site analysis
Drainage Stormwater from UASTP, Rita Ranch, and the access road enters the Kolb Road Basin at three ~20’ inlet drop structures, as marked in red at left. Riprapped splash-pads at the bottom of the three inlets and adjacent areas appear to have partially siltified with a surface layer of fine sediment (areas in yellow.) The composition of these deposits seems to differ, resulting in variable plant growth among the three areas. Drainage from three adjacent areas was not considered in the original 1982 design, and this has caused multiple headcut rills (zig-zags in orange at left) along the
Figure 9.2.X: Deep headcutting erosion rills developed over the life of the basin, as documented by this PCRFCD filed visit in early 2008.
side slopes of the basin as the collected stormwaters pass over the top and down the side of the basin side-slopes, creating maintenance access problems (see photo below and to right.) PCRFCD has filled these headcuts with rip-rap, which only serves as a temporary solution as rills appear to the sides of the rock soon thereafter (see photo at bottom right.)
Figure 9.2.X: Rills such as the one to the left were temporarily resolved by PCRFCD Infrastructure Management staff in 2008, through slope regrading and the installation of an uncompacted slope-top berm diverting sheet flow to rip-rapped gulleys at points of heavy flow. This picture from November, 2009 demonstrates continued rilling to the left and right of a gulley.
Figure 9.1.X (right): Analysis of drainage at the Kolb Road Basin reveals problem drainage areas on adjacent parcels that were unaccounted for in original design, leading to side-slope rill erosion and soil deposition areas within the basin bottom.
Figure 9.1.X (left): Erosion rills continue to sacrifice the passability of the slope-top maintenance road.
Figure 9.1.X (above): Aerial oblique photo of sideslope erosion rills prior to PCRFCD Infrastructure Management maintenance.
Figure 9.1.X (left): Deposition of soils is storm events occurs as floodwaters from both designed inlets and erosion rills loses hydraulic energy and falls out of suspension. These have taken the form similar to the delta of a river.
vegetation Significant volunteer regrowth of xeroriparian scrub vegetation exists throughout the basin’s interior and along the inlet channels, as seen in green to left. The basin top, levees, some adjacent parcels by Kolb Road, and major portions of the basin bottom, as shown in beige, have remained denuded since original disturbance. Clay-rich sedimentation and maintenance access disturbance has prevented regrowth at the base of the side slopes. Aside from the dominant Prosopis and Baccharis, representative plants of xeric scrub, interior strand, and semidesert grassland communities occur throughout the site. Small stands of non-native Johnson grass and buffelgrass occur on site. The nearby Rita Ranch Retention Basin supports dense thickets of mesquite and cottonwood, suggesting that a similar plant communitiy could be supported at Kolb by producing slight retention
ponds to infiltrate increasing amounts of stormwater.
Figure 9.2.X: Insert picture of pooling area in basin bottom, describing clay sealing, and correlation of woody vegetation with slightly elevated areas
Figure 9.2.X: Insert picture of stunted mesquite growth where no adjacent pooling areas are present.
Figure 9.2.X (right): Existing vegetation at the Kolb Road Basin has been categorized into xeroriparian vegetation within the basin bottom and external drainages, and denuded areas on the side slopes, basin bottom, and external areas.
Figure 9.2.X (left): Picture of Upland biotic community on site
Figure 9.2.X (left): Picture of Johnson grass blowdown in front of designed inlet.
