We know that the construction business is waste and energy-intensive, so as general contractors, our decisions and actions carry great responsibility.
More and more, our clients are concerned with the triple bottom line: environment, social and economic. Our clients are on the cutting edge of providing the most sustainable building solutions on earth – for example, biodiesel facilities that turn local animal waste to clean fuel, cogeneration facilities built within operating water treatment plants, and laboratories devoted exclusively to research on green architectural components. Through LEED training and the good fortune of living in the Bay Area, where the entrepreneurial zeal for energy efficiency is contagious, we have learned a great deal.
But when my teenage son asked me a few years ago, “What do you do at jobsites to reduce waste? It seems like small steps could have huge impacts because of the sheer volume of material you use.” He was right: our fleet of hybrid cars and recycled office supplies seemed inconsequential to all that wood and steel that ends up in a typical jobsite dumpster, despite sorting and recycling efforts.
Few studies exist in the US on construction waste statistics, but in the UK, the construction industry is responsible for 32% of landfill waste. Further, it can account for a staggering 2-3% of construction cost which, any builder will tell you, can seriously impact profit margins. The lack of integration of waste control with the planning and control process, and the need for not only verifying but also monitoring the efficiency of construction processes has been neglected industry-wide. In the face of the current economic boom, while we all scramble to fulfill our client’s needs, the process of incorporate waste control into the construction industry seems to be nobody’s priority.
Overaa buys 75,000 cu yards of concrete, 132,000 board feet of milled lumber, and 195,000 board feet of forming plywood annually. That’s a lot of raw natural resources. When I saw those numbers, I was convinced that, as builders, we have a moral responsibility to create a system to monitor and reduce waste in our processes. Further, I believe the scalability of operational and environmental savings is huge when leveraged across multiple sites, companies, and regions.
Several years ago we set out to develop waste control procedures as part of site management on a routine basis, by using a Lean approach as well as quantitative data collection techniques. Admittedly, our primary goal was to increase operational labor productivity, but in doing so, we significantly reduced tangible construction waste.
In an attempt to be develop transparency and share our procedures with our industry peers, I’d like to highlight lessons learned some of the specific measures we have taken in the past few years to consciously reduce construction material waste.
In 2013, we hired Gary Gibson, a former superintendent with 44 years of experience with projects like the Disneyland Parking Garage and Kodak Theatre under his belt. Gibson’s sole charge was to analyze and improve the productivity rates within our concrete forming operations.
Concrete related activities represent 55% of our work volume, so naturally the first place we looked was concrete forming operations. Every month Overaa purchases more than 11,000 board feet of milled lumber (1 board foot is 1″X1″X12″) and approximately 16,250 square feet of new forming plywood. Most of this wood is cut and assembled into forming panels at Overaa’s fabrication yard in Richmond, CA, then dispatched to various jobsites. By aggregating this operation in a central location, the wood remnants, which normally would be waste if fabricated at the jobsite, are saved for other applications requiring shorter length wood. These waste pieces are used for blocking therefore utilizing 95% of the original purchased material.
Once the forming panels are utilized on the job site, they are returned to the yard for dismantling and re-sized for use at other job sites. The used plywood is also cleaned for use on unexposed formwork applications, utilizing 85% of the salvaged material.
Other materials have been consciously selected for use because of their re-use potential:
Aluminum and steel forms are used wherever possible. These can be reused up to 250 times.
Recycled plastic is used to replace wood nailers in aluminum joists.
High strength steel, re-useable wall forming ties are used in 85% of the forming for walls replacing one time use steel “snap ties” with plastic cones.
This year Overaa dismantled prefabricated wood “I” joists resulting in components recycled into other forming materials.
Overaa has invested in LVLs (laminated veneered lumber) which utilize remnants of milled lumber fabricated into longer lasting forming members creating less bulk tree harvesting. Sure, LVL’s cost a little more, but they get paid for many times over through more re-use than typical lumber.
Overaa has set up a collection program to recycle unused mechanical components and forming miscellaneous hardware including chemicals. These materials have no restocking value and typically are disposed of in the construction industry.
In the Richmond yard, wood, paper, and metal scrap are separated in bins then taken to recycle collection firms in the local area.
When projects are nearing completion, local farmers and school wood shop programs are approached so Overaa can donate unused building materials.
Approximately 30% of our projects are design build with significant concrete components. We encourage the use of recycled class II aggregate subbase, and do this in 92% of our subgrade preparation work.
We have saved costs by recycling common building materials, purchasing materials that are made of post-consumer content, and introducing efficiencies in fabrication and application that have paved the way to get more and more uses out of our materials. We have proven with a little planning, we can reduce our waste stream, and actually improve efficiencies resulting in money saved and time spent on the project. When we see the benefits, it is clear that wise choices in materials, good fabrication techniques, and planned execution and application can produce a triple bottom line enhancement.
Kara Overaa Gragg holds an MS in Architecture and is a 4th generation owner of Overaa Construction, a design-build general contractor headquartered in the San Francisco Bay Area.