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RD-fi144 062 NATIONAL PROGRAM FOR INSPECTION OF NON-FEDERAL
DAMS i/iLAUREL LAKE DAM (CT 8 (U) CORPS OF ENGINEERS WALTHAM
I MA NEW ENGLAND DIV SEP 80UNCLASSIFED G 0/ N
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MICROCOPY
RESOLUTION
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* CONNECTICUT RIVER BASINNEW HARTFORD, CONNECTICUT
LAUREL LAKE DAMQ CT 00372
PHASE I INSPECTION REPORT
* NATIONAL DAM INSPECTION PROGRAM
AF DTICELECT-F .'
AUG 8 1984
r. E NLN IIIN OP ADEPARTMENT OF THE ARMY
NEWENGANDDIVSIO, CRPSOF ENGINEERSC1. WALTHAM, MASS. 02154
La...SEPTEMBER, 1980
This document has been 0PP!r'v'dfor public release atid :
.. I distribution is unlimited
'0IINr ,A'-,;T"T EnSECURITY CL ASSIFICATION OF THIS PAGE (When Deei Entered)
REPORT DOCUMENTATI( PAGE READ INSTRUCTIONSBEFORE COMPLETING FORM
I. REPORT NUMBER 2. GOVT ACISSO HNO RECIPIENT'S CATALOG NUMBER
CT 003724 TITLE (rnd Subtie) S. TYPE OF REPORT & PERIOD COVERED
Laurel Lake Dam INSPECTION REPORT
NATIONAL PROGRAM FOR INSPECTION OF NON-FEDERAL -. PERFORMINOORO. REPORT NUMUERDAMS ..7. AUTHOR(a) S. CONTRACT OR GRANT NUMBER(e)
U.S. ARMY CORPS OF ENGINEERSNEW ENGLAND DIVISION
S. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASKAREA & WORK UNIT NUMBERS
II. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE
DEPT. OF THE ARMY, CORPS OF ENGINEERS September 1980NEW ENGLAND DIVISION, NEDED 13. NUMBER Of PAGES
424 TRAPELO ROAD, WALTHAM, MA. 02254 5514. MONITORING AGENCY NAME A AOORESSI(ll dliteent Irm Co091.mllng OWiles) IS. SECURITY CLASS. (of thie report)
UNCLASSIFIED|Its. DECL ASSI PIC ATI ON/DOWNGRAOING
SCHEDULE
16. DISTRIBUTION STATEMENT (ot thie 0110porl)
APPROVAL FOR PUBLIC RELEASE: DISTRIBUTION UNLIMITED
* 17. DISTRIBUTION STATEMENT (of the eberec entered in Block 20. II d11ll44,01 ho Repel )
I tll. 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 ofNon-Federal Dams; use cover date for date of report.
IS. KEY WORDS (Continue on revere olde It neceeer and 11"iI4' bY bock number)
DAMS, INSPECTION, DAM SAFETY,
Connecticut River BasinNew Hartford, Connecticut
20. ABSTRACT (Couinue an revoee ide ID neeeoeery end Identity by block number)The Laurel Lake Dam is an earth embankment built about 1965 and impounding an un-
.- named tributary to Morgan Brook in New Hartford. The dam is approximately 595 feet%long, 10 feet wide at the top, 27 feet high and has a maximum impoundment of 176
acre-feet. Laurel Lake Dam is classified as a significant hazard, small size dam.The test flood range is from the 100 year storm to one-half the PMF. Based uponthe visual inspection at the site and past performance of the dam, the project isJudged to be in poor condition.
DD I AN' 1471 EOITION OF I -0 s ,S IS OBSOLETE
% 21- .
DEPARTMENT OF THE ARMY
NEW ENGLAND DIVISION. CORPS OF ENGINEERS
424 TRAPELO ROAD
RELT WALTHAM. MASSACHUSETTS 02254
-..- REPLY TO
ATTENTION OF:
NEDED DEC19 i9BO"DE 19°
Honorable Ella T. Grasso... Governor of the State of Connecticut
State CapitolHartford, Connecticut 06115
Dear Governor Grasso:
Inclosed is a copy of the Laurel Lake Dam (CT-00372) Phase I InspectionReport, which was prepared under the National Program for Inspection ofNon-Federal Dams. This report is presented for your use and is basedupon a visual inspection, a review of the past performance and a briefhydrological study of the dam. A brief assessment is included at thebeginning of the report. I have approved the report and 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 program.
A copy of this report has been forwarded to the Department of Environ-" mental Protection, the cooperating agency for the State of Connecticut.
In addition, a copy of the report has also been furnished the owner,Mountain Laurel Development Corp., West Hartford, Conn.
Copies of this report will be made available to the public, upon
request, by this office under the Freedom of Information Act. In thecase of this report the release date will be thirty days from the date
* of this letter.
I wish to take this opportunity to thank you and the Department of 4f
* Environmental Protection for your cooperation in carrying out thisprogram.
Sincerely, Ac't!:3sAon For
Corpsl ndor-
md~~~~~~~~ LLI E OGO, *.~ .i~~to
d bAs stated unliritof E gineerst g Division Engineer
AvtI 1 1 ty C,)deS
Thisdocuent as been appToved
dist~tib~1 is unlimited.
CONNECTICUT RIVER BASINNEW HARTFORD, CONNECTICUT
LAUREL LAKE DAMCT 00372
So
N1
PHASE I INSPECTION REPORTNATIONAL DAM INSPECTION PROGRAM
DEPARTMENT OF THE ARMY
NEW ENGLAND DIVISION, CORPS OF ENGINEERS
I WALTHAM, MASS. 02154
.SE
.
.. .. . .. ....... .DE A T EN F TH .M
*-*.5-**di*N EW ENGLA N D D*.*S.. . . .CO*S OF E G I E R
BRIEF ASSESSMENT
PHASE I INSPECTION REPORT
NATIONAL PROGRAM OF INSPECTION OF DAMS
Name of Dam: LAUREL LAKE DAMInventory Number: CT 00372
C State Located: CONNECTICUTCounty Located: LITCHFIELDTown Located: NEW HARTFORDStream: UNNAMED TRIBUTARY TO MORGAN BROOKOwner: MOUNTAIN LAUREL DEVELOPMENT CORPORATIONDate of Inspection: MAY 9, 1980, June 3, 1980Inspection Team: PETER HEYNEN, P.E.
JAY COSTELLOJEFFREY 0. BORNEMURALI ATLURU, P.E.MIRON PETROVSKYTIMOTHY KAVANAUGH
The Laurel Lake Dam is an earth embankment built about 1965 andimpounding an unnamed tributary to Morgan Brook in New Hartford,Connecticut. The dam is approximately 595 feet long, 10 feet wide
, at the top, 27 feet high and has a maximum impoundment of 176 acre-3 feet. The spillway is a 40 ft. long unlined earth channel located
at the left end of the dam. A 24 inch cast iron drop inlet pipe islocated approximately 10 feet upstream from the central portion ofthe dam. A 30 inch x 30 inch steel frame structure with removableboards is used to control the lake level. No low-level outlet wasfound at the dam. The outlet is a 24 inch concrete pipe. Theslopes and top of the dam are densely vegetated with brush and treesaplings. A footpath extends the entire length of the dam crest.
In accordance with the Army Corps of Engineers Guidelines,Laurel Lake Dam is classified as a significant hazard, small sizedam. The test flood range is from the 100 year storm to one-halfthe Probable Maximum Flood (h PMF). The test flood for Laurel LakeDam is selected as the h PMF. Peak inflow to the impoundment is 350cfs; peak outflow is 240 cfs with the dam maintaining 0.75 feet offreeboard. Based upon hydraulic computations, the spillway capa-city is 410 cfs, which is greater than 100% of the routed test floodoutflow.
Based upon visual inspection at the site and past performanceof the dam, the project is judged to be in poor condition. Thereare areas requiring maintenance, monitoring and repair such asI-.. seepage, embankment repair, lack of proper spillway protection andvegetation on the embankment.
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It is recommended that the owner initiate further studies, tobe performed by a registered professional engineer. These shouldinclude inspection of the drop inlet, 24 inch concrete outlet pipe,
i and conduit through the embankment; providing a means of loweringthe lake level in case of emergencies at the dam; repair of thespillway; implementation of a geotechnical investitation program todetermine embankment and foundation conditions; an investigation ofthe seeps at the toe of the embankment and preparation of "as-built" drawings for future reference.
It is recommended that the seepage at the dam be investigatedimmediately upon the owner's receipt of the report. All otherrecommendations and remedial measures should be instituted with one(1) year of the owner's receipt of this report.
• ....
Pete M..eynen ,.
Project Manager - Geotechni 'tCahn Engineers, Inc.
