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HomeMy WebLinkAboutSnow Load Monitoring 1998Alaska Idustiel Doveimpment end Export Authority DRYDEN &LaRUE,INC. P.O.Box 111008 ANCHORAGE,AK 99511-1008 (907)349-6653 Stan Sieczkowski AIDEA 480 W.Tudor Rd. Anchorage,AK 99503 O Anchorage-Fairbanks Intertie Snow Load Monitoring System Tower Alert Investigation No.98/99-04 Date:12/24/98 Tower(s):5 to 79 Some of the towers being monitored by the SLMS had been in alert status since the snow storm that caused an outage on the line on December 15,1998.On the morning of Dec.16,1998,the SLMS reporteda center phase inclination on tower 14 as 4.636°above normal with a snow load of 255 Ibs. and for tower 23 the center phase inclination was reported as 12.77°above normal with a snow loadof212Ibs.Tower 59 had a center phase inclination of 8.61°above normal with 490 Ibs.of snow. The line was investigated on Dec.16,1998 and clearances of 20'and.15'were estimated at spans 24- 25 and 57-58 respectively.These apparent low clearance conditions were not deemed critical by MEA linemen and no snow was cleared from the lines.On the morning of December 24,1998,thecenterphaseinclinationontower14was10.74°above normal with a load of 550 Ibs.and the center phase inclination on tower 23 was 12.52°above normal with a load of 405 Ibs::Although these inclinations had not changed much over the week,other phases on these towers had shown largeinsulatorswingsassociatedwithunloadingevents.The loads reported by the instruinented towers had been gradually building since Dec.16,1998 presumably due to icing condition'(See attached graphs of loads and angles for Dec,16 through Dec,24,1998 for towers 5,14,23 &79). Since relatively low clearance conditions were already observedin the area and loads had graduallyincreasedsincethattime,it was decided to make a line patrol-before the Christmas holidays andassociatedbackcountrytrafficwasencountered.The patrol was to only cover the section of line from tower 1 to about tower 50 based on observations made in the last field investigation.On the morning of December 24,1998,tower 79 phoned the base station with a load alarm of 1380 lbs. above normal.This section of line would also require patrolling: Summary: Field Trip Report 12/23/98 We monitored the SLMS on December 23 &24,1998 (See attached tabulations of loads and angles *" for December 23 and 24).On Wednesday December 23,1998 we attempted to patrol the line via helicopter.Tom Bassler of Dryden &LaRue,Inc.and pilot Lambert DeGaverre left Anchorage at 12:05 p.m.after the fog had lifted slightly and flew to Palmer to pick up Steve Pakhula,.The fog was very thick all the way to the Palmer airport.We picked up Steve and left at 12:32 p.m.We flew to Douglas substation where the fog picked up again.We flew to about tower 4 and the pilot turned around because it was too foggy.Very little snow was evident on the lines.The static wires and down guys did have significant frost buildup on them (Photo 1-1 to 1-5).On the return trip the Palmer airport was also fogged in so we dropped Steve off behind Wendy's in Wasilla and returned to Anchorage.All of Anchorage was covered with dense fog.We landed at ERA in Anchorage at 2:05 p.m. Anchorage-Fairbanks Intertie Snow Load Monitoring System December 29,1998 Tower Alert Investigation No.98/99-04 Page 2 Field Trip