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CONSTRUCTION WASTE MINIMIZATION: CONSERVING OUR ENVIRONMENT BY MANAGING OUR RESOURCES

William R. Mincks

Construction Management Program

Washington State University

Pullman, Washington

Introduction

America is facing a crisis with its own waste. We generate an inordinate amount of waste in all of our activities. We then bury it, much of it embalmed by petrochemical products. We are poisoning ourselves from this buried waste, polluting our water and our land. To prevent further pollution of our earth resources, the Environmental Protection Agency (EPA) and its State counterparts are severely limiting landfill operations. We are seeing a general acceptance of changed waste disposal patterns throughout our communities with recycling programs growing and being mandated by local authorities. We're even seeing corporate awareness of reducing waste and non-biodegradable waste, such as McDonald's exchanging the Styrofoam burger package for a recycled and recyclable paper wrapper.

Construction, however, lags behind the general public's increasing environmental awareness. About 20% of the total waste stream can be attributed to construction, including new construction, renovation, and building demolition. The majority of construction waste has been deposited in landfills. Until recently, there has been little effort made by the construction industry to reduce construction waste or to consider alternative sources for disposal of write materials. Although the construction industry has been aware of the tremendous amount of waste generated by construction, there has been no economic incentive to reduce this waste.

With the decreasing number of landfills and the dramatic increase in disposal costs, the construction industry has been forced to acknowledge the problem it faces with waste. There are many potential solutions to the construction waste problem. These solutions will require concerted efforts by architects, contractors, subcontractors, and owners in the coming decade.

The Problem

Prior to World War II, material was at a premium and labor was inexpensive. The construction material used was labor intensive. Materials, such as plaster, were used extensively. Plaster is batch mixed, with minimal waste of material. As plaster is in a plastic form, it requires considerable labor for installation. Material was conserved, due to its cost, which was often double the cost of labor.

After World War II, new technology was applied to building materials. Materials such as plywood and gypsum board were panelized, providing relatively inexpensive materials that required less labor. Technology advanced in the production of these materials, resulting in relatively low cost materials. Construction labor cost, however, has increased disproportionately to material cost.

The low cost of material and high cost of labor encouraged waste in new construction. It has become easier and less expensive to cut and use new material, rather than to use waste pieces of the material in the installation. Gypsum drywall is the classic example of excessive waste in construction material. Gypsum board consists primarily of gypsum, an abundant natural resource. Gypsum is inexpensive and it is inexpensive to incorporate this material into gypsum board for construction. Installation cost, including hanging and taping, nearly triples the cost of the material. Typically, the drywall contractor orders all 12 foot lengths of gypsum board. The installers use the largest pieces possible for the wall configuration, discarding the remainder of the sheet, which may be as large as 4' x 6' pieces. The goal for the drywall contractor is to use the minimum amount of labor hanging the board and the minimum amount of labor in taping. The discarded smaller pieces are not used in the installation, as they require additional installation and taping labor, far exceeding the cost of the material and the disposal costs. An average of 12 W I S% of gypsum drywall is wasted in projects with a rectilinear wall and ceiling layout. Amore unusual layout of walls, ceilings and sots can easily produce up to 30% gypsum board waste. Up until recently, the drywall contractor sent laborers to pick up the discarded gypsum board (to "scrap" the project) and to take the waste to the local landfill. Gypsum drywall has been an economical material for construction, using the method of installation described. The alternative material for gypsum drywall is plaster, which costs about four to five times the in-place cost of drywall. Plaster is not even a close competitor to gypsum drywall, due to the labor intensive nature of plaster.

As our awareness of the environmental impact of landfills has increased, the drywall industry, as most of the construction industry, has been impacted. Half of the solid waste landfills throughout the United States have been closed within the last two years, decreasing the opportunities for disposal of construction waste. Many communities have replaced their solid waste landfills with waste-to-energy incinerators. Many construction materials, such as concrete, asphalt paving, and gypsum drywall, are not flammable, thus inappropriate for disposal by incineration. Some construction waste landfills still exist. These sites accept "inert construction waste" consisting of materials that are noncombustible, non-dangerous and are likely to retain their physical and chemical structure under expected conditions of disposal. Gypsum board, however, has been found to produce hydrogen sulfide gas and sulfide leachates in the anaerobic environments typically found in landfills. In the early 1980's, several municipal landfills in Vancouver, British Columbia, experienced serious odor and leachate problems caused by the decomposition of gypsum board. Because of these problems, a number of landfill snow refuse to accept gypsum wallboard waste. Many regulatory agencies are concurring with the finding that gypsum board is not acceptable for an "inert construction landfill", resulting in fewer disposal opportunities for gypsum wallboard.

