Street sweepers help municipalities meet federal and state regulations.

By Joseph Lynn Tilton

As the federal demand for cleaner water continues to intensify, cities and contractors are struggling for ways to abide by resulting regulations while remaining within budget. One element for meeting National Pollutant Discharge Elimination System (NPDES) regulations for stormwater cleanliness is the use of street sweepers, but with machines running $75,000 - $250,000 and up, that can prove a hefty investment, even for larger cities. Enter the manufacturer, the private contractor, and - in at least one instance - the state to the rescue.

Contractor Counsel

"The biggest part [of] maximizing stormwater systems and the cleanliness at the treatment plant is to keep catch basins clean, which eliminates material from flowing into the pipe to begin with. You must catch the particulate runoff before it enters the piping system," emphasizes Randy Johnson, president of Gap Pollution & Environmental Control in Johnstown, PA. "In our area, most of the smaller towns are going to centralized sewage treatment plants. Before, we had combination systems, with stormwater and septic all together, and combination systems had a constant flow. But with more and more stormwater lines separate from sewage lines, sediment has become a major challenge to keeping a system working when it's needed the most."

While Gap Pollution & Environmental Control's focus is on industrial cleaning, it has contracts with a dozen or so smaller communities in the region, handling those contracts on a fill-in basis. This makes equipment acquisition more affordable, keeps employees more fully employed in a business where the demand or need for services ebbs and flows, and makes it possible to offer that service at a more affordable price. Everyone, whether contractor, employee, or community, comes out a winner.

"We can go into a municipality and clean all 200 or so of their catch basins in a relatively short time versus manual cleaning. In the spring we'll clean out the antiskid material that's gotten in the catch basins during winter, and in the fall we'll pull out leaves and other debris," Johnson continues. The firm uses two GapSE vacuum trucks from GapVax Inc., also of Johnstown, that recycle the water used for flushing out the material. Water recycling keeps the machine on the job longer before there's need to recharge the tank.

After noting that they started up the other firm specifically to manufacture the equipment they use, Johnson comments, "With this technology we can clean anywhere from 60 to 100 catch basins a day, while cities doing it manually can only clean two or three. Cleaning a catch basin is relatively simple: We remove the grating with a hydraulic winch, lower the hose boom, and vacuum the debris out. One machine provides 3,600 cubic feet per minute at 28 inches of mercury while the other is capable of vacuuming 5,300 cubic feet per minute. If there's a brick in the inlet, it'll be in the truck."

He points out that catch basins in his area typically have a 3-ft. dropout area where heavier material has settled, which helps keep bricks and other solids out of the pipe. Actual cleaning, he adds, takes just five minutes.

Where possible, the communities have their streets swept before Johnson's firm cleans the catch basins. "The biggest challenge for communities in this area is budgeting. Some might have only 2,500 people, so we always try to have something to give them the best bang for the buck. We're always looking for better efficiencies with our equipment and are constantly working to improve our services."

A Word on Vacuum

While sweeper manufacturers talk about the strength of the vacuum action with their particular machines, Steve Schoenberger, president of Vector Technologies Ltd. in Milwaukee, puts it in perspective. "A street sweeper's vacuum is a fan-type system, while those we manufacture include a positive displacement or ROOTS style blower, which draws a very high vacuum. For example, our vacuum, measured in inches of water, is 380, while a typical fan-type vacuum will draw 15 inches. We can move just about anything that will fit in the hose, even when it weighs 250 pounds per square foot."

That technology also is designed to move material up to 1,400 ft. from the intake, with a 6-in. hose delivering 30 tons/hour or about 350 gpm for liquids. This technology obviously is not needed for your typical city street, so the fan type tends to be the vacuum technology of choice. "However, the additional power will tend to have appeal for varied specialty applications that municipalities often encounter," Schoenberger observes.

