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SUBURBAN RES Team 19185 Competition Submittal


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Electronic submittal from the team of LandPlan Engineering and DAF Studio

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SUBURBAN RES Team 19185 Competition Submittal

  1. 1. Team Identification Number 19185 Ranchbridge Community
  2. 2. Overview <ul><li>LID Definition and Discussion </li></ul><ul><li>Design Considerations </li></ul><ul><li>Storm Water Detention & Storm Water Quality </li></ul><ul><li>Economic Evaluation </li></ul>Successful Green is Affordable. Marketable. Livable. For a summary of our concept and approach to LID reference Ranchbridge Concept.
  3. 3. Traditional Development <ul><li>Impacts: </li></ul><ul><ul><li>Increases impervious surfaces within watershed </li></ul></ul><ul><ul><li>Permanently alters hydrology </li></ul></ul><ul><ul><li>More frequent flooding </li></ul></ul><ul><ul><li>Higher peak flows </li></ul></ul><ul><ul><li>Watershed experiences increase in pollutant concentrations </li></ul></ul><ul><ul><li>Increased water temperatures </li></ul></ul><ul><ul><li>Loss of wildlife habitat and open space </li></ul></ul><ul><ul><li>Loss of groundwater recharge </li></ul></ul>
  4. 4. Low Impact Development decreases impact to ecology by trying to mimic or maintain pre-development hydrology. <ul><li>Tools: </li></ul><ul><ul><li>Store </li></ul></ul><ul><ul><li>Inflitrate, </li></ul></ul><ul><ul><li>Reuse, and </li></ul></ul><ul><ul><li>Detain runoff </li></ul></ul>
  5. 5. LID Examples <ul><li>Bioretention Swales </li></ul><ul><li>Rain Gardens </li></ul><ul><li>Xeriscaping </li></ul><ul><li>Lot orientation consideration for optimal solar/light exposure </li></ul><ul><li>Wheel path driveways </li></ul><ul><li>Utilizing recycled materials where possible (i.e. recycled crushed concrete) </li></ul><ul><li>Utilizing local materials </li></ul><ul><li>Pervious pavement </li></ul><ul><li>Stormwater reuse pond </li></ul><ul><li>Walkability via trails and road layouts that promote connectivity – Safe Routes to School </li></ul><ul><li>Curb-less streets </li></ul>
  6. 6. Existing Site Characteristics <ul><li>Relatively flat with elevations ranging from 146’-139’ </li></ul><ul><li>Relatively high average annual precipitation at 50.83” </li></ul><ul><li>Type D Soils with very low rate of water transmission (0-0.05 in/hr) </li></ul>
  7. 7. Traditional Design Schematic
  8. 8. LID Schematic Ranchbridge Community
  9. 9. Bioretention Swale Diagram from Preliminary Low Impact Development Manual for Sarasota County Diagram from Preliminary Low Impact Development Manual for Sarasota County <ul><li>Function: </li></ul><ul><li>Provides storm water quality treatment </li></ul><ul><li>Increases surface roughness, “n,” to retard velocity, helping to more closely mimic pre-development hydrology </li></ul><ul><li>Reduces post-development runoff volume </li></ul><ul><li>Consists of the following elements: </li></ul><ul><ul><li>Prefilter Strip </li></ul></ul><ul><ul><li>Ponding Area </li></ul></ul><ul><ul><li>Organic Mulch Layer </li></ul></ul><ul><ul><li>Planting Soil Filter Bed </li></ul></ul><ul><ul><li>Sand Bed </li></ul></ul><ul><ul><li>Underdrain (Pipe and Gravel Media) </li></ul></ul><ul><ul><li>Overflow Pipe or Spillway </li></ul></ul>
  10. 10. Ground Cover Considerations <ul><ul><li>Wheel path driveways </li></ul></ul><ul><ul><li>– Reduces Impervious Area </li></ul></ul><ul><ul><li>Xeriscaping </li></ul></ul><ul><ul><li>– Reduces irrigation demands </li></ul></ul><ul><ul><li>Pervious Concrete Pavement </li></ul></ul><ul><ul><li>– Utilized for alleyways in 50’x115’ pods to reduces Impervious Area </li></ul></ul>
  11. 11. Stormwater Reuse Pond <ul><li>Can be used to supplement or replace reliance on more costly potable water </li></ul><ul><li>Relatively low maintenance requirements </li></ul><ul><li>Increases pollutant removal via large fraction of annual stormwater runoff being applied back to the watershed </li></ul><ul><li>Reduces the amount of runoff delivered downstream of watershed </li></ul>Stormwater runoff is captured and stored in a pond, and then pumped back out to irrigate pervious areas in the contributing watershed. This LID practice is ideal for the Houston area due to the relatively high average annual precipitation.
