Final Environmental Impact Statement 3-53 Chapter 3 Affected Environment

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1 3.4.4 Transit Air Quality Impact Criteria Air quality impact analysis for this project is based on the criteria as defined in the U.S. Federal Transit Administration (FTA) Environmental Process. FTA requires that mass transit projects proposed for federal funding must meet the requirements of the Clean Air Act in addition to NEPA requirements. The Clean Air Act contains detailed transportation conformity requirements to ensure that federally funded highway and transit projects conform to the applicable SIP. This analysis is useful in addressing the mesoscale (regional) concerns of the project. The conformity requirements apply only in nonattainment and maintenance areas. In addition to the conformity issues, the Federal Transit Administration requires that a microscale CO analysis be performed. This analysis is required for each reasonable alternative for the estimated time of completion and design year. Total CO concentrations (project contribution plus estimated background) at identified reasonable receptors for each alternative should be reported and a comparison should be made between alternatives and with applicable State and national standards. In case the preferred alternative would result in violations of 1 or 8-hr standards, an effort should be made to develop reasonable mitigation measures through early coordination between FTA, EPA, and appropriate State and local highway and air quality agencies. 3.5 NOISE This section describes the methodology used to characterize the existing noise and vibration conditions along the Irving/DFW Line of the DART Northwest Corridor, and provides background information on airborne noise and ground-borne vibration issues related to the proposed transit project. Noise is typically defined as unwanted or undesirable sound, where sound is characterized by small air pressure fluctuations above and below the atmospheric pressure. The basic parameters of environmental noise that affect human subjective response are (1) intensity or level, (2) frequency content and (3) variation with time. The first parameter is determined by how greatly the sound pressure fluctuates above and below the atmospheric pressure, and is expressed on a compressed scale in units of decibels. By using this scale, the range of normally encountered sound can be expressed by values between 0 and 120 decibels. On a relative basis, a 3-decibel change in sound level generally represents a barely-noticeable change outside the laboratory, whereas a 10-decibel change in sound level would typically be perceived as a doubling (or halving) in the loudness of a sound. The frequency content of noise is related to the tone or pitch of the sound, and is expressed based on the rate of the air pressure fluctuation in terms of cycles per second (called Hertz and abbreviated as Hz). The human ear can detect a wide range of frequencies from about 20 Hz to 17,000 Hz. However, because the sensitivity of human hearing varies with frequency, the A- weighting system is commonly used when measuring environmental noise to provide a single number descriptor that correlates with human subjective response. Sound levels measured using this weighting system are called A-weighted sound levels, and are expressed in decibel notation as dba. The A-weighted sound level is widely accepted by acousticians as a proper unit for describing environmental noise. Because environmental noise fluctuates from moment to moment, it is common practice to condense all of this information into a single number, called the equivalent sound level (Leq). Leq can be thought of as the steady sound level that represents the same sound energy as the varying sound levels over a specified time period (typically 1 hour or 24 hours). Often the Leq values over a 24-hour period are used to calculate cumulative noise exposure in terms of the Day- Night Sound Level (Ldn). Ldn is the A-weighed Leq for a 24-hour period with an added 10-decibel penalty imposed on noise that occurs during the nighttime hours (between 10 P.M. and 7 A.M.). Many surveys have shown that Ldn is well correlated with human annoyance, and therefore this Final Environmental Impact Statement 3-53