Report 12/24/98 On Wednesday December 23,1998,ML&P again coordinated a field trip for MEA and us to fly the line on Thursday December 24,1998. On Dec.24,1998 Tom Bassler and Kelly Hill of Dryden &LaRue,Inc.went to ERA Helicopters at Anchorage International Airport where ERA pilot Brian Carlin had an ASTAR Helicopter ready to leave.At 10:00 we departed for the Palmer airport.When no one was found at the Palmer airport we landed at MEA's Palmer office.We then learned that we were supposed to go to MEA's Big Lake office.We arrived at MEA's Big Lake Office at 10:52 and picked up Mark Lee,an MEA lineman.We left Big Lake at 11:00 a.m.. From Big Lake we flew directly to Douglas substation.From Douglas we flew north along the Intertie usually flying on the east side of the line.We planned to fly to tower 79 first,note all line conditions on the way north and land at the problem spots on the return trip for clearance measurements and line unloading. From Douglas substation to tower 14 there was little snow on the lines.The static wires were generally evenly covered with frost.The insulators were snow covered with some ice on top presumably due to melted snow from the tower (see photo 1-8).There was little snow or ice on the towers.Low clearance conditions were noted around tower 53 and tower 14 that would be addressed on the return trip. From around tower 55 to tower 65 there was no snow on the lines. The phase conductors around tower 79 were all fairly evenly covered with about 2-4"of radial snow. The static wires were evenly loaded with frost to about 3 times the diameter of the static wire.This frost appeared to be very light as the sag in the static wires was only a few feet.The insulators at tower 79 were all plumb.It was determined that since no low clearance problems existed,and clearing any snow would require clearing all spans,not to clear the lines at tower 79. We landed between tower 51 and 52 at 11:36 p.m.We investigated an apparent low clearance condition on the center phase of span 53-54.The clearance of the center phase in this span was measured with the Extendo stick as 16'-11"from the center of conductor to the top of snow.The snow depth was measured as 24".The diameter of snow on the west subconductor was measured as 14"and 10"diameter on the east subconductor.The snow was apparently remaining from the earlier snowstorms.The entire span unloaded after a light tap from the extendo stick.The clearance was measured with the Suparule as 54'from conductor to top of snow after unloading.The shield wire was loaded with about 3 times its diameter of frost for the entire span (photo 1-18). The west phase of span 51-52 was also relatively low.We estimated the clearance at this span to Anchorage-Fairbanks Intertie Snow Load Monitoring System December 29,1998 Tower Alert Investigation No.98/99-04 Page 3 be about 30'.Since there was a clearing around this span we backed up to see the behavior of the conductor after unloading.The conductors jumped up after unloading to an estimated height of even with the tower crossarm (see photo 1-17).The two spans south of this span also unloaded at the same time.We left at 12:25 p.m. The next apparent low clearance area investigated at span 13-14.We landed at 12:34 p.m.The center phase clearance was measured as 27'-2"from conductor to top of snow with a Suparule and 27'-3"to top of snow with the extendo stick.The snow depth was measured as 18".The snow diameter was measured as 16"on the east subconductor and 12"diameter on the west subconductor on the center phase.The other phases were sparsely loaded with snow (photo 2-1).We left at 1:00 p.m. We next investigated tower 23 due to a center phase inclination alert.The conductors around tower 23 did appear to have about 1-3"of radial snow on them but the center phase insulator on tower 23 was plumb.