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TPH Risk Evaluation at Petroleum Contaminated Sites

Written by Abimbola Baejo, Staff Reporter

This report is from a webinar
conducted by the Interstate Technology and Regulatory Council (ITRC) Total
Petroleum Hydrocarbon Risk Evaluation Team and the US EPA Clean up Information
Network on the 19 of June 2019. https://tphrisk-1.itrcweb.org/

The webinar was made to facilitate
better-informed decisions made by regulators, project managers, consultants,
industries and stakeholders, on evaluating the risk of TPHs at petroleum contaminated
sites.

What is TPH?

In environmental media, crude oil and individual refinery products are typically characterized as TPH. They are made up of hydrocarbons along with other elements such as nitrogen, oxygen, sulphur, inorganics and metals. The refining process generates various commercial products such as kerosene, diesel, gasoline; with over 2,000 petroleum products identified. These products are made up of various number of carbon atoms which may be in straight or branched chain forms.

TPHs can be found in familiar sites such refineries, air- and seaports, offshore sheens, terminals, service stations and oil storage areas. Hydrocarbons can be broadly classified into aliphatic (e.g. alkanes and alkenes) and aromatic (e.g. benzene and naphthalene) hydrocarbons.

For TPH assessment at contaminated sites, relevant properties to consider are water-solubility, polarity, boiling point and evaporation ranges. Aliphatic hydrocarbons are non-water soluble, non-polar, have lower boiling points and are more prone to evaporation compared to the aromatic hydrocarbons. At a typical petroleum contaminated site, substances such as fuel additives (such as oxygenates), naturally occurring hydrocarbon components, metabolites from degraded substances and individual petroleum constituents (such as BTEX).

TPHs are made up of various constituents with similar or different carbon atoms. This means that there is the challenge of analytically separating TPH constituents in a risk assessment context since hydrocarbon constituents from a specific range of carbon atoms could be a challenge, especially if they are diesel, jet fuel or petroleum. With this knowledge, one can conclude that bulk TPH analysis, though a good screening method, is not a suitable method for TPH risk evaluation. A good way of summarizing this is in shown below.

Chromatograms of samples from the same analysis. Sample 1, 2 and 3 are Gasoline, Diesel fuel and South Louisiana Crude respectively. The analysis method used was EPA method 8015. (Image courtesy of ITRC, 2019)

The same concentration of TPHs in
different areas of a site might be composed of different products; which in
turn, may present different risks to the ecological environment. Therefore, we
can safely say that TPH is:

  • a
    complex mixture with an approximate quantitative value representing the amount
    of petroleum mixture in the sample matrix
  • is
    defined by the analytical measure used to measure it, which varies from  one laboratory to another.
  • is
    either made up of anthropogenic products freshly released into the environment
    (or weathered) or natural products from ecological activities
  • not
    totally of petroleum origin and may simply be detected by the analytical method
    used.

This definition then enhances the
challenges faced with TPH risk assessing such as dealing with continual changes
in TPH composition due to weathering brought on by site-specific conditions,
trying to analyze for hundreds of individual constituents in the mixture and
having limited data on the toxicological effects of the various constituents.

To overcome the challenge of drawing erroneous conclusions about a contaminated site therefore, the project manager should not focus only on TPH individual constituents when making remedial decisions, which mostly degrade before the toxic fractions do, but should collect samples for both fractions and individual constituents. A detailed Conceptual Site Model (CSM) is suggested as a good guide in assessing TPH risks as it shows where the the remediation focus should be, away from human exposure routes; and periodic revision of this CSM will assist in documenting contaminant plume changes and identifying areas with residual contamination.

TPH ANALYSES

Due to the complexity of TPH mixtures,
analytical methods should be selected based on the data quality objective,
application of the results (whether to delineate a contaminated area or to
conduct a risk assessment), the regulatory requirements, the petroleum type and
the media/matrix being tested. As long as the method is fit for its purpose and
cost effective. TPH mixtures require separation and most laboratories use GC as
a preferred method as it separates I the gas phase based on its volatility.
Since it is difficult to evaluate risk for a TPH mixture, most methods suggest
separation into fractions. Guidelines are usually provided on what methods suit
a purpose best by governmental records but if such records are inaccessible,
getting information from seasoned chemists is the best option. 

