2021 Excellence in Environmental Engineering and Science™ Awards Competition Winner

Superior Achievement

Category Entered: Environmental Sustainability

Sustainable Green Fleet: Clean Fuel for LA Today

Entrant: Los Angeles County Sanitation Districts
Engineer in Charge: Robert C. Ferrante, P.E., BCEE
Location: Los Angeles, California
Media Contact: Wendy Wert, P.E., BCEE

Entrant Profile

LACSD

Figure 1: Material handler with smart hydraulics which reduces fuel consumption.

Figure 2: Sanitation Districts fuel usage (2016 to 2020).

Figure 3: CNG powered vacuum/jetter sewer cleaning truck.

Figure 4: Sanitation Districts Food Waste to renewable energy program.

Figure 5: Mean Green Rival electric mower.

Figure 6: Maintenance on RNG powered transfer truck.

Figure 7: DC fast charging stations at the Sanitation Disticts main office.

The Los Angeles County Sanitation Districts (Sanitation Districts) are a regional public agency that serves the wastewater and solid waste management needs of 78 cities and unincorporated areas in Los Angeles County. The agency protects public health and the environment and, in doing so, converts waste into resources like recycled water, green energy and recycled materials.

The agency operates and maintains a regional wastewater collection system (which includes approximately 1,400 miles of sewers, 48 pumping plants, and 11 wastewater treatment plants) that treats about half the County’s wastewater or about 400 million gallons of sewage per day. The recycled water produced by our treatment plants is beneficially reused at more than 950 sites, which contributes to a more sustainable Southern California.

The agency also operates and maintains a regional solid waste management system (which includes two active landfills, two energy recovery facilities, three materials recovery facilities, and one recycle center) that accommodates about one-fourth of the County’s solid waste management needs.

The Sanitation Districts utilize an extensive fleet of vehicles and off-road equipment to provide its essential services. Historically, the agency’s fleet was powered by fossil fuel that, when combusted, produces greenhouse gases that contribute to global climate change. In 2015, the agency began its “Sustainable Green Fleet: Reducing Our Carbon Footprint” program to reduce greenhouse gas impacts from its fleet. The program has resulted in the agency electrifying some of its fleet, utilizing renewable fuels, and producing renewable vehicle fuel.

Project Description

Sustainable Green Fleet: Reducing Our Carbon Footprint

The Los Angeles County Sanitation Districts (Sanitation Districts) rely on a fleet of 687 on-road vehicles, 85 utility carts, and 354 pieces of off-road equipment to help provide regional wastewater and solid waste management. In 2020, the agency’s vehicles travelled 4,151,990 miles and their off-road equipment was operated over 140,000 hours. The vehicles and equipment used to perform the agency’s essential duties have historically relied on fossil fuels (gasoline and diesel). Fossil fuel combustion is the biggest source of human-caused greenhouse gas (GHG) emissions in the United States, which can negatively impact human health and the environment. Thus, the Sanitation Districts have been moving to a green fleet. Already, this transition has reduced the agency’s GHG emissions, including a 43% reduction in fossil fuel use in 2020 alone. Improvements have been achieved by transitioning to alternative and renewable fuels; using technology and data to optimize service and reduce fuel consumption; and purchasing more fuel-efficient vehicles and equipment with hybrid technologies (see Figure 1).

Over the past five years, the Sanitation Districts have reduced their fleet fuel consumption from 1.13 million gallons per year to 840,000 gallons in 2020. That’s a 25% reduction (see Figure 2). Not only has fuel consumption been reduced, but renewable fuel usage has increased from 3% in 2016 to 53% in 2020. Increasing the use of Renewable Natural Gas (RNG) and Renewable Diesel (RD) has reduced GHG emissions.

Transitioning to alternative and renewable fuels has required a lot of research and work, including verifying fuel capacity; adding fuel storage tanks without restricting operation or visibility; designing and installing new fueling infrastructure; and training staff on the new maintenance and repair procedures.

Compressed Natural Gas (CNG)

The Sanitation Districts have been using CNG vehicles over the past 20 years. The agency has 91 vehicles powered by CNG, which represents 13% of their on-road fleet. Nineteen are heavy-duty trucks, which have certified near-zero emission engines. This is the cleanest commercially available diesel technology today.

Over the past five years, the Sanitation Districts entire fleet of vacuum/jetter sewer cleaning trucks have transitioned from diesel to CNG (see Figure 3). The trucks are critical for routine sewer maintenance and emergency response to sewer overflows. Therefore, a dependable source of fuel is a must. One challenge was finding space for the additional CNG storage tanks on trucks that are already loaded with other equipment.

The CNG station at the Puente Hills Materials Recovery Facility was upgraded, making the station faster and more reliable. In summer 2021, the agency will install new CNG fueling infrastructure and upgrade an existing CNG fueling infrastructure. These improvements will provide fast and reliable fueling for the growing fleet of CNG vehicles. The CNG station at the agency’s largest wastewater treatment plant, the Joint Water Pollution Control Plant (JWPCP), will be upgraded and expanded next.

Food Waste to Renewable Natural Gas (RNG)

Since 2016, the Sanitation Districts have been recycling food waste into green energy to help their member cities meet state organic waste recycling requirements. In 2020, this system was expanded to produce renewable natural gas, which is used to fuel vehicles. Waste haulers bring food waste slurry to JWPCP, where the food waste is anaerobically digested and converted to biogas. Some of the biogas is used at a power plant, which makes the JWPCP essentially energy self-sufficient. The remainder is sent to a biogas purification system that produces renewable natural gas that is dispensed at a nearby Sanitation Districts fueling station, which is also open to the public. This biogas reduces the need for natural gas and reduces greenhouse gas emissions. By the end of 2021, the vast majority of the CNG dispensed at this station will be RNG (see Figure 4).

