2023 Excellence in Environmental Engineering and Science™ Awards Competition Winner

Grand Prize - Environmental Sustainability

Reducing Our Carbon Footprint: The Sanitation Districts' Greenhouse Gas Reduction Initiatives

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

Entrant Profile

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, 49 pumping plants, and 11 wastewater treatment plants) that treats about 400 million gallons of sewage per day. The agency also operates and maintains a regional solid waste management system (which includes two active landfills, two energy recovery facilities, and three materials recovery facilities.

For decades, the Sanitation Districts and its partners have undertaken activities that reduce greenhouse gas (GHG) emissions to help protect the environment and provide for a more sustainable world. Most of these initiatives produce green power which reduces use of fossil fuels, a main contributor to global GHG emissions. Another key initiative is recycling water, which reduces the need to import water, the largest single energy use in the State of California. “Reducing Our Carbon Footprint: The Sanitation Districts’ Greenhouse Gas Reduction Initiatives” highlights our major initiatives.

The Sanitation Districts are proud to announce we have achieved carbon neutrality for the 2021 calendar year. We continue to look for more ways to reduce GHG emissions and help make our community more sustainable.

Project Description

Reducing Our Carbon Footprint: The Sanitation Districts’ Greenhouse Gas Reduction Initiatives

The Sanitation Districts’ mission is to protect public health and the environment. Over the years, our agency has evolved to meet society’s changing environmental needs.In the1920s, we focused on collecting and treating sewage for the region. Today, a hundred years later, we convert waste—whether it be sewage or solid waste—into resources while still doing our part to protect the environment.

We now face the environmental challenge of global climate change, which is the result of increasing greenhouse gases (GHGs) in our atmosphere. Human activity, especially the combustion of fossil fuels, creates GHGs at a higher rate than naturally occurs. According to the U.S. Environmental Protection Agency, our current concentrations of the most prevalent GHGs (carbon dioxide, methane, and nitrous oxide) “are unprecedented compared with the past 800,000 years.” This increased amount of GHGs in our atmosphere traps more of the earth’s heat, causing an overall warming, which changes weather patterns. Scientists predict that rainfall will come in more intense bursts that are more likely to cause flooding. The strength of hurricanes is largely fueled by ocean temperature. Thus, warmer oceans are expected to lead to stronger hurricanes. Events intensified by climate change such as wildfires, droughts, flooding, heat waves and sea level rise can have devastating and costly consequences like loss of life, loss of property, jeopardized water supply and increased air pollution.

Reducing The Districts Greenhouse Gas Emissions

For decades, the Sanitation Districts have undertaken activities to reduce waste and maximize the use of renewable resources. These activities have also reduced GHG emissions. Most of the Sanitation Districts Greenhouse Gas Reduction Initiatives produce green power which reduces use of fossil fuels, a main contributor to global GHG emissions. Another key initiative is recycling water, which reduces the need to import water and the associated energy required to import water, the largest single energy use in California. Seven initiatives are highlighted and evaluated as part of our comprehensive program.

water recycling
biogas-to-electricity
green waste diversion
food waste diversion
commodities recycling
biosolids management
alternative fuels

Water Recycling

Importing water to Southern California requires a vast amount of electricity. By recycling water, the Sanitation Districts reduce the need for imported water and the GHG emitted to convey this water. In 2021, the Sanitation Districts recycled 113,000 acre-feet of water, which avoided 52,000 metric tons of carbon dioxide being released to the atmosphere. This GHG avoidance is equivalent to driving our cars 130 million miles less.

Biogas-to-Electricity

The Sanitation Districts operate three gas-to-electricity facilities, which use biogas generated from anaerobic decomposition of organic material in landfills and wastewater treatment plants. Biogas is rich in

methane, a potent GHG, that can be a valuable source of energy. These facilities reduce GHGs by avoiding carbon dioxide emissions from traditional electricity generation processes, such as natural gas and coal-fired power plants.

In 2021, Sanitation Districts facilities generated a combined 45 megawatts (MW) of green electricity, enough energy for 23,000 homes per year, thereby avoiding 190,000 MTCO₂e of GHG emissions.

