A Builder’s Introduction ToA Builder’s Introduction To

Low Impact DevelopmentLow Impact Development

How to Make LID Pencil OutHow to Make LID Pencil Out

For Your ProjectFor Your Project

Common Builder QuestionsCommon Builder Questions

How do I know if my site is good for LID? How do I know if my site is good for LID? Will LID be too expensive to consider?Will LID be too expensive to consider? How many practices must I do to be How many practices must I do to be

considered a LID project?considered a LID project? Can I avoid some permits or reduce the size Can I avoid some permits or reduce the size

of my pond with LID?of my pond with LID? Will the local government be on board?Will the local government be on board? Are there other ways to fund LID on my Are there other ways to fund LID on my

site?site?

What is Low Impact What is Low Impact Development?Development?

Conserving vegetation & soilsConserving vegetation & soils Keeping natural flow pathsKeeping natural flow paths Increasing time on siteIncreasing time on site

LID mimics a site’s natural hydrology by:LID mimics a site’s natural hydrology by:

Source: AHBL Engineering

Which means…Which means… Less impervious surfacesLess impervious surfaces Disconnecting roofs, Disconnecting roofs, downspouts & parking downspouts & parking areasareas

Disbursing small-scale Disbursing small-scale controls vs. large detention controls vs. large detention pondpond

Hydrology 101Hydrology 101

• 50%50% intercepted by intercepted by leaves & evaporatesleaves & evaporates

• 30%30% stored by 2 – 4ft of stored by 2 – 4ft of organic & biologically organic & biologically active soilactive soil

• Of interflow, Of interflow, 10 – 40%10 – 40% goes to groundwater goes to groundwater (that acts as natural (that acts as natural water storage and water storage and maintains instream maintains instream flows)flows)

• Overland flow Overland flow < 1%< 1%

Native forest and soils intercept, store, and Native forest and soils intercept, store, and slowly convey precipitation.slowly convey precipitation.

Source: LID Technical Guidance Manual, Fig 1.1

Urbanization Changes Forest FunctionUrbanization Changes Forest Function

Traditional residential Traditional residential development removes development removes almost all vegetation almost all vegetation and topsoil.and topsoil.evapo-transpirationevapo-transpirationsoil storagesoil storagein groundwaterin groundwaterrapid surface runoffrapid surface runoffpollutants to waterpollutants to waterchannel instabilitychannel instability

Source: LID Technical Manual, Figure 1.3

And We’re Growing!And We’re Growing!

The Puget Sound is The Puget Sound is expected to have 1.4 expected to have 1.4 million more residents million more residents by 2025. by 2025. (Source: OFM)(Source: OFM)

Between 1991 – Between 1991 – 2001, impervious 2001, impervious surface increased by surface increased by 10.4%10.4%

Source: Sightline Institute

Traditional Stormwater ManagementTraditional Stormwater Management

Collecting & conveying to Collecting & conveying to centralized ponds is centralized ponds is reliable, predictable & reliable, predictable & simple to maintainsimple to maintain BUTBUT•90% storage loss v. 25% 90% storage loss v. 25% storage gain storage gain

•Heavy rains = excess to Heavy rains = excess to receiving watersreceiving waters

•Flow/duration standards in Flow/duration standards in 2005 Manual require larger 2005 Manual require larger ponds = ponds = costs and costs and buildable landbuildable land

So…instead of focusing on So…instead of focusing on structurestructure, , LID focuses on LID focuses on landscapelandscape..

Disburse & infiltrate rather than capture Disburse & infiltrate rather than capture and store.and store.

