HomeMy WebLinkAboutTanana Waste Heat Status Reports, Trip Reports, & Field Notes 1992MEMORANDUM STATE OF ALASKA
ALASKA ENERGY AUTHORITY
To: File Date:4/6/92 “7 fer 206 Aye : : <* Thru: Brian Gray
Sst Steve Stassel
Subject: Tanana Waste Heat Investigation 3/24-25/92 Trip Report
SUMMARY
A site visit was made to the City of Tanana to investigate the operation of the waste heat system
there. Overall, the system is functioning as designed. However, the heating systems in several of
the City buildings and the school are not operating properly which has the effect of overcooling the
waste heat loop and reducing the waste heat supply temperature.
A "normally closed" valve at the school gym boiler room was closed and the boiler set point was
increased by 15F. This helped to increase the waste heat supply temperature from about 135 to
165F.
Tanana Power has replaced its D399 and D398 Caterpillar diesels with more efficient D3508 and
D3512 diesels over the past few years. This has reduced the amount of heat available to the waste
heat system. Recovery of the exhaust heat would about double the amount of waste heat available
and may make economic sense for the utility to pursue.
The waste heat sales agreement between the end-users and Tanana Power lapsed in 1991. I
recommend that Tanana Power repair the waste heat system BTU meter in the power plant and
use it for determining the amount of waste heat provided to the School District and the City
buildings.
TRIP REPORT
Tuesday and Wednesday 3/24-25/92 (Clear, light wind, 25F-40F)
I departed from Anchorage on Alaska Airlines at 6:45 a.m. and arrived in Tanana at 9:30 a.m. I
was met by Ralph Eller of Tanana Power and proceeded to the power plant where I met Dennis
Schouweiller (Plant Operator, 366-7190). Mr. Eller showed me the waste heat system and
explained the history of the system.
The system was installed in 1984 and provides heat to six city buildings and three school buildings.
Originally, the power plant operated Cat D398's and D399's, but has converted to Cat D3508's and
a D3512. This change has reduced the amount of waste heat available due to the increased
efficiency of the new engines.
Mr. Eller also explained that in late November 1991 the plant had an oil cooler failure. This caused
all fifteen butterfly valves in the plant cooling system to fail. The valve seats were dissolved by the
glycol/oil mixture and literally fell apart. Mr. Schouweiller explained that he was in the process of
replacing the failed Nibco valves with Crane butterfly valves that have oil and heat resistant seals.
He also mentioned he thought that the power plant H/E was plugged with the pieces of the valve
seals. After the oil cooler failure, the cooling system glycol was changed from ethylene to
propylene glycol. The plant now adds propylene glycol to the ethylene glycol in the waste heat
system.
After as-builting the power plant cooling system and waste heat tie-in, Mr. Eller escorted me
through the nine waste heat end-user buildings. Each of the end-user buildings receives heat from
the waste heat system by one of the three following methods:
-Stand alone ceiling mounted, or cabinet, unit heaters
-Return air duct heating coils
-Heat exchanger connected to the boiler return line
In the end-user buildings that have unit heaters and return air duct heating coils, a Danfoss
temperature regulated valve is installed in the waste heat return line and throttles the flow of the
waste heat in response to rise in the waste heat return temperature. In the end-user buildings that
have heat exchangers, the Danfoss valve is also located in the waste heat return line and throttles
the flow of waste heat in response to a rise in the temperature of the water from the heat exchanger
into the boiler. The Danfoss valve is a direct-acting valve in that it modulates closed with a rise in
the sensor temperature. In this way, when the demand for waste heat at an end-user building is
low, the valve will start to modulate closed. This should allow more flow to other end-user
buildings with a greater demand for waste heat.
Each Danfoss valve is manually adjusted from 1 to 5 to change the operating temperature setpoint.
The Danfoss valves on the unit heater systems should be set at 150F (about #2) and on heat
exchanger systems the Danfoss valves should be set at the same temperature as the boiler high limit
(180F maximum). The approximate temperature relationship for each scale value is as follows:
Scale Temperature
1 130
150
175
195
210 Ak WN To adjust the valve correctly (heat exchanger application), first adjust the boiler set point to the
correct setting. Remove the sensor from the pipe (this assumes that the sensor is in a well and not
directly immersed in the fluid) and immerse in a liquid at the same temperature as the boiler high
limit (180F, maximum). Adjust the valve so that it just starts to modulate closed at that
temperature. For unit heater applications, adjust the valve so that it just starts to modulate closed
when the waste heat return temperature is at 150F. The current setting for each Danfoss valve is
listed below in the narrative for each building.
