HomeMy WebLinkAboutItem 3.5Town of Los Altos Hills April 2, 2009
Staff Report to the Planning Commission
RE: A REQUEST FOR A CONDITIONAL USE PERMIT RENEWAL AND
MODIFICATION TO REPLACE TWO 2' TALL ANTENNAS WITH 4' TALL
ANTENNAS ON AN EXISTING 70' TALL MONOPOLE.
FROM: David Keyon, Associate Planner Vk
APPROVED BY: Debbie Pedro, AICP, Planning Director.
RECOMMENDATION That the Planning Commission:
Forward a recommendation to the City Council to approve the requested modification and
renewal of the Conditional Use Permit from 5 years to 10 years in compliance with
Government Code Section 65964(b), subject to the conditions in Attachment 1.
BACKGROUND
The subject parcel is located along the west side of Purissima Road, at the Little League
Fields new Viscaino Road, AT&T Wireless is the operator of this wireless
communications facility and is requesting an extension of the Conditional Use Permit that
was initially granted in 1993 and subsequently extended in 1997 and 2004. As part of this
Use Permit renewal, the applicant is requesting to replace two existing 2' tall antennas
with two 4' tall antennas on the 70' tall monopole.
Existing equipment within the AT&T lease
area includes one equipment shed of 312
square feet and 4 panel antennas mounted
60 feet high on a 70 -foot monopole. The
original Conditions of Approval for this
permit are included in Attachment #2.
DISCUSSION
The Conditional Use Permit was originally
approved on October 20, 1993.
Landscaping and irrigation were installed,
as approved by the Town, during
construction of the facility. Today, the landscaping has matured and obscures most of the
lower two-thirds of the monopole. Maintenance visits are performed by the applicant as
needed. No complaints have been received regarding the existing communications
facility.
Item 3.5
As indicated in the attached report by Hammett & Edison, Inc., the maximum cumulative
ground level radio frequency exposure for both the AT&T site and adjacent MetroPCS
Staff Report to the Planning Commission
AT&T CUP modification & renewal
April 2, 2009
Page 2
site was equal to 0.97% of the most restrictive public limit on radio frequency exposure
(Attachment #5). Based on this information, the site complies with the FCC guidelines
limiting public exposure to radio frequency energy.
The Wireless Communications Facilities Policy requires that the wireless carrier's 5 year
Master Plan be included with all applications (Attachment #6). The 5 year Master Plan
shows existing facilities and coverage in the Los Altos Hills area.
AT&T proposes to modify the existing facility by replacing two (2) two foot tall antennas
with two (2) four foot tall antennas. The larger antennas will result in negligible
additional visual impacts from off site. To minimize any potential visual impacts of the
existing and proposed antennas, staff recommends a condition of approval requiring the
existing and new antennas to be painted to match the existing tower (condition # 6).
Pursuant to Government Code Section 65964(b), the conditions have been amended to
allow the Conditional Use Permit to be valid for 10 years (currently five (5) years). This
section states:
(b) (Unreasonably limit the duration of any permit for as wireless
telecommunications facility. Limits of less than 10 years are presumed
unreasonable absent public safety reasons or substantial land use reasons.
However, cities and counties may establish a build -out periodfor a site.
Because most of the conditions of the original Use Permit approval from 1993 (Permit
#5-93-ZP-SD-CUP) are no longer applicable, staff recommends revised conditions
consistent with recent wireless communications facility permits. Specifically, these
conditions update the time period between reviews from five to ten years per Government
Code Section 65964(b), and include operational conditions consistent with the Town's
Wireless Communications Facilities Policy (Attachment 1).
CONCLUSION
The facility is operating in compliance with the approved conditions of the Use Permit,
and the Wireless Communications Policy. The proposed antenna replacement will not
constitute a significant visual impact. The extension of the Use Permit will allow
continued operation of the facility for an additional ten (10) years at which time
subsequent Planning Commission/City Council review will be required.
