Updates
August 2007 – Apron Construction
As you can tell, construction of the apron east of the new terminal is progressing well. Building the apron is much more complex than it first seems. First of all, the decision must be made as to whether the construction will be in concrete or asphalt. In areas where airplanes and tractors park concrete is generally used. The thickness of the concrete differs depending on the type of plane. For those places where the planes drive, asphalt is generally used. Its lifespan is shorter than that of concrete, but the initial cost is significantly less.
A crucial aspect during apron design is the final slope. It must ensure that the rain runs into the catch basins. Water build-up on the aprons could cause problems during a heavy rainfall or the spring thaw. However, the guidelines that apply to aprons do not allow slopes greater than one degree on the plane’s longitudinal axis and no more than half a degree on the transverse axis. Therefore, these constraints determine the location of the catch basins. Under the ground, there is also the requirement that, in the event of a fuel leak, the fuel is caught before the rainwater is discharged off the airport site. For this purpose, an oil separator is installed below ground.
Apron construction also receives special attention. In Ottawa, we are spoiled because the native soil is nearly all sand and is therefore easy to move, compact and pile. Once the native soil is shaped into the required slopes, several layers of different-sized aggregates (stones) must be added. These aggregates are dampened and then compacted with road rollers to prevent all movement once the surface is finished. Laying the asphalt is relatively simple. For the concrete, a machine is used that pours it in strips. Once the pouring starts, it doesn’t stop until the whole strip is poured. It is crucial for everything to be level. During the pouring, concrete samples are set aside in order to check its composition and hardening. The pouring is usually done in the evening or at night when the temperature is cooler, to prevent the concrete from hardening too quickly, which could cause cracks to form. The concrete takes about a month to harden enough for planes to drive on it. In the critical areas, the hardening can be sped up by adding hardening agents. However, since we have time, we will let nature do the work.
In 2007, the east apron will be built and next year the contractor will return to complete the west portion. We expect to have the entire project completed before winter, 2008.