Reducing Inflow and Infiltration in Wastewater Systems

Stormwater flowing into a municipality’s sewer system through low gully traps, illegal connections, broken pipes, and unsealed manholes can cause overflows, system strains, and interruptions in your sewer operations. This is known as Inflow and Infiltration; aka I&I.

Why bother to fix Inflow & Infiltration?

By identifying I&I early and reducing their levels, municipalities can benefit from:

1. Reduced localized overflows: Through the management of overflows from manholes during rainfall, controlled overflow points, pump stations, and treatment plants.

2. Improve operational efficiencies: I&I reduces the sewer system capacity, limiting the potential for growth within a specific catchment.

3. Reduced ongoing costs: I&I results in clear water being pumped and treated along with wastewater, contributing to increased costs.

How to identify whether you have an I&I problem

Councils and water authorities can identify whether they have existing I&I issues within their system by looking for these indicators:

• Pumps run for hours and inflows increase significantly during storm events

• The hydraulic loading of wastewater treatment plants increases significantly after a rain event

• Localized overflows occur within a collection system during a heavy storm event

• An increase in inflow during dry weather conditions compared to previous months

Steps to reduce I&I within your wastewater system

First, identify the general vicinity of the issue through flow monitoring. Then identify the exact problem, locate the area(s) where it is occurring, and introduce measures to improve the situation.

The following steps provide a simple overview of an I&I reduction plan that can assist in identifying various stages associated with reducing I&I in a wastewater system:

1. Targeted monitoring – monitoring wastewater flows within the system

2. Identifying the problem – is it inflow or infiltration?

3. Source detection – where is it occurring within the system?

4. Rehabilitation – what can be done to reduce or eliminate the problem(s)?

Source detection

A few ways to detect the sources of I&I include:

Private Inspections – after receiving and documenting permission from property owners, inspecting private properties consists of visual assessments of the stormwater and wastewater networks within a property. Illegal connections could mean that a stormwater down pipe is directly connected to a wastewater gully trap.

Manhole Inspection – Manhole inspections can identify leaks from broken pipes, and joints due to tree root intrusion or design issues. Manholes can contribute to significant I&I through leaky covers as well.

Smoke Testing – Smoke testing locates I&I sources by identifying stormwater drain cross connections, broken pipes, and laterals, or unsealed manholes.

Dye Testing – Dye testing can be used to identify leaks and confirm smoke test results. The method uses water mixed with a non-toxic dye. The colored water Is pumped through the ground and storm water system and appears in the sanitary sewer collection system where leaks and illegal connections occur.

CCTV (closed circuit television) cameras – CCTV allows authorities to visualize the inside of pipes by using a small camera that travels down the length of a pipe to produce a visual representation of its condition. CCTV inspections can reveal the need for rehabilitating leaky pipes, facilitate grease or root removal, identify improper taps into the municipal lines, or find broken lateral connections.

Rehabilitation of Wastewater systems

Rehabilitation can include, but is not limited to, the following:

• Seal manholes and replace leaky covers

• Use cured-in-place piping (CIPP), trenchless rehabilitation or chemical grouting to seal leaks, and open cut replacement pipes

• Raise gully traps and disconnect stormwater downpipes from the gully trap and redirect into stormwater systems

• Fix broken laterals (reline or replace); fix any other private connections which might be improperly or illegally tapped into the municipal system

OMAG Risk Management Services wants to assist our municipalities in providing a safer and more efficient sanitary sewer system for their constituents. We offer several grants and programs to help you get started. Contact William Sheppard (wsheppard@omag.org) for more information if you are interested in improving your sanitary sewer system by reducing Inflow and Infiltration.

City of Weatherford: A CMOM Success Story

The Oklahoma Supreme Court has stated that “The maintenance and repair of [city] sewers is a corporate or proprietary function of a city and the city is liable for injuries sustained because of its failure to maintain and repair sewers properly.”  Oklahoma law requires municipalities “to use reasonable diligence and care to see that such sewer is not clogged ... and is liable for negligence in the performance of such duty to a property owner injured thereby after reasonable notice of the clogged condition of its sewer.”[1]

During 2004, the City of Weatherford had 48 sanitary sewer overflow claims resulting in a Consent Order from the Oklahoma Department of Environmental Quality (DEQ). Included in the Consent Order was the development of a CMOM (Capacity, Management, Operations, and Maintenance) Program to control their sanitary sewer overflows (SSOs).

