The Terrace design dialog

The dialog is multi-step. The breadcrumb at the top shows where you are: Select Surveys → Channel Design → Berm Analysis → Implement.

Channel Design

Looks like Slope-IQ. The channel survey terrain is on the chart, the proposed channel line is below. Same Best-Fit / Guided / Freeform modes.

Parameter cards:

• DEPTH OFFSET — channel cut depth below terrain.
• MIN GRADE — minimum drainage grade for the channel.
• CHANNEL BASE WIDTH — channel bottom width (also used for cut volume). Displayed in metres in metric mode (0.3–9.0 m, 0.5 m step), in feet in imperial (1–30 ft, 1 ft step). Defaults to your configured Swath Width.
• SIDE SLOPE — H:V ratio of channel sides. The Auto button derives a side slope by averaging each berm point's horizontal distance from the channel centerline divided by its vertical rise above the channel design elevation, clamped to 1:1–12:1. It needs at least 3 berm points that sit above the channel design; otherwise the button is disabled.

Berm Analysis

The dialog re-stations the berm survey onto the channel centerline (using the LinearInterpolator for distance-along projection). The chart now shows four lines:

• Channel terrain — existing ground along the channel.
• Channel proposed (design) — the cut line below channel terrain.
• Berm terrain re-stationed onto channel station — your surveyed berm centerline, in sky-blue. For a normal terrace this sits ABOVE the channel terrain because the berm is a ridge.
• Min Berm Line — channel proposed + Min Berm Height. The berm has to reach at least this elevation; where the surveyed berm is below this line, fill is required.

Where the berm terrain is below the Min Berm Line, the chart fills that gap in red — that is the fill needed to bring the berm up to minimum height. Where the berm terrain is already above the Min Berm Line, no fill needed (or surplus material).

Volume strip (left to right):

• Cut — what the channel design will excavate (cubic yards / m³).
• Fill Needed — raw fill required to bring the berm up to the Min Berm Line.
• Cut Req (incl. 15%) — cut needed once the built-in 15% compaction factor is added in.
• Status badge (far right) — reads Balanced, Surplus, Short, or No fill needed depending on whether cut volume meets the compaction-adjusted fill requirement.

Auto-Balance button

If your cut is short of the adjusted fill, tap Auto-Balance. The dialog walks the channel Depth Offset deeper in 0.5″ steps, recomputing volumes at each step, until cut volume meets compaction-adjusted fill volume. A snackbar reports the offset increase. The total offset is capped by Settings → GRADING → Auto Balance Max Offset (default 36″).

Min Berm Height card (BERM MIN HT)

The card is labelled BERM MIN HT. Adjust the minimum berm vertical (default 18″ / 46 cm). Range 6–36″ imperial (1″ step) or 15–90 cm metric (1 cm step). Bigger min height = more fill needed = deeper channel cut. The value you pick persists as the next-design default.

Implement

Tap Review & Implement to reach the final step — a Ready to Grade summary card showing the channel and berm survey names, total distance, channel grade, min berm height, bottom width, and the cut / fill / balance rows, plus the note Use the Channel/Berm toggle in the sidebar to switch targets during grading. There is no channel-first / berm-first confirmation — grading starts in the Channel phase by default. Tap Implement Slope (play icon) to commit.