6"- j- IT

SUSQUENANNA RIVER BASIN,TRIBUTARY TO SUMMIT LAKE Ch7F,

LACKAWANNA COUN T IPENNSYLVANIA. LEVELO

"NDI ID NO. PA-01037DER ID NO. 35-087 'TlG

WILLIAM P. KELLY- 4'982JAN 0 41•982

JI jI

PHASE I INSPECTION REPORT

NATIONAL DAM INSPECTION PROGRAM

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DEPARTMENT OF THE ARMY

Baltimore District, Corps of Engineurs

Baltimore, Maryland 21203

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distribution is unlimitod.

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SUSQUEHANNA RIVER BASIN

TRIB. TO SUNMIT LAKE CREEK, LACKAWANNA COUNTY

PENNSYLVANIA

INTERLAK!! DAM

DER ID No. 35-87

NTIS GRA&IMR. WILLIAM P. KELLY DTIC TAB

Unannourirzd

By.DistriUt ! oi) /

Avai1i2LlttV-ý Codes

PHASE I INSPECTION REPORT

NATIONAL DAM INSPECTION PROGRAM

4Li

Prepared Byt

DEPARTMENT OF THE ARMYBaltimore District, Corps of Engineers

Baltimore, Maryland 21203

JUNF 1981

[ i -

PREFACE

This revort is prepared under guidance contained in the Recommended Guidelinesfor Safety Inspection of Dams, for Phase I investigations. Copies of theseguidelines may be obtained from the Office of Chief of Engineers, Washington,D.C. 20314. The purpose of a Phase I investigation is to identifyexpeditiously those dams which may pose hazards to human life or property.The assessment of the general condition of the dam is based upon availabledata and visual inspections. Detailed investigation and analyses involvingtopographic mapping, subsurface investigations, testing, ar'd detailedcomputational evaluations are beyond t-%e scope of a Phase I investigation;however, the investigation is intended to ilentify any need for such studies.

I In reviewing this report, it should be realized that the reported condition ofthe dam is based on observations of field conditions at the time of inspectionalong with data available to the inspection team.

It is important to note that the condition of a dam depends on numerous andconstantly changing internal and external conditions, and is evolutionary innature. It would be incorrect to assume that the present condition of the damwill continue to represent the condition of the dam at some point in thefuture. Only through frequent inspecttons can unsafe conditions be detectedand only through continued care and maintenance can these conditions beprevented or corrected.

Phase I inspections are not intended to provide detailed hydrologic andhydraulic analyses. In accordance with the established guidelines, thespillway design flood is based on the estimated "Probable Maximum Flood" forthe region (greatest reasonably possible storm runoff), or fractionsthereof. The spillway design flood provides a measure of relative spillwaycapacity and serves as an aid in determining the need for more detailedhydrologic and hydraulic studies, considering the size of the dam, its generalcondition, and the downstream damage potential.

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UDI ID No. PA 01037, DER ID No. 35-87

PHASE I INSPECTION REPORT

NATIONAL DAM INSPECTION PROGRAM

CONTENTS

Description Pa e

Brief Assessment of General Conditionand Reco-iended Action ........ iii

SECTION 1 - Project Information. . . . . . . . . . . . . . . . 1SECTION 2 - Engineering Data............... 5SECTION 3 - Visual Inspection ............... 6SFCTION 4 - Operational Procedures ......... ..... 8SECTION 5 - Hydrology and Hydraulics ...... . . ..... 9SECTION 6 - Structural Stability ............... 11SECTION 7 - Assessment, Recommendations, and

Proposed Remedial Measuret. .......... 12

APPENDICES

Appendix Title

A Checklist - Visual Inspection.B Checklist - Engineering Data.C Photographs.D Hydrology and Hydraulics.E Plates.F Geology.

