To: New Edinburgh Community Alliance From: Stantec Consulting Ltd. File: CSST Date: November 18, 2016

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1 Memo To: From: Stantec Consulting Ltd. File: CSST Date: November 18, 2016 Reference: CSST Site 5 Material Excavation and Management Requirements The purpose of this memorandum is to provide an overview of the material excavation and management requirements at Site 5 (Stanley Park) of the Combined Sewage Storage Tunnel (CSST) project. In response to a question posed at a meeting with the New Edinburgh Community Association on November 2, 2016, we also provide in this memo some examples of our experience managing work at contaminated sites in Ottawa. BACKGROUND The CSST is one of the most important projects of the Ottawa River Action Plan (ORAP), which is the City of Ottawa s roadmap to protect the Ottawa River for future generations. The CSST will greatly reduce the frequency of sewage overflows entering the Ottawa River, which is required by the Ministry of the Environment and Climate Change. To help the City meet this goal, Stantec completed an environmental assessment (EA) that identified and developed a preferred solution to provide additional storage facilities in the combined sewer area. Alternatives considered were various combinations of localized or interlinked combined sewage storage tanks, deep tunnels, and other forms of linear storage facilities. The evaluation identified deep tunnel storage through the core combined sewer area as the best value solution. SUMMARY OF ENVIRONMENTAL SITE ASSESSMENT PROCESS FOR CSST During the environmental assessment for the CSST, Stantec completed a qualitative assessment of possible environmental concerns associated with the CSST alternatives. The possible environmental concerns were assessed through a modified Phase I Environmental Site Assessment (ESA) process, which included a search of the available pertinent historical information and a site visit to identify potential environmental concerns from field observation. Qualitative criteria were used to rank the sites as significant, moderate or minor according to the level of environmental concern associated with each site. The ranking system was designed to evaluate the alternatives based on the potential to encounter soil or groundwater contamination. Stanley Park was ranked as significant because there were known environmental impacts from historic activities at this location, because additional investigation would be required during design and because contaminant impacts to soil and groundwater could present technical risks to the construction of the CSST, such as elevated costs to manage contaminated material. During detailed design, Stantec completed an ESA, with soil and groundwater sampling, to identify and evaluate the environmental concerns associated with the CSST construction at each site, including Stanley Park. Borehole drilling and logging, as well as the groundwater monitoring well

2 Page 2 of 7 installation, was undertaken by Golder Associates Ltd. The analytical results from the samples were compared to the Ontario Standards to assess soil management options. The environmental sampling completed for the CSST project focused on areas where the CSST infrastructure is planned to be constructed. The intent of the sampling for the CSST project was to provide the contractor with information on the quality of the soils and groundwater where construction is proposed. The contractor will use this information in the development of their management plan for excavated materials. SUMMARY OF ENVIRONMENTAL SITE ASSESSMENT FINDINGS FOR CSST SITE 5 The following provides a summary of the information reviewed or collected for Site 5 and Bordeleau Park. Stanley Park Prior to the EA for the CSST, a Phase I ESA and screening level risk assessment (SLRA) were conducted in The SLRA recommended completing a detailed delineation of the impacts followed by a quantitative human health and ecological risk assessment due to moderate health risks being identified for adults and children visiting the park. Soil and groundwater sampling was conducted in 2008 for a Human Health and Ecological Risk Assessment (HHERA), which characterized the risk to park visitors, park maintenance workers and adjacent residents. The risk to adjacent residents was calculated based on continuous exposure to airborne dust with maximum concentrations of contaminants over a lifespan of 80 years and the result of the HHERA indicates that the level of risk is well below what is considered unacceptable. The recommended remediation of Stanley Park was based on the calculated risk to park visitors and park maintenance workers, assuming continuous exposure to the soils over a lifetime. The remediation consisted of the removal of selected trees and vegetation, excavation of contaminated soil to create drainage swales, and capping of the property with clean soil cap placed directly on the contaminated fill. During the design of the CSST, soil and groundwater samples were collected from two locations in Stanley Park. The soil samples collected contained concentrations exceeding the Ontario Table 1 or Table 3 Standards for one or more of the following parameters: metals, volatile organic carbons (VOCs) and polycyclic aromatic hydrocarbons (PAHs). Groundwater concentrations did not exceed the Ontario Standards. The environmental information provided by the NCC for Stanley Park indicates that soil impacts were identified in the upper 30 centimetres of soil, prior to placement of the cap. The soil sampling completed by Stantec for the CSST project suggests that soil impacts extend to at least 2.1 metres below grade. We have made a conservative assumption that soil impacts may extend to the bedrock surface.

