Exhibit 74 - Meterology Research - Technical Reports · 2011. 9. 30. · L L 4 METEOROLOGY RESEARCH...

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METEOROLOGY RESEARCH INCTECHNICT REPORTS:

MRI 74R1255:

I

wind and ice loadings for a portion ofthe

Gull Island Transmission Line.

A meteorological evaluation of the conthined

Sept 20, 1974

Revised wind and ice loadings for a Portion

of the Gull Island Transmission line.,

Jan 30, 1975

MRI 75 FR-1378: The follow on meteorological evaluation

of the proposed Gull Island TransmissionLine network.

Muskrat Falls Project - Exhibit 74 of 116

karsimcr

Typewritten Text

Reference 1 (4)

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c_.D i' c C. . - . -

I nstructions to Prepare Site Visit Report Forms

a. General Conditions

1. Site Number or Location

2. Date: Month, day, and year.

-'-/ -.. o ''

3. Time: Times of start and finish of observation.

Use 24-hour clock and local time.

4. Sky Cover: Tenths of cloud cover, such as or "fog".

5.. Cloud Height Above Site Level: Estimated height in feet.

6.' Wind

a. Direction: By sector, such as, WNW

b. Speed: In miles per hour.

,c, Indicate whether taken from chart or measured

with hand set.

.Temerature: In degrees Fahrenheit. Indicate whether

from chart or psychrometer.

8. 'Relative Humidity: In percent. Indicate whether from

chart or psychrometer.

9.. Precipitation: Type and intensity of precipitation, if any,

occurring at time of observation, such as, 5--.

O. Icing Rate Meter Reading: Record both the chart and

dial readings.

b. 'Boxes: Complete boxes for three or more positions along

horizontal span and two or more, inluding top, along vertical

span.

K :Photo Numbers: Number rolls and exposures cOnsecutively

from start of program. Write 22nd roil, 13th exposure as

2213. If more than one picture taken at that spot, record

them all, e.g. 22-13, 14, 15.

2. Overall Shape: Record as circular, oval, pennant-west,

irregular; or very irregular. Always indicate direction

pennant is pointing.


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3. Dimensions: Measure with calipers where possible;

otherwise, check 'testimated". Give diameter for cir-

cular shape. Give greatest and least dimensions for

oval. Give length and greatest width for pennant. Amplify

under Remarks.

4, Character of Ice: Record one description from each of

the following columns Describe in more detail in Remarks,

rnooth Clear Hard

Rough Opaque Medium Hard

Mitüre Mixture Soft and Crumbly Frost

5. Conductor Visible? Enter yesor no plus remarks, such

a's, yes, fairiry, through smallest dimension.

: Density: Enter approximate density obtained by specified

'technique. This will vary from about 0. 2 for very soft

rime to 0. 9 for clear, hard ice. Enter only for those loca-

tions actually, measured,

?.Layers; When layers can be identified, enter approximate

thickness and the character (from table above) of each

layer. Start with that nearest the conductor. If no apparent

layers, so indicate and give character of innermost and

out&rmost portions.

. Remarks

.1, General Photo Numbers: Record roll and exposure numbers

olpictures not covered in data boxes. If there caii be any

question describe what picture is of.

2.. Shape and Dimensions: Add amplifying remarks on shape

and dimensions and how they vary along the conductor. We

can reconstruct only as well as you describe.

3. Character: Md amplifying remarks on the character of

the ice and how it varies along the conductor.


4, Ice on Towers: Describe the structure of any ice on the

towers: shape, dimensions, character. Does it fill the

tower interior? Does it encase the MWS?

5. Ice on Guys: Describe ice on guys the same as for towers.

6. Snow Depth and Character: Record average snow depth and

character; e. g. , .wet and heavy, hard packed, drifted, etc.

7. General Remarks: Add Additional remarks about ice on

surrounding trees and shrubs.

d, Ge

1•,

2.

3.

4..

ieral Instructions:

• Draw line from cross sectionto data box that describes

ft.and to location along the corductor,

Include dimensions on all cross sections.

Indicate distance from end or top for each cross section.

Measure dimensions with. calipers whenever possible.

4


- - Photo £rtbcru: - j... um - , , ,, ...catL... • , A1i Shape: / '2 1 vcz-fl Shape: C VAL Overall si tpc: C / , . t' /A, Datop./ J77.2 Time: Start 07Jt5 Finish -

CaIipet or Est. ; Calipers _______ or Est. )' Dim; C*liper ' or Eiit. Scy Cover: f Cloud Mgt. Above Site Level: Z c' ,c:.17ctcr of icc: Character of icc:

________

Ci-acLer of icc;.

__WD: _______ WS: /.j. C}art________ or Mcasurcd )?L ,4 ed. R,u Lg.ue I_ R j.k .________ Tcmperaturc:Z.L.F Chart orMcasured )(

,ctor Ylaiblo? Wô Condt..(or Viibl? ,1/. Conductor Viiblc? IVo .

_Rd. Humid.: Q4O Chart_______ or Measured

____________________________ Dcnty; . Density: _____________________________Prccip. 4/e))7e UtM Reading: (Dial) .2"(Chart) (0_

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Shapc and Dimcnaloa: A4A'es AnLLy - •..

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V/&, V .-,27 °0v41_Chactcr:p&//4//r I t/ Ve7, L$ . V. V

£7E47 TiYA /1 L Na ,r' /IceonTowerz:L,j, //.:p o ,t// 7weis. . . -

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• XceoaCuya:.5af-.7 j$pr See -. t' /7 . V

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Ccaeral Rcmarka:2j/O7$ . /LJ(/ r4qF.Iae...

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Atchment I • - SITE \TISI REPORT • -

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- I 1• ,ere. ________________ Phoc, L'umbers: ___________________

_______________________________

____

______ -

Photo Nun, .': _______________________ biLe o. or Location:. •

all Shape: _________________________ vcra1l Shape: __________________________

.

Overall Shape: - -. Dao: .

.

Time: Start _________ Pinish-

CaUpcr ________ or EeL. -- Dim: Cali?cra - or 25t. _______ Dim Calipers - or Est. ________ Sky Cover: - Cloud flat. Abovc Site Level: _____________

acter of Ice: Clrr*ctor of icc: Character of lee:. WD: _________ WS; _________ Chart________ orMeasured _______

_______ ___________ __________ ____________ ___________ __________ ___________ ___________ _______ Tcmpcrnurc: - F Chart_______ or }icasured ______

actor Vi1blo? __________________ CncJtot Visible? -. Conductor VisibIc? ___________________ Rd. }Iumld.: _________% Chart ________or Measured _______

________________________________ Dantity: .Density: Pcci;. : IRM Rcadin: (Dial) • (Chart).________________________________ - ______________ ______

s: .4ucKncb .L.aycrs: A ctness LiaracLcr L.ayers; J.iuc:rc53 cHaracter

1 _________ -• 1• ________ 1 _________ _________

2 _______ ______ 2 _______ ______ 2 _______ _______

3 . ______ . 3 _______ ______ 3 _______ ______

______________ _____________ 4 ______________ _____________ 4 .- - •

1tEMAR}(S: •

Cencrl photo Numbers: ______________________________________

Shape and Dimen2ieas: _____________________________________

Character: _________________________________________________________

Ice on Towers: -

Yr. ., r.1,u,.

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0

0

__________________ I •• 0

Snow Depth L Character: - / _______ .

CccrclRcmarka;_ . . : 7.,• -,

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Lttacbrnnt 1 SITE VISIT REPORT 'ORM

Photo Numbers: _________________________

Dye rail Shape: __________________________

Dim: Calipers ________ or Eel. _________

Character at Ice:

Conductor Visible? ____________________

Density: -

Layers: •Thlckncss Character

a _________________ __________________

3 _____________________ ______________________

4 _________________ _________________

Photo NIlrnberG: _______________________

Dvcrall Shape: ___________________________

Dim: Calipers _______ or Eat. ________

Charictur at Ice:

Conductor Visible?_____________________

Dcnalty.:

Layers: TMckncss Character

.2 _______ _______

3 -•


- -- '

If\_______

mootjy research, inc. 464 w. voodbury rti • alta(kfla, calif.

30 January 1975

- ........ - ......... 911 fl4 1027

rrE657. AIt.'n

Ctt(. ¶tUOtD' 2 I.oi

Mr. Art . . . .

Teshrnont Consultants, Ltd.225-2025 Corydon AvenueWinnipeg, ManitobaR3P 0N5Canada

Dear Art:

Attached are five copies of the summary of the revised return periodvalues of transverse wind loads and winds associated with icing storms.These values were obtained by reviewing hourly weather records for

(-\ several_daj after icing ceased. All values of icing given in theseptember, 1974 report remain the same.

If you have any questions about these results or need any additionalinformation, please give me a call.

Sincerely,

• PrRonald J. cMmer

RJB/cm

Enclosures

- .• I ..4 •Meteorologist.

IL Li

FEI3 1q75 .

I•,,.

• • ..


REVISED COMBINED WIND AND ICE LOADINGSFOR A PORTION OF THE

GULL ISLAND TRANSMISSION LINE

During the analysis of weather recrds for eastern Newfoundland,only winds occurring during or up to six hours following icing stormswere considered in deriving transverse wind load of Ice-coveredtransmission lines, Subsequent conversations with Art Hannah, HarveyYoung, and lunar Reinart, raised some doubt that all of the strongestwinds will occur within this time span when ice remains on the conductorsand towers. Microfilmed hourly records were analyzed to determinewhen the maximum transverse loads did occur.

The new criteria was quite simple. The highest wind speed duringeach icing period (or following it if the temperature remained belowfreezing) was recorded. If the temperature rose well above freezing, itwas assumed that all of the ice melted; winds occurring during or afterthis period were not considered. This was done for periods up to fivedays following each icing storm,

Table 1 •shows the results of extending the period of observationfrom six hours to five days following the storms, The first columnindicates the number of storms investigated in the 19 years between1953 and 1971, The second column shows the number of storms wherethe maximum wind speed and thus the maximum transverse wind loadremained unchanged from the previous study. The third column shows thenumber of questionable increases in wind speed. The question lies in theuncertainty of whether or not the ice remained when the higher windsoccurred. Occasional periods of temperatures in the range of 330 - 380 F

lasting several hours may have been sufficient to melt the ice. When thehigher winds occurred, however, the temperature was below freezing.The final column shows tie number of storms where the wind speed washigher than that which occurred up to six hours following the storm.

New return period values for both St. John's-Torbay and Ganderwere calculated for both transverse wind load of glaze and rime-coveredtransmission lines and maximum winds associated with icing storms.These results are presented in Tables 2 and 3. The wind speeds in thequestionable category were included in the new calculations. The numberin parentheses are those values presented in the September, 1974 report.

It can be noted that in many cases the new values are actually lowerthan those in the previous report, despite wind speeds that were equal toor greater than those.usd previously. This results from the theory and


method used to develop return periods and described by Weiss (1955).The extreme values for each year are listed, and the means and standarddeviations are calculated. The return period values (denoted by X)are obtained from the equation: -

X = +SKxn,t

where is' the mean of the extremes, S is the standard deviation ofthe extremes, and K isa constant detrmined by the period of recordn and the return peri'd T. -

It was found from examination of the microfilmed data that the lowerannual extreme values were usually increased by extending observationsto five days following the storm. However, those highest extremes thatwere found during the September, 1974 study (in several cases exceeding50 mph) remained unchanged. This would result in a higher value ofX but a lower value of S,, since the range of extreme values decreases.The value of K, ranged' from approximately 1.65 (for a 10.-year returnperiod) to 3. 5 (for a 75-year return period). Thus the standard deviationcan be a critical parameter. In this current study, the effect in severalcases was to decrease the slope of the return period plot, and although thelower end of the plot would result in higher values for return periods lessthan 10 years, values for longer return periods were in many instanceslower than those given in the earlier report.

Return period values of maximum icing winds and winds combinedwith maximum ice loads were again extrapolated to line segments andpresented in Tables 4 and 5. These values are for sustained winds; windgusts can be estimated by multiplying the results by the gust factor of 1.5.Segment numbers refer to those used in the September, 1974 report anddescribed in the original meteorological study of November, 1973. Allicing values derived in the September, 1974 report remain unchanged.

There seemed to be a general rule of thumb concerning the time. ofoccurrence of maximum wind speeds after icing storms. If the maximumwinds did not occur within the storm or a few hours thereafter, then theyusually occurred within 24 hours following the occurrence of glaze icingand -48 hours following rime icing. There were some exceptions, generallyat St. John's, where average wind speeds are high. Even these exceptionsextended the time of the maximum winds only another 24 hours. Alterthese time periods either the wind speeds decrased or the temperatureincreased, thus melting the ice,


REFERENCE

Weiss, L. L,, 1955: A nomogram based on the theory of extreme windsfor determining values for various return periods.. Mon. Wea. Rev.,83, 69-71.


V

St. John's Glaze

St. Johns Rime

-! Gander Glaze

Gander Rime

Table 1

No. of Number Number NumberStorms Unchanged Questionable Chan

37 28 3 6

41 32

28 14 3 11

41 27 3 11


Table 2

TRANSVERSE WIND LOADS (lbs/lineal ft.)FOR ICE-COVERED T/L (2. 0-inch Diameter 'Conductor)

Result from September, 1974 Report in Parentheses

GANDER ST.JOHN'S

ReturnPeriod(years) Glaze-Covered Rime_Covered* Glaze-Covered Rime-Covered*

10 1.5 (1.2.) 2,0 (2,0) 1.7 (1.7) 3.6 (3.6)

25 1.9 (1.4) 2.4 (2.5) 2.1 (2.1) 4.5 (4.6)

50 ' 2.2 (1.7) 2.7 (2.7) 2,4 (2.3) 5.1 (5.3)

75 2.4 (1.8) 2.9 (2.9) 2.6 (2.5) 5.5 (5.7)

*Adjusted to '300-ft above station elevation.

Table 3

RETURN PERIOD VALUES FOR MAXIMUM SUSTAINEDWIND SPEEDS (mph) ASSOCIATED WITH ICING STORMS

Results from September, 1974 Report in Parentheses

GANDER ST. JOHN'SReturnPeriod ,

(years) Glaze Storms Rime Storms Glaze Storms Rime Storms

10 42 (36) 46 (46) 45 (41) 54 (54)

25 48 (40) 52 (54) 51 (47). 61 (62)

50 . 52 (43) 57 (58) 56 (52) 67 (69)

75 54 (45). 60 (61) 58 (55) 70 (72)


Table 4

RETURN PERIOD VALUES FOR MAXIMUM SUSTAINEDICING WIND SPEEDS (mph) EXTRAPOLATED TO LINE SEGMENTS.

Results from September, 1974 Report in Parentheses

Segment Ret ur n P eriod, Yea r s

Number 10 25 50 75

1 " 51 (51) 59 (60) 65 (66) 69 (70)

54 (54) 61 (62) 67 (68) 70 (72)

3 46 (47) 53 (54) 61 (62) 65 (66)

4 53 (54) 61 (62) 67 (68) 71 (72)

2.0 53 (54) 61 (62) 67 (68) 71 (72)

Table S

RETURN PERIOD VALUES FOR MAXIMUM SUSTAINEDWIND EPEEDS (mph) ASSOCIATED WITH ICING,

EXTRAPOLATED TO LINE SEGMENTSResults from September, 1974 Report in Parentheses

Segment Ret urn P er io d,. Ye ar s

Number 10 25 50 75

1 40 (40) 44(44) '( 47 (48) 72. 49 (50)

2 43 (43) 47 (47) 50 (51) 77 52 (53)

3 3 (36) 40 (40) (. 44 (44) t'C 46 (46)

4 43 (43) 47 (47) Y) 51 (51) •i7 53 (53)

20 43 (43) 47 (47) Y? 51 (51) 7? 53 (53)

Note: Wind gusts can be estimated by multiplying the above results

- by the gust factor of 1.5


INDUSTRIAL METEOROLOGY DEPARTMENT6 November 1974

Associate DirectorEnvironmental Meteorology

N. L, 1-lallanger

HAdministrative ManagerIndixstrial Meteorology

____ _______ B, R. Warr -________________

FSecretary 1 iMontrealOfficel

C. MarzanO' 1 1R.DChancenoLt

r'eiiant Transmission Special DataSurveys Lines Stuciies . Processing

I B. R. Warr M. Richmond I M. Weinstein I. ZifE

S. Marsh R. Boorner W. Moreland D. Brown

B. Macdonald T. Peters (pt) .- B. Rider

M. P•Z R Poyrier

I. Peters (pt) S .

W.Hodir1S RollinsC. SoeloE PoynterC SwanR. Hillcsiad

U[:LayayaG, BcsworLhS BristowF'L, i\O.

