Most agencies think about cleaning because of debris in the line. If we have an effective cleaning program there should not be a lot of debris in the line after the line is cleaned and tv d for acceptance. If we have a problem with getting a lot of debris in the lines we need to look at where it is coming from and why.
What is H2S and why should it affect our cleaning cycle? Hydrogen Sulfide It is formed when the slime layer in the pipe builds up. It is also formed in bellies, wet wells, and other places where wastewater sits. It is dangerous to the people who work around sewer systems. It is very detrimental to concrete pipe and concrete structures as well as most metals
What is H2S and why should it affect our cleaning cycle? As the sewer becomes anaerobic It gives off the smell of H2S which is somewhat like rotten eggs. What is the difference between Fresh Wastewater and Septic Wastewater? The answer is Oxygen. When people say that it smells like sewer, they are smelling the H2S. FRESH waste water does not have an odor How long it takes to create a problem with H2S depends on: PH The lower the PH, the higher the H2S generation Temperature - The higher the temperature, the higher the H2S generation. Oxygen the lower the oxygen, the higher the H2S generation
Smoke Testing to Find Odors Any place the odors will go, smoke will also go. We had a brand new school that they had to close because of sewer odors. We did a smoke test on the school and found that no one had filled the p- traps in the floor with water after the school was completed. The best way to find odors that people are complaining about is to do a smoke test in that area.
What causes blow back? Vents are clogged There is a belly in the service line There is a belly in the main line.
All of these reasons for blow back can be detected by a smoke test. Place door hangers in the area you are going to smoke test saying: IN PREPARATION FOR COLLECTION SYSTEM LINE CLEANING DURING THE WEEK OF WE WILL BE DOING A SMOKE TEST ON. THIS IS ACCOMPLISHED BY INDUCING A NON TOXIC SMOKE INTO THE SYSTEM AND OBSERVING WHERE THE SMOKE COMES OUT. WE WILL HAVE TEAMS NOTING WHERE THE SMOKE COMES OUT. WE EXPECT IT TO COME FROM THE VENTS ON YOUR HOUSE OR BUSINESS AND IF YOU OBSERVE SMOKE COMING INSIDE YOUR BUILDING PLEASE CALL TO REPORT IT. WE WILL SEND SOMEONE TO INVESTIGATE. THANK YOU FOR YOUR COOPERATION. IF YOU HAVE QUESTIONS, PLEASE CALL.
Send teams of observers to look for the following: No smoke coming from vents. This indicates the vent is blocked or there is a blockage in the service This requires another door hanger, preferably colored Red, that reads: IN A RECENT SMOKE TEST, IT WAS OBSERVED THAT YOUR VENT OR VENTS DID NOT EMIT SMOKE. THIS INDICATES YOUR VENT IS BLOCKED AND WILL CREATE BLOW BACK WHEN WE ARE CLEANING PAST YOUR BUILDING. WE WILL BE DOING THAT CLEANING ON. PLEASE CLOSE YOUR TOILET LID AND PLACE SOMETHING ON IT THAT WEIGHS AT LEAST FIVE POUNDS. IF YOU HAVE ANY QUESTIONS, PLEASE CALL. WE APPRECIATE YOUR COOPERATION
No smoke coming from the manhole. This is an indictor that the main line is blocked. This requires a CCTV of this line and a check of the condition of the main line. Do not attempt to clean this line until it is known what is happening in the line. After CCTV, a plan for cleaning this line can be formulated
Watch also FOR smoke coming from places it should not be coming from. ú Broken cleanouts ú Broken Service lines ú Smoke on the inside of buildings ú Storm drains in the area
Different methods of smoke testing Smoke Bombs ú Convenient You have a blower and a cage. You set the blower on the manhole and the smoke bomb in the cage and go about your testing. ú Inconvenient You run out of smoke during your test according to the size of smoke bomb you used. This sometimes triggers errors due to everyone hurrying to get the observation completed before the smoke bomb runs out.
Liquid Smoke ú Convenient You have a blower and a tank with liquid smoke. Put the blower on the manhole and pressurize the liquid smoke tank. You don t run out of smoke ú Inconvenient You need to have someone at that manhole all the time you are smoke testing to make sure the tank stays pressurized.
You can block the lines above and below where you are smoke testing or you can allow the smoke to go where it will normally go. If you block the lines you run the risk of backing up a service line or filling a main giving you a false smoke test reading. If you don t block the lines your smoke may go outside your area of influence. Make sure you notify everyone that may be affected! Normally, upstream from the smoke tester three to four line segments and downstream four to six line segments, depending on the effluent flow and the air flow.
Be sure to notify police and fire before doing any smoke testing. Smoke testing only needs to be done once every five years if good records are kept.
