preliminary design report - sediment control …sedimentcontrolsystems.com/sludge monsters.doc ·...

Dr. Orson Smith

May 1, 2000

New Tools for the Maintenance of Sewage Lagoons for Rural and Native Villages in Alaska

Prepared by:

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NEW TOOLS FOR THE MAINTENANCE OF SEWAGE LAGOONS

FOR RURAL AND NATIVE VILLAGES IN ALASKA

Prepared By:GREGORY C. SMITH

CE-A603, ARCTIC ENGINEERING, SPRING 1999

UNIVERSITY OF ALASKA ANCHORAGE

Gregory C. Smith, P.E.3330 Shamrock Street

Anchorage, Alaska 99504(907) 337-6817 (voice)(907) 337-8168 (fax)

[email protected] (e-mail)

May 1, 2000

ABSTRACT

The sanitation conditions in some rural and native villages are comparable to third world countries. Residents in nearly half of the 270 villages in Alaska must use buckets as toilets. Sewage lagoons accumulate a pile of broken and unbroken plastic bags of human waste well above the water level. Probably unseen in Alaska, there are new machines and devices to maintain these remote lagoons. Amphibious excavators could pull the waste into the water. In ice-covered times, these excavators could penetrate the ice and reduce the piles of waste that accumulate above the ice. Another device, a sludge sled has been designed to remove accumulated sludge from the bottom of these lagoons.

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1.0 INTRODUCTION

In the arctic engineering class, videotape was presented declaring the sanitation conditions in some rural and native villages to be comparable to third world countries. Residents in nearly half of the 270 villages in Alaska must use buckets as toilets.1 Most villages have sewage lagoons for the residents to dump their “honey buckets”. The videotape showed how the buckets are sometimes lined with plastic bags to keep the contents from spilling onto the residents as they used different methods of transportation to the sewage lagoons. The contents with the plastic bags were dumped over a railing at one end of a lagoon accumulating in a pile of broken and unbroken collections of human waste to remain well above the water level until, hopefully, the shear weight of the waste would finally cause a slide into the water where the bacteria could feed during months the pond was not ice-covered.

Probably unseen in Alaska, there are new machines to maintain these remote lagoons. An amphibious excavator floating in a lagoon could pull the waste piles into the water for biological treatment. In ice-covered times, on an occasional basis, these excavators could penetrate the ice and continue to reduce the piles of waste that accumulate above the ice without exposing a conventional excavator or the operator to an accidental dunking.

Once the waste in is in the water, bacteria and algae eat the waste and form sludge. A sludge sled has been designed by Dr. Jim Martel of the U.S. Army Cold Regions Research and Engineering Laboratory (USACRREL) to remove accumulated sludge from the bottom of the lagoons.

2.0 REVIEW OF WASTEWATER TREATMENT SYSTEMS

The principal components of a wastewater treatment system can generally be classified as either active or passive. Active components usually include some mechanical or chemical augmentation to accelerate or improve the component’s treatment process. Well understood examples include forced aeration of biological reactors and rotating collectors for clarifiers (both mechanical processes), and the addition of flocculating agents to improve sedimentation and the use of chlorine for effluent polishing (both chemical processes). Passive components generally do not employ mechanical or chemical augmentation with typical examples including simple lagoons and constructed wetlands. The fundamental difference between active and passive components is the use of energy. Active components generally require power sources while passive components require little or no generated power to function. In addition, passive components generally do not require the use of operator provided chemicals to function properly.

Larger communities where throughputs are high and land use must be minimized generally employ such systems. Moreover, the frequently larger size of such systems justifies the labor, power, and consumable costs.

These systems are frequently inappropriate for small rural communities where high throughput is not required and land use is not a constraint. For these communities, wastewater treatment may

Gregory C. Smith May 1, 2000

An Alaskan by Choice Page 1 of 10

be efficiently provided by systems comprised of passive components. The advantages of such systems are:

Minimal to no power usage. Minimal labor requirements. Minimal maintenance requirements. Component robustness. Minimal use of consumables (e.g., chemical agents).

