The Future of Composting at K

“Campus Compost System Design” ENVS-398 Independent Study

Samantha Jolly (K’15)

Alicia Pettys (K’13)

Advised by Dr. Binney Girdler

Abstract

This document outlines the “Campus Compost System Design” independent study course’s proposed solution to Kalamazoo College’s need for a composting system to divert cafeteria food waste from the landfill in order to reduce waste, methane emissions, and tipping fees. Based on research about composting at other small liberal arts colleges, potential compost models, and a cost-benefit analysis, we propose the purchase of two Earth Tub systems and a food pulper to reduce the volume of the food waste. The Earth Tub is a fully enclosed composting vessel featuring power mixing, compost aeration, and biofiltration. Also included in this proposal are recommendations for the Earth Tubs’ location on campus, labor models, and operational work flow.

Table of Contents Page

A Guide to Reading this Document....... 1

Executive Summary...... 2

Introduction...... 3

-Problem definition

-Purpose

Compost Methods Research....... 5

-Method comparison conclusions

Earth Tub Composting System at K...... 9

-Overview

-Location

-Composting process

-Labor

-Labor flow

Cost Benefit Analysis...... 14

-Start-up costs

-Annual operational costs

-Cost reductions

-Return on Investment

Conclusion...... 18

-Acknowledgements

Bibliography………...... 20

A Guide to Reading this Document

Proposals like this can be difficult reading to tackle. Sometimes the important facts and sections are clear to the authors, but less clear to their audience. To make this more useful for everyone, here’s a quick guide to what’s in here and where to find it.

The proposal has five main sections:

Section 1: Overview of the ‘problem’

Section 2: Research on compost methods

Section 3: Implementing Earth Tubs at K

Section 4: Cost-benefit analysis

Section 5: Conclusion

So if you’re looking for:

●  A description of what we think composting at K could/should look like à Section 3

●  What this program would cost à Section 4

●  Proof that we actually know what we’re talking about à Section 2

●  Justification that composting is necessary à Section 1

Executive Summary

Kalamazoo College currently produces an average of 3.44 yd³ of food waste per week; extrapolated out for the 31 weeks that school is in session, this would create an approximate annual total of 136,422 lbs or 68.2 tons. From 2010 to early 2013, the College diverted this food waste from the landfill by transporting all pre- and post-consumer cafeteria food waste to Lake Village Homestead Farm. However, the program was ended in March 2013 due to lack of appropriate licensing with the Michigan Department of Natural Resources.

Since then, all College cafeteria food waste is being sent to the landfill. This costs the College $1,642 in tipping fees per year. Moreover, while the campus generates a significant amount of yard waste each year, there is no long term plan to manage it. A comprehensive plan could successfully manage all the College’s food and yard waste, offset current costs and assist in the reduction of the campus’ total solid waste, which the College committed to in its American College and Universities Presidents Climate Commitment (ACUPCC), which President Eileen Wilson-Oyelaran signed in 2007.

This document outlines the “Campus Compost System Design” independent study course’s proposed solution to Kalamazoo College’s organic waste issues. After developing a problem definition and describing the scope of our research and findings, we conduct a cost benefit analysis and suggest a solution. While we will summarize our methods and findings in this report, our full research can also be accessed online through the Kalamazoo College sustainability webpage.

Based on this research, our recommendation is that the College purchase two Earth Tub in-vessel composting systems and a pulper to reduce food waste volume. This system was chosen because of its technical simplicity, minimal labor requirements, minimal site and size requirements, and climatic factors. Additionally, our cost-benefit analysis showed that the Earth Tubs have the cheapest start up costs, most costs potentially offset, and thus best Return on Investment (ROI). The total sticker price for two Earth Tubs and a pulper is $33,191- 38,191, with additional annual operational costs of $162 - $398 plus $600 - $5,000 depending on the labor model chosen. Using the Earth Tubs also has the potential to reduce current annual costs by $2,837. Thus the expected Return on Investment (ROI) of the system is 16.0 - 20.8 years.

Section I: Overview of the Issue

Introduction

Waste in landfills has been identified by the US Environmental Protection Agency (EPA) as the single largest source of man-made methane released to the atmosphere in the United States. These landfill methane emissions have severe implications because methane is a potent greenhouse gas 21 times more effective at trapping heat in the atmosphere than carbon dioxide (CO2) (US EPA Region 9, 2011).

