Transfer Stations

Transfer Station Retrofits and Expansions: Rethinking Inside and Outside the Box for Reuse of Your Facility

By focusing capital improvements in areas that are most needed, existing solid waste transfer station operating life can be extended in a cost-effective manner, resulting in beneficial reuse of solid waste facilities.

Shane Womack

Existing solid waste transfer stations are being forced into use beyond their planned capacity and design life, and with Capital Improvements Program budgets stretched to the breaking point, financing and constructing a new solid waste transfer station is not always feasible. The rigors of locating and permitting a new solid waste transfer station alone can make the prospects of replacement seem unattainable.

There is a growing trend of retrofitting and expanding existing solid waste transfer stations. Rethinking inside and outside the transfer station “box” for reuse provides a pathway for existing solid waste transfer stations to continue to meet the needs of the communities they serve. By focusing capital improvements in areas that are most needed, existing solid waste transfer station operating life can be extended to address site specific differences in operations and waste streams in a cost-effective and efficient manner.

It has often been said that form follows function, and within an existing transfer station site, functionality is the most important factor when looking for a way to increase throughput and extend facility life. Examples of rethinking include: consideration of separate entrances to segregate citizen traffic, commercial traffic, visitors and employees; separate and/or automated scales for each type of user; separate tipping areas for citizens, commercial and recyclables; designated parking areas for transfer trailers; re-routing of traffic throughout the site to minimize or eliminate crossings of citizen and commercial traffic; and segregation of spaces for different users to provide for uninterrupted traffic flow.

Rethinking for Reuse

The Goal of Operational Efficiency Improvement

Through the lifecycle of a transfer station site, the areas designated for specific uses are often changed, rearranged and reused for various purposes as the need arises. This can result in overall site operational inefficiency, as the various areas are in competition with one another for space and ingress and egress of vehicles.

Taking a fresh look at the overall site, and re-thinking through how each of the specific use areas interact with one another, will result in ideas and opportunities to improve operational efficiency of the site. This article will discuss ideas that have been put into place on existing transfer station sites and have provided improvements to operational efficiency and extended facility useful life.

Change in Processes or Services

Changing the way that processes are implemented or services are provided to customers when they come to a transfer station site should be considered as a viable way of improving how the site works for both users and operators. If a process is confusing for customers, or cumbersome for operators, the results can lead to frustrating and un-safe situations.

Residential or self-haul customers most often arrive with loads of varying size and type. Consideration of offering alternative points of deposition to these types of customers is one way of changing processes and services to improve operational efficiency of use and increase safety. This may be accomplished by providing a separate entrance or drop-off area for residential customers with small loads.

Addition of a residential drop-off by-pass lane and drop-off area with roll-off containers for recyclables can provide a means of removing a portion of customers from the traffic queue, thereby reducing wait times and increasing overall throughput without having to route these customers through the transfer station. Although these customers do have to come into and flow through the transfer station site, their separation from other traffic types will aid in increasing overall throughput.

Throughput Increase

Throughput is defined as the amount of work that can be performed or the amount of output that can be produced by a system in a given period of time. In manufacturing facilities, changes to processes are intended to increase efficiency, thereby leading to increased throughput. The same principles used in manufacturing facilities can be applied to transfer stations. However, in transfer stations, the amount of output is measured by the amount of tons of waste or recyclables that can be received, separated, baled and transferred over the daily hours of operation.

Increases in throughput can be directly linked to increased tipping floor space, which includes designated areas for unloading stalls. Providing additional and separate tipping floor areas for residential or self-haul customers, commercial customers and recyclables can significantly increase the throughput of a transfer station. By providing separate areas for tipping/unloading, material storage/processing and material loadout, more customers can be moved through the transfer station during the course of daily operations, and wait times can be reduced.

Design-Life Extension

Extension of the design-life of a transfer station can vary from refurbishment of an existing tipping floor or hopper, to a full-scale retrofit and renovation project. The challenge is to determine the most practical and economical methods of making improvements to an existing facility for reuse, while keeping the existing facility in operation.

Expansion of tipping floor space to facilitate separation of traffic should be considered as a part of the overall strategy of improving operational efficiency. Separate tipping floor spaces for self-haul, commercial and recyclables will provide the flexibility needed to extend existing transfer station service life and increase user and operator safety.

Combining a tipping floor space addition with traffic segregation and changes in processes or services will lead to accomplishing the goal of operational efficiency improvement, and extend the life of the transfer station.

Traffic Flow and Routing

Traffic flow both off-site and on-site is crucial to making transfer stations operationally safe and efficient. By rethinking traffic flow patterns, signing, striping and traffic segregation, enhancements can be made to reduce (or eliminate) traffic interruptions, improve operational efficiency of use, accommodate new uses, and increase safety within an existing transfer station site dramatically and economically.

