CHATHAM COUNTY EMERGENCY SERVICES
Radio Communications Tower for Backup EOC
Bid Specification
Version 2.0
March 15, 2012
Contents
1.
Page
Radio Communications Tower: Introduction_____________________________________ 1
1.1.
2.
Applicable Standards _____________________________________________________________1
Radio Communications Tower Specifications ____________________________________ 2
2.1.
General Tower Specifications ______________________________________________________2
2.2.
Transmission Lines ______________________________________________________________3
2.3.
Antennas _______________________________________________________________________4
2.3.1
2.3.2
2.3.3
2.3.4
2.4.
5
5
5
5
Grounding, Surge Suppression, and Entrance Panels __________________________________5
2.4.1
2.4.2
2.4.3
2.4.4
2.4.5
2.4.6
3.
VHF Directional Antennas_____________________________________________________________
UHF Directional Antennas _____________________________________________________________
800 MHz Directional Antennas _________________________________________________________
Side Arm Brackets ___________________________________________________________________
General Grounding Conductors Specifications ______________________________________________
Tower Ground Bus Bars _______________________________________________________________
Feedline Entrance Panel _______________________________________________________________
Antenna Lightning Surge Protector_______________________________________________________
Ice Bridge __________________________________________________________________________
Tower Signage ______________________________________________________________________
5
6
6
7
8
8
Radio Communications Tower Erection, Installation, and Other Services _____________ 9
3.1.
General Installation Standards _____________________________________________________9
3.1.1
3.1.2
3.1.3
Implementation Schedule ______________________________________________________________ 9
Installation Site ______________________________________________________________________ 9
FCC Tower Registration ______________________________________________________________ 10
3.2.
Engineering ____________________________________________________________________10
3.3.
Project Management ____________________________________________________________11
3.4.
Shipping and Delivery ___________________________________________________________12
3.5.
Tower Erection _________________________________________________________________12
3.5.1
3.6.
Tower Loading and Antenna Systems Relocation ____________________________________14
3.6.1
3.6.2
3.7.
Painting and Finishing _______________________________________________________________ 13
New Antennas and Feedlines __________________________________________________________ 14
Antenna System Testing ______________________________________________________________ 15
Grounding Methods _____________________________________________________________16
3.7.1
3.7.2
3.7.3
Ice Bridge _________________________________________________________________________ 18
Entrance Panel _____________________________________________________________________ 19
Grounding Testing __________________________________________________________________ 19
3.8.
Safety _________________________________________________________________________19
3.9.
Contractor Responsibilities _______________________________________________________20
3.9.1
3.10.
Warranties and Service Agreements _____________________________________________________ 20
Chatham County EM's Responsibilities ___________________________________________20
i
Contents
Appendices
Appendix A: Pictures - Chatham County's new backup EOC
Appendix B: Picture - Google Earth of new backup EOC
Appendix C: Existing tower at Chatham County's Main 911 Center
ii
Page
1.
Radio Communications Tower: Introduction
Chatham County Emergency Managerment submits this Request for Proposals
(“RFP”) for a radio communications tower (“TOWER”) which is intended to support
two-way radio communications antenna systems for Chatham County First
Responders. This TOWER will be purchased and maintained by Chatham County
Emergency Management (CCEM). This document describes specifications for
materials to provide a complete functional support structure.
The TOWER will be a self-supporting type communications tower installed at
Chatham County Emergency Management’s Backup EOC facility near Siler City,
North Carolina.. The TOWER will support all antenna systems as described herein,
and the proposer’s pricing shall include engineering, (to include if required by
County Ordinances) soil bore testing, tower loading design, final site design along
with materials list, shipping and labor costs.
1.1.
Applicable Standards
Issues of the following documents, in effect at the time of solicitation for bids, form a
part of this specification. In the event of conflict between this specification and the
codes, standards, and specifications below, the most stringent and/or current
requirement shall govern.
American Institute of Steel Construction (AISC): Manual of Steel
Construction.
Electronics Industries Association (EIA) Standard TIA-222-F:
Structural Standards for Antenna Towers and Antenna Supporting
Structures.
Electronics Industries Association (EIA) Standard TIA-607:
Commercial Building Grounding and Bonding Requirements for
Telecommunications.
American Welding Society (AWS): Structural Welding Code.
American Institute of Steel Construction (AISC): Specification for
Structural Joints using ASTM A325 or A490 Bolts.
American Concrete Institute ACI 318: Building Code Requirement
for Reinforced Concrete.
Concrete Reinforcing Steel Institute (CRSI): Manual of Standard
Practice.
American Society for Testing and Materials (ASTM)
FAA Advisory Circular #AC 70/7460: Obstruction Marking and
Lighting.
FCC: Federal Communications Commission Rules and Regulations
1
General Tower Specifications
2.
Radio Communications Tower Specifications
This section describes the specifications of this RFP for the tower components,
antenna systems, and hardware.
2.1.
General Tower Specifications
The proposed structure shall be a one hundred foot (100’) self-supporting triangular
lattice-type TOWER, similar to Valmont model U-3.5, constructed of solid steel
members, with hot-dipped galvanized sections and components. TOWER sections
shall use solid rod construction, with angular support bracing. The maximum
allowable distance between the legs at the base of the TOWER will need to be
determined based on tower site location and tower loading..
