March 2013

Two slow sand filter design projects using bolted steel tank technology

 The photos and sketchs below show preliminary design concepts leading to installation of bolted steel slow sand filters which reduce capital cost and shorten installation times.

20 gpm concept
Concept view of a proposed 20 gpm slow sand filter for a remote site in Hawaii
the pad goes down

The filter is going in. First, a moisture barrier and  floor panels are laid on a leveled gravel base. Wall panels can be seen in the truck.

the walls go up

The walls go up, Day 2. Due to the highly acidic rain in the area, all bolts are stainless with plastic caps on the nuts outside.


The underdrain piping goes into the completed epoxy coated tank. The filter was installed start to finish in 5 days, ready for water. This saves considerably in installation cost compared to traditional steel and concrete.


concept of 100 gpm slow sand filter

What's next? a 200 gpm slow sand filter composed of two 38' tanks. this filter uses an innovative overflow wier and clear well, and new cleaning system. Filter is scheduled for completion in Oklahoma, summer 2013. Stay tuned.

Sketch-up drawings- Humphrey Blackburn, all rights reserved