Mill Leat, Cardiff Castle

The Mill Leat Project is located within Bute Park, Cardiff’s flagship Urban Park and was formally part of the Bute family’s private estate.

Client: Cardiff City Council
Location: Mill Leat, Bute Park, Cardiff
Date: November 2013
Value: £900k
Contract: NEC Option A


The historic water body situated on the outer western flank of Cardiff Castle had been dry since the 1970s and was identified as a major deliverable under the Bute Park Restoration project, jointly funded by Cardiff Council and the Heritage Lottery Fund.


Works Undertaken

  • Heritage and Restoration
  • Dam Construction
  • Reinforced Retaining Walls
  • Working with Cadw & NRW
  • Knotweed Control/Removal
  • Community Benefits Plan


In order to re-flood Mill Leat the following works were undertaken:

  • construct of an upper and lower dam to contain water and remove the risk of down-stream flooding
  •  construction of 2 no. retaining dams with a revetment to the upper dam utilising 200 tonnes of reclaimed cobble stones to match Cardiff Castle
  • construction and installation of pumping main and station to circulate and aerate the fresh water increasing local biodiversity
  • 270m of reinforced masonry clad retaining walls, ranging in height to up to 3m, and also utilising 300 tonnes of reclaimed material
  • all works were required to be “like for like” in keeping with the’ historic fabric of castle surroundings
  • a knotweed management plan was implemented and involved the encapsulation of 300m3 of Knotweed contaminated material utilising a Bontec liner


All works were undertaken in close proximity to Cardiff Castle, a Scheduled Ancient Monument and within Bute Park and  Arboretum with strict tree root protection zones.

Excavation works were undertaken under an archaeological watching brief in conjunction with Cadw and a number of artefacts, including engraved leather items, a sword sheath, Venetian glass as well as pewter spoon and clay tobacco pipe were uncovered.

During the construction phase a Community Benefits Plan was developed in order to engage with our neighbours. A number of visits to local primary schools with our H&S mascot, Sally Safesteps, were held. In conjunction with Cardiff and Vale College 4 weeks work experience was provided to a local brickwork student who has since been employed fulltime with us. We also accommodated numerous visits to site by Friends of Bute Park and held pottery, history and archaeology classes and provided guided talks on the project.

Now re-flooded, Mill Leat is self-contained, self-regulating and self-circulating. This restoration project has not only improved the character of this area of the park, it has also reduced safety issues and reduced the risk of flooding. It has also transformed a previously blighted area to create a sustainable, attractive restored historic ornamental water feature.

Councillor Ramesh Patel, Cabinet member for culture, said:
The completion of the Mill Leat marks an important milestone in the Bute Park Restoration Project and this latest feature will further enhance the park, bringing another captivating element of the city’s history back to life”.

Madeleine Havard, of the Heritage Lottery Fund, added: “It’s really important in terms of heritage and creating a habitat for wildlife while it’s also vital for the economy of Cardiff in attracting people to visit.”

Project Location