- . .- S CVeoD Nugent

Technical Deputy..

. _______________I

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1

TECHNICAL

REPORT

A METEOROLOGICAL EVALUATION•• OFTHECOMBINED WIND AND ICE

LOADINGS FOR A PORTION OF THE• GULL ISLAND TRANSMISSION LINE

MRII4R-1255• -

• Submitted to

Teshrnont Consultants Ltdb225-2025 Corydon AvenueWinnipeg, Manitoba R3P 0N5Canada

Date• SeptQmber 20; 1974

• • By: R. I. BoomerM... C.Richthond

• METEOROLOGY RESEARCH, INC.Box 637, 464 West Woodbury RoadAltadena, California 91001Telephone (213) 791-1901A Subsidiary of Cohu, Inc0


SUMMARY

I, INTRODUCTIONa

• II, SCOPE OF STUDY

IlL DATASOURCES .

IV. WIND DATAc

Va COMBINED WINDS AND ICING

A. Combined Wind and Glaze Ice LoadingsB. combined Wind and Rime Ice Loadings

• C. Combined Wind and Wet Snow Loadings

VI. TRANSVERSE WIND LOADING PR OBABILITIES FORICED TRANSMISSION LINES BY LINE SEGMENT

A. Loadings Derived From the November 1973 ReportB. Loadings Derived From Actual Storm Data

VII. COMBINED WIND SPEED AND ICE LOADS• BY LINE SEGMENT .

• VIII. CONCLUSIONS • .

REFERENCES

Page

1

2

3

.4

5

6

777

33.

3333

36


SUMMARY

A meteorological study was conducted to determine the extremevalues df transverse ice and wind loading likely to be experienced along.the proposed transmission line route between Holyrood and the northernHumber Valley. Analysis of data was in three phases: Completion ofbansverse ice and wind loadings for 10-, 25-, 50-, and 75-year returnperiods at six stations in Newfoundland; extrapolation of these values tothe proposed route; and comparison of the results with computationsbased on values obtained in the November 1973 report. Also looked at,ere loadings in conjunction with wet snow on the conductors.

Highest transverse wind loads generally occurred with rime ice,Maximum transverse loads are expected to reach 4.9 lbs/lin.e,axftin a

'' ; 25-year return period near' the isthmus. This is much less than the9.lbIjiear ft estimated in the previous ,report by assuming irule- ___pendence of individual maximum wind and ice loadings. If it is assumedthat wind gusts are 50,percent greater than the hourly wind values, thenthe maximum load becomes 11.0 lbs/linear ft'.

- ,- - 1'

Wet, snow will occur occassionally, but the associated loadings 'T(a.inaximum of 2.9 lbs/linear ft at Gander) are not great enough to bethe limiting design values.

• Combined wind and ice loads were computed using the winds andice as independent variables, but using only winds which had occurredduring orimm.tly following icing storms. These combined loads

- - based on hourly.winds were significantly lower than those derived inthe November 1973 report. Combined loads based on gst-condition

,. • ice-storm wind speeds were found to be quite. similar to the values in• the 1973 report which were based on annual maximum hour1 wind speeds.

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I, INTRODUCTION d," -

Teshinont Consultants Ltd., is in the process of designing. a ''transmission line for the Newfoundland and Labrador Power Commission;The proposed line will extend from the Gull Island Hydro Site southwestof Goose Bay-, Labrador to near Holy-rood on the Avalon Peninsula ofNewfoundland. This proposed route traverses some of the most severewind and icing areas known to exist in North America. In recognitionof the need for quantitative meteorological information on which to basethe design, Meteorology Research, Inc., (MBI) was commissioned tocoduct a meeorological-study of the proposed routes. This sdy was

- completed in November 1973, Combined wind and ice loadings wereexpressed as wind speeds in miles per hour with glaze and rime ice inradial inches and pounds of ice per foot of conductor. These values werederived by treating the maximum fee loads and maximum winds asindependent variables and using the same probabilities for each to developcombined probabilities. It was suggested in the 11 June 1974 meeting withrepresentatives of the Natural Energy Board and of Energy, Mines, and

• Resources that the winds and ice are, not always independent variablesand that using equal probabilities for each might not always result in therzrnximum load.

• •' A study was conducted to review the individual storm data forseveral Newfoundland stations, to determine at what point during the storm

• ' the nximnum transverse wind load would have occurred and what that value.5 was, and to develop return period values for the maximum combined

• loading's expressed in terms of transverse wind load on the iced Oonductor.This method of approach has the advantage of being based directly on actual

• - storm data and avoiding the debatable use of combined probabilities.

This report presents the results of that study. The scope of the• study is presented in Section II. Data sources are described in Section

III. The method of handling wind data is discussed in Section IV..• Combined wind and ice loadings at individual stations are analyzed in

• Section V, and the results are extrapolated to the proposed route andcompared with values obtained from the November 1973 report in SectionVI.' Section VII deals with treating individual wind and ice loads asindependent variables, where only those winds occurring during ice stormswere considered. Finally, conclusions are summarized, in Section VIII,

/

2


II, SCOPEOF STUDY

This transmission line study consisted of analysis of actual stormdata to determine potential transverse wind loads on ice covered trans.-mission lines proposed for eastern and centi.LNewfound1and, Themaximum transverse wind load on ice covered conductors which wouldhave occurred during or immediately following each of the glaze or rimeproducing storms identified in the climatologi.cal records were computedfor stations near the planned rute east of the Humber Valley. Themaximum transverse wind loading for'each year of record for each stationwas identified and return period probabilities developed. These values

ere then extrapolated to the route segments used in the November 1973study for comparison with the values derived by the joint probabilitymethod. Combined wind and ice loadings similar to those presented inthe November 1973 report, but based only on wind speeds recorded duringicing storms, were also derived and extrapolated to the route segments.

This portion of the route was selected for the study because theavailable station data are more representative of the route than the sectionsnorth and west of the Humber Valley.

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• •


III. DATA SOURCES

The basic data available for study of the proposed transmissionline route came from long-term records at a number of locations in thearea. Observations of wind speed and direction, temperature, precipita-.tion, and cloud conditions are reported by these stations to theAtmospheric Environment Service (AES), These data form the basis ofthe route study but are not normally available in the form required forthis type analysis. In previousprojects, theAES has developed f.o,rus special computer rograms to condense the long periods of data into moreuab1 forms for this analysis. These were used once again in this

• project.S

..........................

Listings o hourly observations during p4.potentia1accumu1a_.'5 tions of glaze ice, rime ice, or wet snow were generated by the AES. The

criteria used to generate these listings include:•

''

S .55.5 5

Rime icing: Cloud ciiig 1000 ft or Js..,.and ambient rtemperature 25 to 38°F (Only ceilings atbe1ow linelevelwere considered inthe actual analysis.)

Glaze icing Precipitation at or below 35°F (Only periods "

••.

of fcczingrairi wcrc ccriidcrcd in thc actual analysis.)

0 Wet snow: Temperature greater than 28°F with moderateor hy snow lasting at least hours.

• 3 all cases, these listings were continued for six hours followingthe last hour that met these criteria.- .

.5

The six stations for which data were analyzed and their length ofrecord included:

St'Joh&sTorbay, Nfld. 1953-1971 '

Argentia, Nfld. 5

1953-1969 •

Ga.nder, Nfld', . 5 1953-1971 '''

Buchans, Nfld. 1953-1964Deer Lake, Nfld, 1966-1971 -

Daniel's Harbour Nfld, 1966-1971 -

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-

IV. WIND DATA / -

/When used for maximum wind speeds, "hQiu1y.-wLnd values are

usually conserva'tive. The hourly-wind recorded in the hourly weatherosrvation consists of a one-minute average wind speed observed duxingthe 10 minutes pipr to tje hour. Thus; if the actual maximum one-minute average does not occur in that ten minutes, it is not recorded.Wind gust records are normally available only for locations with full scaleweather facilities.

Iii order to account for these gust values, a gust factor was employed,' equal to G/V, where G is the maximum gust speed and V is the maximum'

sustained wind speed. Many studies have been made to determine this gustfactor, whicj u.ally decreases with increas ingy.in&peed. Sissenwi.neet al.(1973) calculated gust factors that ranged from about L.3 for a one-

• minute steady wind speed of 20 knots down to 12 at 7,Qjcnts. 'Boyd(1970) developed a formula usefby the AES to calculate speeds of windgusts where••

+L29 V

This, or i1aresult in gust fac'tors ranging from l58 at Zknotstø l,7 at 70knots, For this study a constant gust facthr of .5 wasusel, ccihich would correspond to a steady wind speed according to BoycP sformula of knots, This was found to be typical of those wind speedsassociated with the highest transverse wind loads on the ice-coatedtransmission lines. - '

24 - --ci . - .- -

€; T

- -

-

• -l'-•••

-;' • -

' ',}

.5


'

- 4 t.

V.•. COMBINED WINDS ANDICING rr t

iTh 'i

Of extreme importance to the design engineer s the maximum - .-effect on towers and conductors resulting from the combined loadings .'

-of the weight of the ice plus the pressure of.the wind onthe increased .msurface area. The determination of this combined effect is complicatedin any specific case by several factors, The accretion rate of both glazeand rtme ice is a function of wind speed, the faster the wind, the morerapidly ice will build up To determine the maimum combination, it is

H necessary to know when during the storm the strongest wind occurred andhow much ice had accumulated at that time. If the strongest wind occurredearly in the storm, the greatest combined effect may have occurred laterwith a lesser wind speed and a greater surface area and weight of ice,Superimposed on this is the effect of wind direction both on accretion rte -•and transverse and longitudinal wind loadings. Going beyond this, wehave the problem of how long the ice can be expected to stay on thecorisiuctors. The longer the ice stá'yson,' the greater the vulnerability tohigh winds not associated wth the storm which caused the ice -

In the orj.ginal study a review of both the glaze and rime producingstorm per iod at the reporting stations revealed no pattern to the timewi%hin the storm period that the maximum wind occurred. The peak wipd

' 4.' i.-. el_s 1,, 4,_s ;_sel.rne ._ .

upto at least six hours subsequent to the termination of icing conditions,As was discussed in that report, how long the ice will stay on the conductorswill vary with each storm. In some cases, the temperature rises immedi.-aely and the melting and cracking process starts. At the other extrern,a'prolongédcold period niay result in the ice remaining for several daysor In orhe locations perhap,_weeks.

• DevIäp.ing return period probabilities for maximum combined windarid ice loadings is a necessary but controversial area of effort. Several•methods of arriving at these combined loading probabilities have beenproposed and used by various people with. no method being completelyaccepted as valid by all concerned. In this report, we have computed themaximum transverse wind load on the ice covered conductors which wouldhave occurred diring or i ediate1yiolloingeach of the glaze and rimeproducing storms identified. The maximum transverse wind loading foreach year was identified for the entire period of record for each stationand return period probabilities developed as had been done for maximumwind speeds, glaze icing, and rime icing in the November 1973 study.'The maximum combined wind and wet snow loadings that might haveoccurred over the entire period of record for each station were alsocomputed. Loadings were computed for winds being perpendicular to theconductors, Computations were based on the relationship ofW H = (0. 00Z5 V ) D/lZ ivhere W is the transverse wind load in. pounds

6.


per linear foot, V is wind speed in miles per hour, and D is the totaldiameter of conductor and ice in inches.

This method has the advantage of being based on actual cornbtned1a..ds.. rather than joint probabilities of yearly maximum winds and icingloa.cls occurring simultaneously. All computations were based on thewinds being perpendicular to a 2, 0-inch diameter conductor.

A. Combined Wind and Glaze Ice Loadings

Figures 1 through 6 show the return period plots of transversewind loads of glaze-covered transmission lines for the six stations based

• on hourly wind speeds.. Figures .7 through 12 are the corresponding plots• computed using wind c c _with heJ,5.gj,.st ctor. The

extracted values for 10-, 25-, 50-, and 75-year return periods are listedin Table L

On the return period plots for Bicha.ns (Figs. 4 and 10), the• 2.81 lbs/un ft value based on hourly winds and the 6.32 lbs/Un ft value

based on gust speeds (denoted by x1s on the plots) are from a Mçj24,1962 storm. The solid lines are drawn for all twelve plotted values.we eliminate those extreme values and plot the next highest values forthat year (1,41 and 3.17 lbs/Un ft, on February 12) the dashed lines resultand the March values become 1000-year storms, (Use of these graphs

In Tab1eI the values in parentheses•

. are from the dashed curves, - - . -

. .-."-- .-., - .-.•.•

c -.I • • • rB, Combined Wind and Rime Ice Loadings' - (• . • .•

,•,7flç, d--" (.':

Maximum transverse wind loads for transmission lines coatedwith rime were computed at specific elevations above the stations that are

• . representative of the proposed route. Figures 13 through 17 show thereturn period plots using hourly winds for 300 ft above St. John's-Torbay,

• . 300 ft above Gander, 300 and 800 ft above Buchans, and l0atabove..Daniel's Harbour. Figures 18 through 22 show return period plots usingthe-l.Sgustfactor. The extracted 10-, 25-, 50-, and 75-year returnperiod values are listed in Table II. . .

Cothbined Wind and Wet Snow Loadings

Iable• III lists the maximum wind and wet snow loading at,eachof the six stations, Wet snow is not expected to be a major problem inNewfoundland, Although several of the values in Table III appear high,there were only 20 occurrences of wet snow storms lasting at least sixhours among all six stations, eleven of which occurred at Argentia.

7


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Fig., 3, TRANSVERSE WIND LOADS FOR GLAZE-COVERED T/L AT GANDER, NFLDBASED ON HOURLY WIND DATA


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Fig. 71 TRANSVERSE W!ND LOADS FOR GLAZE-COVERED T/L AT TORBAY, NFLDBASED ON WIND GUSTS


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Fig. 9, TRANSVERSE WIND LOADS FOR GLAZE-COVERED T/L AT GANDER, NFLDA1T\ rVI\T xrrrT TIflP


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Fig, 10. TRANSVERSE WIND LOADS FOR GLAZE. COVERED T/L AT BUCHANS, NFLDBASED ON WINDGUSTS


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t? •.?flODAEILITY

• Fig0 12 TRANSVERSE WIND LOADS FOR GLAZE-COVERED T/L AT DANIEL'S HARBOUR, NFLDBASED ON WIND GUSTS


• Tablel

RETURN PERIOb VALUES OF TRANSVERSEWINDOADS FOR GLAZE-COVERED TJL

Location Return Period Amounts (lbs/linear ft)

10-year 25-year 50-year 75-yearSustained Wind Sustained Wind Sustained Wind Sustained Wind

Wind Gusts Wind Gusts Wind Gusts Wind Gusts

St. Joh&s-Torbay 1.7 3.6 2.1 4.5 2.3 • • 5.2 2.5 5.7

Argentia • 1.2. 2,5 1.5 3.3 1.8 • 4.0 1,9 4,5

Gander 1.2 2.6 1.4 3.2 1,7 3.7 1.8 • 4,2N0 J3uchans 1.9 4.2 2.6 5,8 3.1 7,0 3.4 7.7

(1. 1) (2.5) (1,4) (3.2) (1,7) • (3.8) (1,8) (4.1)

DeerLake 0.5 1.0 0.6 1;3 0.7 1,5 0,7 1,6

Daniel's Harbour 2.6 5,9 3,4 7.6 4.0 8.9 4.4 • 9.6


EXTREME PRO6!UTY PAPERRErurN PCtT)QD (Yeou)

..............

