This mixture is in the culvert. The Ministry of Fisheries often ask for the invert of culverts to be lined with native material and/or stone, to protect the aquatic life from the abrasiveness of the culvert material. The outlets here in Ontario Canada are generally Rip Rap material.
Specifications often require the mixing of round river stone with native materials at the invert of stormwater culverts. Does anyone have a standard ratio of mixing these items?
