Allandale Storm Drain Improvements

This project will reduce flooding of houses, yards and streets caused by an old, inadequate stormwater conveyance system in the Allandale neighborhood without making flooding worse for residents living along Shoal Creek. The project is partially funded by the November 2006 Bond Election.

The original plan called for a stormwater detention pond at the site of a commercial storage facility located on Burnet Road and the installation of underground pipes in the neighborhood. However, the City has decided not to pursue this option due to the high cost of purchasing the land. Instead the City is considering other, more cost-effective options. The City is working closely with the Allandale Neighborhood Association during this process and is currently evaluating the possibility of installing a storm drain underneath Bull Creek Road.

Tuesday, January 8, 2008

COA Meeting 12/6/07

The Drainage Committee met with the City of Austin on 12/6/7 for an update on phase one of the drainage project. Phase one will add an additional covered drainage pipe under White Rock between Woodview Avenue and Shoal Creek. Subsequent phases will make improvements upstream.

After receiving feedback at the ANA meeting in the Fall and reviewing their flow rate calculations, the City paused the project in order to perform additional analysis. There was a significant difference between the capacity of the original design and the calculated flow rates for 25 and 100 flood events. The City is looking at ways to increase the water captured on White Rock and the impact of capturing additional water on the total watershed.

The City has hired an outside consulting firm to determine the maximum amount of water that can be diverted without causing problems where the water will enter Shoal Creek at White Rock.

With this information, they will determine the maximum size of the new drainage pipe to be put under White Rock. The City noted that the size of the pipe may be further constrained by existing utilities currently under the road.

The City also gave us an update on the storage facility behind White Horse Trail, Nasco and Twin Oaks. It is still cost prohibitive for them to convert part of this facility into a retention pond, and they have reviewed historical planning applications to ensure that the current site complies with these plans. John Panak (ANA) identified an apparent discrepancy to the plans, and although it is fairly minor the City said that they would follow-up with the storage facility.

The Drainage Committee expects to meet with the City of Austin again sometime on February after this analysis has been completed. The updated schedule for phase one of the project is to complete the design by the end of May, and then have a five month bid process.

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