Wastewater Enterprise
525 Golden Gate Avenue, 13th Floor
San Francisco, CA 94102
T 415.554.3155
F 415.554.3161
TTY 415.554.3488
FY21-22 Sewer Inspection and Replacement Program
Annual Summary
Introduction
The Wastewater Enterprise (WWE) owns, operates, and maintains approximately 800 miles of sewer mains equal to or smaller than 36” diameter (small diameter gravity sewers). These gravity sewers convey both dry weather wastewater flows and combined sewage (wastewater and stormwater) during wet weather. In addition, WWE replaces sewer service laterals with structural deficiencies located on the pipe portion extending from face of curb to the sewer main (sewer lateral). There are approximately 160,000 sewer laterals. The SFPUC Commission has previously established a goal of awarding a rolling average of approximately 15 miles per year of renewal or replacement (R&R) of small diameter gravity sewers. Laterals do not have a specific annual R&R target, however these are inspected and replaced as needed during construction of the sewer main R&R projects, with about 35% of existing laterals encountered typically requiring replacement. This report summarizes progress for FY21-22 period including condition assessment (cleaning, inspection, and coding), renewal, and replacement of small diameter gravity sewers and laterals.
Renewal & Replacement Bu dget
The WWE Collection System R&R Program has a capital budget of $112.2M for FY21-22, summarized by major activity as shown in Table 1. These activities include condition assessment, renewal, and replacement of sewer mains, and similar actions for sewer laterals. The Sewer Improvements (R&R) budget in FY 21-22 of $81.2M is funding a sewer main award target of 13.5-mile, slightly lower than the 15-mile target. The reduced 13.5-mile target is due to a 10% decrease to the original FY 21-22 Sewer Improvements (R&R) budget.
Table 1: FY21-22 Collection System R&R Program Capital Budget Sewer Improvements (R&R) – Small Diameter $81,228,000
Condition Assessment – Sewer Mains $3,940,000
Condition Assessment – Sewer Laterals $520,000
Spot Sewer Repair Program $26,476,000
Total $112,164,000
The program maintains the existing functionality of the sewage collection system and includes planned and emergency repairs and replacement of structurally deficient sewers. Individual projects vary from less than one and up to three miles typically and are most often completed as part of inter-departmental capital projects such as the recent SFPW 19th
Avenue and SFMTA 16th Street corridor projects, and as part of the SF Public Works paving program. Actual mileage awarded and completed in any single FY will vary based on the timing for initiation and construction for joint projects and the variability of bid results that may limit awarded mileage under the FY budget.
WWE is shifting focus to utilize more trenchless construction methods for sewer main and lateral R&R, including cured-in-place-lining, pipe bursting, sliplining, and alternative pipe materials. Trenchless construction methods are industry best practice and provide the benefit including substantially lower average cost per mile, shorter construction times per mile, and lower overall disruption to the public from the construction activity. As reflected in the newest 10-year Capital Improvement Program, WWE’s goal is to have 50% or more of gravity sewer R&R work done using trenchless construction methods within the next 7 years.
The following sections of the report describe each of the primary activities that support the small diameter gravity sewer program and how mileage is credited between initial contract award and completion of
Commission Meeting: January 10, 2023
FY21-22 Sewer Inspection and Replacement Program Annual Summary
construction. Table 2 provides detailed figures on each activity by quarter for the FY 21-22 as well as mileage awarded and mileage completed.
Spot Sewer Repair Program Changes
The Collection System R&R Program includes funding of $26.4M for the Spot Sewer Repair Program, which has a current target of 700 repairs per year that are performed by outside contractor resources and a target of 400 repairs using a Public Works crew funded by Wastewater Operating funds. Spot repairs at this level of activity have been limited to reactive repairs of already failing pipes and laterals. As part of the changing asset management strategy for the gravity sewers, the annual spot repair targets will be increased so that proactive spot repairs can be deployed to restore pipe structural integrity before failure and will rely more on trenchless spot repair construction methods. Proactive spot repairs will provide improved cost efficiency, less public disruption due to construction, and improved overall construction quality, in comparison to the current reactive spot repairs approach.
Another notable change to the spot repair program is the ending of use of Public Works crews. This change has been evaluated for several years between SFPUC and PW due to the increasingly limited capabilities of the crews, substantially higher costs, and lower productivity compared to the contractor resources. The two departments have worked cooperatively on this transition, including the transfer of 11 staff from PW to SFPUC WWE as of July 2022. These staff are working on gravity sewer activities such as cleaning, condition assessment, and service calls. The Wastewater Operating budget funds previously used for the PW crews have been repurposed to increase the mileage capacity of the next round of proactive spot repair bid projects.
Condition Assessment
WWE Collection System Division (CSD) performs condition assessment on small diameter sewer mains.
Condition assessment generally consists of cleaning, inspection, and NASSCO Pipeline Assessment Certification Program (PACP) coding. Due to the large quantity of assets, CSD prioritizes sewer main condition assessment by grids with a risk-based asset management approach, known as the Collection System Asset Management Program (CSAMP). Once condition assessment is performed, renewal and replacement projects are developed.
