City of Elmhurst Comprehensive Flooding Plan December 5, 2011

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1 December 5, 2011 City of Elmhurst Comprehensive Flooding Plan December 5, 2011 Sanitary Sewer System Summary of Findings Prepared by CBBEL RJN Group

2 Sanitary Sewer Presentation Outline Where: Sources of infiltration / inflow Locations of homes with backups How: Options for reducing backups How Much: Costs for each option Relationship of costs to level of protection General / Operations Recommendations

3 Where? Clearwater Infiltration/Inflow Sources Basement Backup Locations

4 Clearwater Sources Into Sanitary Sewer Public Sector Manholes Main sewers Storm sewer cross connections Private Sector Interior sources - sump pumps and foundation drains Exterior sources - driveway, stairwell, patio, area drains, cleanouts Service laterals and service lateral correction to main sewer

5 Manhole Infiltration/Inflow Defects

6 Main Sewer Defects

7 Indirect Cross Connections

8 Clearwater Sources Into Sanitary Sewer Public Sector Manholes Main sewers Storm sewer cross connections Private Sector Interior sources - sump pumps and foundation drains Exterior sources - driveway, stairwell, patio, area drains, cleanouts Service laterals and service lateral connection to main sewer

9 Typical Sump Pump Configuration St S t Storm Sump to Sanitary Sewer

10 Typical Sump Pump Configuration C bi ti S Combination Sump to Sanitary Sewer

11 Typical Sump Pump Configuration Unsealed Sanitary Sump to Sanitary

12 Directly Connected Foundation Drain Private Public Cleanout Building Lateral Sanitary Sewer Main

13 Directly Connected Foundation Drain

14 Foundation Drain Video

15 Window Well Cleanouts / Area Drains / Downspouts

16 Window Well Stairway Cleanouts / Area Drains / Downspouts

17 Window Well Stairway Cleanout Cleanouts / Area Drains / Downspouts

18 Window Well Stairway Cleanout Downspouts Cleanouts / Area Drains / Downspouts

19 Window Well Stairway Cleanout Downspouts Driveway Drains Cleanouts / Area Drains / Downspouts

20 Leaking Service Laterals

21 Elmhurst Main Sewer Lining Program

22 Leaking Service Lateral Video

23 Summary of Data Sources Internal Building Infiltration/Inflow Sources 1987 Citywide inspection program City records of tear down homes City records of overhead sewer installations City records of property transfer inspections City Annual Sewer Lining Program Lift Station SCADA Records City s GIS Sanitary Sewer Database Manhole Rehabilitation Program 1988 Sanitary Relief Sewer Construction Plans Flood Questionnaires i Field Investigations

24 Summary of 2011 Field Investigations Flow Metering Manhole Inspection Smoke Testing Selective Basement and Sewer Elevation Survey

25 Spring 2011 Rainfall Summary

26 Significant Spring Rainstorms Date 2 Hour Rainfall Recurrence Interval April < 2 Month April < 2 Month May Month May Month June Month June < 2 Month

27 Flow Monitoring

28 Typical Flow Response to Rainfall Hydrograph ELM-M Late May Rain Events el (in.) ity (fps) Flow (mgd) Rainfall (in/hr) /26/2011 5/27/2011 5/28/2011 5/29/2011 5/30/2011 5/31/2011 6/1/2011 ADWF Rain Level Velocity Flow /25/2011 Leve Veloci

29 Typical Rainfall/Inflow Correlation Predicted Flow ELM-M Excess Flow () Excess Flow Predicted Flow 1-year storm 3-year storm 5-year storm Peak 2- Hour Rainfall (Inches)

30 Sample Manhole Inspection Spring 2011 Inspected 76 Manholes Locations Near Creek, with Main Sewer Lining, Various Ages Result Limited Defects 1987 Rehabilitation Work Still Generally Sound

31 Sample Smoke Testing Summer 2011

32 Sample Smoke Testing Summer 2011

33 Elevation Survey / Hydraulic Modeling Develop XP SWMM Hydraulic Model GPS Survey manhole elevations GPS Survey basement elevations

34 Flow Balancing

35 Infiltration/Inflow Defects Public Sector Source 1-Year Storm Average Flow - GPM Rehabilitation Cost Manholes $850 Storm Sewer $5,000 - $10,000 Cross- Connections Mainline Defects $8,000- $10,000

36 Infiltration/Inflow Defects Private Sector Source 1-Year Storm Average Rehabilitation Flow - GPM Cost Sump- Combined $5,000 Sump- Unsealed 7.0 $2,000 Sump - Suspect $750 Service lateral $5,000 Area Drains $5,000 Foundation Drain Up to $15,000 with Rear Yard Rain Garden

