Bloodvein First Nation Environmental Remedial Actions - 5 PHC Sites

The petroleum hydrocarbon impacted soil will be hauled to a new community landfarm, for treatment.

A new landfarm facility is proposed for construction at the Former Waste and Landfarm site, in the vicinity of the Former Manitoba Hydro treatment cell following spot (target) remediation activities. During the construction of a new landfarm floor, it is recommended that the PHC impacts previously identified (or newly encountered) within the Former MB Hydro landfarm cell be excavated and stockpiled on-site, pending treatment. Any non-impacted, overlying, soil may be excavated and recycled into the base and/or berm reconstruction. Once the landfarm has been reconstructed, any impacted soil identified on site that was excavated and separated, may be placed and treated in the new facility. Targeted remediation will also be undertaken within the former school landfarm treatment cell.

Pre-construction activities will include the development of a detailed project design report for approval. Upon approval of the final design stage by the project team, tender documents (i.e. drawings and specifications) will be prepared and the tender call will be administered.

Construction work will be initiated by the successful Contractor in the summer of 2021, and will commence with the construction of a new community landfarm. Landfarm construction will include, at a minimum, grading the cell floor, followed by the installation of a 60 mil HDPE liner and non-woven geotextiles. Perimeter ditching and berms, erosion control mats, a sump, and monitoring wells will also be included in the design layout. The existing site access trail will be upgraded with geotextiles and aggregate materials to provide an all-weather, durable road for truck travel.

Site preparation activities at the remediation sites will include proper buried service locates, the installation of silt fencing, general site clean-up, and minor clearing and grubbing. A general site cleanup will be required at the Maintenance Garage site including the removal of all derelict vehicles / equipment / machinery, fencing, barrels, and other debris. The abandoned ASTs located at the Maintenance Garage site will also require proper decommissioning by a Licensed Petroleum Technician (LPT). Following decommissioning, the tanks should be hauled out of the community for recycling.

Excavation activities will begin in the summer of 2021, following the landfarm construction and site preparation activities. Care will be exercised in loading the material into the trucks so that contaminated material does not fall outside the truck box. Half or ¾ full buckets should be the norm when loading the soil into the trucks and all trucks will be required to have a proper cover during transport. Vehicles travelling between the excavation area and the disposal site shall also be kept clean to prevent tracking of contaminated soil between the working areas. All overburden soil will be stockpiled on-site and sampled to ensure its suitability for reuse. The overburden stockpile will be orientated to minimize the area exposed to winds and/or stabilized using water sprays or an appropriate cover material.

During the course of the soil excavation activities, the limits of the excavation will be assessed using field screening techniques. The final limits of the excavation (vertical and horizontal extents) will be subject to field screening and confirmatory laboratory analysis of CWS F1-F4 hydrocarbon fractions, CCME CEQG benzene, toluene, ethylbenzene and xylenes (BTEX), volatile organic compounds (VOC), and/or polycyclic aromatic hydrocarbon (PAH) concentrations. All laboratory results will be compared to current CCME residential land use guidelines. The excavated areas will be backfilled with clean soil from a selected borrow area and the impacted soil will be hauled to the community landfarm for treatment.

PHC impacts may extend beneath existing buildings at the Miskooseepi School, Maintenance Garage, Former Maintenance Garage and Raw Water Intake building site, and full removal of the PHC impacted soil may not be possible due to the shallow foundations. In the event that full removal of impacted soils cannot be accomplished to the referenced CCME values, a hydrocarbon resistant, HDPE separation liner (20 mil) will be recommended to enclose the base and/or sidewalls of the excavation. This will effectively separate impacted soils from the clean backfill material placed within the excavation. In addition, indoor air and/or potable water sampling within the buildings may be necessary following site remediation, as a mitigation measure. A long-term groundwater monitoring program may also require implementation at the sites, for risk management purposes.