Sweeper Technology Explained

When it comes to experience in the marketplace, one of the older participants in street sweepers is Elgin Sweeper Company, a division of Federal Signal Corporation. "We've been manufacturing sweepers since 1914," declares Brian Giles, product manager at the Elgin, IL, headquarters. He continues, "Sweepers come in four categories: pure vacuum, regenerative vacuum, pure mechanical, and mechanical with vacuum fugitive-dust control." He cites the last technology as giving "the best of both worlds."

"The first is pretty much a nozzle that sucks up material, while a regenerative vacuum recirculates the air, keeping attendant dust down. The mechanical uses a broom rather than sucking any material and sweeps the material onto a conveyor to load into a hopper." He adds that pure vacuum and mechanical sweepers typically spray water to help control dust emissions.

"Though most particles are trapped by regenerative air sweepers, most still use water to help control dust generated by the side brooms that push material from the curb and gutter to the front of a pickup head and to help settle small particles into the hopper. Vacuum fugitive-dust control systems do not require water, as a small amount of vacuum pulls any dust generated into the sweeper where it is collected."

Regarding regulatory pressures, Giles states, "Street sweeping in California is being legislatively driven. PM10, Rule 1186, Subcategory 1190 cites the minimum pickup efficiency and maximum fugitive dust allowed. From the federal level, other than NPDES concerns regarding stormwater collection systems, there's nothing specific except that the cities should be employing [best management practices], and there are a lot of those out there, including street sweeping and inlet cleaning. Contractors and cities have to keep an eye on the law."

He then observes that within the industry, safety is a big issue, not only for the operator but also for other people around them. "This is why we have the Pelican, our urban sweeper for congested areas. There's a 360º view from the cab, which is above the hopper instead of in front of the hopper."

Both Sides of the Fence

When talking of design efficiency and operator ease, Raymond Massey, southern regional manager of Schwarze Industries Inc. in Huntsville, AL, can speak from both viewpoints. "I had my own sweeping business for 13 years before joining Schwarze. Mechanical sweepers used to be prevalent, but due to new air-quality regulations, we're seeing regenerative air sweepers more of a factor throughout the US. Mechanical sweepers continue strong in the Snowbelt for efficient heavy-debris removal. Regenerative air machines are being used more frequently to remove fine particles, which helps cities meet federal and state regulations."

He notes that street sweeping is becoming more frequent and credits this to air- and stormwater-quality regulations. "Before, street sweeping was considered largely a cosmetic move, but now it's more of a necessity. Municipalities are being pressured to keep their streets cleaned. They like to keep costs down, so they're looking for equipment that's more reliable and more durable to meet longer life expectancies."

Manufacturers such as Schwarze have responded. The Clean Air and Clean Water Acts of the early 1970s, for example, have prompted the move to machines that can handle dry particulates without raising dust, whether for city streets or for industrial operations, yet help ease the cost of operation by further refinements. Massey states, "We continue to develop machines to meet market demand, which is why we offer a full line of regenerative sweepers, mechanical sweepers, and fine-particulate dry-sweeping surface and air cleaners. This gives Schwarze the ability to solve any problems in any sweeping application."

Indianapolis Strategy

With about 750,000 inhabitants, Indianapolis prefers to contract out its street sweeping. Leaf collection is a separate operation. "We have the contract to sweep a 10-square-mile downtown area and all residential streets," explains Jim Katter, vice president and general manager for Advance Sweeping Services Inc. "Residential sweeping is done only once or twice a year, while downtown streets are swept daily, twice weekly, or weekly, depending on need. Our job is to keep the streets clean and material from entering the stormwater system." Last year, his company's contract totaled 27,000 lane-mi. of downtown streets and 4,000 mi. of residential streets and yielded 9,000 yd.³ of waste. Advance also responds to cleanups on a demand, emergency, and special-events basis for the city. The Indy 500 race and recent tornadoes provided a great need for immediate debris removal.

