Waste Stream Assessment

Introduction

A building block of a successful solid waste management program is knowledge of the local waste stream. Armed with this knowledge, local governments can design an efficient waste reduction strategy that targets the most promising and most problematic waste materials first. A waste stream assessment is the process of understanding the mix of material in the local waste stream. A waste stream assessment can be as simple as evaluating existing data that a local government already keeps or it may include an extensive waste sort to estimate quantities of various materials in the waste stream.

This fact sheet reviews the basic options available to local governments as they evaluate their waste stream. It focuses, first, on easier ways of assessing the waste stream and then introduces more involved waste assessment activities.

Importance of Waste Stream Information

A waste stream assessment should not be conducted only to gather dust on a shelf. It should be a dynamic record that helps a local government prioritize its waste reduction activities. A waste stream assessment provides local governments with the following benefits:

• Identifies major material categories and their quantities in the waste stream.
• Helps rank materials according to their impact on the local waste stream.
• Helps identify specific commercial/industry types and/or facilities that should be targeted for waste reduction.
• Assists in creating local educational materials on solid waste management.

Although a waste stream assessment is important, it should be remembered that recycling is a market-driven endeavor, and markets will be the ultimate factor used to target materials for recycling.

Levels of Waste Stream Assessment

A waste stream assessment is an incremental and ongoing process. Local governments should not necessarily begin by hiring a consulting firm to conduct a waste sort as a first step. A waste stream assessment can be compared to an archer's target in which a waste sort is a bull's eye.

However, the information available in the many concentric rings around the center may hit the mark close enough to satisfy the needs of many local governments. As shown in Figure 1, a local government should start its waste stream assessment with the methods listed in the outer rings of the target and work inward as needed. For most local governments, existing figures from national and state averages combined with easily gathered local data from the disposal facility will be sufficient.

Level 1 Assessment: Borrowed Data

Most local government waste streams are similar, especially with respect to their residential waste streams. Much of the data local governments need to have about residential waste can be garnered from average national and state data. Figures 2 and 3 below should provide local governments with estimates of materials in their waste stream.

Figure 2 presents national averages by percent of materials in the entire waste stream. Although national averages do not precisely reflect North Carolina's waste stream (e.g., North Carolina probably has more drink containers in the summer), these values should still be useful for identifying materials to target for waste reduction. For example, it is obvious from the chart that paper and yard trimmings comprise a dominate share of the waste stream, and these materials should be primary targets of waste reduction efforts.

A 1995 study by the NC Division of Pollution Prevention and Environmental Assistance (DPPEA) researched the recyclable components of the North Carolina waste stream. Results of this study are aggregated in Figure 3, which presents materials commonly recycled in North Carolina and the percentage by weight of the total stream of recyclables (not percentage of the total waste stream). This chart provides North Carolina local governments insight into the portion of the waste stream that can be feasibly reduced.

An examination of these numbers along with consideration of local conditions may help a local government choose materials to target for waste reduction as well as develop and justify reduction strategies. For example, the values presented in Figure 3 suggest that a community may wish to ban corrugated cardboard from the landfill or develop a program to compost food waste along with its yard waste. When using the values in Figure 3 to evaluate a local waste stream, local governments should subtract any known recovery of individual commodities to obtain an estimate of materials that still go to the landfill and to evaluate the effectiveness of their programs to date.

The breakdown of material by source sector, as shown in Figure 4, may also be useful for local calculations. In additional to national and state data, a local government may be able to borrow data from local governments with similar demographics that have already conducted waste sorts. In addition to those in the charts, the following figures may also be useful if data need to be manipulated and presented:

Level 2 Assessment: Disposal and/or Transfer Facility Data

The data gathered in a Level 1 Assessment can be complemented by simple recordkeeping techniques at the disposal facility or transfer station. A Level 2 Assessment allows communities to identify sources and quantities of waste and is particularly useful for understanding the non-residential waste stream. Whereas the residential waste stream is relatively consistent among communities, commercial and industrial waste can vary dramatically.

Scale House Records

If scale house records are properly maintained, they should reveal the sources of the waste brought to a facility and the quantity deposited. Such records in themselves do not necessarily reveal exact types of materials in the waste stream; however, they may be useful for two reasons.

First, scale house records can allow a local government to rank the generators of waste in order of the quantities of material that they produce. Such information can help a local government determine the specific industrial and commercial facilities that should take priority as it works with the private sector to reduce waste. In some cases, one company can generate as much as 25 percent of the community's waste stream. For example, from scale house data a local government may identify a mobile home manufacturer as the largest generator of waste and then concentrate on helping the company to reduce waste.

