07-09-18 Drainage and Flooding Committee Meeting

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IML Executive Summary This report identifies existing pavement and drainage issues and recommends improvements within the airfield of the La Porte Municipal Airport at La Porte, Texas. TxDOT Aviation (Client) has programmed pavement rehabilitation for all parts of the airfield pavement (including Runways 12/30 and 5/23, as well as drainage improvements on the airport. Specifically, this report identifies pavement rehabilitation of patching, crack sealing, and seal coat surface treatment of the pavement. The existing airport classification is a "B-II", but the existing airfield geometry does not support this classification. The pavement rehabilitation does not change the pavement geometry. For this project the designs were carried out for identified improvements meeting FAA criteria for airport design and for drainage. The Taxiway Design Group was determined to be IX based on the representative aircraft listed on the ALP and observation of traffic at the airport. For drainage, the design storm period was set to a more stringent 10 year return period at the request of the City of La Porte. Data collection for drainage study and pavement surface condition assessment was accomplished by the use of aerial drones, supplemented with on -the -ground survey. With the exception of a portion of Taxiway A between Taxiway B and Taxiway Al, all the pavement within the airfield will benefit from a seal coat surface treatment. Many areas of pavement will need patches and crack seal prior to seal coat. All pavements will be re- marked as well. For drainage, there were several locations where ponding of stormwater was at levels not permitted by the FAA for pavement inundation. The drainage study identified many locations where existing culverts on the airfield were undersized and were up -sized to provide better drainage on the airfield. To accommodate limitations in the receiving system (most of the airport drains to Spencer Highway), several locations of linear detention were identified. The geometry of the linear detention system achieves volume by creating wide flat -side ditches. Due to limitation on the programmed funding of just under $2,000,000, some of the identified improvements (consisting of TWA between TW B and TW Al, seal coat topping of the aprons, and much of the linear detention) can be removed from this project and programmed into later project(s). The recommended project is estimated to total of $2,131,500.00 and includes construction and professional services for the administration of the construction. The programmed professional services appeared underfunded for a project of this size. The rehabilitation will be constructed following FAA specifications to keep with the grant assurances associated with the FAA funding on the project. There are 3 non-standard aspects of the project that may require a Modification of Standards (MOS) during design. Executive Summary) i