New “zero rock cut” design scenario for lower Fourmile Canyon Drive reconstruction available for review and comment 

Public feedback will be used to create a hybrid option

Boulder County, Colo. – In response to public comment on the original set of plans for flood-related permanent reconstruction of two sections of lower Fourmile Canyon Drive , Boulder County and its engineering team have created a new “zero rock cut” design scenario that eliminates the need for removing rock from the uphill side of the road.

Both the zero rock cut and rock cut design scenarios are available for public comment until Friday, Dec. 11 at www.4MileCanyon.com, use the “Lower Fourmile Canyon Drive Reconstruction Options” link.

The new Zero Rock Cut scenario reduces many of the visual impacts by eliminating any rock removal from the uphill side of the road; however, it also increases impacts to some sections of the creek. The Zero Rock Cut design scenario requires the installation of retaining walls and other stream bank stabilization measures in order to protect the road from being completely washed away in a significant future flood event, while still making every effort to reduce impacts to the creek and surrounding properties. With this scenario, Boulder County would do everything it can to minimize the visual impacts of any retaining walls, and much of the bank stabilization would be buried and revegetated.

The previously released “Rock Cut” scenario would move the roadway away from the creek, not require as many retaining walls or guardrails, and have fewer impacts on the creek.

Both design options include an approximate one-foot strip of paved buffer between the downhill lane and the edge of pavement, two 11-foot travel lanes, an approximate 4’ uphill paved shoulder (within the two construction zones only), and drainage ditch improvements on the uphill side of the road. The primary function of the uphill shoulder is to hold and convey water that is coming down the hillside and prevent it from inundating the road.

After the Dec. 11 public comment deadline, Boulder County will incorporate feedback, where applicable, to create a new design that incorporates aspects of both design scenarios in order to complete permanent flood recovery-related construction of two sections of lower Fourmile Canyon Drive: 1) Between mile marker 1 and Poorman Road; and, 2) just past Logan Mill Road to Salina Junction.

The new set of plans will be presented at an open house at a date to be determined and will also be made available for review at www.4MileCanyon.com.

• The county’s goal is to make permanent repairs to the flood damaged portions of Fourmile Canyon that can:

• Withstand future flooding;

• Make the road safer;

• Reduce the impact of flooding on residents adjacent to the roadway and creek; and,

• Maintain the special visual, environmental, and community character of the canyon.

It is not possible to rebuild lower Fourmile Canyon Drive in a way that accomplishes these goals without either moving the road away from the creek and into the hillside, or strengthening the creek-side of the road.

For more information on the project, contact Andrew Barth, Transportation Department communications specialist, at abarth@nullbouldercounty.org or call 303-441-1032.

All current Boulder County Transportation roadway project information, including regular maintenance and flood-recovery activity, can be found at www.BoCoConeZones.com.