Wireless Facility Radio Frequency Compliance Review

Transcription

1 Wireless Facility Radio Frequency Compliance Review ATT Application Modification of Existing Wireless Facility 554 El Camino Real, Belmont, CA Site ID: CCL /10/2017 Preiser Consulting La Posta Court, Corona, CA Tel Fax

2 ATT Application Modification of Existing Wireless Facility 554 El Camino Real, Belmont, CA Site ID: CCL00730 Introduction Preiser Consulting has been engaged by the City of Belmont to conduct a peer review of the radio frequency (RF) safety aspects of a permit application by ATT for the modification of an existing wireless facility located at 554 El Camino Real, Belmont, CA. System Description ATT is proposing to modify an existing wireless facility located at a U Haul Self Storage building by replacing three existing antennas, decommissioning the 850 MHz GSM 1 and 1,900 MHz UMTS 2 systems, and install additional 850 MHz and 2130 MHz 3 systems. The apparent objective is to decommission legacy equipment and replacing it with 4 th generation (4G) equipment to increase voice and data capacity. The site has the antennas mounted on the exterior of the building, below the roof line. Associated base stations and power equipment are located in an adjacent fenced equipment service shelter. Three existing antennas, Kathrein Model , one in each of the three antenna sectors, will be replace with Commscope SBNHH 1D65A 4.58 panel antennas to be mounted in the same position at a height of 39 above ground based on the center of radiation. The type of antenna proposed, as most other cellular antennas, is designed to concentrate radiated energy toward the horizon in the direction of orientation, with very little energy 1 GSM is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second generation (2G) digital cellular networks 2 Universal Mobile Telecommunications System (UMTS) is a third generation (3G) mobile cellular system for networks based on the GSM standard. 3 Long Term Evolution (), commonly marketed as 4G, is a standard for 4 th generation mobile wireless communications for high speed data and voice. Preiser Consulting Page 2

3 wasted toward the sky or the ground. A detailed specification sheet is provided in Attachment 1. With this site modification, ATT will be operating in five (5) different frequency bands, 700 MHz, 850 MHz, 1900 MHz, 2130 MHz and 2300 MHz, providing voice and high speed data services service with UMTS and technology. Table 1, below, contains the proposed site antenna inventory with basic operating parameters. The proposed replacement antennas are highlighted in the table. ATT Antennas Ant # A1 A1 A2 A2 A3 A3 B1 B1 B2 B2 B3 B3 C1 C1 C2 C2 C3 C3 Transmitter Frequency Band and Technology 850 MHz UMTS 2,130 MHz 850 MHz 2,300 MHz 700 MHz 1,900 MHz 850 MHz UMTS 2,130 MHz 850 MHz 2,300 MHz 700 MHz 1,900 MHz 850 MHz UMTS 2,130 MHz 850 MHz 2,300 MHz 700 MHz 1,900 MHz Effective Radiated Power (ERP) (Watts) Antenna Gain (dbd) Azimuth (Deg) Antenna Model Horizontal Beamwidth (Deg) Ant. Length (ft) Height Above Ground (ft) Center of Radiation CommScope SBNHH 1D65A CommScope SBNHH 1D65A CommScope SBNHH 1D65A CommScope SBNHH 1D65A Kathrein Kathrein CommScope SBNHH 1D65A CommScope SBNHH 1D65A CommScope SBNHH 1D65A CommScope SBNHH 1D65A Kathrein Kathrein CommScope SBNHH 1D65A CommScope SBNHH 1D65A CommScope SBNHH 1D65A CommScope SBNHH 1D65A Kathrein Kathrein Preiser Consulting Page 3

4 Table 1 Antenna Inventory Sector A Sector B Sector G Figure 1, below, is an aerial vicinity view of the existing facility. Sector A (30 deg) Antennas Sector B (110 deg) Antennas Sector C (280 deg) Antennas Figure 1 Aerial View Methodology In conducting a peer review, relevant site application documents are reviewed and analyzed against current FCC regulations and guidelines, wireless industry standards and best practices. In this case, the project construction drawings, dated 6/20/2017, and the RF study by OSC Engineering, Inc., dated 3/24/2017, were reviewed relative to the RF safety aspects to determine compliance with Federal Communications Commission guidelines. Potential RF exposure levels were independently calculated using methods detailed in their Office of Preiser Consulting Page 4

