discuss the  various types of foundations that are used and explain when should we use them in general. You are to write in general about

those different types of foundations and then chose 3 types which i have already chosen. We chose raft foundations, pile foundations and

pad foundations so we need to talk about why we chose them instead of the other types in detail. We are going to use those foundations to

support a 100m long Observation tower so you must explain the advantages those 3 types of foundations have over the rest and why they will

be efficient. Each foundation type is to be separate heading as to why we chose it. There is a geotechnical investigation we have that must

be looked at as to regard the type of land that is being dealt with. Methods to improve the quality of the sand such as compaction can also

be part of the report and you must explain why this type of foundation is better than for example a strip foundation or it will be

efficient and effective because it is cheaper or able to withstand more load. i will attach a copy of the soil investigation of the site in

which the observation tower will be built on to see the properties of the soil.
Geotechnical Investigation

Description of Borings

Ten (number) trial pits were excavated across the site; with depths ranging from 0.8 to 1.2m. Undisturbed samples were taken from the base

of each trial pit. These samples were tested for a range of geotechnical properties (see Table 1).

Additionally, 15 boreholes were excavated beneath the anticipated proposed footprint of the development using a light cable percussion

drilling rig or ‘shell and auger’.  The boreholes were cased as they were advanced in order to prevent cross-contamination and disturbed

samples were taken at the top of each stratum, with additional U100 undisturbed samples taken from the glacial clay.

Additionally, two further boreholes (See figure 1 for location) were driven using a rotary open hole drilling rig in order to confirm

bedrock and to determine the extent of weathering in the sandstone. These holes were extended to a minimum of 3.0 m into the bedrock.

Geotechnical Properties

The following table provides a summary of the geotechnical properties obtained from laboratory tests carried out on the encountered

materials:

Strata     Description    Thickness    Geotechnical properties obtained
Fill/made ground    Generally medium dense becoming loose black-brown clayey SAND and GRAVEL with fine to coarse brick fragments

0.40 – 1.30m    none
Alluvium    Soft brown sandy CLAY    0.50 – 5.10    mv = 0.00035 m2/kN             cv = 0.7 m2/yr                                 Su =

35 kN/m2
Sand and gravel    Dense becoming very dense with depth brown sandy fine to coarse rounded GRAVEL    2.90 – 4.20m    Mean SPT N value 42

= 52o
Boulder clay    Stiff reddish brown CLAY    12.0 – 15.0m    mv = 0.07 m2/kN                         cv = 5.0 m2

E = 7500 kN/m2                           Su = 125 kN/m2
Sandstone    Red-brown SANDSTONE    Not determined    Su = 4 MPa                                    UCS = 20 MPa
Table (1) Geotechnical properties of ground encountered.

Observations of the material recovered from the open hole drilling indicates that the sandstone is weakly weathered at the surface

progressing rapidly to fresh within 0.5m of the surface of the bedrock.

Groundwater conditions

Groundwater was encountered in all boreholes between the depths of 0.50 – 2.50m, within the sand and gravel deposits. Some water was

encountered in the superficial material within the trial pits and this did affect sidewall stability.

Borehole 1
Strata     Description    Depth       (m)    Geotechnical properties obtained
Fill/made ground    Generally medium dense becoming loose black-brown clayey SAND and GRAVEL with fine to coarse brick fragments    0 –

1.30    none
Alluvium
Soft brown sandy CLAY

1.30 – 5.10    mv = 0.00035 m2/kN
cv = 0.7 m2/yr                Su = 32 kN/m2
Sand and gravel    Dense becoming very dense with depth brown sandy fine to coarse rounded GRAVEL
5.10 – 9.20    Mean SPT N value 42
 = 45o
Boulder clay    Stiff reddish brown CLAY

9.20 – 24.0    mv = 0.07 m2/kN
cv = 5.0 m2
E = 7500 kN/m2
Su = 125 kN/m2
Sandstone    Red-brown SANDSTONE
24.0 –     Su = 4 MPa                     UCS = 20 MPa

Borehole 2
Strata     Description    Depth
(m)    Geotechnical properties obtained
Fill/made ground    Generally medium dense becoming loose black-brown clayey SAND and GRAVEL with fine to coarse brick fragments    0 –

0.40    none
Alluvium
Soft brown sandy CLAY

0.40 – 0.90    mv = 0.00025 m2/kN
cv = 1.05 m2/yr                Su = 35 kN/m2
Sand and gravel    Dense becoming very dense with depth brown sandy fine to coarse rounded GRAVEL
0.90 – 4.90    Mean SPT N value 35
 = 32o
Boulder clay    Stiff reddish brown CLAY

4.90 – 28.1    cv = 1.5 m2/yr
Eu = 6300 kN/m2
Su = 130 kN/m2

Sandstone
Red-brown SANDSTONE

28.1 –     Su = 4 MPa                     UCS = 20 MPa

Land Use Timeline
The earliest maps available are from 1848 where the site is shown as agricultural land.
1922
Ordnance Survey maps show two reservoirs on the site.  The first is surrounded by a dyeing and finishing works (surrounded by bowling

greens), the second is in the southern meadow section of the site.  Both appear to be used to supply industrial processes rather than for

water supply.
The weirs appear to have been constructed before 1922 to maintain a relatively constant level of water in the Irwell loop.
In the immediate vicinity of the Irwell loop there are many factories and industrial works – notably a pharmaceutical plant and an iron

works.  All are likely to have discharged fluids into the River Irwell.
The Adelphi Iron Works is known to have dumped fly ash onto the meadow on a weekly basis; this has considerably raised the general level of

the river loop.  The meadow was later used as a sport ground and playing field.
1933
The meadow reservoir was removed, and a large spoil heap has been established on the east bank of the Irwell loop extending between Cannon

