il. 1in nk to corps of engineers walthan iii.' 'iithe test flood peak inflow of 175,000...

AD-AI5S 321 NATIOhAL. POWAN FOR INSPECTION OF NON4ISSNAL DMS Il.ELf.sn 00 1 O1j. .IUI CORPS OF ENGINEERS WALTHAN Il

* 0 Divu s To F/ 1/11IN I'l l ""0N NK m E N E

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I I

N ANDROSCOGGIN RIVER BASIN

ERROL, NEW HAMPSHIRE

ut)

,I ERROL DAM

NH 00161

NHWRB 80.01

PHASE I INSPECTION REPORTNATIONAL DAM INSPECTION PROGRAM

DEPARTMENT OF THE ARMY- NEW ENGLAND DIVISION, CORPS OF ENGINEERS

WALTHAM, MASS. 02154

MAN 1979 . ,

85 06 14 028

IINCI AS ETFTEDSECURITY LL ASSIFICATION OF THIS PAGE lWhn bOa. k-nlorodi

REPORT DOCUMENTATION PAGE READ INSTRUCTIONSBEFORE COMPLETING FORM

I REPORT NUMBER "2. GOVT ACCESSION NO I RECIPIENT'S CATALOG NUMBER

N[' 001614 TITLE (Aid Sulbt,11 ) 5 TYPE OF REPORT & PERIOD COVERED

Errol Dam INSPECTION REPORT

NATIONAL PROGRAM FOR INSPECTION OF NON-FEDERAL 6 PER0RMuiN OR. REPORT NUMBER

DAMS7 AUTOR- 1 CONTRACT OR GRANT NUMBER(&)

U.S. ARMY CORPS OF ENGINEERSNEW ENGLAND DIVISION

9 PERFORMING ORGANIZATION NAME AND AOORESS 10 PROGRAM ELEMENT PROJECT TASKAREA 4 WORK UNIT NUMBERS

Ii CONTROLLING OFFICE NAME AND ADDRESS 12 REPORT DATEDEPT. OF THE ARMY, CORPS OF ENGINEERS May 1979NEW ENGLAND DIVISION, NEDED ', NUMSER OF PAGES424 TRAPELO ROAD, WALTHAM, MA. 02254 7714 MONITORING AGENCY NAME A ADORESS(II dilloretnI ~ CdirI,.Illad Oile) IS SECURITY CLASS. (of this repor)

UNCLASS I FI EDI&& DECLASSIVICATION/DOWNGRAOING

SCHEDULE

16 DISTRIBUTION STATEMENT (ol thl i Aoporl)

APPROVAL FOR PUBLIC RELEASE: DISTRIBUTION UNLIMITED

17 DISTRIBUTION STATEMENT (ot the abtrIact mrtered In Bleck 20, It dIIlleornI 1" Report)

IS SUPPLEMENTARY NOTESCover program reads: Phase I Inspection Report, National Dam Inspection Program;however, the official title of the program is: National Program for Inspection ofNon-Federal Dams; use cover date for date of report.

19. K E Y WORDS (Conirlnue on reve ,. slde If noc.o.w' and Identlfy by block nflmbo.)

DAMS, INSPECTION, DAM SAFETY,

Androscoggin River BasinErrol, New HampshireAndroscoggin River

20 ABSTRACT (Conillnuiii ar reverse dO It necessary mr d Idel"Ity by block mna.lt. )

The dam was constructed of rock filled timber crib and an earth dike. -he max-imum height of the dam is 20 ft. The dam is considered to be in fair ccndition.Continuance of this classification depends on proper operations and maintenanceof the dam. It is large in size with a high hazard potential . There arevarious remedial measures which should be implemendted by the owner.

DD jAN 1473 11TOR O 1 NOV 63 IS OBSOLETE

DISCLAIMER NOTICE

THIS DOCUMENT IS BEST QUALITYPRACTICABLE. THE COPY FURNISHEDTO DTIC CONTAINED A SIGNIFICANTNUMBER OF PAGES WHICH DO NOTREPRODUCE LEGIBLY.

DEPARTMENT OF THE ARVIYz , NEA ENGILA,:N E'. CCRPE, Cr E%"i.EErS

4 24 T APE.C ,:A:

K-.-.WALTHAM MASSACHLSE7TE 02!5

D('r7 ):; £DED

I' Honorable Hugh J. Gallen

Governor of the State of New HampshireState HouseL -Concord, New Hampshire 03301

Dear Governor Gallen:

I am forwarding to you a copy of the Erroll Dam Phase I InspectionReport, which was prepared under the National Program for Inspection of'ion-Federal Dams. This report is presented for your use and is basedupon a visual inspection, a review of the past performance and a brief1'vdrolozical study of the dam. A brief assessment is included at the'eginning of the report. I have approved the report and support thefindings and recommendations described in Section 7/ ar. ask that you

keep me informed of the actions taken to implement them. This follow-upaction is a vitally important part of this program.

A copy of this report has been forwarded to the 'ater Resources Board,the cooperating agency for the State of New Hampshire. In addition, acopy of the report has also been furnished the owner, Union Water PowerCompany, 150 Main Street, Lewiston, Maine 04240.

Copies of this report will be made available to the public, uponrequest, by this office under the Freedom of Information Act. In thecase of this report the release date will be thirty days from the dateof this letter.

I wish to take this opportunity to thank you and the Water ResourcesBoard for your cooperation in carrying out this program.

Sincerely yours,

As stated Colonel, Corps of EngineersDivision Engineer

I

'a

Ac~'sion For

ERROL DAM 7k

NH 00161

N5WRB 80.01 -r

Dt 't .,'j l r

Dist

ANDROSCOGGIN RIVER BASINERROL, NEW HAMPSHIRE

PRASE I INSPECTION REPORTNATIONAL DAM INSPECTION PROGRAMI

I

9

,, ,I I I

NATIONAL DAM INSPECTION PROGRAMPHASE I INSPECTION REPORT

Identification No.: NE 00161Name of Dam: Errol DamTown: ErrolCounty & State: Coos, New HampshireStream: Androscoggin RiverDate of Inspection: June 29, 1978

BRIEF ASSESSMT

The towns of Errol and Berlin are located 1/2 mile and 8 miles,respectively, downstream of the Errol Dam. Errol Dam was constructedof rock-filled timber crib and an earth dike. The maximum height ofthe dam is 20 feet. The distance between abutments is 184 feet, andthe total width of the sluice gates is 121 feet. This dam has twelvesluice gates and no spillway, and therefore, it may be called a bar-rage. It was built on crib foundation with a wooden plank apron.

Based on visual inspection and hydraulic/hydrologic evaluation,the overall condition of the dam is considered to be fair. The oldtimber cribs were observed to be in fair condition. Some leakage atthe gates and cribs was noted. Visual inspection did not reveal anyevidence of instability. Continuance of this classification dependson proper operations and maintenance of the dam.

This dam falls under the category of high hazard potential, andit is large in size. The test flood peak inflow of 175,000 cfs wouldresult in a peak outflow of about 108,000 cfs at the dam after routingthrough the upstream lake. Hydraulic analysis indicates that such aflood would produce an upstream level to Elevation 1269.4 ft. msl,overtopping the earth dike section of the dam by about 17.4 feet. Theestimated tailwater at the dam under such a flood condition would bein the order of 1259 which would also be several feet over the top ofthe dam at Elevation 1252 ft. msl. It would, therefore, not be pos-sible to provide sufficient spillway capacity at this project to pre-vent overtopping of the dam under test flood conditions. With thistype of structure, it is important to have sufficient discharge capac-ity so that during a major flood the difference between headwater andtailwater would not be sufficiently great to produce a major surge ifthe dam were breached. Preliminary tailwater computations indicatethat with a normal full pool discharge capacity of 16,000 cfs therewould be little difference between headwater and tailwater and withthe pool at top of the dam, the discharge would be an estimated 40,000cfs and the differential head in the order of 3 feet.

i

9

Within two years after receipt of this Phase I report by the

owner, more detailed hydraulic studies are recommended to better esta-

blish the discharge and tailwater characteristics of the project andthe extent of damage that might occur at the dam and in downstreamareas in the event of a major flood.