ATTACHMENTS
1. Recommended amended conditions of approval
2. Conditions of approval from original Conditional Use Permit (5-93-ZP-SD-CUP)
3. Letter dated January 30, 2009 from representative of AT&T Wireless
4. Photosimulations showing existing site conditions and proposed site conditions
5. Statement of Hammett & Edison, Inc., dated February 17, 2009
6. Five year build out plan for AT&T Wireless in Los Altos Hills
7. Site plans with details of proposed modifications
-1
Staff Report to the Planning Commission
AT&T CUP modification & renewal
April 2, 2009
Page 3
ATTACHMENT
RECOMMENDED CONDMONS OF APPROVAL FOR A CONDITIONAL USE
PERMIT RENEWAL AND MODIFICATION (AT&T WIRELESS)
27400 PURISSIMA ROAD -LOS ALTOS HILLS LITTLE LEAGUE FIELDS
FILE# 26 -09 -CUP -SD
PLANNING:
1. Any changes or revisions to the telecommunications facility or its use shall require
an amendment to the applicable conditional use permit(s). Additionally, the
Planning Director may, at any time, schedule a review or revocation hearing
before the Planning Commission regarding the use permit, if any condition of
approval is not being met or the facility is being used inconsistently with the
approved use or in violation of Town development codes.
2. In accordance with the Town's Wireless Communications Policy, the applicant
shall permit the collocation of other carrier's wireless communications equipment
at this facility. If no collocation has occurred within 12 months of this approval,
the Town may initiate conditional use permit review proceedings pursuant to
condition #1. Prior to the issuance of a building permit, the applicant's structural
engineer shall certify that the wireless communication tower is structurally
capable of co -location.
3. The use permit shall expire ten (10) years from the date of approval. Renewal of
the permit must be requested in writing, with appropriate fees, prior to the
expiration date. This condition replaces condition # 10 of the original use
approval (Attachment 2).
4. Maintenance of the building, antennas, and the grounds, including weed
abatement and maintenance of weathering of the building is required to be
accomplished on an on-going basis. The Town shall make random inspections of
the property to ensure that the required maintenance is being accomplished to the
satisfaction of the Town of Los Altos Hills.
S. The applicant shall submit a signed agreement to the Town that should the use be
discontinued by the carrier, all facilities will be removed not later than ninety (90)
days after discontinuance of the use or abandonment. The agreement shall be
approved by the City Attorney, and must be signed by the applicant and submitted
to the Town prior to acceptance ofplans for building plan check.
6. The applicant must obtain a building permit for the proposed antenna
replacement. To reduce visual impacts, the 4' tall replacement antennas and all
remaining antennas must be painted to match the existing tower (dark grey/green)
prior to final inspection.
Staff Report to the Planning Conmtission
AT&T CUP modification & renewal
April 2, 2009
Page 4
7. AT&T Wireless or the operator of the site shall be responsible for repair or
repainting of the proposed facilities (equipment shed, monopole, and fences) in
case of vandalism or wear and must do so within 72 hours of notice by the Town
that a complaint has been received.
8. The applicant is required to water sweep roads if soil material is carried onto
public streets.
ENGINEERING:
9. Any, and all, changes to the proposed Site Plan shall first be approved by the
Town Engineering Department. No grading shall take place during the grading
moratorium (October 15 to April 15) except with prior approval from the City
Engineer. No grading shall take place within ten feet of any property line.
10. Any, and all, areas on the project site that have the native material disturbed shall
be protected for erosion control during the rainy season and shall be replanted
prior to final inspection.
LOSS
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r
CALIFORNIA
January 11, 2005
Marsha Converse, Property Management
AT&T Wireless Services, Inc.
651 Gateway Blvd., Suite 1300
South San Francisco, CA 94080
ICZ4Ljff1L'1ie171i
AT&T
Purissima Road, Little League Fields
Conditional Use Permit Renewal
Dear Ms. Converse:
Attachment 2
Your request for a Conditional Use Permit renewal for an existing/previously approved
wireless communications facility that was initially granted to Cellular One in 1993 and
extended in 1997 was approved at the Planning Commission meeting December 9, 2004.
