Powell River Project

Septic Alternatives

Peat Filter

The photos below show a community sewage treatment project that uses Pura-Flo peat filters manufactured by an Irish firm, Bord-na-Mona. Pura-Flow peat filters are approved for use in Virginia.

This was a community project serving 20 homes.  The cost of $6,000  per home includes new 1000 gallon septic tanks for each home. Cost was kept down by the labor of community members, who applied "sweat equity" to construct the piping that collects septic effluent from each home and brings it to the central treatment location.

Each septic tank contains a chamber with a pump that pumps sewage effluent through a piping system to the Pura-Flo units. Because septic effluent, not raw sewage, is being pumped, pipes may be used that are smaller than what would be used in a typical sewage system. This arrangement is known as a "STEP" system (Septic Tank Effluent Pumping).

The STEP effluent is delivered to large subsurface tanks that provide storage and recirculation. A 50 percent recirculation ratio is used in this project (which means that each volume of effluent is circulated through the peat filtration system twice, on average), although the peat filtration system can be used without recirculation. The 50 percent recirculation provides an extra factor of safety to ensure adequate treatment in this high water-table area.

Above are the Pura-Flo units. Each unit is approximately 7' x 4' x 30" in size, and contains built-in piping as well as the peat filter.  Four banks of 10 units each were set up to treat septage from 20 homes. A typical Pura-Flo installation in Virginia will use one unit per bedroom.
 
 

Above are two more banks of Pura-Flo units. The banks were installed on top of a gravel bed, which was placed on top of the existing soil. The soil fill placed over the gravel bed and surrounding the Pura-Flo units has not yet been graded smooth or revegetated. Effluent from the peat filters enters the gravel bed and is dispersed over the underlying natural soil. This type of arrangement allows for cost-effective effluent dispersal despite the high water table conditions that prevent use of conventional septic drainfields on this site.
 
 

Above and below are close-up views of the Pura-Flo units. The built-in piping that distributes wastewater is visible through the peat. The peat itself is very coarse textured, much more coarse than peat products that can be purchased in retail stores for landscaping and other purposes. The manufacturer states that the coarse-textured peat is able to retain permeability and its capability to treat septic wastewaters effectively for more than 10 years without replacement. The peat's acidic nature is an asset to its capability to reduce wastewater pathogens. The Pura-Flo units' lids can be closed and secured with the built-in metal fasteners that are visible in the photo above.
 
 


 


This page created and maintained by Carl Z
26 October 01
czip@vt.edu