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Read more on the design-build and solid waste industries from articles on Cambridge Companies, our design-build experience and our expertise on new builds, repairs, renovations, upgrades, expansions and modifications on solid waste facilities.
Why Experience Matters When Building a Transfer Station
Waste Today│ October 2019
I hear it all the time: “I’ll get an architect to design my transfer station, and then it will be easy to just find anyone to build it.” I’m here to tell you it’s not that simple. Some people think these facilities are just concrete and steel—they can’t be that difficult to build, right? Well, there are myriad factors that come into play during construction where the intent of the design just can’t be made clear enough. During these times, experienced and knowledgeable professionals are needed to take the lead.
The tipping floor
While many people think the tipping floor is just a concrete floor with rebar, so much more goes into the design and the makeup of the concrete itself. I would venture to say 99 percent of the architect and engineering firms out there don’t know how to design a tipping floor to withstand the abuse it takes on a daily basis. On top of that, 99 percent of contractors don’t know how to properly pour the concrete or place the rebar in these facilities. By using a general contracting firm to design or build transfer stations, it is highly likely that a basic tipping floor installed by inexperienced contractors will wear down too fast (sometimes within three to seven years) and cost a lot of money in inefficiencies and repairs over the life of the facility. By contrast, a proper concrete mix design can keep tipping floors intact for over 15 years without the need for repairs.
In terms of pouring the floor, the contractor must have experience with the right mix in order to do it correctly. Contractors need to understand how many control joints should be placed and where, why the floor should slope a certain way, how the rebar needs to be placed, why testing is important and how many tests are necessary for the mix during placement, how to cure the floor to limit stress cracks, and various other considerations. With all these job-specific requirements, being able to rely on a building team that has specialized in transfer station construction or other similar types of jobs is critical.
Rebuilding After a Natural Disaster
Waste Advantage Magazine│ October 2019
Natural disasters—be they floods, tornadoes, hurricanes, earthquakes, wildfires, etc.—can do great damage to any building, including a solid waste facility. Having plans in place for continuity of operations and setting up a clear plan for reconstruction can help recover faster after a disaster. To that end, we will focus on two parts of this response: the continuity of operations plan and approaches to physically repairing and reconstructing your facility.
Continuity of Operations
Once a disaster has passed, it is time to start picking up the pieces. Solid waste companies often have a critical role in this process, so getting back into operation is very important. Facility operators should have measures in place that allow them to re-start their operation if their facility is damaged. Certainly, available resources will impact this, as a larger company with multiple locations and built-in redundancy will likely have an easier time re-starting their operation, rather than a single-site company. These measures can include keeping backups of all personnel and company files in the cloud, so if onsite servers are damaged this information is preserved. The backup information should include scans of your facility drawings. This item is often overlooked, but having good quality up-to-date facility drawings will save time and money if a disaster hits your facility.
Not all disasters are a complete surprise. Several, such as hurricanes or flooding, may provide some advance warning. While there might not be an abundance of time, you may be able to relocate hauling trucks to higher ground if your facility is low-lying, or make sure a recycling center/transfer station is cleared out of material. With available time, you can work to minimize the environmental impact of your facilities and preserve your assets, so they are available after the event.
The local GM should be in contact with local emergency services to confirm when it is safe to re-start operations. Often, priority is given to waste services companies, but this coordination should be one of the first steps. Whether it is with some advance warning or as a complete surprise, the next step in re-building after a disaster, once access to the site is feasible, is a complete facility and fleet assessment. This assessment should look for two things: What is needed ASAP to restart operations? and What will be needed in the longer term to restore the facility to how it was before the event? Once the assessment is complete, the management team should bring all available resources to produce results quickly and continue operation as allowed. Other unaffected facilities can provide rolling stock and drivers, while volume from damaged transfer stations could be diverted to other facilities. In addition to this coordination, there may be critical facility repairs that need to be performed. This can include repairs to the electric infrastructure, the building roof or siding and similar repairs.
