A Builder's Introduction to LID: How to Make LID Pencil Out for Your Project


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Introduces builders and developers to Low Impact Development and the most effective design and treatment methods in the Northwest.

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  • A lot of attention on LID BUT…LID in infancy for developers and builders b/c in many cases it doesn’t pencil out incentives aren’t fully developed local gov’ts still learning about LID many LID practices still being tested, and outside comfort zone for builders.
  • For the past 2 decades, the rate of land development across the country has been 2X the rate of population growth (EPA)
  • Because of this growth, stormwater management has become the focus of attention
  • EXAMPLE: Instead of a treatment pond, the subdivision could have a rain garden in each yard, disconnect downspouts from driveway surfaces, remove curbs, and install grassed swales in common areas.
  • CSO = combined sewer overflow storage & conveyance systems Groundwater recharge = instream flows Less expensive to keep water clean than to clean up (treat)
  • Pilot project by Sea Pub Utils to redesign entire 660 ft block Apparently Fire Dep’t did not approve
  • Meadow on the Hylebos Poor/low infiltrating soils—Pierce Co considered good site to test LID Intensive monitoring; report due fall ’08 Dreamcraft Homes
  • Key lessons: GMA is forcing us to develop more marginal sites to accommodate density. But LID becomes more difficult and costly with steep slopes, rolling topography, poor soils, and high water table (which accounts for crawl space flooding). Developer must be on board and part of plat agreement. Developer must set foundation elevations and design utilities for 6” compost tilled and 12” scarified. Amended soil cannot be afterthought. Buyers had expectations and couldn’t necessarily see economic return.
  • PSAT created in 1996 to coord & implement env agenda (PS Conservation & Recovery Plan); recent focus on LID; regulation assistance project started in 2005 PSAT no funded/absorbed by PSP; PSP created by Gregoire in 2006 to address health of Puget Sound; 13-yr $12 billion plan issued 12/06; action agenda due September
  • Muni permits – 104 cities/17 counties must adopt erosion control ordinances & regulate construction (certain BMPs are required based on impervious surface)
  • King County Dedicated “Green Track” for LID projects Free LID consulting services
  • Leadership in Energy and Environmental Design – national green building standards (1998—developed by US Green Building Council)
  • Pierce Co= “yellow light” for cluster development; “red light” for decreased road widths
  • Cell = shallow depression with amended soils & special plants; may or may not have underdrain; not designed as conveyance system Swale = same but are designed as part of a conveyance system (w/gentle side slopes and flow depths less than 12 inches)
  • Sand mixture general rule: 60-65% loamy sand mixed with 35-40% compost OR 30% sandy loam/30% coarse sand/40% compost
  • Meadow on Hylebos – gardens were finished before construction. Major fine sediment problems. Bioretention areas were still functioning even with extreme fine sediment inputs). Builder & developer have to determine financing, contracting, bonding, and liability. Developer probably willing to come back & finish garden (removing top 6”, other repairs, and planting) if figured into initial land costs.
  • 3500 lot size (typical LID) w/1900 sq ft for amended soils = $700
  • 1 a) Use soil berm instead of silt fence & then spread berm as organic matter 1 b) Hylebos tried to stockpile but too big; became costly because equipment to spray compost didn’t work & had to wheelbarrow in material (primarily to back yard areas) 2. Flow control for dispersion & have to use amended soils for dispersion, thus indirect credits 3. Heavily amended soils can become saturated = poor plant quality
  • 2-day class by PSP/WSU will certify your company
  • Pierce Co = “yellow light” for porous pavement in private travel ways
  • F & S Grade Rd and Jones Dr just NW of Sedro-Woolley and there are several hundred feet of porous asphalt. Was done by Lakeside Paving and it is several months old and holding up just fine.
  • Bunyan power screed place pervious concrete smoothly Most expense in fully cleaning out equipment between regular & pervious concrete—prices will drop when more applicators or new equip available Perco-Crete is a sandy mix verses a 3/8" or Gran stone mix you have seen earlier. All pervious concrete needs to be consolidated. However, Perco-Crete, being made of 'fluffy, slightly moist' sand, must be packed 1/8" for each inch of thickness place.
