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State of Maine
Department of Defense, Veterans, and Emergency Management
Maine Emergency Management Agency
Office of Dam Safety
Maine Dam Safety Program
Whitney Irrigation Pond Dam
Draft Hazard & Condition Report
(DRAFT)
Prepared for;
The State Dam Inspector
Prepared by;
David Vitali EI
72 State House Station
45 Commerce Drive
Augusta, Maine 04333
Phone: 207-624-4400
2. #1011 Whitney Irrigation Pond Dam
Hazard & Condition Report
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Cover Letter
To: State Dam Inspector
From: MEMA Civil Engineering Intern
Date: September 23, 2016
RE: #1011 Whitney Irrigation Pond Dam, Corinna, Penobscot Co.
Sir,
Attached is a copy of my hazard and condition report for this project. The report is based on
visual inspections, field surveys, downstream hazard inspections, and a hydraulic study of the
dam’s overtopping potential and the downstream impact of a theoretical breach.
Based on the findings in the attached report:
My hazard assessment of the project, according to MRSA 37B, Chapter 24, “Dam Safety,” is that
the dam should be registered in MEMA’s files as a “low” hazard dam.
My condition assessment is that the dam is in unsatisfactory condition.
In order to improve the safety of the Whitney Irrigation Pond Dam, I make the following
recommendations:
For the dam owner:
1. Remove all brush and all trees with a diameter of less than 9” from the downstream face
of the dam.
2. Clear the spillway and its channel of vegetation.
3. Establish a maintenance schedule to prevent further vegetation growth on the dam and
in the spillway.
4. Place rip rap along the waterline on the dam to prevent wave erosion.
5. Hire an engineer to investigate the possible settlement within your dam.
For the State Dam Inspector:
I Recommend that the dam be classified as a “low” hazard to the Operations Director of MEMA.
Please do not hesitate to contact me with any further questions or concerns about my
assessments or the contents of this report.
David Vitali
MEMA Civil Engineering Intern
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Hazard & Condition Report
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CONTENTS
LETTER TO STATE DAM INSPECTOR...........................................................................................2
CONTENTS..................................................................................................................................3
PREFACE.....................................................................................................................................4
REPORT................................................................................................................................... 5-9
ABBREVIATIONS.......................................................................................................................10
FIGURE 1 – DOWNSTREAM AREA MAP....................................................................................11
FIGURE 2 – WATERSHED AND IMPOUNDMENT MAP..............................................................12
FIGURE 3 – LOCATION OF DEFECTS .........................................................................................13
ATTACHMENTS.............................................................................................................................
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Hazard & Condition Report
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PREFACE
The WIPD is one among a handful of unregistered dams to have been discovered by MEMA during a
random visual inspection of aerial imagery. The purpose of this report is to implement MDSL, which
ensures all jurisdictional dams in Maine are constructed, maintained and operated in a safe manner.
The law specifies that dams be assessed for both “hazard” and “condition.”
The “hazard” classification of a dam is a measure of its “potential” to cause downstream damage if it
failed, which has nothing to do with its “condition.” “High” hazard dams are a threat to human life,
“significant” hazard dams are a threat to downstream property, and “low” hazard are unlikely to be a
threat to either. The law requires “hazard” assessments every six years. Dams classified “high” and
“significant” hazard must have EAPs and be inspected for condition every two and four years,
respectively. The “hazard” of this dam was assessed by visual inspection of the dam’s basin and
downstream watercourse.
The “condition” of this dam was determined by the visual inspection of the top, upstream and
downstreamfacesof the dam,the abutments, the spillway, the toe and groin areas. Inspection sought
adverse defects which would affect the stability of the structure such as; root penetration, surface s
covered by vegetation, material deterioration, settlement, misalignment, seepage, piping, spillway
blockage, missing control features and mis-operation. The dam’s potential for overtopping was
assessed,butitsdesign,stability, construction, operation, and maintenance was not. No sampling and
testingof materials,foundationinvestigation,installationof instrumentationor the testing of gates and
spillways was done. Figure 3 contains photographs of defects on the dam.