  12. 12. Walkability <ul><li>Trail system combines recreation, safe routes to schools, and view amenities at low cost utilizing recycled materials. Reduces vehicle trips per day on neighborhood streets, as well as school pick-up queuing/idling. Home owner education planned through signs along path highlighting neighborhood Low Impact Design concepts incorporated. </li></ul>
  13. 13. Percent Reduction of Storm Water Runoff Volume
  14. 14. Hydrologic Modeling <ul><li>HEC-HMS was utilized for stormwater modeling. While other software applications were considered for their ability to quantify stormwater quality treatment, it was decided that since this project is within Harris County, Hec-HMS is ideal. Why: </li></ul><ul><li>Hec-HMS Widely used and accepted </li></ul><ul><li>Offers flexibility in design </li></ul><ul><li>Use simplifies and expedites review by HCFCD </li></ul><ul><li>Stormwater quality treatment features were unnecessary -- alternative methods were used for calculations </li></ul><ul><li>Design Criteria: </li></ul><ul><li>Existing and proposed conditions were modeled using the SCS Unit Hydrograph method. Harris County, IDF curves were utilized for 24-hour, 5, 10 and 100 year storm events. </li></ul>
  15. 15. Storm Water Quality <ul><li>Studies have shown that the first 1” of storm water runoff, the “first flush,” is regularly more toxic than raw sewage. It was decided to treat storm water quality at the source. Design layout provides bioswales to intercept initial stormwater water runoff. Drainage areas to be limited to 5 acres or less per biofiltration system area, preferably less than 2 acres for optimal performance. Biofiltration areas sized to treat the first 1” of runoff. When designed, constructed, and maintained properly, biofiltration systems have been shown to achieve excellent removal or pollutants including: </li></ul><ul><li>86% for Total Suspended Solids (TSS) </li></ul><ul><li>97% for Chemical Oxygen Demand </li></ul><ul><li>67% for Oil and Grease </li></ul><ul><li>90% for Metals </li></ul><ul><li>60% for Nitrogen </li></ul><ul><li>80% for Phosphorus </li></ul><ul><li>Reference: Low Impact Development Manual for Sarasota County </li></ul>
  16. 16. Bacteria Removal Efficiencies <ul><li>Ranchbridge design allows for potential bacteria reduction in two areas: stormwater and sanitary effluent . </li></ul><ul><li>Stormwater: Current studies indicate that biofiltration areas “show promise in removing bacteria at the site level.” Reference: Stormwater Magazine, May 2008 ( </li></ul><ul><li>Wastewater: Utilizing Membrane Biological Reactor Treatment Process provides higher quality effluent, effectively reducing bacteria. </li></ul>
  17. 17. LID Typically Overlooked <ul><li>Perceived increased cost in both capital and maintenance </li></ul><ul><li>Many LID storm water management concepts are technically categorized as non-compliant with many regulatory agencies </li></ul><ul><li>First impressions are often of “weeds” by the houses </li></ul>
  18. 18. LID Cost to Benefit Breakdown <ul><li>Decrease in impervious surface area decreases detention costs </li></ul><ul><li>Decreasing piping and curb & gutter </li></ul><ul><li>Decreasing size of storm water controls </li></ul><ul><li>Reduced traffic with links to where people want to go for a truly walkable neighborhood lower roadway requirments </li></ul><ul><li>Reduced water capacity associated with lower demand for potable irrigation water </li></ul><ul><li>Emphasis on local recycled materials lowers construction costs </li></ul><ul><li>Dual use of parcels for detention and recreation </li></ul>