The TOWER shall be designed to support the following antenna loading in Chart 5
below:
Chart 5 – Antenna Installation Locations
Frequency
(MHz)
Antenna Type
Transmission
Line Size
Height
(ft)
Azimuth
Tower Leg
North
VHF
ANT150Y10H
½”
100’
56°
VHF
ANT150Y10H
VHF
ANT150Y10H
UHF
DB499
UHF
DB499
North
North
South
South
South
South
South
South
South
West
West
West
West
West
North
North
2
VHF
VHF
VHF
½”
½”
½”
ANT150Y10H
½”
ANT150Y10H
½”
P1544 SERIES
VHF
P1544 SERIES
UHF
DB499
UHF
DB499
VHF
P1544 SERIES
VHF
½”
ANT150Y10H
VHF
VHF
½”
½”
½”
½”
½”
½”
P1544 SERIES
½”
P1544 SERIES
½”
VHF
P1544 SERIES
UHF
DB499
½”
½”
95’
90’
100’
90’
85’
75’
70’
60’
55’
80’
70’
60’
50’
45’
40’
35’
56°
56°
85°
85°
85°
85°
85°
85°
85°
190°
190°
190°
190°
190°
74°
74°
Chatham County EM EOC Backup Communications Tower
North
South
LOW
BAND
DB201
VHF
P1544 Series
½”
½”
25’
30’
74°
103°
The TOWER will be designed to support the above loading under a wind load of
75MPH basic wind speed, per EIA/TIA RS222-F, and shall conform to the 2000
International Building Code (IBC) for 90 MPH 3-second gust, and Importance Factor
1.0. An additional load factor of ½” radial ice shall be supported with a maximum of
25% load reduction.
This RFP specifies no twist or sway limitations for the TOWER.
The above loading factors allow for future growth. The actual initial loading of the
tower is discussed in detail in the Tower Loading section.
The TOWER shall include all anchor steel with a full-sized template to
simultaneously position anchor bolts for all legs. Horizontal members for climbing
shall be supplied and installed. All tower assembly hardware shall be included. The
successful tower vendor shall provide bolts, nuts and lock washers in a quantity in
excess of the actual bolt count for each size required, per the following chart:
Bolt
Count
0-200
200-500
500-1000
1000 and over
Percentage
Excess
5%
4%
3%
2%
Minimum
Excess
3
10
20
30
Grounding materials shall be supplied with the TOWER which comply with the
specifications shown in the section “Grounding, Surge Suppression, and Entrance
Panels”, p. 5, as required to meet the implementation standards cited in the section
“Grounding Methods”, p. Grounding Methods16, as well as described in other
sections of this document, and shall be compliant with EIA and other industry
standards. A lightning rod shall be provided and cannot exceed an overall height of
120’
A vertical support cable ladder is recommended, but optional (include cost of vertical
cable ladder). Snap-in type transmission line hanger brackets will be furnished and
installed every 2½ ft (vertical spacing) either with the above cable ladder or angle
brackets to support all cables to be installed
The TOWER shall include an approved (ANSI A10.14-1991, ANSI Z359, and CSA
Z259) cable-type safety climb system and harness.
2.2.
Transmission Lines
New transmission lines will be provided by CCEM’s radio service provider for each
antenna to be mounted to the proposed TOWER. The antenna transmission lines
3
Antennas
supplied (including jumpers) shall be of a length sufficient to reach from the antenna
connector to the radio station.
Transmission lines for antennas to be mounted shall meet the medium loss
transmission line requirements as shown in Chart 2, below.
Chart 2 – Medium-Loss Transmission Line Specifications
Item
Specification
Outer Conductor Diameter
1/2 Inch (0.63 inch nominal diameter, with jacket)
Minimum Bending Radius
5 Inches
Outer Conductor (Type)
Copper
Inner Conductor (Type)
Copper Clad Aluminum
Jacket Material
Polyethylene
Attenuation Maximum
1.5 dB per hundred foot at 400 MHz
Each feedline and its associated jumpers shall be equipped with connectors
compatible with the antenna, station, and intermediate connections (e.g., primary
transmission line to jumper, surge suppressor) with which it is used.
A jumper shall be provided between each transmission line and its associated
antenna. Jumpers shall be constructed of ½” super flexible transmission lines.
Antenna jumpers shall not exceed ten feet (10’) in length.
Up to four (4) two-hole grounding straps will be provided for each transmission line,
as required in the section titled “Grounding, Surge Suppression, and Entrance
Panels”, p. 5. Grounding straps provided shall be those recommended by the
manufacturer of the transmission lines.
Snap-in hanger kits, as recommended by the transmission line manufacturer, will be
provided to allow support for each transmission line every 2½ feet across the
waveguide ice bridge and up the tower cable ladder.
Ancillary components (e.g., hoist grips), hardware, and cabling will be supplied as
needed.
2.3.
Antennas
Antennas will be provide by CCEM’s radio service provider for the proposed
TOWER. The tpyes of antennas will be UHF, VHF and 800 MHz directional “yagi”style antennas.
Each antenna will be configured and tuned for the correct frequency range to operate
properly with the station to which it is attached. Antennas will include appropriate
mounting hardware.
4
Chatham County EM EOC Backup Communications Tower
2.3.1
VHF Directional Transmit Antennas
Directional antennas in the VHF band shall be 10dB gain dipole models, equivalent
to model ANT150Y10H or P1544 Series.
2.3.2
UHF Directional Antennas
Directional antennas in the UHF band shall be 10 dB gain yagi style, equivalent to
Decibel Products model DB436 or PLC456 Series
2.3.3
800 MHz Directional Antennas
Directional antennas in the 800 MHz band shall be 10dB gain yagi style , equivalent
to Decibel Products model DB499.
