ii/!iiieeeeee i eeeeeeeeeeeee/iof the downstream slope of the dam should he investigated. in...

AD-A144 280 NATIONAL PROGRAM FOR INSPECTION OF NON-FEDERAL DAMS 1/1PLAINVILLE RESERVOIR..(U) CORPS OF ENGINEERS WALTHAM MANEW ENGLAND DIV JAN 80

UNCLASSIFIED F/G 13/13 NL

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LlM 12,8 12__________5__

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MICROCOPY RESOLUTION TEST CHARTNATrONAL BUJREAU OF STANDARDS- 1963-A

o QUINNIPIAC RIVER BASIN00 SOUTHINGTON ,CONNECTICUT

I4PLAIN VILLE RESERVOIR DAM

CT 00259.

PHASE I INSPECTION REPORT

NATIONAL DAM INSPECTION PROGRAM

ITI

ELECT F' r-AUG 13 1984

JANUARY 1980

DSIBU1tJONSTATEmENT A E)Approved tot public telease

Distributioll thu v&&....

_____4_______S 09 033

"INO* ASSITI'lDSECURITY CLASSIFICATION OF TH4IS PAGE (When Does kneeued)

REPORT DOCUMENTATION PAGE READ INSTRUCTIONSSBEFORE COMPLETING FORM

1REPORT NUMBER 2.6V O~ CIPIENT*S CATALOG NUMBER

CT 00259 __________________

14. TITLIE (mnd Subfli) S. TYPE OF REPORT 6 PERIOD COVERED

Plainville Reservoir Dam INSPECTION REPORT

NATIONAL PROGRAM FOR INSPECTION OF NON-FEDERAL 6. PERFORMING ORG. REPORT NUMBERDlAM--,_ __ _ _ _ __ _ _ __ _ _ _

7. AUTNOR(aI C. CONTRACT OR GRANT NUMUER(a)

U.S. ARMY CORPS OF ENGINEERSNEW ENGLAND DIVISION

9 . PERFORMING ORGANIZATION NAMIE AND ADDRESS 16. PROGRAM ELEMENT. PROJECT. TASK

AREA A WORK UNIT NUMBERS

ItI. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATEDEPT. OF THE ARMY, CORPS OF ENGINEERS January 1980

*NEW ENGLAND DIVISION, NEDED 13. "UNDER OF PAGES424 TRAPELO ROAD, WALTHAM, MA. 02254 65_____________

14. MONITORING AGENCY NAMES6 AODRESS(of different Euem COOhIuAm ONE.0) is. SECURITY CLASS. (fOhl du rP..

UNCLASSIFIEDIs&. D2ECL ASSI FlCATION/ DOWNGRADING

SCMEDLE

1S. DISTRIBUTION STATEMENT (o is de Apwt)

APPROVAL FOR PUBLIC RELEASE: DISTRIBUTION UNLIMITED

17. DIST RINUTION STATEMENT (of ** u absa..afloe In Dis Ofb~ d bfoefi ft XP0

IS. SUPPLEMENTARY NOTES

Cover program reads: Phase I Inspection Report, National Dam Inspection Program;however, the official title of the program is: National Program for Inspection of

* Non-Federal Dams; use cover date for date of report.

IS. KEY WORDS (Cm'Imu. o ........ *ide, El .em..ea doddemeti by ~ bloc

DAMS, INSPECTION, DAM SAFETY,Quinnipiac River BasinSouthington, Connecticut

20. ABSTRACT (Coitme a oewe,.. aide if Poooseml aod ME*OP 1W 600" MninA)

Plainville Reservoir Dam is an earthen embankment cdam with a maximum height of17 ft. and a length of 688 ft. In general, the dam was judged to be in faircondition. The spillway is not adequate to pass the 0.5 Pi4F test flood outflowwithout overtopping the dam. The test flood would overtop the darn by about 0.2ft.

DD 1473 aona OP I NOV gois OSSOLEITe

4. H 4 w

DEPARTMENT OF THE ARMYNEW ENGLAND DIVISION. CORPS CF ENGINEERS

4;- Tk:LrE.-C FZ;k,

W.ALT.HAM. MA;SAOHUL.TTS 02154

L L

Lhar Governor Grasso;

Inclosed is a copy of the Piainville Re-servoir Dam Pnase I InspectionReport, which was preparrd under the National Pro~raw for inspection ofKon-iEdvril Dams. Tnis rtporc is presented for your use anu is bdsVUupon a visual inspection, a review of the past performance and a briefhydrological study of the dam. A brief assessment is incluoed at thebeginning of the report. I have approved the report ano support thefindings and recommendations described in Section 7 and ask that youkeep me informed of the actions taken to implement them. This follow-upaction is a vitally important part of this pro6 ram.

A copy of this report has been forwarded to the Department of Environ-mental Protection, the cooperating abency for the State of Connecticut.In addition, a copy of the report has also been furnisheo the owner,Piainville Water Company.

Copies of this report will be made available to the public, uponrequest, by this office under the Freedom of Information Act. In the

case 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 Department otEnvironmental Protection for your cooperation in carrying out this

program.

Sincerely,

As stated Colonel, Corps of EngineersDivision Engineer

'VIC

A

Accession For

DTIC TAB11nM~ounced 0]

I ~JustIficatlo

Distribution/ PLAINVILLE RESERVOIR DAM

Availability Codes CT 00259

1sI Special

QUINNIPIAC RIVER BASIN

SOUTHINGTON, CONNECTICUT

PHASE I INSPECTION REPORT

NATIONAL DAM INSPECTION PROGRAM

DII

Approved for public reloasq

Distribut ion Unlimited

I

INATIONAL DAM INSPECTION PROGRAM

i PHASE I INSPECTION REPORT

I Identification No.: CT 00259Name of Dam: Plainville Reservoir DamTown: SouthingtonCounty and State: Hartford, ConnecticutStream: Tributary - Quinnipiac RiverDate of Inspection: 23 October, 1979, and 15 November, 1979

BRIEF ASSESSMENT

"Plainville Reservoir Dam is an earthen embankment dam with amaximum height of 17 feet and a length of 688 feet. A concretespillway section, 15 feet wide, is located near the left abut-ment. The upstream face has a slope of 1.5:1, and is protectedby riprap. The downstream face has a slope of 1.5:1. Thereare two 6-inch diameter blow offs located adjacent to the twogatehouse structures located downstream of the dam.

For the past several years the reservoir has not been used act-ively for water supply, but has functioned as a standby reser-voir. Plainville Reservoir has a storage volume of 528 acre-feet; the size classification is thus small. A breach of thedam would affect about 15 residential homes along Flanders Roadand Shuttle Meadow Road. With the possibility of some loss oflife and the probability of significant economic losses, thedam is classified as having a high hazard potential.

