Wastewater Collection System Components

Contributed by Phil Vela

A wastewater collection system is a series of pipes, tunnels, conduits and other devices that transport wastewater from homes, businesses and industries to a central treatment plant. Transport of the wastewater is either by gravity (the preferred method) or with the use sanitary lift or pump stations to either a location that gravity can be used or to another lift or pump station and finally to the wastewater treatment plant. In either case, the collection system has many functioning parts as shown and described below.

Figure 1 (source) shows the different types and sizes of sewer lines in a typical wastewater collection system. They range from the smallest (approximately 4 inches) located at the home or business to the large truck mains (minimum 12 inches and can be as large as 27 ft tunnels in large cities) that carry the sewerage to the waste treatment plant. A brief description of each follows.

Here's house the Louisville Metropolitan Sewer District describes each of the components:

House Sewer conveys the sewerage from a building to the lateral or branch lines.

Lateral & Branch Sewers are the upper ends of the municipal sewer system. Laterals dead-end at their upstream end with branch sewers collecting the wastewater from several lateral sewer lines.

Sub-main Sewers are collectors for numerous lateral and branch sewers from an area of several hundred acres or a specific neighborhood or housing development They convey the wastewater to larger trunk sewer lines, to lift stations or to a neighborhood package water quality treatment center.

Trunk/Main Sewers serve as the main arteries of the wastewater collection system. They collect and convey the wastewater from numerous main sewer lines either to a water quality treatment center or to a interceptor sewer.

Interceptor Sewers receive the wastewater numerous from trunk sewers and convey it to a water quality treatment center. These are the largest diameter lines in the sewer system and the furthest downstream in the system.

Lift or Pump Stations are utilized in gravity sewer systems to lift (pump) wastewater to a higher elevation when the route followed by a gravity sewer would require the sewer to be laid at an insufficient slope or at an impractical depth. Lift stations vary in size and type depending upon the quantity of wastewater to be handled and the height it must be lifted.

This video from American Water College describes the components of a wastewater collection system:

Using Willow Trees to Treat Wastewater

This article was featured in a recent edition of Innovations for Small Systems, our monthly water technology newsletter.

Researchers at University of Montreal, Canada have found a way to filter the waste from municipal wastewater through the roots of willow trees while also producing renewable bioenergy and 'green' chemicals. The study, which was published in Science of the Total Environment, details the experiment conducted in Quebec, Canada to investigate the potential for sustainable wastewater treatment through phytofiltration, an emerging method to remove contaminants from water through the use of plants, to be integrated with renewable biorefinery. 

Phytofiltration plantation is an alternative wastewater treatment method where root systems from non-food crops, such as fast-growing trees, are used to capture contaminants and nutrients from wastewater. Short rotation coppice (SRC) willow has been considered as a promising renewable bioenergy crop due to its natural tolerance to contamination and the roots ability to filter out nitrogen in sewage, which can then be harvested for renewable lignocellulosic biofuels. This concept of a biorefinery illustrate the potential of multifunctional biotechnologies to address environmental challenges caused by human activities.

Photo Credit: Katy Walters

Studies Track PFAS Through Wastewater Facilities

This article was featured in a recent edition of Innovations for Small Systems, our monthly water technology newsletter.

University of New Hampshire (UNH) researchers have conducted two of the first studies in New England to show that per- and polyfluoroalkyl substances (PFAS) are ending up in the environment differently after being processed through wastewater treatment facilities, making it more challenging to set acceptable screening levels.

Researchers including Paula Mouser, associate professor of civil and environment engineering at UNH, aimed to highlight the gaps around contaminants of emerging concerns (CECs) in wastewater residuals and to stress that more research is needed to assess the impact of facility design and operation on the treatment of CECs before costly upgrades are implemented to comply with stricter drinking water standards. 

The first study, which was recently published in The Royal Society of Chemistry, investigated the distribution and fate of 24 different PFAS through six New Hampshire wastewater treatment facilities to examine how they are distributed after being treated. The study aimed to characterize PFAS in wastewater treatment influent, sludge, and effluent discharging into the Great Bay Estuary in southeastern New Hampshire. 

The second study, which was featured in the New England Water Environment Association Journal, evaluated the changes in 24 PFAS and 21 pharmaceutical and personal care products (PPCPs) during wastewater treatment and assessed the composition of PFAS in biosolids post-stabilization treatment. Recent studies have suggested PPCPs and PFAS from land-applied biosolids may accumulate in soils, agricultural crops, and food products. This study compares the composition and concentration of PFAS from 39 biosolid samples collected from WWTFs in New Hampshire and Vermont.

