Western works with Crow Creek Nation to repair structure

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 Richard Dion looks on. (Photo provided by Dave Kluth)

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 along the Fort Thompson-to-Fort Randall 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.

UGP Archaeologist and Historic Preservation Officer Dave Kluth assisted the Maintenance Office’s effort to keep the tower upright and safe. This included monitoring the work to ensure Western’s compliance with Federal cultural resource law and consulting with the Crow Creek tribe on various solutions aimed at avoiding damage to the known sites and minimizing impact to any unknown sites. "Since there was a chance for buried archaeological deposits in the area, UGP and tribal members felt that the project should be monitored in the event that the maintenance work uncovered any unknown historic resources," explained Kluth.

Planning a solution
Since this was an emergency situation where collapse of the structure would have caused an extended outage to customers in the region, the normal consultation process for determining the environmental and cultural impact of the Federal project was streamlined. "This process normally takes months to complete, but representatives from Western, the Crow Creek Nation, Bureau of Indian Affairs and State Historic Preservation Office worked together to expedite the consultation process in order to ‘keep the lights on’ in this part of South Dakota," said Kluth.

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.

Preserving archaeologically sensitive areas
During the planning phase of the project, Kluth identified several archaeological sites near the threatened tower that would have been severely damaged by the proposed maintenance work. 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.

Initial project specifications called for the disturbance of additional acres of ground, but Western was able to keep its construction "footprint" to a minimum, thereby reducing the amount of ground disturbance around the project area. In addition, Western provided an archaeological monitor who, in cooperation with a Crow Creek monitor, observed all ground-disturbing activity for any sign of cultural material. Artifacts, like stone tools, pottery sherds and animal bones, would indicate that the work had uncovered a previously unknown archaeological site.

"Although the monitors did not identify any unknown archaeological sites, a number of ancient bison bones were observed approximately 10 feet below the current land surface. The age of the bones is currently unknown, but it is likely that they were deposited there by a flood event many thousands of years ago. The find included a complete leg bone, a vertebra fragment and a section of rib bone," Kluth said.

A job well done
UGP is constantly trying to balance the requirements of the project with the needs of the land owners and other affected parties. When the project was complete, Kluth reflected on the connection between Western and the Crow Creek Nation: "The cooperation shown by all parties will continue the relationship of trust between the groups that has been built up over the years, and it’s another example of UGP’s commitment to being a ‘good environmental neighbor."

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.