In general, the dam was judged to be in fair condition. Thevertical and horizontal alignment is good; however, a slightdip in the crest was noted in the vicinity of the downstreamgatehouse. Several windows were observed in the upstream rip-rap, which ends about 2 feet below the crest of the dam. Somesmall seeps were observed near the downstream slope (right sideof the dam). The concrete spillway and training walls were in

-. good condition. Some flow of water was observed passing belowthe spillway and flowing out the spillway channel.

I The spillway is not adequate to pass the 0.5 PMF test flood out-flow without overtopping the dam. The test flood would overtopthe dam by about 0.2 feet. The spillway would pass about 461 percent of the test flood outflow without overtopping the dam.

Within one year of receipt of the Phase I Inspection Report,S Ithe owner should retain the services of a qualified registered

engineer to investigate the possibility of seepage along thetoe of the dam and to determine what type of seepage controlmeasures are required, if any. The possibility of movement

of the downstream slope of the dam should he investigated. Inaddition, underflow occurring at the spillway area should beinvestigated and required repairs initiated. The rip rap onthe upstream face of the dam should be repaired.

The owner should carry out the following operational andmaintenance procedures: 1) provide proper vegetation on theupstream and downstream slopes of the dam; 2) take such actionas is necessary to prevent trespassing on the crest and slopesof the dam; 3) maintain the area within 25 feet downstreamfrom the toe of the dam clear of trees and brush; 4) removetrees and brush from the downstream channel and at a distanceof 20 feet on either side of the channel for a distance of 100feet downstream of the dam; 5) develop a formal surveillanceand flood warning plan, with an operational procedure to befollowed in the event of an emergency; 6) institute proceduresfor an annual technical inspection of the dam and its appurtenantstructures; and 7) outlet works capable of drawing down thereservoir should be maintained operational and in good repair.

Giavara, P.E.;esident

Registered CT 7634

I.4

V j

1L

L:I ..... .....

This Phase I Inspection Report on Plainville Reservoir Dam,has been reviewed by the undersigned Review Board members. In ouropinion, the reported findings, conclusions, and recommendations areconsistent with the Recommended Guidelines for Safety Inspection of

* Daa nd with good engineering judgment and practice, and is herebysubmitted for approval.

ARA AST MAHTESIAN, MDMERGeotechnical Engineering BranchEngineering Division

CARNEY M. TERZIAN, MEMBERDesign BranchEngineering Division

lqI IBONO.IR

RICHARD CHAIRMANWater Control BranchEngineering Division

APPROVAL IZCCO EDs~

oD.

LI; "Chief Ikttm~ri8 Dlio o

A. o '

-

PREFACE

This report is prepared under guidance contained in the-Recommended Guidelines for Safety Inspection of Dams, for Phase IInvestigations. Copies of these guidelines may be obtained fromthe Office of Chief of Engineers, Washington, D.C. 20314. Thepurpose of a Phase I Investigation is to identify expeditiouslythose dams which may pose hazards to human life or property. Theassessment of the general condition of the dam is based upon avail-able data and visual inspections. Detailed investigation, andanalyses involving topographic mapping, subsurface investigations,-testing, and detailed computational evaluations are beyond thescope of a Phase I investigation: however, the investigation isintended to identify any need for such studies.

In reviewing this report, it should be realized that the re-ported condition of the dam is based on observations of field con-ditions at the time of inspection along with data available to theinspection team. In cases where the reservoir was lowered ordrained prior to inspection, such action, while improving thestability and safety of the dam, removes the normal load on thestructure and may obscure certain conditions which might other-wise be detectable if inspected under the normal operating environ-ment of the structure.

It is important to note that the condition of a dam dependson numerous and constantly changing internal and external condi-tions, and is evolutionary in nature. It would be incorrect toassume that the present condition of the dam will continue torepresent the condition of the dam at some point in the future.Only through continued care and inspection can there be any chancethat unsafe conditions be detected.

Phase I inspections are not intended to provide detailed hydro-logic and hydraulic analyses. In accordance with the establishedGuidelines, the Spillway Test flood is based on the estimated"Probable Maximum Flood" for the region (greatest reasonably pos-sible storm runoff), or fractions thereof. Because of the magni-tude and rarity of such a storm event, a finding that a spillwaywill not pass the test flood should not be interpreted as neces-sarily posing a highly inadequate condition. The test flood pro-vides a measure of relative spillway capacity and serves as an aidein determining the need for more detailed hydrologic and hydraulicstudies, considering the size of the dam, its general conditionand the downstream damage potential.

The Phase I Investigation does not include an assessment ofthe need for fences, gates, no-trespa-ing signs, repairs to exist-ing fences and railings and other items which may be needed tominimize trespass and provide greater security for the facilityand safety to the public. An evaluation of the project for com-pliance with OSHA rules and regulations is also excluded.

4

I

TABLE OF CONTENTS

Section Page

Letter of Transmittal

Brief Assessment

Review Board Page

Preface i

Table of Contents ii - iv

Overview Photo v

Location Map vi

REPORT

1. PROJECT INFORMATION 1

1.1 General 1

a. Authority 1b. Purpose of Inspection 1

1.2 Description of Project 1

a. Location 1b. Description of Dam and Appurtenances 1c. Size Classification 2d. Hazard Classification 2e. Ownership 2f. Operator 2g. Purpose of Dam 2h. Design and Construction History 2i. Normal Operational Procedure 3

1.3 Pertinent Data 3

2. ENGINEERING DATA 7

L 2.1 Design Data 7

2.2 Construction Data 7

2.3 Operation Data 7

2.4 Evaluation of Data 7

[MmC *

111

Section Page

3. VISUAL INSPECTION 8

3.1 Findings 8

a. General 8b. Dam 8c. Appurtenant Structures 9d. Reservoir Area 10e. Downstream Channel 10

