Building collapse in Kandy due to foundation on unstable slope: National implications

By Dulip Jayawardena

The recent collapse of a five-storey building in Kandy has caused much concern among the residents around the district, especially those who have built houses around slopes which are now speculated as unstable by an expert geologist who has rung alarm bells indicating that all those who reside on hill slopes should vacate their houses during heavy rains.

The Governor of the Central Province has gone on record as saying there are over 200 buildings, including houses, at risk of collapse, and it is pertinent to question whether that conclusion was reached after conducting relevant investigations.

HISTORY OF FOUNDATION

ENGINEERING IN SRI LANKA

The origin of the Geological Survey Department (present GSMB ) can be traced to 1904, when Dr Ananda Cooramaswamy was the Principal Mineral Surveyor appointed by the Colonial government. The Mineral Survey was converted into the Mineralogy Department in early the 1940s and, with the appointment of the first Sri Lankan as Head of the Department, in 1948 this vital state institution was renamed the Geological Survey Department (GSD) in 1961.

With the reorganisation of the GSD, an Engineering Geology section was created and the first Engineering Geologist was my former Director, the late D. B. Pattiarachchi, who underwent extensive training at the US Bureau of Reclamation, which was founded in 1902.

The GSD had a very efficient Engineering Geology Section, headed by Pattiarachchi and all the foundation investigations for major buildings, power plants hydro electric dams, reservoirs, etc., were undertaken by it. Some of the foundation investigations that I was involved in were the construction of the proposed Urea Plant at Sapugaskanda by Kellogg Inc of USA at a cost of US $ 117 million in early the 1970s and the Electro Smelting Plant at the Oruwela Steel Corporation also in the early 1970s with the assistance of the former Soviet Union.

Following the establishment of the GSMB in terms of the Mines and Minerals Act No 33 of 1992, the earlier functions of the GSD, in engineering geology were dropped (See Para 12 (a) to (e) of the Act). However, the Mines and Minerals (Amendment )Act No 66 of 2009 was amended to undertake projects in regard to engineering geology and advise and recommend remedial measures in case of geological hazards and disasters.

The question is whether there is an effective engineering geology division at GSMB with trained engineering geologists.

In order to educate the readers and the so-called experts, I would like to quote from a publication titled “Engineering geology: Principles and Practice” Publisher Springer Authors D.G. Price and Michael Freitas, etc., where the Abstract reads as follows “Provides the reader with the basics of engineering geology illustrates how geology is related to calculations of stability, deformation and groundwater flow. Specifically written for those first degree is not geotechnical engineering. Shows how to identify, investigate and define an engineering response to problems arising from ground conditions … The text is directed at the heart of Engineering Geology where geology is used to identify potential problems arising from ground conditions. It describes how to investigate those conditions and to define an engineering response that will either avoid or reduce related calculations of stability deformation and ground water flow ….” This applies to shallow foundations in residential areas, especially in the hill country of Sri Lanka.

THE NATIONAL BUILDING RESEARCH ORGANIZATION (NBRO) AND LANDSLIDE HAZARD MAPS

The NBRO is now designated as the prime organisation specialising in landslides and formulating effective policies and strategies to effect risk reduction.

It must be stressed that the GSD was earlier involved in these functions that have been assigned to NBRO. It is incorrect to say that according to NBRO landslide studies date back to only 1980, ignoring the extensive field and research studies done by the GSD from the early 1960s.

A paper written by me titled “Analysis of Devastating Landslides in Haldumulla – Koslanda Areas ( -lands) I have stated that landslides up to 2002 were considered as minor disasters and from 1974 to 2002 the incidence was 10 to 60 per annum. However in 2006 this number shot up to 360.

It was recognised by GSD that from the 1980s that the Haputale scarp including the devastating landslide that occurred at Haldumulla on October 29, 2014, causing a huge of loss of lives and property proved that the area from Haldumulla and Koslanda as well as the Poonagala Valley up to Ella is unstable. It is interesting to find out whether the NBRO has done any detailed studies in this area recently.

