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Dubuque Green Alley

Contact Person: John Dienst, P.E.
Phone: 563-589-4270
Project Designer:


Design:  City of Dubuque Engineering Department.

General contractor:  Portzen Construction.

Paving contractor:  River City Paving, a division of Mathy Construction.


Rainfall Managed:

Drainage area:  1 acre

Runoff per 1" rain:  27,152 gallons

Project Description:


The Green Alley program in the City of Dubuque strives to reconstruct downtown alleys using permeable pavements. Most of the downtown sits on sandy soils. The City has been reconstructing an alley or two a year for the last several years. This continues to be a priority of the City Council.



This project involved the reconstruction of an alley in dubuque using porous asphalt as the final pavement. The alley is between White and Jackson Streets from 12th to 13th Streets. The alley involved the replacement of the watermain and corresponding services the replacement of the sanitary sewer manholes waterproofing of adjacent structures and placement of clean stone and porous asphalt.


County: Dubuque
Construction Start Date: June 2009
Construction Completion Date: September 2009
Cost Per Square Foot:


The porous asphalt pavement portion of the project including clean stone amounts to $30,000; with all utility project cost was $100,000.


Performance to Date:


The alley has performed well to date. The biggest issue is the tracking of dirt or fines from adjacent gravel driveways. This alley tends to clear up sooner than the other alleys after a winter storm too.




The alley received two sweep and vacuum treatments each year. These typically happen in early spring and in the fall.  The City does not plow the alley.  We also had alleys that had gravel driveways, which increases the maintenance activity of sweeping and vacuuming. We tried to install wider collars along the alley to minimize the grit tracked onto the alley.
Lessons / Tips:


One lesson:  Make sure that the contractor keeps their equipment off of the clean rock if possible. You don't want fines tracked onto the stone. It is very important to contact all of the adjacent residents and educate them on the new pavement.


The biggest lesson learned though is to be very proactive with neighbors in talking about the benefits of the alley. The City of Dubuque marks the alleys with a Green alley stamp at each end of the alley. The residents also get a flier that explains how to take care of the alley and what not to pour onto the surface (no oil antifreeze etc.)


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