Guidelines for Inspection and Maintenance of Dams

Connecticut Department ofEnvironmental Protection

Arthur J. Rocque, Jr.Commissioner

Guidelines for Inspection and Maintenance of Dams

September 2001

Department of Environmental ProtectionBureau of Water Management

Inland Water Resources Division(860) 424-3706

Arthur J. Rocque, Jr. Jane K. StahlCommissioner Deputy Commissioner

Robert L. Smith Charles E. Berger, Jr.Bureau Chief Director

Denise Ruzicka Wesley D. MarshAssistant Director Supervising, Environmental Analyst

ACKNOWLEDGMENTS

From this projects inception through its publication, I had the opportunity to work with Phil Moreschiand Jim Otis of Fuss & ONeill, Inc., who must be thanked for their patience, diligence and profession-alism in preparing this manual. I also want to acknowledge the support of Charles Berger, Jr., Directorand Denise Ruzicka, Assistant Director of the Inland Water Resources Division.

This manual would not have seen the light of day without the contribution of Wesley Marsh, Supervisorof the Dam Safety Section. His intelligence, honesty, practicality and comprehensive knowledge ofConnecticuts dams have been invaluable.

Finally, I would like to acknowledge the contribution of David Majachier. Nearly a decade ago, whileworking for the Dam Safety Section, he envisioned what I hope we have accomplished with thismanual. With great appreciation and respect, this manual is dedicated to David.

Ann KuzykProject Manager

The Department of Environmental Protection is an affirmative action/equal opportunity employer, providing programs andservices in a fair and impartial manner. In conformance with the Americans with Disabilities Act, DEP makes every effortto provide equally effective services for persons with disabilities. Individuals with disabilities needing auxiliary aids orservices, accommodations to participate in a listed event of for more information by voice or TTY/TTD call (860) 424-3000.

Guidelines forInspection and Maintenance of Dams

Prepared for

Connecticut Department of Environmental ProtectionBureau of Water Management

Inland Water Resources Division

Prepared by

Fuss & ONeill, Inc.146 Hartford Road

Manchester, CT 06040(860) 646-2469

This document was printed on recycled paper.

SECTION

A. INTRODUCTIONPurpose and ScopeImportance of Dam Maintenance and Inspection

B. DAM SAFETY REGULATIONS, OWNER RESPONSIBILITYAND LIABILITYDEP Dam Safety Program OverviewPertinent Statutes and RegulationsHow Dams are ClassifiedOperation and Maintenance Plan RequirementsInspection RequirementsResponsibility and Liability

C. TYPES OF DAMS AND COMPONENTS

D. TYPES OF FAILURESeepage/PipingOvertopping/ErosionStructuralProblems, Consequences, Recommended Actions

E. PREVENTIVE MAINTENANCEEmbankmentSpillwaysIntake/Outlet StructuresMasonry and Rubble WallsMiscellaneous Safety and Access Features

F. MAINTENANCE SUMMARY AND SCHEDULE TABLE

G. INSPECTION CHECKLIST

H. REPAIR ASSISTANCE AND EMERGENCY INFORMATIONWhen a Permit May Be RequiredWhen to Contact a Professional EngineerEmergency Operation PlanLocal Emergency Management RoleEmergency Telephone Numbers

GLOSSARY OF TERMS

APPENDIXInspection Checklist

TABLE OF CONTENTS

APPENDIX

Funding for the development and publication of this document was provided by a grant from the FederalEmergency Management Agency in cooperation with the Association of State Dam Safety Officials. In

preparing this manual, similar publications from the States of Missouri and Colorado were valuable sources ofideas and information.

Purpose and Scope

Dams are barriers typically constructed across astream channel to impound water. Dams are man-made structures requiring routine inspection andmaintenance. Several dams fail every year due tolack of maintenance, and in most cases failure couldhave been prevented.

This manual was developed to assist and encouragethe many owners of small dams in Connecticut toinspect and maintain their dams on a regular basis. Itis intended to be a useful guide for owners to refer towhile performing these activities. By inspecting adam on a regular basis, and becoming familiar withthe structure, the owner can recognize importantchanges more readily over time.

A number of inspection and maintenance practicesfor various types of dams are covered, although anemphasis has been placed on earth and earth/ma-sonry structures since they are the most commontypes of small dams in Connecticut.

Importance of Dam Maintenance and Inspection

Impact of Dam Failure: Dam failure may result in theloss of life, property and income. The loss or signifi-cant lowering of a pond or lake impounded by a dammay cause hardship for those dependent on it for theirlivelihood or water supply. The loss of a dam mayalso alter existing wetlands and eliminate recreationalopportunities for swimming, fishing and boating. The

likelihood of future residential and commercialdevelopment occurring both downstream of dams andadjacent to impoundments means that the potential forsuch losses will continue to grow over time. Adheringto the maintenance and inspection guidelines of thismanual is not only an important endeavor for damowners but also a legal requirement.