2.3.4
Side Arm Brackets
If required, due to spacing of directional antennas, new side arm brackets maybe
supplied by the tower manufacturer and shall be provided in the proposal for any
directional antenna mounted on the tower to meet designed tower height locations.
The side arm mounts proposed shall be of the angular or tubular type and shall be
galvanized inside and out. The side arm shall hold the antennas at a distance of three
(3) feet from the tower, and shall be plumb in directions of designed azimuth.
2.4.
Grounding, Surge Suppression, and Entrance Panels
The following sections describe grounding and surge suppression systems provided
with the TOWER.
2.4.1
General Grounding Conductors Specifications
Grounding conductors are the conductors used to connect equipment or the grounded
circuit of a wiring system to a grounding electrode or grounding electrode system.
These conductors may be the wires that connect grounding electrodes together, form
buried ground rings, and connect objects to the grounding electrode system. (See
NFPA 70, Article 100 for more information.)
All external grounding conductors shall be bare tinned solid or stranded 35mm2 (#2
AWG) or larger copper wire and shall meet the size requirements of NFPA 70,
Article 250-66. Solid wire shall be required below grade to prolong longevity. Solid
straps or bars may be used as long as the cross-sectional area equals or exceeds that
of the specified grounding conductor.
5
Grounding, Surge Suppression, and Entrance Panels
2.4.2
Tower Ground Bus Bars
One (1) single-point Tower Ground Bus bar (“TGB”), similar to MTS Wireless GB0214-IT, proposer shall provide for mounting to the tower at the following point:
At the base of the tower, no more than ten feet (10’) above ground;
•
The purpose of the TGB is to provide a convenient termination point for multiple
transmission line grounding conductors. The tower ground bus bar should be an
integral part of the tower construction or vertical transmission line cable ladder
assembly. The TGB shall be constructed and initially sized in accordance with the
specifications shown in Chart 3, below, ensuring the ground bus bar is large enough
to accommodate all present and future coaxial cable connections as described
elsewhere in this document, and connection to the grounding electrode system. The
tower ground bus bar shall be physically and electrically connected to the tower.
Chart 3 – Tower Ground Bar (TGB) Specifications
Item
Specification
Material
Bare, solid Alloy 110 (99.9%) copper bus bar or plate of
one piece construction. May be electro tin-plated.
Minimum Width
5 cm (2 in.)
Minimum Length
35.6 cm (14 in.)
Thickness
0.635 cm (1/4 in.)
Mounting brackets
Stainless steel
Conductor mounting holes
Number dependent on number of conductors to be attached,
including present and future plans. Holes to be 1 cm (7/16
in.) minimum on 1.9 cm (3/4 in.) centers to permit the
convenient use of two-hole lugs.
Acceptable methods of attachment
of grounding electrode conductor
Exothermic welding
Irreversible crimp connection
Other suitable irreversible crimp connection process
2.4.3
Feedline Entrance Panel
An entry port specifically designed for cabling, functionally similar to MTS Wireless
model EP1297 or Microflect model B1336, shall be provided by the proposer. The
entry port shall be a weatherproof, commercially made port assembly specifically
designed for this purpose. This assembly shall consist of a transmission line entry
plate, boot assemblies, and appropriate grounding materials. The entry plate shall
supply enough ports to accommodate the number of transmission lines initially
installed on the TOWER and shall allow for adequate expansion for future lines.
The entry plate shall have either 10 cm or 12.7 cm (4 or 5 in.) diameter openings.
The plate shall be made of copper or painted aluminum. A single entry plate mounted
on the outside wall or bulkhead is sufficient.
6
Chatham County EM EOC Backup Communications Tower
Boots shall be supplied for all ports of the entry plate. Boots appropriately sized and
configured to match the transmission lines to be installed shall be provided. Multiple
cables per entry port boot is recommended. All unused ports shall be covered with
blank caps supplied by the port manufacturer, or shall use appropriately sized
cushion plugs into standard inserts.
A Single-Point External Ground Bus bar (“EGB”) shall be provided to connect
feedline ground-kits and shall be mounted on the outside wall below the feedline
entrance panel. The purpose of the EGB is to provide a convenient termination point
for multiple grounding conductors. . The EGB shall be constructed and initially
sized in accordance with the specifications shown in Chart 4, below, ensuring the
ground bus bar is large enough to accommodate present and future coaxial cable
connections as described elsewhere in this document, and connection to the
grounding electrode system.
Chart 4 – External Ground Bar (EGB) Specifications
Item
Specification
Material
Bare, solid Alloy 110 (99.9%) copper bus bar or plate of
one piece construction. May be electro tin-plated.
Minimum Width
5 cm (2 in.)
Minimum Length
30.5 cm (12 in.)
Thickness
0.635 cm (1/4 in.)
Mounting brackets
Stainless steel
Insulators
polyester fiberglass, 15 kV minimum dielectric strength
flame resistant per UL 94 VO classification
Conductor mounting holes
Number dependent on number of conductors to be attached,
including present and future plans. Holes to be 1 cm (7/16
in.) minimum on 1.9 cm (3/4 in.) centers to permit the
convenient use of two-hole lugs.
