December 5, 2011 City of Elmhurst Comprehensive Flooding Plan December 5, 2011 Sanitary Sewer System Summary of Findings Prepared by CBBEL RJN Group
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
Where? Clearwater Infiltration/Inflow Sources Basement Backup Locations
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
Manhole Infiltration/Inflow Defects
Main Sewer Defects
Indirect Cross Connections
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
Typical Sump Pump Configuration St S t Storm Sump to Sanitary Sewer
Typical Sump Pump Configuration C bi ti S Combination Sump to Sanitary Sewer
Typical Sump Pump Configuration Unsealed Sanitary Sump to Sanitary
Directly Connected Foundation Drain Private Public Cleanout Building Lateral Sanitary Sewer Main
Directly Connected Foundation Drain
Foundation Drain Video
Window Well Cleanouts / Area Drains / Downspouts
Window Well Stairway Cleanouts / Area Drains / Downspouts
Window Well Stairway Cleanout Cleanouts / Area Drains / Downspouts
Window Well Stairway Cleanout Downspouts Cleanouts / Area Drains / Downspouts
Window Well Stairway Cleanout Downspouts Driveway Drains Cleanouts / Area Drains / Downspouts
Leaking Service Laterals
Elmhurst Main Sewer Lining Program
Leaking Service Lateral Video
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 1988 500 Flood Questionnaires i 2011 2011 Field Investigations
Summary of 2011 Field Investigations Flow Metering Manhole Inspection Smoke Testing Selective Basement and Sewer Elevation Survey
Spring 2011 Rainfall Summary
Significant Spring Rainstorms Date 2 Hour Rainfall Recurrence Interval April 8 034 0.34 < 2 Month April 19 0.73 < 2 Month May 25 1.24 6 Month May 29 102 1.02 3 Month June 9 1.13 4 Month June 15 0.39 < 2 Month
Flow Monitoring
50 45 40 35 30 25 Typical Flow Response to Rainfall Hydrograph ELM-M Late May Rain Events 4.0 3.6 3.2 2.8 2.4 2.0 el (in.) ity (fps) Flow (mgd) Rainfall (in/hr) 20 15 10 5 0 1.6 1.2 0.8 5/26/2011 5/27/2011 5/28/2011 5/29/2011 5/30/2011 5/31/2011 6/1/2011 ADWF Rain Level Velocity Flow 0.4 0.0 5/25/2011 Leve Veloci
Typical Rainfall/Inflow Correlation Predicted Flow ELM-M 100.00 10.00 Excess Flow () 1.00 0.10 Excess Flow Predicted Flow 1-year storm 3-year storm 5-year storm 0.01 0.10 1.00 10.00 Peak 2- Hour Rainfall (Inches)
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
Sample Smoke Testing Summer 2011
Sample Smoke Testing Summer 2011
Elevation Survey / Hydraulic Modeling Develop XP SWMM Hydraulic Model GPS Survey manhole elevations GPS Survey basement elevations
Flow Balancing
Infiltration/Inflow Defects Public Sector Source 1-Year Storm Average Flow - GPM Rehabilitation Cost Manholes 0.4 0.6 $850 Storm Sewer 1.0 10.0 $5,000 - $10,000 Cross- Connections Mainline Defects 1.0 2.0 $8,000- $10,000
Infiltration/Inflow Defects Private Sector Source 1-Year Storm Average Rehabilitation Flow - GPM Cost Sump- Combined 70 7.0 $5,000 Sump- Unsealed 7.0 $2,000 Sump - Suspect 70 7.0 $750 Service lateral 1.0 3.0 $5,000 Area Drains 1.0 10.0 $5,000 Foundation Drain 70 7.0 Up to $15,000 with Rear Yard Rain Garden
Typical Inflow Source Distribution in Illinois Private Sector = 50% Public Sector = 50%
Elmhurst Citywide Distribution in 1987 Private Sector = 63% Public Sector = 37%
Elmhurst Citywide Distribution in 2011 Private Sector = 93% Public Sector = 7%
Southwest Elmhurst Distribution in 2011 Private Sector = 93% Public Sector = 7%
Saylor & Jackson Pump Station (Basin 24) Private Sector Sources Private Source Number % Total Buildings Foundation Drains 231 34% Suspect Storm Sump Pump 152 22% Combination Sump Pump 66 10% Unsealed Sanitary Sump Pump 7 1% Total 456 67% Total Parcels in Basin 24 681