Regular Inspection: Regular inspection is vital to theproper care and maintenance of dams. A regularinspection program is essential in preserving theintegrity of a dam and avoiding costly repairs. Damsare subject to erosion, corrosion, and deterioration bywind, rain, ice and temperature. Water passing over,under and through dams can weaken these structuresover time. A regular inspection program should startjust after construction is completed and continuethroughout the life of a dam.

A. INTRODUCTION

Dam Failure

DEP Dam Safety Program Overview

The Dam Safety Section of the Inland Water Re-sources Division of the Connecticut Department ofEnvironmental Protection (DEP) is responsible foradministering and enforcing Connecticuts dam safetylaws. The existing statutes require that permits beobtained to construct, repair or alter dams, dikes andsimilar structures and that existing dams, dikes andsimilar structures be registered and periodicallyinspected to assure that their continued operation anduse does not constitute a hazard to life, health orproperty.

Pertinent Statutes and Regulations

The dam safety statutes are codified in Sections 22a-401 through 22a-411 of the Connecticut GeneralStatutes (CGS). Sections 22a-409-1 through 22a-409-2 of the Regulations of Connecticut State Agen-cies (RCSA) govern the registration and safetyinspection of dams in Connecticut. A copy of thesestatutes and regulations are available from the DamSafety Section of the Inland Water ResourcesDivision of the DEP by calling (860) 424-3706.

How Dams are Classified

DEP assigns dams to one of five classes according totheir hazard potential:

a. Class AA: negligible hazard potential dam which, ifit were to fail, would result in no measurabledamage to roadways, land and structures, andnegligible economic loss.

b. Class A: low hazard potential dam which, if itwere to fail, would result in damage to agriculturalland, damage to unimproved roadways, or minimaleconomic loss.

c. Class BB: moderate hazard potential dam which,if it were to fail, would result in damage to nor-mally unoccupied storage structures, damage tolow volume roadways, or moderate economic loss.

d. Class B: significant hazard potential dam which, ifit were to fail, would result in possible loss of life;

B. DAM SAFETY REGULATIONS, OWNER RESPONSIBILITY AND LIABILITY

minor damage to habitable structures, residences,hospitals, convalescent homes, schools, etc.;damage to or interruption of the use or service ofutilities; damage to primary roadways and rail-roads; or significant economic loss.

e. Class C: high hazard potential dam which, if itwere to fail, would result in the probable loss oflife; major damage to habitable structures, resi-dences, hospitals, convalescent homes, schools,etc.; damage to main highways; or great economicloss.

The classification of a dam can change due tochanges in downstream development. As shown inthe chart below, 83% of dams in Connecticut fallwithin the negligible to moderate hazardous categorieswhile only 17% fall within the significant and highhazard categories.

Operation and Maintenance Plan Requirements

DEP typically requires owners of Class B and Chazard classification dams to prepare individualOperation & Maintenance Manuals for their dams,while owners of Class A and BB dams are notroutinely required to do so. The DEP created thismanual in order to help the owners of Class A andBB dams inspect and maintain these lower hazardstructures. In addition, this manual may also serve asa starting point for the preparation of individualOperation & Maintenance Manuals for Class B andC dams.

Connecticut Dams by Hazard Class

Inspection Requirements

DEP is charged with periodically inspecting all damssubject to the jurisdiction of the Commissioner. Theseare dams which by breaking away would causeproperty damage or loss of life. Information regard-ing the inspection process is contained in 22a-409-2 ofthe RCSA.

Responsibility and Liability

Owners of dams are legally responsible for theoperation and maintenance of their structures.Negligence by dam owners in fulfilling their responsi-bilities can negatively impact downstream andadjacent residents and properties.

Section 22a-409-2(j) of the RCSA outlines ownerresponsibilities including:

a. Inspection of the dam to assure no unsafe condi-tions are developing, e.g., due to weather, animalactivity, vandalism.

b. Notification to DEP of any major damage such asovertopping by flood waters, erosion of thespillway discharge channel, new seepage, settling,cracking or movement of the embankment.

c. Maintenance of structure and adjacent area toremain free of brush and tree growth.

d. Written records of all inspections and maintenanceactivities undertaken.

Periodic DEP Inspections

Dam owners are encouraged to visit and inspect theirdam frequently in order to become familiar with itsfeatures and current condition. This allows importantchanges to be detected quickly.

Dam owners may consider obtaining insurance toprovide coverage in the event of damages and claimsresulting from a dam failure. Contact yourhomeowners insurance agent for more information.

