We have asked the council project manager, Claire Watts, to respond to some of the topical questions being asked about the Forge Dam situation.
Is the project working as expected?
The answer is mixed for the different outcomes the project was working towards:
To remove enough silt from the Dam to maintain an open body of water:
Although the project removed approximately 5000m3 of silt, you will have seen that during extended periods of dry weather there is a land bridge to the island. Whilst it was planned that there would be some areas of shallow water and even small areas of silt exposed during the summer to benefit wildlife, the continual flow of water through the main spillway which was an unintended consequence of the de-silting means that the overall water level in the Dam is lower than planned.
To find a way to slow down the speed at which Forge Dam silts up:
Ideally the training wall should sit just below the water line. We have observed that during high flows it is having the desired effect of keeping the Brook moving through the Dam. However it should ideally be sitting just below the water line which would protect it from exposure to the weather and hide it for the most part from view. The tree which has fallen across it will be removed soon. As in the previous answer, the problem is that in dry weather, the leaking sluice means that the pond level is lowering.
To improve the condition of footpaths around the pond:
On the whole, I think this achieved its objectives, the new path surface around the pond and new handrails up the ramp are a big improvement and we have managed to improve the drainage of some of the boggier areas of the bridleway and footpath routes out towards Quiet Lane. We will be consulting with interested groups shortly on some new access control furniture at the exit of the bridleway onto Quiet Lane. It is always a last resort to add in any restrictions to accessibility, but we will not allow any habit of parking in the former compound area to establish. Look out for further information regarding the proposals for this area shortly.
To provide new / update information for visitors about Forge Dam Park:
There are 2 new information boards on their way. One for the pond side is with the printers and will be incorporated into the existing notice board on the north bank and a new one about Festival Wood is now with the designer.
So what’s happening about the leaking sluice gate on the main spillway?
We have kept a watching brief over the past 12 months to understand the impact of the leak.
There is some benefit to water flowing through, as previously during dry weather the flow of water to the pool at the bottom of the spillway, and further on to Wire Mill Dam, dried up. This resulted in 2021 in serious fish distress in Wire Mill. There has been a lot of coverage in the national news recently about the high levels of fish distress seen in rivers and ponds as a result of June’s weather and we can expect this to be an ongoing problem as seasonal patterns change due to climate change.
However, this consideration needs to be balanced against the needs of Forge Dam to retain sufficient water during extended periods of dry weather so that the island is still an island.
The immediate options to stem the flow were tried and failed last year.
The ideal solution is to install a control mechanism so that we can control the flow of water through the spillway penstock – benefiting the downstream environment without causing detriment to Forge Dam.
The Council will commission a design solution for this as the next step and will keep you updated on progress on this.
Will the silt trap get emptied this year?
Yes, the silt trap will get emptied much more regularly and plans are underway for it to be emptied later this summer.
What are the plans for the recovery of the area where the contractor’s main compound was?
We have allowed a season of natural growth with some wildflower seeding to see how the compound area recovers. However, we are also looking at other options which can make use of the fact that this is a naturally wet area and that there is much more sunlight reaching the ground now that the clump of self-set alder trees which was previously there has been cut down and used in the construction of the training wall. Options under consideration include a “scrape” – which is a seasonal pond and would complement the hibernaculum built by the conservation volunteers earlier this year by benefiting amphibians which are scarce in the area (lots of fish in the Dam itself means it’s not a great habitat for amphibians), more wildflower planting using species which like wet conditions and / or the re-introduction of a limited number of damp loving trees to complement the wet woodland on the other side of the Brook. The Council’s Ecology Unit will provide guidance on the best approach and this will be an autumn project.
What about the smaller compound near Quiet Lane?
We will take action to make sure this area cannot be used for ad hoc car parking, however it is useful to retain an area of hard standing as we know that tasks such as emptying the silt trap and future work on the spillway will require a base area for contractors. In partnership with the Public Rights of Way Service, we will be consulting shortly on designs for an access point which works safely and easily for all bridleway users.
Questions
If you wish to know more or have any specific questions for the council regarding Forge Dam, please contact parksandcountryside@sheffield.gov.uk directly.