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Inuvik, N.W.T. airstrip instrumentation: 1969
DIVISION OF BUILDING RESEARCH
No.
NATIONAL RESEARCH COUNCIL OF CANADA
544
NOTlE
'IrE
C
1HIN ][ CAlL
PREPARED BY G.
H. Johnston CHECKED BY L. W.G. APPROVED BY C. B. C.
March 1970
PREPARED FOR Inquiry and record purposes
SUBJECT INUVIK, N.W.T. AIRSTRIP INSTRUMENTATION -1969
Studies of the effect on permafrost of a large £ill were begun
in 1957 when four thermocouple cables were installed during
con-struction of the Inuvik airport. The runway, parking apron and
connecting taxiway were constructed of crushed rock (miniInum
thickness 8 ft) placed directly on the original ground surface. Ground
temperatures have been measured at weekly intervals since June 1957
at four locations - two on the runway centreline (cables Nos. 3 and 4), one at the centre of the parking apron (cable No.2) and one in an
adjacent undisturbed area (cable No.1). The original installations,
and modifications made to them in 1961, have been described
previously in DBR/NRC Technical Note No. 360, issued in January
1962.
The Department of Transport enlarged the aircraft parking
apron in 1969 and paved the runway, taxiway and apron with hot mix
asphaltic concrete thus changing the surface characteristics of the
fill. Additional instrumentation was installed during 1969 to determine
the effect of the changed surface conditions on the ground thermal regiIne.
This Note has been prepared to record details of the work
carried out during May and early August 1969 which consisted of the
following:
(a) Extending the lead wire s so that the switch boxe s for the
original thermocouple cables Nos. 2 (parking apron) and 3 (runway centreline - west) could be relocated on the slope of the crushed rock fill.
2
-(b) Installation of two new thermocouple cables - No. 5 located
about 100 ft from the toe of slope in the tree -cleared, but otherwise undisturbed, area on the south side of the runway; and No. 6 located
at the centre of the unpaved south shoulder of the runway. Both are
opposite the taxiway (and original cable No.3). Cable No. 5 replaces
No.1 (installed in 1957), which was abandoned because of disturbance in the adjacent area and malfunction of the installation.
(c) Installation of two short (3 ft) thermocouple strings and
two heat flow transducers; cable No. 7 and HFT -1 under the centre of the taxiway, and cable No. 8 and HFT -2 under the centre of the adjacent unpaved shoulder.
(d) Installation of recorders in the airport terminal building
to continuously monitor ground temperatures and the output from the heat meters placed in the taxiway as noted in (c).
Details of the location and position in the ground of all
instru-mentation at the airport are given in Figures 1 to 5. All chainage and
elevation values given are based on 1969 DOT Construction surveys. The location of all cable runs as shown in plan view are accurate to
± 1 ft. Whenever airport lighting or power ducts were encountered,
the thermocouple extension cables were placed under the ducts.
In-formation concerning the location of these intersections can be obtained from DBR/NRC - Attention: G. H. Johnston, Geotechnical Section.
MODIFICATIONS TO CABLES NOS. 2 AND 3
The switch boxes for cables Nos. 2 and 3 were originally
placed at the edge of the shoulder of the parking apron and immediately
adjacent to the runway marker lights respectively (as described in DBR/NRC
Technical Note No. 360). Because both switch boxes would interfere
with construction and airport operations they were relocated on 17 to 19 May 1969 and were placed well down on the slopes of the fill prior to the start of construction (Figures 1, 2 and 4).
The lead wires for both cables Nos. 2 and 3 (24 thermocouple points - 2 lead cables containing 12 wire pairs at each installation) were extended by splicing 120-ft lengths of l2-pr thermo-cable (Shaw Flexible Tu.bes, Dekoron- 1820-01250, 20 gao Type M) to the ends of
the existing lead cables. The extension cables were placed inside
7 ft - 16 ft
1 ft below the fill surface across the shoulder and down the slope
(Figures 6 and 7). A 4-ft length of I-in. dia. plastic pipe was used
to cover each of the splices and connect the ends of the 3/4-in. dia. protective plastic pipes in which the :multi-conductor cables were threaded.