The cost of disposal of most construction waste materials is increasing. The cost of landfill "tipping fees" has escalated in all parts of the country, but these costs vary a great deal from area to area. Landfill "tipping fees" appear to average in the area of $ 65-75 per ton, with costs well over $ 100 per ton in the Northeast. These "tipping fees" are increasing at a phenomenal rate, depending on the local facilities for disposal. Some materials, such as drywall, are facing alternative disposal methods, not solely caused by increased costs, but also caused by unavailability of traditional disposal methods. Unfortunately, some contractors faced with no feasible alternative are dumping gypsum board illegally on vacant property, or they bury the waste on the jobsite.

The problem in this case is obvious. The American construction industry wastes too much material. We remodel and raze buildings frequently, burying their pulverized remains. We are running out of places to bury this waste. The EPA and State Regulatory Agencies are intent on reducing the amount of solid waste during the next decade. California has mandated a 25% decrease in solid waste going to landfills by 1994 and a 50% reduction by the year 2000. The construction industry needs to voluntarily participate in waste reduction, or the industry will be subject to increased regulatory control. A new vision must develop throughout the industry -- one that encourages the responsible and conservative use of construction materials.

Solutions

The Environmental Protection Agency's "Agenda for Action" contains a strategy for "integrated waste management", combining source reduction, recycling, combustion, and landfilling to substantially reduce the pollution impact of solid waste. In construction, we can look at the following elements for an integrated waste management program: source reduction, salvaging for reuse, composting, recycling, use of recycled products, combustion, and landfill disposal. To further integrate positive waste management in the construction, consideration of the total impact of the design, use, and reuse of the building and its materials relating to waste generation should be made throughout the design and construction process.

Education, of course, is necessary to increase awareness of the need for waste management in the construction industry and of the alternatives available. The EPA and State agencies are active in distributing information to municipalities and to the industry. Increased awareness of waste management is a result of increased economic and regulatory pressures. Many corporate owners are very cognizant of their liabilities for landfill material, and are active in the disposal method of construction and demolition material. The Boeing Company, a large construction owner in the Northwest, is very sensitive about the disposal of material from their construction projects. On a recent construction project, Boeing demolished several concrete buildings built in the 1950's on the site of the construction project of a modern instrumentation laboratory. The concrete buildings were crushed on site and the crushed material remained on site as compacted fill. Both public and private owners are mandating responsible and documented disposal of material from their construction projects.

Source Reduction:

Source reduction includes the reduction of the quantity of materials going into the waste stream and the reduction of the toxicity of materials entering the waste stream. Source reduction is the most efficient method of reducing the waste stream, the action having a direct result. Considerations taken during the design phase can directly affect the quantity of waste on the project. The contractor can also easily control the waste quantity with careful attention to the quantity needed. When comparing costs of material and reduction, the material cost should always include a realistic estimate of transportation and disposal costs for the waste, considering local conditions.

(1) Material considerations in the design phase:

Each material has a dimensional restraint or module that should be considered. Panelized materials, such as gypsum board and plywood, are available in only a few sizes. Consideration of these modules in the dimensions of the building elements, both in plan and elevation, can reduce waste. In instances where the panelized material will have considerable waste, alternative materials should be considered. Batch‑mixed materials, such as plaster, may become a more competitive cost alternative in situations requiring a large amount of waste of a panelized material, such as gypsum board. Even the most reasonably priced material can be too expensive when used inappropriately.

Although concrete formwork is normally designed by the contractor, use of modular panels will conserve formwork, reducing the waste stream. Concrete formwork is normally intended for several uses, and modular dimensioned concrete can facilitate repetitive use of the formwork.

Insight into the future use of a facility can also contribute to reducing the waste stream. Providing flexibility for change can avoid wasting the initial construction materials for replacement materials. Demountable and reusable interior partitions can substitute for traditional gypsum board partitions. The initial cost of the demountable partitions is substantially more than the cost of the gypsum board partition. The estimated cost of relocating the standard gypsum board wall, however, should include the cost of disposal of the original gypsum board. Although initial cost is usually the driving force behind material selection, consideration of the environmental costs is also necessary. We should investigate reusable systems rather than always use systems that are thrown away after the first use.

Consideration of the disposal of the material, either waste or debris from demolition, will often result in lower construction costs. There will be some instances, however, that a higher cost will be incurred to reduce the quantity of material going into the waste stream. Each situation will require a subjective decision that will be dependent on attributes of the owner, the facility, the designer, and the community. Each design decision we make has an effect on the environment.

(2) Material considerations in the construction phase:

The contractor, too, has an influential role in source reduction. Appropriate ordering of material can reduce the waste during construction. Instead of ordering x114' x 12' sheets of gypsum board, the contractor can strategically order a variety of lengths, 8',10', and 12', and arrange the appropriate stocking of the board. Strategic ordering can reduce waste substantially, depending on the configuration of the building elements.