Attached, please find the original conditions of approval with a change to #10, extending
the review time from three (3) years to five (5) years. -
Please contact me at (650) 941-7222 if you have any questions regarding the conditions
of approval.
Sincerely,
Carl Cahill
Planning Director
Attachment: Conditions of Approval
cc: Leslie Hopper, Project Planner
26379 Fremont Road
Los Altos Hills
California 94022
650/941-7222
Fax 650/941-3160
LOSAMS HILLS
CALIFORNIA
January 16, 1997
Ms. Elizabeth Pennington
Cellular One
651 Gateway Blvd., Suite 1500
South San Francisco, CA 94080
Re: 5-93-ZP-SD-CUP
Purissima Road
Extension of Conditional Use Permit
Dear Ms. Pennington:
your request for a Conditional Use Permit renewal was approved at the Planning Commission
meeting of January 8, 1997. The conditions for the Use Permit approved by the City Council on
October 20, 1993 apply to the renewal with a modification to condition ii10. Please note the
conditions which apply to this approval:
1. All conditions of the Sum Country Cable Conditional Use Permit approved by the
City Council on February 15, 1990, shall be conditions of this approval.
2. The site drainage mast be designed to meet the goal of reducing the rate of run off
associated with the proposed development A grading and drainage plan shall be
submitted to the City Engineer for review and approval prior to issuance of a building
permit
3. Fire retardant roofing is required for the new construction-
4.
onstruction
4 paint color shall match the color of the Sun Country building.
5. Prior to final inspection and release of final building permits a landscape planting
plan must be submitted to and approved by the Planning Commission No trees are
shown to be removed. U trees are damaged or removed it may be required to be
replaced. The replaced tree shall be equal in size to the removed or damaged tree up
to a maximum 24" box size tree The landscape plan shall take into consideration
adequate screening of the equipment shelters and the existing dish antennas and
fencing.
.6379 Fremont Road
Los Allos Hills
California 94022
415/941-7222
Fax 415/941-3160
Ms. Elizabeth Pennington
January 16,1997
Page 2
A landscape maintenance agreement shall be recorded in the office of the County
Recorder, prior to final building permit approval, agreeing to install and maintain in
good condition all required plantings. All planting required for mitigation screening
that does not establish itself within eight (8) months, shall be replaced.
A $5000.00 landscape deposit shall be posted prior to final inspection. Required
plantings shall be installed within one year, 50% of the bond shall be returned one
year after the date of the inspection to ensure adequate establishment and
maintenance. The remainder will be released one year later if the plantings remain
viable.
6. Prior to beginning any grading operation, all significant trees are to be fenced at the
drip line. The fencing shall be of a material and structure to clearly delineate the drip
line. Town staff must inspect the fencing and the trees to be fenced prior to
commencement of grading. The fence must remain throughout the course of
construction. No storage of equipment, vehicles or debris shall be allowed within the
driplines of these trees.
7. The location of the foundation is to be re -certified in writing by a registered Civil
Engineer or licensed land surveyor after the foundation has been poured as being in
the approved location and elevation established by this permit
8. The property owner shall inform the Town of any damage and shall repair any
damage caused by construction of the project to pathways, private driveways, and
public and private roadways prior to final inspection and release of occupancy permits
and shall provide the Town with photographs of the existing conditions of the
roadways and pathway prior to issuance of building permits..
9. The Pathway shall remain open at all times.
5
10. The approval of the Conditional Use Permit will be reviewed in,Yyears or with the
review of Sum Country Cable's Conditional Use Permit, whichever is sooner. The
application for extension of the use shall be re -reviewed by the Planning Commission
for determination of modifications necessary and for approval to continue the
Conditional Use Permit This permit does not authorize the applicant to intensify
authorized emissions beyond that which is specifically required for communications
in the Advanced Mobile Phone System AMPS specification and as constrained by
ANSI specification C95.1-1992. Monitoring shall ensure that emissions are safe and
remain consistent with safety standards as they address exposure to the public.
Ms Elizabeth Pennington
January 16, 1997
Page 3
11. In the event that any of the conditions of this permit are not satisfied, the Planning
Department may cause a noticed public hearing to be sent to review whether the
permit should be continued; and upon a showing of compelling public necessity
demonstrated at the noticed public hearing, the Town may add, amend, or delete
conditions and regulations contained in this permit.