3 Page 3 of 7 Intersection of Queen Victoria and River Lane During the design of the CSST, soil and groundwater samples were collected from the intersection of Queen Victoria Street and River Lane. The soil sample collected contained concentrations exceeding the Ontario Table 1 or Table 3 Standards for the following parameters: VOCs, petroleum hydrocarbons and PAHs. This sample was collected from 2.3 to 2.6 m below grade. We have assumed that it is representative of the soil quality from surface grade to bedrock. Groundwater concentrations did not exceed the Ontario Standards. Bordeleau Park According to the previous reports reviewed, a Phase I ESA, Phase II ESA and SLRA were completed between February 2004 and October 2005, to address environmental concerns of the soil and groundwater quality at Bordeleau Park due to historical activities. The contaminants found in soil included metals, PAHs, and benzene, toluene, ethylbenzene and xylenes (BTEX); groundwater contaminants identified included metals and PAHs. The SLRA did not identify unacceptable health risks to park visitors, park construction workers or park maintenance workers, or unacceptable ecological risk to terrestrial receptors from the contaminants identified in the Phase II ESA. The groundwater sampling data did not indicate any adverse effect on the Rideau River. QUANTITIES OF EXCAVATED MATERIAL As previously stated, we have made a conservative assumption that soil impacts may extend from the ground surface to the bedrock surface. Table 1 provides a summary of the Site 5 soil excavation activities based on the above assumption, the diameter of the excavations and the depth to bedrock, and the contractor s planned construction sequence. Table 1. Summary of CSST Site 5 Soil Excavation Location Soil volume (cubic metres) Number of trucks 5a Stanley Park Tunnel Access Shaft 5b Stanley Park Diversion Sewer Access Shaft 5c Queen Victoria Street and River Lane Trucks per hour Duration 2, to 4 3 to 4 weeks to 4 3 to 4 days To be determined (possibly 2 to 3) To be determined (possibly 2 to 3 days) It is estimated that truck traffic carrying potentially contaminated soil will pass through the neighbourhood periodically for up to approximately a month and a half. Trucking will be carried out between the hours of 7:00 am and 10:00 pm and will be along designated truck routes. As noted previously, an HHERA characterized the risk of exposure to the contaminated soil in Stanley Park based on continuous exposure to airborne dust at maximum concentrations of contaminants over a lifespan of 80 years. The result of the HHERA indicates that the level of risk is well below what is considered unacceptable.

4 Page 4 of 7 If the tunnel mucking shaft was shifted from Stanley Park to Bordeleau Park, there would be a requirement to excavate an additional approximately 1,400 cubic metres of potentially contaminated soil. The soil excavation in Stanley Park would still be required to build the outlet chamber to attenuate flows, the connection chamber to the existing Interceptor Outfall Sewer, and the diversion sewer to collect combined sewage that would otherwise overflow into the Ottawa River from the Rideau River Collector and convey it to the CSST. MANAGEMENT OF EXCAVATED MATERIAL Contractor will produce a detailed soil, groundwater and rock management plan for Site 5 that will include the following as a minimum: Health and safety requirements Testing and sampling procedures further characterization of the subsurface material will be completed as excavation commences to determine the requirements for disposal of excavated material. If offsite disposal of suspected contaminated material is required, the soils to be removed from the site will be tested for BTEX, PHCs, VOCs, PAHs and metals prior to haulage off site for disposal. Identify area and procedures where stockpiling of material and soil segregation will occur (including ensuring that suspected or contaminated soil does not impact other soils by use of a liner or containment). Identify the fill and waste receiving sites including permission from the Owner of these sites. Handling and hauling of waste materials must comply with the requirements of O.Reg.347. Specific conditions, as recommended in the MOECC Guideline (Management of Excess Soil A Guide for Best Management Practices), include the following: A traffic control plan that identifies the access/egress route of the trucks, truck queuing and parking locations, dust control measures and haul routes between the source site and the receiving site. The Contractor will employ covers on the back of the dump trucks when leaving site, which is typical practice regardless of whether or not the soil is contaminated. Dust control is required under the CSST contract by use of water and a truck wash station is required. For hauling of waste material or excess soil from the site, the Contractor is required to keep a chain of custody of material leaving the site (i.e. they know what material was hauled, where it was stored or transported to and can confirm the quality of that soil and it s acceptability at the receiving site). Specifically, each load must be accompanied by documentation signed by the Contractor s qualified person that includes appropriate and representative soil analyses from the soil at the Source Site confirming the soil quality is acceptable for storage at a receiving or temporary soil storage site. The Contractor will keep any written documentation from the receiving or temporary soil storage site confirming that the soil was received and the quality and quantity were acceptable for an intended reuse.

5 Page 5 of 7 EXPERIENCE WITH MANAGING EXCAVATION AND HANDLING OF CONTAMINATED SOIL Stantec has completed a variety of projects in the City of Ottawa. These projects have included Phase I ESAs, Phase II ESAs, Phase III ESAs, contaminant assessments, delineation and remediation, qualitative risk assessment, hydrogeological modeling, and groundwater contaminant management and remediation. Contaminant assessments have addressed VOCs, total petroleum hydrocarbons, PAHs, and inorganic parameters such as metals. Stantec completed these projects as a prime consultant on an as-needed basis (e.g., Phase I, II, and III ESAs, remediation, and tank removal activities for the City s Real Property Asset Management group), and as a sub-consultant to other engineering firms coordinating multi-disciplinary projects (e.g., Rideau Canal pedestrian bridge, Munster sewage pipeline, and numerous road right-of-way projects). Two examples of our work managing work at contaminated sites in or near residential communities in the City of Ottawa are attached. We hope this addresses your concerns regarding the volumes of contaminated soil we anticipate, our findings during the EA and design, how the material will be managed, and what our experience is with managing excavations in contaminated sites in Ottawa.

