Appendix 3.1 Calcualtion of Dust Emission Factor
Source	Emission Factors	Unmitigated	Mitigated	Parameters
Sai Kung Drainage Improvement Work (Sai Kung River, Pak Kong River and Ho Chung Channel)
1	Material handling  (50 % dust reduction by watering the site area twice a day)	########	4.0898E-04	TSP emission factor (kg/Mg)	k*0.0016*(U/2.2)^1.3 / (M/2)^1.4
	for Sai Kung River, Pak Kong River and Ho Chung Channel					from AP-42, 5th ed., S13.2.4
	(g/s)			Particle size mutipler, k	0.74	from AP-42, 5th ed., S13.2.4, particle size < 30 um
				Material moisture content, M (%)	20	from preliminary site investigation report
				Average wind speed, U (m/s)	3.1	from Hong Kong Observatory
				E (g/Mg)	0.0736	calculated
				Density of the spoil (Mg/m3)	2	assumed
				Handling Capacity (m3/hr)	20	from engineer
				% mitigation	50	Watering the site area twice a day
				PM-10 emission factos (kg/Mg)	4.00E-05	from AP-42, 5th ed., S11.19.2
2	Excavation	########	9.3333E-04	TSP emission factor (kg/Mg)	8.40E-05	calculated (base on AP-42, 5th ed., S13.2.2 & S13.2.4)
	for Sai Kung River, Pak Kong River and Ho Chung Channel
	(g/s)			Density of the spoil (Mg/m3)	2	assumed
				Capacity (m3/hr)	20	from engineer
	Total (g/s)	########	1.3423E-03
	for Sai Kung River, Pak Kong River and Ho Chung Channel
3	Unpaved haul road (50 % dust reduction by watering the site area twice a day)	########	4.5945E-04	TSP emission factor (g/VKT)	281.9*k*(S/12)^0.8(W/3)^0.5 / (M/0.2)^0.4*(S/15)
	for Sai Kung River					from AP-42, 5th ed., S13.2.2-2-3
	(g/s/m)			Particle size mutipler, k	10	from AP-42, 5th ed., S13.2.2-3, particle size < 30 um
				Material moisture content, M (%)	20	from preliminary site investigation report
				Silt content (%)	8.5	from AP-42, 5th ed., Table 13.2.2-1
				Vehicle weight (ton)	26	assumed
				Flow including return trip  (veh/hr)	8	from Engineer
				Speed (kph)	10	assumed
				Speed, S (mph)	6.2139	from AP-42, 5th ed., S13.2.2
				E (g/VKT)	413.507124
				% mitigation	50	Watering the site area twice a day
4	Unpaved haul road (70 % dust reduction by extensive watering )	########	2.7567E-04	TSP emission factor (g/VKT)	281.9*k*(S/12)^0.8(W/3)^0.5 / (M/0.2)^0.4*(S/15)
	for Ho Chung Channel and Pak Kong River					from AP-42, 5th ed., S13.2.2-2-3
	(g/s/m)			Particle size mutipler, k	10	from AP-42, 5th ed., S13.2.2-3, particle size < 30 um
				Material moisture content, M (%)	20	from preliminary site investigation report
				Silt content (%)	8.5	from AP-42, 5th ed., Table 13.2.2-1
				Vehicle weight (ton)	26	assumed
				Flow including return trip  (veh/hr)	8	from Engineer
				Speed (kph)	10	assumed
				Speed, S (mph)	6.2139	from AP-42, 5th ed., S13.2.2
				E (g/VKT)	413.507124
				% mitigation	70	Extensive Watering
Improvement of Ho Chung Road
General construction activities		########	5.1890E-05
(g/m2/s)				TSP emission factor (Mg/hectare/month)	2.69	from AP-42, 5th ed., S13.2.3.3
Line sources emissions with 10 m width:		########	5.1890E-04
(g/m/s)				Percentage area actively operating (%)	100	assumed
				% mitigation	50	Watering the site area twice a day