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TJ 1.2 1.3 14 L3 2 3 4 3 23 30____ i' •_.IL'_J ITfi TIT t

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Zoo • 2C.O 300 400 1000

h TI. ' 1 TITI. tiV

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10 '3 116 111 I . 31.1 993PT03ASI7..1TY ['-i.it)

Fig 13 TRANSVERSE WIND LOADS FOR RIME COVERED T/L 300 FT ABOVE TORBAY, NFLDBASED ON HOURLY WIND DA1A


-- ----------- - - - 2 _ --

; ..

EXTREME PROBABILITY PAPERRCJrM TfiOD (Y'r°

OGI L C .2 .3 i.4 l. 4 - 5 - 50 tOO - 200 300 400 ?.0O

2

1

,

Fit:i

t i r i• . l-T : •L:I: : T r: L - L :- £: :

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__i 4 fi 1 Jftt___ __ 1 1 1 , ± t -t--I---tTh -

•i . - - . 0 - 5 7 O - ? 3)0 - 99ProaiLLTy

Fig 14, TRANSVERSE WIND LOADS FOR RUVE COVERED T/L 300 FT ABOVE GANDER, NFLDBASED ON HOURLY WIND DATA - - - -.


............4

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4

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PRO0A1ILITV

Fig. 15. TRANSVERSE WIND LOADS FOR. RIME COVERED T/L 300 FT ABOVE BtJCHANS, NFLDBASED ON HOURLY WIND DATA


r.I - -.

4'J . .

EX1REME PROBABILITY PAPERRCU1 PCtIO CVo,%)

.

...........

....................

...

..

•..; 3 3 LI 1.2 L 3.4 3.5 2 . 3 4 5 10 50 100 2c0 00 4QØ 13). 3000

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90 55 53 I7 55 993 ,zr ¶99

PRO8AILITY [ioo>-,,3

Fig4 16 TRANSVERSE WIND LOADS FOR RIME COVERE T/L 800 FT ABoY BUCHANS, NFLD •0

BASEDONHOURLYWINDDATA0


V 1 I I

..............

.......

.................

EXTREMEPROE31Efl L1TYPPER1unl rrcnnf) fYois

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=

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Fig. 17, TRANSVERSE WIND. LOADS FOR RIME COVERED T/L 1000 FT ABOVE DANIEL'S HARBOUR, NFLD•BASED.ON HOURLY WIND DATA . -


XsME -toB.wLri T PAPC

RETURN ('Dr)I .'CI I 01 1.1 1.2 !. 1.4 1.5 • 3 4 5 . 10 25 50

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-

Fig 18 TRANSVERSE WIND LOADS FOR RIME COVERED T/L 300 FT ABOVE. TORBAY, NFLDBASED ON WIND GUSTd


- -

: •:: i I 1.2 1.4 .3 2

C

"-1

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• EXTREME PROBM3?LITYPAPER -:

PIQD-(Yor) . .-- • • 2 50 100 200 C0 400 )0 lOGO

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Fig. 19. TRANSVERSE WIND LOADS FOR RIME COVERED TJL 3O FT ABOVE GANDER, NFLDBASED ON WIND GUSTS


; .

--,

,-,. . ..

:J . - .

. .. . . EXTREME PROBABILITY PAPERRE1u? rEr(W1) tyeats) •.d : LI z .3 1.4 L5 2 4 . 10 t .Z3 Q . tOO flo cO 400 G 1000

'0ET [fltfJrf -r ? r : - : : E i 49L4LLr' Lh11f L 'i J j'it 1i i iL, : I I ITh:L' : IIHII 4 H i:JTT1F

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Fig0 ZO TRAN\tERSE WIID LOADS FOR RiME COVERfl P/ --

BASED ON WTNTh

:.i ..; .

LLE--;i"irri

9L1 11


FF ! r .

•. EXTREME PR..OBAB1ITY PAPER

. fETU8U PtIUQL) (oor).

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PROaADIL1TY [-i4.4;]..

. -

Fig. Z11 TRANSVERSE WIND LOADS FOR RIME COVERED T/L 800 FT BOVE BUCHANS, NFLD -

BASED ON WIND GUSTS


r' F•• :

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10

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9

8

7

6

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Fig. .2Z. TRANSVERSE WIND LOADS FOR RIME COVERED T/L 1000 FT ABOVE DANIELtS HARBOUR, NFLDBASED ON WIND GUSTS

t.Oo


- '--- -

Table II

RETURN PERIOD VALUES OF TRANSVERSEWIND LOADS FOR RIME-COVERED T/L

Location Return Period Amounts (lbs (linear ft)

10-year 25-year 50-year 75-yearSustained Wind Sustained Wind Sustained Wind Sustained Wind

Wind Gusts Wind Gusts Wind Gusts Wind Gusts

300 ft above Torbay 3, 6 8.2 4. 6 10. 3 5.3 11. 9 5.7 12; 8

300 ftabove Gander 2.0 4,5 2,5 5.5 2.7 6,3 2.9 6.8

300 ft above .Buchans 1.2 2,7 1.5 3.4 1,8 4,0 1.9 4.6

800 ft above Buchans 4.0 8.9 5,1 11.4' 6.0 13,4 6,4 14,6

1000 ft above Daniels Harbour 3.7 8.3 4.7 10.7

0

5.7 12,9 6.2 13.9


Table III

MAXIMUM TRANSVERSE WIND LOADSDUE TO. WET SNOWONONDUCTQRS

: Period of No. of Date of Duration Average Maximum Wet Snow TransvereLocation Record Wet Snow Maximum of Wet Wind Wiiid Diameter Wind Load

Storms > 6 Hrs Load Snow Speed Speed . (lbs/un ft)

Sustained WindYrs (hrs) (mph) (mph) (in.) Winds Gust

St. John's Torbay 19 2 5-1-55 6 35 '40 4.7 1.6 3.5Gander 19 4 3-5-60 9 41 45 6.8 2,9 6.5Buchans 12 1 3-19-64 6 33 37 4.7 1.3 3,0Daniel's Harbour 6 1 1-11-69 6 13 24 3.0 0.4 0.8

Deer Lake 6 1 10-23-69 7 20 20 38 0.3 0.7Argentia 17 11 12-18-65 6 39 46 5 1 2,3 5 1


VI. TRANSVERSE WIND LOADING PROBABILITIES OF ICE-COATEDTRANSMISSION LINES BY LINE SEGMENT

A, Loadings Derived From the November 1973 Report

In the November 1973 report, individual wind arid ice loadingswere assumed to be independent variables. Thus the probability of theiroccurring simultaneously becomes a product of their individual probabilities,

• For a given combined probability there are many possible combinationsoI individual probabilities, the product of which. would equal the selectedcombined probability. It was assumed that the probabilities of bothvariables were equal, and therefore the individual probabilities were. equaltd the square root of the combined value. The combined wind and iceloads (both glaze and rime) for the 10-, 25-, 50-, and 75-year return

- . periods at each of the five line segments between Holyrood and the northend of Humber Valley were used to compute the corresponding transversewind loads of iced transmission lines, Table IV lists these results,

B. Loadings Derived From Actual Storm Data

Table V lists the 10-, 25-, 50-, and 75-year return periodvalues for transverse wind loads based on actual storm data as extrapo-

• Jated to the proposed route. A comparison of glaze and rime ice loadingsiTables land II indicates that the transverse wind loads in conjunctor withrime ice is generally larger than that with glaze ice. Therefore the valuesin Table V are all associated with rime ice. The loadirgs for vcind gustsare also presented. The values computed frm the Noyember 1973 report(Table IV) generally lie between those values computed from hourly windsand wind gusts.

All_segment values have been computed for a level 80 feet abovethe most exposed terrain in the segment.• . • -•-•- •.-.-------. S.----

.-•--..

Z I

I ;:/1--' .

3.3


V - :---- r -

Table IV

TRANSVERSE WIND LOADS (lbs/linear It)FOR GLAZE AND RIME COVERED T./L

ASSUMING INDEPENDENCE OF WINDS AND ICING

Return Period i1 Years :.

ScgmeritNo. . 10 25 50 75.Glaze Rime Glaze Rime Glaze Rime Glaze Rime

1 Holyrood to Whitbourne(<500 It) 5.1 5,5 7.2 a.z . 9.2 10.6 10.1 12,2

2 VThitbourne to 10 miles S

west of Clarenville(<500 It) 6.9 6.9 9.4 10,3 11.7 13,1 12.9 15.6

3 10 miles west of Claren-. .

yule to Grand Falls(^8001t) 3.8 3.8 5.6 5.5 7.1 7.4 80 8.4

4 (800-1200 ft elevations .

west of Gander Lake) 5.5 5.6 7.5 7.8 9.6 10.1 10.9 11,5

20 Grand Falls to north end S

of Humber Valley 5.5 5.6 7,5 7.8 96 10.1 10,9 11.5


ab1eV

TRANSVERSE WW LOADS (lbs/linear ft)OF RIME COVERED T/L USING ACTUAL STORM DATA

Return Perod n Years$egmentNo. . 10 25 50 75

Hourly Wind Hourly Wind Hourly Wind Hourly WirWinds Gusts Winds Gusts Winds Gusts Winds Gus

1 Wolyrood to Whitborne ..,

I,-

• (<500 ft) • 3.6 8,1 46,) 10) 5,3 11.9 5.7 12-

2 Whitbourne to 10 mileswest of Clarervville .

(<500 ft) 4.0 9. 0 4.9 11.0 5. 6 12, 6 6.0 13

3 10 miles west of Claren..vile to Grand Falls

(^OO ft)S

2, 3 5 2 2, 7 6. 1 3. 0 '6. 8 3.2 7

4 (800-1200 ft elevations.west of Gander Lake 3.8 8.6 14.6 10,3 5.2 . 11,7 5.6 12

20 Grand Falls to north endofl-IumberValley . 3.8'. 8.6 4.6 10.3 5.2 11.7 5e6 12


VII. COMBINED WIND SPEED AND IE LOADS BY LINE SEGMENT

..

e

'4 - ..

Obtaining transverse wind loads by assuming independence ofindividual wind and ice loads is a valid method of approach. However,

Iuring icing wif/iismoresto usituations. The rime ice storm data for St. Jdlm's-.Torhay and Gander '

'er isolated, and maximum wind speeds during ice storm for earhyear extracted. Return period values for these wind speeds weregenerated, as represented in Figs. 23 through 26. The 10-, 25-, 50-,and 75-year vaiues were extracted from the figuires and presented in

Table VI.

resp ible for the combine ding eturn period values Tiansrse rdioads ar function of both wind speed and ice diameter A - -

partiülar value of transvere wi adcan result from many differentcombinations of wind speed and diameter In the previous repoEsdescribed in Section VI, iidividual ice iid wind loadings were treatedas independent variables, In that study, the wind speeds used to generate 1-

return period values were annual maximum hourly wind speeds, withoutregard to when they occurred. The resultant transverse windloads,shown in TableIV, werequite large. ..

This report has presented transverse wind loads for ice-coated

transmission lines for 10-, 25-, 50-, and 75-year return periods using

predic ted loadings from actual storm data. Thisprobablyrepresents.

jimost accurate method of obt.arning return period lodings directlyIIwever, ii has been pointed out that, for tower loaduidesigr, wind

qpeed.nd ice alue.swilLbpthberequirec1. There is no

reliable method of extracting eindividuw.ii or icing data that are

The return period plots of wind speed, both hourly values, andwind gusts, were then extrapolated to conductor level for the five linesegments. The return period values for rime and glaze icing along theproposed route were taken from the November 1973 report. The combinedwind and ice loads were obtained using the method described in SectionVI, and the results presented in Tables VII through X.

Caution should be exercised when comparing the tiansverse windloads of ice-cod transmission lines aspidsèntedi Table V with thecombinc1 wind and ice loads listd in Tables VII throughX. The_formerwere derived from actual storm combined values, the latter, while alsobased on storm data, assumed individual \vinra.rd iceloads to be rnde-pendento1 each other Eamination of the stoim data indicates that the1ârest transverse wind loads do not usually csult from a combinationof Uiéliighest winds with the heaviest icing. Since the loads are pro-prtional to the square of the wind speedy torms relatively short in

.,

36 --


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Table VI

RETURN PERIOD VALUES OFMAXIMUM WIND SPEEDS

DURING GLAZE AND RIME ICE STORMS(mph)

LOCATION RETURN PERIODS10-yr 25-yr 50-yr 75-yr

Glaze Rime Glaze Rime Glaze Rime Glaze Rime

St. John's-Torbay 41 54 47 62 52 69 55 72

Gander 36 46 40 54 43 58 45 61.

41


r r

--

TableVil

10-YEAR RETURN PERIOD VALUES

Segment Maximum Icing Maximum Ice Loads Combined Wind and Ice LoadsWind Speeds Glaz e Rime

_______Wind Sp eeds Glaz e Rime

Sustained Gusts Rad. in. lb/ft Rad. in, "lb/ft Sustained Gusts Rad, 1:11t Rad. .lbf

(mph) (mph) (0,9)________

(0.5) (mph) (mph)________

(0.9)________

0.

1 51 76.

_________

2. 17.4 3.8 15.0 40 60 2,2 11,3' 24 7.

2 54 81 3.5 23.6 4,3 18.4 43 '64 2.8 16.5 2.8 9.

3 47 70 2.4 12.9 3.1 10.8 36 54 '1.7 7.7 1,7 4.

4 54 81 2.7 15.5 3.5 13,1 43 64 2.0 9.8 2.1 5,

20 54 81 2.7 15.5 3.5 13.1 43 64 2.0 9.8 2,1 5.


Table VIII

25-.YEAR RETURN PERIOD.VALUES

cin-.ent Maximum Icin.3peedsWind

Mdmum Ice LoadsGlaze Rime

CombinedWind_Speeds

Wind and Ice'LoGlaze

lb/ftiR d

adsRime

lb/ftRad in_Sustained Gus

hRad. in. lb/ft

(0 9)Rad. in. lb/fe

(0. 5)Sustained

(mph)Gusts(mph)

n.a ,(0.9)

. .

___________(0.5)

(mph) (mp ) _____________. ___________

___________

60 S 90.. 3:4 22.5 5.0 23.8 44i 66 2,5 13.8 3.0 10.2

.2 62 c 93 4.0 29.4 5.5 28.1 47,7 70 3.1 19.4 3.5 13;1

3 54 81 2.9 17.4 4.0 16.3 40o 60 2.1 10.5 2.0 54•

4 62 93 3.2 20.4 4.4 19.2 •47 1 70 2.,3 12.1 2.4 7,2

20 62 93 3,2 20.4 4.4 19,2 47' 70 2,3 12.1 2.4 7,2


- -.- -.p

- -

ab1e IX


/

Sement Maximum Icing Maximum Ice Loads Combined Wind and Ice LoadsWind SDeeds Glaz e Rime

_____Wind Sp eeds Glaze Rime

Sistained Gust Rad. in. lb/ft Rad. in. lb/ft Sustained Gusts Rad. in. lu/ft Rad. in. lb/ft

(mph) (mph) (0.9)________

(0.5) (mph) (mph)________

(0.9)_______

(0.5)

1 66 99

_________

3.8 27.0 5.7 29.9 . 48 72 2;8 16.5 3,4 12,5

2 68 i 102 4,4 34. 5 6.2 34.6 51 co 76 3,4 22. 5 3,9 15,7

3 62 93 3,3 21.4 4,7 21.4 44- 166 2.3 12.1 2,4 7,2

4 68 1 102 3.6 24. 7 5. 1 24. 6 51 76 . 6 14.7 2. 8 9. 1

20 68 (1 10 3.6 24.7 5. 1 24. 6 ,&35i, 76y 2. 6 14.7 2.8 9, 1


TableX


Segment Maximum Icing Maximum Ice Loads Combined Wind and Ice Loads

Wind Speeds Glaz e-

Rime______

Wind Speeds Glaze_____ RimeSustained Gusts Rad. in. lb/ft Rad. in. lb/It Sustained Gusts Rad. in. lb/ft Rad. in. lb/ft

(mph) (mph) (0.9)________

(0,5) (mph) (mph)________

(0.9H (0.5)_________

V.-'1 70 105 3,9 28.2 6.3 35.6 50 7 2.9 17.4 3.7 14.4

2 7. 108 4. 5 35.8 6.8 40.7 53 79 3,4 22. 5 4,3 18.4.