5 Engineering & Technology Bulletin No. 65, Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields, August 1997 ( OET Bulletin 65 ). Based on the OET Bulletin 65, the Maximum Permissible Exposure ( MPE ) for the general population/uncontrolled exposure is 0.47 mw/cm² in the 700 MHz spectrum, 0.58 mw/cm² in the Cellular spectrum (850 MHz) and 1 mw/cm² in the PCS (1,900 MHz), AWS(2,130) MHz and WCS (2,300 MHz) spectrum and higher. Permissible levels for exposure under occupational/controlled conditions, such as may be encountered by maintenance personnel, are five times higher. (See Attachment 2 for a general discussion of FCC MPE levels.) Findings Relating to Radio Frequency Emissions Safety The potential exposure levels documented in the OSC Engineering Report were independently verified by Preiser Consulting using modeling techniques consistent with FCC guidelines. The calculations were based on very conservative modeling assumptions; actual levels are expected to be significantly lower. The results indicate the following: 1. The maximum calculated exposure at ground level would not exceed 17.6% of the applicable public exposure limit. 2. Exposure levels may exceed the occupational MPE limits within a 3 foot zone directly in front of the panel antennas in the direction of orientation. However, this zone would only be accessible by maintenance personnel working at an elevated position directly in front of the antenna. The following measures are recommended: 1. Provide RF safety awareness training to personnel that may work at elevated positions directly in front of the antennas. 2. Post green information signs (INFO 1) at the roof access points. (These may already be in place but should be verified.) Preiser Consulting Page 5

6 3. Provide green information signs (INFO 2) on the parapet near each antenna sector. These may already be in place but should be verified.) Summary and Conclusions Preiser Consulting is of the opinion that the modification of the wireless facility as proposed complies with FCC guidelines for permissible levels of radio frequency exposure. Certification 1. I have read and fully understand the FCC regulations concerning RF safety and the control of human exposure to RF fields (47 CFR et seq). 2. To the best of my knowledge, the statements and information disclosed in this report are true, complete and accurate. 3. The analysis of site RF compliance provided herein is consistent with the applicable FCC regulations, additional guidelines issued by the FCC, and industry practices. Date: July 10, 2017 Dieter J. Preiser, PMP Preiser Consulting Page 6

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8 Attachment 1 Page 2

9 Attachment 1 Page 3

10 Attachment 2 The FCC MPE Limits The Federal Communications Commission (FCC) has established limits for maximum continuous human exposure to RF fields as directed by the Telecommunications Act of The FCC maximum permissible exposure (MPE) limits represent the consensus of federal agencies and independent experts responsible for RF safety matters. Those agencies include the National Council on Radiation Protection and Measurements (NCRP), the Occupational Safety and Health Administration (OSHA), the National Institute for Occupational Safety and Health (NIOSH), the American National Standards Institute (ANSI), the Environmental Protection Agency (EPA), and the Food and Drug Administration (FDA). In developing its guidelines, the FCC also considered input from the public and technical community notably the Institute of Electrical and Electronics Engineers (IEEE). The FCC s RF exposure guidelines are incorporated in Section et seq of its Rules and Regulations (47 CFR ). Those guidelines specify MPE limits for two types of exposures to RF energy: 1. Occupational / Controlled Exposure persons who are exposed as a consequence of their employment and are fully aware of the potential for exposure and have the ability to exercise control over their exposure. 2. General Population/Uncontrolled Exposure apply when one is exposed and may not be fully aware of the potential for exposure or cannot exercise control over their exposure. The specified continuous exposure MPE limits are based on known variation of human body susceptibility in different frequency ranges, and a Specific Absorption Rate (SAR) of 4 watts per kilogram, which is universally considered to accurately represent human capacity to dissipate incident RF energy (in the form of heat). The occupational MPE guidelines incorporate a safety factor of 10 or greater with respect to RF levels known to represent a health hazard, and an additional safety factor of five is applied to Attachment 2 Page 1