Acceptable methods of attachment
of grounding electrode conductor
Exothermic welding
Irreversible crimp connection
other suitable irreversible crimp connection process
2.4.4
Antenna Lightning Surge Protector
An inline antenna lightning surge protector will be provided for each RF transmission
line. Surge protectors shall be similar to Polyphaser models IS-B50LN-C1-MA
(VHF) or IS-B50HN-C1-MA (UHF).
The connectors on the surge protector will mate with the connectors on the
transmission line and those supplied for the equipment jumper, and connector
genders shall be configured such that the jumper may be mated directly with the
transmission line without an intermediate jumper or adapter should a need arise to
remove the surge protector.
7
Grounding, Surge Suppression, and Entrance Panels
2.4.5
Ice Bridge
A waveguide ice bridge, if ample space based on tower location design, the proposer
shall provide to be installed between the tower and the Transmission Line Service
Entrance on the building wall. The ice bridge shall be engineered to provide
horizontal support of waveguide and coaxial feedlines.
The waveguide ice bridge shall typically be a maximum 24 inches wide and shall be
suitably attached to, and supported only by its support pipes independent of the radio
shelter and tower. The height of the waveguide ice bridge shall be determined upon
final location of tower with proximity to building and shall be taller than the top of
the building transmission line entrance panel, such that transmission lines from the
TOWER will either be level with their appropriate entry port, or will approach the
entry port from above.
The design and construction of the ice bridge shall be include sufficient strength to
support one 250 pound person, and so that no damage is sustained by a falling one
pound block of ice from the top of the TOWER.
The horizontal support of the feedlines under the waveguide bridge shall be via a two
tier galvanized angles, with combination ¾ inch O.D. and 7/16 inch drilled holes for
the securement of hanger kits, with each end supported vertically from the overhead
waveguide bridge channel via 3/8 inch galvanized threaded rods. These hanger kit
support frames shall be spaced horizontally every 2½ feet under the waveguide
bridge. Ice bridge hanger brackets shall support all proposed transmission lines.
The waveguide bridge support pipes shall be grounded via Cadwelded #2 bare solid
or #2 bare stranded copper ground cables to the buried ground system.
2.4.6
Tower Signage
Warning signs shall be mounted on the sideof the tower. The signs shall display the
warning "RF/Microwave Energy Controlled Area”, shall comply with ANSI C95.21982 Ref. 3, Z35.1-1972, and Z53.1-1979 and shall warn of high RF fields. The signs
shall be impervious to weathering, and shall be mounted to avoid ease of removal by
vandals.
8
General Installation Standards
3.
Radio Communications Tower Erection, Installation, and
Other Services
The proposer’s plan and commitment to meet the requirements of the following
services shall be described in detail in the proposal. Unless a specific service is
excepted in their proposal, all stated services shall be provided in their entirety by the
successful contractor. The requirements listed in this section apply to all equipment
regardless of application or location unless otherwise excepted.
3.1.
General Installation Standards
Each proposer must provide stamped engineering tower drawings and complete
tower erection, transmission line and antenna installation costs for the proposed
structure. The cost will include soil bore sampling, environmental studies and all
required documentation for County or City approval of tower. System
implementation shall be considered “turn-key,” meaning that the contractor shall
consider all necessary equipment, materials, labor, and technical planning necessary
to make the proposed TOWER completely functional.
The responsibility for the successful, safe and proper implementation of the proposed
TOWER system shall lie solely with the proposer. The proposed system shall be
supervised, coordinated, erected and installed by experienced and knowledgeable
personnel. Erection and installations shall be done consistent with “good”
engineering practices, according to industry standards, and all work areas shall be
maintained in a neat, clean, and orderly manner at the end of each workday.
Subcontractors may be used for specific portions of the project. The intended use of
such subcontractors shall be stated in the proposal and priced separately. CCEM
may choose to provide these services or to subcontract them independently, in whole
or in part
3.1.1
Implementation Schedule
The successful vendor shall submit to CCEM, within 30 days of contract award, a
project timetable including the delivery schedule and installation of all equipment
from award of contract to final acceptance. This project schedule shall detail all
steps in the engeineering, permitting, County or City ordinance compliancy, ordering,
delivery, erection and acceptance of the proposed system. The project schedule shall
take into account the impact of other events and construction that must be completed
by CCEM, its contractors, and its agents prior to successful implementation of each
step.
The proposal shall include a preliminary schedule, in Gantt chart format, of a typical
implementation of the proposed system.
3.1.2
Installation Site
All proposers shall submit a statement that they have visited the planned tower site
and have made an inspection of the site. Each proposing vendor is responsible for
obtaining necessary information about the site to allow that site to be used as
proposed.
9
Engineering
CCEM and its contracted project manager will answer questions developed from the
site inspections. The selected vendor will not be allowed to petition for any
additional monies because of lack of information about the site that should have
been known or learned from a site visit, or freely available through other means.
Any changes, improvements, or modifications to any existing proposed site which are
required to make the proposed system operational, or to meet the requirements or
specifications of this RFP, shall be described in detail in the vendor’s proposal.
Any action required by Chatham County because of a proposed modification or
change shall be clearly stated in the vendor’s proposal. Each proposing vendor shall
state in their proposal that these changes or modifications are required for the proper
operation and/or installation of the proposed system.
The selected vendor will be required to sign a document stating that any changes or
modifications the selected vendor makes to any site will not detrimentally affect the
physical integrity of that site or any structure at that site.
3.1.3
FCC Tower Registration
If appilicable, the contractor shall assist Chatham County by providing information
relevant to registration of the tower site under the FCC Antenna Site Registration
rules, CFR 47 Part 17.7.
