George "Doc" Cavalliere Park

Challenge

Doc Park is located within a site that also serves as a regional detention basin to manage stormwater from several upstream developments. Early investigations in the design process uncovered that elements of the previous stormwater management system had been improperly constructed, causing the basin capacity to be undersized. The hydrology report indicated that an overall volume of just under 50 acre-feet was required for the system to provide the correct amount of storage. This requirement conflicted with the original design intent to limit construction disturbance, as proper excavation for this volume would dramatically increase the area of disturbance.

Solution

To limit the impact of disturbance, the design team utilized a system of over 4,000 gabion baskets to create a vertical retaining wall system to shape the detention basins. The retaining walls allow the basin to have a steeper slope, incorporating more storage volume into a smaller area. The gabion baskets increase porosity for water flow and have an aesthetic that blends into the surrounding context. This design solution prevented additional habitat disturbance, and the areas that were preserved can now be enjoyed via a new hiking trail.

• The park functions as a regional stormwater management facility for several upstream developments. Off-site stormwater and runoff generated by the park are detained in large basins and slowly released downstream when storm events are large enough. The basins are planted with native riparian plant communities.
• More than 4,000 stacked gabion baskets create vertical retaining walls to form the detention basins. They are filled with locally-sourced rock, which helps integrate the park into the surrounding desert landscape.
• Over 300 native plants identified in the City of Scottsdale protected plant list were salvaged for reuse or preserved in place. Preserved species include species of concern such as the Saguaro, Barrel Cacti, Desert Ironwood, Mesquite, Cottonwood, and Soaptree Yucca.
• The landscape design utilizes a completely native plant palette diversified with Arizona Upland and riparian plant communities. The planted species include: Velvet Mesquite, Blue Palo Verde, Arizona Cottonwood, Creosote, Brittlebush, Saguaro, Soaptree Yucca, Penstemon, and Desert Marigold.
• Site disturbance was limited during construction by locating fencing within 11 ft of grading limits and by staging construction within the previously disturbed portions of the site.
• The top 4 inches of soil was harvested and stored on-site during construction. The topsoil was then redistributed at the end of construction to restore important microorganisms and organic matter.
• A total of 35,658 sf or 30% of paved surfaces are permeable, including the parking lot, which is paved with stabilized decomposed granite. Granite for the paving was harvested from material found on site.
• A total of 63% of materials, including granite topdress, gabion rock, concrete, and plant materials were purchased from sources within 300 miles of the site.
• The park features 4,387 ft of compacted decomposed granite hiking trails, including an accessible trail designed to meet ADA specifications.
• A drip irrigation system with a smart controller efficiently irrigates plants during the establishment period of 3 years for trees and 1 year for shrubs. Once the plants become established, the landscape will be weaned off regular irrigation and the system will be turned off.
• An array of 61 photovoltaic panels installed on the main shade structure is designed to provide an output of at least 24,000 kWh of power each year.

• The parking lot, entry drive, and pathways are constructed from stabilized decomposed granite harvested from the site. The material cost for this was approximately $87,300. To cover the same area, the material cost for a typical asphalt entry drive and concrete paths would be approximately $206,600. This represents a material cost savings of $119,300.

• Once park construction began, the City of Scottsdale was faced with significant budget cuts that greatly impacted park operations and maintenance. This meant that while the City was able to complete the construction of the park, their ability to maintain the park as designed was greatly challenged. At the same time, the construction phase of the park was coming in under budget. Since the park was funded through a bond initative, the construction funds would be lost if they were not utilized. In response, the City worked with their consultants to find ways to shift some maintenance costs into the construction phase. This included extending the contractor’s maintenance period and changing the planned turf panels to artificial turf, which costs more to install, but has lower ongoing maintenance costs.
• One of the adjustments made in construction was to replace the turf panel adjacent to the playground with artificial turf. This is the first such installation of artifical turf in a public park for the City of Scottsdale. One concern with artificial turf, especially in the southwest, is that the surface temperature can become quite hot. A sprinkler irrigation system installed in the artifical turf helps to mitigate the surface temperatures by allowing visitors to cool the turf when needed. Initially this system was set up with a push button option that visitors could press when needed. That system had to be revised to operate only during particular times of day to avoid overuse of water by visitors.

Plants: Mountain States Wholesale Nursery
Lighting: Bega, Visionaire Lighting, Winscape, Beta LED 
Gabion Baskets: Hilfiker Retaining Walls
Gabion Rock: Granite Express
Photovoltaic Panels: Centrosolar C-Series
Granite Stabilizer: Soil-Loc 

Project Team

Client: City of Scottsdale
Landscape Architect of Record: JJR, LLC and Floor Associates
Architects: Weddle Gilmore Architects
Civil Engineer: Kland Engineering
Structural Engineer: Bakkum Noelke
Electrical Engineer: Woodward Engineering
Hydrology Engineer: Argus Consultants
General Contractor: Markham Contractors

Role of the Landscape Architect

The landscape architect for the project held the primary contract with the City of Scottsdale and coordinated all public outreach, design subconsultants, permitting, and construction administration. After construction the design team successfully coordinated the documentation process for the Sustainable Sites Initiative Pilot Program earning a 3-star certification.