Evaluation of private property i i sources for sanitary sewer evaluation study
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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

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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

  • Private Property Evaluation Strategies

  • Private Property I/I Findings

  • SSES Alternatives Considered and Selected


E. Leonard Heights Study Area

Sweet St.

Ball Ave.

Spencer St.

E. Leonard St.

Mayfield Ave.

Lewison Ave.

Carlton Ave.


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


Recent Concerns


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


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


Why Are Footing Drains Important?


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 and Inspection


Private Property Survey and Inspection


Private Property Survey and Inspection


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


Private Property Survey Findings


Private Property Survey Findings


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

  • 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

  • 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 Monitoring


Flow, Rain and Sump Monitoring


Flow, Rain and Sump Monitoring


Flow, Rain and Sump Monitoring


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 Calibration


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)

  • 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

  • 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

  • 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 Comparison


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

  • 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

  • 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

  • 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?

Jay Zawacki – CDM Michigan Inc.

[email protected]

(734) 205-2701


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