Wayne Sewer Ball The cleaning is accomplished by hydraulic action through the ribs around the ball. This requires filling up the upstream manhole with water to create the pressure that will cause the hydraulic action. When houses are connected to the sewer line, it creates the hazard of filling somebody s basement or bathroom with water as you fill the manhole.
Sewer Scooter Basically the cleaning is accomplished by hydraulic action like the sewer ball, except the plate on the sewer scooter is raised and lowered by a rope connected to the plate going back to the upstream manhole. The same hazard exists as with the sewer ball, of filling someone s basement or bathroom as you fill the manhole.
Prior to the Wayne sewer ball or the sewer scooter, people built flush manholes at the head of the sewer line. They even ran a fresh water line into the manhole with a valve on it. When the manhole was filled to a certain point, the water was released to run down the line, thinking there was enough hydraulic action to clean the line. They also used water trucks or a hose from a fire hydrant It was found that the hydraulic action only existed for about ten feet, and then the water ran over the debris in the line, with no cleaning action beyond the first few feet. It was determined the hydraulic action had to be within about two feet of whatever was creating the hydraulic action.
Hydro Cleaner a high pressure pump is mounted on a truck and forces water down a hose to a nozzle in the line. The nozzle is drawn through the line so the hydraulic action is just in front of the nozzle which makes this method much more effective in moving material in the line. Hydro Vac The hydro-vac cleans the same way that the hydro cleaner does, but has a heavy duty vacuum mounted on the truck to remove the debris at the manhole. Both the hydro cleaner and hydro-vac depend on a tank full of water on the truck, which means they have to be filled by another water truck or pull the hose and go refill at a fire hydrant.
What is in the future? If a way can be found to clean lines using compressed air instead of hydraulic action, the trucks wouldn t need water refills or use potable water. An air compressor mounted on the truck would create the pressure. This is much easier said than done.
This item can make or break a $350,000 Hydro-vac ú Pressure & Volume Most of the hydro-vacs or combination trucks as some call them, are rated at 2,000 PSI at 60 to 80 GPM. This is a very good combination. It can scour the pipe or move material down the line. During the drought years in California they tried to use less water and more pressure. Those trucks used various pressure and various GPM and some are still in use. They centered around 3,000 PSI at 30 GPM. This combination is not as effective at 2,000 PSI at 60 to 80 GPM. Make sure your nozzles match the pressure and volume of your truck. NEVER TURN YOUR PRESSURE DOWN!
Angles Each nozzle is built to accomplish something special. ú 12 to 15 degree nozzles are used to move debris down the line. It has an effective hydraulic action for twenty feet behind the nozzle pulling rocks and sand down the line toward the manhole where you are. The nozzle needs to be set in the bottom of the pipe. It will not scour the top portion of the line. ú 30 to 35 degree nozzles are used to scour the top of the pipe to take off the slime layer. The nozzle needs to be on skids so it will sit in the center of the pipe. ú Combination 15 to 35 degree nozzles are supposed to do both but there is not usually enough volume going either direction to accomplish its given task.
15 degree 20 degree 30 degree
Specialty Nozzles Spinning nozzles for root control Chain flails do an excellent job on roots but if out of adjustment and the chain hits VCP or concrete or PVC it can cause damage to the pipe. Cable flails do not do as much damage to the pipe but the do an excellent job on the roots. Most of these types of nozzles require grease or they need to be kept in oil. They also require skids built to keep them in the center of the pipe. Nozzles for penetrating These usually have enough rear jets to push themselves and the hose down the line and jam it into whatever is blocking the line and then the jets on the front of the nozzle blows the debris apart.
Nozzles for penetrating These usually have enough rear jets to push themselves and the hose down the line and jam it into whatever is blocking the line and then the jets on the front of the nozzle blows the debris apart.
Nozzles for cleaning large diameter lines ú All Lines are designed to flow at 2fps Why? To scour the lines The only part of the line that gets scoured is where the flow is touching the pipe. This sounds good but lines are designed to run at 2fps when they are 50 to 70% full. When they are new and are not running at 50% full, they are not running at 2fps and the solids settle to the bottom of the pipe. They need a heavy nozzle to move along the bottom with jets at 12 to 15 degrees to stir up the solids and keep them moving down the line before they turn septic.
Know the Dynamics of your system. What is the actual velocity in your lines? What is your average effluent temperature? Where do your pressure lines come in? ú What is the retention time in your wet wells and pressure lines? What material is your line?
ú Are there inside or outside drops? ú Are there overcharged lines and why? ú Are there lines with bellies larger than ½? ú Where is your effluent generated? ú Do you have odor complaints in the fall? Never go over two years between cleaning. ú You will find backups before they happen. ú You will keep the H2S down.