No changes were :made to the original ther:mocouple cable No.4 (runway centreline - east); its location re:mains as described in Technical Note. No. 360, and as shown in Figure 5.
CABLES NOS. 5 AND 6
Cable No. 5 was installed on 24 May 1969 in a 6-in. dia. auger hole drilled to a depth of 16 ft about 100 ft south of the runway
opposite the taxiway (Figures 1, 4 and 8). This cable was installed
to :measure te:mperatures in an undisturbed area and replaces original
cable No.1, which has been abandoned. The cable is fabricated of
12 -pr ther:mo-cable (Shaw Type) with ther:mocouple junctions at I-ft
intervals of depth fro:m the ground surface to 8 ft inclusive, and at
depths of 10, 12 and 15 ft. The cable was placed inside a 3/4-in. dia.
plastic pipe for protection. A 12 -pr Shaw cable threaded inside 3/4-in.
dia. plastic pipe was used to extend the wire s to the switch box (shared
with cable No.6) located on the south slope of the runway. The lead
cable was spliced to the ground cable about 5 ft fro:m the hole. The
lead cable was buried in a trench approxi:mately 1 ft below the ground surface between the hole and the toe of slope and about 1 ft below the
fill surface between the toe of slope and the switch box. The location
of the buried cable was :marked with flags and warning signs (Figure 8). No soil sa:rnples were taken as the hole for cable No. 5 was drilled but a visual exa:rnination of the auger cuttings gave the following soil profile:
0.0 ft - O. 5 ft - peat
0.5 ftCo: 7.0 ft - brownish-grey, dense stony. clayey silt
till - :many s:mall stones up to i in. and rando:m 6- to 9-in. cobbles, streaks of peat in top 3 ft
- rando:m irregular ice lenses up to i-in.
thick, s:maller (hairline) ice lenses throughout - grey, stony silt clay, rando:m 6- to 9-in. cobbles - occasional thin (hairline to 1/16 in.) ice lenses
4
-From the 7 -ft depth to the bottom, the hole was backfilled
around the cable with fine rock dust and fine crushed rock. Between
the surface and the 7 -ft depth auger cuttings were used. The
back-fill was well tamped for the full depth of the hole and the living mos s
cover and peat were replaced on the surface. At the time of installation
(24 May 1969) the ground was frozen from the surface down - no thaw had occurred.
Cable No. 6 was installed on 6 August 1969 in a 6-in. dia. hole drilled, using a rock bit and air drill, near the centre of the south
shoulder of the runway opposite the taxiway (Figures 1 and 4). It was
drilled through the crushed rock fill (9. 6 -ft thick) with little difficulty,
to a depth of 15 ft below the original ground surface. Following
in-stallation of the cable the hole was backfilled with well tamped, fine
crushed rock ＨｾＭｴｯ i-in. sizes) and rock dust. The material penetrated
by the drill could not be identified as no cuttings were brought to the surface.
The ground temperature and lead cable were fabricated of one length of 12 -pr Shaw thermo-cable placed inside a 3/4-in. dia. plastic
pipe for protection. Ground temperatures will be measured at the
original ground surface and at depths of 2, 4, 6, 8, 10, 12 and 15 ft
below and 2, 4, 6 and 7 ft above the original ground surface. The lead
cable was buried about 1. 5 ft below the surface of the shoulder and slope in a trench excavated from the hole to the switch box.