Action and Reaction
MSW Magazine│ July/August 2019
Transfer Station Operations and Equipment
Transfer stations are the connection nodes in a system of hauling routes. Like the branches of a tree or its root system, smaller hauling lines converge onto large hauling routes at these nodes which then load waste for the long haul to a large scale MRFZ or a regional landfill. In detail, their individual design layouts may vary somewhat depending on location, property limits and configuration, access to regional hauling routes, and local zoning laws. Their interior structure will be modified in accordance with its anticipated pass through capacity (the amount of waste entering and leaving the facility per work day). As such, the interior layout will affect floor space configurations, loading pit dimensions, access roads given over to truck queues, and whether the facility is open or enclosed.
The simplest layout includes a series of loading bays located adjacent to the tipping floor where the hauling trucks enter the facility and deposit their loads. These bays are set lower than the tipping floor surface in order to allow for a parked open top transfer trailer (usually with a 100 cubic yard volume capacity) to park and receive waste being pushed in from the top. The deposited waste piles are pushed into the open tops with wheeled bulldozers or wheeled front end loaders (tractor treads would typically do too much damage to a concrete surface of the tipping floor). There is nothing fancy about this operation: no compaction, no baling, no removal of valuable scrap. For facilities with low volume pass through capacities, this is an appropriate and cost-effective design. Larger operations can manage higher pass-through rates with the help of operational systems that increase overall efficiency (defined in terms of pass-through rate per square foot of tipping floor space) by increasing the final density of the waste being handled. These include surge pits, compactors and balers. More sophisticated equipment can produce higher density waste for long-haul transport. The most commonly used compaction mechanism is the hydraulic ram. This allows for direct compaction of waste into the back of the transfer trailer itself. The resultant high pressure requires that the transfer trailer frame must be upgraded to reinforced steel to withstand the impacts from the ram. This results in increased truck weight which does subtract somewhat from the vehicle’s overall load capacity. Economic analyses would be performed to see if the operational savings resulting from the use of a hydraulic ram exceed the resultant increase in long haul transport costs.
The baler is a refinement on the compactor that is the best of both worlds: it produces high-density waste without the need for reinforced and heavier hauling trucks. Baler equipment compressed waste into large self-contained bales or bricks which are further secured by wrapping them in wire. These large bales can be loaded onto flatbed trucks (no need for specialized vehicles) with simple forklifts. Being stable objects, they can be stacked in place without the need for truck sidewall necessary to contain loosely dumped waste. The downside is the cost, which can be a significant upfront capital investment However, for larger transfer stations with high pass-through capacities, a baler may provide the perfect cost-effective solution.
Upgrading you MRF: What to Consider Before Starting the Process
Waste Advantage Magazine│ July 2019
Upgrading your MRF is serious business and requires a lot of planning and thought prior to beginning the actual process of the upgrade.
Where to Begin
The first thing needed to begin any facility upgrade is a full evaluation of the need for the upgrade. Why do you need to upgrade? Has the volume increased? Have the materials the facility receives changed drastically and sorting needs changed? Has the end user (who accepts your commodities) changed their requirements? Has there been a territory expansion? Has the condition of, or maintenance to, the existing equipment become too large of a portion of the budget? There are any number of things that can trigger the need for an upgrade; however, identifying the reason(s) should be the first step in upgrading your MRF. Once the high-level project performance goals have been laid out and agreed upon, the appropriate professionals should be contacted to assist with the evaluation. Oftentimes it is helpful to have a thirdparty help determine your goals. There are several industry experts who can work to evaluate the waste stream, client requirements, permit needs, and develop the means and methods to go from the current status of your business to where you need to go during this growth or change period. These experts will help analyze your current material and equipment sorting approach and determine where you need to be in order to adjust to the business changes; once that is conceptually defined, the next step would be to determine what, if any, building changes would need to be made to accommodate the proposed changes. Let’s not get too far ahead though; let’s get back to what needs to be figured out early in the process.
Back to the Basics!
So, a consultant has been brought on board to help evaluate the waste stream and help plan the changes you require. There are some items that will need to be thought about when going through this process that will affect you before and during the process of the upgrade.
Is it Major or Minor?