The 2005 implementation of Weatherford’s CMOM program included the purchase of a trailer-mounted jetter and a dedicated crew of two full-time employees tasked with sanitary sewer collection system maintenance and record keeping for annual reports to OK-DEQ. Today their program has grown to three full-time employees, two trailer-mounted jetters, two vacuums, and a rover CCTV camera complete with a van. Weatherford has gone from having 48 SSOs in 2004 to averaging less than 2 per year from 2005 through 2018. Liability costs are greatly diminished and quality of life for the residents of Weatherford has improved.

The City of Weatherford’s sewer maintenance crew cleans over 250,000 feet of sewer line per year and video inspects about 3,400 feet per year. Their CCTV camera (OMAG has a grant for CCTV camera purchase assistance) removes the guesswork in determining what obstructs the line (roots, grease, debris, line collapse, etc.) and where exactly the problem is in the line. Then they can develop a plan to fix the problem and service the line. Weatherford uses root foam on about 7,000 feet of line per year (OMAG has a grant for Dukes Roots purchase assistance). Larry McKillip and his crew recommend using a Warthog jetting nozzle when jetting lines especially if they contain root balls. Larry says the Warthog is much more effective than mechanical cutters and saws, because the saws get stuck and are hard to dislodge, resulting in the need to dig up a line and break the pipe to retrieve the tool.

Trent Perkins, Public Works Director for Weatherford stated, “maps are critical for productivity.” That is why the city contacted their local COG (Council of Government)- SWODA for assistance in locating and mapping their water and sewer lines.  Through a grant (COG provides grant assistance for REAP and CDBG programs provided by the Oklahoma Department of Commerce,) the city has a viable computerized map showing the locations of all their water and sewer lines as well as manhole locations. OMAG can also assist member municipalities in gaining helpful information about their sewer systems using the SL-Rat (Sewer Line -Rapid Assessment Tool). This tool is loaned to cities and towns to quickly assess and map their sewer lines and determine what areas of town need maintenance, repair, or replacement, so municipal leaders can formulate a plan and budget for said infrastructural improvements. It is our belief the SL-Rat is an excellent tool for municipalities to use if they are seeking a REAP or CDBG grant.

Since sanitary sewer overflows are the most frequent liability claim filed against municipalities and authorities annually, and the cost of SSO claims continues to increase each year, OMAG recommends our cities and towns investigate utilizing resources to rehabilitate their aging sewer infrastructure.

A CMOM or any sewer line maintenance program is a costly start-up investment in time, staffing, and money, but it will quickly pay for itself by reducing sanitary sewer back-up claims. Citizens like to see capital improvements like new fire trucks, police cars, parks, and ballfields (the stuff we can see), but it’s also true they don’t like to have raw sewage running into their homes and businesses. Oklahoma leaders have been talking about our aging and disintegrating infrastructures for years. It is time to start making plans for major overhauls of these systems. Don’t wait for a consent order from OK-DEQ - take advantage of the resources available to you and start making the changes now.

According to Trent Perkins, “Personnel is the most important factor in the success of a sewer maintenance program, that and having the proper equipment, but support from the city’s mayor and council is key to our success.” Mike Brown, Mayor of Weatherford stated, “The City of Weatherford is thankful and proud that OMAG recognizes our efforts utilizing the CMOM program. Trent Perkins and his crew do an outstanding job maintaining our water and sewer lines. We appreciate the partnerships with SWODA and OMAG working with Weatherford to provide the best services available to our citizens.”

For more information about borrowing an SL-Rat from OMAG or to inquire about a CCTV camera or Duke’s Root Control grants contact William Sheppard or Kip Prichard at (800) 234-9461.

[1] Spencer v. City of Bristow, 2007 OK CIV APP 67, ¶ 12, 165 P.3d 361, 364

Preventing Waterjetting Injuries

You wouldn’t expect latex gloves to protect you from a gunshot. They won’t protect you from water-jetting accidents either. 

An OSHA article describing the dangers of high-pressure jetting notes, “High pressures can cause injuries similar to gunshot wounds, but have the added health hazard of involving contaminated water.” 

In pipeline-related industries, dangers are plentiful. Trenches, excavation, and confined spaces are often touted as the main concerns in risk management, but operators face another underestimated risk on a daily basis — cleaning with water under pressure. 

