Rain, rain, rain – we have had 2 weeks of rain and the Chena River started to rise. Everyone from the Corps to the mayor of Fairbanks is concerned about flooding and potential damage caused. The Corps Rangers have gone on 12 hour shifts with hourly checking of the water and the dam. Cyndy and I have been manning the office phones to answer questions. We are now getting to see the real purpose for the Chena Flood Control Project as we go through our first flood of the season. The Corps calls this situation an “Event.”
The picture below is of the dam in June, showing calm water and plenty of room for boats to pass through.
In 1967, Fairbanks experienced a flood that destroyed much of the city. Over 4,000 people had to be evacuated and much of the downtown was destroyed. To prevent another flood the U.S. Army Corps of Engineers stepped in. The problem is that the Chena River flows through the heart of downtown Fairbanks so the Corps’ plan called for limiting the volume of water to pass through a dam located about 15 miles upstream and east of Fairbanks.
The river has risen 8 feet and the dam gates have been lowered, closing the river to boat traffic.
One of the problems caused by the flooding is the amount of debris (trees, logs etc.) that is carried down the river. The large crane in the picture will be used to remove the debris.
The blue screen door looking things are called “trash racks.” In a severe event they would be lowered allowing the rangers to continue regulating the volume of water by raising or lowering the gates without debris getting caught under them.
The numbers on the side of the dam indicate the actual river elevation (feet above sea level). June 1992 was the date of a severe event with water reaching almost 508′.
Normal July-August river volume runs at 700-1,000 ft3/sec (cubic feet per second). The Corps is mandated to only allow the river to get to 8,100 ft3/sec. When the Chena reached that level Friday night, the gates were lowered. During the 1967 flood the River was running at 74,000 ft3/sec.
Water over 8,100′ in volume is diverted south to the Tanana River by the construction of an 8 mile long levee. In this first picture you are looking south on top of the levee near the dam. Our trailer is just behind us to the right.
This picture was taken 2-3 miles further south on the levee. At the southern most end of the levee there is a spillway where the flood water empties into the Tanana River.
Although this event is only 10% of the 1967 flood, it demonstrates just how important this project is to the city of Fairbanks and it was exciting for us to watch the Corps go into action.
Cliff and Cyndy