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CONSTRUCTION WASTE
AND
DEMOLITION DEBRIS RECYCLING
WHAT IS TECHNICALLY FEASIBLE?
Robert H. Briclcner, Senior Vice President and
J. Frank Bemheisel, Vice President
GERSHMAN, BRICKNER & BRATI'ON, INC. 2735 Hartlaad Road
Falls Church, VA 22043
For ppesentation at
SOLID WASTE MANAGEMENT ASSOCIATION OF NORTH AMERICA (SWANA) 3rd Annual Intemational Recycling Symposium
Mesa, Arizona
February 28, 1992
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CONSTRUCTION WASTE
AND
DEMOLITION DEBRIS RECYCLING
WHAT IS TECHNICALLY FEASIBLE3
___-- - - A. INTRODUCTION -___--- -_ __ - _ _- -- -
-part of a community’s overall solid waste management strategy, it is possible to !I/ a feasibility study on the recycling potential of construction waste and demolition debris
--__ - management system. The initial activity would involve information gathering and review of the local C&D waste situation.
Such data would include a review of the existing construction waste conditions at local landfills, review of nearby demolition landfills, if any, current C&D waste handling methods,
--_- --- *- I
B. OBJECIlMESOFASTUDY - - - _ I
/. 7- The typical objectives of a C&D waste recycling feasibility study should generally be considered to be as follows:
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I_______ - - --
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0 To evaluate the experience of C&D waste recycling with respect to the local conditions;
To identify the nature of potentially recycled products from C&D waste received at the local landfill(s) and to assess the availability of markets/outlets for these products;
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0 To verify the practicality of different technological processes by pilot testing, if deemed appropriate, or other suitable means;
0 To study the institutional arrangements for the application of potential recycled C&D waste products at the local landfill(s), and other community construction and demolition projects; and
0 To recommend a system for recycling C&D waste at the local landfill (or other justifiable site) giving full account of the economic, engineering, operational and environmental considerations of such projects.
C. EMSTING AND PROJEczlED C&D WASTE MATERIAL MARKER3
Based on GBB’s experience with C&D waste from five sources (Le., Excavation, Roadwork, Building Demolition, Building Renovation and Site Clearance), at least 19 individual materials found in C&D waste have been examined for their potential reuse. These materials are by nature low in economic value; otherwise, they would not have been discarded. The fact that the 19 materials are mixed helps to lower their value as a recovered material. However, the identified materials, when separated or when combined into subgroupings, were found to have potential value. Given the style of C&D waste generation and its composition, five principal recoverable products have been identified: (1) asphalt pavement, (2) aggregate, (3) soft fill, (4) ferrous metal, and (5) shredded wood. Each of these are recoverable and reusable when properly processed to the users (market) requirements. Based upon a previous GBB report, Table 1 shows the recoverable quantities for each of three processing options discussed in this paper. This specific C&D waste recycling feasibility report offered the municipality the potential reduction of between 25 and 60 percent of the C&D waste disposed of in their landfills. These values depended upon the technical option selected.
The five recoverable products presented above can be aggregated into three basic categories of recoverable materials which, depending up the nature of the C&D waste generating base, have been shown in at least one study, to comprise over 95 percent of me local C&D waste stream. These categories are:
Shredded wood products; and 0 Ferrous metal.
Inert granular material (aggregate, asphalt and soft fill);
In many parts of the country, there are no companies commercially recycling C&D wastes. Depending on state regulatory controls, C&D landfills, if permitted differently from conventional sanitary landfills, are typically faced with less stringent environmental regulations. Consequently, there may be no established uses of commercially recycled C&D waste materials, and thus no identifiable established markets. The markets discussion may therefore focus on identifying potential markets and potential market values versus fitting into a more well established product niche, e.g., the aluminum beverage can recycling programs associated with residential waste stream recyclables. The objective must therefore be to add maximum value to the products removed from the overall waste stream during the processing of as much of the overall material as deemed economically viable. Some recovered products will have higher
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Table 1. Potential Recovery Quantities for Processing Options of C&D Waste Materials
Recoverable Quantitv. in Tons
and Mixed C&D Combined Rock Crusher Plant Waste Plant System
Material ODtion I ODtion 2 ODtion 3
Concrete
Asphalt 33,398 8,997 42,395
Concrete 222,173 59,849 282,022
Reinforced Concrete 246,013 66,27 1 31 2,284
Dirt
. Rock
Rubble
Wood
Block Concrete
Brick
Glass
Sand
Trees
Metal (Ferrous)
Residue
Total
358,878 193,348 552,226
1 73,629 46,772 220,401
116,166 31,292 147,458
0
12,101
78,057
4,808
47,757
0
21,758
77.562
1,392,300
123,675
3,260
42,053
2,590
25,729
2,289
5 1,480
270.594
928,200
123,675
15,361
120,110
7,398
73,486
2,289
73,238
348,156
2,320,500
Note: Options noted are described in more detail later in this paper.