11 the MPE limits for general population exposure. Thus, the general population MPE limit has a built in safety factor of more than 50. The limits were constructed to appropriately protect humans of both sexes and all ages and sizes and under all conditions and continuous exposure at levels equal to or below the applicable MPE limits is considered to result in no adverse health effects or even health risk. The reason for two tiers of MPE limits is based on an understanding and assumption that members of the general public are unlikely to have had appropriate RF safety training and may not be aware of the exposures they receive; occupational exposure in controlled environments, on the other hand, is assumed to involve individuals who have had such training, are aware of the exposures, and know how to maintain a safe personal work environment. The FCC s RF exposure limits are expressed in two equivalent forms, using alternative units of field strength (expressed in volts per meter, or V/m), and power density (expressed in milliwatts per square centimeter, or mw/cm2). The table below lists the FCC limits for both occupational and general population exposures, using the mw/cm2 reference, for the different radio frequency ranges. The diagram below provides a graphical illustration of both the FCC s occupational and general population MPE limits. Attachment 2 Page 2

12 Because the FCC s RF exposure limits are frequency shaped, the exact MPE limits applicable for a particular system installation depend on the frequency range used by the systems of interest. The most appropriate method of determining RF compliance is to calculate the RF power density attributable to a particular system and compare that to the MPE limit applicable to the operating frequency in question. The result is usually expressed as a percentage of the MPE limit. For potential exposure from multiple systems, the respective percentages of the MPE limits are added, and the total percentage compared to 100 (percent of the limit). If the result is less than 100, the total exposure is in compliance; if it is more than 100, exposure mitigation measures are necessary to achieve compliance. Attachment 2 Page 3

13 Attachment 3 Statement of Qualifications SUMMARY OF EXPERIENCE: Over 35 years experience in all facets of telecommunications, with specialization in wireless technologies, including six years as an independent consultant for state and local government agencies on wireless and wireline telecommunications technologies. Areas of expertise include: Mobile radio technologies for public safety agencies Wireless site development and operation Tower design and implementation Cellular voice and data technologies In building coverage solutions Distributed Antenna Systems (DAS) Fiber optic and microwave backhaul transmission Next Generation systems design and implementation Satellite voice and data transmission CLIENTS SERVED: Wireless Site Development and Evaluation: City of San Diego, CA City of Martinez, CA City of Berkeley, CA City of Belmont, CA County of Santa Barbara, CA City of Burlingame, CA City of San Jose, CA City of Palo Alto, CA Other Wireless and Telecom Projects: County of Los Angeles, CA County of Riverside, CA State of Washington Salt Lake City, UT North Slope Borough, AK Clark County, WA Chelan County PUD, WA Fresno Fire Department ADDITIONAL INFORMATION: BS Degree in Electronic Technology, MBA in Information Systems Certified Telecommunications Engineer RF Endorsement (NARTE) First Class FCC Radio Telephone license Project Management Professional (PMP) certification from the Project Management Institute (PMI) Certified Cost Engineer (AACE), volunteer certification course instructor. Served as chairman of the Engineering Sub Committee of the California Public Safety Radio Association. (CPRA) a local chapter of the Association of Public Safety Officials (APCO) Served as chairman of the Regulatory Review Committee of the California Public Safety Radio Association representing southern California in matters before the FCC and Public Utilities Commission Member of the Associated Public Safety Communications Officials International (APCO) FCC Amateur Radio License, N6DGS Served as a Computer and Communications Specialist with the California Air National Guard, Combat Communications Squadron Remote Pilot License issued by the Federal Aviation Administration (FAA) Attachment 3 Page 1

14 ELECTROMAGNETIC ENERGY (EME) EXPOSURE REPORT Site Name: Site ID: USID: FA Location: Belmont 3 El Camino Real CCL Site Type: Rooftop Location: 554 El Camino Real Belmont, CA Latitude (NAD83): Longitude (NAD83): Report Completed: AT&T M-RFSC March 24, 2017 Casey Chan Prepared By: Prepared for: AT&T Mobility c/o Caldwell Compliance, Inc Koll Center Parkway. Ste. 401 Pleasanton, CA 94566