12. Monitoring and reporting to the Town shall be accomplished at the installatioa of the
facility and once a year for three years. The reports shall be forwarded to the
Planning Commission for their information and review. If problems are noted, staff
or the Commission may agendize the report for review along with the Conditional
Use Permit at a public hearing. _
13. Maintenance of the building, antennas and the grounds, including weed abatement
and maintenance of weathering of the building is required to be accomplished on an
on-going basis. The Town shall make random invectionss of the property to ensure
that the required maintenance is being accomplished to the satisfaction of the Town of
Los Altos Hills.
14. Upon completion of construction, a final inspection shall be set with the Planning
_Department and Engineering Department at least two weeks prior to final building
inspection approval.
Please contact us if you have any questions.
Sincerely,
Curtis S. Williams
Planning Director
cc: Planning Commission
Chair, Environmental Design and Protection Committee
Chair, Pathways Committee
Building Official
Susan Manes, Planner
Attachment 3
RE LC®M
2620 Laguna Street, #1, San Francisco, CA 94123
VIA HAND DELIVERY
January 30, 2004
David Keyon
Los Altos Hills Planning Dept
26379 Fremont Road
Los Altos Hills, CA 94022
RE: AT&T Minor Site Modification & CUP Renewal
Address: 27400 Purissima Road
Property Owner: Town of Los Altos Mlls
APN: 182-03-022
Dear W. Keyon,
The attached application and materials are to obtain zoning approval and conditional use permit renewal
from the Town of Los Alms Hills for a minor modification of the above -referenced existing AT&T
telecommunications site.
The existing site is located on Los Altos Hills property behind some new in a park off of Purissima road.
There is a 70 -foot monopole with four 22.8 -inch (approximately 2 -feet) long antennas separated into two
sectors of two amemus each, and mourned about 60 -fed up the pole.
We propose to swap out two of the existing antennas and replace them with two 51 -inch (approximately
4 -fed) long antennas, and to affix miniature 7 -inch long remote control units (known as "REFsr) onto the
bottom of two antennas. These upgrades will enhance AT&T telecommunications service to the area and
the RETS will allow AT&T engineers to tilt the antennas remotely, fintber enhancing wireless service.
We also propose to renew the existing conditional use permit.
In support of this proposal, attached please find the following materials: a completed permit application,
10 full-sized site plans, photographic simulations, a parcel map, aproperty information detail, and the
appropriate filing fee payment
We respectfidly request approval of this relatively straightforward site upgrade and CUP renewal. Feel
free to contact me if you have my questions or if you require any additional information.
Best Regards,
REALCOM ASSOCIATES
MATTHEW S. lERGOVICH
FOR AT&T
Attachment 4
atet Los Altos Hills _Slte s CN00095 Aerial Map
27400 Pudesima Road __
128109 Los Altos Hills, CA 94022 ewaHbapn sw YuL
Al e..
f
- proposed antenna modifcaniu j,
Attachment 5
AT&T Mobility • Base Station No. CNU0095
27400 Purissima Road • Los Altos Hills, California
Statement of Hammett & Edison, Inc., Consulting Engineers
The firm of Hammett & Edison, Inc., Consulting Engineers, has been retained on behalf of AT&T
Mobility, a personal wireless telecommunications carrier, to evaluate proposed modifications to its
existing base station (Site No. CNU0095) located at 27400 Purissima Road in Los Altos Hills,
California, for compliance with appropriate guidelines limiting human exposure to radio frequency
("RF') electromagnetic fields.