3 66 99 3.4 22, 5 5. 1 24. 6 46 69 2.4 12.9 2, 6 8. 1

4 72 108 3.7 25.8 5.5 28.1 53 79 . 2,7 15.5 2,9 9,7

20 72. 108 3.7 25. 8 5. 5 28. 1 53 79 2.7 15. 5 2.9 9,7


duration (thus resulting in light icing) in conjmction with high windspeeds can produce the largest transverse wind load for a given year.Conversely, storms lasting a very long time, but with less severe winds,may result in the largest transverse wind load for a given year. (

In all cases, the segment icing wind values were extrapolatedfrom the rime ice storm winds, which were approximately 2_pehigher than the winds associated with glaze ice storms, (See Table VI,)As stated earlier, wind speed is he..dp ing fan determining

Htransverse wind loads for ice-covered conductorand towers,

L

46


• VIII. CONCLUSIONS

The principal conclusions of the study are the following:

o Transverse wind loads were generally greater with rime

ice than with glaze ice.

o Transverse wind loads derived from the November 1973

report were larger than those computed from actual stormdata using hourly winds; however, using a 1.5 gust factor

with the storm data results in loads larger than the earlier

report.

O Combined wind and ice loads computed using the wind andice as independent variables, as in the November 1973 report,but using only ice storm winds, result in gust-condition loadvalues similar to the sustained-\d load values inth

.

..-.-

Highest transverse wind loads can be expected along theisthmus west of St. Johnts. Lowest values occur along thesegment south of Gander,

-f 7C...-).

o Wet snow is not expeáted to be a problem east of I-lumberValley; there were a total of only 20 occurrences of wet snowlasting at least six hours at the stations in the area of theproposed route.

o Much of these proposed transmission line routes are throughareas of sparse, if any, recorded weather data. Some ofThe line segments used for loading estimation are quite long.Local variations within the segments could be large.

47


REFERENCES

Boyd, D. W., 1970: Icing of wires in Canada, NRCC 11448, Proc. ofTwenty-Seventh Annual Eastern Snow, Conference, February 12-13, 1970,Albany, New York,

Sissenwine, N., P. Tattelinan, D. D. Grantham, and I. I. Gringorten,1973: Extreme wind speeds, gustiness, and variations with heightfor MIL-STD 210B. Ai Force Cambridge Research LaboratoriesTechnical Rept. 73-0560, Aeronomy Laboratory, Project 8624, 72 pp

48


.................

......

(\I_______

I meteorooy research, fl0 464 w. woodbury rd. • altadena, calif.

TO:- -

6 August l9'4_______ I3 I-IOO

Teshrnont Consultants, Ltd.225-2025 Croydon Avenue .Winnipeg, Manitoba

R3P 0N5 _____...

Canada -- .

EN;. D.

Attention: Mr. A. W.-HannahA(' -:

Dear Art:FL NO.

•!

In our meeting of 11 June 1974 in Montreal, Mr. Strex aised the questionof why we had not taken the differences between anemometer heights andconductor heights into consideration in'the wind and ice loadings in ouroriginal study. At the time I had nothing with me to indicate what considera-tion had been given this factor,

As I mentioned in our telephone conversation, when I returned to Californiaafter the meeting, I went through the original computations and the heightdifferences had been taken into consideration in the extrapolation to the linesegments. The extrapolation from anembmeter heights at the stations, asshown in Table I of the report,- to 80 feet above the terrain at the mostexposed portions of the route segments was accomplished in one step ratherthan the two steps of standardizing all station wind curves at 80 feet, thenproceeding with the extrapolation as was done in the Calgary Power studywithwhich you were familiar.

The two step process is probably easier for the reader to envision, but is no

more accurate. The segment values shown in the report are conductor-level

values although this point was not brought out in the text of the report. Since

the values in our report were determined to be valid, I took no action \ J-

publish an addendum.

. .

6 '

The relationship v1 /v2 = [log (z /z )/log (z/z0)} '/P, where z0 was

taken at its turbulent value of 0.4 and P was taken at its unstable lapse-rateva]ue of 2-, was used for height adjustment to wind speeds.

Since the most exposed portion of each of our route segments was used inthe wind and ice computations, our values will be conservative (wind estimatestoo high and ice load estimates too heavy) for the more sheltered portions ofthe segments. The further combining of segments in Table 6-1 of your reportincreases that conservatism for many miles of the proposed routes.


Teshmont Consultants, Ltd.6 August 1974 . Page 2

I hope this will relieve the concern regarding conductor level values. Thepoint should have been spelled out in our report, but was apparently leftout in the crush to meet the deadlcne,

Work is underway on the ombined wind and ice loading and on the proposalfor instrumenting the measurement sites.

. Sincerely,

M, C. Richmond

- Project Manager

MCR/cm

lhrnont Con rts Ltd

RECEIVEDAUG 8 1974

-. .- -. .-.


L.

____

Tecinc Report

THE FOLLOW-ON METEOROLOGICALEVALUATION OF THE PROPOSEDGULL ISLAND TRANSMISSION LINENETWORK

I

1/7

MR.I 75 FR-1378

Submitted to

Teshmont Consultants Ltd.2025 Corydon Avenue 9Winnipeg) Manitoba, Canada

R3PON5

Contract No. 133-61081-1

Date 31 October 1975

By M. C. RichmondR. J. Boomer

Meteorology Rescarch, Inc.Box 637, 464 West Woodbury RoadAltadena, California 91001Telephone (213)7911901 TWX-9105B8-3291A Subsidiary of Cohu, Inc.

.: :


TABLE OF CONTENTS

Page

SUMMARY 1

I. INTRODUCTION 2

II, SCOPE OFSTUDY 4

III. DATA SOURCES 5

A. Clirnatological Data S

• B. Field Data 5

IV. SITE DESCRIPTIONS 8

V. ANALYSIS OF FIELD PROGRAM RESULTS 10

A. Winds 10

• 1, Wind Gusts 11

2. Gust Factors 11

3. Results from 1974-1975 MeasurementProgram -

' '14

4. Height Factors 20

B. 2p!atures 21

C. Icing 23

VI. REFINED LOADING ESTIMATES 28

A. s in Route_Segments 28

B, Refined_Loading Estimates by Route Segment 28

1. Icing '28

•

02, Winds ' 29

VII, SIGNIFICANT RESULTS AND RECOMMENDATIONS 39

REFERENCES 42

31


SUMMARY

In 1973, a study was conducted of the possible meteorologicalproblems involved in constructing a transmission line network fromthe Gull Island Hydro Site in Labrador to the Avalon Peninsula ofNewfoundland, That report was presented in November, 1973,During the winter of 1974-1975, a second phase of the study wasconducted to validate and refine the values of wind and ice load de-termined during the previous year. This study consisted of dataacquisition, field surveys, analysis of field and dlimatological data,an.d revision of line sector values developed during the earlier study.Meteorological measurements were recorded at one site in the highterrain of Labrador, two sites in the Long Range Mountains ofNewfoundland, and one site east of the mountais, Data from thesesites were correlated with that recorded at nearby weather servicestations, and probabilities of occurrence of specific ice and windloadings were extrapolated to 16 route segments.

This year's data did not result in any revision of the icing esti-mates given in the 1973 report. It appears that the winter of 1974-1975 was a relatively light icing season throughout Newfoundland,

Wind speeds 4g J...ongRanMountains weremuèli greater than previously believed. The 50-year return periodvalue was increased from 98ih in the 1973 report to 140 roth inthis study. The prevailing direction of the extreme winds has been c-.

changed from north-northwesterly to easterly. Measurements takenin Labrador have shown the 1973 estimates of return period windspeeds on the mainland to be somewhat low, The S0-year returnperiod value for the higher elevationsIsle was increased from 93 mph to 100 mph.

The shifting of the, proposed route eastward at the crossing ofthe Long Range Mountains wil). result in some decrease in ice andwind loads along most of this portion of the line, However, portions0 the segment are ecposed to the east and should be subject to thesame extreme loadings as predicted by the past winter's measure-ment program.

1


I. INTRODUCTION

--(..:) Teshmont Consultants, Ltd., is in the process of designing a500-ky transmission line for Newfoundland and Labrador Hydro. Theproposed line will extend from the Gull Island Hydro Site southwestof Goose Bay, Labrador, to neai 1-lolyrood on the Avalon Peninsulaof Newfoundland.

It was knoWn that portions of the line would be subjected tosome of the highest wind and ice loads to be experienced in Canada,Northeastern Newfoundland was known to be especially susceptibleto damaging icing storms in recent years. The proposed routes wereto cross through that area as well as uninhabited areas where nopast experience or reports were available, Two preliminary meteor-ological evaluations of the area and potential routes were conductedduring the fall of 1973 and the summer of 1974. Those studies werebased on the edsting climatological records of the few weather stationslocated throughout tho area supplemented by storm damage reportsand. conversations with personnel having fir sthand experience withthe winds and icing in the various regions of the province. It wasreadily apparent that e:dsting data were not available from the remoteareas most susceptible to high winds and/or icing, The need tocollect meteorological data at some of the more vulnerable locationsand to develop relationships between these locations and existingweather stations was recognized. A data collection program wasestablished and data collectod at four sites during the winter of 1974-1975. If necessary, the wind and ice loadings predicted for theseremote portions of the proposed route could be refined to reflect theresults of the measurement program.

There have been some changes in the proposed route since thetvo previous studies were made. The portion of the route in Labradorhas not changed significantly since the November, 1973, report. Aftercrossing the Strait of. Belle Isle, the route will then run south-southwest-ward along the west coastal plain of the norii1\vcs peninsula ofNewfoundiand, remaining at elevations near or below 500 feet exceptwhere tile route runs between the 1-Ugh Lands of St. John and tile Long

2


Range Mountains. The elevation in this region briefly roaches 1500 feet.1\rhofl the sites for tue 1974- 1975 meteoro1oica1 pro am wore chosen,the prooscd route was ox outed to run between Per Liancl Creek Pondand Inner Pond, stay on the coastal plain on the west side of VT est 1-lill,

and thou veer southeastward as it rapidly ascended to the ridge of the

Long .R ange Mountains One of the weather station sites was located nenothe highest point: of the ri.dge, The current route also runs betweenPortland Creek Pond and Inner Pond, but then iimnediately begins a moregradual climb east of West Hill and crosses the mountains at slightlylower elevations, The new crossing of the Long Range Mountains shouldbe slightly less exposed than the earlier route. South of the Main Riverthe descent into the Upper Humber Valley is along the original routedescribed in the November, 1973, report0 However, the latest route thenturns south of the original, running south of Shcf:Eielcl Lake and close to thenorthern edge of the Top sails. South of Gander the original and currentroutes become one again and remain essentially so, with only minorvariations, until the terminus northeast of I-iolyrood.

This report presents the analysis of the data collected during thewinter of 1974..1975, The scope of the study and data sources aredescribed in Sections II and III, The four remote data collccti.on sites aredescribed in Section 1V, and the results of the field program arc analyzedin Section V, Thc wind and ice loading estimates given in the two previousreports are updated by line segment in Section Vi, Finally, significantresults and conclusions are summarized in Section VII,

3


II, SCOPE OF STUDY

This transmission line study consisted basically of three phases,as follows:

a Data acquisition (field program)

0 Reclucion and analysis of data

Rcfiiiing of segment values

The data acquisition phase consisted of making measurements ofwind, temperature, and ice accumulations at four sites previously identifled as being apparent citical locations to determine ice and wind loadingext.remes, These locations were selected as being reDresentative of thehighest and/or most exposed portions of the proposed route. Site locationsand equipment installed are described in Section PT. Measurements weremacic from October 1974 through June 1975.

In the data reduction and analysis phase, the data gat:hcred from thefour instrumented sites and the corresponding weather records from thesix area weather stations listed in Section III were processed together.They were related to the historical data for those stations to developprobabilities of occurrence of specific ice, wind, and combined ice andwind loads for the measurement sites,

Results of the analysis phase were used to refine the route segmentvalues previously developed.

4


Ill. DATA SOURCES

A, Climato].ogical Data

Historical met:ooro1oica1 data for twelve Dep3rtment of the Environ-

meat stations in the area were available iron). previous studies conducted

in 1973 and 1974. For six of the stations most nearly related to the

instrumented sites, microfilms or photocoeicS OZ hC) houm'ly weather

obe.rva(:ions taken during the 1)oriod 1 October 1974) through 30 June 1975,

were procured from the Atrnopner.c Environr.neni; Service (AES). The

twelve stations for which the historical, data were available and their

period of record are listed below. The stations for which hourly data dw:ingthe past winter were acquired are designated by the asterisks.

St. John1sTorbay, Nfld. l9531971

.Argentia, Nfld, 1953.. 1.969* Gender, Nfld. 1 95:3..- 1971

.buchans, Nfl.d, 193..l9u4

Deer Lake, Nfld. 1 966.- 1.9 71

Stephenville, Nfid. 1953-1971

Daniels Harbour, Nfid. 1966-.1971

Battle Harbour, Labrador 1958-1971* Goose Bay, Labrador 1953-1971

Wabash Lake, Labrador 1961-1971

Schefferville (Knob Lake), Quebec 1953W- 1971

Lake Eon, Quebec 1961-1971

Periods with wind speeds greater than 20 mph and/or peak gustsgreater than 30 mph were extracted from wind charts obtained from IlawkeBay, Nfl., for the period November, 1974, through April, 1975, In

addition, Monthly Climatological Sammaries were available from St. JohnTsAirport and Gander International Airport for the October, 1974, throughMay, 1975, period.

B. Field Data

Recorded data were ojtained from four instruincnted sites along the

5


proposed route during the period from ndd-Octobcr, 1974, through early

Jnne, l975 The Jocations of these remote sites arc shown in Figure

III- 1 and des criptiois of their locations and in.sta u:nientation in Lalied are

detailed in Section IV

6


__________-_______________________ __________________________________________________________

-

COUIDEC

C/

I A B R ADO R

CP4U?)L

LiArTLE HAROOUR

/1 AIL.&NTIC QrE

OU(BEC

I (S

/1_.' j7,'7 ONR01

7 .uCA S

EWfOU'1DLAL9Tt P,t?VtLL.

p ST. t_AwflEN

-7 -

Fig UI-i. PROPOSED GULL ISLAND TRANSMISSION LINE SYSTEM.

McasuiemehL SiLe; arc Indicated by the Squares.

7


IV SITE DESCRIPTIONS

Site 1 was located near the microwave tower on a kill north ofShofflold Lake, At an elevation of 1500 feet, this station, approximatel\r1000 feet above th lake, was well exposed to the gradient wincE flow fromall directions, This site was chosen to ruproseit the in xirc.uni exposurein an area where no regular observations ara available. Of specialinterest was northeast winds coming off the Atlantic Ocean,

Site 2 was located eight miles south-southeast of Portland Creek ona ridge 2000 feet above sea level, This site, located near the area wherethe prouosccl route was expected to cross the ricHe, is well ecposod in alldirections,

Site 3 was located bet\'een the High Lands of St. John and the Long.Lange ..Lountains , 1)proxraately eleven miles east of Barr 'd Harbour. Atan e].ovn:Lon ot 1 bOO loot, the site is s crcd by h.igior Lcrratn to the west,The possibility of channelling of north.northcast or soutlsouthviest windsled to the selection of this site.