15 Site Overview and Description The antennas are façade mounted on a building The site consists of three (3) sectors with a total of nine (9) antennas The site is not co-located Sector A Sector B Sector G Azimuth 30º 280º 110º Number of antennas Bottom tip of antenna above ground (ft.) Bottomtip of antenna above roof (ft.) Technology UMTS / UMTS / UMTS / Commscope SBNHH-1D65A Commscope SBNHH-1D65A Commscope SBNHH-1D65A Antenna Make and Model Kathrein Kathrein Kathrein Site Compliance Status (FCC & AT&T Guidelines) Compliant with recommendations OSC Engineering Inc. Page 2/13

16 Compliance Notes Occupational Safety & Compliance Engineering (OSC Engineering) has been contracted by Caldwell Compliance, Inc. to conduct an RF (radio frequency) computer simulated analysis. The Federal Communications Commission (FCC) has set limits on RF energy exposed to humans on a wireless cell site in order to ensure safety. The FCC has also mandated that all RF wireless sites must be in compliance with the FCC limits and a compliance check should be performed annually to ensure site compliance. This report is an in depth analysis summarizing the results of the RF modeling provided to us by AT&T and in relation to relevant FCC RF compliance standards. A reanalysis is recommended upon the site going on air. OSC Engineering uses the FCC OET-65 as well as AT&T Standards to make recommendations based on results and information gathered from drawings and Radio Frequency Data Sheets. For this report, OSC Engineering utilized Roofview software for the theoretical analysis of the AT&T Cellular Facility. A site-specific compliance plan is recommended for each transmitting site. This report serves as a single piece of the overall compliance plan. Information utilized for this report: RFDS: SAN-FRANCISCO-SACRAMENTO_SAN-FRANCISCO_CNU0730_2017--Next- Carrier_-4C_ps7945_3701A07GEL_ _13309_ _Final- Approved_v4.00 (1) DWGs: CCL00730_4C5C_CDRLCompleted_ For the purpose of theoretical simulation, OSC Engineering models antennas as if they are operating at full power (100% capacity). This assumption yields more conservative (higher) results. On-site measurements may yield different results, as antennas do not always operate at full capacity. To the right is a result diagram of the site in question. The diagram is a color-coded map per ND levels, which coincide with FCC MPE Limits. Any exposure resulting in a level higher than 100% exceeds the Limits and requires further action, such as barriers. A level exceeding 100% does not make a site out of compliance. All results are given in General Population percentages even when a site may be considered Occupational. OSC Engineering Inc. Page 3/13

17 Compliance Results of the Proposed Site (theoretical simulation) Max RF Exposure Level from (AT&T roof): % FCC General Population MPE Limit Max RF Exposure Level simulated (AT&T ground): 17.6 % FCC General Population MPE Limit OSC Engineering Inc. Page 4/13

18 FCC Regulations and Guidelines from OET 65 When considering the contributions to field strength or power density from other RF sources, care should be taken to ensure that such variables as reflection and re-radiation are considered. In cases involving very complex sites predictions of RF fields may not be possible, and a measurement survey may be necessary The process for determining compliance for other situations can be similarly accomplished using the techniques described in this section and in Supplement A to this bulletin that deals with radio and television broadcast operations. However, as mentioned above, at very complex sites measurements may be necessary. In the simple example shown in the below diagram, it is desired to determine the power density at a given location X meters from the base of a tower on which are mounted two antennas. One antenna is a CMRS antenna with several channels, and the other is an FM broadcast antenna. The system parameters that must be known are the total ERP for each antenna and the operating frequencies (to determine which MPE limits apply). The heights above ground level for each antenna, H1 and H2, must be known in order to calculate the distances, R1and R2, from the antennas to the point of interest. 1 1 OET Bulletin 65, Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields, Page OSC Engineering Inc. Page 5/13