Prevailing Exposure Standards
The U.S. Congress requires that the Federal Communications Commission ("FCC") evaluate its
actions for possible significant impact on the environment. la Docket 93-62, effective October 15,
1997, the FCC adopted the human exposure limits for field strength and power density recommended
in Report No. 86, "Biological Effects and Exposure Criteria for Radiofrequency Electromagnetic
Fields," published in 1986 by the Congressionally chartered National Council on Radiation Protection
and Measurements ("NCRP'). Separate limits apply for occupational and public exposure conditions,
with the latter limits generally five times more restrictive. The more recent standard, developed by the
Institute of Electrical and Electronics Engineers and approved as American National Standard
ANSYMEE C95.1-2006, "Safety Levels with Respect to Human Exposure to Radio Frequency
Electromagnetic Fields, 3 kHz to 300 GHz," includes similar exposure limits. A summary of the
FCC's exposure limits is shown in Figure 1. These limits apply for continuous exposures and are
intended to provide a prudent margin of safety for all persons, regardless of age, gender, size, or
health.
The most restrictive FCC limit for exposures of unlimited duration to radio frequency energy for
several personal wireless services are as follows:
Personal wimless Seivim
A&zxnox. Frameng
O ati nal Lit
Public inut
Broadband Radio (`BRS")
2,600 MHz
5.00 mW/cm2
1.00 mW/cm2
Advanced Wireless ("AWS')
2,100
5.00
1.00
Personal Communication ("PCS')
1,950
5.00
1.00
Cellular Telephone
870
2.90
0.58
Specialized Mobile Radio ("SMR')
855
2.85
0.57
Long Term Evolution ("LTE'
700
2.15
0.43
[most restrictive frequency range]
30-300
1.00
0.20
General Facility Requirements
Base stations typically consist of two distinct parts: the electronic transceivers (also called "radios" or
"channels') that are connected to the traditional wired telephone lines, and the passive antennas that
send the wireless signals created by the radios out to be received by individual subscriber units. The
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Page 1 of 4
AT&T Mobility • Base Station No. CN00095
27400 Purissima Road • Los Altos Hills, California
transceivers are often located at ground level and are connected to the antennas by coaxial cables
about 1 inch thick. Because of the short wavelength of the frequencies assigned by the FCC for
wireless services, the antennas require line -of -sight paths for their signals to propagate well and so are
installed at some height above ground. The antennas are designed to concentrate their energy toward
the horizon, with very little energy wasted toward the sky or the ground. Along with the low power of
such facilities, this means that it is generally not possible for exposure conditions to approach the
maximum permissible exposure limits without being physically very near the antennas.
Computer Modeling Method
The FCC provides direction for deterring compliance in its Office of Engineering and Technology
Bulletin No. 65, "Evaluating Compliance with FCC -Specified Guidelines for Human Exposure to
Radio Frequency Radiation," dated August 1997. Figure 2 attached describes the calculation
methodologies, reflecting the facts that a directional antenna's radiation pattern is not fully formed at
locations very close by (the "near -field" effect) and that at greater distances the power level from an
energy source decreases with the square of the distance from it (the 'inverse square law'j. The
conservative nature of this method for evaluating exposure conditions has been verified by numerous
field tests.
Site and Facility Description
Based upon information provided by AT&T Mobility, including zoning drawings by Streamline
Engineering and Design, Inc., dated January 15, 2009, that carrier presently has four Kathrein Model
742-226 dualband directional panel antennas mounted on a 70 -foot steel pole sited near sports fields
located at 27400 Purissima Road in Los Altos Hills, California. It is proposed to replace two of those
antennas with Kathrein Model 742-264 dualband directional panel antennas at the same locations,
mounted at an effective height of about 60 feet above ground. The four antennas would be oriented in
pairs (one of each model) toward 143°T and 334°T. The maximum effective radiated power in any
direction would be 1,910 watts, representing simultaneous operation at 1,300 watts for PCS and
610 watts for cellular service.
Also located on the pole are two "Yagi" antennas and another antenna for low-power service. Located
on another pole about 50 feet away are similar antennas for use by MetroPCS, another wireless
telecommunications carrier. For the limited purposes of this study, it is assumed that Metro has
installed Kathrein Model 742-213 directional panel PCS antennas at an effective height of about
48 feet above ground and operates at a maximum effective radiated power of 1,890 watts.