Second, scale house data may indicate types of commercial and industrial generators in a community. For example, the data may indicate that construction and demolition debris is a major contributor to the waste stream. Although each contractor may not bring large quantities of waste to a landfill, there may be so many small companies that this waste stream merits special attention from the local governments.

If scale house data are not collected in an organized manner so that they can be easily reviewed, a local government should consider revamping its scale house recordkeeping procedures. Good software is available to help local governments with such recordkeeping. In addition to reviewing scale house records, those responsible for waste reduction should have discussions with the scale house operators to get their evaluation of the waste stream as they will likely have valuable information to share. Even if the landfill or transfer station is privately operated, the local government still should seek access to scale house data relevant to its community. If the private company considers such data proprietary, access to such data should be negotiated as part of the contract.

Direct Observation

Observation of solid waste as it is dumped on to a transfer facility floor or into a landfill cell provides additional information beyond the scale house data. Such observations can provide a rough evaluation of the waste material of a specific company or common waste in a community. For example, direct observation may indicate that a specific industry has not successfully implemented a corrugated cardboard recycling program, or it may identify pallets as waste material commonly brought to the facility. Even if no formal observations are made, the workers on the transfer floor or the landfill face can be extremely good resources about the waste stream, as they witness the unloading of vehicles every day.

Level 3 Assessment: Commercial/Industrial Survey

In a Level 3 Assessment, the waste stream is evaluated from information gathered about or from the generators. The simplest form of such an assessment is identification of the major types of commercial and industrial businesses in the community. Such information frequently is common knowledge. For example, an extensive furniture industry in a community may indicate that furniture waste should be targeted. More specific information may be obtained from the local government economic development office or chamber of commerce. As a rule of thumb, if there is any industrial or commercial infrastructure in a community, corrugated cardboard should be targeted for waste reduction.

Written Survey

A more involved effort may involve sending a written survey to all or a portion of the companies in a community. A written survey can be used to identify the major components of a company's waste stream. At the same time, such a survey can help businesses identify waste reduction opportunities and give companies an opportunity to request assistance and/or site visits. Mailing addresses may be available through the local economic development or tax office. If addresses are not available locally, the Public Information Section of the North Carolina Employment Security Commission in Raleigh at (919) 733-4329 maintains a database of every company in the state. This database includes address, contact, telephone number, number of employees, and industry type according to Standard Industrial Classification codes. Also, if a local government plans to undertake a comprehensive survey, it may want to use a database program such as Microsoft Access™ to produce mailing labels and organize the data once it is collected.

Site Visit

In addition to or instead of a written survey, some local governments choose to visit major waste generators in the community. A waste assessment should not be the only goal of a site visit. A site visit is an opportunity for the local government and company representative to work together to identify components of the waste stream and waste reduction alternatives. The local government can provide advice on source reduction, recycling markets, and conservation opportunities for water and electricity. A site visit is a serious undertaking that requires extensive preparation and follow-up work. (More information on commercial and industrial site visits is available from DPPEA). Wake County provides a work sheet to its commercial enterprises to help them analyze their own waste stream. This kind of work sheet may be made available as part of a written survey or site visit.

Level 4 Assessment: Waste Sort

Some solid waste management programs may benefit from the detailed waste stream assessment provided by a waste sort. A detailed waste sort can help guide a local government's waste reduction activities as the program matures, and focus on the less major components of the waste stream is possible. A waste sort also provides a good indication of the successes and failures of the waste reduction program, especially if a local government has baseline data. For example, a waste sort can reveal the success of efforts to keep organics out of the landfill. However, a detailed waste sort may not be appropriate for most communities as the cost of conducting a sort may outweigh the benefits. A local government should conduct a waste sort only if the added level of information will contribute to its waste management goals.

Steps for Conducting a Waste Sort

A successful waste sort is a methodical effort. Following is a list of the major steps to conduct a sort.

• Step 1: Plan the Waste Sort
  
  Careful planning is a key to conducting a waste sort that will generate accurate data. All aspects of the waste sort from sorting garbage to analyzing data should be considered during the planning stage; also, the reasons for conducting the waste sort should be identified.