19 Computer Simulation Analysis The Federal Communications Commission (FCC) governs the telecommunications services, facilities, and devices used by the public, industrial and state organizations in the United States. RoofView is a software analysis tool for evaluating radiofrequency (RF) field levels at roof-top telecommunications sites produced by vertical collinear antennas of the type commonly used in the cellular, paging, PCS, ESMR and conventional two-way radio communications services. 2 RF near-field levels are computed from selected antennas by applying a cylindrical model that takes into account the antenna s aperture height, mounting height above the roof, azimuthal beam width for directional antennas and the location of the antennas on the roof Resulting, spatially averaged power densities are expressed as a percentage of a user selectable exposure limit depending on frequency. The entire roof is composed of one-square-foot pixels and RF fields are computed for each of these pixels for each selected antenna. 3 Computer simulations produced for clients are simulated with Uptime = 100%. This means that all transmitters associated with an antenna are considered to be on. 4 RoofView uses a near-field method of computing the field based on assuming that the total input power delivered to the antenna, at its input terminal, is distributed over an imaginary cylindrical surface surrounding the antenna. The height of the cylinder is equal to the aperture height of the antenna while the radius is simply the distance from the antenna at which the field power density is to be computed. Within the aperture of the antenna, this approximation is quite accurate but as the antenna is elevated above the region of interest, the model output must be corrected for mounting height. 5 2 Roofview User Guide 4.15, Page 7, Richard A Tell Associates 3 Roofview User Guide 4.15, Page 7, Richard A Tell Associates 4 Roofview User Guide 4.15, Page 10, Richard A Tell Associates 5 Roofview User Guide 4.15, Page 45, Richard A Tell Associates OSC Engineering Inc. Page 6/13

20 Certification The undersigned is a Professional Engineer, holding a California Registration No Reviewed and approved by: John B. Bachoua, PE Date: March 24, 2017 The engineering and design of all related structures as well as the impact of the antennas on the structural integrity of the design are specifically excluded from this report s scope of work. This report s scope of work is limited to an evaluation of the Electromagnetic Energy (EME) RF emissions field generated by the antennas listed in this report. When client and others have supplied data, it is assumed to be correct. OSC Engineering Inc. Page 7/13

21 FCC MPE Limits (from OET-65) OSC Engineering uses the FCC s and clients guidelines to model the computer simulation. Explained in detail in Office of Engineering & Technology, Bulletin No. 65 ( OET-65 ) Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Radiation. Occupational/controlled 6 exposure limits apply to situations in which persons are exposed as a consequence of their employment and in which those persons who are exposed have been made fully aware of the potential for exposure and can exercise control over their exposure. Occupational/controlled exposure limits also apply where exposure is of a transient nature as a result of incidental passage through a location where exposure levels may be above general population/uncontrolled limits (see below), as long as the exposed person has been made fully aware of the potential for exposure and can exercise control over his or her exposure by leaving the area or by some other appropriate means. As discussed later, the occupational/controlled exposure limits also apply to amateur radio operators and members of their immediate household. General population/uncontrolled 7 exposure limits apply to situations in which the general public may be exposed or in which persons who are exposed as a consequence of their employment may not be made fully aware of the potential for exposure or cannot exercise control over their exposure. Therefore, members of the general public would always be considered under this category when exposure is not employment-related, for example, in the case of a telecommunications tower that exposes persons in a nearby residential area. 6 OET-65 Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields pg OET-65 Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields pg. 9. OSC Engineering Inc. Page 8/13

22 Limits for Maximum Permissible Exposure (MPE) 8 The FCC Exposure limits are based on data showing that the human body absorbs RF energy at some frequencies more efficiently than at others. The most restrictive limits occur in the frequency range of MHz where whole-body absorption of RF energy by human beings is most efficient. At other frequencies whole-body absorption is less efficient, and, consequently, the MPE limits are less restrictive. 9 8 OET-65 FCC Guidelines Table 1 pg OET-65 FCC Guidelines for Evaluating Exposure to RF Emissions, pg. 8 OSC Engineering Inc. Page 9/13

23 Limits for Maximum Permissible Exposure (MPE) continued 10 MPE Limits are defined in terms of power density (units of milliwatts per centimeter squared: mw/cm 2 ), electric field strength (units of volts per meter: V/m) and magnetic field strength (units of amperes per meter: A/m). In the far-field of a transmitting antenna, where the electric field vector (E), the magnetic field vector (H), and the direction of propagation can be considered to be all mutually orthogonal ( [plane-wave conditions], these quantities are related by the following equation: 10 OET-65 FCC Guidelines Table 1 pg. 72. OSC Engineering Inc. Page 10/13