T AXIWA Y INST ALLA TIONS
Between 21 and 26 May 1969, i. e., prior to construction activity, lead wires for the thermocouple strings (cables Nos. 7 and 8) - Shaw 12-pr thermo-cable, and heat flow transducers (HFT -1 and -2)
- 20 gao duplex copper, to be installed in the taxiway, were threaded through protective plastic pipe (various lengths of i- and 3/4-in. dia. pipe) and buried in a trench from 1 to 2 ft below the surface of the rock fill across the shoulder and along the slope from 15 to 20 ft from the edge of the shoulder between the instrument site and the RCMP hangar
(Figures 1,2, 9, 10 and 11). At the same time the specially fabricated
thermocouple strings (24-gauge, copper-constantan duplex wire) were placed to the desired depths in hand dug holes on the taxiway centreline and the centre of the adjacent west shoulder and spliced to the appropriate
lead wires. All were carefully backfilled and buried to protect them
On 9 August 1969 a 1 -ft square hole was cut through the asphalt pavement on the taxiway centreline and heat flow transducer HFT-l (Thermonetics Corp. Model No. Hll-18-5-P, Serial No. S-103)
was connected to the appropriate lead wires. At the same time the
upper points on thermocouple string No. 7 were repositioned to the
correct depths. The hole in the pavement was then backfilled with
well tamped crushed rock and hot mix asphalt. On 11 August 1969
the crushed rock covering the lead wires at the west shoulder site was removed and heat flow transducer HFT-2 (Thermonetics Corp. Model No. Hll-18-5-P, Serial No. S-106) was connected to the appropriate lead wires and the top points of thermocouple string
No. 8 repositioned in the fill. The excavation was then carefully
backfilled with crushed rock. Both heat flow transducers were
bedded in Ottawa sand (a i-in. layer below and a I-in. layer above
each meter) to provide protection. Details of the thermocouple
strings and heat flow transducer installations are given in Figure 3. In late July the remaining length of lead cables, which had been buried in a trench as far as the RCMP hangar in May 1969, were placed in a trench by the contractor along with airport lighting cables; this trench was located between the hangar and the west end
of the airport terminal building. In early August the cables were
tacked to the wood piles supporting the building and brought up through holes in the floor (well caulked) into the weather office where they were connected into recorders provided by DBR/NRC.
Two recorders, mounted on a portable rack, have been placed in the DOT weather office in the terminal building to monitor the
ground temperatures and heat flow at the taxiway site continuously. The six points in each of cables Nos. 7 and 8 and the temperature of each heat flow transducer (a total of 14 temperature measurements)
are recorded on a Leeds and Northrup Speedomax Type G; 20-point
chart recorder (Cat. No. 60000, Serial No. 1201532). The output of
the two heat flow transducers are recorded on a Leeds and Northrup Speedomax Type H chart recorder (Cat. No. 3-32-000-084-6-01, Serial No. 58-1013-10-072-1-1).
FROST DEPTH INDICATORS
Several years ago four methylene blue frost depth indicators
were fabricated and installed by DOT at the airport. Indicator A was
placed adjacent to thermocouple cable No. 1 at the original undisturbed test site in October 1963 and indicators B, C, and D were installed in
6
-the runway in September 1964. Frost indicators B, C, and D ceased
to function properly and were abandoned in 1969. Two new frost
in-dicators were installed by DOT on 28 August 1969; F.!. -2 at the west end of the runway and F. I. -3 at the junction of the taxiway and the
parking apron (Figure 1). F. I. -1 (previously identified as A) will
continue in use at the original undisturbed site. Details of the
instruments and their installation can be obtained from Construction Branch, Air Services, Department of Transport, Ottawa, Ontario.
SUMMARY OF INSTRUMENTATION AND OBSERVATIONS
Ground temperatures are measured to depths of 15 ft below
the original ground surface and from 6 to 7 ft above the original ground surface, i. e., in the rock fill, at cables Nos. 2, 3, 4 and 6 and to 15 ft below the ground surface at cable No. 5 (replaces No. 1 - now
abandoned) in an undisturbed area. Observations are made weekly
us-ing a portable temperature indicator provided by DBR/NRC and are recorded on Form N-l (Figure 12, revised August 1969) which gives details of the position of the thermocouple junctions in the ground for each cable.
Temperatures are measured to depths of about 3 ft below the surface of the pavement and rock fill at cables Nos. 7 and 8 placed on
the taxiway centreline and adjacent west shoulder respectively. The
temperature of and the output from two heat flow transducers (HFT-l
and -2) placed with these cables are also measured. Data from the
cables and the transducers is monitored continuously on chart recorders located in the DOT weather office in the airport terminal building.