Fortunately, for most small rural communities, particularly in Alaska, land is generally available for plant use and throughputs are typically low. Moreover, unlike many active systems where the components must be protected from the cold, passive systems can be designed such that weather enclosures are not required thereby reducing cost and complexity while improving robustness. This is frequently accomplished by simply increasing the size and depth of the system’s components. Such size requirements generally do not impact land use for rural communities, unlike that for larger communities and urban areas.

3.0 SEWAGE LAGOONS IN REMOTE ALASKA

Wastewater and human waste from honey buckets can be treated in sewage lagoons. Lagoons are often the most economical alternative for waste treatment in remote villages because they are simple to construct as opposed to an enclosed pressure piped system. Maintenance is very low. Some lagoons are called stabilization ponds. These are usually shallow earthen basins 1 to 2 meters (3 to 6 feet) deep to biologically treat a variety of wastes. Because of permafrost conditions in remote Alaska, some ponds are constructed by building berms on top of the ground instead of digging a basin in the frozen ground. Depending upon the type of wastes, the depth of the pond, and the amount of aeration, if any, the conditions in the pond can range from aerobic to anaerobic or a combination of both. Aerobic bacteria require free oxygen for growth. Anaerobic bacteria can grow without free oxygen. The major disadvantage of anaerobic ponds is the smell.

Most ponds are a mixture of the aerobic and the anaerobic conditions with the aerobic bacteria living near the surface and the anaerobic bacteria living near the bottom in distinct layers much like the thermocline temperature difference a swimmer may touch with the toes. These combination ponds are called facultative. Facultative ponds, which are also stabilization ponds, are typically deeper than the oxidation ponds. A stabilization pond is a lined pond designed and constructed to hold the wastes for a retention time of about six months to retain the sewage through the winter. The stabilization lagoon functions at full capacity during the summer months while the sewage temperature is compatible with the biological processes. As the temperature cools, the lagoon’s biological treatment processes decrease in efficiency and reach a low point in midwinter when the lagoon is covered with ice and the sewage temperature is low. The ice cover prevents the honey bucket contents from reaching the water and it prevents aeration. With the low amount of available oxygen, the pond becomes anaerobic. During this time of year, biological treatment continues, but at much reduced pace. Sewage solids settle to the bottom of the stabilization lagoon and are stored until increased biological activity resumes in the spring.



Unlined ponds are typically called percolation lagoons because they allow the water to seep out through the bottom. However these ponds, get their bottoms clogged rather quickly if they are loaded with untreated sewage. The plastic bags from honey buckets and disposable diapers will quickly block the water flow through the bottom of the pond. The biological bacteria, and photosynthetic algae that live and die in the ponds eat the waste. Their bodies make up the sludge that also clogs the pond bottom. The advantage of an anaerobic pond is the reduced amount of sludge that is produced.2 Both the lined ponds and single, receiving lagoons accumulate sludge.

4.0 THE SLUDGE SOLUTION

Lagoon cleaning and the disposal of the resulting sludge are a maintenance problem that will have to be dealt with periodically over the years. The villages cannot keep throwing stuff into a pond without it becoming inoperative or just getting full. Historically, the removal of sludge in a lined pond has proven to be a difficult problem. If the pond is not drained, then a dredge operator working without the advantage of seeing where he is digging will probably puncture the liner. If the pond is drained, the village usually has no other place to put their wastes while the pond out of service during the cleaning, which is usually performed with heavy equipment. Draining and cleaning, especially in remote villages, is an expensive operation.

