ABSTRACT

The Angolan oil and gas industry workgroup (ACEPA-Associação das Companhias de Exploração e Produção de Angola) continues to collaborate in the development and completion of oil spill response initiatives as responsible operators and committed participants in the IMO-IPIECA Global Initiative for West, Central and Southern Africa (GI WACAF). Between 2012–2015, a comprehensive program of oil spill response planning, geodatabase development, mapping, and guides were completed for the entire coast of Angola. Low altitude aerial video surveys that combine oblique imagery and a verbal commentary record were recorded as the foundation for mapping coastal sensitivities, ESI characterization, shore zone and backshore operational definition, and shoreline segmentation. Other information added to the coastal geodatabase includes operational and logistical considerations such as land access and boat launch locations, proposed sites for staging, holding of temporary wastes, industrial and human use (fishing, recreational), and nearshore access constraints. A key aspect of the shoreline mapping effort was to build the information into a stand-alone pre-shoreline cleanup assessment technique (SCAT)-database that provides layered information for each of the 1999 shoreline segments. Digital video and high-resolution oblique aerial photos for 2400 km of coastline are geo-referenced and integrated into the GIS system with viewer software that allows the user to “fly” the shoreline. Shoreline attributes for biological, socioeconomic, and human use were used to rank 117 sensitive sites. The 45 highest priority sensitive sites were surveyed and detailed geographic response plans (GRPs) for site protection strategies and tactics were compiled into two atlases. The comprehensive coastal characterization, segmentation, and priority site protection plans provide the Angola government and oil industry with spill preparedness tools that are world-class.

1. INTRODUCTION

As part of the continual oil spill response (OSR) improvement program, the petroleum industry in Angola has developed a comprehensive OSR shoreline assessment and planning strategy that includes the creation of a set of site protection tactics and tactics sheets, including: sensitivity maps, operational and logistics maps and sensitive sites maps (Figure 1).

Figure 1.

Examples of coastal mapping products to support different purposes in oil spill planning and response.

Figure 1.

Examples of coastal mapping products to support different purposes in oil spill planning and response.

The objective of these site protection tactics was to identify recommended first response actions for key coastal locations in order to protect resources at risk and minimize potential impacts to the coastal zone. The purpose of the tactics sheets was to provide spill response management teams and field responders with a set of pre-planned recommendations for deploying OSR equipment and personnel at, or near, the shoreline. These recommendations were based on practical and realistic containment, control, or intercept options to guide the first response activities at shoreline locations.

2. METHODOLOGY

The coastal mapping and oil spill response tactics were prepared by Polaris Applied Sciences, Inc. through a joint project launched in 2011 with ACEPA members, the Angolan Ministry of Petroleum (MinPet), Angolan Ministry of Environmental Protection (MinAmb), Sonangol E&P (SNL- the state owned corporation that oversees petroleum and natural gas exploration and production in Angola), and Total Exploration and Production Angola acting as the technical coordinator. The sponsorship and execution sequence for the project was distributed into four work packages for each of two phases: north and south coastlines of Angola:

  • North (Luanda to Soyo): Initiated in July 2011 – Completed in Dec. 2013

  • South (Luanda to Namibia): Initiated in Oct. 2013 – Completed in Oct. 2015

The work packages (WP) for each part consisted of:

  • WP 1: Aerial survey/Maps/GIS

  • WP 2: Field visit to priority sites

  • WP 3: Protection plans for priority sites

  • WP 4: Intermediate and final workshops

a. Work Package 1: Aerial Survey and Preliminary Coastal Sensitivity Maps

The aerial survey consisted of geo-referenced digital video imagery of the Angolan coasts; the purpose of the field work was to generate low altitude, high-resolution geo-referenced digital imagery with a continuous commentary. That field work provides the basis for mapping, following IPIECA-IMO-IOGP (2012) best practices, of (a) the environmental sensitivity index (ESI) of shoreline types that could be impacted by oil reaching the coast, (b) the coastal character for backshore areas where operations could establish staging areas, and (c) access from land and water to the shore zone.

b. Work Package 2; Coastal Sensitivity Analysis and Field Assessments

Work Package 2 was conducted by a local team of environmental and socio-economic experts (Holisticos) that conducted the on-site validation of the sensitivity mapping including biological resources and human activities (fishery activities, plant, etc.). The sensitivity analysis and field visits also integrated data on landmines areas and identified potential logistical and staging bases. Experts engaged with the community leaders and conducted multiple interviews to capture local coastal use information (logistics, cultural, social and economic issues) at each site.