2 descriptor is widely used for environmental noise impact assessment. Figure 3-18 provides examples of typical noise environments and criteria in terms of Ldn. While the extremes of Ldn are shown to range from 35 dba in a wilderness environment to 85 dba in noisy urban environments, Ldn is generally found to range between 55 dba and 75 dba in most communities. As shown in Figure 3-18, this spans the range between an ideal residential environment and the threshold for an unacceptable residential environment according to U.S. Federal agency criteria Transit Noise Criteria Noise impact for this project is based on the criteria as defined in the U. S. Federal Transit Administration (FTA) guidance manual Transit Noise and Vibration Impact Assessment (FTA- VA , May 2006). The FTA noise impact criteria are founded on well-documented research on community reaction to noise and are based on change in noise exposure using a sliding scale. Although more transit noise is allowed in neighborhoods with high levels of existing noise, smaller increases in total noise exposure are allowed with increasing levels of existing noise. The FTA Noise Impact Criteria group noise sensitive land uses into the following three categories: Category 1: Buildings or parks where quietness is an essential element of their purpose. Figure 3-18 Examples of Typical Outdoor Noise Exposure Final Environmental Impact Statement 3-54

3 Category 2: Residences and buildings where people normally sleep. This includes residences, hospitals, and hotels where nighttime sensitivity is assumed to be of utmost importance. Category 3: Institutional land uses with primarily daytime and evening use. This category includes schools, libraries, and churches. Ldn is used to characterize noise exposure for residential areas (Category 2). For other noise sensitive land uses such as parks and school buildings (Categories 1 and 3), the maximum 1-hour Leq during the facility s operating period is used. There are two levels of impact included in the FTA criteria. The interpretation of these two levels of impact is summarized below: Severe: Severe noise impacts are considered "significant" as this term is used in the National Environmental Policy Act (NEPA) and implementing regulations. Noise mitigation will normally be specified for severe impact areas unless there is no practical method of mitigating the noise. Moderate: In this range of noise impact, other project-specific factors must be considered to determine the magnitude of the impact and the need for mitigation. These other factors can include the predicted increase over existing noise levels, the types and number of noise-sensitive land uses affected, existing outdoor-indoor sound insulation, and the cost effectiveness of mitigating noise to more acceptable levels. The noise impact criteria are summarized in Table The first column shows the existing noise exposure and the remaining columns show the additional noise exposure from the transit project that would cause either moderate or severe impact. The future noise exposure would be the combination of the existing noise exposure and the additional noise exposure caused by the transit project Existing Noise Conditions Noise-sensitive land use along the Project Corridor was first identified based on preliminary alignment drawings, aerial photographs, visual surveys and land use information from the Existing Conditions inventory. Based on this review, summary descriptions of noise-sensitive land use and existing noise sources along the Irving LRT Corridor, from southeast to northwest, are as follows: Cistercian Abbey. The proposed alignment is located between the Abbey and the existing freeway. There is also a preparatory school located behind the Abbey at this location. The dominant noise source in the area is the John W. Carpenter Freeway (SH 114). Miss Bloomingdale s Academy (Rochelle Boulevard). The proposed alignment is located adjacent to this childcare facility at the corner of Rochelle Boulevard and Teleport Boulevard. The existing noise environment is dominated by traffic on Rochelle Boulevard and Teleport Boulevard. Mandalay on the Lake Apartments. New multi-family apartment buildings are currently being constructed south of O Connor Boulevard, on Lake Carolyn Boulevard between Las Colinas Boulevard and California Crossing Road. The proposed alignment is located in the median of Lake Carolyn Parkway, directly adjacent to the apartments. The major sources of existing noise include traffic on Lake Carolyn Parkway, Rochelle Boulevard, and Northwest Highway (Spur 348). Final Environmental Impact Statement 3-55

4 Existing Noise Exposure TABLE 3-23 FTA NOISE IMPACT CRITERIA Project Noise Exposure Impact Thresholds, Ldn or Leq (dba) Category 1 or 2 Sites Category 3 Sites Leq or Ldn Impact Severe Impact Impact Severe Impact <43 Amb.+10 Amb.+15 Amb.+15 Amb > Note: Ldn is used for land uses where nighttime sensitivity is a factor; maximum 1 hour Leq is used for land use involving only daytime activities. Source: Federal Transit Administration, May 2006 Lofts at Las Colinas and Delano A Las Colinas Residence (Lake Carolyn Parkway). These multi-family apartment buildings are located on Lake Carolyn Boulevard, north of O Connor Road. The proposed alignment is located in the median of Lake Carolyn Boulevard in front of these multi-family apartment buildings. The major noise sources include traffic noise from Northwest Highway (Spur 348), located on the opposite side of the alignment from the apartments. Local traffic on Lake Carolyn Parkway and O Connor Boulevard also contribute to the existing noise environment. Final Environmental Impact Statement 3-56

