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Findings: Culverts

Findings: Culverts Only three or four culverts were operating adequately in the study area. Many dozens of others were blocked by either sediment or logging debris. Stream flow subsequently had been redirected either across the road surface following ponding above the culvert, or via below ground drainage which had caused extensive piping and slumping on down slope areas (particularly in areas where the stream bed had been replaced with large volumes of unconsolidated fill). Even along road sections currently utilised for log extraction to log ponds, there are more blocked or failed culvert placements than there are successful flowing culverts.

The major reason for culvert failure was the materials utilised in their construction. The Standard Logging Agreement states:

"Logs with earth and fill shall not be used for culvert construction."
(SLA, Clause 14)

This was a common means of culvert construction and impoundments upstream of the culverts were almost ubiquitous. Poor construction techniques and inadequate allowance for water and sediment flows have permitted the sediment and logging debris carried in the waterway diverted through the culvert to completely block flow under the road. The environmental consequences of this impeded flow is obvious. Blocked culverts defeat the very purpose for which they were constructed under the roads throughout all logging areas.