Green Waste Diversion

The Sanitation Districts recycle green waste, producing mulch and compost. This reduces methane generation from landfilling, decreases soil erosion, and reduces fertilizer and herbicide use. In 2021, the Sanitation Districts diverted 77,000 tons of green waste from landfills, which avoided 14,000 MTCO₂e of GHG emissions. This is equal to avoiding the burning of 15 million pounds of coal.

Food Waste Recycling

California mandated that organic waste (primarily food waste) be diverted from landfills. As a result, the Sanitation Districts has developed its food waste recycling program to help member cities comply with this law. In 2021, the Sanitation Districts diverted approximately 78,000 tons of food waste from landfills. Food waste diversion reduces GHG emissions by reducing methane generated through organic waste decomposition in landfill and carbon dioxide emissions from heavy equipment used during the landfilling process. By diverting food waste from landfills, the Sanitation Districts avoided approximately 42,000 MTCO₂e of GHG emissions. This reduction is equal to avoiding the use of 5 million gallons of gasoline.

In addition, the Sanitation Districts recycled food waste into green power, which further reduces GHG emissions.

Commodities Recycling

The Sanitation Districts and its partners divert recyclables from landfills through the Downey Area Recycling and Transfer Facility and the Puente Hills Materials Recovery Facility. Recycling reduces GHG emissions by enabling products to be created using previously manufactured materials rather than raw materials. In 2021, the Sanitation Districts diverted 25,000 tons of recyclables from landfills, which avoided 59,000 MTCO₂e of GHG emissions. This reduction is equal to avoiding use of 6 million gallons of diesel.

Biosolids Management

Biosolids are a by-product of the wastewater treatment process and are rich in nutrients. In 2021, approximately 80% of all biosolids generated by the Sanitation Districts were recycled through direct land application or composting. The recycling of biosolids decreased the use of synthetic fertilizer and reduced GHG emissions by 2,500 MTCO₂e. This reduction is equal to avoiding the conversion of 17 acres of forest to cropland.

In addition to reducing GHG emissions, biosolids recycling also helps soil retain moisture, which reduces water use.

Alternative Fuels

The transportation sector is a major contributor of GHG emissions due to the burning of fossil fuels. In addition to GHG emissions, vehicle exhaust is responsible for the formation of smog, which can harm human health. In 2021, by building charging stations, transitioning to electric vehicles, and utilizing alternative fuels, the Sanitation Districts reduced GHG emissions by 3,400 MTCO₂e. This reduction is equivalent to removing 730 passenger vehicles from the road per year.

Summary

The combined GHG reduction from these initiatives in 2021 was over 362,000 MTCO₂e. These initiatives have resulted in the Sanitation Districts achieving carbon neutrality for the 2021 calendar year. Nonetheless, we continue to look for more ways to reduce GHG emissions to help protect the environment and provide for a more sustainable world.

Click images to enlarge in separate window.


2023 marks the Sanitation Districts 100-year anniversary of service. As we celebrate achievements, we recognize that managing both wastewater (sewage) and solid waste (trash) provides carbon reduction opportunities. For example, we can divert organics from the solid waste side of our operations to the liquid waste side of our operations and in doing so reduce fugitive emissions, while generating renewable energy and fuel. (Sanitation Districts' service area in Los Angeles County, CA).	The Sanitation Districts seeks opportunities to protect the environment and provide resources to the communities we serve. In 2009, we restored a 17-acre freshwater marshland that is open to the public. (Bixby Marshland in Carson, CA)

Marshlands help protect our regions resources. Marshlands are home to 43 percent of listed species. They provide habitat for all types of life. We planted 124 Torrey pines, 60 Arroyo Willows, 84 Red Willows, 85 Black Willow trees, 90 Cottonwood trees, 70 Sycamore trees that sequester 23,000 pounds of carbon dioxide annually – and provide enough oxygen for more than 1,000 people just in these 17 acres. (Bixby Marshland in Carson, CA)	Importing water to Southern California requires a vast amount of electricity. The State Water Project conveys water throughout the state and is our state’s largest electricity consumer. By recycling water, the Sanitation Districts reduce the need for imported water and the GHG emitted to convey this water. In 2021, the Sanitation Districts recycled 113,000 acre-feet of water, which avoided 52,000 metric tons of carbon dioxide equivalents MTCO2e in GHG emissions. (Recycled water recharging aquifers in the San Gabriel River Spreading Grounds, in Whittier, CA). This reduction is equal to 130 million less miles driven by cars.