On-site traffic routing

Most transfer station sites have a single point of entry and exit, which can be both a blessing and a curse. The blessing is that greater control of who comes in and out of the site is accomplished with a single point of entry. The curse is that everyone is competing for the same space when entering and the same space when exiting.

One method to improve on-site traffic routing is to segregate the different types of traffic at the entry point of the site, and keep them separated while on the site through the use of circular traffic paths that minimize or eliminate crossings. For maximum efficiency and increased safety, the circular traffic paths should all flow in the same direction, moving the segregated traffic types into, through, and out of the site.

At a minimum, segregate traffic types into residential or self-haul, commercial, transfer vehicles and employees/visitors where possible. This will allow the commercial and transfer vehicles to enter and exit the site more efficiently, and will improve service and safety for the residential or self-haul customers and employees/visitors. Traffic segregation may be accomplished by clear signage, color codes and pavement striping from the entrance to point of deposition and then to the exit.

If traffic crossings are necessary and not avoidable, then clear “stop”, “yield” and “merge” signage must be in place and maintained in order to keep the traffic safely flowing. If space is available, consider the use of traffic circles in lieu of four-way stops. Traffic will continue to flow with less backups.

Re-evaluating the direction of traffic flow into and out of an existing transfer station can often lead to some out of the box ideas. Reversing the flow of customer or commercial traffic into and out of the transfer station tipping floor, or the flow of transfer trucks into and out of the tunnel, in some instances can provide a means of creating circular traffic flow patterns and reducing crossings of traffic.

Off-site traffic routing

Routing customers to the transfer station site can often be as challenging as routing customers within the transfer station site. Clear signage directing customers to the transfer station site is a vital part of the overall traffic routing plan.

Sufficient space for traffic queuing at transfer station entrances is a must. If long lines are forming in front of or after the scale house, consider the following alternatives:

  • Add length to the queuing space in front of the scale house

  • Add length to the queuing space after the scale house and the point of deposition

  • Make provision for a commercial-only lane with a dedicated scale and automated tare weight system

  • Provide a bypass lane for employees and visitors

  • Add a new scale house and additional lanes

Transfer Station Additions

Tipping Floor Expansion

Tipping floors are the most used and most sought-after spaces on the entire transfer station site. In order to extend transfer station useful life, creative uses of space are required on transfer station floors to provide storage, segregation of traffic and waste/recyclable type, and space to maneuver vehicles and equipment.

An investment in additional tipping floor space is one way that can significantly extend the design-life of an existing transfer station facility. If space is available on the existing site, the addition of tipping floor space on the opposite side of the transfer station hopper(s) can significantly increase processing capacity without having to construct new hoppers or tunnels. This additional space may be added while keeping the existing transfer station in operation, as accessibility to the hopper(s) is still available from one side. With separate tipping floor areas, the added bonus of segregation of traffic may be realized. Segregation of traffic leads to increased site safety and less frustration for users and operators.

If tipping floor space for recyclables competes for tipping floor space for waste, consider adding a separate recyclable tipping floor space to the existing transfer station. If possible, a new entrance could be added to the existing transfer station dedicated just for recyclables in order to create separation of traffic.

Self-Haul Area Addition

The addition of a separate self-haul area for segregation of space for self-haul users from commercial users is one of the best ways to improve transfer station efficiency and customer safety. By providing a separate unloading area for self-haul customers, throughput times are decreased substantially for both self-haul and commercial customers because they are no longer competing for the same space.

Self-haul area additions can be as simple as using or constructing a paved area outside of the transfer station building for self-haul load deposition into containers and transfer (depending on site usage regulations), or may involve construction of additional tipping floor space.

Scale House Improvements / Automation

Traffic type segregation improvements to entrance road lanes in combination with improvements to scale house capabilities in the form of automation for commercial customers and transfer trucks can significantly improve site efficiency. Card readers or radio frequency identification devices (RFIDs) allow commercial and transfer trucks to enter and exit the transfer station in less time, which provides an opportunity for cost savings.

Providing an Alternative Pathway

Rethinking inside and outside the transfer station “box” for reuse provides a pathway for existing solid waste transfer stations to continue to meet the needs of the communities they serve. The methods presented can be incorporated by transfer station owners and operators to improve existing transfer station site operational efficiency, traffic flow and safety. By focusing capital improvements in areas that are most needed, existing solid waste transfer station operating life can be extended in a cost-effective manner, resulting in beneficial reuse of solid waste facilities.

Shane R. Womack, P.E., is a Senior Project Manager for HDR Engineering’s Federal, Energy and Resource Management Business Group (Chattanooga, TN). His responsibilities include project and design management for solid waste facility projects, as well as leading civil design and quality control activities for water, wastewater and renewable energy facilities. Shane may be reached at (423) 634-0170 or via e-mail at [email protected].

References

  • Prescott Transfer Station, City of Prescott, Arizona

  • 27th Avenue Transfer Station, City of Phoenix, Arizona

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