Identifying the specific changes needed will help determine if a major or minor upgrade will be required. In some cases, minor upgrades can occur while you are still in operation and changes can be made during down time or with limited down time. These can consist of updating certain pieces of equipment, adding newer technology to the line such as an optical sorter, replacing a baler or many other things. Minor upgrades are easier to plan with minimal impact on the operations. For the rest of this article, we will focus on major upgrades. Major upgrades typically require extensive planning because several pieces of equipment may be added to the system or the system will be replaced in its entirety, which could also require building modifications, leading to additional site changes and a complete shutdown of the facility for several months. Let’s dig into major upgrades some more. Major upgrades will require a team of professionals to help with planning, budgeting, scheduling and execution. This team will consist of a recycling expert, equipment expert, Design/Build team, internal operations team, financing company (if required) and eventually an equipment supplier. As you go through the initial process of working on what the plan looks like, it will likely entail some or all of the following pieces:
• Equipment Upgrades: The first thing you need to identify is what equipment changes will be occurring in the building. This will be the epicenter and affect everything else we will talk about. The building design of an MRF is based around the needs of the system. The system needs to efficiently fit within the building so the operator can clearly access all pieces of the system for regular maintenance and cleaning. Therefore, the exact plan for the equipment, whether it is as minor
as adding, replacing or removing some pieces or replacing the entire system, your team should pay special attention to whether you will design the equipment to fit your existing building, or design the equipment for efficiency, performance, and cost, and then modify the building accordingly. Sorting systems, especially screen packages, like to be taller to be as effective as possible and minimize unnecessary conveyors. Many facilities try to cram equipment into buildings that are too small or too short. While this can work, the equipment often does not perform ideally, and there are many “extra” conveyors to make this work. The added equipment drives the system and maintenance costs up. Many times, it is more cost-effective to modify the building through targeted interventions, additions, or wholesale replacement and install as efficient a system as possible. Working with your assembled team of professionals should allow you to properly vet the different approaches. Remember, your specific situation drives any and all needs for building modifications, so let’s touch on those here for a few minutes.
Dirty MRFs and Clean Products
MSW Management│ May 2019
What separates winners from losers in a tight market? Since China declined to take further bulk quantities of recyclable materials from the US last year, unless they met new very stringent quality standards, the recycling market has experienced a downturn with the loss of its single largest market. Something similar happened to the recycling industry after the stock market crash and recession of 2008. Though in this earlier case it was a general dropoff in demand for recycled materials due to a fall in economic activity, in both cases the demand and price for recyclables were negatively impacted. And in both cases, the market for recyclable materials has and will recover.
While the recycling industry is working to find other markets, the industry winners will be those who increase productivity, improve quality, and cut prices. And this will depend on advances in sorting technology and concurrent improvements and innovations. At the forefront will be advances in sensor technology and optical sensing to achieve the necessary purity levels demanded by improving quality. And although advanced AI and robotics may one day create a “Smart MRF,” the human element will always remain paramount, requiring ever improved levels of training and intelligent, market focused planning.
Multi-Stream and Single-Stream MRFs
Single-stream MRFs are the opposite of multi-stream MRFs in every important operational characteristic. Instead of receiving multiple streams of waste from various sources and locations, single-stream MRFs receive waste directly from a single source, the community’s waste collection operations. As such, the commingled material that arrives at a single-stream MRF is far from pure, which give the facility its other name of “dirty MRF”. This type of facility relies primarily on machines to perform its sorting and separation operations. Waste arrives at the MRF’s tipping floor and is loaded onto a conveyor belt which carries the wastestream through various removal stations. Each of these stations is designed to remove a particular type of material from the waste. These machines perform their operations based on the size, electromagnetic properties, shape, weight, color, and density of the material being removed. The primary types of machines and the materials they remove are as follows:
• Magnetic separators for removal of ferrous metals: This is a simple and straightforward mechanism that relies upon electromagnetism to remove steel and other ferrous metals directly from the wastestream. What varies is the configuration of the magnets and the adjacent conveyor belt carrying the wastestream. The magnets either can be set overhead, pulling up the ferrous objects out of the wastestream passing underneath on the conveyor belt, or can be integrated into the belt itself, causing the ferrous metals to stick to the belt while the rest of the wastestream falls off into bins or another conveyor belt carrying the waste to the next removal station. The belts and the attached ferrous metals turn under at a roller located at the end of the conveyor belt. There, the metal is scraped from the belt by an edged blade and drops off into a designated collection bin.
