Selected Publications

A Record of Experience book cover

A Record of Experience…

by Boro Lukajic

This book reflects on Boro’s personal and professional experience. It contains 19 chapters; describes growing up in a small village, situated in a high mountainous region of the Southern Alps in the former Yugoslavia, now known as Bosnia and Herzegovina. In a professional sense, it reflects on the experience, working with many great Engineers and professional corporations. Project examples are presented in a brief descriptive style, illustrated with numerous photographs. The photographs of hydro dams, tunnels, nuclear stations and other structures have been provided to emphasize the nature of projects and the environment in which I worked.


A Perspective on Canadian Tunnelling 2005

Lukajic, B., Garrod, B. 2005. A Perspective on Canadian Tunnelling. K.Y.Lo Symposium, July 2005, London, Ontario.

Around the world, most countries depend on hidden, yet vital, tunnels to provide life-sustaining fundamentals such as power generation, transportation, water supply and sewage disposal system. The same is true here in Canada where the majority of the country’ tunnels provide the municipal infrasturcture required to sustain modern life in every city and town between the Pacific and Atlantic Oceans. Numerous hydroelectric facilities, including tunnels, were built in remote Arctic regions of Canada, some of which are beyond public (tourist) reach.

This paper provides a brief overview of Canadian tunnelling history, as well as current and future trends in tunnelling history.

Use of Asphalt in Treatment of Dam Foundation Leakage Stewartville Dam

Lukajic, B., Smith, G., and Deans, J. 1985. Use of Asphalt in Treatment of Dam Foundation Leakage: Stewartville Dam. ASCE Spring Convention, April 1985, Denver, Colorado.

This paper presents the recent development and application of a hot asphalt grouting technique used to stop a 5,000 Imperial Gallons Per Minute (IGPM) (22,000 lpm) dam leakage under full reservoir operating head. Two zones of major leakage were successfully sealed in 1983 and 1984 by simultaneous injection of hot asphalt and conventional cement grouts. This method was necessary in order to deal with the high velocity, turbulent water flow without plugging the adjacent foundation drain. In addition to improving the integrity of the dam foundation, the grouting eliminated water flow within the dam’s inspection tunnel which was a safety hazard to personnel and the plant.

While asphalt grouting may have been performed elsewhere under different field conditions, to our knowledge, this is the first instance of its use in Canada.

Exploratory Tunnel for the Mill Creek Project

Pintabona, R., Schafer, M., Lukajic, B., Kritzer, M., Shively, T., Switalski, R. Exploratory Tunnel for the Mill Creek Project; 2006 North American Tunneling Conference, Chicago, Illinois

A 1,216 -ft long, (9-ft diameter) exploratory tunnel was bored as part of the Mill Creek Project to investigate ground conditions underneath a buried glacial valley. The tunnel crown was supported with fiberglass dowels to allow unobstructed over-boring of a 24-ft. diameter (excavated) Mill Creek Phase 3 Tunnel. A comprehensive program of probe hole drilling, core sampling and seismic tomography was conducted to better define the location and condition of the soil/rock interface. The Mill Creek Tunnel is utilized to convey and store combined storm and sanitary sewage collected from the member communities in the southeast portion of Cleveland Ohio. This paper will provide an overview of design objectives and explain how an exploratory tunnel was used to provide clarity of underground conditions.

Gas Mitigation in the Mill Creek Tunnel

Schafer, M., Pintabona, R., and Lukajic, B. Gas Mitigation in the Mill Creek Tunnel; 2007 Rapid Excavation & Tunneling Conference & Exhibit, Toronto

Methane gas caused an eight-month shutdown of mining operations at the Mill Creek, Phase 3, Tunnel. The gasrelated shutdown occurred as the tunnel was advanced to an approximate distance of 2,700 feet, which constitutes approximately 18 % of the total tunnel length. The construction of an emergency ventilation shaft, a comprehensive program of de-gassing wells and an expanded gas monitoring system were used to mitigate the gas condition. When complete, this tunnel will be utilized to convey and store combined storm and sanitary sewage collected from a portion of Cleveland, Ohio and ten suburbs.

This paper will provide an overview of gas related remedial measures and explain how these measures were integrated into the project to ensure safe tunneling conditions.

Ground Freezing for Deep Shafts at the Mill Creek Tunnel Project

Lukajic, B., Pintabona, R., Kritzer, M., and Switalski, R. Ground Freezing for Deep Shafts at the Mill Creek Tunnel Project, 2003 North American Tunneling Conference, New Orleans, Louisiana, USA

Artificial ground freezing was chosen as an initial support method during construction of two deep shafts at the Mill Creek project. The 13,000 feet long Mill Creek, Phase 2 tunnel (MCT-2) is utilized to convey and store combined storm and sanitary sewage collected from the member communities in the greater Cleveland area. The project was conceived as the backbone of an integrated solution to convey and store flows while relieving the existing undersized sewers. The main objective of ground freezing was to provide a strong shaft support structure to resist soil and groundwater pressures. This was achieved by creating a watertight, frozen-ground barrier around the shaft perimeter. Both shafts are located in a buried ancient glacial valley. The paper will provide an overview of ground freezing techniques applied during the construction phase that ensured safe shaft excavation.

