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GREEN ROADWAY Team O7187 Competition Submittal


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Electronic submittal from the AECOM team

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GREEN ROADWAY Team O7187 Competition Submittal

  1. 1. Green RoadwayDesign Challenge- A New Sustainable Standard -<br />TEAM ID: 07187 <br />
  2. 2. The Program<br />An approximately one mile stretch of the existing Independence Parkway within Harris County Precinct Two will be expanded from a traditional two lane roadway with drainage ditches on either side to a four lane thoroughfare. The challenge is to design a new ‘green’ roadway section that incorporates Low Impact Development techniques, promotes infiltration, reduces stormwater pollution, and reduces long term maintenance costs.<br />Our Objectives<br /><ul><li>Develop a new sustainable standard road section for existing county ROW’s that can serve as a model for future roadways
  3. 3. Develop an approach that is innovative, affordable, sustainable, and aesthetically pleasing
  4. 4. Develop an approach that works today and offers more possibilities in the future</li></ul>Click to access Aerial Map<br />Low Impact Development Contest - Overview<br />
  5. 5. Click to access<br />the written<br />Design Narrative<br />Reduce total development cost andmaintenance cost <br />Manage stormwater in the ROW with LID Integrated Management Practices (IMP) <br />Reduce stormwater runoff peak discharge rates<br />Eliminate storm sewers and minimize drainage infrastructure <br />Minimize and disconnect impervious surfaces, lengthen time of concentration and promote bio-filtration of runoff to improve the quality of stormwater leaving the site<br />Use small-scale landscape features <br />Minimize the need for potable water and irrigation <br />Enhance aesthetics and interface with Project Stars<br />Increase marketability of development<br />Conserve natural resources <br />Recycle materials when feasible<br />DESIGN GOALS<br />
  6. 6. Click to access<br />photos of the<br />existing roadway<br /><ul><li>Two-lane asphalt roadway with shoulders and roadside ditches on both sides
  7. 7. Roadway width along with the shoulders is forty feet (40’) with 12’ lane widths and 8’ shoulders.
  8. 8. The remaining space within the right-of-way is used to convey runoff in the roadside ditches</li></ul>Existing Roadway<br />
  9. 9. <ul><li>Roadway section contains 4 – 12’ lanes, concrete curb and gutter drainage system, and a 32’ raised median
  10. 10. Runoff is collected in the inlets and conveyed in a storm sewer beneath the median of the roadway</li></ul>Standard Roadway Detail <br />
  11. 11. Storm Sewer <br /><ul><li>Stormwater disposal mentality: efficiently convey water from roadway with costly mitigation or control assumed at end of pipe / outfall
  12. 12. Requires stormwater conveyance in roadway for extreme events
  13. 13. Minimizes variety of vegetation creating monotonous landscapes which are unable to support native birds, animals, insects, etc.
  14. 14. Provides no treatment of highway runoff resulting in large discharges of pollutants to the bayous and bays of the region</li></ul>Standard Roadway Assessment<br />
  15. 15. <ul><li>Four-lane median divided concrete roadway with outside swales within 120’ of right-of-way
  16. 16. Has an inward sloping roadway with continuous curbs on the outside and slotted curbs on the inside
  17. 17. Roadway Runoff is conveyed into the 48’ swale median
  18. 18. Outer roadside swales are approximately 12’ in width</li></ul>Proposed Green Roadway Detail <br />
  19. 19. 120’ ROW<br /><ul><li>Utilizes a wider median for stormwater capture, water quality management, bioswales, rainwater harvesting gardens, and ornamental plantings
  20. 20. Includes linear detention in median for runoff control
  21. 21. Enhances aesthetics and natural habitats</li></ul>Proposed Green Roadway<br />
  22. 22. Use wider median to manage stormwater runoff and provide opportunities for landscaping<br />Use culverts as restrictors for linear detention stormwater management<br />Use slotted curbs to allow inward sloping roadway and median collection of runoff <br />Eliminate the need for underground stormwater infrastructure<br />Use native plants and grasses along water quality swales (bioswales) to slow down water runoff and improve water quality<br />Develop a standard blend for seeding that can be installed to provide both short-term and long-term slope stabilization <br />Install underground cisterns to capture stormwater runoff and irrigate with solar powered drip irrigation system (optional)<br />Click to access Site and Drainage Plan<br />Proposed Green Roadway – Engineering Plan<br />
  23. 23. <ul><li>The objective of landscaping plan is to enhance aesthetics, create a sustainable environment, minimize runoff, and utilize resources within the ROW
  24. 24. The landscaping includes native and indigenous plantings along the bioswales and rainwater harvesting gardens and ornamental massing to provide visual interest
