17
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011
Analysis of Infrastructure Vulnerability to Climate Change
Limon Underwater Outfall, Costa Rica
March 2011
ACKNOWLEDGEMENTS
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011
The success of this Project was made possible thanks to the following people:
Instituto Costarricense de Acueductos y Alcantarillados (AyA):
Ing. Alejandro Rodríguez Vindas Ing. Hernán Villalobos Slon Ing. Patricia Zamora Cordero Ing. Álvaro Araya García M.Sc. Ing. Luis Carlos Vargas Fallas, Dr.Sc. -- Coordinador
Instituto Meteorológico Nacional (IMN):
Ing. Nazareth Rojas Morales Ing. Roberto Villalobos Flores
Colegio Federado de Ingenieros y de Arquitectos (CFIA):
Lic. Marcela Matarrita Zeledón Lic. Cristina Carmona Lopéz Ing. Laura Solera Bonilla Ing. Freddy Bolanos Cespedes Ing. Olman Vargas Zeledón
Unión Panamericana de Asociaciones de Ingeniería (UPADI):
Ing. Irene Campos - Presidenta de UPADI
Engineers Canada:
Jeff O´Driscoll, P.Eng. Guy Felio, P.Eng. Roger Rempel, P.Eng. Darrel Danyluk, P.Eng Heather Auld David Lapp, P.Eng
Without the hard work and voluntary efforts of this group of professionals, the completion of this important project would not have been possible.
This project was supported through a financial contribution from the Government of Canada.
Substantial in-kind professional days were contributed by the members of the Costa Rica Project Team (Colegio, Aya and IMN) and from the Canadian Project Team from Engineers Canada.
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011 Page 2 of 17
Introduction
The Instituto Costarricense de Acueductos y Alcantarillados de Costa Rica (AyA), the Instituto Meteorológico Nacional de Costa Rica (IMN) and the Colegio Federado de Ingenieros y de Arquitectos de Costa Rica (CFIA), under the guidance of Engineers Canada, developed a vulnerability analysis to climate change of the Underwater Outfall of the city of Limon, Costa Rica. The analysis, conducted using the PIEVC Engineering Vulnerability Protocol, integrated the sewer system, pumping system, wastewater pre-conditioning plant and the controlled outlet system into the sea (underwater outfall).
The infrastructure under analysis is located on the Caribbean coast of Costa Rica, it provides service to the
central area of the city of Limon and it is between 10 and 20 years old (outfall – 10 years and sewers - 20 years).
The main purpose of this study was to perform a risk assessment of the Wastewater Treatment System of Limón (Costa Rica) to climate change starting from the selection of parameters describing the climate and meteorological events typical of the geographical area where the infrastructure is. The result of this analysis was the prioritisation of the actions to be carried out by the entity in charge of this infrastructure (AyA) taking into consideration climate change based risks (nature and intensity of events).
The analysis was made using the PIEVC Engineering Protocol, Version of April 9 2009 as guideline.
The project was carried out from August 2010 to March 2011 and it considered climate change effects up to year 2040.
This project involved a multidisciplinary team which involved about 13 engineering and meteorology professionals. IMN provided support related to meteorological information, analysis, modelling and projection of climate behaviour. Since AyA was the original designer of the project and it is at present the system owner and manager, it provided support regarding engineering design and specific operational aspects. . The local implementation of the PIEVC Engineering Protocol and general coordinator of the project was CFIA. Engineers Canada worked as an external advisor in the use of the Protocol and on meteorological aspects.
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011 Page 3 of 17
Definition of the Project
The infrastructure for the project was chosen because of the availability of information and social considerations. The combination of these factors made the vulnerability analysis to climate change of the Limon underwater outfall a high priority project.
On one hand, the application of the Protocol requires broad information on the design and operations of the infrastructure to be analyzed. The underwater outfall, pumping and sewer system, all together, were recently built (no more than 20 years ago). Technical and design specifications of the main infrastructure elements were therefore available, which was not the case in other project identified.. In addition, the system operational logs were available for the outfall, which provided essential information to determine the performance of the system regarding certain climate events.
Likewise, regarding meteorological information, there was data available from a meteorological station near the study site. Furthermore, global and regional models were also available - which, together with local information, represented enough data to carry out the respective analysis.
Limon is one of the most socially depressed cities in Costa Rica; the central Government has defined a series of important projects for this area with the purpose of investing capital and thus create jobs and social welfare. However, these projects of national importance (Limon Project – City – Port and New Port of Limon) require a wastewater management infrastructure able to handle the new loads they will be subjected to. This is the strategic aspect of the underwater outfall system and which forces to take into consideration climate change aspects so that its service level reaches optimal conditions for future development.
