A-G WOODWARD-CLYDE CONSULTANTS PLYMOUTH F/6 …design and construction of dams. (1) The right...

A-G WOODWARD-CLYDE CONSULTANTS PLYMOUTH MEETING PA F/6 13/13

NATIONAL DAM INSPECTION PROGRAM. ECHO LAKE DAN (MDI NUJMBER PA-S-.ETCIU)MR81 M F BECK, 4 H FRDRICKUNCLASSIFIED

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ELAWARF i; -- BASIN lv00 iTRIBUTARY TO JACOBY CREEK, N(ORTHAMPTON COUNTY

PENNSYLVANIA110N1 NO. PA-00957

DER NO.48-3

OWNER: ECHO LAKE DEVELOPMENT COMPANY INC.

-~~HA-SE.I INPCIN REPORT.'$

rSATIONAL DAM INSPECTION PROGRA:MeDO,, I? '~i - ..01

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DEPARTMENT OF THE ARMY~ Baltimore District, Corps of Engineers

11iPI in, Baltimore, Maryland 21203A 'onA

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DELAWARE RIVER BASIN

TRIBUTARY TO JACOBY CREEK

ECHO LAKE DAMNORTHAMPTON COUNTY, PENNSYLVANIA

NDI NO. 00957DER NO. 48-3

PHASE I INSPECTION PROGRAMNATIONAL DAM INSPECTION PROGRAM

Prepared by:

WOODWARD-CLYDE CONS ULTANTS5120 Butler Pike

Plymouth Meeting, Pennsylvani.a 19462

Submitted to:

DEPARTMENT OF THE ARMYBaltimore District, Corps of Engineers

Baltimore, Maryland 21203

I March 1981

UTIO-n N SAEE~

Appnwed for pub~c rmleza;

PREFACE

This report is prepared under guidance contained inthe Recommended Guidelines for Safety Inspection of Dams forPhase I Investigations. Copies of these guidelines may beobtained from the Office of the Chief of Engineers, Washington,D.C. 20314. The purpose of a Phase I investigation is toexpeditiously identify those dams which may pose hazards to humanlife or property. The assessment of the general condition of thedam is based upon available data and visual inspections.Detailed investigations, testing and detailed computationalevaluations are beyond the scope of a Phase I investigation;however, the investigation is intended to identify the need formore detailed studies.

In reviewing this report, it should be realized thatthe reported condition of the dam is based on observations offield conditions at the time of inspection along with dataavailable to the inspection team. In cases where the reservoirwas lowered or drained prior to inspection, such action, whileimproving the stability and safety of the dam, removes the normalload on the structure and may obscure certain conditions whichmight otherwise be detectable if inspected under the normaloperating environment of the structure.

It is important to note that the condition of a damdepends on numerous and constantly changing internal and externalconditions, and is evolutionary in nature. It would be incorrectto assume that the present condition of the dam will continue torepresent the condition of the dam at some point in the future.Only through frequent inspections can unsafe conditions bedetected, and only through continued care and maintenance canthese conditions be prevented or corrected.

Phase I inspections are not intended to providedetailed hydrologic and hydraulic analyses. In accordance withthe established Guidelines, the spillway design flood is based onthe size and hazard classifications. The selected spillwaydesign flood can range from the 100 Year Flood to the estimated"Probable Maximum FloodO for the region (greatest reasonablypossible storm runoff). The spillway design flood provides ameasure of relative spillway capacity and serves as an aid indetermining the need for more detailed hydrologic and hydraulicstudies, considering the size of the dam, its general condition

and the downstream damage potential. -

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PHASE I INSPECTION REPORTNATIONAL DAM INSPECTION PROGRAM

Name of Dam: Echo Lake DamCounty Located: Northampton CountyState Located: PennsylvaniaStream: Tributary to

Jacoby CreekCoordinates: Latitude 400 54.2'

Longitude 750 8.7'Date of Inspection: November 20, 1980

LEcho Lake Dam and Peservoir are used for recreationalpurposes. The dam and spillway structure of Echo Lake are currentlyin fair condition and the outlet structure is in poor condition.

I4. accordance with criteria established by Federal (OCE)Guidelines, he recommended spillway design flood for this "Small"size dam and "Significant" hazard potential classification is the100 Year Flood to one-half the Probable Maximum Flood. Based on thesmall capacity of the reservoir and the fact that no loss of life islikely during failure of the structure, the 100 Year Event has beenselected as the spillway design flood.

Hydrologic and hydraulic computations presented in Ap-pendix D indicate the spillway structure is not capable ofdischarging the 100 Year Event while confining dam outflow to thedesigned spillway. With the spillway notch closed (normal poollevel), the right abutment area overtops by about 0.3 feet for anestimated five hours. Thus the spillway is consideLed "Inadequate".If the spillway notch is permanently open, the spillway would beconsidered "Adequate". I /(I

It is recommended that the following measures be under-taken immediately. Item (1) should be performed under thesupervision of a registered professional engineer experienced in thedesign and construction of dams.

(1) The right abutment area would be the first area toexperience overtopping; it should be evaluated from thestandpoint of functioning as an emergency spillway.Alternatively, the stop log could be removed permanently.

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ECHO LAKE DAM, NDS I.D. No. PA 00957

(2) Cracks in the spillway walls and slabs should be sealed toprevent further damage.

(3) All trees and brush should be removed from the downstreamembankment face.

(4) The pond drain pipe should be fitted with an operationalcontrol device at its upstream end.

(5) Seepage through the dam should be monitored for thedevelopment of turbidity and increase in quantity.