  25. 25. Solar powered drip irrigation could facilitate the use of ornamental plantings with greater water demand
  26. 26. Switchgrass could be planted along the edges of wider ROWs or on adjacent public land
  27. 27. Switchgrass could be left unmaintained or could be harvested and sold as biofuels</li></ul>Click to access Landscaping Plan<br />PROPOSED GREEN ROADWAY – LANDSCAPING OVERVIEW<br />
  28. 28. <ul><li>The median includes a meandering bioswale down the center
  29. 29. The bioswale consists of native grasses, shrubs, and selected trees
  30. 30. Dry creek beds are located at crossings and driveways
  31. 31. Rainwater harvesting gardens are located in selected areas. In appropriate sites (where sandy/loam soils exist), they allow water to percolate into the soil
  32. 32. Underground cistern is used to capture stormwater for irrigation
  33. 33. Ornamental plant massings are added in selected areas for visual interest. These massings could be integrated with Project Stars monuments
  34. 34. Switchgrass is planted in wider ROWs and along adjacent public land. Once harvested, the grass is used for biomass or for hay</li></ul>Click each image to access detailed Landscaping Plans<br />PROPOSED GREEN ROADWAY – LANDSCAPE FEATURES<br />
  35. 35. Fraxinus pennsylvanica <br />Conoclinium<br />coelestinum<br />Hibiscus aculeatus<br />Tripsacum dactyloides<br />Phlox divaricata<br />Wedelia texana<br />Chasmanthium latifolium<br />Sorghastrum nutans<br />Taxodium distichum<br />Lobelia cardinalis<br />Wedelia texana <br />Panicum virgatum<br />Andropogon virginicus<br />Landscaping – Native Plant Material<br />
  36. 36. Dry creek beds are located at crossings and driveways. They provide the functionality of riprap for erosion control, enhance aesthetics and visually integrate with bioswales.<br />Landscaping – Dry Creek Beds <br />
  37. 37. Cercis canadensis var texensis - Texas Redbud<br />Cyrilla racemiflora - Leatherwood<br />Wedelia texana <br />Ornamental massings are located along selected parts of the ROW to enhance visual character and to serve as focal points, including along sculptures as part of Project Stars. They are irrigated with water captured on-site. <br />Landscaping – Ornamental Massing<br />
  38. 38. Tripsacum dactyloides<br />The wide median is slanted inward towards the middle to collect stormwater. Bioswales are used to slow stormwater runoff and improve water quality. In selected locations, rainwater harvesting areas are used to capture stormwater, either allowing the water to percolate into the soil (where sandy/loam soils exist) or to be directed into an underground cistern for later on-site use.<br />LANDSCAPING – BIOSWALES & RAINWATER HARVESTING<br />
  39. 39. Optional on-site irrigation for ornamentalplantings is handled by capturingstormwater runoff in underground cisterns<br />Cisterns located in rain harvesting areas<br />Solar powered drip irrigation system (1 GPM up to 50 PSI)<br />80W solar panel and mount<br />ShurFlow 9300 pump (&lt;45 Watt, 2.5 amps)<br />ShurFlow 902-200 Pump Controller and level monitors<br />2500 gallon cistern<br />Drip Irrigation lines and emitters<br />Total cost approximately $12,000 per station <br />Long term costs include: pump repair/replacement (every 5 years). Solar panel replacement (every 15 years), and cleaning out cistern (every 2 years)<br />Solar powered drip irrigation will reduce long term maintenance costs<br />Demonstrates how solar energy can be used along highway ROWs<br />Educational signage will be included to inform public about the approach<br />SOLAR POWERED DRIP IRRIGATION<br />
  40. 40. Switchgrass could be planted in areas with expanded ROWs. Utilizing different switchgrass species of varying heights will create an attractive visual element<br />Switchgrass is a native warm-season, perennial grass indigenous to Harris County, and its high cellulosic content makes it a good source of biomass<br />Seeds from local switchgrass colonies collected by TX Agriculture Research Stations should be utilized. Yields in the Southeastern U.S. typical range from 7 to 16 tons per acre<br />The switchgrass does not have to be harvested every year, and could be maintained for its aesthetic qualities<br />Switchgrass can be located so it does not interfere with site lines<br />Click to access Bio-harvesting Area Plan<br />BIO-HARVESTING IN AND ADJACENT TO THE ROW<br />
  41. 41. To make LID attractive in the Houston Region, we must show cost effective, long-lasting benefits <br /><ul><li>Stormwater benefits must be quantifiable and long lasting
  42. 42. Regulatory approval is dependent on permanent benefits which will not decline over time
  43. 43. Modeling methodologies must be defensible and Houston appropriate
  44. 44. Integrated management practices must be low maintenance
  45. 45. Design must improve aesthetics and offer additional amenities over standard approach
  46. 46. Cost must be equal to or less than the standard design approach</li></ul>LID STORMWATER MANAGEMENT REQUIREMENTS<br />
