Tower Pre Construction

In 2005, we tested and evaluated available microwave radio technology and products to determine if 802.11g (54 Meg/second) radios are technology feasible and cost effective.

The Broadband department working with the Tribal IT department installed, tested and verified 802.11g microwave radios and verified 802.11g technology does perform reliably.  The entire Coeur d’Alene tribal wireless network was changed from the existing and older 802.11b (11 Meg/second) system to a newer and faster 802.11g (54 Meg/second) network.  This established a working fully functional proof-of-concept that 802.11g microwave radios will perform reliably in large quantity deployments over a vast area.  The decision was then made to build the wireless microwave broadband system on 802.11g (54 Meg) technology instead of the older and more popular 802.11b (11 Meg) technology.

The final results of our testing 802.11g (54 Meg/second) technology radios resulted in our decision to utilize Vivato 802.11g microwave Base-Station radios for high density and long distance distribution points.

Above is one of our outdoor Vivato 802.11g radios

Tower Construction

Road work was one of the first projects needing to be completed prior to tower construction.  The Plummer-Butte road needed to be widened and leveled to allow heavy equipment to access the top of the mountain.

The Plummer-Butte’s three mile long road needed to be leveled, widened and brushed to allow heavy construction equipment to access the Plummer-Butte mountain top.

Plummer-Butte road being worked on to widen the road

Worley T574 needed a road to the top allowing heavy equipment to access the top of the T574 hill.

Worley T574 – New road for tower construction equipment access

Tower construction – core samples:

Core samples at Plummer-Butte and Worley T574 microwave tower sites were required to engineer the microwave tower foundations.  Core samples were drilled to a depth of 30 feet at both primary tower locations.  The core samples are then sent to a geotech lab to determine the type of tower foundation needed to support the structure and weight of the microwave tower.

Left – A tracked core drilling rig.  Right – core drilling samples

A tracked core-drilling rig was brought in to access the tower sites.  At this time, the ground is still soft and a heavy truck or crane will sink into the ground and get stuck.

All microwave towers must have core-drilling samples made.  The results from the core drilling samples determine the design required to adequately support the foundation of the tower.  A tower foundation does not only support the weight of a tower, itadditionally holds the tower in place during high winds, which create up-lift pressures on legs.  When storm winds push on a 3-leg self-supporting tower, two legs take the entire weight of the tower while a third leg is lifted into the air.  A properly engineered tower foundation uses information from core samples to determine what the earth can support.

Tower construction – Underground Electrical:

Both Plummer-Butte and Worley T574 microwave tower locations need electrical power installed.  A first step in laying underground power is the pre-rip stage.  Heavy equipment cuts a three to four foot deep trench in the ground the entire distance where new underground power will be installed.  The pre-rip procedure makes the actual installation of underground conduits & power much easier because the ground has been pre-cut.  Additionally, a pre-rip is necessary to locate hard rocks which would require additional rock cutting equipment.

Equipment above is pre-ripping underground path

The Plummer-Butte pre-rip encountered about one hundred yards of rocks which required a heavy duty rock cutting wheel to be brought in for pre-trenching.

Rock cutter above is cutting a four foot deep trench for cable

Although the rock cutter pictured above spins the cutting wheel at almost 30 MPH, the hard rocks delayed underground power installation of conduits almost two weeks.

The gray fiber optic conduit from Plummer-Butte crosses the road by A366.  The conduit is drilled horizontally under the road.  Because the road is not dug-up, there is less maintenance needed for road care after the conduit is installed.

Horizontal drilling machine

After pre-trenching is completed, underground conduits are plowed into the pre-trenched ditches.

Heavy equipment installing underground conduits

When heavy equipment is plowing underground conduits, the equipment can’t backup when it encounters rocks.  Pre-ripping enables the underground conduits to be installed without problems because a known tested pre-ripped path is used.

Our conduits are buried at the following depths (on Plummer-Butte):

• Two feet – A warning marker ribbon
• Three feet – Gray conduit for fiber optic cable
• Four feet – Red conduit for power (7,000 volts)

Marker ribbon with red and gray conduits

The marker ribbon serves as warning to any person digging in the future.  Encounter a warning marker ribbon; stop digging because you are feet from thousands of volts in electrical power.

After all underground conduits were installed; The KEC 7,000 volt electrical power wires were pulled through the underground red conduits.  Both Plummer-Butte and Worley T574 had electrical meter basses installed.