Photo Credit: Conservation Law Foundation

Free Wastewater Quizzes

Last year the much-loved Skills Builder tool from WEF, the Water Environment Federation, received an refresh along with a commitment to keep it updated.

The WEF Skills Builder offers randomized 10-question quizzes on wastewater and laboratory topics at three difficulty levels. The updates modernized the functionality as well as aligned the questions with ABC's standards for subject matter and format.

The tool is free to use and correct answers are provided, along with linked references to WEF's publication store.

Study guides and test preparation resources are a popular topic on our blog, including this post on studying for certification exams.

Fatbergs, the Icebergs of a Wastewater Collection System

Contributed by Phil Vela

The term fatberg was first used in 2008 to describe the "large, rock-like lumps of cooking fat" washing up on beaches in Wales. In 2015 the word was added to the Oxford English Dictionary. In general a fatberg is a rock-like mass of waste matter in a sewer system formed by the combination of flushed non-biodegradable solids, such as wet wipes, and congealed grease or cooking fat. Fatbergs have been around since humans invented sewer systems and date back to Roman times when slaves were used to clean out effected areas. Because most of the mass cannot be seen, the term fatberg is used.

How do they form?

Fatbergs are basically a combination of fats, oils and grease (FOG) that congeal forming solid deposits in the collection system or at a lift station. These obstructions usually form at rough surfaces of sewers where the fluid flow becomes turbulent. All that FOG, along with human waste, settles into crevices in the sewer pipes. The fat can also interact with calcium that can either come from concrete pipes or water in the system that has flowed over concrete and undergoes the process of saponification, or turning into soap.

Recently the problem has increased due to the use of so called “flushable wipes”. Kimberly Worsham, founder of FLUSH (Facilitated Learning for Universal Sanitation and Hygiene) describes wet wipes as “absorbent cotton bastards” that, unlike toilet paper, don’t dissolve in water but instead are great at grabbing grease. “Imagine a bunch of fat-soaked wet wipes in a sewer about 2 feet wide—they’re going to get together and clump up.”

How big are they?

Fatbergs can be very large and can cause sewer backups. In 2017 a fatberg of congealed fat, wet wipes, and waste was discovered under the streets of Baltimore, Maryland that caused the spillage of 1.2 million gallons of sewage into Jones Falls.[1]. The largest fatberg in the UK was discovered in a sewer at Birchall Street in Liverpool. It weighed 440 tons and was 820 ft long. After 6 months is was still being removed from the sewer as it is proving to be difficult to break-down using conventional tools and equipment.[2] A fatberg the size of a gas tanker truck, found in Melbourne in April 2020, is thought to have grown so big due to a toilet paper shortage brought on by COVID-19, which spurred people to buy more wet wipes.[3, 4]

How can you prevent fatberg formation?

Fatberg formation can be minimized by simple actions including: 

1. Installation of grease traps from commercial businesses. This is a common practice in the US and most cities have regulations relating to sizing and maintenance of the traps.
2. Do not add coffee grounds, fat, oils or other food items to your drain. Even though you may have a garbage disposal, try to minimize the amount of material placed in them as it ultimately can add to the load on a wastewater treatment facility.
3. Never flush wet wipes or anything other than toilet paper down the toilet. If you ever had a septic system, you know the problems and expense this will cause.

Fatberg in Macomb County, Michigan

References

• https://en.wikipedia.org/wiki/Fatberg
• https://www.mentalfloss.com/article/627079/fatberg-facts
• ¹Wells, Carrie. "'Fatberg' of congealed fat, wet wipes and waste discovered under Baltimore's streets, causing sewer overflows". The Baltimore Sun. Retrieved 26 September 2017
• ²"Monster found in liverpool sewer". www.unitedutilities.com. Retrieved 22 July 2019.
• ³"The flushed items that caused a 42-tonne 'fatberg' in Melbourne". 7NEWS.com.au. 14 April 2020. Retrieved 14 April 2020
• ⁴"Giant fatberg heavier than petrol tanker discovered in Melbourne sewer". www.9news.com.au. Retrieved 14 April 2020

Image Credit: Macomb County Public Works

Is Water Recycling the Future?