Prior to TPH mixture separation,
removing method interferences, such as non-petroleum hydrocarbons, is ideal for
more accurate results. US EPA method 3630C describes the use of silica gel to
remove polar, non-PH and naturally occurring compounds from the analysis. This
gel cleanup leaves only the hydrocarbons in the sample which is the analyzed
for bulk TPH. The silica gel used is a finer version  of the common ones found in clothing
accessories and using it in a gel column setup is most effective at removing
non-hydrocarbons. Quality controls using laboratory surrogates is also advised.
Cleaning up prior to bulk TPH analysis is ideal in determining the extent of
hydrocarbon impact, biodegradation locations and knowing where to focus
remediation activities.

Silica gel can also be used to fractionate samples into aliphatic and aromatic fractions; and the technique can be applied to all matrices. However, alternative fractionation method is suggested for volatile samples. The eluted fractions are then run on the GC instrument  to obtain information on the equivalent carbon ranges. It is good to note that fractionation is more expensive compared to bulk TPH analyses as it provides a more detailed information, removes non-hydrocarbons from the analyses and raises reporting limits.

Chromatograms provide information such as sample components, presence of non-hydrocarbons, presence of solvents, presence of non-dissolved hydrocarbons, poor integration and weathering. They can also be used to compare samples with interferents as shown below:

Chromatograms from the same sample collected at different times showing an unweathered sample (above with red asterisk) and weathered samples (below). (Image courtesy of ITRC, 2019)

Chromatograms from the same TPHd contaminated groundwater sample comparing analysis before silica gel cleanup (left image, TPHd=2.3mg/l)) and after silica gel cleanup (right image, TPHd = <0.05 mg/l). The hump centered around the C19 internal standards and the non-uniform peaks indicate the presence of non-hydrocarbons, as confirmed after silica gel cleanup. (Image courtesy of ITRC, 2019)

Methods used to analyze TPH in
contaminated samples can yield different results when compared with one another,
as well as the presence of non-petroleum hydrocarbons being quantified as TPHs.  To overcome this, use field methods such as
observed plume delineation during excavation, PID analysis of bag headspaces
and oil-in-soil analysis for semi-volatiles, as well as the CSM to get valuable
information, before using laboratory methods and chromatograms to confirm
conclusions made from the field observations.

ENVIRONMENTAL FATE OF TPH

Determining the environmental fate of
TPH is critical to understand how the vapor composition and dissolved plumes
differ from the source zone  due to partitioning
and transformation processes. TPHs partition to vapor as well as water. When
partitioning to vapor, the smaller hydrocarbons are more volatile and therefore
dominate the vapor composition. A more complex process is involved when TPH is
partitioning to water because the smaller hydrocarbons are more soluble, based
on their molecular structure. Aliphatic hydrocarbons are less soluble compared
to the aromatics which are likely to dominate the soil water fractions. TPH
weathering on the other hand, contributes exceedingly to TPH mass reduction in
the environment may be due to aerobic or anaerobic biodegradation processes in
the soil or photooxidation processes; to generate petroleum metabolites which
may be further degraded. Petroleum metabolites produced have oxygen atoms in
their molecules, making them polar in nature and partition preferentially in
water. These metabolites are measured primarily via TPH analysis without silica
gel cleanup, and are identified using chromatogram patterns, understanding the
solubility of the parent compound and using CSMs maps. most TPH components
found in groundwater are metabolites and their toxicity characteristics are
usually different from their parent compounds.

The use of TPH fraction approach with
fractionation methods is considered best for assessing TPH risks because it
provides accurate hydrocarbon quantitation along with the toxicity values as
well as the chemical or physical parameters involved. To determine the
fractionation composition in a TPH, the fuel composition and the weathering
conditions are determined.