C. Michael Horton, PE. .-(-Department Head 0.84Cahn Engineers, Inc.
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This Phase I Inspection Report on Laurel Lake Dam
has been reviewed by the undersigned Review Board members. In ouropinion, the reported findings, conclusions, and recouendation areconsistent with the Recomended Guidelines for Safety Inspection ofDams, and with good engineering judgment end practice, and is herebysubmitted for approval.
CARNEY M. TERZIAN, MEMBER-Design Branch
Engineering Division
"'a
RICHARD DIBLONO, MMEWater Control BranchEngineering Division
ARAMAST MAHTESIAN, CHAIRMAN
Geotechnical Enqineering Branch* Engineering Division
APPROVAL RICOOIENDED:
! B.flTAR
Chief. Rngineering Division
* - . *', . . -. . . .-.. . . - - . . ......%. . . .- . . . . ... I
J" "PREFACE
. This report is prepared under guidance contained in the Recom-
mended 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 inspection. 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 tnereported condition of the dam is based on observations of fieldconditions at the time of inspection along with data available tothe inspection 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 otherwisebe detectable if inspected under the normal operating environmentof the structure.
It is important to note that the condition of a dam depends onnumerous and constantly changing internal and external conditions,and is evolutionary in nature. It would be incorrect to assume thatthe present condition of the dam would necessarily represent thecondition of the dam at some point in the future. Only throughcontinued care and inspection can there be any chance that unsafeconditions will be detected.
Phase I inspections are not intended to provide detailedhydrologic and hydraulic analyses. In accordance with the esta-blished Guidelines, the Spillway Test Flood is based on the esti-mated "Probable Maximum Flood" for the region (greatest reasonablypossible storm runoff), or fractions there of. Because of themagnitude and rarity of such a storm event, a finding tnat aspillway will not pass the test flood should not be interpreted asneccessarily posing a highly inadequate condition. The test floodprovides a measure of relative spillway capacity and serves as anaid in determining the need for more detailed hydrologic andhydraulic studies, considering the size of the dam, its general
* .condition and the downstream damage potential.
S-iv
", 7, t
The Phase I Investigation does not include an assessment of theneed for fences, gates, no-trespassing signs, repairs to existingfences and railings and other items which may be needed to minimizetrespass and provide greater security for the facility and bafetyto the public. An evaluation of the project for compliance with
- OSHA rules and regulations is also excluded.
-" The information contained in this report is based on thelimited investigation described above and is not warranted toindicate the actual condition of the dam. The integrity of the dam
I can only be determined by a means of a monitoring program and/or adetailed physical investigation. The accuracy of available data isassumed where not in obvious conflict with facts observable duringthe visual inspection.
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TABLE OF CONTENTS
Page
Letter of Transmittal
Brief Assessment i, ii
Review Board Signature Page iiiPreface iv, vTable of Contents vi-viiiOverview Photo ixLocation Map x
SECTION 1: PROJECT INFORMATION
1.1 General ... .................................... 1-1
a. Authorityb. Purpose of Inspection Programc. Scope of Inspection Program
1.2 Description of Project ...................... 1-2
a. Locationb. Description of Dam and Appurtenancesc. Size Classificationd. Hazard Classificatione. Ownershipf. Operatorg. Purpose of Damh. Design and Construction Historyi. Normal Operational Procedures
- 1.3 Pertinent Data ............................ ... . 1-3a. Drainage Area
b. Discharge at Damsitec. Elevationsd. Reservoire. Storagef. Reservoir Surfaceg. Damh. Diversion and Regulatory Tunnel1 . Spillway
* j. Regulating Outlets
SECTION 2: ENGINEERING DATA
2.1 Design Data ................................. 2-1
2.2 Construction Data ............................. 2-1
2.3 OperationData................................ .2-1
vi
".-.-.-'..-•-. . ,,[,v' "... ... "- -. ""- . . -. ... " a.'.' ",''- .. - - " -."% . -',' .''-a."l" : " : " '" :
2.4 Evaluation of Data .......................... 2-1
SECTION 3: VISUAL INSPECTION
3.1 Findings .................................... 3-1
a. General" b. Dam
c. Appurtenant Structuresd. Reservoir Area
* e. Downstream Channel
3.2 Evaluation 2..................................3-2
SECTION 4: OPERATIONAL AND MAINTENANCE PROCEDURES
4.1 Operational Procedures .......................... 4-
a. Generalb. Description of Warning System in Effect
4.2 Maintenance Procedures ........................... 4--.
a. Generalb. Operating Facilities
4.3 Evaluation ...................................... 4-1
f D SECTION 5: EVALUATION OF HYDRAULIC/HYDROLOGIC FEATURES
5.1 General ..................................... 5-1
* 5.2 Design Data 1.................................5-1
* 5.3 Experience Data ............................. 5-1
5.4 Test Flood Analysis ............................. 5-1
5.5 Dam Failure Analysis ............................ 5-1
SECTION 6: EVALUATION OF STRUCTURAL STABILITY
6.1 VisualObservations............................. 6-1
6.2 Design and Construction Data ................... 6-1
6.3 Post Construction Changes ...................... 6-1
6.4 Seismic Stability ............................... 6-1
L vii
CC
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2 SECTION 7: ASSESSMENT, RECOMMENDATIONS & REMEDIALMEASURES
7.1 Dam Assessment ............................... 7-1
a. Condition
b. Adequacy of Informationc . Urgency
7.2 Recommendations .............................. 7-1
- 7.3 Remedial Measures ................................ 7-2
a. Operation and Maintenance Procedures
. . "7.4 Alternatives ................................ 7-2
APPENDICES
Page
APPENDIX A: INSPECTION CHECKLIST A-I to A-5
APPENDIX B: ENGINEERING DATA AND CORRESPONDENCE
Dam Plan, Profile and Sections Sheet B-IList of Existing Plans B-iSummary of Data and Correspondence B-2Data and Correspondence B-3 to B-12
APPENDIX C: DETAIL PHOTOGRAPHS
Photograph Location Plan Sheet C-1Photographs C-1 to C-3
F APPENDIX D: HYDRAULIC/HYDROLOGIC COMPUTATIONS
Drainage Area Map Sheet D-IComputations D-i to D-10Preliminary Guidance for EstimatingMaximum Probable Discnarges i to viii
APPENDIX E: INFORMATION AS CONTAINED IN THE E-INATIONAL INVENTORY OF DAMS
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PHASE I INSPECTION REPORT
LAUREL LAK" DAM
.1 -"SECTION I -PROJECT INFORMATION
1 . GENERAL
a. Authority - Public Law 92-367, August 8, 1972, autnorizedthe Secretary of the Army, through the Corps of Engineers, to
* initiate a National Program of Dam Inspection throughout the UnitedStates. The New England Division of the Corps of Engineers has beenassigned the responsibility of supervising the inspection of damswithin the New England Region. Cahn Engineers, Inc. has beenretained by the New England Division to inspect and report onselected dams in the State of Connecticut. Authorization andnotice to proceed were issued to Cahn Engineers, Inc. under aletter of April 14, 1980 from William E. Hodgson, Jr., Colonel,Corps of Engineers. Contract No. DACW 33-80-C-0052 has beenassigned by the Corps of Engineers for this work.
b. Purpose of Inspection Program - The purposes of the programare to:
1. Perform technical inspection and evaluation of non-federaldams to identify conditions requiring correction in atimely manner by non-federal interests.
2. Encourage and prepare the States to quickly initiateeffective dam inspection programs for non-federal dam.
3. To update, verify and complete the National Inventory ofDams.
c. Scope of Inspection Program - The scope of this Phase Iinspection report includes:
1. Gathering, reviewing and presenting all available data ascan be obtained from the owners, previous owners, the stateand other associated parties.
2. A field inspection of the facility detailing the visualcondition of the dam, embankments and appurtenantstructures.
3. Computations concerning the hydraulics and hydrology of thefacility and its relationship to the calculated floodthrough the existing spillway.
4. An assessment of the condition of the facility and cor-rective measures required.
| L- It should be noted that this report passes judgment only onthose factors of safety and stability which can be determined by avisual surface examination. The inspection is to identify those
- ". visually apparent features of the dam which evidence the need forcorrective action and/or further study and investigation.
I 1-1
'.
1.2 DESCRIPTION OF PROJECT
a. Location - The dam is located on an unnamed tributary toMorgan Brook (Connecticut River Basin) in a suburban area of thetown of New Hartford, County of Litchfield, State of Connecticut.
The dam is shown on the Winsted USGS Quadrangle Map havingcoordinates latitude N41 53.2! and longitude W73 01.1'.