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PHASE I INSPECTION REPORT

NATIONAL DAM INSPECTION PROGRAM

BRIEF ASSESSMENT OF GENERAL CONDITIONAND

RECOMMENDED ACTION

Name of Dam: INTERLAKEN DAMNDI ID NO. PA 01037DER ID NO. 35-087

Size: Small (9.6 feet high; 61 acre-feet)

Hazard Classification: Significant

Owner: Mr. William P. KellyClarks Summit, PA

State Located: Pennsylvania

County Located: Lackawanna

Stream: Tributary to Summit Lake Creek

Dates of Inspection: 23-24 March 1981

The visual inspection and review of available design and construction dataindicate that Interlaken Dam is in poor condition. The deteriorated conditionof the spillway, the inadequate spillway capacity and the adjlacent breachedand low areas of the embankment are the primary deficiencies which causeconcern for the safety of this facility. In accordance with the recommendedguidelines, the spillway design flood (SDF) for this facility is in the rangeof the 100 year flood to 1/2 the Probable Maximum Flood (PMF). Based on thesize of the dam and degree of downstream hazard, the selected SDF is the 100year flood.

The hydrologic and hydraulic computations indicate that the combination ofreservoir storage and spillway discharge capacity will not pass the SDF priorto overtopping the embankment. In accordance with the criteria outlined andevaluated in Section 5.5, the spillway for Interlaken Dam is considered to beinadequate.

INTERLAKEN 1AM

The following reco-mmendations should be implemented by the owner withoutdelay:

a. Necessary remedial measures should be implemented under the guidanceof a qualified engineer to repair the deteriorated spillway and fill in theadjacent breached and low areas of the embankment. In addition, the spillwaycapacity should be made adequate and an upstream closure should be provided onthe outlet works.

b. The trees and brush should be cleared from the embankment under theguidance of a qualified engineer.

c. A formal surveillance and downstream emergency warnring system shouldbe developed for use during periods of heavy or prolonged precipitation.

d. An operation and maintenance manual or plan should be prepared for useas a guicle in the operation and maintenance of the dam (luring normal andemergency uond it ions.

e. A schedule of regular inspection by a qualified engineer should bedeveloped.

APPROVED BY:4¶

DEPARTMENT OF THE ARMYBALTIMORE DISTRIC CORPS OF ENGINEERS

MES W. PECKolhnel, Corps of Engineersommmmander and District Engineer

DATE: 28~ ZIA ~

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PELASE I INSPECTION REPORT

NATIONAL DAM INSPECTION PROCG1AM

INTERLAKEN DAM

NDI ID No. PA 01037

DER IM No. 35-087

SECTION I

PROJECT INFORMATION

1.1 General

a. Authority. The Dam Inspection Act, Public Law 92-367, authorized theSecretary of the A"p, through the Corps of Engineers, to initiate a programof inspection of non-federal dams throughout the United States.

b. Purpose. The purpose of this inspection is to determine if the damconstitutes a hazard to human life and property.

1.2 Description of Project.

a. Description of ram and Appurtenances. Interlaken Dam is an earthfillstructure approximately 9.G feet high and 425 feet in length (includingspillway). The spillway is an uncontrolled broadcrested weir locatedapproximately 200 feet Crom the right abutment, and has a length of 30 feetbetween two concrete walls. A uoncrete apron is lo~.ated immediatelydownstream of the spillway. The outlet works consists of a 12 inch terracotta pipe with a gate valve at the downstream toe.

Note: The U.S.G.S. 7.5 ninute Quadrangle S'eet (Scranton, PA.) indicates areservoir elevation of 1341.0, which in used as the spillway crestelevation for this report.

b. Location: Soutn Abington Township, Lackawanna County, Pa.

U.S.C.S. Quadrangle - Scranton, Pa.

Latitude 410 28'; Longitude 750 42.7'

Refer to Plates I & II, App. E.

c. Size Classification: Small: Height-9.6 feet, Storage 61 acre feet

• •d. Hazard Classification: SignificanL (Refer to Section 3.1.e)

1

a. Ownershipt Mr. William P. KellyRD 3, Box 305Clarke Summit, Pa. 18411

f. Purpose: Recreation

g. Design an~d Construction History:

The dam was designed by W. R. Bircher and W. V. Devereaux. Construction wascompleted in 1928. During construction, the spillway location was changed toits present position, and a concrete cap was added to the spillway crest. In1930, the spillway walls were raised to develop a total spillway depth of 3feet.

h. Normal Operating Procedure

At the time of inspection, normal flow was passing through a breachlocated iumediately adjacent to the right spillway wall. Plow also waspassing under the spillway cap. The owner has been requested by PennDER todraw tho reservoir down until such time as this condition can be corrected.

