PAST PROJECTS

Bournemouth Beach Timber Groyne Replacement winter 2015/16

Part of a 17-year Beach Management Scheme to protect Bournemouth’s coastline

LEAD AUTHORITY

Bournemouth Borough Council

WORKING WITH

START DATE

October 2015

END DATE

June 2016

The first phase of the Bournemouth Beach Management Scheme 2015-2032 has been delivered.

Project Overview

  • 10 groynes replaced: Nos. C27 to C36, ranging from the east of Boscombe Pier by Honeycomb Chine to Fisherman’s Walk, near the zigzag path
  • Project cost: £3.6m
  • Funded by: Environment Agency

Project Description

These new groynes are the third (C) series of groynes to be constructed on Bournemouth beach. The programme of work was restricted by tides as the outer ends of the groynes could only be worked on during low spring tides. The 10m length piles for all 10 groynes were driven into position using a combination of auger drilled pilot holes and an excavator mounted vibratory pile driver. Planks fastened to the side of the piles are sometimes up to 17 rows (5m) deep or until the clay substrate is reached. With each plank being 300mm wide, considerable excavation around each groyne area was required to enable the planking work to take place.

Different timber species have been used to construct the C-series groynes, in varying quantities and applications, in order to test and monitor their durability. Some use Greenheart piles with Greenheart planking, others have a combination of Greenheart piles with Ekki planking and Ekki piles and planking. One groyne is constructed entirely from Basralocus piles and planking.

Five of the eight existing B-series groynes in the area were removed as part of this scheme. The planks and piles of these were salvaged, carefully labelled and retained for inspection with a view to investigating the condition of the timber after 29-31 years of service.

Assessing the performance of timber groynes at Bournemouth Beach, 2015-2017

A 29 year field-test of 5 different species

As part of the groyne renewal programme at Bournemouth beach, a study was made into the performance of five ‘experimental’ groynes that had been built between 1985-1987 in order to evaluate the performance of different timber types in the field. Results will inform future groyne engineering decisions regarding choice of material for Risk Management Authorities here and elsewhere in the region.

Full details and associated reports available at www.southerncoastalgroup.org.uk/scopac-research/timber-groynes-bournemouth-beach/