07-09-18 Drainage and Flooding Committee Meeting

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IML Seal coat surface treatment is to follow the FAA specification item P-631: Refined Coal Tar Emulsion with Additives, Slurry Seal Surface Treatment. Knowing that Harris County is in the EPA nonattainment district "Moderate" classification for 8-hour ground level ozone concerns, we have investigated any issue that may interfere with the use of a coal -tar emulsion in the rehabilitation. Research into Texas Commission on Environmental Quality rules under 30TAC115 does not indicate there is any limitation on the use of a coal -tar emulsion product in Harris County. There are neither local nor statewide limitations on the use of this material. Therefore, the statewide success of this material as a seal coat warrants the use of the product in this project. For asphalt patching of the pavement, the anticipated material specification for the asphalt is P-403, using the TxDOT state highways specifications for asphalt, with a "bumped" performance grade to accommodate for aircraft tire pressures. The current standard for FAA asphalts limits the P-403 asphalt to use on pavements serving aircraft weights of 12,500 lbs. or less. The pavement is currently rated for much heavier aircraft. The layout depicting the limits of the pavement rehabilitation are included in Exhibit 9. Runway 12130 Given that the pavement within the limits of Runway 12/30 and the connecting taxiways to the holdlines are good, the pavement is determined to need some patch repairs over the alligator -type crack areas and crack sealing of those block cracks identified. After proper curing of the patches, the entire length and width of the runway is to receive a seal coat in accordance with the specifications for item P-631 For the striping, the existing pavement markings on the runway must be removed — especially in those areas where old markings have been blacked out. The rehabilitation will include requirements to remove the paint markings prior to the pavement seal coating. This will also allow for best adhesion of the seal coat to the pavement. After the installation of the seal coat and curing time, the markings will be replaced. Recent updates to the pavement marking standards14 will have some minor changes to bring the markings to the current standard. One of the tenants on the airport asked if changing the striping of the displaced thresholds could allow for a longer takeoff declared distance. The existing markings on the displacements are not configured as a taxiway aligned with the runway (which would affect declared distances), so it is not clear there are ways to report declared distances that would be different than the runway length. Further investigation is beyond the scope of this report. While it does not appear that declared distances exist for either runway, it may be worth investigating the possibility of this use. The rehabilitation of the pavement should also include re -dressing the pavement edges. This will be accomplished by the stripping of the turf and topsoil at the 14 FAA AC 150/5340-1 L, Standards for Airport Markings, 4/14/2014. Page 122