Brownfield Opportunities
09/05/2005
by -- David Harper
Facilitating urban renewal is possible using an integrated environmental site management strategy.
Revitalizing the thousands of abandoned, vacant, derelict or underutilized former industrial/commercial properties idling within our urban core is an opportunity to facilitate renewal and reduce sprawl. This opportunity can only be realized if a successful environmental site management strategy is integrated into development options that ultimately satisfy all stakeholders, including owners, the community, regulatory agencies and financers. While each brownfield site has its own specific environmental issues, there are a number of common elements that characterize brownfield sites from Greenfield development. They include the following:
* Former industrial/commercial site with established location and infrastructure
* Site market value neutral or negative
* Various historical site usage with unclear site management practices
* Site restoration technically challenging and/or cost prohibitive
* Soil and/or groundwater impacted by former operations
* Remaining site infrastructure including wastes and building materials
* Stigmatization and liability concerns
To address these brownfield characteristics, a successful integrated site management strategy typically consists of determining the appropriate cleanup standards, alignment of site development and remedial objectives, demolition and source removal, material segregation and recycling, site monitoring and management. Environmental assessment/remediation programs that are comprehensive and follow established protocols and procedures are important considerations.
In general, it is not practical or cost effective to know all the site conditions that may be associated with the brownfield. These risks can be managed by the preparation of an integrated site management strategy that addresses widespread concerns, responds to changing site conditions and establishes appropriate contingencies. There are also a number of insurance products available to help mitigate brownfield risks.
Brownfield Case Study: Former Heavy Industrial Manufacturing Site
A 40-acre site is located in the greater Toronto area and had been used as a heavy industrial manufacturing site since the early 20th Century. In the 1990s, the site was demolished to grade and during the site decommissioning activities various Phase I and II environmental site assessments were conducted by the owner to determine the soil and groundwater quality at the site. As expected, with many long-standing former industrial uses, the subsurface investigations indicated that the site was widely impacted by both organic (volatile organic compounds) and inorganic (metals) parameters. There were also many localized petroleum hydrocarbon impacts to soil and groundwater. Similar impacts were also observed beyond the property boundaries at some locations. Some of the properties surrounding the site were also historically industrial and may have contributed to potential impacts to soil and groundwater quality.
The corporation in control of the site was in bankruptcy protection, but the site with its environmental liabilities still needed to be addressed. Many initial developers taking an interest in the site in this "as in" condition considered the site for residential redevelopment to maximize their investment return. However, these objectives were not aligned with municipality and the local community interests -- redevelopment to light manufacturing and commercial use. In addition, the site's current environmental conditions made it challenging to achieve the more stringent residential cleanup requirements.
Site Revitalization
Realizing the community potential, a developer and potential tenant were willing to negotiate with the insolvent owner for the site and its planned use. The lands would be purchased at a below market value that considered the estimated cleanup costs associated with industrial/commercial redevelopment.
For the site development to succeed from a financial perspective, it was necessary to develop an integrated environmental site strategy. An environmental consultant was retained to develop the integrated site management strategy for the site. This person determined that the 40-acre site could be segregated into various parcels for development depending on the nature and extent of the soil and groundwater impacts. Appropriately 15 acres of the site could be remediated to Ontario Ministry of the Environment (MOE) generic cleanup standards for industrial/commercial use during the construction of a proposed development that would include a slab on grade building (160,000 square feet) to accommodate the tenants needs of transfer and warehousing operations. The remaining 25 acres of the site would be managed by source removal and risk assessment. The income generated from the initial 15-acre development would assist the implementation of a remedial plan for the remainder of the site.
Integrated Environmental Site Management
The integrated environmental site management strategy for the initial transfer and warehouse operations included the excavation of impacted soils and treatment of associated groundwater during the removal of remaining concrete and below grade infrastructure. This approach was attractive since soil excavation was already required as part of the development process. Soil excavation is also the most direct and timely method to address environmental impacts.