For example, Non-Aqueous Phase Liquid (NAPL) undergoing weathering process overtime will first have the mobile hydrocarbons partition out while at the same time, further NAPL depletion will occur with the generation of metabolites  by continual biodegradation. There is the migration of vapor plumes to thin zones around the NAPL as well as heavily impacted media due to aerobic degradation in the unsaturated zone. Contaminated ground water could be made up of mostly small aromatic hydrocarbon fractions, some small aliphatic hydrocarbon fractions as well as medium aromatic hydrocarbon fractions.

Along a groundwater flow path, a differential fate affects the TPH composition which in turn affects the exposure.

Fate of TPH composition in Groundwater. (Image courtesy of ITRC, 2019)

TPH
 composition changes along the path of
flow  could be due to:

  • – differential transport and sorption of individual hydrocarbons,
  • – different susceptibilities of hydrocarbons to biodegradation and
  • – different redox zones along the path of flow.

On the other hand, bulk TPH composition show highest hydrocarbon concentrations near the surface and diminish downwards along the gradient while the metabolites generated via biodegradation, increase in concentrations downgradient of the source area and highest parts of the dissolved hydrocarbon plume. Over time, metabolite concentrations may increase near source, shifting the apex of the triangle to the right.

ASSESSING HUMAN AND ECOLOGICAL RISK
FROM TPH

TPH risk assessment is done in three
tiers where the first tier is a screening-level assessment; and the  site-specific assessment comprises the second
and third tiers.

Screening-level assessment involves
preliminary CSM development (source characterization and initial exposure
pathway assessment) and initial data review (regulatory requirement evaluation,
existing TPH data review).

Site-specific assessment involves more
detailed assessment which includes the identification of data gaps from data
obtained from screening-level assessment and collecting additional field data
such as bulk TPH  data and chromatograms,
indicator compounds and fractions, and CSM updates.

An environmental risk assessment may
not be necessary if viable habitats are absent at the TPH contaminated site, if
no contamination is found below the root zones and below the burrowing zones of
ecological receptors; and there is no potential release of the contaminant to
nearby viable ecological habitats. However, risk assessment is necessary if it
is a regulatory requirement, if the screening level values are available and if
the available levels are appropriate for the site conditions or the type of
release.

Site-specific assessment, therefore,
is required when screening levels are lacking or exceeded; and at complex sites
with multiple media, sensitive habitats and receptors. Such an assessment  should focus on direct exposure,  contaminant bioaccumulation and toxicity
assessment which evaluates the ecological risk, physical and chemical toxicity
effects and the metabolites produced.

STAKEHOLDER CONSIDERATIONS

The stakeholders involved are affected
property owners or communities with regard to the risks that are specific to
petroleum contamination as measured by TPH. Communicating with them requires sensitivity
and a timely approach  in order to help
them understand facts and clear their confusions and concerns about TPH risk
assessment. This could be done through factsheets, posters, outreach meetings,
websites and internet links on TPH information. There should be public
notification prior to sampling as well as the provision of post sampling TPH
data results with appropriate explanations.  Technical information and public health issues
should be translated and communicated in a format that is easily understood by
the general public.

Similar sensitivity should be shown to
other TPH assessment impacts to public property, including property value,
access, and private property rights. A major concern is the fear of property
devaluation as a result of possible residual TPH and a Monitored Natural
Attenuation (MNA) remedy. The fears can be effectively addressed by explaining
why the selected remedy is protective and effective (especially MNA), describing
how all activities are done with agency oversight (that is local organizations
and government agencies); and individual property owners concerns  should also be addressed.

Overall, a successful TPH risk
evaluation project requires an appropriate technical approach, careful review
of analytical methods chosen, a complete CSM with regular updates during
remediation as well as stakeholders’ engagement.

AI Software Firm Specializing in Smart Remediation receives Canadian Government Support

WikiNet, a Quebec-based software firm that claims to have the world’s first
first soil remediation solution using Cognitive Artificial Intelligence (AI), recently received $254,000 in funding from the Canadian government through its Quebec Economic Development Program and its Regional Economic Growth through Innovation Program.

