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It is worth noting that given the uncontrolled nature of the service spillway at the <br />Havana Street dam, the total volume released by the dam failure is only slightly <br />greater than the volume which would have been released had the dam not failed. This <br />slight increase in volume of water released corresponds to the portion of the dead <br />storage in the reservoir which was escaped when the breach of the spillway progressed <br />to an elevation lower than the service spillway control elevation. This dead storage <br />was estimated to be approximately 70 acre feet based on contour mapping available in <br />the C -1991 planset. <br />8.0 Conclusions <br />The September 2013 flood event did not exceed the capacity of the spillway at Havana <br />Street, but clearly, the erosion protection in the spillway channel for the Havana Street Dam <br />was insufficient to safely convey the spillway flow it experienced during the event. <br />The damage from the failure of the Havana Street Dam did not result in any significant <br />downstream damage, and was therefore properly classified as a low - hazard dam. Some <br />damage was caused to the Havana Street road embankment, but given the low volume of <br />traffic of the road and the fact that it was still passable, this damage is considered `low,' <br />validating the hazard classification of the Havana Street Dam. It appears that the 24 -hour <br />precipitation event experienced in September 2013 exceeded the event probability the <br />spillway at a low - hazard dam is required to convey by the Colorado Rules and Regulations for <br />Dam Construction and Dam Safety (Small, Low Hazard dams are required to safely pass the <br />100 -year 24 -hour event). <br />The actions at the dam during the event to evacuate people downstream of the dam were <br />appropriate given the potential for the railroad embankment to fail.