Lecture 10 Flashcards
(25 cards)
what is Saglek Bay, Labrador?
- inuit have inhabited the area for ~3800 years
- the nearest community is Nain, 225km South
- known for its rich harvesting
what is LAB-2 Saglek?
- saglek was the site of US air force military radar station from early 1950s to early 1970s, part of the pinetree line
- currently a north warning long range radar facility operated for the north warning system office of DND since 1980s
what are the historical sources of PCB contamination in saglek bay?
- Prior to construction of the new site, structures remaining from the old station were demolished, burned and then buried on site spreading PCB contamination
- Antenna Hill which housed a set of large
tropospheric antennae and some support structures that contained a variety of electrical
equipment that utilized PCBs
what happened in saglek bay in 2014?
DND reported that the largest environmental cleanup in canadian history was now finished
- the DEW line remediation project cost the government $575 million and saw the removal of toxic
waste from 21 former radar stations across the Arctic.
what were the results of an environmental assessment at saglek bay?
assessment identified 3 areas of PCB contamination in excess of 50ppm:
- site summit: site of old radar station
- antenna hill: site of old communications radar
- beach landing/staging area: site of old maintenance garage and laydown area for ‘junk’
there’s evidence of PCB migration to the ocean and accumulation in bottom feeding fish species, shorthorn sculpin
what happened with soil that had PCB concentrations greater than 50,000 ppb?
- they were removed from site summit and antenna hill
(50,000 ppb is the CEPA PCB cleanup guideline)
what was the PCB criteria for the beach area?
set lower to 5000ppb as it was a direct input source to the marine environment
what was the remedial action/communication plan for saglek bay?
- establishment of stakeholder group (1997): primarily DND, labrador inuit, environment canada, newfoundland environment, fisheries and oceans
- regulatory requirement to remediate CEPA soils
- remedial plan: excavate all CEPA soil prior to treatment, interim storage of soil followed by PCB storage regulations (regulations were not designed for large volumes of soil)
what is the summary and actions of PCB concentrations in saglek bay?
- CEPA (>50ppm) = approximately 4690kg of PCBs = stockpiled and shipped off site
- 5-50ppm = 890kg of PCBs = secured at antenna hill
- contaminated marine sediments = 260kg of PCBs = risk based assessment
what is the site status of the marine area at saglek bay?
director general of the environment’s responsibility
what is the site status of the beach/beach area?
- left ‘as is’ after excavation complete in 1999
- 2% (around 60kg) of PCBs remain (could not be excavated)
what is the site status of the staging area?
- contaminated soil and debris stockpiled during excavations (1997-1999)
- remediation of stockpiled soil and debris (2004)
- work areas returned to ‘pre-work’ conditions
- disposal area created (oversized material, <5ppm), estimate of 8kg of PCBs in disposal area
what is the site status of antenna hill and site summit?
- excavations of CEPA soil completed and capped with clean soil (1999)
- monitored since 1999
what are the commitments to stakeholders?
- ongoing studies on PCBs in the surrounding environment
- human health risk assessment
- sediment transport model
- ecological risk assessment
- long term monitoring (monitor ecosystem recovery)
what were the outcomes of the human health risk assessment?
- arctic char levels were deemed safe for human consumption
- some ringed seals had high PCB concentrations in blubber
- overall food basket risk assessment advised against local harvesting
what did the sediment transport model reveal?
the direction of sediment movement into deeper regions of the bay
how do we evaluate the sediment concentration?
- problem: delineation of sediments in saglek bay revealed concentrations ranging from background (0.4ppb) to over 50,000ppb
- purpose: to identify the extent to which the PCB contaminated marine sediments represented an ecological risk as they existed from 1997-1999
in theory, there are two approaches to evaluate the ecological significance of contaminated sediments:
- criteria (guideline) based approach
- risk-based approach
what are 4 reasons for choosing a risk based approach over a guideline based approach?
- real world differs from a controlled lab
- marine environment is a traditional harvesting area for local inuit
- species tied to benthic environment at saglek were not used in derivation of the canadian sediment guideline created by CCME
- special site characteristics which increase vulnerability to contaminants accumulation and possible adverse health effects
what were the ERA endpoints for benthic invertebrates?
decrease in abundance or composition due to toxicity
what were the ERA endpoints for bottom feeding fish?
- decrease in abundance or production due to toxicity
what were the ERA endpoints for fish eating seabirds?
- decrease in abundance or production due to toxicity
how was endpoint one: benthic invertebrates tested?
- 22 sites within saglek bay selected for analysis
- 6 sediment grabs were collected at each location and subsampled for toxicity testing
- less than 0.5ppb in reference zones and the highest concentration was 7000ppb in immediate subtidal zone
what were the 3 benthic invertebrate measurement endpoints used?
1) amphipod toxicity test
2) microtox toxicity test
3) benthic community survey