1.3 Pertinent Data

a. Drainage Area (Square miles)

From files: 0.57Computed for this report: 0.40"Use: 0.40

b. Discharge at Damsite (cubic feet per second)

Maximum known flood unknownOutlet works with maximt,% pool (El. 1342.7) unknownSpillway with maximum pool (El. 1342.7) 190

c. Elevations (feet above mean sea level)

Top of DamDesign UntcnownExisting Low Point (Breach Area) 1339.?Assumed top of dam (top of left 1342.7

spillway wall)

Normal pool (exasting breach) 1339.7Spillway Crest

Design UnknownExisting 1341.0

Outlet WorksUpstream invert UnknownDownstream invert UnknownStreambed at toe 1333.1

2-k

d. Reservoir Length (feet)

Normal pool (11. 1339.7) 2000Spillway crest (11. 1341.0) 2100Assumed Max. Pool (11.1342.7) 2200

e. Storage (acre-feet)

Normal pool (11. 1339.7) 39Spillvay crest (E1. 1341.0) 43Assumed Max. Pool (91.1342.7) 61

f. Reservoir Surface (acres)

Normal pool (E1. 1339.7) 9.5Spillway crest (El. 1341.0) 10.0Assumed Max. Pool (11.1342.7) 10.5

g. Dam

Notet R efer to plate@ in Appendix E for plansand sections

E Earthfill with concretecorewall

Length 425 feet including4- spillway

Top Width 6 feet

Height 6.6 feet - low pointof breach to

downstream toe9.6 - Assumed top of dam

to downstream toe.

Side Slopes

Upstream Varies, 1VM1.%E above spillway crest; 1V:51 belowDownstream Varies, 1V:2H right end to 1V:2.7H left

ZonIAg None

Cutoff Corevall

Grouting None

h. Outlet Works

Tue. 12-inch terra cotta pipe throughembankment

Closu-e Valve located at downstream toe

3

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SSToad-ctesttd roectatkengr coAcrete We*r

Location- Center of dm

30 feet

Crest Ilevation 1341.0 a.*.l.

0 feet (existing 1ow point)1.7 feet (assumed TOD)

aproach Channel Reservoir

Dovustrea ChaGnes Gouted riprap apron

, a-- to rock and earth

channel.

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SECTION 2

ENGINEIRING DATA

2.1 Design.

The available data for Interlaken Dam consist of files prnvided byPennDER. Information availabln includes a permit application report with ageneral description of the design of the facility, PennDER inspection reportsand various related correspondeace. Drawings which provide cross-sections anddetails of the dam are also available. The reference datum for these designdrawings is unknown.

2.2 Construction.

Information concerning construction of the dam is limited to thecorrespondence contained in the PennDER files which indicated that the dam wasbuilt in general accordance with the plans.

2.3 Operation.

No formal records of operation or maintenance exist. The owner has beendirected by PennDER to keep the reservoir d'avn down to prevent flow fromcontimuing to erode a breach area adjacent to the right spillway wall.

2.4 Evaluation.

a. Availabil t . All available written information was contained in thepermit files provided by PannDER.

b. A. The available data, including that collected during therecent detailed visual inspection, are considered to be adequate to make areasonable assessment of the dam.

II

A

SECTION 3

VISUAL INSPECTION

3.1 Observations.

a. General. The overall appearance and general condition of the dam andappurtenances are poor. The embankment is breached for a width of five feetadjacent to the right spillway wall. This and other noteworthy deficienciesare discussed below. The visual inspection checklist, field sketch andprofile are provided in Appendix A. Photographs taken during the inspectionare reproduced in Appendix C.