  • Craig Morrison, CMI Homebuilders Started Pervious Concrete Inc in 2002 w/Sultan plat Ran into stormwater issues & suggested to do entirely pervious in order to avoid piping, catch basins & detention
  • EcoStone is high density w/aggregate in openings New specs do not require compaction…but no flow credits yet
  • Grass & GravelPave – 100% recycled
  • Vacuuming may not be as necessary—use rented leaf vac if needed
  • Acceptable methods to restore levels of flowability are to vacuum, flush the pervious concrete sections with high volume-low pressure wash or to spray enzymes that digest organic materials on to the pervious concrete sections during wet seasons of the year without excessively low temperature. My counsel has always been to treat it just like any other pavement.  Remove leaves and debris from the surface when it accumulates, and DO NOT let people dump topsoil, bark dust, etc. on it. Andrew E. Marks, PE Managing Director Puget Sound Concrete Specification Council "The Concrete Council" [email_address]
  • Pierce Co = “yellow light”
  • Pierce Co = yellow light
  • Discharge has to match pre-developed forested discharge from 50% of 2-yr peak flow to 50-yr peak flow unless prairie or 40% impervious since 1985 (subject to appeal)
  • Credits for amended soil?
  • Maintenance requirements for property owners should be conveyed with deed
  • A Builder's Introduction to LID: How to Make LID Pencil Out for Your Project

    1. 1. A Builder’s Introduction To Low Impact Development How to Make LID Pencil Out For Your Project
    2. 2. Common Builder Questions <ul><li>How do I know if my site is good for LID? </li></ul><ul><li>Will LID be too expensive to consider? </li></ul><ul><li>How many practices must I do to be considered a LID project? </li></ul><ul><li>Can I avoid some permits or reduce the size of my pond with LID? </li></ul><ul><li>Will the local government be on board? </li></ul><ul><li>Are there other ways to fund LID on my site? </li></ul>
    3. 3. What is Low Impact Development? <ul><li>Conserving vegetation & soils </li></ul><ul><li>Keeping natural flow paths </li></ul><ul><li>Increasing time on site </li></ul>LID mimics a site’s natural hydrology by: Source: AHBL Engineering <ul><li>Which means… </li></ul><ul><li>Less impervious surfaces </li></ul><ul><li>Disconnecting roofs, downspouts & parking areas </li></ul><ul><li>Disbursing small-scale controls vs. large detention pond </li></ul>
    4. 4. Hydrology 101 <ul><li>50% intercepted by leaves & evaporates </li></ul><ul><li>30% stored by 2 – 4ft of organic & biologically active soil </li></ul><ul><li>Of interflow, 10 – 40% goes to groundwater (that acts as natural water storage and maintains instream flows) </li></ul><ul><li>Overland flow < 1% </li></ul>Native forest and soils intercept, store, and slowly convey precipitation. Source: LID Technical Guidance Manual, Fig 1.1
    5. 5. Urbanization Changes Forest Function <ul><li>Traditional residential development removes almost all vegetation and topsoil. </li></ul><ul><li> evapo-transpiration </li></ul><ul><li> soil storage </li></ul><ul><li> in groundwater </li></ul><ul><li> rapid surface runoff </li></ul><ul><li> pollutants to water </li></ul><ul><li> channel instability </li></ul>Source: LID Technical Manual, Figure 1.3
    6. 6. And We’re Growing! <ul><li>The Puget Sound is expected to have 1.4 million more residents by 2025. (Source: OFM) </li></ul><ul><li>Between 1991 – 2001, impervious surface increased by 10.4% </li></ul>Source: Sightline Institute
    7. 7. Traditional Stormwater Management <ul><li>Collecting & conveying to centralized ponds is reliable, predictable & simple to maintain </li></ul><ul><li>BUT </li></ul><ul><li>90% storage loss v. 25% storage gain </li></ul><ul><li>Heavy rains = excess to receiving waters </li></ul><ul><li>Flow/duration standards in 2005 Manual require larger ponds =  costs and  buildable land </li></ul>
    8. 8. <ul><li>So…instead of focusing on structure , LID focuses on landscape . </li></ul><ul><li>Disburse & infiltrate rather than capture and store. </li></ul>