3.2 Evaluation 10

4. OPERATIONAL AND MAINTENANCE PROCEDURES 11

4.1 Operational Procedures 11

a. General 11b. Description of any Warning System in R-fect 11

4.2 Maintenance Procedures 11

a. General 11b. Operating Facilities 11

4.3 Evaluation 11

5. EVALUATION OF HYDRAULIC/HYDROLOGIC FEATURES 12

5.1 General 12

5.2 Design Data 12

5.3 Experience Data 12

5.4 Test Flood Analysis 12

5.5 Dam Failure Analysis 13

6. EVALUATION OF STRUCTURAL STABILITY 14

6.1 Visual Observation 14

[ 6.2 Design and Construction Data 14

6.3 Post-Construction Changes 14

* 6.4 Seismic Stability 14r: ,.4-

Section Page

7. ASSESSMENT, RECOMMENDATIONS AND REMEDIAL MEASURES 15

7.1 Dam Assessment 15

a. Condition 15b. Adequacy of Information 15c. Urgency 15

7.2 Recommendations 15

7.3 Remedial Measures 16

a. Operation and Maintenance Procedures 16

7.4 Alternatives 16

APPENDIXES

Appendix Description

A INSPECTION CHECKLIST

B ENGINEERING DATA

C PHOTOGRAPHS

D HYDROLOGIC AND HYDRAULIC COMPUTATIONS

E' INFORMATION AS CONTAINED IN, THE NATIONALINVENTORY OF DAMS

iv

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NATIONAL DAM INSPECTION PROGRAMPHASE I INSPECTION REPORT

PLAINVILLE RESERVOIR DAM - CT 00030

SECTION I - PROJECT INFORMATION

1.1 GENERAL:

a. Authority. Public Law 92-367, August 8, 1972, authorizedthe Secretary oT the Army, through the Corps of Engineers, to ini-tiate a national program of dam inspection through the United States.The New England Division of the Corps of Engineers has been assignedthe responsibility of supervising the inspection of dams within theNew England Region. Flaherty Giavara Associates, P.C. has been re-tained by the New:England Division to inspect and report on selecteddams in the State of Connecticut. Authorization and notice to proceedwas issued to Flaherty Giavara Associates, P.C. under a letter of 19October 1979 from William E. Hodgson, Jr., Colonel, Corps of Engineers.Contract No. DACW33-80-C-0001 has been assigned by the Corps of Engi-neers for this work.

b. Purpose.

1) Perform technical inspection and evaluation of non-federal dams to identify conditions which threaten the public safetyand thus permit correction in a timely manner by non-federal interests.

2) Encourage and assist the States to initiate quickly ef-fective dam safety programs for non-federal dams.

3) To update, verify arid complete the National Inventory ofDams.

1.2 DESCRIPTION OF THE PROJECT:

a. Location. Plainville Reservoir Dam is located in Southington,Connecticut on a tributary stream to the Quinnipiac River. The reser-voir is located approximately 2 miles southeast of the center of Plain-ville. The reservoir is shown on U.S.G.S. Topographic Map "New Britain,Connecticut" at a latitude of 410 38' 21" and a longitude of 720 50' 36".The Location Map on page vi shows the location of the structure.

b. Description of Dam and Appurtenances. Plainville ReservoirDam is an earthen embankment dam with a maximum height of 17 feet anda length of 688 feet. A concrete spillway section is located near theleft (west) abutment of the dam. The dam embankment elevation is 427±feet. The upstream face of the earth embankment slopes at 1.5 horizon-tal to 1 vertical and protected with riprap underlain by select

* I -1-

material. The downstream face also slopes at 1.5 horizontal to1 vertical. The construction plans indicate that this dam containsa center core "puddle wall."

The spillway consists of a concrete slab broad crested weir 15 feetwide. Concrete training walls are located on both sides of thespillway. The available construction plans indicate that the con-crete spillway slab is underlain by a central "puddle wall" withearth material to either side. The downstream face of the spillwayis a stone masonry wall.

The outlet works consist of a free standing stone and mortar intaketower in the reservoir. This intake tower feeds two gatehouses atthe downstream toe of the dam which supply 8-inch and 12-inchdiameter water supply mains (standby). There are two 6-inch diameterblow-offs located on each of these mains.

c. Size Classification. Plainville Reservoir has a storagevolume of 528 acre-feet and a dam height of 17± feet. Storage ofless than 1,000 acre-feet and a height of less than 40 feet classifiesthis structure in the "small" category according to guidelines estab-lished by the Corps of Engineers.

d. Hazard Classification. The dam is classified as having a"high" hazard potential. The areas of probable impact include singlefamily residential properties along Flanders Road and Shuttle MeadowRoad in the Town of Southington, Connecticut. The number of dwellingsin the probable impact area is approximately 15. Interstate Highway84 is located 4,000± feet downstream of the dam. It is anticipatedthat the highway embankment would provide an obstruction to the down-stream movement of water.

e. Ownership. The Plainville Reservoir Dam was originally builtfor and is owned by the Plainville Water Company, 17 Pierce Street,Plainville, Connecticut. The current Superintendent of the companyis Mr. Lou Bordeau, telephone: 203-747-2734.

f. Operator. The Plainville Water Company Superintendent, Mr.Lou Bordeau, operates this dam.

g. Purpose of Dam. The original purpose of the dam was to impoundthe reservoir for use as a public water supply. For the past severalyears the reservoir has not been utilized actively for water supplypurposes. It functions as a standby reservoir.

h. Design and Construction History. The dam was constructed in1884 and designed by the Connecticut Patent Water Pipe Company. Theoriginal design plans for this dam are included in Appendix B.

2

%_

i. Normal Operation Procedures. The reservoir for the pastseveral years has not been utilized actively for public water supply.As a result, the 8-inch and 12-inch water mains through the dam fromthe intake tower have not been utilized other than for routine main-tenance purposes. In anticipation of heavy rains, the water mains areopened and water is discharged downstream below the dam via blow-offpipes. This procedure is practiced to minimize the reservoir's maxi-mum water surface level during a storm event.

1.3 PERTINENT DATA:

a. Drainage Area. The drainage area consists of 0.37 squaremiles of rural land located on the western side of a prominent rockyridge. The watershed is totally wooded with steep to moderate slopes.The length of the watershed is 3,000± feet with a width of 5,000± feet.

b. Discharge at Dam Site.

1) Two water mains (8-inch and 12-inch) pass through thedam to individual gatehouses. A 6-inch diameter blow-off pipe islocated on each of these water mains and serve as a free dischargefor the outlet works. The discharge capacity of the outlet works isunknown.

2) There are no known records of past floods or flood stageheights at the dam.

3) The ungated spillway capacity at the top of dam - 109cfs @ El. 426.8.

4) The ungated spillway capacity at the test flood elevation -

123.5 cfs @ El. 427.0.

5) The gated spillway capacity at normal pool elevation isnot applicable at this dam.

6) The gated spillway capacity at test flood elevation isnot applicable at this dam.

7) The total spillway capacity at test flood elevation -

124 cfs @ El. 427.0.

8) The total project discharge at the top of dam - 109 cfs@ EL. 426.8.

9) The total project discharge at test flood elevation -238cfs @ El. 427.0.

[ -3- 3- -1

I

c. Elevation (ft. above MSL).

1) 3treambed at toe of dam ..................... 409±

2) Bottom of cutoff ................................... 405±

3) Maximum tailwater .......................... N/A

4) Recreation pool ............................ N/A

5) Full flood control pool ..................... N/A

6) Spillway crest.............................425±

7) Design surcharge ........ %................. Unknown

8) Top of dam ................................. 426.8±

9) Test flood design surcharge ................ 427.0

d. Reservoir (Length in feet).

1) Normal pool ................................ 2,000±

2) Flood control pool ......................... N/A

3) Spillway crest pool ........................ 2,000±

4) Top of dam ................................. 2,010±

5) Test flood pool ............................ 2,010±

e. Storage (acre-feet).

