The key to minimizing costs on a heavy civil hydroelectric project is to obtain the Dam Embankment fills and Concrete Aggregates from borrow sources as close to the site as possible. When determining the location for a hydroelectric project the availability of quality embankment and aggregate material is essential. This includes impervious tills, granular sources and rock sources for concrete aggregates and riprap erosion protection.

When estimating a hydroelectric project, the first thing the estimator must do is a “Material Balance” chart to analyze the material available from excavations vs the material required for embankments and concrete to determine the amount of borrow required. The depth of the available borrow is also important to determine the amount of stripping required to access the borrow areas. The haul distances to the various borrows must also be summarized.

Refer to HCI 180 Excavation & Backfill for Hauling Costs

Refer to HCI 510 Process Aggregates for Crushing & Screening Costs

Hydroelectric Projects involve harnessing & diverting the flow of water. This usually includes the diversion of water during construction within river Cofferdams & Diversion Tunnels. This construction usually can only be performed at certain times of year when the flow is the lowest. No cofferdam is ever fully watertight and estimating the amount of pumping required to keep the foundations dry is difficult to predict. The Dam & Cofferdam construction includes the blasting, processing, excavating, hauling & placing of Impervious, Filter & Rock material.


Refer to HCI 100 Site Preparation for Dewatering Costs

Refer to HCI 180 Excavation & Backfill for Dam Embankment Costs

Refer to HCI 220 Drill Blast Tunnels for Dam Embankment Costs

Most heavy civil hydroelectric projects, for stability reasons must be situated on competent rock. This usually involves drill and blasting operations as well as line drilling to prepare vertical rock faces. The cost of sub-grade preparation is also high on these projects because the rock must first be cleaned prior to concreting.


Refer to HCI 180 Excavation & Backfill for Drill Blast Rock Costs

Estimating concrete and formwork costs on heavy hydro projects is much different that estimating the same costs on traditional civil projects. Formwork man-hour factors can be 3-5 times higher on a Hydroelectric Project than on a Bridge Project. The forms are often curved and constructed against rock requiring special forms and rock anchors. The forms must also support heavier pours and quite often cannot be reused as often as on traditional civil projects. Invariably the concrete is also cast against blasted rock which leads more wasted concrete, called “Overbreak” than would be traditionally found on other projects.


Refer to HCI 420 Cast in Place Concrete for General Concrete Costs

Refer to HCI 460 Water Control & Hydro Structures for Specific Structures

Penstocks consist of large diameter steel pressure pipe used to carry water from the Intake to the Powerhouse. The large diameters often require the pipe to be delivered in ½ to ¼ shells that must be welded onsite. Before reaching the Turbines, the large diameter pipe is often bifurcated into smaller diameters requiring complex onsite fabrication, welding & heavy lifting techniques. The cost of Penstock Steel can often be 3-4 times the cost of traditional structural steel on other civil projects.


Refer to HCI-480-Structural Steel Erection for Penstock Costs

Intake Structures, Spillway Structures and Powerhouse Draft Tubes usually require steel gates to be installed that can be opened and closed to control the flow of water. The gates can be “Vertical” gates or curved “Radial” gates. The gates are usually accompanied by either wire-rope or hydraulic hoists so they can be opened and closed. Steel Guides must also be embedded in the concrete before the gates are installed. These guides must be installed precisely to guarantee water tightness.


Refer to HCI-480-Structural Steel Erection for Gate Installation Costs

These projects include the construction of a heavy steel building to house the Turbines and Generators and to provide space for ongoing operations and maintenance. This building usually comes complete with a large capacity overhead crane capable of lifting out the heaviest pieces of the Turbines and Generators.

Refer to HCI-480-Structural Steel Erection for Powerhouse Steel Costs

These projects can be hundreds of miles long running over isolated rough terrain consisting of clearing, extensive access roads, tower foundations in soil, rock & bog, guyed & self supported steel lattice towers, stringing conductor, installing insulators, grounding & site restoration.


Refer to HCI-710-High Voltage Transmission Lines

Invariably Heavy Civil Hydroelectric Projects are situated in remote locations far from the nearest town or city. Based on the man-hours generated from the estimate and the schedule the estimator must calculate the number of travel trips, the size of the camp & the number of man-days of catering. The cost of transporting the workers to and from the camp can also be significant.


Refer to HCI-960 Remote Project Indirects for Travel & Camp Costs

When a Camp is required, it is often more cost effective to work a 7-day operation to increase the camp utilization. Operating & monitoring site services such as onsite power generation & dewatering is a 24 hour per day operation. As such, Overtime and Shift Differential Costs are normally much higher than traditional bridge or highway projects.


Refer to HCI-010-Labor Rates for development of Overtime Rules

Due to the isolated nature of these projects, contractors must provide their own infrastructure including access roads, temporary power, water supply and compressed air. All services like equipment transfer, equipment fueling & warehousing must be performed by their own forces. For these reasons the indirect costs on remote projects can be as much as 2 to 3 times the cost of civil projects located close to town or the contractors home office.


Refer to HCI-960 Remote Project Indirect Assemblies