A waste heat system is not intended to be the primary heat source for a building. Rather, a waste
heat system is designed to reduce the fuel consumption of a building heating system by either pre-
heating the boiler return water (heat exchanger systems) or pre-heating the air (unit heater and
return air coil waste heat systems). It is mandatory that the end-user building heating system is in
proper working order and adjusted properly. If not, the load on the waste heat system can exceed
the amount of heat available from the power plant and cause the waste heat loop temperatures to drop substantially. With heat exchanger systems, the boilers should be set to fire between about 155F and 175F, or 160F and 180F for optimum efficiency (based on the boiler temperature gauge
and not the aquastat setting). If the boilers operate above 180F, they may add heat to the waste heat loop rather than take heat out. With unit heater systems, the waste heat wall thermostats
should be set about 3F to SF degrees above the building heating thermostat setpoints (if the waste
heat thermostat is set at 70F, set the building heating thermostat at 67F). This guidelines will help
provide the maximum amount of heat from the waste heat system to the end-user building and
prevent the waste heat supply temperature from being overcooled.
As can be seen by the information below, many of the buildings heating systems are not operating
properly.
City Maintenance Garage
The garage waste heat system originally consisted of two vertical unit heaters. The waste heat return temperature was about 160F and the Danfoss valves were set at about 3. The garage heating system consists of two direct oil fired unit heaters. At the time of my visit, only the waste
heat unit heaters were operating.
Sometime in the last few years a bus barn was added to the garage and was also connected to the
waste heat system. The bus barn uses only waste heat for heat. There are no Danfoss or circuit
balance valves on the bus barn unit heaters. While I was there, the bus barn waste heat unit
heaters were providing a much higher discharge air temperature than the garage waste heat unit
heaters.
The waste heat return valves in the bus barn should be closed some to help balance the flow of heat to both the bus barn and garage. Close each return valve in the bus barn an equal amount until the
discharge air temperature of the unit heaters in the bus barn is about the same as in the garage. It will take a bit of trial and error to adjust them properly. Also, the oil fired unit heaters should be adjusted to come on a few degrees below the waste heat thermostat setpoints.
VSW Building (Washeteria)
There are two boilers in the washeteria, one Burnham rated at 391 MBH @ 3.95 GPH oil, and one
American Standard rated at 1257 MBH @ 12.56 GPH oil. The Burnham boiler was isolated off
from the heating system. The American Standard boiler was set at a low limit of 160 and a high
limit of 170F. However, the boiler power was turned off and the boiler was not operating. I briefly
tripped the power switch and the boiler fired. At the time of my visit, the VSW building was
receiving all of its heat from the waste heat system. Later I mentioned this to Mayor Peter Platten
and he informed me that the controls on the boiler were not operating and the boiler was manually
turned on and off.
The waste heat system heat exchanger is piped as a secondary loop into the boiler return line and
uses a Grundfos UMS 65-180 pump for circulation. All valves were inspected and found to be set
correctly.
The temperatures were recorded as follows:
Waste Heat Supply 162F
Waste Heat Return 155F
Waste Heat Pressure Gauge broken
Heating Water Into H/E 135F
Heating Water out of H/E to Boiler Thermometer broken
Danfoss Valve Setting 1.7
The washeteria has several (as many as 6 or 8) hot water heated dryers. Based on my experience
with this type of dryer, it is very difficult for a waste heat system to provide adequate heat for the
dryers to operate efficiently. A hot water heated dryer requires very high temperature water (220F +) to run at its optimum efficiency. Most PHS and VSW boiler systems I have seen that
don't have waste heat systems operate at about 200F, maximum. A waste heat system can provide about 180 to 185F, maximum. If the end-user boilers are set to fire above 180F it is very possible
during warm weather that the boilers will heat up the waste heat loop and cause the power plant
radiator fans to run. If this occurs, the boilers will run excessively and increase the end-user
building fuel consumption. It can also cause the power plant to shut down on high temperature.
