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%.