Designing LID Treatment Systems
Upcoming SlideShare
Loading in...5
×
 

Like this? Share it with your network

Share

Designing LID Treatment Systems

on

  • 1,149 views

Siting and design effective Low Impact Development stormwater treatment systems, cost, maintenance & aesthetic considerations,

Siting and design effective Low Impact Development stormwater treatment systems, cost, maintenance & aesthetic considerations,

Statistics

Views

Total Views
1,149
Views on SlideShare
1,147
Embed Views
2

Actions

Likes
1
Downloads
24
Comments
0

1 Embed 2

http://www.linkedin.com 2

Accessibility

Categories

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

Designing LID Treatment Systems Presentation Transcript

  • 1. Low Impact Development SystemsSiting, Design and Installation for Maximum Environmental Benefit. What are the aesthetic, maintenance, & financial considerations? AIA, Committee on the Environment Sustainable Sites Program New Haven, Connecticut
  • 2. Presenter Background Nationally recognized expert in Low Impact Development (Regulations and Applications) Licensed Professional Engineer (CT) Holds IECA certifications as CPESC & CPSWQ Over 27 years in the Land Development Field and 11 years working with Low Impact Development12/16/2010 Copyright Trinkaus Engineering
  • 3. Stormwater Management Old Way to New WayUniversity of Arkansas Community Design Center 12/16/2010 Copyright Trinkaus Engineering
  • 4. Types of LID Treatment System (Dry) Bioretention Dry Swales Infiltration Basins & Trenches Sand Filters Permeable Pavement & Porous Concrete Filter Strips12/16/2010 Copyright Trinkaus Engineering
  • 5. Types of LID Treatment System (Wet) Wet Swales Constructed Wetlands & Ponds Subsurface Gravel Wetlands Organic Filters12/16/2010 Copyright Trinkaus Engineering
  • 6. How they work All “Dry” LID systems function by infiltrating runoff into the underlying native soils where physical, chemical and biological processes treat and reduce pollutant loads12/16/2010 Copyright Trinkaus Engineering
  • 7. How they work All “Wet” LID systems function by creating an anaerobic environment when bacteria can reduce pollutant loads. Additional pollutant removal occurs by physical settlement and vegetative uptake12/16/2010 Copyright Trinkaus Engineering
  • 8. Siting of LID Systems on the Landscape Site Considerations: Soil Class & Infiltrative Capacity Depth to Groundwater Slope of Land Hydrologic Conditions12/16/2010 Copyright Trinkaus Engineering
  • 9. Soil Classes Four Main Soil Classifications (NRCS) “A” – Excessively well drained (Sands & Gravels “B” – Well drained (Sandy Loams) “C” – Moderately well drained (Fine Sandy Loams to Silt Loams) “D” – Poorly drained (soils with high silt, clay content [wetland soils]12/16/2010 Copyright Trinkaus Engineering
  • 10. Soil Textural Classes12/16/2010 Copyright Trinkaus Engineering
  • 11. Soils: Get your hands Dirty!!! Test Pit: Best way to see the Mason Jar Test: Simple test dirt. OK, you don’t need 14 to determine type & amount of people to log a test pit soil particles12/16/2010 Copyright Trinkaus Engineering
  • 12. “A” Soils12/16/2010 Copyright Trinkaus Engineering
  • 13. “B” and “C” Soils12/16/2010 Copyright Trinkaus Engineering
  • 14. “D” Soils12/16/2010 Copyright Trinkaus Engineering
  • 15. Average Infiltrative Capacity “A” Soils: 10 – 200 feet/day “B” Soils: 3- 12 feet/day “C” Soils: 1 – 3 feet/day “D” Soils: NONE12/16/2010 Copyright Trinkaus Engineering
  • 16. Average Depth to Groundwater “A” Soils: > 10 feet on average, but can be less depending upon position on landscape “B” Soils: 6 – 3 feet “C” Soils: 1 – 2 feet “D” Soils: On Surface12/16/2010 Copyright Trinkaus Engineering
  • 17. Land Slope12/16/2010 Copyright Trinkaus Engineering
