Backyard Composting/Grass Mulching vs Export: Comparative Costs

Contact: Thomas Outerbridge


The Department of Sanitation (DOS) has proposed eliminating the backyard composting and grass mulching program education run by the Botanical Gardens. In fact, the Botanical Garden program provides cost effective waste diversion, when compared with current export costs.

Since 1993, the four Botanical Gardens combined have received about $1.2 million/year to provide citywide education aimed at promoting backyard composting by residents, on-site composting by institutions, and grass mulching by lawn-owners and landscapers.

It is difficult to measure how much food and yard waste is not set out for collection by DOS as a result of the program. However, certain impacts can be roughly quantified. The following are direct outcomes of the ongoing efforts of the Botanical Gardens under this program:

The Housing Authority (NYCHA) has adopted grass mulching as standard practice, and thus no longer bags and sets out for collection 8,000 to 15,000 tons of grass clippings a year (according to DOS reports). This practice equals savings of $1,040,000 to $1,950,00/year (based on $130 per ton for waste collection/export), and alone justifies the entire program.

NYCHA operates on-site leaf composting facilities at many of its locations, handling 6,500 cubic yards of leaves (according to DOS reports). This practice equals savings of $105,635 per year.

More than 10,000 NYC households have purchased backyard compost bins and instruction on their use. If one half of these households compost at rates measured by DOS, this correlates to approximately 325 tons/year of food waste now being managed now by these households. This practice equals savings of $42,250 per year.

Over the past 3 years, the Gardens have provided technical assistance and information on

backyard/on-site composting and grass mulching to more than 70,000 New Yorkers, more than 100 institutions and dozens of landscapers. Using very conservative figures on participation, the resulting practices probably divert several thousand tons per year from the waste stream. Every thousand tons diverted equals savings of $130,000 per year.

Less quantifiable benefits coming out of the Botanical Garden program include the 1,500 teacher workshops conducted over the past 3 years, and the distribution of finished compost to tens of thousands of residents and hundreds of community gardens across the City.

Program Expansion

Rather than contemplate cutting the successful composting and grass mulching education

program, the City should look to expand it and the practices it promotes. Specifically, the City should cease collection of grass clippings.

Bans on grass collection have been successfully implemented by many, far more suburban, communities across the US. Such a ban was proposed for NYC in the City's 1992 Solid Waste Management Plan, which recommended for FY93 the following:

"Adopt rules halting the municipal collection of mown grass." (1992 NYC SWMP Ch.19)

Through public hearings at the time, DOS received feedback from the public and local elected officials that education was required before adopting such a rule. Since that time, 10 years ago, DOS has been conducting constant citywide education. Educational efforts include literature, personal instruction, web pages, workshops, seminars and demonstration sites, all providing information on grass mulching practices and techniques, equipment alternatives, and the moisture, nutrient and labor-saving benefits of grass-cycling.

New Yorkers generate an estimated 78,000 tons/year of grass clippings. Based on $130 per ton for waste collection and export, a grass collection ban would provide savings of $10,140,000. The Botanical Garden program budget could be tripled to enhance education and outreach accompanying such a ban, and it would still generate savings of more than $7,000,000 per year.