Friday, 26 January 2018 13:23

Today’s waste nourishes tomorrow’s landscapes

Houston Parks and Recreation Department employees feed the 65-foot City Hall Holiday tree into a wood chipper to create mulch that will nourish Houston soil for months to come. Houston Parks and Recreation Department employees feed the 65-foot City Hall Holiday tree into a wood chipper to create mulch that will nourish Houston soil for months to come. Photo by Elise Marrion


Snowfall, ice storms, and eight consecutive nights with temperatures below freezing — Houstonians experienced an uncommonly chilly start to 2018.

A deep freeze can complicate life in a city that rarely requires wearing a heavy coat, and Jack Frost is not always kind to the local trees and landscaping. As holiday trees are cast aside and foliage and frost-damaged tree limbs fall, January through March are busy months to tidy greenspaces and make way for spring growth.

Luckily, that valuable organic matter can get a second life as mulch and compost because the City of Houston Solid Waste Management Department runs one of the most robust green waste recycling programs in the nation. Through a partnership with Living Earth, the program diverts tons of organic materials from landfills and saves more than $1 million a year in disposal fees.

Recycling your tree and yard waste will be more important than ever this year. According to the Environmental Protection Agency, mulch and compost products play a critical role to help soil recover from floodwaters that can carry contaminants, deplete nutrients and damage the root systems that absorb storm runoff and prevent future erosion.

In addition to paper, plastic, aluminum, tree and yard waste curbside recycling, the city also has programs and partnerships to recycle building materials, mattresses, textiles, cartons, concrete, electronics, paint and household chemicals. Houston residents will be able to recycle glass and filmy plastic bags in 2019 thanks to a new recycling contract approved on Jan. 10.


Photo by Elise Marrion

SWMD resumed curbside tree and yard waste recycling on Jan. 2.

Curbside comeback

After a four-month hiatus to focus on household waste and Harvey storm debris, the city’s Solid Waste Management Department resumed yard and tree waste collection on Jan. 2.

SWMD kicked off the first green waste month of the year by feeding the 65-foot City Hall holiday tree into a wood chipper on Jan. 5, creating mulch that will return nutrients to soil. Mayor Sylvester Turner, Solid Waste Management Department, Houston Parks and Recreation Department and Living Earth leaders were present to fell the tree and encourage residents to recycle their holiday trees.

Sarah Mason, division manager for the city’s recycling and environmental services, said the collection schedule coincides with Christmas tree season. Odd numbered months are for tree and yard waste and even months are for junk waste.

“Tree waste is collected in odd months because we start the year by recycling thousands of holiday trees every year in January,” Mason said. “Untreated real trees make the perfect base for mulch products that will benefit local soil year-round.”


Photo by Elise Marrion

Lora Hinchcliff holds a slice of the City Hall Holiday Tree trunk.

Getting green for going green

Living Earth mulches holiday trees for free, but charges the city to process residential tree waste. Once that tree debris is mulched, the city earns 10 cents for every bag of Houston Mulch that Living Earth sells. The city also earns revenue from Living Earth for the grass, leaves and yard waste if it’s collected in approved compostable bags, Mason said. That revenue is used to fund the expansion of recycling program, she said.

In Fiscal Year 2016 and 2017, Mason said that the yard waste collection program saved the city about $200,000 each year in disposal costs, and earned about $75,000 in revenue. In the same fiscal years, the tree waste recycling program saved the city about $1 million each year in landfill disposal costs. Totals for each year were about the same, she said.

“In Houston, we have a year-round growing season, and we are a huge geographic area, so we produce a high volume of tree and yard waste,” Mason said. “For regular household waste collection, the city pays fees to dump materials at the landfill, but we pay significantly less to dump it at Living Earth than we would at the landfills.”

Lora Hinchcliff, municipal solutions manager for Living Earth, said Houston’s organic recycling program is a model for other cities to follow.