Approximately 80 to 90 per cent of the site was covered with concrete and it was important to recycle these materials on-site since the development required engineered fill materials. Also soils that were below the appropriate generic standards would be beneficial for reuse on-site, provided they fulfilled geotechnical requirements. Site activities were led by a design build contractor who planned to deliver the site redevelopment within an estimated 10-month time frame. During the site preparation and remedial activities, the developer and the environmental consultant conducted discussions with the MOE to address the known off-site impacts and continuation of a previously established site monitoring program. Specifically, a reactive barrier was to be installed along the property boundary to treat groundwater impacted by volatile organic compounds. The development and installation of this mitigation approach required licensed technical expertise.
During the below grade demolition and former infrastructure removal, various test pits were completed across the site to guide the remedial and geotechnical programs. Like all brownfield sites, various unknown conditions at the site existed. For example, building wastes were buried during the initial demolition and placed within the remaining infrastructure. These materials were characterized and disposed off-site appropriately. In addition, the average thickness of concrete was much greater than originally expected and many large concrete piers had to be addressed to prevent differential settlement during site redevelopment. Shallow fill materials, a shallow groundwater table and winter conditions strongly affected the suitability of near surface soils based on geotechnical considerations.
Before reuse, the soils had to stripped and stockpiled until the moisture content was reduced. Any impacted soils identified during the previous environmental assessments or the supplemental test pit program were stock piled separately for further evaluation and disposal/treatment options. The supplemental test pits successfully reduced the extent of the remedial soil excavation program from preliminary estimates of 20,000 cubic metres to 10,000 cubic metres, and assisted in management of soils on the site.
Shallow groundwater impacted by volatile organic compounds encountered during site excavation activities was contained on-site using an existing below grade holding tank. Impacted groundwater was subsequently treated and discharged to the sanitary sewer in accordance with all municipal requirements. Supplemental groundwater treatment was required in one area and consisted of chemical oxidation. The supplemental groundwater treatment program was completed following all MOE requirements.
The soil excavation and remedial program was completed in conjunction with other site preparation activities. Material management from both environmental and geotechnical perspectives was a key issue throughout initial site preparation because of the costs associated with importing engineered fill. However, with the high moisture content of shallow soils and an accelerated construction schedule through the winter months, it was decided that engineered fill would be placed within the building foot print. The parking and drive areas could be completed later in the schedule, giving the on-site recycled material an opportunity to dry. Any remaining soil could be incorporated into the landscaping features of the site.
Material reuse also included approximately 40,000 cubic metres of concrete that was excavated, crushed and recycled on-site. Concrete crushing operations and soil excavation were completed concurrently and air quality was constantly monitored and sampled. Air quality and noise were the most important issues for local residences neighbouring the site. Most of the earth works and crushing operations were completed during the colder weather when the windows of the adjacent residences were closed.
At the same time as the initial site development, the installation of the reactive barrier was completed along property boundaries. The barrier also consists of low permeable sections to help direct shallow groundwater flow and prevent any migration pathways through former utility areas. All soils excavated during the installation of the reactive barrier followed a similar material management strategy as designed for the site development. The installation of the barrier needed to be precise because of high costs associated with the reactive media (>$1000/metric tonne). Monitoring wells were also incorporated in the barrier design to monitor and manage its ongoing performance. This mitigation technology was favoured over other engineered systems because of the relative low ongoing operating and monitoring costs. The barrier was placed along the site boundary and will not significantly influence future development at the site.
The next major environmental task for the remaining 25 acres is to complete an MOE-approved risk assessment and source removal program. This work should be completed over a 12-month period.
At present the initial site development project is approximately 80 per cent complete and is following the anticipated construction schedule. In addition to the revitalization of this brownfield site, the developer and their tenant have elected to also construct the building to meet sustainable building strategies following the Leed Certification program. This demonstrates the developer's leadership qualities and meets the goal of taking this former brownfield site to an exceptional standard in the revitalization of this community.
David Harper is the Area Manager at Jacques Whitford in Oakville, Ontario. He is also a member of the CBN Advisory Panel.
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