  • 18. LID Slope Issues Ideal slope for Bioretention systems is 2 – 10% Ideal slope for Vegetated Filter Strips < 6% Ideal slope for Infiltration Basin < 6%12/16/2010 Copyright Trinkaus Engineering
  • 19. Primary LID System: BIORETENTION12/16/2010 Copyright Trinkaus Engineering
  • 20. BIORETENTION SYSTEMS Functionality: Settling of coarse & fine sediments on surface Removal of pollutants by physical, chemical and biological processes Infiltration of runoff into underlying soils12/16/2010 Copyright Trinkaus Engineering
  • 21. BIORETENTION SYSTEMS Design Requirements: Maintain specified separation to seasonally high groundwater level Surface storage must contain required Water Quality Volume (fixed volume) Depth of Ponding (vary per natural soil type) Specific Soil Media (Enhance pollutant removal) Appropriate Plants Ponded water shall drain in 24 hours, no more than 48 hours12/16/2010 Copyright Trinkaus Engineering
  • 22. BIORETENTION1. Facility handles 1,900 sq.ft. of residential roof2. Has not overtopped in 3 years3. Located in “B” soils Newtown, CT – Trinkaus Engineering 12/16/2010 Copyright Trinkaus Engineering
  • 23. BIORETENTION1. Facility handles 2,800 sq.ft. of road runoff2. Facility is 4’ x 9’ x 10” deep3. Never overtopped in 2 years4. Located in “B” soils5. Soil media is 50 % sand & 50% leaf compost6. Ponded surface drains down in less than 4 hours after rainfall Southbury, CT – Trinkaus Engineering 12/16/2010 Copyright Trinkaus Engineering
  • 24. BIORETENTION Field Investigation: Deep Test Pit at least 6’ deep Type & Description of each soil layer Sample Soil Description: 0 – 4” Topsoil (Organic layer) 4 – 33” Orange brown fine sandy loam 33 – 48” Orange brown fine sand to silt loam 48 – 84” Brown grey lightly compact sand & gravel, No ledge, no mottling, no water, roots to 48”12/16/2010 Copyright Trinkaus Engineering
  • 25. BIORETENTION Field Investigation: Percolation Test: Depth of test shall be approximately equal to anticipated depth of soil media for Bioretention Shall be above season high groundwater level Provides reasonable estimate of soil infiltrative capacity12/16/2010 Copyright Trinkaus Engineering
  • 26. Location, Location, Location1. Bioretention are infiltration systems – do the soils next to a wetland infiltrate?2. Bottom of system is 6” above observed seasonal high groundwater level3. Bottom of system is 2’ below ex. grade in wetlands4. Treating parking lot runoff – require 3’ vertical separation to groundwater 12/16/2010 Copyright Trinkaus Engineering
  • 27. This looks easy, what can go wrong???1. Ponding more than 3 days AFTER a rainfall event2. Very few plants3. Site was not fully stabilized prior to installation of facility Trinkaus Engineering 12/16/2010 Copyright Trinkaus Engineering
  • 28. This looks easy, what can go wrong???1. Use outdated detail for construction,2. Inappropriate soil media (too much topsoil)3. Use of filter fabric (causes clogging, reduced or no infiltration 12/16/2010 Copyright Trinkaus Engineering
  • 29. This looks easy, what can go wrong???1. Overflow grate set flush to soil surface – NO STORAGE VOLUME2. Questionable soil media, visual inspection shows large silt component3. One tree (outside of low point of facility Trinkaus Engineering12/16/2010 Copyright Trinkaus Engineering
  • 30. This looks easy, what can go wrong???1. Overflow grate set flush to soil surface, NO STORAGE VOLUME2. Notch on left side has no function, parking pitches away from facility3. 24” of soil media on top of Structural fill with no underdrains (Where would the water go if it could infiltrate?) Trinkaus Engineering 12/16/2010 Copyright Trinkaus Engineering
  • 31. This looks easy, what can go wrong??? 1. Runoff can only enter near low1. At low point is flush catch basin end of sloping facility grate directly connected to hydrodynamic separator 2. Runoff must make 90 degree turn into facility2. No available storage for runoff 3. Minimal storage around overflow3. Balance of island is raised, not grate depressed CT NEMO CT NEMO12/16/2010 Copyright Trinkaus Engineering
