Transcript Module 2

NASHVILLE’S PROGRAM REMOVES
3.6 BILLION GALLONS OF I/I
George Kurz, P.E., DEE
615-252-4441 [email protected]
Gregory Ballard, P.E. (Metro Nashville)
Paul Stonecipher, P.E. *
* A significant portion of this work was conducted with CTE-AECOM as part of the Nashville
Overflow Abatement Program 1991-2005
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Master Sewer Growth Plan
OBJECTIVE of Metro’s Project
Demonstrate the significant, positive
value and effectiveness of trenchless
sewer rehabilitation for infrastructure
renewal and environmental
protection.
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I/I & SSO ALTERNATIVES
• BIGGER IS BETTER
(Increase Plant and System Capacity)
• REHABILITATE AND RECAPTURE
(Goal in Nashville is 50% Reduction)
• MIX OF REHAB, EQUALIZATION, ADDITIONAL
CAPACITY
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1970’s Legacy
• LEAK – BY – LEAK APPROACH
(or find-and-fix)
–MANY DEFECTS NOT ADDRESSED
–ESTIMATED VOLUME BASED ON
“SNAPSHOT”
–FLOW “MIGRATION” IGNORED
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GROUNDWATER MIGRATION
ACTIVATES NEW LEAKS
"DRY" DEFECT
(POTENTIAL LEAK)
LEAK
LEAK
REPAIR
5
FIX THE PROBLEM –
DON’T BAND-AID THE SYMPTOM
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Now: “COST-EFFECTIVE”
REHABILITATION
• SYSTEM APPROACH
– ACCOUNTS FOR MIGRATION
– VOLUME MEASURED
– FLOWS PROJECTED TO DESIGN
EVENT
– MULTIPLE RAINFALL EVENTS
– WET & DRY WEATHER
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MEASURES OF EFFECTIVENESS
• Reduction of I/I
• Reduction of Overflows
(and concurrent water quality
improvement)
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NATIONAL TRENDS
WERF - study of trends of I/I reduction in
44 utilities:
“Unfortunately, none of the
information between projects was
comparable . . .”
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OTHER MAJOR PROGRAMS
PROGRAM
Miami-Dade
Atlanta
SYSTEM FLOW
REHAB
I/I REDUCTION
(miles)
(mgd)
(miles)
(% or mgd)
3,600
320 (W)
152 mgd
1,600 s
139 E
Birmingham_Jeff
Co
3,000
176 W
Jacksonville, FL
3,200
125 W
296
Nashville
2,518
123.7
295
W - Web,, s - separate, E - EPA DMR 200506
180
5 mgd E
~9.9mgd
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LACK OF INFORMATION
• Holds our industry back
• Discourages investment in
infrastructure renewal
• Hinders environmental
improvements
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SUCCESSFUL TRENCHLESS
REHABILITATION
• Based on actual field results in Nashville, TN
• Largest published database for measured I/I
reduction in the US
• Analyzed 94 miles of rehabilitation (295 miles
total - ~ 12% system)
• I/I cut in half
• 123 overflows eliminated
• EPA commends stream improvements
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RESULTS IN NASHVILLE
• 27 Areas Analyzed
• 94 Miles Rehabilitated
• 50 % + I/I Reduction
• 1/3 + of Total Work in Nashville
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BEFORE-AFTER PROJECT EVALUATION
5-YEAR, 24-HOUR I/I REDUCTION (CU-01 1999-2002)
5.0
4.5
50%
Reduction
24-hour I/I (m g)
4.0
CAPACITY
3.5
3.0
I/I REDUCTION
BEFORE REHAB
2.5
2.0
1.5
AFTER REHAB
1.0
0.5
0.0
0
0.5
1
1.5
2
2.5
24-hour rainfall (in.)
3
3.5
4
4.5
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I/I Before Rehab
I/I After Rehab
Linear (I/I Capacity)
NASHVILLE MEASURED RESULTS
For the 27 areas (94 miles) analyzed so far:
3.6 billion gallons I/I eliminated annually
49.6%
Annual I/I eliminated
53%
24-hour, 5-year I/I reduction
52.2%
Peak-hour, 5-year I/I reduction
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Annual Duration of Rainfall Induced
Bleeder and Manhole SSOs
Nashville, Tennessee
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60
59
55
59 60
57
10
49
49
47
49
41
44
8
50
52
42
40
40
6
30
4
20
2
10
0
0
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
Year
Overflow Duration
Linear (Overflow Duration)
Annual Rainfall (in)
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Annual Rainfall (in)
Annual Duration (103 hrs)
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Nashville Overflow Abatement Program
157 Potential SSO Locations Identified Since 1990
Active
Overflow =
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Nashville Overflow Abatement Program
34 Active Overflows & Watch list Locations (As of January 2005)
Active
Overflow =
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Governor’s Ceremony 11-25-2002
Graphic Courtesy of Tennessee Department of
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Environment and Conservation
EPA & Governor’s Deposting Ceremony
November 2002
33 miles “deposted”
Many segments
on 303d list
removed or no
longer attributed
to collection
system failure
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STANDARDIZED APPROACH
(summary highlights)
• DESIGN STORM (e.g. 5-YEAR, 24-HOUR EVENT)
• STATISTICAL CRITERIA FOR QA/QC
• DEFINE RAINFALL EVENT (e.g. 10 HRS DRY PREV.)
• USE MAXIMUM NUMBER OF EVENTS IN PERIOD
• MINIMIZE ANALYST BIAS (SELECTIVITY)
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STANDARDIZED DESIGN
TOTAL SYSTEM APPROACH
GOAL: “CONTAINMENT” FOR FLOWS FROM 5YEAR, 24-HOUR RAINFALL
POLICY:
ALL SERVICE LATERALS CONNECTED TO THE
REHABILITATED PIPES WILL BE RENEWED TO
THE EASEMENT LINE OR THE PROPERTY LINE