Rapid growth along with our arid climate led to limited water resources in our region. The groundwater in the area was being over pumped. Something clearly had to be done, so in 1949 and again and in 1958 we wrote reports that helped verify the feasibility of reclaiming wastewater. (Recycled water from the San Jose Water Reclamation Plant, in Whittier CA)	Breakthroughs in water treatment technology over the next several decades have led to an increasing demand for high quality recycled water. (Recycled water from the Palmdale Walter Reclamation Plant is used to irrigate crops, in Palmdale, CA)

LA County generates 21 million tons of waste per year. Almost 9 million tons is disposed in landfills. About 9 million tons is buried in landfills (Scholl Canyon Landfill in Los Angeles, CA)	One third of the landfilled waste is organic. This is equivalent to the mass of 45,000 blue whales. (organic green waste at the Scholl Canyon Landfill in Los Angeles, CA)

In 2021, the Sanitation Districts diverted 77,000 tons of green waste from landfills, which avoided 14,000 MTCO2e of GHG emissions. This reduction is equal to avoiding the burning of 15 million pounds of coal. (organic green waste diversion operations at the Scholl Canyon Landfill in Los Angeles, CA)	In 2021, Sanitation Districts facilities generated a combined 45 megawatts (MW) of green electricity. This production avoided 190,000 MTCO2e of GHG emissions. This reduction is equal to emissions from providing energy for 23,000 homes per year. (Puente Hills Gas-to-Energy facility produces green energy from landfill gas in Whittier, CA)

In 2021, the Sanitation Districts diverted approximately 78,000 tons of food waste from landfills. Food waste diversion reduces GHG emission by reducing methane generated through organic waste decomposition in landfill and carbon dioxide emissions from heavy equipment used during the landfilling process. By diverting food waste from landfills, the Sanitation Districts avoided approximately 42,000 MTCO2e of GHG emissions. This reduction is equal to avoiding the use of 5 million gallons of gasoline. (food waste diversion Puente Hills Materials Recovery Facility in Whittier, CA)	Well managed landfills transition into community resources. Los Angeles County Department of Parks and Recreation is partnering with the Sanitation Districts and working with the community to plan for the future of the 1,365-acre Puente Hills Landfill. (the gas collection system at the Puente Hills Landfill in Whittier, CA part of the environmental controls operated by the Sanitation Districts)

In 2021, the Sanitation Districts diverted 25,000 tons of recyclables from landfills, which avoided 59,000 MTCO2e of GHG emissions. This reduction is equal to avoiding use of 6 million gallons of diesel. (the automated sorting line at the Puente Hills Materials Recovery Facility in Whittier, CA produces high purity recyclables)	In 2021, approximately 80% of all biosolids generated by the Sanitation Districts were recycled through direct land application or composting. The recycling of biosolids decreased the use of synthetic fertilizer and reduced GHG emissions by 2,500 MTCO2e. This reduction is equal to avoiding the conversion of 17 acres of forest to cropland. (Tulare Lake Compost in Kettleman City, CA)

Our largest water reclamation plant is energy self sufficient due to renewable biogas generation and efficient operations. (The Total Energy Facility in Carson, CA converts renewable biogas into electrical power for use on-site to operate our facilities)	In 2021, by building charging stations, transitioning to electric vehicles, and utilizing alternative fuels, the Sanitation Districts reduced GHG emissions by 3,400 MTCO2e. This reduction is equivalent to removing 730 passenger vehicles from the road per year. (Sanitation Districts Heavy Duty Green Fleet Vehicles in operation at the Puente Hills Materials Recovery Facility in Whittier, CA)

Since operations have achieved energy self sufficiency, the additional methane generated from food waste recycling had to be converted into another resource. So the Sanitation Districts make affordable, renewable, clean fuel available to the communities we serve. Currently renewable natural gas is dispensed to cars and trucks at a nearby fueling station at a cost of $3 per gallon gasoline equivalent. This biogas reduces the need for fossil-fuel natural gas and reduces greenhouse gas (GHG) emissions. (Clean Energy Fuel Station at the Joint Water Pollution Control Plant located in Carson, CA)	A Sanitation Districts’ employee charges one of the zero emissions electric fleet vehicles. (at the Joint Administration Office in Whittier, CA)