(Photo 2-6). The lines south of Douglas substation were clear of snow.The trees south of Willow were all clear of any snow.Fairly high winds were encountered from Willow to Palmer. We then flew directly to MEA's Big Lake office where we dropped Mark off at 1:15 p.m.and continued back to Anchorage where we landed at 1:28 p.m. CC:Doug Hall,ML&P Stan Sieczkowski,AIDEA Victor Willis,MEA Paul Risse,CEA Monte Ervin,GVEA TLB:briclients\mea\MEASLMS trip report 98_99-04 12-24-98.wpd Photo Descriptions Field Trip 12/23/98 and 12/24/98 Roll 1 12/23/98 1-1.Span 2-3 west phase 12/23/98 1-2.Span 2-3 west phase 12/23/98 1-3.Span 2-3 west phase 12/23/98 1-4.Span 2-3 west phase 12/23/98 1-5.Fog 12/23/98 12/24/98 1-6.Tower 79 north 1-7.Tower 79 north 1-8.Tower 80 east phase 1-9.Span 80-81 east phase 1-10.Tower 53 looking west 1-11.Tower 54 looking west 1-12.Tower 55 looking west 1-13.Tower 56 looking west 1-14.Tower 52 looking west 1-15.Span 53-54 looking north 1-16.Span 53-54 looking north 1-17.Span 53-54 looking south 1-18.Span 53-54 center phase 1-19.Span 53-54 center phase O 1-21. 1-22. 1-23. Roll 2 2-5 O 2-6 Span 51-52 west phase after unloading Tower 13 east phase Tower 14 east phase Tower 15 east phase Span 13-14 looking south Span 13-14 center phase Span 13-14 center phase,with 9"glove Tower 14 snow accumulation Tower 14 Tower 23 looking west Dryden LaRue,Inc. O ANCHORAGE FAIRBANKS INTERTIE SNOW LOAD MONITORING SYSTEM Line Status Sheet Relative to normal Actual Readin StationNum SampleTime |Eastincl Centerincl Westincl Load BatteryVolts BatteryTemp |Airlemp 5 12/23/98 4:00 -3.429 -2.12 6.971 510 12.14 13.60°|10.94 ° 14 12/23/98 4:15 1.944 7.881 11.94)444 12.2 13.65 °}11.18 ° 23 12/23/98 4:30 9.19 12.66 0.75|353 12.23 14.06 °}6999.00 ° 32 12/23/98 5:00 -3.418 2.931 6.977}723 12.24 14.35 °|11.63 ° 41 12/23/98 5:15 -4.801 0.17 -1.985}817 12.23 14.64 °|12.46 ° 50 12/23/98 5:30 -6.322 -1.207 -6.44|665 12.2 14.47°|12.08 ° 59 12/23/98 4:00 -2.928 7.8 2.863|620 12.17 13.77 °|12.56 ° 69 12/23/98 4:15 -0.982 2.056 2.064|716 12.28 14.13 °|12.32 ° 79 12/23/98 4:45 1.468 0.171 0.982|1276 12.27 14.41 °}11.95 ° 90 12/23/98 5:00 -2.942 2.439 0.939]417 12.22 14.51 °}|11.66 ° 98 12/23/98 5:15 1.765 2.934 -2.138]760 12.21 13.53 °|11.50 ° 109 12/23/98 5:45 2.731 -1.234 7.424)435 12.22 14.49°|11.56 ° 120 12/23/98 4:00 -0.617 3.859 -3.666|510 12.16 14.72°|16.83 ° 129 12/23/98 4:30 4.947 -0.084 6.043]287 12.24 14.69°}11.73 ° 140 12/23/98 4:45 0.231 0.441 5.855]294 12.23 6999.00°}11.30 ° 150 Missed 159 12/23/98 5:30 4.634 1.493 1.186}277 12.21 14.89 °|11.13 ° 168 12/23/98 5:45 4.789 3.276 3.525}313 12.22 14.15 °|10.99 ° 181 12/23/98 4:15 -0.229 -0.093 0.057 1 12.14 15.81 °|12.12 ° 191 12/23/98 4:30 -0.635 2.502 -0.307 -10 11.96 13.89 °}12.65 ° 203 12/23/98 4:45 -0.15 1.065 -0.266 12 12.16 14.83 °|11.75 °O 213 12/23/98 5:15 0.738 0.617 0.66 2 12.24 14.31 °|11.22 ° 222 12/23/98 5:30 -0.026 3.181 0.218 0 12.2 15.56°|12.64 ° 12_23_98.xIs Page 1 12/28/98 Dryden LaRue,Inc. O ANCHORAGE FAIRBANKS INTERTIE SNOW LOAD MONITORING SYSTEM Line Status Sheet Relative to normal Actual Readin O StationNum SampleTime |Eastincl Centerincl Westincl Load BatteryVolts BatteryTemp {AirTemp 5 12/24/98 6:00 -0.493 3.043 -2.368{585 12.03 -10.36 °]-13.80 ° 14 12/24/98 8:15 3.567 10.74 0.118|550 12.11 -9.31 °|-13.04 ° 23 12/24/98 6:00 -0.679 12.6 0.75}399 12.13 -9.87 °|6999.00 ° 32 12/24/98 6:00 -3.037 3.007 -3.477|893 12.15 -8.59 °|-13.95 ° 41 12/24/98 6:00 -4.652 0.184 -1.828|978 12.12 -10.43 °}-13.66 ° 50 12/24/98 6:00 -5.894 -0.93 -4.958}806 12.09 -10.08 °]-13.65 ° 59 12/24/98 6:00 -0.619 7.69 0.512]685 12.06 -12.46 °|-15.32 ° 69 12/24/98 6:00 -1.513 1.971 2.04)825 12.33 -7.59 °|-15.39 ° 79 12/24/98 6:00 1.521 0.212 1.064]1372 12.17 -10.87 °|-12.44 ° 90 12/24/98 6:00 -3.048 2.491 1.095}513 12.11 -8.56 °|-10.73 ° 98 12/24/98 6:00 1.02 3.016 -2.274|786 12.11 -9.95°}-9.44° 109 12/24/98 6:00 2.257 -1.25 7.872|492 12.1 -6.73°|-8.84° 120 12/24/98 6:00 0.569 4.547 -2.249]521 12.12 '3.54 °}11.16 ° 129 12/24/98 6:00 3.156 -0.822 3.854 3 12.21 6.44°| -0.72° 4140 12/24/98 6:00 0.249 0.137 0.721 21 12.2 6999.00 °}11.19 ° 150 missed 0 0.00 °0.00 ° 159 12/24/98 6:00 0.885 1.636 0.41 12 12.21 16.03 °|26.54 ° 168 12/24/98 6:00 2.051 1.57 2.139 -7 12.21 19.40°}|25.76 ° 181 12/24/98 6:00 0.023 -0.092 0.18 4 12.16 21.30 °|26.42 ° 191 12/24/98 6:00 -0.004 2.875 0.166 7 11.97 20.12 °|29.89 ° 203 12/24/98 6:00 -0.144 1.062 -0.161 6 12.17 22.58 °|27.82 ° 213 12/24/98 6:00 -0.137 0.313 -0.089 -9 12.26 25.22 °|27.78 ° 222 12/24/98 6:00 -0.275 2.438 0.012 13 12.2 23.42 °|26.20 ° 12_24 98.xls Page 1 12/28/98 14fe€&Load (Ibs)Nagnal 3365 Ibs &a 3 3 ie 3 3 00SS12/16/98 4:00 12/16/98 8:15 12/16/98 12:30 12/16/98 16:45 12/16/98 21:00 12/17/98 1:15 12/17/98 5:30 12/17/98 9:45 12/17/98 14:00 1217/98 18:15 12/17/98 22:30 12/18/98 2:45 12/18/98 7:00 12/18/98 11:15 12/18/98 15:30 12/18/98 19:45 12/19/98 0:00 12/19/98 4:15 12/19/98 8:30 12/19/98 12:45 12/19/98 17:00 12/19/98 21:15 2/20/98 1:30 3220/98 5:45 #/20/98 10:00O£/20/98 14:1512/20/98 18:30 12/20/98 22:45 12/21/98 3:00 12/21/98 7:15 12/21/98 11:30 12/21/98 15:45 12/21/98 20:00 12/22/98 0:15 12/22/98 4:30 12/22/98 8:45 12/22/98 13:00 12/22/98 17:15 12/22/98 21:30 12/23/98 1:45 12/23/98 6:00 12/23/98 10:15 42/23/98 14:30 12/23/98 18:45 12/23/98 23:00 12/24/98 3:15 12/24/98 7:30HOMO|LweyS0JOMOLwa}skgBuvoyUuO;Wpeo}Mousalyoju;syueque.4-aBesoyouy12/24/98 11:45 So N -o Inclination (°) Normal E=-0.25°,C=0.45°,W=-1.35°sonK)9-v-aJOUNSAAA-=JOULJOJUBDaneaewepuysey----peo]--- 12/16/98 4:00 12/16/98 8:30 12/16/98 13:00 12/16/98 17:30 12/16/98 22:00 12/17/98 2:30 12/17/98 7:00 12/17/98 11:30 12/17/98 16:00 12/17/98 20:30 12/18/98 1:00 12/18/98 5:30 12/18/98 10:00 12/18/98 14:30 12/18/98 19:00 12/18/98 23:30 12/19/98 4:00 12/19/98 8:30 12/19/98 13:00 12/19/98 17:30 12/19/98 22:00 2/20/98 2:3012/20/98 7:00 12/20/98 11:30 #2/20/98 16:00 12/20/98 20:30 12/21/98 1:00 12/21/98 5:30 12/21/98 10:00 12/21/98 14:30 12/21/98 19:00 12/21/98 23:30 12/22/98 4:00 12/22/98 8:30 12/22/98 13:00 12/22/98 17:30 12/22/98 22:00 12/23/98 2:30 12/23/98 7:00 12/23/98 11:30 12/23/98 16:00 12/23/98 20:30 12/24/98 1:00 12/24/98 5:30 12/24/98 10:00 :w nn Load (Ibs)Negmal 3365 Ibs a3 o0ssfp)JamMoLInclination (°) Normal E=1.25°,C=-2.15°,W=-0.05°ObZbJOUNS@AA-»-JOUPOJUID)aeeeenejouyseg----peo]----bHEYDsnje}sJaMoL MOL weyos12/16/98 4:00 12/16/98 8:30 12/16/98 13:00 12/16/98 17:30 12/16/98 22:00 12/17/98 2:30 12/17/98 7:00 12/17/98 11:30 12/17/98 16:00 12/17/98 20:30 12/18/98 1:00 12/18/98 5:30 12/18/98 10:00 12/18/98 14:30 12/18/98 19:00 12/18/98 23:30 12/19/98 4:00 12/19/98 8:30 12/19/98 13:00 12/19/98 17:30 12/19/98 22:00 42/20/98 2:30 12/20/98 7:00 £2/20/98 11:30#2/20/98 16:00 12/20/98 20:30 12/21/98 1:00 12/21/98 5:30 12/21/98 10:00 12/21/98 14:30 12/21/98 19:00 12/21/98 23:30 12/22/98 4:00 12/22/98 8:30 12/22/98 13:00 12/22/98 17:30 12/22/98 22:00 12/23/98 2:30 12/23/98 7:00 12/23/98 11:30 12/23/98 16:00 12/23/98 20:30 12/24/98 1:00 12/24/98 5:30 12/24/98 10:00 00SZWw gi Load (Ibs)"gna 2885 ibs &3 o0ssbod £7JOMOLwajysksHuoyuoyypeo]MousS-ms fe>)oe Inclination (°) = o Normal E=-.05°,C=1.65°,W=-0.75°ZhylJOUPJO}UDD)weeaneceejouysey----peo]--$--alvajuysyuequie4aBesoyouy LvueO son12/16/98 4:00 ¢ 12/16/98 8:15 12/16/98 12:30 12/16/98 16:45 12/16/98 21:00 12/17/98 1:15 12/17/98 5:30 12/17/98 9:45 12/17/98 14:00 12/17/98 18:15 12/17/98 22:30 12/18/98 2:45 12/18/98 7:00 12/18/98 11:15 12/18/98 15:30 12/18/98 19:45 12/19/98 0:00 12/19/98 4:15 12/19/98 8:30 12/19/98 12:45 12/19/98 17:00 12/19/98 21:15 of 2/20/98 1:30 12/20/98 5:45 £2/20/98 10:00 B/20/98 14:15 12/20/98 18:30 12/20/98 22:45 12/21/98 3:00 12/21/98 7:15 12/21/98 11:30 12/21/98 15:45 12/21/98 20:00 12/22/98 0:15 12/22/98 4:30 12/22/98 8:45 12/22/98 13:00 12/22/98 17:15 12/22/98 21:30 12/23/98 1:45 12/23/98 6:00 12/23/98 10:15 12/23/98 14:30 12/23/98 18:45 12/23/98 23:00 12/24/98 3:15 12/24/98 7:30 12/24/98 11:45 00SZ2g Load (Ibs)"gna 3285 Ibs ZoJaMOL-9pp oO Inclination (°) Normal E=.45°,C=1.05°,W=0.65°JOUNSAAA=2226poupayuey--f[OUNSEQ=ow©ompeo)waj}sksBuvoyUoWypeo]MouSalyejuysyueqie4-ebesoyouy IweydOoonosO sank12/16/98 4:00 12/16/98 8:15 12/16/98 12:30 12/16/98 16:45 12/16/98 21:00 12/17/98 1:15 12/17/98 5:30 12/17/98 9:45 12/17/98 14:00 12/17/98 18:15 12/17/98 22:30 12/18/98 2:45 12/18/98 7:00 12/18/98 11:15 12/18/98 15:30 12/18/98 19:45 12/19/98 0:00 12/19/98 4:15 12/19/98 8:30 12/19/98 12:45 12/19/98 17:00 12/19/98 21:15 of 2/20/98 1:30 312720198 5:45 #2/20/98 10:00 32/20/98 14:15 12/20/98 18:30 12/20/98 22:45 12/21/98 3:00 12/21/98 7:15 12/21/98 11:30 12/21/98 15:45 42/21/98 20:00 12/22/98 0:15 12/22/98 4:30 12/22/98 8:45 12/22/98 13:00 12/22/98 17:15 12/22/98 21:30 12/23/98 1:45 12/23/98 6:00 12/23/98 10:15 12/23/98 14:30 12/23/98 18:45 12/23/98 23:00 12/24/98 3:15 12/24/98 7:30 12/24/98 11:45 00SZLoad (Ibs)Neal 2945 Ibs &3 00ss62JaMOLN Inclination (°) Normal E=0.65°,C=0.05°,W=-0.25°[OUNISAA,---JOUPAUADawwnanJOULJSe™peo}wiayskgBuuoyUoyypeoMouSaiyeyuysyuequiey-ebesoyouy agi;4ay2gfi eS Nee aSAS ,"wes eamt:eee”"t.BINYS -DAKS .pte beeeadiwe,;peda Poy i Span a-3$Nest J I-4 AYES 294 Tos eee 4 =asyeoa Sse ; -= ny@+Hoyht?Tw yee ee Pepe,Ne wid Tower 53 |East & ea.,creer?owes =.wg?wt:"yesRdt wie *wy oe ar ' >er phpeieoh dahypealtHNL,NS: East &Tower Slo | S7an 53-54- I-'9\cosreSene3,LoAReeeUBFstcatesSeAgeeaeteeRRSaaraypenne) Tower 14 ] EAoTD eeenaedet se eee meme cane om oa"-AP FO -aclaey te ee a fyat f p YZLNI)[_bt-% Yee = |oe< ae BAe we 7 er tee eee perenne TS wee O Anchorage-Fairbanks Intertie Snow Load Monitoring System Tower Alert Investigation