What’s all this about grading?
A few thoughts...
Time to explore a few ideas on topographic relief, and some of the opportunities it provides. While not an exhaustive look, it hopefully can start a dialogue. Comment as you like.
Grading is to the basic components of landscape as Hollandaise Sauce is to the five Mother Sauces of classical French cuisine.
Without going too far afield with a funky analogy, grading is one of the few fundamental elements in the design and construction of a landscape, just as a few sauces form the foundation of virtually all other sauces.
Other basic landscape elements include structures, plantings, water, and lighting.
One of the basic elements of landscape
For context, let's consider these other elements: structures can include curbs, walls, steps, ramps, furnishings, pavements, fences, or smaller out-buildings like sheds, cabanas, outdoor showers, and such.
We all know plantings can include partitions like hedges, hedgerows, and green walls. They provide surfaces like lawns and ground-covers and green roofs. Many purposes are met with specimen trees and shrubs, flower or vegetable beds, and wooded, naturalized areas that contain a little of everything.
Water in the landscape usually includes surface and underground drainage. Combining necessary functions with ornamentation could mean that we add fountains, runnels, swimming pools, outdoor sinks for cooking or utility, hot tubs, irrigation, and outdoor showers.
Lighting creates mood, it enhances safety, and it highlights specimens, monuments, and architectural features. Lighting provides directions and wayfinding, and it can add a sense of depth to a space.
And all of these, including grading, can contribute to the ornamentation of a landscape. They can each help to convey a sense of ownership or signature, engagement or exclusion. They offer intimacy or expansiveness, open views or introspection.
Simple and clean? Ornate and complex?
Let's talk about the function of grading, and the possibilities it affords, whether in a minimalist sense or more rooted in tradition.
Grading creates a specific slope, plane, curve, or pitch to the ground – be it planting beds, pavements, lawns, or any other open-air surface at grade.
This is not a technical review of grading. You might be interested how to grade effectively, what goes into drainage, what slopes are appropriate to which purposes, and how to represent all that with a grading plan. If so, then shoot over a note and I’ll offer suggestions that can get you going.
While working with the landscape architect Allain Provost, I contributed to the Parc Diderot project in Courbevoie, France.
The objectives at Parc Diderot were to manage a drop of about forty feet in one city block and to create a passable space for people on foot. The idea was also to make the entire space beautiful, to handle tons of water that passed through the site, and to create grounds for permanent recreational activities.
Steps rise on each side of the central water course, catwalks cross the water, walls retain the gardens, hedges accentuate the slopes. Grading is found in every aspect of the site.
Grading must be integral to the structures, the plantings, water, and the lighting that form a landscape. And when done well, grading serves many purposes:
- Grading directs water from places that should remain dry by implementing simple slopes or more complex swales or drains. If we’ve ever slipped on an icy patch, we might have wished it were graded better.
- Managing slopes also allows collection of water for ponds or retention basins;
- Controlling changes in elevation renders places accessible to automobiles, pedestrians, and wildlife. Grading allows plantings to gain a foothold on steep slopes with miniature terracing;
- Grading can save money through elimination of retaining walls in the design phases or during physical replacement;
- Moving up or down can create a sense of change of place and enhance the feeling of transition from one setting to another. A pocket-park elevated a few steps above a busy sidewalk is a great example. Those few steps up cause us to feel a real change of place.
- Manipulating the land can help to create vistas – think of the famous French chateau in Versailles.
- Here in the first photo, the lawn descends to a series of canals. The allées of trees at either side of the lawn are angled inward, so the lawn is actually narrower at the far end. This creates a forced perspective, making the end of the lawn seem further away.
- At the same time, because the lawn is pitched down and away, it appears to tilt the canals up in front of us. This seems bring them closer, even though we know the water must be flat.
- These tricks create mystery at the subconscious level. We engage with the space and it feels wondrous, even though we might not really know why. The canals then pull the eye toward the horizon, once again creating greater depth. This visual sleight of hand at Versailles was created in the 1670’s, a little over 300 years before Parc Diderot.
Relief, or change in elevations in a site, creates opportunities if you’re willing to seize them, and if the budget is sufficient to exploit them.
What about flat sites?
Ironically, the flattest sites are the most difficult to grade. Rarely are existing or proposed conditions actually flat. But when they are, the tolerance for error is tiny. We're forced to work with the shallowest slope to shed surface water.
In cases such as playing fields, underground drainage structures collect water that percolates straight down. But when no structures are possible, very careful work is required.
Grading is integral to the successful design and construction of a place, from both technical and aesthetic perspectives. We would be lost without it. Grading helps make spaces manageable, habitable, special, and appealing.