Various materials are used for dam constructionincluding earth, timber, rock, concrete and steel.Most dams in Connecticut are constructed of earth orcombinations of earth and other materials. Dams areprovided with spillways to safely pass a broad rangeof flows over, around or through the dam. Damsoften have a drain or similar mechanism to controlwater levels in the impoundment for maintenance oremergency purposes.

C. TYPES OF DAMS AND COMPONENTS

Some typical dam configurations are described below:

a. Earthfill Dam: in which more than 50% of thevolume consists of soil. This type of dam is oftenreferred to as an Embankment Dam.

b. Zone Embankment Dam: composed of zones ofselected materials having different degrees ofpermeability.

Zone Embankment Dam with Cutoff Trench

Earthfill Dam

c. Masonry Dam: constructed mostly of shapedstone, brick or concrete blocks that may or maynot be joined by mortar.

d. Rubble Dam: constructed of unshaped coarsestone or fragments of stones, not placed incourses, that may or may not be joined by mortar.

e. Masonry Wall/Earthfill Dams: consisting of earthembankment with one or two masonry rubble rock

faces; walls on downstream and/or upstream facesare generally vertical.

f. Concrete Dam: constructed primarily of cast-in-place concrete.

g. Concrete Wall/Earthfill Dam: consisting of earthembankment with one concrete wall, generallyvertical and on the upstream face.

Concrete Wall/Earthfill Dam

Concrete Dam

Masonry Wall//Earthfill Dams

Masonry Dam Rubble Dam

The common components of a typical earthfill dam are illustrated below. Descriptions of some common damcomponents are also given below.

Section Through Dam

Earthfill Dam

Embankment Dam Nomenclature

Embankment

The embankment is the primary part of the dam. It isthe section which impounds and resists the forces ofthe water. A homogeneous embankment is composedof essentially the same material throughout, while azoned embankment has different materials, such asclay or rock, incorporated into some areas. Seepagethrough the dam embankment may be collected andcontrolled by an internal drainage system such as atoe drain or foundation drain.

Intake Structure

Intake/Outlet Structures

Also referred to as drawdown facilities, these struc-tures help control impoundment levels and drain areservoir for normal maintenance or emergencypurposes. Most drawdown facilities consist of a pipethrough the dam with a valve which may be operatedas needed. The dam spillway and drawdown struc-tures may be built in close proximity to one another,and an outlet structure may be incorporated into theprincipal spillway structure.

Spillways

The principal spillway establishes the normal waterlevel of the pond or lake. The function of the principalspillway is to allow normal flow to pass the dam in asafe and non-erosive manner. An emergency spill-way is an auxiliary spillway designed to pass floodflows greater than the principal spillways capacity inorder to prevent the dam from overtopping duringextreme storms. Spillways must be resistant toerosion because their failure may be as significant asan embankment failure and may well lead to damfailure. Because flows in spillways may reach highvelocities, a stilling basin or plunge pool is often usedto prevent erosion.

Spillway

Well Maintained Embankment

Masonry and Rubble Walls

Many masonry and rubble-wall-faced earth damsexist in Connecticut. In some instances properlygraded gravel was placed immediately behind thewall to provide a drainage outlet for any seepagemoving through the earthfill. Spillway and spillwaytraining walls have also been constructed withmasonry/rubble walls. Evidence of any seepage,subsidence or undercutting of these walls is bestobserved with the impoundment at spillway crestelevation to assess whether the crest is level. Thestructure should then be viewed with no flow overthe spillway to assess the degree and location ofseepage/leakage and the presence of scour orundercutting erosion at the toe.

Miscellaneous Safety and Access Features

Fences, handrails, gates, access roads, bridges andwarning signs serve to improve access and personalsafety. Fences also discourage vandalism.

Relative Numbers for Types of Dams

As shown in the chart below, 77 percent of Connecti-cut dams in the negligible to moderate hazard catego-ries are constructed primarily of earth, masonry or acombination of these materials.

Rubble Wall

Construction of Types AA, A and BB Damsin Connecticut

Dam failures usually result from poor design, im-proper construction, inadequate maintenance, or acombination of the above. Although the manner inwhich a dam fails and the particular causes of failureare often varied and complex, failures can generallybe grouped into the following three types:

Seepage/Piping

All earth dams have seepage due to water movementthrough the dam and its foundation, however, the rateof seepage must be controlled. Uncontrolled seepagecan progressively erode soil from the embankment orits foundation in an upstream direction towards thereservoir and develop a flow conduit (pipe) to thereservoir. This phenomenon is known as piping.Uncontrolled seepage may also weaken the soil andlead to a structural failure. Common causes ofseepage/piping include rodent activity, tree roots andpoor construction.

