Construction and Installation of the Structure

Several posts back we determined how much PSM (treated slag in this case) was required to meet our P removal goals at this site, and we also determined how to orient that slag (i.e. area and depth) at our site to be able to treat all the runoff from a 2 yr-24hr storm event. 

Now it is time to build the structure.   In this case we are going with the low-tech, standard box structure where water flows through the PSM from the top-downward into subsurface drainage pipes.  With one small twist however: the drainage pipes at the bottom of the structure will not protrude through. 

We also designed our structure to be easily cleaned out with a front-end loader or a skid-steer. 

Below is the 33 x 13 ft structure from the perspective of downstream (drainage) side looking up to the upstream (entrance).  This was built in a modular form so that we can take it out into the field in pieces and assemble on-site.  Note the expanded metal on the drainage side.  The buried perforated pipes will drain to the expanded metal, where the treated water can then exit the structure.  This downstream side of the structure was designed as a “gate” to be removed when the PSMs become saturated with P.  At that point, the gate can be unbolted and easily removed, providing access for a skid-steer to drive in and scoop up material.

 Below is a picture of the “upstream” side where the runoff water will enter into the structure.  There will be perforated pipes connected to the metal pipes that will serve as an “entrance manifold” in order to evenly distribute the runoff water over the top of the PSM.

Here is most of the structure in pieces as we take it to the shop for painting:

Getting the primer on:

Then the paint:

 These students are talented!

Heavy, but not so heavy that we could not lift them by hand. Shown in the picture is Stuart Wilson – technician, Alexandre Ricardo Alves (i.e. The Shark) – Brazilian student intern, and Josh Daniel – graduate student.

Putting the pieces into our previously made “footprint”.  Note the adviser is actually working the shovel.

It was wet that day:

Completely put together: Note the earthen berms meet at the entrance to the structure:

Total cost for the metal materials and for a private fabrication shop to custom construct to our specification: $2,500.  Powerhouse, in Stillwater, OK.  405-377-6396. They did an excellent job.