1) Normal pool ................................ 429

2) Flood control pool .................. N/A

3) Spillway crest pool ........................ 429

4) Top of dam ................................. 528

5) Test flood pool ............................ 540

f. Reservoir Surface (acres).

1) Normal pool .......... ....................... 55

2) Flood control pool ......................... N/A

3) Spillway crest ............................. 55

4) Test flood pool ......... ............. 55

5) Top of dam ........................... .. ... 55

- 4- [.. . . .,4i -l . . . . I lI . = . . . . . . . . . . ..... - -

g. Dam.

1) Type ....... Earth embankment with broad crested concretespillway

2) Length ........................... . 688 feet

3) Height.......................... 17 feet

4) Top Width .................. ...... 10 feet

5) Side Slopes .... Upstream: 1.5 horizontal to 1 verticalDownstream: 1.5 horizontal to 1 vertical

6) Zoning.......... Selected material under riprap face puddlewall core

7) Impervious Core....................... Puddle wall core

8) Cutoff.......... Puddle wall keyed into original ground

9) Grout curtain ........................ None

h. Diversion and Regulating Tunnel.

1) Type .......... .................. N/A

2) Length ................................N/A

3) Closure . . ..... 9................ N/A

4) Access............................ N/A

5) Regulating Facilities ..... .... N/A

i. Spillway.

1) Type ...9............................. Broad crested concretewe ir

2) Length of weir .................... 15 feet

3) Crest elevation ................9.......425 feet

4) Gates ............................... None

5) U/S Channel ............... 9......... Reservoir

6) D/S Channel ............. ........... Rectangular concrete.channel

j. Regulating outlets.

1) Invert .. .. .......... . .. . .. . .... Unknown

2) Size o ............. . ........... 12" diameter and8" diameter

3) Description ... ....l-woo....... Cast iron pipe

4) Control mechanism .... o......Manually operated

gates

SECTION 2 - ENGINEERING DATA

I 2.1 DESIGN:

No engineering data has been found to provide any informationI about the design of Plainville Reservoir Dam.

2.2 CONSTRUCTION:

A plan showing sections through the center of spillway, gatechamber and embankment section prepared by Connecticut Patent WaterPipe Co. Hydraulic Engineers (all undated), is the only known con-struction information available. A topographic map of the site showinga plan view of the dam was provided by the owner. Information pre-sented in this report was primarily obtained by interviews and directmeasurements of the existing structures.

2.3 OPERATION:

Formal operation records are not available for this dam.

2.4 EVALUATION:

a. Availability. Only minimal engineering information is avail-able for this dam.

b. Adequacy. The lack of in-depth engineering data did not allowfor a definitive review. Therefore, the adequacy of this dam could notbe assessed from the standpoint of reviewing design and constructiondata, but is based primarily on visual inspection, past performancehistory and sound engineering judgement.

c. Validity. The field investigation indicated that the externalfeatures of Plainville Reservoir Dam substantially agree with those onthe available plans.

.4

i[

bI

ISECTION 3 - VISUAL INSPECTIONI

3.1 FINDINGS:

a. General. The initial Phase I visual examination of Plain-ville Reservoir Dam was conducted on 23 October 1979, with a follow-up inspection conducted on 15 November 1979.

In general, the dam was judged to be in fair condition. The verticaland horizontal alignment is good, however a slight dip in the crestwas noted in the vicinity of the downstream gatehouse. Several windowswere observed in the upstream riprap which ends about 2 feet below thecrest of the dam. Some small seeps were observed near the downstreamslope (right side of dam). The concrete spillway and training wallswere in good condition. Some flow of water was observed passing belowthe spillway and flowing out the spillway channel. The deficienciesrequiring correction have been noted.

A visual inspection checklist is included in Appendix A and selectedphotographs of the project are presented in Appendix C.

b. Dam. The dam is a 688-foot long earthen embankment with aspillway se-tion at the left side of the dam. The embankment is com-prised of two straight sections which intersect at approximatelyStation 3+0.

1) Upstream Face - The upstream face is mostly covered withthick vegetation as shown on Photo No. 1. Riprap extends approximatelyhalfway up the slope from the water surface. In some locations theriprap is absent or has been displaced by erosion. At Station 1+0,the riprap is absent in a 10-ft.-wide zone as shown in Photo No. 14.Erosion and slumping is evident at several locations along the upstreamface above the upper edge of the riprap. Vertical scarps up to 2 feethigh on the upstream face of the dam were oterved (see Photo No. 17).

2) Crest - The crest of the dam is covered with grass, andthere is a worn-F !otpath near the right end of the embankment (PhotoNos. 2, 3, 4, 5 and 6). The crest is rounded and slopes slightlytoward both the upstream and downstream faces. Near Station 4+20 thereappears to be a slump near the downstream edge of the crest which isapproximately 4 feet wide and up to 1 foot in height. No longitudinalcracks were observed along the crest of the dam at the time of theinspection. An area of apparent slumping along the downstream crestin thq vicinity of Station 4+0 is shown in Photo No. 15. The slumparea is approximately 4 feet wide and 1 foot high.

o 3) Downstream Face - During the initial site visit on 23

October 1979, the downstream face was covered with an extensive growthof grass, trees, small saplings and brush which made it very difficult

A

traverse the slope (Photos No. 7, No. 9 and No. 13). The dam wasagain visited on November 15, 1979, at which time the majority ofthe vegetation on the downstream slope had been cut and removed,exposing the underlying surface (Photos No. 8 and No. 10). Thedownstream face has an average slope of 1.5H:lV. The screen wellstructure is located just downstream from the toe of the slope nearStation 4+40. An eroded footpath has developed on the downstreamslope adjacent to this structure. An erosion ditch has also formedjust downstream from the structure which is approximately 1.5 feetdeep in the vicinity of the catch basin.

Standing water was observed at several locations along the downstreamslope. Photo No. 16 shows one of the areas in the vicinity of Station2+65. Note that several rocks have been piled around this location.

c. Appurtenant Structures.

1) Spillway - The bottom slab of the broad crested spillwayis in good condition (Photos No. 1 and No. 11). A 6-inch deep notchhas been cut in the slab to concentrate low flows. The vertical down-stream concrete face of the spillway is also in good condition. On 15November 1979, water apparently was flowing beneath or around thespillway. The reservoir water level was below the spillway crest,however water was flowing in the spillway discharge channel.

The spillway has concrete (or concrete faced masonry) training wallson both sides of it to retain the earth embankment of the dam. Theexposed surface of the training walls are in fair condition, withseveral areas of spalled concrete and hairline cracks. It appearsthat the walls have received some repair work as evidenced by concretepatching. The allowable head in the spillway is 1.8 feet. The heightof the training walls decreases at the downstream end of the spillway.At high depths of flow, it may be possible for water in the spillwayarea to overtop the training wall and run down the earth embankmentbehind the walls.