"Because of the potential for property damage in the eventof failure, a formal procedure of observation and warning duringperiods of high precipitation should be developed and implementedfor this facility. This procedure should be coordinated with localauthorities and should include a method of warning downstreamresidents that high flows are expected. In addition, an operationand maintenance procedure should also be developed to insure thatall pertinent items are carefully inspected on a regular basis andmaintained in the best possible condition.

Mary ,. Beck, P.E. Date/Pennsylvania Registration 27447EWoodward-Clyde Consultants

Joh9 H. Frederick, Jr., P.E.Ma/land Registration 7301Woodward-Clyde Consultants

APPROVED BY:

EDate1lonel, Corps of Engineers

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TABLE OF CONTENTS

PAGE

Preface iAssessment and Recommendations iiOverview Photograph iv

SECTION 1 - PROJECT INFORMATION1.1 Genctal 11.2 Description of Project I1.3 Pertinent Data 3

SECTION 2 - ENGINEERING DATA2.1 Design 52.2 Construction 52.3 Operational Data 52.4 Evaluation 5

SECTION 3 - VISUAL INSPECTION3.1 Findings 63.2 Evaluation 8

SECTION 4 - OPERATIONAL PROCEDURES4.1 Procedures 94.2 Maintenance of the Dam 94.3 Maintenance of Operating Facilities 94.4 Warning Systems In Effect 94.5 Evaluation 9

SECTION 5 - HYDROLOGY/HYDRAULICS5.1 Evaluation of Features 11

SECTION 6 - STRUCTURAL STABILITY6.1 Evaluation of Structural Stability 13

SECTION 7 - ASSESSMENT/REMEDIAL MEASURES7.1 Dam Assessment 157.2 Remedial Measures 15

APPENDIXA Visual InspectionB Engineering Data, Design, Construction

and OperationC PhotographsD Hydrology/HydraulicsE PlatesF Geology

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PHASE I INSPECTION REPORTNATIONAL DAM INSPECTION PROGRAM

ECHO LAKE DAMNATIONAL I.D. NO. PA 00957

DER NO. 48-3

SECTION 1PROJECT INFORMATION

1.1 General.

a. Authorit . The Dam Insoection Act, Public Law 92-367, authorized the Secretary of the Army, through the Corps ofEngineers, to initiate a program of inspection of dams through-out the United States.

b. Purpose. The purpose of the inspection is todetermine if the am constitutes a hazard to human life orproperty.

1.2 Description of Project.

a. Dam and Appurtenances. Echo Lake Dam is an earthand rockfill dam approximately 10 feet high across the West Forkof Jacoby Creek. The approximately 550-foot long dam impounds areservoir with an estimated total capacity of 80 acre-feet. Thedam crest ranges from 11 to 16 feet wide and is covered by wellmaintained grass. The crest elevation ranges from 560.7 to561.4. Surficial upstream embankment materials are broken shaleand sod above the waterline. Wave erosion has created a nearvertical face, exposing the underlying riprap. The upstreamembankment slope below the waterline appears to be fairly flat.The downstream embankment slope ranges from 1.25H:lV to2.25H:lV, typically about 1.65H:lV. Weeds and light brush aregrowing between the exposed rock. Small to moderate size treesare growing in the downstream area immediately adjacent to thetoe of the dam.

A 49.4-foot wide spillway is located about themiddle of the dam. The concrete broad-crest weir located atapproximately the dam centerline has a low-flow notch approxi-mately 2.5 feet wide by 14 inches deep. Downstream of the weirthe spillway is concrete paving over rockfill. The spillwaydischarges into the stream bed at the downstream toe. A steelfoot bridge crosses the spillway on the downstream side of theweir.

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About five feet to the right of the spillway is a12-inch diameter cast iron pipe. Discharge through the ponddrain is controlled by a gate valve at the downstream end of thepipe. Pond drain discharge would impact directly upon theground surface at the toe of the dam. The inlet to this pipe isunderwater to the right of the right spillway wall.

The abutments of Echo Lake Dam merge into lawn areasof residences around the lake. There is little topographicrelief between the embankment crest and the left abutment. Theright abutment is lower than the dam crest. Large flows wouldbe expected to flow around the embankment before overtopping theembankment.

b. Location. The dam is located approximately 2.6miles northeast of East Bangor in Upper Mount Bethel Township,Northampton County, Pennsylvania. Echo Lake is located on atributary to Jacoby Creek approximately 3.3 miles upstream fromits confluence with the Delaware River. The dam site andreservoir are shown on the- USGS Quadrangle Map entitled"Stroudsburg, Pennsylvania-New Jersey" at coordinates North 40054.2', West 750 8.7'. A Regional Location Plan is enclosed asPlate 1, Appendix E.

c. Size Classification. The dam is classified as a"Small" size structure by virtue of its less than 40-foot heightand less than 1000 acre-foot total storage capacity.

d. Hazard Classification. A "Significant" hazardclassification is assigned consistent with the potential fordamage to downstream commercial and residential properties, butwith few or no lives lost.

e. Ownership. The dam is owned by the Echo LakeDevelopment Company, Inc. All correspondence should be ad-dressed to Mr. Ralph L. Schlough, President, Echo LakeDevelopment Company, Inc., RD #1, Box 1145, Bangor, Pennsylvania18013.

f. Purpose of Dam. The dam and reservoir are used forrecreational purposes.

g. Design and Construction History. Echo Lake Dam wasbuilt by the Portland Ice Company sometime before 1911. The"Report on the Condition of the Dams along Jacoby Creek," dated1912, described Echo Lake Dam as about 600 feet long, a maximumheight of 10 feet and with a spillway at the center of theembankment. The embankment was constructed of earth and fieldstones with side slopes of 1.5H:lV. The upstream face wasriprap with loose stones and the crest of the dam was eight to 10feet wide. It was noted that the reservoir area was previously

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a swamp and encompassed approximately 27 acres. The spillwaywas 49 feet long and two feet below the dam crest. It wasreported that in 1911 the spillway had been rebuilt with aconcrete upstream apron, weir crest and spillway walls. Down-stream of the weir, the spillway was timber planking overrockfilled cribs. No leakage was noted and it was concludedthat the dam appeared to be safe.