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Page 2 of 4
AT&T Mobility • Base Station No. CN00095
27400 Purissima Road • Los Altos Hills, California
Study Results
The maximum ambient RF level anywhere at ground due to the proposed AT&T operation by itself is
calculated to be 0.0086 MW/CM2, which is 0.94% of the applicable public exposure limit. The
maximum calculated cumulative level at ground for the simultaneous operation of both AT&T and
Metro is 0.97% of the public exposure limit; the maximum calculated cumulative level at the second -
floor elevation of any nearby residence' is 0.67% of the public exposure limit. It should be noted that
these results include several `worst-case" assumptions and therefore are expected to overstate actual
power density levels.
No Recommended Mitigation Measures
Due to their mounting locations, the AT&T antennas are not accessible to the general public, and so no
mitigation measures are necessary to comply with the FCC public exposure guidelines. It is presumed
that the several carriers will, as FCC licensees, take adequate steps to ensure that their employees or
contractors comply with FCC occupational exposure guidelines whenever work is required near the
antennas themselves.
Conclusion
Based on the information and analysis above, it is the undersigned's professional opinion that the
AT&T Mobility base station located at 27400 Purissima Road in Los Altos Hills, California, will
comply with the prevailing standards for limiting public exposure to radio frequency energy and,
therefore, will not for this reason cause a significant impact on the environment. The highest
calculated level in publicly accessible areas is much less than the prevailing standards allow for
exposures of unlimited duration. This finding is consistent with measurements of actual exposure
conditions taken at other operating base stations.
Located at least 275 feet away, based on aerial photogaphs from Google Maps.
HAMMErt' & EDISON, INC
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Page 3 of 4
AT&T Mobility • Base Station No. CN00095
27400 Purissima Road • Los Altos Hills, California
Authorship
The undersigned author of this statement is a qualified Professional Engineer, holding California
Registration Nos. E-13026 and M-20676, which expire on June 30, 2009. This work has been carried
out under his direction, and alt statements are true and correct of his own knowledge except, where
noted, when data has been supplied by others, which data he believes to be correct.
February 17, 2009
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Page 4 of 4
FCC Radio Frequency Protection Guide
The U.S. Congress required (1996 Telecom Act) the Federal Communications Commission ("FCC")
to adopt a nationwide human exposure standard to ensure that its licensees do not, cumulatively, have
a significant impact on the environment. The FCC adopted the limits from Report No. 86, `Biological
Effects and Exposure Criteria for Radiofrequency Electromagnetic Fields," published in 1986 by the
Congressionally chartered National Council on Radiation Protection and Measurements ("NCRP").
Separate limits apply for occupational and public exposure conditions, with the latter limits generally
five times more restrictive. The more recent standard, developed by the Institute of Electrical and
Electronics Engineers and approved as American National Standard ANSVIEEE C95.1-2006, "Safety
Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to
300 GHz," includes similar limits. These limits apply for continuous exposures from all sources and
are intended to provide a prudent margin of safety for all persons, regardless of age, gender, size, or
health.
As shown in the table and chat below, separate limits apply for occupational and public exposure
conditions, with the latter limits (in italics and/or dashed) up to five times more restrictive:
Frec uencv
Electromagnetic Fields (f is freauencv of emission in MHz)
Applicable
Electric
Magnetic
EquivelentFar-geld
Range
Field Strengih
Field S6rngth
Power Density
(MHz)
(VIM)
(Alm)
(mW/cm')
0.3— 1.34
614 614
1.63 1.63
100 100
1.34-3.0
614 813.81f
1.63 2191f
100 180/}
3.0— 30
1842/f 823.8/f
4.89/f 1191f
900/fr 1801f
30— 300
61.4 17.5
0.163 0.0729
1.0 0.2
300— 1,500
3.54* 1.59�(f
*/106 -&238
f/300 0500
1,500— 100,000
137 61.4
0.364 0.163
5.0 1.0
1000
Occupational Exposure
100
!