2) Spillway Discharge Apron - The spillway discharges ontoa nearly flat apron or bed of stone riprap as wide as the spillway.This apron serves as an impact and stilling area. The riprap wasovergrown with weeds and small diameter brush which prevented observa-tion of the entire channel bed. The sides of the apron area consistof stone masonry retaining walls, approximately 4 feet high. Somedeterioration of the walls has occurred, and two short sections ofwall have partially collapsed.

3) Spillway Discharge Channel - The open channel conveyingwater away from the spillway discharge apron is five feet wide and isconstructed of stone masonry. It is generally in good condition, withno visible erosion or deterioration. Weeds and brush are also growingin its bed as shown in Photo No. 12.

-9

I4) Outlet Works - The abandoned gatehouses are shown in

Photo No. 18. An 8-inch and 12-inch diameter outlet pipes werepreviously used as water supply mains and were not visible. Thecontrol valves were found at the toe of the dam in the vicinityof the gatehouses. There are two 6-inch blow-off pipes locatedadjacent to the water supply pipes, and these blow-offs are openedprior to major storm events to lower the reservoir water level.

d. Reservoir. The watershed is rural and totally wooded.The perimeter of the reservoir has mild to steep slopes, and ap-peared stable (Photo No. 19). There were no visible sediment de-posits in the reservoir.

e. Downstream Channel. The downstream channel is a naturalbrook, which has a stable sand bed, with some light vegetationnoted. The banks are stable, with no signs of erosion.

3.2 EVALUATION:

Based on the visual inspection, Plainville Reservoir Dam is infair condition.

Trespassing has led to the development of a path along a portion ofthe crest of the dam and along a section of the downstream slope.There is an extensive growth of brush and vegetation on the upstreamand downstream slope which requires periodic cutting to allow adequateinspection.

Several wet and spongy areas were observed in the vicinity of thedownstream toe. Underflow beneath the spillway could lead to erosionand a possible stability problem.

10

I

- 10 -

SECTION 4 - OPERATIONAL AND MAINTENANCE PROCEDURES

4.1 OPERATIONAL PROCEDURES:

a. General. Plainville Reservoir has been used in the recentpast as a water supply reservoir. However, at the present time,no water from the reservoir enters the water supply system. Two6-inch diameter blow-off pipes are opened prior to major storm eventsto lower the water level in the reservoir.

b. Description of Any Warning System In Effect. There is nowarning system in effect at this project.

4.2 MAINTENANCE PROCEDURES:

a. General. The crest of the dam is occasionally mowed andthe downstream slope is cleared of brush on a periodic basis.

b. Operating Facilities. There are no formal maintenance pro-cedures followed for the operating facilities.

4.3 EVALUATION:

Regular operational maintenance procedures for this dam and itsappurtenances have not been developed or implemented.

An emergency action plan should be prepared to prevent or minimizethe impact of failure. This plan should list the expedient actionto be taken and authorities to be contacted.

now"

SECTION 5 - EVALUATION OF HYDRAULIC/HYDROLOGIC FEATURES

5.1 GENERAL:

The Plainville Reservoir Dam is a 688-foot long earth embank-ment with a maximum height of approximately 17 feet. The dam has abroad crested spillway made of concrete, with a width of 15 feet.The allowable head at the spillway is 1.8 feet, and the verticaldrop at the end of the spillway is approximately 3.5 feet. PlainvilleReservoir impounds a normal storage of about 430 acre-feet and ahlut530 acre-feet to the top of the dam. The spillway is capable ofdischarging about 110 cfs with surcharge to the top of the dam.

The watershed consists of 0.37 square miles of land, all rural,located on the western side of a prominent rocky ridge.

5.2 DESIGN DATA:

There is no known data available on the hydraulic design ofthe dam.

5.3 EXPERIENCE DATA:

No records are available in regard to past operation of thereservoir or of outlets. The only available information on thepast performance is from an interview with a nearby resident whohas lived in the area for over 25 years. This person reported thatthe maximum observed flow depth over the spillway was approximately6 inches (20 cfs).

5.4 TEST FLOOD ANALYSIS:

The test flood for determining the spillway adequacy is basedupon OCE guidelines. The size classification of the dam is "small,"based upon a height of 17 feet and storage volume of 528 acre-feet.The hazard potential is "high," due to suburban land use downstreamof the dam and the results of dam failure analysis. The spillwaytest flood in the Corps of Engineers guidelines for this size damand hazard potential ranges from the 1/2 PMF to the PMF. The recom-mended spillway test flood is 1/2 PMF, due to the small height ofthe dam and degree of downstream development.

The magnitude of the spillway test flood was determined by using ahydrograph method developed by the U.S. Department of Agriculture,Soil Conservation Service, and described in the publication "Designof Small Dams," by. the U.S. Bureau of Reclaimation.

The runoff rates were developed for storms with durations of one andsix hours, to determine the most critical case.

ii -12-

The hydrographs were routed through the reservoir using a computerprogram based on stage-storage and stage-discharge data. Thereservoir was assumed to be full and level with the spillway priorto the storm event.

The results of the routing indicate that the six-hour durationspillway test flood would have a peak reservoir stage at elevation427.0 (0.2 ft. above the crest of the dam). The dam would be over-topped by the spillway test flood.

The spillway capacity (110 cfs) is equal to 46 percent of the testflood outflow rate (238 cfs).

5.5 DAM FAILURE ANALYSIS:

The downstream impact of a dam failure was analyzed using theCOE "Rule of Thumb Guidance for Estimating Downstream Dam FailureHydrographs" dated April, 1978.

Based upon an assumed breach width equal to 40% of the dam's widthat mid-height, the peak flood flow leaving the dam would be 32,400cfs, with an initial depth of 13.3 downstream of the dam. The floodflow rate and flow depth diminish slowly as it initially moves down-stream, due to a steep valley and the low storage volume. The widthof the flood prone area then increases in the vicinity of FlandersRoad, and the height of the flood wave decreases to about 6 feet.

The areas of probable impact include the single-family residentialproperties along Flanders Road, and Shuttle Meadow Road areas of theTown of Southington. The number of dwellings in the probable impactarea is about 12.

Interstate Highway 84 crosses the path of the failure flood wave,and possibly could serve as an embankment impounding.a portion ofthe flood flow. The depth of flooding at the low area east of thehighway is estimated to be in the range of 10 feet, (4 houses).The other houses would generally be subjected to flooding of 4feet or less.

-13-

SECTION 6 - EVALUATION OF STRUCTURAL STABILITY

6.1 VISUAL OBSERVATIONS:

The visual observation did not disclose any immediate stabilityproblems. The vertical displacement resulting from erosion alongthe upstream face above the top of the riprap varies up to 6 inchesin height. Some slumping and erosion of the downstream edge of thecrest has occurred in the vicinity of Station 4+20. Some seepage maybe occurring near the toe, especially in the vicinity of Station 2+60.