Traditionally, wood framing contractors order either all 16' lengths or random lengths of dimension lumber. Ordering specific lumber lengths and coordinating the installation reduces lumber waste.

Utilization of waste material into the product is also a method of source reduction. Sorting the waste and using smaller pieces in the installation can reduce the amount of waste. A complete cost comparison should be made, however, including the cost of additional labor, comparison of material cost, and waste disposal costs. Unless the initial material cost is substantial, considering current labor and disposal costs, utilization of waste material in the product is usually not cost efficient. Rising disposal costs, rising energy costs, and rising material costs can change this relationship, though.

The initial cost of the material has a large impact on the effort made by the contractor to reduce the amount of waste. When lumber was $200 per thousand board feet, there wasn't much effort made to conserve lumber and minimize waste. As lumber prices have climbed to $500 per thousand board feet, contractors are realizing the necessity of changing work habits to keep the wood waste to the minimum. As gypsum board still is inexpensive, the contractors' current efforts seem to center around alternative methods for disposal rather than source reduction.

Recycling

Recycling of construction materials doesn't reduce the waste during the process, but will reduce the amount of waste reaching the waste stream. Recycling of construction materials, in most instances, results in cost for recycling, which is usually less than the tipping fees charged by the local landfill. Any recycling effort requires some separation and sorting of materials prior to delivery to the recycler.  Although there are several recycling opportunities for many materials, new recycled uses are being discovered daily.  Every community has a large amount of construction waste and demolition waste, providing many recycling opportu­nities. Recycling within the community, where the waste is generated, is most desirable to avoid transportation costs.

There needs to be a market for the recycled product, and the recycler needs to make a profit to stay in business. Most successful recyclers are going to receive revenue from the generator and from the purchaser of the recycled product.

The following sections discuss some of the current recycling opportunities available for construction materials. As these opportunities vary from community to community, investigation of the available programs in the locality is necessary.

(1)  Recycle construction waste to the manufacture of the same material:

Some materials can be recycled into the manufacturing process for the same material. The most commonly recycled materials are metals. Steel, aluminum, copper, brass, and other metals used in construction can be recycled back into the same materials. Metals recycling has been actively practiced in the United States since World War II. As the cost of landfill disposal has risen dramatically, separation of metals at the jobsite has become more feasible. In one Northwest community, a metal recycler provides a dumpster at jobsites at no charge. The contractors then separate metals from other materials and deposit the metals in the dumpster. The recycler sorts the metals and processes them for recycling. Although there is no premium for the metals in this scenario, the contractor doesn't pay for disposal costs. Metal recycling is fairly common throughout the country, resulting in much of the steel manufacturing in this country coming from recycled steel. About 50% of copper products are manufactured from recycled copper, a common building material.

Gypsum board waste can also be recycled back into the manufacture of new gypsum board. A process developed by a Vancouver, British Columbia recycler removes the paper from gypsum board and grinds it into pellet form. The recycled material is then sold at a very minimal amount to gypsum board manufacturers, who incorporate the recycled material with gypsum. As there are some impurities, primarily paper, in the recycled material the manufacturer can use up to 25% recycled gypsum material in the production of gypsum board. The recycler charges the contractor a tipping fee for disposal of the material, usually less than other disposal charges. This recycling process, however, is dependent on the proximity of a gypsum board manufacturing plant. Transportation of the recycled material increases the cost and feasibility of recycling. Gypsum board recycling facilities exist in Vancouver, B.C., Seattle, and Toronto, with plans for further expansion.

Other materials, such as asphalt based materials, can be recycled back into the same product. Concrete from demolition can be crushed, washed, and screened for use as an aggregate in new concrete. Research is continuing throughout the country attempting to use the abundant "resource" of construction waste materials.

(2)  Recycle to another product or use:

There are a number of applications of recycled consumer products from construction waste. Gypsum board, due to its relatively large amount of waste, has a number of recycled uses. Gypsum is an absorbent material, and is used in several applications. One manufacturer is making kitty litter from recycled gypsum. One agribusinessman has been processing gypsum board waste for cattle bedding, with the farmer spreading the used cattle bedding on the fields, enhancing the soil with the gypsum. Several companies are processing gypsum board into agricultural gypsum, which is combined with soil in many areas.

(3)  Using recycled products (from other uses) into construction products:

There are, of course, waste materials from other sources that are being used in construction products. Used rubber tires constitute a very large source of waste material. A process has been developed that combines "crumb rubber", made from used tires, with asphalt, forming "rubberized asphalt", which is used for asphalt paving. This process combines asphalt cement with finely-ground rubber material. The paving material produced is a reliable product, having been tested since the 1960's. Rubberized asphalt, however, is more expensive than standard asphalt paving, due primarily to limited competition caused by patent restrictions. The Federal Surface Transportation Act of 1991 mandates a 5% use of rubberized asphalt in federally funded State road contracts by 1994, with a 5% increase per year until 1997. This will result in a 20% use of rubberized asphalt paving after 1997.