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Hazard & Condition Report
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DAM OWNER AND COUNTY EM DIRECTOR
Dam Owner:
Roger Whitney
438 Exeter Road
Corinna, ME 04928
Tel: (207) 745-2747
Penobscot County EM Director:
Michelle Tanguay
97 Hammond Street
Bangor, ME 04401
Tel: (207) 945-4750
DESCRIPTION OF DAM
The WIPD is a 16’ highand 460’ wide earthembankmentdamlocated off of Exeter Road in the Town of
Corinna, ME. The dam is owned by Roger Whitney and it is used for irrigation. There is a 13’ wide road
that runsalong the topof the dam and itis neitherfencednorposted.The damhasone spillwaylocated
on the rightside of the dam.A spillway channel directs water to the downstream as shown in Figure 3.
At NP the WIPD reservoir has an area of 18 acres and a normal storage of 125 acre feet. The watershed
has an area of 1.2 square miles as shown in Figure 2. The fill and foundation of the dam are unknown.
MEMA has no design or construction records on file.
Historyof the dam isbasedon anecdotal evidence from the dam owner and NRCS, as follows. The dam
was constructed in the 1950’s as a farm pond. Originally, a drop inlet pipe served as the primary
spillway.The inletpipe was filled with concrete 15 years ago when it showed signs of failure. The dam
owner worked with the NRCS to install a spillway on the right side of the embankment, as shown in
Figure 3. The NRCS(formallySCS) constructedmanyearthembankmentdamswithadropinletpipe and
an outlet pipe at the toe around the State of Maine. The Whitney Dam fits the description of an SCS
dam.
BREACH IMPACT
A breach of the dam is likely to impact the area shown on the map in Figure 1. The downstream of the
dam intersects with Exeter and West Barker Road. Exeter Road has an adequate culvert to pass a fair
weather breach. The culvert on West Barker Road is totally inadequate to pass a fair weather breach
and will likely wash out.
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Hazard & Condition Report
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FIELD INSPECTIONSAND SURVEYS
I made a total of four trips to see the Whitney dam during the summer of 2016. Pertinent inspection
photographs are included in Attachment 1.
06/06/2016 – Reconnaissance
I visitedthe damwiththe ASDI to performa reconnaissance of the dam.We walkedalongthe top of the
dam and onthe downstreamface. Additionally, we observed the culvert at Exeter Road. We made the
following observations:
Dam
A. The downstream face is totally covered in vegetation.
B. The spillway is overgrown with vegetation.
C. “Beaching,” or wave erosion, has occurred on the upstream slope of the dam.
D. There are small holes in the ground along the on the upstream slope just above water level.
E. Two pipes are located on the upstream slope of the dam.
F. A 24 inch diameter pipe is located at the bottom of the dam near the toe.
The small holes in Observation D are likely caused by animal burrowing and are of no immediate
concern. Sinkholes onearthembankmentdamsindicate structural failure within the embankment and
should be monitored if more significant holes appear.
The pipes mentioned in Observation E most likely pump stored water to the adjacent fields.
There was no flow through the outlet pipe during our observation, which supports the anecdotal
evidence describing the past use of an inlet pipe. The absence of flow through the pipe supports the
claimthat the pipe hasbeen filled with concrete. The inlet pipe was not visible during this inspection.
Exeter Road
A. Two properties are located near the culvert: 519 and 532 Exeter Road.
B. A buried cable is posted above the inlet of the culvert.
06/09/2016 – Survey
The survey was conducted on a cloudy, windy afternoon with a temperature of 58°F.
I performedatacheometricsurveyof the dam with the assistance of the SDI and ASDI. We established
three stationswhere there were clearlinesof sighttopointsof interestalongthe dam,labeled “A”, “B,”
and “C.” Station locations can be seen on the drawing in Attachment 2. The survey crew set up a
theodoliteoverthe stationsandsightedanglesanddistancesatvariouspointsusinga level staff. Stadia
linesinthe theodolite wereusedto record distances. Measurements were taken along the road, along
water level, through the spillway, on the bridge, along the spillway channel, and at the outlet pipe.