Overtopping/Erosion

Overtopping failures result from the erosive action ofthe uncontrolled flow of water over, around oradjacent to the dam. Earth embankments are notdesigned to be overtopped and therefore are particu-larly susceptible to erosion. Surface erosion mayreduce the embankment cross-section, saturate anearth embankment and lead to a structural failure.General causes of overtopping include inadequatespillway size and/or spillway blockage by debris.

D. TYPES OF FAILURE

Dam Failure

Structural

Structural failures can occur in the dam itself or itsfoundation. Structural failure of a spillway, draw-down facility, concrete wall or other appurtenancecan lead to a total dam failure. Cracking, settlementand slides are common signs of structural failurewhich often result from uneven settlement of founda-tion materials and/or poor workmanship duringconstruction.

Problems, Consequences, RecommendedActions

Various observable problems, their possible conse-quences, and recommended actions are groupedbelow by failure type.

SEEPAGE/PIPINGPROBLEM

POSSIBLECONSEQUENCES

RECOMMENDEDACTIONS

Continuous flows can lead topiping erosion of the foundationand failure of the dam.

Examine boil for transportation offoundation materials, evidenced bydiscoloration. If soil particles aremoving downstream, create a sandbag or earth dike around the boil.This is a temporary control mea-sure. The pressure created by thewater level within the dike maycontrol flow velocities and preventfurther erosion. If erosion contin-ues, lower the reservoir level. AQUALIFIED ENGINEER shouldinspect the condition and recom-mend further actions to be taken.CONTACT DEP DAM SAFETYPERSONNEL.

Can lead to erosion of embank-ment materials and failure of thedam.

Study leakage area to determinequantity of flow and extent ofsaturation. Stake out the saturatedarea and monitor for growth orshrinkage. Inspect frequently forslides. Water level in the impound-ment may be lowered to increaseembankment safety. A QUALI-FIED ENGINEER should inspectthe conditions and recommendfurther actions to be taken.

Condition shows excessive seep-age in the area. If control layer ofturf is destroyed, rapid pipingerosion of foundation materialscould result in failure of the dam.Marked change in vegetation maybe present.

Carefully inspect the area foroutflow quantity and any trans-ported material. A QUALIFIEDENGINEER should inspect thecondition and recommend furtheractions to be taken. CONTACTDEP DAM SAFETY PERSON-NEL.

Seepage Water Exiting atAbutment Contact

Seepage Water Exiting as aBoil in the Foundation

Spongy Condition at Toe ofDam



RECOMMENDEDACTIONS

Can reduce length of seepage pathand lead to piping erosion failure.If rodent tunnel exists throughmost of the dam, it can lead tofailure of the dam.

Control rodents to prevent moredamage. Determine exact locationof digging and extent of tunneling.Remove rodents and backfillexisting holes.

Rodent Activity

Piping erosion can empty areservoir through a small hole orcan lead to dam failure as soilpipes erode. Dirty water at the exitindicates erosion.

Inspect other parts of the dam forseepage or more sinkholes.Identify exact cause of sinkholes.Check seepage and leakageoutflows for dirty water. AQUALIFIED ENGINEER shouldinspect the conditions and recom-mend further actions to be taken.CONTACT DEP DAM SAFETYPERSONNEL.

Continued flows can lead to rapiderosion of embankment materialsand failure of the dam.

Investigate the area by probingand/or carefully shoveling to see ifthe cause can be determined.Determine if leakage water iscarrying soil particles evidenced bydiscoloration. Determine quantityof flow. If flow increases, or iscarrying embankment materials,reservoir level should be lowereduntil leakage stops. A QUALI-FIED ENGINEER should inspectthe condition and recommendfurther actions to be taken.CONTACT DEP DAM SAFETYPERSONNEL.

Seepage Water Exiting From aPoint Adjacent to the Outlet

Sinkhole



RECOMMENDEDACTIONS

Large tree roots can createseepage paths. Brush can obscurevisual inspection and harborrodents. Decaying root systemscan provide seepage paths. Windthrown tree can create void indam.

Remove all trees and shrubs onand within 25 feet of the embank-ment. Properly backfill void withcompacted material. A QUALI-FIED ENGINEER may berequired; CONTACT DEP DAMSAFETY PERSONNEL.

Trees /Brush

Wave action against unprotectedareas decreases embankmentwidth. Soil is eroded away whichallows riprap to settle, providingless protection and decreasedembankment width.

Re-establish normal slope. Placebedding and competent riprap.ENGINEER REQUIRED fordesign of bedding and riprap.

Erosion can lead to eventualdeterioration of the downstreamslope and failure of the structure.Can reduce available freeboardand/or cross-sectional area ofdam. Can result in a hazardouscondition if due to overtopping.

Protect eroded areas with riprap.Compacted soil and re-establishingturf may be adequate if theproblem is detected early. If gullywas caused by overtopping,provide adequate spillway de-signed by a QUALIFIED ENGI-NEER.