Source: Gershman, Brickner & Bratton, Inc.
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_I__ 1 _ -
intrinsic value than others; however, this value will only be realized if the market for the produc exists within economic transport distance and if the incremental cost of producing the highe
\-- value product is less than the incremental higher value of the virgin material being displaced. I --
1. Inert Gran ular Materials
Inert granular material products, derived from certain elements in the C&D waste stream, are listed in the Table 2, along with their potential uses.
Table 2. Inert Granular Material: Sources and Products
Sources in Waste St ream Potential Product Uses
Asphalt Concrete Reinforced Concrete Dirt, Soil and Mud Rock
. Rubble Block Concrete Brick
Landfill Daily Cover Landfill Final Cover Landfill Temporary Access Roads Land Reclamation Fill for Road, Airport and Port Embankments Base and Sub-base for Roads and Airports Cover and Bedding for Landfill Liners Aggregate for Filter Layers in: Landfills,
French Drains, Bridge Abutments Asphaltic Concrete
Much of the land reclamation work and roadway construction work in the United States is initiated by the Federal Highway Administration and department of transportation (D.O.T.) in the individual States. The general specification for Civil Engineering Works is widely used. as a guide to materials and workmanship. State regulatory agencies should initiate a review of their respective department of transportation specifications to include specific references to crushed concrete and use of recycled materials wherever this is possible without unacceptably reducing standards of finished products.
A number of the uses identified in Table 2 could be implemented promptly at Federal, State, and local government work sites, such as sanitary landfills, highway and road construction projects, major airport construction sites, etc. while private sector markets are attempting to be developed. In order to develop markets, as practicable, the C&D waste recycling facility should allow adequate space for stockpiling product so that recovered materials are available to construction contractors as needed. Marketing startup costs and the costs of slow market development should be considered and shown in project cash flows and economic proforma’s.
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2. Shredded Wood Products
The reusable wood products and their sources in the waste stream are shown on Table 3. The reusable products are basically cellulose materials in chip or powder form. The cost of producing reusable wood products increases as the size of the finished product decreases, because of the greater amount of processing required.
Table 3. Wood Waste Sources and Uses
Sources in Waste St ream Potential Product U seS
Wood Landfill Cover
Trees Animal Bedding Fuel
Composting Bulking Medium Boiler Fuel Feedstock for Pulp Mills Raw Material for Chipboard Wood Flour for Plastic Fiber
Use of wood chips as landfill cover is an immediately available application for this material, which would be relevant if all of the inert granular recycled material discussed previously could be utilized off-site. Use of shredded wood as landscape mulch or soil conditioner is also a readily developed market. Government agencies (e.g., the public works department, parks department, sanitation department, etc.) should specify and purchase landscaping mulch for parks, sitting out areas, playgrounds, and street landscaping.
. Use of wood products for animal bedding, a composting bulking medium or as boiler fuel may provide significant sales opportunities. However, problems with cost and/or lack of market applications on a regional basis may be encountered. Also, lack of current market applications for use of shredded wood for pulp mill, chipboard or plastic fiber feedstock, however, should, not discourage further consideration of these high-value applications. It is recommended that local govemment economic development agencies investigate these markets further, particulari y pulp mill and chipboard manufacturers. To enhance market development, a small shredder installation specifically to produce sample material for testing by manufacturers could be set up to develop market interest. Limited data on the use of recovered wood flour for plastic fiber is available and further research is recommended.