3.2.
Engineering
The proposal shall include engineered stamped drawings of the proposed TOWER.
These drawings shall show details of the tower components, construction, and
foundation, per EIA/TIA RS222-F (“Structural Standards for Steel Antenna Towers
and Antenna Supporting Structures”).
Upon award to a successful contractor, the contractor shall provide engineering
services to ensure and verify the structural stability of the proposed TOWER. A soil
survey shall be conducted per EIA/TIA RS222-F by a licensed geotechnical engineer.
A report generated from this survey shall be submitted to CCEM.
Based on the results of the survey, the contractor shall create, or shall contract with
an engineering firm to have created, a suitable tower foundation design generated by
a professional engineer with experience in communications tower design who is
registered in North Carolina. The design shall include a complete and orderly
summary of the tower stress analysis showing loading considerations, tower base
reactions, member sizes, allowable stresses and maximum computed forces in tower
members. The contractor shall provide to CCEM engineered drawings of the
foundation and tower sealed by a professional engineer registered in North Carolina.
Installation drawings shall be provided by the tower designer, showing the location of
all initial antennas and their mounting locations. The placement of antennas is not to
be left to the judgment of installation crews.
10
Chatham County EM EOC Backup Communications Tower
3.3.
Project Management
An on-site, in-state Project Manager shall be assigned to facilitate and oversee the
completion of this project, and shall be the sole vendor contact for CCEM for all
items concerning this project. The Project Manager shall be a direct employee of the
selected vendor, and not a subcontractor. The Project Manager's responsibilities
shall include but not be limited to the inventory all equipment, determination of site
requirements, facilitation of all site and equipment installations, coordination with
CCEM personnel on any areas that are in question during system installation,
scheduling, subcontracting ,generation and distribution of progress reports
throughout the tower implementation period.
Vendors shall certify in the proposal that the assigned Project Manager has the power
to make significant decisions relevant to the project, and that the Project Manager has
direct access to the vendor’s top management for resolving problems beyond the
Project Manager's direct authority.
The Project Manager must be on site during critical points of the installation of this
system. The Project Manager will perform the following tasks as a minimum to meet
the requirements of this specification:
•
Review all bid specifications and familiarize himself/herself with the
requirements of this RFP.
•
Will be the sole contact for Chatham County EM, after the award of the
contract to the vendor.
•
Schedule the delivery, and keep CCEM informed at all times, regarding the
delivery schedule of proposed tower.
•
Be responsible for coordinating any required engineering which needs to be
completed.
•
Will perform all site visitations with CCEM representative as well as any
installation subcontractors.
•
Coordinate all site preparation required for the successful installation of this
tower.
•
Perform all installation scheduling with all required plant or subcontractor
personnel. S/he will further provide to CCEM within 30 days of contract’s
award a Gantt chart for the scheduled installation of this tower.
•
Will have full authority and perform all subcontracting functions required to
complete this installation within the guidelines of this specification.
•
Will provide to CCEM all manufacturers documentation, engineering
documents, wiring diagrams and as-built documentation.
•
Will be on site during the installation of the fixed equipment and provide
any information and assistance as required by the installation personnel
and/or CCEM
11
Tower Erection
3.4.
•
Will inventory all equipment for this tower, with CCEM representatives
present.
•
Will be available to CCEM until final acceptance of the tower. The
resolution of all punch list items is the sole responsibility of the Project
Manger prior to final acceptance of the tower.
•
Aid CCEM in performing an audit of the tower installation to ensure that the
installation has been installed to the highest quality standards for items such
as system grounding.
•
Will have meetings, depending on the status and progress of the project,
during the tower installation, to keep CCEM up to date on the status of the
installation.
Shipping and Delivery
The proposal pricing shall include all shipping costs to deliver the materials to the
nearest access point to the site via flat-bed tractor trailer, including unloading.
Pricing shall include all labor to move the materials from the unloading site to the
actual tower site, if different. If the implementation schedule requires that anchor
steel is shipped prior to the remainder of the tower, then the proposer shall include
that caveat in the proposal, and shall cover all costs associated with the extra
shipping, unloading, etc.
Two complete sets of tower assembly drawings (prints) and One soft copy shall be
provided and shipped with the tower parts. Complete packing slips will be provided
for the tower. Two prints each of the installation drawings will be placed in a
moisture-proof bag with the material and hardware packing slips and secured to the
tower material or crating.
All materials shall be properly marked and match-marked for field assembly. The
delivery sequence of all materials shall be arranged in a manner to expedite erection
and minimize field handling of materials.
Upon receipt of each shipment of materials, the contractor’s project manager shall
inventory all equipment, and shall provide a signed copy of the inventory with serial
numbers, where appropriate, along with copies of all shipping documents to CCEM.
3.5.
Tower Erection
The construction of the tower foundation and the erection of tower structural steel
shall be performed by personnel experienced and knowledgeable concerning
communications towers, and shall be in accordance with the applicable provisions of
the EIA/TIA RS222-F standard.
All construction practices shall be performed in a professional and safe manner,
compliant with federal, state, and local codes and consistent with applicable industry
standards. Appropriate building permits shall be obtained by the contractor prior to
initiating any site construction.
12
Chatham County EM EOC Backup Communications Tower
No field welding shall be permitted unless specifically approved in writing by
CCEM.