Broken Down or MissingRiprap

Erosion

OVERTOPPING/EROSIONPROBLEM


RECOMMENDEDACTIONS

May reduce discharge capacityand cause overflow of spillwayand/or dam overtopping. Dam, ifovertopped frequently, can erodeand/or fail.

Remove debris blockage (e.g.beaver dams) regularly. Measurequantity of flow depth in spillwayfor various rain events. Controlvegetative growth in spillwaychannel. Install log boom or trashrack in front of spillway entranceto intercept floating debris. AQUALIFIED ENGINEER shouldinspect the conditions and recom-mend further actions to be taken.

Blocked/Inadequately SizedSpillway

OVERTOPPING/EROSIONPROBLEM


RECOMMENDEDACTIONS

Allows standing water to collectand saturate crest of dam. Ve-hicles can get stuck.

Regrade and recompact crest toprovide proper drainage to up-stream slope. Install gravel or roadbase material to accommodatetraffic.

Ruts/Puddling Along Crest

Creates areas bare of erosionprotection and causes erosionchannels. Allows water to standand makes area susceptible todrying cracks.

Prohibit access using fence, signs.Repair erosion protection withriprap or grass. If access isneeded or required, provide aformal access way designed toprevent erosion.

Pedestrian/Vehicle Traffic

Missing/Deteriorated RiprapChannel Lining

Erosive action displaces channellining and washes sedimentdownstream.

Install properly graded riprap inchannel lining with filter material toprevent soil from being washed outthrough spaces in the riprap.

STRUCTURALPROBLEM


RECOMMENDEDACTIONS

Large cracks indicate onset ofmassive slide or settlement causedby foundation failure. A series ofslides can lead to obstruction ofthe outlet or failure of the dam. Ifmassive slide cuts through crest orupstream slope, reducing free-board and cross section, structuralcollapse or overtopping can result.

Measure extent and displacementof slide. If continued movement isseen, begin lowering water leveluntil movement stops. A QUALI-FIED ENGINEER should inspectthe condition and recommendfurther action. CONTACT DAMSAFETY PERSONNEL.

Large Cracks, Slide, Slump orSlip

Ice action may further weaken ordisplace concrete by freezing andthawing.

Determine cause. Either patchwith grout or contact engineer forpermanent repair method. Ifdamage is extensive, a QUALI-FIED ENGINEER should inspectthe conditions and recommendfurther actions to be taken.

Cracked or DeterioratedConcrete Face

Minor displacement will createeddies and turbulence in the flow,causing erosion of the soil behindthe wall. Erosion of foundationmaterial may weaken support andcause further displacement. Majordisplacement will cause severecracks and eventual failure of thestructure.

Reconstruct displaced structure.Water-stops should be used atjoints where feasible. Consult aQUALIFIED ENGINEER beforeactions are taken.

Wall Displacement/OpenJoints

STRUCTURALPROBLEM


RECOMMENDEDACTIONS

Disturbance in flow patterns;erosion of foundation and backfill;eventual collapse of structure.May allow entrance of waterwhich could cause freeze andthaw damage and further weakenstructure.

Cracks without large displacementmay be repaired by patching, inwhich case surrounding areasshould be cleaned or cut outbefore patching. Installation ofweep holes or other actions maybe needed. A QUALIFIEDENGINEER should inspect thecondition and recommend suchfurther actions.

Large Cracks

Can cause walls to tip over. Flowsthrough concrete can lead to rapiddeterioration from weathering. Ifthe spillway is located within theembankment, rapid erosion canlead to failure of the dam.

Check area behind wall forpuddling of surface water. Checkand clean drain outfalls, flush lines,and weep holes. If conditionpersists a QUALIFIED ENGI-NEER should inspect the conditionand recommend further actions tobe taken.

Leakage Through Joints orCracks

Can weaken or disintegrate wallby dislodging masonry or rubblestone.

Control excessive brush throughregular routine maintenance(removal). Remove large trees,stumps and roots under thedirection of a QUALIFIEDENGINEER.

Tree Growth in MasonryWalls

Freezing/thawing of silty/clayeysoils push (lean) masonry walls outof vertical alignment. Missingstones can weaken wall and leadto wall failure.

Monitor movement over time.Replace lost or unsuitable soilsbehind wall or brace downstreamface with riprap or washed stone.Replace missing stones, chokeand/or chink gaps in wall. De-pending upon extent of displace-ment/condition, a QUALIFIEDENGINEER may be required.CONTACT DEP DAM SAFETYPERSONNEL.

Leaning/Bulging MasonryWalls

STRUCTURALPROBLEM


RECOMMENDEDACTIONS

Provides passageway for water toexit or enter pipe, resulting inerosion of internal materials of thedam.