In-Situ Stresses in a Rock Overhang at the Ontario Power Generating Station, Niagara Falls

Lo, K.Y., Lukajic, B., Yuen, C.M.K., and Hori, M. In-Situ Stresses in a Rock Overhang at the Ontario Power Generating Station, Niagara Falls, Ontario, 1979 International Rock Mechanics conference, Montreux, Switzerland

The power house of the Ontario Power Generating Station is located approximately 240m downstream from the Horseshoe Falls at Niagara Falls. A 24m high vertical rock cliff exists directly above the power house. A comprehensive programme of investigation was performed for evaluating the cliff stability, including in-situ stress measurements and joint survey. The results of stress measurements showed that high horizontal stresses existed parallel to the Gorge face. The variation in magnitude and orientation may be related to the regional stress system, the major and minor topographic features and the mechanical properties of the rock members. The effect of these stresses on the stability of the rock cliff and the remedial measures undertaken are also described.

Cliff Stabilization in the Niagara Gorge

Lukajic, B., Azis, I., and Dupak, D. 1983. Cliff Stabilization in the Niagara Gorge. VII Pan-American Conference, June 1983, Vancouver, British Columbia.

The Niagara Gorge of southern Ontario occupies a unique position in the early development of hydroelectric power. Since the early 1900’s, three generating stations have been constructed in the Gorge on the Canadian side of the river to harness the potential of Niagara Falls. During this period, the rock cliffs adjacent to these generating stations have undergone deterioration and weathering. This has required remedial measures to be taken in order to maintain or increase the stability of the cliff faces.

A World Class Giant

Lukajic, B. 2017. A World Class Giant. Tunnels and Tunnelling, December-January 2017.

As part of Canada’s 150th anniversary in 2017 T&T North America, in conjunction with the Tunnelling Association of Canada, is celebrating industry’s landmark underground projects. Boro Lukajic begins the six-part series with the Churchill Falls Generating Station

Great Lakes Journey

Great Lakes Journey; 2017 Tunnels and Tunneling Journal, 40 – 42 Hatton Garden, London, United Kingdom

As part of the Sesquicentennial series Boro Lukajic reflects on his personal tunnelling experience under Lake Huron and Lake Ontario. The article features construction aspects of cooling water tunnels for nuclear stations.

Rock Tunnelling at the Mill Creek Project

Schafer, M., Lukajic, B., Pintabona, R., Kritzer, M., Shively, T., and Switalski, R. Rock Tunnelling at the Mill Creek Project; 2004 North American Tunneling conference, Atlanta, Georgia, USA

The Mill Creek Phase 2 Tunnel (MCT-2) is the largest tunneling project undertaken by the Northeast Ohio Regional Sewer District (NEORSD). The 13,000-ft long tunnel was mined using a 24-ft diameter boring machine in shale ranging from 160 to 260 feet in depth. The tunnel will be utilized to convey and store combined storm and sanitary sewage collected from the member communities in the greater Cleveland area. The project was conceived as the backbone of an integrated solution to convey and store flows, relieving the existing undersized sewers. This paper will discuss the design of the tunnel and describe the construction progress to date. The discussion will include design of tunnel support and criteria for selection of tunnel boring machine (TBM).

Trenchless Crossing of Highway 400 in Saturated Sands

Horan, A., Lukajic, B., Kneght, L. 2014. Trenchless Crossing of Highway 400 in Saturated Sands. North American Society for Trenchless Technology No-Dig Show, April 2014, Orlando, Florida.

A 600mm Concrete Pressure Pipe (CPP) watermain line was installed in the City of Barrie (Ontario) to upgrade the water supply and to match an increase in demand. As part of this upgrade, it was necessary for approximately 90m of the watermain to cross the King’s Highway 400 south of the Anne Street Bridge – a stretch of highway which has an annual average daily traffic volume of 112,00 vehicles.

Ground conditions at the crossing location consisted of a layer of sand and gravelly fill overlying native deposits of medium to fine grained saturated sand with SPT “N” values ranging from 8 – 69 recorded at the proposed crossing horizon. The crossing was of high risk when the daily traffic volumes and difficult ground conditions are taken into account.

Several trenchless methods were evaluated for this crossing. They included pipe jacking, jack and bore, horizontal directional drilling, pipe ramming and Earth Pressure Balance (EPB) tunnelling. Slurry microtunnelling was eventually recommended for the crossing given its advantages over the previously mentioned methods.

The crossing was performed with a Herrenknecht AVN1200TC in September 2012. The TBM was jacked using reinforced concrete pipe as the primary liner. A settlement monitoring program was employed during tunnelling, and for a time after completion of the crossing to ensure there were no time dependent effects. This monitoring program produced a bank of data which shows that the crossing had no effect on the HWY 400 surface and that no appreciable settlement was recorded at ground level.