Finally, as previously mentioned, the city of Limon has critical social conditions that make it susceptible to climate impacts (coastal city and high criminality index). Therefore the identification of infrastructure elements vulnerable to climate change provided by the application of the Protocol will allow limiting the negative social effects that would occur in case of extreme climate events.
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011 Page 4 of 17
Climate Factors
The project team originally defined thirteen climate factors to be considered in the analysis. However, upon extended analysis and discussions, it was concluded to use a reduced group of factors. The final list of climate factors is as follows:
Parameter Application in the analysis Relevant effect on the infrastructure
High temperature
Determine variation in water consumption given that higher per capita water consumption involves higher returns to the collection system.
Reduce the system treatment capacity upon early reaching the design value.
Impact on the work conditions in the EPA.
Risks of accidents and operation shutdown of EPA.
Sea breeze
The breeze contains salinity that may damage the equipment and electric, telemetric, control and communication installations because of increased corrosion.
Failure of control system resulting in operation shutdown of EPA and of underwater outfall.
Intense rain Intake flow to EPA increases due to storm drain connections.
Operation shutdown of EPA and of underwater outfall.
Flooding rain
Flooding of urban area when hydraulic capacity of the storm drain system is exceeded and damage caused from flooding of EPA.
Operation shutdown of the EPA and of the underwater outfall. Risk of damage to the equipment, infrastructure and operators.
Lightning
Damage to electromechanical equipment and possible effects on the personnel of EPA.
Failure of the control system resulting from operation shutdown of EPA and of the underwater outfall.
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011 Page 5 of 17
Power supply failure at EPA and at the pumping stations.
Wind: speed and direction
Wind speed and direction component determines the direction of sea currents in the discharge area of the outfall diffusers.
They jointly determine the spreading of the outfall plume in accordance with the design taking it far from the shore or towards the shoreline.
Tidal waves
Possibility of extreme hurricane winds and waves in the study area where the EPA and the underwater outfall are.
Operation shutdown caused by waves reaching the EPA level and flooding the operation area. Damage to the building infrastructure.
Stability of the underwater outfall piping and anchoring.
Hurricane
Determine the possible infrastructure damage and overcharge– heavy rain and effect of wind and waves.
Possible damage to infrastructure under poor urban drainage conditions, elevation of stations and equipment considering the effects of additional loads.
Analysis period
The work team defined the assessment term in 30 years (2040). This is based on the remaining useful life of the sewerage system, the pre-conditioning station and the underwater outfall without significant rehabilitation work.
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011 Page 6 of 17
Infrastructure components
The infrastructure elements for this project are defined in the following table.
Element Subelements
Sewage collection system
Connections Siphons Networks Local sewers Main collectors Manholes
Pumping stations
Coastal mini-stations Land mini-stations Centrifugal stations Submersible stations
Pre-conditioning station
Building Ventilation system Gates, screens, Parshal channel, interconnection channel Milli-screens Worm screw, baskets, hoisting system, transportation Water tank Pumps Overflowing structure Accessories in pumping line Control board Electrical plant
Underwater outfall
Piping Diffusers Closing valve Anchoring
Wave retaining wall
Personnel Wastewater collection system Pre-conditioning station Underwater outfall
Telecommunication equipment
Telephones at the pre-conditioning station Telemetry Radios Internet text messaging
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011 Page 7 of 17
Climate change considerations and modelling performed
In order to forecast potential climate changes, a series of studies were carried out based on the following aspects:
• Climate description of the area
• Definition of climate and meteorological factors giving rise to the present vulnerability of the infrastructure
• Present occurrence probability according to historic records
• Future occurrence probability by means of model-generated projections for the 2011-2040 period
• Critical analysis of climate projections for those parameters with missing records to allow modelling
The following information sources for the climate change vulnerability analysis of the infrastructure were used:
• Limon meteorological station record (81-003)
• Flooding records (database of the Sistema de Inventario de Efectos de Desastres – System of Inventory of Disaster Effects)
• Records of Hurricanes (Central American Probabilistic Risk Assessment)
• Wave modelling: WAVEWATCH III Model, version 2.22 of NOAA
• Meteorological reports of IMN
• Operation Log of the sewage treatment and collection system (AyA)
• Climate related literature produced and edited by IMN
• Scientific publications
• Regional climate models (MCR) and application to local conditions by means of dynamic Downscaling Model using special and temporal high resolution MR PRECIS. Results used were those of MG HAdAM3H and sea surface anomalies of model HadCM3. (space resolutions– 50 km, temporal resolutions – annual)
• Global models generated by CCCSN, based on the results of the 4th report of IPCC.
