“They paved paradise, and put up a parking lot.”
– Big Yellow Taxi
The early 1970’s, when this song premiered, were a time of environmental awakening for our nation. Green was good; asphalt was bad. Indiscriminate building activities were frowned upon by environmentalists who worried that the country was becoming over-developed. Protesters chained themselves to trees, marched against industries, and boycotted environmentally dangerous products. Today, however, some have come to realize that “paving paradise” is an option to be considered. Not all development is harmful to the environment. Planned developments are beneficial and can actually enhance environmental conditions at a site.
Present geo-environmental thinking considers various approaches in utilizing land and building developments to cap contaminated sites. This is illustrated in the following scenarios where different levels of environmentally friendly design can be utilized to help soil, air, and water resources.
Site A is a clean site. Subsurface investigations have shown no contamination by previous landowners or operators. With input from the landscape architect and architect, development plans maximize the green space on the site. Roof runoff is piped directly to inlets and stormwater conveyance systems. Runoff from parking lots and driveways is diverted through grassy lawn areas and earth swales, filtering petroleum residue and sediment contaminates prior to entering retention ponds where collected stormwater can percolate into the natural ground water regime. Environmentalists appreciate Site A’s common-sense design and consideration for green spaces.
Site B is a partially contaminated site. Years ago, industrial waste and by-products were improperly dumped onto a corner of the tract, leaving approximately one quarter of the site unusable for green space. A Phase I Environmental Assessment and subsequent laboratory testing has shown a heavy concentration of Total Recoverable Petroleum Hydrocarbons (TRPH) and coal tar in the soil which cannot be completely removed. Since rainwater should be prevented from percolating through the contaminated soil and entering into the ground water regime, the architect, in consultation with a geo-environmental engineer, may recommend locating the building over the contaminated area. Engineers would then include vapor barriers and vapor recovery systems in the design to prevent moisture penetration and petroleum or other chemical fumes from filtering into the building. Runoff is routed away from the contaminated area. In addition, parking lots may be purposely located in this area to further cap the contaminated land. Landscape design utilizing pavers, plastic liners, underdrains, mulch covers over clay, and special plant material (tolerant to TRPH contamination) are another capping option. This capping approach to controlling surface infiltration allows a contaminated and formerly unusable site to be fully developed and/or transformed into a landscaped, protected green space.
Site C is every environmentalist’s nightmare. Contamination is everywhere and includes chlorinated solvents, coal tar, and leachable metals. Total clean-up is not practical. However, this abandoned property as it presently exists is more dangerous to the environment than if it were to be developed. Why? On an extremely contaminated site, rainfall filters through the contaminates, which are then carried through the soil to the ground water regime where these substances infiltrate and contaminate domestic water systems. Capping 100% of the site would be recommended for the presumed levels of contamination described for Site C. While this can result in massive building, parking lot, and sidewalk site coverages with limited or no green space, surface runoff from the site can be intercepted and piped safely to a lined stormwater detention basin, minimizing surface water percolation. Hence, contaminates do not enter the ground water regime. In this case, paving paradise is definitely an option to consider!
When property is under consideration for purchase, geotechnical and environmental engineers should be the first consulted. Whether contracted by developers, contractors, corporate real estate departments, or other engineers and architects, their input is critical to proper design and assessment of development feasibility. Buying, selling, and transferring property has become increasingly complicated. Most banking institutions and insurance companies require an environmental assessment and sometimes a geotechnical evaluation of a proposed purchase prior to settlement on the property.
Within JDBE, geotechnical and environmental engineers have combined forces to benefit the natural environment and our clients’ construction budgets. Not only does this joining of forces avoid the duplication of efforts in land assessments, design, and planning, but geo-environmental specialists are able to envision the complete development potential as opposed to focusing on only a narrow scope. For example, geotechnical and environmental assessments can assist a structural engineer in developing adaptive foundation designs, assist the architect in building placements and layouts, and provide guidance to a contractor for efficient earthwork operations, while still addressing remediation issues and incorporating environmentally-friendly land development designs.
A team effort within the design community is necessary. Often, one of the major hurdles in a land development plan is the approval process. To be approved, every land use plan must conform to an array of federal, state, county, and local regulations. A wide range of issues must be addressed and resolved, especially if contaminates are involved. A geo-environmental consultant with a thorough knowledge of governmental procedures and regulations can work with the architect and land development engineer to expedite projects through the potentially multi-layered approval and permitting process. Not only can this team effort save money and time, it also helps to optimize and fully develop the land. The team is able to develop an environmentally sensitive design which improves the landscape and helps cleanse our waterways and ground water drinking supplies.
Today we face increasing concerns about our fragile environment. The public demands a clean environment in harmony with nature. Government regulatory agencies are increasing enforcement and imposing severe penalties for non-compliance. Business owners, lenders, and buyers are now aware that environmental management makes good business sense. To the environmentalist, paving paradise may not be the most attractive path, but when considering a contaminated site, it is sometimes the only path to take.