    9. 9. Benefits of LID <ul><li>Smaller ponds = more land and less cost </li></ul><ul><li>Marketable as green neighborhood </li></ul><ul><li>Reduce stormwater utility or SEPA fees </li></ul><ul><li>Avoid/speed permits or other regulations </li></ul><ul><li>For local governments: </li></ul><ul><ul><li>Prevents flooding </li></ul></ul><ul><ul><li>Maintains drinking water supplies & instream flows </li></ul></ul><ul><ul><li>Reduces maintenance costs </li></ul></ul><ul><ul><li>Less need for CSO storage & conveyance </li></ul></ul><ul><ul><li>Cost effective urban retrofit (especially with fewer streets, curbs & gutters) </li></ul></ul>
    10. 10. So if LID is so great, why aren’t we seeing it everywhere? <ul><li>Still being tested </li></ul><ul><li>LID practices + native vegetation/open space + additional storage = $$$ </li></ul><ul><li>Expensive products and applications </li></ul><ul><li>Difficult to find the right soil </li></ul><ul><li>Few incentives & difficult to get flow credits </li></ul><ul><li>Local governments slow to allow </li></ul><ul><li>Conflict within government offices (planning v. public works v. fire department, etc.) </li></ul>
    11. 11. SEA Streets, Seattle <ul><li>Reduced impervious surfaces to 11% less than traditional street; vegetated swales; added over 100 evergreen trees & 1100 shrubs </li></ul><ul><li>Cost: $850K </li></ul><ul><li>Completed spring 2001 </li></ul><ul><li>Prevented all dry season runoff and 99% of wet season runoff 2000-03; no runoff since 2003 </li></ul>Source: Seattle Public Utilities
    12. 12. High Point, West Seattle <ul><li>120 acres; Phase I 829 units finished 2006; Phase II 2009 </li></ul><ul><li>Mixed housing--all 3 star or more </li></ul><ul><li>½ Seattle Housing Authority; ½ private </li></ul><ul><li>Vegetated swales w/ 3ft amended soils, porous walks, one porous street, football field detention pond w/ trail, overlook & artificial stream </li></ul><ul><li>Intended to process water like forest meadow </li></ul><ul><li>Monitoring started 1/07; data in 3 years </li></ul>Source: Seattle Public Utilities
    13. 13. Fife Heights, Pierce County <ul><li>8.9 acres; 35-lot residential subdivision </li></ul><ul><li>48% + in open space; 150 ft. revegetated buffers </li></ul><ul><li>20 ft. roadways, including sidewalks </li></ul><ul><li>Roadside bioswales instead of curb & gutter </li></ul><ul><li>Amended soils (low infiltrating glacial till) </li></ul><ul><li>Low Impact Foundation Technology (LIFT) on selected sites </li></ul><ul><li>Homes finished in 2006/07 </li></ul>Source: AHBL Engineering & WSU, Pierce Co Extension Source: Pierce Co Public Works & Utilities
    14. 14. Sumner LID Pilot Project, Pierce County <ul><li>9 units on 2.7 acres </li></ul><ul><li>Completed in 2004 </li></ul><ul><li>Driveway pervious pavers; vegetated swales w/over-drains; amended soils; one sidewalk; curvilinear street design </li></ul><ul><li>Sumner monitoring—will implement LID ordinances if successful (open to LID now) </li></ul>Source: University of Puget Sound
    15. 15. Cooper Crest, Olympia <ul><li>First to build under mandatory LID ordinance </li></ul><ul><li>140 units on 70 acres </li></ul><ul><li>1 developer; 2 builders </li></ul><ul><li>55% open space; 18-ft streets; amended yards; rain gardens; 20 ft areas to infiltrate roof run-off; some porous sidewalk </li></ul><ul><li>Complaints of poor soil, runoff, crawl space flooding, lawn erosion, and soil & rain gardens insufficient to handle stormwater </li></ul>
    16. 16. Whidbey Island Projects <ul><li>Pacific Crest Subdivision in Oak Harbor </li></ul><ul><ul><li>Bioswales and narrow roads </li></ul></ul><ul><ul><li>Poor homeowner maintenance </li></ul></ul><ul><li>The Highlands at Langley </li></ul><ul><ul><li>No stormwater to city drains </li></ul></ul><ul><ul><li>Native vegetation; pervious pathways, bioswales; rain gardens </li></ul></ul><ul><ul><li>Under construction </li></ul></ul>Photos courtesy of Stacy Smith, Whidbey Island Conservation Dist.