Daily maximum and minimum air temperatures and precipitation records are obtained from the standard observations made at the DOT weather station.
Weekly observations of snow depth are made at temperature
cables Nos. 5, 6 and 8. A graduated painted stake (2- x 4-in. wood),
which can be read visually from the edge of the runway, has been
placed at cable No.5. Graduated rulers are used to measure the
depth of compacted snow on the shoulders at cables Nos. 6 and 8. All snow is removed from the paved runway and taxiway.
ACKNOWLEDGEMENT
The assistance and cooperation received at the site during the installation of the instrwnentation in 1969 from Mr. L. Borowski, Resident Engineer, Construction Branch, Department of Transport and members of the survey crew; Mr. B. MacNeil, airport manager,
and his staff; Mr. Gordon Dye, C.I.C. Weather Station and his
e
e
e
CABLE No2 CABLE No4 CABLE No3
PARKING APRON RUNWAY-EAST END RUNWAY-WEST END
BUR'ED CABLE
.0
40 lO
vEATIC"l StAl,.E IN FEET
HORrlOHT"Il SUH IK fH l 10 ｉｾ 12". CIIUSHED ROCK MAX. SIZE - 6· 2tl 10 0 IB9-3
ＮＮＢＮＢＬﾷｴＧＧＧＬﾷＢＬＬﾷＬﾷｾｯｾ " 'w'." ORIGINAL GROUND SURFACE
CABLE No 7 CABLE No 8 IAXlm ·3"; ASPHALT PAVEMENT 199·9 .4@6" r:"'--'\,I'
ｬＳｾＺ
2' ! 3'ELEVATION· DATUM - LOW WATER LEVEL, EAST CHANNEl AT INUVIK, 1954 CABLE No 5 UNDISTURBED AREA ＮＮＭＺＱＸｾＺＳ ｉｃｾＮ eT -2' 2' 2.11,...-194.0 ｾ 2' 2' 2' 2' 2' 3' CABLE No 6 RUNWAY - SHOULDER (AL.N!l.J) 1'2036 z' 2' 2' S' 5' 2·5' 2·5' 1'20S'4 :: ,("214-7 5' :..:..THERMOCOUPLE 2'I r JUNCTION 2' ｾＳＭＵ 2'5' 2'S' ｾＢＭＧｾＧｾＧ
...
"" ｾＧＲ s' s' 2' 2' ORIGINAL GROUND-l..! SURFACE 2S' , 2'5' ＳＧＱｾ ASPHALT ('98'8 ｐａｖｅｍｅｎｔｾＧＢ " .':'.',' ',.' 12" CRUSHED ROCK---r"
/r '
MAX SIZE -I"; . 'CRUSHEDｒｏｃｋｾｉ MAX. SIZE - 6' F.I.-I ('A)
ｎｏｉｾ
s.c4l[IfFHT ｯＧｾ .r---BURIED CABLE '? ':' No5 0 0I
1-1 Li•
0 $ '0 ｾY(fl-nc.Al SC...l.E IN FEU
ｬｾｲ
.,
ｾ GROUND TEMPERATURE ｃａｂｌｅｾ ..• _ . . . _ . _ . . . · · ' 0\
Not,2,364 -INSTALLED IIARCH 1957. A- INSTALLED OCT. 1963. 18+50--t No 1- ABANDONED AUGUST 1969. B,caD-INSTALLED SEPT 1964.ｾ
BURIED CABLE--J
ｎＰＲｾＱ
No 5 • INSTALLED MAY 1969. B, caD - A8ANDDNED 1969. BURIED CABLE N06 -INSTALLED AUGUST 1969. 263- INSTALLED AUG. 1969.
