07-09-18 Drainage and Flooding Committee Meeting

Browse Search

IML The existing conditions 5-year XPSWMM model results indicate taxiway encroachment at the north ends of Taxiways A and B. The existing 10-year event XPSWMM model results indicate that ponding would occur on the taxiways adjacent to the northern portions of Runways 5/23 and 12/30 The 10-year model also indicates that there would be ponding on the service road that connects the southwest corner of the airport site to Runway 5/23. The existing 100-year event XPSWMM model results indicate that there would be significant ponding on the northern portions of Runways 5/23 and 12/30, as well as on the adjacent taxiways. There is slight encroachment on the southern portions of the taxiway along Runway 12/30 as well. The 100-year model also indicates that there would be significant ponding on the service road that connects the southwest corner of the airport site to Runway 5/23. The storm sewer system in Spencer Highway is also overwhelmed during the 100-year event, leading to ponding in the road. But the ponding on the street is as expected for the extreme events. During 10 and 100-year storm events the culverts and ditches along the western edge of the airport site overtop and spill onto Farrington Drive and the nearby neighborhood to the west. There is ponding in the northeast corner of the airport that likely flows into the bordering neighborhood system along North Avenue H. Exhibit 6 presents the ponding during the 5-year storm event for the existing conditions. Exhibit 7 presents the ponding during the 10-year storm event for the existing conditions. Exhibit 8 presents the ponding during the 100-year storm event for the existing conditions. 4. Rehabilitation Design 4.1. PAVEMENT REHABILITATION The tabulation of block cracking from the pavement surface analysis was used to quantify the amount of crack seal and repairs needed for the rehabilitation of the pavement. Crack seal material is commonly available, and is specified by the FAA under specification item P- 605. For those areas that need repairs due to alligator -type cracking, the anticipated size of the repair equipment determined the width of the repair. It is expected that a six-foot paving lane width is the minimum to achieve a well -compacted, quality finish. This means that a six- foot repair width was set even though the area of alligator cracking may have been much less. Additionally, the length of the repair was extended 10 feet beyond the observed limit of the cracking. This was to account for additional soft pavement at the limits of the cracking. Our experience has shown that providing additional length beyond the damage allows for proper tying of the repair to existing pavement. Therefore, the quantities of repairs for alligator cracking are far larger than the area counted and discussed in the existing conditions sections for the pavement. Page 121