Editor’s Note: This article originally appeared in the June 2011 (Buyers Guide) issue of Stormwater magazine.
Improved street sweeping and vacuum technologies are helping communities throughout the United States comply with National Pollutant Discharge Elimination System (NPDES) Phase II control measure of pollution prevention and good housekeeping.
Systems such as regenerative air sweepers are further helping the environment by not pumping dirty particles back into the air or by using alternative fuels to power the machines. One Michigan contracting company is focusing on water efficiency by creating a vacuuming system that uses recycled sewer water in its operations.
And while the public may still not comprehend the relationship between street sweeping and clean water, their appreciation for the process is evident, municipal officials say.
Elgin, IL, residents’ regard for street sweepers matches that of their regard for the ice cream truck, says Dan Rich, an Elgin public works superintendent. “People love seeing the street sweepers, in part because they get cleaner streets,” says Rich. “I also think they feel a one-on-one relationship between the money they spend as taxpayers and what is a direct and viewable service.”
Last year, Elgin cleaned 476 tons of matter from 1,920 catch basins and 1,800 tons of matter from approximately 10,000 sweeping miles of street sweeping. And, during the fall leaf collection, the city gathered 22,300 cubic yards of leaves.
The numbers demonstrate the efficacy of its machines, Rich notes. “We could effectively argue that a good portion of that would end up in the stormwater system if it weren’t collected,” he says.
Elgin’s fleet is composed of sweepers from Elgin Sweeper Company, a subsidiary of Federal Signal, located within the city. The fleet includes five Pelicans, two Eagles, and a Megawind.
The Pelican is a three-wheel broom sweeper that now comes with three optional alternative fuel systems for compressed natural gas (CNG), liquefied petroleum gas (LPG) and liquified natural gas (LNG). The Pelican also has a waterless dust control option.
The Elgin Eagle is a four-wheel mechanical sweeper that has two optional alternative fuel systems, CNG and LPG, as well as a waterless dust option. It also has the Rule 1186 PM10 certification.
The Eagle has a dual-mode air suspension system, enabling operators to switch from a solid rear axle for sweeping and dumping stability to a fully sprung chassis for operator comfort and control during high-speed transport. “The city of Elgin was one of several communities involved in the development of the new Elgin Sweeper Megawind product,” says Rich. “During the design phase, the city of Elgin made several recommendations to Elgin Sweeper that included changes on the boom and swing arm that changed the height, swing, and overall operation of the rear boom
The city also offered ideas to change the way the machine applied water and in the style and design of the sweeping mechanism and pick head, Rich adds. “The Elgin Sweeper Company was great to work with, and Elgin Sweeper was able to effectively implement many of the suggested changes to the prototype,” he says. “The city of Elgin was so impressed with the end result that Elgin is now the owner of the first 13-yard Megawind to leave the production line. The machine is used daily in Elgin’s sweeping and catch basin cleaning operations, and has been a key in helping the city meet its Phase II goals.”
The Megawind encompasses a street sweeper, catch basin cleaner, and leaf and debris vacuum in one unit. It has a 12-inch vacuum hose with an articulated power boom. The boom features 180-degree hydraulic powered rotation for various positioning options, a high-performance vacuum system, and a choice of large-capacity tilt dumping debris bodies. System components include an “open throat” suction nozzle, trailing arm side brooms, and an extension broom.
The fleet has been highly effective in helping the city of Elgin meet its goals, Rich says.
“A portion of the National Pollutant Discharge Elimination System program requires that we keep the floatables out of the system,” he says. “We typically clean the catch basins in the city on a three- or three-and-a-half year rotation–upwards of a couple thousand catch basins a year.
“Our street sweeping program is an integral part of that. We have about 950 lane miles of street in Elgin, and we normally get in between 10 and 12 sweep cycles per year. On-street collection helps keep debris out of the catch basins and keeps the floatables out of the stormwater system.”
It may take two weeks to work through the entire city on one cycle, Rich says, adding that during spring and fall, the cycles are heavier, while June through August is lighter. All of the work is done in-house.