Benefits of LIDBenefits of LID Smaller ponds = more land and less costSmaller ponds = more land and less cost Marketable as green neighborhoodMarketable as green neighborhood Reduce stormwater utility or SEPA feesReduce stormwater utility or SEPA fees Avoid/speed permits or other regulationsAvoid/speed permits or other regulations For local governments:For local governments:

Prevents floodingPrevents flooding Maintains drinking water supplies & instream flowsMaintains drinking water supplies & instream flows Reduces maintenance costsReduces maintenance costs Less need for CSO storage & conveyanceLess need for CSO storage & conveyance Cost effective urban retrofit (especially with fewer Cost effective urban retrofit (especially with fewer

streets, curbs & gutters)streets, curbs & gutters)

So if LID is so great, why aren’t we So if LID is so great, why aren’t we seeing it everywhere?seeing it everywhere?

Still being testedStill being tested LID practices + native vegetation/open space + LID practices + native vegetation/open space +

additional storage = $$$additional storage = $$$ Expensive products and applicationsExpensive products and applications Difficult to find the right soilDifficult to find the right soil Few incentives & difficult to get flow creditsFew incentives & difficult to get flow credits Local governments slow to allowLocal governments slow to allow Conflict within government offices (planning v. Conflict within government offices (planning v.

public works v. fire department, etc.)public works v. fire department, etc.)

SEA Streets, SeattleSEA Streets, Seattle

Reduced impervious Reduced impervious surfaces to 11% less surfaces to 11% less than traditional street; than traditional street; vegetated swales; added vegetated swales; added over 100 evergreen over 100 evergreen trees & 1100 shrubstrees & 1100 shrubs

Cost: $850KCost: $850K Completed spring 2001Completed spring 2001 Prevented all dry season Prevented all dry season

runoff and 99% of wet runoff and 99% of wet season runoff 2000-03; season runoff 2000-03; no runoff since 2003no runoff since 2003

Source: Seattle Public Utilities

High Point, West SeattleHigh Point, West Seattle 120 acres; Phase I 829 units 120 acres; Phase I 829 units

finished 2006; Phase II 2009finished 2006; Phase II 2009 Mixed housing--all 3 star or Mixed housing--all 3 star or

moremore ½ Seattle Housing Authority; ½ ½ Seattle Housing Authority; ½

privateprivate Vegetated swales w/ 3ft Vegetated swales w/ 3ft

amended soils, porous walks, amended soils, porous walks, one porous street, football field one porous street, football field detention pond w/ trail, detention pond w/ trail, overlook & artificial streamoverlook & artificial stream

Intended to process water like Intended to process water like forest meadowforest meadow

Monitoring started 1/07; data in Monitoring started 1/07; data in 3 years3 years

Source: Seattle Public Utilities

Fife Heights, Pierce CountyFife Heights, Pierce County

8.9 acres; 35-lot residential subdivision 48% + in open space; 150 ft. revegetated buffers 20 ft. roadways, including sidewalks Roadside bioswales instead of curb & gutter Amended soils (low infiltrating glacial till) Low Impact Foundation Technology (LIFT) on selected sites Homes finished in 2006/07

Source: AHBL Engineering & WSU, Pierce Co Extension

Source: Pierce Co Public Works & Utilities

Sumner LID Pilot Project, Pierce CountySumner LID Pilot Project, Pierce County

9 units on 2.7 acres9 units on 2.7 acres Completed in 2004Completed in 2004 Driveway pervious Driveway pervious

pavers; vegetated pavers; vegetated swales w/over-drains; swales w/over-drains; amended soils; one amended soils; one sidewalk; curvilinear sidewalk; curvilinear street designstreet design

Sumner monitoring—will Sumner monitoring—will implement LID implement LID ordinances if successful ordinances if successful (open to LID now)(open to LID now)

Source: University of Puget Sound

Cooper Crest, OlympiaCooper Crest, Olympia First to build under First to build under

mandatory LID ordinancemandatory LID ordinance 140 units on 70 acres140 units on 70 acres 1 developer; 2 builders1 developer; 2 builders 55% open space; 18-ft 55% open space; 18-ft

streets; amended yards; streets; amended yards; rain gardens; 20 ft areas to rain gardens; 20 ft areas to infiltrate roof run-off; some infiltrate roof run-off; some porous sidewalkporous sidewalk

