SOUTH WEST CULVERTS

November 2017 – February 2018

BRIEF DESCRIPTION

This scheme was made up of two small projects, one in Bodmin and one in Paignton.

The Bodmin scheme was to clear the existing 900m long culvert from silt and debris, renovate any areas of structural concern and to replace defective areas of the culvert with new invert channels that are more suited to keeping flows moving through the network.

The Paignton scheme was to clear the 130m long existing stone culvert, replace the defective flap valve and ensure the scour protection was sufficient at this location.

SCOPE OF WORK

Bodmin Culvert: The existing culvert varied in size from a 600mm x 800mm egg-shaped brick sewer, to an open channel, to a 3000mm x 1000mm wide stone walled culvert with a PCC slabbed roof. The culvert had several areas of debris that were built up to a level that was restricting the flows and causing issues in the rest of the network.

MDA specialist confined space entry teams worked from the upstream location out of existing manholes to remove the silt completely which enabled us to make a full assessment of the condition of the culvert.

The culvert was repaired in multiple locations with a new invert installed across certain sections of the line.

Paignton Culvert: The existing culvert is a 1000mm x 1200mm stone overflow storm culvert. It is used to remove flows from the wet well located in the esplanade and discharge them to sea under extreme weather events.

The culvert showed many signs of deterioration and had a large build up of sand as the flap valve had not being working correctly, letting sand wash in on an incoming tide.

With the defective flap valve removed, MDA cleared the sand and debris from the culvert using man entry techniques. Approximately 200 tonnes of debris were removed by hand and taken to be recycled.

Once the invert was clear, we repaired all of the leaking joints and rendered certain sections of the culvert that were in further need of repair.

We then had to install numerous stainless steel dowels, resin fixed into the stonework masonry where the flap valve was going to be positioned. Once in place and secure, the flap valve was sealed internally and externally and this will afford protection to the culvert for many years to come.

The culvert was repaired in multiple locations with a new invert installed across certain sections of the line.

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