Proper Wet Well Maintenance Contributes to Sewer System Health and Decreases Risk of Sewer Backups and Associated Environmental and Economic Costs
Wet well maintenance is essential. Any number of things can cause a pump to fail resulting in sewer infrastructure damage, sewer backups or a spill into the natural environment. A recent article in Timmins Today, “Grease and Rags Clog Pumps, Raw Sewage Bypassed into Lake”, demonstrates how things can go very wrong with a sewage system and negatively impact the environment.
The need for monitoring and cleaning of pumping stations has increased over the past decade thanks to the introduction of so called “flushable wipes” and other “flushables” that increase the potential for pump plugging or failure. These items are, in fact, not flushable and whole campaigns have been set up to inform people about their damaging effects and associated costs. In addition to the increased use of “flushables”, new construction and cultural diet have contributed to the growing necessity for increased focus on wet well cleaning and maintenance.
5 Steps to Wet Well Maintenance & Cleaning
While there is no set standard when it comes to pumping station design or maintenance schedule, each station specific cleaning and maintenance needs must be assessed in accordance with the flows and sewage characteristics it receives.
There are 5 essential aspects to wet well maintenance and cleaning:
1. Wet Well Maintenance Safety Considerations
The first aspect for any maintenance and cleaning project is to ensure the project is completed in a safe manner. Wet wells are confined spaces and should be treated accordingly:
- Workers should be trained in confined space entry,
- Continuous gas monitoring should be employed,
- Lockout-tagout (LOTO) procedures should be followed, and
- Emergency procedures should be planned, documented and practiced in advance.
As wet wells often maintain flow during the cleaning and maintenance, extra care should be taken with gas monitoring as the gases in a wet well can change rapidly as influent is received from the sewer system.
2. Plan for Wet Well Cleaning and Maintenance
Each pump station has unique characteristics which will need to be accounted for. Some things will affect the maintenance operation, others may affect the safety procedures required. A wet well hazard assessment should be done prior to entry. Many municipalities have hazard assessments done for their pumping stations which should be reviewed with staff prior to well entry. Proper planning will tie into the safety, timing, water, and disposal aspects to ensure that the maintenance and cleanout activities are completed as efficiently and safely as possible.
3. Timing of Wet Well Cleaning
Flows through a pumping station will vary throughout the day reflecting the hours that people inhabit those areas. In a heavy industrial area, working hours may experience higher flows, whereas a station servicing a residential area will have higher flows earlier in the morning and later in the evening.
Some pumping stations will have multiple wet wells which can be isolated thereby eliminating inflow as a concern. Smaller stations will have only one wet well and maintenance should be scheduled when flows are typically lowest. Most pumping stations have flow monitoring which will assist in determining the optimal times for wet well cleaning and maintenance.
Another timing consideration is the frequency at which stations need to be cleaned. Often a complete cleaning of a wet well is only needed 1-2 times a year. However, weekly or even daily maintenance by operators is needed to clean bar screens and readily accessible debris.
4. Water Considerations
Proper cleaning and maintenance of wet wells requires a water source to break up the debris that has built up in the pump station. Grease, plastics, hair, rags, and grit can collect in the station and require a high-pressure water source to break up, dislodge, and liquify debris for easy removal with a vacuum truck or submersible pump. If onsite water is unavailable, it can be trucked in to complete the project.
5. Wet Well Cleaning Disposal
Once wet well clean-out debris is removed from the pumping station, it needs to go somewhere. Few wastewater treatment plants can receive the slurry/grit and debris from a pumping station wet well. Additionally, landfills will not accept material that does not pass a slump test (an indicator for overall solids concentration). Usually the material needs to be taken to a drying bed to solidify and then taken to a landfill for disposal. In some cases, it makes sense to process the material onsite, solidifying it for landfill disposal.
Implementing Procedures for Wet Well Cleaning and Maintenance Ensures Reduced Risk of Sewer Failures and Related Costs
To keep sewer systems running optimally, appropriate wet well cleaning and maintenance is crucial. Keeping the five steps to wet well maintenance in mind and ensuring that you have experienced workers performing the job will set you up for success. If you need to further explore your options for wet well maintenance, contact us; we can use our wet well maintenance expertise to customize the right plan of action for your facility.