24 Limitations OSC Engineering completed this evaluation analysis based on information and data provided by the client. The data provided by the client is assumed to be accurate. Estimates of the unknown, standard, and additional transmitting sites are noted and based on FCC regulation and client requirements. These are estimated to the best of our professional knowledge. This report is completed by OSC Engineering to determine whether the wireless communications facility complies with the Federal Communications Commission (FCC) Radio Frequency (RF) Safety Guidelines. The Office of Engineering and Technology (OET-65) Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Radiation has been prepared to provide assistance in determining whether proposed or existing transmitting facilities, operations or devices comply with limits for human exposure to radiofrequency (RF) fields adopted by the Federal Communications Commission (FCC) 11. As each site is getting upgraded and changed, this report will become obsolete as this report is based on current information per the client, per the date of the report. Use of this document will not hold OSC Engineering Inc. nor it s employees liable legally or otherwise. This report shall not be used as a determination as to what is safe or unsafe on a given site. All workers or other people accessing any transmitting site should have proper EME awareness training. This includes, but is not limited to, obeying posted signage, keeping a minimum distance from antennas, watching EME awareness videos and formal classroom training. 11 OET-65 FCC Guidelines for Evaluating Exposure to RF Emissions, pg. 1 OSC Engineering Inc. Page 11/13

25 AT&T Antenna Shut-Down Protocol AT&T provides Lockout/Tagout (LOTO) procedures in Section ( ) in the ND These procedures are to be followed in the event of anyone who needs access at or in the vicinity of transmitting AT&T antennas. Contact AT&T when accessing the rooftop near the transmitting antennas. Below is information regarding when to contact an AT&T representative Maintenance work being performed near transmitting antennas Whenever anyone is working within close proximity to the transmitting antenna(s), the antenna sector, multiple sectors, or entire cell site may need to be shut down to ensure compliance with the applicable FCC MPE limit. This work may include but is not limited to structural repairs, painting or non-rf equipment services by AT&T personnel/contractors or the owner of a tower, water tank, rooftop, or other low-centerline sites. The particular method of energy control will depend on the scope of work (e.g., duration, impact to the antenna or transmission cabling, etc.) and potential for RF levels to exceed the FCC MPE limits for General Population/Uncontrolled environments AT&T Employees and Contractors AT&T employees and contractors performing work on AT&T cell sites must be trained in RF awareness and must exercise control over their exposure to ensure compliance with the FCC MPE limit for Occupational/Controlled Environments ( Occupational MPE Limit ). The rule of staying at least 3 feet from antennas is no longer always adequate to prevent exposure above the Occupational MPE Limit. That general rule was applied early in the development of cellular when omni-directional antennas were primarily used and later when wide-beamwidth antennas were used. That application was then appropriate for the Occupational exposure category. However, the current prevalence of antennas with 60- and 70- degree horizontal half-power beamwidths at urban and suburban GSM and UMTS/HSDPA sites raises some question about the continued reliability of the 3-foot rule. Antennas with low bottom-tip heights and total input powers around W can produce exposure levels exceeding the Occupational MPE Limits at 4 feet, and these levels can be augmented by emissions of co-located operators. Therefore, AT&T employees and contractors should apply the above general work procedures and use an RF personal monitor to assess exposure levels within the work vicinity Other Incidental Workers All other incidental workers who are not trained in RF safety are considered general public and subject to the FCC MPE limits for General Population/Uncontrolled Environments. In such instance, the M-RFSC (primary contact) or R-RFSC (secondary contact) must refer to the Mobility RF site survey plan to assess the potential RF exposure levels associated with the antenna system. If capable of exceeding the FCC General Population/Uncontrolled MPE limit, then local sector/site shutdown is necessary. The FE/FT must also follow the local shutdown procedure and use their RF personal monitor as a screening tool for verification, as necessary. 12 ND-00059_Rev_5.1 Lockout/Tagout (LOTO) Procedures Page 45. OSC Engineering Inc. Page 12/13

26 RECOMMENDATIONS Access Point Information 1 all roof access point(s) (to be posted) AT&T Sector A To be installed: a Information 2 Sign behind sector Exposure levels are out into the air AT&T Sector B To be installed: a Information 2 Sign behind sector Exposure levels are out into the air AT&T Sector G To be installed: a Information 2 Sign behind sector Exposure levels are out into the air If work is being performed in the vicinity of the transmitting antennas, site shut-down procedures must be followed. See page entitled AT&T Antenna Shut-down protocol for further information. OSC Engineering Inc. Page 13/13