The following remedial measures, as stated in Section 7.3,should be implemented:

1. Maintenance program of the owner should be continued. This

would include his ongoing program of replacing all the

wooden crib piers by precast concrete crib piers.

2. Vegetation should be removed from the dike embankment except

for grass that prevents slope erosion.

3. A program of technical biannual periodic inspection of the

project features should be prepared and initiated.

4. Surveillance and a formal warning system be developed for

periods of usually heavy rains and runoff.

FAY, SPOFFORD & THORNDIKE, INC.By

/ugi.s Gimbutas, P.E.

JUGI ,,,Project Engineer

* 6131 0 / / / L

Richard W. Albrecht, P.E.

SVice President

ii

This Phase I 2nspection Report on Errol Ca-has beer revie-ed by the U"ersicned Revie' Board r.c;ni.z, the re orted fincirgs, cor.clusions, ard re :o .c'S ;re

c.ns-nste, t 7,- the i n-r : - es fcr S::.'

of and with good engineering judcrment and practice, a.,, Ishereby subcitted for approval.

C- E , S ". T .. T h a.

Chief, Foundation and I, aterials EranhEngc reering Division

3 V WNC7ie, , D-- c SrArch

Zri ~erig . sion

C,ef, ae ter Control BranchEngineering Division

APPROVAL RECOVUNDED:

JOE B. FRYARCtief, Engineering Division

PREFACE

This report is prepared under guidance contained in the Recom-mended Guidelines for Safety Inspection of Dams, for Phase I Investi-gations. Copies of these guidelines may be obtained from the Officeof Chief of Engineers, Washington, D.C. 20314. The purpose of aPhase I Investigation is to identify expeditiously those dams whichmay pose hazards to human life or property. The assessment of thegeneral condition of the dam is based upon available data and visualinspections. Detailed investigation, and analyses involving topo-graphic mapping, subsurface investigations, testing, and detailed com-putational evaluations are beyond the scope of a Phase I investiga-tion; however, the investigation is intended to identify any need forsuch studies.

In reviewing this report, it should be realized that the re-

ported condition of the dam is based on observations of field condi-tions at the time of inspection along with data available to the in-spection team. In cases where the reservoir was lowered or drainedprior to inspection, such action, while improving the stability andsafety of the dam, removes the normal load on the structure and mayobscure certain conditions which might otherwise be detectable if in-spected under the normal operating environment of the structure.

It is important to note that the condition of a dam depends on

numerous and constantly changing internal and external conditions, andis evolutionary in nature. It would be incorrect to assume that thepresent condition of the dam will continue to represent the conditionof the dam at some point in the future. Only through continued careand inspection can there be any chance that unsafe conditions be de-tected.

Phase I inspections are not intended to provided detailed hydro-logic and hydraulic analyses. In accordance with the establishedGuidelines, the Spillway Test Flood is based on the estimated *Proba-ble Maximum Flood" for the region (greatest reasonably possible stormrunoff), or fractions thereof. Because of the magnitude and rarity ofsuch a storm event, a finding that a spillway will not pass the testflood should not be interpreted as necessarily posing a highly inade-quate condition. The test flood provides a measure of relative spill-way capacity and serves as an aide in determining the need for moredetailed hydrologic and hydraulic studies, considering the size of thedam, its general condition, and the downstream damage potential.

iv

TABLE OF CONTENTS

PazILetter of TransmittalBrief AssessmentReview Board Signature Sheet iiiPreface

ivTable of Contents vOverview Photograph

viiiLocation Map ix

[ REPORT

SECTION I - PROJECT INFORMATION 1

1.1 General 1

a. Authority 1b. Purpose 1

1.2 Description of Project 1a. Location

1b. Description of Dam 2c. Size Classification

3d. Hazard Classification 3

e. Ownership 3f. Operator

3g. Purpose of Dam 3h. Design and Construction History 4i. Normal Operational Procedure 4

1.3 Pertinent Data 5

a. Drainage Area 5b. Discharge at Dam Site 5

c. Elevation (Feet above MSL) 5d. Reservoir

6e. Storage (Acre-Feet) 6f. Reservoir Surface (Acres) 6g. Dam 6

h. Spillway 7i. Regulating Outlet 79 J. Dike 7

SECTION 2 - ENGINEERING DATA 9

2.1 Design 9

V

R

2 Construction 9

2.3 Operation 92.4 Evaluation

9a. Availability 9b. Adequacy 9c. Validity

9

SECTION 3 - VISUAL INSPECTION 10

3.1 Findings 10a. General 10b. Dam 10c. Appurtenant Structures 10d. Dike 10e. Reservoir Area 11f. Downstream Channel 11

3.2 Evaluation 11

SECTION 4 - OPERATIONAL PROCEDURES 12

4.1 Procedures 12

4.2 Maintenance of Dam 12

4.3 Maintenance of Operating Facilities 12

4.4 Description of any Warning System in Effect 12

4.5 Evaluation 12

SECTION 5 - HYDRAULIC/HYDROLOGIC 13

5.1 Evaluation of Features 13a. Design Data 13b. Experience Data 14c. Visual Observations 14d. Overtopping Potential 14

vi

Ii

Paze

SECTION 6 - STRUCTURAL STABILITY 1I

6.1 Evaluation of Structural Stability Ir

a. Visual Observations 15b. Design and Construction Data 15

c. Operating Records 15d. Post-Construction Changes 15e. Seismic Stability 1E

[ SECTION 7 - ASSESSMENT, RECOMMENDATIONS &RFISiEDIAL MEASURES 16

7.1 Dam Assessment 16a. Condition 16b. Adequacy of Information 16c. Urgency 16d. Need for Additional Investigation 16

7.2 Recommendations 16

7.3 Remedial Measures 16

7.4 Alternatives 17

APPENDIX A - VISUAL INSPECTION CHECK LISTS A-I

APPENDIX B - EXISTING AVAILABLE INFORMATION B-1

APPENDIX C - PHOTOGRAPHS C-I

APPENDIX D - HYDROLOGIC & HYDRAULIC COMPUTATIONS D-1

APPENDIX E - INFORMATION AS CONTAINED IN THE NATIONALINVENTORY OF DAMS E-1

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GEOLOGICAL SURVEY SCL SCIZSCNi STEAM

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INDIAN STREAM QuAD ANS$I *,5 JIM POND QUADRANGLE i9fERROL OQJAORANG E '932 QUILL HILL QuA:,PAN3LE j9%MILAN QUADRANGLE 933 OOUOSSOC QUADRANGLE 1945

MOOSE BOG QUADRf.NCE 192" CUPSUPTIC QUADIRdINGLE 19!,NEW HAPS~iRERANGELEY OjAZ0RANGLE 1933-43NE HMP~~REBLACx MTN 0Q)ADPANSLE f969DIXVILLE QUADRANjLE 1930 ARNOLD POND QUAD)RANGLE '932

CHAIN OF PONOS OJA RANG.E 1969OLD SPECK MTN OLADRANZCLE 194!

KENNEBAGO LAKE QUADRANGLE9'

ERROL DAY

SECTION 1 - PROJECT INFORMATION

L 1.1 General

a. Authority

Public Law 92-367, August 8, 1972, authorized the Secretaryof the Army, through the Corps of Engineers, to initiate a NationalProgram of Dam Inspection throughout the United States. The New Eng-land Division of the Corps of Engineers has been assigned the respon-sibility of supervising the inspection of dams within the New EnglandRegion. Pay, Spofford & Thorndike, Inc., have been retained by theNew England Division to inspect and report on selected dams in theState of New Hampshire. Authorization and notice to proceed was is-sued to Fay, Spofford & Thorndike, Inc., under a letter of May 3,1978, from Mr. Ralph T. Garver, Colonel, Corps of Engineers. ContractNo. DACW33-78-C-0308 has been assigned by the Corps of Engineers forthis work.

b. Purpose

(1) Perform technical inspection and evaluation ofnon-Federal dams to identify conditions which threatenthe public safety and thus permit correction in atimely manner by non-Federal interests.