Sb. Description of Dam and Appurtenances - The dam is 595 feetin length, 27 feet high and is of earth fill construction. Thespillway is located at the left end of the dam and the outlet is at
" the central portion of the embankment. All elevations are based onan assumed datum (spillway crest = 100.0) and are not N.G.V.D.elevations
- The top of the dam is typically 10 feet wide and has aminimum elevation of 103.3, which is 3.3 feet above the spillwaycrest. A well used footpath extends the length of the top of thedam. The upstream slope inclination is 1.5 horizontal to 1vertical and is entirely covered with weeds and tree saplings.Dumped riprap, extending below elevation 101 (approximately 2 feet
S".below the top of slope) stabilizes the slope below the water level.The downstream slope is also vegetated with weeds and small trees.The slope is inclined at approximately 1.5 horizontal to 1vertical.
The spillway is located to the far left end of the dam. Itis a 40 foot wide unlined sand and gravel channel extending alongthe left abutment to the original streambed. The spillway "crest"is at elevation 100.0, leaving approximatley 3 feet of freeboard.Except during very high discharge, water is released through asmaller (5+ feet wide) stream at the right side of the spillway (SeeSheet B-l, Photo 4). The spillway has no definite shape and noriprap protection at the crest or in the discharge channel.
The intake structure is located about 10 feet from theupstream slope of the dam, approximately 210 feet from the rightend. It consists of a 24 inch cast iron drop inlet pipe and a 30inch by 30 inch steel frame with wooden boards (Photo 5). At thepresent time there are five, 8 inch boards totaling 40 inches inheight. These boards are tongue and groove, and can be removed.The top of the upper-most board is approximately elevation 101.9and the overflow elevation with all boards removed is approximately98.6.
-* The outlet consists of a 24 inch concrete pipe, (invertelevation 76.3) located at the central portion of the toe of theembankment (Photo 3). The discharge channel appears to be the
. natural channel of the original stream. The size and configurationof the conduit between the inlet and outlet structures is assumedto be a 24 inch concrete pipe. There is no low-level outlet at thedam.
c. Size Classification - SMALL - The dam impounds 176 acre-feet of water with the lake level at the top of the dam, which atelevation 103.3, is 27 feet above the original streambed.According to the Recommended Guidelines a dam with this height andavailable storage capacity is classified as small in size.
1-2
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d. Hazard Classification - SIGNIFICANT - If the dam werebreached, there is potential for loss of less than a few lives at ahouse located 3,800 feet downstream and 4+ feet above thestreambed. Upon failure of the dam, this house would be inundatedfl by 1.4+ feet of water, Bsullak Road would be inundated by 3.4+ feetof water causing considerable damage, and a culvert and embankmentfor East-West Hill Road would be impacted farther downstream.
e. Ownership- Mountain Laurel Development Corp.Bishop Corner, West Hartford, Conn.Mr. Isadore Case, President
L (203) 242-77454 , ._ _ __ _
f. Operator - Same as owner, above.
g. Purpose of Dam - According to the owner, the dam was builtabout 1965 to provide a lake for a fish and game club. The present
- -owner acquired the property about 1973 to develop the lake front-- property for residential construction.
1.3 PERTINENT DATA
a. Drainage Area - 0.27 square miles of gently rolling,wooded, rural terrain (located in the Connecticut River Basin) withnew suburban development close to the lake.
b. Discharge at Damsite - Normal discharge is over the spill-way and through the ungated drop inlet. Elevations are based onassumed datum, spillway crest = 100.0.
1. Outlet Works (conduits):
24" cast iron drop inlet pipeto 24 inch concrete @ d/s in-vert El. 76.3: 70 cfs (water level to
top of dam)
2. Maximum flood @ damsite: Unknown
3. Ungated spillway capacity@ top of dam el. 103.3: 410 cfs
4. Ungated spillway capacity@ test flood el. 102.55: 240 cfs
5. Gated spillway capacity0; @ normal pool: N/A
6. Gated spillway capacity @test flood: N/A
7. Total spillway capacity @test flood el. 102.55: 240 cfs
8. Total project discharge @top of dam el. 103.3: 410 cfs
9. Total project discharge @"["..test flood el. 10 2. 55: 240 cfs
1-3
c. Elevations - (Elevations are not NGVD. All elevations
based on an assumed datum; spillway crest = 100.0)
1. Streambed at toe of dam: 76.3
2. Bottom of cutoff: N/A
3. Maximum tailwater: Unknown
4. Normal pool: 100.0
5. Full flood control pool: N/A
-i *..6. Spillway crest (ungated): 100.0
7. Design surcharge (original
design): Unknown
8. Top of dam: 103.3
9. Test flood surcharge: 102.55
d. Reservoir (Length in feet)
1. Normal pool: 1500 ft.
2. Flood control pool: N/A
* 3. Spillway crest pool: 1500 ft.
4. Top of dam: 1600 ft.
5. Test flood pool: 1550 ft.
P e. Storage (acre-feet)
1. Normal pool: 118 acre-ft.
2. Flood control pool: N/A
3. Spillway crest pool: 118 acre-ft.
4. Test flood pool: 160 acre-ft.
5. Top of dam: 176 acre-ft.
f. Reservoir Surface
1. Normal pool: 15 acres
2. Flood control pool: N/A
3. Spillway crest: 15 acres
U.
1-4
-7. -..
4. Test flood pool: 18 acres
5. Top of dam: 20 acres
g.Dam
1. Type: Barth embankment
. 22. Length: 595 ft.
3. Height: 27 ft.
4. Top width: 10 ft.
5. Side slopes: 1.5 H to 1 V Upstream
1.5 H to 1 V Downstream
6. Zoning: Not known
7. Impervious core: N/A
8. Cutoff: N/A
9. Grout curtain: N/A
- 10. Other: N/A
h. Diversion and Regulatory Tunnel-N/A
i. Spillway
1. Type: unlined earth channel
2. Length of weir: 40 ft.
3. Crest elevation: 100.0
4. Gates: N/A
5. U/S Channel: sand and gravel,gently sloping
6. D/S Channel: Highly vegetated,
boulder filled channel
7. General: Non-structural
j. Regulating Outlets - The only outlet is a 24 inch dropinlet, which discharges via a 24 inch concrete pipe outlettingat the toe of the downstream slope.
1. Invert: 76.3 downstream98.6+ upstream (no boards)101.9+ upstream(five 8 inch boards)
S-2. Size: 24" conduit
'" i1-5
•75
3. Description: 24 inch cast irondrop inlet pipeto concrete pipethrough embankment
4. Control Mechanism: 30" x 30" steelframe with removableboards. Boardsare five, 8 inch
"-'. tongue and grooveboards totaling40 inches high.
g. .1--
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I I2 1-6
-V V.7
SECTION 2: ENGINEERING DATA
2.1 DESIGN DATA
No design data or design plans are available for the originaldesign of the dam.
2.2 CONSTRUCTION DATA
There is no data or construction inspection reports availablefor the original construction of the dam.
. 2.3 OPERATION DATA
No formal operation records are known to exist nor are lake- level readings known to be taken on any regular basis. The only
-. available information is correspondence between the State ofConnecticut and the owner (Mountain Laurel Development Corp.) andan inspection report done by S.E. Minor and Company, CivilEngineers, in 1975. These are presented in Appendix B.
2.4 EVALUATION
Existing data was provided by the State of Connecticut and
verbally by the owner, who also made the premises available forvisual inspection. The limited amount of detailed engineering dataavailable was generally inadequate to perform an in-depth
Sassessment of the dam, therefore, the assessment of this dam mustbe based on visual inspection, performance history, hydrauliccomputations of spillway capacity and approximate hydrologicjudgements. A comparison of record data and visual observationsreveals no significant discrepancies in the record data.
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SECTION 3: VISUAL INSPECTION
3.1 FINDINGS
a. General - Based upon visual inspections performed on May 9and June 3, 1980, the dam is considered to be in poor condition.
* * The inspections revealed areas requiring maintenance, monitoringand repair. The reservoir level was at elevation 100.2 with a smallamount of flow over the spillway.
b. Dam
Top of Dam - The top of dam is covered with brush andsmall trees except for a narrow, well worn, footpath extending theentire length of the dam. The vegetation consisted mostly of treesaplings 10-12 feet tall and 1-2 inches maximum diameter (Photos 1and 2, Overview). No washouts, sloughing or depressions were notedon the crest.
..- . Upstream Slope - The upstream slope is also heavilyvegetated and has dumped riprap present below elevation 101+ (Photo1). No sloughing, washouts, or depressions were noted althoughsome erosion from trespassing is present where paths lead to the
- edge of water (Photo 6). The riprap is in fair condition with someareas of displacement.
