Transcript Barrier Wall Performance

Sheen
Characterization
2009 Data and Observations
July 2010 Progress Meeting
McCormick & Baxter Superfund Site
Portland, Oregon
Sheen Characterization
Presentation
• Objectives – Identify Nature of Sheen
• Previous Investigations Summary
• 2009 Sheen Characterization
Activities and Results
– Chemical
– Biological (Dr. Anne Camper)
• Conclusions and Recommendations
2007 Sheen Investigations
• Focused on area
surrounding large
Reactive Core Mat and
shoreline in the TFA –
June
• Time-series sampling
in September
2008 Sheen Investigations
•
•
•
Sheen with water, adjacent surface
water, and sediment with sheen were
collected from 4 locations along the
shoreline
Concentrations of low molecular
weight similar to those in surface
water were detected in the sheen
with water
Sheen appeared blocky and
iridescent in appearance; did not recoalesce upon probing
2008 Investigation Tasks
• SPME, sediment cores, and porewater samples
• 10 co-located flux chamber samples
• Biodegradation study on cores
• Survey of locations and rates of ebullition through tidal cycle and
season
• Continued shoreline documentation of sheen
• Sampling of sheen (July 2008)
Sampling Locations
Overall Conclusions 2008
• Organoclay retains its full sorption capacity – both OC mats and
granular
• Permeability remains near fresh organoclay (similar to sand)
• HEM fraction higher in ET-1 – likely reason for enhanced
microbial activity in bulk granular organoclay
• Porewater concentrations generally below comparison criteria
• No evidence that sheens are caused by creosote migrating from
beneath the cap
Overall Conclusions 2008 (cont.)
• Sediment concentrations in cap below cleanup
goals
• Sheen concentrations comparable to ambient
surface water
• Ebullition is a pathway for contamination – however,
below comparison criteria with exception of low level
cPAHs thought to be particulate matter
• Sheen origin remains unknown
2010 Characterization Activities
• Shoreline Sheen
Observations
• Sheen Simulation
with Site Product
• Sheen Sampling
– Chemistry
– Biological
Sheen Simulation
• Method with pipette and pan
• Sheen was sampled similarly to the field sampling – by passing a
Teflon® net and pad through the sheen (ASTM D4489)
More Photos
Sheen Sampling
Methods
• Sheen
– Teflon nets and pads (ASTM 4489)- used to collect sheen
samples from surface water. Each pad/net used daily at same
location for four days to obtain sufficient sheen on pad/net.
– C-18 cartridges – know volume of sheen with water was pumped
through C-18 cartridge.
• Ambient Water – peristaltic pump
Samples sent to Pace for Analytical and Dr. Anne Camper/MSU for
biological analysis
Sampling Locations
Chromatograms
Actual Site Sheen - TFA
Simulated Sheen
<0.59 mg Total PAHs
Blank Net
25,000 mg Total PAHs
0.918 mg Total PAHs
Analytical Results
Teflon® Net/Pad
• Iron/Mg was concentrated in sheen (54X - sheen/9X water)
• PAHs were not detected in sheen (exception: fluorene
was estimated in 2 samples)
C-18 Method
• Method comparable for water and sheen
• PAHs (acenaphthene, acenaphthylene, fluorene, and
naphthalene) detected at slightly higher concentrations
in water than in sheen samples.
Chemistry Conclusions
• Collection method robust
• Chromatograms demonstrate sheen is very different
from a site product sheen
• Iron concentration in sheen (in creosote sheen –
chromium is the highest concentration metal -0.11XMg)
• PAH concentrations detected with C-18 cartridge
reflective of water concentrations (nets and pads will not
sorb dissolved PAHs from water)
Microbiology Methods
• Samples of parallel water and mesh
• Heterotrophic plate counts
• Extracted DNA and population analysis
• Microscopy
Heterotrophic Plate Counts
• Water counts from 10^4 to 10^5/ml
• Mesh counts from 10^6 to 10^8/mesh
Sheen had associated bacteria
• No major difference between two samplings
• No differences in colony morphologies
Denaturing Gradient Gel
Electrophoresis
• Targeted 16S rDNA
• Each band ~ one species
• No substantial differences
TFA2
8-13-09
Water
Mesh
Microscopy
• Staining methods to determine if sheen was
created/stabilized by bacteria
• Emphasis on morphologies typical of iron
oxidizing bacteria
• Mesh samples inconclusive for bacteria;
sheen not formed by bacterial biofilms or
iron bacteria
Overall Conclusions-Sheen
Characterization
• 2009 characterization work support the previous
sheen sampling results, porewater sampling
results, and core sampling results from 2007
and 2008
• General shoreline sheen in late summer/early
fall are not due to sheen migrating through the
sediment cap
• Sheen appears to be a non-biological iron
concentration