(2) Encourage and prepare the states to initiate quicklyeffective dam safety programs for non-federal dams.

(3) To update, verify, and complete the National Inventoryof Dams.

1.2 Description of Project

a. Location

Errol Dam is located in the town of Errol, which is in thenorthern part of the state of New Hampshire. The dam is built acrossthe Androscoggin River, about three miles west of the confluence ofthe outlet of Umbagog Lake and the mouth of Magalloway River. In thecenter of the town, approximately 1/2 mile downstream of the dam, theriver makes a turn to the south. The dam is 167.1 miles above thetidewater at Brunswick, Maine.

I

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b. Description of Dam

Errol Dam is a rock-filled crib structure made of timber,concrete, and steel. The crib is 4 feet to 6 feet deep and extendsfrom heel to toe and from the south abutment to the north abutment.

On this crib foundation, the crib piers were constructed and betweenthese piers, the wooden gates were installed. There is a wooden plankflooring in each bay in front of and in back of each sluice opening upto the end of the crib piers. This wooden plank flooring was anchoredto the cribs below the riverbed. The maximum structural height is 20feet, and the length between the abutments is 184 feet.

As there is no spillway, the flow is controlled by twelvegates which are located for the full length of the dam. Five of thegates are 15 feet wide and 10 feet high and are referred to as sluicegates (Photographs No. 1, 5, and 6, Appendix C). Seven of the gatesare near the northwest abutment and are 10 feet high, with the widthsvarying from 5 to 7 feet. The sills of these seven gates are at Ele-vation 1232.0, 20 feet below the permanent crest of the dam, and theyare referred to as deep gates (Photographs No. 6 and 12, Appendix C).The sills of the sluice gates are several feet higher than the sillsof the deep gates. The total width of all gates is 121 feet. Thegates are separated"by piers or king posts with braces. The structur-al support of this dam consists of a series of piers. They are eitherconcrete or timber cribs, filled with stone (Photographs No. 2, 3, 5,and 7, Appendix C).

There is a gate house for the full length of the dam. It isa wooden structure covered with corrugated metal housing the gate op-erating equipment. Rodney Bunt hoists were installed on all deepgates except the small northerly gate. An electric motor is providedfor every two deep gates with the option to connect the electric motorto one or two gates at a time. The five large sluice gates are me-chanically operated by a movable gasoline driven pulley and belt, asreported in the 1971 inspection. An additional movable gasoline motordrive is provided for backup. Either of the two movable gasoline mo-tors being used to operate the large sluice gates can also be used forthe operation of the deep gates (Photographs No. 1, 9, and 10, Appen-dix C).

On the left bank of the river, there is an earth dike abut-ting the southeast abutment of the dam (Photograph No. 12, AppendixC). The total length of the dike is about 230 feet. There is a103-foot long concrete core wall adjacent to the dam abutment, withthe bottom at Elevation 1240 and the top at Elevation 1252. Recentlyto reinforce the old concrete core wall, steel sheet piling was drivenon the upstream side of that abutment. This new cut-off wall is 40feet long with 9 feet extending into the river on the upstream side of

2

I

the dam. The bottom elevation of the sheet piling is 1225. The topelevation is approximately 1252.

There is a footbridge from one abutment to the other on theupstream side of the gate house (Photographs No. 2 and 4, Appendix C).

c. Size CLassification

The storage capacity of Umbagog Lake at average spring fillelevation of 1247.0 is 80,000 acre-feet, which is greater than 50,000acre-feet. Therefore, on the basis of Table 1, Size Classification,in the "Recommended Guidelines for Safety Inspection of Dams," fur-nished by the Corps of Engineers, Errol Dam is classified as large.

d. Hazard Classification

In the event of failure of this dam, the town of Errol andthe town of Berlin, which are at a distance of about 1/2 mile and 8miles downstream of the dam, respectively, will be in danger of beingflooded. The depth of water at the possible damage impact area, asshown in Appendix D, is estimated. It is also estimated that in theevent of failure of this dam, loss of more than a few lives and exces-sive property damage would probably occur. Therefore, on the basis of

Table 2, Hazard Potential Classification, in the "Recommended Guide-lines for Safety Inspection of Dams," furnished by the Corps of Engi-neers, this dam falls in the category of high hazard potential.

e. Ownership

The Union Water Power Company was and is the owner of theErrol Dam and has control of the use and flow of the waters of theAndroscoggin River and its tributaries. This company is a water stor-age and industrial water sales company established in 1878. Prior tothat time, Androscoggin River Improvement Co. owned the old Errol Dam,which was replaced by the present dam in 1887.

f. Operator

The Union Water Power Co., 150 Main Street, Lewiston, Maine04240, telephone (207) 784-4501, is the operator through its agent Mr.

4 William M. Groove. There is a local attendant, Mr. Carl Littlehale,who lives near the dam and is on duty twenty-four hours a day.

g. Purpose of Dam

The purpose of this dam is to store water and regulate theflow from Umbagog Lake for generation of power in several downstreamplants. Prior to 1880, all dams in this system were used to regulate

3ti

the flow for log driving. Presently, log driving is a secondary pur-pose of the dam as the conservation of water is the primary purpose.

h. Design and Construction History

The first Errol Dam was built in 1853, as a part of a systemto facilitate log driving. The present dam was built in 1887, as atimber crib structure, after the original dam was washed out. Avail-able data indicate that the dam is founded on both ledge and hardpan.

Since 1947, the Union Water Power Co. has been replacing thetimber cribs on the downstream side with precast concrete cribs. In1950, six principal piers on the upstream side were reconstructed in

timber with all cribs or piers filled with stone. These repairs wereapproved by the New Hampshire Water Resources Board. During the fol-lowing years, additional repairs were done on the downstream side ofthe gates and all five sluice gates were rebuilt.

The maintenance program in 1962, included extensive recon-struction, such as, replacement of all king posts and braces; renewalof all deep gates; replanking of flooring and aprons, and driving ofsteel sheet piling on the upstream side. The petition for this recon-struction was granted to the owner by the New Hampshire Water Re-sources Board on December 18, 1961. During 1963 and 1964, the remain-ing timber cribs on the downstream side were replaced by precast con-crete cribs.

In 1972, a 2-inch, hand-placed plank cut-off wall reinforcedwith polyethelene was constructed upstream of the dam with new stoneplaced to the elevation of the existing concrete cap. The wood walk-way was replaced with steel grating.

Since 1968, Rodney Hunt hoists have been installed at alldeep gates, except at No. 12, and at two sluice gates, Nos. 3 and 4.In 1977, a wooden sluice crib pier on the upstream side was replacedby a new precast concrete pier.

i. Normal Operational Procedure

This dam is operated jointly with Aziscohos Reservoir andthe Middle, Upper, and Rangley Dams to insure that the regulated flowat Berlin will be maintained at not less than 1,550 cfs. Impoundmentis increased during the spring runoffs to ensure sufficient storagefor this flow during late summer.

An attendant is on duty twenty-four hours a day and livesnear the dam site. Therefore, around-the-clock surveillance is pro-vided. The attendant adjusts the rate of flow by using a calibration

I 4I

chart, discharge vs. gate openings. Flow rates may be varied at thediscretion of the attendant or at the direction of the Union WaterPower Co.

The dam is inspected yearly by Androscoggin Reservoir Co.,of which the Union Water Power Co. is a member. Remedial action istaken at their recommendation. Independent consultants have been re-tained at irregular intervals to inspect this dam..

1.3 Pertinent Data

a. Drainage Area

Umbagog Lake is a natural one. Errol Dam was constructedacross the Androscoggin River, about 3 miles west from the outlet inUmbagog Lake. The total drainage area above the dam is 1,095 squaremiles. The watershed area is heavily wooded and of mountainous topog-raphy.

b. Discharge at Dam Site

(1) There are no conduits, but there are twelve sluicegates.

(2) The maximum known flood at the dam site is the flood of1917, and the corresponding maximum level of record is18.75 or 1250.75 msl.

(3) The ungated spillway capacity is not applicable asthere is no spillway.

