Environmental Engineering Reference
In-Depth Information
McDonald, Stone and Ingles (1981) describe how turbidity in Ben Boyd Dam, Eden
NSW, was controlled by adding 1% by weight of gypsum of the soil depth in the reservoir
area (27 tonnes per hectare). Gypsum was mixed in to 150 mm depth by disc harrow and
compacted with a sheep's foot roller and gave initially clear water, but flood rains washed
soil from the catchment and led to turbidity. The storage water was subsequently floccu-
lated and clarified by adding 40 mg/l of alum (Al
2
(SO
4
)
3
) and 20 mg/litre NaOH.
