Transcript E. Leonard Heights 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
 Project Background
 SSES Objectives
 Private Property Evaluation Strategies
 Private Property I/I Findings
 SSES Alternatives Considered and Selected
E. Leonard Heights Study Area
Ball Ave.
Sweet St.
Mayfield Ave.
Lewison Ave.
Carlton Ave.
Spencer St.
E. Leonard St.
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
Where Does the Rain Go?
Surface
Runoff into
storm
drains and
streams
70%
30%
Soaks Into Soil
I/I
Storm
Drain
Stream
baseflows,
grass & trees
Other
Sources
5% wastewater
95% stormwater
Sanitary
Sewer
Footing
Drains
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
– 66 properties 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 500,000
gallons at the school
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
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