Downstream Slope - The downstream slope has a heavyU vegetative cover of small trees and brush (Photo 3) with a footpath
extending from the top of the dam to the toe at the central portionof the slope. Seepage totalling more than 20 gpm was noted allalong the toe of the dam with the most seepage occuring at thecentral portion of the dam (Photo 8). A large swampy area withseveral pools of stagnant water was observed along the toe of thedam in the same area as the seeps (Photo 7). Some "holes" at theright end of the dowstream slope were observed about 8 feet belowthe top of dam (Photo 9). These areas apparantly are not related tothe seepage and appear to have been dug out to approximately 2 feetin depth and 3-4 feet in diameter to remove some boulders or treestumps.
Spillway - The spillway is an unlined channel ofirregular shape extending along the left abutment. The channel isfilled with various debris and heavy vegetation (Photo 4). Waterdischarges through a smaller "natural" stream at the right side ofthe channel. Some small mounds of earth have been placed from the
ezO left side of the channel to this stream, allowing water over theearth mounds only during times of high discharge (See Sheet B-l)No riprap was observed at any part of the spillway. The approachchannel is gently sloped, sand and gravel material.
A
__ 3-1
,w..-, - . -.. ,. _ - "5 . ...- _..- * . . .. . .
c. Appurtenant Structures
Intake Structure - The intake :tructuro is a 24 inch castiron drop inlet pipe and a steel framed structure with wooden5 boards to control the lake level. (Photo 5). It is locatedapproximately 10 feet upstream from the top of the slope. Some woodand boulders were noted at the base of the drop inlet. No low-leveloutlet for lowering the pond was found during the inspection.
Outlet Structure - The outlet structure is a 24 inchconcrete pipe located at the toe of the downstream slope (Photo 3).There was flow from the outlet at the time of the inspection.
d. Reservoir Area - The area surrounding the reservoir isrural, rolling and wooded. Low density (+ 1-2 acre) lake frontresidential building lots are being sold and developed aroundLaurel Lake.
e. Downstream Channel - The downstream portion of the outletchannel is the natural channel of the original streambed. Debris
. and overhanging trees were observed during the inspection (Photo10).
3.2 EVALUATION
Based upon the visual inspection, the project is assessed asbeing in poor condition. The following features which couldinfluence the future condition and/or stability of the dam were
3 identified.
1. Erosion areas with riprap displacement on the upstreamslope caused by access paths, could present stabilityproblems should the dam be overtopped.
2. Dense, immature, woody vegetation covering the entire damwill result in root penetration which will presentstability problems by providing seepage paths along rootsystems and weakening the embankment should trees blow overduring strong winds.
3. Seepage along the downstream slope could result in daminstability if a program to study and monitor seepage isnot implemented.
4. The unstabilized, earthen spillway does not have adequateprotection to prevent erosion during flows which the
4 spillway is expected to experience.
5. There is no access bridge to the drop inlet, making it- "impossible to reach the inlet during high lake levels. The
present system of removing boards to increase dischargethrough the drop inlet would be quite difficult during
.g 4 periods when water is flowing over the boards.
6. There is no low-level outlet or means to draw down the lakein case of emergencies at the dam.
4 3-2
. . ..-" ,". .. .: : ',-,. ' . ..- ' ... ' - - ".."..".. ...... ..- ". .. ... ... .. -. ' '. ' ... .- .*." .. .-
SECTION 4: OPERATIONAL AND MAINTENANCE PROCEDURES
4.1 OPERATIONAL PROCEDURES
a. General - There are no formal operating procedures known to
exist. No lake level readings are taken, nor is the drop inletadjusted to vary the flows or lake level. The dam was inspected by
S.E. Minor and Company, Incorporated in 1975.
b. Description of Any Formal Warning System in Effect -Noformal warning system is in effect.
4.2 MAINTENANCE PROCEDURES
a. General - There is no formal maintenance program for thedam or operating facilities. The owners reported that they haverecently contracted to have the vegetation cut and the spillway
--. riprapped, however no evidence of repair was found at theinspection. No repairs are known to have been done after the 1975inspeciton by S.E. Minor and Company, Inc.
b. Operating Facilities - No maintenance is known to be
performed for the drop inlet structure and outlet facilities.
4.3 EVALUATION
The operation and maintenance procedures are poor. A formalprogram of operation and maintenance procedures should beimplemented by the owner, including documentation to provide
' complete records for future reference. Also, a formal warningsystem should be developed and implemented within the time periodindicated in Section 7.1c. Remedial operation and maintenance
-" =recommendations are presented in Section 7.
4-1
N. N %J
" -. . . ... . . .7 V " " 7 "- "
SECTION 5: EVALUATION OF HYDRAULIC/HYDROLOGIC FEATURES
5.1 GENERAL
The watershed is 0.27 sq. mi. of rolling, undeveloped, woodedterrain, which is located in the Connecticut River Basin. Somehousing developments exist in the eastern section of the watershedand a new housing development is currently under construction inthe same general area. The maximum imioundment to the top of dam is
L estimated to be 176 Ac.Ft and estimated storage below spillwaycrest is 118 Ac.Ft based on the assumption that normal lakeelevation is the same as the spillway crest elevation. The dam isclassified as being small in size having a significant hazardclassification.
N.G.V.D. elevations were estimated from the Winsted U.S.G.S.Quadrangle map and were used for the computations in Appendix D soas to facilitate downstream flood routing computations. Allelevations in this section have been converted to the assumed datumelevation to maintain unity in the test portion of this report. Theassumed datum is based on the spillway crest equal to elevation
- 100.0.
5.2 DESIGN DATA
No hydraulic or hydrologic design data are available for thisdam.
5.3 EXPERIENCE DATA
Serious flooding downstream of the dam more than 10 years agowas reported, and apparently a road and driveway of one house wereinundated with flood water. No other details regarding thisreported problem could be found. The maximum previous discharge atthis dam is unknown.
5.4 TEST FLOOD ANALYSIS
The test flood for this significant hazard, small size dam isin the 100 year to half Probable Maximum Flood (h PMF) range.
' .. Selecting PMF as test flood based on the involved downstream riskpotential, the Corps of Engineers Recommended Guidelines fordrainage areas below 2 sq. miles with rolling terrain yields a peakinflow of 350 CFS. The peak outflow is estimated to be 240 CFS withthe maximum stage in the lake at 102.55, which is 0.75 feet belowthe top of the dam. Thus, the dam is not expected to overtop fortest flood conditions. The storage routing is also performed for a100 year peak inflow of 200 CFS and the peak outflow is estimated tobe 112 CFS with the maximum stage in the Lake at 101.86. Thespillway capacity with pool at top of dam is estimated to be 410 CFSwhich is greater than 100% of the routed test flood outflow. The
* outlet from the dam consists of a 24" concrete pipe with a dropinlet and its discharge capacity being small, is not included inthe analysis.
5-1
-. .. - .- - " ..- '.-. . . . • -.- ~ ... ..-. ,.-.. -. -..-..- -... -. .-.--.- .~- . . ., -. , . . . -. .
5.5 DAM FAILURE ANALYSIS
Utilizing the Corps of Engineers April 1978 "Rule of Thumb5 Guidance for Estimating Downstream Failure Hydrographs," the peak* failure outflow due to dam breach is estimated to be 36,000 CFS with
an estimated flood depth of 12Ft. immediately downstream of thedam.
The flood routing was performed for peak failure outflow withmaximum pool at test flood outflow elevation of 102.55. Theprefailure flow in the Brook is estimated to be 240 CFS and afterfailure the flood stage is estimated to increase by 2.9 Ft. at the
. .initial impact area.
The estimated peak flow rates and peak flood depths at foursections downstream of the dam resulting from a dam failure are:
D/S Section Flow Flood Depth Velocity(Ft.from Dam) (CFS) (Ft) (FPS)
At Dam 36,000 12 -- 2200 19,500 10.8 4.6
2600 12,000 8.3 3.62900 7,700 7.7 3.03450 3,700 5.4 2.5
A portion of Bsullak Road (3800 feet downstream) adjacent to alarge swamp and one house just north of Bsullak Road would be
-. damaged due to dam failure. The peak flow rate at this impact area
is estimated to be 3,700+ CFS with a flood depth of 5.4+ Ft. Thus,the house, located 4+ Ft. above the edge of the swamp, is likely tobe inundated with 1.4+ Ft. of flood water, providing the potentialfor the loss of less than a few lives. The road would be inundatedwith 3.4+ Ft. of flood water, causing substantial damage to theculvert and embankment. Further downstream, a culvert on East-WestHill Road could also be impacted because of inadequate capacity.
Based upon the hydraulic and hydrologic analysis, the dam has asignificant hazard classification.
.-
-5-
.......................................
O ......................................
