Managing a sewage pump station can be a smelly business. The million dollar question is always, "How can we prevent blockages"?
The stock answer to questions like this is normally, 'it depends'. We don't find that kind of answer too useful, so we've addressed the issue head on with this post. Here's 5 tips to help you cut out blockages on your sewage pumps, saving you money on replacement pumps and preventing the mess, smell and inconvenience that follows a bad pump blockage.
1. Consider the sewage pump impeller type
In a previous post we looked at the main types of impellers for submersible pumps, and the effect they have on a pump's performance. A good starting point is to consider whether the pump impeller type you have at the moment is the best specification for your application, or whether there's a better option out there. If you do decide to change the impeller it will often mean the entire pump has to be replaced, so it really is much better to specify the impeller carefully in the first place. Obviously if your pump is already installed you don't have the luxury of correcting the original specification, so unless it's causing serious issues maybe it's just something to bear in mind for when the pump needs replacing.
2. Educate users about what to put down the drain
We affectionately refer to people who create the sewage as 'users'. These people need to be aware of what they can and can't flush away down the drain. Pumps will clog on a number of commonly flushed away items - 'flushable' wipes are a big one. If the pump station is serving public toilets, or an area frequented by many different users, putting signs up in the toilet areas warning users that irresponsible disposal could damage the pumps is a good way to combat this. Also make sure there are sanitary disposal units for non-flushable items. Mains drainage is a lot more forgiving than pumps so users who aren't used to sewage being handled by a pump station may not be aware of the problems. Even on mains drainage, for that matter, the water authorities end up dealing with the issue further down the line. Here's just a couple of the recent articles about the problem:
3. Remove the floating solids in the pump station
The usual layout of a pump station is to have one or two submersible pumps sitting at the bottom of the pit. When the pit fills to a predetermined height the pump starts up and sucks the wastewater out, bringing the level back down to the top of the pump - usually no lower, as the motor relies on being surrounded by water to stay cool. Problems can be caused by floating solids, as instead of being sucked away they just move up and down on the surface with each cycle of the pumps. Eventually they can form a thick mass, potentially one day sinking down and getting sucked into the pumps, blocking them fast. They can also tangle float switches. Use a vacuum tanker lorry to jet down and suck out the pump station every so often to prevent this issue. We don't have tankers ourselves, but can arrange this for you with one of our approved tanker operators if required.
4. Ensure correct duty/standby changeover
As mentioned on point 5 of our post on increasing the life of a pump, it's important to make sure any system with two or more pumps working together should be configured to take turns at being the duty pump. This also helps to prevent blocking as well, because if a pump is left without running for a long period of time then solids will collect around it. These solids are sucked into the pump when it eventually does start up, and can cause a blockage.
5. Service the sewage pumps regularly
Last but not least, make sure you have a service schedule in place for the pumps. Part of a service should include removing the pumps and cleaning the impeller from anything that's started to collect on it. Our engineers will also look out for any of the above problems starting to happen, giving advance notice of issues that could occur in the future. OK, so we were going to say that servicing pumps is important because that's what we do, but if it wasn't important we wouldn't be doing it anyway!
Hopefully this post will have given you some ideas to get started with. It goes without saying that none of these are any guarantee that your pump station won't block, and they're only the main reasons we come across - there's probably lots of other reasons that sewage pumps get blocked. If you know of any, be free to comment below so that you and all our blog followers can benefit from it!
Warning - don't scroll down further to view the last image if you're squeamish!
This is what to avoid...