5 Las Colinas Studio Plus and Candlewood Suites hotels (Meadow Creek Drive). These hotels are located on the opposite side of Meadow Creek Drive from the proposed alignment, at the corner of Meadow Creek Drive and Green Park Drive. The Extended Stay Deluxe and the Fairfield Inn & Suites hotels are also located behind these hotels. Contributors to the existing noise environment include traffic at the intersection of Meadow Creek Drive and Green Park Drive, traffic on the Northwest Highway, and aircraft arriving at or departing from DFW Airport. The Villas at Beaver Creek (Meadow Creek Drive). These multi-family apartment buildings are located on Meadow Creek Drive, between Green Park Drive and MacArthur Boulevard. The proposed alignment is located behind these multi-family apartment buildings, with a small channel of water separating them from the alignment. Contributors to the existing noise environment include traffic at a nearby parking garage that is accessed via Hidden Ridge Drive and aircraft arriving at or departing from DFW Airport. Archstone at MacArthur Apartment Homes (1100 Hidden Ridge Drive). These multi-family apartment buildings are located on Hidden Ridge Drive, between MacArthur Boulevard and Brangus Drive. The proposed alignment is located behind these multi-family apartment buildings, along North Lake College Road, which is directly to the south of the apartments. Existing noise sources include local traffic on North Lake College Road and aircraft arriving at or departing from DFW Airport. Mandalay Place (Brangus Drive). These single family residences are located on St. Croix and St. Monet, off of Brangus Drive. The proposed alignment is located behind these single-family residences. Existing noise sources include local traffic on Brangus Drive and aircraft arriving at or departing from DFW Airport. Existing ambient noise levels in the above areas were characterized through direct measurements at selected sites along the proposed alignment during the period from August 30 through September 1, 2005 and July 5 through July 6, Estimating existing noise exposure is an important step in the noise impact assessment since, as indicated above in Section 3.5.1, the thresholds for noise impact are based on the existing levels of noise exposure. The measurements included both long-term (24-hour) and short-term (60 minute) monitoring of the A- weighted sound level at representative noise-sensitive locations. All of the measurement sites were located in noise-sensitive areas, and were selected to represent a range of existing noise conditions along the corridor. Figure 3-19 shows the general location of the four long-term monitoring sites (LT-1 through LT-5) and one short-term monitoring site (ST-1). At each site, the measurement microphone was positioned to characterize the exposure of the site to the dominant noise sources in the area. For example, microphones were located at the approximate setback lines of the receptors from adjacent roads or rail lines, and were positioned to avoid acoustic shielding by landscaping, fences or other obstructions. The results of the existing ambient noise measurements, summarized in Table 3-24, serve as the basis for determining the existing noise conditions at all noise-sensitive receptors along the Irving Line of the Northwest Corridor. The results at each site are described below. Final Environmental Impact Statement 3-57

