Cities and towns had to choose either the "combined" or "separate" approach to designing and operating a sewerage system. Sometimes that choice was pre-determined by either circumstance or history. It was also soon realized that both types require actual maintenance. (see Design Choices for explanation of "separate" and "combined" sewer systems)

In the early years of new "separate" systems (Memphis, TN, etc.), it was recognized not only that manholes had to be an integral feature of the sewers, but that (especially in the outlying, terminal reaches of the collector sewer systems) flushing was needed. Flushing could not remove the need for physical cleaning in all reaches of the system, but it would help in the outer reaches where minimal flows (and, as such, minimal cleansing velocities) were being realized. Flush tanks (both automatic and manual) were developed and installed at the upstream ends of terminal reaches of sewer. The maximum extent of a flush tank's effectiveness (downstream) was soon learned to be 800 to 1000 feet at best.

Soon after manholes came into wider use, it was realized that sand and grit were getting into the sewer through the vent holes. (Manholes generally used cast-iron rim and cover assemblies, with most of the covers including vent holes.) A device called a "dirt pan" was developed and installed beneath the covers to catch sand and gravel before it could fall into the sewer. It was hoped that using such devices would lessen the number of blockages encountered in the sewer mains.

Flush tanks were of both the automatic variety and the manually-operated types. Heads of 6' to 8' were attained in the flush tanks. All required some level of personal attention to help assure that they were operating correctly. Water was brought to the flush tanks by either direct connections to nearby water mains, or by water wagons. (Putting water directly into the involved sewer mains via fire hoses, etc., from the sources, was thought by many to not always provide enough flushing power to cleanse away settled sand, grit, etc.) With the use of flush tanks, a relatively large volume of water was accumulated in the flush tank and then released (as a sizeable surge) into the immediately down-gradient sewer main. Many types of flush tank designs and/or mechanisms were developed over the years, including those by the Van Vranken Flush-Tank Company, the Rhoads-Williams Siphon, and the Pacific Flush-Tank Company (the Miller Siphon).

Almost all flush tank setups incorporated a "lamp-hole" assembly at a location on the sewer immediately down-gradient of the tank (proper). Off the lamp-hole was a lateral (horizontal) pipe connecting the vertical riser of the lamp-hole to the storage reservoir of the tank. This "inter-connect" served two purposes:

• As an overflow: in case the reservoir became overfilled, the overflowing water would travel through the lamp-hole setup and on into the down-gradient sewer.
• As an air relief system: to allow any air traveling up-gradient (rare, but it could happen) a place to vent, since the reservoir of the flush tank physically blocked off the air's escape.

In some cities (example: New Haven, Connecticut), to save capital money, water was delivered (via water wagons, etc.) to the flushing points and released directly into a manhole and then into the involved reach of sewer, often in combination with an ovoid (oval-shaped) wooden ball. The ball (sized slightly less in size than the diameter of the sewer pipe, and with a tag line attached) was pushed down the pipe by the release of water. In doing so, debris was pushed ahead of it -- downstream to the next manhole. Such an approach was often used at manholes within the overall conveyance system -- more so than at terminal end manholes. Such an approach also resulted in more real attention being paid to the condition of the involved sewers.

Sewerage agencies believed the flushing of sewers (by the use of flush tanks or by other methods) to provide at least two (2) benefits:

• The flushing of settled solids out of the slow-flowing portions of the involved gravity sewage collection/conveyance system ... thereby, lessening the chances for stoppages in the sewers and the production of odors from the decomposition of the solids sitting in the sewer pipe. NOTE: It would take many years before it was fully recognized that "flushing" was only effective for approximately 400-500 feet downstream of the entrance point of the flushing water.
• The turbulence of the flushing water surging through the sewers was believed to mix air (O2) with the sewage, helping to" treat" the sewage before it was discharged into the nearest river or stream or lake.

In 1907, in a sampling of 138 U.S. cities with populations of 30,000 or more, 30 used flush tanks, 78 applied water obtained directly from fire hydrants, and 27 used both. New Haven, Connecticut, was the only one then using portable tanks for the source of water -- often used in combination with an ovoid.

In 1940, it was reported that in the Los Angeles, California, area alone, nearly 11,500 flushing structures were in place; 6580 were "automatic" (six different mechanisms) and 2500 "manual," with the balance utilizing hauled water. Automatic flushing mechanisms were usually utilized on the sewers with "flatter" grades; manual ones on sewers with gradients of 1.5% or more.

Some communities used storm water as a primary source of flushing water. It was collected from catch basins and roof drains connected to the sewer whenever it rained. Certain cities developed storage facilities to collect and store storm runoff, to later be released in surges as the flushing water.

Several systems got their flushing water from either tidewater, nearby streams, lakes (Ex: the City of Milwaukee in the early days pumped 40,000 gpm of Lake Michigan water into its sewers for flushing purposes), or rivers, or (in certain instances) the sewage itself was in effect dammed up and released periodically to flush the down-gradient sewer (Ex: San Diego system).

Several innovative approaches to flushing sewers were developed. One such example was in the Washington, D.C., area: the Tiber sewer (a "combined" system) discharged into the eastern branch of the Potomac River at an entrance level about 5 feet below low tide. The sewer was put into service in 1875; it consisted of a wood plank bottom, battered sidewalls, and a brick/masonry arched crown. During low rainfall periods, solids deposition (and odors) became a problem.

A system of gates was installed near the upper end of the 1½-mile-long sewer; the gates backed up flow in the Tiber Creek. Twice a day (during low tide), the gates were opened up, allowing approximately 4 million gallons of creek water to surge through the sewer and help sweep settled solids out into the Potomac. See sketch of the gate assembly below.