Check for evidence of watereither entering or exiting pipe.Tap pipe in vicinity of damagedarea, listening for hollow soundwhich indicates a void has formedalong the outside of the conduit. Ifa progressive failure is suspected,request advice from a QUALI-FIED ENGINEER. CONTACTDEP DAM SAFETY PERSON-NEL.

Use of the system should beminimized or discontinued. If theoutlet system has a second controlvalve, consider using it to regulatereleases until repairs can be made.

Loss of support for control stem.Stem may buckle and break undereven normal use, resulting in lossof control.

Outlet Pipe Damage:

Joint Offset

Control Works

Hole, Crack

STRUCTURALPROBLEM


RECOMMENDEDACTIONS

Gate will not close. Gate or stemmay be damaged in effort to closegate.

Raise and lower gate slowly untildebris is loosened and floats pastvalve. When reservoir is lowered,repair or replace trashrack.

Valve Leakage:

Debris Stuck Under Gate

Cracked Gate Leaf

Damaged Gate Seat orGuides

Gate leaf may fail completely,evacuating reservoir.

Leakage and loss of support forgate leaf. Gate may bind in guidesand become inoperable.

Use valve only in fully open orclosed position. Minimize use ofvalve until leaf can be repaired orreplaced.

Minimize use of valve until guides/seats can be repaired. Check tosee if air vent pipe exists and isunobstructed.

E. PREVENTIVE MAINTENANCE

Because dams are subject to deterioration over time,and seemingly minor deficiencies can quickly developinto major problems, all dam components and appurte-

nances should be inspected and maintained regularly.Routine maintenance recommendations are providedbelow by dam component.

Typical Deficiencies

Embankment

Recommended routine maintenance procedures andfrequencies include:

a. Vegetation Control - twice per year

Mow grass to maintain visibility of dam surfacesand remove woody vegetation from within 25 feetof all dam components

Maintain a healthy stand of grass to preventerosion and growth of woody vegetation

b. Rodent Control - as required

Fumigate burrow Trap or eradicate rodent Fill entire burrow with fill material

Rodent Burrow

Spillways


a. Vegetation Control (for grass lined emergencyspillways)

Mow grass twice per year Maintain a healthy stand of grass to prevent

erosion Remove woody vegetation annually

b. Minor Earthwork and Erosion Repair - as required

Replace missing soil with new soil that contains novegetation, organic matter, trash or large rocks

Place and compact in thin (i.e., 6-inch) layers Install topsoil and seed

c. Erosion Protection - as required

Install rock, riprap, vegetation or other material(e.g., concrete or asphalt) where erosion protec-tion is missing, damaged or otherwise required

Check downstream spillway channel for evidenceof excessive siltation or erosion

d. Concrete/Stone/Masonry Repair - as required

Consult DEP Dam Safety personnel and/or aprofessional engineer to determine appropriaterepair

e. Beaver Dam Removal - as required

Remove beaver flowage debris from spillway

Beaver Dam in Spillway

c. Minor Embankment and Erosion Repair - asrequired

Restore damaged/eroded areas with soil that isfree from vegetation, organic matter, trash, largerock

Place and compact in thin (i.e., 6-inch) layers Install topsoil and seed

d. Erosion Protection - as required

Install rock, vegetation or other material (concreteor asphalt) where erosion protection is missing,damaged or otherwise required

Intake/Outlet Structures


a. Trashrack - after every major storm

Remove accumulated debris Repair rusted or broken sections as needed

b. Mechanical - once per year

Cycle (open and close) outlet gate valves throughfull operating range

Lubricate mechanisms per manufacturers recom-mendation

Paint or grease ferrous metal surfaces as needed Align stem guides or brackets

c. Internal Conduit - once per year

Check for undermining or seepage around theoutlet end

Check for corrosion or other deterioration ofconduit material

Should deficiencies be detected, obtain immediateprofessional guidance before attempting repairs

d. Concrete Features - once per year

Check for misalignment, cracks, spalls, scaling,exposed steel rebar, rust stains

Consult with DEP Dam Safety Personnel or aconsultant engineer before attempting repairs

Concrete Intake Structure

Masonry and Rubble Walls


a. Vegetation Control - twice per year

Remove woody vegetation within 25 feet ofmasonry dam structures

Cut trees growing in masonry walls flush with faceof masonry

b. Missing Stones - as required

Replace missing or misaligned capstones inspillway

Replace missing stone masonry in downstreamand upstream walls

Do not mortar up or seal off the spaces or open-ings between the stones on the downstream faceof masonry or rubble walls without first consultinga qualified engineer

Leak in Masonry Wall

Miscellaneous Safety and Access Features


a. Maintain vehicular and pedestrian access featuresto allow future inspection and maintenance - onceper year.

b. Check fences, locks and signs for damage - onceper year.