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3. Ferrous Metal
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Nationally, there is an active ferrous scrap metal market which has the capacity to consume an estimated 69 million' tons per year of ferrous scrap. The value of recovered ferrous metal depends on the quality of the material. Quality is determined by degree of contamination and ease of handling. Depending on location and grade, current scrap steel prices range from $55 to $90/ton according to the American Metal Market. Adding more recovered scrap from the C&D waste stream to the present scrap market may, on a regional basis, have the effect of depressing prices to some extent. However, an active export market also exists for scrap steel.
As discussed, it appears feasible to develop markets for the three types of products discussed above, To develop additional markets will most likely require certain government action with regard to both supply and demand for the specific products.
D. C&D WASTE PROCESSING AL'I'ERNA'IWES
1, Introduction
In the highlighting of technical alternatives for this paper, the review will focus on the design of C&D waste processing technologies which have been designed to "unscramble the egg" and produce distinct product streams from a heterogeneous C&D waste stream. Many such modem facilities exist as solid waste processing plants in the United States and in Europe including the Fresh Kills landfill crushing/screening plant on Staten Island, New York, the Star Recycling facility in Brooklyn, New York, and the Basoray Plant in Basel, Switzerland. The principal C&D waste processing plant techniques covered in the paper mainly consist of two plant types as follows:
0
0 Mixed C&D waste. RocWConcrete/Asphalt crushing and screening plants; and
2. Rock Crus hine Plants
The process flow of a typical rock crushing plant with a single crushing stage is presented in Figure 1.2 The two principal size reduction unit processes are jaw crushers and cone crushers. The jaw crusher is the most universally applicable primary crusher. As a general rule, discharge material is twice the size of the crusher setting and the output gradation is also changed by closing or opening the discharge setting. Cone crushers have the same universal acceptance for secondary crushing as jaw crushers do for primary work. Standard cone crushers with a reduction ratio of 6 - 8 to 1 can reduce material to a minimum size of 314" minus.
'Based upon 1987 data from U.S. Bureau of Mines.
2Figures 1-12 are located at the end of the text.
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The use of rock crushing and sizing equipment is well known and proven around the world, and a plethora of equipment manufacturers have years of experience to draw upon. The existence of hundreds of rock quarries in the United States provides local and experienced equipment owners and operators in most regions of the country. Several complementary pieces of equipment (e.g., the primary crusher feeder, magnetic separator, vibrating screens for product sizing, and several belt conveyors) form the rock processing system.
Based upon the waste quantification and characterization data completed by GBB on a recent C&D waste recycling study, approximately 30 percent of the Excavated Material category was classified as rock and this accounted for over 45 percent of the total rock identified in the five waste categories that were selected. Based upon the data that may be collected during the C&D waste characterization activities, it could be possible to target the processing of only the Excavated Material waste fraction. In the above cited example, this allowed processing access to almost half of the total rock quantity projected to be available in the entire C&D waste stream of the study area.
3. Concrete Crushing Plants
The popularity of concrete recycling has continued to rise throughout most of the developed world. Two primary benefits are stimulating this interest: (1) saving of landfill space, (2) conservation of virgin materials that are being depleted in some areas (these have some unique product applications) and (3) cost savings.
The process flow of a concrete recycling plant is similar to that of the rock processing plant shown in Figure 1. Depending upon the type of concrete demolition taking place, the thickness of the concrete slabs, the shape of the concrete pieces and the amount of non-concrete contamination will vary. The demolition of major old concrete highways, for example, could have very large surface area slabs but at a very predictable thickness. However, a concrete reinforced building replacement may encounter a myriad of thicknesses and shapes. Depending upon the physical shapes of the products, additional sizing (Le., using jackhammers) may be needed. If a large concrete piece got past the initial visual inspection area and into the'feeder system, most systems have a special-purpose jackhammer mounted at the feederkrusher interface point to enhance reduction. The plant operator is typically positioned to see the choke.point jam and take action to jackhammer the concrete piece at that point.