For the cases where modelling was not available, the analysis used correlations and trend analysis, scientific publications, information on the web related to climate change and publications of IPCC.
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011 Page 8 of 17
Occurrence probability
Based on the analysis described above, and as a result of discussions held with the work team, the following group of present and future probabilities were established for the different climate factors considered. It should be noted here that, besides this general analysis, an alternate methodology of probability determination was developed. Events were therefore divided in extreme and recurrent events.
Parameter Present probability
Future probability
High temperature
5 6
Sea breeze 7 7
Intense rain 1 2
Flooding rain 1 2
Lightning 2 2
Wind: speed and direction
1 2
Tides (wave) 1 2
Hurricanes 0 1
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011 Page 9 of 17
The following are the tables of modified probability (present and future) for extreme (Ext) and recurrent (Rec) events:
Type Parameter
Probability
present future
Rec High temperature 4 5
Rec Wave 1 2
Rec Sea breeze 2 3
Rec Lightning 2 2
Type Parameter
Probability
present future
Ext Flooding rain 4 5
Ext Intense rain 6 7
Ext Hurricane 1 2
Ext Wind 3 3
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011 Page 10 of 17
Training, discussion and follow-up workshops for the application of the PIEVC Engineering Protocol.
For the implementation of the project under consideration, three workshops were held. The first one, in August 2010 (three days), was the initial training for the Costa Rican work team. This workshop also included a visit to the project site.
The second workshop focused on the discussion of the risk analysis matrix and was held for three days in December 2010.
The last workshop took place in March 2011 to review the results and global analysis of the project. During this workshop, the analysis results were presented to government entities and professionals from other organisations and it included a site visit. This was a five-day workshop.
Furthermore, during the course of the project, 7 telephone conferences were held with the specialized support team of Engineers Canada and the work team of Costa Rica.
Risk tolerance thresholds
The tolerance thresholds provided under the Protocol were used for this project. These thresholds proved to be appropriate for risk rating. However, the system operator (AyA) included in its recommendations a slight downward variation of the high risk threshold. Thus, the following are the risk thresholds used:
Risk calculation for main interactions found
Based on the probabilities obtained for the climate factors rated as recurrent and extreme, severity (gravity of impact) values were assigned and the risk equation shown below was applied:
R = P x S
Where:
R = risk
P = probability
S = severity (gravity of impact)
Low Risk
•Less than 12•Excluded for further
analysis
Medium Risk
•From 12 to 35•Kept for further
analysis
High Risk
•More than 35•Go directly to
recommendations
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011 Page 11 of 17
The respective results were obtained after applying the risk equation for each one of the defined interactions (climate event + infrastructure component). Risk rating was made using the above established thresholds.
The following table shows the matrix of the main risks found. It must be noted here that the matrix includes present and future risks (RA and RF).
It follows from the analysis performed that from the 138 interactions there is none of high risk. There are 41 interactions that currently have a medium risk which will increase to 54 for future risks. It follows from the above that there are presently 97 low risk interactions decreasing to 84 in the future. The charts below summarize present and future risks.
Infrastructure Component Climate Parameter PA PF G RA RF
Asis Esna, 4 5 7 28 35 Pacuare 2 4 5 7 28 35 Gates, grids, Parshall channel, interconnection channel 4 5 7 28 35 Networks, sub sewer, sewage system 6 7 5 30 35 Land mini-stations 6 7 5 30 35 Asis Esna, 6 7 5 30 35 Gates, grids, Parshall channel, interconnection channel
6 7 5 30 35 Networks, sub sewer, sewage system 4 5 6 24 30 Coastal mini stations 4 5 6 24 30 Coastal mini stations 6 7 4 24 28 Pacuare 1 6 7 4 24 28 Pacuare 2 6 7 4 24 28 Water tank 6 7 4 24 28 Land mini stations 4 5 5 20 25 Pacuare 1 4 5 5 20 25 Water tank 4 5 5 20 25 Overflow structure 4 5 5 20 25 Power plant Sea breeze 3 3 7 21 21 Pumps 6 7 3 18 21 Overflow structure 6 7 3 18 21 At EPA High temperature 4 5 4 16 20
Intense rain
Flooding rain
Flooding rain
Intense rain
Flooding rain
Intense rain
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011 Page 12 of 17
Present risk Future risk
Vulnerability Assessment
A series of calculations were made to determine the system wastewater collection, treatment and disposal capacity in Limon.