Where? Clearwater Infiltration/Inflow Sources Basement Backup Locations
Reported Sanitary Sewer Backups from 2010 Questionnaire
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 20 15 8.20% 12 6.63% 21 5 2.73% 4 2.21% 22 3 1.64% 10 5.52% 23 32 17.49% 40 22.10% 24 77 42.08% 80 44.20% 25 3 1.64% 5 2.76% 26 9 4.92% 12 6.63% 27 0 0.00% 3 1.66% South Elmhurst Total 144 78.70% 166 91.71%
South Elmhurst - Reported Backups from Questionnaire Basin Total Homes Homes with reported Backups/Unspecified Percent of Ttl Total Homes 20 982 27 2.7% 21 733 9 12% 1.2% 22 808 13 1.6% 23 769 72 94% 9.4% 24 681 157 23.0% 25 713 8 1.1% 26 562 21 3.3% Total 5,248 307 5.8%
Storm Events Recurrence Probability of Percent Chance Interval Years Occurrence Any Occurrence in Any Given Year Given Year 6 Months 2 in 1 200 1 Year 1 in 1 100 2 Year 1 in 2 50 5 Year 1 in 5 20 10 Year 1 in 10 10 25 Year 1 in 25 4 100 Year 1 in 100 1
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
Sanitary Sewer Existing Level of Minimum Protection North Elmhurst
Sanitary Sewer Existing Level of Minimum Protection South Elmhurst
How? Relief Sewers and WWTP Expansion I/I Sources Removal Relief Sewers and Storage Individual Home Basement Backup Protection
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
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
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 18-26 6% 22% 28%
Level 1 Rehabilitation - Level of Protection North Elmhurst
Level 1 Rehabilitation - Level of Protection South Elmhurst
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 18-26 ( 81% Total) $1,300,000 $5,650,000 (83 % Total) $6,780,000
Level 1 Rehabilitation Cost Distribution - Citywide
Level 1 Rehabilitation Cost Distribution - South Elmhurst
How? Relief Sewers and WWTP Expansion I/I Sources Removal Relief Sewers and Storage Individual Home Basement Backup Protection
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
10 Year Storm Protection Rehabilitation South Elmhurst Basin % Flow Reduction Required Approx. Number of Foundation Drains required to Disconnect % of Total Foundation Drains 18 75 210 69 19 75 70 78 20 70 260 65 21 75 175 70 22 75 135 69 23 70 55 39 24 70 150 62 25 50 15 21 26 70 80 55 Total 72 1,150 65
Overhead Sewers
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) $23,480,000 000
How? Relief Sewers and WWTP Expansion I/I Sources Removal Relief Sewers and Storage Individual Home Basement Backup Protection
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)
Sanitary Sewer 10 Year Storm Relief and Storage
Storage at WWTP- 1.72 Acre Feet
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 $1,400,000 000 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
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)
Sanitary Sewer 25 Year Storm Relief and Storage
Storage at WWTP- 3.8 Acre Feet
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
July 2010 Storm Sanitary Sewer Protection Tunnel Storage
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
Sanitary Sewer - Summary of Levels of Protection Level of Protection Level 1 Rehabilitation 1 Year to 10 Year Area Dependent Cost $6,780,000 000 South Elmhurst 10 Year Storm Rehabilitation $24,780,000 10 Year Storm Relief + Storage $12,540,000 25 Year Storm Relief + Storage $17,460,000 > 100 Year Storm Deep Tunnel >$150,000,000
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
Item Sewer System Additional Requirements for Sanitary Sewer System Estimated Cost Permanent Flow Meters $50,000 Computerized Asset / Maintenance $50,000 000 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