Most concrete recycling plants use jaw crushers as their primary crushers with the same extensive history as the quarry site units mentioned previously. The reasons are high reliability, low maintenance costs, and greater particle size control. A secondary crusher, e.g., a cone crusher, may be used for more precise and fine product sizing at concrete recycling plants. If a secondary machine is not used, a conveyor, used to carry back or recycle the oversized screened products, is employed to control the product's top size (see Figure 1).
The overall data collected on concrete and reinforced concrete availability in the five waste categories classified at a recent GBB C&D waste recycling study activity indicated that, based upon quantification and characterization data, approximately 40 percent of the weight of the Roadwork Material category was concrete and this accounted for approximately 20 percent of the total non-reinforced concrete quantity identified in the five waste categories. The Building
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Demolition waste category had a nominal 25 percent reinforced concrete content and this amounted to approximately 75 percent of the available reinforced concrete in the total C&D waste stream.
4. AsDhdt RecvclinP Plant
In some areas, the demand for new asphalt product allows economical recycling of old asphalt material and this is being done. However, due to the presence of asphalt in landfills, it is generally acknowledged that not all of this material is being recycled. This could be caused by specifications which are not updated, no incentive (asphalt plant owned by the virgin aggregate producer) or cost factors.
The process flow of a typical asphalt recycling plant is presented in Figure 2. The overall data collected on asphalt av$lability in the five waste categories of a recent GBB C&D waste recycling study indicated that approximately 20 percent of the weight of the Roadwork Material category waste was asphalt and this accounted for approximately 75 percent of the total available asphalt identified in the five waste categories quantified at the landfill.
5. Mixed C&D Waste Processing
- Due to the high costs of waste disposal in many urban areas of the world, ebntractors involved in processing building rubble have, at times, tried to produce high quality products to be competitive with natural aggregates. The rubble has been extensively processed for rock and asphalt aggregate as well as steel reinforcing, wood and other materials. Since most mixed C&D waste recycling facilities are privately owned, the disposal fees and product revenues must cover all system costs, company overhead and provide a profit. However, regardless of product sales prices, sometimes customers prefer natural aggregates due to a variety of reasons, for example, building material specifications often require the use of virgin material.
Depending upon the markets being addressed, the mixed C&D waste that is delivered may be sorted rather than processed at the plant, particularly if a load consists primarily of only one constituent (e.g., concrete, or asphalt mixes, or rock, or wood, etc.)
In considering mixed C&D waste processing systems as shown in Figure 3, several existing plants use mechanical separation devices (e.g., trommel screens and disc screens) in conjunction with air or wet processing separators. These dry.or wet processes are typically applied for the separation of materials of organic or mineral nature. In the dry processing systems with air separators, a cyclone baghouse or bio-filter control system needs to be installed to properly treat and dispose of dust. In wet processes, the heavy fraction, rich in inorganics, sinks to the bottom of the wet quench tank whereas the organic materials tend to float and are removed in the wash water.
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6. Representative Facility Recommendations
Over the past two years in particular, many technology systems and C&D processing devices have been introduced into the waste industry and reviewed by GBB staff based upon the type of material and quantity of C&D waste flows expected to be available. As a result of this review, several different system configurations have been deemed to be technically applicable and reasonably proficient in reducing C&D waste material going to local landfills and provide products for local use.
a. Option 1
Option 1, illustrated in Figure 4, focuses on C&D waste materials which could be diverted from landfilling in the immediate time frame by processing equipment which is readily available from many vendors in the United States. The material selected for processing could be the inert portion of the C&D waste stream consisting of concrete, rock, dirt, sand, etc. so as to generate readily products readily useable. This Option 1 concept allows for the production of an aggregate for fill at "clean fill" or reclamation sites and a soft fill product. Ferrous metal would also be recovered.
as follows:
(1)
The typical equipment needed for Option 1 is depicted schematically in Figure 5 and are
Tracked Front End Loader - Sepagtes non-processible material and moves surge piles.
Front End Loader - Loads feeder/screen from nearby surge piles.
Feeder/Screen - Vibrating grizzly screen designed to pass sand, dirt, and small rock.
Crusher - Set to crush material 8 inches and larger..
Feed Conveyor - Moves oversized material from the feeder and the crusher to the screen.