The $254,000 in government funding will help WikiNet diversify its markets, thereby increasing its sales and exports. The contribution will go toward prospecting, producing promotional tools and registering a patent. Fifteen jobs will be created once the government funded project is completed. A sum of $109,000 is a repayable contribution.

WikiNet was founded in 2016 to provide innovative software solutions for the environment sector. It offers niche applications, including a smart management tool for the transportation and management of contaminated soils and an application that uses both a database and artificial intelligence to guide environmental experts in choosing the best site remediation technologies.

WikiNet is developing WatRem, a system that learns from past environmental cleanup efforts to provide automated expert recommendations for treating contaminated sites worldwide.

WikiNet’s artificial intelligence product was one of over 150 projects from 36 countries selected as part of the global IBM Watson AI Xprize for Good competition. The winners of the IBM competition will be announced in 2020.

WikiNet has also developed a smart tool called “Trace” for offsite contaminated soil disposal and certification. ​”Trace” is a cognitive tool to support environmental sustainability by offering a smarter and safer way for off-site soil disposal. It allows stakeholders involved in a remediation project to manage offsite disposal of soils and dangerous materials with live GPS traceability.

Top Environmental Clean Up Projects throughout Canada

by David Nguyen, Staff Writer

1. The Randle Reef Contaminated Sediment Remediation Project – Hamilton, Ontario

Cost: $138.9 million

Contaminant: polycyclic aromatic hydrocarbons (PAHs),
heavy metals

Approximately 60 hectares in size and containing 695 000 cubic metres of sediment contaminated with polycyclic aromatic hydrocarbons (PAHs) and heavy metals, the Randle Reef restoration project is three decades in the making. The pollution stems from various industries in the area including coal gasification, petroleum refining, steel making, municipal waste, sewage and overland drainage.1

Slated to be completed in three stages, the first stage involved the completion of a double steel sheet-piled walled engineered containment facility (ECF) around the most contaminated sediments, with stage 2 consists of dredging of the contaminated sediments into the ECF. Stage 3 will involve dewatering of the sediments in the ECF and treating the wastewater to discharge back into the lake, and the sediments will be capped with 60 cm of sand and silt enriched with organic carbon. This cap will both the isolate the contaminated sediments from the environment and form a foundation or future port structures. The ECF will be capped with layers of several material, including various sizes of aggregate, geo-textile and geo-grid, wickdrains, and asphalt and or concrete. This isolates the contaminants and provides a foundation for future port structures.

The project is expected to be completed by 2022 and cost $138.9 million. The Hamilton Port Authority will take over monitoring, maintenance, and development responsibilities of the facility for its expected 200-year life span. It is expected to provide $151 in economic benefits between job creation, business development, and tourism.

The Canada–United States Great Lakes Water Quality Agreement listed Hamilton harbour (which contains Randle Reef) as one of 43 Areas of Concern on the Great Lakes. Only 7 have been removed, 3 of which were in Canada.

2. Port Hope Area Initiative – Port
Hope, Ontario

Cost: $1.28 billion

Contaminant: low-level radioactive waste (LLRW),
industrial waste

The town of Port Hope, Ontario has about 1.2 million cubic metres of historic LLRW across various sites in the area. The soils and materials contain radium-226, uranium, arsenic, and other contaminants resulting from the refining process of radium and uranium between 1933 and 1988. Additional industrial waste containing metals, hydrocarbons, and dried sewage and sludge with copper and polychlorinated biphenyl (PCBs) will also be contained at the new facility.

The material was spread across town as the tailings were given away for free to be used as fill material for backyards and building foundations. An estimated 800 properties are affected, but the low-level radiation poses little risk to humans. The Port Hope Area Initiative will cost $1.28 billion and will include monitoring before, during, and after the construction of a long term management waste facility (LTMWF).

The LTWMF will be an aboveground engineered storage mound on the site of an existing LLRW management facility to safely store and isolate the contaminated soil and material, as well as other industrial waste from the surrounding area. The existing waste will also be excavated and relocated to the engineered mound. Leachate collection system, monitoring wells, and sensors in the cover and baseliner will be used to evaluate the effectiveness of the storage mound, allowing for long term monitoring of the waste.

