There is no shortage of decisions that need to be made early in the process of designing a MRF that will suit your operations in the short and long term. The earlier you get your design/build partner involved with this process and teamed up with your operations team as well as your equipment supplier, the higher the likelihood of avoiding many of the issues.
By Jeff Eriks and Evan Williams
Material Recovery Facilities (MRF) can be a deceptively simple concept. Once you get past the initial concept of an enclosure for tipping materials to be sorted, running material through a sortation system, and trucking out the sorted products to their final destination, the nuance of how to best perform those tasks begins to present itself. Other questions regarding how the site will function and accommodate future changes will begin to come into focus as well. In our work, we have observed and studied many MRFs across the country. Many of them are great facilities run by skilled operators and we have also seen many that need a re-evaluation of their layout and operations procedures. One constant we observed across the board is that there are typical critical areas of consideration that are often missed or incompletely addressed in many MRFs. These mistakes can be grouped by the area of the operation: the Office and Employee Support Areas, MRF Shop, Process Area, Tipping Hall, Bale Storage, Site Area, and Planning for the Future.
Office and Employee Support Areas
The office and employee areas are a critical part of a properly functioning MRF. They provide areas for the admin staff to be located, as well as areas for the operations team to have a break area, locker rooms, and meeting spaces. During the initial facility scoping and planning phases, the design, equipment vendor, and owner teams should really work out a detailed operations plan. This includes whether multiple shifts will be used to accurately reflect the staffing levels at the facility throughout the day to ensure what is designed and built will address that sufficiently as well as to not overbuild in areas that are not needed.
Inadequately understanding the needs of these spaces and building spaces to accommodate can complicate several areas of performance for different employee types.
A typical issue that arises in designing spaces for office staff is to simplify the operations for initial needs. This often leads to tightly defined offices with minimal opportunity for expansion or modification. Often, MRF sites have regional safety, admin, accounting, and related staff that need temporary offices, or similar accommodations, and the area is simply not available.
For full-time MRF operations employees, this can manifest in areas that may initially meet their needs, but they may not accommodate future needs. For example, if your initial plan is to operate one shift for 20 sorters and you design the locker room for exactly that headcount and fail to account for your longer term goal of two-shifts, then what you will encounter is that the locker room will not work at shift changes. That will either require expensive re-work or a tight space that is unpleasant for staff, complicating employee retention efforts.
During that initial scoping exercise, the operator really needs to decide if they will be using a third-party staffing company as a part of their staffing approach at their MRF. This approach often requires a dedicated office either adjacent to the employee breakroom, or a separate office for them to conduct their admin tasks as well as employee management.
Accommodating all of the required tasks in locations that flow well from an operational perspective is certainly an important facet of the Admin Area design, but how staff get to/from that area from the site and the sort system is an important consideration from both a safety and operational efficiency perspective. If there is no good way to get from the sorting system to the break and locker rooms, timed lunch and bathroom breaks can end up being longer than desired. In addition, if you do not provide a short and direct path to the Admin Areas, staff may walk through areas with yellow iron and forklifts, presenting additional and unnecessary safety risks. Putting some additional effort in the planning stage to lay out how employees will move through the facility and make changes to ensure that is done safely is a critical task that is often missed.
safest and most efficient way to design a site. Photos courtesy of Cambridge Companies.
MRF Shop
MRF shop areas are essential to ensure your sort system is able to function at the highest level. When planning the facility, the facility maintenance manager and equipment supplier are critical to include in that discussion to ensure the supplied space will perform as needed.
Often MRF Shops are not designed with enough space to store the needed parts to keep the system up and running. This often includes spare motors, belts, screen shafts, balter wire, etc. The equipment vendor should be able to provide a recommended list of spare parts that should be kept on hand and the facility maintenance manager should be able to weigh in on consumables like belts to lay out how much storage is needed.
When designing the actual shop, the manager should be able to identify and/or provide cut sheets for the actual equipment they plan on locating in that facility. That way, the plan can reflect those items as well as any support systems they require. That can include proper three-phase power supplies, dedicated ventilation for welding, storage for fab steel, and similar items. Having those conversations upfront will help ensure what is built best aligns with how the manager plans on running the facility.