37 Typical Inflow Source Distribution in Illinois Private Sector = 50% Public Sector = 50%

38 Elmhurst Citywide Distribution in 1987 Private Sector = 63% Public Sector = 37%

39 Elmhurst Citywide Distribution in 2011 Private Sector = 93% Public Sector = 7%

40 Southwest Elmhurst Distribution in 2011 Private Sector = 93% Public Sector = 7%

41 Saylor & Jackson Pump Station (Basin 24) Private Sector Sources Private Source Number % Total Buildings Foundation Drains % Suspect Storm Sump Pump % Combination Sump Pump 66 10% Unsealed Sanitary Sump Pump 7 1% Total % Total Parcels in Basin

42 Where? Clearwater Infiltration/Inflow Sources Basement Backup Locations

43 Reported Sanitary Sewer Backups from 2010 Questionnaire

44 South Elmhurst Reported Sanitary Backups / Unspecified from Questionnaire Reported Number of Basement Backups Reported Number of Unspecified Sources % Total of Citywide Reported Unspecified Sources % Total of Citywide City Sewer Basin Reported Backups % % % % % % % % % % % % % % % % South Elmhurst Total % %

45 South Elmhurst - Reported Backups from Questionnaire Basin Total Homes Homes with reported Backups/Unspecified Percent of Ttl Total Homes % % 1.2% % % 9.4% % % % Total 5, %

46 Storm Events Recurrence Probability of Percent Chance Interval Years Occurrence Any Occurrence in Any Given Year Given Year 6 Months 2 in Year 1 in Year 1 in Year 1 in Year 1 in Year 1 in Year 1 in 100 1

47 Level of Protection Level B Level A Basement bottom elevation is above sanitary sewer (Level A) Basement backup can occur when sanitary sewer surcharges up to Level B If 10-year storm results in sanitary sewer surcharge to level B, then this house has 10 year storm protection Sanitary Sewer Vertical differences in Surcharge Level B versus Level A is surcharge that does not cause basement backup Sanitary Sewer

48 Sanitary Sewer Existing Level of Minimum Protection North Elmhurst

49 Sanitary Sewer Existing Level of Minimum Protection South Elmhurst

50 How? Relief Sewers and WWTP Expansion I/I Sources Removal Relief Sewers and Storage Individual Home Basement Backup Protection

51 Relief Sewers and WWTP Expansion Elmhurst WWTP Permit Has Maximum Flow Limit Recent Regulatory Activity by IEPA Makes Likelihood of Recent Regulatory Activity by IEPA Makes Likelihood of Expanding Peak Flow Capacity at WWTP Very Low

52 Level 1 Rehabilitation Sources Public Sector Manhole defects Mainline defects Mainline defects Cross connections with storm sewer Private Sector Sump pumps - combined, unsealed, suspects Driveway drains, cleanouts, area drains, downspouts

53 Level 1 Rehabilitation Percent Peak Flow Reduction Area Public Sector Private Sector Total Manholes/Cross Sump Pumps, - Connections Area Drains Citywide 13% 22% 35% South Elmhurst Basins % 22% 28%

54 Level 1 Rehabilitation - Level of Protection North Elmhurst

55 Level 1 Rehabilitation - Level of Protection South Elmhurst

56 How Much $ - Level 1 Rehabilitation Area Public Sector Private Sector Total Manholes/Cross Sump Pumps, - Connections Area Drains Citywide $2,510,000, $10,620,000, $13,130,000, South Elmhurst Basins ( 81% Total) $1,300,000 $5,650,000 (83 % Total) $6,780,000

57 Level 1 Rehabilitation Cost Distribution - Citywide

58 Level 1 Rehabilitation Cost Distribution - South Elmhurst

59 How? Relief Sewers and WWTP Expansion I/I Sources Removal Relief Sewers and Storage Individual Home Basement Backup Protection

60 Sanitary Sewer 10 Year Storm Protection Rehabilitation Level 1 Sources Public Sector Manhole Defects Mainline defects Cross Connections with Storm Sewer Private Sector Sump Pumps- Combined, Unsealed, Suspects Driveway drains, Cleanouts, Area Drains, Downspouts PLUS Selective Foundation Drains South Elmhurst Selective Overhead Sewers North Elmhurst

61 10 Year Storm Protection Rehabilitation South Elmhurst Basin % Flow Reduction Required Approx. Number of Foundation Drains required to Disconnect % of Total Foundation Drains Total 72 1,150 65

62 Overhead Sewers

63 Sanitary Sewer 10 Year Storm Protection - Rehabilitation Cost Summary Item Cost Level 1 Rehabilitation South Elmhurst Selective Foundation Drains- South Elmhurst (1,150 Total) Selective Overhead Sewers North Elmhurst (75 Total) $6,780,000 Up to $17,250,000 $750,000 Total $24,780,000 Private Property Cost (95% Total) $23,480,

