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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.

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Presentation on theme: "Evaluation of Private Property I/I Sources for Sanitary Sewer Evaluation Study City of Grand Rapids – E. Leonard Heights Area Presenter: Jay Zawacki, CDM."— Presentation transcript:

1 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

2 Overview Project Background SSES Objectives Private Property Evaluation Strategies Private Property I/I Findings SSES Alternatives Considered and Selected

3 E. Leonard Heights Study Area Sweet St. E. Leonard St. Ball Ave. Carlton Ave.Lewison Ave.Mayfield Ave. Spencer St.

4 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

5 Recent Concerns

6 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

7 Where Does the Rain Go? Stream baseflows, grass & trees I/I Footing Drains Other Sources 5% wastewater 95% stormwater Sanitary Sewer Storm Drain 30% Soaks Into Soil 70% Surface Runoff into storm drains and streams

8 Why Are Footing Drains Important?

9 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

10 Private Property Survey and Inspection

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13 Private 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

14 Private Property Survey Findings

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16 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

17 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

18 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

19 Flow, Rain and Sump Monitoring

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23 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)

24 Use of Monitoring Data in Model Development and Calibration

25 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

26 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

27 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 500,000 gallons at the school

28 Solution 3 – Footing Drain Disconnection Remove footing drain flows from homes to eliminate surcharging Sump pumps used to route footing drain flow to the storm drains Surcharging eliminated by disconnecting at least 60% of the connected homes

29 Alternative Cost Comparison

30 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

31 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

32 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

33 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

34 Questions? Jay Zawacki – CDM Michigan Inc. (734)


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