    17. 17. LID & Government <ul><li>EPA w/other clean water agencies signed letter of intent to formalize use of LID (April, 2007) </li></ul><ul><li>PSAT/PSP action agenda focuses on stormwater & LID </li></ul><ul><li>Ecology stormwater manual & permits </li></ul><ul><li>Local ordinances </li></ul><ul><ul><li>Seattle, Tacoma, King, Pierce, Snohomish & Clark – LID mandatory “where feasible” </li></ul></ul><ul><ul><li>Other jurisdictions must allow for LID and determine inconsistencies preventing LID </li></ul></ul>
    18. 18. State Stormwater Regulation Local ordinances must include “Provisions to allow non-structural preventive actions and source reduction approaches such as Low Impact Development Techniques (LID)…Provisions for LID should take into account site conditions, access and long term maintenance.” Department of Ecology Construction Stormwater Permit Municipal Stormwater Permits (Phase I & II) Stormwater Manual (Western & Eastern) Disturbing > acre or < acre if in subdivision Disturbing > acre or < acre if in subdivision “ Guidance” required by constr and muni permits WWHM or MGS Flood to estimate surface runoff and size facilities SWPPP must use BMPs from Manual SWPPP must use BMPs from Manual Phase I: LID mandatory Phase II: locals must allow Addendum to Vol. III provides flow control credits for LID practices
    19. 19. Local Ordinances <ul><li>Ordinances allow, encourage or require: </li></ul><ul><li>Pierce, King, Snohomish, Kitsap Counties </li></ul><ul><li>Bellingham, Bothell, Kirkland (clustering), Lacey, Langley, Marysville, Poulsbo, Port Angeles, Port Orchard, Redmond (manual), Sedro Woolley, Tumwater, Olympia, Seattle, SeaTac </li></ul><ul><li>PSAT/PSP grants (ordinance changes under review): </li></ul><ul><li>Issaquah, Poulsbo, Woodinville, Edmonds, Normandy Park, Anacortes, Bremerton, Coupeville, Eatonville, Everett, Federal Way, Hamilton, Lake Forest Park, Lake Stevens, Mill Creek, Mukilteo, Oak Harbor, Clallam, Jefferson, Kitsap, Thurston, Whatcom, Mason, San Juan </li></ul><ul><li>City of Seattle </li></ul><ul><li>2/15/08 submitted final draft of stormwater code to DOE </li></ul><ul><li>Requires “green infrastructure technologies” of all single-family residential to “maximum extent possible” </li></ul>
    20. 20. Built Green/LEED <ul><li>NAHB model green home building guidelines (2006) </li></ul><ul><li>LID practices earn points toward green building designations </li></ul><ul><li>Preserve vegetation/trees, amend soil, limit impervious/add pervious, use drought tolerant plants, install cistern, etc. </li></ul><ul><li>LEED </li></ul>
    21. 21. Types of LID Practices
    22. 22. Types of LID Practices <ul><li>Site planning & layout </li></ul><ul><li>Protecting vegetation/minimizing soil disturbance </li></ul><ul><li>Integrated Management Practices </li></ul><ul><ul><li>Rain gardens </li></ul></ul><ul><ul><li>Amending soils </li></ul></ul><ul><ul><li>Permeable paving </li></ul></ul><ul><ul><li>Green roofs </li></ul></ul><ul><ul><li>Minimal excavation foundations </li></ul></ul><ul><ul><li>Roof rainwater collection systems </li></ul></ul>
    23. 23. Site Planning & Layout <ul><li>Hydrology as part of initial site assessment and planning </li></ul><ul><li>Building sites, roads, and stormwater infrastructure designed around natural features and LID practices </li></ul>Source: WSU, Pierce County Extension (Kensington Estates)
