The Friends of Lyttelton Committee is delighted to announce that a generous grant from the Hampstead Garden Suburb Trust has been awarded to fund the installation of a swale, bridge and rain garden in the Henrietta Barnett Orchard Garden. Swales are a sustainable drainage solution consisting of a shallow, broad and vegetated channels designed to store and/or convey runoff and remove pollutants. They may be used as conveyance structures to pass the runoff to the next stage of the treatment train and can be designed to promote infiltration where soil and groundwater conditions allow.

Since the original installation of the orchard a couple of years ago, and its further development into an orchard garden with the help of over 100 volunteers the space has become a haven for wildlife and park users alike, with many visitors passing through each day and a significant amount of positive feedback. A baseline biodiversity survey was conducted in the summer of 2024, and will be repeated annually to chart improvements.

As with much of the Suburb, drainage has been an issue with a large patch of the Orchard garden, and beyond becoming flooded for months at a time during winter, with further significant flooding regularly occurring downhill closer to the Nursery.

In consultation with Barnet Council, ecologists and landscape gardeners it has been agreed that the best solution would be the installation of a Swale, draining into a rain garden planted for bog conditions just outside the current boundary of the orchard. This will help drain the orchard, hold water that would otherwise flood downstream to the Nursery, add significant interest for visitors and create new habitats for biodiversity. The full details are below.

Furthermore, the Friends Committee sees this as a pilot project on how to improve drainage elsewhere in the park and beyond using sustainable methods. Significant flooding has been reported by the residents of Norrice Lea, backing onto Lyttelton, especially towards Linden Lea. Whilst drainage is an issue across the wider suburb, it is believed that there may exist an underground water course here, compounded by the installation of astro turf in the gardens of some neighbouring gardens, reducing the water holding capacity and forcing more water downstream into the park and neighbouring gardens.

The mission of the Friends Group is to improve the park for park users and wildlife. Whilst the flooding in this region does not cause significant issues for park users at the moment, and indeed the temporary ponds created present interesting habitats, should the circuit path proposal be approved by Barnet Council, accessibility to this section of the park would be increased, and the Friends Group would see improving the drainage in this region as a top priority and commits to seeking both approval and funding for a wider drainage project.

To confirm the installation of the Swale and rain garden will have no detrimental impact on the upstream drainage, and should offer some improvement by giving the surface water somewhere to drain into.

*Rough drawing of location for Swale and Rain Garden*

Details on the Orchard Drainage Swale

Following discussions with ecologists, gardeners and Barnet Council we propose to install a mini “Swale” (drainage ditch) to drain water from the orchard and a rain garden just outside the current boundary of the orchard to be planted with bog loving plants. The excavated soil will be mounded to create both a berm beside the swale and a planting mound, which can showcase drought resistant plants.

We estimate that 40 tons of soil will be dug out and moved, and thus the Swale and rain garden will have a holding capacity of 40 tons of rainwater. Not only will this help to significantly dry the Orchard area, but it will also hold water that would otherwise flood down the gradient towards the other flooded area outside the nursery, and thus also help to dry out that area.

The swale and rain garden will create new areas of interest for visitors, with a sleeper bridge for a path over the swale; create a huge variety of new habitats for wildlife, massively increasing biodiversity and also act as a case study for local residents on how to manage rainwater in a sustainable way, and how to plant for the changing climate.

Permission has been granted for this work by Barnet Council, and they are very supportive of its development.

Draining Lyttelton - Swale funded for HB Orchard Garden

Kids Gardening Club