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Nord Stream’s Environmental Mitigation and Monitoring During Munitions Clearance in the Gulf of Finland
MIREMAR - Conference
Tiina Salonen, Environmental Manager Finland & Simon Bonnell, Senior Project Engineer, Nord Stream AG
More than 40,000 survey line kilometres have been sailed by Nord Stream research vessels along the pipeline route to conduct surveys and underwater investigations. The goal was to find the best possible route, avoiding dangerous objects and minimizing impact on the physical, biological and socioeconomic environment. Special attention was paid to munitions, particularly within the Gulf of Finland.
In total, over 300 munitions have been located. To ensure safe installation and operation of the pipelines, some clearance of conventional munitions was required. Within the Finnish section of the pipeline route Nord Stream conducted munitions clearance in two operations – in autumn 2009 and in spring 2010. Altogether 49 munitions were cleared in the Finnish Exclusive Economic Zone (EEZ). The clearance operations were performed in accordance with the permits granted by the Finnish authorities and in compliance with detailed environmental monitoring programmes. Nord Stream’s monitoring programmes for munitions clearance in the Finnish EEZ were designed based on the results of individual munitions-by-munitions environmental impact assessments.
The following monitoring and mitigation measures were implemented to minimize and measure the actual impacts on the environment:
- Survey of the seabed morphology prior to and after a clearance to determine the crater dimensions and assess the amount of released sediment.
- Monitoring of sediment, contaminant and nutrient dispersion due to detonations by means of pre- and post detonation vertical turbidity profiles, water sampling and sediment sampling.
- Measurement of pressure waves during detonations.
- Visual observations by qualified marine mammal observers for marine mammals and seabirds and passive acoustic monitoring (PAM) of marine mammals in the clearance area prior to detonations. Detonation was delayed if marine mammals were observed in the area.
- A sonar survey from a work boat to detect fish shoals in the clearance area prior to detonations.
- Deployment of an array of seal scrammers and a small fish scarer charge to displace marine mammals and fish from the clearance site prior to detonations.
- Visual inspection of cultural heritage sites, cables and barrels within 1 km from the detonation site prior to and after a clearance to identify any potential impact Monitoring
of third party vessels with support of the Gulf of Finland Mandatory Reporting System (GOFREP). Detonation was delayed if vessels were in the established safety zone.
- Monitoring of ‘key performance indicators’ visual observations of any marine mammal and seabird casualties after detonations, estimation of the extent of fish kill and recovery of any dead fish after detonations, visual assessment of impact to cultural heritage, barrels and existing infrastructure.
The experienced contractors used for performance and monitoring of the munitions clearance works were Bactec International, Marin Mätteknik, Noordhoek Offshore, Luode Consulting and Kala-ja Vesitutkimus. In October 2010, Nord Stream submitted the environmental monitoring report on munitions clearance in the Finnish EEZ to the supervising authorities. The results show that the actual environmental impacts of all munitions clearance operations were significantly less than predicted, confirming that Nord Stream´s environmental impact assessments were conservative.
Environmental Manager Finland
Senior Project Engineer
Nord Stream AG
Tel.: +41 41 7669191