• Eddy-current separators for the removal of non-ferrous metals: This is a more complex system than an electromagnet, but it is required to extract the bulk of the metals in the wastestream that are not ferrous. Its operation is based on the method of induced currents and the generation of an electromagnetic field from these currents. A collection of fixed magnets is arranged around the rim of rapidly spinning rotors. As the rotor spins, its magnets induce an electrical current in each piece of non-ferrous metal. This current, in turn, generates its own electromagnetic field in opposition to the field created by the fixed magnets. The two fields repel each other and the non-ferrous metal literally leaps off of the belt into a waiting receptacle.
Minimizing Impacts from Transfer Stations and MRF Operations
Waste Advantage Magazine│ May 2019
Transfer stations and material recovery facilities (MRFs) serve important functions to the greater community. They serve as a means to more efficiently transport municipal solid waste (MSW) for disposal and recover materials for recycling to minimize what is sent to the landfill. From a high level, they exist as purely positive forces with important functions. Why then, are they relegated to the far corners of industrial parks or adjacent to closed landfills? This issue relates to the complexities of managing the potentially negative impacts these facilities can have on their neighbors and the community as a whole. By better understanding the impacts your facility can have on the larger community you can better address them or use education to build a greater understanding and appreciation for the realities of your business. The impacts can be grouped into several categories: Vectors, Odors and Dust, Wind-Blown Debris, Environmental Concerns, and Traffic.
Any facility that receives solid waste, single stream recyclables or source separated material has an issue with vectors in one way or another. Vectors as a term covers nuisance animals that can carry disease. For solid waste facilities, this mostly deals with mice, rats and birds. There are several operational best practices to help minimize these populations. For the mice and rats, keeping the floor clean is important. In addition, designing a facility with minimal space to create homes can help stop a colony from getting a foothold. As a best-practice, a local pest control company may be engaged to set up bait block stations to keep the population of these low. Birds, on the other hand, can pose a difficult challenge. The birds will often roost in the roof rafters, and their waste can become a large issue. There are several strategies that can be effective in dealing with this, depending on your building type and the type of bird you are attempting to discourage. Bird wire—a wire that is strung across tipping aprons and similar areas—discourages the birds from nesting in the areas it is strung. In addition, you can install bird netting on the inside of your building to keep the birds from roosting in your ceiling. Another approach that can be effective is using air noise makers to disturb the birds. You must take proactive action to keep these vectors under control, as their populations not only impact your facility, but also your neighbors who will also pay the price if you do not address this.
Odors and Dust
The issue with odor and dust in transfer stations and MRFs can be greatly minimized through smart facility planning, operations and a few remediative approaches. When you are designing a facility, it is important to site the primary tipping bay doors away from the prevailing winds. In addition, high-speed doors can be installed on all exterior doors. These approaches can minimize the magnitude of odors and fugitive dust that are carried offsite. In addition, there are several negative air systems that can pull in and treat the facility air before releasing it. These systems can help control dust and odor. Another effective solution for dust and odor control is the use of a misting system. These systems use water and can incorporate chemical odor neutralizers to create a very fine mist over the primary work areas. A benefit to the misting systems is that they can be easily retrofitted to existing facilities with minimal disruption and yield impressive results. For MRFs, a dust extraction system with pickup points at the main dust generations points can also prove very effective.
Evaluating the Challenges and Benefits of Constructing a Solidification Pit at your Landfill Facility
Waste Advantage Magazine│ April 2019
Liquid waste presents a unique challenge and opportunity for landfill operators. There are many factors that should be figured into the decision on whether to locate a liquid bulking (solidification) operation at your landfill facility. These factors an be grouped into four categories to form a decision matrix: business case, environmental considerations, future growth and operational considerations. By clearly understanding all the pros and cons to co-locating a solidification operation at your landfill facility, the decision will be best suited to serve business needs now and in the future.