Figure 9.2.X (below): This photo, taken from the middle designed inlet shows riparian vegetation circled in red both within the basin bottom and in the upstream channel. Red areas below correlate to green areas at right. Blue areas signify areas of sparse growth, correlated with tan areas at right. <<CHANGE COLORS TO MATCH>>
planning context Current features adjacent to the site include a Burlington Northern Santa Fe/Amtrak railroad track, Kolb Road and the access road for the University of Arizona Science and Technology Park (UASTP.) The City of Tucson contracted Olsson Associates to design the dual-trail Julian Wash Greenway that extends the length of the wash, including a stretch in which it follows the northwestern and northeastern sides of the Kolb Road Basin. These plans include two interpretive stations just east of the basin. UASTP contracted The Planning Center (TPC) to create a master land use plan to drive and guide future development. The flight departure corridor of the Davis Monthan Air Force base, due to the decibel level of noise, prohibits many human uses, including gathering areas. From the northwest corner of the basin counter clock-wise, designs currently in development by UASTP and TPC staff include a park
and ride, cell tower, fire station, hotel and conference center, solar array, and the Julian Wash Greenway. Additional planned uses for the eastern area of the park include a University of Arizona extension campus (UA South,) an experimental solar array, and other additional industrial development pads.
Figure 9.3.X: Additional graphic?
Figure 9.3.X: Decibel level graphic
Figure 9.3.X (right): The UA Tech Park Master Land Use Plan, developed by The Planning Center, calls for industrial and open space usage within the flight paddle (red line,) and hospitality and public land use around Kolb Road Basin, at upper left.
Figure 9.3.X (below): The Julian Wash Greenway has been designed along the northwestern and northeastern slope-tops of the Kolb Road Basin by Olsson Associates, under contract with the City of Tucson Parks and Recreation Department. Parallel trails enter on the north side of the outlet structure, and are punctuated with interpretive nodes on both sides of a bridge at inlet #3, with excellent views of the southeastern side slopes and the basin bottom.
circulation Kolb Road is a major N-S arterial in SE Tucson that lies to the west of the site. Entry to the UASTP from Kolb is through the UASTP Road, which is seen at the bottom of the image at left. The basin, and slope-top maintenance road, can be accessed by maintenance staff either from Kolb Road, through a levee road turning off of the UASTP road, or by a gasline road paralleling the railroad track (shown in small black dashed line.) This access road currently veers away from the basin top between drop structures 2 and 3 through a drainage easement intersecting UASTP land. Olsson Associates has designed the Julian Wash Greenway to parallel the northwest side of the basin, mount the levee to the north, and cross the diversion channel on its way southeast, as shown by the dashed red line at left and the construction document at right. Maintenance vehicles will be able
to drive upon the paved path, and enter the basin top at a proposed access gate (green star.) Another trail will be surfaced with 2 inches of 1/4â&#x20AC;?-minus granite over leveled, 95% compacted native fill.
Figure 9.2.X: Insert picture of intersection of Kolb Road and UASTP road.
Figure 9.2.X: Insert cross-section detail of DG path designed by Olsson Associates.
Figure 9.4.X (right): Existing maintenance access to the basin occurs along levees, and the internal perimeter along the slopetops. The Julian Wash Greenway will replace the northwestern portion of this access road. <<REVISE GRAPHIC>>
Figure 9.4.X (left): Insert detail of interpretive node designed by Olsson Associates.
Figure 9.4.X (below): The Julian Wash Greenway (proposed) will transform provide maintenance access for PCRFCD staff along an asphalt trail that will replace the existing maintenance road along the slope tops. In addition, the existing fence will be removed and replaced with a new barricade railing located closer to the top of the side-slopes than the existing fence. A controlled access gate will be installed where the green star is located, allowing for continued access to the southeastern portion of the perimeter road to PCRFCD staff. Interpretive nodes will be located at the circular features below.
design
Phase 1: xeroriparian mitigation Phase 1 of the design includes a xeroriparian habitat mitigation area within the Kolb Road Basin parcel that will preserve the capacity of the ultimate detention basin, resolve erosion problems on the side slopes of the basin, allow maintenance access by Pima County Flood Control District Infrastructure Management staff, and allow passive recreational use by visitors.