However, since the VSW (washeteria) building was operating only on waste heat at the time of my
visit, the waste heat system was being overcooled which lowered the waste heat supply
temperature. Operating the dryers at such low temperature substantially increases the time
required to dry clothes.
The boiler controls should be repaired and adjusted so that the boilers fire between 160F and 180F.
Also, the broken thermometer and pressure gauge should be replaced.
Day Care
There is one Burnham boiler in the Day Care building rated at 167 MBH @ 1.65 GPH oil. The aquastat was set at 160F, however, the boiler log indicated that the boiler was firing between 190
and 200F+. The waste heat system heat exchanger is piped in series with the boiler return. All
valves were inspected and found to be set properly.
The temperatures were recorded as follows:
Waste Heat Supply 162F
Waste Heat Return 161F
Waste Heat Pressure Gauge broken
Heating Water Into H/E 156F
Heating Water out of H/E to Boiler 144F
Danfoss Valve Setting 3
As can be seen by the heating water temperature decrease through the heat exchanger, the Day
Care boiler is adding some heat to the waste heat loop. The waste heat loop thermometers are also
out of calibration. Since some heat is being added to the waste heat loop, the waste heat return
temperature should have been slightly higher than the supply temperature.
The boiler set point should be lowered and the boiler temperature gauge visually monitored so that the boiler fires from about 155 to 175F. This will prevent the heating system from adding heat to
the waste heat loop. Also, the waste heat supply and return thermometers and the pressure gauge should be replaced.
Teen Center
The Teen Center has been closed for several years. The waste heat system consists of a large cabinet unit heater tied directly into the waste heat arctic piping. The waste heat valves are closed and no heat is being provided to the building.
Fire Station
There is one Burnham boiler in the Fire Station rated at 137.4 MBH @ 1.35 GPH oil. The aquastat was set at 158F. The waste heat system heat exchanger is piped in series with the boiler
return. All valves were inspected and found to be set properly, except that the valve from the heat exchanger to the boiler was only one-half open. The boiler gauge indicated a supply temperature of 150F.
The temperatures were recorded as follows:
Waste Heat Supply 160F
Waste Heat Return 135F
Waste Heat Pressure Gauge broken
Heating Water Into H/E 106F
Heating Water out of H/E to Boiler 146F
Danfoss Valve Setting 3.5
The boiler aquastat was calling for heat but the boiler would not fire. I checked that the boiler
breaker (#6) was on and adjusted the aquastat but the boiler would not fire. At the time of my
visit, the Fire Station was receiving all of its heat from the waste heat system. As can be seen by the
low waste heat return temperature (135F), the Fire Station was overcooling the waste heat system
and lowering the waste heat supply temperature.
The boiler controls should be repaired and the boiler set to fire between 155F and 175F. Also, the
pressure gauge should be replaced.
City Office
There is one Lennox furnace in the City Office. The waste heat system provides heat to a preheat
coil in the return air duct. The R/A duct was covered with boxes that obstructed the flow of air to
the furnace. At the time of my visit, the office was not calling for heat and the furnace was not
running. All valves were inspected and found to be set properly,
There is only one thermometer in the waste heat return line and it was broken. The Danfoss valve
setting 3.5.
The boxes should be removed, and the thermometer and pressure gauge replaced.
Voc-Ed Shop
The Voc-Ed Shop waste heat system consists of two circular coil Dunham-Busch horizontal unit
heaters, one in the welding room and one in the wood shop. The unit heater in the welding shop
was not operating upon our arrival. I reset the wall switch and the unit started. The wall
thermostat for this unit is broken and should be repaired or replaced. The waste heat return
temperature was about 125F and the Danfoss valve was set at 5.
The unit heater in the wood shop was operating upon arrival. The waste heat return temperature
was about 130F and the unit was providing good heat. The wall mounted thermostat was set at 70
and was operating. The Danfoss valve was set at about 2.
The VocEd Shop heating system consists of large oil fired air handling unit. I adjusted the wall
thermostat and the unit did not come on. At the time of my visit, only the waste heat unit heaters
were operating.
The oil fired unit heater should be repaired and the thermostat adjusted to about 67F. Also, the
broken waste heat thermostat should be replaced.
Main School Building
There are two boiler rooms in the main school building, one at the gym and one adjacent to the
teacher's lounge. The boiler rooms are piped so that heat can be provided from one boiler room to
the other, and vice-versa.