    24. 24. Minimize connected pervious area <ul><li>Narrow streets/smaller turnarounds </li></ul><ul><li>Curvilinear design </li></ul><ul><li>Driveways (20%) – shared, porous, wheel strips, plastic grid </li></ul><ul><li>Sidewalks – 44-48”, one side, 2% slope to swale, porous </li></ul><ul><li>Fewer curbs & conveyances (that create flow) </li></ul>Source: Boston Metropolitan Area Planning Council (t); Puget Sound University (Sumner)
    25. 25. Questions <ul><li>Does the market want this type of lot design? </li></ul><ul><li>Will fire departments allow for narrow roads and limited access? </li></ul>
    26. 26. Protecting vegetation/minimizing soil disturbance <ul><li>LID Manual endorses: </li></ul><ul><ul><li>65% native cover = </li></ul></ul><ul><ul><li>rural & large lots </li></ul></ul><ul><ul><li>50% native cover = </li></ul></ul><ul><ul><li>4-6 du/acre </li></ul></ul><ul><ul><li>As much as possible = </li></ul></ul><ul><ul><li>6+ du/acre </li></ul></ul><ul><li>Locate downslope </li></ul><ul><li>Protect tree root zones (1’ per 1” at chest) </li></ul><ul><li>Retain topsoil; use removed soil to amend </li></ul>Source: Timothy Lowry, Pierce Co Public Works & Utilities
    27. 27. Questions <ul><li>How do I keep subs, graders, and/or teenagers off the site (especially swales and gardens)? Are fences and signs really helpful? </li></ul><ul><li>Does less site disturbance really = less cost? </li></ul>
    28. 28. Integrated Management Practices <ul><li>Bioretention areas (rain gardens) </li></ul><ul><li>Amending soils </li></ul><ul><li>Permeable paving </li></ul><ul><li>Vegetated roofs </li></ul><ul><li>Minimal excavation foundations </li></ul><ul><li>Rainwater collection systems </li></ul>Source: Seattle Public Utilities
    29. 29. Bioretention Areas (Rain Gardens) <ul><li>Shallow landscaped depressions with designed soil mix & plants </li></ul><ul><li>Hold & treat water </li></ul><ul><li>Cells v. swales </li></ul>Source: (l) Seattle Public Utilities; (r) Olympia medical plaza
    30. 30. Rain Garden Design <ul><li>Flow entrance </li></ul><ul><li>Pre-treatment filter strip </li></ul><ul><li>Plants </li></ul><ul><ul><li>Drought/saturation tolerant </li></ul></ul><ul><ul><li>No watering req’d after establishment </li></ul></ul><ul><li>Soil zone </li></ul><ul><ul><li>Loamy sand w/ compost amendment </li></ul></ul><ul><ul><li>18” min soil depth </li></ul></ul><ul><li>Mulch (not req’d) </li></ul><ul><ul><li>Compost base/shredded hard or softwood elsewhere </li></ul></ul><ul><ul><li>Not grass clippings or bark </li></ul></ul><ul><li>Filter fabric </li></ul><ul><li>Underdrain (if necessary) </li></ul><ul><ul><li>Can be connected to another swale, cell or storm drain </li></ul></ul><ul><ul><li>6” slotted, thick-walled plastic pipe </li></ul></ul><ul><li>Max ponding depth 12” & 24 hr drawdown </li></ul>Source: MPCA Stormwater Manual, 2005
    31. 31. Also… <ul><li>Keep equipment out of rain gardens during construction! </li></ul><ul><li>General landscape maintenance – replace mulch every two years on residential lots. </li></ul>Source: North Carolina Office of Environmental Education
    32. 32. Questions <ul><li>Who is responsible for maintaining the garden(s)? Homeowner? Public works? Builder? Developer? </li></ul><ul><li>Does the rain garden have to be designed to handle construction run-off? </li></ul><ul><li>Is the rain garden finished before or after home construction (does the builder or developer finish the bioretention areas)? </li></ul>
