Seething Lane Garden, alongside the iconic 10 Trinity Square building, embraced DeepRoot Silva Cells for soil volume and water drainage benefits
Situated just west of 10 Trinity Square — a century-old building adjacent to the Tower of London and the River Thames — Seething Lane Garden is a «pocket park» with a rich history dating back to the 1600s and the writer Samuel Pepys. In 2017, after years of project planning and construction, it reopened to the public with a series of impressive upgrades: a large open lawn, commemorative Pepys monument, and 18 new trees. The DeepRoot Silva Cells were installed under the new plaza walkways to help provide enough soil volume to guarantee healthy tree growth, while also assisting in managing on-location rainwater.
Number of Silva Cells: 216 (4x)
Total Amount of Soil Volume: 1,300 m3
Number of Trees: 14
Type of Project: Plaza, Residential, Government, Pocket Park
Project Designer: Capita Symonds
Project Contractor: Frosts Landscape Construction Limited
Installation Date of Silva Cells: 2017
Officially introduced by Prime Minister David Lloyd George in 1922, 10 Trinity Square served as the home of the Port of London Authority for many decades. Located in the southeastern corner of the City of London, the Beaux Arts-style structure became a Grade II “listed building” in 2012, the same year it began its redevelopment as the Four Seasons Hotel London at Ten Trinity Square — a 100-room hotel that opened its doors in 2017.
Adjacent to the historic building, Seething Lane Garden — a publicly owned park — also underwent an upgrade project at the same time. Famous for its association with Samuel Pepys, the garden is situated just outside the Navy Board where the 17th century diarist worked (and indeed, where he likely composed much of his work, including his memorable recollections on the Great Fire of London in 1666).
The City of London Corporation’s Open Spaces Department partnered with Capita Symonds for the garden improvement initiative, prioritizing pedestrian traffic and welcoming green spaces. The new design included paved walkways between planters, a large open lawn area, bench seating, and a bust statue of Pepys.
Also incorporated into the design were 18 new plaza trees. To assist in providing proper soil volume under the garden’s new paved walkways, project planners utilized the DeepRoot Silva Cell system.
One of the primary goals of the garden’s redevelopment plan was to ensure the new trees would grow to healthy maturity. By installing the Silva Cell system, adequate soil volume standards for robust growth would be guaranteed, as the cells support the suspended pavement paths above while allowing nutrient-rich, uncompacted soil to be incorporated within its void space. Indeed, the layout of the plaza allowed the Silva Cells under the hardscapes to connect the areas beneath the softscapes to one another, creating a large, united soil environment for active root expansion. The Silva Cell system also buttresses the small walls around the planter areas, providing even more space for loamy soil.
A unique challenge of this project was the garden’s foundation: an underground car park was built beneath Seething Lane Garden. This meant that the garden itself would have to be constructed from the bottom up, as opposed to the top down. To reach walking level, project planners chose a 4x Silva Cell configuration — a more affordable option than laying down space-filling foam as the garden’s foundation. The DeepRoot technical team assisted project designers throughout the process. Technical director Pat Greeley was on location for the Silva Cell installation, ensuring the process went smoothly.
The Silva Cells also provide a destination for area rainwater. Water from the roof of the 10 Trinity Square building is collected and filtered down beneath the garden where it enters the soil in the Silva Cells and irrigates the garden trees.
The newly improved Seething Lane Garden is already a local favorite, a small green oasis in the middle of the city. Graeme Smith, Chairman of the City of London Corporation’s Open Spaces and City Gardens Committee, raved about the project and its benefits: “Seething Lane Garden is a good example of our work protecting and conserving historic green spaces in the city. The addition of new trees and shrubs will improve the biodiversity of the area [and it] will become an important habitat for wildlife within the urban landscape.”