The
facility also contains a wastewater treatment plant that will treat surface
water and groundwater during construction of the facility, as well as the
leachate after the completion of the storage mound. The plant utilizes a two
stage process of chemical precipitation and clarification (stage 1) and reverse
osmosis (stage 2) to treat the water to meet the Canadian Nuclear Safety
Commission requirements for water discharged to Lake Ontario.

3. Marwell Tar Pit – Whitehorse, Yukon
Territory

Cost: $6.8 million

Contaminant: petroleum hydrocarbons (PHCs), heavy
metals

This
$6.8 million project funded by the governments of Canada and Yukon will
remediate the Marwell Tar Pit in Whitehorse, which contain 27 000 cubic metres
of soil and groundwater contaminated with hydrocarbons, such as
benz[a]anthracene and heavy and light extractable petroleum hydrocarbons and
naphthalene, and heavy metals such as manganese. Some of the tar has also migrated
from the site.

Contamination
began during the Second World War, when a crude oil refinery operated for less
than one year before closing and being dismantled. The sludge from the bottom
of dismantled storage tanks (the “tar”) was deposited in a tank berm, and over time
other industries and businesses added other liquid waste to the tar pit. In the
1960s the pit was capped with gravel, and in 1998 declared a “Designated
Contaminated Site.”

The
project consists of three phases: preliminary activities, remedial activities,
and post-remedial activities. The preliminary phase consisted of consolidating
and reviewing existing information and completing addition site assessment.

The
second phase of remedial activities began in July 2018 and involves
implementing a remedial action plan. Contaminated soil segregated and heated through
thermal conduction, which vaporizes the contaminants, then the vapours are
destroyed by burning. Regular testing is done to ensure air quality standards
are met. The main emissions from the site are carbon dioxide and water vapour. Remediated
soil is used to backfill the areas of excavation. This phase is expected to be
completed in 2019-2020.

The
final phase will involve the monitoring of the site to demonstrate the
remediation work has met government standards. This phase is planned to last
four years. The project began in 2011 and is expected to be completed in
2020-2021.

4. Boat Harbour – Nova Scotia

Cost: approx.$133 million

Contaminant: PHCs, PAHs, heavy metals, dioxins and
furans

The provinces largest contaminated site, Boar Harbour, is the wastewater lagoon for the local pulp mill in Abercrombie Point, as well as the discharge point for a former chemical supplier in the area. Prior to 1967, Boat Harbour was a saltwater tidal estuary covering 142 hectares, but a dam built in 1972 separated Boat Harbour from the ocean, and it is now a freshwater lake due to the receiving treated wastewater from the mill since the 1967.

The
wastewater effluent contains contaminants including dioxins and furans, PAHs, PHCs,
and heavy metals such as cadmium, mercury, and zinc. In 2015, the government of
Nova Scotia passed The Boat Harbour Act, which ordered that Boat Harbour cease
as the discharge point for the pulp mill’s treated wastewater in 2020, which
allows time to build a new wastewater treatment facility and time to plan the
remediation of Boat Harbour.

The
estimated cost of the cleanup is $133 million, which does not include the cost
of the new treatment facility. The goal is to return the harbour to its
original state as a tidal estuary. The project is currently in the planning
stages and updates can be found at https://novascotia.ca/boatharbour/.

5. Faro Mine – Faro, Yukon

Cost: projected$450 million

Contaminant: waste rock leachate and tailings

Faro Mine was once the largest open-pit lead-zinc mine in the world, and now contains about 70 million tonnes of tailings and 320 million tonnes of waste rock, which can potentially leach heavy metals and acids into the environment. The mine covers 25 square kilometres, and is located near the town of Faro in south-central Yukon, on the traditional territory of three Kasha First Nations – the Ross River Dena Council, Liard First Nation and Kaska Dena Council. Downstream of the mine are the Selkirk First Nation.

