CALCULATE YOUR
CONSTRUCTION WASTE REDUCTION POTENTIAL |
Conversion
Factors
One of the trickiest parts of evaluating your construction waste
stream is in the various ways it can be measured - weight or volume. Both are
acceptable methods, however, the numbers could be deceiving. Take for example,
cardboard and drywall. A cubic yard of cardboard will only weigh about 30 pounds
while a cubic yard of drywall will weigh about 400 pounds. Therefore, a full
30 yard dumpster of cardboard will only weigh about 900 pounds. A 30-yard dumpster
full of drywall will weigh about 12,000 pounds. The important thing is to use
consistent units. The following table, adapted from National Association of
Homebuilders will help with conversions from one unit of measure to the other:
Material
|
Pounds per Cubic Yard
|
Cubic Yards per Pound
|
Solid Sawn Wood |
267
|
0.004
|
Engineered Wood |
280
|
0.004
|
Drywall |
400
|
0.003
|
Cardboard |
30
|
0.033
|
Metals |
150
|
0.007
|
Vinyl (PVC) |
150
|
0.007
|
Masonry |
1000
|
0.001
|
Paints, Caulks, etc. |
167
|
0.006
|
Mixed Wastes |
95
|
0.010
|
* Source: NAHB Research Study - "Residential
Construction Waste: From Disposal to Management (April, 1995)
Computing
Waste Amounts
In 1998, a project was tracked in Park City, Utah. The construction
was of a 4,300 square foot single family home with a three car garage. For the
duration of the project, a total of 7 dumpsters, 15-yards each, were hauled
to the landfill for a total of approximately 108 cubic yards. Using the conversion
chart above, total pounds were calculated based on the observed material percentages
(estimated on-site). The following table shows the results:
Material
|
Percentages
|
Cubic Yards
|
Solid Sawn Wood |
25
|
27
|
Engineered Wood |
20
|
22
|
Drywall |
15 |
16
|
Cardboard |
12
|
13
|
Metals |
3
|
3
|
Vinyl (PVC) |
1
|
1
|
Masonry |
1
|
1
|
Paints, caulks, etc. |
1
|
1
|
Other |
22
|
24
|
Total |
7 Loads
15 cu yards each
|
108
|
Landfill fees are often charged per ton (1 ton = 2000 pounds), so the Park City
project converted the waste composition data into pounds for ease in calculating
potential from avoided disposal costs. Converting cubic yards to pounds isn't
difficult, using the conversion factors:
Material
|
Cubic Yards
|
x
|
= Pounds
|
Solid Sawn Wood |
27
|
267
|
7209
|
Engineered Wood |
22
|
280
|
6160
|
Drywall |
16
|
400
|
6400
|
Cardboard |
13
|
30
|
390
|
Metals |
3
|
150
|
450
|
Vinyl (PVC) |
1
|
150
|
150
|
Masonry |
1
|
1000
|
1000
|
Paints, caulks, etc. |
1
|
167
|
167
|
Other |
24
|
95
|
2284
|
TOTAL |
|
|
24210
|
Potential
Savings Calculation
The following example shows the estimated landfill savings derived from C&D
recycling and/or reuse:
Item |
%
|
Waste Tons
|
Diverted Tons
|
No Recycling/Reuse |
|
|
|
Tons of C&D Waste |
100 |
100
|
0
|
Landfill cost per ton ($50) |
|
$5000
|
$0 cost savings
|
|
|
|
|
With Recycling/Reuse |
|
|
|
Tons of C&D Waste |
100 |
|
|
Wood |
45 |
0
|
45
|
Drywall |
15 |
0
|
15
|
Cardboard |
2 |
0
|
2
|
Metals |
3 |
0
|
3
|
Other - mixed waste |
35 |
35
|
0
|
Landfill cost per ton ($50) |
|
$1750
|
$3250 cost savings
|
This estimate is a direct financial calculation of savings due to reduced landfill
costs associated with reduced disposal needs. It provides a good rough estimate
of potential savings and is the first step to preparing a C&D waste management
plan. This estimate does not include the savings in landfill space (community/tax
savings), nor does it include the money that could be derived from reselling
items such as cardboard or wood. It also does not include costs associated
with employee/subcontractor training, material hauling, or time spent finding
markets for recyclable materials. All of these factors will be weighed as a
C&D waste management plan is developed. The calculation of this estimate
for a particular company will likely indicate that a plan should in fact be
developed to reduce material waste and reuse or recycle what can not be avoided.
- Additional
Resources:
-
- The Construction
Waste Management Handbook provides a step-by-step discussion of a construction
waste management plan developed and applied by The Homestead Habitat for Humanity
(HHFH) at their Jordan Commons development. The handbook includes details
on the calculation of disposal costs (potential savings), waste composition,
identification and selection of recycling and reuse outlets, on-site training,
material sorting procedures, and more. A must-read for anyone interested in
developing a construction waste management plan. National Association of
Home Builders Research Center
- http://www.smartgrowth.org/library/constwastemgmt_hndbk.html
- Calculating
the Cost-Effectiveness of Jobsite Recycling - Are there dollars in your dumpster?
This site provides a series of worksheets to help determine how much of what
materials are produced at the job-site, and the cost of recycling versus disposal.
King County Department of Natural Resources
- - http://dnr.metrokc.gov/swd/bizprog/sus_build/analyze.htm
|
(Fact Sheet 4 of 10)
|
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