There are two Burnham boilers in the gym boiler room, both rated at 539 MBH @ 5.45 GPH oil.
Boiler #1 high limit was set at 165F and boiler #2 high limit was set at 190F. Boiler #1 was
operating and boiler #2 was valved off. Both boilers have Honeywell aquastat controllers that have
a dial that is adjusted from "cool" to "hot" for the low limit, and a hand wheel that is adjusted for the
high limit temperature difference. The boiler operating controller for boiler #1 was set between
"normal" and "warm", and boiler #2 was set at "cool". The hand wheel for boiler #1 was missing.
Boiler #1 was firing between 140F and 152F according to the boiler gauge.
There are two American Standard boilers in the second boiler room, both rated at 381 MBH @
4.75 GPH oil. Boiler #1 high limit was set at 162F and the low limit at 143F. Boiler #2 high limit
was set at 160F and the low limit at 135F. According to Bill Sam, school maintenance, boiler room
#2 receives all of its heat from the gym boiler room. Both boiler rooms share a common day tank
located in the gym boiler room. Recently, a new day tank was installed in the gym boiler room.
The new day tank is a one-pipe system, whereas the boilers in both boiler rooms are two pipe
systems. The return fuel piping from boiler room #2 was not capped and when the boilers in boiler
room #2 fire, fuel is spilled on the floor at the day tank in the gym boiler room. In order to prevent
this from occurring, the boilers in boiler room #2 are not used.
The heating supply water temperature at boiler room #2 was about 140F, whereas, boiler #1 in the
gym boiler room was providing 152F heat. I traced the piping at the gym boiler room and
determined that a normally closed bypass valve was open providing the gym boiler return heating
water to boiler room #2. I closed this valve and left a note to Bill Sam indicating this. I also raised
the high limit set point on the gym boiler #1 to 180. This caused boiler #1 to fire from about 145F
to about 165F. The combination of closing the bypass valve and increasing the high limit raised the
heating supply water temperature in the second boiler room to about 160F.
The net result of the two changes implemented above stopped the school from overcooling the
waste heat loop and increased the waste heat supply temperature to about 170F.
The waste heat system heat exchanger is piped as a secondary loop into the gym boiler return line
and uses a Grundfos UMS 65-180 pump for circulation. All valves were inspected and found to be
set correctly.
The temperatures were recorded as follows:
Waste Heat Supply Broken (assume 162F)
Waste Heat Return 135F
Waste Heat Pressure Gauge broken
Heating Water Into H/E 144F
Heating Water out of H/E to Boiler No thermometer
Danfoss Valve Setting 5
The fuel system to boiler room #2 should be repaired. The thermometer and pressure gauge
should be replaced and the boilers set to fire between 155F and 175F.
Power Plant
The power plant tie-in to the waste heat heat exchanger is different than any other system I have
worked with, in that it has two amot valves rather than one. Most waste heat systems have one
amot valve (with 180F thermostats) located on the outlet side of the heat exchanger between the
heat exchanger, radiators, and return piping to the engines. The valve is designed to prevent
coolant flow from going to the radiators if the waste heat system has lowered the coolant
temperature to 180 or less. If the coolant temperature is above 180F, the valve diverts some flow to
the radiators to be cooled and then mixes the "cold" coolant from the radiators with the "warm"
coolant from the heat exchanger so that the "mixed" return temperature to the engine is 180F.
The Tanana power plant has an amot valve as described above, but it also has another amot valve
(heat exchanger amot) with 180F thermostats located between the inlet and outlet ports of the heat
exchanger in the engine coolant piping (usually a normally closed heat exchanger bypass valve is
located at this point rather than an amot). The purpose of this second amot valve is to prevent the
end-user buildings from over-cooling the Tope This amot valve is piped so that "hot"
coolant from the engine bypasses the heat‘exchanger ‘fhlet and mixes with the "warm" coolant from
the outlet of the heat exchanger to provide 180F heat to the second amot valve.
A heat exchanger is designed for full flow. If the flow is reduced by as little as 25%, the heat
transfer ability of the heat exchanger is reduced substantially (maybe by as much as 50%). This
occurs because with reduced flow, the hot coolant is not equally distributed across all of the plates
of the heat exchanger. If flow is reduced enough, only a few of the plates will have fluid flow across
them which will further reduce the heat transfer ability of the heat exchanger. Either the
thermostats in the heat exchanger amot valve should be replaced with 170F thermostats, or the
valve should be removed and a normally closed heat exchanger bypass valve installed. This should
allow full flow through the heat exchanger and help maintain the waste heat supply temperature at around 170F to 180F (this also assumes that the end-user building heating systems are operating
properly).