The seasonal distributions of rainfall were during the south west and north east monsoons and the months were January, May and October that experienced highest rainfall. It appears that this trend has been affected due to climate change; Sri Lanka has not placed emphasis on carrying out research in this regards.

I have also stressed that the Meteorology Department should analyze rainfall data since 1956 up to present and compare them with the data from the Hunting Survey Corporation of Canada, in which past records indicate rainfall data from 1907 to 1956. A Monograph titled “Hydrometeorology of Ceylon” was compiled and copies were available at the relevant Departments including GSD. The temperature variations were also published.

Any change in rainfall during the period October to January identified as the autumnal period may be directly attributed to climate change.

LANDSLIDE HAZARD MAPS AND NBRO

The NBRO, established in 1985 to conduct building and geotechnical research, was involved in Landslide Hazard Zoning Programme (LHZMP) to compile Landslide Hazard maps with funding from the UNDP, in 1990, and initially covered the Nuwara-Eliya and Badulla Districts. This programme was eventually extended to 12 other landslide prone districts namely Kegalle, Matale, Kandy, Kalutara, Galle, Hambantota, Moneragala and Kurunegala. Three hazard zones were identified as High, Medium and Low by analyzing relevant data related to geology, hydrology, inclination of slopes, landform, soil characteristics and its thickness and land use. Public and stakeholder awareness programmes were initiated in effected landslide areas. Conflicting land use by stakeholders due to land development, building and relevant construction activities were not recognised. Further identification of zones related to these development activities would help avoid conflicting land use, especially in the areas with high population density.

TESTING GEOTECHNICAL PROPERTIES OF SOIL

The Standard Penetration Test (SPT) is an effective test to check the geotechnical engineering properties of soil. ( https: //en.wikipedia.org/wiki/Standard_penetration_test ). The procedure helps determine relative density of soil which can vary from very loose, loose, medium dense and very dense. In house building, the bearing capacity determined by the SPT will depend on the foundation load factor, namely number of floors, concrete columns, including reinforced steel beams, etc.

TYPES OF FOUNDATIONS IN BUILDING CONSTRUCTION

There are many types of foundations in building construction .

I quote from an article, “Foundations in Building Construction- Understanding Building Construction” as follows “In this article we will discuss the common types of foundations in buildings. Broadly speaking all foundations are divided into two categories: shallow foundations and deep foundations. The words shallow and deep refer to the depth of soil in which foundation is made. Shallow foundations can be made in depths of as little as 3 ft. (1m) when deep foundations can be made at depths of 6 -200 ft (20-65m) shallow foundations are used for small light buildings while deep ones for large heavy buildings” ( http://www.understanding construction.com/types-of-foundations.html ). The types are (a) individual footings (c) strip footings (d) raft or mat foundations and (e) pile foundations.

Another common type of foundation is the floating foundation (Ref Floating Foundation – Principles, Suitability and construction Difficulties – quoting “a floating foundation is a type of foundation constructed by excavating the soil in such a way that the weight of structure built on the soil is nearly equal to the total weight of soil excavated from the ground including the weight of water in the soil before construction of structure. Floating foundation is also called balancing raft and caused zero settlement to the structure”

However, in most of the lowlands, especially around Colombo, the soil in underlain by laterite (weathered hard rock) and some areas are identified as soft laterite. Accordingly, if a floating foundation is anchored in hard laterite and if some areas have soft laterite it will result in differential settlement which will damage the building due to differential settlement.

DEVELOPING BUILDING CODES FOR SRI LANKA

It is encouraging to note that the NBRO with the Construction Industry Development Authority (CIDA) has initiated action to formulate building codes with financial assistance from the World Bank which has appointed an expert team, led by the University College London, to conduct a Building Regulatory Capacity Assessment in Sri Lanka. This team will carry out the following tasks:

“(1) to evaluate the current Building Regulatory capacity in Sri Lanka. (2) To facilitate discourse and consultations with local stakeholders in Sri Lanka to determine their aspirations for an improved system of building Regulations and identify barriers and opportunities for their implementation (3) Provide tailored recommendations for implementation of an improved Building Regulatory system.

