Project Roundup: Ice Fountain Water District Spring Reconstruction

by Robin Harris, P.E., Senior Engineer

On November 7, 2006, an avalanche of debris barreled through the Middle Fork of the Hood River, flooding the whole area with destructive force. Hard-hit by the flood was the Ice Fountain Water District’s spring box, as the debris rose approximately 10 feet above the top of the 17-foot-tall spring box retaining wall and washed away the existing riprap, vegetation, and streambank that protected the spring structure. The Ice Fountain spring is the only water source for approximately 6,000 residents in Hood River County, south of the City of Hood River, and this flood event reduced the spring’s capacity by almost 30 percent.

The Original Spring Project
Eight years earlier, in 1998, AP partnered with the District to successfully complete the Ice Fountain spring development and a 9-mile-long pipeline carrying the water into the District. AP developed innovative designs to deal with the spring’s remote location, maintain the floodway of the river, protect the spring from surface and groundwater intrusion, capture the entire spring flow, and deliver this crystal-clear water to the users in the District in an economical manner.

Engineering the Intake Reconstruction
During the flood event, streambed scour occurred to a depth of approximately 10 to 15 feet. This extensive scour left the existing retaining wall and area below the retaining wall vulnerable to failure. As part of an emergency work effort, riprap that washed away was replaced at the spring site as well as upstream where the torrent removed vegetation and bank material. The portion of riprap immediately around the existing retaining wall was removed, and the area under the retaining wall was injected with grout to capture spring water flowing into the adjacent river. To restore the capacity of the spring, cabled riprap was put in place, streambank areas at the Ice Fountain spring were stabilized with woody material, and 200 feet downstream, streambank planting and seeding were completed. By anchoring the cabled riprap to the bedrock using micropiles, AP developed a monolithic structure that is able to better withstand flood events.

Emergency Environmental Permitting
Because the reconstruction work required to install the new intake structure involved in-stream construction activities, AP’s biologists had to quickly and thoroughly analyze the effects of the project on the habitat of Endangered Species Act-listed and candidate species present in the project area, including Coho salmon, steelhead, Chinook salmon, and bull trout. The AP Natural Resources Group developed a Biological Assessment (BA) and a USACE Section 404 permit to address the project’s environmental effects in compliance with Section 7(c) of the Endangered Species Act and to assess impacts to Essential Fish Habitat. AP prepared the BA in a two-week timeframe, moving the reconstruction work as quickly as possible through the regulatory process.

Results of the Intake Reconstruction
The project was a total success in terms of restoring and enhancing spring flows and installing the riprap cabling and anchoring system. The grout injection operation captured the 700 gpm of lost spring flows and then some. The original spring capacity was 2,400 gpm; after the grout injection operation, the spring capacity increased by 25 percent to 3,100 gpm, making the spring more effective than before the storm and restoring access to the spring water upon which 6,000 residents of Hood River County depend.