SECTION 6: EVALUATION OF STRUCTURAL STABILITY
6.1 VISUAL OBSERVATIONS
U. The dam is an earth embankment with an ungated 24 inch dropinlet and an unlined spillway. The dam is 27 feet high, 10 feetwide at the top and has an upstream slope of 1.5 horizontal to 1vertical and a downstream slope of 1.5 horizontal to 1 vertical.There is dumped riprap protection on the upstream slope with weedsand small trees on the remaining portion. There were numerousseeps observed along the toe of the dam (over 20 gpm total) re-sulting in soggy areas with stagnant pools of water in some placesalong the toe. Several depression areas or "holes" approximately 2feet deep and 3 feet wide were observed on the downstream slope nearthe right abutment. These are not considered to be seepage relatedbut appear to have been excavated or dug out for some unknownpurpose. The spillway has no lining, riprap or proper "designshape". The protective cover consists of weeds and small trees. Nolow-level outlet for draining the lake exists at the dam.
The dam was constructed around 1965 with no construction permitor regulation on construction procedures. There are no plansavailable, nor is there any evidence that the dam was designed by anengineer. No correspondence concerning construction inspectionscould be found and the inspection report by S.E. Minor and Companyin 1975 indicates that there is no seepage although our inspectionson May 9 and June 3, 1980 revealed substantial seepage along thetoe.
The above considerations, the problems revealed at theinspections and the relatively young age of the dam, indicate thata geotechnical investigation to determine the embankment andfoundation conditions should be performed, as well as performing
-r maintenance and repair to the embankment and appurtenances.
6.2 DESIGN AND CONSTRUCTION DATA
Design or constru ion data is not available, and therefor anin-depth assessment of P structural stability of the dam cannotbe performed.
6.3 POST CONSTRUCTION CH,
There is no record of post construction changes made since thedam was built about 1965.
0 6.4 SEISMIC STABILITY
The dam is in Seismic Zone 1 and according to the Army Corps ofEngineers Recommended Guidelines, need not be evaluated forstructural stability.
6-1
L7.7-7 ,
SECTION 7: ASSESSMENT, RECOMMENDATIONS AND REMEDIAL MEASURES
3 7.1 DAM ASSESSMENT
a. Condition - Based upon the visual inspection of the siteand past performance, the dam appears to be in poor condition.There are items requiring repair such as irregularities on thedownstream slope, the drop inlet and its operating mechanism andthe spillway channel. There are also items requiring maintenanceand monitoring such as displaced riprap, erosion from trespassingand seepage through the embankment.
Based upon the "Preliminary Guidance for Estimating Maximum" - Probable Discharge", dated March 1978, and hydraulic/hydrologic
computations, peak inflow to the lake at the h PMF is 350 cfs andpeak outflow is 240 cfs with the dam maintaining 0.75 feet offreeboard. The spillway capacity to the top of the dam (elevation103.3) is 410 cfs, which is greater than 100% of the routed testflood outflow.
b. Adequacy of Information - The information available is suchthat an assessment of the condition and stability of the dam must bebased solely on visual inspection, past performance of the dam, andsound engineering judgement.
c. Urgency - It is recommended that all seepage beinvestigated immediately upon the owners' receipt of this reportand that other recommendations presented in Section 7.2 and 7.3 beimplemented within 1 year of the owner's receipt of this report.
7.2 RECOMMENDATIONS
-r It is recommended that further studies be made by registered*professional engineer qualified in dam design and inspection
pertaining to the following items. Recommendations should be madeby the engineer and implemented by the owner.
1. Immediately upon receipt of this report, the owner shouldretain a professional engineer for development of a programto investigate the origin and significance of seepageemanating along the toe of the embankment.
2. Conduct a detailed topographic survey of the dam andprepare "as-built" drawings for future reference.
3. Perform a geotechnical investigation to determine theembankment and foundaiton conditions as related to existingseepage, the geometry of the embankment and the damstability.
*4 4. A spillway section and profile should be developed whichwill provide a design shape and protection suitable formaximum flows expected through this spillway.
% '7-1
"J '
* 5. A means of drawing down the lake in case of emergencies at
the dam should be provided.
°. 6. Another system to increase discharge into the drop inletother than the present method of removing boards, and anaccess ramp to the inlet structure, should be provided.
7. Inspection of the 24 inch concrete outlet pipe for possibleleakage into the pipe from the embankment.
8. Removal of large trees from embankment, backfill withsuitable material and placement of proper slope protection.
-7.3 REMEDIAL MEASURES
a. Operation and Maintenance Procedures - The followingmeasures should be undertaken within the time period indicated inSection 7.1c, and continued on a regular basis.
1. Round-the-clock surveillance should be provided by the- c owner during periods of heavy precipitation and high
project discharge. The owner should develop andimplement an emergency action plan as well as adownstream warning system in case of emergencies at thedam.
2. A, formal program of operation and maintenance pro-cedures should be instituted and fully documented toprovide accurate records for future reference. The
f maintenance procedures should include documentedmonthly inspections by the owner or owner
*:" *representative.
3. A comprehensive program of inspection by a registered
professional engineer qualified in dam design andr inspection should be instituted on a biennial basis.
4. Small trees and brush should be cut and removed fromthe dam.
' 5. Displaced riprap along the upstream slope should be" "repaired.
-' 6. Areas on upstream slope eroded by trespassing should be
regraded and proper slope protection placed.
7. The irregularities at the right end of the downstream0. slope should be backfilled and proper protection
placed.
S8. Remove all debris and clear trees and brush from thespillway and spillway discharge channel.
7.4 ALTERNATIVES
This study has identified no practical alternatives to the
above recommendations.
7-2
= - .~ *~* ~ '~-
A- %
APPENiDIX A
INSPECTION CHECKLIST
0.
VISUAL INSPECTION CHECK LIST
PARTY ORGANIZATION
PROJECT r k /k hOnn DATE: Ala
TIME: x27ThW - I/. PA/
WEATHER: -S rn\ - 7o'F
• ~w.s. ELEV. I ,!U.S.
___________U.S.
PARTY: INITIALS: DISCIPLINE:
1 k. r Rl. ,,JI (L2n- 4- k,6m/2. ')jo, Pe-'ovky Ap #--Z 6 Akhial
3.~ iU&J/ Ac('hn 660kcAhica)
4. Mu.,/. A rw T-,.." .- 5. J:effr e, O, Rrr,,,, (2"8 A n. GOe,-,. ,-a)
6. T Ka nwa. "a TA a.,A- survC4
PROJECT FEATURE INSPECTED BY REMARKS
1. 6mbankwmei+PMZAC U7-
2. p" li T, &4, R&4 A-3
3. PM~c ~4~. P)., QT( AIA MP.JTR A- 4
4. f4e+ ?M 1, Z& , M. PJR Tk A --i
5.
6.
7.
8.
9.
10.
11.
S@' 12.
'-" :-i' I-' ,
a 'p Izaa.. .v. ~ - .- *
PERIODIC INSPECTION CHECK LIST
PROJECT 4a.ur/ A, ,O
PROJECT FEATURE -y
AREA EVALUATED CONDITION
*DAM EMBANKMENT
Crest Elevation /03,3
Current Pool Elevation /00 .
Maximum Impoundment to Date Unknoch
Surface Cracks
• iPavement Condition Alone- o~lse ved
Movement or Settlement of Crest
.. Lateral Movement
Vertical Alignment A o S ood
Horizontal Alignment
[Condition at Abutment and at Concretei' '... Structures '
* Indications of Movement of Structural ,1Omi oLb3 (Vd
Items on Slopes
Trespassing on Slopes y s- .o+ c.'-""
Sloughing or Erosion of Slopes or fS - d° ' S :0).- .lAbutments r )sre o ;f pa 4 ,S
p.
Rock Slope Protection-Riprap Failure. - 3ie rO4. dt;pc,
Unusual Movement or Cracking at or /"" " .'.' .Near Toes"
Unusual Embankment or Downstream - o > 2O tJp',ckr
Seepage on d)2 S Op-
Piping or Boils
Foundation Drainage Features r v
Toe Drains
Instrumentation System
:- A-A
-.-./ . .... .. ._... . .. ... ...-. . -.. . . .. .. ... .... , .. ... ... .. ....... . . .... . . .. . ... ... . .... . .. .. ., .... ... .... ... . .. ... ... . . . . . .
PERIODIC INSPECTION CHECK LIST Pg
PROJECT FEATUREV. Ap /gJ - -- BY P/1,. J9.-A , I Rh T
- . AREA EVALUATED CONDITION
• . CUTLET WORKS-SPILLWAY WEIR, APPROACH
* AND DISCHARGE CHANNELS
a) Approach Channel
General Condition , 0.d
Loose Rock Overhanging Channel 0A-, .m e-o"s, v
, , , Trees Overhanging Channel
Floor of Approach Channel S,, r4 jroCI Vr- e 4 s)op,..
b) Weir and Training Walls
* ., General Condition of Concrete
Rust or Staining
* Spalling NAAny Visible Reinforcing
Any Seepage or Efflorescence
Drain Holes
C) Discharge Channel
General Condition "
F. Loose Rock Overhanging Channel
Trees Overhanging Channel
Floor of Channel poor- debris -tt-e on
Other Obstructions N/A
.-lo
''-.'.., ., ."......... . . ,. ..... ;.,.e "."...."""""...... ".......... .... '.
