St Mary Redcliffe Project 450 RIBA 2 Stage End Report

4.1 STRUCTURES
Undertaken by Integral Engineering, the Structural Report documents the following civil and
structural information identified, recorded, and developed during RIBA Stage 2:
1. Ground Conditions & Site Investigation
2. Drainage
3. Site Constraints
4. Substructure
5. Superstructure
6. Design Criteria
Additionally, the report has identified and informed the structural risks and potential mitigations
that are embedded within the Project Risk Register in Section 7.0
2. Ground Conditions & Site Investigation
2. Ground Conditions & Site Investigation
The BGS geology maps show the site to be in the area of an outcrop of Redcliffe
Sandstone possibly overlain by River Terrace Deposits to the north of the site.
2. Ground 1. Ground Conditions Conditions & Site & Investigation
The BGS geology maps show the site Site to Investigation
be in the area of an outcrop of Redcliffe
Sandstone possibly overlain by River Terrace Deposits to the north of the site.
The BGS geology maps show the site to be in the area of an outcrop of Redcliffe
The BGS geology maps show the site to be in the area of an outcrop of Redcliffe Sandstone
Sandstone possibly overlain by River Terrace Deposits to the north of the site.
possibly overlain by River Terrace Deposits to the north of the site
Three historic boreholes have been identified in close proximity to the site with the closest being south of the site
to the rear of Colston Parade. The borehole was drilled to a depth of 10m in 1970 and encountered approximately
1.0m made ground over 1.2m very stiff red silty clay over red and grey sandstone
If a lightweight construction is adopted a shallow spread foundation is likely to be suitable apart from in the
location of the events space in the south courtyard which is likely to require a mini piled or screw piled foundation
due to the presence of existing tree roots
Figure 4. St Mary Redcliffe geology
An intrusive site investigation (SI) will be required to inform the design of the proposed
foundations which will need to encompass the following;
Figure 2. BGS Superficial Deposits
Figure 2. BGS Superficial Deposits
Figure 3. BGS Bedrock
Figure 3. BGS Bedrock
Figure 2. BGS Superficial Deposits
Figure 3. BGS Bedrock
Figure 4. North churchyard foundations
Figure 4. St Mary Redcliffe geology
Figure 4. St Mary Redcliffe geology
Three historic boreholes have been identified in close proximity to the site with the
breath
closest being south of the site to the rear of Colston Parade. The borehole was drilled
Three historic boreholes have been identified in close proximity to the site with the
to a depth of 10m in 1970 and encountered approximately 1.0m made ground over
closest being south of the site to the rear of Colston Parade. The borehole was drilled
1.2m very stiff red silty clay over red and grey sandstone.
to a depth of 10m in 1970 and encountered approximately 1.0m made ground over
If
1.2m
a lightweight
very stiff red
construction
silty clay
is
over
adopted
red and
a shallow
grey sandstone.
spread foundation is likely to be
suitable apart from in the location of the events space in the south courtyard which is
If a lightweight construction is adopted a shallow spread foundation is likely to be
likely to require a mini piled or screw piled foundation due to the presence of existing
suitable apart from in the location of the events space in the south courtyard which is
tree roots.
likely to require a mini piled or screw piled foundation due to the presence of existing
tree roots.
Made ground & burial ground
Choir Vestry
Made ground & burial ground
Screw piles between tree
Events space
roots, building
Screw piles between tree
Events space
suspended to allow trees to
Sandstone roots, building
Figure 5. South churchyard breath foundations
suspended to allow trees to
breath
BGS Superficial Deposits
BGS Bedrock
Three historic boreholes have been identified in close proximity to the site with the
closest being south of the site to the rear of Colston Parade. The borehole was drilled
to a depth of 10m in 1970 and encountered approximately 1.0m made ground over
1.2m very stiff red silty clay over Events red Space and grey sandstone.
If a lightweight construction is adopted a shallow spread foundation is likely to be
suitable apart from in the location of the events space in the south courtyard which is
likely to require a mini piled or screw piled foundation due to the presence of existing
tree roots.
Made ground & burial ground
Sandstone
Events space
TunnelScrew piles between tree
roots, building
suspended to allow trees to
- 2 cable percussion boreholes with gas/water standpipes installed 1 x 10-15m
borehole on the north lawn in the location of the proposed building and 1 x 15-
20m in the paved area to the south of the church in area of the proposed
education space.