Water recycling could be the answer to one of the country's greatest challenges in the coming years as drought worsens because of climate change.

The Infrastructure Investment and Jobs Act, if signed into law, could provide $1 billion for water recycling and reuse projects, including funding for large-scale projects to ease dwindling supplies in Western states.

This explainer from Bloomberg Law offers a plain language overview of water recycling, including why direct potable reuse isn't as 'icky' as the public might think. As attention grows on these projects, public education will be a key factor to garner support. A United Nations report from 2017 also touts wastewater as the ultimate untapped resource. 

Tour of Alaska's Largest Wastewater Treatment Plant

The John M. Asplund Water Pollution Control Facility in Anchorage, Alaska is the state's largest wastewater treatment plant. It is owned and operated by the Anchorage Water & Wastewater Utility. This video showcases the plant's evolution since 1972 to its current capacity of 58 million gallons per day. It also provides regulatory and scientific context for the wastewater treatment process. This is a great example of how a system can use video to help the public understand what you do and why it is important. 

Preparing for Funding Opportunities

Proposed infrastructure funding has been on everyone's radar, despite uncertainty about what fine print will ultimately be passed by Congress. The new plan could be the largest investment in drinking water and wastewater infrastructure in American history and bipartisan support for these efforts means that new funding opportunities for a range of stakeholders are likely.

This makes it all the more important to know how to apply for and manage funding when it becomes available, as well as understand your needs and eligibility. Navigating the world of funding can feel intimidating, but there are many resources available to help aid the process. Preparing ahead of time is the best way to make sure your organization is ready to respond to funding opportunities. 

This preparation begins with a capacity development approach. Capacity development is a process that water systems can use to acquire and maintain adequate technical, managerial, and financial capacity. Programs have been established in every state to help public water systems continue to strengthen their capacity and you've likely crossed paths with training, resources, or technical assistance provided through these programs.

We're highlighting a selection of our favorite capacity development resources that can help systems (and those who serve them) undertake readiness efforts for potential infrastructure investment.

Managerial Capacity 

Managerial capacity for short and long term planning includes:

• Ownership accountability 
• Staffing and organization 
• Effective external linkages 

Resources:
Water System Owner Roles and Responsibilities: A Best Practices Guide
This guide can help owners and operators of public water systems serving less than 10,000 people better understand their responsibilities. 

Strategic Planning: A Handbook for Small Water Systems
This handbook was designed to help operators serving less than 3,000 people develop a strategic management plan. 

Manual for Assessing Public Water Supply System Capability
This manual goes through each of the components of capacity development, technical capacity, managerial capacity, and financial capacity. 

Financial Capacity 

Financial capacity for short and long term planning includes:

• Revenue sufficiency 
• Creditworthiness 
• Fiscal management and controls  

Resources:
Water Finance Clearinghouse
This portal was created by the U.S. EPA to help water operators locate helpful financial resources. 

Grant (Loan) Writing 101 - Right Grant, Right Time, Right Project
This 31-slide presentation explains the numerous steps that are included in writing a grant from start to finish. 

Introduction to Grant Writing
This 25-slide presentation addresses the basics of grant writing in the state of Utah. 

A Financially Healthy Water System Now and Into the Future
This presentation introduces questions that should be considered regarding the financial health of your system and how to understand your system's present and future needs.

U.S. EPA Grants Management Training for Applicants and Recipients
This online training course designed by the U.S. EPA  includes six modules that explain the grant life cycle process. 

Asset Management 

Asset management is the practice of making the most of capital assets, while also delivering the best customer service. It is essential to establishing sustainable infrastructure. Building an asset management team can lead to increased knowledge management, financial efficiency, and work efficiency. 

Resources: 
Building an Asset Management Team
This factsheet outlines the steps to take to build a functioning asset management team. 

Asset Management: A Handbook
This handbook, designed specifically for small water systems, reviews the basic concepts of asset management and lists tools to help develop a concrete plan. 

Reference Guide for Asset Management Tools
This reference guide is a collection of asset management plan components and implementation tools that drinking water and wastewater systems can use. 
 

You can find thousands of additional helpful resources in our database.

Maintaining Customer Satisfaction

Maintaining customer satisfaction can go overlooked when operators are busy tending to the daily needs of their facility, however good customer relationships are an important component to any well run utility. Community trust improves cooperation under emergencies and helps customers to do their part in caring for their system. When changes to the utility are made such as a new infrastructure project or a long awaited rate adjustments, customers will more easily hop on board. Not to mention, an unhappy customer can lead to unnecessary public relations (PR) challenges.