    33. 33. Amending Soils <ul><li>Stripped, compacted = impervious </li></ul><ul><li>Compost amended soils ↑ retention and ↓ irrigation needs </li></ul><ul><li>Ways to enhance/amend: </li></ul><ul><li>Avoid </li></ul><ul><li>Amend existing disturbed soils </li></ul><ul><li>Stockpile on-site & replace (test and amend w/ organic to 8” depth) </li></ul><ul><li>Import topsoil </li></ul>Same soil with 30% compost Source: Soils for Salmon, UW Soil Study Glacial till w/high runoff, poor turf quality
    34. 34. Amended Soil Design <ul><li>Landscaped areas = 10% organic content </li></ul><ul><li>Turf areas = 5% organic content </li></ul><ul><li>2:1 ratio of loose soil to loose compost landscaped (4:1 turf areas) </li></ul><ul><li>Depth of 12” (8” amended & 4” scarified) </li></ul><ul><li>Mulch planting beds w/ 2 – 3” (max) organic material </li></ul><ul><li>Adds .36¢/sq ft (1997 City of Redmond study) </li></ul>Source: www.BuildingSoil.org
    35. 35. Questions <ul><li>What is the most cost efficient way to amend soil (amend existing, stockpile, or import)? </li></ul><ul><li>Will amending soils change traditional spec landscaping (using evergreens, rhodies, etc.)? </li></ul>
    36. 36. Permeable Paving <ul><li>The good news: initial research shows that properly designed and maintained permeable pavement can almost eliminate surface flows for traditional Puget Sound rain events. </li></ul><ul><li>The bad news: technical design standards, few credits, requires precision installation and long term maintenance. </li></ul>
    37. 37. Permeable Paving Cross Section <ul><li>Surface layer </li></ul><ul><li>Aggregate base (two sizes of stone) </li></ul><ul><li>Geotext fabric (?) </li></ul><ul><li>Treatment layer (sand or amended soil) uncompacted </li></ul><ul><li>Underdrain (if necessary) </li></ul>Source: A. Richard Miller
    38. 38. Permeable Asphalt & Concrete <ul><li>Less sand + admixes = 14-18% void </li></ul><ul><li>100-200+ in water/hr </li></ul><ul><li>Access roads, driveways, parking lots </li></ul><ul><li>Asphalt cost neutral but few local projects & contractors </li></ul><ul><li>Concrete 3X more expensive; placing & finishing almost same </li></ul>Source: TecEco Porecocrete, Australia
    39. 39. Asphalt Sedro-Woolley Photos courtesy of Pete Haase
    40. 40. Concrete <ul><li>StoneyCrete – TX (1/4 – 3/8”) </li></ul><ul><li>PercoCrete – Kenmore (sandy) </li></ul><ul><li>Do not overwork mix, over-handle during finish, and allow 7 covered cure days </li></ul><ul><li>Bunyan Power Screed </li></ul><ul><li>Use National Ready Mix Concrete Association (NRMCA) certified pervious concrete placer </li></ul><ul><li>$3 – 5 sq ft for surface material & install; base aggregate and maintenance add’l </li></ul>Source: Chris Webb & Associates, Bellingham
    41. 41. Top: Stratford Place, 20-lot LID development in Sultan (2002) Pervious Concrete, Inc., Snohomish WA www.perviouscrete.com Bottom: PercoCrete installation on 15’ road Sammamish www.percocrete.com
    42. 42. Interlocking Concrete Pavers <ul><li>Cast-in-place or pre-cast </li></ul><ul><li>SF-RIMA, Turfstone, or EcoStone </li></ul><ul><li>Residential access roads, driveways, walkways </li></ul><ul><li>Subgrade compaction (for stability) makes for impermeable soils (no flow credits) unless high sand & gravel content </li></ul><ul><li>$2.50 - $4.50/sq ft for pavers & install; base aggregate separate </li></ul>Source: (t) Kitsap HBA – SF-RIMA, (m) Mutual Materials - EcoStone, (b) MM - Turfstone
    43. 43. Plastic Grid System <ul><li>Lightweight grid of plastic rings; geotext fabric fused to bottom </li></ul><ul><li>GravelPave 2 or GrassPave2 </li></ul><ul><li>Alleys, driveways, utility access, overflow parking </li></ul>Source: Invisible Structures, Inc.