A sludge sled has been designed by Dr. Jim Martel of USACRREL to remove accumulated sludge from the bottom of the lagoon while the lagoon is still in operation.3

The sludge sled is essentially a large wedge-shaped scoop. It is aluminum and weighs 70 kg (155 lbs). The sled is dragged along the bottom of the lagoon by a rope or cable attached to the front of the sled to a winch on the embankment. Another cable is attached to the rear of the sled to help with alignment. The winches are moved along the embankment to position the sled over



different portions of the lagoon bottom. Sludge is channeled to a submersible, air-powered pump, which pumps the sludge to truck or a drying bed. The test at a site in Fort Greeley, concluded that two days of effort would keep up with the year’s production of sludge. For an “average-sized” lagoon, an operator should be able to remove enough sludge in a few days each year to control the level of sludge. The total cost of this device including pump and hose was less than $4,000 (not including the winches). Plans and specifications are available.4

5.0 THE AMPHIBIOUS EXCAVATOR SOLUTION

5.1 The barge-mounted amphibious excavator

An amphibious excavator can enter the lagoon to pull down the piles of honey bucket waste that accumulate above the water level. Aquarius Systems5 in Wisconsin manufactures a barge-mounted excavator that is apparently the smallest solution. The shipping length is 30 feet long and 8.5 feet wide. Overwidth trucking permits are not required. The amphibious excavator is not just a tracked machine attached to a barge; the tracked undercarriage is not included. The excavator’s barge has three sets of dual wheels for land travel and stability in the water. The hydraulically positioned wheels can be used on land for transportation. In the water, the wheels are good for added stability when they are lowered to the bottom. The excavator can work in water to 11.5 feet deep. The limit may be that the machine, an AE-12, can only dig 12 feet deep anyway. As for pulling wastes down a slope into the water, the digging depth is not a concern. The machine will be able to reach the piles above it and work them, a piece at a time, if necessary, into the water with the machine. A conventional, tracked excavator would have to stay on the sloped embankment and avoid sliding into the water. Much of the effort would also be expended trying to sweep the piles towards the water with the swing motor that is designed to be weak so as to avoid side-loading the boom structure. Any amphibious excavator can take advantage of its position in the water directly downslope of the piles to pull on the piles as backhoes are designed to work – by pulling.



5.2 The pontoon-mounted, tracked amphibious excavator

The more mobile, but wider solutions come from three manufacturers. The machines from Wilco Marsh Buggies6, built in Louisiana, look impressive. They have some huge machines in the 400 class. Their conventional, tracked counterparts weigh 100,000 pounds. The smaller amphibious excavators in the 200 class are less than half the weight. Only a couple groupings of photos are included.

Marsh Buggies7, a competitor to Wilco Marsh Buggies, has similar products. An identical solution that is available here in the United States is from Quality Industries8 in Louisiana. They were difficult to find. Quality Industries quickly responded to a request for information with brochures and pictures in an overnight mail package.



Quality Industries is apparently making use of the longer booms. Although the compromise is a smaller bucket, the extra reach around a large floating platform is to be welcomed. One of their pictures is a smaller machine, also a Link Belt excavator. It is shown below.

Jerry Fischer with the United States Department of the Interior showed that the Bureau used a pontoon-mounted, tracked amphibious excavator in the Rio Grande9. The Water Operation and Maintenance bulletin did not mention a specific manufacturer because information “…is not to be construed as an endorsement of any product or firm by the Bureau of Reclamation.” However, Bill Kolodnicki10 with the U.S. Fish and Wildlife Service in Connecticut helped to identify Quality Industries as the manufacturer of their machine. Bill Kolodnicki provided a phone number, too. Anita Flanagan11 with Iroquois Gas helped to track down Quality Industries.

5.3 A specially-designed amphibious excavator from Canada

Although Normrock Industries12 in Canada did not respond with information for this report, their machine is unique enough to deserve to be included as an amphibious excavator solution for the village lagoons in Alaska. In point of fact, their amphibious excavator’s name is Amphibex.



6.0 SHIPPING CONSIDERATIONS

The machines need to be able to be transported to the villages to work in their lagoons. While most of the work in the lagoons should be during the summer months when the ponds are not ice-covered and the biological activity is at its best performance, the amphibious excavators can be used in the winter to break through the ice and pull down the piles of waste. Some transportation may need to be during the winter because of the village locations. Many villages are not connected to the road system or they only have winter roads. Even if the amphibious excavators have trouble with the ice, which can be three feet thick, they can move the piles from the dumping area onto the ice without the fear of sinking a machine. The Amphibex from Canada advertises that it can prevent or break up ice jams. All the amphibious excavators, for that matter, could attack ice jams without the fear of sinking – a decided advantage over conventional excavators that cannot float.