Landfills create methane gas because the waste is buried underground to seal it off and minimize leachate. [1]However, this means that the waste breaks down anaerobically (no oxygen) and with minimal moisture—the conditions that cause it to emit methane gas (USCC, 2011). Moreover, densely populated areas of the country are increasingly beginning to see their landfills fill up, creating new waste management challenges and causing a growing number of states to consider organic or food waste bans from the landfill (Hasek, 2012; Willard, 2013).

Fortunately, food and other organic wastes can be diverted from landfills and decomposed in ways that do not emit methane— and with significant impact. Food waste was the second largest category of municipal solid waste (MSW) sent to landfills in the United States in 2007, accounting for 18% of the waste stream at over 30 million tons of food waste (US EPA Region 9, 2011). Just like recycling for paper and plastics, food waste can also be diverted from the landfill and put to more productive uses through composting.

Composting is different than landfill processes because the organic waste decomposes with sufficient moisture and aeration, creating the conditions necessary for both aerobic and anaerobic bacteria to break down the organic waste while creating little to no methane (USCC, 2011). Moreover, the nutrients found in the final composted product make a great fertilizer. This presents the opportunity for a closed loop system: the nutrients found in the food waste generated by an institution can be recycled into fertilizer for plants growing on the same campus.

Currently, all Kalamazoo College cafeteria food waste is being sent to the landfill. Moreover, while the campus generates a significant amount of yard waste each year, there is no long term plan to manage it. A comprehensive plan could successfully manage all the College’s food and yard waste, offset current costs and assist in the reduction of the campus’ total solid waste, which the College committed to in its American College and Universities Presidents Climate Commitment (ACUPCC) in 2007.

Problem definition

Food Waste

Cafeteria food waste collection data from Winter Quarter 2013 shows the average total food waste generated per week was 4,421 lbs or 3.44 yd³. Extrapolating this average out to the whole year (31 weeks school is in session), the College creates approximately 136,422 lbs (68 tons) or 115 yd³ of cafeteria food waste a year. [2] Without the development of an alternative plan, this food waste will continue to be sent to the landfill, costing the school $1,642 per year and creating methane gas-- one of the most potent greenhouse gases.

Yard Waste

Moreover, the College has a significant amount of campus yard waste to manage. The campus generates 410 yd³ of leaves, light plant waste, wood chips, and stumps per year, which in previous years has either been delivered to Western Michigan University (WMU), transported and dumped at the Lillian Anderson Arboretum (the Arb/LAA), or taken to a private company. However, none of these are a permanent, long term solution. The College can no longer transport to WMU because of the construction of new facilities on their campus; transferring yard waste to the Arb has created stewardship issues such as invasive species because the yard waste is simply dumped, not managed through a process like windrow composting. Nonetheless, these piecemeal solutions have an associated annual cost to the College.

Purpose

To begin addressing these issues, the “Campus Compost System Design” independent study course sought to find the most suitable method of managing the campus’ organic waste, considering not only the amount of food and yard waste generated but also feasible program management structures, Kalamazoo College’s particular annual cost savings, and sustainable funding sources for necessary equipment and staffing.

Section 2: Research on Compost Methods

To determine the optimal food waste diversion method for Kalamazoo College, we began by studying composting programs at other universities. These included all schools in the Great Lakes Collegiate Association (GLCA), of which Kalamazoo is a part, and top-ranked schools in the 2013 Recyclemania competition[3]. Based on this research, we determined the full range of potential composting methods, including windrows, Earth Tub/Earth Flow, Rocket Composter, pulper or dehydrator, vermicompost, or a private company.

For each of these potential methods, we investigated factors such as initial and lifetime cost, acceptable inputs, size and location, and feasible labor models and labor flows. Some models include the additional use of a pulper: a garbage disposal-like machine designed that reduces the volume of food waste. These pulpers are necessary for some models (as indicated) because reduction of food waste volume makes the smaller capacity of these models feasible. Our full research can be accessed online in the Compost Methods document and is summarized in Table 1 below.

Table 1. Compost Methods Evaluation

This chart summarizes our comparison of potential composting methods.

