For many dams currently being removed in the U.S., the primary reason behind this work is the need to protect fish and restore their habitat. This article provides case studies of the removals under way and the context under which these decisions were made.
For people working in the hydroelectric industry, the idea of dam removal may seem counterintuitive. After all, the goal is to use dams to generate electricity, and removing them certainly prevents that from happening. But, the fact is that dam removal has been and is happening and appears certain to continue in the future.
The question is, Why are owners and other agencies removing dams? I'm sure it is challenging to accept the series of circumstances that leads to removal of a dam as the best available option for all parties, especially when so many developers throughout the U.S. and Canada are in the process of building new projects, expanding existing facilities or exploring potential future locations for hydroelectric powerhouses.
Hydro Review presents several dams recently removed or in the process of being removed to showcase the reasons for this work. The overarching common denominator? Fish protection and restoration. In all of the cases mentioned below, the ultimate decision to remove the dam(s) was made with an eye toward improving or restoring fish runs, particularly of species listed as endangered or threatened under the Endangered Species Act.
With installation of the fish passage structures required to earn a new Federal Energy Regulatory Commission operating license for the 13.7-MW Condit project estimated to cost $100 million, project owner PacifiCorp made the decision to decommission and remove this facility in 1997. A settlement agreement with federal and state agencies, as well as tribal and local conservation and recreation organizations, was finalized in 1999.
And in October 2011, after a dozen years of studies and permitting, PacifiCorp blasted a tunnel through the base of Condit Dam, on the White Salmon River in south central Washington. The entire dam structure is scheduled to be removed by August 31, 2012. Removal of this dam and hydroelectric facility, which had operated for nearly a century, opened 33 miles of the river for steelhead and salmon migration.
Condit Dam is 3.3 miles upstream from the confluence of the White Salmon and Columbia rivers. The dam created a reservoir, Northwestern Lake, that extended 1.8 miles upstream of the dam and covered about 92 acres. Project facilities consist of a 125-foot-high, 471-foot-long concrete gravity diversion dam and an intake structure that directs water into a 13.5-foot-diameter by 5,100-foot-long woodstave flow line, then through two penstocks and into a powerhouse containing two double horizontal Francis turbines.
Condit Dam was built in 1912 and 1913 but wasn't under license requirements until the 1960s. It was originally licensed by FERC in 1968, with a May 1, 1965, effective date. PacifiCorp began work to relicense the project in 1991. Several resource agencies and groups, including American Rivers, pushed for decommissioning and removal of the dam because it cut off salmon and steelhead from the upper White Salmon River.
In November 1996, FERC issued a final environmental impact statement that would have required PacifiCorp to install fish ladders and screens for fish passage. Fish ladders were part of Condit's original design, but they washed out twice during floods in the early years of the dam's operation. FERC also required higher instream flows, which would reduce capacity of the project by an undetermined amount. PacifiCorp determined that these requirements would render the dam uneconomical for its customers.
In a settlement signed in 1999, after two years of negotiation with resource agencies and stakeholder groups, PacifiCorp agreed to remove Condit Dam and to decommission the project. The cost of decommissioning and removing Condit is estimated at $35 million, including funds already spent during the planning process over the 12 years since the settlement was announced.
Micheal Dunn, president of PacifiCorp Energy, says the choice to remove Condit Dam was a result of a decision to work with "settlement partners to come to the most reasonable solution for everyone involved, especially the cost to our customers."
In October 2010, the Washington Department of Ecology approved a Section 401 Water Quality Certification for the project. FERC then accepted PacifiCorp's surrender of its license for Condit Dam and approved the utility's plan to remove the dam. In December 2010, PacifiCorp received a surrender order from FERC providing for dam decommissioning.
The commission made minor modifications to the surrender order in April 2011, including timing issues and sediment management details. In conjunction with a section 404 permit received from the U.S. Army Corps of Engineers in May 2011, this provided the regulatory certainty PacifiCorp needed to proceed to remove the high dam. In June 2011, the commission completed review and approval of project removal design and resource management plans.
Crews worked throughout the summer of 2011, preparing to blast a 13-foot-wide hole near the base of the dam. During August and September, crews excavated a 90-foot-long drain tunnel through the dam. Other work included dredging the upstream side of the dam at the drain tunnel, strengthening a bridge that crossed Northwestern Lake, relocating a water pipeline that crossed the reservoir and shutting down the powerhouse (just minutes before the breach).
PacifiCorp, prime contractor JR Merit of Vancouver, Wash., and detonation contractor Kiewit Infrastructure West of Vancouver, Wash., surveyed the area after the October 2011 blast, took readings from sensing devices, and flew over the area in a helicopter before declaring the breach a success and the remaining structure to be safe.
Demolition of the remaining portion of the dam is in progress and is to be completed by August 31, 2012. Restoration work throughout the former reservoir area is slated for completion by the end of 2012.
PacifiCorp says there are no plans to dismantle the powerhouse, and the generating equipment was not removed.
Elwha and Glines Canyon Dams
The three-year process to remove the Elwha and Glines Canyon dams began in September 2011. The Elwha River flows through Olympic National Park in Washington, and restoration will open up more than 70 miles of salmon and steelhead habitat. At 210 feet, Glines Canyon will be the largest dam ever removed.
Elwha Dam construction was completed in 1913 and Glines Canyon Dam in 1927. Neither dam included a fish ladder, thus preventing native anadromous salmon and trout from advancing past the lower 5 miles of the river.
To add your comments you must sign-in or create a free account.
Hydro Review's goal is to provide readers with reliable, relevant information on the issues and challenges encountered in the hydro industry. Hydro Review offers practical, useful information, helpful examples, and constructive guidance...