A 1919 inspection of the dam disclosed no evidenceof embankment settlement but both spillway walls were cracked,with serious cracking at the left spillway wall. The timberplanking on the downstream side of the spillway was rotted withmissing planks. A small amount of leakage was noted and thedownstream toe area of the embankment was described as being wetand swampy. A large tree on the downstream embankment slopeimmediately to the left of the spillway had blown over leaving alarge hole. It was recommended that the hole be filled withclay or impervious material. The 1921 inspection report notedthe hole filled with loose rock and stone.

Subsequent inspection reports of Echo Lake Dam notedswampy conditions downstream from the dam, seepage at variouspoints along the embankment, poor condition of the spillwayplanking and also of spillway abutments. By 1934 the timberplanking was replaced with concrete. The inspection report of1938 noted leakage to the left of the spillway and a smallstream flowing along the toe of the dam. In 1941, theinspection report noted settlement of the dam crest approxi-mately 12 feet left of the spillway. It was commented that thissettlement might be the result of leakage through the embank-ment.

h. Normal Operating Procedures. Under normal con-ditions, all flow is discharged over the spillway. Thereservoir level is lowered in the late fall by removing thewooden stop log from the notch. Periodically, the lake level islowered to permit maintenance to the bathing beach area.

1.3 Pertinent Data.

A summary of pertinent data for Echo Lake Dam ispresented as follows.

a. Drainage Area (square miles) 0.38

b. Discharge at Dam Site (cfs)Maximum Known Flood 50Tropical Storm Agnes, June 1972At Minimum Embankment Crest 134At Minimum Abutment Elevation 150

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c. Elevation (feet above MSL)(1)Top of Dam 560.7Right Abutment Area

Along dam centerline 560.1Upstream of dam centerline 560.3

Spillway Crest (average) 559.9Spillway Notch 558.6Stream Bed at Spillway 550.6

d. Reservoir (feet)Length at Normal Pool 1300Length at Maximum Pool (est) 1350

e. Storage (acre-feet)Normal Pool (est) 62Right Abutment Elevation (est) 70Top of Dam (est) 80

f. Reservoir Surface (acres)Normal Pool 20.8

g. Dam DataType Earth and rockfillLength 545 feetSlopesUpstream (above water line) Near verticalDownstream (Average) 1.65H:lV

Volume (est) 2100 cu. yd.Height (above stream bed) 10.1 feetCrest Width 11 to 16 feetCutoff UnknownGrout Curtain Unknown

h. SpillwayType Concrete over rockElevation at Crest (Average) 559.9 feetNotch 558.6 feetLength 49.4 feet

i. Pond DrainType 12-inch conduit with

gate valve at down-stream end.

Length UnknownInlet Invert Elevation UnknownOutlet Invert Elevation 551.9

(1) Right end of spillway weir assumed 560 feet from USGSmap, all other elevations relative.

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SECTION 2ENGINEERING DATA

2.1 Design.

a. Availability. There are no original engineeringdata for Echo Lake Dam. A summary of Subsequent evaluation datais presented on the checklist attached as Appendix B. Principaldocuments containing pertinent data used for this report arelimited to periodic state inspection reports, correspondence andphotographs. All of these data are contained within theDepartment of Environmental Resources (DER) files.

b. Design Features. A plan view and section of the damare presented in Appendix E and profile is presented in AppendixA. This information was obtained from visual inspection. Asummary of the design features is included in Section 1.3.

2.2 Construction.

Nothing is known concerning the construction his-tory beyond the information given in Section 1.2, paragraph g.

2.3 Operational Data.

There are no operational records maintained for thisdam beyond the periodic applications for permits to draw downthe reservoir level.

2.4 Evaluation.

a. Availability. All information presented herein wasobtained from DER files and supplemented by conversations withthe owner's representative.

b. Adequacy. The available data are not adequate toevaluate the engineering aspects of this dam.

c. Validity. There is no reason to question thevalidity of the limited available data.

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SECTION 3VISUAL INSPECTION

3.1 Findings.

a. General. The observations and comments of the fieldinspection team are contained in a checklist presented inAppendix A and are summarized and evaluated in the followingsubsections. In general, the appearance of the facilitiesindicates that the embankment and spillway is currently in faircondition and the outlet works are in poor condition.

b. Dam. The vertical alignment of the dam crest was

checked and the profile is !;hown -,! Sheet 5B, Appendix A. Therewere no distortions in al iqnm' nt or grade that would beindicative of movement within the embankment cr foundation. The

crest elevation ranges from <'0.7 to 561.4. The minimumelevation of 560.1 is, in tho r iqht abutment area beyond theembankment. The minlmum elvat i( in the fraqht abutment areaupstream of the daim which must I e overtoppe before water canflcow over the riqht -butment is 560.3. The crest width rangesfrom Li to 16 feet and sopports a weil maintained growth ofgrass. It was reported that broken shale covered with topsoiland seeded, has been placed on lo: areas of the embankment crestand on damaged areas at the waterline. A bench, created by waveerosion, was observed at the cunmmvr water line on the upstreamembankment face, occasionally exposing underlying riprap. Aflatter upstream embankment slope covered with broken shale wasobserved below the water level.

