Los Indios Culvert Upgrade and Channel Improvements The Los Indios subdivision and Los Indios Trail are located in northwest Austin. The Los Indios Trail roadway was overtopped by Rattan Creek during the 10-year and greater return period storm events putting seven (7) homes in the vicinity of Los Indios Trail at risk of flooding in the 100-year storm event. Using on-the-ground topographic survey, Doucet developed alternatives to mitigate the culvert and local flooding problems and prepared construction plans for the proposed improvements.

Doucet performed a hydrologic and hydraulic study of the existing storm drain network in the lower Fort Branch Oak Lawn Subdivision area bounded by Springdale, Heflin, Webberville, and Ribecke roads. This area was identified as having localized flooding problems through the Fort Branch Watershed Integrated Solutions Study. As a result, new storm drain systems were designed to supplement the existing systems. The final design encompassed approximately 5,500 LF of storm drain pipe and 2,000 LF of water main.

Over 100 linear feet of existing 36” diameter concrete wastewater line lost the cover and backfill due to scour and downcutting of Country Club Creek just upstream of Grove Boulevard. The line was downstream of the Austin Community College Riverside Campus and many apartment complexes. The exposed line was vulnerable to being deflected with opening pipe joints and wastewater spills if not stabilized. We designed a stabilized riffle downstream of the problem area to stable upstream environment for the new backfill around the exposed wastewater line. To stabilize the exposed wastewater line, an external gasket was used at each joint. The final design included normal bedding for the pipeline to the haunch, rock ballast to the top of the pipe and top it off with 12” diameter rock riprap.

Most of the Austin’s watersheds, including urban and suburban watersheds, are drained by streams that exhibit existing creek bank erosion problems and have the potential for future creek bank degradation. The concern for future creek bank failures, long term channel degradation, and their impact to creekside residents and water quality initiated the City of Austin Drainage Utility Department to authorize the city wide watershed erosion assessments in January 1997. The 17 watersheds are as follows: Barton Creek Watershed Blunn Creek Watershed Boggy Creek Watershed Bull Creek Watershed Buttermilk Creek Watershed Country Club Creek Watershed East Bouldin Creek Watershed Fort Branch of Boggy Creek Watershed Johnson Creek Watershed Little Walnut Creek Watershed Shoal Creek Watershed Tannehill Branch of Boggy Creek Watershed Waller Creek Watershed West Bouldin Creek Watershed Walnut Creek Watershed Williamson Creek Watershed

Doucet prepared “natural channel” design which incorporated floodplain creation and bioengineering to maintain bed load transport and flow conveyance in a stable channel system.

The Shoal Creek hike and bike trail experienced erosion problems in the lower reaches of Shoal Creek, often completely washing the trail out at some locations along the top of the channel banks. The project designed solutions for nine separate erosion locations along Shoal Creek in the area from 6th Street to 29th street. Nine areas were selected for improvements and were developed using varying techniques such as limestone boulders with geogrid for stability, erosion matting, permeable concrete for trails, and bioengineering were employed to manage erosion of the trails while creating a natural appearance for the channel.