06/22/2016 – Survey
The survey was conducted on a cloudy afternoon with a temperature of 72°F and a wind speed of 3
mph.
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Hazard & Condition Report
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I returned to the dam with the SDI and another EI to take additional measurements of cross section
elevations.The surveycrewestablishedtwomore stations,labeled “D” and “E” in Attachment 2. A total
stationwasused in place of a theodolite to record distances and angles. A reflective prism was placed
each pointinthe place of a level staff. Vegetationthroughthe sectionwasremoved in order to obtain a
clearline of vision forthe reflective prism.Itbegantorainonce we had collected points through a cross
section and we packed up the equipment immediately.
07/12/2016 – Survey
The surveywas conducted ona clearafternoon with a temperature of 81°F and a wind speed of 5 mph.
I realizedthatIwas missingnecessaryinformationafterIbegan modelingthe damforhydraulicanalysis.
I returnedto the dam withthe ASDI usinga total stationto measure points. We reshot the points taken
during the first survey and took three lines through the spillway using a total station. Later, I selected
the best representation of the spillway, as seen on Attachment 2.
Additionally,we visitedthe culvertlocatedat155 WestBarker Road and spoke withthe propertyowner.
Photographsfromthe site visitare includedonpage 3 of Attachment1. We measuredthe dimensionsof
the culvert, but did not conduct a formal survey.
07/21/2016 – Accuracy Check
The surveywas conducted ona cloudyafternoonwithatemperature of 85°F and a windspeedof 7mph.
I had notclosedout the stations duringprevioussurveys andIwasquestioning the accuracy of my data.
I decided to return to the dam to perform an accuracy check with the ASDI and an EI. I set up a total
stationovereachstationand shotall stationsinsight. The accuracy of the survey was determined to be
sufficiently accurate for a hydraulic analysis, but not for foundation or structural analysis. Two
geometriccheckswere usedtodetermine the accuracyof the horizontal angles. The triangle formed by
Stations ABD closed correctly, meaning the sum of its interior angles was 180. Additionally, the
quadrilateral formedbyStationsADCEclosedcorrectly,meaning the sum of its interior angles was 360.
However, the location and elevation of certain points varied between stations and days of
measurement.The most“correct”measurement of locationorelevation wasdeterminedbywhether or
not the measurement was present multiple times in the data.
Initially,the teamestablishedanelevationdatumof 100 feetat StationA. Later,a correctional constant
was applied to bring each elevation to a global scale using an approximation of top water level
elevation.
DAM CONSTRUCTION RECORDS
MEMA has no records for the construction or design of this dam at this time. I contacted the NRCS in
search of any records in their files. I received no records at the time of this report.
SPILLWAY
The dam has one single uncontrolledspillwayonthe rightabutment.The spillwayhasnodebrisrackand
isin a state of neglect.Anecdotalevidence from correspondence with the SCE with the NRCS indicates
that the current spillwaywasdesignedasanauxiliary/emergencyspillwaywhenthe inletpipe wasfilled
with concrete.
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Hazard & Condition Report
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HYDRAULIC ESTIMATES
Attachment 3 shows the results of a hydraulic study to determine the ability of the dam’s spillway to
pass a 100 year storm and the effects of a dam breach on the impact zones downstream. The routing
diagramis shownonthe firstpage of Attachment3. AdditionalestimatesandassumptionsforScenarios
1 and 3 are attached. To determine pond storage, NP = 380’ was used based on the most recent aerial
imagery in Google Earth.
DAM STORAGE
Using the above information and a dam height of 16.1’, dam storage at NP =380’ is 125 af. The storage
at the top of the dam is 170 af. The dam is thus jurisdictional.
STORM IMPACT ON THE SPILLWAY
Usinga 100 year,24 hour5.6” storm fallingonanicedwatershed,the spillwayadequately passes water
with a flow of 293 cfs with a freeboard of 0.63’.
