ISCST3 Tech Guide

Gaussian Plume Air Dispersion Model

7.2.4 The Long-Term Open Pit Source Model

The ISC Long Term Open Pit Source Model is based on the use of the long term area source model described in Section 2.2.3. The escape fractions and adjusted mass distribution for particle emissions from an open pit, and the determination of the size, shape and location of the effective area source used to model open pit emissions are described in Section 1.2.4. For the Long Term model, a sector average value for open pit sources is calculated by determining an effective area for a range of wind directions within the sector and increasing the number of wind directions used until the result converges, as described in Section 2.2.3 for the Long Term area source model. The contribution from each effective area used within a sector is calculated using the Short Term area source model described in Section 1.2.3.