The reseprvoir rool was approximately 1.2 feet below spillway crest and0.1 foot above the bottom of the breach on the day of the initialinspection. Present during part of this inspection were Mr. William P. Kelly,owner, and Mr. John Chernesky of Pennsylvania Department of EnvironmentalResources.

On the day of the review inspection, the pool was being drawn down asrequested by PennDER on 26 March 1981. This request 4as made as a result ofthe initial inspection.

b. Embankment. The horizontal alignment of the six foot wide crest is 4

good. The crest is low adjacent to both spillway walls, and the left end ofthe crest is about one foot higher than the right. The low spot adjacent to

-i the right spiliway wall is the result of a five foot wide breach in theembankment. At the bottom of this breach is the top of the 18 inch thickconcrete corewall. Flow through this opening has eroded the embankment on thedownstream side of the corewall to a depth of about two feet below the top ofcorewall. Another low spot adjacent to the left spillway wall is about 0.8foot below the top of the wall. The entire embankment except for the upstreamslope below spillway crest is covered with trees and brush. Riprap comprisedof flat stones with a median dimension of 8 inches covers the upstream facebelow spillway crest elevation. Although the riprap is sparse in some areas,there is no erosion occurring except at the breached section. The upstreamslope varies from about IV:I.511 above the riprap to LV:b51 below. Thedownstream slope varies from about 1V:2H right of the spillway to IV:2.7H leftof the spillway. Except for the breached section, the slopes appear stablewith no erosion or sloughing. The toe area is wet and rutted due to a partialthaw and the movement of logging equipment.

c. Appurtenant Structures. According to the PennDER inspection report,the outlet works consists of a twelve-inch terra-cotta pipe through thecorewall. An upstream valve box was pioposed; however, a four foot squarebrick pit was located near the toe of the dam in line with the right spillwaywall. The pit is filled with debris which! was probed, but no valve was foundduring the initial inspection. The discharge end of the pipe is not visible;however, flow can be seen existing at various locations along the rockculvert. When the review inpsection was made, the top of the valve was

4 visible in the pit, and had recently been operated satisfactorily.

6

The spillway is located near the center of the dam. The crest consistsof 2 16 inch high by 18 inch vide concrete cap on the corewall. This cap iscracked and leaning downstream. Water is flowing under the cap near its rightend at the rate of approximately 2 gallons per minute. The concrete spillwaywalls are severely deteriorated. The upstream wingwall on the right side haspartially collapsed. The remaining portion of the wall adjacent to the crest.1 is precariously balanced on a narrow piece of concrete. The adjacent breachthrough the embankment has removed any lateral support for the wall. It isapparent that the right wall was raised in the past since large slabs ofconcrete are cracking along regular horizontal lines which appear to bejoints. The upstream wingvall on the left side has cracked at the crest andI settled six inches. The discharge channel immediately downstream of the weiris a concrete slab which was placed over riprap. The concrete is cracked andis being undermined along the edges. This slab is initially the same width asthe weir but narrows immediately and all flow is directed into a 3.5 foot highby 4 foot wide rock culvert. Flows in excess of the capacity of this culvertflow over the dirt road at the toe of the dam causing some erosion. Thiserosion would not be sufficient to threaten the safety of the dam.

d. Reservoir. The wooded reservoir slopes are moderate and appearstable. Logging operations are being conducted within the watershed.

e. Downstream Channel.. Immediately downstream of the dam the channel iscut in earth with light woods along the banks. Flows from Interlaken damjoins Summit Lake Creek approximately 500 feet downstream of the dam. A largeconcrete culvert then conducts the flow under Pennsylvania Route 307 about 300feet further downstream. Two private residences are located in the floodplainof Suomi- Lake Creek approximately 1,400 feet downstream of Interlaken Dam.The first floor (damage level) of the first residence encountered is nine feetabove the streambed. The damage level for the second house is 6 feet abovethe stream channel. It is judged that failure of Interlaken Dam would createa potential hazard for property damage and the loss of a few lives. For thenext 3,000 feet the floodplain is considerably wider and the channel slope isflatter. Summit Lake Creek flows into Maple Lake, DER No. 35-27,approximately 0.9 miles downstream from Interlaken Dam. The next 0.5 mile ofchannel is a steep gorge within which LaRue Dam, DER No. 35-28, is located.Both this structure and Maple Lake Dam are less than 20 feet high with smallamounts of storage. These dams would not be seriously affected by failure ofInterlaken Dam. Summit Lake Creek passes under U.S. Route 11 and joins