  • 32. This looks easy, what can go wrong???1. How does runoff enter this facility? (Forgot to cut notches thru curb CT NEMO12/16/2010 Copyright Trinkaus Engineering
  • 33. Bioretention Installation Excavate to required subgrade Scarify with hand rake; bottom and sides of facility to remove soil smearing Place 1-1/4” crushed stone (storage layer) w/underdrain & overflow pipe Place pea gravel filter layer Mix and place soil media layer Install plants12/16/2010 Copyright Trinkaus Engineering
  • 34. Scarification of Native Soils Harwinton Sports Complex – Trinkaus Engineering12/16/2010 Copyright Trinkaus Engineering
  • 35. Scarification and Placement of Reservoir LayerHarwinton Sports Complex – Trinkaus Engineering12/16/2010 Copyright Trinkaus Engineering
  • 36. Installation of underdrain/overflow pipe & Pea Gravel Harwinton Sports Complex – Trinkaus Engineering12/16/2010 Copyright Trinkaus Engineering
  • 37. Bioretention Construction Protect area from construction traffic and stockpiling during site work Fully stabilize surface around bioretention area, such as pavement Do not install when soils are wet (will adversely affect infiltration capacity)12/16/2010 Copyright Trinkaus Engineering
  • 38. Erosion/Sediment Issue Unstabilized site surrounding Bioretention Area Silt layer from gravel parking base material - clogged Bioretention soil surfaceNorth Carolina State University – Bioengineering Group12/16/2010 Copyright Trinkaus Engineering
  • 39. Result from prior slideNorth Carolina State University – Bioengineering Group 12/16/2010 Copyright Trinkaus Engineering
  • 40. Bioretention Maintenance Mulch around plant stems only Stabilize inlet of runoff with stones to encourage overland flow Weed basin annually for first two years Prune vegetation as needed Remove accumulated sediment at inlet by hand12/16/2010 Copyright Trinkaus Engineering
  • 41. Swales Bioswales (Dry) Swales: Linear applications Max. slope = 4.0% 3’ vertical separation from top of soil to shallow groundwater Bioretention soil media – 30” in depth12/16/2010 Copyright Trinkaus Engineering
  • 42. Swales Wet Swales: Max. slope = 4.0% Bottom of swale must intercept shallow groundwater level (necessary to create & maintain hydrologic condition) Plant with wetland species12/16/2010 Copyright Trinkaus Engineering
  • 43. Dry & Wet Swales Dry Swale Wet Swale CT NEMO Dr. Bill Hunt, PE (NCSU)12/16/2010 Copyright Trinkaus Engineering
  • 44. Dry Swales High Point – Seattle, WA SEA Street Retrofit – Seattle, WA12/16/2010 Copyright Trinkaus Engineering
  • 45. Dry Swale Construction Protect area from construction traffic and stockpiling during site work, do not want to compact underlying soils Fully stabilize contributing drainage area above swale. Prevent silt from entering the system Do not install when soils are wet (will adversely affect infiltration capacity) Vegetation must be fully established before receiving runoff12/16/2010 Copyright Trinkaus Engineering
  • 46. Dry Swale Maintenance Maintain grass at 4” height Weed swale annually for first two years Prune vegetation as needed Stabilize inlet of runoff with stones to encourage overland flow Remove accumulated sediment at inlet by hand12/16/2010 Copyright Trinkaus Engineering
  • 47. Wet Swale Construction Protect area from construction traffic and stockpiling during site work Fully stabilize contributing drainage area above swale. Prevent silt from entering the system If soils are a little wet, it is OK – we want a silty, wet environment Vegetation must be fully established before receiving runoff12/16/2010 Copyright Trinkaus Engineering