Complaints of poor soil, Complaints of poor soil, runoff, crawl space flooding, runoff, crawl space flooding, lawn erosion, and soil & rain lawn erosion, and soil & rain gardens insufficient to gardens insufficient to handle stormwaterhandle stormwater

Whidbey Island ProjectsWhidbey Island Projects Pacific Crest Pacific Crest

Subdivision in Oak Subdivision in Oak HarborHarbor

Bioswales and Bioswales and narrow roadsnarrow roads

Poor homeowner Poor homeowner maintenancemaintenance

The Highlands at The Highlands at LangleyLangley

No stormwater to No stormwater to city drainscity drains

Native vegetation; Native vegetation; pervious pathways, pervious pathways, bioswales; rain gardensbioswales; rain gardens

Under constructionUnder construction

Photos courtesy of Stacy Smith, Whidbey Island Conservation Dist.

LID & GovernmentLID & Government EPAEPA w/other clean water agencies signed w/other clean water agencies signed

letter of intent to formalize use of LID letter of intent to formalize use of LID (April, 2007)(April, 2007)

PSAT/PSPPSAT/PSP action agenda focuses on action agenda focuses on stormwater & LIDstormwater & LID

EcologyEcology stormwater manual & permits stormwater manual & permits LocalLocal ordinancesordinances

Seattle, Tacoma, King, Pierce, Snohomish & Clark – Seattle, Tacoma, King, Pierce, Snohomish & Clark – LID mandatory “where feasible”LID mandatory “where feasible”

Other jurisdictions must allow for LID and determine Other jurisdictions must allow for LID and determine inconsistencies preventing LIDinconsistencies preventing LID

Department of Ecology

Construction Stormwater PermitMunicipal 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 constrand muni permits

WWHM or MGS Flood to estimatesurface runoff and size facilities

SWPPP must use BMPsfrom Manual

SWPPP must use BMPsfrom Manual

Phase I: LID mandatoryPhase II: locals must allow

Addendum to Vol. III providesflow control credits for LID practices

State Stormwater RegulationState 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.”

Local OrdinancesLocal OrdinancesOrdinances allow, encourage or require:Ordinances allow, encourage or require:• Pierce, King, Snohomish, Kitsap CountiesPierce, King, Snohomish, Kitsap Counties• Bellingham, Bothell, Kirkland (clustering), Lacey, Langley, Bellingham, Bothell, Kirkland (clustering), Lacey, Langley,

Marysville, Poulsbo, Port Angeles, Port Orchard, Marysville, Poulsbo, Port Angeles, Port Orchard, Redmond (manual), Sedro Woolley, Tumwater, Olympia, Redmond (manual), Sedro Woolley, Tumwater, Olympia, Seattle, SeaTacSeattle, SeaTac

PSAT/PSP grants (ordinance changes under review):PSAT/PSP grants (ordinance changes under review):• Issaquah, Poulsbo, Woodinville, Edmonds, Normandy Issaquah, Poulsbo, Woodinville, Edmonds, Normandy

Park, Anacortes, Bremerton, Coupeville, Eatonville, Park, Anacortes, Bremerton, Coupeville, Eatonville, Everett, Federal Way, Hamilton, Lake Forest Park, Lake Everett, Federal Way, Hamilton, Lake Forest Park, Lake Stevens, Mill Creek, Mukilteo, Oak Harbor, Clallam, Stevens, Mill Creek, Mukilteo, Oak Harbor, Clallam, Jefferson, Kitsap, Thurston, Whatcom, Mason, San JuanJefferson, Kitsap, Thurston, Whatcom, Mason, San Juan

City of SeattleCity of Seattle• 2/15/08 submitted final draft of stormwater code to DOE2/15/08 submitted final draft of stormwater code to DOE• Requires “green infrastructure technologies” of all single-Requires “green infrastructure technologies” of all single-

family residential to “maximum extent possible”family residential to “maximum extent possible”

Built Green/LEEDBuilt Green/LEED

NAHB model green home building NAHB model green home building guidelines (2006)guidelines (2006)

LID practices earn points toward green LID practices earn points toward green building designationsbuilding designations

Preserve vegetation/trees, amend soil, Preserve vegetation/trees, amend soil, limit impervious/add pervious, use drought limit impervious/add pervious, use drought tolerant plants, install cistern, etc.tolerant plants, install cistern, etc.