Further, a Steering Committee Meeting (SCM) had been held on 7 March 2019 with the team from the University College London and consisted of the following organizations (1) Ministry of Public Administration and Disaster Management (2) Ministry of Housing Construction and Cultural Affairs (3) National Building Research Organization (4) Construction Industry Development Authority (5 ) Urban Development Authority (6) National Physical Planning Department (7) Sri Lanka Institute of Local Governance and (8) Disaster Management Centre .

A Workshop held on 8 March 2019 on Building Regulatory Capacity Assessment (BRCA) to identify the views of the stake holders on the following (a) National level legislation and institutions (b) Building code development and maintenance (c) Local level implementation

(Ref Building Codes for Resilience <http:www.nbro.gov.lk/index.php?option=com_content&view=a…>

It is interesting to find out about the progress of this Expert Group in identifying and formulating the relevant Building codes covering the entire Island.

CONCLUSIONS

In this article, I have highlighted the collapse of a five-storied building used as a residence in an unstable slope in Kandy. It has now resulted in the law enforcing authorities taking legal action about the construction and the owner of the building has made statements that all approvals were obtained from the regulatory agencies and the construction was supervised by the State Engineering Corporation.

I also highlighted the past activities of the Geological Survey Department (GSD Present GSMB) and the extensive work carried out by the Engineering Geology Section in foundation investigations as well as the landslide investigations by the highly qualified and experienced geologists with a limited staff of only 13 geologists. However in 1992 with the conversion of the GSD to GSMB both a legitimate functions of GSD namely foundation investigations as well as landslide studies was dropped but again in 2009 with the Amendments to the GSMB Act those functions were restored. It is queried whether the GSMB is now involved in these functions.

I also briefly described the various foundations and also the initiation of identifying procedures for formulation of appropriate building codes.

RECOMMENDATIONS

(1) The NBRO, which has prepared landslide hazard maps covering the 14 districts should make these maps available to local government authorities and building plans should be approved with the recommendations of NBRO.

(2) The GSMB should also actively get involved to identify landslide prone areas as well as foundation investigations for residencies and buildings.

(3) The NBRO should demarcate safe zones in the High, Medium and Low Risk areas for housing and other buildings including factories for relevant industries by foreign and local investors.

(4) The government should study the creation of effective entities that would have expertise of civil engineers, geotechnical engineers, engineering geologists, representatives from NBRO and Disaster Management Center, Ministry of Environment Central Environment Authority (CEA) etc to approve building plans for dwellings and the industrial activities. Such entities could be on a district basis.

(5) To expedite identification and appropriate building codes for construction in the three areas namely High, Medium and Low Risk areas and legislate such Codes expeditiously.

(6) Include the Ministry of Environment CEA and the GSMB to participate in the Steering Committee for developing building codes for the entire Island.

(7) The NBRO and GSMB should actively coordinate in exchange information of landslides that had occurred prior to 1992 and past foundation investigations by the GSD and create a depository of such information and data for the use of relevant agencies.

(8) The appointment of a Presidential Task Force to regulate building activity in Sri Lanka with all safety precautions and eliminate loss of life and property to achieve sustainable economic and social development.

References

1. Landslide Danger Risk Reduction Strategies and Present Achievements in Sri Lanka by R.M.S.Bandara and Padhmakumara Jayasinghe National building Research Organization Geosciences Research Vol 3 No 3 August 2018.

2. Standard penetration test –Wikipedia

3. Developing Building Code for Resilience – NBRO

(The writer is a retired Economic Affairs Officer United Nations ESCAP and former Director Geological Survey Department form 1983 10 1985 (Present GSMB) Professional Geologist for over 55 years and can be contacted at ?)