In Hartsville, South Carolina one business owner watched for a month as a sinkhole slowly took over her car lot. The owner first called her Water and Sewer Authority in September reaching out about her growing concerns. She made five additional calls into October until finally contacting her local news channel for help. Swiftly after the news channel reached out to the Authority, workers were sent to fix the sinkhole.

In Darlington, South Carolina a pair of homeowners brought their sewer system into the public eye under equally pressing conditions. The city received unprecedented rainstorms in October leading to excess stormwater runoff. Under these conditions, many homeowners experienced sewage backups. Despite the city's ongoing efforts to manage overflows, the backups brought the system into an unwanted spot light. A Sanitary Sewer Overflow Response Plan can help for incidents such as these.

While we can do our best to avoid these incidents, accidents happen. When they do, good communication and listening skills can make a difficult situation much easier. How to Keep Customers Happy in Solution H2O encourages utilities to establish a good public presence prior to these events. When services are disrupted, the article encourages utility leaders to step forward and reassure customers that their complaints are being addressed. We also recommend the supervisor follow up with impacted customers after the issue has been resolved. Many of the negative articles we see published in local news can be avoided by following the tips suggested in the American Water Works Association's publication Trending in an Instant. 

Defend Your Water System Against Drought

Many states across the United States are currently experiencing one of the worst droughts in American history. Some are even experiencing a "megadrought", meaning that they have been experiencing drought conditions for many years. Climate change also exacerbates drought conditions by increasing the average global temperature and causing irregular weather patterns. Westerns states such as California, Arizona, Montana, Nevada, New Mexico, and Idaho are experiencing some of the most extreme effects. Drought is particularly devastating because it is slow coming but its effects are widespread.

Increased drought conditions can result in:

• Loss of water pressure and supply 
• Poor water quality 
• Limited access to alternative water sources 
• Increased customer demand 
• Increased costs and reduced revenues 

For example, in Nevada, the drought has had disastrous impacts on Lake Mead, the largest water reservoir in the United States that currently provides water for over 20 million people across California, Nevada, Arizona, and some of Mexico. The reservoir is now at the lowest it has been since it was filled in 1937 and the situation is so extreme that the federal government is expected to declare an official Lake Mead shortage by the end of the summer. Drought can also negatively impact drinking water providers that rely on lakes because they can increase the number of algal blooms in freshwater. Algal blooms not only contain chemicals that are toxic to humans but large amounts of algae can also clog water filters and damage the water treatment process. 

A total of 31 states are currently experiencing moderate to severe drought across the country. Research also shows that the drought has become progressively worse over the past few decades. The U.S. Drought Monitor website has a feature that allows you to monitor the level of drought happening in your area.

Like most natural disasters, rural and low-income communities are often hit the hardest by drought conditions because of their lack of access to resources and infrastructure. Rural farmers are also greatly impacted by drought because of the lack of water available for irrigation, making it very difficult to support themselves. 

Droughts are a public health issue because they affect access to clean and safe drinking water. Practicing emergency response and preparedness is the best way to minimize severe impacts from drought. To avoid serious impacts from droughts, water utilities should:

1. Conduct observation and monitoring 
2. Practice planning and preparedness  
3. Predict and forecast 
4. Maintain good communication and outreach with customers 
5. Use interdisciplinary research and applications 

Resources for Drought Assessment and Resilience

Incident Action Checklist – Drought
This checklist from the U.S. EPA provides various ways for water and wastewater utilities to prepare for, respond to, and recover from a drought. 

10 Ways to Prepare for a Drought Related Water Shortage
This resource from the Rural Community Assistance Partnership lists ten ways to prepare your small water system for water shortages.

Small Water Systems and Rural Communities Drought and Water Shortage Contingency Planning and Risk Assessment
This report can be used to help strengthen your water shortage vulnerability assessments and risk scoring. 

Drought Contingency Plan for a Retail Public Water Supplier
This is a sample form that can be used as a model of a drought contingency plan for a retail public water supplier. 

Drought Management Plan A Template for Small Water Systems
This document outlines mitigation measures that water managers can take to greatly minimize the effects of drought. 

100 Water Saving Tips from “Water. Use it wisely.” 
Communicate some of these water-saving tips to your customers to help them conserve water during a drought.