Walkway, Hand Railing

Fence and Signage

This maintenance summary and schedule is intendedto provide the owner with a quick reference of therecommended frequency intervals for inspecting and

F. MAINTENANCE SUMMARY AND SCHEDULE TABLE

performing routine maintenance on the components ofa dam.

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Regular dam inspection and the review of inspectionrecords are essential in assessing the need forcarrying out dam repairs. By inspecting a dam on aregular basis, the owner can recognize changes in thestructure over time. Very often the existence of aproblem is not as important as its rate of developmentor a sudden change in its condition or extent.

The dam owner should keep records of all (routineand special) inspections in the form of notes, photo-

G. INSPECTION CHECKLIST

graphs and/or sketches. The inspection checklistfound in the Appendix of this manual is intended tohelp the owner perform routine inspections in aconsistent, efficient manner.

Each dam registered in the State of Connecticut hasan assigned identification number unique to that dam.Contact the DEP Dam Safety Section to obtain theappropriate identification number for your dam.

When a Permit May Be Required

The DEP Bureau of Water Management, InlandWater Resources Division, regulates the construction,alteration, repair or removal of dams, dikes, reservoirsand similar structures. This authority is derived fromSections 22a-401 through 22a-411 of the CGS.Consequently, any person or agency proposing toconstruct a dam, dike, reservoir or similar structure,or proposing to repair, alter or remove such a struc-ture, must first obtain either a permit under CGSSection 22a-403 or 22a-411 from the DEP, or obtain adetermination from DEP that such a permit is notrequired for the proposed activity. Pursuant to CGSSection 22a-401, DEP regulates dams which, bybreaking away or otherwise, may endanger life orproperty. Dams whose failure does not endangerdownstream life or property may not be regulated byDEP, but by the local inland wetlands or conservationcommission where such dam is located.

Routine maintenance activities that do not require aconstruction permit from the DEP Dam SafetySection typically include the following:

Grass mowing Cutting of brush or trees from the dam or adjacent

areas Removal of debris and sediment from spillway

intake areas and channels Restoration of minor eroded areas by placing

topsoil, seed and mulch Minor patching of concrete structures Eradication of rodents and filling rodent holes Maintenance of drain valves (exercise, grease,

adjust, repair valve stem and operators)

The local inland wetlands or conservation commissionshould be contacted prior to undertaking these typesof activities to determine what, if any, local agencypermits may be required.

Repair activities that do require a construction permitfrom the DEP Dam Safety Section typically includework of a more intrusive nature such as:

Removal of tree roots and stumps and repair toearth embankments

Reconstruction of severely deteriorated concrete

structures or stone masonry walls Repair or replacement of damaged/deteriorated

low level outlet pipes, conduits, valves Installation of drainage systems to control embank-

ment or foundation seepage/leakage Flattening of embankment slopes Reconstruction of spillway, outlet control structure,

walls

The DEP normally requires a dam construction permitfor those repairs, alterations, or modifications toexisting dams which, if improperly constructed, wouldadversely impact the structural integrity of the dam.Similarly, other proposed work which may affect theintegrity of a dam, such as excavation adjacent to thedam, may require a DEP dam construction permit.DEPs review of permit applications under CGSSection 22a-403 evaluates the structural and engi-neering aspects of the proposed dam repair, modifica-tion or alternation. In addition, the potential impact ofthe proposed construction on the environment, thesafety of persons and property, and inland wetlandsand watercourses are considered. The DEP mustalso determine the need for providing fish passage atthe site in accordance with CGS Section 26-136.

Before obtaining a permit, plans and specifications bya licensed professional engineer must be submitted tothe DEP Dam Safety Section of the Inland WaterResources Division for approval. After a permit isissued, a professional engineer familiar with damconstruction (ideally the design engineer) must inspectthe construction, certify completion of the work andprepare as-built plans of the structure. FollowingDEP approval of the permitted construction, aCertificate of Approval is issued to the owner ofthe dam in accordance with CGS Section 22a-405.The Owner must file the certificate on the landrecords of the town or towns in which the dam islocated. The Certificate of Approval may containspecific terms and conditions regarding the damsinspection and operation which are intended to protectlife and property.

When to Contact a Professional Engineer

Regular dam inspection and prudent operation andmaintenance by the owner will help identify and solveminor problems early and reduce the potential for

H. REPAIR ASSISTANCE AND EMERGENCY INFORMATION

dam failure. However, since each dam is unique, thismanual cannot begin to cover every possible condi-tion/deficiency which may develop. The importanceof contacting a qualified engineer when significantdeficiencies are detected cannot be overemphasized.

