PROJECT STATEMENT: The Lost Dog Wash Trailhead demonstrates the highest potentials in Sustainable Desert Design including strategies for planning, preservation and construction. The project balances the needs of various users and conservation methodologies that protect the fragile desert ecology including minimization of site disturbance, utilization of onsite materials, solar power, composting toilets, rainwater and gray-water harvesting. Lost Dog Wash Trailhead now serves as the model for all future Preserve access areas and desert sensitive design in general.
PROJECT NARRATIVE: The Lost Dog Wash Trailhead is the third facility of nine planned public entry points designed by the design team (a collaborative effort between the landscape architect, architect and the Preserve staff) for the McDowell Sonoran Preserve. Access areas are intended to allow visitors to experience the Preserve through hiking, horseback riding, mountain biking, nature studies, bird watching, scenic viewing, picnicking, rock climbing and more. The 7-acre Lost Dog Wash Trailhead site is located at the convergence of two popular multi-use trails along the periphery of the Preserve at the foot of the McDowell Mountains, and allows access to more than 17 miles of recreational trails within the Preserve. The current assembled land area of the Preserve confines occupy more than 16,000 acres, with future land acquisition plans expected to more than double the current size to over 36,400 acres of native desert. When completed, the Preserve will encompass approximately 1/3 of Scottsdale’s total land area and will be one of the largest urban preserves in the country.
Prior to designing the first access area, the design team (lead by the landscape architect and including architects and environmental graphic designers) worked closely with the City of Scottsdale’s Preserve Trust and public steering committee to develop “The McDowell Sonoran Preserve Access Area Design and Site Standards” which set forth the goals for all projects within the Preserve. The Mission Statement for the access areas is “to develop environmentally responsible public access areas that borrow from and blend into the natural desert landforms and landscape of each specific Preserve access location.” These Standards specifically and in great detail addressed issues relating to site design and planning; site elements and required amenities; construction processes and methodologies; and review and approval processes over and above the City requirements.
The Preserve access areas are envisioned to be demonstration projects for Sustainable Desert Design practices and are intended to explore new technologies and to develop new methodologies that promote and contribute directly to sustainable design practices. The program for the Lost Dog Wash Trailhead project included new trailhead facilities, outdoor classroom areas, and trail improvements for pedestrian and equestrian uses, each being served by separate parking areas. The facilities are home to various educational programs that include guest lectures, field-based classrooms, and guided interpretive hikes that introduce participants to local area history and instill appreciation for the varied flora and fauna of the Sonoran desert.
The surrounding desert context was the touchstone for all site and architectural improvements within the project confines. Extensive studies and analyses were conducted by the design team which included archeological assessments, topographic surveys, slope and hydrology analyses, vegetation survey, soil studies, wildlife and habitat surveys, and native plant inventories. These forensic studies informed all design decisions from initial design through the project’s construction phase. All program elements (vehicular access, parking areas, circulation routes and restroom facilities) were located between existing desert washes, to minimize environmental and visual impacts and fit unobtrusively into the existing landscape. Generous native landscape areas with smaller wash corridors were left undisturbed and protected throughout construction between parking aisles to accept drainage while preserving large swaths of desert vegetation.
The early studies were frequently reviewed and proposed development limits were repeatedly fine-tuned allowing for maximum preservation of native trees and cacti stands. Where development necessarily disturbed native desert, existing vegetation, native trees, cacti, shrubs and natural artifacts were salvaged, stockpiled, and reinstalled on site as part of the planting design. In all over, more than 1,000 specimens were salvaged and reintroduced to the site as part of the revegetation effort.
The planting concept is derived entirely from the site itself. As part of the site analysis process, the landscape architect conducted extensive field surveys to determine specifically what plant species were indigenous to what areas of the site, including cataloging of plant densities and plant associations. In the desert, plant species, densities and associations can vary widely within even relatively small sites due to such environmental influences as drainage patterns, soil characteristics, exposure and elevation. This data was used to “re-vegetate” the site to replicate pre-construction conditions. Re-vegetation efforts mirrored the symbiotic plant relationships of the surrounding Sonoran desert and drew from native plant densities and growth patterns cataloged prior to construction. The focus on these patterns and densities helped to ‘blur the edges’ of natural and recreated landscapes as well as to preserve and protect wildlife habits.
In addition to the native plants, the top four inches of native soil and native “Desert Pavement” cobble within the limits of disturbance were salvaged and stockpiled for later redistribution. This allowed the project’s top-dressing to seamlessly integrate into the adjacent coarse and rugged desert floor. The desert cobble textures allow the establishment of plant communities by providing a protected place to take root.
Construction was carefully monitored by the landscape architect, and the Design Standards strictly enforced. This included paying close attention to the construction envelope to reduce site disturbance and limit activities to designated areas; designating staging areas for materials and equipment and restoring these areas upon project completion; and developing a stringent construction recycling program.
Over 70 percent of building materials were of local origin or directly supplied from the site in the form of native soils and screened rock materials. The parking lot areas and vehicular drives were constructed of stabilized decomposed granite, in lieu of traditional paving materials, to increase percolation and minimize surface runoff and heat gain. Stabilized granite parking areas and trail surfaces utilized screened site soils to match the adjacent colors and textures of the desert floor. All exterior walls of Trailhead structures are rammed earth, whose soil source came from site excavations and further balanced the site in regard to import and export of site soil.
All trailhead structures’ metal roof panels, steel panels and steel framing members were left in their unfinished raw state and allowed to naturally rust and patina, thus avoiding the use of paint or other potentially toxic finishes. This natural approach was extended to include the site furnishings, such as light bollards, trash receptacles, and vehicular wheel stops. The Trailhead lavatories use composting toilets that provide an annual savings of 20,000 gallons of water compared to conventional systems and eliminated the need for installation of municipal sewer lines. The rooftop panels of the main Trailhead structure house a 2,000-watt solar array that allows the Trailhead to be self-sufficient and independent from the municipal electric grid. The array powers LED lighting and a drinking fountain chiller. The project is essentially “off the grid” with no utility connections, save potable drinking water.
Rainwater from the roof of the main structure and gray-water from its lavatory sinks and drinking fountains is collected and stored in a 4,000-gallon underground cistern. This gray-water is reused by the drip irrigation system as supplemental water to new landscape plantings. A two-year timetable was set to wean new plantings from irrigation, thus relying solely on natural rainfall. A temporary irrigation system utilizing potable water was used for initial establishment, particularly for the dry-scattered seed mix, and has since been phased out, as initially planned. The collected gray-water will continue to provide supplemental water during severe summer months to offset a long-term drought the region is experiencing.
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PROJECT RESOURCES |
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Owner:
City of Scottsdale
Landscape Architect:
Floor Associates, Inc.
FA Project Team:
Christopher Brown, Project Principal
Rick Jones, Senior Project Manager
Mike Faulkner, Alex Howell, Rayka Robrecht
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Architect:
Weddle Gilmore Architects
Philip Weddle, AIA
Civil Engineer:
DMJM
General Contractor:
Valley Rain Construction
Rammed Earth Contractor:
Rammed Earth Solar Homes
Steel Contractors:
Kovak, Inc.
Cave’s Canopies
Photovoltaic:
American Solar Electric |
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