Date:12/7/98 Tower(s):All Most towers being monitored by the SLMS had been in alert status since December 4,1998.Towers 5,50,90,and 98 had insulator inclinations ranging from 12°to 18°above normal.Loads for these towers ranged from 950 to 2,400 lbs above normal. Summary:Field Trip Report 12/7/98 We monitored the SLMS from the beginning of the storm on December 3,1998 (See attached tabulations of loads and angles for December 4,5,6 and 7).On Monday,December 7,1998 ML&P coordinated a field trip for MEA and us to fly the line. Tom Bassler and Al Peabody met at ERA Helicopters at Anchorage International Airport at 10:00 a.m.where ERA had pilot Brian Carlin and an ASTAR Helicopter ready to leave.At 10:20 a.m.we departed for MEA's Big Lake office.We flew across Knik Arm and CEA's Pt Mackenzie to West Terminal and Pt.Mackenzie to Teeland lines.The wires on both lines were bare. We arrived at MEA's Big Lake Office at 10:40 a.m.and picked up Butch,an MEA lineman.He brought snowshoes for Tom and an extendo.We left Big Lake at 10:55 a.m. From Big Lake we followed the Parks Highway to where the Teeland to Douglas 138-kV line crosses.From there we followed the Teeland to Douglas 138-kV line to Douglas substation. Conductors were bare all the way to Douglas Substation,but there was some snow or ice on the wire around where the dampers attach. From Douglas we flew north along the Intertie usually flying on the east side of the line. The east insulator at tower 3 was swung south (see photo 1-1).At tower 5 the insulators were also swung back (see photo 1-2).As we flew north,the east phase looked like:Tower 6 swung south, 7 swung 1 bell south,between 8 and 9 wires clear,bells plumb at 9,10,11,and 12,swung two bells north at 13,span between 13 and 14 loaded with snow.Bells at 14 plumb and at 15 and 16 swung one bell to the south.At tower 23 bells were approximately plumb,at tower 32 the wires were bare or lightly frosted,bells at tower 41 were approximately plumb. The east phase between towers 52 and 53 was heavily loaded and appeared low.At 11:22 a.m.we landed to the east near mid-span.The distance from the top of the snow on the ground to the top of the snow on the wire was about 19 feet and to the middle of the snow on the wire about 18 feet 5 inches.The overall diameter was estimated to be 10 inches with 4-3/8 inches between the snow covering each wire.The snow had not bridged between the sub-conductors.Butch tried to scrape a bare spot with the extendo to show the shape but the scraping unloaded the whole span around 11:45 a.m.Brian saw the wire jump from off to the side and said that it appeared to rise to a little above "straight and level".The snow was powdery.Snow on the ground was a heavy powder.The Anchorage-Fairbanks Intertie Snow Load Monitoring System December 7,1998 Tower Alert Investigation Page 2 snow depth was approximately 22". At 11:54 am,we continued flying north.A stream between 56 and 57 had an open lead -most of the streams we crossed had open water showing. The bells at tower 69 were relatively plumb.The span from 76 to 77 had snow on it.The bells at 79 were almost plumb.There was a snow machine trail along the distribution line that crosses the intertie north of tower 79;but no snow machine tracks parallel to the intertie. The west phase was loaded and appeared low between 96 and 97 and the east