Civil Engineering
What is civil engineering?
Civil engineers are trained to solve problems, objectively and impartially.
Civil engineering alters and reshapes the natural environment to provide built environment to meet the needs of mankind.
This field of engineering includes the planning, design, construction and maintenance of structures making up the built environment.
Examples of these structures are industrial, commercial and residential low- and high-rise buildings, also bridges, roads, dams, drainage systems, earthworks, and hydraulic works. Included is the plant and equipment in the buildings and the infra-structure servicing the buildings.
Consulting Civil Engineering Services
My consulting work includes:
| A. | Investigating surface and sub-surface conditions at proposed construction sites on-shore and off-shore. |
| B. | Characterizing the foundation soil conditions underlying a site. |
| C. | Identifying suitable foundations to support buildings and civil engineering structures resting on the soils underlying the site. |
| D. | Determining foundation design parameters. |
The objective is to uncover any problems peculiar to a site before the project reaches the construction stage, and to gather information to design solutions for any problems encountered.
I have investigated sites for different types of buildings and most types of civil engineering structures. These structures have included dams, bridges, earthworks, highways, airport runways, low-rise and multistory buildings, wharves and marine structures, pipelines, and drainage works.
The different structures have been located on a variety of surface and sub-surface ground conditions typical of eastern, western and northern Canada, offshore Nova Scotia (the Scotian Shelf), the Caribbean, North Africa, the U.K. and Australia.
Examples of Civil, Foundation and Geotechnical Engineering Projects
The different examples are organized into the following categories:
These projects usually involved investigating the foundation soil and groundwater conditions underlying proposed construction sites for buildings and civil engineering structures. Post-construction problems often involved civil litigation and are covered on the Forensic Engineering Page.
Each project is briefly described, significant problems identified where found, and the method of investigating the problem outlined.
I carried out the engineering investigations personally. Drilling and excavating work was contracted out to local firms. Laboratory testing was carried out at commercial laboratories in the area.
A. Multistory and Large Buildings
1. Multistory Condominium
Can-Euro Investments Limited retained my firm to inspect and approve construction of the foundations for the 19 story condominium on Horizon Drive, Dartmouth, adjacent Mic Mac Mall.
The building was constructed in an old rock quarry on sound bedrock. Broken bedrock from past blasting operations was exposed on the floor of the quarry.
The building was supported on five foot square concrete footings. Shear walls to resist wind load were located at right angles in the middle of the building.
Foundation inspection and approval involved:
Directing excavation of the broken bedrock down to sound bedrock.
Quality control of structural concrete.
Pull out tests of the shear wall anchors.
Quality control of the structural soil fill supporting extensive areas of concrete floor slab in the parking areas beneath and the beyond the building.
A critical situation was uncovered during construction when inspection revealed that the sound bedrock was sloping steeply at the location of some of the footings. Footings located on such a sloping surface would have slipped sideways and settled several inches severely damaging the building. The settlement would have occurred as the weight of the building came on the footings.
This situation was not covered in the specifications which was a serious omission. It was also missed by an inadequate investigation by others at the start of the project. The risk of failure was corrected quite simply by leveling the sloping bedrock with additional rock excavation.
2. Multistory Condominium
Can-Euro Investments have retained my firm to investigate the foundation and groundwater conditions for a third tower on Horizon Drive, the tallest to date at 22 stories. The development will include a four story commercial centre and basement parking to serve the residents and customers.
Investigation so far has involved walkover surveys, reviewing existing maps, plans, photographs and documents – a “desk study” in engineering terms, and examining existing parking garages in the Halifax area.
The investigation has found that the site is covered at one location by a large wetland, at others by old fill, and in one area by drainage infrastructure from former use of the site.
The investigation to date has also found that the dewatering systems for some basement parking garages in Halifax are not well designed resulting in increased operating costs.
3. Forest Products Shed
I was retained by a design-build firm to investigate the foundation soil conditions underlying the site of a forest products shed on the Halifax waterfront. We were also asked to provide materials testing and inspection services during construction.
