4.0 REMEDIATION AND RISK MANAGEMENT

Transcription

1 4.0 REMEDIATION AND RISK MANAGEMENT 4.1 Residential Property Use Area The residential development area includes PAH impacted soil in the vicinity of the former Coliseum Annex Buildings, Horticultural Building and former East Lavatory. s at the former Coliseum Annex Buildings and Horticultural Building include exceedances of the EPA 2004 and 2011 Table 3 SCS by PAH for R/P/I property use, while those at the former East Lavatory include exceedances of the EPA 2011 Table 3 SCS by PAH for R/P/I property use. The areas and volumes of impacted soil exceeding residential property use SCS are summarized in Table 1 below. Table 1: Summary of Inferred Areas of in Residential Property Use Area Exceeding EPA 2004 and 2011 EPA Table 3 SCS EPA 2004 Table 3 SCS EPA 2011 Table 3 SCS Site Area Area (m 2 ) Thickness (m) Volume (m 3 ) [tonnes] Area (m 2 ) Thickness (m) Volume (m 3 ) [tonnes] Former Coliseum Annex 2, ,880 [11,760] 6, ,440 [26,880] Horticultural Building 2, ,675 [7,350] 3, ,875 [9,750] Former East Lavatory , ,625 [5,250] Totals 5,250-6,555 [13,110] 11,400-20,940 [41,880] Excavation of ed Soil The Site redevelopment plan includes the construction of an underground parking structure to accommodate in excess of 1,000 vehicles. Construction of the underground parking structure will necessitate the excavation of approximately 228,000 cubic metres of existing fill and soil to an approximate depth of metres below the existing surface grade. The PAH impacted fill and soil in the vicinity of the former Coliseum Annex, Horticultural Building and former East Lavatory will be excavated as part of the parking structure excavation works. Although the City has filed a Transition Notice allowing it to file an RSC based on the EPA 2004 Table 3 SCS, it is recognized that the required excavation works will also result in the excavation of fill and soil that exceeds EPA 2011 Table 3 SCS. This will necessitate the management of excess soil that meets the required EPA 2004 Table 3 SCS, as per the Transition Notice, but exceeds EPA 2011 Table 3 SCS. As the excavation works are being undertaken after July 1, 2011 when the O.Reg. 511/09 amendments take full effect, including the EPA 2011 SCS, excess soil generated at the Site exceeding EPA 2011 Table 3 SCS will require management in accordance with the Page 14 TZ

2 amended regulation. Under the revised regulation, soils meeting the EPA 2004 Table 3 SCS for R/P/I property use but exceeding the EPA 2011 Table 3 SCS for R/P/I property use will not be permitted for re-use at other -owned R/P/I property use sites and will require on- Site management and/or disposal at a licensed landfill. The approximate extent of the excavation required for the underground parking structure is shown on Figure 12 and is roughly coincident with the residential property use area. The inferred extent of the PAH impacted soil in the vicinity of the former Coliseum Annex, Horticultural Building and former East Lavatory are also shown on Figure On-Site Management of ed Soil ed soil exceeding EPA 2011 Table 3 SCS for R/P/I property use within the residential property use area will be managed on Site taking advantange of the cut and fill quantities required as part of the Site redevelopment. The cut requirements, as noted above, stem from the parking structure excavation requirements. ed fill and soil with the residential property use area extending beyond the limit of the parking garage excavation, such as areas along the north property boundary, will also be managed through conventional soil excavation methods. Part of the Site redevelopment will include the construction of earthen berms along the south and east sides of the new Stadium. The berms will extend from the southwest corner of the Site across the south side of the Stadium and wrapping around the east end of the stadium where it will serve as the foundation for additional stadium seating during large events such as the Grey Cup. The fill volume for the berms is estimated at 86,000 cubic metres. ed fill and soil exceeding EPA 2011 Table 3 SCS for R/P/I property use excavated from the residential development area will be used as fill for part of the construction of the berms. Such an approach, that is, the use of contaminated excavated soils and materials on-site, constitutes a beneficial re-use of waste material that would otherwise require landfill disposal and provides a sustainable development solution that has been successfully employed in a number of jurisdictions in Canada as part of Brownfield redevelopments. Use of the impacted fill and soil excavated from the future residential area would be restricted to that portion of the berms to be located on the future parkland property use portion of the Site on the south and east sides of the new stadium. A conceptual plan and cross sections showing the construction of the berms and location of the impacted soil are provided on Figures 13 and 14, respectively. Final details of the berm construction will be determined as part of the final design and Risk Assessment being undertaken for the parkland property use area. The berms will be constructed using conventional earth moving equipment. The northern side of the South Berm, where in contact with the new South Side Stands, will have a vertical face being set against the south elevation of the new Stadium. The south side of the South Berm and the East Berm will be constructed with a slope of 20-30% to minimize surface water infiltration and interaction with the impacted soil. The impacted soil will be covered with a TZ Page 15