The
Government of Canada funds the project, as well as leads the maintenance, site
monitoring, consultation, and remediation planning process. The Government of
Yukon, First Nations, the Town of Faro, and other stakeholders are also responsible
for the project and are consulted regularly to provide input.

The
entire project is expected to take about 40 years, with main construction activities
to be completed by 2022, followed by about 25 years of remediation. The
remediation project includes upgrading dams to ensure tailings stay in place,
re-sloping waste rock piles, installing engineered soil covers over the
tailings and waste rock, upgrading stream diversions, upgrading contaminant
water collection and treatment systems.

6. Sylvia Grinnell River Dump – Iqaluit,
Nunavut

Cost: $5.4 million

Contaminant: PHCs, polychlorinated biphenyls
(PCBs), pesticides

Transport Canada awarded a contract of over $5.4 million in 2017 for a cleanup of a historic dump along the mouth of Sylvia Grinnell River in Iqaluit, Nunavut. The dump contains metal debris from old vehicles and appliances, fuel barrels, and other toxic waste from a U.S. air base, and is a site for modern day rogue dumping for items like car batteries. This has resulted in petroleum hydrocarbons, polychlorinated biphenyls (PCBs), pesticides, and other hazardous substances being identified in the area.

The Iqaluit airfield was founded in Frobisher Bay by the U.S. military during World War 2 as a rest point for planes flying to Europe. During the Cold War, the bay was used as part of the Distant Early Warning (DEW) Line stations across the north to detect bombers from the Soviet Union. When the DEW was replaces by the North Warning System in the 1980s, these stations were abandoned and the contaminants and toxic waste left behind. Twenty-one of these stations were remediated by the U.S. Department of National Defence at a cost of about $575 in 2014.

The Sylvia Grinnell River remediation project is part of the Federal government’s responsibility to remediate land around the airfield that was transferred to the Government of Nunavut in the 1990s.The contract was awarded in August 2017 and was completed in October. The remaining nontoxic is sealed in a new landfill and will be monitored until 2020.

7. Greenwich-Mohawk Brownfield – Brantford,
Ontario

Cost: $40.78 million

Contaminant: PHC, PAC, heavy metals, vinyl
chloride

The
City of Brantford have completed a cleanup project of 148 000 cubic metres of
contaminated soil at the Greenwich-Mohawk brownfield site. The area was historically
the location of various farming manufacturing industries that shut down,
leaving behind contaminants like PHC, PAC, heavy metals like lead, xylene, and
vinyl chloride.

Cleanup
began in 2015, and consisted coarse grain screening, skimming, air sparging,
and recycling of 120 000 litres of oil from the groundwater, using biopiles to
treat contaminated soil onsite with 73% of it being reused and the rest
requiring off site disposal.

Barriers
were also installed to prevent future contamination from an adjacent rail line
property, as well as to contain heavy-end hydrocarbons discovered during the
cleanup that could not be removed due to the release odorous vapours throughout
the neighbourhood. The 20 hectare site took two years to clean and costed only
$40.78 million of the allocated $42.8 million between the all levels of
government, as well as the Federation of Canadian Municipalities Green
Municipal Fund.

8. Rock Bay Remediation Project –
Victoria, British Columbia

Cost: $60 million

Contaminant: PAHs, hydrocarbons, metals

Located near downtown Victoria and within the traditional territories of the Esquimalt Nation and Songhees Nation, the project entailed remediating 1.73 hectares of contaminated upland soils and 2.02 hectares of contaminated harbour sediments. The site was the location of a former coal gasification facility from the 1860s to the 1950s, producing waste products like coal tar (containing PAHs), metals, and other hydrocarbons, which have impacted both the sediments and groundwater at the site.

Remediation occurred in three stages. From 2004 to 2006, the first two stages involving the remediation of 50 300 tonnes of hazardous waste soils, 74 100 tonnes of non-hazardous waste soils, and 78 500 tonnes of contaminated soils above commercial land use levels. In 2009, 250 tonnes of hazardous waste were dredged from two sediment hotspots at the head of Rock Bay. About 7 million litres of hydrocarbon and metal impacted groundwater have been treated or disposed of, and an onsite wastewater treatment plant was used to return treated wastewater to the harbour.