Light brush and weeds were growing between rocks onthe downstream slope. The downstream slope is about 1.65:1V.Steeper slopes (1.25H: IV) occur in areas appearing to havemore boulders and cobbles exposed. Flatter slopes (2.25H:lV)were observed as the downstre,3m face transitioned into theabutments.

Midway between the spillway and left abutment at thedownstream toe w,, - area with lush grass and standing water.Another wet area with pondedl water an(] -watipy vegetation wasobserved auproximately 50 feet to the left of the spillway.This area extended to the spillway and about 50 feet downstream.Approximately 75 feet to the riqht of the soillway, another wetarea was noted with standing water and lush grass. Near thedownstream toe and slightlv U,) th,: rslope of tne dam there were.;everal trees, qrowj n i r -An-i i '; in ;j 7r. I) to 12 irch'S indiameter.

c. Appurtenant Structures.

1. Spillway. The spillway is a concrete structure49.4 feet wide. The upstream slope is concrete and underwater.The downstream slope is concrete over rock fill. A concreteweir 18.5 inches wide and 16 inches high controls spillwaydischarge, Plate 3, Appendix E. The weir crest ranges inelevation from 560 to 559.8 and appears to be in good condition.Flow through a notch approximately 30 inches wide by 14 inchesdeep is controlled by a wooden stop log. A foot bridge acrossthe spillway is about 18.5 inches above the weir crest. The~original concrete upstream spillway walls were extended as

diving board platforms and the phases of construction can beseen. The spillway walls are cracked. Only the anchor boltsremain. The largest crack in the right spillway wall isapproximately one-inch wide, Photograph 5. The downstreamspillway walls also showed occasional cracks. The downstreamslao of the spillway has a five-inch step at about its mid-height. There are several cracks noted in the spillway slab andpieces of concrete have apparently been broken off at the lowerend of the slab. Cobbles and boulders underlie the spillwayslao, Photograph 7. The spillway discharges directly into thedownstream channel. No evidence of channel erosion or under-mining of the spillway resulting from spillway discharge wasnoted.

2. Outlet Works. A 12-inch diameter metal pipeexits the downstream face of the dam approximately five feet tothe right of the spillway. Discharge from the pipe impactsdirectly upon the ground surface at the downstream embankmenttoe. It was reported that the upstream end of this pipe is nearto the right spillway wall and is protected by a screen. Duringthe inspection, the downstream gate valve was exercised andfound to be functional although the valve did not seatcompletely when in a closed position. Also a small crack wasnoted in the upper valve case such that small streams of waterwere spurting out. The crack was reported to be at least twoyears old.

d. Reservoir. The side slopes of the reservoir are ata moderate to gentle slope and are vegetated to the water's edgewith grass and trees. There was very little debris noted alongthe shore line and very little sediment was observed enteringthe lake. The maximum depth was reported as six feet indicatingsedimentation within the reservoir.

e. Downstream Channel. The channel downstream from thedam flows through a broad, flat, wooded, and occasionallyswampy, flood plain. Immediately downstream from the dam, thechannel is about 11 feet wide and the banks are approximatelyone-foot high. The valley gradient in the vicinity of the dam

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is about 0.008. There are a few cottages located on the floodplain downstream of the dam. The closest residence isdownstream of the embankment near the left abutment and has afloor level at approximately the dam crest elevation. About3000 feet downstream from Echo Lake is Lake Poco, DER No. 48-4,which is formed by an earth dam approximately six feet high.About 1000 feet downstream from Lake Poco, the stream valley isconstricted by an abandoned railroad embankment, such that floodflows would be confined to a small portion of the valley where afew residential dwellings are located. With the constriction onthe valley, it is possible that a failure of Echo Lake Dam and,possibly, a consequent failure of Lake Poco Dam would causedamage to homes and buildings. Since no loss of life isenvisioned, a "Significant" hazard classification for thisstructure is indicated.

3.2 Evaluation.

In summary, the visual inspection of the damdisclosed no evidence of incipient failure of the embankment.The embankment is judged to be in fair condition consistent withthe trees and brush on the downstream slope and the wet andponded areas at the downstream toe. Consistent with the reportsin the DER file, this seepage is assessed to represent anapparently long-term condition which only requires monitoringfor development of turbidity and increase in flow. Although theupstream embankment slope is damaged at the waterline, reportedmaintenance practices (see Section 4) have resulted in a minimum11-foot top width, more than adequate for a 10-foot high dam.

The spillway structure appears to be in generallyfair condition. This assessment is based upon the lack of anylarge scale dislocations or structural deficiencies althoughspillway cracking should be sealed to prevent further deteriora-tion. The channel immediately downstream of the spillway shouldbe checked after large flows for signs of channel erosion orspillway undermining. The outlet works are in poor conditionconsistent with the cracked valve case and the location of thevalve at the downstream end of the outlet conduit.

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SECTION 4OPERATIONAL PROCEDURES

4.1 Procedures.

Normal operating procedures of Echo Lake Dam do notrequire a dam tender. The reservoir level is lowered during thewinter by removing the stop log from the spillway notch. Allflow is discharged over the spillway into a tributary of JacobyCreek. There is no minimum downstream flow requirement.

