RTW Engineering - Bent Tree Subdivision Project Highlight

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Bent Tree Subdivision Drainage Study and Design

Tetra Tech RTW prepared the Final Drainage Report for the Bent Tree III subdivision in northern El Paso County. This development, east of Monument, comprises more than 200 wooded acres subdivided into approximately 2 ½-acre lots. Jackson Creek, a tributary of Monument Creek, is the major drainageway for the site.

Highlights of the project are:

Hydrologic/hydraulic analysis of entire basin

Design to mitigate 100-year storm runoff

Maintained natural drainage channels

Detention storage/velocity-reducing checks for erosion control

Construction administration

The drainage report incorporated both rational and SCS methods to calculate peak flows for both historic and developed conditions. The SCS stormwater analysis included use of the TR55, TR20, and PONDPACK computer programs. Rainfall data was derived from 24-hour precipitation isopluvial maps prepared by the Soil Conservation Service.

The study also included analysis and design of a detention pond to attenuate flows resulting from development. Tetra Tech RTW sized the pond to accommodate the 100-year storm and included a two-stage release structure to operate for both the 10-year and 100-year storms. We chose to locate the pond at the farthest downstream point in the main basin to optimize capture efficiency and reduce the number of ponds required.