A LOOK AHEAD
Here is a quick glimpse into projects in the works
across the country. Watch for more on them in our blog
(AyresAssociates.com/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.
AyresAssociates.com
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