The Elgin sweepers pick up everything from large objects and leaves to small particles like fine silt, Rich notes.
“When we’re one with a catch basin or cleaning the street, it’s broom clean,” he says. “There’s nothing left.”
Elgin finances the catch basin cleaning from an enterprise fund for sewer maintenance, while the street sweeping is funded through the
general fund as a street operation. Elgin officials are contemplating the possibility of a stormwater utility; for now, there is no stormwater budget, says Rich.
Removing Leaves in Roseville
In Roseville, CA, the street sweepers are running once every three weeks through the residential area and on almost all commercial streets once every two weeks.
“It’s an aggressive program, and our goal is to get it out of the gutter before it reaches the catch basin,” says Jerry Dankbar, Roseville’s superintendent for street maintenance.
Roseville owns four Allianz Johnston street sweepers–two 610 models and two VT650 models–and one Elgin Crosswind street sweeper. The catch basins are cleaned with a street sweeper attachment; the city sends out a full drainage crew to inspect and clean every basin once every two years. The city has nearly 10,500 catch basins.
The air-powered Johnston units work well to pick up fines as well as heavier material, says Dankbar.
“They have one broom on the back, which will help scrub the street a little bit and pick up the heavier stuff,” he says. “The Johnston gives us the best of both worlds–mechanical and air broom–and that’s why we use them.
“We use the Elgin to pick up the fines and keep the foreign particles off of the street,” he adds. “We do it often enough that we don’t need to scrub the street every time with a heavy sweeper. We find that with a vacuum sweeper it works very well.”
Roseville also has an annual leaf removal program from November 1 to January 15. “We have set routes in the older sections of the city where we have most of the trees,” says Dankbar. “Our residents can either pile the leaves in the street for us to pick up, or they can bag the leaves and call us to have the bags picked up. We remove 550 to 600 tons of leaves each year through this program. All of the leaves are recycled at the county landfill. Our goal is to keep the drains clear to prevent flooding and to keep our drains, creeks, and streams clear from leaves.”
In Roseville, all of the street sweeping and catch basin cleaning is done in-house with the exception of cleaning some large CDS units that serve as filters for subdivisions that have been constructed in the last eight years. The city subcontracts out the twice-yearly inspection and cleaning for those units because the city’s own vacuum truck is not strong enough to clean up the silt from the bottom, Dankbar says.
Roseville residents have responded well to the street sweeping program because they like their streets to look good, Dankbar notes.
“I don’t know if they understand that we’re trying to keep it clean [to keep material] from going into the drains as much,” he says. “We’ve got an education program we’ve been doing for the last five years. It’s working pretty well to get the word out. They want us more often and they’d like to see us on a set day like garbage pickup, but we don’t have the resources to sweep on a set day.
“Since we do it once every three weeks, we keep doing it on a rotational schedule,” he continues. “The crew has their routes, so as they finish one, they go to the next.”
The street sweeping and drainage program accounts for about 25% of the overall budget, which includes paving, street signs, and
Roseville has been sweeping some permeable surfaces such as new parking lots with its air sweepers, but Dankbar says it’s too early to tell how effective that’s been.
He points out that the city of Monterey, CA, has performed studies that found, overall, the more a municipality sweeps its streets, the better the outcome for keeping unwanted matter out of stormwater.
For Roseville, the street sweeping program has been a success, says Dankbar.
“Our streets are very clean. We hardly get any complaints,” he says. Bicyclists have complained of obstructions in the road, but since the city has been cleaning bike trails on and off of the street, the number of complaints has decreased.
“We’re picking up less and less out of our catch basins because we have a regular program now,” says Dankbar. “We go out with a Vactor, but we don’t flush every line. We check it first and if it doesn’t need it, we don’t clean it. We just inspect it and clean it as needed, but we try to get to every drain every two years.”
In Noblesville, IN, street sweeping is almost a daily endeavor. The work is done with a fleet of five Tymco units, all of which were purchased at the same time.
“The reason we chose that particular model is that we do numerous services for the city,” says Len Finchum, the street commissioner. “We also have leaf pickup program. Because of that, we needed a method that was more efficient for cleanup.”
