Repairing Floodwater Retarding Structure No 18A

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Is It Worth Repairing Floodwater Retarding Structure No. 18A?

Introduction

The purpose of this project is to establish a cost ratio associated with a flood retarding dam, known as floodwater retarding structure 18A, or dam 18A from hence forth, north of the City of Celina within the northwest portion of Collin County, Texas.

Dam 18A, of the Little Elm and Laterals Watershed on an unnamed westerly tributary of Little Elm Creek, is of concern due to its existing and concurrent eroding action taking place producing areas of mass wasting along portions of the earthen dam.

Dam 18A was built in 1970 by the Collin County Soil and Water Conservation District with assistance from the National Resources Conservation Service and designed for watershed protection and agricultural flood reduction with at least a 50 year lifespan. The dam is now under the sole responsibility of Collin County and specifically the Collin County Soil and Water Conservation District. Recently, because of the increased destabilization of the dam, a 24 inch diameter pipe has been installed at the lowest point of the dam to drain the pond and release the flood waters during heavy precipitation events.

With the present erosion of the dam taking place, a cost ratio needs to be established to determine of what cost Collin County would incur if the dam were to burst during a heavy saturation period creating a full basin behind the dam. Once this cost is determined in case of dam failure, does this cost exceed the money saved by allowing the slow erosion of the dam to continue and possibly fail at a later time or possibly never fail?

Questions to be Answered by Analysis

1. How much water does dam hold at maximum and how much precip...

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