FEASIBILITY STUDY DESIGN APPROACH
Design Method
The design method for this project was to produce quality compost while keeping the local environment unpolluted including a nearby stream and maintaining a reasonable cost. The key to producing quality compost started with coming up with a volume based mixture including at least pre-consumer food waste and chicken litter. The compost recipe needed to accomplish a carbon to nitrogen ratio close to 30 to 1 ratio while maintaining a moisture content within the range of 45% to 55%. The recipe was found by averaging carbon to nitrogen ratios together and moisture contents of the composting ingredients on weight bases and then converting this ratio to a volume basis. After the recipe was created, a sufficient size composter was found to withstand the weight and volume needs of the daily food waste being provided along with other ingredients needed for the recipe. The cycle of the compost needed to be determined as well such as time in the composter and the curing period. The next step was to compute the amount of area needed to store ingredients for compost, curing of compost, and final compost. These were all based on necessary demand of ingredients and curing time as well as the amount of final storage needed. The storage needed to be kept protected from the environment and local creek. The team had to decide what type of storage was going to be used and how they were going to be separated. The final step of the design was to create a site containing the composting facility that was accessible, environmentally friendly with best measurement practices, and could be expanded on if need be. For more detail on the project, a link is found below that will go to the design report.
Design Solution
The composting recipe developed for this project was a 4:5:1 volume based mixture including pre-consumer food waste, chicken litter, and sawdust. This recipe produced a carbon to nitrogen ratio of 30.5:1 and moisture content of 52%. For on-site storage of the composting ingredients, curing compost, and final compost will be stored in bins with 5 feet tall concrete walls. Pre-consumer food waste will be stored in an 8'x6' storage bin to accommodate a weeks worth of food. Sawdust will be stored in an 8'x4' bin to accommodate three weeks worth of sawdust. Chicken litter will be stored in an 11.3'x12' bin to accommodate a dump truck load of chicken litter. The curing bin will be 12’x 24’ to accommodate a 35 day curing period, and a 15'x12' bin will store the completed compost material which will hold four weeks worth. The composting period will be a 49 day process with 14 days being in the composter and 35 days to cure. The calculations for all above numbers can be found here. The team decided to go with a 66'x50' pole barn that is enclosed on three sides to house the composter and all storage bins as well as additional amenities. The pole barn will protect the facility from weather conditions and storm runoff. The site where the pole barn will be located has 12 feet accessible roads as well as large enough turnarounds to accommodate full size dump trucks including a 66'x55' concrete area to maneuver. The site will also contain a bio-swale and drainage ditch as best management practices to prevent contaminants in storm water from leaving the site. The facility as a whole was over sized in the case of a higher demand of compost or food waste being produced in the future. The design drawings can be found below.