Water Filters

One of our jobs last year was to help Craig, the maintenance guy, replace the filter screens in the water treatment plant.

This steel box covers one of the water filter units.  There are 3 units in the plant, with two running and one "back-up".

The Green Lake National Fish Hatchery gets its water from, you guessed it, Green Lake.  The first stage of treatment is some large grates and screens that remove fish, leaves, branches, etc. 

The second stage of treatment is under the steel covers, and consists of a rotating rack of 36 very fine fabric screens. Here the screens are being rotated while we look for torn screens that need replacing. You tell the newest screens (white) from the oldest (dark brown).  The water here has a lot of tannin in it, and with time the fabric screens get stained. 

Screens that need replacing are pulled out and taken to the maintenance shop.

Replacing the fabric is a great rainy day project or if we only have an hour or so we can start taking off the old fabric.  We've already worked on several screens this year.

Frame without fabric.

The fabric comes from Switzerland and is very expensive.  Mark has to burn holes with a soldering iron in order to get the screws through to attach the fabric to the frames. Each fabric screen panel has 38 sets of bolts, washers, lock washers and nuts holding it to the frame. That is a lot of hardware!

New screen ready to go!

Old screen/new screen comparison.

New screens are then placed on the rotating drums.

You can certainly tell the new from the old!

  

We like to keep a stockpile of finished screens.

This is a fun project. 

Next year all of this will be obsolete with a new system that does away with the fabric screens.