Final Tunnel Liner at Mill Creek 3 Project – Case Study

Schafer, M., Lukajic, B., Pintabona, R., Kritzer, M., Switalski, R., Janosko, S. Final Tunnel Liner at Mill Creek 3 Project – Case Study; 2008 North American Tunneling Conference, San Francisco, California (USA)

The 20 foot diameter cast-in-place tunnel lining for Phase 3 of the Mill Creek Tunnel (MCT-3) has been completed. This paper will summarize aspects of liner design and address the construction approach in placing the liner in areas of tunnel that experienced crown overbreak. Tunnel lining production rates, installation procedures and form buoyancies experienced during concrete placement will also be presented.

Seepage Control During Tunnel Driving Under Lake Huron

Lukajic, B. 1986. Seepage Control During Tunnel Driving Under Lake Huron. International Symposium on Large Rock Caverns, August 1986, Helsinki, Finland.

The objective of this paper is to provide a case history on rock tunnelling beneath Lake Huron, Ontario, Canada. The project under review consisted of the construction of an 8.7m diameter cooling water intake tunnel for the Bruce B Nuclear Generating Station owned and operated by Ontario Hydro.

Continuous consolidation grouting of the tunnel was carried out to control water inflow during excavation. A summary of design parameters and construction procedures is given.

Tunnelling in Mayo, Yukon Territory

Mann, J., Dobson, R., McPhail, G., and Lukajic, B. 2014. Tunnelling in Mayo, Yukon Territory. Tunnelling Association of Canada, 2014, Vancouver, British Columbia.

The Mayo B project involved building a new two-unit 10 MW powerhouse downstream from the existing 5.4 MW Mayo A hydro facility, which was constructed in 1951. In order to divert water from the existing intake to the new powerhouse, construction of a new conveyance system was required, consisting of a 300-m long intake tunnel, and 3.6-km steel penstock. The tunnel excavation and structural concrete transition for the tie-in of the new Mayo B intake power tunnel to the existing Mayo A intake power tunnel were completed under full reservoir conditions.

The paper describes the experience gained, relative to tunnel design, construction, and tie-in to the existing sixty year old Mayo A intake. In addition, an overview is given of the measures engaged to mitigate an unstable rock slope, located immediately above the power tunnel intake.

Design and Construction of Darlington Cooling Water Discharge Tunnel

Lukajic, B., and Dupak, D. 1986. Design and Construction of Darlington Cooling Water Discharge Tunnel. International Congress on Large Underground Openings, June 1986, Firenze, Italy.

The paper summarizes the design and construction background for the 9.5m excavated diameter cooling water discharge tunnel at the Darlington Nuclear Generating Station. The tunnel is furnished with 90 diffuser shafts drilled through the soil and rock sediments beneath Lake Ontario.

Because of the project arrangement both the underground excavations and marine drilling were combined and carried out in several stages. The paper describes these operations and touches on other design features that influenced the construction sequence.

Mill Creek Tunnel Geomechanics

Lukajic, B., Schafer, M., Pintabona, R., Kritzer, M., Janosko, S., and Switalski, R. Mill Creek Tunnel Geomechanics; 2006 Tunneling Association of Canada Conference, Vancouver, British Columbia

The purpose of this paper is to review technical considerations and summarize the methods used in constructing the large diameter Mill Creek tunnels in shale. The three-phase tunnelling construction program encompasses nineteen (19) shafts and three (3) tunnels, totalling 12,727 m of tunnel length. The paper describes the experience gained during design and construction, relative to specialized techniques used for ground improvements and exploration.

Old Meets New

Mann, Jason, Dobson, Ryan, McPhail, Gordon, Lukajic, Boro. Old Meets New. Tunnels and Tunnelling. December 2014.

British Columbia’s minister of energy Bill Bennett opened the Vancouver TAC conference in October. With attendees from around the world, he had the perfect opportunity to boast. Some 80 per cent of the energy powering the province comes from hydropower. Bennett cites estimates that as many as one million people could move to BC over the next 20 years, requiring up to a 40 per cent increase in electricity demand. The region is looking to refurbish and replace many of its old facilities. In this section we present several of the papers from TAC Vancouver in light of the importance of hydropower work to Canada

Rehabilitation of the West Tailrace Tunnel, Churchill Falls, Labrador

Stevenson, G., Lukajic, B., Smith, W., and Hynes, G. Rehabilitation of the West Tailrace Tunnel, Churchill Falls, Labrador; Tunneling Association of Canada conference, 2003 Vancouver, British Columbia

The Churchill Falls Hydroelectric Project was watered up in 1971. The west tailrace tunnel was dewatered for inspection after 28 years in service. Most of the 1700 m long tunnel was in excellent condition. However, a 50 m long zone of altered schistose rock had weakened and failed due to chemical and physical weathering. The paper describes the investigation and assessment of the rock conditions, including the nature of the alteration. The remedial work consisted of staged dewatering of the tunnel, preparation of rock surfaces, application of shotcrete, installation of rock bolts, drilling of drain holes and removal of the rockfall debris from the floor of the tunnel. The objectives were to isolate the altered rock from the flowing water and to reinstate the rock support that had been originally installed. The work was performed in the summer of 2001.