c. Work Package 3: Site Tactical Protection Plans

WP3 entailed development of site-specific detailed tactical plans to protect key sensitive coastal areas. During the development of protection plans oil spill response experts (Polaris Applied Sciences), representatives from the ACEPA members, and Holisticos conducted on-site missions whereby key sensitive sites were visited to assess the feasibility of multiple spill countermeasures in the nearshore and at the shoreline. This onsite assessment was critical for defining practical and feasible response strategies and tactics with operational instructions for the selected key sensitive sites.

d. Work Package 4: Intermediate and Final Workshop

Both phases (north and south part of Angola) included an intermediate and a final workshop. The intermediate workshop was focused on reporting overall status of the project, approve the preliminary results, and agree on the path forward. The final workshop presented the full project deliverables to all the stakeholders involved and with the objective of receiving an endorsement of the project, the priority identified sensitive sites, and protection tactics from the authorities.

3. SHORELINE MAPPING

When an oil spill occurs, cleanup operations should be guided by experts’ recommendations considering all available countermeasures as appropriate to key response aspects, including: type of coast, logistical and operational resources to respond, and sensitivity (IMO, 2005). Key elements used to define a relative scale of coastal sensitivity for each site and the project outcome include (IPIECA-IOGP, 2015a):

  • environmental sensitivity index (ESI) used for assessment defined during WP1 (Table 1);

  • integration of biological resources and socio-economic sensitivities from WP 2 into the ESI sensitive site identification;

  • consideration of site location relative to spill risks and access, including sites details defined in operational and logistics maps (WP1, WP2, and WP3); and

  • definition of the strategy to respond at each the sensitive site through drafting of site protection plans (WP3).

A key aspect of the shoreline mapping effort was to build the information into a stand-alone pre-shoreline cleanup assessment technique (SCAT)-database that provides layered information for each of the 1999 shoreline segments. The pre-SCAT database allows response managers to assess shoreline characteristics and recommended countermeasures on a segment-specific basis.

Table 1

Relative sensitivity rankings used for E2SI indices and overall sensitivity rankings

Relative sensitivity rankings used for E2SI indices and overall sensitivity rankings
Relative sensitivity rankings used for E2SI indices and overall sensitivity rankings

4. PRIORITY SITE SELECTION

As the size of the spill increases, response activities need to be selective and the spill management team must identify priority areas for on-water response and for shoreline protection. Priority protection sites were identified through a collaborative effort in consultation with Angola Ministry of Petroleum (MinPet) and Ministry of Environment (MinAmb) and environmental specialists representing ACEPA member companies. Criteria that the group used included, but were not limited to:

Human use

    Human use
  • Subsistence fishing/harvesting, commercial fishing, drinking water exposure, recreational use, industrial use

  • Public perception: shore use, parks, and esthetics

Ecological use

    Ecological use
  • Birds, vegetation, marine mammals, reptiles

Oil Residency

    Oil Residency
  • Exposure to waves, substrate, slope

  • Vulnerability

  • Modeled oil spill trajectories, past experience with spill incidents

Operational Treatment

    Operational Treatment
  • Sensitivity to clean-up treatments, habitat recovery, feasibility

Priority protection sites were identified following completion of the WP2 in which sensitivity indices were noted for each location using a simplified four-category (low, medium, high, and very high) assessment for each of: ESI, Biological Sensitivity (habitat vulnerability and sensitive populations), and Socio-economic Sensitivity (Table 1) (IPIECA-IOGP, 2015a). Measures of relative weighted sensitivity (E2SI) were quantified and the scores were used to identify the top priority sites for each project phase (north and south). Relative sensitivity was calculated as follows in agreement with ACEPA member discussions and conclusions and in which socioeconomic sensitivities were specifically weighted:

 
formula

Based on this analysis, sites ranked from Low-Med (1 – 1.4), Med (1.5 – 2.5), Med-High (2.6 – 3.4), High (3.5 – 3.9), and Very High (4.0). Results were presented to ACEPA and the Government of the relative sensitivity rankings. Sites with high and very high sensitivities were identified and agreed upon as locations for which tactical protection strategies were to be developed.