LEEDLEED

Types of LID PracticesTypes of LID Practices

Types of LID PracticesTypes of LID Practices

Site planning & layoutSite planning & layout Protecting vegetation/minimizing soil disturbanceProtecting vegetation/minimizing soil disturbance Integrated Management PracticesIntegrated Management Practices

Rain gardensRain gardens Amending soilsAmending soils Permeable pavingPermeable paving Green roofsGreen roofs Minimal excavation foundationsMinimal excavation foundations Roof rainwater collection systemsRoof rainwater collection systems

Site Planning & LayoutSite Planning & Layout

Hydrology as part of Hydrology as part of initial site initial site assessment and assessment and planningplanning

Building sites, roads, Building sites, roads, and stormwater and stormwater infrastructure infrastructure designed around designed around natural features and natural features and LID practicesLID practices

Source: WSU, Pierce County Extension (Kensington Estates)

Minimize connected pervious areaMinimize connected pervious area Narrow Narrow

streets/smaller streets/smaller turnaroundsturnarounds

Curvilinear designCurvilinear design Driveways (20%) – Driveways (20%) –

shared, porous, shared, porous, wheel strips, plastic wheel strips, plastic gridgrid

Sidewalks – 44-48”, Sidewalks – 44-48”, one side, 2% slope to one side, 2% slope to swale, porousswale, porous

Fewer curbs & Fewer curbs & conveyances (that conveyances (that create flow)create flow)

Source: Boston Metropolitan Area Planning Council (t); Puget Sound University (Sumner)

QuestionsQuestions

Does the market want this type of lot Does the market want this type of lot design?design?

Will fire departments allow for Will fire departments allow for narrow roads and limited access?narrow roads and limited access?

Protecting vegetation/minimizing Protecting vegetation/minimizing soil disturbancesoil disturbance

LID Manual endorses:LID Manual endorses: 65%65% native cover = native cover =

rural & large lotsrural & large lots 50%50% native cover = native cover =

4-6 du/acre4-6 du/acre As much as possibleAs much as possible = =

6+ du/acre6+ du/acre Locate downslopeLocate downslope Protect tree root zones (1’ Protect tree root zones (1’

per 1” at chest)per 1” at chest) Retain topsoil; use Retain topsoil; use

removed soil to amendremoved soil to amend

Source: Timothy Lowry, Pierce Co Public Works & Utilities

QuestionsQuestions

How do I keep subs, graders, and/or How do I keep subs, graders, and/or teenagers off the site (especially teenagers off the site (especially swales and gardens)? Are fences and swales and gardens)? Are fences and signs really helpful?signs really helpful?

Does less site disturbance really = Does less site disturbance really = less cost?less cost?

Integrated Management PracticesIntegrated Management Practices

Bioretention areas Bioretention areas (rain gardens)(rain gardens)

Amending soilsAmending soils Permeable pavingPermeable paving Vegetated roofsVegetated roofs Minimal excavation Minimal excavation

foundationsfoundations Rainwater collection Rainwater collection

systemssystems

Source: Seattle Public Utilities

Bioretention Areas (Rain Gardens)Bioretention Areas (Rain Gardens) Shallow landscaped Shallow landscaped

depressions with depressions with designed soil mix & designed soil mix & plantsplants

Hold & treat waterHold & treat water Cells v. swalesCells v. swales

Source: (l) Seattle Public Utilities; (r) Olympia medical plaza

Rain Garden DesignRain Garden Design Flow entranceFlow entrance Pre-treatment filter stripPre-treatment filter strip PlantsPlants