Remedial measures will also include the treatment of hydrocarbon impacted water that may accumulate in the excavations during site remediation due to seepage or precipitation, by means of a water treatment system. To address water infiltration or precipitation, a water treatment system will be made available throughout the excavation work to treat any impacted water. Coalescing separators and clay/carbon filtration/polish systems shall be implemented to deal with hydrocarbon impacted water at the source. Treated water will be sampled and analyzed for hydrocarbon concentrations, prior to discharge. The same treatment methodology and treatment system will be used to treat impacted water accumulated within the sump at the landfarm treatment cell. The Federal Interim Groundwater Quality Guidelines applicable to the appropriate land use, pathway and receptors at the remediation sites are presented in the 2021 Preliminary Design Report (PDR) developed for the project by Aski. Any water treated to these levels will be suitable for direct discharge to the environment (i.e. nearby ditching).

For the duration of the project, roadways will be watered on a regular basis for dust control and regraded. Minor grading and placement of roadway gravel is also expected. In order to ensure the protection of the general public, safety personnel will be retained throughout the duration of the project. This will include an on-site flagman to provide traffic/pedestrian control, as well as site security personnel during non-construction hours. In addition, safety fencing will be erected at the remedial sites prior to initiating any construction work and will remain in place until backfilling activities are complete. By way of community bulletin, notices, or radio announcement, adjacent businesses and community members will be informed of the intended on-site dates to avoid exposure to vapors and fumes. Large industrial fans may also be established near the remediation zones, to direct vapours away from any buildings, pedestrian traffic, and any fresh air intake vents that may be nearby.
 

The Contractor will be responsible for ensuring compliance with applicable provincial and federal legislation for the storage, handling and disposal of hazardous substances such as fuels and lubricants. Any hazardous waste materials generated during the soil remediation activities will be hauled away for proper off-site disposal. Construction vehicles will be fueled off-site at a designated area. An emergency response plan that includes spill prevention, notification and response will be prepared and implemented by the Contractor during soil remediation activities and landfarming operations. The Contractor is responsible for ensuring that spill response equipment is available on-site at all times during the soil remediation activities. No free-product has been identified at any of the sites to date, however, should free-product be encountered during excavation activities, it will be pumped into drums, stored in a secure location on a hydrocarbon resistant liner, and removed from the community.

Treatment of soils at the landfarm site may be initiated during the 2021 fall construction season. Biodegradation of the hydrocarbon fractions will be accomplished by spreading the impacted soils across the treatment facility in lifts, followed by periodic tilling and application of nutrients (phosphate and nitrogen mixture). Treatment of soils at the landfarm site will be on-going throughout the 2023 field season (if required). Composite samples will be obtained from the treated soils on a regular basis for field analysis. Once field testing has indicated an acceptable decrease in petroleum hydrocarbons, select soil samples will be submitted for confirmatory laboratory analysis. Once treated to the regulatory standards indicated in the PDR, the soil will be hauled to the community landfill for utilization as cover material.
 

Throughout the use of the landfarm site, groundwater samples will be collected from the perimeter monitoring wells and analyzed for baseline hydrocarbon parameters (CCME F1 to F4, BTEX, and PAH), as required and before closure of the landfarm. Collected surface water within the sump area may be used for periodic irrigation of the treatment layer during very dry conditions in order to prevent desiccation or excessive wind-blown dust. The water may be broadcasted over the impacted soils in the treatment cell. Alternatively, a water treatment system will be utilized to remove hydrocarbon concentrations from the sump water prior to discharge.

At the completion of the project, the excavation areas will be cleaned-up and fine graded with positive drainage. To ensure slope stabilization, landscaping, leveling, compaction and seeding will be performed where required. Erosion control mats may also be installed over disturbed areas at the sites. Any area where vegetation was removed for construction and/or excavation purposes will be landscaped or seeded to allow re-establishment of vegetation common to the community. The monitoring wells installed within the impacted zones during the Environmental Site Assessments will be removed during the remedial activities and any remaining monitoring wells will be decommissioned if the wells are no longer required for future monitoring.

Upon completion of the soil treatment at the landfarm site, Indigenous Services Canada (ISC) will be notified of the proposed closure of the facility. In general, landfarm closure will include the removal of  the treated soils for use as cover material in the landfill and the removal of the containment berms. Following removal of berms, the site shall be shaped for proper drainage, and re-vegetated, if necessary, to control runoff erosion. Alternatively, the landfarm facility may be maintained and retained for future soil remediation projects in the community.