(4) The total discharge capacity of all the gates when they

are fully opened is 16,300 cfs.

c. Elevation (Feet above MSL)

(i) Top of dam - 1252.0.

(2) Maximum pool elevation 1269.4. This value is obtainedby routing test flood peak inflow through Umbagog Lake.

4 (3) Full lake pool - 1247.0. It is assumed that the recre-ation pool elevation is the same as the average springfill elevation.

(4) Invert elevation of deep gates - 1232.0.

(5) Invert elevation of sluice gates - 1237.0.

5elvaio

(6) Stream bed at centerline of dam - 1228. (estimated)

(7) Maximum tail water elevation 1259.5. This value cor-responds to the test flood peak outflow fro the tailwater rating curve below the dam site. Refer to Appen-dix D.

d. Reservoir

(1) Length of maximum pool - 11 miles (estimated)

(2) Length of full lake - 10 miles (estimated).

e. Storage (Acre-Feet)

The following values have been estimated from project rec-ords:

(1) Full lake pool - 80,000 acre-feet.

(2) Design surcharge - unknown.

(3) Top of dam - 105,000 acre-feet.

f. Reservoir Surface (Acres)

(1) Top of dam - 10,100 acres (estimated).

(2) Full lake level - 8,850 acres (estimated).

g. Dam

(1) Type Rock filled crib

(2) Length 184 feet

(3) Height 20 feet

(4) Top width 30 feet

(5) Side slopes Vertical

(6) Zoning None

(7) Impervious core None

6

!,

(8) Cutoff 2-inch planks reinforcedwith polyethylene at up-Stream toe

(9) Grout curtain None

h. Spillway None

i. Regulating Outlet

(1) 5 sluice gates

(a) Invert 1237.0 msl

(b) Dimensions 15 feet wide by 10 feethigh

(c) Description Wooden gates

(d) Control mechanism Electric and gasolinemotors with manual backup

(2) 7 deep gates

(a) Invert 1232.0 msl

(b) Dimensions 5 gates - 7 feet wide by10 feet high; 1 gate - 6feet wide by 10 feethigh; 1 gate - 5 feetwide by 10 feet high

(c) Description Wooden gates with RodneyHunt hoists

(d) Control mechanism Electric and gasolinemotors with manual back-up, One gate nonoperable

j. Dike

(1) Type Earth embankment

(2) Length Approximately 550 feet

(3) Height Approximately 20 feetg (4) Top width 21 feet

!7

I

(5) Side Slopes I vertical to 2 horizontal

(6) Cutoff Steel sheeting and con-crete core wall adjacentto the northeast abutment

,IIw[!

II

SECTION 2 - ENGINEERING DATA

2.1 Desia.n

No original design data was disclosed for Errol Dm. Borings,dated 1930 and 1944, and a ledge topographic map was obtained fromproject records. The borings in 1944 were drilled for a new dam toreplace the existing dam. See Appendix B for the borings drilled in1930. The sketches of the sluice gates identifying pertinent hydrau-lic features and dimensions relevant to the determination of the dis-charge capacity are included in Appendix B.

2.2 Construction

No engineering data are available on the construction of thisdam.

2.3 Operation

The gate openings from the south abutment are numbered 1, 2, 3,4, and 5, and they are called sluice gates. For operational purposes,a hydraulic engineer prepared a calibration chart which reads "Head onsill of sluice gates versus discharge for different openings (as aparameter)." A similar calibration chart was prepared for the deepgates numbered 6, 7, 8, 9, 10, 11, and 12. The operator uses thesetwo calibration charts and the gage reading to determine the number ofgates to be opened and the required opening of each gate.

2.4 Evaluation

a. Availability

Pertinent structural, geotechnical, hydrologic, and hydrau-lic data, which formed the basis of the design of the dam, are avail-able on a limited basis.

b. Adequacy

Sufficient engineering data are available for a Phase I in-spection.

c. Validity

The available engineering data is considered valid on thebasis of the results of the visual inspection.

9

SECTION 3 - VISUAL INSPECTION

3.1 Findincs

a. General

The Phase I inspection of Errol Dam was performed on

June 29, 1978. A copy of the inspection check list is included in Ap-

pendix A.

In general, the soil and rock features are in good condi-

tion. The steel and concrete structures were observed to be in goodcondition, see subparagraph c.

b. Dam

The dam is in good condition. No evidence of vertical or

horizontal misalignments was observed nor was there any evidence ofseepage or piping.

The dam was observed to consist of both timber and precast

concrete cribs. The exposed parts of the timber cribs are old wood,but not rotten, with just a few visible checks and vertical cracks.

Therefore, it can be considered to be in fair condition. The precastconcrete cribs were observed to be in good condition. Leakage of thegates and cribs was noted.

c. Appurtenant Structures

The concrete of the north abutment above the water level was

observed to be in good condition. Joint alignment is generally good,

and no erosion was noted. The steel footbridge and the aluminum rail-ing was in good condition with the longitudinal members rusting in

places. Field observations indicate that the gate house, a wooden

structure covered with corrugated metal, is in good condition.

d. Dike

The dike is in fair condition with no evidence of vertical

or horizontal misalignments. There is no indication of sloughing,bulging, or movement of the slopes; nor is thiere evidence of seepageor piping. No riprap was observed on either slopes.

e Vegetation was noted on both the upstream and downstreamslope and top of the dam. There are small bushes, trees, and grass onboth slopes. (Photograph No. 12, Appendic C.)

10

e. Reservoir Area

Umbagog Lake is a natural one. The storage area of the lakeis about 15.8 square miles. The lake is surrounded by mountains anddense forest.

f. Downstream Channel

The downstream channel and side slopes are in good condition.

3.2 Evaluation

The observed condition of the dar is good. The potential prob-

lems observed during the visual inspection are listed as follows:

a. Questionable condition of the old timber cribs underwater.

b. Potential for overtopping.

c. Leakage of the gates.

I

| 11

,I

SECTION 4 - OPERATIONAL PROCEDURES

4.1 Procedures

The Union Water Power Company has operated Errol Dam since it

was constructed in 1887. The only control available to maintain orlower the lake level is the twelve sluice gates. These gates are ope-rated by electric and gasoline motors with manual backup. This dam isoperated jointly with Aziscohos Reservoir and the Middle, Upper, andRangley Dams to ensure that the regulated flow at Berlin will be main-tained at not less than 1,550 cfs.

4.2 Maintenance of Dam

The maintenance of Errol Dam is the responsibility of the UnionWater Power Co. who controls the use and flow of the waters of theAndroscoggin River and its tributaries. Since 1947, the Union WaterPower Company has been replacing the timber cribs on the downstreamside by similar precast concrete structures. In 1950, six principalpiers on the upstream side were reconstructed in timber. In the fol-lowing years, additional repairs were done, see Section 1.2h.

4.3 Maintenance of Operatino Facilities

The dam is inspected yearly by the owner's engineering staff anddaily by the attendant residing near the dam site. Maintenance of thefacilities to operate the sluice gates controlling the flow throughthe sluice openings is considered to be good.

4.4 Description of any Warning System in Effect

There are four reservoirs upstream of Umbagog Lake, and they areall owned by Union Water Power Co. The operators of these reservoirsare in contact by radio, and therefore, they do have a flood warningsystem.

4.5 Evaluatio.

The operational and maintenance procedures consisting of daily

and yearly inspections should ensure that all problems encountered canbe remedied within a reasonable period of time.

12

SECTION 5 - HYDRAULIC/HYDROLOGIC

5.1 Evaluation of Features

a. Design DataL

(1) This dam falls under the category of high hazard poten-tial, and it is large in size. Using the 'RecommendedGuidelines for Safety Inspection of Dams," the recom-mended spillway test flood peak inflow would be equalto the probable maximum flood. Since the basin of thisdam has so much storage, the probable maximum floodpeak inflow is not applicable.

Flood studies conducted in 1959, by Chas. T. Main,Inc., for a proposed dam approximately 1/2 mile down-stream from this dam, yield a spillway inflow hydro-graph with a peak value of 175,000 cfs. Therefore, the

adopted test flood peak inflow is 175,000 cfs.

