|The initial topsoil removal and cutting back of the bank (notice the eroded area close to the structure footing), while Crow Creek Nation archaeological monitor looks on.|
In May, floodwaters engulfed the Crow Creek Reservation located in central South Dakota, damaging several roads and structures. Flash flooding eroded a ravine next to one of Western’s transmission towers located on private land within the reservation boundary. The erosion endangered both the tower and the line’s operability and reliability near a 230-kilovolt steel transmission line. Had the bank caved to the edge of the footing, the tower would have begun to lean and could eventually have collapsed, cutting power to the customers who rely on the line. Western’s Upper Great Plains region employees, in cooperation with the Crow Creek Nation, worked to prevent its destruction.
Western’s Engineering and Maintenance employees determined that the best way to fix the erosion problem was to use simple but effective Gabion baskets to stabilize the bank and divert water away from the structure. Gabion baskets are large wire baskets filled with rip-rap and connected together—in this instance, three tiers high— to divert the flow of water away from an eroding bank. Initially, the floor of the ravine was leveled in order for a track-hoe to cut back the bank for the placement of the baskets. Filter fabric that allows for the passage of water, but not sediment, was layered between the baskets, and the soil from the excavated bank was then filled in behind the baskets. A layer of clay was then placed in the ravine in front of the baskets to prevent soil from eroding out from underneath.
The Crow Creek Nation, as stewards of the cultural resources within the reservation boundaries, felt that it was important to protect and preserve these sites. It’s also Western policy to preserve, protect and avoid disturbance to cultural resources whenever possible. For that reason, UGP developed several project alternatives to address the emergency situation without damaging the archaeological sites. Western was able to keep its construction “footprint” to a minimum, thereby reducing the amount of ground disturbance around the project area.
Field work began Nov. 2 and concluded within two weeks. Nice weather conditions helped the work progress quickly. Following completion of the project, Western restored the excavated bank and reintroduced the removed vegetation to the topsoil so that it has a chance to recover in spring.
After receiving a number of requests, the Department of Interior’s Bureau of Reclamation and U.S. Park Service decided to extend the scoping period for a new Environmental Impact Statement related to the operation of Glen Canyon Dam on the Colorado River from Dec. 30 to Jan. 31.
During the scoping period, agencies determine what factors to consider in the EIS and gather comments from the public to identify social, economic and environmental concerns and project alternatives to evaluate.
The EIS, which is jointly led by Reclamation and the Park Service, involves adopting a Long-Term Experimental and Management Plan for the Operation of Glen Canyon Dam.
The plan, the first comprehensive review of dam operations in 15 years, will ensure that regulated flows on the Colorado River meet the goals of supplying hydroelectricity and water for communities, agriculture and industry; protecting endangered species; and lessening the impact on downstream ecosystems, including the Grand Canyon and Glen Canyon.
Changes to current water flows will be evaluated as “alternatives” in the EIS.
For more information on the EIS or how to submit a comment, visit the project’s web site.