Noblesville officials studied the machines from several manufacturers, including mechanical and regenerative air street sweepers. The Model 600 Tymco street sweeper was favored for its ability to handle the diversity of work, from street sweeping to catch basin cleaning. The Tymco unit can be adjusted to pick up everything from large items to finer, granular sand.
“We have five different highways that intersect through the city, so we have a lot of truck traffic with different products and materials,” says Finchum. “From time to time, we are called upon to assist state highway cleanup from sand to larger products and large stones that get stuck at intersections. It does a good job with all of them.”
With the regenerative air system, the debris gathered by the pickup head–trash, dirt, and fines–is directed up the large-diameter, heavy-duty suction hose into the hopper. Because it is a regenerative air sweeper, it does not exhaust polluted air into the atmosphere.
The regenerative air system is closed-loop, using the force of a high-velocity controlled jet of air created by the blower wheel. The air stream takes in everything from fine dust particles to large debris, pulling it into a large hopper. The air loses velocity, and the larger debris falls to the bottom. A screen at the top of the hopper prevents items such as leaves, paper, cans, and rocks from leaving the hopper and entering the centrifugal dust separator.
The centrifugal dust separator spins the air clean until the micron-size dust particles are skimmed off into the hopper. Only clean air is returned to the blower to start the regenerative air cycle again.
In the summer, street sweeping occurs nearly daily in Noblesville. “As the weather changes and freezing temperatures come in, we try to get them out at least once a week if the weather allows it,” says Finchum. “We try to do our downtown twice a week because of the traffic there.”
Noblesville turns over its fleet every six to seven years to keep maintenance costs low, just dealing with normal wear of the machines.
“These machines have less general maintenance than a mechanical sweeper,” says Finchum. “The way these are designed, we’ve had very little maintenance on them, and we’ve had them for three seasons. With the turnover we have, we don’t have the wear or the corrosion. It has reduced our maintenance budget as far as keeping these sweepers going.”
He adds, “We’ve been very happy with this sweeper, and we turn in a report to the wastewater department every year, which goes to the Indiana Department of Environmental Management. It’s very important we get those credits for grants.”
Additionally, Noblesville residents have been very receptive to the street sweeping program, Finchum says. They appreciate the other services, such as the leaf pickup program. The city puts signs on streets prior to sweeping time so residents know to move their vehicles, and they are “very cooperative,” Finchum notes.
As the public is more educated about stormwater and clean water through the media, there is a greater awareness and understanding of what needs to be done, including why their streets are being swept, he says.
Using Recycled Water to Clean Pipes
Many communities have combined sewer–systems that collect sanitary sewage and stormwater runoff in a single pipe system.
Joe Schotthoefer, a fifth-generation manager at Doetsch Environmental Services, a full-service environmental contractor in Warren, MI, says his company has developed a new sewer cleaning process that involves using 100% recycled sewer water to clean large-diameter pipes.
“This process is very important to eliminating sewer overflows into riparian waterways,” he notes. “There is a niche market for large-diameter cleaning that has to do with NPDES. There isn’t specific equipment to fit this need for cleaning.”
Doetsch has essentially taken a conventional vacuum truck/sewer cleaner apart, made it larger, and split it into two trailers that also house the filtering operation.
“In years past, the only way to tackle a job was to adapt production equipment,” says Schotthoefer. “We took a look at inefficiencies by doing this and developed the equipment we
There were inefficiencies relating to safety and labor-intensiveness. Using recycled sewer water would address those, Schotthoefer says.
“We actually started focusing on recycling water before “˜green’ became such a big buzzword,” he adds.
On a typical day, his company would use more than 100,000 gallons of water to do a job, Schotthoefer says.
Although it’s “much easier to put a hose to a hydrant and say “˜here we go’ than to make this a stand-alone operation,” there are numerous environmental benefits to Doetsch’s new approach, says Schotthoefer.
“We’re not adding water back into the system that has to be treated later,” he says. “We’re not using treated water that would normally be used by the neighborhood. As far as the infrastructure goes, typically the amount of water we use we can’t always get from hydrants. That’s what led us to get excited about the ability to recycle.”