Katter continues, "All residential sweeping is in tandem. We're using a mechanical sweeper, followed by a regenerative air sweeper. This gives us the best of both worlds. Our sweeping fleet includes a Schwarze M5000 mechanical sweeper, an A7000 regenerative air, an A4000 regenerative air, with two of Sweeprite's Husky mechanical sweepers as our latest addition. The mechanical machines pick up the larger debris, while the regenerative air machines clean the gutter line and pick up the fine material left over - material not even visible to the naked eye. Since the sweepers are high-dump, they can discharge into a dump truck and keep on sweeping rather than having to make seven or eight trips a day to the landfill."

Stating that water is needed for dust control, he adds, "Even with extra spray bars, sweepers cannot always wet material sufficiently enough. And with 95% of material within 3 feet of the curb line, with a wire mesh broom moving at high speed, unless you dampen the material before moving it over to the pickup mechanism, you'll get dust. Sometimes in heavy, dry conditions, a flusher truck that just dampens the material is desirable."

He points out that using both mechanical and regenerative air keeps Advance downtown except on Thanksgiving, Christmas, and during severe storms. "While regenerative air does a better job at fine-material pickup than mechanical, you can't use them in freezing conditions with ice actively being picked up or the machine will freeze up. You can use the air machines, though, if it's dry and cold." He then warns that the operator must give special attention to wear and dust, which need to be controlled with lower rpms and less water in the hopper.

Still, the challenge is to keep the operation efficient and profitable. "From March through October we operate two shifts a day, doing residential from 8 a.m. to 5 p.m. and downtown 10 p.m. to 6 a.m. We have an extensive [preventative maintenance] program. All machines are cleaned daily, adjustments are made daily. After all, if you don't adjust your machine so brooms and heads perform, you'll have to resweep the area. Sweepers live in a dirty environment; if you don't keep moving parts and collection areas cleaned you're going to have wear and excess rust. Operators and mechanics share in the cleaning, and the machine is left so it can dry out nightly. Our operators and mechanics share in the maintenance, and it's all done with quality-control sheets, verifying that each step was done." This care makes it possible for Advance to minimize breakdowns and sweep 98% of the routes in one pass with the two machines.

"We get a lot of paper products, a lot of car parts, and the normal grit, dirt, and grime that get into streets and can be deposited in the stormwater system." Katter says goal is to get in and out of a sweep area quickly, and crews typically handle 20-50 residential lane-mi. per day and 76 mi. of downtown at night. This strategy, along with residential "No Parking" signs, minimizes traffic or parked-vehicle concerns. Still, strobes and warning lights on all machines, including the dump truck, help improve safety of operation.

When it comes to selecting machines for the job, as with other savvy operations, Advance Sweeping Services strives to match them with the conditions involved. "Indianapolis has a lot of cul-de-sacs, and it's hard to maneuver a big machine in them. That's why we've added the Sweeprite Husky to our lineup. It burns 1.9 gph versus 3.8 to 3.9 gph for the bigger trucks, is more maneuverable, and with just 17,000 [pounds gross vehicle weight], the operator doesn't need a commercial driver's license. Coupled with an initial lower cost, the smaller Husky is operating at 30% to 40% less expense than the larger mechanicals."

Goodbye, Mud

"The intent of NPDES Phase II is to ensure that only rainwater, nothing more, goes down the storm drain," says Mark Kinter, principal application engineer for Tennant Company Inc. in Minneapolis, MN. "The goal of various street sweeping operations is to ensure that the streets are clean and anything that would get into a storm drain is carted off before the next storm strikes."

Kinter, who has been with Tennant for 32 years, explains that NPDES II has six control measures:

1. Citizen education
2. Citizen involvement
3. Illicit discharge detection and elimination
4. Construction-site stormwater runoff control
5. Postconstruction stormwater management in new developments
6. Pollution prevention and good housekeeping for municipal operations

"Cities have to be responsible for cleaning up their areas, from city yards to streets," he maintains. "Yet 20 years ago, an EPA study found that street sweeping did not reduce stormwater pollution and in some cases actually increased it! In the last few years, technologies of street sweeping have radically changed that."

