Implementation of two new treatment facilities; dry ponds and sedimentation screen basins & revised coefficients for calculated reduction efficiency of the facilities biofilters, macadam ditches, swales and ditches

Dry ponds (ponds without permanent pool, with bottom outlet and dry between rain events) have been added as a new treatment facility in the biofilter box. Before, dry pond could only be designed for flow detention in the box Flow detention facility, or be designed as e.g. swales in the biofilter box. Now they can be designed for both treatment ad flow detention in the biofilter box.

Sedimentation basins (screens in ponds/wetlands or in the recipient water body) can now be designed in the wet pond box.
Descriptions appear in this box and in the box Reduction efficiency.
It is important to consider the lengt:width relation and that no extra effect for flow detention should be accounted for when calculating the reduction efficiency for screens in recipients, but else the design is the same as for wet ponds and wetlands.

Revised coefficients for calculated reduction efficiency of the following facilities and substances have been made after comparative studies of the data, and since more data have been added to the data base:

Biofilters: Pb, Cd, Cr, Ni, oil, PCP.

Macadam ditches: SS.

Swales: P, N, Pb, Cu, COD.

Ditches: P, Cu, Zn, Ni, SS, BOD.

This means that the calculated reduction efficiencies will be changed for the above facilities and substances for projects started after this release date.