Construction
for the final stage occurred between 2014 to 2016 and involved:

  • installing
    shoring along the property boundaries to remove up to 8 metres deep of
    contaminated soils,
  • installing
    a temporary coffer dams
  • draining
    the bay to remove the sediments in dry conditions, and
  • temporary
    diverting two storm water outfalls around the work area.

Stage
three removed 78 000 tonnes of contaminated and 15 000 tonnes of
non-contaminated sediment that were disposed of/ destroyed at offsite
facilities.

Final post-remediation monitoring was completed in January 2017, with post-construction monitoring for 5 years required as part of the habitat restoration plan to ensure the marine habitat is functioning properly and a portion of the site will be sold to the Esquimalt Nation and Songhees Nation.

9. Bushell Public Port Facility
Remediation Project – Black Bay (Lake Athabasca), Saskatchewan

Cost: $2 million

Contaminant: Bunker C fuel oil

 Built in 1951 and operated until the mid-1980s, the Bushell Public Port Facility consist of two lots covering 3.1 hectares with both upland and water lots. The facility supplied goods and services to the local mines, and petroleum products to the local communities of Bushell and Uranium City. Historical activities like unloading, storing, and loading fuel oil, as well as a large spill in the 1980s resulted in the contaminated soil, blast rock, and bedrock in Black Bay that have also extended beyond the waterlot boundaries.

The remediation work occurred between 2005 to 2007, and involved excavation of soil and blast rock, as well as blasting and removing bedrock where oil had entered through cracks and fissures.

Initial
remediation plans were to crush and treat the contaminated material by low
temperature thermal desorption, which incinerates the materials to burn off the
oil residue. However, opportunities for sustainable reuse of the contaminated
material came in the use of the contaminated crush rock for resurfacing of the
Uranium City Airport. This costed $1.75 million less than the incineration
plan, and saved the airport project nearly 1 million litres of diesel fuel. The
crush was also used by the Saskatchewan Research Council in the reclamation of
the Cold War Legacy Uranium Mine and Mill Sites. A long term monitoring event
is planned for 2018.

10. Thunder Bay North Harbour –
Thunder Bay, Ontario

Cost: estimated at upwards to $50 million

Contaminant: Paper sludge containing mercury and other contaminants

 While all of the projects discussed so far have either been completed or are currently in progress, in Thunder Bay, the plans to clean up the 400 000 cubic metres of mercury contaminated pulp and fibre have been stalled since 2014 due to no organization or government designated to spearhead the cleanup.

While
the water lot is owned by Transport Canada, administration of the site is the
responsibility of the Thunder Bay Port Authority, and while Transport Canada
has told CBC that leading the cleanup is up to the port, the port authority was
informed by Transport Canada that the authority should only act in an advisory
role. Environmental Canada has participated in efforts to advance the planning
of the remediation work, but is also not taking the lead in the project either.
Further complications are that the industries responsible for the pollution no
longer exist.

Industrial activities over 90 years have resulted in the mercury contamination, which range in concentrations between 2 to 11 ppm on surface sediments to 21 ppm at depth. The thickness ranges from 40 to 380 centimetres and is about 22 hectares in size. Suggested solutions in 2014 include dredging the sediment and transferring it to the Mission Bay Confined Disposal Facility, capping it, or building a new containment structure. As of October 2018, a steering committee lead by Environment Canada, Transport Canada, Ontario’s environmental ministry and the Thunder Bay Port Authority, along with local government, Indigenous groups, and other stakeholders met to evaluate the remediation options, as well as work out who will lead the remediation.

Performance Assessment of Pump and Treat Systems

Researchers at the U.S. Department of Energy’s Pacific Northwest National Library recently released a paper on the Performance Assessment of Pump-and-Treat Systems.

The pump-and-treat (P&T) remediation technology is comprised of three main aspects:  groundwater extraction for hydraulic control and contaminant removal, above-ground treatment, and groundwater monitoring to assess performance.

