LOCATION

Sheffield

CLIENT

Sheffield County Council

START DATE

October 2022

CAPABILITIES

Flood Alleviation

Design

Construction

Demolition

Concrete Works

Temporary Works

Steel Works

Piling

Project Scope

Upper Don Flood Alleviation Scheme (Phase One) – Design And Construction

The project involved the design and construction of linear flood defences across 15 sites along both banks of the river Loxley from Malin bridge to the confluence of the rivers Loxley and Don. The project is designed to alleviate flooding in the Hillsborough, Malin Bridge and Owlerton areas of Sheffield.

Upper Don Flood Alleviation Scheme (Phase One) – Flood Alleviation Works

Keltbray’s main scope of works included the construction of new structural concrete retaining walls (1.5km long); Raising and strengthening of existing walls, including the installation of steel beams to counteract flood pressures; Ground raising (clay earthwork bunds, 1m x 60m); Embankment construction, including brick clad walls with copings along the whole section of defences; Utilised a bulk bag dam to enable works on retaining walls; Construction of bridge parapets along the Penistone Road Bridge; Installation of sheet pile walls rather than demolition of pre-existing buildings; Vibration free piling used throughout installation of the sheet piles; Demolition of existing balconies, and installation of new balconies with demountable flood defences; Installation of demountable flood barriers on Rudyard Mews, approximately 40m in length total; And removal of an existing weir to assist with works.

Upper Don Flood Alleviation Scheme (Phase One) – Ecology

Working with River Stewardship Company, Natural England, and the Environment Agency, we phased the project to minimise disruption to aquatic life, ensuring all necessary permits were in place. Environmental efforts included protecting fish, crayfish, and nesting birds, relocating bats, and addressing an unidentified badger sett under Regent Court car park. Consulting BWB, we amended the design of the culvert installing a concrete slab, headwall, and pipe for safe badger access. Additionally, we managed invasive plants like Japanese Knotweed and Himalayan Balsam via spraying and injection methods.

Key Challenges and SolutionsKey Challenges and Solutions

Third party assets

Challenge: Managing third party owned land and businesses surrounding the project Solution: Amended original flood defence plans which involved demolishing industrial buildings, avoiding costly and disruptive practice. Avoided this by installing sheet pile walls and using a Giken silent piler significantly reducing noise and vibration, crucial in the environmentally sensitive area, further mitigating impacts.

Ecology on site

Challenge: Managing a wide scope of ecological constraints and adapting to unexpected badger sett. Solution: Developed plans in line with our Environmental Management Plan (EMP) to implemented measures to manage ecology safely, mitigate loss of biodiversity.

Working in water

Challenge: Working in and around water resulting in the need to dam the river temporarily to facilitate construction. Further challenges posed from traversing sedimentary materials. Solution: Careful planning and actioned the amendment of damming methods and subcontractor methods to accommodate the limited working room and constraints caused by damming off the river.