PERIODIC INSPECTION CHECK LIST
Page - A
PROJECT',',.L" "" DATF' , ' I 1 -"
PROJECT FEATUR ~ ~ J flAh~J(,.) "A t
AREA EVALUATED CONDITION
OUTLET WORKS-INTAKE CHANNEL AND /(Q -jin- w/ wl oJ'. J*eINTAKE STRUCTURE -ene ra)) } 0O( CoSiJ
a) Approach Channel
Slope Conditions
Bottom Conditions
Rock Slides or Falls
-Log BoM
Debris
Condition of Concrete Lining
U Drains or Weep Holes
b) Intake Structure
Condition of Concrete /1
Stop Logs and Slots warhrr e roa s,-...~i ,,poor" _ ." cY, 4kk
jfl O•
*j
"-°. 44
"°
k,,_, ,.,.' -. ,..,, ...,.- -~~~~~~~~....... .. " v-..... .-........ ......... :.................. , ..... :...... ,,......o:. ........ .. ..
PERIODIC INSPECTION CHECK LISTI Page 1PR{OJECT /-P'/ Iit
~~ I PROJECT FEATUJRE F
pBY
AREA EVALUATED CONDITION
OUTlET WORKS-OUTLET STRUCTURE AMDOUTLET CHANNEL
General Condition of Concrete
Rust or Staining IA
Spal ling
Erosion or Cavitation
Visible Reinforcing
-v ~ ~Any Seepage or Eff lorescence K M
Codto atJit
* IDrain Holes
Channel
* - Loose Rock or Trees Overhanging 7VS ~/ c* r channel
*Condition of Discharge Channel 4rire ,I f (,anne)
APPENDIX B
ENGINEERING DATA AND CORRESPONDENCE
7,.
-LAUREL LAKE -
SHORELiPE
STRUCTURE NI -'EDGE 05 WATER
__________TOP OF OW~ F[ 103 3
( NI -243 WPIPE,N OUTLT
-- SEEPAGEJ. -~ -SEEPAGE -- - -
EROSION AREA~ 77
STANDING WATER ' -- L~.'.f---
SEER .i STREAMPLAN WET AREA
30 0 30 60
TOP, OF DAME, 03 3
-SEEPS -- 'SEEPS -
24" rONC PIPEINV 76i3
EL E VAT ION_* 3 so - - o HNR]:')NIAL
10 D 10 20
( 'I0 -- 0 0 VERICA
LHRE___E
9t
Sk-CHA~hI\
-2-: /RIPRAP- -
) STREAM
-- . . . /3 0 " 1 3 0 , D R O P IN 1- E -".'' -- .T,') OF DAM / STOP-PLA/is5/ 8
- LCST EL" 98PE
,~~~~O . S LIO 2 ... ...
NOE
DM-- IT SEHOW IA- A
24"/O CASTCTRA rNPIP
II
SECTION A-A ASSUEO__ __ _ __ _ .- __ __ _OF 24"c
NOTES
OIFIMUM EVATKO 000 ISPECTN OF TIE DAMNDENSION G S-I N ARE
N/OR STRLTURAL AMEA
2 N NV P ELEVAT SN E
". --........... ... . ..... • .. ...._-.- . 1 '-- OR LAKE SURFA E ALLPAN MRG ,ASE O N
EQUJAL To tlO 0P -SR AM
"; - " .," APPRI(MATE TOE
I " --OF DAM
CAIIN ENGINEERS IN0
IU
-, Wit L tNCFORD.,CONNELCT CUI
FNG NEER
NATIONAL PROGRAM 0!
PLAN EL~
LAUREL-' TR- MORGAN 8ROCK
-" ." - .--- -- -. -_ 1 -
CRS ELA 96 L24RE C CiINVER
SECTION \- ASSME LOCTIO
;-" ,,- / /
OF= o.COC PIPE
" :'i.7 //
S'" 3O" 30" AP NLE T
OR" LAK SURFACT ALLg EL TSSHW NTI
-. EP
5/9EN IN R T HAM . . . ...
~I - -
,..'.. iI - L.6
LSECTON A-A EASSUdD LOCATION
C0 I0 2C'
NOTES"- EO-, 'H;tLW .. I THIS PLAN WAS CO0PFLED FRO H IN'ER
.- '1 ', VATI 1000 tNSPECTOd (Y THE DAM DATED MAY 9, 1980. -D M NSONS S)40WN ARE ARPROX,VATE NOT A.IL TOPOGRAPHC
; ANDEO ST RtCT IWAL PEATRS ARE NECESSARLY IDENTIFIED
' = W -- 2 NCK RGVD ELEVAIONS WERE AMILABLE FOR THE DAM
- -- OR I.AKE SURPACE. ALL ELE .TIOS SHOWN ON THIS.- - ---.- P1-AN ARE BASED CtN AN ASSUMPED SPII.LWAY ELEATION
, EOJL. TO I00 0
---. /"" / " /
• /
!CAHN ENGINEERS I C, IIl S ARMY ENGINEER DIV NEW ENGL4NDi*A .WILINGrORO,CONtIECTICJTl CORS O N' NFRS
•"""ENGINEER WALTNAN, MASi
NATIONAL PROGRAM OF I PECtICN OF NON-1E.D DAMS
%#0PLAN ELEVATIUN AN() SECTION
..- LAUREL LAKE DAM
_, ,TR- MORGAN SPOOK NEW IIARTFORD, CT
__...______.__________,_ o ~ ,,,
%" N ~ 1 IfL%
LAUREL LAKE DAM
EXISTING PLANS
No information is available
9B-
I<
all CI 4 I CO ,M I
'-4
0 d-
4 C 0(a ' 0 0 C
(a $4 $4
I-i d4 0 00 0 4-'-4 0- C1
>1 44 ~ 4-i 44 . 4 0&4. 0 u 0 -41..-
E-4 0 41 413C 4J M 4-J
LI~r wa(l'~- d
Ul :s Ej c Rm~~~4 C0 0i.- 0 ic12 En 13 Z~ -0
O0 0 i
0 0) 0m > ~W diO to n
4J r= U iL 0 C
$4 di Em -
E-41 %4 0'u :4- *3r 3 0 .0 .0 -
*0 u Uo tmn~ 0) .---- d iiad di rC
0i to~f t-) .4 to Caa)- 0 04-i -- I4 LC4
>4 XHdi 04 - 44Q 04d U.
* U)
--4 0-S
Li4 >4 H.->1 i 'd
'U4. La am
(a 0 % i- 4d
413- ~ 0 0Li=a * H w 0m
~j- 0 d ) - 0 ('Di04 In rid
r- It-
rii 4 4; -I *44 4J3 .4 *LA
E'I ar- or- M r- 0. - oi -
B- 2
4. No. ________________ AI ESOURCES CO-tSSION' 4 1SPRIINO AI i
Inventore, IIVENTORY DATA
tt.,4JzL CT- ,1 -
'Name of Dam or Pond /4/ 'e /j
Code No. r 2 / ' " ; I/C.
Nearest Street Location ' s e l
44Town ~
)x; AA14-USGS Quad, 14 ,'
Name of Stream .
d s .' s .. ...Address ) i, .o
0d14- A/Il* . . . . , ,,
-".., Pond Used For
Dimensions of Pond: Wiidth 5WLength /a OZ Area~~
Total Length of Dam <L I Length of Spillway, tawev
Location of Spillway A/ A toreHeight of Pond Abovstre __
Height of Embankment Above Spillway 4. -
Type of Spillway Construction _C_ __e
Type of Dike Construction
Downstream Conditions - 4 -
4. Summary of File Data 41, ey-.
Remarks
K )oud Failure Cause Damage? Class
- -"-3
. *' o . . . o- . . . . o. o . . • . . . o* . i
August 26, 1971
Mountain Laurel Development Corp.820 Park AvenueBloomfield, Connecticut
Attn: Mr. Isadore Case
... * "Re: Laurel Lake Dam(Lake Lausanne Dam)New Hartford
Dear Mr. Case:
S- According to the records in this office, the dam on LaurelLake (also referred to as Lake Lausanne) in New Hartford is underyour ownership.
The Water Resources Commission under the General Statutesof the State, a copy of which is enclosed, has jurisdiction overall dams, "--which by breaking away or otherwise might endanger
* life or property--". Since this dam could cause damage in theevent of failure it is under the jurisdiction of the Water Re-
. sources Commission.