Kinter states that the principal problem 20 years ago with both air and mechanical brooms was their use of large volumes of water to control dust. "A majority of the older machines were not capable of picking up the mud left behind. In some cases, cities would use flusher trucks to flush that mud down the drain." He points out that street debris can be classified in three size ranges, with large, floatable items - such as styrene cups or plastic water bottles, which look bad but are not pollutants - among the larger items. Then comes sand and heavy debris, which he estimates make up 98% of the total solids, with silt accounting for the final 2%.

"Most sweepers were capable of picking up cups and most of the sand, but not the silt because they used water for dust control and left it behind as mud. The material they were getting out of the drains was mostly Styrofoam items and sand, while silt stayed in suspension and was flushed out into the waterways at the end of the pipeline. The key thing is you can't sweep mud," Kinter relates.

Then in September 2001, Tennant introduced its latest combination vacuumized broom sweeper, the Centurion. Because it is able to sweep with either no water or limited water for dust control, it doesn't have to deal with attempting to sweep mud. Thus, it can remove the silt that conventional wet sweeping can leave behind.

In the Evergreen State

Still, what's a city to do? "Washington State provides a street sweeping service for communities under 22,500 as a service - not for profit," says Mike Brace, special maintenance lead tech for the Washington Department of Transportation (DOT). "We've been doing it at the request of smaller communities because they don't usually have the necessary equipment. If they want it done on a regular basis, we contract ourselves to do it with the city on an overtime basis and receive pay rather than state aid. We base the contract on operating costs for running the machines and on labor costs. At the same time, this strategy ensures that residents taxed to cover their own city's street sweeping program aren't also taxed to support someone else's street sweeping program, which handily avoids the taxation-without-representation dilemma."

When possible, the sweeping's done the same time the DOT crew is sweeping the highway that passes through the community. This strategy makes the service more economical. Brace adds, "One of the biggest challenges is to create a safe environment for the traveling public and for our employees and still give our customers, the traveling public, the most environmentally sound job that they can have for the most bang for their tax dollar."

A Washington State sweeping crew includes an advance person to pick up large debris from in front of the machine, including lumber, tire carcasses, cardboard boxes, large plastics, and string and wire. "This keeps the operator in the cab and the whole production moving and has boosted our speed," Brace continues. "Last year, after a four-month lease, we took on a Tennant Centurion, which has both mechanical and vacuum brooms. Before, we were getting 3 to 4 miles of sweeping in a 10-hour day. Now we've more than doubled those miles." In heavy arterial areas, the crew includes two sweepers running in tandem; two truck-mounted attenuators with arrow boards for traffic control, each with a side dump box for the sweepers; and two truck-mounted message boards following to provide motorists advance warning of the project.

"When we're doing city streets we can get by with a whole lot less. There, besides the sweeper, one truck-mounted attenuator and one pickup-mounted message board is enough."

The Washington State operation has a trammel mill to recycle all street sweeping and vactor waste. "We are doing that for economic reasons. We can't just dump street sweepings in landfills. They will take it, but the price is high. When we process what we collect, we reuse as much as 80%, with only 20% actually going to the landfill," Brace explains.

Looking to the future, he concludes, "We need to keep up with current sweeping technology and the need to keep stormwater clean because DOT wants to lay lightly on the land, which is in agreement with the Department of Ecology."

Sweeping a Growing City

During the past few decades, the once-sleepy Canadian city of Edmonton has grown to nearly a million individuals, and provincial clean-water regulations have prompted the city to add sweeping to its services. "We have 15 Elgin Series F sweepers, covering 8,000 lane-kilometers, helping us keep heavy metals and organics out of the 84 outlets that flow into the North Saskatchewan River," states Margaret Li, civil engineering technologist for the city.