6 N MACARTHUR BLVD VALLEY VIEW LN ESTERS RD UV 161 Cabell Dr DFW International Airport NORTHGATE DR ROCHELLE RD BELT LINE RD BELT LINE RD Belt Line Road CARBON RD Source: HMMH, 2006 WALNUT HILL LN IRVING BLVD STORY RD UV114 PRESIDENT GEORGE BUSH TPKE WALNUT HILL LN JOHN CARPENTER FWY Carpenter Ranch LT-5 North Lake College Irving LT-4 E AIRPORT FWY MACARTHUR BLVD H LT-3 I DDEN RIDGE DR N O' CONNOR RD ROYAL LN Lake Carolyn BNSF RR RIVERSIDE DR North Las Colinas ST-1 LT-2 ROCHELLE BLVD Farmers Branch &- 348 JOHN CARPENTER FWY LUNA RD CALIFORNIA CROSSING RD South Las Colinas (deferred) LT-1 University of Dallas TOM BRANIFF DR Dallas NORTHWEST HWY UV 183 UV 354 GRAUWYLER RD 12 Loop 12 (deferred) 35E STOREY LN & E lm Fork Trinity River</FNT> HARRY HINES BLVD Bachman REGAL ROW 35E WALNUT HILL LN DENTON DR WEB CHAPEL RD Figure 3-19 NW Corridor LRT Line to Irving/DFW 0 2,000 4,000 8,000 Environmental Impact Statement Feet Ambient Noise Monitoring Locations Legend Short-term Noise Monitoring Location Long-term Noise Monitoring Location Proposed Station Proposed LRT Line to Irving/DFW Carrollton-Farmers Branch LRT Line UV 354

7 Site No. TABLE 3-24 SUMMARY OF EXISTING AMBIENT NOISE MEASUREMENT RESULTS Measurement Location Description Start of Measurement Meas. Time (hrs) Noise Exposure (dba) Date Time Ldn Leq LT-1 Cistercian Abbey Irving : LT-2 Lofts at Las Colinas Irving : LT-3 Los Colinas Studio Plus Irving : LT-4 The Villas at Beaver Creek Irving : LT-5 Archstone at MacArthur Apartment Homes Irving : ST-1 Miss Bloomingdale s Academy Irving : Source: Harris Miller Miller & Hanson Inc., 2006 Site LT-1: Cistercian Abbey. The Ldn measured at the Abbey was 68 dba. The ambient noise levels were dominated by noise from the John W. Carpenter Freeway (SH 114). Ambient noise levels were monitored for 24 hours. Site LT-2: Lofts at Las Colinas (Lake Carolyn Parkway). The Ldn measured near these multi-family residences was 63 dba. Major noise sources included traffic from Northwest Highway (Spur 348) and other local activities. Ambient noise levels were monitored for 24 hours in front of one of the apartment buildings. The measurement at this location can be used to estimate the existing noise exposure at the new apartment buildings on Lake Carolyn being built to the southeast as well. Site LT-3: Las Colinas Studio Plus (Meadow Creek Drive). The Ldn measured at this hotel was 64 dba. The major noise sources were traffic on Meadow Creek Drive, traffic on Northwest Highway and aircraft arrivals at DFW Airport. Ambient noise levels were monitored for 24 hours in front of the hotel, near Meadow Creek Drive. Site LT-4: The Villas at Beaver Creek (Meadow Creek Drive). The Ldn measured near these multi-family residences was 56 dba. The noise sources included traffic from a nearby parking garage and aircraft arrivals at DFW Airport. Ambient noise levels were monitored for 24 hours behind the residences, on the opposite side of the water channel. Site LT-5: Archstone at MacArthur Apartment Homes (1100 Hidden Ridge Drive). The Ldn measured at these multi-family residences was 58 dba. Existing noise sources included traffic on North Lake College Road, aircraft arrivals at DFW Airport, and exterior air conditioning compressors at the residences. Ambient noise levels were monitored for 24 hours behind the residences. The measurement at this location can be used to estimate the ambient noise at the nearby Mandalay Place residences as well. Site ST-1: Miss Bloomingdale s Academy (Rochelle Boulevard). The Leq measured during a short term measurement at this location was 60 dba. The major sources of existing noise are traffic on Rochelle Boulevard and Transport Boulevard, and cars in the parking lot of the childcare facility. Ambient noise levels were monitored during one peak transit hour period at this location. 3.6 VIBRATION Ground-borne vibration is the oscillatory motion of the ground about some equilibrium position that can be described in terms of displacement, velocity or acceleration. Because sensitivity to vibration typically corresponds to the amplitude of vibration velocity within the low-frequency range Final Environmental Impact Statement 3-59