point cover jan 13 - Boston Redevelopment Authority

Emission Rates
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Expanded_PNF\04_Environmental_FINAL.do
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Vanasse Hangen Brustlin, Inc.
The Point, Boston
All the vehicle emission factors used in the microscale analysis were obtained using the EPA's MOBILE 6.2 7
emissions model. MOBILE 6.2 calculates CO, PM10, and PM2.5 emission factors from motor vehicles in grams
per vehicle-mile. The emission rates calculated in this study were adjusted to reflect Massachusetts-specific
conditions, such as the state vehicle registration age distribution, the statewide Inspection and Maintenance
(I/M) Program, and the Stage II Vapor Recovery System. 8 Emission factors for the mobile sources were
determined using the DEP-recommended temperatures for the winter (CO) season and summer (PM) season.
Traffic Data
The air quality study utilized motor vehicle traffic data specifically developed for each analysis condition.
The Build Condition used for the microscale analysis includes the physical and operational mitigation
proposed to improve traffic operations. The microscale analysis used the evening peak hour traffic conditions
during the CO season (winter). Vehicle speeds were developed based upon traffic volumes, observed traffic
flow characteristics, and roadway capacity. The traffic data were developed based on the traffic study
presented in Chapter 3, Transportation of this PNF report.
Existing Air Quality Conditions
The CAAA resulted in states being divided into attainment and non-attainment areas, with classifications
based upon the severity of their air quality problems. The Project is located in the Boston Metropolitan area,
which has been classified as a “Maintenance” area for CO and an attainment area for PM10 and PM2.5.
The microscale analysis determined that the 1-hour CO concentrations for the 2012 Existing Condition ranged
from a minimum of 4.2 parts per million (ppm) at the intersection of Boylston Street at Yawkey Way to a
maximum of 6.3 ppm at the intersection of Brookline Avenue at Fenway. The corresponding maximum
8-hour CO concentrations ranged from a minimum of 2.9 ppm to a maximum of 4.4 ppm. The microscale CO
results are presented in Table 4-3 and Table 4-4 (presented below). All the 1-hour and 8-hour concentrations
are below the CO NAAQS of 35 and 9 ppm, respectively. These values are consistent with the area’s
designation as a CO Maintenance area.
The microscale analysis determined that the 24-hour PM10 concentrations for the 2012 Existing Condition
ranged from a minimum of 41.3 micrograms per cubic meter (ug/m 3 ) at the intersection of Brookline Avenue
at Kilmarnock Street and the intersection of Boylston Street at Kilmarnock Street to a maximum of 43.3 ug/m 3
at the intersection of Brookline Avenue at Fenway. The microscale PM10 results are presented in Table 4-5
(presented below). All concentrations are below the PM10 NAAQS of 150 ug/m 3 .
The microscale analysis determined that the 24-hour PM2.5 concentrations for the 2012 Existing Condition
ranged from a minimum of 23.1 ug/m 3 at the intersection of Brookline Avenue at Kilmarnock Street and the
5 MOBILE 6.2 (Mobile Source Emission Factor Model), The May 19, 2004 official release from US EPA, Office of
Mobile Sources, Ann Arbor, MI.
6 The Stage II Vapor Recovery System is the process of collecting gasoline vapors form vehicles as they are refueled.
This requires the use of a special gasoline nozzle at the fuel pump.
4-19 Environmental Protection