Finalist 07185 - Green Roadway
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Finals Event presentation from team of TBG Partners, Pate Engineers and the Lady Bird Johnson Wildflower Center (Steve Windhager speaking).
![[object Object],[object Object],[object Object],Design Approach: Reclaimed Roadway](https://image-private.slidesharecdn.com/grlbwfcaudio-100223151614-phpapp01/85/slide-1-320.jpg?hdnea=acl=/grlbwfcaudio-100223151614-phpapp01/85/slide-1-320.jpg*~exp=1714967142~hmac=41da78044aea8c2a0ec45b59bdfdab9e2b584d1e4f8947ac7c20641d7eb1a155&cb=1266944638)
![3 Core Integrated Principles ,[object Object],[object Object],[object Object],[object Object],Low Impact Development (LID) Reduce volume and rate of storm water runoff through restoration of hydrologic function.](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
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Finalist 07185 - Green Roadway
- 6. Perspective Section Not To Scale Biofiltration Storm Water Treatment
- 11. Pre and Post Development Hydrograph
Editor's Notes
- Our team of ecologists, landscape architects and civil engineers have created a design that will provide for the economic, ecological and social sustainability of Independence parkway. Our design approach -- “The Reclaimed Roadway” concept -- focuses on the application of tested Low Impact Design approaches, innovative use of reclaimed materials and core design elements that respond to the unique context of Independence Parkway.
- There are 3 Integrated Principles we followed through this design: A focus on water through Low Impact Development A focus on place through Context Sensitive Solutions (CSS) And the application of appropriate Transferable Renewable Technology (TRT)
- The LID element of our design creates a broad, vegetated median that restores natural bio-filtration services to the soil. The solution: -Improves water quality and increases detention capacity. -Increases soil porosity and infiltration rates through the use of recycled materials. -Minimizes the use of piped conveyance for storm water and reduces outfall depth requirements. -and, oh yea, this is going to save the county money as well. By reducing the capital costs of roadway construction by 12% compared to conventional roadway design.
- Specific to the project site along Independence Parkway, our landscape design responds to the cultural and historical context by incorporating interpretive design elements relating to the adjacent San Jacinto Battleground. Ecologically the design restores the coastal prairie setting with large open fields scattered with tree clusters and broad swaths of individual native plant beds.
- Our goal when considering materials for the roadway was to focus on materials that are typically waste products but that could be recycled for beneficial use. For the biofiltration mixture that provides primary stormwater treatment, we have used a mixture of recycled glass, coal bottom ash and low nutrient compost to create a filtration media which will have a high infiltration rate as well as form an excellent growing media for the selected native plants.
- This biofiltration media forms the bulk of the soil in the roadway median to create a linear series of biofiltration areas and detention ponds. Treated water is conveyed to the outfall by moving through the media itself, rather than trough a pipe. _______________ The total amount of water that will run off this site when compared to current conditions is much lower despite of adding 2 additional lanes of traffic.
- Initial testing at the Wildflower Center demonstrated that a mixture of these four materials had an infiltration rate of approximately 30 ft./day, and a void space of approximately 42%. In addition, RHA’s high field capacity makes it a valuable soil amendment for plants during drought periods. ------------------------------------- Existing literature and research has shown that BA is inert with regards to the leaching of heavy metals and toxins when tested without plants. Should future research including plant growth indicate otherwise, our media mixture ratios could easily shift to maintain the same filtration properties using only RG, RHA and compost. ( Alsup S., S. Ebbs, and W. Retzlaff. In press; Mudd, G. M., and J. Kodikara. 2000; Snodgrass E. C. and L.L. Snodgrass. 2006; Wearing, C., J. D. Nairn, and C. Birch. 2004).
- The biofiltration media is currently being tested at the Wildflower Center. Unlike sand, a mined material often used in filtration media, the proposed media mixture gives new life to local waste products (simultaneously augmenting the local economy) that would otherwise end up in the landfill. Plant roots maintain media porosity over time and will extend the functional live of the filter media to well over double of the lifespan of a sand filter alone and will reduce maintenance over the life of the roadway compared to conventional measures. The proposed design over-treats the run-off. So even if infiltration is reduced over time, the goals of the program are achieved.