    44. 44. Keep in Mind… <ul><li>Should not receive water from adjacent areas (during and after construction) </li></ul><ul><li>Maintenance required 1 – 2X annually (vacuuming, replacement) </li></ul><ul><li>Homeowners can’t seal driveways or walks </li></ul><ul><li>Not allowed for slopes exceeding 5 – 10% </li></ul>
    45. 45. Questions <ul><li>Which method is best for residential applications? </li></ul><ul><li>Who provides maintenance (vacuuming) services in the Puget Sound area? </li></ul><ul><li>Will local governments allow pervious asphalt roads in subdivisions? </li></ul>
    46. 46. Green Roofs <ul><li>Extensive v. intensive </li></ul><ul><li>$10 – 15 sq ft installed (w/o plants) </li></ul><ul><li>12 – 15 lbs/sq ft w/ 4” soil mix </li></ul>Source: Going Green at the Beach
    47. 47. Minimal Excavation Foundations <ul><li>Driven piles and connection component at or above grade </li></ul><ul><li>Rick Gagliano has patent on pre-cast w/ driven piles; homes on Gig Harbor and Bainbridge </li></ul>Source: PinFoundations, Gig Harbor
    48. 48. Roof Rainwater Collection <ul><li>Rainwater for non-potable uses (landscaping, toilets) </li></ul><ul><li>Ecology & water rights? </li></ul>Sources: (l) Phinney Neighborhood Assoc, (r) Construction Resources, (ur) City of Portland
    49. 49. Flow Credits <ul><li>Projects have to provide flow control (per muni permits) </li></ul><ul><li>Discharge = pre-developed forested discharge </li></ul><ul><li>Manual Vol I, Table 2.2 shows whether you need a pond </li></ul><ul><li>LID may get you under impervious threshold that triggers flow control req’mt OR you can reduce facility size </li></ul>
    50. 50. Flow Credits <ul><li>Chapter 7 of LID Technical Manual </li></ul>Pasture on native soil Minimal excavation foundations Pond w/steady infiltration (if no drain) Rain gardens Landscaped area Reverse slope sidewalk (2% into soil edge) Landscaped over soil or 50 landscaped/50 imp (no credit if underdrain) Pervious pavement
    51. 51. Questions <ul><li>Can I get flow credits for amending soils? </li></ul><ul><li>Are there other ways to finance a LID project, such as special grants or loans? </li></ul>
    52. 52. Homeowners need to understand maintenance requirements…
    53. 53. Maintenance Agreements <ul><li>Easements, covenants, homeowners’ association requirements </li></ul><ul><li>Most locals will require LID projects to have homeowners’ or other association w/recorded maintenance covenant </li></ul><ul><li>Sample maintenance covenant in Prince County, Maryland manual: Low-Impact Development Design Strategies: An Integrated Design Approach, January 2000 </li></ul><ul><li>High Point Maintenance Guidelines (HP Maintenance Association) available from Seattle Public Utilities </li></ul><ul><li>LID maintenance schedule (WSU, AHBL, PSAT) available from Pierce Co Public Works </li></ul>
    54. 54. Resources <ul><li>PSP/WSU LID Technical Workshop Series </li></ul><ul><li>Low Impact Development Center: www.lowimpactdevelopment.org </li></ul><ul><li>Building Soil: www.buildingsoil.org & Soils for Salmon: www.soilsforsalmon.org </li></ul><ul><li>PSAT’s Low Impact Development Technical Manual </li></ul><ul><li>WSU Rain Garden Handbook for Homeowners </li></ul>
    55. 55. Questions? Jodi Slavik BIAW 1-800-228-4229