Drought/saturation tolerantDrought/saturation tolerant No watering req’d after establishmentNo watering req’d after establishment

Soil zoneSoil zone Loamy sand w/ compost amendmentLoamy sand w/ compost amendment 18” min soil depth18” min soil depth

Mulch (not req’d)Mulch (not req’d) Compost base/shredded hard or Compost base/shredded hard or

softwood elsewheresoftwood elsewhere NotNot grass clippings or bark grass clippings or bark

Filter fabricFilter fabric Underdrain (if necessary)Underdrain (if necessary)

Can be connected to another swale, Can be connected to another swale, cell or storm draincell or storm drain

6” slotted, thick-walled plastic pipe6” slotted, thick-walled plastic pipe Max ponding depth 12” & 24 hr Max ponding depth 12” & 24 hr

drawdowndrawdown

Source: MPCA Stormwater Manual, 2005

Also…Also… Keep Keep

equipment out equipment out of rain gardens of rain gardens during during construction!construction!

General General landscape landscape maintenance – maintenance – replace mulch replace mulch every two every two years on years on residential lots.residential lots.

Source: North Carolina Office of Environmental Education

QuestionsQuestions

Who is responsible for maintaining the Who is responsible for maintaining the garden(s)? Homeowner? Public works? garden(s)? Homeowner? Public works? Builder? Developer?Builder? Developer?

Does the rain garden have to be designed Does the rain garden have to be designed to handle construction run-off?to handle construction run-off?

Is the rain garden finished before or after Is the rain garden finished before or after home construction (does the builder or home construction (does the builder or developer finish the bioretention areas)?developer finish the bioretention areas)?

Amending SoilsAmending Soils Stripped, compacted = imperviousStripped, compacted = impervious Compost amended soils Compost amended soils ↑ retention and ↓ ↑ retention and ↓

irrigation needsirrigation needs

Ways to Ways to enhance/amend:enhance/amend:

• AvoidAvoid• Amend existing Amend existing

disturbed soilsdisturbed soils• Stockpile on-site & Stockpile on-site &

replace (test and replace (test and amend w/ organic to amend w/ organic to 8” depth)8” depth)

• Import topsoilImport topsoil

Same soil with 30% compost

Source: Soils for Salmon, UW Soil Study

Glacial till w/high runoff, poor turf quality

Amended Soil DesignAmended Soil Design

Landscaped areas = 10% organic contentLandscaped areas = 10% organic content Turf areas = 5% organic contentTurf areas = 5% organic content 2:1 ratio of loose soil to loose compost 2:1 ratio of loose soil to loose compost

landscaped (4:1 turf areas)landscaped (4:1 turf areas) Depth of 12” (8” amended & 4” scarified)Depth of 12” (8” amended & 4” scarified)Mulch planting beds w/ Mulch planting beds w/

2 – 3” (max) organic 2 – 3” (max) organic materialmaterial

Adds .36¢/sq ft Adds .36¢/sq ft (1997 City (1997 City of Redmond study)of Redmond study)

Source: www.BuildingSoil.org

QuestionsQuestions

What is the most cost efficient way to What is the most cost efficient way to amend soil (amend existing, stockpile, or amend soil (amend existing, stockpile, or import)?import)?

Will amending soils change traditional Will amending soils change traditional spec landscaping (using evergreens, spec landscaping (using evergreens, rhodies, etc.)?rhodies, etc.)?

Permeable PavingPermeable Paving

The good news:The good news: initial research shows initial research shows that that properly designed and maintained properly designed and maintained permeable pavement can almost eliminate permeable pavement can almost eliminate surface flows for traditional Puget Sound surface flows for traditional Puget Sound rain events.rain events.

The bad news:The bad news: technical design technical design standards, few credits, requires precision standards, few credits, requires precision installation and long term maintenance.installation and long term maintenance.