6.2 DESIGN AND CONSTRUCTION DATA:

No original design and construction data are available.

6.3 POST-CONSTRUCTION CHANGES:

No records of post-construction changes are available.

6.4 SEISMIC STABILITY:

Plainville Reservoir Dam is located in Seismic Zone 1 and inaccordance with the recommended guidelines of the Corps of Engineersdoes not warrant seismic analysis.

1

- 14 -

SECTION 7 - ASSESSMENT, RECOMMENDATIONS

AND REMEDIAL MEASURES

7.1 DAM ASSESSMENT:

a. Condition. The visual examination indicates that Plain-ville Reservoir Dam is in fair condition. The major concerns re-garding the long-term performance of the dam are:

1) Existence of possible seepage areas along the downstreamtoe of the dam which are undetected due to the extensive vegetationin this area.

2) Existence of erosion on the upstream slope above the topof the riprap protection.

3) Underflow in the vicinity of the spillway, that couldundermine the spillway and cause stability problems.

4) A number of operation and maintenance procedures shouldbe followed as outlined in 7.3a, below.

The capacity of the spillway is inadequate to pass the 1/2 PMF testflood outflow of 238 cfs without overtopping the dam. The test floodwould overtop the dam by 0.2 foot. The spillway is adequate to passabout 46 percent of the test flood without overtopping the dam.

b. Adequacy of Information. The information available is suchthat the assessment of the dam must be based primarily on the resultsof the visual inspection, past performance history and sound engineer-ing judgement.

c. Urgency. The recommendations made in 7.2 and 7.3 should beimplemented by the owner within one year after receipt of this Phase Iinspection report.

7.2 RECOMMENDATIONS:

a. It is recommended that the owner retain the services of a

qualified registered engineer to perform the following:

1) Investigate the possibility of seepage along the toeof the dam and to determine what type of seepage control measures are

required, if any.

2) Investigate the possibility of movement of the downstreamslope of the dam.

3) Investigate the underflow occurring at the spillway andinitiate required repairs.

- 15 -

4) Determine method of repair of the rip rap on the upstreamface.

7.3 REMEDIAL MEASURES:

a. operating and Maintenance Procedures.

1) The owner should provide proper vegetation on the up-stream and downstream slopes of the dam.

2) The owner should take such action as is necessary toprevent trespassing on the crest and slopes of the dam.

3) The owner should maintain the area within 25 feet down-stream from the toe of the dam clear of trees and brush.

4) Remove trees and brush from the downstream channel andat a distance of 20 feet on either side of the channel for a distanceof 100 feet downstream of the dam.

5) Develop a formal surveillance and flood warning plan,with an operational procedure to be followed in the event of an emer-gency.

6) Institute procedures for an annual periodic technicalinspection of the dam and its appurtenant structures.

7) Outlet works capable of drawing down the reservoir

should be maintained operational and in good repair.

7.4 ALTERNATIVES:

There are no practical alternatives to the recommendations inSections 7.2 and 7.3.

!i

- 16 -11:

APPENDIX A

INSPECTION CHECK LIST

L _______

INSPECTION CHECK LIST

PARTY ORGANIZATION

PROJECT PLAINVILLE RESERVOIR DAM DATE Oct. 23, 1979Ledge RoadPlainville, Conn. TIME 0930

WEATHEROvercast - 650 F

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

PARTY:

1. R. Smith, FGA, Project Manager

2. J. MacBroom, FGA, Hydraulics/Hydrology

3. R. Murdock, GEI, Geotechnical

4.

5.

PROJECT FEATURE INSPECTED BY REMARKS

1.

2.

3.

4.

.5.

6.

7.

8.

9.

10.

A-1

PERIODIC INSPECTION CHECK LISTNATIONAL DAM INSPECTION PROGRAM

DAM: Plainville Reservoir Dam DATE:OCt. 23, 1979

AREA EVALUATED CONDITIONS

DAM EMBANKMENT

Crest Elevation

Current Pool Elevation

Maximum Impoundment toDate Unknown.

Surface Cracks None observed.

Pavement Condition Grass, good.

Movement or Settlement Slight dip in d.s. direction just aboveof Crest d.s. gatehouse.

Lateral Movement Good.

Vertical Alignment Good.

Horizontal Alignment Good.

Condition at Abutment and Erosion in the vicinity of the spillwayat Concrete Structures wing wall.

Indications of Movementof Structural Items onSlopes None.

Trespassing on Slopes Footpath in the vicinity of the d.s.gatehouse.

Sloughing or Erosion ofSlopes or Abutments None observed.

Rock Slope Protection - Many windows observed in the u.s. riprap;Riprap Failures riprap ends -2 ft below crest.

Unusual Movement orCracking at or near Toes None observed.

Unusual Embankment or Small seepage observed near d.s. toe nearDownstream Seepage Sta 2+65.

Piping or Boils None observed.

Foundation Drainage

Features None.

Toe Drains None.

Instrumentation System None.

xtqnsive. veetation on u.s. and d.s. slopeVegetation fe-inspected-on 15 Nov. 1979 - brush cut anI grass mowed- A-I t

' ...A.. .€


DAM, Plainville Reservoir Dam DATE:OCt. 23, 1979


DIKE EMBANKMENT Not applicable.

Crest Elevation

Current Pool Elevation

Maximum Impoundment toDate

Surface Cracks

Pavement Condition

Movement or Settlementof Crest

Lateral Movement

Vertical Alignment

Horizontal Alignment

Condition at Abutment andat Concrete Structures

Indications of Movementof Structural Items onSlopes

Trespassing on Slopes

Sloughing or Erosion ofSlopes or Abutments

Rock Slope Protection -

Riprap Failures

Unusual Movement orCracking at or near Toes

Unusual Embankment orDownstream Seepage

Piping or Boils

Foundation Drainage

Features

Toe Drains

Instrumentation-System

S"vegetation A-


DAM' Plainville Reservoir Dam DATE' Oct. 23, 1§79


OUTLET WORKS - INTAKECHANNEL AND INTAKESTRUCTURE

a. Approach Channel

Slope Conditions Underwater concrete apron 3 ft upstreamfrom spillway location.

Bottom Conditions

Rock Slides or Falls

Log Boom

Debris

Condition of ConcreteLining

Drains or Weep Holes

b. Intake Structure

Condition of Concrete

Stop Logs and Slots

L

"14j- 4-


DAMS Plainville Reservoir Dam DATE: Oct. 23, 1979


OUTLET WORKS - CONTROL TOWER

a. Concrete and Structural Wooden control tower, deteriorated, andsome rotting noted.

