Plan dredging and excavation quantities for berth pockets. Add slopes, allowances, costs, and production rates. Download a tidy report for site records anytime easily.
| Scenario | Length | Bottom width | Depth | Slopes (L/R/F/B) | Overdig | Contingency | In-place with contingency | |
|---|---|---|---|---|---|---|---|---|
| Typical berth pocket | 60 m | 22 m | 4.5 m | 1.5 / 1.5 / 1.0 / 1.0 | 0.15 m | 5% | ≈ 7,500 m³ (varies by inputs) | |
| Shallower pocket | 45 m | 18 m | 3.2 m | 1.0 / 1.0 / 1.0 / 1.0 | 0.10 m | 3% | ≈ 3,000 m³ (varies by inputs) | |
| Irregular pocket (stations) | Areas: 360, 390, 420, 440, 420, 400, 370 m² | Spacing: 10 m | 5% | ≈ 4,200 m³ (varies by areas) | ||||
A berth pocket is typically surveyed as a plan rectangle, but the excavation behaves as a tapered prism once side slopes are applied. Small changes in depth create large volume changes: a 0.10 m depth increase over a 60 m by 22 m base adds roughly 132 m³ before slopes and allowances.
Side slopes are often specified as horizontal-to-vertical ratios. Soft silts and loose sands may require 2H:1V to 3H:1V for stability, while dense sands and stiff clays can work near 1.5H:1V. Where rock is present, temporary cuts may approach 0.25H:1V to 0.5H:1V with controls.
Overdig helps meet final grade after trimming, turbidity, and equipment limits. For dredging or underwater excavation, allowances of 0.10–0.30 m are common depending on tolerance, survey frequency, and the plant used. Apply overdig to the effective depth so top dimensions expand consistently with the slopes.
Contingency covers uncertainty in surveys, model assumptions, and material variability. Many projects carry 3–10% for planning, then tighten to 1–3% once pre- and post-dredge surveys are validated. This calculator applies contingency to in-place volume so procurement and production planning share one baseline quantity.
Bulking (swell) estimates loose volume after excavation, useful for barge capacity or stockpile space. Typical swell ranges are 10–25% for sands, 20–35% for clays, and higher when material breaks down. Shrinkage estimates compacted placement volume; 0–15% is a common planning range for engineered fills.
When the pocket shape is irregular, station areas from cross-sections provide better accuracy than a single width. Use evenly spaced stations (often 5–20 m). With an even number of intervals, Simpson’s 1/3 rule improves precision by fitting curvature between areas; otherwise the final segment uses a trapezoidal step.
Production depends on method, disposal distance, and permits. A small excavator and barge cycle might average 300–800 m³/day, while larger dredging spreads can exceed 1,000–3,000 m³/day in favorable conditions. This tool converts volume to estimated days, helping align marine windows, tides, and traffic constraints.
Unit-rate estimates are most reliable when tied to the same measurement basis used in payment. If contracts pay by in-place survey quantity, apply the rate to the contingency-adjusted in-place volume. Exporting the summary to CSV supports review, while the PDF snapshot provides a consistent attachment for submittals and internal approvals.
Use Dimensions + side slopes for pockets that are approximately rectangular in plan with consistent slopes. Use Station areas when geometry changes along the length or when cross-sections are already available from survey profiles.
Spacing of 5–20 m is common. Tighter spacing improves accuracy in rapidly changing geometry, especially near transitions, corners, or localized deepening. Keep stations evenly spaced to match the integration rules used by the calculator.
Yes. Contingency reflects uncertainty in the in-place quantity. After that baseline is set, apply bulking to estimate loose handling volume, and apply shrinkage to estimate compacted placement volume if material is reused.
Start with geotechnical logs and past projects. Sands often bulk 10–25%, clays 20–35%. Shrinkage for compacted placement is frequently 0–15%. Update factors after test loads, trial sections, or early production data.
Depth increases expand both the bottom-to-top dimensions through the slopes and the prismoidal relationship. The top area grows as depth increases, so the added volume is more than the base area times the depth change.
Yes, for planning. Enter surveyed dimensions, expected slopes, and an overdig allowance that matches the tolerance and equipment. Final payment should follow the contract measurement method, typically comparing pre- and post-dredge surveys.
Use the in-place volume with contingency if your budget and payment are survey-based. Use loose volume for transport and disposal capacity checks. Use compacted volume only when excavated material will be placed and compacted as fill.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.