Magnetic Separator - Removes reinforcing rod and other ferrous metal.
Double Deck Screen - Vibrating screen with two decks to produce three products: oversized (for recycling back to crusher), middling - an aggregate material, and fines - soft fill.
Recycle Conveyor - Moves oversized material from the screen to the crusher.
Middling Conveyor - A two-part belt conveyor (short fixed discharge conveyor and a stacking conveyor) for discharge of the aggregate fraction.
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(10) Fines Conveyor - A two-part belt conveyor (short fixed discharge conveyor and a stacking conveyor) for discharge of the undersize (fines) fraction.
(11) Front End Loader - Loads products into trucks for removal and reuse.
Based upon the C&D waste to be processed, for illustrative purposes, this equipment has been specified to process a nominal 250 tons per hour. Technically, the system can be operated on a two-shift basis and has an expected availability of 85 percent; taking into account both scheduled (preventive maintenance) and unscheduled (failure) outages.
b. Option 2
Option 2 is a Mixed C&D Waste Processing Option. This concept focuses on identifying mixed C&D waste material which can be diverted from landfilling. The raw material infeed would consist of: (a) certain building demolition waste; (b) renovation waste; and (c) mixed site clearance waste materials. Generally, except for oversized materials that are screened initially, for economic viability, most of the products from this processing system should be useable to reduce the ultimate disposal costs of residue materials. The material products would be the inert portions of C&D waste consisting of concrete, rock, dirt, sand, etc. Processed to produce an aggregate and a soft fill product. Additionally, ferrous and shredded wood products could be generated.
.
Under this concept, which is depicted in Figures 6 and 7, trucks with loads of small sized inert material would be diverted by a spotter at the scalehouse for processing along with mixed C&D waste loads noted 'above. Option 2 would not include a rocWconcrete crusher system and thus only material that is less than 8 inches and falls through the disc screen is further processed. Thus Option 2 as depicted, would not address the processing of larger inerts nor the processing of roadwork material and excavated material. The oversized product is assumed to be landfilled as a reject material.
The typical equipment needed for Option 2 is as follows:
Track Loader - moves dumped material near to feed area; develops surge pile and siparates any large pieces of rock or concrete material.
Front End Loader -- Loads feed conveyor and separates large inert material.
Disc Screen - Horizontal disc screen designed to eliminate material greater than 8-10 inches in size.
Magnetic Separator - Removes ferrous metal.
Trommel Screen - Set to screen dirt and fines -- soft fill material.
Handpicking Station - sort out non-recoverable contaminant materials (such as plastic pipe) that might otherwise float and be carried over to the wood processing system.
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(7) FloaVSink Tank - designed to separate heavy inert fraction (e.g., rocks, concrete, etc.) from the lighter floatable fraction (such as wood). The heavy inert fraction would be available for use as fill at reclamation sites.
(8) Hammermill - shreds the float fraction -- mainly wood.
For purposes of developing data for this paper, the Option 2 equipment has been specified to process a nominal 150 tons per hour. Based on location and permit conditions, system can also be operated on a two shift basis and has an expected availability of 85 percent for both scheduled (preventive maintenance) and unscheduled (failure) outages.
c. Option 3
Option 3 is the combination of Option 1 and Option 2 and is designed to handle most, if not all, of the infeed waste categories presented within the overall C&D waste stream that may be generally expected to be delivered to a landfill. This concept is to (a) identify material which can be diverted from landfilling by rocWconcrete crusher equipment which is readily available (e.g., excavated material, roadwork material, and certain building demolition waste) and (b) interface a mixed C&D waste processing system for the separation of the more organic laden loads (e.g., renovation waste and mixed site clearance waste). Inherent in the design is the assumption that the recovered products from these two processing trains are marketable.
To illustrate this combined system for purposes of this paper, this equipment is assumed to be specified to process a nominal 400 tons per hour. The material selected for the rocWconcrete crusher system is the inert portion of C&D waste stream consisting of concrete, rock, dirt, sand, etc. as well as the oversized inert material separated from the mixed C&D waste system. This would produce an aggregate and soft fill product. Under this Option 3, trucks with loads of inert material (or almost all inert material) would be diverted by a spotter at the RocWConcrete scalehouse for processing at the crusher plant, whereas organic loads would be sent to the mixed C&D waste processing system.