(2) The computed peak outflow corresponding to the routedtest flood peak inflow through Umbagog Lake (assumingearth dike remains intact after being overtopped) is108,500 cfs. Refer to Appendix D for details.

(3) The lake storage capacity versus the elevation, an es-timated capacity curve is included in Appendix D.

(4) The discharge rating curve for the twelve sluices isfurnished in Appendix D.

(5) The composite discharge rating curve for pool levelsabove the top of earth dike (assuming earth dike andbarrage structure remain intact) is furnished in Appen-dix D.

(6) The tail water discharge rating curve immediately belowthe dam site, including elevation corresponding to com-puted peak outflow is furnished in Appendix D.

(7) The hydrologic map of the watershed above the dam (bar-rage) site, including the reservoir area and the water-course, is furnished in Appendix D.

13

II

b. Experience Data

Major floods occurred in 1917 and 1969. The maximum watersurface level attained during the flood of 1917 was 1250.75. The max-imum, flow recorded for May, 1969, was 16,300 cfs. All the gates wererequired to be fully opened during the floods of 1917 and 1969.

c. Visual Observations

At the time of inspection, rate of flow through the sluicesinto the downstream channel was 2,500 cfs. All the sluice gates arevertical lift gates. These gates slide along the channels ofI-beams. The width of Androscoggin River bed immediately downstreamof the dam is about 150 feet. The side slopes of the river are notsteep. The left bank is approximately 10 to 12 feet high, and theright bank is about 20 to 25 feet high. In 1947, about 0.4 of a miledownstream of the dam, U.S.G.S. established a stream gaging station(Indian Bay Gage) at Errol.

Near Errol Dam there are two stage gaging stations. One isa lake gage and the second one is near the dam. The lake gage readingat the time of inspection was 13.75 or 1245.75 msl.

Minor leakage of water through the edges of Sluice GateNo. 1 (adjacent to the south abutment) was noticed.

d. Overtopping Potential

The test flood peak inflow of 175,000 cfs would result in apeak outflow of about 108,000 cfs at the dam after routing through theupstream lake. Such a flood would produce an upstream level to Eleva-tion 1269.4 ft. msl, overtopping the earth dike section of the dam byabout 17.4 feet. The estimated tailwater at the dam under such aflood condition would be in the order of 1259 which would also be sev-eral feet over the top of the dam. It would, therefore, not be pos-sible to provide sufficient spillway capacity at this project to pre-vent overtopping of the dam under test flood conditions. With thistype of structure, it is important to have sufficient discharge capac-ity so that during a major flood the difference between headwater andtailwater would not be sufficiently great to produce a major surfge ifthe dam were breached. Preliminary tailwater computations indicatethat with a normal full pool discharge capacity of 16,000 cfs therewould be little difference between headwater and tailwater and with

Uthe pool at top of dam, the discharge would be an estimated 40,000 cfsand the differential head in the order of 3 feet.

14

II

SECTION 6 - STRUCTURAL STABILITY

6.1 Evaluation of Structural Stability

[a. Visual Observations

The upstream slopes could not be seen due to the fact thatit was underwater. The slopes of the dike do not show any erosion orother weak areas. The visual inspection revealed that the only evi-dence of possible stability problems is the conrition of the existingold timber cribs.

Visual inspection of the concrete abutments and the cribsdid not reveal any evidence of instability.

b. Design and Construction Data

No design computations are available, but drawings dated1962 and 1977 were obtained from the project records.

c. Operating Records

The operating records of this dam can be found at the officeof the owner, Union Water Power Co.

d. Post-Construction Changes

Available records indicate that improvements to this da-have been made on a regular basis. All changes were to upgrade thestructural elements of the dam with no design changes.

Replacement of the timber cribZ with precast concrete wasstarted in 1944, and is still in progress.

e. Seismic Stability

The dam is located in Seismic Zone 2 and, in accordance withrecommended Phase I guidelines, does not warrant seismic analysis.

1

| 15

1

SECTION 7 - ASSESSMWT, RECOMMENDATIONS, & REMEIAL MEASURZES

7.1 Dam Assessment

a. Condition

The visual inspection indicates that the Errol Dair is in

good condition. Based on hydraulic/hydrologic evaluation, this dam, isjudged to be in fair condition. Therefore, the overall condition ofthe dam is fair.

b. Adequacy of Information

An adequate assessment of the dam consistent with the scopeof a Phase I investigation has been made based upon the visual inspec-

tion and available information.

c. Urgency

The recommendations and remedial measures enumerated in Sec-tions 7.2 and 7.3 should be implemented within 2 years of receipt ofthis Phase I report by the owner.

d. Need for Additional Investigation

The information available from the visual inspection is ade-quate to identify the potential problem of overtopping. This problemrequires the attention of a competent engineer who will have to makeadditional engineering studies to design or specify remedial measuresto rectify this problem. If left unattended, this problem could leadto instability of the structure.

7.2 Recommendations

It is recommended that a more detailed hydraulic study be made

to better establish the discharge and tailwater characteristics of theproject and the extent of damage that might occur at the dam and indownstream areas in the event of a major flood.

7.3 Remedial Measures

Although the dam is generally maintained in good condition, itis considered important that the following operating and maintenanceprocedures be attended to as early as practical:

II 16

a. The old timber cribs were observed to be in fair condition.Nevertheless, the owner should continue his ongoing program of replac-ing all the wooden crib piers by precast concrete crib piers.

b. Vegetation should be removed frori the dike embankment exceptffor grass that prevents slope erosion.

c. Maintenance program of the owner should be continued.

Id. A program of technical, annual periodic inspection of theproject features should be prepared and initiated.

e. As the dam is upstream of a populated area, round-the-clocksurveillance should be provided during periods of high precipitation.

f. The owner should develop a formal warning system. An opera-tional procedure to follow in the event of an emergency should beadopted.

7.4 Alternatives

None recommended.

1

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ICI

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[

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APPEND IX A

VISUAL INSPECTION CHECK LISTPARTY ORGANIZATION

PROJECT Errol Dam DATE June 29, 1978

TI1E 830 - 1230

WEATHER Sunny

W.S. ELEV. 1245.4 U.S. DN.S.

PARTY:Team Captain - Structural

1. Jurgis Gimbutas, P.E. and Concrete

2. Harvey H. Stoller, P.E. Soils, Geology, & Foundations

3. V. Rao Maddineni, P.E. Hydraulics & Hydrology

PROJECT FEATURE INSPECTED BY REMARKS

1. Dam H. H. Stoller Good

2. Dike Embankment B. H. Stoller Fa.r

3. Gate House J. Gimbutas GoodApproach and Discharge H. H. Stoller

4. Channels V. R. Maddineni Good

5. Footbridge J. Gimbutas GoodReservoir and Downstream

6. Channel V. R. Maddineni Good

IV

A-1

It

PERIODIC INSPECTION CHECK LIST

PROJECT Errol Dar DATE June 29, 1978

PROJECT FEATURE .aDISCIPLINE Soils & Foundatiosns NAME_-_-_-_____-________-_

PROJECT FEATURE

DISCIPLINE NAME

DISCIPLINE NAME

AREA EVALUATED CONDITION

DAMr

Crest Elevation 1252.0

Current Pool Elevation 1245.4

Maximum Impoundment toDate 1250.75 (in the year 1917)

Surface Cracks None

Pavement Condition None

Movement or Settlement of

Crest None observed

Lateral Movement None observed

Vertical Alignment No visual vertical

misalignment

Horizontal Alignment No visual horizontalmisalignment

Condition at Abutment andat Concrete Structures Normal

AI A-2

PERIODIC INSPECTION ChECK LIST


PROJECT FEATURE Da

DISCIPLINE Sozis & Fondations NAME____________

PROJECT FEATURE

DISCIPLINE NAME

DISCIPLINE NAME


Indications of Movement ofStructural Items on Slopes None observed

Trespassing on Slopes None observed

Sloughing or Erosion ofSlopes or Abutments None observed

Rock Slope Protection -

Riprap Failures None

Unusual Movement orCracking at or Near Toes None observed

Unusual Embankment orDownstream Seepage None observed

Piping or Boils None observed

Foundation Drainage

Features None

Timber Cribs Fair Condition - SeeSection 3

Precast Concrete Cribs Good Condition

A-3

,!