PCS
FM Cell
0.1
Public F,x sure
0.1 1 10 100 103 10"
105
Frequency (Wh)
Higher levels are allowed for short periods of time, such that total exposure levels averaged over six or
thirty minutes, for occupational or public settings, respectively, do not exceed the limits, and higher
levels also are allowed for exposures to small areas, such that the spatially averaged levels do not
exceed the limits. However, neither of these allowances is incorporated in the conservative calculation
formulas in the FCC Office of Engineering and Technology Bulletin No. 65 (August 1997) for
projecting field levels. Hammett & Edison has built those formulas into a proprietary program that
calculates, at each location on an arbitrary rectangular grid, the total expected power density from any
number of individual radio sources. The program allows for the description of buildings and uneven
terrain, if required to obtain more accurate projections.
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Figure 1
RFR.CALCTM Calculation Methodology
Assessment by Calculation of Compliance with FCC Exposure Guidelines
The U.S. Congress required (1996 Telecom Act) the Federal Communications Commission ("FCC's to
adopt a nationwide human exposure standard to ensure that its hoensees do not, cumulatively, have a
significant impact on the environment. The maximum permissible exposure limits adopted by the FCC
(see Figure 1) apply for continuous exposures from all sources and are intended to provide a prudent
margin of safety for all persons, regardless of age, gender, size, or health. Higher levels are allowed for
short periods of time, such that total exposure levels averaged over six or thirty minutes, for
occupational or public settings, respectively, do not exceed the limits.
Near Field.
Prediction methods have been developed for the near field zone of panel (directional) and whip
(omnidirectional) antennas, typical at wireless telecommunications base stations, as well as disb
(aperture) antennas, typically used for microwave links. The antenna patterns are not fully formed in
the near field at these antennas, and the FCC Office of Engineering and Technology Bulletin No. 65
(August 1997) gives suitable formulas for calculating power density within such zones.
For a panel or whip antenna, power density S = ISO
x 0.1 x P' in mW/CM2
w xxD xh'
and for anenure ant 0.1 x 16 x rl x P. mW z
ap eons, maximum power density S = x hz in /an ,
where OBw
= half -power beamwidth of the antenna, in degrees, and
Poet
= net power input to the antenna, in watts,
D
= distance from antenna, in meters,
h
= aperture height of the antenna, in meters, and
n
= aperture efficiency (unittess, typically 0.5-0.8).
The factor of 0.1 in the numerators converts to the desired units of power density.
Far Field.
OET-65 gives this formula for calculating power density in the far field of an individual RF source:
power density S = 2.56 x 1.64 x 100 x RFF2 x ERP in MW/CM2
4xnxDZ
where ERP = total ERP (all polarizations), in kilowatts,
RFF = relative field factor at the direction to the actual point of calculation, and
D = distance from the center of radiation to the point of calculation, in meters.
The factor of 256 accounts for the increase in power density due to ground reflection, assuming a
reflection coefficient of 1.6 (1.6 x 1.6 = 2.56). The factor of 1.64 is the gain of a half -wave dipole
relative to an isotropic radiator The factor of 100 in the numerator converts to the desired units of
power density. This formula has been built into a proprietary program that calculates, at each location
on an arbitrary rectangular grid, the total expected power density from any number of individual
radiation sources. The program also allows for the description of uneven terrain in the vicinity, to
obtain more accurate projections.
HAMM= & EDISON, INC
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Attachment 6
5 -YEAR FACILITIES
Address
PLAN
city
- CURRENT
Semah Rina Name
SITES (MARCH
AT6TSearoh
Rino 91 MID 0
2009)
Latlfude
Lo Bede
27400 PA%ima Road
Los Alma Hills
Loa Mos Hills
CN00095/13246
3]37552
-12214843
13618 Pae Mill Road
Loa Mos Hills
HmdW PmmrtV
CN3256/47703
37.37431
-122.17158
2614D D.1 W
LosA s Hils
EI Menta Ave Wes[
74091
37.38553
-122.135
12883 Ls Crest Drive
Los Alto. Hos
L"Nk Lwiuo F7 La Cres
74092
37.38272
-12214861
26379 We F..om BW
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37.38432
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852311
37.3871
-12215303
123455. EI manta Road
Las Alto. Kd.
Fo*d Cd
ONUM79113283
37.3636
-122.1257
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