phase was loaded between 97 and 98 (see photos).We landed near tower 98 and walked back to approximately mid span where we measured the diameter of the accretion as being approximately round and 10 to 11 inches in overall diameter.The clearance above the snow to the wires was 19 feet 3 inches and the snow depth was approximately 23 inches.Measurement of clearance was also taken with a Suprarule ultrasonic cable height meter.It measured the clearance as 20'-5".One of the snow covered conductors showed some scalloping.The normally east sub-conductor was twisted over and on the west side.After making the measurements and taking pictures we walked to tower 97.There is a creek south of tower 97 that was iced over but had only a dusting of snow on most of the surface. The ice was not thick enough to cross the stream.We returned to mid-span between 97 and 98. Butch used the extendo to unload all three phases -it barely reached the center and west phases.He was able to shake the west phase hard enough that it unloaded between 96 and 97 also.The snow here was also powdery and all came off with one good shake.When the east phase was unloaded, the bundle untwisted also.Phases were unloaded at approximately 1:20 p.m. We continued north at 1:37 p.m.The span between tower 107 and 108,north of Future Road,was heavily loaded but did not appear to have a clearance problem.In some spans we could hover off to the side even with the wire and read an approximate height with the helicopter's ground proximity sensor.Three or four spans south of Stevens substation,there was also a heavily loaded spans,but the insulators at each end of the span were relatively plumb. The largest swing angle we saw on a center phase was at tower 127 (see photos).We landed at tower 150 at 1:55 p.m.to see if there had been any damage to the conduit from the solar panels.All of the solar panels and the conduit and wires into the data logger looked OK.We did not open either of the cabinets (last year the conduit from solar panels was ripped loose from battery box).We then flew north as far as tower 300.From about 159 on the wires were almost all bare.There were a few spans with small snow accretions.We then flew to Talkeetna where we landed to refuel at 2:40 p.m. We left Talkeetna at 3:05 flying directly to MEA's Big Lake office where we dropped Butch off and continued back to Anchorage where we arrived at 3:45 p.m. We do not remember seeing any loaded shield wires or guy wires.The crossarms and tower legs typically had snow on them in the areas where the wires had snow.We could not read any tower numbers in the area with snow on the lines and had to keep track by checking numbers when we passed towers with instrument systems. On returning to the office in Anchorage,we called Carolyn in dispatch to report on our findings. Roll 1 1-10. 1-11. 1-12. 1-13. 1-14. 1-15. 1-16. 1-17. 1-18. 1-19. 1-20. 1-21. 1-22. 1-23. 