4.2 Maintenance of Dam.

Dam maintenance provided by the Owner consists ofmowing the grass and removing debris as required. Periodically,additional material is dumped on the upstream embankment face torestore the slope at the water line and protect against furtherwave erosion.

4.3 Maintenance of Operating Facilities.

The operating facilities associated with thisstructure are the stop log and the gate valve on the outletconduit. Maintenance to these facilities is provided as neededand the valve is kept oiled and operational. The gate valve isscheduled for repair this spring (1981). The Owner provides therequired maintenance.

4.4 Warning Systems in Effect.

There are no formal warning systems or proceduresestablished to be followed during periods of exceedingly heavyrainfall. If potentially dangerous conditions are observed, theOwner's representative reported that the local police would benotified.

4.5 Evaluation.

It is judged that the current operating procedure,which does not require a dam tender, is a realistic means ofoperating the relatively simple control facilities of Echo LakeDam.

There are no written operational or maintenanceprocedures or any type of warning system. Maintenance andoperating procedures should be developed, including a checklistof items to be observed, operated, and inspected on a regularbasis.

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Since a formal warning procedure does not exist, oneshould be developed and implemented during periods of extremerainfall. This procedure should consist of a method ofnotifying residents downstream that potentially high flows areimminent or dangerous conditions are developing.

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SECTION 5HYDROLOGY/HYDRAULICS

5.1 Evaluation of Features.

a. Design Evaluation Data. There are no originaldesign data for this construction nor subsequent evaluation datafor the existing spillway section. The small irregularly shapedwatershed is about 1.1 miles long and 0.3 mile wide having atotal drainage area of about 0.38 square mile. Elevations rangefrom a high of about 788 in the upper reaches to the normalreservoir level of about 559.9. The watershed is about 65percent wooded with moderate residential development. Whilesome residential development has recently occurred within thewatershed, runoff characteristics are not expected to changesignificantly in the near future.

In accordance with criteria established by Federal(OCE) Guidelines, the recommended Spillway Design Flood for this"Small" size dam and "Significant" hazard classification is the100 Year Flood to one half the Probable Maximum Flood. Based onthe relatively small capacity of the reservoir and the fact thatno loss of life is likely during the failure of this structure,the 100 Year Event has been selected as the Spillway DesignFlood.

b. Experience Data. No reservoir level records orrainfall records are maintained for this dam by the Owner.During Tropical Storm "Agnes" in 1972, the reservoir level wasreported to just barely reach the top of the right abutment.

c. Visual Observations. At the time of the inspectionthere were no conditions observed that would indicate a reducedspillway capacity during an extreme event. Overtopping of theright abutment area could be detrimental to the embankment ifdischarge through the abutment area flows against the downstreamtoe causing erosion. Other observations regarding the conditionof the downstream channel, spillway and reservoir are located inAppendix A and discussed in greater detail in Section 3.

d. Overtopping Potential. The overtopping potentialof this dam was estimated using the HEC-1 Dam Safety VersionComputer Program. A brief description of the program isincluded in Appendix D. Calculations for this investigationindicate a maximum spillway capacity of 134 cfs with the stoplog in place and 151 cfs without the stop log when the reservoirlevel is at 560.7, the minimum embankment elevation. Spillwaydischarge is reduced to 33 and 50 cfs, respectively, when thereservoir level is at 560.3, the elevation at which the rightabutment area overtops. The 100 year peak inflow rate wascalculated by the computer program as about 188 cfs. This value

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was checked against the peak inflow value as determinedaccording to procedures contained in "Regional Frequency Study,Upper Delaware and Hudson River Basins, New York District" whichresulted in an estimated peak inflow value of about 197 cfs.The computer program indicates that the 100 Year Event will notovertop the embankment. However, the low area at the rightabutment, noted on Sheet 5B, Appendix A, will overtop by about0.3 feet for an estimated five hours with the stop log in thespillway notch. The abutment will not overtop if the notch isleft open.

e. Spillway Adequacy. The reservoir level with thespillway notch closed is considered the normal pool level. Thespillway is considered to be "Inadequate" as it will not passthe spillway design storm while dam outflow is confined todesigned spillways. If the spillway notch is permanently open,the spillway would be considered "Adequate".

f. Downstream Conditions. Immediately downstream ofthe dam are a few cottages located on the flood plain. About3,000 feet downstream of Echo Lake is Lake Poco Dam whosespillway is 36.5 feet wide and 23 inches deep with an estimatedmaximum capacity of 210 cfs. The top of Lake Poco Dam is abouttwo and one-half feet above the first floor of a housedownstream of the dam. About 1,000 feet downstream from LakePoco Dam the stream valley is constricted by an abandonedrailroad embankment, thus, flood flows would be confined to asmall portion of the valley where residential dwellings arelocated. It is considered likely an Echo Lake Dam failure andpossibly a Lake Poco Dam failure would cause damage to the homesand buildings. Since no loss of life is envisioned, a"Significant" hazard classification for this structure isindicated.

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SECTION 6STRUCTURAL STABILITY

6.1 Evaluation of Structural Stability.

a. Visual Observations. Visual observations indicateno evidence of existing or pending embankment instability otherthan that which would result from overtopping. The visualportions of the upstream face and downstream face of the damappeared to be in fair condition. The concrete spillwaycracking does not appear to be serious. The cracks should besealed to prevent further damage. Although there is no energydissipator at the spillway discharge, no channel erosion orspillway undermining was noted. The area should be checkedafter large spillway discharges for signs of undermining orerosion.