BREACH IMPACT ON EXETER ROAD AND WEST BARKER ROAD
The breach used to analyze the downstream impact was 12.8’ high by 20’ wide with a duration of 12
hours under “fair weather” conditions. The starting elevation was set at TWL (379.8’), which gave a
breach flow of 185 cfs.
The breach wasroutedthrough a reach to a 6’ diameter culvert passing under Exeter Road, which then
passed through a second reach to a 4.5’ culvert passing under West Barker.
ExeterRoadsuccessfullypassedthe culvert with a freeboard of 5’ while West Barker Road overtops by
6” with a flow of 79 cfs, which will likely wash out the road.
FINDINGS OF THE HYDRAULIC ANALYSIS
1. The spillway is adequate to pass a 100 year storm falling on an iced watershed (AMC = 3).
2. The dam is a “low” hazard.
DEFECTS IN THE WHITNEY IRRIGATION POND DAM
A. Heavy vegetation growth on the downstream face
B. Vegetation growth in the spillway
C. Beaching on upstream slope
D. Left groin area of the toe is damp
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CONCLUSION
DefectsA and B are causedby the neglectof basicmaintenance of the structure.The larger trees on the
upstream face are likely well-rooted into the dam and removal would cause uprooting of the dam
embankment.The vegetation andbrushonthe downstreamface and in the spillway can be maintained
by regular monitoring and removal. These features must be kept clear to ensure the ease of visual
inspection to detect any further defects in the dam.
DefectC iscause bywave erosionanddeterioratesthe structure of the dam.DefectDis an indicationof
waterflowingthroughseepagepathsinthe dam.The extent of seepage flow through the dam must be
assessed to determine the dam’s potential for breaching.
The resultsof my surveydatashowlowerelevationsinthe middle of the dam, which is an indication of
settlement within the structure. My findings indicate that the dam has potentially settled over 2”.
Settlement should be monitored and investigated to prevent a breach.
Despite the factthat the WIPD isa “low” hazard with respect to MDSL does not eliminate the potential
for a dam failure tocause propertydamage orlossof life.The conditionof the damisunsatisfactoryand
proper maintenance and monitoring of the dam is of the utmost importance to ensure public safety.
RECOMMENDATIONS
Based on the hydraulic study of the dam and visual inspection, I present my recommendations as
follows:
For the dam owner:
1. Remove all brushandall treeswitha diameterof lessthan9” from the downstreamface of the
dam.
2. Clearthe spillwayanditschannel of vegetation.
3. Establishamaintenance schedule topreventfurthervegetationgrowthonthe damand inthe
spillway.
4. Place riprap along the waterline onthe damtopreventwave erosion.
5. Hire an engineertoinvestigate the possible settlementwithinyourdam.
For the State Dam Inspector:
I Recommendthatthe dam be classified asa“low”hazard to the OperationsDirectorof MEMA.
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ABBREVIATIONS (Alphabetical)
AF........................................................................................................................................ Acre-Feet
AMC ....................................................................................................AntecedentMoisture Condition
ASDI........................................................................................................AssistantState DamInspector
CFS.................................................................................................................... CubicFeetperSecond
CN .........................................................................................................................CatchmentNumber
EAP...................................................................................................................EmergencyActionPlan
EI............................................................................................................................ EngineeringIntern
EAP...................................................................................................................EmergencyActionPlan
MDSL...........................................................................................MRSA 37B, Chapter24, “Dam Safety”
MDSP......................................................................................................... Maine Dam SafetyProgram
MEMA .....................................................................................Maine EmergencyManagementAgency
NP....................................................................................................................................Normal Pool
NRCS........................................................................................Natural ResourcesConservationService
ODS......................................................................................................................Office of DamSafety
SCE...........................................................................................................State ConservationEngineer
SCS................................................................................................................Soil ConservationService
SDI........................................................................................................................State Dam Inspector
TWL............................................................................................................................Top Water Level
WIPD......................................................................................................Whitney Irrigation Pond Dam
