Three Scenarios for Piling Schedules
Each pile takes approximately 3 hours to drive. With three projects active simultaneously, the question is whether they pile at the same time, at random times, or in coordinated non-overlapping windows. The difference determines how many quiet hours exist per day.
Simultaneous
All three projects pile at the same time. Maximum noise for 3 hours, silence for 21. Most quiet hours, but highest peak noise and no control over when quiet occurs.
Uncoordinated
Each project piles when convenient. Random overlap creates fragmented quiet periods.
Sequential
Projects stagger piling into non-overlapping 3-hour blocks. The remaining hours are guaranteed quiet.
| Scenario | Hours Masked | Hours Quiet | Quiet Guaranteed? |
|---|---|---|---|
| Simultaneous (all at once) | 3 | 21 | Yes |
| Uncoordinated (current) | ~12 | ~12 | No |
| Sequential (coordinated) | 15 | 9 | Yes |
The simultaneous scenario produces the most quiet hours but concentrates the loudest noise into a single window. The sequential scenario spreads noise across 15 hours but guarantees 9 continuous quiet hours when no project is piling. The uncoordinated scenario is worst in practice because it provides no guarantee — quiet hours are random and fragmented.
When You Start Matters 3.3 Times More
Beyond daily scheduling, the month each project begins construction determines how much of the piling season overlaps with peak whale density. We evaluated all possible combinations of start months across 7 eligible months (May–November).
16,807 schedule combinations (7&sup5; = five regional projects × 7 possible start months) were evaluated by brute force. The daily coordination analysis above uses 3 co-located projects (staggering within a day); this analysis expands to 5 projects across the broader region (staggering across months). The best combination — all projects starting in June — produces 3.3× fewer total takes than the worst combination (projects starting in November and December, piling through the highest-density months).
The distribution of outcomes is not symmetric. Most schedule combinations cluster near the median. But the tails are wide — the worst schedule produces 3.3× more takes than the best. This is a large effect from a decision that costs nothing and requires only coordination between project timelines.
Two-Level Optimization
Daily coordination and start date optimization are independent. They can be combined.
Level 1 (within-day): Stagger piling into non-overlapping blocks. This creates 9 guaranteed quiet hours per day when whales can communicate without interference.
Level 2 (across-season): Coordinate project start dates to minimize overlap with peak whale density months. This reduces total seasonal takes by 3.3×.
Neither level requires new technology, additional monitoring, or regulatory changes. Both are scheduling decisions. The only requirement is a mechanism for inter-project coordination — which the current per-project IHA process does not provide.
| Mitigation | What It Does | Reduction | Cost |
|---|---|---|---|
| Daily staggering | 9 guaranteed quiet hours/day | Continuous communication window | $0 |
| Start date optimization | Avoid peak density overlap | 3.3× fewer takes | $0 |
| Bubble curtain (10 dB) | Shrink shutdown zone | 12× zone reduction | $500K–$2M per project |
| Pile-free foundations | Eliminate pile driving entirely | 100% reduction | $10M+ per project (est.) |
The per-project IHA has no mechanism to coordinate across projects. The masking zone is 14× larger than the shutdown zone. At that scale, coordination is the only mitigation that works — and it is the only mitigation that the current regulatory framework cannot require.
3 projects modeled · 7 eligible start months · 16,807 brute-force schedule combinations · Roberts et al. 2024 monthly NARW density · RAM PE propagation · 10 dB bubble curtain assumed