Tool 1: Physical Features
The purpose of the physical analysis of the site is to determine what opportunities and constraints are created by the conditions of the site. Those opportunities and constraints may rule out or discourage some uses, and encourage others. Key issues and opportunities for each of the physical condition areas listed in the table of site analysis elements are shown on the physical features checklist table below.
Physical Features Checklist
Environmental and Subsurface Conditions
In addition to the natural features that all sites contain, such as its hydrology and topography, vacant sites in older cities share a distinctive characteristic: with rare exceptions, they are all formerly built sites, and contain the residues of their former use. Formerly used parcels often contain environmental contamination and subsurface conditions resulting from their former uses.
Former industrial sites known as brownfields sites may contain environmental conditions which must be identified and often remediated before reuse is possible. Many former residential sites also have such conditions, such as lead contamination in the soil resulting from decades of proximity to automobile exhausts. In some cases, the cost of remediation for a planned reuse may be modest and easily managed; in others, it may make some reuse options, or reuse altogether, problematic.
A particular form of environmental problem found in many urban sites is unstable or problematic subsurface conditions arising from different historic practices. One is the widespread one-time practice of disposing of demolition debris on site, often by filling the basement with debris and covering it over with a thin layer of topsoil, leaving the debris under the surface. Another is the presence of unstable fill, common in urban sites near lakes or rivers, many of which were formerly wetlands raised and built during the 19th or early 20th century.
While all of these conditions can be corrected with enough money, given the financial constraints on development, they can become severe obstacles to many reuse options. They must be carefully evaluated before moving forward.