Mr. Eller and I conducted a test at the power plant to see if the power plant heat exchanger was
plugged with junk from the failed butterfly valve seals by shutting off the waste heat circulating
pumps. With the pumps off, no heat was removed from the coolant. This should have caused the
heat exchanger amot valve to divert full coolant flow through the heat exchanger (about 400 GPM).
We monitored the pressure gauge at the inlet of the heat exchanger during this test. Prior to
shutting off the pumps, the flow through the heat exchanger was about 80 GPM (based on
temperature readings and an assumed full flow of 400 GPM) with an inlet pressure of about 3 psi.
After shutting off the pumps, the inlet pressure remained at 3 psi. We then closed the B-port of the
heat exchanger amot valve to ensure full flow through the heat exchanger. This caused the inlet
pressure to rise to 4.25 psi. A 1.25 psi pressure increase with an increase in flow from 80 GPM to
400 GPM is well within the design parameters of the heat exchanger and indicates that the heat
exchanger is not clogged. However, the increase in pressure upon closing the amot B-port does
indicate that the amot valve is not working properly and that maybe the amot thermostat seals have
failed due to the oil in the glycol and should be replaced.
On Wednesday prior to departing from Tanana, Mr. Eller and I met with Mayor Platten to inform
him of our findings. A topic of discussion was the waste heat sales agreement between the Tanana
Power and the City and School District. The original agreement expired in 1991 and all parties are
looking for a better way to calculate fuel savings. The power plant has a BTU meter that is
currently not working. I suggested that Tanana Power repair and use the BTU meter to measure
the amount of waste heat (BTUs) provided to the waste heat system.
The amount of waste heat received by the School and the City would be the number of BTUs
provided minus the constant losses (BTUs) for the underground piping. One gallon of #1 heating
fuel is saved for every 100,000 BTUs of waste heat received. The distribution of waste heat
received by the City and District could be based on fuel usage records prior to the waste heat
system being installed (about 55% to the school and 45% to the City). It would be up to the City,
District and Tanana Power to place a value on each gallon of waste heat received.
I departed Tanana on Larry's Flying Service and arrived in Fairbanks at 6:15 pm. I interviewed
students at UAF on Thursday who were interested in the Summer ME and EE positions with AEA.
I departed Fairbanks on Alaska Airlines on Thursday at 5:25 pm and arrived Anchorage at 6:15
pm.
CONCLUSIONS:
There is less heat available for waste heat now than when the system was installed in 1984. This is
due to more efficient diesels being used.
I recommend using the BTU meter in the power plant to measure the amount of waste heat
provided to the end-users. It would be up to Tanana Power and the end-users to decide the
distribution of heat to the end-user buildings and the value of the waste heat.
The heating systems in the end-user buildings need to be repaired and adjusted properly to
maximize the efficiency of the waste heat system and increase the waste heat supply temperature.
The heat exchanger amot valve should be replaced with a normally closed valve, or the 180F
thermostats should be replaced with 170F thermostats.
Recovery of exhaust heat at the power plant may make economic sense for the utility and would
about double the amount of waste heat available.
ISS
Waste Heat Projects
Waste Heat Recovery Program
Purpose:
Results:
To provide planning, design and construction of facilities to
recover waste heat from new and existing diesel generators for
use as space heating of nearby buildings.
Between 1981 and June 1988, the Power Authority assisted in
constructing 37 waste heat recovery facilities in rural Alaska.
While some systems are owned by the Power Authority, the
agency also provides to communities construction management
and inspection of locally- or contractor-built waste heat sys-
tems and has supervised loans and legislative grants for waste
heat construction.
The Legislature appropriated $5,000,000 to the Power Author-
ity in SLA 1982, Ch 141 for loans or grants to communities or
qualified utilities for devices to decrease the cost of power
production. The intent of the legislation, introduced by the
Office of the Governor, was to decrease the cost of energy in
communities where there was no near term alternative to
diesel generation. This and other, subsequent appropriations
have been used to increase generating system efficiency and to
displace oil used for space heating with installation of waste
heat recovery systems at the generating plants.