Site 4 was located on the. mainland on a plateau about twenty-sixmiles north of the Strait of Belle Isle crossing point at an elevation of 1800feet, It is well exposed in all directions and representative of high terrainin this area,

At each site two 30-foot towers were erected approximately 54 feetapart, spanned by a cable 1,338 inches in diameter. An ice rate meter(IRM) that measures increased tension clue to ice loading was connected

to the cable. Atop each tower was a Mechanical Weather Station (MWS)that recorded vincl dir ection, wind run, temperature, and relative huniid-ity. In addition, power was available at Site 1 'which allowed for theinstallation of heat lamps atop 0110 of the towers in an attempt to reducethe heavy ice accumulations ihat were expected at the site,

8


r2110 IR i\P s begn service in inid-.OcLober, 1974, and the MWS's in

mid.November, 1974 All of the sites were deacLivated in June, 1975

9


V. ANALYSIS OF FIELD PROGRAM RESULTS

Mechanical Weather Station data recovery percentages by parameterwere calculated for each site. The value of having two MWS's at each siteis reflected in tile comparison of the recovery pe rccntages of each MWS.By station, only 73.4 percent of the data was recovered, yet, by site,90 percent was recovered. These percentages i.ucludc data that was questionable clue to Lii lihelihocci of icing (c. g. wind speeds very tow for SOVC ralconsecutive days with a constant wind dIrection during the same period).iiQweCr, these data are sl:ill useful in that they give a good inclica Lion of theduration of severe icingr conditions. One parairieter not iriclucicci in theserecovery percentages was relative humidity. The somewhat delicate humidityelement could not withstand the severity of the many winter s terms that pas secithrough Newfoundland ancL thus, the resulting data were, at best, suspectciuriiig most of the season.

A. VTi.ncls

The Mechanical Vfeathc' r Stations used at Sites 1 through 6 measurei'Ufl, Lao number oi miles of winci hich pass the station, No rrnal

data roucton o MTS i:ecordngs resuILs in liotuly average v:incis, the totalnumber of miles of wind which passed the station between 30 minutes bforethe hour and 30 irilnutes after the hour. The winds extracted from the rnic ro -filmed hourly weather reports of six stations in Newfoundland and Labradorare II1OUI.ly v'iricl1 speeds. The hourly wind consi.sts of a one-minute averagewind speed observed sometime during the ten minutes prior to the hour. Thus,if the actual maxiriiurn one-minute average does not occur in that ten minutes,it is not recorded. The fastest ''hourly wind'' values represent only samplesof the wind conditions for each hour. The sample covers a period of fromone to ten consccuti.ve minutes just before the hour, depending upon the ob-server and the recording or indicating equipment used for the observation,Such a sample ignores the winds that occur during at least 5/6 of each hourand possibly as much as 59/60 of each hour. Thus, there is a consistenttendency for hourly wind values to understate the fastest wind occurrenceduring the hour. The degree of understatement is directly proportional tothe variability of the nd speed.

Studies of the relationships between maximum wind speed values do-rived from different aveiagin; times have me sultecl in a considerable range

10


of conversion factors to be used. These relaLLonships have been studiednuder the general category of wind gusts and gust factors.

1, Wind Gusts

Gusts arc sudden brief inc reases in the sr)eecl offrom edutes superimposed on t:he basic flow of air. Many s Luc1ic cd therelationship of gusts to the steady wind and their variation with speed, height,thermal stratification, and terrain have culminated in general agreementconcerning th nature of these relationships (i)avis and Newstein, 1968;Camp, 1968; Shellard, 1965; Miisuta, 1962; Boyd, 1965; Brook and Spillanc,1970; Sissen\\'ine et al. , 1973; and others). However, quantitative resultshave varied, depending Qfl the data and analytical methods used.

Most studies of gustiness arc from micrometeorological research,Though measurenients obtained from such experiments are generally superiorto operational data because of refined anemnomnetry, such studies hardly everprovide data for the very high wind speeds important in design of trausmis siontowers and conductors. Sissenwine et al. , 1 (y73, analyzed a more meaningful spectrum of wind speeds and this work appears to be one of the betterrecent efforts in this field. Their study included the analysis of 54S windobservations kml\en at anemometer heights varying from 1 0 to 85 feet, withone -mthute steady wind speeds varying from 20 to over 70 knots, and loca-tions varying from tropical Pacific islands to Alaska and Greenland. Sincerecorder charts of steady \villdls greater than 70 knots were scarce (on!y 10cases of the 518 studied), they also used 26 observations of gust factorsfor fivc-n-iinnte steady winds ranging from 71 to 1 63 knots taken at ML. V/ash-ing:on, New psnire, and. four values derived from wind data taken duringhurricanes that nassed ciose to the Blue Hill Observatory near Boston, Massa-chusetts. Actuai].y, accurate data on short period gusts are quite rare. Inweather station cliniatoiogical records the steady state wind speed co rresponcling to maximum peak gusts is usually not available. The maximumhourly wind speed and maximum peak gust for the station frequently did notoccur in the same storm and are related only in. a qualitative sense.

2. Gust factors

In discussion of gust relationships, a "gust factor" equal to 0/V iscommonly employed. In this expression C is the maximum gust speed andV is the maximum sustained wind speed. While there is general agreementthat gust factors tend to decrease with increasing wind speed and heightabove the surface, past -studies have resulted in a variety of gust factorre1at-ionships with as many different values as studies. There has beenlittle apparent effort to standardize the type of wind speed used as the sus-tained wind or the duration of the gusts involved,

11


Sissçuiwine et al, found that a least- squares relationship (C. F, =r 'O.0093V

1 4 0. 5 e ) best fit the mc'dian (50 percentile) two- second gustsrelated to five-minute steady speu:Is. Two- second gusts thus derivedranged from 1,46 limes a five-ninuLe steady speed of 25 knots to 1.22

ites a five.-iuinutcstc a(Iy speed 0. 100 knøts . niabie \1r_ 1 uu1 Fig. V- 1

show the reIaLioisiip o other gust dura Lions to fly e- minute steady

peed s.

One of the most widely used relationships for computing gust speedswas derived by Boyd. His formi1a, G 5.8 + 1.29 V, gives gust speeds(G) in miles per hour bas cci on hourly wind speeds (V) in nules per hour.At the time he derived this formula, the gust data used were thought to beof approximately three- second duration, Recently, Mr. Boyd stated thathe now believes the response time of the pressure tube anemometer andits recorder, which his data were collected from, to be of the order offive to eight seconds.

Another often referenced authority, I)uust (1960), developed a statis-tical. model based on samples taken with a high speed recorder. Althoughhis empIrical data were talceii at speeds less than 42 miles per hour, heapplied his model, to class intervals of speeds up to 80 mph. As TableV-2 shows, illS probable gust factors for various duration gusts arenearly the same mom all speed classes.

If the Burst relationships for hourly pceds to five -minute gusts(intcrpe].atecl) are combined with the Sis senv'ine et al. relati.on of ItVC -ruin-

ute to two-second speeds, the rcsulii.ng gust factors fo r t.vo-sccouc gusts

I toni hourly rinds 6 t 20vary from I mph to I. 4 a t SO mph. This is.nearly exacciy what the noydt formula of C = 5. 8 4- 1. 29 V results in for

live-second gusts.

In 1964, the Bonneville Power Administration published gust factorsfor 52 stations in their area of operation (Bonneville Power Administration,1964). These gust factors comparing maximum gusts to one-minute windspeeds ranged from 1.23 to 1.67 with a mean of 1. 35. They detected novariation of gust factor with wind speed in the data used in their study.

Gust factors tend to decrease with height above the terrain0 Thisdecrease with height is generally accepted as theoretically reasonable ina qualitative sense; however, there is limited experimental data to developfirm quantitative values from. It is apparent that, since this variation withheight is a function of eddy size, it must also be related to terrain rough-ness, wind speed, and atmospheric stability. Wind near the earth's surfaceis very sensitave to the terrain; consequently, any particular location islikely to have its own gust cnamactc ristics, IL is certainly well within thestate of the art in anemom.etry to experimentally develop gust factor heightdependence values applicable to a selection of typical topographic and

12


TABLE V-i

GUST FACTORS VERSUS 5-MINUTE STEADY WIND SPEED

E- inute Cujt F'ac r (C t)

(knota) 60-sec 30-cc 2-sec

20 1.120 1.172 1.4566

30 1.105 1.151 1.4160

40 1.094 1.134 1.3791

50 1.085 1.121 1.3451

60 ,077 1.111 1.3147

30 1.066 1.095 1.2613

100 1.057 1.001 1.2170

125

-

1.049 1,06l 1.1719

150 1.042 1.059 1.1363

175 1.035 1.050 1.1000

200 1.028 1.0'lO 1.0856

1000 -, r- -r-r.rrl--rlr, r-1-r - T1'T' T1-rrr I-Vrr[rT

\\\\2C'C\

::. 80 "N

2- -JJ. LLLJ.Lt U ,.i I LÀ

EO 1.1 1.2 14Gusr lcion

I.

Fin, V-i, GUST FACTORS VERSUS S-MINUTE STEADY WiND SPEED

13


TABLE V-2

PROBABLE (50 RCENT) GUST FACTORS FOR 20- TO S0.MP1IAVERAGE flOUR LY SPEii)S USING DURST S MODEL

Mean HourlyGust Factor (OF)

___________ __________

Speed(mph) 600 sec 60 SeC 30 sec 2() sec 10 sec S sec

20 1,05 1.25 1.30 1.35 1,40 1,50

30 1.07 1.23 1.33 1.37 1,43 1,47

40 3.07 1.25 1.32 1.35 1,42 1.48

so 1.06 1,24 1,32 '1.36 1,42 1.48

60 1,07 1.24 1.32 1,35 1.42 1.48

70 1,06 1.24 1,31 1,36 1,41 1.49

80 1,06 1,24 1.33 1.36 1,43 148

cco'raphic locales; however, thi.s has not beau on any o ganizeclbasis.

It is apparent from the above discussion of the currently most fre-quently referenced sources that there are no hard and fast relationships touse in relating speeds of different averaging times. Observations at highwind speeds in the range to be expected to occur in Newfoundland were in-cluded in the derivation of the relationship developed by Sissenwine, et al.For this reason, Sis senwine' s least sc1ua res relationship is used in the esti-mation of peak gusts in this study, This fo rrnula may Lend to underestimategusts at lower one-minute speeds, hut it appears to be more realistic forthe higher wind speeds. In order to be consistent, the same formula wasused. throughout.

3. Results From 1974-1975 Measurement Program

Table V- 3 lists the maximum hourly wind speeds and the peak gustsreported at the six weather stations this winier, The peak gust is the

* Daniel's Harbour did not record gusts.

14


TAFLE V-.3

MAXIMUM STATION WINDS REPORTED DURING

WINTER OF 1975-1975

(Wind Speeds in Miles Per Hour)

Oct. Nov. Dec Jan. Feb. Mar. ADr. May

SI. Johris

Max. Hourly* WSW 35 SSW 40 NN 15 SIC 50 W 45 WSVT 52 NNW 46 N 63

Peak Gust S 55 WSVT 56 NE 63 S 71 NNVT 61 WSVT 72 S 70 N 91,1d•'

G.ande r

Ma>:. Hourly S -15 SSW 32 25 55W 41 VT 23 VT 35 NNW 30 N 10Peak Gut 55W 80 SSVT -19 E 44 55W 69 NNW 43 1y 53 S 13 N ss

1_ /

Doer Lake

Max. Hourly SSW 35 SW 20 ENE 25 NNE 25 W 25 sw 23 ENE 23 NW 2P,ak. Gust 58W 30 WSW 35 ENE 45 NNE -15 W 35 SW 37 ENS 40 WNW 32

i.T') ,'•,/

1):i'iel's Har)our

?1ax. Hourly SW 64 555 42 WSVT 36 WSW 45 WSW 36 EN: 36 ENE 41 SSVT 32

DIe Harbour

Max. Hourly SW 35 SW 40 N 50 N 45 SSE 25 NNVT 10 35 NNVI 46Pt;/k Gest 571 30 } 57 N 53 N 63 55540 NNV' 48 S 46 NNVT 56

7 1. - / / -

Max. auriy WSW 27 ENF; 58 NNN 26 VT 40 SW 30 VT 37 sw 35 NW 23Peak Gust WSVT 45 ENS 70 NHE 40 VT 32 SW 40 VT 53 SW 55 NW 29

i:. ''-::' ,,,

Max. Hourly -- NW 32 ESS 23 N 39 VT 29 VT 30 SW 26 --

Peak Gust -- 5 61 5 50 N 62 wsw 46 VT -16 14 48 --

/ / / #

Maximum Hou rly Wind Speeds are one-minute averages* Period oI Record Novembe r through April

15


highest 'insLtntanoous' wind speed recorded at a station during a specified

period. Depending on the respon so time o the aneinc rue Ler and recorcie rused, Lb is Value may repros en L anything from a two -• second to an eight-

second I US t, or, if the \\'Lfld iS tIO L p us ting , simply Uu. h iphe sL \viuc1 speedrecorded. IL should i:. noted LLnt the naxi.muin 1ourtv winds and noah pus t:sarc not necessarily nsociaLcd. They frequently occur on diflc rnL days.

Winds were generally lighter than normal at reporting weather stationsin Newfoundland and Labrador during the winter and spring of 1974- 1975,In November, an hourly wind speed of 58 mph was recorded at Goose Baysurpassing the previous all-time record by 6 mph. May was an exceptionallyeiindy windy month over much of the province. St. John's re co rcicd a peakgust of 91 mph, the highest over recorded in May, but well below the all-time record of 120 m:h. '1 he average wind speed for t;hc month was alsoa record 18. 8 mph. At Gander, total wind mileage v;as above normal inMay.

In contrast, February was relatively calm, with no wind storms duringthe month. For the remaining winter and spring months, the average windspeed was near or s1ilit1y below normal.

The maximum hourly average wind speeds recorded at each of theobservahon sit0 s clu::in this oast winter are listed in Table V-I. Thew)lueS in n: .cn±osc are the estimated maximum one -minute eneraresconn)uLed at I * 25 times the rn:•:.iniutn hourly av ra:e and estinaLed peak

(tan - ocond a: rac) co.unteci us in the relaInnshio o Pi. sen:ineci. al. Table 7- b re ns down hc V. 111(1 da La niLe eol catecor o , bo L:h bynumber of hours and perccntacio of recove sect data. By far, the h.ghestwind speeds rome moser clod at Site 2. Over 15 percent of the wind data re-covered at that site showed speeds in cxc es s of -10 mph; over S ie reent ofthe data indicated averagehourly wind speeds exceeding 50 mph. The high-est speed recorded was from the east at 101 mph, on March 3. It is likelythat t:hi.s figure was e1uai1ed or exceeded during storms that resulted indamage to the MWS or that occurred when both stations were iced up. OnDecember 13 the cups on both, stations were blown off at wind speeds in ex-cess of 80 mph from the east. One storm of note occurred between April26-28 when one of the stations at Site 2 recorded 3 consecutive hours ofwinds above 50 mph and 14 consecutive hours of wirds in excess of 80 mph.This highest wind speed recorded during this period was 93 mph. Onceagain, the prevailing direction of these winds was from the cast. Althoughthe site is well expos cc! in all directions, less than 10 percent of time windsin excess of 50 mph were from directions oilier than northeast throughsoutheast. This would seem to indicate that the extreme winds at. Site 2are prevalent when tl.e low pressure systems thove to the south of New-foundland.