The 1956 U.S. Geological Survey map does not indicate alake at this location but when these maps were photo-revisedin 1969, this lake was evident. According to the assessor's
office in the Town of New Hartford, this property was formerlyowned by a Mr. Sherwood Wilson and the dam was apparently built
., i.. some 10 or 15 years ago while under his ownership. We havesearched our files and can find no record of a ConstructionPermit being issued for this dam as required under General Statute25-112.
As the present owner of the dam, you are responsibile forits safety.
We request that you submit as-designed and built plansfor this dam, prepared by an engineer registered in the Stateof Connecticut and bearing his seal and signature. We also re-
S. quest that your engineer submit a report on the overall safety
B-4
.U - * -. - *
Mr. Isadore Case Page 2I - August 26, 1971
of the structure including an analysis of the capacity of thefacilities to pass the design run-off without overtopping. Thisdam was inspected by a member of our staff on August 6, 1971,and general seepage was emerging from the ground along the toeof the dam. Your engineer should investigate the influence ofthis seepage on the safety of the dam. It was noted that thestructure was covered with brush and small trees and these shouldbe cut down and removed immediately, with special attention givento the clearing of the emergency spillay on the west end of thedam, to permit the free flow of water at flood time.
It is requested that you advise the Commission in writingprior to September 15, 1971, as to your intentions in submittingengineering plans and report as mentioned above.
Very truly yours,
3 John J. CurreyDirector
JJC:WHO:ljg
Enclosure
B-5
0'"2-
* rk,. n- P~k.~~~...*
FI VA4 I I I Em -
CIRM-txaUl ICK-Fy r
(ghrra'aan I'visur AftOAN1AlrS
SeptLmnbcr 17, 1971
Mr. J. Curry
State of CoI)neCtikcutWater Resources Dept.Hartford, Conn.
Re: Mt. Laurel Development Corp.
Lake L,-u,-;anuic
Miounta in Laure I IDc'elopmnt -Corpo-a. ni t s n.< i M'ar ton fine Asso.
EnF in'ci-s to subai- t as d si g:ikJ, aiWa ; bti .t 0 i! and a reportI cvn the
overall structur,: rf t* v damn.
Thijs work is Lc, be~ doe imniediat-cly.
Very Vyily your..,
M 11) ds Mor ton L. 4n-iyar
K STATE VIATFR WSU RrC::S
SEP 2 31371
% B-6
OP%
" -A/ I
INTERDEPAI RTIZENI MAILI 17, 1971.- 0 I .,. A V I . . . .
~File-"" ... . ....___--_ -,,',K LC ,; . .. .. .. . .. . ..... ......
I ^I I,
* L-I.J..r W i ia II 0' , 1rien, 111, ClviI Ennii.f erl ;Vatr 1 ci,'uurce. Co.i'-,ioln
5 "-' l ~ Laurel Lake iD,-m (L.ausanin D.1,), tl9I.w -..Yt_ _i__
On September 17, 1971, the undert.igned called arid spoke to
Mr. Isadore Case about the subject dam.
lie had received our letter of August 26, 1971 and had de-
termined that the original plans were not prepared by an englr,et.
I told him this matter would probably be brought before the Ccr':ajs-
sion at its September 20, 1971 meeting for whateve" action they
may wish to take.
/'., r'//.C " .
-- - I ---
• / Civil Lrk': r. ":r
"E I
'.'
- - .... I
.%.
--- -. B-7
:- - .J
:-F-
August 15, 1972
U Mountain Laurel Development Corp.c/o Mr. Morton DanseyarBishops CornerWest Hartford, Connecticut
* Attention: Mr. Morton Danseyar
Re: Laurel Lake Dam(Lake Lausanne Dam)New Hartford
Gentlemen:
On September 23, 1972 an order was issued to you bythe Water Resources Commission to submit an engineeringreport and findings on the safety of the dam by December 31,1971.
You have informed us that the firm of Morton FineAssociates has been retained to submit such a report to us.
S,On June 13, 1972 we again wrote to you requesting- assurances that an engineering report would be forthcoming.
Our records indicate no reply to this letter. Please adviseus by return mail as to when we may expect to receive yourengineer's report and findings so that more formal actionr will not be required.
Very truly yours,
Stephen C. Thomson, Director.'.* 0-". Water and Related Resources
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S. E. MINOR & CO.. INC.
CIVIL ENGINEERS
161 MASON SIREIET
G-LE'NW) .. CONNECTICUT OU830
August 8, 1975
State of Connecticut'. Department of Environmental Protection
State Office Building- Hartford, Connecticut 06115
Attention: Mr. Victor F. Galgowski
Superintendent of Dam MaintenanceWater and Related Resources
Re: Laurel Lake Dam(known as L..ke Luzan)New Hartford, Connecticut
Dear Mr. Galgowski:
In accordance with your request, we have examined the subject dam in orderto ascertain its structural soundness and stability. Prior to our visit
to the site, we went to the Town Hall offices and attempted to obtain anystructural drawings of the subject Installation. We were advised that no
plans were on file and that the Town officials had no knowledge whatsoeverof the construction of the dam.
Upon visiting the site, which was located cn a tributary to Morgan Brook in
the northwest section of town, 4e found the dam to ban earth withapproximately four feet of freeboard and the top to be approximately tenfeet wide. 'T1e slope on the back of the elam waz L.)pro,:imatvly one on
rthree and had loose riprap of cobbles and botilders. The face of the dam
is sloped at approximately one on one and drops in tie. vicinity of 30 feetvertically. The face of the dam is heavily overgrvwn and upon inspectionof same we found no evidence of leaks, fissures, or boils. Tho blow-offchamber consists of approximately a 3' by 3' squar,. overfall which is pipedoff to the stream below. The total length of the dam is about 575 feet, and
rthe blow-off chamber is located approximately in the center and about ten
- et back from the water linc.
It is our considered opinion that the dam is structurally sound and not in
danger of overtopping. We feel that said dam with normal maintenance willservice for many years.
Respectfully submitted,
S. E. MINOR & CO., INC.
Edward F. Ahnemnan, Jr., P.E.Chief ng ilit', r
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APPENDIX C
DETAIL PHOTOGRAPHS
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Photo 1I Upstream slope from left shore, (May, 1980).
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US AMY NGINER IV. EW NG LND AT Lure Lak Da
CORP OF NGINERSIONA PRORAM F IR-Moaan rooMASSo
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Photo 4 - Unlined spillway at left end of dam. Overflow
. occurs at small stream at right side of spillway,(May, 1980).
• ,' U S R M Y E N G I E E R D IV .N E WL a u r e l L a k e D a mUS ARYEGNE IV-E NLN NATIONAL PROGRAM OFTRoraBokCORPS OF ENGINEERS RMraBok
WALTHAM , MASS
- INSPECTION OF New Hartford, CT" " ~~CAHN ENGINEERS INC. C#775K, WALLINGFORD. CONN. NO-FED. DAMS C#2 75K
ENGINEERNON DATE ept. 980 PAGE C-2- - -
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oto -Drop in et 2' x 2' with metal frame, woodVslats and pipe for control mechanism, (May, 1980).
Photo 6 -Area of erosion from trespassing on upstreamslope, (May, 1980).
US ARMY ENGINEER DIV. NEW ENGADNTO LPR RM Laurel Lake Damo L ~CORPS OF ENGINEERS LADNTO LPRG MOFTR-Morgan BrookWLHMMASS.
___________________* NSPETIO OF New Hartford, CTCAHN ENGINEERS INC. DAMSCIO O
% WALLINGFORD, CONN. NO-E.CE* 27 785 KE C-
@2.18 PC
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-:-Photo 7 -Wet area at central portion of the toe of theembankment, (May, 1980).
Photo 8 -Seepage at central portion of embankment, flowrate is approximately 5 gpin, (May, 1980).
Laurel Lake DamUS ARMY ENGINEER DIV. NEW ENGLANDNAOALP GRMO -ora Bok
*CORPS OFENIERNAINLPORMO RMraBokWALTHAM * MASS,
-~ .INSPECTION OF New Hartford, CT
CAHN ENGINEERS INC. c*7 75KW ELLINEERO ONd NON- FED. DAMS JDATESe t.1980 PAGE C-4
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APPENDIX D
HYDRAULICS/HYDROLOGIC COMPUTATIONS
7/ -- 77
A PPROXIMATE LIMITS O F. I <i\-_
DAM FAILURE OUTFL OW
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PROJECT NON FEDERAL DAM INSPECTION PROJECT NO. S81017 SHEET- -OF 2-5
NEW ENGLAND DIVISION COMPUTED BY " DATE_ _
LAUREL LAKE DAM CHECKED BY -4 DATE 7/ i / /E
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U LAUREL LAKE DAM CHECKED BY DTE7/I'
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DIVSEIFIED TECHNOLOGIES CORP CONSULTING ENGINEERS.,- NORTH HAVEN, CONNK
PROJECT. NON FEDERAL DAM INSPECTION PROJECTN4. 80-10-17 _EET2 -5PROJETCT.PROJECT NO.