64 How? Relief Sewers and WWTP Expansion I/I Sources Removal Relief Sewers and Storage Individual Home Basement Backup Protection

65 Sanitary Sewer 10 Year Storm Protection Relief and Storage Level 1 Rehabilitation South Elmhurst PLUS Overhead sewers in North Elmhurst Overhead sewers in South Elmhurst Basin 24 Saylor & Jackson Lift Station - Larger pumps at Saylor & Jackson Pump Station (Basin 24) - Extend existing Saylor & Jackson Force main outlet from Saylor & McKinley to the WWTP - New Dry weather force main west to Basin 23 Construct storage basin at WWTP (1.72 acre feet)

66 Sanitary Sewer 10 Year Storm Relief and Storage

67 Storage at WWTP Acre Feet

68 Sanitary Sewer 10 Year Storm Protection Relief and Storage Item Cost Level 1 Rehabilitation South Elmhurst $6,780,000 Saylor & Jackson LS- Upsize Pumps/Station Modifications - 5 MGD New Dry weather force main to west Extend existing Force main to WWTP - 18 $350,000 $260,000 $1,400, Storage Basin at WWTP (1.72 acre feet) $1,000,000 Overhead Sewers Up to North Elmhurst (75 total) $2,750,000 South Elmhurst (200 total) Total $12,540,000 Private Property Cost (67 % Total) $8,400,000

69 Sanitary Sewer 25 Year Storm Protection Relief and Storage Level 1 Rehabilitation South Elmhurst PLUS Overhead sewers in North Elmhurst Overhead sewers in South Elmhurst Basin 24 Saylor & Jackson Lift Station - Larger pumps at Saylor & Jackson Pump Station (Basin 24) - Extend existing Saylor & Jackson Force main outlet from Saylor & McKinley to the WWTP - New Dry weather force main west to Basin 23 - Upsize 1,500 feet of Jackson Street sewer to 24 upstream of lift station Construct storage basin at WWTP (3.8 acre feet)

70 Sanitary Sewer 25 Year Storm Relief and Storage

71 Storage at WWTP- 3.8 Acre Feet

72 Sanitary Sewer 25 Year Storm Protection Relief and Storage Item Cost Level 1 Rehabilitation South Elmhurst $6,780,000 Saylor & Jackson LS - Upsize Sewer into LS - 1,500 ft - 24 $470,000 Upsize Pumps/Station Modifications 6.5 MGD $400,000 New Dry Weather Force Main to West $260,000 Extend Existing Force Main to WWTP - 18 $1,400,000 Storage Basin at WWTP (3.8 acre feet) $1,900,000 Overhead Sewers North Elmhurst (100 total) South Elmhurst (525 total) Up to $6,250,000 Total $17,460,000 Private Property Cost (68 % Total) $11,900,000

73 July 2010 Storm Sanitary Sewer Protection Tunnel Storage

74 July 2010 Storm Protection Sanitary Sewer Tunnel Storage Volume = 75 Acre Feet Requires Multiple Drop Shafts from Sanitary Sewer to Tunnel Tunnel Volume Pumped Back to Gravity Sewers after Storm Flows Subside Estimated Cost = Greater than $150 Million

75 Sanitary Sewer - Summary of Levels of Protection Level of Protection Level 1 Rehabilitation 1 Year to 10 Year Area Dependent Cost $6,780, South Elmhurst 10 Year Storm Rehabilitation $24,780, Year Storm Relief + Storage $12,540, Year Storm Relief + Storage $17,460,000 > 100 Year Storm Deep Tunnel >$150,000,000

76 Additional Requirements for Sanitary Sewer System Item Lift Stations Atrium Force Main Replacement Saylor & Jackson Force Main Replacement SCADA Improvements Short-Term (Hardware, Software, Meters, Rain Gauges) Estimated Cost Budgeted Design Initiated Budgeted Design Initiated t $80,000 SCADA Improvements Long-Term $40,000 (Hardware, Software) General Electrical Upgrades $55,000

77 Item Sewer System Additional Requirements for Sanitary Sewer System Estimated Cost Permanent Flow Meters $50,000 Computerized Asset / Maintenance $50, Management System Internal Building Inspection South Elmhurst Manhole Inspection South Elmhurst Smoke Testing Balance of System Sewer Use Ordinance Revisions Complete prior to starting disconnect program Cost included in Level 1 Rehab Cost Complete prior to starting Level 1 Rehab Program Cost included in Level 1 Rehab Cost Multi-year Program $350,000 N/A