Building collapse in Kandy due to foundation on unstable slope: National implications

By Dulip Jayawardena

The recent collapse of a five-storey building in Kandy has caused much concern among the residents around the district, especially those who have built houses around slopes which are now speculated as unstable by an expert geologist who has rung alarm bells indicating that all those who reside on hill slopes should vacate their houses during heavy rains.

The Governor of the Central Province has gone on record as saying there are over 200 buildings, including houses, at risk of collapse, and it is pertinent to question whether that conclusion was reached after conducting relevant investigations.

HISTORY OF FOUNDATION

ENGINEERING IN SRI LANKA

The origin of the Geological Survey Department (present GSMB ) can be traced to 1904, when Dr Ananda Cooramaswamy was the Principal Mineral Surveyor appointed by the Colonial government. The Mineral Survey was converted into the Mineralogy Department in early the 1940s and, with the appointment of the first Sri Lankan as Head of the Department, in 1948 this vital state institution was renamed the Geological Survey Department (GSD) in 1961.

With the reorganisation of the GSD, an Engineering Geology section was created and the first Engineering Geologist was my former Director, the late D. B. Pattiarachchi, who underwent extensive training at the US Bureau of Reclamation, which was founded in 1902.

The GSD had a very efficient Engineering Geology Section, headed by Pattiarachchi and all the foundation investigations for major buildings, power plants hydro electric dams, reservoirs, etc., were undertaken by it. Some of the foundation investigations that I was involved in were the construction of the proposed Urea Plant at Sapugaskanda by Kellogg Inc of USA at a cost of US $ 117 million in early the 1970s and the Electro Smelting Plant at the Oruwela Steel Corporation also in the early 1970s with the assistance of the former Soviet Union.

Following the establishment of the GSMB in terms of the Mines and Minerals Act No 33 of 1992, the earlier functions of the GSD, in engineering geology were dropped (See Para 12 (a) to (e) of the Act). However, the Mines and Minerals (Amendment )Act No 66 of 2009 was amended to undertake projects in regard to engineering geology and advise and recommend remedial measures in case of geological hazards and disasters.

The question is whether there is an effective engineering geology division at GSMB with trained engineering geologists.

In order to educate the readers and the so-called experts, I would like to quote from a publication titled “Engineering geology: Principles and Practice” Publisher Springer Authors D.G. Price and Michael Freitas, etc., where the Abstract reads as follows “Provides the reader with the basics of engineering geology illustrates how geology is related to calculations of stability, deformation and groundwater flow. Specifically written for those first degree is not geotechnical engineering. Shows how to identify, investigate and define an engineering response to problems arising from ground conditions … The text is directed at the heart of Engineering Geology where geology is used to identify potential problems arising from ground conditions. It describes how to investigate those conditions and to define an engineering response that will either avoid or reduce related calculations of stability deformation and ground water flow ….” This applies to shallow foundations in residential areas, especially in the hill country of Sri Lanka.

THE NATIONAL BUILDING RESEARCH ORGANIZATION (NBRO) AND LANDSLIDE HAZARD MAPS

The NBRO is now designated as the prime organisation specialising in landslides and formulating effective policies and strategies to effect risk reduction.

It must be stressed that the GSD was earlier involved in these functions that have been assigned to NBRO. It is incorrect to say that according to NBRO landslide studies date back to only 1980, ignoring the extensive field and research studies done by the GSD from the early 1960s.

A paper written by me titled “Analysis of Devastating Landslides in Haldumulla – Koslanda Areas ( -lands) I have stated that landslides up to 2002 were considered as minor disasters and from 1974 to 2002 the incidence was 10 to 60 per annum. However in 2006 this number shot up to 360.

It was recognised by GSD that from the 1980s that the Haputale scarp including the devastating landslide that occurred at Haldumulla on October 29, 2014, causing a huge of loss of lives and property proved that the area from Haldumulla and Koslanda as well as the Poonagala Valley up to Ella is unstable. It is interesting to find out whether the NBRO has done any detailed studies in this area recently.

