CECS — Hydropower
Two identical dams on different rock can cost wildly different sums. Hydropower is dominated by massive site-specific civil works and what lies underground, so an estimate's maturity hinges on how thoroughly the ground has been investigated. Built on AACE 69R-12.
What this standard adds
Same five-class logic as Lesson 1, but hydropower shifts the center of gravity to civil works and the ground. Where a process plant's maturity rides on equipment and a building's on design phases, a hydropower estimate's maturity rides on how well the site — its rock, its river — is understood.
Why hydropower is distinctive
- Civil works dominate cost — Dams, spillways, tunnels, and powerhouses — massive concrete and excavation — typically far outweigh the electromechanical equipment.
- Every site is unique — There's little repeatability; each project is shaped by its specific topography, geology, and river — limiting the use of generic cost data.
- Hydrology drives the design — The available water and flow regime set the plant size and energy output — and carry their own long-term uncertainty.
- Long schedules, big contingency — Multi-year construction and deep ground uncertainty mean early estimates must carry substantial contingency.
Site definition mapped to classes
Hydropower maturity climbs with site investigation and civil design (general pattern; the RP gives the authoritative matrix):
| Class | Site / civil definition | Typical study |
|---|---|---|
| 5 | Desktop hydrology, no drilling | Reconnaissance |
| 4 | Initial geology, concept layout | Pre-feasibility |
| 3 | Drilling program, civil design advanced | Feasibility |
| 2 | Detailed geotech, detailed design | Detailed engineering |
| 1 | Tender-level civil documents | Tender / control |
Putting it to work
For a hydropower estimator, the class is largely a statement about site knowledge. Tie the class to the level of geotechnical and hydrological investigation, keep generous contingency until drilling confirms conditions, and resist pressure to firm up a budget before the ground has actually been explored.
Nine things to remember
- 69R-12 applies the five-class system to hydropower — anchored to site investigation.
- Civil works dominate cost — dams, tunnels, powerhouses outweigh the equipment.
- Every site is unique — limited repeatability, so generic data is risky.
- Site investigation is the maturity driver — geotech drilling and hydrology move the class.
- Hydrology drives the design — available water sets size and output.
- Electromechanical is often better-defined than the civil works.
- Ground risk is the great destroyer — unforeseen conditions cause the big overruns.
- Pre-drilling estimates are effectively Class 5, however detailed the drawings.
- One framework, many dialects — hydropower centers "definition" on the natural site.
Glossary
- Civil works
- Dam, spillway, tunnels, powerhouse — the dominant cost.
- Electromechanical
- Turbines, generators — manufactured, better-defined equipment.
- Estimate class
- Maturity level (5 roughest → 1 most definitive).
- Geotechnical investigation
- Drilling and testing to characterize the ground.
- Headrace tunnel
- Conduit carrying water to the turbines.
- Hydrology
- Study of water availability and flow — sets plant size.
- Hydropower
- Generating electricity from flowing or falling water.
- Unforeseen ground conditions
- Unexpected geology — a major overrun source.