Grading: 16 acres of xeroriparian habitat will be planted within 4 Shallow Basins excavated to a depth of 6”-1’ from the existing basin bottom. These shallow basins will be contoured with pooling areas and planting islands as described in the “Microbasins” subsection of the “Design Guidelines” above. Salvaged riparian topsoil from the Airport Wash disturbance site will be imported to the surface profile of these Shallow Basins, to allow for greater infiltration of soils by pooling water, and improve growing conditions. Soil excavated to a depth of 1.5’ across the 16 acres of the Shallow Basins will be stockpiled along the side-slopes, in two large berms that will gently drain slope runoff toward existing inlets 1-3, and rip-rapped gulleys (see figure 10.1.X.) A compacted berm will also be located along the top of the side-slope to solidify the existing drainage strategy diverting sheet flow into these designed side-slope drainages.
Access:
Maintenance access to the basin will continue from the gas pipeline road paralleling the railroad, from the N-S trending levee arriving at the central inlet, and from the southwest corner, and also from the proposed Julian Wash Greenway, when it is built. Perimeter maintenance access will be preserved along the slope-tops, which will be protected from further rill erosion. Access to the basin bottom for both maintenance staff and visitors will continue to be served by the gently-sloping existing inlets. Additional Walking Trails encircling the shallow basins will provide further opportunities for observation of wildlife and the water-harvesting features.
Phasing: Recognizing financial and political constraints, the zones of the master plan have been divided into two phases. The designed improvements of phase 1 can function with little maintenance, and can be constructed without compromising the construction feasability or function of zones included in later phases. Excavated soil material stockpiled along the side slopes in phase 1 can be used as fill and recontoured to create an expanded side-slope design, explained in phase 2.
Figure 9.4.X (right): Existing maintenance access to the basin occurs along levees, and the internal perimeter along the slope-tops. The Julian Wash Greenway will replace the northwestern portion of this access road. <<REVISE GRAPHIC>>
Figure 10.1.X (right): Off-site sheet flow runoff is diverted by a compacted berm on the inside of the access road, and conveyed along the road until it meets an existing inlet or rip-rapped channel. Rain falling directly on the side-slopes is conveyed in a simlar fashion by two more uncompacted wide berms closer further down-slope. Runoff reaching the bottom is both directed to existing pooling areas, and proposed shallow basins excavated to a similar depth.
Figure 10.1.x. Cross section AA: : Insert picture of intersection of Kolb Road and UASTP road.
Phase 2: passerines park Phase 2 of the design will take advantage of the excavated soils from phase 1 to create more extensive diversion and sideslope improvements. An expanded slope-top pathway will seamlessly connect the proposed Julian Wash Greenway to a perimeter loop of passive-recreational nature, with a parallel swale punctuated by water-harvesting basins to encourage further riparian growth. Rip-rapped channels will be removed, and low-flow diversion devices installed within existing inlets, and the ends of the vegetated runoff swales, directing them into a low-flow channel tranversing the side-slope, and will be paralleled by multi-use paths and walking paths for observation and demonstration of the riparian habitat mitigation design.
Grading: Four Low-Flow Channel Areas (~2 acres) will be constructed along the side slopes, and Off-site Runoff Basins/Swales (~1 acre) capturing nuisance off-site runoff and concentrating it into multiple Feeder Channels (<1 acre) leading to the larger low-flow channels. Side-slope areas between these larger-scaled features will be gently terraced with back-sloped On-Contour Berms to promote upland revegetation. Incoming flows from 2-year events or lesser at the three current inlets will be diverted as they crest the top of the basin through hardened structures to low-flow channels which gently descend along courses roughly parallel to the side slopes. Waters passing through these low-flow channels, contained
by a slight berm, will collect in a series of micro-basins separated by smaller drop structures of 2-3â&#x20AC;&#x2122; (see figure 10.2.X. Smaller â&#x20AC;&#x153;feederâ&#x20AC;? flows entering from the drainage problem areas or falling directly onto the side slopes will be directed into these low-flow channels through lesser bermed channels. Depending upon budget, french drains may be installed below the channels and basins of the side slope and basin top in order to enhance infiltration and encourage soilstabilizing root growth. Flows occuring in events greater than the 2-year event will bypass these low-flow channels, instead flowing directly over top of the diversion structures, and will be quickly spread by sculptural energy dissipation devices at their base in order to protect sensitive planting areas, and provide an intriguing, playful observation area. Flows of all sizes will then be directed into the Shallow Basins constructed in phase 1. The amount of soil needed to be added to the proposed side-slope improvements of phase 2 is approximately 1,027,000 cubic feet. Taking into account the excavated material available from the off-site runoff swales, and the stockpiled fill from phase 1, the cut soil available would approximately equal this amount. French drains increase the pore space of the underlying soil, and, if implemented, would increase the capacity of the basin under which they lay by approximately 1/3 to 1/2 of the volume of Figure 10.2.X (right): Passerines Park combines the drain. large-scale interior habitat areas of phase 1 with highly-interactive slope-top and side-slope improvements that clearly reveal the techniques employed to create riparian experience.