PROZECT Errol Dam DATE June 29, 1978

PROJECT FEATURE Dike Eran~ ce.t

DISCIPLINE Soils & Foundations NAME -.- _-- -.---. , -•

PROJECT FEATURE

DISCIPLINE NAME

DISCIPLINE NAME


DIKE DMBANFKMrk

Crest Elevation 1252.0

Current Pool Elevation 1245.4

Maximum Impoundment toDate 1250.75 (in the year 19!7)

Surface Cracks None observed

Pavement Condition None

Movement or Settlement ofCrest None observed

Lateral Movement None observed

Vertical Alignment No visual vertical.misalignment

Horizontal Alignment No visual horizontal'K misalignment

Condition at Abutment andat Concrete Structures Normal

A~A-4

!t



PROJECT FEATURE Dike EnbarJment

DISCIPLINE Soils 1 FoxidationS NAME 4C -* K'- -

L PROJECT FEATURE

DISCIPLINE NAME

DISCIPLINE NAME


Indications of Movement ofStructural Items on Slopes None observed

Trespassing on Slopes None observed

Sloughing or Erosion ofSlopes or Abutments None observed

Rock Slope Protection -Riprap Failures None

Unusual Movement orCracking at or Near Toes None observed

Unusual Embankment orDownstream Seepage None observed

Piping or Boils None observed

Foundation Drainage

Features None

Toe Drains None

Instrumentation System None

g A-5



[ PROJECT FEATURE Gate House

DISCIPLINE Structures NAME -

PROJECT FEATURE

DISCIPLINE NAME

DISCIPLINE NAME


OUTLET WORKS - GATE HOUSE

a. Structural

General Condition Good (wood structure

covered with corrugatedmetal)

Unusual Seepage orLeaks in Gate Chamber Leakage, minor in nature

b. Mechanical and Electrical

Air Vents None

Float Wells None

Crane Hoist Appears to be in good

condition

Elevator None

Hydraulic System NoneIService Gates Twelve gates - one gate

non-operable

Emergency Gates None

A-6

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PERIODIC INSPECTION CHDCK LIST

P RJE CT Errol Da. DATE June 29 19"8

PROJECT FEAnURE Gate Hou.se

DISCIPLINE Strct -re NAME ______.____

rPROJECT FTA7JRE

DISCIPLINE NAME

DISCIPLINE NAME

AREA EVALUATD CONDITION

ILightning ProtectionSystem None

Emergency Power Gasoline motor with man.a"System backup

Wiring and Lighting

System Operating condit on

A-7

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PROJECT FEATURE

r DISCIPLINE_____________ NAMEAr~roach and

PROJECT FEATURE:-scharce Channels

DISCIPLINE Soils & Foundations NAME._________________

DISCIPLINE Hvdraulics & Hvdrolocv NAME / ' / j' /. "<


OUTLET WORKS - APPROACH ANDDISCHARGE CHANNELS

a. Approach Channel

General Condition Good

Loose RockOverhanging Channel None observed

Trees OverhangingChannel None observed

Floor of Approach Water at Elevation 1254.4,Channel floor of channel could not

be observed

b. Discharge Channel

General Condition Good

Loose Rockj Overhanging Channel None observed

A-B

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PROJECT Errol Dam DATE June 29. 1978

PROJECT FEATURE

DISCIPLINE NAME

PROJECT FEATURE Discharge Channel

DISCIPLINE Soils & Foundations NAME '-----. -- \

DISCIPLINE Hydraulics & Hydrolon:, NAME_____________


Trees OverhangingChannel None observed

Floor of Channel Could not be observed

Other Obstructions None observed

A-

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[PROJECT FEATUJRE Footbridge

DISCIPLINE Str'1ztures NAME - ' .; ,

PROJECT FEATURE

DISCIPLINE NAME

DISCIPLINE NAME


OUTLET WORKS - FOOTBRIDGE

a. Superstructure

Bearings None

Anchor Bolts Good condition

Bridge Seat None

Longitudinal Members Steel L's, rusting inplaces

Underside of Deck Good condition

I Secondary Bracing None

Deck Good condition (steelgrating)

Railings Good condition

Expansion Joints None

A-10

I.

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APPENDIX B

EXISTING AVAILABLE INFORMATION

*

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APPENZIX B

1. Listing of Records and Their Location

The New Hampshire Water Resources Board, 37 Pleasant Street, Con-cord, New Hampshire, has three folders of records and correspondencedated 1924 to 1977, and filed under Town/Darr No. 80.Cl, ErrolI Town/Errol Damn.

The documents of importance to the design and maintenance are the

following:

1) 1924 to 1925. Inventory card on Errol Town Dam No. 1, ownedby the Union Water Power Co.

2) July 15, 1928. Photograph showing downstream view of da-Twith six wooden cribs or piers.

3) May, 1950 to June, 1951. Correspondence between the UnionWater Power Co. and the Water Control Commission in Concord,regarding temporary repairs of the dam, including smallsketches.

4) Two charts showing average daily flows of Androscoggin Riverat Berlin, New Hampshire, in 1952.

5) Thirteen charts showing average daily flows of AndroscogginRiver near Gorham, New Hampshire, from 1942 to 1953.

(6) April, 1953. Hydraulic charts regarding the new Errol proj-ect, by Chas. T. Main, Inc., Boston, Massachusetts.

(7) May 1, 1957. Brief description of Errol Darr by Mr. Paul W.Bean of Union Water Power Co.

(8) November, 1959 and November, 1961. Outlines and petitionfor maintenance repairs of the dam, from Mr. Paul W. Bean,Agent, Union Water Power Co. to the New Hampshire Water Re-Sources Board. Petition was granted on December 18, 1961.

(9) May 6, 1966. Letter from Mr. Paul W. Beam to Mr. Moore of

Concord, regarding dimensions of dam.

(10) June 12, 1969. Report from Mr. G. M. McGee, Sr., Chairman,New Hampshire Water Resources Board, to Representative G. J.Fortier of Berlin, New Hampshire, regarding proper mainte-nance and safety of Errol Dam.

B-I

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(11) May, 1969. Tabulation of precipitation at Errol Dam in thespring of 1969.

(12) May, 1970 to April, 1911. Correspondence between severalinterested parties regarding yearly flooding along Route 16near Errol Dam. These letters contain valuable hydrologicaldata.

(13) Charts showing flows at Errol, New Hampshire, and levels ofLake Umbagog from 1964 to 1973.

(14) March 20, 1974. Three photographs taken from the Army Corpsof Engineers' Dam Inventory Program.

(15) January 17, 1975. FIA Flood Hazard Boundary Maps, town ofErrol (ten pages).

(16) March 31, 1976. Statistical data on sizes of the reservoirsin the town of Errol, with a small map showing AndroscogginRiver drainage area.

(17) November 14, 1977. Application for repair to Errol Dam, bythe Union Water Power Co. to the New Hamsphire Water Re-sources Board.

Mr. William M. Grove, Agent for the Union Water Power Co., 150Main Street, Lewiston, Maine, made available to us the following data:

1) Test borings drilled in September, 1944, by Mr. M. J.

O'Kelly, driller, and plan of location of borings made onMay 15, 1947 (fifteen pages).

2) Headwater storage on the Androscoggin River, November, 1948,

by Mr. F. W. Harris.

3) Hydrologic study, January, 1959, by Chas. T. Main, Inc.

4) Revised in 1975. Operation of Androscoggin River storageSystem, pamphlet by the Union Water Power Co. (fifteenpages).

5) RepOrt of 1977. Inspection by Chas. T. Main, Inc.

2. Copies of Past Inspection Reports

The following copies of past inspection reports are included inthis report:

B-2

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(1) August 6, 1936. By the New Hampshire Water Resources Board.

