Presentation
Update of Large-scale Mangrove Cleanup and Revegetation of 1000 ha in the Eastern Niger Delta
DescriptionPaper 206s2. The Bodo Remediation and Revegetation Project, initiated in 2015, is the largest rehabilitation effort to date ever undertaken in an oil-contaminated mangrove habitat. We provide an overview of (a) cleanup requirements, (b) cleanup methods, (c) Shoreline Cleanup Assessment Technique (SCAT) monitoring, (d) chemical sampling to meet Site Specific Target Levels (SSTLs) for government close-out, (e) waste treatments, and (f) mangrove seedling planting and monitoring. At the time of Project suspension due to community unrest at the end of 2022, ~1000 workers were active 6 days/week and more than 5.4 million work hours were completed without any lost-time injuries. Remediation restarted in January 2024.
Cleanup involved intensive flushing using ambient water to release oil sequestered in sediments ≥ 50 cm depth, surface raking and tilling, and cutting/removal of nipa palm (an exotic species that out-competes mangrove recovery). Post-treatment visual analyses by SCAT and verified by chemical analyses showed great reductions in oil contamination. 9,342 t of waste (6,032 t solids and 3,310 t liquid) were removed from 834 ha remediated to date.
Measured total petroleum hydrocarbons (TPH) from 318 samples taken in the same work area (Grid) showed a 98% median reduction of maximum values in surface sediments from 51,000 to 1,072 mg/kg and in subsurface sediments from 10,800 to 348 mg/kg. Factors for the reduction include (1) removal of oil from contaminated sediments by cleanup, (2) sediment aeration by flushing, raking and tilling aiding biodegradation, and (3) a cessation of new oiling from illegal activities in 2022. Unfortunately, 5 illegal pipeline taps occurred in 2023 which re-oiled ~60 ha of previously cleaned mangrove habitat.
Prior to new oiling in 2023, 87% of the area was remediated and 84% chemically verified. Over 300,000 red mangrove seedlings were planted covering 14% of the area. ~11% initial seedling losses occurred which were then replaced. 4.8% by area passed 6-month seedling verification of survival and growth measurements. Additional planting to reach ~2 million seedlings and 6-, 12- and 18-month monitoring surveys are planned for 2024-2026 followed by 3 years of monitoring using remote sensing.
Cleanup involved intensive flushing using ambient water to release oil sequestered in sediments ≥ 50 cm depth, surface raking and tilling, and cutting/removal of nipa palm (an exotic species that out-competes mangrove recovery). Post-treatment visual analyses by SCAT and verified by chemical analyses showed great reductions in oil contamination. 9,342 t of waste (6,032 t solids and 3,310 t liquid) were removed from 834 ha remediated to date.
Measured total petroleum hydrocarbons (TPH) from 318 samples taken in the same work area (Grid) showed a 98% median reduction of maximum values in surface sediments from 51,000 to 1,072 mg/kg and in subsurface sediments from 10,800 to 348 mg/kg. Factors for the reduction include (1) removal of oil from contaminated sediments by cleanup, (2) sediment aeration by flushing, raking and tilling aiding biodegradation, and (3) a cessation of new oiling from illegal activities in 2022. Unfortunately, 5 illegal pipeline taps occurred in 2023 which re-oiled ~60 ha of previously cleaned mangrove habitat.
Prior to new oiling in 2023, 87% of the area was remediated and 84% chemically verified. Over 300,000 red mangrove seedlings were planted covering 14% of the area. ~11% initial seedling losses occurred which were then replaced. 4.8% by area passed 6-month seedling verification of survival and growth measurements. Additional planting to reach ~2 million seedlings and 6-, 12- and 18-month monitoring surveys are planned for 2024-2026 followed by 3 years of monitoring using remote sensing.
Event Type
Paper
TimeThursday, May 16th1:30pm - 1:50pm CDT
Location291-292
Restoration