The concept for Option 3 is presented in Figure 8 and the equipment is graphically presented in Figure 9. As noted earlier, for purposes of this presentation it is assumed to. be a combination of that detailed in the earlier Option 1 and Option 2 descriptions.
E. SlTEREQ-
1. In troduct ion
The physical space requirements for the actual C&D waste processing equipment is fairly moderate compared to the traffic area and the space requirements for C&D waste feedstock storage and finished product stockpiles. Efficient logistics of receiving and materials shipping will go a long way in reducing the total site needs of any of the waste processing systems recommended.
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2. Paw Mate rial Feedstock
All incoming C&D waste materials should be weighed and given a classification for ultimate discharge location. If only one processing system is utilized and the category of waste is to go through the C&D waste processing system without any additional visual prescreening, the load would be moved to the active receiving area. However, if rock-rich or concrete-rich loads, for example, are intended to be discharged into discrete waste piles of comparable material, the C&D waste hauler must be clearly told the classification and dumping location, especially at the larger Option 3 processing site.
For raw materials stockpiling, an average in place density of 1.25 tons per cubic yard has been assumed for a combination of broken up asphalt and concrete from roadways and similar demolition debris from buildings. If this material is stockpiled, a height of approximately 10 feet is assumed for track front end loader piling. Staff members of GBB have seen C&D waste piles higher than 50 feet but this was more the exception than the rule. Based upon 1.25 tons per cubic yard, the average burden weight could, when fully stockpiled, be approximately 4.2 tons per square yard. However, during the truck dumping cycle prior to stacking by a tractor dozer, the stockpile may only average 3 feet in height and this height is used in this paper for calculation of the incoming feedstock stockpile area requirements. For Option 2, the Mixed C&D Waste Material stockpile average density was assumed to be 1.0 tons (2,000 pounds) per cubic yard.
After C&D waste has been processed, the finished product must be stockpiled and eventually loaded for transport off-site. Most C&D waste processing plants utilize portable and radial stacking conveyors to stockpile materials. Depending upon the product, the dumping angle (or angle of repose) varies from one material type to another but the general angles for certain representative C&D waste products vary from 30" to 45". In the use of portable conveyors for stacking purposes, the ultimate heights of the pile and the available arc movement of the radial stacking conveyor would be used to determine the stacking volume and capacity.
3. e d l Site Requirements
a. Option 1
For purposes of this paper, Option 1, the RocWConcrete Crushing and Screening Plant has been assumed to have a nominal design rating of 250 tons per hour. At capacity, the plant would be expected to operate for at least 15 hours per day at 85 percent availability and process a nominal 3,200 tons per day. Assuming a worst case scenario that the plant were down for one full receiving shift and material was not diverted directly to the landfill during that shift, a full one-day storage requirement of approximately 3,500 tons would be necessary. Since during the truck dumping cycle and prior to stacking by the track dozer, the average pile height may only be one yard, the recommended site area allowance for storage of incoming material is approximately two (2) acres, which also allows for dump trucking vehicle discharge, maneuvering, entrance, and exit.
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The actual process equipment area reflected in Figure 10 will require approximately one (1) acre which would include room for adequate maintenance vehicle servicing.
Allowing for front-end loader movement around the stockpiles as well as free access for loadout area trucks that will be both arriving and leaving the site from the stockpile area, an area of approximately one (1) acre is required for each of the two principal product loadout areas or two acres of total product storage.
Therefore, with minimal buffer area, the total site requirement for Option 1 would be approximately six (6) acres and the site configuration could be as generally portrayed in Figure 10.
b. Option 2
Option 2, the Mixed C&D Waste Recycling Plant, is assumed in this paper to have a nominal design rating of 150 tons per hour. At capacity, the plant would be expected to operate for at least 15 hours per day at 85 percent availability and process 2,000 tons per day. If the plant were down, more than a one-day storage requirement would be necessary; approximately 2,500 tons was selected. With an assumed stockpiled density of 2,000 pounds (1 ton) per cubic yard for the mixed C&D waste (versus 1.25 tons per cubic yard for the stockpiled concrete and rock), the stockpiling of 2,500 tons at an average pile height of one yard requires an area allowance for front-end storage of approximately 1.5 acres to allow dump trucking vehicle discharge, maneuvering, entrance, and exit.