3 minimum clean cover soil thickness of 1.5 metres to isolate the impacted soil and provide adequate growth medium for landscaping without the risk of contaminant uptake by any of the plant species. Geotextile and/or geomembrane materials will be used to separate the impacted and clean soils and to facilitate easy identification of the impacted during any subsequent earth works involving excavation into the berms. The finished berms will be landscaped with grass sod and trees to minimize erosion and provide aesthetic appeal Segregation and Separation of Construction Demolition Debris Investigations carried out at the Site to date have shown that varying quantities of construction debris including brick, rubble, concrete glass, metals and wood are present in the vicinities of the former Coliseum Annex and former East Lavatory. These materials are known to occur within the limits of the PAH impacted soils in each of these areas as well as beyond. The inferred limits of the waste and construction/demolition debris are shown on Figure 15. Within the areas of soil impact, these inert materials may affect the placement and integrity of the earthen berms depending upon the nature and size of their occurrences. As such, it may be necessary to segregate these materials from impacted and/or non-impacted soil. Such soil segregations activities would be carried out making use of a remnant portion of the Coliseum Building to be used as a staging and sorting area to allow more effective dust control and to provide cover from wind conditions that could lead to increased dust emissions from the Site where higher dust generating activities are being carried out. Should it become necessary to completely demolish the Coliseum Building prior to segregating the construction/demolition debris due to project timing or other issues, a temporary sprung-type structure would be erected at the Site as a replacement for the Coliseum Building Health and Safety The excavation and management of impacted soil within the residential development area will necessitate significant movement and handling of soil that has been impacted by contaminants potentially harmful to human health. A health and safety plan will be developed for the Site not only to protect workers during construction activities, but also to protect the local community and the general public. The health and safety plan will include plans for dust control and soil tracking to prevent excessive fugitive dust emissions onto other parts of the Site and adjacent properties as well as to prevent vehicle tracking of contamination onto municipal roadways and private properties during the Site works. Fugitive dust monitoring will be carried out to assess dust emissions and measure airborne particulate loadings from the Site as well as to measure the effectiveness of any dust control measures implemented at the Site as well as to address potential complaints from the public. The fugitive dust monitoring program will include development of a conservative contaminant surrogate based on total particulate. This will allow for more rapid reporting of daily dust fall measurements that are closer to real time and thus allowing a more timely response for corrective actions that may be required. The surrogate values will be periodically verified and/or calibrated through analysis for the target contaminants of concern, namely PAH and/or metals. Page 16 TZ

4 Potential corrective actions for dust control may include simple soil wetting techniques using water or other chemical dust suppressants, as deemed appropriate Soil Staging The East Berm will be constructed concurrent with the underground parking structure excavation works thus allowing the impacted soil to be re-located directly to the berm without the need for temporary stockpiling or staging. However, the design capacity of the East Berm may be insufficient to contain all the impacted soil to be excavated at the residential property use area. On-site temporary stockpiling or staging of impacted soil in excess of the East Berm design capacity may be required due to a later construction period for the South Berm. This stems form a requirements to construct the south retaining wall of the new stadium prior to the South Berm. The soils will be stockpiled on Site in a designated location yet to be determined. Alternatively, the City may elect to dispose of any excess impacted soil at an approved disposal facility. Where it becomes necessary to temporarily store impacted soil at the soil prior to placement within the berms, such stockpiles will be protected from wind erosion and the effects of potential effects of precipitation infiltration and leaching and/or entrainment in precipitation run-off through the use of suitable covers such as tarpaulins or plastics sheeting. Such covers would be appropriated weighted to prevent unwanted movement or removal by wind action. Soil staging will be conducted on areas of the Site where existing hard surface caps such as asphalt or concrete surfacing materials are already in place. The use of such hard surfaced areas will allow for easy clean-up of residual impacted soil that can not be moved using conventional earth moving equipment. In the event that impacts soil must be stockpiled on areas void of impermeable surface cover and placed directly on soil, such areas will be subject to verification and confirmatory soil sampling program at the completion of the soil staging operations to ensure that all impacted soil has been effectively removed form the staging area. 4.2 Community Property Use Area The community use portion of the Site includes those lands currently occupied by Frank Clair Stadium/Civic Centre, the Aberdeen Pavilion and that portion of the Site to which the Horticultural Building will be relocated at the east end of the residential property use area. The future property uses will include those that are similar to the current property use and will thus not result in any property use change that will trigger the need to file a RSC. 4.3 Parkland Property Use Area The Site redevelopment will include the removal of the majority of the existing asphalt parking areas from the eastern portion of the Site which will be replaced with a landscaped front lawn stretching across the eastern portion of the Site. The front lawn will feature a park-like setting with pedestrian and cycling paths, a children s playground, an outdoor curling court, and an outdoor concert hall and will be consistent and continuous with the existing property use on the TZ Page 17