CCEM shall be notified five (5) working days prior to completion of excavation,
forming, and setting of foundation reinforcing steel so that a CCEM representative
can, at his/her option, observe work prior to pouring concrete.
After the erection of the steel tower is complete, the contractor shall verify that the
tower tolerances are within manufacturer-required limits.
The successful contractor shall provide an independent engineer registered in North
Carolina to inspect and approve all work associated with the construction of the
towers.
The tower shall be grounded continuously during the erection phase.
3.5.1
Painting and Finishing
All steel members and fasteners shall be galvanized (zinc coated). Under no
circumstances shall any coating on any metal member or fastener be cathodic relative
to the base material.
After the tower is erected, “Devcon Z Cold Galvanizing Compound”, or equivalent
zinc rich paint, or approved equal, shall be used to touch up damaged galvanization
and over Cadwelded ground cable connections to the tower members. Touch up may
be done by either a spray or brush application. Field painting shall be limited to
touch-up of paint damaged during transportation and erection.
If required by tower manufacturer, immediately after tower erection and leveling nut
adjustment Five Star Special Grout 100 or approved equal shall be mixed per
manufacturer’s recommendations and placed in between the bottom of each tower
base plate and the top of the finished tower leg concrete foundation
No Federal Aviation Administration (“FAA”) requirements for lighting or special
painting per FAA specification AC70/7460 required for this TOWER
3.6.
Tower Loading
After the tower and ice bridge are constructed, and all grounding facilities are
finalized and tested, the contractor will install the provided new antennas and
transmission lines on the tower.
3.6.1
New Antennas and Feedlines
New antennas will be provided and installed at locations per Chart 5, below. After
contractor awarding, proposer will work with CCEM and it’s radio service provider
to determine the final layout based on tower orientation, frequencies and azimuths for
the directional antennas below.
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Tower Loading
Chart 5 – Antenna Installation Locations
Frequency
(MHz)
Antenna Type
Transmission
Line Size
Height
(ft)
Azimuth
Tower Leg
North
VHF
ANT150Y10H
½”
100’
56°
VHF
ANT150Y10H
VHF
ANT150Y10H
UHF
DB499
UHF
DB499
North
North
South
South
South
South
South
South
South
West
West
West
West
West
North
North
North
South
VHF
VHF
VHF
½”
½”
½”
ANT150Y10H
½”
ANT150Y10H
½”
P1544 SERIES
VHF
P1544 SERIES
UHF
DB499
UHF
DB499
VHF
P1544 SERIES
VHF
½”
ANT150Y10H
VHF
VHF
½”
½”
½”
½”
½”
½”
P1544 SERIES
½”
P1544 SERIES
½”
VHF
P1544 SERIES
UHF
DB499
LOW
BAND
DB201
VHF
P1544 Series
½”
½”
½”
½”
95’
90’
100’
90’
85’
75’
70’
60’
55’
80’
70’
60’
50’
45’
40’
35’
25’
30’
56°
56°
85°
85°
85°
85°
85°
85°
85°
190°
190°
190°
190°
190°
74°
74°
74°
103°
Contractor shall install three-foot side-arm mounts on the tower, if needed for proper
mounting and spacing of antennas. Antennas shall be mounted to the side-arm
brackets per the manufacturers instructions. The pipe mount, if used, shall be plumb
in each axis.
Transmission lines shall be raised to within eight feet (8’) or less of the antenna using
hoisting grips as provided by the transmission line manufacturer, and shall be secured
to the tower every 2½ feet (vertical spacing) using snap-in style hangers fastened into
the hanger brackets on the tower.
Connectors shall be installed on each end of the transmission line. A jumper shall be
installed and connected between the end of the transmission line and the antenna. All
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Chatham County EM EOC Backup Communications Tower
connections shall be sealed against the ingress of moisture using transmission line
manufacturer-supplied or approved cold-shrink weatherproofing products, installed
according to manufacturer’s instructions and industry standards.
Ground straps shall be applied to the transmission lines at the top of the transmission
line nearest the antenna and at the tower ground bar located where the transmission
line transfers to the ice bridge.
The transmission line shall be secured to the hanger brackets on the ice bridge every
2½ feet using snap-in style hangers fastened into the ice bridge hanger brackets. The
transmission line shall be inserted no more than two feet (2’) into the building
through the entrance panels using a properly-sized boot. Strain relief, in the form of
a drip loop, shall be provided between the tower and the ice bridge, and between the
ice bridge and the entrance panel.
Each feedline shall terminate into a lightning surge protector. The transmission line
shall connect directly into the surge protector, without an intermediate jumper.
All feedlines shall be labeled at the antenna, top side jumper to transmission line,
bottom of tower at tower ground bar, at entry port externally and at the surge
suppressor with a durable indelible markings, i.e, colored electrical tape. A list of
color codes shall be posted at the internal entry port, plus a copy given to CCEM for
their records.
Contractor shall supply installation documation to include at the minium,
photographs of the completed tower, every antenna at the proposed antennas heights,
transmission line from antenna, hoisting grip, ground kits, transmission line down
tower, lower ground kits and tower ground bar, transision from tower to transmission
entry port, transmission line entry port(external and internal), tower grounding and
tower foundation.
3.6.2
Antenna System Testing
Upon completion of all transmission line and antenna installations, and prior to
connection to radio station equipment, the contractor shall test each transmission
line/antenna combination across the full frequency band for which the antenna
manufacturer certifies the associated antenna. The transmission line shall be tested
using a 50-ohm resistive RF load on the antenna end of the transmission line.
