Friday, 24 March 2017

Troubleshooting Effluent Treatment: Septic Tanks

I've had another mixed week, teaching water engineering at Manchester University on Monday, then a day on site on Tuesday taking measurements of some big old septic tanks to try and work out the required desludging intervals. I've been seeing If I can make any sense of that data today.

It is an interesting site, which has increased over time to a far higher peak loading than the plant was originally designed to take, successively overlaid official and unofficial modifications, and operating and maintenance procedures passed down from operator to operator for many decades. The end result of this is that I have to work out what we have, and guess at why long-dead operators modified and operated as they did before I can figure out what was a bad idea in the first place, what has become obsolete, and what needs to be left well alone. 

Friday, 3 March 2017

More Troubleshooting Effluent Treatment Plant: Storm Water Handling: Planning Issues: Listed Monument

I have been preparing for the recommissioning of a misbehaving submerged aerated filter (SAF) plant this week. I'm just back from site, where a few tweaks were applied to the stormwater handling side of things.

Before changing anything, it is important to accurately measure what you have and I am making sure I have accurate data on flows and loads to the plant, as well as its performance in removing BOD, suspended solids and ammonia across the range of conditions it sees.

The plant is unusual for a private one in having a consent to discharge storm water by overflow from the storm tanks above a certain incoming flowrate. Today's tweaks were intended to ensure compliance with both the normal and storm discharge consents at high flows to the plant.

I have also spoken to the Environment  Agency about my plans for further changes to futureproof the plant, and have obtained agreement in principle for the recommissioning.

As the site is all Grade II listed, I will be accompanied on next week's visit by a specialist architect, to assist with producing pre-planning documentation.