On or about Thursday June 17th a debris torrent ran down the western slopes of Koch Face in SFP's T.F.L. #3. This debris torrent started approximately 550 metres below a clear-cut located at the top of Koch Face at an elevation of 1795 metres. This clearcut was logged pre Forest Practices Code in 1994. The road accessing this cutblock from Berry Creek entered the clear-cut and traversed across the bottom third of this cutblock. A landing was located approximately in the middle of the cutblock along this road. As the road approached this landing it dropped on a grade of approximately 8%. There was a 300 metre length of this road with no water bars, cross ditches, ditch blocks, or any other culverts. As a result the intercepted runoff from a 300 metre section of this clear-cut was concentrated into a single culvert at the entrance to the landing. Not only was this water concentrated in a single culvert but also a stream was diverted from its natural channel because of improper culverting and directed to the same culvert. This culvert emptied its contents into the clear-cut on open slopes. Approximately one-third of the water made its way back into the gully below the ephemeral stream. The remainder of the water randomly ran down the slope from the landing for a distance of approximately 700 metres to the slide scarp, a drop of 135 metres in elevation. As a result the water delivered to the slide slope was far beyond what would naturally have been there. These facts suggest that failure of this road design to dissipate the surface runoff and a lack of a culvert to maintain the natural drainage of the ephemeral stream were the major contributors to this debris torrent. The scarp of the debris torrent broke off to a depth of 3 metres by 15 metres wide and ran for 2 km, dropping 1000 metres in elevation. It scoured out a small creek channel, destroyed hundreds of trees, damaged Slocan Forest Product's logging road in two places and washed out the Koch Creek Forest Service Road in the valley bottom.

"We followed the running water to its point of discharge from a culvert, the road crosses a shallow but obvious gully, where a culvert should have been installed. Some water from the culvert found its way left, back into the gully but most of it flowed over the ground surface to where the landslide started. The next culvert is located 313m east. In between the two culverts is a half-waterbar which is ineffective. The ditch intercepted a considerable volume of water, mostly subsurface, from the road cut at the gully, and also some water from several skid trails and the road cut further east, and discharged the water through the offending culvert. Between the culverts the road has an adverse slope of about 8 %. The ground slope in the area averages about 30%.

The primary cause of the slide is clearly the poorly placed culvert, and failure to install cross ditches after logging. Other contributing factors may have been concentration of runoff by the skid trails in the cutblock above the road, and enhanced snowmelt in the clearcut. As the clearcut is on or very close to the ridge top, the ECA of the area above the offending segment of road is about 75%."