Testing shall use equipment specifically made for the purpose. Approvide testing
modes include:
•
time-delay reflectometry (TDR),
•
voltage standing wave ratio (VSWR), or
•
return loss bridge.
Any transmission line/antenna system which does not meet the manufacturer’s
specifications shall be diagnosed, and the faulty component shall be replaced at no
cost to CCEM.
A documented report of each line tested shall be provided to CCEM. Documentation
shall include calculations of acceptable parameters for the testing mode used, based
on the transmission line and antenna manufacturer’s specifications, and a graphical
15
Grounding Methods
diagram of the full range tested with the specific frequency(s) intended for use on the
antenna marked on the diagram.
3.7.
Grounding Methods
The proposal shall provide for materials and labor to design and install a complete
external ground system for the tower site. The external ground system shall include:
•
External subterranean ground system;
•
Tower grounding system;
•
Transmission line entrance panel; and,
•
Grounding of all metallic components within the ground system.
At all locations all equipment shall be grounded to the building ground system using
not less than #2 bare or green jacketed stranded copper conductor, unless otherwise
specified. The following requirements shall apply to the installation of all grounding
conductors:
•
Sharp bends shall be avoided because the sharp bend increases the
impedance and may produce flash points.
•
Grounding conductors shall be run as short, straight, and smoothly as
possible, with the fewest possible number of bends and curves. (See NFPA
70, Articles 800-40, 810-21, and 820-40.
•
A minimum bending radius of 20 cm (8 in.) shall be maintained, applicable
to grounding conductors of all sizes (per NFPA 780, Section 3-9.5 and
ANSI T1.313-1997). A diagonal run is preferable to a bend even though it
does not follow the contour or run parallel to the supporting structure.
•
All bends, curves, and connections shall be toward the ground location, rod
or ground bar (grounded end) of the conductor.
The tower shall be grounded on each leg by a minimum of #2 AWG solid copper
wire to not less than four (4), 5/8" x 10' copperweld ground rods driven in a square
and interconnected around the tower base. The distance between each ground rod
shall be sixteen feet (16ft) and each rod shall be at least three feet (3ft) from the
nearest tower leg. The ground loop and ground rods shall be at least eighteen inches
(18") below the surface. All connections shall be exothermically bonded.
Each leg of the TOWER shall be exothermically bonded to the tower ground ring
using grounding conductors of 35mm2 (#2 AWG) minimum, bare tinned solid or
stranded copper conductor.
A Single-Point External Ground Bus bar (“EGB”) shall be installed on the outside
wall just under the feedline entrance panel. A #2 AWG copper conductor shall be
connected to the tower ground ring earth ground conductor, using the straightest
possible downward run. The new entrance panel shall be grounded to the EGB using
solid #2 AWG copper conductor. Optionally, for reduced impedance to the
grounding electrode system, the EGB may be connected to the external ground ring
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Chatham County EM EOC Backup Communications Tower
using solid copper strap. Relatively small copper strap has significantly less
inductance (impedance to lightning) than large wire conductors
A ground kit shall be installed on each transmission line within twelve inches (12”)
of the EGB, and the ground lead shall terminate at the EGB prior to entering the
building.
The lowest tower ground bus bar (“TGB”) shall be installed near the area of the
tower at the point where the antenna transmission lines transition from the tower to
the ice bridge. A TGB shall be installed on the TOWER at seventy-five foot (75ft)
intervals above the lowest TGB. TGBs shall be installed adjacent to the cable ladder,
and shall be interconnected using a 35mm2 (#2 AWG) or larger bare tinned solid
copper conductor. Avoid bending this conductor. The grounding conductor shall
continue to the top of the tower, where it shall be exothermically bonded to the
TOWER lightning rod.
Each TGB shall be directly bonded to the tower, using hardware or materials suitable
for preventing dissimilar metal reactions as allowed by the tower manufacturer. The
lowest TGB shall also be exothermically bonded to the tower ground ring with a
35mm2 CSA (#2 AWG) or larger bare tinned solid copper conductor. Avoid bending
this conductor. This conductor may be sleeved in PVC for protection if desired. (See
ANSI T1.313-1997)
All transmission lines shall be grounded to prevent lightning from creating a
difference of potential between the tower and the transmission lines. Such a potential
difference could cause arcing between the tower and the coaxial transmission line
cable, resulting in damage to the transmission lines. All transmission lines shall be
grounded using ground kits from the transmission line manufacturer as follows (See
ANSI T1.313-1997 for more information):
•
Transmission line ground kits shall be installed per manufacturer
specifications.
•
Transmission line ground kits shall be sealed from the weather to prevent
water and corrosion damage to the transmission line.
•
A ground kit shall be installed on each transmission line which passes by
that TGB within twelve inches (12”) above each TGB, and the ground lead
shall terminate at the TGB.
•
Transmission line ground kits shall be attached to the closest lower TGB or
other tower manufacturer approved locations on the tower structure. Cable
ladders shall not be used as a grounding point for transmission lines unless
effectively grounded using low impedance methods and specifically
designed by the tower manufacturer as a transmission line grounding point.
Transmission line ground kits shall be attached to the tower using tower
manufacturer approved methods, such as clamps or exothermic welding.
•
Transmission line ground kit grounding conductors shall be installed
without drip loops, parallel to the transmission line, and pointed down
towards the ground to provide a direct discharge path for lightning.