CSAMP is based on the Total Risk, which is calculated by Likelihood of Failure and Consequence of Failure:
Likelihood of Failure is a score that considers sewer main expected remaining useful life and age. Likelihood of Failure is further refined by physically assessing actual sewer main condition by Closed Circuit Television (CCTV) video inspections. Consequence of Failure is a score that considers a variety of potential impacts, including location-specific risks, public safety, and economic factors. Table 2 summarizes the overall progress of the condition assessment activities for Fiscal Year 2021-2022.
System Maintenance is defined as regular maintenance activities completed by WWE CSD Sewer Operations, which includes cleaning, inspection, and NASSCO PACP coding for condition assessment. These individual activities are identified to illustrate different efforts. Condition assessment includes coding media sources from prior years and 3rd Parties such as PG&E’s cross-bore elimination program inspection mileage.
*Sewer Renewal & Replacement: Miles of Sewer Mains Awarded is defined as the mileage of sewer mains that were included as part of construction contracts awarded this Fiscal Year. These data sets are further broken to illustrate different contract mechanisms for project delivery. Note contract award is approximately 2-3 years prior to construction completion.
**System Renewal & Replacement: Miles of Sewer Main Renewed / Replaced is defined as contracted collection system asset renewal and replacement that have been installed during the current Fiscal Year. After award, completion may take 2 to 3 years typically.
***System Renewal & Replacement: Locations of Spot Repair is defined as individual spot repair locations for both mains and laterals, tracked by number of locations for spot repairs.
Commission Meeting: January 10, 2023
FY21-22 Sewer Inspection and Replacement Program Annual Summary
Table 2: Fiscal Year 2021-2022 Sewer Inspection & Replacement Program System Maintenance: Miles of Sewer Mains Cleaned
Description Q1
Jul 1-Sept 31
Q2
Oct 1-Dec 31
Q3
Jan 1 - Mar 31
Q4
Apr 1 - Jun
30 Cumulative
Total as of
06/30/2022
CSD Sewer Ops 21.6 12.7 21.7 22.7
SFPUC Inspection Contractor 0.9 1.1 2.9 0.90
Total Miles of Sewer Mains Cleaned 22.5 13.8 24.6 23.6 84.5 System Maintenance: Miles of Sewer Main CCTV Inspected
Description Q1
Jul 1-Sept 31
Q2
Oct 1-Dec 31
Q3
Jan 1 - Mar 31
Q4
Apr 1 - Jun
30 Cumulative
Total as of
06/30/2022
CSD Sewer Ops 14.4 9.0 16.9 20.8
PG&E 0.0 0.1 0.01 0.0
SFPUC Inspection Contractor* 2.1 0.9 2.6 1.3
Total Miles of CCTV Inspection 16.5 9.9 19.5 22.1 68.0
System Maintenance: Miles of Sewer Main Inspection Media Coded for Condition Assessment Description Q1
Jul 1-Sept 31
Q2
Oct 1-Dec 31
Q3
Jan 1 - Mar 31
Q4
Apr 1 - Jun
30 Cumulative
Total as of
06/30/2022
CSD Sewer Ops 11.7 7.0 5.2 28.0
CSD Consultants 1.0 3.3 2.1 8.5
SFPUC Inspection Contractor 0.5 1.9 3.1 0.9
Total Miles of Media Coded 13.1 12.2 10.4 37.4 73.1
System Renewal & Replacement: Miles of Sewer Main Awarded for Renewal and/or Replacement* Description Q1
Jul 1-Sept 31
Q2
Oct 1-Dec 31
Q3
Jan 1 - Mar 31
Q4
Apr 1 - Jun
30 Cumulative
Total as of
06/30/2022
R&R (PUC Led Projects) 1.0 0.9 1.0 0.7
R&R (Joint Projects) 0.8 5.0 1.3 2.2
Total Miles Awarded for Renewal /
Replacement 1.8 5.9 2.3 2.9 12.9
System Renewal & Replacement: Miles of Sewer Main Renewed / Replaced** Description Q1
Jul 1-Sept 31
Q2
Oct 1-Dec 31
Q3
Jan 1 - Mar 31
Q4
Apr 1 - Jun
30 Cumulative
Total as of
06/30/2022
R&R (PUC Led Projects) 0.5 0.6 0.2 0.1
R&R (Joint Projects) 1.0 0.8 1.2 3.6
Total Miles Renewed / Replaced 1.6 1.4 1.4 3.7 8.1
System Renewal & Replacement: Locations of Spot Repair*** Description Q1
Jul 1-Sept 31
Q2
Oct 1-Dec 31
Q3
Jan 1 - Mar 31
Q4
Apr 1 - Jun
30 Cumulative
Total as of
06/30/2022
Repairs Completed by Contractor 213 181 141 172
Repairs Completed by SFPW BSSR 53 50 46 34
Total # of Repairs Completed 266 231 187 206 890