The seasonal distributions of rainfall were during the south west and north east monsoons and the months were January, May and October that experienced highest rainfall. It appears that this trend has been affected due to climate change; Sri Lanka has not placed emphasis on carrying out research in this regards.

I have also stressed that the Meteorology Department should analyze rainfall data since 1956 up to present and compare them with the data from the Hunting Survey Corporation of Canada, in which past records indicate rainfall data from 1907 to 1956. A Monograph titled “Hydrometeorology of Ceylon” was compiled and copies were available at the relevant Departments including GSD. The temperature variations were also published.

Any change in rainfall during the period October to January identified as the autumnal period may be directly attributed to climate change.

LANDSLIDE HAZARD MAPS AND NBRO

The NBRO, established in 1985 to conduct building and geotechnical research, was involved in Landslide Hazard Zoning Programme (LHZMP) to compile Landslide Hazard maps with funding from the UNDP, in 1990, and initially covered the Nuwara-Eliya and Badulla Districts. This programme was eventually extended to 12 other landslide prone districts namely Kegalle, Matale, Kandy, Kalutara, Galle, Hambantota, Moneragala and Kurunegala. Three hazard zones were identified as High, Medium and Low by analyzing relevant data related to geology, hydrology, inclination of slopes, landform, soil characteristics and its thickness and land use. Public and stakeholder awareness programmes were initiated in effected landslide areas. Conflicting land use by stakeholders due to land development, building and relevant construction activities were not recognised. Further identification of zones related to these development activities would help avoid conflicting land use, especially in the areas with high population density.

TESTING GEOTECHNICAL PROPERTIES OF SOIL

The Standard Penetration Test (SPT) is an effective test to check the geotechnical engineering properties of soil. ( https: //en.wikipedia.org/wiki/Standard_penetration_test ). The procedure helps determine relative density of soil which can vary from very loose, loose, medium dense and very dense. In house building, the bearing capacity determined by the SPT will depend on the foundation load factor, namely number of floors, concrete columns, including reinforced steel beams, etc.

TYPES OF FOUNDATIONS IN BUILDING CONSTRUCTION

There are many types of foundations in building construction .

I quote from an article, “Foundations in Building Construction- Understanding Building Construction” as follows “In this article we will discuss the common types of foundations in buildings. Broadly speaking all foundations are divided into two categories: shallow foundations and deep foundations. The words shallow and deep refer to the depth of soil in which foundation is made. Shallow foundations can be made in depths of as little as 3 ft. (1m) when deep foundations can be made at depths of 6 -200 ft (20-65m) shallow foundations are used for small light buildings while deep ones for large heavy buildings” ( http://www.understanding construction.com/types-of-foundations.html ). The types are (a) individual footings (c) strip footings (d) raft or mat foundations and (e) pile foundations.

Another common type of foundation is the floating foundation (Ref Floating Foundation – Principles, Suitability and construction Difficulties – quoting “a floating foundation is a type of foundation constructed by excavating the soil in such a way that the weight of structure built on the soil is nearly equal to the total weight of soil excavated from the ground including the weight of water in the soil before construction of structure. Floating foundation is also called balancing raft and caused zero settlement to the structure”

However, in most of the lowlands, especially around Colombo, the soil in underlain by laterite (weathered hard rock) and some areas are identified as soft laterite. Accordingly, if a floating foundation is anchored in hard laterite and if some areas have soft laterite it will result in differential settlement which will damage the building due to differential settlement.

DEVELOPING BUILDING CODES FOR SRI LANKA

It is encouraging to note that the NBRO with the Construction Industry Development Authority (CIDA) has initiated action to formulate building codes with financial assistance from the World Bank which has appointed an expert team, led by the University College London, to conduct a Building Regulatory Capacity Assessment in Sri Lanka. This team will carry out the following tasks:

Building

“(1) to evaluate the current Building Regulatory capacity in Sri Lanka. (2) To facilitate discourse and consultations with local stakeholders in Sri Lanka to determine their aspirations for an improved system of building Regulations and identify barriers and opportunities for their implementation (3) Provide tailored recommendations for implementation of an improved Building Regulatory system.