The process equipment area reflected in Figure 11 would require approximately one (1) acre of land which would include room for adequate maintenance vehicle servicing.
The product stockpile area, which could initially involve conical piles for four of the output streams and the use of on-site containers, could be enhanced by the use of at least one radial stockpile conveyor for the heavy materials. Since the Option 2 configuration would be expected to generate at least seven product splits, the use of additional radial stackers for the dirt and fine loadout area and the wood market demands could generate additional on-site storage availability.
In addition to stacker conveyors, the use of large containers to receive certain products could be considered. Based on market receiving hours and transporting constraints, some on-site container storage space could also be provided.
Therefore, allowing for front-end loader movement around the stockpiles as well as free access for loadout area trucks that will be both arriving and leaving the site from the stockpile area, an area of approximately 2.5 acres is estimated for the combined loadouthnterim storage areas.
Therefore, based upon an assumed rectangular area being available, the total site requirement for Option 2 with minimal buffer is approximately 7 acres for the conceptual system configuration presented in Figure 1 1.
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c. Option 3
Option 3, the Integrated C&D Waste Recycling System has a nominal design rating of 400 tons per hour (Le., 250 tons per hour at the RocMConcrete Plant and 150 tons per hour at the Mixed C&D Waste Recycling Plant). At capacity, the facilities are expected to operate for at least 15 hours per day at 85 percent availability and process a nominal 5,000 tons per day. Based upon the C&D waste stockpiling assumptions presented in Option 1 and Option 2 previously, a total of 6 acres and 7 acres respectively, for the rocWconcrete and mixed C&D waste plant would be required. It is deemed prudent to allow one (1) additional acre of open space between the major stockpiles for equipment maneuvering area and a contingency zone. The recommended site area allowance for front storage for both systems is therefore approximately 14 acres which also allows room for trucking and vehicle discharge maneuvering onto the site storage area.
The equipment area for the two processes is estimated to require approximately 3 acres which would include room for adequate maintenance vehicle servicing. Since the Option 3 configuration is assumed to generate at least seven products, the use of both radial stackers over both 45" and 90" swings is assumed as well as on-site storage containers.
Allowing for front-end loader movement around the stockpiles as well as free access to loadout area trucks that will be both arriving and leaving the site from the stockpile area, an area of approximately 3 acres is projected to be required for each of the two main aggregate product loadout areas and approximately 3 acres of total site area is allowed for additional surface piles and/or container storage of the other selected products (e.g., metals, wood, plastics, etc.).
Therefore, based upon a rectangular area being available, the total site requirement for Option 3 is approximately 14 acres as generally portrayed in Figure 12.
P. COSTESTIMATING
Although the purpose of this paper is to present the technical processes associated with processing and recycling of C&D waste, it goes without say that GBB staff have had discussions with several manufacturers for each representative type of plant discussed herein and budgetary prices solicited. Very preliminary capital costs, the cost of mobile equipment, exclusive of land costs and buildings (open air operations were assumed), were as follows:
Option 1: WocklConcrete Crushing Plant Option 2: Mixed C&D Waste Option 3: Combined System
$1,800,000 - 2,200,000 $2,000,000 - 2,250,000 $4,000,000 - 4,500,000
Due to the extremely variable nature of local labor rates, fuel costs, finance interest rates, recovered product values, etc., this paper will not attempt to present the annual operations costs for each technical option discussed. However, it needs to be noted that when conducting a life cycle cost model, the following six major parameters should be covered: (1) annual C&D waste quantities, (2) recovered material quantities and unit sales prices, (3) product transportation cost, (4) operation costs (capital, operating, and maintenance), (5 ) projected revenues, and (6) landfill savings.
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The economic models are sensitive to the price received for reusable products. These parameters could be explored by sensitivity runs of the model to identify the full range of cost or profit expected from the implementation of C&D waste recycling facilities.
