Green Infrastructure Performance in NYC

Transcription

1 January 8, 2015 Ackerson Hall Rutgers-Newark Green Infrastructure Performance in NYC Carter H. Strickland, Jr Vice President 2014 HDR, Inc., all rights reserved.

2 NYC Green Infrastructure Plan Evaluating GI for LTCPs and CSO benefits Review of postconstruction GI monitoring (PCM) results Discussion

3 NYC Green Infrastructure Plan

4 NYC Green Infrastructure

5 Planning Phase: Estimate of Performance 30,000 25,000 GREEN STRATEGY -5,666 built/under construction GREY STRATEGY 2045 BASELINE - PROJECTION FROM 2007 FACILITY PLANS -5,666 built/under construction -2,602 planned -2,547 planned Annual CSO Volume (millions of gallons) 20,000 15,000 10,000 21,698-1,701-1, ,896 21,753-1,945 19,808 5,000 - Cost-Effective Grey Investments (Built & Planned) Reduced Flow Green Infrastructure (10% Capture) Optimize Existing System Green Strategy Cost-Effective Grey Investments (Built & Planned) Potential Tanks, Tunnels, & Expansions Grey Strategy

6 Planning Phase: Estimate of Costs $8.0 $7.0 $6.8 $6.0 $5.0 $0.03 $5.3 $0.9 $3.9 $4.0 $3.0 $1.5 $2.4 $2.0 $1.0 $2.9 $2.9 $- Green Strategy Potential Tanks, Tunnels, & Expansions Green Infrastructure - Private Investment Reduced Flow Grey Strategy Optimize Existing System Green Infrastructure - Public Investment Cost-Effective Grey Investments

7 Planning Phase: Estimate of Additional Benefits

8 Co-benefits: Schoolyards to Playgrounds

9 Co-benefits: Right of Way Bioswale

10 Co-Benefits: Grant Program

11 NYC CSO Consent Decree Modification (2012) Benefits $1.4 billion in savings from substituted green and grey infrastructure $2 billion in grey infrastructure deferred Key elements Over $187 million in green infrastructure through neighborhood scale pilot projects to be monitored 5 year milestones and overall commitment to managing 10% of CSS area for 1 storm by 2030 Adaptive management structure

12 Performance Standards

13 Review of NYC s Post- Construction Monitoring Program and Results

14 NYC GI Monitoring (Site Scale) City-Owned Sites Right-of-Ways Agency Buildings and Parking Lots Public Housing City Parks Public Schools

15 Monitoring Equipment Roof Drain Inserts ISCO 4230 Bubble Flow Meter Weather Station Arlyn Series 320D-CR Scales and Data Logger V-notch Weir and Pressure Transducer Stage Gauge Water Level Logger and Weir Plate H-flume Water Quality Sampling Wells Piezometers Hydrant Testing Infiltration Testing

16 Monitoring Approach Site Scale Inflow and outflow measured with remote monitoring equipment. Soil moisture and ponding levels measured. Equipment monitored performance at regular intervals, typically five minutes. Site visits conducted regularly to download data, maintain equipment and assess qualitative monitoring aspects. Rain gauges or weather stations at most locations to collect locallyaccurate weather data. Calibrate, calibrate, calibrate!!!!

17 Blue Roofs DEP s Metropolitan Ave. Storehouse Modified Inlet 2 Check Dams Trays 2

18 Blue Roof Monitoring June 22, Storm Benefit Benefit

19 Blue Roof Performance: Volume Reduction Results for (~70 storms) Designed for peak shaving, but achieve good volume capture through ponding/evaporation Trays: most consistent results (50-80% retention)

20 Blue Roof Performance: Peak Flow Reduction Results for (~70 Storms) All types provide good peak shaving Trays most consistent, ~80-100% reduction of peak flow

21 Permeable Pavement Far Rockaway Bus Terminal Parking Lot Porous Pavement Standard Asphalt FilterPave 21

22 Permeable Pavement Performance: Volume Retained Volume Retained Volume Retained Results (96 Storms) FilterPave consistently captures 100% Standard and Porous Asphalts variable Porous Asphalt generally captures >50% FilterPave experiencing wear and tear Volume Retained Rainfall Depth (in) Rainfall Depth (in)

23 Subsurface Detention & Infiltration NYCHA Bronx River Houses Perforated Pipes South Parking Lot North Parking Lot 23

24 Subsurface Systems Performance: Peak Flow & Volume Reduction Chamber System Perforated Pipe System

25 Rain Gardens NYCHA Bronx River Houses RAIN GARDENS

26 Rain Gardens Monitoring: 1.4 Storm, May 24, 2012 (Ponding Depth)

27 Rain Gardens Performance: Volume Retained Volume Retained 100% 80% 60% 40% 20% 0% Bio 1-7:1 Bio 2-6:1 Effective Storm Depth (in) Volume Retained 100% 80% 60% 40% 20% 0% Effective Storm Depth (in) Volume Retained 100% 80% 60% 40% 20% 0% Bio 3-9:1 Bio 4-17:1 Effective Storm Depth (in) Volume Retained 100% 80% 60% 40% % % Effective Storm Depth (in)

28 N&S Conduit Bioretention Impervious Area 81,870 ft² DA: GI Footprint 11:1

29 N&S Bioretention: Data Summary Monitoring data from August 2011 to December 2012 Maintenance: Removal of debris and sediment from curb cuts Weeding and mulching Storm Characteristics Number of Storms Storm Depth 0.11 to to 2.78 Peak Intensity 0.24 to 4.92 in/hr 0.24 to 4.2 in/hr Storm Duration 0.2 to 53 hrs 1.5 to 77 hrs

