Green Infrastructure Implementation Planning for Multiple Objectives

Transcription

1 Green Infrastructure Implementation Planning for Multiple Objectives Hazem Gheith, ARCADIS September 10, 2014 Imagine the result

2 Integrated Plan for Stormwater Control Integrated Plan Objective Sanitary Modeling and Overflow Mitigation Plan Stormwater Modeling and Flooding Mitigation Plan

3 Integrated Plan Objective Protect Public Health Sanitary System: Mitigate sewage overflowing to receiving waters or backing up into basements by reducing excessive rain driven inflow and infiltration (RDII) Stormwater System: Reduce pollution to the receiving waters and mitigate backups and street flooding Control cost by coordinating one solution to both

4 Workflow Diagram Sanitary Mitigation Planning Investigate RDII Sources (GIS) Define and Understand the Problem Stormwater Mitigation Planning Investigate Runoff and Pollutant Loading (GIS) Construct House- Level Resolution H/H Model Prepare the Planning Tool Construct House Level Resolution Storm Model Quantify Inflow Sources and Deficiencies Understand Existing LOS Quantify Inflow Sources and Deficiencies Define Suite of Effective RDII Reductions Plans Mitigate SSOs, CSOs and WIB Alternatives Planning Additional Flow between the Systems One Integrated Plan Solution Define Suite of Effective GI Technologies Mitigate Pollution (TMDL) and Street Flooding Balance RDII Reduction and Storm Water Controls to Make Certain One System is not Improved at the Expense of the Other! Cost Benefit Analysis

5 Blueprint Columbus City wide Integrated Plan to be presented to OEPA by September 2015 Pilot project Park of Roses Sub-basin: Mitigate an active SSO at the Park Reduce stormwater street flooding Improve TMDL into the Ravine POR sub-basin

6 Sanitary Overflow Mitigation Plan Detailed Sanitary Modeling Quantify RDII sources Select mitigation plan

7 RDII Process and Potential Solutions Evapotranspiration Infiltration to Groundwater Increase flow into storm system Increase flow into storm system Precipitation Surface runoff Storm water arrives at vicinity of sanitary system Leaks through sanitary system defects as RDII Routing through Storm System Receiving waters Mitigation 1: Divert runoff away from sanitary system Mitigation 2: Rehab pipes and MHs defects in sanitary system

8 Potential RDII Inflow Points (1) Direct Downspout Connection (2) Foundation Drain (3) & (4) Private and Public Lateral Service (5) & (6) Manhole Lids and Manholes Castings (7) & (8) Manhole Structures and Sewer Mains under pervious or cracked impervious surface (9) Sewer Mains in trenches parallel to colocated storm pipe trenches

9 (1) Direct Downspout Connection Contributing area = roof top Remediation: Redirect roof drainage to the street

10 (2) Foundation Drains Contributing area = roof top + buffer area around the house Remediation: Redirect roof drainage to the street (partial) or install stormwater sump pump

11 (3) & (4) Private and Public Laterals Contributing area = buffer area around the lateral pipe Remediation: Line the lateral pipes

12 (5) & (6) Manhole Lids and Castings Contributing area = ponding around and above the MH Remediation: Rehab MHs cover and casting

13 (7) & (8) MH Structure and Sewer Main Contributing area is a buffer around the main pipe Remediation: Line the main pipe and rehab the MHs structure

14 (9) Sewers Colocated with Storm pipes Contributing leaks from pressured storm pipes to sanitary pipe trenches Remediation: Line sanitary and/or storm pipes

15 Subareas and Connectivity Split the area into its RDII sources (GIS) Roof Drainage Splashing Buffer1 (Splash houses) Lateral Pipes Area Main Sewers Area Surface flow Subsurface flow Roof Drainage Directly Connected Buffer2 (Rest of houses) Lawn Area Garages Impervious surface Areas with aquifers Roof Drainage To Street Street/ Driveway Colocated Main Trench Upstream Strom System Sanitary System Storm Inlet

16 Computed RDII Sources Percentage Sources A22A A26A Foundation Drain Private 34.4% 36.3% 31.9% 34.5% 30.5% 43.6% Private Lateral Private 25.8% 18.2% 22.3% 22.7% 15.1% 15.7% Co-located Mainline/Storm Public Pipes 26.9% 13.3% 26.4% 16.8% 20.4% 16.2% Mainline and Manhole Public Structures 10.1% 16% 17.6% 33.2% 29.1% 22.4%