Permeable Paving Cross SectionPermeable Paving Cross Section

Surface layerSurface layer Aggregate base (two Aggregate base (two

sizes of stone)sizes of stone) Geotext fabric (?)Geotext fabric (?) Treatment layer Treatment layer

(sand or amended (sand or amended soil) soil) uncompacteduncompacted

Underdrain (if Underdrain (if necessary)necessary)

Source: A. Richard Miller

Permeable Asphalt & ConcretePermeable Asphalt & Concrete

Less sand + admixes Less sand + admixes = 14-18% void= 14-18% void

100-200+ in water/hr100-200+ in water/hr Access roads, Access roads,

driveways, parking lotsdriveways, parking lots Asphalt cost neutral Asphalt cost neutral

but few local projects but few local projects & contractors& contractors

Concrete 3X more Concrete 3X more expensive; placing & expensive; placing & finishing almost samefinishing almost same

Source: TecEco Porecocrete, Australia

AsphaltAsphaltSedro-WoolleySedro-Woolley

Photos courtesy of Pete Haase

ConcreteConcrete StoneyCrete – TX (1/4 – 3/8”)StoneyCrete – TX (1/4 – 3/8”) PercoCrete – Kenmore PercoCrete – Kenmore

(sandy)(sandy) Do not overwork mix, over-Do not overwork mix, over-

handle during finish, and allow handle during finish, and allow 7 covered cure days7 covered cure days

Bunyan Power ScreedBunyan Power Screed Use National Ready Mix Use National Ready Mix

Concrete Association Concrete Association (NRMCA) certified pervious (NRMCA) certified pervious concrete placerconcrete placer

$3 – 5 sq ft for surface $3 – 5 sq ft for surface material & install; base material & install; base aggregate and maintenance aggregate and maintenance add’ladd’l

Source: Chris Webb & Associates, Bellingham

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

Interlocking Concrete PaversInterlocking Concrete Pavers Cast-in-place or pre-castCast-in-place or pre-cast SF-RIMA, Turfstone, or SF-RIMA, Turfstone, or

EcoStoneEcoStone Residential access Residential access

roads, driveways, roads, driveways, walkwayswalkways

Subgrade compaction Subgrade compaction (for stability) makes for (for stability) makes for impermeable soils (no impermeable soils (no flow credits) unless high flow credits) unless high sand & gravel contentsand & gravel content

$2.50 - $4.50/sq ft for $2.50 - $4.50/sq ft for pavers & install; base pavers & install; base aggregate separateaggregate separate

Source: (t) Kitsap HBA – SF-RIMA, (m) Mutual Materials - EcoStone, (b) MM - Turfstone

Plastic Grid SystemPlastic Grid System

Lightweight grid Lightweight grid of plastic rings; of plastic rings; geotext fabric geotext fabric fused to bottomfused to bottom

GravelPave 2 or GravelPave 2 or GrassPave2GrassPave2

Alleys, Alleys, driveways, utility driveways, utility access, access, overflow parkingoverflow parking

Source: Invisible Structures, Inc.

Keep in Mind…Keep in Mind…

Should not receive water from adjacent Should not receive water from adjacent areas (during and after construction)areas (during and after construction)

Maintenance required 1 – 2X annually Maintenance required 1 – 2X annually (vacuuming, replacement)(vacuuming, replacement)

Homeowners can’t seal driveways or Homeowners can’t seal driveways or walkswalks

Not allowed for slopes exceeding 5 – 10%Not allowed for slopes exceeding 5 – 10%

QuestionsQuestions

Which method is best for residential Which method is best for residential applications?applications?

Who provides maintenance (vacuuming) Who provides maintenance (vacuuming) services in the Puget Sound area?services in the Puget Sound area?

Will local governments allow pervious Will local governments allow pervious asphalt roads in subdivisions?asphalt roads in subdivisions?

