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Recycle Construction and Demolition (C&D) Debris
Construction Waste Handbook
Worksheet Economics
C&D Resources
Education Program
C&D waste in large custom houses is greater by an exponential factor than the national typical house. The cost of C&D waste hauling in this immediate area is a mere fraction of the builders cost and the hauling costs represent no more than 20% of the total cleaning costs the builder incurs. Thus, there is little current incentive to recycle. The barriers are manifold and the culture is not favorably inclined to change due to the economics of the situation. The cold hard fact that drywall has no marketplace in the state of Texas is a huge barrier to overcome for the H-GAC area. The solid sawn wood and the engineered wood with no foil applied are basically being recycled in an underground economy in which the builder does not participate in. In developments that require the use of a container to house the C&D waste, the policies actually encourages more total waste and promote neighbor/citizens to behave in an inappropriate manner.
On-site grinding is technically a very viable option. The fundamental difference an on-site grinder in the waste stream reduction makes is too large to ignore. Waste stream reduction rates of more than 80% can and should easily be accomplished. The economics of on-site grinding are close to being viable but do not exist as of today. There are now three on-site grinding companies in the H-GAC area. Two of these sources are in the grinding business because the ownership is enlightened and wants to do the right thing. The third is a part-time business that primarily is involved in the sale of the grinding equipment.
A brief review of the study follows:
House One compared to House Two in Macro Numbers
- There were 9 container hauls versus 3 container hauls in house two
- There was 85,242 pounds of C&D waste in the landfill versus 13,220 pounds in House Two
- The builder had to purchase 9 loads of crushed concrete, mulch, and fill for the lot versus house two, where the reuse of the waste from the house was used for these purposes and no additional material had to be bought.
- The builder lost days due to rain in house one versus house two where the wood grind mat allowed craftsmen to continue working
Crushed Concrete - Nine dump trucks of crushed concrete were purchased to control mud
| Cost: $500 |
Nine 30 cubic yard containers were filled; 3 of wood only; 1 of drywall only, and 5 commingled
| Costs for House One: | |
| – 9 (landfilled) x | $180 |
| – 2 (settings) x | $90 |
| Subtotal: | $1800 |
| Total Cost: $2300 |
The waste stream for House Two
No crushed concrete used, ground wood used instead
3 containers were filled; all commingled.
| Costs for House One: | |
| – 3 (landfill) x | $180 |
| – 1 (settings) x | $90 |
| Subtotal: | $630 |
Utilizing on-site grinding (donation) valuation set by current list price at $.50/per square foot
|
Cost: $3900 Total Cost $4530 |
There are other monetary considerations which would vary from project to project. Examples include silt fencing, Fill material avoidance, base material avoidance, and most significantly the number of days that skilled craftsmen can continue working due to the conditions of the lot. HARC has not attempted to quantify those potential savings due to the jobsite unique nature of the savings. Previous studies on on-site grinding have not tackled this problem either. The most famous of these is the Indiana study conducted by the NAHB. In this study, the costs of land filling alone made the on-site grinding economically feasible.
The cost of the fill material and the base material is a hard dollar number that the builders can factor and consider in their decision making.
Simply put, Houston area landfill costs are so low that if the test of economic feasibility is the only one then it will be at some future date that on-site grinding becomes the predominant method of addressing the C&D waste stream.
In the instance of House Two, if we use only the metrics of landfill costs versus grinding and if we assume that 9 hauls is the correct number, the costs per cubic yard of waste would have to be $14.44 a cubic yard and a 30 yard container would have to cost $433.
The application of crushed concrete, a recycled product, is very common in our area. In the instance of House One, the application was a $500 expenditure. If we factor that into the equation, then the "per cubic yard cost" can be lowered to 12.60 or $378 per container. This remains more than double the current Harris County landfill rates.
In some respects builders should not have to worry about facing the dilemma of paying for containers and materials versus paying for grinding, they should be provided the most responsible method of waste handling by the scientific community. This has not happened and is unlikely to occur due to the fractious debate over a dollar today and long term costs.
When builders have large containers on-site, there is a tendency to generate more waste because of the "out of sight out of mind" philosophy. It also is unquestionably the case that large containers represent an open invitation to the general public to dump their household waste, regardless of the law, the threat or the signs which say smile you are on a closed circuit camera.
On-site storage in anticipation of on-site grinding may not be practical in large tract developments or dense sites unless the entire builder community agrees to the methodology. A more aggressive waste management plan will need to be employed to minimize the amount of waste left on-site with the associated potential risks and the cleanliness and tidiness perception issues raised with potential buyers.
Wood waste ground into mulch can be used in a variety of ways on a residential construction sites with very positive results. The most direct of those positive results are:
- Erosion control material for disturbed areas
- Mulch berms to aid or replace silt fencing in erosion control for the site
- Protecting Tree Root Zones
- Road and walkway stabilization for crews
- Landscaping, and
- Workmen's mats or pads
Shingle waste is a perfect source of base material for the flatwork on most new home construction building sites. H-GAC should consider a specific education program for on-site utilization of asphalt shingle waste.
Brick waste the single largest and most difficult to handle of the wastes in these studies needs to be seriously examined. The entire process needs to be subjected to a quality control cycle review. Builders could dramatically reduce their first costs by addressing the over specification of quantity and remove the safety factors that have to be part of the equation. The factories should be approached about take back contracts. If brick manufacturers over supply the material, the manufacturers should be encouraged/required to go back to the manufacturer for redistribution. HARC believes that there is little difference between a battery, a tire, or brick in the context of solid waste. The current practice is very expensive in the short and long term. The process is ripe with the opportunity to be improved.
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