Building the machine in-house, Doetsch employees took a Goliath combination sewer cleaner and added two trailers to it. One houses the vacuum equipment and debris storage, and the other houses the final filtration as well as the high-pressure water pump and the hose reel.
“Everything is vacuumed and the solids are separated from the liquid,” says Schotthoefer. “The liquid goes through several stages of filtration until it’s usable to be put back into the high-pressure pump to be injected back into the sewer.”
Although many cities with combined sewer systems treat all of their stormwater, notes Schotthoefer, during heavy rain events, the system can’t always handle the volume of water and get it to the treatment plant quickly enough, so the whole system backs up. Such systems allow for an overflow, and if the municipality is near a water body, that’s where the overflow is directed. That overflow sometimes includes raw sewage.
“They need to treat it before they can discharge it into a riparian waterway, so therefore, in this cleaning process, while we are removing debris from these large pipes, we are restoring capacity, so they have storage if it backs up during a rain event,” he says. “They then have a bit more time to discharge treated water.”
Doetsch’s efforts begin with a site survey to determine the type and amount of debris.
“We set up our mobile operation and begin by vacuuming water to start the recycling process,” says Schotthoefer. “Once our tanks are full and we are ready to operate, the hose will traverse down the sewer pipe to a given distance and then we will retract it. As we retract the high-pressure hose with the cleaning head, it will bring material back to the access point, which is typically a manhole that is already installed.”
The process repeats as the cleaning head travels farther to bring the material back. The material is put into a dewatering hopper, and at some point during the cleaning operation, it is unhooked and a new one is put into its place.
The process picks up everything from sand and silt to heavier materials, such as rocks–even car parts, shopping carts, and bicycles, Schotthoefer notes.
“Typically, these have never been cleaned,” he says. “They’ve been installed in the 1950s and we don’t know what’s in there.”
Once the job is completed, a camera or sonar operation is used to verify capacity has been restored to the particular segment of the system.
Leasing Versus Buying
Some municipalities are finding it difficult to meet NPDES requirements on the leaner budgets with which they operate in the current economy. In an effort to save money, Pinellas County, FL, is considering leasing a street sweeper.
“The annual cost of leasing a sweeper with guaranteed 72-hour loaner equipment is considered to be a cheaper alternative,” says Kevin Murren, district operations manager for Pinellas County Permitted Stormwater Management Division.
The county used to have five street sweepers–two for the arterial road program and two for local roads, with one unit retained as a spare. Street sweeping comprised about 10% of the county’s stormwater budget.
“Through budget evaluation and analysis, it was recognized that the cost was hard to justify,” he says. “Through time, there’s been attrition to the point where we basically have two sweepers here. They are 10-year-old units, which, by today”˜s standards, are ancient.”
County management has figured through its budget reduction process that leasing a loaner unit within 72 hours is less expensive than the down time associated with an owned unit, Murren says.
“Until it actually goes into place, we don’t know it will prove to be financially superior, but we hope it will be,” he adds.
Pinellas County sweeps its arterial roads at least 12 cycles per year. The county is looking to replace an older unit with a 48-month leased
unit and has considered both an Elgin Eagle and an Allianz Johnston 4000.
The remainder of the streets are cleaned by a subcontracted company, which sweeps the streets four times a year, says Murren.
Drainage pipe and catch basin inlet cleaning is conducted in-house with three Aquatech vacuum trucks.
“Our program consists of maintaining internal filtration units to our permitted pond and general MS4 conveyance maintenance of inlets and
pipes,” says Murren.
Most of the debris picked up in Pinellas County’s street sweeping program is larger particles.
“A mechanical broom doesn’t get the finer parts,” he says. “We tend to deal with the larger debris, especially with arterial roads.”
Public complaints usually fall into two categories: some residents complain that they didn’t receive the service, when in fact they did. Others see it as a waste of money.
“We have to explain to them the larger scope of NPDES permits and water quality,” says Murren. “Once we’ve explained that to most people, they then understand.”