Method / Advantages / Disadvantages / Approximate Start-up cost
Windrows / -Would make use of an already heavily impacted area (the Lillian Anderson Arboretum stump dump)
-Effective in areas with freezing winter temperatures
-No issues of finding space
-Regular turning and mixing speeds up process
-Creates compost usable as fertilizer
-Manages yard waste / -A site manager would have to be employed to manage area
-Waste would be transported to Arb-12 miles round trip
-Front end loader or windrow turner necessary
-Very easy to mismanage
-labor and time intensive creation of site / ≈$70,000 + paid employee to manage the sight year round
2 Earth Tubs + Pulper / -Most cost effective and comprehensive system
-Minimal transportation
- Minimal labor: small time commitment and can be operated by one person
-Manages yard waste
-Creates compost usable as fertilizer
-Time efficient (product is processed in 2-3 weeks) / -Would need at least two vessels, creating space/ location issues / $37,000
Earth Flow
(larger model of Earth Tub) / -Minimal transportation and labor cost
-Simple to manage
-Manages yard waste / -Larger size which creates issues of location
-Double the initial cost / $60,000-$65,000
Dehydrator / -Minimal transportation
-Minimal labor: small time commitment and can be operated by one person / -Final product is soil amendment that must be composted with other materials
-Cannot manage yard waste / $30,000
Rocket Composter + Pulper / -Minimal transportation
-Minimal labor: small time commitment and can be operated by one person
-Manages yard waste
-Creates compost usable as fertilizer
-Time efficient: processed in 2-3 weeks / -Requires storage under cover and a hard standing base / $65,000
Rocket Composter
(larger model) / -Manages yard and food waste / -Requires storage under cover and a hard standing base
-Size: larger than Rocket Composter needed w/ pulper, creating issues of space
-Double the cost of the smaller model with pulper / $101,100
Private Company
(food waste only) / -No need for space or student/staff labor / -No educational component for K students (i.e. no student collaboration/ is not visible to students)
-Does not solve yard waste issue
-No eventual payback on investment / $5,000/ year
Private Company
(food and yard waste) / -Eradicates yard waste dumping in Arboretum / -Cost prohibitive over time
-No eventual payback on investment
-No educational component / $12,000/year
Vermicomposting / -No turning necessary
-Various models accommodate space needs / -Cannot be sustained through the winter because worms may would die of hunger / $30,000-$40,000

Method Comparison Conclusions

Upon comparison of all of the models, it became clear that the purchasing two Earth Tubs and Pulper was the best option for Kalamazoo College. Although there were other options that had smaller initial costs, these methods were unsuitable for the College’s particular calendar, climate, or landlocked location.

Windrows

Windrows involve high start up costs (including paving the entire area necessary, purchasing a tractor/front end loader and windrow turner attachment), intensive labor requirements (full time staff member) and the level of expertise needed to manage the windrows (climatic factors, appropriate material mix, troubleshooting for dynamic chemical processes). Moreover, because the Arb is located on the way out of town on West Main Rd, the cost for daily food waste and frequent yard waste transportation would be substantial.

Earth Flow

The Earth Flow is essentially a larger version of the Earth Tub. Due to its high price without any different benefits than two Earth Tubs, this option was deemed unfeasible.

Dehydrator

The dehydrator is not a composter. It is, however a machine capable of reducing waste by 1/9th into a soil amendment that can either be thrown away or composted further. While this option looks attractive due to its low sticker price, it would not be the most cost effective in the long run. A dehydrator would not have a Return on Investment because cost reductions that apply to other models, such as replacing some fertilizers with compost, do not apply to the non-composting Rocket. Also, the final product of this machine would either have to be thrown away, still contributing to the issues associated with dumping landfills, or composted, which would necessitate the use of another composting method.[4]

Rocket Composter

We examined two possible models of the Rocket Composter that could be used on campus. The biggest difference in these two models are their size. The smaller model could handle all of the cafeteria food waste with the use of the pulper, and the larger model could handle all of the cafeteria food waste without the use of the pulper. Either model is significantly more expensive than the two Earth Tubs + Pulper. The Rocket Composter is also significantly larger than other systems, and requires a structure with a roof to be built around it. This, in combination with the high price, led us to discount either Rocket Composter system as a viable option for Kalamazoo College.