Figure 10.1.X (right): Insert Phase 2 graphic of this.
Access: The perimeter road from phase 1 will be moved in towards the center of the basin, and improved to recreational use standards. Multi-Use Path/Access Roads will descend into the basin from the proposed Julian Wash Greenway entry gate and the southwest corner and will provide pedestrian, bicycle, and maintenance vehicle access to the mitigation areas and hardened structures; another will be located along the top of the side slope. Hardened structures will be designed such that they will also serve as climbable vista points for bird watchers and other recreationists. Additional Walking Trails encircling the shallow basins and following the low-flow channels will provide further opportunities for observation of wildlife and the water-harvesting features.
Phasing: Recognizing financial and political constraints, the zones of the master plan have been divided into two phases. Improvements in phase two are of a mostly recreational and aesthetic nature, and therefore must be funded by parks and recreation funds or as part of a public-private agreement with UASTP.
Figure 10.1.x. Cross section AA: : The visitor to Passerines Park will have a variety of riparian experiences to choose among, from sweeping vistas along the busy circulatory overlook up top to the peace and solitude of the wooded canopy below. ..
future directions
Southwestern Lands Innovation Center: The University of Arizona Science and Technology Park is uniquely positioned to become the innovation hub of alternative energies and sustainable arid-land design. Tucson lies at the crossroads between cultures, nations, states, and ecosystems, and boasts an internationally-renown cadre of scientists and designers at the University of Arizona and regional companies such as Raytheon, Intuit, and UASTP’s own, IBM. As the University breaks ground on the Arizona Bioscience Park, planned to become the a state and regional leader in biotech research, the University has struggled to find additional space within its confined boundaries for the type of land-intensive research necessary for solar, wind, and hydrological technologies. UASTP currently holds ____ undeveloped acres contiguous to an already-thriving computer software and hardware development laboratory at it east end. Much of this acreage lies within the departure corridor of the Davis Monthan Air Force Base, and, due to ambient noise levels exceeding 65 decibels from engine noise, is undevelopable for offices, residential, or commercial use. Currently, the park lies on the eastern fringe of residential development in the city, and both City of Tucson and Pima County project plan for the lands surrounding it to be built out as the metropolitan area reaches it threshold long-term capacity given available groundwater resources. As such, the traditionally-undevelopable lands at UASTP within the flight paddle serve as an ideal opportunity for large, experimental solar, water and productive land use technologies, and industrial auxiliary buildings, set in the middle of a large potential future work force, with pre-built communications and utility infrastructure of the park, and easy freight access to both the Burlington Northern Santa Fe Railroad and Interstate 10. Those lands outside of the flight paddle, including the majority of lands along the proposed Science and Technology Park Road, are ideal locations for associated support offices, light commerce, residential, hospitality, park and ride, and fire station, and has been master-planned as such by The Planning Center within recent years. Like many university research parks, UASTP has been seeking the right combination of business sectors, hotel and conference capacity, and quality-of-life amenities to make it attractive to small and large businesses seeking to expand their operations. Three ideas in particular have been suggested by UASTP and The Planning Center staff over the years, to address these needs. One of these original ideas forwarded to make the park more attractive to businesses was is the creation of an 18-hole golf course, in the flight paddle, adjacent to a pro shop, conference center, and two hotels. This model of business park has seen success in many of the early business parks of the late 70s, 80s, and 