Pump-and-treat (P&T) is a widely applied remedy for groundwater remediation at many types of sites for multiple types of contaminants. Decisions regarding major changes in the remediation approach are an important element of environmental remediation management for a site using P&T. Performance assessment during P&T remedy implementation may be needed because of diminishing returns, the complex nature of the site and contamination, or other factors.

While existing guidance documents for the performance assessment of pump-and-treat systems provide information on design, operation, and optimization for P&T systems, these documents do not provide specific technical guidance to support remedy decisions regarding when to transition to a new remedy or to initiate closure of the P&T remedy.

In the paper, the researchers describe a structured approach for P&T performance assessment that was developed  using analysis of three example P&T systems. These examples highlight key aspects of the performance assessment decision logic and represent assessment outcomes associated with optimizing the P&T system, transitioning from P&T to natural attenuation, and supplementing P&T with another technology to hasten transition to natural attenuation.

Decision elements for the P&T performance assessment include:

  • Contaminant concentrations and trends
  • Contaminant mass discharge from source areas or at selected plume locations
  • The attenuation capacity of the aquifer
  • Estimated future plume behavior and time to reach remedial action objectives for the site
  • P&T system design, operational, and cost information

Categories of decision outcomes for the P&T assessment include:

  • Initiate P&T remedy closure
  • Continue with existing or optimized P&T
  • Transition to Monitored Natural Attenuation
  • Supplement P&T with other treatment technologies
  • Transition to a new remedy approach

 

Labrador Dump to be converted to Wetland

As reported by the CBC, The Canadian Department of National Defence is cleaning up an old dump in Happy Valley-Goose Bay, Newfoundland and Labrador.

Crews are working to clean up the old dump used by the 5 Wing Goose Bay base, and will be creating an engineered wetland to filter out potential contaminants in the soil.

Happy Valley-Goose Bay is a town of 8,000 people in the located in in the central part of Labrador on the coast of Lake Melville and the Grand River, near the North Atlantic Ocean.

This kind of wetland differs from others that focus on preserving at-risk species of ducks and waterfowl, says Lori Whalen, contaminated sites manager with the Department of National Defence.

“An engineered wetland is a passive designed wetland that is meant to be part of a remedial system, so it’s actually acting like a filter,” she said.

Lori Whalen, contaminated sites manager with the Department of National Defence (Photo Credit: Gary Moore/CBC)

The site was used as the main dump for 5 Wing Goose Bay, and Whalen said the pollution is mainly a legacy of the American Air Force when they used the base in the mid- to late 1900s.

At that time, Whalen said, there were not environmental regulations in place to ensure things were disposed of properly.

“We have material from domestic waste, construction debris, barrels that would have contained fuels and lubricating materials, even vehicles … that were just thrown over the bank,” Whalen said.

The Goose Bay Remediation Program has a $13.5-million cost and is part of a larger federal government program to clean up contaminated sites around Canada.

A majority of the work will be done this summer, National Defence said, and while it continues, people are being asked to steer clear of the site.

Whalen said this project should help ease concerns in the community over the years that pollution from the base could be affecting the water.

“The extensive sampling programs that we’ve done over the past 20 years points out that drinking water is safe for consumption,” Whalen said.

“The surface water that’s flowing through the culverts off site is below the appropriate criteria and we haven’t seen any issues in the ground water as well.”

Aerial view of the Goose Bay remediation project

Meanwhile, people in the community like John Hickey, who has been pushing for the base’s cleanup since he was mayor in the early 2000s, said there’s plenty more to be done.

“When it comes to the environment, we’ll never be satisfied,” said Hickey, who was also an MHA for the area.

“We have to ensure now that, while this work is being done, other work that needs to be done is identified and is cleaned up.”

But Hickey said he is happy to see this site getting the attention it deserves.

“This is going to be, I think, a very nice place when it’s finished and completed,” Hickey said.

“I think you’ll see a lot of waterfowl and things moving in to the area, which is all good for our community.”

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