  47. 47. Stormwater Integrated Management Practices<br />Meandering bioswales along both sides of road and in enlarged center median<br />Thick vegetation to reduce flow velocities and filter stormwater<br />Linear detention concept in median to attenuate peak flows<br />Incorporate rain gardens into bioswale where appropriate <br />Incorporate underground cisterns on-site to store water for uses such as irrigation of newly installed and permanent plant materials <br />Stormwater Management Goals:<br />Reduce peak discharge belowexisting conditions<br />Contain all flooding in the ROWwith no roadway flooding<br />Improve runoff water quality<br />Managing Stormwater in the ROW<br />
  48. 48. Defensible Houston Appropriate Methodology<br />Hydraulics based analysis versus standard volume based analysis<br />No reliance on enhanced infiltration or adjusted Curve Numbers<br />HEC-HMS Hydrology / EPA-SWMM Hydraulics<br />Dynamic modeling of roadway drainage system<br />Uses linear detention concept with vegetated bioswales<br />Mimic timing and peak of undeveloped site<br />Contain all flooding (up to 100 year) inside the ROW with no roadway flooding<br />Hydrologic and hydraulic analysis of different roadway types demonstratesthe significant impact LID drainagedesign strategy has on peak dischargeand flooding<br />Click to access Hydrology & Hydraulics Report<br />HYDROLOGY AND HYDRAULICS<br />
  49. 49. 100 Yr. flood is contained inside the median with no roadway flooding<br />HYDROLOGY AND HYDRAULICS RESULTS<br />
  50. 50. <ul><li>Hydraulics based approach is more reliable and defensible than volume based LID hydrology
  51. 51. This analysis shows that it is not necessary to enhance or increase infiltration to mimic the natural response of a watershed
  52. 52. No additional infiltration was included in this analysis and only reliable, quantifiable, and justified modeling strategies were used to assess the benefit of LID design</li></ul>100 yr Green WSE Profile<br />10 yr Green WSE Profile<br />HYDROLOGY AND HYDRAULICS – CONCLUSION<br />
  53. 53. Standard cross section with storm sewer:<br />Transfers pollutants into storm sewer with no treatment<br />Facilitates direct discharge into receiving water bodies<br />Green Roadway median meets criteria designating it as a water quality swale:<br />Average slope of the watershed is &lt; 5%<br />Soils have an infiltration rate of 0.18” per hour<br />Cross section of the channel carries normal flows at a depth of the normal vegetation height<br />Longitudinal slope is less than 1%<br />Click to access Highway Runoff Pollutants Report<br />Highway Runoff Pollutants<br />
  55. 55. Bioswale and associated plantings will improve water quality with significant reductions in TSS, Metals, Nitrogen, Phosphorous, Oil and Grease, Pathogens, and other harmful pollutants<br />Predicted to average 84% TSS removal<br />Predicted to average 68% metals removal<br />Predicted pathogen remove of ≈ 30%<br />Ability to treat &gt; 1” of stormwater runoff through infiltration and flow through bioswales<br />HIGHWAY RUNOFF POLLUTANTS CONCLUSIONS<br />
  56. 56. <ul><li>Approximately 7% increase in impervious cover vs. existing roadway (no change vs. standard 4-lane roadway)
  57. 57. Approximately 70% reduction in peak stormwater discharge at outfall
  58. 58. Complete containment of flooding inside median
  59. 59. Drivable roadway under all flooding conditions
  60. 60. Significant improvement in water quality of stormwater discharging into Galveston Bay
  61. 61. New habitat for coastal wildlife and native plants
  62. 62. Educational and marketable showcase for native vegetation and innovative technologies </li></ul>Environmental Impact Statement<br />
  63. 63. Greater Benefit for 13% Lower Cost<br />Standard 4-lane detailed cost estimate: $4.97 million <br />Green LID 4-lane detailed cost estimate: $4.32 million<br />Cost estimate prepared with identical unit costs to facilitate honest cost comparison<br />Primary cost reductions:<br />Storm Drainage<br />Slight cost increases:<br />Earthwork<br />Primary cost increase:<br />Landscaping<br />Click to access Cost Estimate<br />COST ESTIMATE OVERVIEW<br />
  65. 65. Maintenance Items<br /> Standard Roadway<br />Mowing<br />Storm Sewer Cleaning<br />Pavement Maintenance<br />Green Roadway<br />Pavement Maintenance<br />Tree Trimming<br />Plant Replacement<br />Landscape Upkeep<br />Solar Irrigation Maintenance<br />Culvert Cleaning<br />Click to access Cost Estimate<br />Savings Per Roadway Mile (2009$)<br />MAINTENANCE COST ESTIMATE<br />
  66. 66. Our Objective:<br />To develop a new sustainable standard road section for existing county ROWs that can serve as a model for future roadways.<br />Our Solution is:<br />More cost effective ≈ 13% reduction<br />More environmentally friendly ≈ 84% reduction in TSS<br />More efficient water management ≈ 70% reduction in CFS<br />More aesthetically attractive and functional<br />More innovative – using available technology that works today and offers more possibilities for the future<br />A NEW GREEN ROADWAY STANDARD <br />