30 Roadway Median Monitoring: 2.6 Storm, June 12, 2012 Ponding Depth

31 N&S Bioretention: Observations Only 4 outflow events since installation Typical surface drawdown duration < 8 hours Ponding drawdown rate increasing, and fewer ponding events occurring, likely due to root growth Vegetated swales effective at infiltrating offsite runoff Volume Retention 100% 80% 60% 40% 20% 0% Effective Storm Depth (in) Drawdown Rate (in/hr) Jun-11 Sep-11 Dec-11 Mar-12 May-12 Aug-12 Nov-12 East West

32 Enhanced Tree Pits Dimensions: 20 ft L x 5 ft W x 5 ft D Entirely in right-of-way Widespread opportunity Pilot findings: Performance results Design modifications Maintenance program

33 Enhanced Tree Pits Monitoring: 1.5 Storm, Dec 7, 2011 Blake Ave ETP

34 Enhanced Tree Pits Performance: Volume Retention at 4 Sites

35 Results of Monitoring Other Bioswales Percent of rainfall captured by 10 bioswales over 185 rain events. Bioswales performed best during storms with less than one inch of rain. Percent Capture of 10 Bioswales Rainfall (in.) Mean Median Below 1 73% 85% % 21% Above 2 14% 12% Total 59% 60%

36 NYC Neighborhood Demonstration Projects

37 Monitoring Approach Demonstration Areas Data collected to measure sewer flow reductions Flow meters located at the point where the sewer exits the Demonstration Area catchment area Meters record flow and depth within the main outlet sewer Data acquisition is continuous with measurements recorded at 15 minutes intervals Piezometers and soil moisture sensors were installed with ROWBs to measure local conditions

38 Demonstration Projects: In-Sewer Monitoring Locations Demo Area 2 Demo Area 3

39 Demonstration Areas Runoff Reduction Observations Percentage of Rainfall Flowing in Sewer

40 Preliminary Conclusions about Success of GI Systems All source controls have provided benefits for storms < 1 In many cases, bioretention source controls have fully retained the volume of one-inch storms they receive The condition of underlying soils have an impact on retention performance and overall source control functionality Source controls designed primarily for detention also retain runoff volumes Porous pavement performance varied for different types Performance generally improved in vegetated systems due to the growth and establishment of plants

41 Evaluating GI for LTCPs and CSO Benefits

42 Scaling up Performance Neighborhood Site Acres to Tens of Acres Infiltration - Native soil - Engineered soil Storage - Stone porosity - Soil porosity Peak flow reductions Sewershed Tens to Hundreds of Acres Long term sewer flow reductions Hundreds to Thousands of Acres

43 Modeling Approach for LTCPs Goals Demonstrate that the potential reduction in CSO from areawide application of GI system, when performance of GI installations varies based on location, site conditions and type of GI Ensure evaluation of grey and green CSO reduction strategies are equivalent Solutions Scale-up or lump individual installations subcatchment-wide Allows for different types of GI i.e., detention and retention to be accounted for in model Also allows for other types to be added later dependent rate of installations

44 Identifying Sewersheds for GI Implementation Attainment of water quality standards Planned/constructed grey controls, remaining CSO volumes and capital costs Ratio of separate stormwater to CSO discharges Proximity to public access locations, planned improvement projects, etc.

45 Opportunities Analysis

46 Waterbody Based Targets Waterbodies/Watersheds CSIA (Acres) ROW Public Onsite Public Onsite Private Total Managed Acres Percent of CSIA Managed Acres Percent of CSIA Current Phase: Priority Drainage Areas Managed Acres Percent of CSIA Managed Acres Percent of CSIA Alley Creek 1,490 0% 0% % % Bronx River 2, % % % % Coney Island Creek 694 0% 0% 7 1.0% 7 1.0% Flushing Bay 4, % % % % Flushing Creek 5, % 0% % % Gowanus Canal 1, % 5 0.4% % % Hutchinson River 1, % % % % Jamaica Bay & CSO Tributaries 7, % % % % Newtown Creek 4, % % % % Westchester Creek 3, % % % % Future Phase: DEP will explore opportunities for remainder of 10% GI target

47 LTCP Alternatives Evaluations for Green & Grey Typically, a multi-step process is applied: 1. Fatal flaw and feasibility review Community Disruption/Potential for Nuisances Constructability/Permitting Operating Complexity/Ease of O&M 2. Quantify Impacts Pollutant Reduction/Water Quality Improvements Control of Discharge to Sensitive Areas Flood Control Environmental Justice Ancillary Community Benefits Sustainability i.e., Energy Savings 3. Quantify Costs 4. Knee-of-the-curve selected (for highest ranked, acceptable, technically feasible CSO control measures)

48 LTCP Alternatives Evaluations for Green & Grey Questions: Application of 2012 EPA Recreational Water Quality Criteria and associated challenges? How to define non-economic criteria? Equally relevant criteria for all member communities? Weighting of criteria? Guidance for consistent evaluation process and criteria?

49 Conclusions Monitoring over several seasons is critical to testing model assumptions and controlling for site specific soil and other conditions A common methodology for green infrastructure stormwater controls is important for comparing green and gray alternatives and for consistency between cities Learn from early action or pilot projects Cost-effectiveness can be maximized during site and technology selection Modeling is an effective way to get a working estimate of CSO reductions from green infrastructure for developing LTCPs

50 Discussion

51 Questions? Carter Strickland