A684 Birklands Culvert

Replacement Culvert - Kendal
CLIENT
Cumbria County Council
LOCATION
Birklands, South Cumbria
VALUE
£327k
FORM OF CONTRACT
NEC Engineering Contract Option A

Overview

Following the extraordinary damage caused by Storm Desmond and its impact on the Birklands Culverts on the A684, EWCE was commissioned under the Cumbria Infrastructure Recovery Programme by the County Council to design and construct a solution to provide resilience for future flooding events and continued connectivity for this important section of the South Lakeland highway. Two parallel culverts crossed beneath the A684 at Birklands, and were susceptible to surcharge during heavy rainfall events and commonly flooded the public highway.

Flooding of the highway occurred on six occasions during 2016 and was becoming an increasing problem. A single flood event could cause the closure of the A684 for several days with associated issues lasting for several weeks after the rainfall. This is one of two routes into Kendal from the M6 and flooding caused long diversions.

Key Challenges

  • No mechanical excavation within 500mm of cables permitted
  • Environmental protection was paramount
  • Water Management

The watercourse drains into the River Kent catchment, designated as a Special Area of Conservation, so environmental protection was paramount.

After conducting survey work we appointed local Kendal based Consulting Engineers RG Parkins to provide hydrological and hydraulic calculations and then produce a civil engineering design. An important consideration was Cumbia County Council’s wish to reduce the future maintenance requirements of any new structure installed under the A684.

Before any ground breaking works were undertaken a CAT and Genny survey identified existing services. Vacuum excavation was undertaken to reveal services. An 11kv electrical cable was in the vicinity of the works. The cable was trial holed and clearly marked out before works commenced. No mechanical excavation within 500mm of cables was permitted. Similarly an 11kv cable crossed the line of the excavation for the new culvert. The electrical cable it was exposed during vac ex and then split ducted and protected whilst works were undertaken around it. Similarly Vodaphone, BT Virgin Media ducts, and water main were identified and protected.

The solution built replaced the two existing culverts by a new single, straight, smooth sided structure with a consistent circular shape and size, 1500 mm diameter concrete pipe and in-situ cast headwalls and aprons. The system is capable of conveying in excess of Q1000 flows.

To facilitate construction, tree clearance took place and stone walls were carefully dismantled.

Temporary works included the construction of cofferdams. A Groundforce Shorco trench support system was used to facilitate concrete culvert box section and pipe installation. Over pumping of the existing becks/drains to facilitate construction of the new culverts was undertaken. Monitoring water levels was continually undertaken. The watercourses drained into the River Kent, designated as a Special Area of Conservation, 400m from the sites, so environmental protection was paramount.

The channel bed immediately upstream of the inlet headwall was protected by filled mattresses, with banks protected by biodegradable mats and new unreinforced slopes created. A stilling basin was installed at the culvert outfall to dissipate energy and reduce the potential for scouring of the outfall headwall and channel downstream.

On the road, kerb line works, markings, highway drainage were undertaken with the stone walls reinstated.

The works required the installation and maintenance of a full road closure for 7 weeks with 4 weeks 2-way lights.

The works required the installation and maintenance of a full road closure for 7 weeks with 4 weeks 2-way lights.

Added Value

Client Feedback

“The contract was carried out with good communication between the client’s representative, public, subcontractors and the like. It started on time, completed on time, within budget constraints and to a very good standard.

Very good aesthetically to design and the land owners satisfaction”
David Lang
Project Manager, Cumbria County Council

Get in Touch

For all enquiries, please get in touch with the team here at Eric Wright.