“Since 2009, the City of Houston alone has diverted over 348,000 tons of tree debris from landfills,” Hinchcliff said. “I work with well over two dozen other Texas municipalities, and Houston is a leader in its commitment to recycle 100 percent these materials into beneficial products for the environment.”

Hinchcliff said the city has diverted 129,000 tons of clean compostable organic material from landfills since it introduced the compostable bag yard waste recycling program in 2010.

She noted that recycling rates vary every year based on climate conditions and weather events. For example, mulch production is high when trees die during drought months. Mulch and compost output was less in 2017, because much of the tree and yard waste was contaminated by floodwaters.


Photo courtesy of Living Earth

Scott Estes, Living Earth Houston area manager, stands in front of a static pile compostable yard trimmings. Living Earth processes the feedstock through grinder after 2-3 months to break down the material.

What happens to your curbside green waste?

Once the city delivers tree debris to Living Earth, the material is processed through a horizontal grinder, aged, and re-screened to produce mulch made available in bulk or in bags sold at Living Earth locations and Houston area retailers.

When residents put grass, leaves and small trimmings in City of Houston-approved compostable bags, SWMD collects the bags and delivers them to Living Earth. Many of the bags are torn and damaged during transit, but Living Earth deposits the bags and loose material into a static compost pile. After a few weeks, the bags break down, and the pile is watered, turned and microbes go to work to naturally  finer texture and sold as U.S. Composting Council-certified organic compost.

“One of the reasons Houston’s organic recycling is so successful is because of the commitment of city leadership, collection crews and residents,” Hinchcliff said. “The translucent compostable bags make a big difference. The collection crews can see if the bags contain anything other than organic waste. The material that we receive is so clean that 100 percent of that material is recycled into compost.”


Photo courtesy of Living Earth

Estes shows the final product after the composting process is complete.

What’s the deal with compostable bags?

According to SWMD, less than 2 percent of plastic (polyethylene) bags are recycled, and they can take up to 100 years to break down in a landfill. Conversely, City of Houston-approved compostable bags, can begin to break down a few days depending on the manufacturing materials, brand, and exposure to heat and moisture. Bags with the City of Houston seal fully degrade within six months.

Unlike the paper leaf bags some cities use, City of Houston-approved compostable bags are translucent and resemble thin plastic trash bags. They are made from a resin using natural polymers from corn or potato starch, vegetable oils and other renewable resources. Look for the City of Houston-approved symbol on any compostable bag you buy. View a list of approved bags.

Mason said the compostable bags cost a little more to the consumer, but the ends justify the means. An alternative to buying compostable bags is grasscyling, or leaving your grass clippings on your lawn. Residents can also compost their own yard waste and organic kitchen scraps. The Houston Public Works Green Building Resource Center also hosts master composter certification courses and hosts an annual compost bin and rain barrel sale. Visit for updates on upcoming events.

“We’re always looking at research that compares different bags and ways to improve them,” Mason said. “We have an abundance of trees in Houston that produce an unbelievable amount of leaves. There is no reason for all of that to sit in a landfill.”



Tree and yard waste are collected in odd numbered months


What is tree waste?

“Clean” wood such as tree limbs, branches and stumps. Lumber, furniture and treated wood is not accepted.

What is yard waste?
Yard trimmings, grass clippings, small branches and leaves. They must be in city-approved compostable bags not weighing more than 50 pounds, and placed at the curb 3 feet away from the automated container for separate yard trimmings collection. Small branches may be put in bundles as long as each bundle is less than 4 feet in length and 18 inches in diameter and weighs less than 50 pounds. Work performed by a contractor must be removed by the contractor.

Benefits of Mulch: 

  • Insulates and moderates soil temperature;
  • Retains moisture and reduces the need to water;
  • Prevents weed growth; 
  • Improves soil structure and prevents soil compaction.


Benefits of Composting

  • Enriches soil, helping retain moisture and suppress plant diseases and pests.
  • Reduces the need for chemical fertilizers.
  • Encourages the production of beneficial bacteria and fungi that break down organic matter to create humus, a rich nutrient-filled material.

Source: Environmental Protection Agency

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