General condition

Condition of Joints

Spalling

Visible Reinforcing

Rusting or Staining ofConcrete

Any Seepage orEfflorescence

Joint Alignment

Unusual Seepage or Leaksin Gate Chamber

Cracks

Rusting or Corrosion ofSteel

b. Mechanical and Electrical

Air Vents

Float Wells

Crane Hoist

Elevator

Hydraulic System

Service Gates Operated on frequent basis to lower waterel. in reservoir.

Emergency Gates

Lightning ProtectionSystem

Emergency Power SystemIWiring and Lighting[System in Gate Chamber

_ A-$


DAM, Plainville Reservoir Dam DATE:OCt. 23, 1979


OUTLET WORKS - TRANSITION Not applicable.AND CONDUIT

General Condition ofConcrete

Rust or Staining onConcrete

Spalling

Erosion or Cavitation

Cracking

Alignment of Monoliths

Alignment of Joints

Numbering of Monoliths

j*

4 ____ ______

________________•__ -

PERIODIC INSPECTION CHECK LIST

S, NATIONAL DAM INSPECTION PROGRAM

DAM . Plainville Reservoir Dam DATE: Oct. 23, 1979


OUTLET WORKS - OUTLET Not applicable.

STRUCTURE AND OUTLETCHANNEL

General Condition of

Concrete

Rust or Staining

Spalling

Erosion or Cavitation

Visible Reinforcing

Any Seepage orEfflorescence

Condition at Joints

Drain Holes

Channel

Loose Rock or TreesOverhanging Channel

Condition of DischargeChannel

A_-


DAM, Plainville Reservoir Dam DATE Oct. 23, 1979


OUTLET WORKS - SPILLWAY WEIRAPPROACH AND DISCHARGECHANNELS

a. Approach Channel

General Condition Underwater.

Loose Rock OverhangingChannel

Trees OverhangingChannel

Floor of ApproachChannel

b. Weir and Training Walls

General Condition ofConcrete Generally in good condition.

Rust or Staining None.

Spalling Minor spalling.

Any Visible Reinforcing None.

Any Seepage orEfflorescence None.

Drain Holes None observed.

c. Discharge Channel

General Condition Fair,- 5 ft of wall collapsed belowspillway weir along right side.

Loose Rock OverhangingChannel None.

Trees OverhangingChannel None.

Floor of Channel Natural stone and gravel bottom.

Other Obstructions None.

A-$,-m


DAM:_ Plainville Reservoir Dam DATE- Oct. 23, 1979


OUTLET WORKS - SERVICE None.

BRIDGE

a. Superstructure

Bearings

Anchor Bolts

Bridge Seat

Longitudinal Members

Under Side of Deck

Secondary Bracing

Deck

Drainage System

Railings

Expansion Joints

Paint

b. Abutment & Piers

General Condition ofConcrete

Alignment of Abutment

Approach to Bridge

Condition of Seat andBackwall

-9T[,4

APPENDIX B

ENGINEERING DATA

O

HN

0

94

40

E4O-4

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Edge Of Pond

PLAN T "

~335

TopO o E

330 To

7 320

31 12+00 3+-00 4400

DOWNSTREAM ELENNTS

[DD949 TTHESELEV.OR U.S.C IN G

DGate House

T-"

__,ous it'_A ANN N F A

d . -- 33

'46

S70,

--------------

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PLAINVILLE7k

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PLAN A -

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4o.1- .--~-----..-------* - - - -*. - - -. ~.. -WIN

APPENDItx c

PHOTOGR~APHS

side.

II1

PHOTO #1: Upstream face of dam from left (South)side.

I

PHOTO #3: Crest of dam looking toward spillway(from Sta. 4+0).

I

I

PHOTO #4: Crest of dam looking toward right(North) side (from Sta. 4+0).3

II

I.

PHOTO #5: Crest of dam looking toward spillway.Note intake structure.

IPHOTO #6: Left abutment looking along the dar. crest.

I

I "it-i

II]

PHOTO #7: Downstream slope of dam looking towardright (north).

PHOTO #8: Downstream slope of dam looking towardright (North). (Nov. 15, 1979)

I

4PHOTO #1: Downstream slope of dam looking towardleft abutment. (Nv 15 19 )

I

UIIIII

PHOTO #11: Spiliway.

I1II

:3.

ii

Iup£- PHOTO $12: Spiliway channel looking downstream from

a location near the left spillway channelwall.

PHT #14 Erso ln•ptemfc fdmna

IIIII

PHOTO #13: Downstream slope looking toward rightI (North) .

4.4

[

I

_ IIJI

PHOTO #15: Area of apparent slumping along the down-

stream crest of the dam in the vicinityof Sta. 4+0. Slump area is approximatelyj4 ft. wide and 1 ft. high.

j I r

I PHOTO #16: Close up of wet area near toe of down-stream slope (Sta. 2+50).

IIIIIII7

PHOTO #17: Vertical scarp up to 2 ft. high on theupstream face of the dam.

P

II

I PHOTO #18: Abandoned gate houses downstream of dam.

* II

V

-L _____________-----.----.--- ------- ~*---.--- ___ -

40r

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DETERMINATION OF SPILLWAY TEST FLOOD*

A. SIZE CLASSIFICATION

Storage Volume (Ac.-Ft.) 528

Height of Dam (Ft.) 17

Size Classification SMALL

B. HAZARD POTENTIAL CLASSIFICATION

Category Loss of Life Economic Loss

Low None expected Minimal

Significant Few Appreciable

ore than few) Excessive

Hazard Classification MlM

C. HYDROLOGIC EVALUATION GUIDELINES

Hazard Size Spillway Design Flood

Low Small 50 to 100-Year FrequencyIntermediate 100-Year Frequency to 1/2 PMFLarge 1/2 PMF to PMF

Significant Small 100-Year Frequency to 1/2 PMFIntermediate 1/2 PMF to PMFLarge PMF

iermediate PMFLarge PMF

" ," Spillway Test Flood //Z PMF

*Based upon "Recommended Guidelines for Safety Inspection of* Dams" Department of the Army, Office of the Chief of Engineers,

November 1976.

7,Ii -

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_____________ONE COLUMB3US PLAZA. NEW FIEN. CONN 0851012037MIM2 CHKD. BY FS O A TE .~ L L.

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PROEC I.. FLAHERTY-GIAVARA ASSOCIATES SHEET NO. 10 OF -___* ~A&.Iloom~" ENVIRONMENTAL DESIGN CONSULTANTS 13Y kL.J-m DATE 2Z116171

________ ON COLUMMS PAZA NE P"EN. CONN~ au003WaoIuMa CHK.B P(.3y. DATE -4AL~

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PLAINVILLE RESERVOIR DAM 79-90-1 DKS 12/17/79

FGA F"LCOD CE ,U* I NG

APPROXIMATE FLOOD WAVE ROUTING BASED UPON U.S. ARMY CORPSOF ENGINEERS' "RULE OF THUMB GUIDANCE FOR ESTIMATINGDOWNSTREAM DAM FAILURE HYDROGRAPHS" DATED APRIL, 1978.