5 NCC lands adjacent to the Queen Elizabeth Driveway and the Rideau Canal. Property use for the front lawn area will be consistent with parkland property use as per O.Reg. 153/04. The redevelopment of this area of the Site and the South and East Berms to be located along the south and east sides of the revitalized Frank Clair Stadium, respectively, will constitute a change to a more sensitive land use and this will require the filing of a RSC. The front lawn will include the majority of the Eastern Landfill. The Eastern Landfill is inferred to have been placed some time prior to 1910 when the last vestige of the former inlet from the Rideau Canal was infilled. Waste materials within the landfill include wood, metal, ashes, cinders, coal, brick and decayed organic matter which were encountered between depths of 1.2 and 4.5 metres below grade. Soils within the limit of the Eastern Landfill exceed EPA Table 3 SCS for R/P/I property uses for metals and PAH. A single PHC F3 exceedance was limited to a solitary sample that also exceeded for metals and PAH. Soil exceedances were identified at depths ranging from 0.8 metres to 4.8 metres below grade. PAH exceedances were identified in shallower soil samples, whereas metal exceedances occur in both shallow and deep soil samples. The metal, PAH and PHC exceedances exhibit a sporadic and random distribution, with several intermediate test locations exhibiting no exceedances. These impacts occur within the fill and waste materials placed at the Site and thus, are likely a direct reflection of the original quality of the fill and waste imported to the Site at the time of filling. The areas and volumes of impacted soil exceeding parkland property use SCS are summarized in Table 1 below. Table 2: Summary of Inferred Areas of in Parkland Property Use Area Exceeding EPA 2004 and 2011 EPA Table 3 SCS EPA 2004 Table 3 SCS EPA 2011 Table 3 SCS Site Area Area (m 2 ) Thickness (m) Volume (m 3 ) Area (m 2 ) Thickness (m) Volume (m 3 ) [tonnes] Eastern Landfill 9, ,590 [81,180] 11, ,150 [94,300] Restoration of the Eastern Landfill to achieve compliance with the EPA 2011 Table 3 SCS for parkland property use using conventional excavation methods would require the excavation and off-site disposal of in excess of 94,000 tonnes of material. As a more sustainable and practical alternative to the conventional dig and dump approach, and in view of its prohibitive cost, the City will complete a Risk Assessment to develop Property Specific Standards (PSS) and identify any risk management measures that will be required to support the filing of a RSC for the parkland use portion of the Site to allow its subsequent redevelopment. Through prior consultation with the MOE, the minimum risk management measures required for the Eastern Landfill will include capping with an impermeable cover to prevent infiltration of precipitation and surface run-off to mitigate potential leaching of contaminants within the landfill to groundwater. Page 18 TZ

6 As noted above, impacted soil excavated from the residential property use area will be relocated to the area south and east of the new stadium stands for emplacement within the South and East Berms. The Risk Assessment will also assess any potential risks to human and ecological receptors and the natural environment that may be associated with construction and future maintenance of the South and East Berms. The Risk Assessment will also identify any necessary construction measures, such as the use of geotextiles or geomebranes, as isolation or infiltration barriers. The Risk Assessment will also identify any post construction monitoring and maintenance requirements to assess the effectiveness and performance of the berms and to ensure its continued operation in accordance with its intended design. In accordance with O.Reg. 153/04, a Pre-submission Form (PSF) has been submitted to the MOE as an initial step in the completion of a Risk Assessment. The PSF summarizes the available site assessment data and provides an indication of the complexity of the Risk Assessment to Ministry reviewers. The completion of the PSF involves tabulating all of the site assessment data and providing scaled drawings showing sampling locations and cross sections depicting stratigraphy, water table depth and the vertical extent of sampling. Owing to the complex scientific nature of Risk Assessments, the PSF is meant to summarize, in a standard format, an understanding of the nature of contamination, its location, potential migration pathways and exposure pathways for human and ecological receptors. The Risk Assessment will evaluate potential risks to both human and ecological receptors. As the RSC is required in support of a property use change that will see the parkland property use area redeveloped to a potentially more sensitive use than the current use, the Risk Assessment will be based on the relevant receptors and exposure pathways that will be associated with the redeveloped parkland property use area and the associated future uses. The purpose of a Human Health Risk Assessment (HHRA) is to quantify within reasonable bounds of uncertainty the potential health risks associated with exposure to chemicals in the environment. In doing so, the Risk Assessment takes into account the concentrations of the chemicals in various environmental media (i.e., soil and groundwater, as well as migration of the compounds into air), the manner in which people may be exposed, and the toxicity associated with the chemical. A critical initial step of the Risk Assessment will be the problem formulation step, which defines the scope of the assessment. This is dependent on the contaminants of concern (COCs), the characteristics of the Site and the receptor populations, potential exposure pathways and the extent of information that may be available regarding the level of COCs in the various media. Similar to the human health assessment, an Ecological Risk Assessment (ERA) is an iterative process for evaluating the likelihood that adverse impacts may occur or are occurring as a result of exposure to one or more stressors. In general, the ERA consists of a multi-phase activity beginning with the assessment of data on the presence of potential COCs in various ecologically relevant media (surface soil, ground water, etc.) and evaluation of the potential for ecological impacts, either through the screening of COC concentrations against relevant benchmarks or the direct measurement/observation of those impacts. The assessment of TZ Page 19

