In many portions of the Southeast, forces prompting the development, redevelopment and adaptive reuse of urban property are in play. These forces include a marketplace that is placing greater importance on shorter commute times and the need for residential and commercial development within proximity to the central business district. These market forces work in tandem with economic forces that include tax incentives and “brownfield” legislation that promote infill and redevelopment opportunities.

For the purposes of this article, brownfield sites include not only contaminated properties but properties that are abandoned or underutilized. While market forces and economic incentives can be significant, urban projects can pose site development challenges not routinely encountered at suburban “greenfield” locations.

Site-specific civil engineering issues are basic to any development project. Urban redevelopment projects, however, tend to include unique factors associated with the retrofitting and compatibility with existing site and/or municipal systems. As-built information on the location and depth of water and sewer lines can be poor, and structures overlying utilities are frequently encountered. Compounding the assessment of site utilities can be the absence of onsite access, resulting in the need for remote evaluation (television camera, radio transmission), geophysical techniques and/or excavation.

The size, construction and condition of municipal utilities can offer challenges for urban development. Routinely, storm sewers or combined sewers may not be sufficiently sized for current design criteria, which may require additional isolated detention and pretreatment of storm water; extreme cases may result in the developer undertaking repairs and modifications to municipally owned systems in order to proceed with the project. Combined sewers (sewers that carry both storm water and sanitary wastewater) require the design professional to plan for both current and future use. Inlet traps and backflow devices may be required to prevent sewer gases and sewer contents from infiltrating site storm water structures. Furthermore, design and construction of site storm water connections need to consider the ease of connecting to a separate municipal storm sewer system in the future.

By their nature, infill and urban redevelopment projects are typically size-restrictive. Size constraints may lead to easement issues with regard to utilities and public access thoroughfares. Traditional easements may not be compatible with site development, resulting in reducing usable square footage. To achieve the required site density and avoid taller structures, the use of deeper building foundations can be considered. Deeper foundations allow for the repair of utilities without the need for more expensive sheet piling or other construction techniques to avoid structure impairment should the utility need to be accessed for maintenance or reconstruction.

While cities promote infill and redevelopment of urban areas, New Urbanism planning and zoning requirements can restrict usable site area. These include increased open space to impervious surface ratios, ease of access to pedestrian walkways and public transportation, and on-grade parking restrictions. These design elements and/or permit requirements result in the need for site planning innovation to avoid reduced density or taller, more expensive structures.

The majority of developers are well aware of the need for environmental due diligence. Property acquisition in urban centers typically raises the stakes for thorough and comprehensive environmental due diligence and developers should anticipate the additional time and cost associated with these activities. A significant quantity of urban properties can be expected to have housed or be located within proximity to present or former commercial (petroleum retail, dry cleaners) or industrial operations that have the potential to result in subsurface contamination. Due diligence in urban areas, therefore, more frequently extends from the typical Phase I Environmental Site Assessment (ESA) to a Phase II ESA in order to quantify site conditions.

Adaptive reuse of older, existing structures presents the developer with additional due diligence concerns and potential long-term liability. Most developers and property owners are familiar with issues associated with asbestos-containing materials (ACM) and lead-based paint (LBP). All states in our region have well-developed programs regulating the characterization, abatement and disposal of ACM and LBP. Less well defined and frequently overlooked are regulations regarding structural building components (brick, concrete, wood) that have been impacted by long-term exposure to regulated materials during past site usage. Even less understood, and with little if any current regulatory control, is mold, which is rapidly becoming a litigation and insurance concern in our region.

Brownfield classification and various insurance instruments can soften the environmental liability associated with urban development. These factors, however, do not relieve the prospective landowner from conducting the appropriate due diligence, if for no other reason than to estimate cost and conduct planning associated with any environmental conditions directly impacting site development. Furthermore, brownfield agencies and insurance companies, as well as other public agencies (HUD, Local/State Department of Community Affairs) that may be involved with a project, will likely have their own due diligence requirements.

Urban redevelopment and infill projects offer opportunities and challenges to both the developer and design professional. In these efforts, the utmost importance should be placed on both the civil and environmental due diligence. Thorough due diligence will improve accuracy of pro forma site evaluation and minimize unanticipated site development expense.

Chris Harrell, PE, and Chris Brown of Highland Engineering Inc. in Atlanta contributed to this article. Harrell is a principal, and Brown serves as senior project manager and environmental engineer.


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