Subjects: Post landfill use/ life expectancy/plastic grocery bags
Questions:
Hello, I am just looking for a little information about landfills and am hoping that someone in your organization can help me out. This is what’s going on here in my region. Some local citizens along with the Sierra Club are pushing for a ban on the plastic grocery bags used by most grocery stores. A local survey found 80% against such a ban and 20% in favor.
Anyway, one of the supposed reasons for such a ban is that the plastic bags do not decompose in a landfill and essentially last forever. My response is–so what? As long as it is in a landfill there are lots of other things that will be there forever also. Isn’t that what a landfill is for?
I am a little familiar with the construction of a modern landfill, a good thick bottom liner, drains for liquids accumulation, gas vents, a good capping method, etc. All the modern stuff I am sure you guys are good at; when I was young, it was just dirt on the bottom and the top.
I am just not sure what is supposed to happen to the contents of the landfill over a period of time after it is closed, 50, 100, 500 years. Maybe you could give me some input. Also, what does society do with a completed landfill to put the area back to use after it is full, covered up and growing grass? Is it ever expected to be drilled or dug into for construction purposes?
I would really appreciate a response from you guys, even though you probably have lots bigger fish to fry.
Answers:
Thanks for your note, and for your interest in SCS Engineers. Bans on plastic bags and similar strategies such as taxing their use have been adopted by several communities, and the subject is controversial.
Personally, the best argument we’ve heard in support of trying to restrict the use of plastic bags is that the bags too often turn up along highways and waterways in the form of litter. Birds and other wildlife can become ensnared in the bags, and they can remain unsightly for a long time (unlike paper bags).
Now to your questions; our general opinion is that our goals for solid waste management are first and foremost to protect human health and the environment. If we can avoid throwing something like a plastic bag away, or if we can reuse the plastic bag for some other purpose, or if we can recycle the plastic bag, those are preferred to disposal.
If the plastic bags need to be disposed of, a modern landfill or solid waste-to-energy facility are safe and environmentally responsible means of disposal. As you say, a plastic bag might linger in a landfill for centuries, but the bags make up a small percentage of the volume of the solid waste disposed of in modern landfills.
Eventually, landfills can be redeveloped for other purposes, and many older landfills have been redeveloped. Organic materials in the landfill will decompose over time, but a substantial portion of the disposed waste material will remain, perhaps including small volumes of plastic bags. In my opinion, plastic bags in a landfill do not present a threat to human health or the environment.
Thanks again for contacting SCS Engineers.
Additional Information and Resources:
The Washington Post has had several articles and blog postings on the subject over the last few years:
Bag Fees — Declining Use of Bags
Plastic Bag Lobby — San Francisco Ban
By Kevin D. Yard, P.E., BCEE, Marc Rogoff, Ph.D., with contributions from SCS’ Environmental Consultants
In view of recent media coverage about the costs of recycling, perhaps it is time to take a “fresh look” at the compatibility of waste diversion and ultimate waste management, i.e., landfilling. Whereas some suggest that Zero Waste enthusiasts and Landfill Management professionals have counterproductive goals, through our recent experience with integrated waste management systems we have a newfound appreciation of the common ground of the two groups.
Zero Waste proponents espouse many important goals such as behavioral changes in consumers (e.g., reducing the generation of waste, minimizing the use of products that contain toxins, reducing energy consumption, etc.). Others, in the “No Burn/No Bury” ZW camp, suggest setting a goal at zero waste of resources achieved through measures such as: bans on disposal of materials that can be beneficially used, mandatory recycling programs to address hard-to-reach constituents, separate collection of food scraps, extended producer responsibility of hard-to-handle materials, etc. Some ZW enthusiasts have stated, “We put a man on the moon, so surely we can achieve ZW”.
On the other hand, many solid waste management professionals realize that landfills represent an important component of integrated solid waste systems and that other waste management options that are sometimes viewed as alternatives to landfills (e.g., material recovery facilities, composting operations, household hazardous waste collection programs, waste conversion and waste-to-energy plants, etc.) are more properly considered as complementary waste management tools. Further, most solid waste managers understand that landfills will continue to be required for residuals from other components of integrated waste management systems for decades to come.
While recognizing that recycling is presently common and an important component of modern waste management systems, particularly in large metropolitan areas, two questions remain:
Whereas in some areas, recycling can be a break-even proposition, in most areas, implementing recycling can cost from $0.50 to $3 per household, per month. One might ask with public school budgets being reduced, the nation’s infrastructure needing extensive improvements, and forecasted water shortages warranting major water resource projects, what is the most appropriate method for determining how the costs of recycling should be born?
Perhaps the answers lie in addressing recycling goals in a manner that makes economic sense depending on the conditions of each community or, more appropriately, each waste-shed. When viewing the magnitude of the investment in a modern-day municipal solid waste landfill, one can gain a greater appreciation for the need for properly managing and amortizing such investments. Like any investment in infrastructure, the public’s investment in disposal capacity should be valued and optimized in the interest of taxpayers. For instance, in areas with limited remaining disposal capacity and limitations for developing additional disposal capacity, investing in a more aggressive recycling program may be much more desirable and cost-effective than for areas with over 20 years of disposal capacity.
As prudent taxpayers, we need to work together to assure that the assets of waste management systems are optimized in a manner that protects the environment. This, of course, includes thoughtful consideration of recycling goals, which can contribute to a more cost-effective utilization of the available landfill capacity. As recycling enthusiasts provide an ongoing impetus for further waste reduction and enhanced recycling, optimization of waste diversion will continue to evolve. This evolution will be site-specific consistent with the variable impact of evolving waste management technologies and changes in the markets for recovered products. Given that the dynamics of each waste-shed can vary dramatically, many cities will benefit from a review of waste management alternatives. Based on our experience, it has been shown that such a review can not only result in an optimization of current assets, but also a plan for continued cost-effective solid waste service for many years in the future.
SCS’ professionals provide assistance to many municipalities across the U.S. by devising programs that address all aspects of the comprehensive waste management systems: waste collection, recycling, composting, waste conversion, and landfilling. SCS’ solid waste professionals stand ready to assist additional municipal managers upon request. Please visit our website at www.scsengineers.com, call or drop us an e-mail:
Kevin Yard, P.E., BCEE, Dallas, TX: , 817-571-2288
Marc Rogoff, Ph.D., Tampa, FL: , 813-621-0080
Greg McCarron, P.E., Suffern, NY:, 845-357-1510
Anastasia Welch, P.E., Overland Park, KS: , 913-681-0030
Michelle Leonard, Pasadena, CA, , 626-792-9593
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