TAELE V-4

MAX1MU'.' SITT WINDS RECORDEDWINTER OF 1974-1975

(Wind Soceds in M1ICS Per Hour')

Nov. Dcc. Jan. Feb. Mar. Apr. MavT

Site 1Max, Hourly Avg; 29* 33* 44 45 40 45 46Est. lMin. Avg./' ' : (36) ' (41) (55) (56) (50) (56) (58)Est. Peak Gust (46),-::; . (02) (68) (70) (63) (70) (72) .''j , (i 24')

Site 2Max, Hourly Avg. 37* 95* 89* 50* i.oi. 93* 75Est. I -Miii. Avg. (46) (1 1) (1 11) (63) (126) (116) (94)Est. Peak Gust (8) (13b) (l) (7?) (14) (134) (112)

Jr

Site 3Max, Hourly Avg. 54* 50* 55 57 49* 60 47Est. Max. 1-Mm, Avg. (68) (63) (69) (71) (61) (75) (59)Est. Peak Gust (83) (77) (65) (87) (75) (91) (73)

Site 4Max. Hourly Avg. 54 60 58 50 57 54 70Est. Max. 1-Mu, Avg. (68) (75) (73) (63) (71) (68) (88) "Est. Peak Gust (83) (91) (89) (77) (8'?) (83) (106) /' 'J

t Period of record began mid-November, o; dcd mid-May* Partial month of data due to equipment problems.


TABLE V-S

Number of Hours

Site:Av. Hourly\,rj1.1(1 Speed (mph) 1 2 3 4

40-49.5 19 171 227 268

s0-59.5 97 30 85

(h). 69.5 59 1 7

70-79.5 21 1

80-89.5 17

90-99.5 7

l00 1

Total 19 373 258 361

Percentage of Recovered Data

Site:

1 2 3 4

O-9. 5 0.47 6.93 5. 13 6.083.93 0-.6S 1.93

60-69.5 2.39 0.02 0. 16

70-79.5 0.85 0.02

80-89.5 0. 69

80-99.5 0.28

100 0.04

Total 0.47 15.11 5.83 8.19

18


On the mainland at Site 4, wLfl(l Speeds exceed 40 mph over 3 percentof the period; however, spee4s in excess of 50 iipIi o(:curred on oniy $hours, or little more than 2 pc roont of the period of record. The hiehest

wind speed recorded was f rum the northwest at 70 mph on tay 17 Onestorm of note occur red bctwccn Dccc mbc c 3-5. \iu.1 cods e:cecdcd

35 mph for 39 consecutive hours and 50 mh for 25 consecutive hours

The wind direction was north-northeast, changing to north later in the storm.Unlike Site 2, the extreme winds at Site 4 showed no obvious preference forany direction, although a majority of the strong winds were from the north-west through northeast. However, there were indications that the wind vaneon one or both of the stations may have been shaken loose on one or moreoccasions and lost •its orientation, Thus, more of a pattern to the directionof the extrenie winds may have existed without being apparent.

The stations at Site 3 recorded winds in excess of 50 mph less thanone percent of the time. A rcuL:cimu.m wind speed of 6t) mph irorn the north-

east occurred on April 1. Howe.rer, most of ihe strongest winds were fromthe southwesterly quadrant, indicatLve of low pressure systems passing tothe north of the region,

Site 1 at Sheffield Lake did not record any winds above 50 mph, andrrl.\r few of the Wind speeds excecr:led 40 mph. There did nut a:par to ho

any prevalent wind direction associated with the stronger wind speeds.

iteas evidcnt:fm urn a co reun risen of all four s ito s thaI: tL c Stror 0s tat cnc} loon Lion we mc ao; gene rally tee cr5 et of the sae.:e Storm 5J Loins

As; noted earlier, the sro1ea:tcmty inds at 51cc 2 vic r :rnw.enLly due toLomni systdd1s pas sing to the rua:h of (.o region, but at Site 3 the strong

southwesterly winds resulted from the storm centers pas sing to the north.On only two occasions was one storm reseons ible for very L is'h winds at more

than one site. On January 19 southerly winds apnroachng 90 mph struckSite 2, while at Site 4 south-to-southwesterly winds i'eachied 58 mph. Thewinds at Site 1 did not exceed 37 mph, and at Site 3 they peaked at only31 mph. During the storm of April 26-28 described earlier for Site 2,northeasterly w-inds at Site 4 penned at 53 mph, while at Site 3 the highesthourly wind spe cci recorded was 'L2 mph. The winds at Site 1 did not exceed30 mph. However, during several severe storms at Site 2 the anernomnciercups at one or mOre of the other sites were partially or completely frozen,and thus, were not recording the true wind speed.

A total of 30 wind storms were analyzed and the strongest winds re-corded during each storm at the four sites were correlated with correspondingwinds at the most representative reporting station in the area. The strongerwinds at Site 1 were approximately 50 pa rcent higher than the co rrc Spoildingwinds at Gander, The rrmagnitudo of the strong winds at Site 1 were, on tileaverage, twice that of Battle Harbour, al.Lhoumgh the actual ratios o Site 4winch; to Rattle i-larbuui. winds ranged from 1. 00 to 2. 86. ior winds above

10


40 np1i at. Battle Harbour, the range of ratios fell to between 1. 00 and

1.91.

Toere s litti e correlztion fcnuid he veen. Site 2 and any of Ihe six(ntions. The station nea cc st Site 2, ,Danie I's I arbon.r, i very h clt,c red

from easterly winds by the ridge upon which Site 2 is lee ccl. At: times,the winds at Site 2 were almost four times stronger than the winds atBattle Harbour, a station well-exposed to all directions, as was Site 2.

On March 3, the maximum wind SpOCCT recorded at Battle Ha rbour was

30 mph, while at Site 2 a one-minute average speed of 120 mph likely

occurred du ring the hour when the ave rage \viricl speed was 101 mph. On

ot1cr occasions, Site 2 winds were less than twice the magnitude of the

winds at Battle Harbour. but, on the ave rage, the mnaxirnuni wind speous

at Site 2 were approximately three times those at Battle 1-larbour. Unfo r-

tenately, during those days when the stronesf; winds were reco rdecl at

battle Harbour, the anemometers at Smte 2 were either .mrozen or otherwi.se

not functioning. At these extreme wind speeds, the correlation bcL\cee the

two locations would probably be easier to ascertain.

Although DanicUs Harbour is sheltered from the cast, strong winds

from the east-northeast or east-southeast are occasionally recox1ed. At

the same time, the winds at Site 2 are very strong. Gene rally, v:hcn

D.nie1's Harbour recorded w-inds from the casl.erly quncIra1t at snces greater

deto ebout 30 nnh, the averae hourly win speed at Site ?. cxccLIod 65iinh

and has apomoacheu 100 this aet Season. Ihis \'0Ul0 I(n.CC ..n esti-

mated one --minute wind. s need of GO mpn and above.

4. Height Factors

The wind speeds obtained from the MWS's have not been c;trapolatedfrom the measurement level of 30 feeL up to an approximate conciuctor levelof 80 to 100 feet above the ground. Wind speed gene atly increases withheight above the surface of the earth. The rate of increase is dependent onthe speed of the wind, the variation with height of the air temperature, and

the roughness of the terrain over which the wind is flowing.

There have been many studies undertaken and theories presented onthe variations of wind speed with height above the surface. There is generalagreement that wind profiles tend to obey a power law (Be Marris, 1959;Johnson, 1959; and Munn; 19 66). This relationship is normally used when

neutral stability exists. The power law is of the form V/V1 = (Z 2/ Zwhere VI is the wind speed at some known level, Z i, and V2 is the wind

speed at the desi mccl level, Z 2 The exponent, P, is dependent on the ati-nos -

pLc nc tcmnne mature lapse rate, wind speed and ground roughness. There isless ag reexnent as to what the value of P should be. IL is larger uncle r astable vertical temnl:)e rature gradient and smaller for neutral and unstable

on


conditions; ii decreases with increas in wind speeds and increases with

terrain rouglines s (Do Marris, 1959 ; Davenport, 196$). The typical val-ue USO(l for P is 1/7 or 0. 113 (Sherlock, 1952), However, Sherlock ree-

OgfliSO(.1 that t:tus P vaLue vas apn1cable to steady or i'neaii wi U1:; Sud that;

lO,tS We10 bettor (iesCri)Od with a vJ.ue of P 0. 0625. Sheitarci (I9d),

in the rtiIy f 1ril ced and Di section Cvot' the TJiiJ,cc[ Ldein,

used P valUes l 0. 17 for mean hourly wind speeds and 0. 005 for three-

second gusts.

The majority of studies of wind profiles are made under regimes of

light to moderate wind speeds atcl P values resulting from such s Ludies may

not be applicable to 1uith wind speeds. Sis sonwine et al. (1973), using high

wind speed data collected at the Argonne National Laboratory ins trurnontecl

tower in Argonne, Illinois, derived the empirical equation

P 0.077 1- 1. 56/V1 where the linilling P value approaches 0. 077 as

V1 becomes very large.

The Arconne National Sununaries presents a 1ercez1tao frequency of

P values versus the ten-minute average wind speeds. The data for the table

contains about 35, 000 observations. For wind speeds. greater than 24 mph

the median P value is about 0. 125. It now apnears that a P value of

0. 125 shouLd be used for wind speeds up to approxima Lely 50 :m.uh, and

0. 080 for wind speeds above that, and for all gust sneeds, Hev:cver, one

must be canti.ous when exf;rapolat:ing the e;ind sneeds recorded at Site 2,

and 'to a ic:; scm extent Site 4, to t:Iic an'p::oxtmate conductor love].. The dcoth

of the air mass st;-aming o-cm the excscci ricigc.aL Sit:e 2 is net known, end

thus, ['he vcrtical vied pmoiic is unce rLH. 1r is relative) y shallow, thewind pccd at 100 feet n-lay even be less than that at 30 feeL. C;xIVCrseIy,

a deep layer rciay result in higher wind sr;cds at 100 feet thane. 30 feet.

IL is likely that the layer of streaming air is at least 100 feet deep. Al-

.thbugh the depth of the layer is not known, it is readily apparent teat thewind speeds in the layer are much greater than in the free air at 2000 feet

above sea level at some distance from the ridge.

B. Temperatures

Ambient air temperatures wore recorded at the four sites and extracted

from station data. Tables V-6 and 'V-7 show the mnuumurn temperatures bymonth recorded at these locations. Temperatures at the station were generallynear or slightly below normal during the entire winter, except for quite coldweather during the last two weeks of January and all of February. Both Gnu-cler and St. John's reported February to be the coldest month on record. Onthe fourth, Gander recorded -.240 F, setting an all.-time record by eight do-grees. Goose Bay recorded -33°F in January and -31°F in February, onlya few degrees off the records for each month. Battle Harbour also cameclose to setting new low standards.

21


TABLE v-6MINI2v[UM STA TTGN Tiv[PE RATU RES

RE CORI)ED DURING .[NT ER 01' .1 971--i 975(Temperatures in Dog ro e-ri .Fah i-enheit)

Oct Nov Dcc Jan Feb Mar Apr \[ay

St. John's 26 22 14 5 -I() 9 14 26

Gander 23 18 2 -15 -24 1 12 25

Deer Lake 17 15 -10 -22 -27 -20 - 5 2

Daniel's Harbour 25 20 - 2 -13 -14 - 2 9 24

13atL}.e Harbour 19 9 - 2 -28 -24 - 6 12 21

Goose Day 5 1 -15 -33 -31 -23 3 18

New a11-tirne low temperature

TABLE V-7MINIMUM SITE TEMPE RATURES

RECORDED DURING VJNTER OF 1974--1975(TerriperaLures in .Dcgrues Eahrnhcit)

Nov Dcc Jan Feb Mar Apr

Sitel 8 8 -7 0 13

Site2 0 -2-1 -25 - 7 7

Site 3 - 3 3 .- 30 -2.3 - @ 12

Sitc4 - -5 -9 -25 •-23 -3 3

Period of record began mid-November, ended mid-MayMissing data due to equipment prohi ems

* Pa rtial nionth of data clue to equipment problems

May

16

17

14

10

22


[emperaLure mea surelncntT was difficult at times due to the tempo ra -ture elements Lrequent;J.y being cororccI with ice and thuS recording a constanttenipe rain re tom days at a time. I-lowe ye r, enough data was rocove red tomnalce scvc].al obse evaf ions. Tom pemaLui:c; be] ow 0 F wore iJo commonat Sites 2, 3 and 1. During the cold wave in January and February, theternr)emaLuJ:e ;tdOii rose above 0 ' F at SiLo 2.

Often these cold temperatures were accompanied by relatively strongwinds, Some examples of this arc shown below:

Site 1; -3°F with 37 mph (46), -7°F with 28 mph (35)

Site 2: +12°F with 101 mph (126), +8°F with 89 mph (ill),3 °F with 52 mph (65), -24 'F with 45 mph (56)

Sit:e3: -12°F with 56 mph (70), -15°F with 53 mph (66)

Site 4: -25°F with 47 mph (59)

Values in parentheses are corresponding estimated one-minute averages.

No precise correlation was established between temperatures at the.sites and any of the staLions in Newfoundland and Labrador. Iloweve r, somegeneralizations can 1)0 made. The temperatures at SiLos 2 and - were us willy5° to 15°F lower than the corre ending temnneraLure at h3-s tUe Harbour, ox-cept during etremel y cold ternperaLures u/hen there was little or no correla-tion.

C. icing

In gene ml, the number of hours of freezing precipitation was belownormal. at the six weather stations in Newfoundland and Labrador during time1974-1975 meas urement pe mod. However, with the exception o BattleHarbour, the totals at; each station were within one standard deviation ofthe mean. Table V-8 shows the number em hours of freezing rain and totalfreezing precipitation for the six stations from October, 1.975, throughMay, 1975. The number of hours of freezing rain was near normal formost stations, The frequency of occurrence of freezing precipitation wasnear or above normal in November, hut in December it was beLow normalat all stations except St. JohnT s, January was well below normal at allstations except St. Johns. Battle Harbour and Goose Bay reported nofreezing precipitation during the entire month of Janua my. This continuedinto February, a month characterized by clear, relatively calm, and cx-tremely cold weather, All stations had less free zing precipitation thannc)rrnal, with Battle Harbour and Goose Bay once again receiving none.No definite pat:tern existed during March. St. Jbhn s and Battle Harbourwere well below normal, but Goose Bay was well above normal, and Ganderwas near nominal. April was -a] Sc) quite variable. Gander recorded 47 hoursof freezing precipitation, comoared to an average of 21 hours. Almost half

23


''' T V -c

HOURS OF FREEZING PREO.PITATION AT STATIONSDURING WINTFF OF 1974-1975

(Number of Hours of Freezing Rain in Parentheses)

197L_75-

V5 ofOct Nov Dec Jan Feb Mar Apr May

TotalAvg.b Record

St. Johnrs 0 1(0) 14(0) 39(12) ZC(9) 19(7) 23(12) 6(0) 122(40) 153(46) 19

Gander 0 12(1) 11(0) 11(2) 19(10) 33(8) 47(22) 0 133(43) 158(31) 19

Deer Lake 1(1) 19(13) 6(1) 2(2) 3(3) 2(2) 0 0 33(22) 43(22) 6

Daniels Harbour 2(2) 6(6) 0 2(2) 2(2) 6(4) 2(0) 0 20(16) 22(15) 6

Battle Harbour 0 0 0 0 0 4(1) 13(3) 3(3) 20(7) 49(17) 12

Goose Bay 3(2) 3(3) 2(2) 0 0 13(5) 13(0) 0 34(12) 35(15) 19


of the precipitation was freeun rain. Hattie Ha rhour and Goose Bay Vcrealso above normal, but St. John's was slightly below normal.. Only St. John'sand Battle I-Ta rbour recorded frening preci.jntaton during May.

nçtl! ficarit; auiount:s of ice were iu urcc.1 frec1t te tt:tr at S to 2 and4. SiLo 1 did not :L' coed any suwtanLLa1 ioinr during Ike oLi v;iiLerseason. At gLLe 3, minor ICinO Occurre on tour uccas LOflS. On T)ccenhur21, approxtmatcly 140 pounds of ice were recorded. Unfortunately, theMWS at Site 3 was iced up, and thus very low wind speeds were recorded.At Battle Harbour, northerly winds of 20 mph with peak gusts of 30 mphwere blowing. The cloud bases were around 3000 feet, with only occasionallight snow and snow flurries. This suggests that the lee was rime. Temper-atures were too low to suggest wet snow to be the cause.