I Leggetts Creek 1.5 miles downstream of the dam. A significant hazardclassification is appropriate for Interlaken Dam.

f. Evaluartion. The breach that has occurred adjacent to the spillwaycauses zoncern for the safety of dam. Continued erosion of the embankment,especially on the downstream side of the corewall, could eventually causefailure of the dam. Repair of this area would also require rehabilitation ofthe adjacent spillway wall. It is doubtful that, in its present condition,this wall would support the adjacent earthfill without collapsing into thespillway. The remainder of the spillway requires considerablerehabilitation. The trees and brush should be cleared from the embankment.

7

SECTION 4

OPERATIONAL PROCEDURES

4.1 Normal Operating Procedure. The pool level is currently maintained atthe low point of the breached section. inflow is passing thru the breachedarea and eroding portions of the downst~res~m face of the embankment. The lowpoint of the breached area is 1..3 fe'et below the spillway crest (elevation1341.0). On March 26, 1981 it was requested by PennDER that the lake be drawndown. No formal operating manual exists.

4.2 Maintenance of Dam. The condition of the dam as observed by theinspection team is indicative of a general lack of maintenance. It appearsthat no maintenance has been performed in the recent past. A breach sectionhas developed in the embankment. In addition, the embankment has a heavygrowth of trees and brush. The spillway has significant wall displacementwith severe cracking. The concrete cap on the spillway is leaking. No formalmaintenance manual exists.

4.3 Maintenance of Operating Facilities. The outlet works consists of a 12inch terra-cotta pipe through the dam with a downstream closure valve. Thevalve was operating satisfactorily during the review inspection.

4.4 Warning System. No formal warning system exists.

4.5 Evaluation. The breached area and spillway are areas that should berepaired immediately. Routine maintenance of the facility should includereimoval of trees, brush, and high weeds. Formal manuals of maintenance andoperation are recommended to ensure that all needed maintenance is identifiedand performed regularly. In addition, a formal warning system for theprotection of downstream inhabitants should be developed. Included in theplan should be provisions for around-the-clock surveillance of the facilityduring periods of unusually heavy precipitation.

8

SECTION 5

HYDROLOGIC/HYDRAULIC EVALUATION

5.1 Design Data. No formal design reports or calculations are known to existfor the facility. A d. sign drawing showing embankment, spillway and reservoirarea details is located in the PennDER files and is shown in Appendix E ofthis report.

5.2 Experience Data. Records of reservoir levels and/or spillway dischargesare not available.

5.3 Visual Observations. On the date of the inspection, the breached s('ctionof the embankment had flow over it. This condition caused concern for thesafety of the dam and it was requested that the lake be drawn down. Thebreach and low areas should be filled in. In addition, the spillway walls andcap are in need of repair. See field sketch in Appendix A and photographs inAppendix C for a better description of the facility.

5.4 Method of Analysis. The facility has been analyzed in accordance withprocedures and guidelines established by the U.S. Army Corps of Engineers,Baltimore District, for Phase I hydrologic and hydraulic evaluations.

5.5 Summary of Analysis.

a. Spillway Design Flood (SDF;. In accordance with the procedures andguidelines contained in the National Guidelines for Safety Inspection of Damsfor Phase I Investigations, the SDF for Interlaken Dam ranges between tha 100year flood and one-half the Probable Maximum Flood (PMF). This classificationis based on the relative size of the dam (small) and the potential hazard ofdam failure to downstream development (significant). Due to the small storage(61 ac-ft) and height (9.6 feet), the SDF selected was the 100 year flood.

b. Results of the Analysis. The 100 year flood peak is derived byaveraging the peak flow value obtained from two regression equations. Thefirst regression equation is from Bulletin 13, Floods in Pennsylvania, WaterResources Bulletin. Guidelines are provided to determine the peak value byuse of regional statistical data. The second regression equation is from theHydrologic Study, Tropical Storm Agnes, North Atlantic Division, U.S. ArmyCorps of Engineers, 1975. Guidelines are provided to determine the flood peakby use of map coefficients and logarithmic equations. The following resultsare obtained.

