Nestled near the vibrant community of Boulder, the City of Louisville, Colorado, stands as a model for enhanced Fats, Oils, and Grease (FOG) management. With a population of around 20,000 and a bustling downtown full of restaurants and historic charm, Louisville 's approach to wastewater management is both innovative and adaptive. A testament to this is their resiliency to the 2021 Marshall Fire which burned 550 homes, 149 of those are still under construction. Adversities such as this have led to the City taking steps to meet the community needs while also addressing the growing FOG problem.
The Louisville Wastewater Treatment Plant (WWTP), established in 1952 and located in Boulder County, has undergone numerous expansions to meet the city's growth and evolving environmental standards. Originally featuring a simple settling pond and aerated lagoon, the plant expanded in 1965 with an Extended Aeration Activated Sludge system that discharged to a lagoon system. Further improvements continued throughout the decades, including the plant remodel into a Biological Nutrient Removal (BNR) system in 2017 to meet the anticipated growth and needs of the community. Initial FSE tracking started in 2010. They purchased their replacement jetting truck in 2019-2020.
Year | Percent change |
2017 | 158% |
2018 | 15% |
2019 | 37% |
2020 | -35% |
2021 | -6% |
2022 | 36% |
2023 | -21% |
2024 | -100% |
This advanced system can treat 2.53 million gallons per day and significantly reduces nutrient loading into Coal Creek. The WWTP's treatment process uses microorganisms to break down sewage, with stages for grit removal, aeration, and ultraviolet disinfection before discharging treated water into Coal Creek. The plant also reuses treated water for irrigation at local facilities and stabilizes sludge into biosolids for agricultural use. Continuous upgrades, including ozone treatment and SCADA (Supervisory Control and Data Acquisition – Louisville's data management software) monitoring, ensure efficient operation and compliance with environmental regulations.
The city launched its FOG program in 2015, but it wasn’t until early 2024 that significant strides were made with more systematic tracking and enforcement. Initial hurdles—such as inconsistent tracking and staffing issues—have been overcome, thanks to a more structured approach and dedicated personnel.
Louisville employs advanced tools like BSI software for manifest tracking and Lucity for geographic mapping. This technology provides a comprehensive view of sewer lines and grease interceptors, allowing the city to prioritize inspections and maintenance effectively.
With approximately 113 food service establishments (FSEs) under its purview, the city’s program aims to address the challenges posed by high grease levels and their impact on the wastewater treatment plant (WWTP).
The results of Louisville's FOG program are already evident:
WWTP Costs: Although their operational costs fluctuate over the years and some projects have caused an increase due to higher capacity needs; buying a new jet/vac truck and ongoing capital improvements, they still seek to see a decrease in maintenance and line cleaning which is a direct correlation to reduced FOG in the sewer system. Any decrease in FOG will lower operational costs at the WWTP. In 2024 measurement of the FOG buildup at the POTW began to determine the efficacy of the Program. Use of a dipstick fog sampler is how the depth of the Influent FOG mat is assessed. 6 locations are sampled each month and the depth of the grease mat is recorded. Improved operations have shown a 5-10% reduction in grease since June 2024 to present.
Fewer Sanitary Sewer Overflows: Under the guidance of Environmental Compliance Program, the city has recorded only one sanitary sewer overflow (SSO) in the last year, which occurred on a private property due to a failed grease interceptor, a testament to effective maintenance and management. SSO's are limited due to excessive jetting of the collection system, cost is not reduced yet due to older infrastructure in process of being replaced. Education and outreach are their main form for FOG reduction/voluntary compliance.
Maintenance Costs: Ongoing data collection suggests an increase in collection system maintenance costs due to ongoing capital improvements. These improvements ought to assist with cutting maintenance costs in the future.
Extended Infrastructure Longevity: Regular maintenance is helping to prevent sanitary sewer overflows. However, due to older clay pipes and the increase of jetting, they also face the barrier of needing to replace infrastructure sooner.
Louisville’s FOG ordinance mandates that all FSEs must have a grease interceptor, maintained every 90 days. This broad definition includes various establishments like coffee shops and bakeries. For areas where traditional interceptors are impractical, such as historic downtown locations, the city permits alternative solutions like under-the-sink interceptors.
The city also enforces industrial pretreatment programs and is considering new clarifications and permits for specific food manufacturers. For example, one industrial user is installing a biodigester instead of a GI, which was a special request that was approved through the city. This was to combat their suspended solids and biological oxygen demand (BOD). This is one of many different alternatives the city is managing instead of working with outdated technology.
The City's Environmental Compliance Team, has implemented several effective strategies:
Enhanced FSE Compliance: Increased site visits and educational outreach, including encouraging voluntary waste manifest submissions, have improved compliance. Updated forms were created for inspections after outreach to other programs. Forms include information about the condition of interceptors, follow-up schedules for timely maintenance, alternative request forms etc.
Fixture Connections: Ensuring that all fixtures and drains are connected to grease interceptors through policy and building reviews, even if not yet mandated by ordinance. Environmental compliance is involved with new builds and tenant finish outs that involve plumbing connections to the city collection system. The program manager reviews the building plans to determine if all fixtures in the kitchens or processes are being captured with the submitted design. When the plans would not successfully prevent the introduction of potential FOG, revisions or alternatives are discussed with the user/contractor.
Collaborative Efforts: The city shares best management practices and program documentation with other jurisdictions.
Effective Tracking: Utilizing geographic data and maintenance records to prioritize inspections and manage FOG buildup effectively.
Communication: Rather than trying to get the managers of the FSE they have started reaching out to the property managers first. They also go to establishments with their FSE guidance information handy so that they can distribute it to staff on location even if a manager is not present.
Working with Other Jurisdictions/Departments: As part of their program restart, they reached out to numerous communities that surround the City to participate in live training for inspections. They also revisited all of the FOG program forms for inspection, NOVs, public education and outreach.
Success Stories:
Amanda worked directly with a business on historic main street to properly size and replace a grease interceptor. Alternate request forms were completed, and a device that met the needs was chosen.
Similarly, a local elementary school had a grease cistern that was no longer meeting code. Input from the city has opened the avenue of a cost-effective alternative to a concrete GGI as they are operating with a small capital improvement budget.