90s, as it creates a pastoral grounds setting in which park employees and hotel/conference visitors can stroll, recreate, and project wealth and order in a highly formalized, business-appropriate setting. While this traditional type of business park is common in areas with more abundant resources, such as the east coast, Midwest, and West Coast, fewer examples of this type exist in the southwestern U.S., primarily due to cost of water resources. Among them are the ____ development of Louisville, CO, and numerous developments of Phoenix, AZ. However, in an arid city with a mean annual rainfall of 13 inches/year, a population base that is reaching its capacity for growth in order to maintain a sustainable yield of the Tucson Valley’s aquifer, and a city development department that controls the ratio of golf courses to population so that local recreational need is met, but draw as a golf destination is discouraged, the enormous use of water resources, even if it from reclaimed sources, should be heavily questioned. Recently, the leaders of UASTP and the designers and planners at The Planning Center have latched onto a new direction to guide the park’s future development. Their goal, now, is to make the UASTP the “greenest” university research park in the nation, one who’s physical design and business recruitment is
geared towards energy efficiency, prudent natural resource use, and further sustainable innovation. The first concrete manifestation of this new goal has been designed at the eastern entrance of the park, where a solar plaza, solar array company/startup, serving as an eastern solar anchor to define the park’s green commitment. In order to synthesize both the old dream of a hotel and conference center with the new proposed designs of the solar plaza, UASTP should build upon the water-wise development of both the Kolb Road Basin Xeroriparian Mitigation Area and Passerines Park, and anchor both the western half of the park with a motif of hydrological innovation. This development can be use both the design recommendations and site analysis from this report as guidelines for the siting of parcels. Imagine becoming fixed in discussion with a doctoral candidate of subsurface irrigation technology, picking his brain on his novel methods, and inviting him to join you for a desert dining experience on the first-floor back-porch restaurant patio, enjoying a burbling stream emanating from a gorgeous interior tinaja grotto, and watching the sun set over the city of Tucson and it’s mountains beyond, as torches alight to your sides to keep you warm against the cool, creosote-soaked breezes wafting down the Julian Wash. The next morning, you step out on to your northern-facing balcony with the morning’s cup of coffee and complimentary newspaper, as you breath in the moisture of a Sonoran desert morning, and chase the path of a mating pair of Phainopepla until you fix upon the brilliant foliage of a Vermilion flycatcher tucked between the canopy of a mesquite and the robust shrubbery of a salt-bush. Satisfied, you then throw on your power suit, zip down eight floors, and begin the day’s first event, detailing the fluid mechanics of passive solar home technologies. Following the day’s proceedings, at the personal suggestion of the keynote speaker, you and your group join him for a round of Disc golf, using discs complimentary borrowed to you by the front desk. With disc satchel and bottle of water in hand, you all stride past the restaurant porch on to the slopetop recreational loop, pausing to admire and comprehend the recreated desert wash system below at one of many interpretive nodes. Finally, you arrive at your destination, hole 1, beginning on top of the former spoils pile, once again given the opportunity to take into a panoramic view of the Tucson Valley, experimental developments already established at the tech park, and delineated building pads that, from this perspective, seem like they may be ideal locations for your company’s next endeavor. The next morning, before you leave, you once again take in the beauty of the site by lacing up your running shoes to take a 5 mile loop around the basin, east along the Julian Wash Greenway, and back around an interior loop that allows you to get a closer view of the parcels you spied the day before.
