The sites on which landscapes have been created have been modified by grading and construction activity resulting in a new altered soil surface layer of mixed, contaminated soil. The characteristics of a healthy, functioning soil are significantly altered during the site development process. "As soil is relocated on the site, taken away, and added to, the natural horizons are mixed and altered. Through this process a new layer is created that blends existing textures creating a heterogeneous and structureless soil."(Harris 1999)

Today, compaction is the biggest problem in dealing with the urban soil environment and has led to various impacts both on-site and off-site. Compaction is caused by various factors such as machinery and foot traffic. Compaction is not only a result of compression; it happens more specifically when delicate aggregates are broken down. The break down of these aggregates, which form the soil structure, is most susceptible when it is wet. "Water causes aggregate cementing agents to become more fluid so soil particles slip into positions that take up less space. Once the soil is saturated it cannot further be compacted, but localized disturbance, of tire compression from heavy machinery, will shear aggregates apart and rearrange the particles. These puddled surfaces that remain upon drying, shrink and become compacted." (Harris 1999)

Within the construction process, many aspects contribute to soil compaction, taking place within the grading limit. Phillip Craul, Senior lecturer in Landscape Architecture, Graduate School of Design, Harvard University says that "soil specifications for contractors in the past have been superficial and incomplete at best." He also states that "there is a greater sensitivity to the requirements of sustainability" and that we as landscape architects need to "Say no" when becoming a loser to construction cost overruns that filter down, ultimately creating low quality soil management practices. The soil is the foundation for our designs and landscape architects are taking liability for the success of these landscapes dependent on properly functioning soil systems, yet steps aren't being taken to ensure quality.

The general purpose of grading soil within the construction site is to reduce the voids within the soil structure. Whether it is cut or fill, mechanical compaction is necessary to stabilize the subgrade for building, but the effects of heavy equipment such as trucks, backhoes, and grading equipment incur compaction at about 6 to 8 inches in depth, at which point the soil is so wet that it flows from under the tires where compaction occurs at much greater depths. Meanwhile, areas adjacent to construction activities are losing their indigenous properties. Contractors are affecting the whole site during construction. Existing trees can be severely impacted, future plantings can be severely impacted, and future stormwater management practices can be significantly altered as a result of a non-functioning soil. This upper layer of soil is where most of the processes take place. New standards need to be set and awareness needs to spread throughout the landscaping profession about the importance of natural process, especially in our urban environments.

A required understanding of natural soil profiles and the native ecosystem are a good beginning place. Native soil profiles consist of about 4 to 6 percent organic matter whereas imported topsoil typically run 15% by weight and 33% by volume organic matter content in the mix. Topsoils are designed soils, focused on maximizing drainage and compaction prevention. With higher levels of organic matter in the soil mixture the soil is more vulnerable to compaction. As the organic material decomposes the soil pore space can be reduced when the soil is compressed. So it is as important to know your sources of topsoil as it is to know the correct ways to apply it.

"Additions to the soil profile are best installed by horizon to make certain that the materials are in proper sequence and horizontally continuous. Wide variations in horizon thickness and presence of discontinuities are not acceptable for a designed soil. Standard specifications as written do not ensure uniformity of soil structure upon installation. Because of differentiation of deposition of material and compaction in the spreading process, greater uniformity of the material can be obtained by placing the soil in 4 to 6 inch lifts." (Craul 1999)

Homogeneous topsoil mixes decrease development costs, but may not provide optimum soil conditions and may compact over time. Fitting horizons together and understanding soil interfaces is important because sharp contrasts in bulk densities are the result of not designing the right textural combination. Mixing interfaces not based on ideal soil properties will result in a failure to the system. The importance of careful placement of the soil materials and the sequencing of operations cannot be overemphasized from a successful installation and the sustainability of the design. Designed soil profiles presents higher costs and more challenging applications but carry a greater potential for success both for on-site and off-site plant communities and water retention ability.

Another procedural element in the construction process is storage of soil material. All soil material, whether it is topsoil from the site or imported fill must be stored properly. General specifications designate areas for topsoil storage but no steps are taken to ensure that soil retains its functioning properties. Craul states that only the amount of soil that can be use within a few days should be brought to the site, furthermore no soil should be stockpiled at heights over six feet because anaerobic conditions can occur. Soil should never be handled during wet periods and should be kept moist at times but not be exposed to rainsplash for purpose of protecting from erosion and loss of aggregate stability.

The order at which the soil is placed on site and graded is important. To prevent further compaction after grading install soil in a way that prevents backtracking over already installed areas. Starting in the center of the site is a good option if there is ample access around the perimeter of the site. Also moving in a successional pattern across the site from one end to the other can help to prevent further compaction.

Further steps can be taken to install planting such as trees on compacted pedestals that support root balls and bring in soil around them while grading. This will prevent further compaction during the construction process as well as provide a good porous structure that will allow infiltration and aeration. When installing soil set rough grade levels then irrigate for two weeks to allow for the soil to naturally settle and reduced the major voids, then once it has settled do the final grading.