"We sweep all streets on the north side of the river and contract out the south side. Investing in sweepers was expensive, but seven years ago we decided it would be cheaper in the long run than to continue the practice we had of renting them." Downtown and residential streets are swept in the spring principally for picking up antiskid material laid down during winter. Downtown sweeping continues weekly from April to the end of October, while older residential areas with heavier leaf drop get another sweeping in the fall, Li explains.

The spring sweep is from 7 a.m. to 7 p.m., with advance signing asking residents to keep their cars off the street the next day. "We do ticket and tow in heavily populated areas," Li comments, adding that this backup measure is not extensively used. Fall residential sweeping takes 20-25 days, with sweepers running eight hours a day when residents usually have departed for work.

"Come winter, we mount snowplows on our sweepers and use them to keep the streets clear. Then, during a 10-14-day mild-weather window in January and February, those machines sweep the downtown area. This made the sweepers more affordable and helped us decide to purchase our own," Li explains.

Downward Pricing

Although price has been a factor with street sweeping and vacuuming equipment, Mark Stratton, technical sales manager for Sweeprite Mfg. Inc. in Regina, SK, Canada, reports that industrywide prices have been dropping during the past few years, when compared with inflation as well as product improvement. "The cost of municipal street sweepers has definitely come down; efficiency is much higher than 10 years ago. Water quality is more and more an issue, and cleaner streets lead to cleaner water. Yet different areas have different ways of looking at things. For example, communities in Kansas look to spring and fall cleanup while there are people in the northeast that want cleaning done on a weekly basis."

He adds that inlet protection is not an issue. "Most communities have the outlook of street sweeping. If they sweep the streets on a regular basis, the cost of caring for the catch basins and the vacuum equipment needed to clean those basins can be reduced. Regular street sweeping greatly reduces the need to go into the inlets and into the pipe, ending up at the treatment plant or settling ponds."

Stratton notes that his firm, which has annual sales of about $2.3 million, is one of the smaller players in the sweeper market. "Our original intent was to target smaller communities, those with 5,000 to 10,000 population. We're now finding larger communities are looking at this type of equipment as well." After citing the same PM10 California ruling as Elgin's Giles did, he comments, "We're aggressively pursuing PM10 testing with our equipment; not in-house but through independent parties. We'd like to see this done industrywide but independently."

Taking Care of the Customer

Although there has been consolidation in the industry, manufacturers affirm that there's plenty of competition out there, and part of their strategy is to do what they can to improve customer service.

Terry Galica, director of customer relations for Clean Earth Environmental Group in Birmingham, AL, reports that a focus is on immediate response for end users. "Each of our VacAll dealers is assigned an in-house representative so the two parties can develop a relationship. Inside reps handle more than one dealer [they have 50 dealers nationwide], but the idea is to foster the relationship between the headquarters and the dealers. So when the dealer calls in and needs some assistance, the rep has the background he needs to give the customer the best service."

Galica states that dealers are able to handle 95% of customer problems. But when they're stumped, "We do whatever we need to solve the problem. We can handle it over the phone or we can fly right out there and solve the problem at their facility - whatever's needed."

More Than Streets

Bobby Johnson, marketing manager for Tymco International Ltd. in Waco, TX, points out that his firm's founder, B.W. Young, invented the regenerative air concept for sweepers more than 30 years ago. He comments, "One challenge in this industry is that sweeping hasn't been a priority item with most cities until the regulations started hitting. It's more of a priority now because of the recognized environmental benefit. Also, people are using sweepers for more than just city streets. You can find units at waste material spills, race tracks, airports, amusement parks, long-term excavation sites, parking lots, even in tunnels."

Author Joseph Lynn Tilton is a frequent contributor to Forester Media publications.

SW - March/April 2003

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