| Owner | Long Lake Hydro Inc. (Regional Power OPW Inc.) |
| Project | New Hydro Energy Project in BC |
| Location | Stewart, BC |
| Size | 32 MW, $120 Million |
| Head and Flow | 778 m & 5.0 m3/s |
| Role | Engineering and Construction Monitoring |
The Long Lake Hydroelectric Project is located at Long Lake, approximately 17 km north of Stewart, BC on the Alaska border at the site of the old Big Missouri hydroelectric project originally constructed in the 1930’s. The new facility included construction of a new 300 m long, 20 m high sheet pile core rock filled dam stemming the flow of Cascade Creek. The concrete intake structure housing a 3 m diameter gated outlet was used for creek diversion during the construction phase. The 1.2 m diameter penstock is over 7 km long falling 780 m down the mountainous pioneering mining road, making it one of the highest head hydroelectric projects in North America. A state of the art powerhouse located on the banks of Cascade Creek contains two Andritz Hydro 16 MW horizontal shaft twin jet Pelton turbines. Power is transmitted at 138 kV along a new 12 km transmission line to a new BC Hydro sub-station near Stewart, BC .
Key features include:
- All dam rock fill, concrete aggregate and penstock backfill materials were excavated from borrow pits or blasted and processed from quarries on site
- Dam core sheet piles were galvanized and coated with a spray-on polymeric liner for double corrosion protection
- 135 m long emergency side channel spillway designed to pass PMF inflow design flood
- New reservoir has a live storage of 27,000 dam³
- Penstock route included cross country sections with gradients approaching 1:1
- Powerhouse bypass valve and energy dissipation chamber will deliver minimum flows to Cascade Creek when turbines are offline
- Penstock included 30 m span pipe bridge over Cascade Creek