17 RDII Mitigation Plan Blueprint Columbus

18 Quantifying RDII Mitigation Redirection House Splashing Buffer1 Lateral Pipes Area Main Sewers Area Sump Pump Lining Lining Redirection House Directly Connected Buffer2 Remaining Pervious Area Garages House To Street Remaining Impervious Area Colocated Main Trench Upstream Strom System Sanitary System Storm System Evaluate and mitigate negative impact on the storm system

19 Stormwater Flooding Mitigation Plan Detailed runoff modeling GI footprint to mitigate roofs rerouting GI footprint to improve water quality Additional plans to increase stormwater LOS

20 Stormwater Planning Objectives Objective 1: Mitigate the impact of RDII reduction on the stormwater flow using green infrastructures. Objective 2: Using GI, how much water quality improvement could be achieved? Objective 3: How much stormwater LOS could be achieved by adding more GI footprints and/or gray structures (upsized pipes)?

21 Objective 1: Mitigate the impact of RDII reduction on the stormwater Evaluation Process: Calculate stormwater LOS before and after RDII mitigation 16 years of spatially-distributed historical storm data Calculate required GI footprint to mitigate the impact Calculate GI construction cost

22 Pilot Area: Chatham Rd Existing Flooding LOS is ~1.6 years

23 Detailed Modeling Area: 30 acres 15 storm inlet sub-catchments with average slope 2.6% BLENHEIM RD NORTHRIDGE RD!. " "!. " N HIGH ST!. FOSTER ST!. " " " "!.!. " " CHATHAM RD!.!. " " SHARON AV!. "!. " " CHATHAM RD " ACTON RD RICHARDS RD GRANDEN RD

24 Model Enhancements A house-scale model is needed to prepare for an educated GI alternative analysis House Roofs (discon.) House Perimeter Lawns Split Garages House Roofs (to street) Alleys Driveways / Streets Commerc ial Roof Parking Storm Inlet Storm Pipe Outfall

25 Detailed Runoff Model Split inlet catchments into detailed surface features Splash Roofs House Perimeter Garages 1.5 acres Roofs draining to Lawn Roofs draining to Street Lawn area around the house (high infiltration rate below top soil) Lawn area away from the house (low infiltration rate below top soil) Streets 6.3 acres 3.9 acres 17.6 acres Sanitary Pipe Garages to Lawn Roofs to Street Roofs to Sanitary Strom Pipe Lawns Driveway / Streets Storm Inlet Outfall

26 Existing Condition No roofs directly connect to sanitary pipes Roofs to Lawn House Perimeter Garages to Lawn Lawns Roofs to Street Driveway / Streets Roofs to Sanitary Storm Pipe Storm Inlet Outfall 50% of roof drainage splashes around the house

27 Base Scenarios Route all roof drainage to street (to minimizing RDII in sanitary system) Roofs to Lawn Buffer Lawns Garages to Lawn Lawns Roofs to Street Driveway / Streets Roofs to Sanitary Manhole Storm Inlet Outfall

28 Existing versus Base Conditions Flood Recurrence Event Rank Recurrence (Years) Date Existing OF Vol. (MG) Date Base OF Vol. (MG) /26/ /26/ /4/ /4/ /27/ /27/ /19/ /30/ /29/ /29/ /30/ /19/ /11/ /28/ /28/ /11/ /23/ /18/ /24/ /23/ /22/ /22/ /24/ Track flooded volume from all manholes in pilot area Existing LOS: ~1.6 yrs Base condition LOS: ~1.2 yrs

29 Total MH Overflow Volume (MG) Existing versus Base Conditions Calculate rain gardens footprint required to bring system back to existing condition MH Flooding Recurrence Curve Existing Base Recurrence (years)

30 Mitigation Scenarios Apply rain gardens footprint Roofs to Lawn Buffer Lawns Garages to Lawn Lawns Roofs to Street Driveway / Streets Rain Garden Storm Pipe Storm Inlet Outfall

31 Chatham Rd: Existing vs. Base Conditions Rain Gardens Footprint Required to Offset Additional Flooding from Rerouting Roof Drainage to Street LOS (years) Existing Flooding Volume (MG) Additional Flooding Volume (MG) Required Rain Garden Footprint (SF) Cost per acre ,164 $12, ,725 $8, ,232 $5, $0 Assume rain gardens with 4 feet depth (3 feet of storage material with 33% available voids plus 1 ft of freeboard) Assume installation and O&M cost of $70 per SF