 “Injection injuries can happen at much lower pressures that are in use in drain and sewer applications. And that carries the risk of infection and tissue damage as well.  …Water injection injuries can appear minor but can cause serious health complications, even at pressures in the range of a consumer pressure washer or drain cleaner,”

says Peter Wright, association manager with the WaterJet Technology Association and Industrial & Municipal Cleaning Association. 

Despite being generally overlooked in terms of safety across the industry — due in part to a relatively low rate of injury when compared to working in trenches and the like — jetting is a concern simply because of how common it is. 

Lines are jetted for daily cleaning operations, inspections, and rehabilitation: With just about any work involving pipes, water jets are in play. 

 “Trying to get people to understand that you can get injured by a water jet strike is probably the most difficult bit to get across to people,” says Nick Woodhead, president of US Jetting. “We’ve got to start promoting safety.”

“I think people assume that hoses are not going to burst, and therefore, they are sort of immune. Or they’ve never seen a hose burst, or they’ve never seen a jet injury, so it doesn’t really register. People get complacent.” 

And it’s not just equipment malfunction that operators need to worry about. 

Case in point: Chad Unverzagt, the Indiana operator who was killed in 2012 during a routine sewer blockage. Unverzagt wasn’t killed by an exploding pipe or other malfunction — his hose got loose while the system was pressurized as he was attempting to retrieve it from the pipe. A momentary lapse in a job he’d done a thousand times before and for more than 30 years in the industry. 

With no protective gear, he didn’t stand a chance against the high-pressure water, which lacerated his neck, killing him before help could arrive. 

 “That’s more of an isolated incident, but it’s worth reminding people,” Woodhead says. “That’s why you’ve got to know what you’re working in.” 

A few months after that incident, Cleaner published another Safety First article, highlighting a new line of protective clothing from TST Sweden AB. Though the medium-pressure gear hadn’t reached enough awareness at the time to help Unverzagt, today, operators and their employers have fewer and fewer excuses for ignoring proper safety. 

“The safety gear is essential when you’re running a machine. So many people don’t wear anything,” Woodhead says. “We’ve got to try and get it across to people, it is worth investing in the kit to protect yourself. Even if you’re the operator and maybe the boss doesn’t want to spend the money; it’s worth investing in it, just as a precaution.” 

US Jetting has made it their practice to supply a pair of protective gloves to customers with the purchase of a jetting system, and it has encouraged other manufacturers to do the same. 

Other products like semiautomatic jetting systems give even more options for mitigating risk to operators. 

“OSHA says if there is safety gear available, the employers are bound to supply it,” Woodhead says. “Rather than have government regulation, we’d rather be self-regulated and have people understand (the dangers).” 

Beyond planning for the worst, simple common sense and following standard operating procedure goes a long way to ensuring safety. That includes checking the equipment before each job, performing the necessary maintenance, and assessing each job site before beginning any work. 

“It doesn’t take more than a couple of minutes to do the cursory checks,” Woodhead says. “Once you’ve gotten to your location, you’ve got to do your due diligence. … Just scope out the job for 15 or 20 minutes while your tank is filling up.” 

To get you started, Wright offers a few quick tips to keep in mind: 

“Use a skid that will not allow the nozzle to turn around in the pipe or mark the end of the hose a distance from the nozzle to help indicate the location of the nozzle within the pipe. Ensure the system is depressurized before conducting maintenance or repairs. Ensure the nozzle is well inside the pipe before bringing the system up to pressure,” Wright says. 

It’s easy to oversimplify pipe cleaning, but when the pressure is on, there’s a lot operators can do to prevent accidents — it’s just a matter of knowing how and promoting safety whenever possible. 

“It’s definitely important to have respect for the power and the force of high-pressure water streams,” Wright says.

MUNICIPAL WATER & WASTEWATER TREATMENT PLANT COVERAGE

Many of our Municipal Property Plan members own and operate their own Water and Wastewater Treatment Plants. Operating these plants can present challenges in providing routine plant maintenance, meeting growing population needs, staying in compliance with regulatory requirements and upgrading their outdated structures and equipment. Many have provided these upgrades and many more will soon need to do so. These upgrades can certainly impact values and leave your municipality exposed. Backup generators, upgraded or added pumps, electric control panels and SCADA systems are exposed to lightning and power outages. Buildings, fencing and lighting are exposed to hail and high winds and vandalism. 

