Geotechnical News • June 2016
53
GEO-INTEREST
He knew that such a design —i n
which the floor area only is floated
—had been rejected for these soils
conditions by one soils engineer,
that it had been proceeded with
notwithstanding that advice and that
it had failed. While he knew very
little about preload, Mr. Doe knew
enough to recognize that he would
need expert guidance in order to
minimize the risks involved if that
design should be adopted for his own
project.
In May and June of 1979 Mr. Doe
discussed his requirements with
personnel from the Contractor who
provides and erects pre-fabricated
steel buildings, and was quoted more
attractive prices.
While these discussions with the
Contractor originally centred around
an all-piled foundation design, the
Contractor also mentioned to him
the possibility of a “floated” floor.
Mr. Doe brought a quantity of sand
onto the property and dumped it in
individual truck-load piles within the
building envelope. He says he did this
not for the purpose of preloading, but
with a view to raising the level of the
site on which he intended to build.
During the discussions between Mr.
Doe and the Contractor the repre-
sentative of the Contractor said they
would need to have a soils test done,
and recommended that the defendant
be asked to do it.
The Preliminary Report
The defendant is a company through
which Mr. Smith carried on his
practice as a soils engineer with the
assistance of three employees — two
technicians and a secretary.
It was one of the technicians, Mr.
Jones, who answered a telephone call
from Mr. Doe on June 12.Mr. Doe
described the sort of building he had
in mind and said he was planning
to build on an all-piled foundation.
Mr. Jones said that was a good idea
in view of the soils conditions in the
area. Mr. Doe said that he was think-
ing of having the Contractor erect
the building and that they needed a
soil investigation. He mentioned that
the owner of a nearby building had
experienced settlement problems.
Mr. Jones suggested a three-hole test
program as appropriate and said he
would get a driller to quote a price
and let Mr. Doe know the total cost.
After getting the drilling quotation,
he phoned back and said the cost
would be $900. Mr. Doe phoned
later and said they didn’t want to
pay that much; he asked for some-
thing less elaborate. After discussion
with Mr. Smith, Mr. Jones quoted
$400 for a report on a single test
hole, and Mr. Doe accepted.
Mr. Jones went to the site three days
later and supervised the test. The
nature of the test and the conclusions
which the defendant drew from it are
described in a document dated June
18, which plays a central role in the
present litigation. Headed
Report of
Preliminary Subsurface Soil Inves-
tigation and Recommendations
, it
reads as follows:
Introduction
In accordance with your request a
preliminary subsurface soil investiga-
tion was conducted June 15 at the
above project site. The proposed 50
foot by 100 foot building will be
steel frame with metal siding. A pile
foundation is planned. This report
presents recommendations for the
pile support of the foundation and
for the slab-on-grade floor.
Investigation
One penetration test hole was
placed at the location shown on the
attached Test Location Plan. A modi-
fied top drive Mayhew drill rig was
used to a depth of 50 feet. A 4 1/2
inch diameter auger hole was bored
to 12 foot depth to explore the upper
soil strata. This hole was placed
about 3 feet south of the penetration
hole.
Description of Site
The site is uniformly flat. No trees
exist. Stockpiles of river sand have
been deposited on the building site to
a depth of about 9 feet for the purpose
of preloading the slab area.
Description of Subsoil
The upper 20 feet of the site is
composed of a brown non-fibrous
peat with some fibrous peat mixed
in. This material is soft and saturated
below about 6 foot depth. The peat is
mixed with clay from about 20 to 30
feet and probably changes at about 30
feet to a sand and silt which exists to
the maximum 50 foot depth explored.
This sand provides suitable bearing
for piles.
Conclusions and Recommendations
The upper 30 feet of soil is unstable
and will consolidate under anticipated
floor loads. Preloading is advised to
stabilize this soil. The river sand cur-
rently on site is suitable preloading
material. Use 1 foot of this sand as
surcharge for each 95 psf of dead and
live load anticipated on this floor. The
penetration test indicates that indi-
vidual size 13 piles (minimum) driven
to 50 foot depth will develop 10 tons
Allowable Bearing Capacity. The same
size piles driven to 60 foot depth may
develop an Allowable Bearing Capac-
ity of 20 tons if the sand density
increases however this investigation
terminated at 50 feet and this increase
in density was not substantiated. The
piles may be either: used, marine piles,
10 pcf creosoted foundation piles;
or green pile for the lower section
and creosoted 15foot top section. A
securely fastened pipe splice is recom-
mended to join the upper and lower
sections of the 2 piece pile. The pile
driving operation should be supervised
by someone competent in this type
of work in order to ensure adequate
bearing for the piles on this project.
If questions should arise, please contact
the undersigned or Mr. Jones.
Mr. Smith, P.Eng.
The position of the plaintiff is that
this report gives the appearance of
approving use of the sand there—as
dumped in truck-load piles on the