NEW ENGLAND DIVISION COMPUTED BY "vi DATE "
LAUREL LAKE DAM CHECKED BY F DATE "/91/8L
..... . ... ...
,-". SUMRY- HYDRAULIC/HYDROLOGIC COMPL4ATI6 S, ' .- . .1-
v-TEST F . PEAK INFLOW PMF 350 FS
t(PAALE:L C-.QfPUTATIONS HAVE-,BEEN PERFcaRMD FOR lIQOYR
*PEAK IrNF~bW AND) RESULTS ARE SU?4MARIZ44D BELOW)-
PERFORMANCE AT PEAK FLOOD CONDITIONS: k pm 4iOO Y'RPEAK INPLOWS CFS 200
..' PEAK OUYIFLOWs CFSF 240 '112..SPLLL.CLAP.TO.IOP .. F DAM(EL,978.3NGVD) CFS 4 --
SPILL,CAP.TO TOP OF DAM % OF PEAK OUTFLOW 1Z0 366
..SPILL.cAP. TO PEAK FLOOD ELVN. CFS 2D4- 112
sPILL, CAP, tO PEAK FLOOD ELVN. % oF PEK OUTFo 0 100
-V PERFORMANCE:
MAXIMUM 'POOL 'ELEVATION NGVD 97, 7,86MAX. SU CHARGE HEI!GHT ABOVE SPILL.CREST T. -Zt . 1.86
-r F- ... -N EFJ.-- kFLOW-!SECTION.OF THE DAM OVERTOPPED -. .. N --- 0--- -----
DOWNSTREW .FAILURE CONDITIONS:j PEAK FAIILURE OUTFLOW CFS 36 OOO
FLOOD.-EIIMMEDIA.TELY -DIS FROM DAM..........2-fCONDITIOIS AT THE INITIAL IMPACT AREA:7
--ESTIMATED STAGE BEIFORE FAILURE WITH 240 CFS . 854,5NGfD
-ESTIMATE _ STAGE AFTER FAILURE WITH 3700 CFS 85.4
i-i -'._ .TFRASS. -IN. STAGE AETtR FAILURE , A .y .... -- I
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PRELIMINARY GUIDANCE
I FOR ESTIMATING
MAXIMUM PROBABLE DISrjhARGES
IN
PHASE I DAM SAFETY
INVESTIGATIONS
New England D~ivisionCorps of Engineers
March 1978
S1
4. -
MAXIMJM PROBABLE FLOOD INFLOWSNED RESERVOIRS
%I
Project D.A. MPF(cfs) (sq. mi.) cfs/sq. mi.
1. Hall Meadow Brook 26,600 17.2 1,546
2. East Branch 15,500 9.25 1,675
3. Thomaston 158,000 97.2 1,6254. Northfield Brook 9,000 5.7 1,580
5. Black Rock 35,000 20.4 1,715
6. Hancock Brook 20,700 12.0 1,725
- . 7. Hop Brook 26,400 16.4 1,6108. Tully 47,000 50.0 9409. Barre Falls 61,000 55.0 1,10910. Conant Brook 11,900 7.8 1,525
It. Knightville 160,000 162.0 987
12. Littleville 98,000 52.3 1,870
13. Colebrook River 165,000 118.0 1,400
14. Mad River 30,000 18.2 1,650
15. Sucker Brook 6,500 3.43 1,895
16. Union Village 110,000 126.0 87317. North Hartland 199,000 220.0 90418. North Springfield 157,000 158.0 994
" 19. Ball Mountain 190,000 172.0 1,10520. Townshend 228,000 106.0(278 total) 820
. 21. Surry Mountain 63,000 100.0 630
22. Otter Brook 45,000 47.0 957
23. Birch Hill 88,500 175.0 50524. East Brimfield 73,900 67.5 1,095 I25. Westville 38,400 99.5(32 net) 1,200
26. West Thompson 85,000 173.5(74 net) 1,150
27. Hodges Village 35,600 31.1 1,145
28. Buffumville 36,500 26.5 1,377
29. Mansfield Hollow 125,000 159.0 786
30. West Hill 26,000 28.0 928
31. Franklin Falls 210,000 1000.0 "tO
12. Blackwater 66,500 128.0 520
33. Hopkinton 135,000 426.0 316
34. Everett 68,000 64. '0 1,06235. MacDowell 36,300 44.0 825
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MAXIKuM PROBABLE FLOWS
BASED ON TWICE THESTANDARD PROJECT FLOOD(Flat and Coastal Areas)
CRiver SPF D.A. ___
(cfs) (sq. mi.) (cfs/sq. mil.)
1. Pawtuxet River 19,000 200 190
2. Mill River (R.I.) 8,500 34 500
3. Peters River (R.I.) 3,200 13 490
4. Kettle Brook 8,000 30 530
5. Sudbury River. 11,700 86 270
6. Indian Brook (Hopk.) 1,000 5.9 340
7. Charles River. 6,000 184 65
8. Blackstone River. 43,000 416 200
9. Quinebaug River 55,000 331 330
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ESTIMATING EFFECT OF SURCHARGE STORAGEON MAXIMUM PROBABLE DISCHARGES
-:! :i]INFLOW , pi1
oQ 3S
-OUTFLOW -
T
STEP 1: Determine Peak Inflow (Qpl) from GuideU tCurves.
STEP 2: a. Determine Surcharge Height To Pass
I b. Determine Volume of Surcharge(STOR]) In Inches of Runoff.
c. Maximum Probable Flood Runoff In NewEngland equals Approx. 19", Therefore:
::; .- STORiQp2 - Qpi x (1
19STEP 3: a. Determine Surcharge Height and
"STOR2" To Pass "Qp2"
b. Average "STORi" and "STOR2" and4 Determine Average Surcharge and
Resulting Peak Outflow "Qp3".iv
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SURCHARGE STORAGE ROUTING SUPPLEMENT
STEP 3: a. Determine Surcharge Height and
"STOR2" To Pass "Qp2"
b. Avg "STORi" and "STOR2" and
Compute "Qp3'.
4 " c. If Surcharge Height for Qp3 and
"STORAv" agree O.K. If Not:
STEP 4: a. Determine Surcharge Height and
"STOR3" To Pass "Qp3"
b. Avg. "Old STORAvG" and "STOR 3 "
and Compute "Qp4"
c. Surcharge Height for Qp4 and
''New STOR Avg should Agree
closely~ .V'i
S SURCHARGE STORAGE ROUTING ALTERNATE
I - STOR'
paQp2 =Qpi - pl )TO
FOR KNOWN QpI AND 19" R.O.
Qp2 STOR E L.
EL.
vi
-, ;' & ' -
"RULE OF THUMB" GUIDANCE FOR ESTIMATINGDOWNSTREAM DAM FAILURE HYDROGRAPHS
'' OPP
STEP I: DETERMINE OR ESTIMATE RESERVOIR STORAGE (S) IN AC-FT AT TIME OF FAILURE.STEP 2: DETERMINE PEAK FAILURE OUTFLOW (Qpl)"
op, w -'/-- Y0- 7 b
Wb= BREACH WIDTH - SUGGEST VALUE NOT GREATER THAN 40% OF DAMLENGTH ACROSS RIVER AT MID HEIGHT.
"Yo = TOTAL HEIGHT FROM RIVER BED TO POOL .VEL AT FAILURE.
*: , STEP 3: USING USGS TOPO OR OTHER DATA, DEVELOP REPRESENTATIVE STAGE-DISCHARGERATING FOR SELECTED DOWNSTREAM RIVER REACH.
STEP 4: ESTIMATE REACH OUTFLOW (Qp2) USING FOLLOWING ITERATION.
A. APPLY Qpl TO STAGE RATING, DETERMINE STAGE AND ACCOPMANYING
VOLUME (V1) IN REACH IN AC-FT. (NOTE: IF V1 EXCEEDS 1/2 OF S,
SELECT SHORTER REACH.)
B. DETERMINE TRIAL Qp2"
Qp(TRIAL) = Op, I
C. COMPUTE V2 USING Q (TRIAL).
D. AVERAGE V1 AND V2 AND COMPUTE Qp2 "
QP2 = Op,1
STEP 5: FOR SUCCEEDING REACHES REPEAT STEPS 3 AND 4.
APRIL 1978
-" viii
.
*to
APPENDIX E
INFORMATION AS CONTAINED INTHE NATIONAL INVENTORY OF DAMS
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