Backwater and Surcharge - ADS

10. Backwater and Surcharge

Most surcharge conditions result from downstream restrictions that reduce sewer capacity.  The flow monitoring data shown here indicate that this sewer operates as expected up to a flow depth of approximately 11 inches.  However, backwater conditions are observed above this point and result in surcharge conditions.  The impact on sewer capacity is readily identified using iso-Qs, presented here as a percent of the estimated sewer capacity determined by the Lanfear-Coll Method.  This downstream restriction results in a capacity loss of 50%.