It must be noted that utilization of the "siphons," initially developed for use in flush tanks, was expanded in succeeding years for "dosing" filters in WWTFs and WTFs, for dosing leach fields in septic tank systems, and many other applications in the water/wastewater fields.

It was also recognized that flushing did not mitigate all sewer cleaning issues. At times, other means had to be employed. "Pills" (round wooden balls) were often employed, especially if the operators were fairly certain that sticks, stones, or other hard materials were not present in the blockage. The sewage flowing in the sewers pushed the "pill" downstream; if enough sewage was not available, flush water was added. The "pill" had to be caught by a maintenance worker standing in a nearby down-gradient manhole -- no tag line was normally used. Initially, a small ball was floated through, then a slightly larger one, and so on until a ball of the diameter of the involved sewer main (or slightly less) could be passed through. The more modern-day techniques of "balling" were derived from the early "pill" approach. The operative principle of the "pill" was the resultant scouring action of the water as it squeezed through between the surface of the "pill" and the inside wall of the sewer.

In larger sewer mains (12" diameter or larger), the "pill" was normally not as effective. In these instances, a carriage device was developed for use; it traveled on wheels down through the sewer as it was pulled through the pipe. It was in essence similar to a bucket on wheels. Its shape was cylindrical, but slightly smaller in diameter than the inside diameter of the sewer being cleaned. Again, the scouring action of the water (sewage) squeezing through between the carriage assembly and the wall of the pipe helped loosen up deposited solids to be collected in the "bucket."

Another mechanism developed early on for cleaning sewers was a "disk," often made of wood. It was pulled through the sewer; as a result, the debris was scraped up and pulled along to the next manhole.

When a sewer was entirely stopped up, so no rope or tag line could be floated through, an opening had to be forced through; rods of various kinds were developed for this. Since the logistics of working through (and within) a manhole limited the length of the rods that could be used, sectionalized rods that were made to be easily joined together in the manhole were developed. Early rods used short lengths of pipe -- but wooden sewer rods 3 to 3½ feet long, utilizing unique coupling mechanisms (several variations were patented), soon evolved. When assembled, they were forced through the obstruction by working them back and forth, or sometimes driving them forward with a mallet or hammer. Several tools were developed to be attached to the front end to remove roots, create an opening in the blockage, scrap out grit, etc.

The worst case sometimes resulted in the sewer having to be dug up in order to physically remove a blockage.

One of the early pioneers in the development and manufacturing of sewer maintenance equipment was the Champion Potato Machinery Company of Hammond, Indiana. They started off in 1897 making potato harvesting equipment. In the early 1900s, the company's name was changed to OK Champion (O.K. standing for Otto Knoerzer, the founder of the Champion Potato Machinery Company). As early as 1905, Knoerzer began testing sewer cleaning equipment to meet the needs of the City of Hammond. The city had a problem with sand getting into and settling out in its sewers.

In the early years, before specialized equipment came along to help clean sewers, one unique approach to cleaning a sewer was practiced by the City of Hammond (maybe others):

First a rat was caught (maybe near a local slaughterhouse) and put in a cage. The cage (with the rat in it) was set down in the invert of the sewer at a manhole. Next a rat terrier (dog) was put into the next downstream manhole; with a tag line tied to it. When the dog sensed the presence of the rat, he would run up through the sewer towards the cage ... dragging the tag line with him (or her).

The dog was then lifted to the surface and the tag line then used to pull through a rope -- which, in turn, was used to insert heavier tools, etc., into/through the sewer. Oh yes, the dog got the rat as his "reward."

OK Champion developed cleaning equipment to improve upon the ability of the above noted "cleaning" processes, and has been in the business ever since.
A Mr. John Kuhlman took charge of the City of Hammond, Indiana, sewers in 1905. He personally invented a sewer cleaning machine for use in the city's system. Eventually, OK Champion manufactured the device (known as the "bucket") for commercial distribution.

All in all, many types of devices/mechanisms were tried as means of cleaning sewers in the early years, more specifically, jointed rods, rope, chain, steel buckets, ovoids, scrapers and drags of various designs, cylindrical scrapers, brushes, and wooden "pills" (balls). Men, horses or engines, and winches/hoists were all used as the specific job dictated.

The following chart provides an idea of the size of the sewage conveyance systems for certain American cities in 1907, and the place of disposal of the involved sewage. About this time, approximately 28,000,000 people lived in urban areas in the United States overall; it was then estimated that the raw sewage produced by 6.5 million of those people was being discharged into harbors and tidal estuaries along the seacoasts; the sewage of another 20.4 million was discharged to inland streams, rivers, or lakes; the remaining 1.1 million's sewage was treated by some type of purification works. Using (or "disposing" of) the sewage for irrigation was common (24+ locations) in the arid/southwestern states. Sewage farming didn't really fare well in the northern or eastern areas of the country.

American Cities' and Towns' Sewerage Infrastructure - 1907 (Sampling)

The following chart provides information on the number of different types of sewage purification processes in use in 1904 in towns and cities with a population of over 3000 in the United States.

The Beginning of Sewage Treatment

First came sewage conveyance systems, either "separate" or "combined." Not too long thereafter, it became readily apparent that in order to preserve supplies of drinking water (streams, lakes, and rivers), to protect fisheries (harbors, etc.), and to minimize public nuisances (odors, floating debris, bottom sludge, etc.), sewage had to be treated to some degree before it was discharged. The movement came slowly, but it came.