“The Government should make sure that funds are available to fund more pilots to continue to make the case for this approach and to protect those places like Pickering which might benefit from a cheaper natural flood management project.”

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Leaky Dam at Pickering

vels that has begun to be shown for NFM in places like Pickering, Cumbria, and recently to the newly-formed Calder Catchment Flood Studies Group.

The development of a Calderdale Catchment Plan (which we are contributing to) is to be welcomed. As Dieter Helm is quoted in the report:

“Flooding is about what happens to catchment systems. It is not about individual houses and it is not about individual flood defences, although they all have roles to play. To work out how much you should spend and how you should spend it on flood defence, you need to start with a proper catchment view.”

By Amanda McDermott CMLI