Almost as important as what is in the shop is where it is located. When the MRF Shop is designed, consideration should be given to how materials will be delivered as well as how the team will access the facility. For example, if the shop anticipates deliveries to be via trucks with liftgates, all the doors can be at grade, but if a loading dock is needed, perhaps locating the MRF Shop close to the loading docks typically associated with the Bale Storage Area would make sense. An additional consideration regarding placement relates to yellow iron. If the MRF is a stand-alone operation, the yellow iron may need to be maintained in the MRF Shop, so any access would need to accommodate those larger vehicles.
Process Area
The process is the most complex part of the MRF and presents the most opportunities for errors and oversights. Following are several common mistakes and ways to avoid or address them.
Comfort
A common issue in new and legacy facilities is the issue of employee comfort for staff working on the sort system, especially in hot or cold climates. Many facilities use sort cabins to provide specific areas that are climate controlled, but this presents further issues with who has access to the temperature controls. In addition, OSHA challenges that if you condition a space, it needs to conform to certain parameters. Further complicating matters is that the energy codes that have been adopted in many areas of the country do not allow for ‘Partially Conditioned’ spaces and the authority having jurisdiction (AHJ) may require your sort cabins to meet the ever-increasing thermal envelope requirements of those energy codes. To help avoid or minimize issues arising down the road, be sure to fully plan out and get approval of those cabins during the initial design, as leaving those details to be sorted out down the road can lead to an unacceptable result and costly re-working.
Lighting
Another common error seen at MRFs is too little or too much lighting in certain areas. This is often due to overall building lighting located at the ceiling being evenly distributed, disregarding the elevation(s) of the sort platforms beneath and other obstructions. This often leads to high-output lights being much too close to staff creating lighting ‘hot’ spots that can even interfere with some optical sorters. The best solution is to perform a photometric plan reflecting the lighting at the various levels and updating accordingly. An opposite issue often comes up in areas where the sort equipment blocks the overhead lighting. This can be dealt with by planning around some, but often the best solution is to build the lighting and electrical system with a set-aside in the electric panels for added lighting that can be located once the system is built to ensure the new lights are in area(s) where they are most effective.
Outlets
When installing the system, it is common to overlook convenience outlets as well as house air for maintenance purposes. This is not necessarily an issue, as it is easily addressed via a pre-startup walk through with the ops team where those locations can be identified, but the project team should carry a budget line item, so that it is not a change order down the road.
Access Area
When designing the building enclosure around the equipment, the ops teams and the equipment vendor should be included to identify areas for equipment access both for daily cleaning and more involved service. This often results in wider clear areas between the equipment and the building structure, increased building height to clean taller equipment, additional perimeter access doors, as well as added overhead steel to install hoist beams or employee fall-arrest tie-offs.
Location
Another common error is to fully design and then construct the facility from an early phase or sales layout drawing provided by the equipment supplier. It is very common for final pit layouts, electrical drop locations and breaker requirements, and baler locations to move somewhat through the process. Often the changes are minor, but where the systems are highly engineered, having critical elements in the wrong location can be a big deal. This can lead to expensive and time-consuming re-work that can be avoided. Keep engaged with the equipment vendor through weekly calls and involve them in the design team to minimize this risk. Also, using a BIM model, Navisworks, Revit, or similar for the design helps to look at the overall interaction between the system and the building around it.
Fires
An evolving area of consideration for MRFs and an area rife with errors relates to the fire suppression system. As the fire risks present in MRFs continue to be better understood and strategies for minimizing the risks of fire and ways to mitigate it post-ignition continue to change, an overhead system with minimal under-equipment coverage that was common 10 to 20 years ago will most likely not be acceptable now. The NFPA13R which covers fire sprinkler design and installation, is increasing coverage requirements and changing storage and sprinkler requirements for commodities, especially plastics, which has a significant impact on the system design. Spending the time to better understand the requirements of the code, as well as any supplemental requirements that your insurance carrier might add above what code requires, will better allow you to account for all the costs and system needs earlier in the process.
Tipping Hall
It is not unusual to visit a MRF and see incoming material packed to the rafters and spilling out the doors onto the tipping apron. The material is not really the issue, but it is a reflection of a confluence of issues that may range from inadequate initial planning, labor management, to equipment maintenance. Not all these factors can be managed, but they can be minimized by designing the tipping area to address the material and operational factors that are anticipated.
A common error seen in the tipping operation is an inadequate number of tipping positions. This is often due to the planning phase, dividing the tons received per day, by the tons tipped per truck, by the hours of operation, to confirm the number of tipping positions. However, the inbound flow of material is rarely linear, and you need to design for your times of peak flow.