The analysis of the intense rain shows that the maximum capacity of sewage is 91,1 l/s and that there are illicit connections from houses roofs to the sanitary sewage system. Modelling, using a light rain of 16 mm/hr of intensity, shows that the system will collapse with only 4% of the houses’ roofs connected to the sewage the system. However, the sewage system does have capacity to treat the wastewater presently generated and what will be generated in the future if the illicit connections made from houses’ roofs to the sewage system are not disconnected.
The flooding rain analysis shows that for an extreme event identified in the system log (intensity of 106 mm/hr) the storm drainage system has enough capacity for the water flow generated. However, in this specific event the analysis showed that many outlets were clogged and this kept rain water from entering into the storm drainage system. It has been verified that the storm drainage system has enough capacity to handle rain but it is vulnerable to future conditions. It should be noted here that the analysis of the storm drainage system was done because there are interconnections between the sanitary and the storm systems.
Regarding wind effects, it was determinedthrough modelling of the contamination plume, that the outfall has appropriate capacity and that it is unlikely low speed current conditions with easterly winds will occur. This means that the underwater outfall has enough capacity to handle wind effects.
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011 Page 13 of 17
General discussion
The analysis performed to determine the vulnerability of the infrastructure and the subsequent engineering analysis show that the two main events that would affect the wastewater collection, treatment and disposal system of Limon are intense rain and flooding rain.
The following are the systems that will be mainly affected:
• Pumping system (coastal and inland systems)
• Gates, screens, Parshall channel and interconnection channel (pre-conditioning station)
• Sewer systems (collectors and sub-collectors)
Recommendations
• It is considered that the application of the PIEVC Engineering Protocol to the Sewage System of the city of Limón has allowed addressing in a systematic way the climate change issue, starting from a broad climate analysis.
• The best results in the Protocol application were obtained for parameters in which there were load thresholds validated by the occurrence of events (recorded in the operation logs) with climate records.
• For these thresholds, the infrastructure that at present is being affected in terms of loss of capacity or operation shutdown was identified.
• The adaptation measures that require immediate action, even without having the extreme conditions resulting from climate change impacts were also identified.
• Aspects that require more detailed study, improvements to be made in equipment and better information records were also identified.
• For future applications of the PIEVC Engineering Protocol to the national infrastructure, institutions must ensure the participation of officials according to workloads arising out of the protocol application, in order to secure an appropriate process and optimum knowledge transfer.
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011 Page 14 of 17
• An alternative way of applying the protocol – through the retention of consulting services (Case study of Claireville and G. Ross Lord Dams and Metro Vancouver Sewerage) may result in time savings for the projects but will not achieve knowledge transfer.
• The Risk Management issue must reach the level of “National Project”, in order to secure joint leadership and participation of the institutions in charge of the infrastructure, and especially those that generate climate related data.
Final comments
Knowledge, management and application of the PIEVC Engineering Protocol
The CFIA, AyA and IMN, with the support of Engineers Canada, carried out the project of applying the PIEVC Engineering Protocol to a given infrastructure. The three entities in Costa Rica reported that they had never worked as a team before the project started and this in itself is one of the milestone achievements of the project. All along the application process the general targets defined in the original proposal were achieved. Thus:
• It was determined the vulnerability to climate change of the wastewater collection, treatment and disposal system of the city of Limon.
• A better understanding was achieved of the need for climate information, the form this information is requested to the corresponding institution and the way it must be submitted to the technical team.
• Expertise in the use and applicability of the PIEVC analysis process was acquired. • The direct or indirect effects of climate change to the infrastructure under study were
established through the establishment of interrelations between the infrastructure components and the climate factors.
• Priority actions to adapt the existing infrastructure to present and future climate events were identified.
• Climate information gaps that shall be filled in the future in order to carry out a second cycle of engineering analysis for this project were identified.
Analysis of Infrastructure Vulnerability to Climate Change Executive Summary Limon Underwater Outfall, Costa Rica March 2011 Page 15 of 17
• An operational structure that integrated all the parties involved (system operator, owner of the system, meteorological specialist, project manager, among others) was established and that, we hope, will be applicable to other projects.
Vulnerability to climate change of the wastewater collection, treatment and disposal system of the city of Limón.
In accordance with the risk analysis performed of the City of Limon’s wastewater collection, treatment and disposal system, it is determined that the system has enough capacity to handle the projected effects of climate change over the 30 year assessment period.