100 year flood peak CFS

Bulletin 13 - 285North Atlantic Division - Tropical Storm Agnes 640Average 100 year flood peak 460

9

To determine the adequacy of the spillway, the average value for the 100year flood is compared against the maximum outflow at low point top of dam.If the maximum ou±tflow exceeds the 100 year average peak value derived above,then the spillway is rated adequate. If, however, the 100 year average pedkvalue exceeds the maximum outlfow at low point top of dam, the spillway israted inadequate. Results are as follows.

CFSMaximum Outflow at low point top of dam - 10Average 100 year flood peak - 460

5.6 Spillway Adequacy.

Under existing conditions, the spillway cannot pass the 100 yearflood peak, value. 3ince this structure cannot pass the selected 813 (100 yearflood), the spillway is rated inadequate.

10

vau xed.h alu ulfwa o on o 5dm the splwyw

SECTION 6

STRUCTURAL STABILITY

6.1 Evaluation of Structural Stability

a. Visual Observations

(1) Embankment. Interlaken Dam is a brush and tree coveredembankment that is in poor condition. The dam contains an 18 inch thickconcrete corewall which is exposed in a breach of the embankment at the rightspillway wall. At the corewall, the breach measures 5 feet wide by 3.5 feetdeep. Embankment material at the breach is visuelly classified as a finesilty sand and appears to erode easily. Water discharges through the breachbefore reaching the spillway weir since the corewall elevation is 1.3 feetlower than the spillway crest. Downstream of the corewall the breach sectionis 6 feet deep by an average of 7 feet wide. Water that flows through thisbreach ponds on the road at the toe in rutted areas, keeping the area soft andwet. Water then flows from the toe area into the discharge channel. Theembankment has a 6 foot wide crest, upstream slopes of 1.5H:IV, and thedownstream slope from 2H:1V right of the spillway to 2.7H:IV left of thespillway. The upstream slope appears to be lightly riprapped with 8 inchrock.

(2) Appurtenant Structures. The 30 foot long spillway is adeteriorated concrete structure. The walls are cracked and broken. A portionof the upstream right spillway wall is laying in the breach area. Much of the"right spillway wall is exposed due to the embankment breach. Immediatelydownstream of the spillway the discharge channel is riprapped and grouted witha concrete cap. A 4 x 4' brick lined pit containing a valve for the outletworks is located at the downstream end of the right spillway wall.

b. Design and Construction Data

(1) Embankment. PennDER files contain a report on the permitapplication, a design drawing, and a modified design drawing that show a planand cross-sections. W. H. Bircher and W. V. Devereaux are listed as thedesign civil engineers. The embankment was designed to have a crest width of10 feet and upstream and downstream slopes of 2H:1V. A revised drawing, Feb.3, 1926, indicates that the corewall crest would follow the contour of theground; however, a drawing submitted in 1928 indicates that the corewall crestis level.

(2) Appurtenant Structures. The 1926 design data indicated that a30 foot long spillway would be locatnd approximately 70 feet from the leftabutment of the dam. Additionally, an outlet works was to be locatedapproximately 200 feet from the left abutment. The outlet works was toconsist of an 8 inch cast iron pipe encased in 12 inches of concrete and havea valve upstream of the corewall.

11

Changes were made during construction that were noted in a 1927PennDER inspection. The spillway location was moved adjacent to the outletworks, approximately 200 feet from the left abutment. The spillway weir crestwas reported to be the top of the coreeall; however, a 1928 photograph Phowsthat a 1.3 foot concrate cap, as measured during this inspection, was placedon the corevall in the spillway. A twelve inch terra cotta pipe reportedlywas used as the outlet works pipe, and the valve location was nov at thedownstream toe of the dam.

c. Operatini Records. None.

d. Post Construction Changes. The height of the spillway walls wasincreased around 1930 to produce a spillway depth of 3 feet.

a. Seismic Stability. The dam is located in Seismic Zone I. Based onvisual observations, the dam is considered statically stable. Therefore, theseismic stability is considered adequate. However, if embankment erosion atthe breach is allowed to continue, exposing more corewall, the stabilitycondition will change.