The first step to determining the viability of moving forward is to confirm that it makes business sense. At this stage, an assessment of local needs should be completed to determine if there is a need/opportunity for this line of business. Once the projected volume of incoming materials (both liquid/wet waste and potential bulking/solidification agents) has been assembled, a gross estimate of projected revenue this operation could generate will be available. The incurred expenses can then be contrast through the design, permitting, construction and ongoing operating costs. If this exercise demonstrates there is a viable business case to be made, you can proceed to the next steps.
Liquid waste (fracking liquids, boring fluid, etc.) is not allowed in landfills in its original form, which presents very real challenges but also opportunities. Excess moisture is a common concern/issue in landfills, and most landfill compliance issues relate to excess moisture. To then introduce materials(s) that have a high liquid content runs counter to the goal of keeping the material dry. There are many liquids that cannot be processed at a private or municipal sanitary facility or cannot be processed in another cost-effective manner. That is where liquid bulking/solidification can perform an important service. For these liquids, bulking/solidification and landfilling may be the best option from an economic standpoint if the processes can be performed in an environmentally responsible manner. (Author’s note: the term “bulking” means absorbing liquids with a dry solid; those liquids will likely release from the mix once compressed. The term “solidification” is the addition of
dry material where the liquids become bound to the material/reagent and will release little, or no liquids once compressed.)
Testing will need to be completed before liquid/wet wastes are approved for acceptance, solidification and disposal. Typically, liquid/wet wastes are reviewed for hazardous/non-hazardous categorization or other factors that would make it undesirable for disposal, such as high oil, salt or other constituents that could affect the biological environment within the landfill, significant odor potential or other similar factors. Once the liquid/wet waste material is deemed acceptable, test mixes are prepared (either in a lab or in the field) to see what ratios of admixtures/reagents can be used to make an appropriate mix for disposal. Consideration must be given to resulting moisture content (Are there no free liquids? Can the material be placed and compacted sufficiently?), short- and long-term liquids release (will the mix give up liquids once placed and surcharged by other wastes?), stability of the solidified materials (are they as strong as the rest of the landfill or will they provide weaker areas/slip planes that could cause failure?) and resulting recipe/solidification costs. Reagent/solidification agent costs directly affect the profitability/success of the operation as do mixing efforts and transportation of the blended materials to the landfill disposal location.
Making Sure Your Facility is Properly Equipped for CNG Conversion
Waste Advantage Magazine│ February 2019
Converting a fleet to compressed natural gas (CNG) can make a lot of sense to reduce fuel costs. Typical considerations toward making this decision include the cost of the new vehicles as well as the fueling infrastructure. An often-overlooked component, that is essential for a fleet CNG conversion, is the cost to modify the existing shop facility to ensure those new vehicles can be serviced in a safe and code compliant environment. It is essential to understand the activities that occur in the shop as they have a direct impact on the CNG retrofit building modifications.
Existing Shop Typical Improvements
As the existing shop is assessed, the first question should be about what might be required for it to be CNG compliant. While a qualified engineer or specialty consultant should be engaged to perform the detailed analysis and scoping, there are several elements that will likely need to be provided, as well as several items to avoid.
The existing ventilation system will likely need to be upgraded to afford more air changes per hour. The shop (if it is heated) is likely heated with a gas-fired unit or radiant tube heaters. These are typically not compatible with a CNG shop and will need replacement.
The height of the shop has a direct impact on the ventilation requirements. If the shop is shorter than 20′-0″, it may not be entirely viable for a CNG retrofit.
It is likely that the existing facility does not have a gas detection system. One may be required by the local Authority Having Jurisdiction (AHJ).
The walls that separate the shop from the administration offices will be required to be two-hour rated for a CNG Shop. If the current walls are not rated, upgrading these can be costly and disruptive to operations.
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Have you ever wondered how something as small as a leftover food we discard can fuel different parts of the world? Take a look at this video from BP about how a simple banana peel can be turned into jet fuel!