Posted March 5, 2020
Through multiple successful projects, J.F. Brennan Company (Brennan) developed a great partnering relationship with the Midwest group of Xcel Energy® (Xcel). From Federal Energy Regulatory Commission (FERC) dive inspections and innovative dam repair projects to the implementation of amphibious equipment and helicopters for transmission line installation, we are always looking at ways of incorporating Brennan’s “can-do” attitude into all client interactions. This year, we got the opportunity to work with Xcel’s Western group.
In late September 2019, we received a call from Xcel Energy’s Western group regarding their Terminal Dam facility, and we quickly responded. Terminal Dam is an asphalt capped rock-fill dam located directly north of Durango, Colorado. A previous underwater dive inspection found a minor anomaly on the dam face.
Lessening Environmental Impact Before Diving
Xcel, W.W. Wheeler & Associates, FERC, and Brennan worked together to formulate an effective and safe repair solution utilizing divers for repairing anomalies in the dam.
After arriving on site in November 2019, Brennan Project Manager Chase Slabaugh led our crew in performing an extensive invasive species prevention cleaning of all gear. We washed all gear we planned to place in the water with a 140-degree pressure washer.
After cleaning the equipment, our onsite crew began their initial investigation using a remotely operated vehicle (ROV) to determine if a differential pressure hazard existed adjacent to the anomaly in the dam.
Safely Repairing Asphalt Anomalies at Terminal Dam
Thankfully, we confirmed that the anomaly had not advanced beyond the initial dive inspection findings and that extremely minimal suction existed near the hole. We began repairs by placing small handmade sacks filled with gravel in and around the anomaly on the asphalt face.
Next, the crew filled any remaining void with a grout-filled synthetic membrane. Finally, the crew placed a rubber membrane over the repair and secured it with 2?IN by 4?IN tack strips. We performed various dive inspections while onsite as well.
Underwater Dam Repairs at 8,194 FT Changed Dive Plans
Overall, the project was deemed a huge success. Brennan mobilized quickly after we received the go-ahead, we suggested solutions to our client’s problem, we performed the work safely and efficiently with the proper tools and equipment, and we did all this work at altitude—8,194 FT above sea level.
Diving at altitude requires an adjustment to our overall bottom times. Standard dive tables give us bottom times based on how our bodies deal with partial pressures of gas at sea level. Bottom times are significantly different when you are well above sea level, as in the case of the site in Durango. We utilized altitude-adjusted dive tables which essentially lessened the amount of time our team could spend at various depths underwater. Because of this careful planning, we were able to meet our client’s expectations.
We hope we left Xcel’s Western group with a great impression, a good understanding of the type of work that Brennan performs, and the exceptional quality we offer.
Brennan's Xcel Terminal Dam Crew:
Chase Slabaugh, Kori Meeks, Evan Christianson, Cory Harris, Ryan Anderson, Bryan Mehus