On the three other occasions, less than 100 pounds of ice were re-corded. During the clay preceding one of those icing periods, Qr March 24,wind speeds pealceci at 35 mph; it is likely that the wind speeds were atleast as high during th ice arrurnulation as he ice built up oil fto. tviWS'sthroughout the day.

At Site 2 there were 12 periods ranging in duration from I to 166hours when ice accumulations eceeclod sin pounds per soot of cable. Ma;J-mum amount-s occurred at the end of the 10n2,est icing period, UoL'.veenJanuary 13-20, when 14, 5 oounds per foot was rccor clod. On the average,about 540 pounds of ice remained on the cable during the entire period,The cloud ba;es at Daniel's m'e less than 2000 feet, thetemperature at Site 2 was generally less than 0 l; therefore, it is likelythat roost of the ice nan in the 1.j:n of m-inie.

Upon examination of the Ice Rate Meter Ohart for the afternoon ofJanuary 19, is appears that the tower and [P.M were vibrating and the rimeice was being blown off the cable by the winds whose neak gusts undoubtedlyexceeded 100 mph, This would account for a gradual decrease of ice untilearly evening, when 150 pounds of ice rerriainecl on the line. This ice wasprobably a glaze coating that is not easily removed by wind and vibration.The ice then began to increase again, durin which time the winch was vib rat-ing the instrument, and another 570 pounds of ice, again likely to be rime,accumulated in only 14 hours. Late in the morning, this new ice droppedoff the cable, again leaving the 150 pound glaze ice base. Assuming a den-sity of 0. 5g/cm3 for the 570 pounds of rime and 0. 9 g/cm3 for the glazebase, the 720 pounds of ice translates into 4, 1 radial inches of ice. Bythis time the MWS's were gradually icing un; although the recorded windspeed was only 25 mph, the erratic IRIvI trace indicates that the winds werequite high. If the winds peaked at 50 mph during the period of maximumicing (not an unreasonable assuninL-ion), the t:mansverse wind load would beahmost five pounds per lineal foot (the diameter of the cable used was1.338 inches),

25


Unfortunately, \vwcl speeds during most periods of mnaxitnuui iceloads were not recorded due to the inability of preventing ice buj Id -up onthe ins irirncnta1i.on. Niaxirnurn co?lIbLnccl \Vi nd and ice loads niav haveoccur red on December IS. ilie hourly average wind s need was 70 mnhbefore tile U LiDS )IUW oIl; tui5 S CC[LI1VJ ent to a 01 --tnuiute \\ifli:U)Ced

90 iL1). The winds at 1,: il.s lOi..L' our v rctroni the e::L.-nerthUast

at Speeds up to 31 mob, WhiChl cuulu indicate Ihat the a.•e rn* heirl.y win.1

speed at Site 2 approached 100 mph. The 1RNI reco rdoci led cuuds ofice during this time before malfunctioning. At a density of 0, 5 g/ cn,this weight is equivalent to 3. 0 radial inches. At 70 mph, the ave ragetransve rse wind load was 7. 6 ioii per lineal toot. It is likely that 'vincigusts were niuc:h higher, and that more icc ac cumulate ci on the cable afterthe recorder failed,

rjIie climate in the vie mliv ot Site 4 is more coniinen1:a l Lhaii that atSite 2. This results in colder, drcr \vinters, and hence less icing duringlate Decenibe r, Janna ry, and February, as reflected by the icing data at

4. Icing that occurs in the fall and spring is usually in the fo 'm ofglaze ice that results from freezing rain. In mid-November 400 poundsof ice v.'as recorded. The MWSs were not in operation at this Lime; however,Battle Harbour reported light rain and. fog with winds gus ting as high as' 0 mph. Freezing rain could have bcc Falii.naat Site 4, wLb -100 noon:lsof ice translating uito two radial inchcs niT glaze. Significant ice loadingswere not recorded again until December 27, when 525 pounds aeenrciul.atedon the cable. T1is ice was likely in the form of rime, because cold Lcmoìra -tures yore urevalent over the entire area, fallacy and Feb:ea :y 'acre cry

Lo Iid I 1i (1(_ JL , ( ( 0on FcLn:nacv 25, the ti r)eratnrc rose ise tb. cnis nab 650 fl.nndkJ Qirimne ice, cqui\r lent to 3. 8 radial inches, vas roco rOod. iSp .o Lu ccc ndiai.inches remained on the cable \VIiCII the site waS servtcco on February 2Ice remaneO on the cable in varying amounts through l'1Lrch, Ca Mardi14- .1 5, approximately 340 pounds, or three radial inches, of rime combined\vitll a wind speed of 56 mph to produce an average transverse wind load of4. 8 pounds per foot. Higher wind gusts undoubtedly resulted in higher trans -verse loads. Ice recorded on March 25 appears to be glaze. iefnpcraturei$in the mnid-20 s were too cold for wet snov.' to occur. Freezing rain andcirizzl.c was reported at several Newfoundland stations, including Goose,and this was li.kely rcsponsblc to tlìc 490 pounds of ice \vhi ch was ec1uiVa-lent to slightly over two radial inches of glaze. Icing was frequent through-out April and lVlay, reaching a peak on May 7, when 650 pounds of ice wasrecorded. The synoptic situation on this day suggested that freezing rainwas failing in the area. Battle Harbour reported light rain, light snow,and ice pellets, with Leinperaturcs near freezing during this period. AtSite 4, average hourly winds ac companying the precipitation were as highas 45 mph. 1-Jowever, one of the two MWS1 s at the site was co mpietelyfrozen, suggesting that the other statjon may have been partially iced upThus, it iS pUS sible that wind speeds could have been even higher.

26


'I'he inds at Site 4 tcnd to be very steady at high speed. It has

1)0011 Obsei'VCd that tins StCa(ILI1CS S Cfl resu't il_i a resonant: •fi'ecjueflcj tietug

set up in the guys, c:able, and towers. This violent shaking may have been

responsible for a sliiLLin in the h'c luic ot Lli l1i recrdnr. ii. is un-

certain as to what e fleet this had Oji the raaguitude ol the tei.ii.on recu rdcd

by the IlM.

27


VI. REFINED LOADING ESTIMATES

Not all loading estimates were changed as a result of the 1974-1975measurement program. Also, several estiniates have been revised becauseof changes in the proposed route since the p].'oviOuS reports.

A. Changes in Route Segments

Segments 1, 2, 3, and $ remain essentially unchanged. St:noni 4,t:hc higher elevations west of Ciande. I.' Lake, is no longer necessary s iinc the

latest version of the proposed route crosses lower terrain to the south. Seg-mnents 5 tliro ugh 7, the portion of the route running from Grand Fails to

]3uchans and up tarough the 1-lumber Valley, have been e1iriinaLecl and are re-

placed by Segment 20, previously an atte mate route. Scg:ieriL 9 now runsfrom tne top of the ridge of the Long Range MouiLains to the west ceastal planeast-SoUtheaSt ol Portland CrroL. Segment 10 still runs along the west coastalplaiii, but it now extends from east of Portland Cre oh north o 51 N. T1e do -vaLun is general.ty less Ulml 300 i.rt. A now sonnt, 1 Oa, cuvcr he o r-tion ot the mute east of thi: high lands of St. lolci, who .rc the el .:VO Lion maa esfroni 500 to 1700 feet. Soinents 11 and 12 remained vi.rLu:.ity u:inged.

ugn1e cit 13, defined as that: portion of Segment 12 with elevations between500 and 1500 feet:, has boon shifted slightly \vost: of the orLginai route, resuic-ing in slightly lower elevations with less exposure to the east. The remainingportions of the proposed route are still described by Segments 14- through 37,20, and 23. The alternate routes to Goose Bay (Segments 18 and 19) and toStephenville (Segments 21 and 22) are no longer being considered in this report,

B. Refined Loading Estimates by Route Segment

1. Icing

The results of the 1974-1975 measurement program have not: indicatedthat a change in the icing estimates from the previous reports is necessary.With the exception of Site 2, no unusual ice loads were recorded or obscLved(luring a winter when icing appeared to be holow normal at most Newfowtdlancjstations. Site 2 did record severe ice buildups during the past winte m-, huttins was to be expected, and the estimates presented in the November, 1973,

28


report retlect this expcctaton. Ilowever, the proposed route has been shifted

from i.is nt-c VLOUS bc aton nea fate 2. to an a rea fu rLh. r en . The el. vat ba

is ene Lally lower, winch 3 PO rd 50103 -hc t(:e i'i hO n; L:R St. ?LP i S shouLd

resuit i ls; icing, altho :i-i hero at-e vet-ni p along die now i-uuLe

that are well. cxpos ccl to caste dy winds, which ii on hi be nea I y C: j oLdto the proposed route. 11 is dtfltcUlt Lo estimate the impact of this ciuirolltngeffect on the icing amounts in nil area where slight changes in elevation or ex-posure can result in large wind and icing differences, Two areas in questionare the high elevations on the west end of Inner Pond and a point on the routealmost directly cast of Site 2. It is likely that the icing in these areas issimilar to that at Site 2, and thus the November, 1973, estirdLates f. .... Segment9 are still valid. The rernainin portion of the t-oute segroe ot c t-oss log the iicLeshould have perhaps ten percent tess ice for each of the return periods.

..

2. un ads

The maximum gusts for all segments have been recalculated us tag the re -lationship of Sissenwine ct al. (1973) as was discussed in Section V. A. 1 * Thisviili result in slightly lower gust factors than were used in the Novelnho r, 1973

rt, The sus caineci \vLndS rorn which the :-g-cj u:-;ts we :e cal.celatodone -minute ave rage wind s pee cis . The v;iid seeds tic Led under the corn-

binod wtn0 and ice toads we t-o cic rlvec us nig onlu the wncts a;; docl.ated .;tUhicing. The method was des c ribed. in d::Lail in the i:; t-nernbe i-, 1)74, report.

;ird.s i;LiL on ra ass(:ia:.:n •.;ith

The 0110-unabLe ;Lv3 .c winds L.rd.;:1ed i.e h coL 1 oe,h , , ii,and 20, should remain unchanged frcrn Lose apse ring in th0 earhe;: :e.o ms.The ioturn period v:incis for Segment 13, the hi::hoe cbevnto;s no :h of theStrait of Belle Isle, were inc n'eas ccl due to info rmation gained from Site 4.Alt:hough the highest hourly average wind speed recorded during the past winterat the site was only1t 70 mph, eight percent of the winds were above 40 mph.This suggests a more gradual slope to the return period plot than was used inthe November, 1973, report. Thus, white the 50 -year rei:nrn period windSpeed for Segment 13 was increased by loss than ten percent, the ten-yearwind speed was increased by 20 percent. The winds for Segments 14 through17 and 23 were increased only slightly, also based Ofl the winds recorded atSite 4.

The peak winds recorded at Site 2 during the past winter were muchstronger than was previously expected. IL is obvious from these results thathourly average wind speeds in excess of 90 mph (or one-minute wind speedsin excess of 110 mph) occur there almost every year. The slope of the re-turn period plot should be small, like that of Segment 1 3 With those factsin mind, the ten-year return period value for Segment 9 was increased by

29


ainiost 60 PC rccnt to 126 iiph, while the SI) .year value of 110 mph is over

•t() ircerL iher L1an the 8 ph iveit in the earlier report. Tie pre-

vaituig cut ctwn fl1.S t)CCfl cIanr,ecI 10 C Lr1y ftoin the rt.h-iirLh eL iven

reviouly. Vi rtLuaily all of Llic s \\ curded at Site 2 we :'u froni

tine cast:erii cjaztnln.

Tables VI-1 through VI-4 give the 10-, 25-, 50, and 75-year return

period values for wind, ice, and conbined wind and ice for the 16 remainingjccrncnts of the Gull Islaiicl Transmission Line System. Whorever possibte,

•the segment numbers from the November, 1973, report wore retained in this

report. They are listed in order running from Holyrood in the east to Gull

Island in the west.

30


TABLE VI-l: 10-YEAR RETURN PERIOD VALUES

..............................................S. No.

I liolyrood to Whithouse

ç.: 500 ft

2 Whithourne to 10 miles

cst of Ciorenville< 500 ft)

3 10 miic vcst of Cinren-viIo to Gr..nd Fa11

N 803 itj

20 sr.d Fil to north end

c.t 1t'.l; r V.iIIey

8 rth c-nI of }:r Vntiey

t.' :.n of ridte of Long Ror.o3.oi:ts or. north s ule of

M.tjnRjv or 4° 50 N

(330 ft to 1200 ftC

9 Croin Long Range Moux-C 1200 ft to 1200 It)

10 A1or.g st Cntl PLiIn(8 500 it)

East side of 1iih Linds ofSt. John (500-1700 It)

11 51 N to Strait of Bi1c Isicnd($ 500 it)

\' ;- h• \v d1' ¶ i tv r - --. - . .- .. ----'-... -.

WindC I ( ..

Wind Spod Cot . nd . in lb/ft itnd. in lb/ft Speed R0. i 3;/f: I -L1. i n Ib/t

Dir. I (r.r.h ) (ub) bO1. In 11./ft (0.Oj (0.5) (n) (0.--

(0. )- --.--, . 1 - - -

-- --.- -S

r

w 7s 91 .: 2.9 17.4 3.S 35.0 0.8 1.5 40 2.2 11.3 2.4 7.2

U6 13 0 8 1 5 43 2 8 36 5 2 8 9 1W 80 97 3.5 23. 4.3 .4 . . : . . . .

wsw lo 36 2.4 12.9 3.1 10.8 1.2 2.6 36 1.7 7.7 .. 1.7 4.3

NNE 33 4 97 3.7 !5.5 3.5 13.l !.7 4,3 43 2.0 9.E, 2.! 5.9

1 4

p J

14>3W 62 77 - 2.2 11.3 1.7 4.3 1.4 3.2 36 1.4 5.3 3.0 2.0

126 1-13 3.5 21.6 7.3 46.2 - 1.7 .3 67 2.8 1-0.5 5.8 30.8

pSW 68 33 2.7 15.5 2.1 5.9 0.9 3.6 36 p 2.0 9.8 1.3 2.9

SW 20 '37 2.7 15.5 4.3 13.4 1.7 4.3 44 2.0 9.3 - 2.3 9.1

NNE ;-75 91 :.o 174 3.8 15.04 2.2 6.3 40 2.2 II.) 2.4 7.2

_@=n_. _ ------ --'--..ca- ,. .


TABLE VI-1: 10-YEAR RETURN PERIOD VALUES (Gontinu)

....:._rt'.ttn1.trr'Sts?trS1..t-tr.1tt... - ;.. .... A. •.. t.%fl.fl_- ,.ArA CtA.Ci_ A.;-A-:: ..zrr_.

-' 1.-t' c '- '' \i .'I - -. - - - - - ,- - - --- - -j-.--- -- - -

- C,.. ) Ct ex. __r

-1 * C . s I.'

i S 'o ( -ri) ( r (3 t (Q C)/ )

12 1t c,f tciic to 30S' ..coast

C ft

YCC r c(.r:r &( Cue0c ..

';.., 75 7,7 1' 2.! 2.2 (... 40 2.0 9, 1.3 2.9

13 a-st tSP) 00 't)S.-'c , j 1CR 1, - b 12 4 3 lU i - 2 2 1 3 -. 12 5.

. 0 :ri 10 .0 W .

