Trends Winter 2017 - Page 17

A LOOK AHEAD Here is a quick glimpse into projects in the works across the country. Watch for more on them in our blog ( and in future TRENDS issues. A PROJECT THAT DOESN’T HOLD WATER Most projects involving pavement result in runoff that has to find its way either to a nearby detention pond, bioswale, or a distant river via a network of storm sewer pipes. This one, not so much. Ayres Associates provided construction engineering this year on a City of Fitchburg, Wisconsin, project that reconstructed 1.4 miles of Lacy Road. What sets this project apart is the intensity of its porosity. Not only is there a 400-foot test section of porous asphalt shared-use path that parallels the street, but there are also permeable storm trenches along most of the project. These trenches allow much of the stormwater to seep through perforated storm sewer pipes and into the ground rather than proceeding through the stormwater collection system. The concept of the porous test section of the 10-foot- wide path is that rainwater can filter directly through the asphalt pavement and through the thick open-graded stone bed underlying the pavement. How can water pass through asphalt? The recipe for the asphalt is essentially altered to skip the sand particles that usually fill in the gaps between larger rocks in the mixture, said Kim Ballweg, Ayres’ supervisor of construction services. One factor to consider in using porous paving is the higher maintenance involved in keeping the pavement swept clean of leaves and sand that can clog the openings that make it porous. EFFORTS CONTINUE ON COLORADO POST-FLOOD RECONSTRUCTION When a historic flood hit Colorado in September 2013, the flooding on the Big Thompson River destroyed a stretch of U.S. Route 34 that serves as the main corridor between the northern Colorado city of Loveland and Estes Park, a major tourist destination and gateway to Rocky Mountain National Park. Since the flooding, engineers at Ayres Associates have been working with the Colorado Department of Transportation (CDOT) and a team of engineering firms to design permanent repairs to the road. Ayres already has performed geomorphic and hydraulic field assessments of the roadway corridor and has developed pre-flood, existing conditions, and design conditions 2-dimensional hydraulic models of the corridor. This modeling provides detailed velocity, water surface elevation, and shear stress data for a 24-mile reach and supports channel rehabilitation design efforts, proposed roadway alignment and profile development, roadway repair scour protection and countermeasure design, and floodplain regulatory compliance. Ayres’ water resources engineers have designed embankment protection for U.S. 34 over damaged areas. Additionally, the team continues to work with Muller Engineering to develop channel rehabilitation plans for an approximately 10-mile reach between Waltonia and the mouth of the Big Thompson River canyon. Ayres is also performing hydraulic analyses for local access bridge design work along the stretch. Construction is now under way on the permanent road and bridge repairs, but much remains to be done. The current construction elements realized significant cost savings, allowing CDOT to add additional design elements, including local access bridge design. Ayres and the rest of the design team are now working to educate the construction management team on the project’s various design elements and will help keep the contractor up-to-date on any design changes that arise, said Will deRosset, an Ayres water resources engineer who has been working on the project since its inception. The bulk of the work is expected to finish by the end of May 2018, when the road will reopen to the public. │17