• Step 2: Design the Sort System
  
  This design should include location of the sort, participants and their responsibilities, and time frame
  
  
• Step 3: Determine Sampling Protocol
  
  A local government will probably want to segregate waste from each of the main generator sectors: residential, commercial, industrial, and construction. A sort may also segregate industrial waste according to industry type. For each main category and to merit statistical accuracy, samples should contain 200 to 300 pounds, i.e., the more material sorted, the greater the accuracy of the results.* A sort plan should designate the process by which loads will be randomly selected to minimize bias. For example, approximately 100 pounds sorted from every fifth residential truck may be used as a random sample from the residential waste stream, or a sample of waste from a known source may be scooped out of the working face of the landfill with a front end loader.
  
  *A Waste Stream Characterization Guidance Document for North Carolina Communities, NC Department of Environment, Health, and Natural Resources, 1992.
  
  
• Step 4: Conduct the Waste Sort
  
  At the same time that designated generator categories are kept distinct, waste should be sorted according to waste type. Sorting categories should include everything from newspaper to textile waste. The number of sorting categories depends on the level of specificity needed and the reasons for performing the sort. By the end of the sorting process, there will be many small piles of sorted material.
  
  
• Step 5: Measure Samples
  
  Each pile of waste should be measured by visual inspection, volume, or preferably weight. All information should be carefully recorded on forms developed prior to the sort.
  
  
• Step 6: Analyze Data
  
  Data should be aggregated and analyzed to obtain a snap shot of the solid waste stream. Computer spreadsheet and/or database programs are useful tools for managing data.
  
  
• Step 7: Use Information
  
  The information from the waste sort should be used to meet goals identified during the planning stage of the waste sort.

Waste Sort Issues

The following issues should be considered in the design and implementation stages of a waste sort.

• Multiple sorts: More than one sort will help reduce statistical bias and variation. For example, a local government may choose to conduct a sort every day for a week.
• Seasonal fluctuations: Waste can vary dramatically from season to season. For example, yard waste is most prevalent in the summer and fall. Commercial/industrial activity may vary seasonally, as well. It may be necessary to conduct waste sorts at various times throughout the year to account for such fluctuations.
• Statistical accuracy: A waste sort is not a precise science. It provides useful data, but it does not provide an exact representation of the waste stream, especially if only a few sorts are conducted.
• Safety: Because sorting can be a messy and even dangerous job, safety should be a primary concern. All sorters should wear gloves, steel-toed boots, safety goggles, long sleeve shirts, and long pants. Hard hats and dust masks may also be appropriate. Procedures for managing any hazardous waste should be determined before the start of a waste sort.
• Demographic factors: A waste stream will be affected by demographic changes in a community. Industrial and commercial waste will fluctuate dramatically in direct relationship to the economy. Also, if a major industry opens or closes, the waste composition for a community may change. Natural disasters such as hurricanes can influence the composition of the waste stream. New residents may not only increase the quantity of local waste, they may have different waste generation patterns than current residents.

Quick Waste Stream Analysis

The DPPEA synthesizes data presented in Figure 3 with data from individual Local Government Solid Waste Management Annual Reports to create Quick Stream Waste Analysis tables for every local government in the state. An example of such an analysis in presented in the table below. The Quick Waste Stream Analysis informs local communities about the approximate quantity of recyclable material in their waste stream and their current recovery level for each material.* The dollar value of the material is also presented in the table. Communities can use this analysis to evaluate the effect of their recycling program and identify additional opportunities for waste reduction.

*	The Quick Waste Stream Analysis is only as accurate as the data provided in the Annual North Carolina Solid Waste Management Reports. The analysis will not be useful for local government that combine their data with other communities or do not complete the survey accurately.

Conclusion

North Carolina law states that each solid waste management plan shall "evaluate the solid waste stream in the geographic area covered by the plan." The law does not require a detailed waste sort: a Level 1 Assessment may be adequate if the plan demonstrates that the local government is making a good faith effort to understand its waste stream.

The purpose of a waste stream assessment is to help local governments implement their solid waste management plans, and the level of assessment should be based on local government needs. Since recycling markets and other local government experiences provide equally important information about the waste stream, a waste stream assessment does not have to be precise to suffice. The many benefits of a waste stream assessment should encourage communities to familiarize themselves with the local waste stream, update the information as necessary, and use waste stream information in the planning process.

The North Carolina Division of Pollution Prevention and Environmental Assistance provides free, non-regulatory technical assistance and training on methods to eliminate, reduce, or recycle wastes before they become pollutants or require disposal. Telephone DPPEA at
(919) 715-6500 or 800-763-0136 or E-Mail for assistance with issues in this Fact Sheet or any of your waste reduction concerns.

DPPEA-97-05. March 1997.