Geotechnical Desk Study - Islington Council

Geotechnical Desk Study
level), is situated at the top of the cutting slope, adjacent to the surfaced car park area in front of
the Community Centre building
East Side Boundary Retaining Wall - Predominately of mass brickwork construction, but
punctuated with sections of insitu concrete walls, The wall is of a constant height of approx 2.2
metres above the adjacent car park surface, originally constructed vertically, with brickwork
buttress walls, retaining the rear garden material of the properties fronting Battledean Road
Olden Garden Retaining Wall – A low level, brickwork retaining wall, providing a recess area at
the foot of the D/S cutting slope for the erection of a community greenhouse
Community Centre End Wall – Forming part of the ‘original’ building construction, and providing
support to the gable end of the main roof structure. The wall appears to be 225mm thick at roof
level increasing to a thickness of 330mm at the base, with an arched window at ground floor level
and 3 No. further window openings at first floor level.
Representative views of the site, along with the retaining wall structures are given by photos in
Appendix C.
7.4 Summary of Site Condition Survey
The site Condition Survey was undertaken by Atkins on 20.02.09, using a ladder, where
necessary, noting the visual defects within the retaining walls. A series of plumb readings were
taken to determine the approx verticality of the walls at varies locations.
The weather conditions were ‘dry’ at time of inspection.
No archive drawings or historic information is available, showing hidden construction details and
understanding of such details will therefore be relied on the undertaking of trial pit/core survey
work.
The Condition Survey concluded that all 3 No. retaining wall structures including the Community
Centre end wall, are in a poor condition, with the following items noted:
West Side Retaining Wall
i) Significantly forward leaning/rotation of the wall out of vertical ‘plumb’ profile, along the total
length – refer to site sketches in Appendix F for verticality readings.
ii)
iii)
iv)
Mature ‘unchecked’ buddleia growth through mortar joints within brickwork, causing
significant damage and displacement
Additional mesh fencing installed along the top of the wall, increasing the lateral instability of
the wall
Deep open mortar joints, particularly, to the low level (trackside) face of the wall
East Side Boundary Wall
v) Vertical fractures, typically, close or adjacent to the buttress walls
vi)
Significant forward leaning (top over base), along the length of the wall
vii) Upper section of the wall sliding over the base (at DPC level) in the ‘newer’ section of the wall
(towards Ronalds Road end)
viii) Section of the wall has been reconstructed on the ‘original’ wall footings
ix)
Evidence of blocked weepholes at the base of the wall
Olden Garden Retaining Wall
x) Vertical fracture (full height) at the centre of the wall with forward displacement, either side,
towards the track
xi)
Vertical fractures within the mitre corners between main wall elevation and side walls
Community Centre End Wall
5044006/002 Geotechnical Desk Study (2).doc 16