(2) November 29, 1938. By the New Hampshire Water Control Com-mission, initialed by AAN & RLT (two pages).

(3) October 26, 1972. By the New Hampshire Water ResourcesBoard, Mr. Robert B. Chamberlin.

(4) October 4, 1977. By Mr. J. Goodrich of Chas. T. Main, Inc.,and Mr. W. Grove of Union Water Power Co. (two pages)

3. Drawings

The New Hampshire Water Resources Board is in possession of prints

listed below and showing the layout of the dam, sections, and somedetails:

*(l) July, and November, 1930. Boring location plan, test pits,drill hole layouts, Errol Dam, by the New England PublicService Co., Engineering Department.

(2) January, 1948. Plan showing proposed flowage of Errol Dam,size 16 inches by 33 inches, colored map showing UmbagogLake and surroundings.

(3) May, 1948. Preliminary study, location plan, and accessroads to proposed Errol Dam, by the Union Water Power Co.,Lewiston, Maine.

(4) December, 1948. Errol 1275 Dam, ledge topography, "Plan B,"by Union Water Power Co.

(5) April, 1958. Exhibit Sheets J, K, L-l, and L-2, Errol Proj-ect: general map, detailed map, plan and sections, and pro-file and sections, by Chas. T. Main, Inc., for the New Hamp-shire Water Resources Board (never constructed).

(6) January, 1975. 1275 Dam, Sheet E-79, Topographic Layout;Sheet E-78, Main Dam Section, by the Union Water Power Co.

Mr. W. M. Grove of the Union Water Power Co. made available to usthe following drawings from the files in his office in Lewiston, Maine.

*(I) July, 1944, Revised June, 1978. Drawing No. ES-24,Sketch-Diagram, Errol Dam, by Mr. Paul W. Bean, Union Water

Power Co.

*Reduced copies are included with this report.

B-3

-- - i iim Imnun m m/mn

(2) March, 1963 (Revised). Reconstruction of the deep gates,plan and section, Drawing Nos. E-92 and E-93, by Union WaterPower Co.

(3) December, 1977 (Revision). Rebuilt sluice pier, Drawing No.E-103, by Union Water Power Co.

L(4) July, 1978 (Revision). Sketched diagram - Errol Dan (origi-

nal date July 1, 1944).

*Reduced copies are included with this report.

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II B- 4

SAM

__ _ __ _ __ _ _ 12. - -- ,-

LO'AL 1- 1 C. D___ ________ ________if~~~~~~~ ~~~~ Z :______D3::P1J~4. -r

H E B A~ i o' 12 c- .FT T T3~ C r

PER',,A: EL2U 5G.. 2 TOCA L A G______

SILL'A: 77-- E -E 3,TI ._______

WA=~ 1c:~: Ti:A.___ ___

PCEB Hl A~E ED C.F.S.

'J 7 I7 S o. H P F EE T F'LG

REIIARK3 S.4 ~ ',/ ~ a.'~

DATE5

/ ¥ N-lArirzt'rl r. YA I LA LJI I A tJL LJAVILVI I1

DATA ON DAMS IN NEW HAMPSHIRE

LOCATION / STATE NO. 8g.1.............Town ........... ErX 01 ............................................... : County .......... ..o.o.Os ./........................

. ,//To ... ... ... ... .... .'.. ... ........................ ..................................Stream . . o g in.li ,R ......... . ....... ........Basin-Primary . A osc g .ie. : Secondary .............................................................

Local Name .............................................................................

Coordinates- Lat .... 44.... 5 .. 13 ............ Long ........ 7/....5 ..............................

GENERAL DATA

Drainage area: Controlled ................ Sq. MT;.: Uncontrolled ........ Sq. Mi.: Total ...10_mS.. s,-

O verall length of dam ................ ft.: D ate of Construction .....................................................................

Height: Stream bed to highest elev. ....,201... . ft.: Max. Structure ........ 1E,?.............................

C ost- D am ................................................................ : R eservoir .............................................................

DESCRIPTION Crib- Timber on Ledge- Earth

Waste Gates

T y p e ................................................. ...... . ............................ .......................................................

N um ber ............................ : Size ........................ ft. high x .................................................... ft. w .

E levation Invert .................................................... : T otal A rea ............................................

H oist ............................................................................................................................................................

Waste Gates Conduit

N um ber .............................................. : M aterials ........................................................ ................

Size .......................... ft.: L ength .......................... ft.: A rea ............................................................ s q.

Embankment

Type ..........................................................................

H eight- Y ax .................................................. ft.: Min ................................................ f

T op- -W idth .................................................... .. : E lev. ......................................................................

Slopes-Upstream .......... on .................... : Downstream ..............on..................

Length-Right of Spillway ................: Left of Spillway ..................................................

Spillway

Materials of Construction ................. (.Gates) ... ..............(=..Zpi11Wa.y)j..........Length-Total ...................................................... ft.: Net ......................... .......

H eight of perm anent section- m ax ..................... ft.: M in ............................................................. f.

Flashboards-- Type .................................................................................. :H eight ......................... f

Elevation-Permanent Crest ...12 3 I ............................ Top of Flashboard ..................................

Flood Capacity .......................................... cfs.: .................................................... cfs/sq. m i.

U Abutments

M aterials: ....................................................................................................................................................

Freeboard: M ax ................................................. ft.: M- Min .......................................... f

Headworks to Power Devel.-(See "Data on Power Development")

O W NER ........ . .. .... .. ........ .. ........... . .........................

REMARKS Use Log Driving- Conservation

B-6

NEW HAMPSHIRE WATER CONTROL COMISSIONDATA ON RESERVOIRS & PONDS IN NEW HAMPSHIRE

LOCATION AT DAM. NO. B01'.02

Town..... rQ............................................ County ....... C..0.sB................................

Stream...And.1Qzo:-.gina. .~ver ........................................................................

Basin-Primrary ........ An~zk.a~g,7............ Secondary ............................................

Local Name .......................................................................................................

It DRAINAGE AREA

Controlied............ Sq. Yi.: Uncontrolled............ Sq. M.Ni.: Tota, *,jO25.,q.j . .......... S4

ELEVATION v.WATER SURFACE AREA vs. VOLUME

SurfacePoint Read Area cur

Feet Acres Acre i:.

(1) M ax. Flood H eight .............. ..........................

(2) Top off Flashboards ..........................................

(3) Perm anent Crest .............. ...........................(4) Normal Drawdown ....

(5) M ax. Drawdown .............. ................... ......

(6) Original Pond E ................ ..............

Base Used ............ Coef. to change to U.S.G.S. Base............................................

RESERVOIR CAPACITY

Total Volumne Useable Volumre

Drawd own ................ft........................... ft.

Volume ...............ac. ft... .. ..................... ac. ft.

* Acre ft. per sq. mi..............................

Inches per sq. mi..............................

USE OF WATER .. ...... (Consezvatian. .... lzv.DivinO ...............................................

OWNER ....... Uin..L4t . oe.C0..... ...................... Lewis.t-on..Ue ..................

fREMARKS Wheel (Not used)

B- 7

Tabulation ....A. ....&.R...... ......... Date .... Noeme

Concord, U. H. 03301

DAM SAFETY I!NPEC7TI:: PEF-T F0 -

Tow-n: Frr ] Dam N ber: P$. ,_

r Inspected by: pcb-rt ' Cb- rrlin Date: 2(

Local name of da or water body: Errcl 1 Tm-. og'- .1T

Owner: Address:

Owner was/was not interviewed during inspection.r

Drainage Area: 1005 sq. mi. Stream: A ..

Pond Area: 89 V Acre, Storage /;'c , Ac-Ft. Max. Head I< r

Foundation: Type Lede , Seepage present at toe - Yes/':o,_

Spillway: Type Gates onlv , Freeboard over rerrn. crest:

Width 121' width of Pat~s,Flashboard height

Fzx. Capacity c.f.s.

Embankent: Type , Cover Width

Upstream slope_ to 1; Dawnstream slope to 1

Abutments: Type Crib , Condition: Good, Fair, Poor

Gates or Pond Drain: Size Capacity__ Type

Lifting apparatus Operational condition

Changes since construction or last inspection: Metal on richt gate secticn.

recently primed. Crib piers are in alignment. Gate house secure. Has a very

goOd overall aopearance.

