Water  Environment  Transportation  Energy  Facilities

TheBigGreenApple

November 16, 2015

Maine Stormwater Conference+ NE IECA Annual ConferenceSouth Portland, Maine

Virginia Roach, P.E.

Overview

• Green infrastructure approach in New York City

• Programmatic areas of the NYC Green Infrastructure Program

• Right‐of‐Way Program• Public Retrofit Program

• Maintenance• Costs

NewYorkCityGreenInfrastructureApplicationRatesandMilestoneSchedule

0%

1%

2%

3%

4%

5%

6%

7%

8%

9%

10%

2010 2015 2020 2025 2030

Initial 1.5% Additional 2.5% Additional 3.0% Final 3% 10% Target

$1.5 billion projected over the 20‐year program.

Manage 1” of stormwaterrunoff from 10% of impervious surfaces in combined sewer areas by 2030

AdaptiveManagementPlan2014AnnualReportSuccesses

• 3 demonstration areas (70 ROWBs)

• Manage 14% of impervious areas

• 20% reduction in runoff to combined sewer in typical storm

• Early 2015• 300 ROWBs constructed• 1,300 under construction

• End of 2015• 5,600 practices projected 

• Constructed, in construction, registered with Notice to Proceed

Area‐WideDesignBB‐008

The Bronx

Queens

Brooklyn

= does not meet water quality standards(pathogens/DO)

Right‐of‐WayBioswales

Right‐of‐WayBioswales–StandardDesigns

SiteSelectionProcess1.TributaryDrainageAreaAnalysis

• BB‐008 (1,200 acres):  More than 4,700 ROWBs needed to manage 100% of impervious ROW area 

SiteSelectionProcess2.Walk‐ThroughstoInvestigatePotentialSites

• BB‐008:  More than 950 Preliminary ROWB locations identified

DOTBioswaleSitingCriteria

ROW Siting Criteria examples:• Mature Trees• Sidewalk widths (8’ or 5’)

• Fire Hydrants• Pedestrian Ramps• Building Entrances/Exits• Driveways• Muni Meters• Bus Stops

PracticalDesignConsideration:BasementFloodProtection

DevelopedEfficientInspectionApp

TheApp

DailyReports

UpdatesinRealTimeAcrossAllApplications

SiteSelectionProcess3.BoringsandPermeabilityTests

• BB‐008• 646 geotechnical investigations representing 895 sites

• 70% success rate• Permeable soils• Low groundwater

SiteSelectionProcess4.LimitedSurvey

• BB‐008• 4 ROWB construction contracts

• 375 ROWBs• $12,300 per ROWB

StormwaterGreenstreets

ExistingRoadway

StormwaterGreenstreet

BB‐008PublicOn‐SitePropertyRetrofitsOpportunities

CoronaGolfPlayground

PublicPropertyRetrofits:Edenwald Houses‐ ACollaborationwiththeNewYorkCityHousingAuthority(NYCHA)

Edenwald Houses

• Hutchinson River CSO tributary area (HP‐024)

• Largest NYCHA development in the Bronx

• 41 buildings• 3‐story and 14‐story• Community Center

• 5,450 residents

Edenwald Houses

Total drainage area• 53 acres• 54% impervious

• Sidewalks 17%• Buildings 14%• Roadways 8%• Parking areas 3%

Edenwald HousesGeotechnicalInvestigations:LowPermeabilityRates

• 0.00014 to 0.13 in/hr at Edenwald Houses• 0.2 in/hr min for groundwater recharge (NJ)• 0.17 in/hr min for stormwater infiltration (MA)

• At 0.13 in/hr – 3 days to infiltrate 10 inches of water• High percentage of fines in soils (>20%)

Edenwald Houses:FinalDesignofGreenInfrastructurePractices

• Vegetated bioretentionareas

• Rain gardens• Rooftop runoff redirection to green infrastructure

• Porous pavements

Edenwald HousesVegetatedBioretention Areas

Before After

Edenwald Houses:RooftopRunoffRedirectiontoGreenInfrastructure

PorousAsphalt

Cast‐in‐PlacePerviousConcrete

“Hose Test”

PrecastPerviousConcretePanels

Edenwald Houses:PermeablePaversandRainGardensatEntranceAreas

After

Before

PracticalDesignConsideration:UseAvailableStorageinPorousPavementandMitigateBreakout

EdenwaldHouses35%ofImperviousAreaManaged

Not Managed by Green Infrastructure

65%

Building Entrances, Walkways and Vehicle 

Access Drives (Permeable Pavers, Porous Asphalt, Pervious Concrete)

18%

Vegetated BioretentionAreas / Rain Gardens

11%

Parking Areas (Porous Asphalt)

6%

Edenwald HousesPercent of Impervious Area Managed by Green Infrastructure

ROWBMaintenance

• Current NYC DEP practices• Inspect and remove trash every two weeks during construction

• Inspect and remove trash every week after construction

• Evaluating maintenance practices under ongoing R&D Program

• GIS‐Based Project Tracking and Asset Management System

VegetatedBioretention Area/RainGardenMaintenance

• Highest maintenance first two years

• Seasonal weeding, raking and pruning

• Infiltration improves over time as roots establish

PorousPavementMaintenance

• Inspect once per year• Vacuum sweep two to four times per year

• Power wash if needed• Permeable pavers

• Regenerative air or traditional sweeper

• Replenish joint material

HartfordGreenCapitolsO&MManual

Porous Asphalt Winter Maintenance:• Remove snow promptly• Slightly raised plow

preferred• Do not use sand

HartfordGreenCapitolsMeasuringSuccess– October2015

EdenwaldHouses‐ NorthCostperImperviousAcreManaged

 $‐

 $100,000

 $200,000

 $300,000

 $400,000

 $500,000

 $600,000

 $700,000

Rain Gardens VegetatedBioretention Areas

Veg Bio Areas w/PlumbingRedirection

Porous Pavements Total

Engineer's Estimate

Bid Costs

Questions?

nyc.gov/dep/greeninfrastructure