  • 48. Wet Swale Maintenance DO NOT MOW OR CUT VEGETATION Remove any invasive species Do not prune vegetation, denser is better Stabilize inlet of runoff with stones to encourage overland flow Accumulated sediment can actually help12/16/2010 Copyright Trinkaus Engineering
  • 49. Vegetated Filter Strips Maximum slope = 6% Stone trench or raised concrete lip – very Generally – important berms are not to achieve needed or overland desired as flow concentration flow can develop12/16/2010 Copyright Trinkaus Engineering
  • 50. Vegetated Filter Strips Ledgebrook Lane – Trinkaus Engineering12/16/2010 Copyright Trinkaus Engineering
  • 51. Filter Strip Construction Prevent compaction of soils If soils get compacted, perform deep tillage (12-18”) to restore infiltrative capacity. Protect area with erosion control measures above filter strip to prevent erosion12/16/2010 Copyright Trinkaus Engineering
  • 52. Filter Strip Construction Grade uniform cross slope to ensure overland flow will occur Hydroseed filter strip area ONLY allow runoff onto filter strip after fully vegetated A hardened edge must be installed above the filter strip to achieve overland flow12/16/2010 Copyright Trinkaus Engineering
  • 53. Filter Strip Maintenance Inspect annually and remove accumulated sediment from upper edge of filter strip Maintain vegetation at an appropriate height12/16/2010 Copyright Trinkaus Engineering
  • 54. Why a Slope Limitation and Minimum Width Requirement? Filter strips on unreinforced slopes > 6% are susceptible to small rivlets of concentrated flow, leading to erosion Flow widths < 25’ will not adequately disperse concentrated flow to overland flow12/16/2010 Copyright Trinkaus Engineering
  • 55. Infiltration Basin Off-line design: Treat and fully infiltrate Water Quality Volume By-pass larger flows12/16/2010 Copyright Trinkaus Engineering
  • 56. Infiltration Basin-3’ separation from bottom ofsystem to SHGW- Native soils must have < 20%& 20-40% silt/clay- Native soils must have in-situ infiltration rate of 0.5”/hr- 25% of WQv to be providedby pretreatment- Must be installed “off-line)- Install on slopes < 6%- Basin to fully infiltrate WQvthrough bottom of basin only 12/16/2010 Copyright Trinkaus Engineering
  • 57. Infiltration Basins Design Infiltration Rates for Soil TexturesUSDA Soil Texture Design Infiltration Rate (fc) Sand 8.27 “/hr Loamy Sand 2.41 “/hr Sandy Loam 1.02 “/hr Loam 0.52 “/hr Silt Loam 0.27 “/hr12/16/2010 Copyright Trinkaus Engineering
  • 58. Infiltration Basin Mulvaney Subdivision – Ridgefield, CT 1. Very sandy soils – has never discharged via overflow pipe 2. System is not off- line, yet fully infiltrates all runoff 3. Designed & Constructed in 2000 prior to State Design specifications Mulvaney Subdivision – Trinkaus Engineering12/16/2010 Copyright Trinkaus Engineering
  • 59. Infiltration Basin Construction Prevent ALL vehicular movement over area of infiltration basin Construct pre-treatment facility (forebay) and basin (off-line facility) Vegetated as soon as grading is done No runoff allowed until dense vegetated cover has been established12/16/2010 Copyright Trinkaus Engineering
  • 60. Infiltration Basin Maintenance Inspect forebay and remove accumulated sediment on annual basis Remove leaves from bottom of basin annually Mow grass on regular basis to maintain 4” height (+/-)12/16/2010 Copyright Trinkaus Engineering
  • 61. Permeable Pavement Design & Maintenance Maintain required vertical separation to shallow groundwater Do not overly compact native soils, reservoir course and filter course of pavement system No application of sand Minimal applications of salt (75% less than normal)12/16/2010 Copyright Trinkaus Engineering
  • 62. Permeable Pavement/Porous Concrete12/16/2010 Copyright Trinkaus Engineering
  • 63. Porous Concrete Design & Maintenance Maintain required vertical separation to shallow groundwater DO NOT USE SALT ON SURFACE UNTIL IT HAS CURED 12 MONTHS Can use sand in first winter, but must use vacuum sweeper to remove fines from surface12/16/2010 Copyright Trinkaus Engineering