Downstream development:

'This dam would/would not be a menace if it failed.

Suggested reinspection date:

]Remarks :I

$1;

UTNIO!; WATER POWB'R CCOMAN'-

ANDROSCOUGCI:; R-ESERVIOR CCM>' Y

LEVISTON;, AE

[ j *REPORT OF 1977 llSFFCTIo),;

Of* 1 ~ ~ UNION WA T'E? C*TrR O 2 X

ANDROSCOGGINh RESE7rVI'Cp, CCO>2,,,yINSTALLATION"S

2

jkNOVD'MER, 1977

Inspection and Report- by

CHAS. T. MAIN, INC.

Boston, Massachusetts

B-

On Octcc- 4, 1977, th e structures wc~e irsectec . 2.&c:.

an-- W. rcve ao aedby M!r, Carl La**,.----*.at~

(b >:ecwas 1-.9K. Ful -- 1. d w a er- lean-d n czlevvel of_ record is .75 (ccurrec i 1

All gates were discharg2lnc a total of 25Cc.f.s. a- t L t

F'3t : dn; c fon. 2h tcta a r i Oa~i < cf a a

L lf,~~cC .f.s. D -nte flooding will ocvr a:-o

Dik e c a tr -uoti n u pstrea m of th e Errol' D ian f c:-zS a co- '7 cir the rlr-,- cr~ati:;c a rise in water lev0l tO oCCZ _7US~_4

of the dan. rforise in water leve: ~c ca:- an-2c - to 3treprescn7-c increa5ec s tcraL-2 caabnIlf tv and :5 useJi an

river releaSes an.d pond_ levels at Errol Dan.- A s C stro -cstation is located. just below the river ctaun

As reported :in 1971 th.e entire daTn struct-urE eac in- s _7.

conditi=r. A hard. placed 2' plank cutoff wall rei-_fcroos vei

poly~etinelene placed upstream was constructed in 197_ V_4t ne s:'u

placed to elevation of the existing concrete ca7 .

The wood wal';,.a' was replaced- with steel gaig

concrete head_-er blcZKs were wate~r~~ 70 ,rv

oil.

Rodey urt h~ss wreinstalled on all deep gate5 exe~

the qs!7l northerly; gate. An. dleotroc notori' ;c

eac-h tv.: dcc;r gates vwtt' prov~lf aet onc

Motor to one or rye gates at atn. Th~e fiv.e larlue sli e

are recohanicailv cperated b% a Wvable gasoline droe p%:

belt as reported inoh 1971 inspection. An diir&ZVil

gaslie otr rive is provided fozaku. lather cf theCtvo can noca gaoiedtrdie for the large sluice gates

can be used to also drive the deep gates.

Portions1 of the dike construction discussed above are heavily;

wooded but under nort-2l conditiorns are above water' level and dry.

As reported in 1971 , the Errol Dam and dik.e are in sound az2

Satisfactory condlifon Ideally, the dike should be cleared of

brush an'. tree prc-_,th but this cord' tion. has bee2 continu1ing co% r

the history of the project and has been dicussed in, the Past reports.

pecorr'v-pnlt ion

As a consequence of the wooded growth which has dcvelcOd over

the years, conti-nuation of the observation progran sqhown inAnn x

C, should be carried Out a' th)e dike area to ascertanasalSeepage condiin Thscndition, hcywever, is not considered' to

constitute a major hazard for this dam. B-10

A'6-1

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Ir

I APPENDIX C

PHOTOGRAPHS

I

ILIIL

Iri

I

* I

APPENDIX C

REPRESENTATIVE PHOTOGRAPHS OF PROJECT

LOCATION PLAN

Plan 1 - Location of Photographs Taken June 29, 1978 C-3

I [ PHOTOGRAPHS

No. Negative No. Page

1. North half of dam on theupstream side. 11-10 C-4

2. Footbridge and wooden cribs on

the upstream side. 11-12 C-4

3. New precast concrete crib on the

upstream side. 11-20 C-5

4. South end of footbridge. 11-13 C-5

5. New precast concrete cribs and oneremaining wooden crib on the

downstream side. 11-35A C-6

I, 6. Wooden sluice gates near northabutment. 1-34A C-6

7. Precast concrete cribs on the

downstream side, with all gatespartially open. 11-6 C-7

8. Crest flashboards near northabutment. 11-22 C-7

9. Inside of gate house; overhead

electric motors lifting gates inpairs. 11-18 C-8

10. Inside of gate house: a standby

gas motor on wheels. 11-16 C-8

C-1

I

No. Necative No. Page

11. Extension of north abutmentdownstream. 11-33A C-9

12. Top of earth dike, looking southeastaway from dam. 11-25 C-9

13. Right bank of Androscoggin River,showing a culvert under Route 16,about 1500 feet upstream of theErrol Dam. 11-30A C-10

14. Androscoggin River approaching theErrol Dam, looking southwest. 11-27 C-10

C

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GATE HOUSE-- 9" FOOT BRIDGE

ERROL DAMjLOCATION OF PHOTOGRAPHSc-3

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TIME IN HOURS

SPILLWAY TEST FLOOD INFLOW HYDROGRAPH

/1i

56 NAT~rNALF~ )3A~ OINLPECT ION OF NON- FEE A

ERROL DAM/HYIDROGRAF-

H, HA-

- --- - it Ali

f 44

2 42 ---

I24 -- ---

CAPACITY IN ACPE FEFT

STORAGE CAPACITY- ELEVATION CU'E;:

1' (L AL [I u~ - 85(

- /-

CURV-

ERROL DAM

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AD-AISS 321 NATIOUW PIneM FOR INMPICTION OF hflh*FSSSWE OM sitam em toe 0welt).u COPSe OF hghiiils WALTHM M

INCI AIfOF/0 13/13 WI.

1.0 1211111 $1 Il2.2

1 0 1.4g 111111.

liii'-~ 18 lll

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VO , n I T V 'HOPAD

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A irmchcee Lake

irst CoiwbC0 e r

Laik

0 10

UNITED STATES SCALE IN MILES NEW AMPSH'E-

DEPARTMENT OF INTERIOR SCALE 1 250000 SECOND CONNEC-,CJT LAE

GEOLOGICAL SURVEY INDIAN STREAM Q Alp

ERROL QuAtRAN,'MILAN QUADRAN,

MOOSE BOG OUARAN

NEW NAMPSMDIXVILLE QUADRA

monorI

.~a DRAINAGE A REA--

• ERROL DAM

-. 4.

-II

4--

nmxheneeLLke

llnL - - PPoow

First ,Cov ! e --u

rmhen Lak pond

0 510S(ALE N MwES NEW HAMPSHIRE-MAINE MAINE

SCALE 1 250000 SECOND CONNECTICJT LAKE CjAZ,,ASE 1927 TIM MTN QUADRANG,E 9'0INDIAN STREAM QUACRY.,- ;?5 JIM POND QUADRANGLE i9S9

ERROL QUADRANGLE 93: QUILL HILL OUA0RAN5E f96 9MILAN QUADRANGLE -3! OOUOSSOC (UADrN4.G,.E 194,3

MOOSE BOG QuADRANGLE t9:' CUPSuPTIC QUAOR, tcE 193,RANGELEY OUACRANGE 1%35-49

NEW HAMPSHIRE BLACK MTN OUADR%hLE 1969

DIXVILLE QUADRANGE lc 3 ARNOLD POND QUADRANGLE 19!

CHAIN OF PONDS OJADRAN-TLE 1969OLD SPECK M"rN QUADRANC.E 1943

KENNEBAGO LAKE QUADRANGLE )9%;

I. I* WDRAINAGE AREA -1

I { ERROL DAM

:7;z7;

AM

-22

I7 M,,-. -AREA

rC L 1 62500(ACTUALUN'TEIw /TTE NE HNIPj R A

DE -i~~ T OF IN ERO E RO.Q A R N L 9*itG'A SUVE

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