G. SUMMARY
A C&D waste recycling project is designed to turn waste products into reusable marketable products. Not only must the operator be mechanically proficient, but the operator must also have appropriate marketing expertise to maintain a long term day-in and day-out commodity movement at competitive prices to assure a profitable business venture. Of key concern to the public sector should be the demonstrated capability of prospective vendors to (1) efficiently and effectively operate the proposed technology and (2) implement the marketing plan for the products generated. If one were to assume that the local landfill contractor and C&D waste recycling operator were one-in-the-same party, it must be remembered that a delicate equilibrium may ultimately be established between the landfill use and its associated costs and the C&D waste recycling system throughput and its costs. Depending upon waste stream mix, these two systems could ultimately be competitive processes.
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Segregated Rock
Loads
unloaded for
Inspection
Unacceptable Material
Grizly Feeder Crusher
I
t I I I I I I
I I n
Multiple Magnet Deck
Screen
Undersized Materid Ferrous Metal Product B
Product A
COld-MiX Asphart Sdd to Municipaltties I and Subcontractors ; orStockplled ;
Ferrous Metal
offsite Acthrtty' ..............................................
'presumed to be at an existing asphdt prant location
Process Flow
I t
I
f f
Raw Material lnfeed 1
0 Roadwork material
Excavated material
Certain building demolition waste
Crushing System
1
Land reclamation site
* Landfill site (optional)
Ferrous material product
Dirt and fines material for soft fill
\
I
Certain building demolition waste
*Renovation waste
*Mixed site clearance
Product Outputs and Usage
(available for delivery to reclamation site, landfill, or marketed as products)
*>8 - inch rock, concrete, and other heavy inor anics (may
*<8 - inch rock, concrete, and other heavy inorganics
be hauled to landfill or available as feedstoc a for Option 1 crusher system)
*Shredded wood waste material
*Ferrous material product
eMixed organics and rejects to landfill
*Dirt and fines material for soft fill
* -
e .
.
....... ......... ... *.*. :.:.:.:.:.:.:.:.:.:.:.;., - - ..'.'*.~.~.*.~.~.~.~.~.~.~.~.~. ................. ................. ................. .................. ........ ......... .-.-.-.=.-.-.*.*. a- inch Interim Storage
.-.*.-.-.-.-.-P. and Loadout Area ......... ......... ........ ......... ................ ......... ......... (Oversized Material) .... .... ....... .............. .............. ............ .......... ......... (8 - inch Material
Dirt end Fines LoadoutArea
...... ......... ............. ........... ............... ................ .................. ................... .................... .................... ..................... ...................... ....................................... ..................... Ferrous Loadout Area ................. ................. .................. .................. ................. ................ ................ ............... ............... ..............
wood and Bark Grinder 49-
,
Raw Material Infeed
Certain building demolition waste
Renovation waste
Mixed site clearance
1 '37
Mixed Waste
Processing System
Crushing System
Product Outauts and Usaae
Raw Material Infeed
Roadwork material
Excavated material
Certain building demolition waste
<8 - inch rock, concrete, and other heavy inor anics
marketed as products) Shredded wood waste material Ferrous material product Mixed organics and rejects to landfill Dirt and fines material for soft fill
(available for delivery to reclamation site, Ian 8 ill, or
............ ....................................... . ..;.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.: .... ............................. .............................. ............................... ............................... ................................ ................................. ................................. .................................. .................................. ..........................................
e-. .-. ..................................... .................................... .................................... ................................... .................................. ................................. ................................ ............................... .......................... .........................
. .. .11*.* ..................................... ..................................... ............................. ............................ ..................... ................ .................... .................... 8 3::: & .,.+. *
............... .............. .... ..... .....
DlrtandFlneS Loadoutha I < y8 - inch Product I Stockpile
t
i I I I I I I I I t I I I I I 1 I I I I I I I I I I I I I 1 I I I I I I I I I I I I I 1 I I I I I I
1 1 31 /c,
- - - I I I 1 1 I I I I 1 I I I I I I 1 I I I I I I I I I I I I I I I I I 1 I 1 I I I I I I I * I I I I I I 1 I I I I I 1 I I I I I I 1 I I I I
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