conclusion
In order to truly create a design environment conducive to combined-use detention basin design, the municipal, state, and federal agencies of a metropolitan region, including the flood control district, parks and recreation departments, fish and game agencies, Army Corps of Engineers, and Bureau of Reclamation, must not only have policy encourages inter-agency, cross-professional, collaborative work, but also must exhibit leadership from both the internal regulatory and external design professions to accomplish this goal. Risk-averse flood control districts, most importantly, must be charged with the additional uses of riparian habitat, recreation, water treatment, and landscape aesthetics from the “bundle of sticks,” and should seek the involvement of fish and game departments, parks and recreation departments, and the Army Corps of Engineers in order to acquire additional funding to accomplish these more expensive designs in publiclyowned basins. Private developers, when approaching a project, should be incentivized to create these combined-use systems by allowing them to meet overlapping code requirements of habitat mitigation, landscape buffers, recreational space, and open space within detention basins. Finally, during the design process of publicly-owned basins, needs assessments of local neighborhoods and adjacent private landowners should be considered, so that the ultimate design of the combined-use basin encourages community, environmental education, and private investment development. When compared to other southwestern U.S. arid and semi-arid metropolitan areas, Pima County has shown leadership in combining two of these uses, flood control and conveyance and riparian habitat, but falls short of encouraging interactive riparian experience and recreational use of detention basins. The Riparian Habitat Protection Ordinance has successfully prioritized a use that has always been within the charter of the Regional Flood Control District, but the “integrated program of natural resource management and flood and erosion hazard reduction” called for in Pima County Code, section 16.04.030, “to maintain a balanced and cooperative relationship between human communities and the land and resources that sustain them,” through “maintenance of natural hydrologic and hydraulic stream flow processes, with consideration for groundwater recharge, aesthetics, natural open space, recreation areas, and flora, fauna, and other wildlife habitat resources,” has marginalized the contributions that both the County’s and incorporated cities’ parks and recreation departments, and the profession of landscape architecture, can make. The Kino Ecological Research Project, held by the district as an example of this integrated approach, while being a positive step towards combined-use design with federal involvement, fails to integrate sanctioned, riparian-focused recreational use and education or a sense of aesthetic. The support of the District in creating this report, in particular the design guidelines for mitigated riparian habitat with detention basins, demonstrates a willingness to improve the design and development environment to better serve the residents of the county. These guidelines, by demonstrating a method by which riparian habitat can not only be incorporated into a site’s detention basin/s, but also improve a site’s livability and marketability, will hopefully serve as a starting point for further policy improvement and interagency collaboration in order to accomplish true integration between natural resource managers, flood control engineers, and landscape designers. Additionally, phase 1 of the Kolb Road Basin retrofit demonstrates a willingness on the part of the District to advance detention basin use in concrete form, by directing Granite Construction Company mitigation dollars from the disturbance of Upper Airport Wash into an off-site mitigation of 17 acres of xero-riparian habitat. While the designer of this project is disappointed that a more combined-use approach with collaborative involvement with parks and recreation departments and the University of Arizona Science and Technology Park was not adopted, it is hoped that the district remains committed to future phases of this design, which will truly extend its value from riparian habitat mitigation to environmental education, community recreational use, and synergistic economic benefit to the UASTP. Likewise, it is hoped that parks and recreation departments, UASTP, and their design and planning consultant, The Planning Center,
consider the ideas put forth in this report as they continue to design and define what the Julian Wash Greenway, the UASTP, and the Kolb Road Basin is to become.
Figure 8.1.9: Daniels, Alan. “Flow of a River,” from “Just add water,” Nature Conservancy Magazine. Vol. 58, no. 2 (2008): 51 Mwtoews (username,) Title: Surface Water Cycle, http://en.wikipedia.org/wiki/File:Surface_water_ cycle.svg, Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License” 04-03-2010, Northern Arizona University ENV302 Lectures: Lecture 3: Evaporation and Transpiration, Title: Mean Annual Evapotranspiration, accessed 04-02-10, <<MORE TO COME!!>>