1-24. Roll 2 Photo Descriptions Field Trip 12/7/98 Looking west at tower 3 Looking east at tower 5 Wires between towers 4 and 5 Looking west at tower 50 Looking west at tower 51 Looking west at tower 52 Looking south from between towers 52 and 53 Looking north from between towers 52 and 53 From 53 looking back From 53 looking back Looking up at the east phase at tower 53 Looking up at the east phase at tower 53 Looking up at the wires between towers 52 and 53 Wires between 52 and 53 after unloading. Looking west at tower 99 Looking west at tower 98 Looking west at tower 98 Looking west at tower 97 Looking west at tower 96 Looking west at tower 96 Looking west at tower 95 Looking south from tower 98 towards tower 97 Looking up at east phase tower 98 West phase of tower 98. From mid-span between tower 97 and 98 looking south at tower 97 Looking up at east phase at mid-span between towers 97 and 98 From mid-span between tower 97 and 98 looking south at tower 97 From mid-span between tower 97 and 98 looking north at tower 98 Looking at east phase between 97 and 98 with some of the snow scraped off 2-9 2-10 2-11 2-12 2-13 2-14 2-15 2-16 2-17 2-18 2-19 2-20 2-21 2-22 2-23 2-24 2-25 Roll 3 3-10 3-11 3-12 3-13 Measuring the snow on the east sub-conductor with a folding rule taped to an extendo Measuring the snow on the west sub-conductor with a folding rule taped to an extendo Measuring the distance between snow covered conductors of east phase between 97 &98 Measuring the distance between snow covered conductors of east phase between 97 &98 Measuring the snow on the east sub-conductor with a folding rule taped to an extendo Measuring vertical thickness of snow with folding rule pushed through the snow accretion - rule had just been visible through the top. Withdrawing the rule from the snow accretion looking at wire after scraping some snow off the west sub-conductor of the east phase between towers 97 and 98 (the face of the scraping tapers towards the camera). looking at wire after scraping some snow off the west sub-conductor of the east phase between towers 97 and 98 Looking up at west insulator of tower 97 Looking between 97 &98 phase West phase between 97 and 98 after unloading Bad picture Location not recorded Location not recorded Tower 127 looking west Tower 127 looking west center phase between 126 and 127 was loaded Tower 5 facing east. Bad Picture Tower 50 facing west Tower 50 facing west Span 50-51 facing north Tower 51 facing west Tower 52 facing west Span 52-53 facing north Span 52-53 facing north Span 52-53 facing north Span 52-53 facing south Span 52-53,east phase Tower 99,facing west 3-14 3-15 3-16 3-17 3-18 3-19 3-20 3-21 3-22 3-23 3-24 3-25 cc: Tower 98,facing west Tower 97,facing west Tower 96,facing west Tower 95,facing west Span 99-98,facing south Span 99-98,east phase Span 99-98,east phase Span 99-98,east phase Span 99-98,east phase Span 99-98,east phase Span 99-98,facing south Span 99-98,east phase Bob Drake/Victor Willis,MEA Doug Hall,ML&P Stan Sieczkowski,AEA Monty Ervin,GVEA . er Vey re vos eel E wt Ne 7.ie .eee Peete ie ates 5 be res.Seer er RNSanatCOCeecyVi:Or .rat woeeheaE pegFGN?IW:ale iter ;ay .net i NamedSymfraat .aa 5%Onna YpketyAelapcene!Seeda5eroe6tweeryem,ye a weyERDARRGxeepriseee'4aeDeyTR¥n4oyrexVat7idaalroe7%,pe ee =_ eae?mass 7 pe:ino i CoM Danek bin of tee ey ny Me ae we tieyIOPtboohiRDacneeeBlabyMatwearteneitiesoadAldbidseftTalaxwURfigeeFiatAutMeiscmltonstkcandeOPEYnserlecon"XPaabedeadTe Aye :oewhNt"papas Bea Mh : ¥ waebeoediate ial'+Hola O pants:PQA eins _ (MOOVOSTSE parser agin y : DAD see baw - i , ' ar f us ; -_-. ° ° Loeeny 887 ;-_ms Had ye ' .t an s cage HE ENRIS ae.wet . i I p ses 'i ema snes ener:.ROTM mo os .AT,eepOoad Leaemal TL Peer a *. 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