In 1983, design and construction was undertaken of 11 waste
heat projects in Ambier, Kiana, Shungnak, Savoonga, Elim,
Kaltag, Ceo. bee St. ae Goodnews ra and
waste heat potential in 42 rural Alaskan communities began.
The study was completed under contract and concluded in 1985 with a report which prioritized installation of systems among the communities. a
Power Authority staff designed and managed the construction of a city/school district heating system for Galena in 1985-86. 7 Staff also designed and assisted with installation of a total =- energy 600 KW diesel to completely heat the Nome/Beltz High School and provide co-generated power to the Nome electrical distribution system in 1986.
In 1986, the Power Authority Board of Directors approved funding for repair and rehabilitation of the waste heat systems constructed in 1983. To accomplish this, staff inspected the systems and prepared necessary design modifications, and ordered equipment to repair the Systems. In 1987, Power Authority staff negotiated waste heat sales agreements and Operations and maintenance agreements with the utility owner, Alaska Village Electric Cooperative (AVEC), and the end- users of heat in Elim, Savoonga, Kiana, Ambler, Shungnak, Grayling. Negotiated system modifications were completed Prior to freeze-up in 1987 in Elim and Grayling. In addition, design and/or construction of waste heat systems was provided to Atka, Birch Creek, Cold Bay, St. George, Golovin and To- giak during 1987.
Construction of waste heat system upgrades was completed in Savoonga, Kiana, Ambler, Shungnak and Kaltag in 1988. Addi- tional agreements were concluded with the communities of Kaltag, Togiak, New Stuyahok, Goodnews Bay, Angoon, Chevak and Yakutat; design and construction assistance was Provided to Golovin, Koyukuk, Togiak and New Stuyahok in 1988.
“Construction: Rockford Corporation (Kiana, Ambler, Shung- ‘7°. nak, Savoonga, Elim, Kaltag, Grayling, Goodnews Bay, ‘Tan-— _ ama); Washington Mechanical (Angoon); Wick Construction _ Company (Unalakleet); J.B. Mechanical (St. Mary’s)
LC. Massel
ALASKA ENERGY AUTHORITY
ANNUAL CAPITAL PROJECT STATUS REPORT
PROJECT: Waste Heat Recovery Program
PROJECT LOCATION:
ORIGINAL ESTIMATED PROJECT COSTS: $__ON GOING
CURRENT ESTIMATED PROJECT COSTS: Expenditures Thru 12/31 $__6,538,800 Encumbrances at 12/31/90 52,047 Estimated Incurred Cost, Not Yet Recorded at 12/31/90 0 Remaining Costs 240,153
Total $ 6,831,000
SOURCE OF FUNDS:
Appropriated Funds: SLA_1982 CH_141 5,000,000 SLA__1984 CH__ 24 \_ 1984 1,131,000 ; SLA__1987_ CH 3 $ 500,000 SLA__1988_ CH_ 173 $200,000 $ Total: $_6,831,000
PROJECT DESCRIPTION:
This project is for the collection of data, analysis, design, financing, and construction of waste heat facilities in rural communities.
PROJECT STATUS AT 12/31/90:
Accomplishments Through 1989:
The first waste heat appropriation was established in 1982. By the end of 1983, eleven projects had been designed and constructed, including Ambler, Kiana, Shungnak, Savoonga, Elim, Kalta e i Mary's, Goodnews Bay, and Angoon. B ther constructed in Te and a study e eat potential in 42 rural communitie ad been completed. In 1986, design and construction management services for a waste heat system in Galena was completed, technical assistance and designs were provided to Nome for a 600 kW cogeneration plant, and existing but inoperable waste heat systems were inspected in several communities served by the Alaska’ Village Electric Cooperative (AVEC) to determine a course of action for bringing the systems on-line once again.
q naia e ng. pene me
In 1987, project agreements and heat sales agreements were initiated between the Energy Authority, AVEC, Bering Straits Schools, Northwest Arctic Borough Schools, Iditarod Area Schools, and Yukon-Koyukuk Schools for seven waste heat renovation projects. By 1988, agreements had been executed and systems had been reconstructed in the following communities:
Ambler Kiana Elim Savoonga Grayling Shungnak Kaltag
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