Sacramento Area Sewer District
Sacramento, California
The Central Trunk Sewer is an eight mile pipeline that conveys both residential and industrial
sewage for Sacramento County. Constructed in the 1960’s of unlined reinforced concrete, the
pipeline ranges from 33-inches to 60-inches in diameter and is located deep under major roads,
residential backyards, creeks, protected wetlands, and a state highway. Nearly 50 years of
corrosion has severely deteriorated the pipeline and restoring the structural stability of the
pipeline in a cost effective manner with minimal decrease in capacity and distribution to the
community became the primary goals for the Sacramento Area Sewer District (SASD). To meet
these goals SASD and their design consultant West Yost Associates (West Yost) chose cured-inplace
pipe (CIPP) to rehabilitate the entire eight mile pipeline alignment.
Throughout construction several lessons have been learned from this large CIPP project. This
paper will discuss some of the lessons learned as well as considerations for owners and designers
regarding quality control and quality assurance of liner samples, bypass vs. plugging sewer
flows, environmental mitigation monitoring and reporting program, public outreach, air quality
regulations, construction noise mitigation, and debris estimating.
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Posted: May 20th, 2011 | Filed under: >1M, Sanitary Sewer, Stormwater, Waste Water Treatment, Water Treatment | Tags: CIPP Rehabilitation, Corrosion Prevention, Environmental Impact, Improved Customer Relations, Improved Sewer Rehabilitation, Increased Sewer Life, Minimized Community Disruption, Noise Mitigation, Pipe Construction Alternative, Reduced Inflow and Infiltration | No Comments »
Orange County Sanitation District (OCSD)
Orange County, California
Wastewater from the coastal areas of the City of Huntington Beach are conveyed to the Orange
County Sanitation District’s Treatment Plant No. 2 through a 1350 mm/1800 mm/2100mm PVC
(Polyvinyl Chloride) lined RCP (Reinforced Concrete Pipe)sewer. The sewer was constructed in
the early 1980′s to service an area that included residential development at the north end that did
not occur due to overwhelming environmental issues. Since then, the sewer has conveyed
substantially lower flows and the portion of the sewer not lined with PVC has been exposed to
corrosive sewer gases and has corroded.
This project included a full evaluation of the condition of the sewer and looked at alternatives for
repair. Ultimately, the course of action included a unique solution that allowed the line to be
rehabilitated with a minimum of impact and disturbance to surface improvements including hotel
resorts and beach activities particularly during the summer.
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Posted: May 20th, 2011 | Filed under: >1M, Sanitary Sewer, Stormwater, Waste Water Treatment, Water Treatment | Tags: CIPP Rehabilitation, Corrosion Prevention, Environmental Impact, Improved Customer Relations, Improved Sewer Rehabilitation, Increased Sewer Life, Minimized Community Disruption, Noise Mitigation, Pipe Construction Alternative, Reduced Inflow and Infiltration | No Comments »
Water Works and Sewer Board of the City of Prichard
Prichard, Alabama
To comply with a State issued Consent Decree, the Water Works and Sewer Board of the City of Prichard, AL had to replace or repair 1,000 private sanitary sewer laterals to reduce inflow and infiltration that was leading to sanitary sewer overflows (SSOs). The anticipated cost of this effort was expected to be between $800,000 and $1 million, a significant amount for a community with a median household income of less than $20,000. Early struggles with excessive paperwork, inadequate equipment, and inexperienced personnel led to concerns by the State about the lack of progress. A revised strategy that simplified analysis and streamlined work was developed. The results were a 30 percent reduction in inflow and infiltration at a cost of $550,000. Overall SSO volumes were reduced by 95% and the number of recurring SSOs dropped from eight to one. Source: WEFTEC 2009 Proceedings
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Posted: August 27th, 2010 | Filed under: Sanitary Sewer, Water Treatment | Tags: Cost Savings, Reduced Inflow and Infiltration, Reduced Sanitary Sewer Overflows | No Comments »
Boston Water and Sewer Commission
Boston, Massachusetts
