evaluation of private property i/i sources for sanitary sewer evaluation study city of grand rapids...
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Evaluation of Private Property I/I Sources for Sanitary Sewer Evaluation Study
Evaluation of Private Property I/I Sources for Sanitary Sewer Evaluation Study
City of Grand Rapids – E. Leonard Heights Area
Presenter: Jay Zawacki, CDM Michigan Inc.
MI AWWA / MWEA Annual Conference
August 13, 2010
City of Grand Rapids – E. Leonard Heights Area
Presenter: Jay Zawacki, CDM Michigan Inc.
MI AWWA / MWEA Annual Conference
August 13, 2010
OverviewOverview
Project Background
SSES Objectives
Private Property Evaluation Strategies
Private Property I/I Findings
SSES Alternatives Considered and Selected
E. Leonard Heights Study AreaE. Leonard Heights Study Area
Sweet St.
E. Leonard St.
Bal
l Ave
.
Car
lton
Ave
.
Lew
ison
Ave
.
May
field
Ave
.
Spencer St.
Project BackgroundProject Background
History of chronic basement backups in the study area
Grand Rapids recognized and began program to address these issues:
– Inspections of homes
– Voluntary installation of check valves and sump pumps
Comprehensive “system-wide” evaluation being performed
Recent ConcernsRecent Concerns
Project ObjectivesProject Objectives
Engage the public
– Public meetings
– Citizen committee
Quantify the sources of Inflow/Infiltration (I/I)
– Homeowner survey and inspections
– Sewer flow and sump pump monitoring
– Inspect the sewers and manholes
Analyze the problem and develop alternatives
Select the best solution
Where Does the Rain Go?Where Does the Rain Go?
Stream baseflows,grass & trees
I/I
Footing Drains
OtherSources 5% wastewater
95% stormwater
SanitarySewer
Storm Drain
30%
Soaks Into Soil
70%
Surface Runoff into storm drains and streams
Why Are Footing Drains Important?Why Are Footing Drains Important?
Private Property Survey and InspectionPrivate Property Survey and Inspection
Exterior Survey:
– Evaluated site drainage
– Identified downspout discharge locations
– Determined basement type/depth
Interior Survey:
– Backup history
– Presence of footing drains & sump pump
Private Property Survey and InspectionPrivate Property Survey and Inspection
Private Property Survey and InspectionPrivate Property Survey and Inspection
Private Property Survey and InspectionPrivate Property Survey and Inspection
Private Property Survey FindingsPrivate Property Survey Findings
Footing Drains:
– 516 properties have connected FDs
– 66 properties not connected (sump pumps)
– Apartments = 21 equivalent FDs
Drainage:
– Gutters and downspouts = 80%
– Surface drainage = Mostly to street
Private Property Survey FindingsPrivate Property Survey Findings
Private Property Survey FindingsPrivate Property Survey Findings
Sewer and Manhole SurveySewer and Manhole Survey
Evaluated I/I conditions at each sewer manhole
Reviewed I/I conditions of sewer pipes using video inspection and PACP coding
Determined material and condition of selected house lateral connections
Sewer and Manhole Survey FindingsSewer and Manhole Survey Findings
Sewers in good shape
Some structural and maintenance issues found, provided to city for correction
Some evidence of limited infiltration at pipe joints
House lead inspections identified no substantial I/I sources
Street flooding can cause significant flow into manhole covers
Flow, Rain and Sump MonitoringFlow, Rain and Sump Monitoring
Monitor sewer flows (4-months)
– Wastewater levels and flows during storms
– Establish sewer capacity
Measure rainfall in area
Monitor sump pump flows
– 15 homes monitored
– Understand local peak flows
Flow, Rain and Sump MonitoringFlow, Rain and Sump Monitoring
Flow, Rain and Sump MonitoringFlow, Rain and Sump Monitoring
Flow, Rain and Sump MonitoringFlow, Rain and Sump Monitoring
Flow, Rain and Sump MonitoringFlow, Rain and Sump Monitoring
Monitoring Findings Monitoring Findings
Sanitary sewer system capacity not sufficient for flows generated during large storms
Footing drain connections on private property are major source of I/I (flow into sewer during rain storms)
Use of Monitoring Data in Model Development and CalibrationUse of Monitoring Data in Model Development and Calibration
Alternative SolutionsAlternative Solutions
Solution 1 – Relief Sewers
– Internal relief sewer to west of Spencer Street
– Downstream relief (if needed) to Plainfield Avenue
Solution 2 – Local Relief and Storage
– Internal relief to underground storage facility
– Storage located west of Spencer Street
Solution 3 – Footing Drain Disconnection (FDD)
– Sufficient FDD to eliminate surcharging
Solution 1 – Sewer Upsizing (Relief)Solution 1 – Sewer Upsizing (Relief)
Relief provided to eliminate surcharging
Relief requirements:
– ELH area: 10 relief sewer segments
– Downstream: 31 relief sewer segments
– WWTP storage
Solution 2 – Sewer Upsizing and Local Storage
Solution 2 – Sewer Upsizing and Local Storage
Relief sanitary sewers provided to eliminate surcharging
Local storage provided west of Spencer Street
System requirements:
– Build 10 relief sewer segments in ELH
– Store 500,000gallons at the school
Solution 3 – Footing Drain Disconnection
Solution 3 – Footing Drain Disconnection
Remove footing drain flows from homes to eliminate surcharging
Sump pumps used to route footing drain flowto the storm drains
Surcharging eliminatedby disconnecting at least 60% of the connected homes
Alternative Cost ComparisonAlternative Cost Comparison
Selection Matrix used to Quantify Preferences of Citizens and City StaffSelection Matrix used to Quantify Preferences of Citizens and City Staff
Quality of Life
Level of protection for private property
Reliability under large storms
Sustainability of solution
Costs (Construction, O&M, homeowner costs)
Construction
Time until solution is effective
Impacts on streets and public areas
Need to work on private property
Recommended Solution – FDDRecommended Solution – FDD
Perform minimum of 310 FDDs in E. Leonard Heights neighborhood
Consider backup sump pump in each home
Include backup check valve for homes previously flooded or at risk for flooding
Provide manhole liners for street flooding areas
All sump pumps will discharge to storm system to eliminate freezing problems in winter
Program is mandatory
Benefits – FDDBenefits – FDD
Addresses root cause of excessive I/I (Green solution)
Can be implemented more quickly than other options
Lower costs for treatment and no additional storage required at WWTP
Least impact on rate payers
Brings older homes into compliance with existing plumbing codes
Concerns – FDDConcerns – FDD Water in basement during power outage:
– Evaluating legal implications of providing backup sump pumps for all FDD homes
Sump pump replacement cost:
– Pumps typically last 5-10 years before replacement needed
Increased street flooding:
– Flows from sump pumps could increase street flooding levels by an average of 1/8”
– Could upgrade upstream stormwater storage to address additional sump pump flow