The smallest machine was the AE-12 by Aquarius Systems. At a length of 30 feet and a width of 8.5 feet, it can be shipped in the C-130 cargo planes, which can use the short runways associated with a lot of villages. Although the standard shipping height is 10’-3”, the glass and metal part of the cab is even removable for shipping. The weight is only 20,000 pounds, well within limits.



It is conceivable that a C-130 can bring in the barge-mounted, Aquarius Systems’ amphibious excavator on a flight to a village and pick it up a day or two later when another palletized load arrives. In this airborne solution, a major consideration is the cleaning and sterilization, perhaps with chlorine, before the amphibious excavator can be reloaded for removal to another village. Some villages do not have running water for a pressure washer, but there may be a way to use available standing water. In the winter, with lower water temperatures causing decreased biological activity in the lagoons, fecal coliforms live longer, giving cause for health concerns. Shipping by truck for the barge-mounted amphibious excavator is shown below.

Shipping for the pontoon-mounted, tracked amphibious excavators would almost have to be by truck unless they are barged to coastal villages. Some of them are 18 feet wide. Trucking for a relatively large, pontoon-mounted, amphibious excavator by Quality Industries is shown below.



Trucking will probably perform shipping for the Canadian Amphibex, too. As with the Aquarius Systems barge-mounted excavator, the Amphibex raises itself up so the truck can drive out from under it.

The outrigger uprights in these photos are also available on the Quality Industries machines.

7.0 CONCLUSIONS

The sludge sled can help remove sludge while allowing the lagoon to stay in service. The cost for fabricating and utilizing the sleds is small enough that every village with a lagoon should have one. The sleds should be utilized with a trash pump capable of passing solids because the test pond at Fort Greeley may not have been heavily loaded with disposable diapers. More investigation may be needed, but the sled needs publicity.

These new breeds of excavators, the amphibious excavators, can clean up the piles of waste that are on the slopes of lagoons. They, too, need more publicity. As a start, Village Safe Water should be contacted and given a copy of this report, which was created for the arctic engineering class requirements.

8.0 REFERENCES

1. From the Alaska Reference room at UAA, Alaska’s Rural Sanitation Strategy, TD 524.A4 A45 1994.

2. Henry, J. Glynn and Heinke, Gary W., Environmental Science and Engineering, 2nd Ed. Prentice-Hall, Inc., NJ (1996).

3. Martel, C. James, “The Sludge Sled: A New Device for Removing Sludge from Lagoons,” 5th International Symposium on Cold Regions Development (ISCORD 97). Anchorage, AK, May 4-10, 1997.

4. Martel, C. James, “Maintain Wastewater Lagoons With a Sludge Sled,” Facilities Engineering Application Program, (1997).

5. Aquarius Systems, Inc., PO Box 215, North Prairie, WI, 53153, Phone: (800) 328-6555 Brochure 6808, www.aquarius-sysytems.com.



6. Wilco Marsh Buggies, Inc., David Galley, salesman, PO Box 710 Marrero, Louisiana 70037, Phone: (800) 253-0869, www.wilcomarshbuggies.com

7. Marsh Buggies, Inc., Perry Autin, salesman, 2018 Engineers Road, Belle Chasse, Louisiana 70037, Phone: (800) 264-6868, www.marshbuggies.com

8. Quality Industries, Inc., PO Box 406, Thibodaux, LA 70302, Phone: (800) 447-8403, Brochure, www.qualityindustries.com.

9. Fischer, Jerry, United States Department of the Interior, [email protected].

10. Kolodnicki, Bill, U.S. Fish and Wildlife Service, [email protected].

11. Flanagan, Anita, Iroquois Gas Company, [email protected].

12. Normrock Industries, Canada, Mr. Norman Grant, Owner, www.normrock.ca/, Phone: (800) 830-9080.



preliminary design report - sediment control …sedimentcontrolsystems.com/sludge monsters.doc ·...

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