12

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4

SECTION 7

ASSESSMENT AND RECOMMENDATIONS

7.1 Dam Assessent. .

a. Safe. The visual inspection and review of available design and

construction data indicate that Interlaken Dam is in poor condition. Thedeteriorated condition of the spillway, the inadequate spillway capacity andthe adjacent breached and low areas of the embankment are the primary defici-encies which cause concern for the safety of this facility. In accordancewith the recommended guidelines, the spillway design flood (SDF) for thisfacility is in the range of the 100 year flood to 1/2 the Probable MaximumFlood (Pt(F). Based on the size of the dam and degree of downstream hazard,the selected SDF is the 100 year flood.

The hydrologic and hydraulic computations indicate that the combination

of reservoir storage and spillway discharge capacity will not pass the SDF(100 year flood) prior to overtopping the embankment. In accordance with thecriteria outlined and evaluated in Section 5.5, the spillway for InterlakenDam is considered to be inadequate.,,

b. adequacy of information. The design and construction data containedin PennDER files, in conjunction with data collected during the recent visualinspection, are considered to be adequate for making a reasonable assessmentof this dam,

c. Urgency. The recommendations presented below should be implex:ýntedwithout delay.

d. Necessity for Additional Studies. The results of this inspectionindicate a need for additional investigations by a qualified engineer todetermine remedial measures required for the spillway structure.

7.2 Recommendations.

a. Necessary remedial measures should be implemented under the guidanceof a qualified engineer to repair the deteriorated spillway and fill in theadjacent breached and low areas of the embankment. In addition, the spillwaycapacity should be made adequate and an upstream closure should be provided onthe outlet works.

b. The trees and brush should be cleared from the embankment under theguidance of a qualified engineer.

c. A formal surveillance and downstream emergency warning system shouldbe developed for use during periods of heavy or prolonged precipitation.

d. An operation and maintenance manual or plan shoulI be prepared foruse as a guide in the operaticrn and maintenance of the dam during normal andemergency conditions.

e. A schedule of regular inspection by a qualified engineer should bedeveloped.

13

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APPENDflC A

CUROCLIST - VISUAL INSPECTION

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PHASE I INSPECTION REPORTNATIONAL DAM INSPECTION PROGRAM

IX: INTERLAKEN DAMWILLIAM R KELLY

/ :FIELD SKETCH

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$a q0 4 N 0 wV* i v v in ) PHASE I INSPECTION REPORT

K, NATIONAL DAM INSPECTION PROGRAM

INTERLAKEN DAM(1.33J) NOI.LVA313 WILLIAM KELLY

PROFILE AND SECTION

IJULY 1981 EXHIBIT A-2

APPENDIX B

CHECKLIST ENGINEERING DATA

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APPENDIX C

PHOTOGRAPH~S

8 %

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II

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'I NOTEALL PICTURES TAKEN

ii 24 MAR 81 EXCEPTAS NOTED.

'-*LOCATION AND ORIENTATIONOF CAMERA

-3 PHOTOGRAPH IDENTIFICATION-. NUMBER

"/ --. NOT TO SCALE

./ / PHASE I INSPECTION REPORT

'//2 NATIONAL DAM INSPMCTION PROGRAM

INTERLAKEN DAMI /WILLIAM R KELLY///

PHOTOGRAPH LOCATIONPLAN

JULY 1961 EXHIBIT C-I

lin"•'i- .••...i=.,• r

INTERLAKEN DAM

1.Crest near right abutment.

2. Upstream face.j

INTERLAKEN DAM

3. Downstream face..

j4. Breach area adjacent to right spillway wall.

c-.3

INTERLAKEN DAMI

5. Breach arva and

spi Iiway crot.t

l.v li sp ilI way wall and c rest .