- roadway within the median. Detention occurs in the southern 70% of the site with median breaks acting as hydraulic grade control structures. Overall, the entire roadway has a run-off rate 30% below the background condition of no-road. The median is effectively on long water quality pond with a 20 ft flat bottom with 30 inches of biofiltration media that extends along the entire length of the
- Rainfall falling on the roadway, as well as run-on from adjacent sites is directed to the median for detention and treatment. An overflow culvert with a flow line above the Water Quality volume allows for conveyance of a 3-year storm event and detention of larger events. Turning lanes act as broad-crested weirs to convey floodwater in extreme events while keeping the primary driving lanes safely free of floodwater even in a 100 year storm. The Biofiltration media captures over 8 tenths of an inch of stormwater runoff and the design ponds an additional 1.3 inches of runoff for later treatment. This provides for a total treatment of the first 2.1 inches of rainfall on the roadway to a 96% removal efficiency for Total Suspended Solids. ______________________ CUT TEXT The median provides conveyance in lieu of storm sewer, both through the biofiltration media as well above ground, greatly reducing infrastructure costs.
- This Hydrogragh shows that the proposed design actually reduces the peak flow beyond predevelopment conditions, providing for a more sustained and high quality baseflow to the bayou from storm events. When you compare the proposed design to the background condition of “no road” what-so-ever, this design reduces the flow rate of run-off leaving the roadway by approximately 20%. This results in an overall decrease flooding potential while increasing traffic capacity. --------------------------------- Modeled the roadway in HEC-HMS. Water Quality ponds add a retention element and hold the water to be filtered through the media. This was not included in the detention calculations resulting in a more conservative design.
- The Landscape plan directly responds to the historical nature of the San Antonio Battlefield through 4 elements: -10 Star Icons – represent the 10 States added to the US -46 swaths single native species plantings – represent the 46 days between the fall of Alamo and the Battle of San Jacinto. -18 tree clusters - represents the 18 minutes of the Battle of San Jacinto. -And then there is my favorite, the Musical interpretive roadway pavement.
- The northbound lane of Independence Parkway is the route that the Texas Republic forces traveled as they made their way to the Battle of San Jacinto. Along with cries of “Remember the Alamo!”, a drummer provided cadence for the Texas force’s advance by playing the beat from the popular song of a day, “Will You Come to the Bower”. The outside northbound travel lane of the Parkway will incorporate scored and grooved concrete to play this tune when traveling at approximately 35 MPH.
- As with many Harris County roadways, this project will result in excavated material haul-off. We plan to use that material less than 2 miles away by filling in the reflecting pond at the monument as recommended in the San Jacinto Masterplan Guidelines (2004). This allows the site to better emulate the conditions as they existed during the battle.
- The reclaimed roadway is projected to have a Capital Cost Savings of 12% (over project life-cycle costing) Assuming bond financing, the realized savings in financing cost is $120 per linear foot. Additionally, our design concept substantially reduces the depth required for the outfall channel saving additional funds in easements and excavation.
- While the total amount of “cut” material, 52,000 CY, exceeds conventional excavation. This is offset by reduced infrastructure costs and impacts including reduced pipe-length and excavation impacts at the channel outfall.
- Ecosystem services are those benefits that the environment provides to humans for free, which humans would have to find ways to provide for themselves if the environment ceased to provide them Luckily, these services can occur not only in wilderness but also in urban, suburban, and rural areas. Our design provides: Carbon sequestration Local and global climate regulation Air and water cleansing Water supply and regulation Erosion and sediment control Native habitat restoration Pollination Habitat Cultural benefits
- The Sustainable Sites Initiative is a newly released rating system for landscape sustainability developed by the Wildflower Center with a host of partners from around the nation. Using this rating system, our design concept for Independence Parkway would achieve 155 points earning it 3 out of a potential 4 stars.
- It is the union of ecological, social and economic goals that makes our design sustainable. By focusing on Low Impact Design, Context Sensitive Solutions and Transferable Renewable Technology, we have ensured that this roadway will exceed the goals set for it, and provide an effective model for future roadway development across Harris county and the rest of the state.