Sewer Wet Wells in the United States: History, Functionality, Deterioration, and Rehabilitation

Introduction

Aging water systems in many U.S. cities require attention. The nation's reluctance to proactively invest in buried infrastructure over the past 50-years has significantly impacted the way that municipalities and other agencies operate. While potable water is first to mind for most when considering buried assets, the nation’s sewer collection systems are deteriorating as well. ?Sewer wet wells are critical components of wastewater collection systems. They play a crucial role in collecting and temporarily storing sewage before it undergoes treatment. This article explores the history of sewer wet wells in the United States, their functionality, the factors leading to their current state of deterioration, the importance of rehabilitating wet wells, and the economic feasibility of constructing new wet wells. Additionally, it delves into the use of Geopolymers and Fiber Reinforced Plastic (FRP) panels for wet well rehabilitation, with a specific focus on the advantages offered by FRP panels from Northwest Geneva and CPM Pipelines.

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History of Sewer Wet Wells in the United States

As cities grew in the 1800s, the demand for efficient water infrastructure became evident. Initially relying on hand-dug wells, lakes, and streams, urban areas progressed to more advanced systems. The ancient Roman water system, exemplified by aqueducts and sewers, served as a precursor to contemporary water infrastructure. In the U.S., rapid population growth prompted investments in imported water systems and sewage treatment facilities during the 19th century. This historical context laid the foundation for modern sewer wet wells.

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Current State of Water Infrastructure

Wet well deterioration is emblematic of broader issues in water management in the United States. It’s not new news that the nation faces challenges with aging water infrastructure. Over the last decade, the American Society of Civil Engineers has consistently given low grades to the country's water systems. An infrastructure crisis looms, demanding a delicate balance between affordability, sustainability, maintenance, and life-cycle cost. ?More than ever, municipalities and agencies are tasked with managing buried assets that have been neglected for far too long.? The good news is that, as with any crisis in American History, these same agencies and municipalities that are understaffed and underbudgeted are responding to these challenges by adopting new technologies and thought processes that will extend the life of their buried assets without realizing the expense associated with complete replacement. ?Technologies designed to protect surfaces exposed to corrosion or that are designed to cover the corrosive surface altogether have been vetted and are being rapidly adopted as the gap between needs and funding continues to increase.

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Importance of Wet Well Rehabilitation

Aging and Decreased Performance

Most wet wells were originally constructed with materials prone to corrosion, such as steel and concrete. These materials deteriorate over time due to corrosion, mineral deposits, bio-fouling, and exposure to the elements leading to decreased performance. Once the structure has deteriorated to the point that structural integrity is questionable, rehabilitation or replacement is essential to ensure longevity, restore efficiency, and prevent potential overflow and flooding.

Rehabilitating existing wet wells provides immediate environmental benefits, while constructing new, energy-efficient wet wells may take decades to offset the energy used during construction. Cost-effectiveness is a crucial factor, with retrofitting often proving more economical than building new structures.

Rehabilitating existing wet wells also minimizes the need for additional construction materials, reducing the environmental impact associated with manufacturing and transportation. Preserving older structures also conserves the significant embodied energy expended during their original construction.

In densely populated cities, rehabilitating existing wet wells optimizes infrastructure without encroaching on valuable land. This aligns with sustainability goals and minimizes disruption to urban areas.

Wet Well Rehabilitation: Surface Focus

Wet well rehabilitation can take various forms, including the rehabilitation of the wet well surface. Oxidation, accelerated by corrosive gases like hydrogen sulfide (H2S), poses a threat to wet well surfaces, leading to structural damage if left unaddressed.

Epoxies in Wet Well Rehabilitation: Definition and Advantages

Epoxies, known for their ability to polymerize and harden at low temperatures, are instrumental in wet well rehabilitation. Epoxy solutions present cost-effective, high-strength alternatives, demonstrating better resistance to aggressive environments compared to conventional materials.? Epoxies and other coatings have been widely used for some time now such that a body of knowledge about their efficacy and life-cycle costs has been developed. Some agencies are content to continue utilizing coatings while others have moved on to alternatives due to coating failures. These failures could be a result of an aggressive environment with high levels of hydrogen sulfide or are simply attributable to the design-life of the product. Whatever the cause, premature failures or failures in aggressive environments have served as a catalyst for a search for a viable alternative.

Fiber Reinforced Plastic (FRP) Panels

FRP panels from Northwest Geneva have emerged as an ideal solution for rehabilitating wet well surfaces, especially in corrosive environments. FRP Panels host a Key of advantages that include:

Corrosion Resistance: FRP panels resist corrosion from chemicals, moisture, and gases, unlike traditional materials like steel or concrete.

Chemical Resistance: Withstanding exposure to a range of chemicals found in sewage systems, FRP panels ensure long-term durability.

Lightweight and High Strength: Despite being lightweight, FRP panels offer impressive strength, handling heavy loads and resisting impact.

Smooth Surface and Easy Installation: The smooth, non-porous surface minimizes debris accumulation, reducing maintenance efforts. Additionally, FRP panels can be easily installed or retrofitted onto existing surfaces.

Longevity and Sanitary Properties: FRP panels boast a long service life, require minimal maintenance, and provide a non-absorbent surface, preventing bacterial growth and ensuring a sanitary environment.

Comparative Advantages of FRP Panels Over Coatings

When considering rehabilitation materials for corrosive sewer structures, FRP panels offer several long-term advantages over epoxy and other protective coatings. FRP panels maintain exceptional resistance to corrosion, chemicals, and moisture, ensuring long-term integrity and reduced lifecycle costs. With minimal maintenance requirements, the smooth surface of FRP panels prevents debris buildup, reducing cleaning efforts. Northwest Geneva’s patented process for customizing panels for each application results in FRP panels that are quick and easy to install while allowing for retrofitting onto existing structures.

Other advantages of FRP Panels over epoxies and other coatings include:

Corrosion Resistance and Structural Strength: Superior protection against corrosive elements, coupled with structural strength, positions FRP panels as a robust solution.

Hygiene and Sanitation: Non-absorbent surfaces of FRP panels prevent bacterial growth, ensuring a clean and hygienic environment.

Environmental Impact: FRP panels are eco-friendly, generating minimal waste and offering sustainability benefits over geopolymer coatings.

Despite a potentially higher initial investment, the extended 50-year service life of FRP Panels by Geneva Northwest offsets costs over time. The following graph depicts the life-cycle cost of the most commonly used rehabilitation methods.

Conclusion

In summary, the history of sewer wet wells in the United States reflects a journey of innovation and adaptation to the evolving needs of growing urban populations. As these wet wells face aging and deterioration, the importance of rehabilitation becomes evident. Wet well rehabilitation not only ensures continued functionality but also addresses environmental, economic, and historical considerations.

Fiber Reinforced Plastic (FRP) panels, particularly those provided by Northwest Geneva and CPM Pipelines, emerge as a superior choice for wet well surface rehabilitation. Their corrosion resistance, durability, low maintenance requirements, ease of installation, and decreased life-cycle cost contribute to long-term advantages over coatings.

As the nation stands on the cusp of a water infrastructure transformation, recognizing the value of wet well rehabilitation and choosing materials wisely will be crucial in building a sustainable and resilient future. Proactive investments in infrastructure and the adoption of innovative materials like FRP panels can pave the way for a water management system capable of meeting the challenges of the 21st century.

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