 OMAG completed an appraisal project on all plants in 2020 through our partnership with a professional appraisal service. This was a five-year project targeted at appraising all of our members’ Water and Waste Water Treatment Plants. These professional appraisals were provided as a value-added service at no charge to members. Our purpose in performing these appraisals is to be certain that you are provided an accurate replacement value for these structures and equipment.

If you have any questions regarding your plants’ coverage or our professional appraisals of your plants, please contact Underwriting Director Chris Webb.   

What is Wastewater?

We’ve all driven by those “wastewater treatment facilities” that are usually miles away from our city or town. You know the place even before you see it; many times in the summer you can tell where it is by following your nose. Have you ever wondered what happens at those facilities? Basically, dirty water is cleaned and returned to streams and lakes in the following methods. 

What Is Wastewater?
Many people confuse the terms wastewater and sewage. According to Wikipedia, wastewater is any water that has been corrupted by human waste, but can also include industrial pollutants, as well as surface, storm, or sewer runoff. Sewage is a specific type of wastewater from human waste.

How Is Wastewater Treated?
Municipal wastewater is treated in municipal wastewater treatment plants. Once treated, wastewater is released back into water systems. In some municipalities, storm drains run directly into moving waterways such as creeks and rivers. In other municipalities where there is a high level of chemical runoff or where the storm drains combine with sewage the wastewater is sent to sewage treatment plants.

Sewage treatment is simply the process of removing contaminants from wastewater so it can be safely released back into the environment. The solids that are removed from sewage, often referred to as sludge or slurry, often undergo further treatment before being burned or even used as fertilizer.

There are physical, chemical, and biological processes involved in wastewater treatment.

The Three Main Types of Municipal Wastewater Treatment

Physical Wastewater Treatment - Physical or mechanical treatment of municipal wastewater removes the heaviest solids from raw sewage and municipal runoff. The process includes screening, sedimentation and allowing solids to sink, and often removes as much as 50-60% of the solids.

Biological Wastewater Treatment - In this second phase, live microbes are added to consume the dissolved organic matter that escaped the physical treatment stage. Microbes consume the organic matter as food and then convert it to carbon dioxide gas, water, and other less harmful waste. Additionally, much of the remaining organic material recombines or binds together. So, an additional sedimentation and screening may occur. At this point, as much as 85% of the solid waste will be removed from the wastewater.

Chemical Wastewater Treatment - This is the final step that will ensure the removal of more than 99 percent of all the impurities from wastewater. Chlorine disinfection is the most common chemical treatment. Other processes attempt to remove levels of phosphorus and nitrogen. Additionally, carbon filtering may be used in this final stage before clean water is released back into the environment.

What About Septic Systems?
According to some estimates, as much as 20% of the United States is currently treating their own sewage using onsite septic systems. Septic systems take all the water flow out of the home including the human and household waste. The wastewater flows into a septic tank where solids sink to the bottom and oils float to the top. These solids and oils are then removed on a regular basis. The remaining water flows into a drain field where the remaining liquids dissipate into the surrounding soil.

The Importance of Good Quality Microbes in Your Treatment System and Lift Stations
There are words in our language which trigger instant, negative sensations in those that encounter them. Sometimes, these feelings are justified; other times, they are not. Words like ‘bacteria’ and ‘microbe’ fall into this latter category.

These words are often associated with disease, with decay, and with general ill-health and uncleanness, but we need bacteria and microbes to survive. Microbes help us to maintain healthy digestion, they support entire ecosystems, and they can be used to great effect in our cities and towns.

Lift stations, or pumping stations, perform vital functions in our municipalities, but they can become unpleasant and even dangerous if they are not properly maintained. Therefore, good quality microbes and bacteria are vital in a treatment system and lift stations. 

A Fresher, Cleaner Environment in the Local Community
The nature of a pumping station – and the nature of the materials such stations handle – can unfortunately render them somewhat unpleasant to the people who live and work in the surrounding area. While people understand the vital work that lift stations do in municipalities all over the world, it is still the responsibility of the public works department to safeguard the quality of life of people nearby. Using good quality bacteria can assist with this.

Bacteria and microbe products work to neutralize odors, securing a fresher and far cleaner environment for the nearby city or town. They can also be used to treat the wastewater of the lift station – usually the source of the unpleasant odor. Oil, grease, and other unclean substances are broken down by the application of bacteria, and can then be easily removed or drained from the site. A healthy balance of microbes is vital to operations of the treatment system and lift stations.