  • 64. Construction Costs Bioretention: $14,000 per acre treated Permeable Pavement: $ 6-8/sq.ft., does not include site prep. Porous Concrete: $ 8-11/sq.ft., does not include site prep Surface materials are approximately +20% than standard surface materials12/16/2010 Copyright Trinkaus Engineering
  • 65. Construction Costs Subsurface Gravel Wetlands: $26,000 per acre treated Permanent Wet Pond: $15,000 per acre treated Wet Swale: $3,500 per acre treated Dry Swale: $5,500 per acre treated12/16/2010 Copyright Trinkaus Engineering
  • 66. Placement on the LandscapeImpervious area disconnection –driveway runoff as overland flowacross 75’ of vegetated surface Site Fingerprinting – defined clearing area as percentage of lot area 24 Lots – 64+ acres of Meadow filter strip with Bioretention systems for preserved Open Space Micro-berm at edge of roof drains development envelope 12/16/2010 Copyright Trinkaus Engineering
  • 67. Placement on the LandscapeConstructed Wetland Systemw/forebay & vegetated outletswale to wetland Linear vegetated level spreader Subsurface flow gravel wetland w/forebay & vegetated outlet swale to 24 Lots – 64+ acres of wetland preserved Open SpaceInfiltration trenches for drivewayrunoff 12/16/2010 Copyright Trinkaus Engineering
  • 68. Individual LotsMeadow filterstrip Bioretention for roof runoffImpervious areadisconnection 12/16/2010 Copyright Trinkaus Engineering
  • 69. Individual Lots Bioretention for roof drains Meadow Filter Strip12/16/2010 Copyright Trinkaus Engineering
  • 70. Holland Joint Venture - Commercial Conventional Stormwater Plan: Catch Basins & Pipe Two Dry Detention Basins Estimated Cost of Conventional: $ 200,000.0012/16/2010 Copyright Trinkaus Engineering
  • 71. Holland Joint Venture - Commercial Bioretention in parking island & along perimeter of facility – sheet flow from building out to facilities12/16/2010 Copyright Trinkaus Engineering
  • 72. Holland Joint Venture - Commercial LID Stormwater Plan: Grade parking lot to use sheet flow, direct runoff to treatment systems Construct four Bioretention systems to handle WQV for roof & parking area Construct Biorention system to handle WQV from access roadway Estimated Cost of LID: $ 110,000.0012/16/2010 Copyright Trinkaus Engineering
  • 73. Harwinton Sports Center - Commercial Conventional Stormwater Plan: Catch Basins & Pipe 600 lf – 24” Perforated HDPE in crushed stone in select fill Cost of Conventional System: $ 90,000.0012/16/2010 Copyright Trinkaus Engineering
  • 74. Harwinton Sports Center - Commercial Bioretention System with Dry Conveyance Swale12/16/2010 Copyright Trinkaus Engineering
  • 75. Harwinton Sports Center LID Stormwater Plan Grade parking lot to two low points, eliminate all structural drainage Construct two Dry Swales to convey runoff Construct two Bioretention systems to handle WQV for roof & parking area Cost Saving over Conventional Plan: $ 40,000.0012/16/2010 Copyright Trinkaus Engineering
  • 76. Subsurface Gravel Wetlands Subsurface Gravel Wetlands: siting OK, not designed per UNHSC specifications – WQV not provided per specs.12/16/2010 Copyright Trinkaus Engineering
  • 77. Pseudo-LID at “End of the Pipe” Proposed ponding depth = 3’ will kill plants in system due to excessive inundation Bioretention in close proximity to wetland boundary – no sizing calculations12/16/2010 Copyright Trinkaus Engineering
  • 78. QUESTIONS??12/16/2010 Copyright Trinkaus Engineering
  • 79. Contact InformationSteve Trinkaus, PE, CPESC, CPSWQTrinkaus Engineering, LLC114 Hunters Ridge RoadSouthbury, CT 06488203-264-4558, Fax: 203-264-4559Email: strinkaus@earthlink.netWebsite: http://www.trinkausengineering.com12/16/2010 Copyright Trinkaus Engineering