This engineering investigation also uncovered a serious design error that may have caused the building to fail catastrophically or, at the very least, significantly reduce the factor of safety on failure.
At 190 feet, the shed had one of the longest roof truss spans in the area at the time. The steel trusses were supported on steel columns which in turn were carried on concrete footings bearing on an old sand fill.
Foundation investigation found that the footings were undersized by 50%. Roof load on the footings tended to push the footings sideways, to “kick out” the footins.
This sliding movement was resisted by the friction between the underside of the footing and the sand. The design engineer knew of two methods for calculating the magnitude of the friction, one of which was incorrect for the situation but produced a significantly cheaper footing - by 50%.
The error was corrected before foundation construction began. The correction significantly increased the design-build firm’s costs. The error occurred because the design engineer did not understand certain basic principles on the behaviour of foundations supported on soil.
B. Marine and Harbour Works
1. Marine and harbour works
I have investigated foundation soil and rock conditions in 23 public harbours in the Maritimes. These investigations were for wharves, breakwaters, dredging, etc. – all the different structures that make up a harbour including the onshore facilities.
The investigations are the most difficult and dangerous that engineers carry out and the foundation conditions are often the most troublesome to a design engineer.
The risk to the engineer and the equipment is that the investigation is carried out on small barges over water in exposed sea and weather conditions, strong currents, or off ice in the winter time.
The troublesome foundation conditions consist of quite variable foundation soil conditions, soft harbour bottom sediments, sloping bearing strata, large boulders embedded in layers of soil that can be mistaken for bedrock, and weak bedrock at the surface. And, because of the cost of harbour investigations, often barely enough foundation investigation data to make informed, cost effective design decisions.
To compound the situation further the design engineer of an offshore structure seldom has the option of relocating a structure elsewhere because of poor foundation soil conditions, an option often available to the designer of an onshore structure.
C. Offshore Structures
1. Scotian Shelf Atlas
I was retained by the Atlantic Geoscience Centre, Bedford Institute of Oceanography on behalf of the Geological Survey of Canada to co-author map sheets depicting the surficial geology and physical properties (of the foundation soils) of the Outer Shelf: Sable Island Bank and the Venture Field Region.
The map sheets are used by the offshore oil and gas exploration and production industry to plan geophysical surveying for oil and gas, drilling, development and production.
Use by the industry would include assessing foundation support for individual jack-up drilling rigs and production platforms.
The map sheets are included with a number of others in the Scotian Shelf Atlas, published by the Geological Survey of Canada.
My contribution involved characterizing the physical engineering properties related to foundation bearing capacity and foundation settlement for the Sable Island Bank and the Venture Field Region. I did this by studying the physical properties recorded in 65 boreholes drilled on the Bank and in the Venture Field over the years by various companies.
2. Jack-up Rig Foundation Stability
I was retained by a drilling company to determine the allowable foundation bearing pressure at six sites on the Scotia Shelf for a jack-up rig.
The engineering analyses used the data and results from the earlier mapping work I did. This type of analysis is fairly straightforward in civil engineering but more critical because of the hostile environment in which the rigs operate.
3. Rowen Gorilla III (the RG III)
I was retained by representatives of an offshore monitoring agency in Nova Scotia to do an independent review of the foundation stability of the R.G. III on a site offshore. Lloyds of London was insuring the stability of the rig while it was drilling on site.
My work involved studying and assessing the nature of the foundation soils, the planned foundations and the loads on the foundations. I also reviewed various engineering standards adopted by counties involved in exploring and developing the petroleum reserves off Canada’s east coast and in the North Sea. These standards are followed by rig foundation design engineers.
4. Semi-Submersible Drill Rig
I was retained by Irving Oil to determine the foundation soil conditions at the berth in Halifax Harbour of a semi-submersible drill rig. Irving Oil owned the rig that was tied up while under construction.
Semi-submersible drill rigs are maneuvered over a drilling site by large, heavy thrusters. Installation of these during construction of a rig involves briefly setting a thruster on the harbour bottom. Tugs then position the drill rig over the thruster which is lifted up and fastened in place on the underside of the rig.