Soils are more important to us than we realize, but they are often taken for granted. Around the world, farmers strive for sustainable, productive agricultural soils. In 2015, we celebrated the International Year of Soils as designated by the Food and Agriculture Organization of the United Nations (FAO). In FAO’s “The Status of the World’s Soil Resources”, it was reported that soils are deteriorating. They attributed this to a number of factors including:
- soil erosion,
- nutrient depletion,
- loss of organic carbon,
- over application of mineral fertilizers and pesticides, and
- declining soil biodiversity.
Further recognition was given by the International Union of Soil Sciences (IUSS) when it declared 2015-2024 the “decade of soils” in an effort to bring more attention to soil’s fundamental role in sustaining human life.
Desertification of Soils Trend and the Nutrient Management Act
Desertification of soils has been an ongoing concern in Canada, specifically in Ontario and Quebec, as soils continue to lose organic matter.
In short, we need to do more to build our soils and we need to do it better. In Ontario, we’ve been working with the Nutrient Management Act (NMA) for over 6 years now. The act and associated regulations ensure that any nutrient rich material (with the exception of fertilizer) is used in a beneficial manner that’s protective of the environment. Non-Agricultural Source Material (NASM) which is nutrient rich material includes manures, biosolids, food and beverage waste, and other non-agricultural source materials. The NMA has provided direction and a push in the right direction for sustainability and environmental responsibility.
The Importance of Biosolids as a NASM
Biosolids is one type of NASM that is key to improving our soils. The land application of biosolids has been going strong for over 50 years in Ontario. They provide many of the same macro and micro nutrients as well as organic matter that are found in manure. The importance of biosolids in agricultural nutrient management is well established and supported by government and academia. The quality of biosolids has continually improved with many municipalities further processing their biosolids into sailable fertilizer product.
Over the past couple of years, there has been a renewed interest in using NASM in different ways:
- Renewable natural gas,
- Electricity generation, or
- Biochar production.
In each instance, a portion of the processed material creates a residual that needs to be managed, typically through beneficial use on agricultural land.
Biosolids Land Application Alternative to Landfills
In Canada, over 2.5 million wet tonnes of biosolids are produced each year. Historically about 25% of that material was taken to landfill, with the remainder either used on agricultural land (35%) or incinerated (40%). Additionally, 34 million tonnes of municipal and industrial waste is generated each year of which only 8 million tonnes (25%) is recycled.
As the province moves towards a more sustainable future, biosolids and other organic materials are becoming coveted resources rather than wastes. New legislation is forcing this change in Ontario with the Waste Free Ontario Act. A renewed focus on reuse has come to the forefront. With diversion goals of 30% by 2020 and up to 80% by 2050, biosolids and other organic resources will no longer be permitted in landfills. Other provinces have already banned organics in landfills.
While biosolids land application and other NASM will increase over the coming years, it will remain a viable and desirable option for municipalities. Only 15% of Ontario’s land base would be needed to use all the biosolids produced in the province beneficially, leaving 85% of the agricultural land available to receive other soil amendments therefore there is a lot of room for growth.
There are additional benefits as returning organic matter to our soils will reduce our carbon footprint through carbon sequestering while simultaneously increasing yields and improving soil resilience. A 1% increase in soil organic matter is approximated to 5.8 tons/acre of sequestered carbon. A study in Michigan also showed a crop-yield increase of about 12% for every 1% increase in soil organic matter.
Biosolids land application produces positive results with both crop production and environmental sustainability. To see biosolids land application in action, check out the Case Study: Brant County.
In the summer of 2012 after wheat harvest, Wessuc injected liquid biosolids in the South East corner of a farm located in Brant County Ontario.
Due to unforeseen circumstances, we were unable to apply the entire usable area. While it was disappointing to leave areas of the field without biosolids it provided the opportunity to collect crop response comparison data. Using Google Earth imagery and yield monitoring data of the biosolids injected vs. the farmer’s attempt to match the fertility levels of those biosolids commercially we were able to track the crop yield response.
The area where biosolids were applied showed a significantly positive yield response compared to the areas that received other amendments.
Economic Advantages- Highlights
The farmer ultimately experienced an increase in profits by using biosolids vs. commercially available amendments.
Find out more about Wessuc’s land application services.