5. PROTECTION STRATEGIES

Oil spill preparedness and planning evaluates the risks (i.e. likelihood and consequences) associated with spilled oil to develop response priorities, as it is not realistic or practical to attempt to protect the entire coast from a large marine oil spill. A primary objective of oil spill response operations is to contain or control the oil as close to the source as possible in order to minimize the size of the affected area. In the case of marine oil spills, if source or near-source control is not feasible or practical, then the natural spreading processes and the effects of currents and winds can result in a rapid increase in size of the affected area and threaten coastlines and sensitive areas.

The project provided Angola with the most feasible strategies for each listed priority site, understanding that specific tactics may need to be adjusted in light of the specific and changing spill situation, weather and seasonal conditions, and availability of resources. The response options considered reflect the response strategies defined in the National Oil Spill Contingency Plan for Angola and Net Environmental Benefit (IPIECA-IOGP, 2015b) and include:

  • no action other than monitoring and evaluating the oil slick may be an appropriate option if the oil trajectory shows no key sensitive sites are at risk or if response operations involve a high safety risk for response personnel;

  • containment and recovery on water using offshore boom towed by work-vessels, skimming systems, and temporary storage on-board;

  • chemical dispersion of oil at sea to enhance the natural dispersion, dilution, and biodegradation of oil droplets into the water column; and

  • shoreline protection and cleanup when shoreline oiling is inevitable or highly probable and key sensitive sites must be protected.

Tactical protection plans were developed using information collected by field assessment teams and taking into consideration local coastal geomorphology, access, and hydrodynamics. Given that many of the highest priority sites coincide with river mouths, most sites are very dynamic and exhibit significant differences between dry and rainy seasons, both in terms of access and river discharge. Strategies defined in the tactics plans are for conditions at the time of site assessment and must be assessed for the conditions prevailing at the time of actual deployment. Each site tactical protection plan includes (Figure 2):

  • satellite and oblique aerial images for orientation;

  • ground photos to show preferred access, staging, and deployment locations;

  • site characteristics such as currents, wave action, sensitivities, and local contacts;

  • graphic depiction of booming and/or nearshore response strategies;

  • minimum resources (personnel and manpower) recommended for the defined tactics; and

  • limitations and cautionary information for responders to consider while on site.

Figure 2.

Sample of a priority site tactical protection plan.

Figure 2.

Sample of a priority site tactical protection plan.

Joint industry-government exercises have been conducted on a yearly basis to test at least one of the site protection plans: e.g. July 2012 at Barra do Dande, November 2015 for the Rio Lifune. The joint exercises typically include specific additional aspects of response, such as oiled wildlife operations (with the support of Sea Alarm), set-up of an Advanced Command Post, and shoreline clean-up operations. These annual joint exercises demonstrate the commitment of the Angola oil exploration and production operators to be familiar with, test, validate, and improve the maps and plans.

CONCLUSIONS

The joint three-year project between the oil industry and government in Angola, coordinated through the ACEPA Environmental program, has produced two OSR atlases (Luanda to north and Luanda to south coastlines), encompassing 99 detailed coastal sensitivity maps and operational/logistics maps representing 1999 SCAT shoreline segments. The pre-segmented shoreline, accompanied by a pre-SCAT database available for use through intranet sites or simply using Google Earth video viewers and imagery, allows spill response management to “visit” field sites, quickly ascertain sensitivities and operational issues for sites, and preview recommended protection strategies and tactics for the highest sensitive 45 coastal sites out of the 117 coastal sensitive sites.

Angola now possesses one of the best shoreline-defined programs in the world for oil spill response preparedness. The comprehensive mapping and database development provide industry and government with the tools to identify and plan for response, considering coastal sensitivities and priorities. As a tool within the National Contingency Plan, spill response coordination and communication becomes more effective and streamlined. As with any well-defined and implemented spill readiness program, the maps, geodatabase, and protection tactics should not be considered static information. These tools must be reviewed, tested and validated, and updated regularly.

REFERENCES

REFERENCES
IMO (International Maritime Organization)
,
2005
.
Manual on Oil Pollution, Section IV, Combating oil spills
.
London
.
ISBN: 978-92-801-4177-1
IPIECA-IMO-IOGP
,
2012
.
Sensitivity Mapping for Oil Spill Response. Good practice guidelines for incident management and emergency response personnel. IOGP Report Number 477
.
IPIECA-IOGP
,
2015a
.
Response strategy development using net environmental benefit analysis (NEBA). Good practice guidelines for incident management and emergency response personnel. IOGP Report Number 527
.
IPIECA-IOGP
,
2015b
.
A guide to shoreline clean-up techniques. Good practice guidelines for incident management and emergency response personnel. IOGP Report Number 521
.