- 6-8 windowless sampler holes (small boreholes) – 3 in north area for the
Screw proposed piles main located building between and basement tree roots area, 1 with under the proposed building
building immediately suspended south of the above church, ground 2 under plane the proposed event space/café
building, 3 - 4 of these with gas/water standpipes. (windowless sampler holes
Made ground and archaeologically sensitive
are small diameter boreholes drilled with a much smaller rig.)
-
ground
3-4 hand
adjacent
dug pits.
to
On
church
north side where building/basement adjoins church, and
An intrusive site investigation
rear of the retaining
(SI)
wall
will
to
be
the
required
south of the
to
church
inform
to allow
the design
the existing
of the prop
foundations which foundations will need to to be encompass viewed. the following;
An intrusive site
-
investigation
Soakaway testing
(SI)
(see
will
section
be required
3.4.)
to inform the design of the prop
foundations which - 2 machine will need dug to trial encompass pits –one on the northern following; lawn area (for near surface
- 2 cable percussion boreholes with gas/water standpipes installed 1 x 10-
foundation/ground conditions) and one on the grass behind the retaining wall
borehole south on the of the north church lawn (to expose in South the the location Churchyard rear of the of retaining the Foundations proposed wall and backfill) building and 1
- 2 cable percussion boreholes with gas/water standpipes installed 1 x 10
20m -in the Standard paved geotechnical area to the lab testing south including of the church testing for in a area piled solution, of the proposed
education
borehole contamination on
space.
the north testing lawn as appropriate in the location and targeted of the contamination proposed building testing in the and 1
20m in the area paved of the old area fuel tanks to the plus south some of Waste the Acceptance church in Criteria area of testing the for proposed
- 6-8 windowless
education
spoil
space.
disposal
sampler
characterisation
holes (small boreholes) – 3 in north area for the
proposed - gas/water main building monitoring and in standpipes, basement including area, monitoring 1 under for the volatile proposed vapours buildi –
- 6-8 windowless sampler holes (small boreholes) – 3 in north area for the
immediately minimum south of 4 of visits the church, 2 under the proposed event space/café
building,
proposed
3
main
- 4 of
building
these with
and
gas/water
basement
standpipes.
area, 1 under
(windowless
the proposed
sampler
buildi
h
immediately The site is archaeologically south of the sensitive church, so all 2 SI under works the will need
are small diameter boreholes drilled with a much
proposed to be accompanied
smaller
event
rig.)
space/café by a
written scheme of investigation and an archaeological watching brief. We would also
building, 3 - 4 of these with gas/water standpipes. (windowless sampler
- 3-4 recommend hand dug that pits. a ground On penetrating north side radar where survey building/basement (GPR) be carried out prior adjoins to church
are small diameter boreholes drilled with a much smaller rig.)
rear
commencement
of the retaining
of the intrusive
wall to
SI
the
to confirm
south
the
of
presence
the church
of underground
to allow the existing
- 3-4 obstructions. hand dug Once pits. the On results north of the side GPR where survey are building/basement available the final exploration adjoins churc
foundations to be viewed.
rear
locations
of the
can
retaining
be agreed with
wall
all
to
parties.
the south of the church to allow the existing
- Soakaway testing (see section 3.4.)
foundations to be viewed.
- 2 The machine above Made has dug been ground trial reviewed pits and –one archaeologically by a geotechnical on the northern sensitive engineer lawn who has area provided (for near a budget surface
Soakaway cost of £16,000-£20,000. testing adjacent (see Whilst to section church this is useful 3.4.) for costing purposes, we would obviously
foundation/ground conditions) and one on the grass behind the retaining
- 2 recommend machine that dug a trial specification pits –one be sent on to the a minimum northern of three lawn companies area (for to near provide surface a
south competitive of the tender. church (to expose the rear of the retaining wall and backfill)
foundation/ground conditions) and one on the grass behind the retaining
- Standard geotechnical lab testing including testing for a piled solution,
south of the church (to expose the rear of the retaining wall and backfill)
contamination testing as appropriate and targeted contamination testing
- Standard geotechnical lab testing North Churchyard including testing Foundations for a piled solution,
area of the old fuel tanks plus some Waste Acceptance Criteria testing fo
contamination testing as appropriate and targeted contamination testing
spoil disposal characterisation
area of the old fuel tanks plus some Waste Acceptance Criteria testing fo
- gas/water monitoring in standpipes, including monitoring for volatile vapo