INITIAL STATION = 0 +0INITIAL WAVE HEIGTH = 17.0 FTASSUMED BREACH WIDTH = 275.0 FT

INITIAL RESERVOIR STORAGE = 528 ACRE-FT"COMPUTED FLOOD WAVE PEAK FLOW 32,388 CFS

!T-FT I 3PN -4 +- S

OFFSET ELEV. OFFSET ELEV. OFFSEI ELEV.

N = 0.080-1000.0 FT 440.0 FT -500.0 FT 430.0 FT -300.0 FT 420.0 FT-170.0 FT 410.0 FT -50.0 FT 400.0 FT -6.0 FT 398.0 FT

N = 0.040

-6.0 FT 398.0 FT -3.0 FT 396.0 FT 3.0 FT 396.0 FT6.0 FT 398.0 FT

N = 0.0806.0 FT 398.0 FT 50.0 FT 400.0 FT 140.0 FT 410.0 FT

400.0 FT 450.0 FT

AREA WETTED PER IMETER N VELOC I TY FLOW

987.6 SF 157.2 FT 0.080 13.2 FPS 13,100CFS154.7 SF 13.2 FT 0.040 40.1 FPS 6,222CFS

855.1 SF 129.1 FT 0.080 13.7 FPS 11,747CFS

INVERT DEPTH W. SURFACE AREA VELOCITY FLOW SLOPE

396.0 FT 13.3 FT 409.3 FT 1,997 SF 15.5 FPS 31,070 CFS 0.0440

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OFFSET JELEV. OFFSET ELEv. OFFSET ELEV.

N = 0. 080-2550.0 FT 400.0 FT -250.0 FT 400.0 FT -100.0 FT 390.0 FT

-6.0 FT 382.0 FT

N =0.040-6.0 FT 382.0 FT -3.0 FT 380.0 FT 3.0 FT' 380.0 FT6.0 FT 382.0 FT

N = 0.0806.0 FT 382.0 FT 180.0 FT 400.0 FT 450.0 FT 420. 0 FT

580.0 FT 410.0 FT 950.0 FT 410.0 FT 1070.0 Fl 450.0 FT

AREA WETTED PER IMETER N VELOCITY FLOW

542.5 SF 118.0 FT 0.080 21.1 FPS 115489CFS132.8 SF 13.2 FT 0.040 71.3 FPS 9,485CFS443.0 SF 93.0 FT 0.080 21.6 FPS 9,6O3CFS

INVERT DEPTH W. SURFACE AREA VELCJCITY FLOW SLOPE

380.0 FT 11.5 FT 391.5 FT 19118 SF 27.3 FPS 30,5723 CFS 0.1700

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OFFSET ELEV. OFFSET ELEV. _OFFSET* ELEV. __

N = 0. 080-1200.0 FT 300.0 FT -850.0 FTl 250.0 FT -600.0 FT 240.0 FT-200.0 FT 240.0 FT -20.0 FT 230.0 FT -6.0 FT 222.0 FT

N = 0.040-6.0 FT 222.0 FT -3.0 FT 220.0 FT : .O FT 220.0 FT6.0 FT 222.0 FT

N = 0.0806.0 FT 222.0 Fl 630.0 FT 250.0 FT 800.0 FT 260.0 FT

1100.0 FT 270.0 FT 1270.0 FT 290.0 FT 1920.0 FT 300.0 FT

AREA WETTED PER IMETER N VELOC ITY FLOW

83.S SF 36.6 FT 0.080 13. 3 ri'S 1, 11SCFS127.6 SF 13.2 FT 0.040 69.8 FPS 8,919CFS930.0 SF 203.8 FT 0.080 21.1 FPS 19s7llCFS

INERT DEPTH W. SURFACE AREA VELOCITrY FLOW SLOPE

220.0 FT 11.1 FT 231.1 FT lvl4l SF 26.0 FPS 2974 CS .,2

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OFFSET ELEV. OFFSET ELEY. OFFSET ELEV.

N = 0.080-700.0 FT 180.0 FT -450.0 FT 180.0 FT -150.0 FTr 180.0 FT

N = 0.040-150.0 FT 180.0 FT 0.0 FT 178.0 FT 250.0 FT 180.0 F"T

N = 0.080250.0 FT 180.0 FT 1900.0 FT 190.0 FT 2300.0 FT 200.0 FT

AREA WETTED PERIMETER N VELOCITY FLOW

19267.0 SF 550.0 FT 0.080 5.0 FPS 6v36OCF-S1,.321.5 SF 400. 0 FT 0.040 12. 7 FPS 169,8IO0CFS437.8 SF 380.1 FT 0.080 3.1 FPS 1,384CFS


178.0 FT 4. 3 FT 182. 3 FT 3, 026 SF S. 1 FPS 24,61-.l5 CFS 0. 0240

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OFFSET ELEV. OFFSET ELEV. OFFSET- -ELEV.----

N = 0. 080-800.0 FT 180.0 FT -220.0 FT 180.0 FT

N = 0.040-220.0 FT 180.0 FT* 0.0 FT 177.0 FT 200.0 FT 180.0 FT

N = 0.080200.0 FT 180.0 FT 1000.0 FT 180.0 FT

AREA WETTED PERIMETLR N VELOCITY _FLOW

2,4a5.6 SF 580.0 FT 0.080 1.5 FPS 3,698CFS2v386.5 SF 420.0 FT 0.040 3.7 FPS 8,926CF53,345.7 SF 800.0 FT 0.080 1.5 FPS SvlO1CFS


177.0 FT 7.1 FT 184.1 FT 8,157 SF 2.1 FPS 179,72E. CFS 0.0010

OFFSET ELEV. OFFSET ELEv. OFFSET ELEV.

N = 0. 080-2S00.0 FT 190.0 FT' -480.0 FT 180.0 FT

N = 0.040-480.0 FT 180.0 FT 0.0 FT 176.0 FT --220. 0 FT 180. 0 FT

N = 0.080220.0 FT 180.0 FT 450.0 FT 180.0 FT 3550.0 FTr 190.0 FT

AREA WETTED PER IMETER N VELOCIT T - FLOW

817.4 SF S74.6. FT 0.080 0.7 FPS 607CFS3,391.4 SF 700.0 FT 0.040 3.3 FPS 11,407CF610908.8 SF 1111.9 FT 0.080 0.8 FPS lv6O'7CFS

INVERT' DEPTH W. SURFACE AREA VELOCITY FLOW SLOPE

176.0 FT 6.8 FT 182.8 FT 6x117 SF 2.2 FPS 13,6.21 CFS 0.0010

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APPENDIX E

INFORMATION AS CONTAINED IN THE

NATIONAL INVENTORY OF DAMS

ii/!iiieeeeee i eeeeeeeeeeeee/iof the downstream slope of the dam should he investigated. in...

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