Plummer-Butte meter base (six-pack)

Plummer-Butte has a six-pack meter base installed.  This type of meter base allows electrical outlets and meters for five additional electrical clients at Plummer-Butte.  The Gateway Fire Department will be the second KEC electric customer at Plummer-Butte.  The remaining four meters (electrical connections) are reserved to attract potential cell phone co-location companies.  At this time, we know there is interest from Verizon,  AT&T and Singular for co-location on the Broadband towers.

Tower construction – foundation boring:

A tracked drilling rig begins drilling tower foundations on Plummer-Butte and Worley T574 locations.  This foundation has been engineered from the previous core samples made several months ago.

Our microwave tower foundations consist of a micro-pile design.  In summary, our microwave tower foundations are essentially a 30 foot hole with a 4 inch threaded pipe placed in the hole then the remaining empty area is filled with grout.  This results in an extremely strong foundation.

Drilling rig digging microwave tower foundations
Tower leg foundation consisting of casing, threaded bar and grout

Interestingly, the micro-pile foundation for the microwave towers appears to look similar to a common (water) well.  The micro-pile hole is then filled with grout and a 1-foot diameter round threaded nut is screwed down on the micro-pile.  Each tower utilizes three micro-pile foundations.  The micro-pile foundations must be level, a ¼ inch off (to low or high) would result in the top of our towers leaning four inches.  Our towers do not lean in any direction because the micro-pile work was checked many times to ensure a solid level foundation.

Tower construction – tower components begin to arrive:

September 13th 2005 – the first shipment of tower components

September 13^th is the first of tower shipments to arrive.  It is clear that fall has arrived.  The fog delays the truck driver until he can safely drive from Coeur d’Alene to Plummer. This shipment of tower components consists of 20-foot tower legs.

Unloading tower components while not destroying trees in the process

The tower components are transported to the Worley T574 and Plummer-Butte tower locations.  The pictures above are the semi-truck delivering the shipment to the Worley T574 tower location.  Please note we have made efforts not to destroy trees and to attempt to keep the natural scenery of the environment where possible.

10/24/2005 – The first 20-foot leg is bolted in place.

Above, the first 20-foot leg of a three leg 120-foot tower is erected and bolted into place on the Worley T574 tower site.

Fall conditions begin to turn roads into mud slides

The image above is the wet clay road to the Worley T574 tower site.  When this road gets wet, the road is slick as ice.  A 30 MPH run up the hill to make it to the top results in a dangerous 30 MPH uncontrolled slide back down the hill.  The tower construction crews are forced to chain up all four tires on their four-wheel-drive to make it to the top.  Additional tower equipment must be pushed or pulled up by bulldozer.

Fortunately, the Broadband staff is able to utilize their tracked vehicle and safely drive to the tower locations.  Otherwise, we would have been walking in the mud and rain up the hills or mountains.

Muddy roads force the use of a dozer to push tower equipment up to tower sites

Above, Nick Parker – a T.E.R.O. registered contractor has sub-contracted with the tower contractor to provide labor, equipment and assistance in many aspects of tower construction.  Above, Nick is pushing our utility building up the hill to the T574 tower location.

Utility building get delivered – tower is at 60 feet and rising

The utility building was color picked to be a dark green.  This was decided to best hide the building around the surrounding green trees.  Above, the tower is now 60 feet tall and has another 60 feet to go up higher still.

Winter sets in and towers need to be wired for equipment

The Plummer-Butte microwave tower was erected in the early stages of winter with off and on snow at the top of Plummer-Butte.

The above pictures show typical winter snow & ice conditions on the microwave towers

Plummer-Butte 120-foot tower covered in ice

A 30-degree day in Plummer often means a sub-zero wind-chill day on Plummer-Butte.  During the above pictured trip, we are working in the utility building to configure our communication equipment.

Worley Long House microwave antenna

The above image is a picture of the Worley Long House microwave dish (lower round object) which communicates to a similar dish on the Worley T574 microwave tower.  The data is then relayed to the Plummer-Butte microwave tower which is then relayed to the tribal head quarters in Plummer, which is then transported by fiber optic cable to the NOC server room where a hand-off is delivered to the IT department.

Broadband coverage areas:

The following image, illustrates the potential line-of-site coverage area from our two primary microwave towers (T574 and Plummer-Butte) and the Worley Long House 40-foot/60-foot relay tower:

Potential line-of-site coverage to clients

The above line-of-site coverage map does not indicate the 5 mile maximum distance we are limiting our clients to.  Any clients beyond 5 miles radius distance from a tower may be subject to weak connections, which are prone to running slow and periodic disconnections.