•
Transmission lines shall be grounded at the top of the vertical run, near the
antenna.
17
Grounding Methods
All metal objects, as allowed by their manufacturer, that are located within 3.05 (10
ft.) of the external grounding electrode system , or are associated with the
communications site equipment, shall be bonded to the external grounding system
using 35mm2 (#2 AWG) conductors (ANSI T1.313-1997). This includes but is not
limited to:
•
Internal Master Ground Bar (MGB)1
•
Metallic entry points
•
Ice bridge
•
Building ice shields
•
Piping
•
Air conditioner
•
Fences
All connections to the earth ground system shall be exothermically bonded.
3.7.1
Ice Bridge
The ice bridge, if required by final design, shall be installed by contractor. The
support posts of the ice bridge shall be firmly encased in concrete foundations. The
ice bridge may be attached to other structures (e.g., tower, building) for additional
stability, but these mounts shall not be used for support – the sole support for the ice
bridge shall be through the support posts provided by the manufacturer.
The tower ice bridge shall be exothermically bonded to the external ground bus bar
and grounded at all support posts using exothermic welding. This connection shall be
of 35mm2 (#2 AWG) minimum bare tinned solid copper wire attached to each post
and connected to the external grounding electrode system.
The tower cable runway/ice bridge shall not be bonded to the tower ground bus bar.
The ice bridge shall be kept isolated from the tower using electrical isolation
hardware as required. This increases the impedance from the tower to the building,
reducing the amount of energy reaching the equipment room in the event of a
lightning strike. This does not lessen the cable runway/ice bridge grounding
requirements.
All spans of cable runway used between the tower and building shall have bonding
jumpers installed between the sections. The bonding jumpers shall use two-hole lugs
and stainless steel hardware to prevent loss of ground continuity with weathering.
3.7.2
Entrance Panel
The contractor shall create a penetration of the cinder-block wall of the equipment
room, sized appropriately to the provided transmission line entrance panel. The
perimeter of the penetration shall be framed using standard 2x8 pressure treated
lumber. The frame shall be securely fastened to the surrounding wall materials using
1
Supplied and installed by others
18
Chatham County EM EOC Backup Communications Tower
appropriate anchor and lag bolt hardware. Use of nails to secure the frame is not
acceptable.
The entrance panel shall be securely fastened to the frame. The perimeter of the
entrance panel shall be weather sealed using a clear exterior silicone-based or
siliconized latex caulking material.
The entrance panel shall be exothermically bonded to the single-point External
Ground Bus Bar (“EGB”) using a solid #2 AWG copper conductor, using the
straightest possible downward run.
Boots shall be installed in the entrance panel, and each transmission line shall be
routed through the appropriate boot.
3.7.3
Grounding Testing
Upon completion of all site grounding, the contractor shall verify that the resistance
to ground at any point does not exceed 5 ohms at any point in the grounding
subsystem. Testing shall be accomplished using either a clamp-on ohmmeter (such
as AEMC Model 3711), or three-point/fall of potential test.
3.8.
Safety
Tower contractors and subcontractors shall be OSHA certified (29CFR Part 1926),
and shall employ appropriate personal protective equipment (“PPE”)
All tower crew personnel, including those on the ground and on the tower, shall be
trained on radio frequency emissions hazards and safety (FCC Bulletins OET-56 and
OET-65, and FCC 97-303) and on the proper use of appropriate RF emissions and
fall safety PPE.
3.9.
Contractor Responsibilities
The successful vendor shall be responsible for the following:
•
Provide all tower materil, as outlined in vendor’s bid response, regardless of
manufacturer.
•
Provide engineering, erection, and installation services for all equipment, as
outlined in vendor’s bid response, regardless of manufacturer.
•
Provide a detailed project schedule which outlines all tasks involved with
the implementation of the proposed tower. Oversee and coordinate all
installation scheduling.
•
Provide all engineering and planning related to the tower.
•
Provide documentation and manuals per specifications.
•
Obtain building permits as needed.
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Chatham County Emergency Management’s Responsibilities
3.9.1
•
Provide coordination between CCEM, the selected vendor, and all
subcontractors to assure a quality system, timely delivery, a safe
implementation, and to ensure that all contractual commitments and
warranty commitments are met.
•
Provide a detailed Statement of Work (SOW), after the vendor has been
selected as the vendor of choice, which will be included in the final contract.
Warranties and Service Agreements
The manufacturer(s) and the proposer shall warranty the operation and functionality
of the proposed tower for one year following installation. All parts and labor shall be
covered under the warranty. Labor warranty repairs shall be covered 24 hours a day,
7 days a week (7x24) including holidays, for the tower provided to CCEM.
System warranty shall begin upon tower acceptance. The proposer shall include in
the proposal a statement of the terms and conditions of all warranties which apply.
3.10. Chatham County Emergency Management’s Responsibilities
Chatham County EM will be responsible for the following:
20
•
Provide reasonable access to CCEM’s facilities where equipment is to be
installed.
•
Provide all antennas, transmission lines, connectors, snap-in cable hardware
and all ancillary material
•
Provide all AC power at site for awarded contractor, if needed
•
Assist awarded contractor, if needed, with contact information of County
personnel for Ordinance Compliancy, permitting and/or inspections
Appendix
APPENDIX A
21
Chatham County Emergency Management’s Responsibilities
22
Chatham County EM EOC Backup Communications Tower
APPENDIX B
23
Chatham County Emergency Management’s Responsibilities
APPENDIX C
24