Evidence of seepage was observed during the visualinspection. Seepage has been noted in the state inspectionreports since 1919. As no evidence of migration of finesthrough the embankment was noted, the seepage is assessed torepresent a long-standing condition for this dam.

b. Design and Construction Data. No design or con-struction data exist other than the observations and reportsconcerning spillway reconstruction in the Department of Environ-mental Resources files. All data concerning the physicalfeatures of the dam were obtained from these reports, visualobservations of the dam and conversations with the Owner'srepresentative.

c. Operating Records. There are no operational recordsfor this structure.

d. Post-Construction Changes. As discussed in Section1.2, paragraph g, post-construction changes to Echo Lake Dam arelimited to reconstruction of the spillway. No reference is madeto a pond drain until 1923, therefore, the 12-inch pond drainmay not be original.

e. Embankment Stability. There were no embankmentstability evaluations in the files. Based on the low damheight, fairly wide crest (11 feet minimum), even when combinedwith fairly steep (up to 1.25H:lV) embankment slopes, the damappears to be stable at the present time, provided thatsignificant overtopping does not occur and that seepage con-ditions do not change.

f. Seismic Stability. The dam is located in seismiczone 1. Normally it can be considered that if a dam in this zoneis stable under static loading conditions, it can De assumed

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safe for any expected earthquake conditions. Since the dam isqualitatively assessed to be stable at the present time understatic loading conditions, it can also reasonably be consideredto be stable under seismic loading conditions.

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SECTION 7ASSESSMENT/REMEDIAL MEASURES

7.1 Dam Assessment.

a. Evaluation. Visual inspection indicates that EchoLake Dam and spillway is in fair condition. The outlet worksare in poor condition.

In accordance with criteria established by Federal(OCE) Guidelines, the recommended Spillway Design Flood for this"Small" size dam and "Significant" hazard classification is the100 Year Flood to one half the Probable Maximum Flood. Based onthe small capacity of the reservoir and the fact that no loss oflife is likely during failure of the structure, the 100 YearEvent has been selected as the Spillway Design Flood.

Hydrologic and hydraulic computations presented inAppendix D indicate the spillway structure is not capable ofdischarging the 100 Year Event while confining dam outflow tothe designed spillway. With the spillway notch closed (normalpool level), the right abutment area overtops by about 0.3 feetfor an estimated five hours. Thus the spillway is considered"Inadequate". If the spillway notch is permanently open, thespillway would be considered "Adequate".

b. Adequacy of Information. The combined visualinspection and simplified calculations presented in Appendix Dwere sufficient to indicate that further investigations arerequired for this structure if the use of stop logs iscontinued.

c. Urgency. It is recommended that the measurespresented in Section 7.2 be implemented as specified.

7.2 Remedial Measures.

a. Facilities. It is recommended that the followingmeasures be undertaken immediately. Item 1 should be performedunder the supervision of a Registered Professional Engineerexperienced in the design and construction of dams.

(1) The right abutment area would be the first area toexperience overtopping; it should evaluated fromthe standpoint of functioning as an emergencyspillway. Alternatively, the stop log could beremoved permanently.

(2) Cracks in spillway and slab walls should be sealed

to prevent further damage.

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(3) All trees and brush should be removed from thedownstream embankment face.

(4) The pond drain pipe should be fitted with an opera-tional control device at its upstream end.

(5) Seepage through the dam should be monitored for thedevelopment of turbidity and increase in quantity.

b. Operation and Maintenance Procedures. Because ofthe potential for property damage in the event of a failure, aformal procedure of observation and warning during periods ofhigh precipitation should be developed and implemented for thisfacility. This procedure should be coordinated with localauthorities and should include a method of warning downstreamresidents that high flows are expected. In addition, anoperation and maintenance procedure should also be developed toinsure that all pertinent items are carefully inspected on aregular basis and maintained in the best possible condition.

-16-

APPE ND[X

A

I

Sheet I of II

CHECK LIST

VISUAL INSPECTION

PHASE I

Name Dam Echo Lake Dam

County Northhampton State Pennsylvania

NDI# PA 00957 DER# 48-3 Type of Dam Earth and Rockfill

Hazard Category Significant

Date(s) Inspection trov. 20, 1980

Weather Sunny Temperature 40's

Pool Elevation at Time of Inspection 55-.9 M.S.L.

Tailwater at Time of Inspection 552.7 M.S.L.

Inspection Personnel:

Mary F. Beck (Hydrologist) Vincent McKeever (Hydrologist)

Richard E. Mabry (Geotechnical) John H. Frederick, Principal (2/9/81)

Raymond S. Lambert, (Geologist)

Mary F. Beck Recorder

Remarks:

Mr. Ralph L. Schlough, President of Echo Lake Development Company,

Inc., was on site and provided assistance to the inspection team.

Sheet 2 of II

CONCRETE/MASONRY DAMS

VISUAL EXAMINATION OF OBSERVATIONS REMARKS OR RECOMMENDATIONS

ANY NOTICEABLESEEPAGE N/A

STRUCTURE TOABUTMENT/EMBANKMENTJUNCTIONS N/A

DRAINS NIA

WATER PASSAGES N/A

FOUNDATION N/A

'A-

Sheet 3 of 11

CONCRETE/MASONRY DAMS


SURFACE CRACKSCONCRETE SURFACES /A

STRUCTURAL CRACKING NIA

VERTICAL ANDHORIZONTALALIGNMENT N/A

MONOLITH JOINTS N/A

CONSTRUCTIONJOINTS N/A

Sheet 4 of II

EMBANKMENT


SURFACE CRACKS None observed

UNUSUAL MOVEMENT None observedOR CRACKING AT ORBEYOND THE TOE

SLOUGHING OR None observedEROSION OFEMBANKMENT ANDABUTMENT SLOPES

VERTICAL AND Vertical alignment shown on Sheet 5B.HORIZONTAL ALIGN-MENT OF THE CREST

RIPRAP FAILURES Riprap at water line has been covered with smallshale fragments, covered with soil and grassestablished. Upstream slope has a one-foot benchat water line. Waves have eroded shale andexposed some underlying riprap.

