Silva Cell “Leeds” the way in Sovereign Square: Case Study

Sovereign Square is the first significant redevelopment in Leeds City Centre in a generation. Seven years ago, the City of Leeds, a financial and legal hub in the UK, initiated the transformation of an industrial site to a green, urban oasis. Between Sovereign Place and Sovereign Street, the aptly named Sovereign Square has become what the Leeds City Council and project designers re-form Landscape Architecture envisioned in 2013 when our Silva Cell product was initially proposed as a part of the plan: a redevelopment that fosters a community by encouraging local workers to gather, eat, enjoy, and have access to an outside area to reflect and rest.

Leeds City Council initiated a masterplan for the South Bank borough to regenerate the historic area, providing space for the rapidly growing digital and financial hub. The project presented an opportunity to bring nature into a city centre. Uniquely located alongside the historic Leeds train station and two major road arteries, the project site is a green vision surrounded by the River Aire. The green infrastructure movement epicenter of Leeds would begin in this square.

Aerial image of Soverign Square c. 2019. Photo courtesy of Google Earth

The project was constructed in two phases from 2014-2017.  Both phases specified and used Silva Cell to create soil volume and stormwater management for growing trees as part of the landscape redevelopment. Just adjacent to the existing Sovereign Square Park, construction began in 2014.

Trees and Landscape

150 Silva Cells totaling 140m3 of soil volume were installed in 2014 to support the Honey Locust Trees. Re-form incorporated a grove of trees surrounded by raised lawns, tree-lined pedestrian boulevards, a water rill, fountains, and other outdoor amenities. These features were designed to encourage locals and visitors of Sovereign Square to linger and enjoy the stylish space and shade from the trees. Under the paving, Silva Cells provide the necessary soil volume to grow large, mature Honey Locust within the hard York stone-paved surfaces.

Water

Water is an integral part of the site’s heritage and this project. In the 18th century, a water channel went through the site from the River Aire, powering mills, which in turn powered Leeds. For the revedevlopment water was an integral part of the design and aesthetics. The water features include fountains and bubbles of water emerging from cracks and flowing down the rill. This has created a place that is exciting for children but also a mesmerizing back-drop for others. Stormwater is channeled through drains and resused to irrigate the trees directly. The Silva Cells were able to be incorporated without sacrificing the intended water designs. and provide storage and water quality improvements for runoff from adjacent hardscapes within the park.

10 Honey Locust planted with Silva Cell in Sovereign Square. Photo taken May 2017

Phase 1: 10 Honey Locust and water rill managing runoff. Photo taken August 2017.

In 2016, the second phase began. Re-form, Leeds City Council, and DeepRoot came together again to incorporating five additional Hornbeams to the square adjacent to phase 1. Beneath the Hornbeams, 102 Silva Cells were installed below grade to give ample soil volume (16.2m3 per tree) and support to the new trees and existing water infrastructure. The trees sit in front of the high-end office and retail building with a sitting area beneath the trees. As employees and coffee shop patrons enter or exit for the day the trees are the first and last thing they see. See the growth of the Hornbeams and the area from 2016 to 2019 in the photos below.

5 fastigiate Hornbeams ‘frans fontalne’ in front of 2 Sovereign Square, Installed 2016. Photo taken May 2016.

5 Hornbeams from Phase 2 providing shade for passersby in front of Caffe Nero. Photo taken August 2019. Courtesy of Google Streetview

In 2017 phase 1 and phase 2 were complete with a combined soil volume total of  220 m3. The lasting effects of the multi-phased project are demonstrated through photos of the square filled with people enjoying the green square. Photos below courtesy of re-form Design

DeepRoot Project Manager Steve Chatwin-Grindey has visited Sovereign Square over the years. “The last few times I’ve visited, the square is full of people. The effect the trees and green infrastructure have had on bringing people to the square is beautiful to see.”

Simon Vine of Landezine speaks on the effects of Sovereign Square in 2017, stating, “Sovereign Square is making a positive contribution to the quality of public life in Leeds City Centre. People are choosing to spend time here and numbers will undoubtedly increase when the remaining development plots are complete. The water and its juxtaposition with dynamic plantings animate the space and engage people in lots of different ways.”

The Leeds City Council masterplan has seen its first efforts with Sovereign Square yield positive results. Now there is a third phase development on the way.

“Sovereign Square will become a gateway into a future City Park that will help transform Leeds into a healthier more attractive and ecologically diverse place.” Landezine Magazine (2017)

DeepRoot is thrilled to have been part of the Sovereign Square reconstruction for the last seven years. We look forward to the progress and maturation of the trees and the squares over the next decade!

Installation Summary:
Number of Silva Cells: Phase 1-150 1X SC1, Phase 2-201 SC2
Amount of Soil volume per tree: Phase 1: 12.7m3 Phase 2: 16.2 m3,
Number of trees and type: Phase 1: 5 Honey Locust , Phase 2: 10 fastigiate Hornbeams
Application and Project Type: City Square, Plaza, Government
Project Designer: re-form
Project Contractor: Eurovia UK and Grace Landscapes
Project timeline: 2012-2017