| Note: Modeled using (a) the current run-up areas; (b) the Z1 run-up areas; and (c) the Z2 run-up areas.
modeled three-month average Pb concentration across the PAO airport footprint. The counterfactual of no run-up emissions was also modeled to illustrate this feature, resulting in maximum modeled concentration of 113 ng/m3, which is only 8 ng/m3 (7%) less than the original maximum concentration.
When the run-up emissions were moved 50 meters to the southwest of the original run-up area, the maximum three-month average concentration decreased to 114 ng/m3, a reduction of only 6%. Moving the run-up emissions to Z2, 100 meters away from the original location, further reduced the maximum three-month average concentration to 113Â ng/m3, which is only a 7% reduction. The run-up area had less of an impact on the location with maximum modeled impacts at PAO than at RVS or SMO because the average run-up TIM was shorter in duration than both RVS and SMO (for both total run-up time and magneto test time) and its impacts are generally to the south of the location of maximum concentration, as shown in Figure 15. It is important to note that moving the run-up areas also moves the location of some taxiing and idling emissions, so there are additional, but small, reductions in impacts from taxiing at the location with maximum modeled concentration.
Conclusions Regarding the Movement of Run-up Areas
The models set up for each of the airports were used to evaluate potential impacts from moving aircraft run-up areas. Figure 16 shows the maximum three-month average concentrations at RVS, SMO, and PAO, for the base case, Z1, and Z2 scenarios. Concentrations for all three scenarios are highest during the winter months at both airports, with the period of November–January being the three-month period with the highest modeled concentration for all three airports.
Figure 16
Maximum Three-Month Average Concentrations for the November-January Period at Each Airport for Different Run-Up Areas
The effectiveness of moving the run-up areas varies by airport. At RVS and SMO, movement of run-up areas could potentially lead to a reduction of about 30% in the maximum Pb concentration; at PAO, however, moving the run-up area would lead to a reduction of only 7%. These findings support the recommendation for evaluating the movement of run-up areas on an airport-by-airport basis.
It is also important to consider other airport activity when evaluating moving the run-up areas. As shown in the RVS modeling, moving the run-up areas farther away from the runway ends eventually resulted in bringing maximum hotspot concentrations closer to original levels because run-up emissions mix with emissions from other busy taxiways. It is also important to note that run-up areas are located close to runways in part to reduce noise near airport hangars. The noise impacts of moving the run-up areas are an important consideration.
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