Green RoofsGreen Roofs Extensive v. intensiveExtensive v. intensive $10 – 15 sq ft installed $10 – 15 sq ft installed

(w/o plants)(w/o plants) 12 – 15 lbs/sq ft w/ 4” 12 – 15 lbs/sq ft w/ 4”

soil mixsoil mix

Source: Going Green at the Beach

Minimal Excavation FoundationsMinimal Excavation Foundations Driven piles and Driven piles and

connection component at connection component at or above gradeor above grade

Rick Gagliano has patent Rick Gagliano has patent on pre-cast w/ driven on pre-cast w/ driven piles; homes on Gig piles; homes on Gig Harbor and BainbridgeHarbor and Bainbridge

Source: PinFoundations, Gig Harbor

Roof Rainwater CollectionRoof Rainwater Collection

Rainwater for non-potable Rainwater for non-potable uses (landscaping, toilets)uses (landscaping, toilets)

Ecology & water rights?Ecology & water rights?

Sources: (l) Phinney Neighborhood Assoc, (r) Construction Resources, (ur) City of Portland

Flow CreditsFlow Credits

Projects have to provide flow control (per Projects have to provide flow control (per muni permits)muni permits)

Discharge = pre-developed forested Discharge = pre-developed forested dischargedischarge

Manual Vol I, Table 2.2 shows whether Manual Vol I, Table 2.2 shows whether you need a pondyou need a pond

LID may get you under impervious LID may get you under impervious threshold that triggers flow control req’mt threshold that triggers flow control req’mt OR you can reduce facility sizeOR you can reduce facility size

Flow CreditsFlow CreditsChapter 7 of LID Technical ManualChapter 7 of LID Technical Manual

Pervious pavementPervious pavement Landscaped over soil or Landscaped over soil or 50 landscaped/50 imp 50 landscaped/50 imp (no credit if underdrain)(no credit if underdrain)

Reverse slope sidewalk Reverse slope sidewalk (2% into soil edge)(2% into soil edge)

Landscaped areaLandscaped area

Rain gardensRain gardens Pond w/steady Pond w/steady infiltration (if no drain)infiltration (if no drain)

Minimal excavation Minimal excavation foundationsfoundations

Pasture on native soilPasture on native soil

QuestionsQuestions

Can I get flow credits for amending Can I get flow credits for amending soils?soils?

Are there other ways to finance a Are there other ways to finance a LID project, such as special grants LID project, such as special grants or loans?or loans?

Homeowners need to understand maintenance requirements…

Maintenance AgreementsMaintenance Agreements Easements, covenants, homeowners’ Easements, covenants, homeowners’

association requirementsassociation requirements Most locals will require LID projects to have Most locals will require LID projects to have

homeowners’ or other association w/recorded homeowners’ or other association w/recorded maintenance covenantmaintenance covenant

Sample maintenance covenant in Prince County, Sample maintenance covenant in Prince County, Maryland manual: Maryland manual: Low-Impact Development Low-Impact Development Design Strategies: An Integrated Design Design Strategies: An Integrated Design Approach,Approach, January 2000 January 2000

High Point Maintenance Guidelines (HP High Point Maintenance Guidelines (HP Maintenance Association) available from Seattle Maintenance Association) available from Seattle Public UtilitiesPublic Utilities

LID maintenance schedule (WSU, AHBL, PSAT) LID maintenance schedule (WSU, AHBL, PSAT) available from Pierce Co Public Worksavailable from Pierce Co Public Works

ResourcesResources

PSP/WSU LID Technical Workshop SeriesPSP/WSU LID Technical Workshop Series Low Impact Development Center: Low Impact Development Center:

www.lowimpactdevelopment.orgwww.lowimpactdevelopment.org Building Soil: Building Soil: www.buildingsoil.orgwww.buildingsoil.org & Soils & Soils

for Salmon: for Salmon: www.soilsforsalmon.orgwww.soilsforsalmon.org PSAT’s Low Impact Development PSAT’s Low Impact Development

Technical ManualTechnical Manual WSU Rain Garden Handbook for WSU Rain Garden Handbook for

HomeownersHomeowners

Questions?Questions?Jodi SlavikJodi Slavik

BIAWBIAW

1-800-228-42291-800-228-4229