Minneapolis-St. Paul International Airport (MSP) had a decision to make when the Metropolitan Airports Commission signed a new agreement with the Minnesota Pollution Control Agency in spring 2013. MSP essentially had two options: Overhaul the drainage system in its parking structures or change the way crews manage and discharge water runoff when cleaning them.
In the past, runoff from cleaning operations was discharged directly into the storm sewer system, which ultimately drains into Mississippi River tributaries, explains Paul Sichko, MSP's assistant director of operations. Rerouting drainage into the airport's sanitary sewer, however, would cost $5 million to $6 million; so Sichko looked for other alternatives.
He found an attractive option just a few months later, at a winter operations conference for hub airports presented by the American Association of Airport Executives. By using cleaning equipment that captures pollutants and recycles the water used to clean garage floors, MSP could avoid the cost and operational disruptions of a plumbing project.
Project: Parking Garage Maintenance
Location: Minneapolis-St. Paul Int'l Airport
Regulatory Document: Nat'l Pollutant Discharge Elimination System agreement
Parking Structures: 4 garages at Terminal 1 (2 with 7 levels, 2 with nine levels); 2 garages at Terminal 2, each with 8 levels
Total Parking: Approx. 22,000 spaces
Surface Cleaning Equipment: Municipal Cleaning Vehicle, by Triverus
Equipment Supplier: M-B Companies
Equipment Fleet: 4 cleaning vehicles; 2 dual-service trailers
Approx. Cost: $1 million (includes warranty, onsite setup & training)
Of Note: Equipment captures, filters & recycles cleaning water, allowing airport to release it into storm sewer system
The specific equipment that caught Sichko's eye was the Municipal Cleaning Vehicle, manufactured by Triverus and supplied by M-B Companies. After further research, the airport purchased four cleaning vehicles and two support trailers (with spare parts) for about $1 million - a fraction of what it would have cost to alter the drainage system for the parking garages. Even with expenses for ongoing equipment maintenance figured into the equation, the cost-benefit analysis tipped sharply against infrastructure change. The lead time needed to engineer, fund and install new parking ramp drainage systems was also a factor, recalls Sichko.
MSP crews maintain six different parking structures, with approximately 22,000 parking spaces spread among 48 different levels. Further complicating matters, weather constraints make it difficult to clean the pavement floors from mid-October through the end of March.
"We have to maintain a very aggressive cleaning schedule," Sichko informs. "Previously, we would close a 500-space section for seven days; use high pressure hoses, scrubbers and agitators to clean the pavement; then flush the surface with water."
Using the new equipment, crews can clean the same 500-space area in two days. "If you multiply 500 spaces by a maximum (parking fee) of $20 per day, that is $10,000 in lost revenue," he explains. "Theoretically, by reducing the cleaning time to two days, we are realizing an additional $50,000 in parking revenue."
The equipment MSP purchased uses surface cleaning technology Triverus originally developed to clean flight decks on aircraft carriers for the U.S. Navy, explains Steve Karlin, senior vice president for M-B Companies. The objective was to restore the proper coefficient of friction on flight deck surfaces while managing cleaning waste and preventing pollution. The company later adapted the technology for a commercial machine to clean pavement in civilian environments, including airports.
The resulting product is a 50-inch cleaning deck that attaches to the front end of a Bobcat Toolcat(tm) vehicle. The combination allows operators to maneuver close to walls and other structures within parking garages, and clean individual spaces between two parked cars. The cleaning unit sprays 200 gallons of clean water at 2,000 psi and recovers approximately 190 gallons of contaminated water in a rear-mounted tank. No detergents or chemicals are needed, notes Karlin.
Maintenance personnel then drive the vehicle to a dual-service trailer they towed to the area being cleaned. It filters out contaminants and returns gray water for additional cleaning in about eight minutes, estimates MSP Field Maintenance Manager Lee Spangrud. "The contaminated sludge that remains is tested by our environmental personnel. Thus far, they have determined that the waste is not hazardous and we are able to dispose of it in our standard dump areas," reports Spangrud. "We lose a little water in the cleaning process, but most of it is reclaimed for reuse."
Salt is one of the main elements the system removes from the cleaning water. "One of the main reasons we clean our parking decks is to remove the salt residue so it doesn't deteriorate the concrete," explains MSP Equipment Supervisor Chuck Kanuit.
Being able to remove such contaminants then discharge the cleaning water into storm sewers is a major advantage, notes Sichko.
The equipment's cleaning head and water storage module are designed to detach easily to free up the Toolcat(tm) for other jobs, but MSP doesn't currently plan to use the vehicles for anything other than cleaning pavements. "These vehicles are running continuously from April to the middle of October," reports Sichko. "During the winter we can (also) use them in other spaces. But they are flexible, and a smaller airport would find them very useful year-round."
Making it Their Own
After their first full season with the new cleaning equipment, MSP maintenance, operations and environmental personnel are all pleased with its performance so far.
"Any new equipment purchase has to go through a shakedown cruise," Sichko acknowledges. "There's always a learning curve on how to operate and maintain it. We enjoy working with manufacturers and always appreciate their willingness to listen to the end user and to make adjustments and design changes."
In this case, MSP personnel suggested a few modifications to the trailer. "Some hooks here, some clips there, a valve system that might work better - things like that," explains Spangrud. "Our mechanics do a good job working with vendors. M-B and Triverus have been really good listening to us and implementing changes."
The airport and its maintenance crews are similarly accustomed to making changes. "There was a change in regulations, but that's routine for us," reflects Sichko.