(10ct 1400 It) NNW. .2 77 t.3 - 1,7 4.3 !4 3.2 36 0.5 1.0 2.0

15 S'.t''.V to £MOYW 2•(21500(t) N:w C?. 77 1.5 6.4 10.0 1.7 4.3 3. 0.8 2.7

:2 .2

16 £YO5W to C0'30'W( 2Oftart2proLCcted . -

' 1C1t / 53 CC 1" '' 2 t2 2t 32 0 1 7 3

17 60'30'WtoGui11.tkc 1'\ 1c,' ( > 1 00 I '-. / 63 1 3 1 C' 3 2 30 0 6 7 4 3

23 C.tL eCtc1ra_z

¶ NNV 33 0.0 1.5. 2.1 .: 0.3 ).3 36 0.5 1.2 2.3 2.5

- __J - - -- --

C-


TABLE VI-2: 25-YTAR RETURN PERIOD VALUES

Sc2. No.

I 1ioIvroo) to WhitSoure(< 500 It)

2 tbtttc to 10 iles

wt of Citrcttv1ie

(- 500 1:)

3 10 m.ie S vest of Claren-

yule to rond F.-tlIs

(' 530 It)

23 Cnd FUs to ncrth eod

8 \r(h cod of }:rohor VOlley

to top of ridc of Lottg Rattgeo oo ttortlt sjco of

3::t lUver

ft to 1203 It)

9 Ct-os.r. 1on Roto otn-toios u120i ft. to 1530 it)

20 A1oot west Co,t1 P1in5c,.t f)

ICa East hide of I ih ztndt ofSt. Joiri (5)0- 1700 It)

11 51 N to Strait of Belle IsleCs 500 It)

. .,

- -C -

S.joiIft : 1d.jo Ift

W 85 102 3.4 22.5 5.0 23,8 1.0 2.0 44 3.5 13.3 3.0 10.2

W 90 138 4.3 29.4 5.5 23.1 1.0 2.0 47 3.1 19.4 3.5 13.1

- V/SW 80 97 2.9 17.4 4.0 16.3 1.5 3.6 40 2.1 10.5 2.0 5.4

NNI2 53 133 3.2 20.-I 4.4 19,2 2.0 5.4 47 2.3 22.1 2.-I 7.2

I4NW 70 36 2.5 13.8 2.0 5.4 .a ,7 43 1.5 6.-: - 1.1 2.3

E 134 151 4.0 29.-i 8.5 60.3 2.0 5.-i 78 3.1 19.4 6.4 36.6

75 92 1.2 20.4 2.3 9.1 1.3 2.9 40 2.3 22.1 1.5 3.6

SV/ °3 33 3' 20-1 - E- 282 20 54 43 23 12.1 35 131

Nt 35 133 34 32.5 5.0 23.8 2.5 7.7 44 2.5 13.3 2.0 10.2


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Li • '0 '0 0) C) Wi 0) C)

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34


.......................

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01

TABLE VI- 3: 5O-EAR RETURN PERIOD VALUES

( S:r.l'.,:_____

"-... .- -.

. c ... .d - .

Sc o ._i (C' :'C- t cfla. - . . C

.._ .. ,flW ?*. c*.&rr y.. . 4. . - - .. _-_

orn'1-- t. .

cc.cto.

: '0(t) 93 10 3.3 27.0 5.7 39.-

1.2 2.t 48 23 10.5 34 12.5v

2 to 10 mi1o -

Carvi1ieW 93

S

110 4 4 6 2 34.6 iZ 2.0 51 3.4 22.3 3.9 15.7.

. .S.

3 10 1c west of C1.trc1- -

ville to L.r.\a(I Fii.q

$ f) WS\V 138 , 100 3. 3 21.4 • 4..! 21.4 1.8 4.7 4-1 Z. 3 12. I 2.4 7.2

:0 11s to rox-th ndcrV1ev NN3 93 110 3.6 24.7 5.1 24.6 2.3 6.7 51 2.6 14.7 2.3 9.1

S th l i 1:u:1- V.11cy

de offt t .; i :

t. en n.rth i1c of 9Mt1n r'4V50N -

C330ft11230i:C NNW 76 '2 3.1 19.4 1.2 6.3 2.0 5.4 44 . 2.0 9.E 1.2 2.6

9 C re sn Lon I'.n.e Mon- . .

t..tli00ftto1C00ft) 1-10 157 4.4 31.5 9.5 744 2.3 6.7 SI 3.4 22.5 6.8 40.7

10 A1-n Co.t1 P1Ai' 6 4 2 6 11 7 1 8 4 7

C0 SW 80-

)7 3.0 21.7 3. 11.3 1.5 3. 4 . . . .

Ca . jl of . S

St. Jch(50C-i7C0 SW 93 110 3.0 24.7 0.2 34.4 2.3 6.7 51 2.6 14.7 3.9 15.7

11 51'toSttofLillC1SC INE 93 110 3.8 27.0 5.7 2.9 I 2.7 S.6 43 2.8 16. 3.4 12.5

I 3_______________ .-.-__-

5... tas.a,

ç-_. -s...-.. - ______


TABLE VI-3: 50-YEAR RETURN PERIOD VALUES (Coitinied)

L)

'lo.

12 S:it of !t'Ii 11e coC d1c i::'d fr'

coa.t near corner ofQuc,cc (< 500 ft)

13 same area (590-1500 ft)

14 30 i1e S to 5640W(1000 it to 1490 ft)

15 5849W to 6005'W(?l.90i)

16 o °0W to 6)30'W( 1 i0 ( and protccedfrct n.rth)

17 6O0'W to Gn.11 akoVoilcy ( 10C ft)

23 C10l to Crj11Y...is (500-1600 :t

-. .. ç r

. nd - -- • nd .- ________

Wind peod C:.ti Rad. L 1S/ft. Rd. Lift Sreed Rad. Sr. 1.'f: 1'ad. Sr.Di:. Cn) 1) (19) •.; fr•) C.J) (9 5).

NN\V 93 113 3.6 24.7 3.2 13.3 2.7 8.6 •i 2.6 1-1.7 1.3 4.7

100 1 1 3.8 27.0 6.7 39.7 3.3 15.0 51 2.8 16.8 4.4 19.2

76 2 1 10 5 2 2 3 2 0 5 3 14 3 0 3 7 1 2 2 6

NN. 76 2 2.3 12.1 4.3 33.4 2.3 6.7 3.2 4.7 2.0 5.4

65 53 1.4 5.8 3.6 3.9 3.8 4.7 40 0.5 1.5 3.0 2.0

i'Ny. $0 2.1 30.5 1.7 31.4 2.0 5.4 -34 1.0 3.7 2.4 7.2

r; so 1.4 .o : 3.2 19.2 1.2 2.2 41 i05 2.2 1.3 4.0r

-


TABLE VI-4: 73.- YAR RETURN PERIOD VALUES

.................

:• --

-SS - . -

-

Sd 1/r rd. i R:td.

p ) Z.. ¶ 0 -) f - )_S •S•:

p.'

S• . . t.S. SS. ? S., ..? . SW.' -

i11 yrooc! to Vfl,itf,oroc115

:-9 28 2 ( 3 35.ô 1.3 2.9 50 2.9 17.-I .7 H.4

k SoOft) 97 . . .

2 Vtu:c to 10 rni1e .S

S wo.t f Chrcotillo .

35 3 6 8 40 7 1 3 2 9 53 3.4 22.5 -. 3 1L4(< SOOf:) 102 170 •.5 . . , . .

3 10 wtot of C1ar-

.ii1o to Crond Foils

( 00 ) . S\ 3 109 3 . 22 5 1 2- 6 2 0 4 ..6 2 4 1 3 - S

SI 20 C:,iF:stooorthtnd .

L 3 7 25 3 5 5 23 1 2 4 7.2 53 2.7 13.5 . 2.9 9.1of,crVi1ey NNE 102 0 . . . . ,

8 trth cd of I :m1or Volloy

toprdcoz_ongRc1

.

-

4

1utio o::th side of p.

£ •

7.1aI; ii-,er-9tO)i SV 30N ' 97 3 2 20.4 2.4 7.2 1 2.2 6.3 46 2.1 19.5 1.4 3.2

(Y3ftt 120)ft) N . .

Cro:1 !.o:' rtae Mou:-

t;.r.s (12)0 ft to 1300 ft) L 143 1)0 35.6 - 10.0 01.7 2.4 7.2 92 L 3.4 22.5 - 7.5 42.5

io Along wcst COnst 1'lain

(500ft) SW 83 1)0 3.7 25.24

lOa Ft1d of lu-h Lnd of . -:

St. 3.1.rp (500-1700 ft) SW 102 120 3.7 20.0

11 51' toStroit of Cello Isle27 2215 0V 500 fj N7:r-: 57 .1 .

3.5 13.1 1.7 4.3 46 2.7 15.5 .0 5.4

0.0 '10.7 2.4 7.3 53 2.7 13.5 -;.3 18.4

0.3 35.1 2,9 9.7 50 2.9 17.4 3.7 14.4


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38


VU. SIGNIFICANT RESULTS AND RECOMMENDATIONS

It is difficult to reach any absolute concIu o s has d on only- -

seven mouths 0! cii- site cata. Ho'ver, several oh S C .LO US Can be

macic:

0 The 1cm observed and/or measu'ec1 during the

vinter of 74- i97 a•a no norc e:':trcme thanhad been predicted in the earlier studies.

Less ice occurred at Site 1 than had been expec-ted; however, this was a relatively light: icing

year tiirouhout the P.ovi.nce.

0 Wi )( s r ecorrlc:l -.te 2 on te ridge Ot the

Lug :nge :::C

I t 35 :..-'i1CO

feet ove *e -fucc Ic Te '..Ie

greater than at any levels below :)OO feet in hc

free air u n:i earn of Lb e ridge, it 15 quite up -

parent that wi.ndspeeds at Site 2 result from

vcrtcal convergence ci the air stream as it is

forced i:w and over the obstrucrtng ridge, For

the Site 2 location, the return period values de-•

veloped for Segment 9 in the 1 973 s t:udy are much

too low, A now rebimn ucriod graph with a higher

average annual extreme windspeed but with less

slope was required. A niean annual extreme wind

of 110 mph and a 50-year return period of 140 mph

resulted,

o In a subjective sense, it appars that shifting the

line route eastward at the crossing of the Long

Range Mountains will result in some sheltering andreduce the wind loads on time line. The actual c1uan-

tit:ativc magnitude of this reduction is not readily

39


apparent. The wind speeds in 1-he more si iLe red

1)0 rt on are li hciy to U as much 2(3 pe rc ont

l()V?O'i thnn t )}LC ?. ov-:ever, crc t?,'c lo-

cations a1.on .C 110W ronic' \c)CC

comparable i 0 i to $ 1 utJ be c:-c 01-0(1. c0.!l

locations appear to be vulnerable to the full force

of the easterly winds. One location is at the top

of a small east-west canyon and nearly directly

east of Site 2. The other location is on the ridge

just before the route dips down to Inner Pond.

o Coulpari son of Winds easured at Site 4 with coresponding winds recorded at I3aLLJC 1iarboar re-

sulted in small increases in the rctni.;:n period values

predicted for the maiulnnd s egcrients of the' Le.Once agahi, the docrcaced slope of the grnhs re-sulted in greater increases in 1-he mean annual cx-

tre'mes in the 50-year return period values,

The combined wind and ice load estimates were re

- adjusted in accordance with the niothod des cribed

in tUe SepIeniJcr 1 97--, study using winds which

occurred in co.tri'uuctiou cith icin conditions

Once again, 'cni in 1-i :Si to are-a has theh1cst tra.-l:-corse nc-s, c: :inct; 3

winds with (n 8 :d.ia] inches of ric.e for ihe

return period value

0 Major uncerta,nteS exist jfl evat'u3a:ng 1-lie shc).ter-

ing which -will be achieved by re-routing to the east

of Site 2, The oni.v way to realistically determine

tue rnagnituue of tic sael1-erng is to instrument a

site in that: area in c onjimcti.on with instrumentation

at Site 2. 'Experience during the winter of 1974-

197 S dictates that power will be required to operate

deicing equipment if the wind recorders are to be

kept operational..

0 Of prime importance during the winter of 1975-1976is the erection of a 10 0-foot guyed tower to serveas a passive ice collector. This simple device will

40


serve as a visual indicator of the chan{e in iceaccunlulation \Vith IlC1'lLt. it was observed Ibatduring the 1971--- 1975 v:inter ice thickness on the30-foot: to'vers va id froni 6 iin:IlcS near thecrowic1 to Id inches near thc top. II: wiLt b im-portant that, to evaluate the effect of successivestorms, the ice be allowed to accumulate until itis melted or blown off. Pictures of this Lower-collector will need to he taken at each site visitas well as a written description of what is oh-served.

41


REFERENCES

Bonneville Power .A.drnini s:raLion, 1964: ''Distribution of e::tr erne windsin the SPA Service area '', U. S. I)epatnent of the inturior.

Boyd, D. W, , 1965: ''Climatic information for building design in Canada'',Supplement No. 1 to the National Building Code of Canada. NationalResearch Council NRC No. 8329, Ottawa,

Brook, R. R, and K, T. Spil].ane, 1970: "Tue variation of iund.mum windgust with hcight, 3. Mei:corol. , 9 (No. 1): 72-78.

Canin, 1). \V, , i96: ''Io': l:ci gut p1.tndc inat.ien :.dy'',T\t >5377 , Cc rge C. 'rv1J So..ce 'Jigt

I Iuntsvillc, L\.i:Wania,

Davenport, A. C. , 1968: 'The dependence of vind loads on in coroiogicalparameters l Paper 2, Wind Effects on Buildings and Stiucturos,Vol. I. University of Toronto Press, Toronto.

Davis, F. K. and H. Newstcin, 1968: "The variation of gust factors withirican wind speed and with height", J,Anpi:Me.I200roi., 7 (No. 3),37• 378,

DeMarris, C.. A, , 1959: ''Wind speed profiles at I3rockhave NationalLaboratory", J,Metcoroi, , 16 (No. 2), 181-190.

Durst, C. S., 1960: 'Wind speeds over short periods of time", M.eteoroi.

- Magazine, 89 (No. 1056), 181-186.

Johnson, 0, , 1959: ''An examination of vertical wind profile in the lowest

layers of the atmosphere'', J. Met:ciorol. , 16 (No. 9), 144- 148.

42


REFERFNCES (Continued)

ivtitsuta, Y, , 1962; "Gust factor and analysis time of gust', S. MeLee rol.Soc. (Japan), 40 (No. 4), 242-214,

Mwin, IL E. , 1966: "Descriptive riii.croineteorology ', Advances in Geo-physics, Academic Press, New ork and London,

Shellard, Ft. C, , 1965: ''The estimation of design wind speeds '', Windw? I' aLLUPU ITh, C O j[j )P

Syniposiutu (No, 16), p. 30-51.

She].iard, H. G. , 1963: Tables of surface 'ind speed and direction overthe United Kingdom", Metcorol. Off. 792, 11cr Majesty's StaLionaryOffice, London.

Sherlock, IL H. , 1952: ''Variation o wind velocity and gu;ts with height'',Papei No 2553, Proc km Sc Cjrlii, p 163 338

Sissenwine, N. , P. TatUeman, D. D. Granthan, and I, I. Gringorten,

1973 : ''Extreme wind ; eceds , gustiness, end variaLio13 vi ti higbt.

lam MIL-.S'IC 1) 21011'' Air Force :aO].'1dg:.ho s earch .L:*o 10 urics

Technica]. Recort 73-0360, Acronuny Labo caLory, Proj oct 3624,

72 pp.

43


Exhibit 74 - Meterology Research - Technical Reports · 2011. 9. 30. · L L 4 METEOROLOGY RESEARCH...

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Transcript of Exhibit 74 - Meterology Research - Technical Reports · 2011. 9. 30. · L L 4 METEOROLOGY RESEARCH...