St. and Peru St.
A hemming and stitching works is on the banks of the River at Adelphi.  The Engineering Works is significantly expanded.
An Architectural concept for a Portland stone, colonnaded City Hall on the meadow is abandoned.
1949
The spoil heap is extended further into the river.  A chemical factory is constructed at Adelphi on the Irwell loop.
There is a major flood in which Peel Park and all lower ground in Salford is consumed for two weeks.
1955
The spoil heap has been removed.
1968
Most of the industrial works have been removed.  The reservoirs have been removed.
The Adelphi chemical factory is converted for use by the University of Salford.
University of Salford constructs the Meadow Road campus, which includes bespoke civil engineering laboratories
2008
Meadow Road campus demolished.

Contamination Data
Reference to BGS Sheet Number 85, Manchester, indicates that the superficial geology beneath the site consists of Alluvium comprising clay,

silt, sand and gravel.  The solid geology is indicated to consist of Sherwood Sandstone.

In 2008, water quality for the River Irwell upstream was classified as E and D for Chemistry and Biology which is poor.

The site lies within the Outer Zone of a Groundwater Source Protection Zone.
The drift deposits below the site are classified as a ‘Secondary A’ aquifer. These are permeable layers capable of supporting water

supplies at a local rather than strategic scale, and in some cases forming an important source of base flow to rivers. These are generally

aquifers formerly classified as ‘minor aquifers’.

The bedrock below the site is classified as a ‘Principal Aquifer’. These are layers of rock which have high intergranular and/or fracture

permeability – meaning they usually provide a high level of water storage. They may support water supply and/or river base flow on a

strategic scale. In most cases, principal aquifers are aquifers previously designated as a major aquifer.

Visual inspection of the Made Ground indicated that ash and clinker were present.Hydrocarbon odours present at depths between 1.5m and 2.0m

below ground level.

Soil samples were screened using a Photo Ionisation Detector (PID) to test for the presence of VOC’s. The results were:
Borehole    Sample Depth (m)    VOC level (ppm)
1    1.20-1.40    1.2
2    0.40-0.60    4.0

Groundwater was not encountered during the SI. However seepages were encountered at 0.8m and 0.75m BGL in BH1 and BH2, respectively. None

of these seepages produced a ‘standing water level’ in either borehole during the site investigation.

The assessment has been undertaken in accordance with the Environment Agency Model Procedures for the Management of Land Contamination

(CLR11). A tiered approach has been adopted comprising a Generic Quantitative Risk Assessment (GQRA).  CLR11 recommends that soil samples

are assessed against the Contaminated Land Exposure Assessment (CLEA) Soil Guideline Values (SGVs).  For contaminants without a CLEA

derived SGV (old or revised), the soil results have been compared to equivalent Generic Assessment Criteria (GAC) derived by the Chartered

Institute of Environmental Health (CIEH) and Land Quality Management (LQM)7.

Comparison of Soil Analysis against Generic Quantitative Assessment Criteria (GQRA)
The chemical laboratory results for the site investigation have been compared against the relevant generic screening values. The results of

the GQRA screen are presented below. The contaminants shown are those which have values which have exceeded the GAC. Contaminants which

have not exceeded the GAC are not listed here. Asbestos was not identified within any of the samples analysed.

Contaminant    Unit    No. of Samples    Range of Concentrations (mg/kg)    GAC (mg/kg)    No. Exceeding GAC
Arsenic    mg/kg    6    23.59-287.3    130    1
Lead    mg/kg    6    320.6-7562.0    870    3
Benzo(a)pyrene    mg/kg    6    0.148-23.1    4.2    2
Organic Matter    %    6    Min: 1.1 Max: 5.7 (Mean: 3.7)
pH    pH    6    Min: 6.4 Max: 7.0 (Mean: 6.68)

The comparison shows that a number of contaminants exceeded the GAC’s for public open space (POS) land use. As such further statistical

analysis was undertaken upon the samples. The results of the statistical analysis are listed in the Table 5 below.

Contaminant    Mean (mg/kg)    UCL (mg/kg)    GAC (mg/kg)    Test Result
Arsenic    83.1    167.0    130    FAIL
Benzo(a)pyrene    5.64    12.9    4.2    FAIL
Lead    1900.48    4226.9    870    FAIL

The Made Ground statistical analysis indicated that the 95th percentile Upper Confidence Limit (UCL) for arsenic, lead and benzo(a)pyrene

exceeded the GAC and thus failed the GQRA.

Elevated levels of phytotoxic copper, zinc and nickel are present as outlined below:
Contaminant    Unit    Range of Concentrations (mg/kg)
Copper    mg/kg    139.2-1245
Zinc    mg/kg    149.5-4803
Nickel    mg/kg    21.6-201.9