The soils at the location where a thruster is set down had to be strong enough to support the thruster and prevent it from tipping over or sinking into the harbour bottom sediments.
I determined the foundation soil conditions including the allowable bearing pressure of the sediments by carrying out a fairly conventional geotechnical investigation. This involved drilling a number of boreholes from a barge and carrying out in-situ tests. The test results along with seismic survey data enabled me to define the layers of soil at the site and the bearing capacity of the soils.
5. “Malikpaq” Manmade Island
The Malikpaq (“Maw-leak-pack”) was a manmade island designed by engineers and constructed in the Beaufort Sea in Canada’s north. It was used to support drilling and petroleum operations. The island failed when it was pushed sideways by sea ice.
Engineers held a conference to determine exactly what took place during the failure. The conference proceedings were recorded, but by malfunctioning equipment.
I was retained to try and transcribe the technical proceedings. This involved listening to tapes of the proceedings and dictating an interpretation of what was said by the different engineers and scientists attending the conference. My interpretation of the proceedings was transcribed to a word processor and printed.
D. Terrain Analysis
Terrain analysis is a technique whereby engineers search for and identify sites of interest on the ground by studying and analysing topographic maps and aerial photographs. The shape and appearance of contours, drainage patterns, vegetation, etc. are used to identify a site with specified characteristics for the intended use.
Clients and engineers specify the characteristics of their site then these are looked for on maps and photographs. For example, a deposit of sand and gravel might be indicated on a map by a certain type of tree and a certain shape to the contours.
The technique enables large areas of countryside to be searched in a preliminary way then the most promising sites examined and confirmed in the field. The technique is used to find sites of interest for commercial use, e.g., cranberry bogs, and sites to be avoided, e.g., steep hills during road construction.
1. Cranberry bogs
I analysed most of the terrain on mainland Nova Scotia, part of Cape Breton Island, and a little on P.E.I. for a Wisconsin client interested in developing a cranberry growing operation.
We looked for commercially viable bogs and identified several. The client’s criteria were quite stringent. Characteristics of interest included bogs in an area with a long growing season, a certain type of peat moss, suitable drainage, availability of power, and road access. One bog was examined in the field and field testing carried out.
2. Sand deposits
Sand is needed in growing cranberries. I analysed most of the terrain in southwestern Nova Scotia using topographic maps, aerial photographs and field reconnaissance searching for deposits of sand for a government agency. The agency used the availability of sand in promoting the area to cranberry growing interests.
3. Industrial park
A developer retained me to study the terrain near Exit 5 on Hwy. 102 proposed for development as an industrial park. The area was found to be underlain by acidic slate bedrock. The acidic slate was indicated by study of geology maps and examination of bedrock exposures in the field. Drilling and testing on site confirmed the problems. An environmental monitoring programme was developed and costs estimated to carry out the programme. The client evaluated the situation and decided it was not economically feasible to proceed with the development.
E. Materials Testing and Inspection
I have been retained by different owners to test and inspect the materials used by contractors during construction of civil engineering works, and to confirm that workmanship conformed to the specifications. These types of quality control testing and inspection services are a normal part of civil engineering work.
1. Missile storage facility
Defence Construction Ltd. (DCL) retained me to provide concrete testing services and to inspect construction of the missile storage facility on Bedford Basin, off Magazine Hill. The facility was constructed of 7,000 cubic yards of concrete, the largest concrete quality control project in the Maritimes at the time. The walls of each missile storage unit were eight feet (8’) thick.
2. Shearwater HDQ
DCL also retained my firm to provide concrete quality control services during construction of the defence headquarters office at Shearwater.
3. Woodside Industrial Park
I was asked by design engineers for the Woodside Industrial Park to provide soil compaction quality control during earthworks construction of the building lots forming the Park. Construction involved excavating soil from one part of the Park and placing it in another. The industrial lots were formed on the “cut and fill” areas of the Park. Quality control involved carrying out numerous laboratory tests of the soil and hundreds of field compaction tests of the soil.