- -.- <-.-'~-.-.C. -- 4 -

INILERLAKEN DAM

7. Spillway crest and discharge apror.-

4*1

8. Valve pit. Top of valve stemn visiblei~ nI

center of picutre. (20 May 81)

G- -5

------

INTERLAKEN DAM

M4

9. Discharge channel with rock culvert in foreground.

10. PA. Route 307 highway culver. (800 feet u

I C;-6

INTERLAKEN DAM

i. First downstream residence.

C-7

APPENDIX D

HYDROLOGY AND HYDRAULICS

BALTIMORE DISTRICT, CORPS OF ENgIWIERpS PACE

SUBJECT-b~42~7i yi

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SALII@1 DISTRICT, CORPS OF 6111e1116110 PAGE

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"SLTIMOOIK 018??CT, CORPS Of tftOIWEERS PAGE

SUSEICT SLJA*ý ____________________________

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SUBAECT S-i- A Ai4%4'S IS

COMPUTATIONS A 4 S9 TO - SHEETS

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I12

APPENDIX E

PLATES

jr

z

zw LK

zz If

ccui C, 't v-10-4 t.

z

g

0

IL

7A 2 tio

jet-ik

uj PHASE I INSPECTION REPORTNATIONAL DAM INSPECTION PROGRAM

cr INTERLAKEN DAMWILLIAM P. KELLY

LOCATION MAP

JULY 1981 PLATE E-Z

C_

A

74

a0 Sum

N

1132

7%,N

atw Tank/A

CP C

Scre tos'ýCou fyClub

fZ

Interlaken DamL

'04

Abington H %4'!ý44 Ilk

%

J01,

__vw

Trainage Area Boundar__

'0/* YF1

T. a Centroid-- Longest Watercourse V%

Id/

11,ý---Downstream Developmen

SCRANTON, PA.

N4122.5-W7537.5/7.5 PHASE I INSPECTION REPORT1947 NATIONAL DAM INSPECTION PROGRAM

PHOTOREVISED 1969 AND 1976AMS 5866 1 NW-SERIES V631 INTERLAKEN DAM

FLALE 1:24000 WILLIAM P KELLY1000 0 1000 20M 30M rM

DRAINAGE AREA 8 DOWNSTREAMDEVELOPMENT PLAN

r JULY 1981 PLATE E-31

r0 64

A N..

-SAc

- )Orr-

A WOO L44

TAP4 (kf 04tm

4- 1 ALand-- - 9, C~i~t47e*

~ ~tB VQ'~.tit: ~-I. -4r

9. . .9-. -LOC.AT io m

OM THL FARMP KPIOWr.. ~ ~~~~~R C.vnt r_.n~oiT~e~ADDRE:Z 354 W,*

4 ~'Y* ~ -JAMU,%Oy - U.-

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7 A

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4.~~~ f 4-.-

..

.~ I L

7-.-WYOMING Co~mflTLACKAfAft~rA

LOCATIOn M PLAI1. -Meso.rK EMAM CIF LEGGETrT CREK rk

IER. DR. Cg. E- ' -0N

R Et s - - " v m r . i s c t w , ^

. --

ItI

44- is

-W " V w

PHS NPCINRPR

ft.. A

JUL 198PLT -

APPENDIX F

GEOLOGY

IGERNAL GEOLOGY

Bedrock at Interlaken Dam is gray to red siltstone and shale of the Catskill

Formation. It is well bedded in thin to medium beds with closely spaced, well

developed joints. Siltstone is moderately resistant to weathering and

breaking along joints into tabular and blocky fragments. Glacial till is

probably thin at this site.

Legend

(Bedrock)

Dck CATSKILL FORMATION UNDTVIDED - Succession of grayish - red sandstone,

siltstone, and shale, generally in fining - upward cycles; some gray sandstone

and conglomerate.

F-1

Vr in/ I

,~ 44

IA~o f~ww

'N - --ow

A' to'

II~%

/ ALE: * 200GEOOGItMA

- EHIITF-................................................... f -Wate Tank