.
r\-·EI'
0 No 7a 6-INSTALLED AUGUST 1969. -N-I 6 +0 0 ---;ｾ
0 g No8--j 0+ 0 0 0 0 0 0 .; HFT-2 0 0 0 '? 0 '?r--. IS"TC"
ｾ
+ + • ... en 0 0 0 0 0 0 ""I
- No 7.../ BOX=
ｾ !2 ::!: ｾ !£ ｾI I HFT-I , I SWITCH BOX
ｾ
.}..r " / .f.-BURIED CABLE 75'I---SHOULDER ｾ... ..F.l.-C
I"FI.-2 '101+00 iNo3 . 150,I-PAV_EMENT .--1. Fl.-D
. -FL-B 'I BURl!oCABLE- Nn4 ..}-J.- oNo6 1-. !""---SWITCH BOX 2Obfoo 0 100 400 .00 BOO t - - -TOF OF SI OPF -_. --
---FIGURE I NRC GROUND TEMPERATURE INSTALLATIONS-INUVIK, N.W.T. AIRSTRIP
PARKING
APRON
SHOULDER
EDGE OF PAVEMENT
BUILDING
CABLE No 7
a
HFT -I
83'
l/CABLE No 2
f-17+73 \ \\-...--BURIED CABLE
\ \(
FI -3
\
17'5' \£!J
v/l'ｾＬＮ '"",",'..oU.I...ｾｾＮＮＮＮＺＮＮＮＮＺＮＮＮＮＮｾＮｬＭｉＮｾＮ ':..:..'';..L,'.u.'T''.:..:.'•.-:,...133'
WITH RUNWAY
CABLES IN THIS
SECTION)
102,7'ｾ 105,0' .: . 103'6' . , " 19 +00 ---+--, I I 18+50 -I
I
I
18+00 -I
I
I
I
16+00 -I
I
I
1 " I I 1 I I ' • IHANGER
2 BURIED
ｃａｂｌｅｓｾI
17+00 - II
I
14+00-I
15+00 -I
CABLE No 8
a
HFT
-2
I
14+46,4-L
106,0' 50' 75' - 50'f
,TAXIWAY
100 i 50a
100 SCALE IN FEET 200 !FIGURE 2
75' PAVEMENT SCALE IN FEET INSERT
o
2 4 6 8ｾｾｩｭｎＧＸｴｴｳ
PLANo
5 10 15 20---"'"
I
+
TO TERMINAL BUILDING----
--CABLE No 8 8 HFT -2 CABLEＣＸｾ
"Q"
4 "....t..1
1 4" HFT·2?
HFT LEAD 50' SHOULDER.1
---- ---- ---- ---- ---- ----
---, CABLE No 78 HfT-1 : 14+43'0 14+46·4 TAXIWAYI.
CABLE No 8 198·9"
. " . <l 0 6" I" 0 0 6" CRUSHED 612 " " ROCK 0 0 " 6""
MAX. SIZE - lY2
6"
•
HFT-2
"
0 "BEDDED IN <> 0 0 0
6" OTTAWA SAND 0 • 0 6"
I"ABOVE 6 0 HFT-2 LEADS
1/2' BELOW <> 0 0 6" 0 ' C ' 6" 0 0 CRUSHED <> THERMOCOUPLE ROCK 0 , LEADS 0 6" MAX. SIZE - 6" <> 2" 0
ｾｔｈｅｒｾｏｃｏｕｐｌｅ
JUNCTION 12" ,..-199'9;1
2L
ｾｊ ' " ' ' • ., ,-, " ｾ ASPHALT 3 2ＢＧｾ
.. jｾ ｛ＢｾＧＢ
. : • • • • •ｾ
, , ",0 . 0 ..' : 0 .;:.-, ' 0'"
T - I -"
" 0 -"
" . l--HFT-I LEADS DDED IN " CRUSHED ｾ ."
0 - DTAWA SAND ROCK o. "
"
•"
" I"
ABOVE 6 • MAX.SIZE- 1Y2 .
"
0 IBELOW..
0 " o\.. 0 0"
0.
<> 0 \ · 0 b 0 . 0 " THERMOCOUPLE 0 LEADS 0 0 CRUSHED 0ｾｔｈｅｒｍｏｃｏｕｐｌｅ
.