The Boston Water and Sewer Commission has been implementing various combined sewer separation projects throughout the City of Boston in order to significantly reduce combined sewer overflow frequency and volume to Boston Harbor. Two of these project areas include the completed South Dorchester Bay area and the Reserved Channel area which is currently under final design. Both of these project areas include ultra urban, primarily residential, watersheds within the city that are currently being served by combined sewers with installations that date back to the late 1800’s and early 1900’s. The Reserved Channel Project area, located in South Boston, and the Dorchester Bay Project Area are approximately 365 acres and 2,700 acres respectively. The sewer interceptor systems currently serving these areas surcharge during wet weather events and the combined sewer overflows then need to be rerouted to outfall pipes that discharge to Boston Harbor. It is evident that early identification and removal of as much stormwater inflow as possible is a key part of the success of both sewer separation projects. It is evident that the removal of as much storm water inflow as possible is a key part of the success of both sewer separation projects. For the ultra urban areas, simply installing storm drains and picking up existing catchbasins does not appear to be enough to significantly reduce the CSO frequency and volumes to meet the long term control plan goals. It makes good sense to investigate, identify, and remove as many impervious areas as possible to reduce storm water inflows to the sewers. This approach leads to the need for a comprehensive look at reducing stormwater from private property such as roof areas, parking lots, and other impervious areas that can be removed from the sewer system to reduce storm water inflow to the sewers. A cost/benefit analysis should be performed that evaluates this additional level of separation as well as alternatives such as increasing interceptor capacity, limiting upstream wastewater flows and providing in-line or off-line CSO storage. Source: WEFTEC 2009 Proceedings
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Posted: August 27th, 2010 | Filed under: Sanitary Sewer, Water Treatment | Tags: Cost Savings, Reduced Inflow and Infiltration, Reduced Sanitary Sewer Overflows | No Comments »
City of Westlake
Westlake, Ohio
The City of Westlake, Ohio has a program to remove Inflow and Infiltration (I/I) from both their public and private property segments of the sewer system. Specifically, the private property program uses residential dye testing to identify houses that have downspouts that contributes water into the sanitary sewer system. Historically, houses that test positive are scheduled for rehabilitation using a lateral liner from the mainline sewer to the house. A liner is inserted into the sanitary lateral which prohibits any stormwater or groundwater from entering the lateral. During the installation of the liners, it was found that a more detailed testing of the house would have shown that the deficiencies could have been corrected with cheaper, spot repairs or other methods of rehabilitation may have been more effective. The more detailed testing included dye testing as many downspouts as possible on the home being tested, and using two Closed Circuit Television Camera for the inspection The sanitary pipe layout is also identified to provide a more detailed knowledge of how the sanitary and storm pipes cross over each other. The CCTV cameras were installed in both the storm and sanitary sewer and advanced to the lateral of the test house. Subsequent testing followed by using a push camera in the lateral and recreating the test, further isolating the deficiency on the property. From this information the City was able to isolate which downspouts could be spot repaired, eliminating lateral lining rehabilitation resulting in a cost savings to the City. The detailed testing methods of both Phase I and II eliminated 70% of the lateral linings. Estimated cost per house for lining was $8000.00. In an area with 100 homes, in which 40% were positive, reducing 70% of the lateral lining is significant in terms of cost and additionally, accurately solving the problem. At the conclusion of the program, the City accurately identified private properties with inflow, removed stormwater from the sanitary sewer, minimized lateral rehabilitation and construction disruption, and provided overall project cost savings. Source: WEFTEC 2009 Proceedings
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Posted: August 27th, 2010 | Filed under: Sanitary Sewer, Water Treatment | Tags: Cost Savings, Minimized Lateral Rehabilitation, Reduced Inflow and Infiltration | No Comments »