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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. Overview. Project Background SSES Objectives

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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

overview
Overview
  • Project Background
  • SSES Objectives
  • Private Property Evaluation Strategies
  • Private Property I/I Findings
  • SSES Alternatives Considered and Selected
e leonard heights study area
E. Leonard Heights Study Area

Sweet St.

Ball Ave.

Spencer St.

E. Leonard St.

Mayfield Ave.

Lewison Ave.

Carlton Ave.

project background
Project 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
project objectives
Project 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

Surface Runoff into storm drains and streams

70%

30%

Soaks Into Soil

Other

Sources

5% wastewater

95% stormwater

I/I

Stream baseflows,

grass & trees

Footing Drains

Where Does the Rain Go?

Storm Drain

Sanitary

Sewer

private property survey and inspection
Private 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 findings
Private Property Survey Findings
  • Footing Drains:
    • 516 properties have connected FDs
    • 66properties not connected (sump pumps)
    • Apartments = 21 equivalent FDs
  • Drainage:
    • Gutters and downspouts = 80%
    • Surface drainage = Mostly to street
sewer and manhole survey
Sewer 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 findings
Sewer 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 monitoring
Flow, 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
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)
alternative solutions
Alternative 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
selection matrix used to quantify preferences of citizens and city staff
Selection 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 fdd
Recommended 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 fdd
Benefits – 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 fdd
Concerns – 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
questions

Questions?

Jay Zawacki – CDM Michigan Inc.

[email protected]

(734) 205-2701

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