Further, a Steering Committee Meeting (SCM) had been held on 7 March 2019 with the team from the University College London and consisted of the following organizations (1) Ministry of Public Administration and Disaster Management (2) Ministry of Housing Construction and Cultural Affairs (3) National Building Research Organization (4) Construction Industry Development Authority (5 ) Urban Development Authority (6) National Physical Planning Department (7) Sri Lanka Institute of Local Governance and (8) Disaster Management Centre .

A Workshop held on 8 March 2019 on Building Regulatory Capacity Assessment (BRCA) to identify the views of the stake holders on the following (a) National level legislation and institutions (b) Building code development and maintenance (c) Local level implementation

(Ref Building Codes for Resilience <http:www.nbro.gov.lk/index.php?option=com_content&view=a…>

It is interesting to find out about the progress of this Expert Group in identifying and formulating the relevant Building codes covering the entire Island.

CONCLUSIONS

In this article, I have highlighted the collapse of a five-storied building used as a residence in an unstable slope in Kandy. It has now resulted in the law enforcing authorities taking legal action about the construction and the owner of the building has made statements that all approvals were obtained from the regulatory agencies and the construction was supervised by the State Engineering Corporation.

I also highlighted the past activities of the Geological Survey Department (GSD Present GSMB) and the extensive work carried out by the Engineering Geology Section in foundation investigations as well as the landslide investigations by the highly qualified and experienced geologists with a limited staff of only 13 geologists. However in 1992 with the conversion of the GSD to GSMB both a legitimate functions of GSD namely foundation investigations as well as landslide studies was dropped but again in 2009 with the Amendments to the GSMB Act those functions were restored. It is queried whether the GSMB is now involved in these functions.

I also briefly described the various foundations and also the initiation of identifying procedures for formulation of appropriate building codes.

RECOMMENDATIONS

(1) The NBRO, which has prepared landslide hazard maps covering the 14 districts should make these maps available to local government authorities and building plans should be approved with the recommendations of NBRO.

(2) The GSMB should also actively get involved to identify landslide prone areas as well as foundation investigations for residencies and buildings.

(3) The NBRO should demarcate safe zones in the High, Medium and Low Risk areas for housing and other buildings including factories for relevant industries by foreign and local investors.

(4) The government should study the creation of effective entities that would have expertise of civil engineers, geotechnical engineers, engineering geologists, representatives from NBRO and Disaster Management Center, Ministry of Environment Central Environment Authority (CEA) etc to approve building plans for dwellings and the industrial activities. Such entities could be on a district basis.

(5) To expedite identification and appropriate building codes for construction in the three areas namely High, Medium and Low Risk areas and legislate such Codes expeditiously.

(6) Include the Ministry of Environment CEA and the GSMB to participate in the Steering Committee for developing building codes for the entire Island.

(7) The NBRO and GSMB should actively coordinate in exchange information of landslides that had occurred prior to 1992 and past foundation investigations by the GSD and create a depository of such information and data for the use of relevant agencies.

(8) The appointment of a Presidential Task Force to regulate building activity in Sri Lanka with all safety precautions and eliminate loss of life and property to achieve sustainable economic and social development.

References

1. Landslide Danger Risk Reduction Strategies and Present Achievements in Sri Lanka by R.M.S.Bandara and Padhmakumara Jayasinghe National building Research Organization Geosciences Research Vol 3 No 3 August 2018.

2. Standard penetration test –Wikipedia

3. Developing Building Code for Resilience – NBRO

(The writer is a retired Economic Affairs Officer United Nations ESCAP and former Director Geological Survey Department form 1983 10 1985 (Present GSMB) Professional Geologist for over 55 years and can be contacted at ?)