Sheet 5 of 11

EMBANKMENT


Vegetation The crest is protected by a good grass cover.The downstream s.ope is brush and tree covered.Some brush has been cut.

JUNCTION OF Good con'itionEMBANKMENTAND ABUTMENT,SPILLWAY ANDDAM

ANY NOTICE- Yes, see sheet 5AABLE SEEPAGE

STAFF GAGE NoneAND RECORDER

DRAINS None

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Sheet 6 of i

OUTLET WORKS


CRACKING AND N/ASPALLING OFCONCRETESURFACES IN OUTLETCONDUIT

INTAKE STRUCTURE Upstream end of conduit is under water and couldnot be seen.

OUTLET STRUCTURE A 12-inch gate valve is at the downstream end ofthe conduit. The gate valve operated easily.Valve does not completely seat. The upper partof the Crane valve was cracked with water jettingout.

OUTLET CHANNEL The conduit discharges into the channel below thespillway,

EMERGENCY GATE The above.

Sheet 7 of II

UNGATED SPILLWAY


CONCRETE WEIR The concrete broad crested weir has a 30-inchwide, 14-inch deep low flow notch. At the timeof the inspection, a w ooden board was in thenotch. The lake level is lowered for the wintermonths.

APPROACH CHANNEL None

DISCHARGE CHANNEL The spillway discharges directly into the down-stream channel.

BRIDGE AND PIERS A foot bridge is 18.5 inches above the concreteweir. The bridge is supported by two sets ofsteel angle members.

-I

Sheet 8 of II

GATED SPILLWAY


TYPE N/A

APPROACH CHANNEL N/A

DISCHARGE CHANNEL N/A

BRIDGE AND PIERS N/A

GATES AND N/A

OPERATIONEQUIPMENT

Sheet 9 of II

INSTRUMENTATION


MONUMENTATION/ NoneSURVEYS

OBSERVATION WELLS None

WEIRS None

PIEZOMETERS None

OTHER None

Sheet 10 of II

RESERVOIR


SLOPES The reservoir side slopes are moderate andgenerally grassed to water's edge. Very littledebris along shore line.

SEDIMENTATION Little sediment is coming into the lake.

WATERSHED About 65 percent wooded with moderate residentialdevelopment.

IASheet II of II

DOWNSTREAM CHANNEL


CONDITION The downstream channel flows through a broad,(OBSTRUCTIONS, wooded flood plain. The channel is about 10 feetDEBRIS, ETC.) wide with one-foot high banks.

SLOPES The valley gradient is approximately 0.013.

APPROXIMATE NO. About 3000 feet downstream of Echo Lake Dam isOF HOMES AND Lake Poco, a 6 foot high earth dam. About 1000POPULATION feet downstream of Lake Poco, the downstream

valley is constricted by an abandoned railroadembankment, thus flood flows are confined to asmall portion of the valley and it is consideredlikely an Echo Lake Dam failure, and possibly aLake Poco failure, would cause additional damageto homes and buildings.

APPENDIX

IS

J1..

Sheet I of 4

CHECK LISTENGINEERING DATA

DESIGN, CONSTRUCTION, OPERATIONPHASE I

NAME OF DAM Echo Lake Dam

NDINO. PA 00957 DER NO. 48-4

ITEM REMARKS

AS-BUILTDRAWINGS None available

REGIONALVICINITYMAP Plate 1, Appendix E

CONSTRUCTIONHISTORY

See text, Section 1.2

TYPICAL SECTIONSOF" DAM None available

OUTLETS - PLAN

DETAILS

CONSTRAINTS No data available

DISCHARGE RATINGS

Sheet 2 of 4ITEM REMARKS

RAINFALL/RESERVOIR RECORDS

None maintained by Owner

DESIGNREPORTS

None

GEOLOGYREPORTS

See Appendix F

DESIGN COMPUTATIONSHYDROLOGY & HYDRAULICS No original studies, seeDAM STABILITY Appendix D for Hydrology/

SEEPAGE STUDIES Hydraulics evaluation.

MATERIALS INVESTIGATIONSBORING RECORDSLABORATORY None

FIELD

POST CONSTRUCTIONSURVEYS OF DAM

None known

Sheet 3 of 4I i EM REMARK5

BORROW SOURCES Unknown

MONITORINGSYSTEMS None

:-! MODIFICATIONSM F ILimited to replacement of

spillway

HIGH POOLRECORDS None

POST CONSTRUCTIONENGINEERINGSTUDIES AND None except state damREPORTS inspection reports

PRIOR ACCIDENTS ORFAILURE OF DAMDESCRIPTION NoneREPORTS

MAINTENANCEOPERATIONRECORDS

None

A

Sheet 4 of 4II .M REMARKS

SPILLWAY PLAN

SECTIONSSee Appendix E

DETAILS

OPERATING EQUIPMENTPLANS AND DETAILS

None

MISCELLANEOUSThe following are located inDER files.

I. "Report on the Conditionof the Dams along JacobyCreek", Dated April 9, 1912.

2. "Inspection Report Dams"from 1929 to 1964.