ROCK 0 -MAX.SIZE-6" 0 JUNCTION 0 I 0 0 0 "" <>,
HF BE OT I" 1/2 CABLE No 7 o 189·3 ORIGINAL GROUND SURFACE SECTIONSo
r-. 5-..,.10 SCALE IN FEET100
ＭＭＭＭｾｉ
RUNWAY EDGE OF SHOULDER EDGE OF PAVEMENT TOE OF SLOPE EDGE OF PAVEMENT EDGE OF SHOULDER SCALE IN FEET 50 0, 100,
---100' CABLE No 5 IRON PIN-BASELINE.,../' >-ｾ ;:: x ｾＭＭＭＭＭＭＭＭＭｾＭＭｾＭＭＮＮＮＮｌＭ｟｟｟ｊ［｟｟ＭＭＭＭＭｌＭＭＭＭＭＭＭＭ
ｾ I L[) r-:.. r<") + o 10 r<") 10 1 .-10"+
I N-
-10 ... =1 -rt') ... + " (Tl 0, II
-
' I ,.
, I BURIED CABLEｾ 10 1 ...ｉｾＭ
10+00 CABLE No 3':'rf-1/2' 0 r:- 0 -10 <:T -10 r-.!. (Tl 10 r-I r I • I , , 1-.'+ -· 0 -U)PLAN
FIGURE 4
(r (
.
,. , ,.
,,
Ｌｾ 60' CABLE NoＴｾ｟
to RUNWAYI"-ｉｾ
--
ｾｉ
I I l"-N to EDGE OF PAVEMENT7 co I Cl l"- I"-I,
..
. . . , .. , .. I',·" t ' I . I ' " \ .,..
, , t I ·I , .....
I ' . ' "f'." 1'" I ｾＭSHOULDER -'It"t:: BURIED ---l ": LIGHT
0
EDGE OF SHOULDERj7 CABLE I 0
to + l"-I l.D I 'It" 100 i 50
a
, SCALE IN FEET 100 Iｾｓｗｉｔｃｈ
BOX lO + W 'It"PLAN
of parking apron.
Figure 7 - Extending leads for cable No. 3 across runway shoulder. Note that leads are placed under 2-in. dia. runway lighting cable duct.
Figure 8 - Cable No. 5 located at tripod - buried lead cable rn.arked by signs and flags.
Figure 9 - Leads for cables Nos. 7 and 8 and HFT-l and -2 in trench along taxiway slope.
in trench along taxiway slope.
Figure 11 - Leads for cables Nos. 7 and 8 and HFT-l and -2 at corner of RCMP hangar - before being extended to terminal building (to the left, not shown in photo).
INUVIK N.W.I AIRSTRIP
GROUND TEMPERATURES
(OF)OBSERVER _
DATE _
#5-AREA
#2
#3
#4
UNDIST URBED+
DEPTHTSWITCH DEPTH PARKING RUNWAY RUNWAY #6-RUNWAY
POINT (FT) APRON WEST END EAST END (FT) SHOULDER
I 15 15
2
1512
3
1510
4
10
0B
510
76
10
6 7 5 5 8 54
9 53
10
2·5
2
II2·5
I12
2·5
0
13
0
1514
0
12
15
0
10
16
-2
8
17-2
6 18-2
4
19 -42
20
-4
0
21
-4-2
22
-6
-4
23
-6
-624
-6
-7SNOW DEPTH
#2
1Y3
#4ｾ
#6REMARKS
1&
FROST INDICATORS)FIGURE 12
NOTES:- 0 TEMPERATURE IN JUNCTION BOX - 11/2 FT BELOW PAVEMENT SURFACE
+
DEPTH BELOW ORIGINAL GROUND SURFACE. NEGATIVE SIGN INDICATES ABOVE ORIGINAL GROUND SURFACE liE. IN ROCK FILL)CABLE #5 (INSTALLED MAY 1969) REPLACES #1 (ABANDONED) CAB LE #2,3,4 - INSTALLED 1957
CABLE # 6 - INSTALLED AUGUST 1969
NORTH ERN RESEARCH GROUP DIVISION OF BUILDING RESEARCH NATIONAL RESEARCH COUNCIL FORM N-I (REVISED AUG. 1969\
