The City of New Berlin was faced with a difficult design challenge for a 7-block section of alley in the Buena Park neighborhood. The north side of the alley supported a commercial area and the south side consisted of residential properties. The commercial area was upslope and drained across the alley which then impacted the downstream residential properties. Due to existing utilities, there was no place to put a storm sewer system. The City wanted to take advantage of a Green Solutions grant from the Milwaukee Metropolitan Sewerage District (MMSD). The solution was a porous asphalt pavement to provide storm water storage, filtration, and conveyance.
The final design incorporated a 4-inch thick porous asphalt pavement with a 12-inch thick open graded stone base underlain by a filter fabric. The entire pavement structure then drained into a 6-inch drain tile system which then discharged to local ditches at the end of each block. During construction, poor soils were encountered underneath the drainage layer which required undercutting and compaction of new base material. There were concerns that the compaction of the subbase may affect the final drainage properties of the road base storage area and drain system. The construction of the project was completed in October of 2016. During the approximate 100-year storm event in July 2017, the pavement received its largest test and passed with flying colors. During the storm, no runoff reached the residential properties that would normally have flooded. The combination of proper design and construction techniques, along with grant funding from MMSD, made this a project that will serve the City for many years to come.
For more information on how your organization can benefit from the innovative use of porous asphalt pavement contact an expert at R/M today.
About the Author
Kenneth R. Ward, P.E.
Ken has been with Ruekert & Mielke, Inc. (R/M) since 1984. He has worked as a primary client contact, project manager and project engineer on a variety of municipal infrastructure projects including streets, alleys, sewers, storm water management, bike route trails and water mains. He has an extensive background in construction inspection, public involvement and public assessment of municipal improvements.