Agenda Date: 09/17/2019
Subject:
Title
Resolution 46-2019: Approving an Intergovernmental Agreement with Mile High Flood District to study Jackass Gulch and update the drainage master plan and floodplain delineation
Body
Prepared by:
Carolyn Roan, Water Resource Manager
PURPOSE:
Staff requests approval of an Intergovernmental Agreement (IGA) with Mile High Flood District to study the hydrology and floodplain of Jackass Gulch in consideration of new rainfall data and development that has occurred in the basin since the original study in 1990. The hydrology will be studied in conjunction with the floodplain and necessary drainage improvements to address erosion and flooding concerns.
PRESENTATIONS:
Staff Presenter(s): None
Additional Presenter(s): None
SUMMARY:
Jackass Gulch was studied in 1990, as part of the Urban Drainage and Flood Control District (now called Mile High Flood District) Flood Hazard Area Delineation of Lower Dad Clark Gulch and DFA 0068, and later Outfall Systems Planning study of the same name in 1991.
Jackass Gulch is actively eroding, and in some places has created hazardous conditions with tall collapsing stream banks exceeding 10 feet in height. While largely on private property, this drainage channel parallels the public Mineral Avenue Trail. The sediment lost due to this erosion has been depositing in the South Platte River, threatening fish habitat. A channel stabilization project on one reach of the gulch was completed in 2018.
In addition, the current floodplain delineation shows significant flood risk to the Mineral Avenue and Santa Fe Drive intersection, which has seen a substantial increase in traffic. There is future development proposed at the southwest corner of the intersection.
Since the original studies, residential development has encroached into the drainage basin. These development activities have affected the land available to implement the 1990 flood mitigation recommendations. Hydrology change...
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