32 Total Suspended Solids Removal % Objective 2: How much water quality improvement could be achieved? 100.0% Performance Curve for Rain gardens TSS Removal vs. Cost per 10 Acres Medium Density Residential, 0.01 Soil Infiltration Rate, 80% Runoff Capture into the RG 90.0% 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% Knee of the curve is at about 58% TSS removal (~$15,000/acre) 0.0% $- $200,000 $400,000 $600,000 $800,000 $1,000,000 $1,200,000 Cost/10Acres * Prepared by EMH&T for the City of Columbus

33 Base versus WQ RGs 11,700 sf of water quality rain gardens for the 30 acres Base Condition Ran Recurrence k (Years) OF Date (MG) /26/ /4/ /27/ /30/ /29/ /19/ /28/ /11/ /18/ /23/ /22/ /22/ /24/ WQ Rain Gardens Ran Recurrence k (Years) OF Date (MG) /26/ /27/ /4/ /29/ /19/ /30/ /11/ WQ RGs increases LOS from 1.2 years to 2.4 years

34 Objective 3: Increase LOS by adding More GI per Site Availability BLENHEIM RD NORTHRIDGE RD CHATHAM RD SHARON AV CHATHAM RD N HIGH ST ACTON RD AMAZON PL RICHARDS RD GRANDEN RD FOSTER ST FALLIS RD ACTON RD FOSTER ST Three Scenarios: Max RG on tree lawn Max RG on tree lawn and street Max RG and pervious pavement at intersections (18 gravel)

35 LOS, Years LOS versus Cost Comparison 3.5 Flow LOS (yrs) versus Construction Cost (per acre) RG WQ Max RG Tree Lawn Max RG RG + PP Tree Lawn + Bump Out 1.5 Existing 1 Base $0 $20,000 $40,000 $60,000 $80,000 $100,000 $120,000 Construction Cost (per acre)

36 Gray Improvement Level 1 Pipe Start with WQ rain gardens footprint, upsize deficient pipes to reach a 5 years LOS Pipe Size Required for LOS (ft) WQ RG Condition (LOS 2.1 Years) Level 1 Gray (LOS 4.5 years) Pipe Pipe Pipe Pipe WQ Rain Gardens Gray Level 1 Recurrence Rank (Years) MH OF Vol MH OF Date Date (MG) (MG) /26/ /19/ /27/ /27/ /4/ /26/ /29/ /19/ /30/ /11/

37 Gray Improvement Level 2 Pipe Upsize deficient pipes to reach a 10 years LOS Pipe Size Required for LOS (ft) WQ RG Condition (LOS 2.1 Years) Level 2 Gray Pipe Pipe Pipe Pipe Pipe Rank Recurrence (Years) WQ Rain Gardens Gray Level 2 Date OF (MG) Date OF (MG) /26/ /27/ /27/ /19/ /4/ /29/ /19/ /30/ /11/

38 LOS, Years LOS versus Cost Comparison with Gray Flow LOS (yrs) versus Construction Cost (per ac) 7 6 Level 2 gray 5 4 Level 1 gray 3 Green Only 2 1 Existing Base RGWQ RGTL RGTL+BO RG & PP 0 $0 $20,000 $40,000 $60,000 $80,000 $100,000 $120,000 Construction Cost (per acre)

39 Pilot Area 2: Weisheimer Rd MH Flooding LOS: ~5 months

40 LOS, Years Chatham vs. Weisheimer 3.5 Flow LOS (yrs) versus Construction Cost (per ac) RG TL RG TL + BO RG + PP 2 RG WQ 1.5 Existing RG TL RG TL + BO RG + PP 1 Base 0.5 Existing Base RG WQ Chatham Weisheimer 0 $0 $20,000 $40,000 $60,000 $80,000 $100,000 $120,000 $140,000 $160,000 Construction Cost (per acre)

41 LOS, Years LOS, Years 7 Chatham Rd (cost per acre ) Existing Base RGWQ RGTL RGTL+ BO RG & PP $0 $20,000 $40,000 $60,000 $80,000 $100,000 $120,000 Existing Base Weisheimer Rd (cost per acre ) RGWQ RGTL RGTL + BO RG & PP $0 $20,000 $40,000 $60,000 $80,000 $100,000 $120,000 $140,000 $160,000

42 Conclusions RDII: Detailed modeling approach for RDII sources allowed for an educated understanding and quantifying RDII flows. This in turn allowed for a more effective RDII reduction plan. Stormwater: Detailed modeling approach allowed for an improved quantification of additional runoff due to reduction in RDII. It also improved evaluating the GI units to increase stormwater flooding protection level. Coordinating between both systems allowed for one integrated plan to: Reduce RDII, Improve water quality, Reduce flooding.

43 Thank You Phone: (614) Imagine the result