Glossary
The words that turn up on a landscaping quote
Some of these are horticultural, some are construction, and several are specific to the ordinances that govern work in this city. All of them are worth recognising before somebody uses them across a kitchen table.
- Aggregate base
- The layer of graded crushed stone under a patio, walkway or wall. Placed and compacted in thin lifts, it is what carries the load on clay subsoil. Most of the cost of a hard surface is here and none of it is visible when the job is finished.
- Amendment
- Organic or mineral material worked into soil to improve structure. On Piedmont clay it works across a whole bed and fails when confined to a planting hole, because an amended pocket surrounded by clay behaves like a container.
- Batter
- The backward lean built into a retaining wall, usually expressed as a setback per course. It puts the wall into the hill rather than standing it vertically against the load.
- Bed line
- The edge between planted bed and lawn. On a wooded lot it should follow the real canopy line rather than an arbitrary curve, because the canopy line is where the light budget changes.
- Cecil series
- The reference soil of the Georgia Piedmont and the Georgia state soil. A sandy loam surface over a red clay subsoil weathered from felsic igneous and metamorphic rock, classified as fine, kaolinitic and thermic, well drained, and rated low for shrink-swell.
- Compaction
- Loss of pore space in soil, from traffic, machinery or working the ground wet. Deliberate under a base course, damaging everywhere else. The thin surface layer that makes Piedmont ground plantable does not survive it.
- Critical root zone
- The area of soil around a tree that contains the roots it depends on, extending well past the drip line. Digging, tilling, compacting or raising grade inside it is how mature trees are lost slowly.
- Cycle and soak
- Splitting an irrigation run into two or three shorter cycles with rest between them, so application never exceeds what the soil can absorb. On clay absorbing around half an inch an hour, this is the difference between irrigation and runoff.
- DBH
- Diameter at breast height. Trunk diameter measured at 4.5 feet above ground, and on a slope measured from the highest ground point at the base. The figure that decides whether a tree removal permit is required in Sandy Springs.
- Daylight
- To bring the end of a drain pipe out to open air at a lower elevation so it discharges by gravity. A drain that does not daylight somewhere real is a drain that fills up and stays full.
- Drip line
- The line on the ground below the outer edge of a tree canopy. A rough marker for root spread, though roots usually extend considerably further.
- Dry creek bed
- A shaped, stone-lined channel that carries storm flow slowly across or down a slope and reads as part of the garden between storms. Does hydraulic work that a pipe of the same cost cannot.
- Edge restraint
- The buried edging that stops a paver field from spreading sideways under load. Without it a patio migrates outward at the perimeter and the joints open.
- Filter fabric
- Geotextile wrapped around the stone in a French drain to stop clay fines migrating into the aggregate. Omitting it is why so many stone trenches stop draining within a few seasons.
- French drain
- A graded trench containing washed stone and a perforated pipe, wrapped in filter fabric, that intercepts water moving through the soil. Lowers a saturated zone. Moves far less volume than most people assume.
- Geogrid
- Structural mesh laid in horizontal layers into the soil behind a retaining wall, tying the wall to a reinforced mass of earth. What allows a segmental wall to work above the height it could stand on its own.
- Grubbing
- Removing roots and buried vegetation from ground being cleared. Named in the Sandy Springs definition of land-disturbing activity, so it can trigger a permit on its own.
- Kaolinite
- The dominant clay mineral in Piedmont red clay. A low-activity clay with no expanding lattice, which is why Georgia red clay is rated low for shrink-swell and does not heave the way smectite clays do elsewhere.
- Land disturbance permit
- The Sandy Springs permit generally required once 1,000 square feet or more of ground will be disturbed, and possibly below that where the work needs erosion control measures or changes topography or drainage patterns.
- Leaf-on conditions
- The state of a wooded site once the canopy is fully out. The only conditions in which a light count is meaningful, because a yard that reads as full sun in February can be deep shade by late April.
- Lift
- One thin layer of fill or aggregate, placed and compacted before the next goes on. Compacting in lifts is the difference between a base that carries load and one that settles.
- MRPA
- The Metropolitan River Protection Act, under which the Chattahoochee River Corridor is protected. Sandy Springs enforces it on behalf of the Atlanta Regional Commission, issuing permits based on ARC findings.
- Permeable paving
- A paver surface over an open-graded stone reservoir that stores and releases water rather than shedding it. The answer where added impervious area is the problem, at the cost of a deeper build and joints that must stay clean.
- Rain sensor
- A device that stops an irrigation controller running when it has recently rained. Required, and required to be left unobstructed, on new landscape irrigation systems under the Metro North Georgia Water Planning District requirements.
- River Corridor
- The band within 2,000 feet of the banks of the Chattahoochee, running from just downstream of Buford Dam to the Fulton and Douglas county boundaries. Carries a 50-foot undisturbed buffer and a 150-foot impervious surface setback.
- Root flare
- The widening at the base of a trunk where it meets the roots. It should be visible at grade. Burying it under soil or piled mulch is a slow way to kill a tree.
- Segmental retaining wall
- A wall built from manufactured concrete units, battered back and often reinforced with geogrid. The default for structural height because the design is documented and the reinforcement is engineered rather than guessed.
- Shrink-swell potential
- How much a soil changes volume with moisture. Rated low for the Cecil series, which is why Piedmont clay is a drainage problem rather than a movement problem.
- Stream buffer
- In Sandy Springs, the 75-foot protection corridor along designated streams and water bodies. The inner 50 feet must remain undisturbed and the outer 25 feet is an impervious setback. Construction inside generally requires an approved variance.
- Swale
- A shallow shaped channel that carries surface water slowly across or along a slope. Handles large volumes cheaply and needs fall and vegetation to hold together. Not the same tool as a French drain.
- Transition zone
- The band of the country, including Atlanta, where neither warm-season nor cool-season grasses are entirely comfortable. Why lawn choice here is a trade rather than an obvious answer.
- Tree Conservation Plan
- The Sandy Springs submittal required where tree removal is tied to construction activity such as grading, patios, pools or additions. Governed by Division 9.3 of the Development Code and submitted with the construction documents.
Where to go next
The terms about soil and water are explained at length in the red clay guide and the drainage guide. The permit vocabulary is covered in the tree rules guide and the buffers guide. Everything about what things cost sits in the cost guide.
Find out what the yard would cost
Call (404) 737-3568 or use the quote form, and a Sandy Springs landscaping company prices the work at no charge.