In addition, when designing the floor storage area, you need to group your tonnage by type of vehicle and tip cycle time, then deduct the material flowing through the system to plan out how that on-floor material pile will change throughout the day. Ideally, when the system needs to shut down for the operating day, they have worked through the material pile that is tipped daily.
One additional consideration that is often missed is accommodating clean loads. Most MRFs do receive some clean loads that simply need to be baled. This can be addressed by a tipping door adjacent to the baler in-feed or a direct feed conveyor in the tipping area. If the direct feed in the tipping area is selected, the floor should be designed to allow for a material storage area large enough to justify a baler run of that commodity.
Bale Storage
Within the bale storage areas of MRFs, it is common to see a lack of wall protection to ensure the materials remain stacked while protecting the building structure from impacts. There are several approaches—from steel guardrail assemblies to cast-in-place concrete walls, or steel angles bolted to the floor. Which approach makes sense entirely depends on your operation and your tolerance for risk versus the cost of more robust protection assemblies.
An emerging mistake that is being seen more often relates to the storage height of the baled goods. Specifically, the more recent NFPA13R versions are more restrictive to how high Group A plastics can be stacked before they are considered high pile storage. The most common approach is to employ a more intensive sprinkler over the Class A plastics bales, but this is something that is challenging to add later in the process. Ideally, you will work with the site operations teams to plan out the area needed for the more intense sprinkler coverage and build that into the sprinkler design.
Facility Site Plan
The MRF is not just the building for housing the sorting equipment, it is also the entire site consisting of a system to receive, tip, sort, and distribute goods for re-use. A common issue with many MRF site plans is insufficient vehicle queuing at the in-bound and out-bound scales. This will vary greatly depending on each facility’s operational needs, but the development teams should really focus on peak vehicle times, as well as typical scale cycle times to build out a queuing plan to ensure the plan can accommodate the anticipated traffic. If the provided scales just barely accommodate the anticipated traffic, it would be wise to consider ways to speed up the cycle time (RFID, tare weights, etc.) or to design the site, so a second scale could be easily added in the future without disrupting ongoing operations.
Another area where many facilities fall short is how they plan for the residual load-out. The residual material can represent a number of loads throughout the day, so placing them in a location that does not disrupt in-bound and out-bound traffic is ideal. In addition, care should be taken to ensure the vehicle maneuvers needed to access the residual are user friendly. The biggest variable here from a design perspective is how does the operator want to handle the residual and how to best incorporate that into the site.
When planning the site, careful attention should be given to how the scale house, if they have one, is operated. Depending on if it is part of the main building or an ancillary building, your needs will change drastically. If the building is remote, depending on distance and how busy the MRF is, the major question is whether or not you supply a small break area and restroom for that employee or do they need to walk to the building for these facilities. This all depends on the client and it is a decision that could change years down the road.
Lastly, identifying what types of visitors will use the site has a huge impact on parking requirements, a training or education center as well as if an elevator ends up being required. The operator needs to make a lot of decisions early in the design process on what visitors expect or want onsite. Ensuring safe parking areas and access to the building is critical along with what floor is their access on and if you are allowing them within the actual process area. Regarding the site, if you expect busloads of kids, then having driving lanes and parking spaces for those will be a must. If you expect groups of 20 driving separately, then you need to accommodate the parking. All these items must be discussed early in the planning process.
Making the Right Decisions
There is no shortage of decisions that need to be made early in the process of designing a MRF that will suit your operations in the short and long term. The earlier you get your design/build partner involved with this process and teamed up with your operations team as well as your equipment supplier, the higher the likelihood of avoiding many of the issues mentioned. This assumes your partner has the experience to identify these and ask the right questions. Choose your partners wisely, they will absolutely make your life easy or extremely difficult, like any other project. | WA
Jeff Eriks is President and Evan Williams is a Design Project Manager at Cambridge Companies, Inc., a design-build firm, specializing in the environmental and waste industries with more than 30 years of experience covering more than 250 projects. During this time, Cambridge has successfully completed all types of solid waste design-build projects including transfer stations, recycling centers/MRFs, RNG facilities, truck and heavy equipment maintenance shops, landfill support facilities, office buildings, and more. The Cambridge team continually monitors industry trends and ever-evolving needs to provide superior and relevant solutions when planning and building new facilities to ultimately benefit clients needing design-build solutions. Jeff can be reached at [email protected], or Evan can be reached at [email protected]. For more information, visit www.cambridgecoinc.com.