3. Correspondence between thestate and various ownersof the dam.

4. Several "Application forPermit to Draw Dam"

5. Seven black and white photo-graphs.

Ik

APPENDIX

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PHOTOGRAPH NO.

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ROCK FILL- SHOWS 'IIROtJGI SNU.

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APPENDIX

D

ECHO LAKE DAM Sheet I of 14CHECK LIST

HYDROLOGIC AND HYDRAULICENGINEERING DATA

DRAINAGE AREACHARACTERISTICS About 65% wooded with moderate residential development

ELEVATION NORMALPOOL (STORAGE CAPACITY): 559.9* feet (62 Acres-feet)

ELEVATION TOP FLOOD CONTROL POOL

(STORAGE CAPACITY): 560.3 feet (70 Acre-feet)

ELEVATION MAXIMUM DESIGN POOL: -

ELEVATION TOP DAM: 560.7 feet

SPILLWAY

a. Elevation 560 feet

b. Type Concrete weir, with concreted fockfill chute

c. Width 49.4 feet

d. Length 36.5 feet

e. Location Spillover Approximately 330 feet from right abutment

f. Number and Type of Gates None

OUTLET WORKS:

a. Type 12-inch pipe with gate valve at downstream end

b. Location adjacent to right spillway wall

c. Entrance inverts Unknown, under water

d. Exit inverts 541.9 feet

e. Emergency draindown facilities the 12-inch pipe

HYDROMETEOROLOGICAL GAGES:

a. Type None

b. Location N/A

c. Records N/A

MAXIMUM NON-DAMAGING DISCHARGE: Not determined

*Right end of weir estimated as 560.0 feet from USGS map,

all other elevations relative.

. . - . -_ .

ECHO LAKE DAMCHECK LIST Sheet 2 of 14

HYDROLOGIC AND HYDRAULIC

DRAINAGE AREA: ( I ) 0.38 sq. miles

100 YEAR PRECIPITATION (2)

30 MINUTES 2.3 inches

I Hour 3.0

2 Hours 3.7

3 Hours 4.1

6 Hours 5.0

12 Hours 6.0

24 Hours 7.0

SNYDER HYDROGRAPH PARAMETERS: (3 )

Zone 1

CpCt 0.45, 1.23

L (4) 1.37 miles

La (5 ) 0.61 miles

tp=Ct (L" LCC)0.3 1.16

SPILLWAY CAPtiITY AT MAXIMUMWATER LEVEL 134 cfs

(I) Measured from USGS maps.(2) TP 40 - Rainfall Frequency

Atlas of the United States(3) Information received from Corps of Engineers, Baltimore District.(4) Length of longest water course from outlet to basin divide, measured from USGS maps.(5) Length of water course from outlet to point opposite the centroid of drainage area,

(see Plate I, Appendix E) measured from USGS mops.(6) See Sheet 11 of this Appendix.

SHEET I of 14

HEC-l, REVISEDFLOOD HYDROGRAPH PACKAGE

The original "Flood Hydrograph Package" (HEC-l),developed by the Hydrologic Engineering Center, Corps ofEngineers, has been modified for use under the National DamInspection Program. The "Flood Hydrograph Package (HEC-l),Dam Safety Version", hereinafter referred to as, HEC-I, Rev.,has been modified to require less detailed input and toinclude a dam breach analysis. The required input is obtainedfrom the field inspection of a dam, any available design/eval-uation data, relatively simple hydraulic calculations, orinformation from the USGS Quandrangle maps. The input formatis flexible in order to reflect any unique characteristics ofan individual dam.

HEC-1, Rev. computes a reservoir inflow hydro-graph based on individual watershed characteristics such as:area, percentage of impervious surface area, watershed shape,and hydrograph characteristics determined from regional cor-relation studies by the Corps of Engineers, Baltimore Dist-rict. The inflow is routed through the reservoir usingspillway discharge data obtained from the field inspection ordesign data. Flood storage capacity is determined from USGSmaps or design information and verified by the field inspec-tion. In the event a spillway cannot discharge 0.5 PMFwithout overtopping and failure of the dam, downstream channelcharacteristics obtained from the field inspection and USGSmaps are inputed and flows are routed downstream to the damagecenter and a dam breach analysis is performed. If the 100year event is selected as the appropriate spillway designflood, the peak inflow value is correlated with other studiesby adjusting hydrograph parameters.

Included in this Appendix are the HEC-l, Rev.pertinent input values and a summary print-out tables.

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APPENDI X

F

ECHO LAKE DAM

SITE GEOLOGY

Echo Lake Dam is located in the Great Valley section

of the Valley and Ridge physiographic province. As shown on

Plate F-1, the dam site and much of the surrounding areas are

underlain by glacial deposits of Pleistocene age. These

deposits consist of varying amounts of gravel, sand, silt and

clay. Locally, in the vicinity of the dam, concentrations of

boulders were noted during the field inspection. No bedrock

exposures were observed near the dam site. Slate and siltstone

deposits of the Martinsburg Formation are exposed elsewhere in

the area, however, regional geologic mapping indicates the dam

site to be underlain by the limestone and dolomite of the

Allentown Formation. Consistent with the variable composi-

tional character of glacial deposits, there exists the potent-

ial for reservoir seepage through these deposits in addition to

seepage along the bedrock interface if bedrock is in fact

relatively close to the surface.

-1-

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\~~~~~ST 2 GEOLOG~*<,*ICA MAP..,i..

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F7 N T.I .NO. A00 -57 ORT AMPT N C UNT

DATAOBTINEDFRO U.SGEOOGICL SRVEMA G-14

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