HomeMy WebLinkAbout2. 2014-2015 Combined Sewer System Evaluation StudyMount Prospect
Mount Prospect Public Works Department
n/ INTEROFFICE MEMORANDUM
TO: ACTING VILLAGE MANAGER DAVID STRAHL
FROM: DIRECTOR OF PUBLIC WORKS
DATE: AUGUST 6, 2015
SUBJ: 2015 COMBINED SEWER SYSTEM EVALUATION STUDY
BACKGROUND
In 2004, the village conducted a combined sewer system evaluation study (CSSES). This study
was performed by consulting engineer, Baxter & Woodman of Crystal Lake, Illinois. It identified
almost $15 million worth of combined sewer repair work including manhole rehabilitation, pipe
replacements and pipe lining. 260,000 feet of combined sewer pipe was assessed during this
project. Repair work was further prioritized and categorized as follows:
• Approximately 8% of the pipes were in severe structural condition (Grade 5). The report
recommended that repairs be completed within one (1) to two (2) years. The estimated
cost to repair sewers in this classification was $2,481,600.
• 10% were in poor structural condition (Grade 4). Completed repairs were recommended
within the next three (3) to four (4) years. The estimated repair cost for sewers in this
classification was $2,548,000.
• 20% had moderate structural defects (Grade 3) requiring rehabilitation within the next
five (5) to ten (10) years. The estimated repair cost for sewers in this classification was
$5,240,000.
• 34% had minor structural defects (Grade 2) that did not require repairs. However, the
report recommended these pipes should be periodically re-examined to assure that
noted defects do not worsen. The estimated cost to repair these defects was
$4,158,000.
• 24% were in very good condition (Grade 1). No discernable defects were observed. No
repairs were recommended.
To date, the bulk of the major defects (all of Grades 5 and 4, with a portion of Grade 3) have
been corrected. The remaining pipe was identified in 2004 as being of low to moderate risk
(Grades 1 to 3).
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2015 Combined Sewer System Evaluation Study
August 7, 2015
The funding mechanism for combined sewer rehabilitation work has been a $5 per month
charge to each water/sewer customer; generating approximately $800,000 per year. This fee
was initiated in 2006 and is set to expire in 2016.
On August 5, 2014, the Village Board awarded a sewer televising contract to Visu-Sewer Illinois,
LLC of Bridgeview, Illinois in the amount of $404,706.67. The purpose of this project was to
gather observations necessary to assess the current condition of unimproved combined sewers.
Televising work included 190,600 lineal feet of unimproved combined sewers that were initially
ranked in the lower risk categories (Grades 3, 2 and 1). It also included a quality control
examination of approximately 10% of the combined sanitary sewer segments that have been
lined since 2006.
On October 7, 2014, the Village Board awarded an engineering contract to Baxter & Woodman
to re -assess the condition of sewers televised by Visu-Sewer. This award was in a not -to -
exceed amount of $112,400.
Baxter & Woodman utilized the Pipeline Assessment Certification Program (PACP) protocols to
assess and codify observed defects. The PACP protocols are a national standard developed
by the National Association of Sewer Service Companies (NASSCO). The Metropolitan Water
Reclamation District of Greater Chicago (MWRDGC) recently required all sewer pipe
assessment to be performed in accordance with this standard.
Although PACP terminology differs from the nomenclature utilized in the 2004 combined sewer
study; the prevailing logic is similar. Consequently, there is a high degree of correlation
between the two reports (a Grade 4 sewer in the 2015 study looks like a Grade 4 sewer in the
2004 study).
This memorandum transmits an abridged version of Baxter & Woodman's 2015 Combined
Sewer Televising Condition Assessment final report. The complete report, including
appendices, can be found on the Village's website (www.mountprospect.org).
DISCUSSION
Baxter & Woodman evaluated over 500 hours of sewer main inspection video (approximately
209,000 feet of sewer mains). They identified $15,460,000 worth of sewer repairs. Most pipe
can be repaired utilizing cured -in -place -pipe (CIPP) technology. Very few segements require
complete pipe removal and replacement.
Generally, about one-third of the sewers categorized as Grade 1, 2, or 3 in the 2004 combined
sewer study have degraded to Grade 4 or 5 sewers.
More specifically, 12% of the sewers televised fall into the Grade 5 category ($3,337,000), 20%
fall into Grade 4 ($4,562,000), and 22% are Grade 3 (7,561,000).
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2015 Combined Sewer System Evaluation Study
August 7, 2015
Additionally, 11 % were Grade 2 and 35% were Grade 1 or Grade 0. Grade 2 sewers do not
require work at this time but continued monitoring is recommended. Grade 1 and 0 pipes are in
good or very good condition and do not require any repairs.
None of the previously lined sewers inspected (18,000 feet) displayed any defects and all were
in good condition.
The continued degradation of sewers is anticipated. Generally, sewers pipes have a 50 -year
design life. Most of the Village's combined sewer system was installed between the 1920s and
1950s. As such, all of the these pipes are over 50 years old and some are approaching 90
years of service.
RECOMMENDATION
Staff recommends continued accelerated rehabilitation of sewer pipes in the combined sewer
area at a pace of $800,000 - $1,000,000 per year.
However, a key component to funding this level of sewer rehabilitation is the Sewer
Infrastructure Fee ($5/month per sewer service line). As noted previously, this fee generates
approximately $800,000 in revenue and is slated to sunset in 2016. Continued accelerated
combined sewer rehabilitation without this funding source does not seem feasible given other
capital and operating demands on the existing water/sewer user rate structure.
Staff seeks direction from the Village Board regarding the disposition of the Sewer Infrastructure
Fee.
Please present this matter for the Village Board's consideration at the August 11, 2015
Committee of the Whole meeting. Appropriate staff, along with a representative from Baxter &
Woodman will be available to present the report and facilitate discussion.
Sean P. Dorsey
CC: Deputy Director of Public Works Jason Leib
Water/Sewer Superintendent Matt Overeem
Administrative Superintendent Kristina Jakupovic
C:\Users\sdorsey\Desktop\2015 CSSES FINAL REPORT TRANSMITTAL.docx