ALL MANHOLES CONNECTED TO
REHABILITATED PIPES WILL BE RENEWED

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REHABILITATION IS ASSUMED TO
ONLY APPLY TO A FRACTION OF
THE SYSTEM
SO:
We must have a way to identify and
select the appropriate – failing parts
of the system for rehabilitation.
*** Random “Find & Fix” until “enough” I/I has 23
been removed is not a STRATEGY ! ***
Strategy for Application of
Products is as Important as
Product Quality
• Product Effectiveness is Equal (no leaks where
applied)
• Therefore: Concentrate Effort to Defeat Migration
• Dry Defects on Video May be Wet Weather Leaks
• Some Defects May Not be Visible on Video
• Pipe Segments: “Connect-the-Dots”
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FLOW MONITORING IS A
KEY TOOL
•
•
•
•
Target and prioritize basins
Correctly interpret hydraulic conditions
Conduct model calibration
Monitor post-rehabilitation to verify
project effectiveness
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SYSTEM APPROACH
• ACCOUNTS FOR MIGRATION
• VOLUME MEASURED
• FLOWS PROJECTED TO DESIGN
EVENT
• MULTIPLE RAINFALL EVENTS
• WET & DRY WEATHER
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SUCCESSFUL REHAB
FACTORS
• EXTENSIVE FLOW MONITORING
• LATERAL RENEWAL TO EASEMENT
• “TARGETING” - LINING SELECTED BY
OBSERVED DEFECTS, AGE, PROXIMITY,
MIGRATION POTENTIAL, SURFACE
WATER
• PERFORMANCE (AIR) TEST LINE &
LATERAL
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Total System: Pick Priority Area
WORK ON THE TOP
PRIORITY AREA -
2
3
1
4
5
- AND
KNOCK IT
OUT !!!!
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STRATEGIC GOALS MET
• I/I REDUCTION
• SSO REDUCTION
• STREAM IMPROVEMENT
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Small City Example
• Population ~400
• Treatment capacity 150,000 gpd
• CDBG Rehabilitation Project
• Sewer line slip lining
• Manhole repair
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Small City Example
Flow and Trend
0.2
Average Flow
+2000gpm
Capacity
+200gpm
0.1
0.05
Date
9/06
5/06
1/06
9/05
5/05
1/05
9/04
5/04
1/04
9/03
5/03
1/03
9/02
5/02
0
1/02
Flow MGD
0.15
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Bell Buckle Daily Influent Flow
0.3
10
Design flow = 0.15 mgd
Base flow = 0.030 mgd
(6/12-18/2006)
0.25
9
8
Flow (mgd)
6
0.15
5
4
0.1
3
2
0.05
1
0
1-Sep-05
0
31-Oct-05
30-Dec-05
28-Feb-06
Date
29-Apr-06
28-Jun-06
27-Aug-06
26-Oct-06
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Rain
Day Flow
24-hr Rain (in)
7
0.2
ANALYSIS OF DAILY PLANT FLOWS
(Sep 2005 – Nov 2006)
0.0687 average plant flow (gross average of all days)
31.335 Total plant flow in period
ADF - Base Flow (average of 7 lowest
0.0301 consecutive days)
I/I in period (Total flow minus base flow for
17.590 period)
0.295 I/I per inch rain (I/I divided by period rainfall)
normalized I/I per year (I/I for 365 days for annual
13.934 average rain)
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Bell Buckle Rainfall Dependent I/I Flow (Sep '05 - Nov '06)
Better
0.25
0.2
2nd day Incremental flow increase (mgd)
Estimate of RDII using
cumulative rainfall and
incremental increase of
influent flow – more
realistic projection of I/I
and has better correlation
factor
0.15
y = 0.0474x + 0.0058
R2 = 0.4432
0.1
0.05
0
0
0.5
1
1.5
2
2.5
3
Cumulative 2nd day Rain (in)
3.5
4
RDII
Bell Buckle Influent Flow (Sep '05 - Nov '06)
0.3
Typical
0.25
Plot of daily flow related to
daily rainfall – poor correlation
factor
Flow (mgd)
0.2
0.15
0.1
y = 0.0297x + 0.057
R2 = 0.2037
0.05
0
0
0.5
1
1.5
2
2.5
24-hr Rain (in)
3
3.5
4
Influent flow
4.5
5
Linear (Influent flow )
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4.5
Linear (RDII)
Module #2
Exercise
• What are your:
»Challenges
»Obstacles
»Barriers
to reducing I/ I?
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