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Work Order 8110

In conjunction with Ron Morrison, P.E., TCFM, the Wallace Group conducted a floodplain study of Upper Waco Creek to evaluate drainage improvement alternatives necessary to alleviate flooding conditions for a proposed Target Greatland site. Originally, this site had been the home of Lake Air Mall which had experienced flooding on several occasions. The scope of work included:

Prepare field-surveyed cross-sections of Upper Waco Creek
Model the extensive underground multiple box culvert system
Establish the “existing conditions” 100-year floodplain
Evaluate various drainage improvement alternatives for the new Target site
Recommend a drainage solution where the Target Building would be 1-ft. above the 100-year floodplain while not increasing the depth of the floodplain upstream, or downstream.
Model the 100-year floodplain including the proposed drainage/site improvements for Target as well as a new development (Lake Air Court) located immediately downstream from Target.

The Wallace Group utilized a hydrologic model from a previous study that Ron Morrison had prepared for a development downstream of the Target site. A HEC-RAS model was then prepared for Upper Waco Creek to determine the 100-year water surface profile. Various alternatives were analyzed before the recommended solution was finalized. The recommended solution included overland conveyance improvements coupled with an underground, multiple box culvert system. Target’s engineers were able to incorporate this solution into their development plans.