Numerous construction materials use recycled materials. "Homasote board", used for many applications in construction for many years, is manufactured from recycled newspaper and paper products. Selection of construction materials based in recycled products ultimately has an effect on reducing the total waste stream.

(4)  Composting

Organic materials can be combined, shredded, and treated into compost. Compost has a number of agricultural uses, primarily as soil additives. Organic construction waste, such as brush, trees, and cleared vegetation material and lumber, can be taken to composting operations. Composting operations, in a variety of sizes and configurations, are becoming more widespread. The end product is also available to enrich soils on construction project sites.

(5) Recycling materials to energy ("combustion"):

Recycling materials to energy through combustion is not actually "recycling", as the material is destroyed for further use. Wood products have energy stored within them, which can be released by burning. Throughout the country, wood recyclers accept wood construction

waste, which has been separated from other materials, chip the material into smaller pieces and provide the material to combustion plants that convert the wood to electrical energy. Wood waste can also be used for heat.

Although sending wood products to combustion does reduce the waste stream to landfills, it doesn't convert them into materials that can be reused. Wood waste can recycle into wood and paper products. Transportation costs and availability of wood recycling plants can affect the feasibility of recycling wood materials. Use of recycled wood materials in construction will help induce manufacturers to continue efforts to use waste wood products in the manufacture of their products.

Salvage/Reuse

The full or partial reuse of construction material after their initial use is a definite objective of an active construction waste management plan. As mentioned previously, foresight into the flexibility needed by the facility will suggest appropriate partition systems that can be reused in their entirety. When a facility is expected to expand at a future date, the use of relocatable wall panels facilitates ease in construction, and doesn't waste the original wall panels. Numerous other considerations in system and material choices can prevent the original construction materials from entering the waste stream when the facility is expanded or remodeled.

The contractor, too, should use care in installation and removal of materials to facilitate their reuse. Excessive fasteners/adhesives can negate intentions to reuse materials. Provisions for alterations and remodeling can be made easily during the initial construction process. The contractor can save removed materials for future use, however this practice requires warehousing of the material or building components and a concentrated effort to reuse the material.

Total demolition of buildings, or razing of the building, is often done without regard for salvage of the materials. The time required for salvaging much of the material is usually far longer than the time required for demolition by heavy equipment. Salvage value is often negligible for many of the materials, making it more economical to take the demolished material to the landfill. Even if material is salvaged, many times the local building officials will reject used materials in new construction. We need to look at demolition differently than we have in the past two or three decades. We need to realize that there are environmental costs as well as the costs of demolition. We need to look at buildings slated for removal as a resource for materials. The buildings contain finish materials, such as hardwood trim, that can be reused. Brick, structural steel, structural wood framing, doors, and windows are many items that can be salvaged for reuse. Many materials can be salvaged for scrap and be recycled. Planning needs to be done well in advance to create the extra time necessary for incremental demolition. The local building officials need to be convinced of the feasibility of reuse of salvage materials. In short, architects and contractors need to expend more effort to manage total building demolition, assuring that the maximum amount of material can be saved for reuse and the minimum amount of material is sent to the landfill.

Waste Management Plans

Effective waste management on a construction project requires a careful plan, as one would make a schedule for the construction of the project. Prior planning can facilitate arrangements for minimizing waste and prudently disposing of the remaining waste. Municipalities are starting to request plans from contractors concerning waste management. Most of this planning will be the responsibility of the contractor or the construction manager. However, guidelines for minimizing construction waste can help the designer to be an active participant in waste minimization.

Contractors are currently being required to keep logs of the disposal of hazardous materials. As regulation seems to be effective in other areas of contractor compliance, such as safety, it is logical to assume that regulations will soon be in place requiring contractors to log and monitor the disposal method and disposal location of all waste materials. Firms that are currently involved in an active waste management program now will be well prepared for regulations concerning construction waste.

Conclusions

The construction industry is a major contributor to the solid waste stream. We can no longer bury garbage to the extent we have done in the past. With fewer opportunities for landfill dumping of waste, other alternatives for waste management need to be examined by all involved in the construction process. We need to produce less waste. Our waste needs to recycled and reused. We need to examine our alternatives before we construct and map out a feasible plan, for both the project and the environment. Our children are made aware of their environmental responsibilities throughout their education. As a continuation of this environmental education, architectural, engineering, and construction education should include an awareness of the impact of construction waste and methods to minimize further additions to the solid waste stream.

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