  19. 19. Cost Comparison Between Traditional Development vs. LID For Same Property <ul><li>Even with LID Elements such as brookside trails, reuse irrigation systems, gardens, and advanced waste water treatment included, construction costs are 3.4 % lower </li></ul><ul><li>Traditional Construction Costs: $13,326.29 per lot </li></ul><ul><li>LID Construction Costs: $12,873.64 per lot. </li></ul><ul><li>Basic development construction costs are nearly 10 % lower </li></ul>
  20. 20. Costs versus Prices: LID in the Marketplace <ul><li>Experience in other areas suggests utilizing multiple builders taking slightly different approaches in distinct areas accentuates market acceptance. Stapleton in Denver being a successful example which distinct LID practices in differing neighborhoods within the community but highly varied housing styles in each. </li></ul><ul><li>Ranchbridge’s layout accommodates various approaches such that the developer may allow deviation in many LID elements to be applied to homes while maintaining requirements for the basic LID and neighborhood elements, such as rain gardens and courtyards, without significant price resistance. </li></ul>
  21. 21. LID Cost Breakdown and Total <ul><li>Ranchbridge has been designed, planned, and costed as a complete community including internal streets and sidewalks and suggested amenities: </li></ul><ul><li>Basic Construction costs $27,261,734 </li></ul><ul><li>Per Lot $ 22,549 </li></ul><ul><li>With Amenties $28,245,160 </li></ul><ul><li>Per Lot $23,362 </li></ul>For a complete preliminary listing of probably costs and items, including major amenities see Construction Costs.
  22. 22. LID Beyond Civil Design… <ul><li>Below are examples of several ways architects, builders and home owners can contribute to Low Impact Development: </li></ul><ul><li>Rain barrels (or Rainwater H2OG or similar systems) </li></ul><ul><li>Efficient home irrigation systems and water heaters </li></ul><ul><li>Xeriscape yards </li></ul><ul><li>Ranchbridge is designed for grasscrete or pervious pavers for front walks </li></ul><ul><li>Photovoltaic roofs are encouraged and the neighborhoods are to be designed to accommodate connections (Stapleton development in Denver now incorporates some neighborhoods focused on solar, new photovoltaic shingles are amongst Time Magazines leading innovation for this year </li></ul><ul><li>Reliance on latest enegy efficient applicances </li></ul><ul><li>Use of recycled materials </li></ul><ul><li>Appropriately insulated walls and roofs </li></ul>
  23. 23. References <ul><li>Preliminary Low Impact Development Manual for Sarasota County, December 2008. Prepared by Jones Edmunds & Associates, Inc., University of Florida Program for Resource Efficient Communities (PREC), and STE </li></ul><ul><li>  </li></ul><ul><li>Low-Impact Development Design Strategies, An Integrated Design Approach , June 1999. Prepared by Prince George’s County, Maryland Department of Environmental Resources, Programs and Planning Division. </li></ul><ul><li>  </li></ul><ul><li>Stormwater, The Journal for Surface Water Quality Professionals , Various 2009 Issues </li></ul><ul><li>  </li></ul><ul><li>Criteria and Procedure Manual, Harris County Flood Control District , October 2004 </li></ul><ul><li>  </li></ul><ul><li>Regulations of Harris County, Texas for the Approval and Acceptance of Infrastructure, Harris County, September 1, 2009 </li></ul><ul><li>  </li></ul><ul><li>Infrastructure Design Manual, City of Houston Department of Public Works and Engineering , October 2008 </li></ul><ul><li>  </li></ul><ul><li>Leander Smart Code, Leander Texas , September 22, 2005 </li></ul><ul><li>  </li></ul>
  24. 24. Questions?