Electric Vehicles (EVs)

The Sanitation Districts are in the process of electrifying their fleet. Over the past three years, the agency has purchased 48 electric cars and four hybrids, which has reduced fossil fuel consumption by more than 26,000 gallons per year. To support the EV fleet, the Sanitation Districts have installed 84 EV charging stations. At most facilities, the EV chargers are used by agency vehicles, employee vehicles and the public. In 2020, the Sanitation Districts also purchased their first fully electric zero-emission ride-on mower, the Mean Green Rival (see Figure 5).

Renewable Diesel (RD)

Although most Sanitation Districts on-road vehicles are being transitioned to alternative fuels like CNG and electricity, the agency still needs off-road equipment that is only powered by diesel. The Sanitation Districts started using RD in September 2018. This fuel is produced from waste fats, oils and greases. RD reduces GHG emissions by about 75% and produces significantly less particulate matter and NOx (a common air pollutant) than diesel. Last year, over 80% of the agency’s diesel usage was RD. This year, the agency is targeting close to 100%.

The agency is currently saving $0.24 per gallon compared to fossil-based diesel. Because RD burns cleaner, RD usage has extended maintenance intervals on engines. By summer 2021, the agency will have used over one million gallons of RD resulting in a cost savings of $193,000 and a reduction of over 7,600 metric tons of GHG emissions. That is equivalent to removing 4,260 cars from the road or planting more than 517,000 trees.

Maintenance

The transition to alternative fuels has required the agency to review and adjust maintenance practices. With EVs, there is no internal combustion engine, which means no oil changes. Mechanics and service crew workers have adapted to the increased electronics, smart hydraulic systems and transmissions, different types of fuel systems, and the need for pressure vessel inspections.

What is Next?

The Sanitation Districts’ transition is not complete. The agency is focused on expanding the EV charging network at its facilities to meet growing needs. This expansion will require a greater number of DC Fast charging stations to support future medium- and heavy-duty EVs. The Sanitation Districts is committed to further protecting the environment by reducing its carbon footprint and increasing its production of renewable energy for the region.

Click images to enlarge in separate window.


In 2020, a biogas purification system was constructed to produce renewable natural gas that is dispensed to cars and trucks at a nearby fueling station. This biogas reduces the need for fossil-fuel natural gas and reduces greenhouse gas (GHG) emissions.	DODA bio separator is essentially a blender that separates organics and inorganics and generates a food waste slurry that is loaded into tankers. Approximately 30 tons per day of food waste slurry is processed and delivered to JWPCP for disposal but the system has a capacity of 165 tons per day. The slurry receiving facilities increase the Districts’ capacity to process up to 600 tons per day of food waste slurry! We are currently receiving an average of 250 tons per day. Prepandemic, we saw a steady rise to about 350 tpd. The result of adding these facilities will generate a 1,000 scfm more of excess biogas!

Food Waste is recycled using a combination of solid waste and wastewater facilities. Source separated food waste from local restaurants and grocery stores is pre-processed at the Puente Hills Materials Recovery Facility then digested at the Joint Water Pollution Control Plant.	We are feeding 5 digesters. The maximum amount of food waste able to be fed into each of the five is still 62tpd, or 20,000 gallons to maintain adequate hydraulic retention time, bringing the total capacity to 310 tons per day at the new food waste receiving station. Slurry receiving facilities will generate up to 1,000 scfm of extra biogas. The Total Energy Facility already has the gas they need.

A Sanitation Districts’ employee charges one of the zero emissions electric fleet vehicles at the Joint Administration Office in Whittier, CA.	Over the past five years we have been able to reduce our fuel consumption from 1.13 million gallons per year to only 840,000 gallons in 2020. That’s a 25% reduction! Not only has overall fuel consumption been reduced, but at the same time the percentage of renewable fuels has increased. For example, the renewable fuels, supplying the Sanitation Districts fleet, transitioned from 3% in 2016 to 53% in 2020.

At Joint Water Pollution Control Plant we are purifying the biogas produced from the treatment plants digestors and dispensing it at CNG station. This is a great example of how the Districts are converting waste into resources and how those resources can be beneficially used to power our fleet.	In 2020, we purchased our first fully electric zero-emission ride-on mower, the Mean Green Rival! Some of you may have seen this in operation, maintaining the lawns at JAO. Commercial lawn and garden equipment typically operate on either diesel or gasoline fuel. This is just another example of how we are electrifying our assets to reduce air pollutants.

We started using Renewable Diesel in September 2018, which is produced from waste fats, oils, and greases. RD reduces GHG emissions on average by 75% compared to use of fossil-based diesel. Add to the fact that particulate matter and NOx emissions are also significantly reduced. Last year over 80% of our diesel usage was Renewable Diesel. This year we plan to get closer to 100%.	The transition to alternative fuels has required us to review and adjust our maintenance practices. With EVs, there is no longer an internal combustion engine. This makes oil changes a thing of the past. Mechanics and service crew workers have had to acquire new skills to adapt to the increased electronics, smart hydraulic systems and transmissions, different types of fuel systems, aftertreatment emission systems, and requirement for pressure vessel inspections.

Our work is not done. Late last year Governor Newsom announced that it is the goal of California that 100% of medium- and heavy-duty vehicles in the State be zero emission by 2045 and to transition to 100% zero-emission off-road vehicles and equipment by 2035. Mandates like this supported by funding for research, development, and early adoption expediate the commercialization of the technology. This will help support the Districts transition to a greener fleet in a cost-effective manner. We will continue working with the Energy Recovery Section to expand the use of renewable energies generated internally for our vehicles and equipment to displace fossil fuels. A good example of this is the food waste to vehicle fuel project.