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 »
Wastewater collection system odor and corrosion issues continue to grow in importance to
communities and to conveyance system owners and operators. Odor and corrosion prevention in
collection systems has been as much art as science. Common control methods are typically
selected based on field experience as opposed to a fundamental understanding of why and when
methods will be successful. Although much is known regarding the cause of odorous gases in the
collection system, the underlying science and mechanisms of odor generation, sewer ventilation,
odor characterization and monitoring, and corrosion mechanisms need further research. This
Water Environment Research Foundation (WERF) research project helps the industry transition
from “odor artists” to scientists and engineers, enabling designers to successfully prevent odor
and corrosion events through proper design and for operators to mitigate and prevent odor
excursions from existing systems.
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Posted: May 3rd, 2011 | Filed under: Sanitary Sewer, Stormwater, Waste Water Treatment | Tags: Corrosion Prevention, Improved Customer Relations, Odor Characterization and Monitoring, Odor Prevention, Sewer Ventilation | No Comments »
Corrosion in sanitary sewer systems occurs when hydrogen sulfide (H2S) is biologically converted to sulfuric acid. Although reducing metals was necessary to protect public health, pretreatment has contributed significantly to increased sulfides, leading to heightened H2S odor and ultimately to accelerated corrosion. As the main contributor to odor and corrosion in collection systems, H2S is typically treated with odor control agents that can be costly and ineffective in providing long lasting H2S removal throughout the collection system. Magnesium hydroxide is effective in eliminating H2S by reducing both dissolved sulfide production and headspace H2S gas, but it also offers additional benefits as well. The introduction of magnesium hydroxide does not lead to the formation of additional unwanted sludge, as often happens with lime and iron salts. Additionally, it provides long-lasting alkalinity, slowly dissolving to increase the pH of wastewater to an optimum pH range that significantly reduces the formation of H2S and prevents further corrosion of sewer lines. Magnesium hydroxide’s pH buffering ability provides effective treatment for miles downstream from the addition point thus reducing the number of chemical injection points needed. In addition to H2S odor and corrosion control and saponification of fats, oils, and greases, adding magnesium hydroxide to the sanitary sewer system provides additional benefit downstream in the wastewater treatment plant. Competing odor control agents do not provide total system treatment as does magnesium hydroxide, making it a more effective solution for municipalities. Source: WEFTEC 2008 Proceedings
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Posted: August 27th, 2010 | Filed under: Sanitary Sewer, Waste Water Treatment | Tags: Corrosion Prevention, Cost Savings, Enhanced Downstream Effluent, Increased Odor Control | No Comments »