4. Victoria Street, Amherst
The Town of Amherst retained me to provide materials quality control, testing and inspection services during rebuilding of Victoria Street. Laboratory and field tests were carried out on soil, concrete and asphalt.
F. Wind turbines
1. Innovation Centre, N.S. Research Station
I investigated the foundation soils for the proposed design and construction of a wind turbine at the Innovation Centre.
This type of investigation is carried out for all important buildings and civil engineering structures. Investigation follows guidelines in publications like the Canadian Foundation Engineering Manual. Investigation can be simple or difficult depending on the nature of the foundation soils at the site and the requirements of the structure’s foundations.
The investigation for the Innovation Centre was quite simple because of the competent foundation soils underlying the site.
The turbine site was on a drumlin, a well known type of glacial soil deposit with well known engineering properties. The Halifax Citadel sits on another drumlin. The investigation consisted of studying soil maps and confirming the presence of the drumlin then drilling boreholes and carrying out field tests to obtain numerical data for calculating the allowable foundation bearing pressure.
G. Power stations
1. Power stations and substations
I investigated foundation soil conditions underlying power stations and substations in the Bahamas and in Nova Scotia. The sites were underlain by a variety of soils including difficult soils and rocks like the Karst terrain in the Bahamas and the loose sands in Truro, Nova Scotia. Conventional field and laboratory investigation and testing methods were used to determine the types of soils underlying the sites and characterize their engineering properties.
2. Tidal power stations
I monitored stability of the deep excavation made during construction of the Annapolis Tidal Power Station at Annapolis Royal, Nova Scotia. The excavation was in glacial soils. Monitoring involved examination of the ground surrounding the excavation for cracks, a sign associated with slope instability.
I also determined the engineering properties of the soils for design of the 60 foot high concrete retaining walls at the inlet to the power stations turbine. The soils were used to backfill the retaining walls.
H. Civil engineering structures
1. Hector reconstruction
I was retained by the Town of Pictou, Nova Scotia to investigate the foundation soil conditions at the site of the Hector reconstruction on the Pictou waterfront, Nova Scotia. A replica of the wooden ship that brought the first Scottish settlers to Nova Scotia was being built on the shore of Pictou Harbour.
The investigation involved drilling deep boreholes in the old fill and soft, marine sediments down to strong soils. Field tests were carried out in the boreholes and data obtained to characterize the different layers of soils and their engineering properties.
2. Steamline, Dartmouth Hospital
I was retained by design engineers for a steam line to run from the Dartmouth Hospital across Pleasant Street to the Nova Scotia Hospital. The steamline was to be buried on hospital property but elevated over the road.
The depth of old fill soils on the hospital property were of particular interest to the designers.
My investigation consisted of researching topographic maps for the area and comparing contours of the ground surface before and after fill was placed on the site. This enabled me to determine the depth of the fill as 18 feet, to a precision of 0.5 feet as found later during excavation for the steam line.
Contours give the height of the ground along a (contour) line at the time a topographic map was made.
It was not possible to use more conventional methods of investigation like measuring the depth of the fill in boreholes because of difficult access to the site for a drill rig.
I. Airport Runways
1. Nassau and Marsh Harbour Airport Runways, Bahamas
I was retained by the Bahamian Ministry of Works to investigate and determine the foundation soil and rock conditions at the sites of proposed new runways at the airports at Nassau, New Providence and Marsh Harbour, Abaco Island.
Both international airports are underlain by a shallow depth of cavernous limestone; Karst terrain. The limestone was exposed at the surface at Nassau Airport and at a depth of a few inches to about three feet at the Marsh Harbour airport.
The most serious potential problem at the location of the runways was the occurrence of voids – caverns, just below the surface that would collapse under the weight of an aircraft. These could be a few inches to several feet across and deep.
I investigated both sites by probing for voids with a drill rig. The probing was done on a grid at Nassau and on the centreline at Marsh Harbour. The foundation soils at some locations at Marsh Harbour were also investigated with boreholes and field testing.
Civil, Geotechnical, Foundation and Environmental Engineers
Dartmouth, Nova Scotia, Canada
Sailboat image courtesy of J. Knoll.