6 Page 6 of 7 Natural Resources Canada Headquarters Booth Street Complex Environmental Remediation Project Natural Resources Canada s (NRCan) Booth Street Complex (BSC), located in Ottawa, Ontario, has been home to a multitude of occupants since the mid-1900s, including NRCan headquarters, research divisions and laboratories, land mapping, private and public rental space, commercial areas, and a daycare. Prior to NRCan s presence, the site had been contaminated by numerous industrial and commercial site uses, rail yards and backfilling of the property with fill of unknown origins dating back to before Added to this historical contamination were impacts from NRCan s laboratory activities on site, in an era when waste management practices were not understood or regulated in terms of their environmental impacts. Contamination included numerous heavy metals, petroleum hydrocarbons, VOCs, and various other compounds. The BSC property has an area of approximately 120,000 m 2 and is located in central Ottawa. The Federal Government is redeveloping portions of the complex, and in order to do so, a major environmental remediation project was initiated in Since 1992, over 16 studies have been carried out by at least ten different environmental consultants to assess the extent of contamination, and to determine the best approach for remediation. The remediation involved excavation and removal off-site of approximately 121,284 metric tonnes of contaminated soil. Between 2008 and 2010, Stantec Consulting Ltd. (Stantec) was commissioned by NRCan to summarize all existing reports, perform a gap analysis, update site data to current environmental standards, conduct additional assessment as necessary, complete a review of remedial options, complete an environmental impact assessment (CEAA EA) with public consultation, prepare a conceptual remedial action plan, prepare engineering specifications and drawings for selected quadrants of the site, and monitor the remediation work of multiple environmental consultants and contractors in collaboration with NRCan and Public Works and Government Services Canada (PWGSC). Because of the variety of contaminants on site, the requirement to keep the complex in full operation and the short time available to complete remediation, an engineered excavation and landfilling of contaminants was selected as the preferred remedial approach. Many factors contributed to the complexity of this remediation project, requiring innovation and advanced applications of engineering principals. The schedule of the project required much of the work to be completed in winter conditions and the health and safety of the building occupants and the general public in the community was of utmost concern. All remediation work had to be completed while keeping the facilities in full operation and protecting the health and safety of over 3000 building occupants. Operational areas included numerous NRCan laboratories with sensitive air quality and vibration control issues, offices, commercial areas, and a children s daycare. Potential

7 Page 7 of 7 risks to humans and the environment were assessed through the EA process and a comprehensive mitigation plan was developed and implemented to address these risks. Mitigation measures included extensive testing of air, soil, groundwater and dust throughout the remediation efforts. A team approach to rapid problem solving was coordinated by PWGSC to come up with the best solution in the least amount time, when unknown site conditions were encountered. A key to the project s success was the collaborative approach taken by all stakeholders, consultants and contractors. Contractors and consultants were hired by PWGSC to remediate the quadrants and monitor the work respectively. Stantec maintained a role throughout the project, working on behalf of NRCan as an Independent Engineer to assess the extent of remediation, conduct an Environmental Impact Assessment, provide public consultation, design the remediation for two of the four quadrants, monitor the work of other consultants and the contractors in accordance with the design intent, conduct independent testing of soil, groundwater, air and dust and to assist with multi-disciplinary solutions to problems encountered on site. Stanley Park Remediation Project Stanley Park is composed of approximately 5.6 hectares (ha)of open space along the east shore of the Rideau River, adjacent to the New Edinburgh community. The majority of the park (3.6 ha) is owned by the National Capital Commission (NCC), with the remaining area (2 ha) owned by the province. It is believed that the provincial lands resulted from historic filling between two small islands within the Rideau River. The NCC has historically managed these provincial lands. Past land uses within the project area include a former railway crossing of the Rideau River, potash storage and a domestic landfill. Recent and on-going environmental site and risk assessments initiated by the NCC have revealed that contaminants of concern (COCs) are present within Stanley Park. Phase I and II ESAs, Screening Level Risk Assessments and an HHERA have identified COCs which include heavy metals, PAH, PHC contaminants and potentially dioxin/furans in groundwater. Recommendations from the Risk Assessment include the placement of a clean fill cover over contaminated park areas to prevent human exposure to the COCs. In 2009, Stantec Consulting Ltd. (Stantec) was commissioned by the NCC to review existing reports and remedial options, complete an environmental impact assessment (CEAA EA) with an archaeological assessment, prepare site plans, landscape plans and stormwater management strategy, prepare engineering specifications and drawings for the site, including special procedures for contaminated sites in collaboration with NCC and other consultants. The remedial option selected for Stanley Park was to cap the site with granular fill and construct/repair a fence along the northern property line. This remedial option included excavation and removal of approximately 240 cubic metres of contaminated soil. Monitoring during the remediation was completed by Geofirma. Results of air monitoring by Geofirma during the remediation did not indicate a risk to human health from airborne lead, total suspended particulates of PAHs on the site or at the property line.