Xylem Inc. has released a white paper outlining strategies to increase the resilience of cities around the world.
According to the United...
By 2008, the sewer system in Fruitland, Md., was more than 40 years old and in need of repair. Both manholes and sewer pipelines had significant wear and tear, with cracks spreading throughout the system. This led to water infiltration to the system, which reduced the capacity of the municipal wastewater treatment plant.
City officials needed to increase the capacity of the plant but also wanted to avoid expanding the plant itself. This meant reducing the volume of infiltration and inflow to the sewers. This proved to be no small feat thanks to the high groundwater table and sandy soil beneath the city. Planners also needed to come up with an approach that would be suitable for the varying field conditions at the sites.
Ultimately, they decided on a two-phase project. The first phase would focus on manhole rehabilitation, while the second would rehabilitate the pipelines. The order of work for each phase was determined by the potential for inflow and infiltration at a given site.
In Phase I, workers prioritized manholes based on age, depth, location and condition. Initially, each manhole was grouted to help seal up any cracks. From there, SpectraShield of the Carolinas installed a three-layer polyurea lining beneath each manhole.
Once manhole rehabilitation was complete, efforts switched to fixing the pipelines. Fruitland’s sewer system features 10,800 ft of pipes ranging in width from 8 to 18 in. The first step was adding cured-in-place pipe lining throughout, utilizing either a water, steam or ultraviolet light cure. In total, the city patched up 122 manhole covers. In addition to large cracks, there were a number of lateral-to-mains connections that had sprung a leak.
“We are extremely proud of this infiltration and inflow project and the positive impact that it has had on the city of Fruitland’s wastewater treatment plant capacity,” said Amanda Pollack, P.E., of George, Miles & Buhr.