7 potential risks for ecological receptors will be based largely on established ecotoxicity studies that identify effect-based screening levels for different species of interest. Where potential risks are identified, mitigation strategies will be developed as a means to reduce and/or eliminate exposure pathways. The development of cost-effective and practical risk management options for any contaminants that present an unacceptable risk is the primary objective of any Risk Assessment. Preliminary discussion concerning potential risk management requirements at the subject property will be conducted early on in the process, with the calculation of preliminary PSS. In finalizing the Risk Assessment for submission, should the evaluation of risk indicate that some form of management is required to reduce risks to acceptable levels, AMEC will develop a series of options for discussion with the City prior to completion of the Risk Assessment. Based on our understanding of the Site conditions and the proposed future redevelopment of the parkland property use area, it is estimated that the risk management measures that will be required for the Site will be limited to barrier risk management measures to isolate the impacted soil from human and/or ecological contact. Upon filing of the Risk Assessment the MOE will likely provide comments on the submitted Risk Assessment requiring edits to the Risk Assessment. With the receipt of comments from the MOE on the submitted Risk Assessment, including any risk management measures proposed from the subject property, AMEC will produce a revised Risk Assessment and detailed responses to the comments raised by the MOE with respect to the submitted Risk Assessment to allow for resubmission of the Risk Assessment in obtaining its acceptance. At the completion of the project, once MOE approval of the Risk Assessment has been obtained, a RSC will be prepared and registered for the Site. The RSC will be prepared and submitted by a QP with the appropriate qualifications for completing RSCs based on the results of a Risk Assessment (i.e., P.Eng. or P.Geo.). 4.4 Schedule The tentative schedule for the RAP is provided in Table 3 below. It should be noted that the schedule is subject to the finalization of certain elements including, but not necessarily limited to, the final design for the South and East Berms and the final design for the front lawn. In addition, there are uncertainties regarding the timing of the Risk Assessment process for the parkland property use area ( front lawn ), more specifically, uncertainties regarding the provision of comments and ultimate acceptance of the Risk Assessment by the MOE Standards Development Branch. The tentative RAP schedule is provided up to the submission of RSC for each of the residential and parkland property use areas. Page 20 TZ

8 Zone A Table 3: Preliminary Environmental Timelines for Lansdowne Park Redevelopment Environmental Element Anticipated Start Date Anticipated Completion Date Excavation of impacted soil beneath residential property use area and placement in South and East Berms. Preparation of Remediation Report for residential property use area Filing of Record of Site Condition (RSC) for residential property use area May 1, 2012 November 1, 2012 November 2, 2012 November 23, 2012 November 30, 2012 December 14, 2012 Zone C Preparation of Pre-Submission Form for parkland property use area ( front lawn ) South / East Berm design modifications for contaminated soil containment Additional subsurface investigations for Risk Assessment parkland property use area ( front lawn ) and to address MOE comments re Phase II ESA Submission of revised Reg. 511 compliant Phase I & II ESA reports for parkland property use area ( front lawn ) Reg. 511 Risk Assessment (RA) and Risk Management Plan (RMP) for parkland property use area ( front lawn ) Submission of Reg. 511 RA and RMP for parkland property use area ( front lawn ) to MOE Receipt of Director s Notice regarding RA and RMP for parkland property use area ( front lawn ) to MOE Review and response to Director s Notice and MOE comments regarding RA and RMP for parkland property use area ( front lawn ) Submission of revised RA and RMP for Reg. 511 Risk Assessment (RA) and Risk Management Plan (RMP) for parkland property use area ( front lawn ) Negotiation of Certificate of Property Use (CPU) with local MOE office and posting on EBR Registry for 30- day review period Filing of RSC for parkland property use area ( front lawn ) June 6, 2011 July 8, 2011 July 1, 2011 July 15, 2011 June 13, 2011 August 19, 2011 August 19, 2011 July 25, 2011 October 21, 2011 October 28, 2011 January 25, 2012 January 30, 2012 February 17, 2012 February 17, 2012 June 1, 2012 August 31, 2012 September 28, 2012 TZ Page 21