Vista View

Prior to closing the landfill, Solid Waste Services had to develop a plan to be approved by the Arizona Department of Quality (ADEQ) and the Environmental Protection Agency (EPA). In accordance with EPA regulations and approved by ADEQ, the landfill now includes a geosynthetic clay liner, and uses an evapo-transpirative cap that prevents infiltration through the use of natural systems. The division still manages and monitors the post-closure environmental elements that primarily revolve around a flare station that burns off the excess gases generated from the decomposition of waste.

“Once the closing procedures were executed and the work was completed … we were able to proceed with the planning and developing for the park site, and that began with adding the additional layer of dirt on top of the engineered cap to provide the necessary buffer zone from the landfill,” says Tolle.

Safety regulations allow for limited shrubs and trees, which will be featured at the bark park area, ramadas and along parts of trails. Aside from native landscaping, there will be grass areas in the bark park.

Elevating The Landscape

Extending the engineered cap with more surface soil required a massive excavation and soil transfer from another nearby future park site called NozomiPark. The removal of 300,000 cubic yards of dirt had an impact on several fronts–it created a needed flood basin for the city, set the foundation for NozomiPark’s development, and elevated Paseo Vista’s grade to a level that afforded a proper base for developing the infrastructure and landscape.

“We needed fill to raise the dirt level above the landfill cap, and being able to draw from the Nozomi site across the street proved to be very convenient and efficient in the whole process,” says Brett Fowler, Project Manager for Tempe, Ariz.-based Valley Rain Construction Corporation.

A section of road that separates the two park sites was closed to ease traffic congestion and expedite the dirt relocation. Overall, the site received more than 478,000 cubic yards of soil above the cap. In addition, many mesquite trees were salvaged from NozomiPark, and will be replanted at Paseo Vista. The new landform creates an overlook that is the second-highest point in the city.

“Building up the dirt level presented a significant challenge as we had to continue to add more than we had anticipated, as there was some settling and shifting of the ground surface and grade changes in the early going,” Fowler says.

As Paseo Vista has developed, its configuration and contours have gradually taken shape as the land and its additional landscape fill have settled. There are 26 moisture sensors throughout the park that will indicate if moisture levels are approaching the landfill cap.

Environmental And Artistic Elements

Since the park is rising from a landfill, city officials also wanted to incorporate components that would not only educate the public on the value of recycling but demonstrate unique ways that recycled materials could be reused. Salvaged tires were used to form retaining walls, the safety backstop to the archery range and a colorful retaining wall in the children’s play area. Large quantities of reclaimed sidewalk and other concrete were used to form additional retaining walls and curbing, while the drive surfaces make use of milled asphalt from other city street-improvement projects. There also will be an interpretive area with art made from a cross-section of materials normally found in a landfill.

Gabion basket walls were used throughout the site as a major piece in preserving the land formation, protecting against erosion, and expediting the run-off of excess water into three major retention basins at the corners of the park. They also project an aesthetically appealing look by using stone that enhances the visual character of the Gabion walls as landscape features. Rainwater will run through a collection of channels, slowing the velocity and alleviating erosion before emptying into the basins, while an elaborate automated irrigation system will tend to the vegetation.

“The operating theme for the site is no penetration or infiltration into the protective cap, while allowing for ventilation through the landfill gas-collection system to the flare station,” Wilson says.

New Urban Park Experience

Upon completion, Paseo Vista Recreation Area will provide a panoramic view of the entire city and adjoining Paseo Trail that serves as a bicycle-friendly, jogger’s paradise. It makes efficient recreational use of a massive land space for the surrounding community that would otherwise have remained dormant within a growing, affluent section of the city, and it has the potential to be a test case for other Arizona cities and developers considering similar landfill redevelopment projects.

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