Sediment concentration and turbidity changes during culvert removals
Foltz, R.B.; Yanosek, Y.A.; Brown, T.M. 2008.
Sediment concentration and turbidity changes during culvert removals.
Journal of Environmental Management 87(3):329-340. May 2008.
Keywords: Soil erosion; Road obliteration; Sediment; Stream water quality; Culvert removal; sediment concentration
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The concentrations of sediment and turbidity in stream water were monitored during culvert removals to determine the short term
effects of road obliteration. Sediment concentration was measured at 11 stream crossings among two locations in Idaho and one in
Washington. Sediment concentration immediately below the culvert outlet exceeded levels above the culvert outlet by at least three orders
of magnitude at all stream crossings. Sediment yields ranged from 170 to less than 1 kg in the 24-h period following culvert removal.
Turbidity exceeded the regulatory limits during culvert removal at all locations monitored in this study and remained above the limits
beyond the monitoring periods of 24 h at four of the locations. Sediment concentrations 100m downstream of the culvert outlet were
reduced by an order of magnitude, but did not change the turbidity values sufficiently to meet regulatory limits. Sediment concentrations
an average of 810m downstream of the culvert outlet were similar to sediment concentrations above the culvert for the entire excavation
period and turbidity regulations were met. Mitigation consisting of two straw bales placed in the stream caused a significant reduction in
sediment yield from an average of 67 kg to an average of 1.6 kg.
Moscow FSL publication no. 2008i