A dam inspection by a qualified engineer provides athorough, systematic evaluation of the condition of thedam. Such inspections should, at a minimum, beperformed during construction of a new dam, modifi-cations to an existing dam, and whenever potentiallysignificant defects are first observed including:

Earth slides in the embankment Uncontrolled seepage from dam, foundation boil Severe erosion of spillways or discharge channels Seepage around pipes Concrete deterioration (cracks, joint displacement) Pipe joint separation or damage Surface cracking Irregular settlement Sinkholes

A professional engineer may be located by checkingthe yellow pages section of the local telephonedirectory under the headings professional engineers,consulting engineers or civil engineers. Confirmthat the engineer has experience with, and is qualifiedto inspect, dams.

Emergency Operation Plan

Dam owners have historically been held liable fordamages which occur as a result of dam failure.Owners therefore bear responsibility for reducing thepotential hazard posed by their dams to downstreamresidents and property. Accordingly, the DEP re-quires that owners of Class B and C potential hazarddams prepare and implement an Emergency Opera-tion Plan (EOP).

Guidelines for EOP preparation include three essentialcomponents:

1) An identification of the area inundated by a damfailure;

2) An established procedure for monitoring the damduring periods of heavy rainfall and runoff; and

3) A formalized warning system to alert the appropri-ate local emergency management officials chargedwith warning or evacuation responsibilities.

Usually, the owners of Class BB and A hazardpotential dams are not required to prepare an EOP fortheir dams. However, the DEP encourages damowners who wish to prepare an EOP to do so inaccordance with the aforementioned guidelines. Theguidelines are available from the DEP Inland WaterResources Divisions Dam Safety Section.

Even if an EOP has not been prepared for a dam, it isstill prudent for the owner to inspect the dam when-ever a flood watch or flood warning alert isissued by the National Weather Service for thecounty where the dam is located. It is also a goodidea to inspect the dam immediately following a veryheavy rainfall. A written record of these special daminspections should be maintained.

Local Emergency Management Role

If any of the following four conditions are observedduring a flood watch or warning, the dam ownershould notify the appropriate local emergency man-agement agency that conditions at the dam mayjustify the evacuation of specific areas or closingcertain roads due to the potential for flooding. Onlylocal emergency management agencies have theauthority to order the evacuation of residences orclose roads.

a. Dam is overtopping or nearly overtopping.

b. Internal piping erosion of soil from the embank-ment or foundation has developed and caused arapid increase in seepage, a muddy discharge nearthe downstream embankment toe, sinkholesappearing on or near the embankment, or asignificant whirlpool (eddy) in the reservoir.

c. A large slide or slough develops in the upstream ordownstream embankment slope which threatens to

breach the embankment and release the im-pounded water.

d. The sudden movement or failure of an appurtenantstructure threatens the complete failure of the damand release of its impoundment.

The dam owner is responsible for notifying, at aminimum, one local emergency management office ordepartment. The local agency contacted should thennotify other appropriate local agencies. The ownermust contact the local government ahead of time tofind out which telephone number(s) to call during orafter normal business hours in the event of an emer-gency at the dam.

Emergency Telephone Numbers

The following agencies typically have responsibility toact in response to an impending dam failure. A spaceis provided next to these agencies for the dam ownerto fill in the appropriate contact information:

a. Town/City Chief Executive:

b. Local Police Department:

c. Local Emergency Management Director:

d. State Office of Emergency Management:(860) 566-3180

e. DEP Flood Emergency Operations Center: (860) 424-3706 or (860) 424-3019

f. DEP Communications Center: (860) 424-3333 - after normal business hours

g. State Police (Nearest Barracks):

ABUTMENT - The natural ground that borders oneither end of the dam structure. Right and leftabutments are those on respective sides of the damwhen an observer looks downstream.

ANTI-SEEPAGE COLLAR - A projecting collar ofconcrete or other material built around the outside ofa tunnel or conduit within an embankment dam, toreduce the seepage potential along the outer surfaceof the conduit.

APPURTENANCE - Any structure or mechanismother than the dam itself which is associated with thedams operation.

AS-BUILT DRAWINGS - Plans or drawingsportraying the actual dimensions and conditions of adam, dike, or levee as it was built. Field conditionsand material availability during construction oftenrequire changes from the original design drawings.

BLANKET DRAIN - A drainage layer of sand orgravel placed directly over the foundation material toallow for the safe release of seepage flow.

BOIL - A disturbance in the surface layer of soilcaused by water escaping under pressure frombehind a water retaining structure such as a dam orlevee. The boil may be accompanied by deposition ofsoil particles (usually sand) in the form of a conical-shaped mound (miniature volcano) around the areawhere the water escapes.

BREACH - A break or opening in a dam whichreleases impoundment water either deliberately oraccidentally.

CHOKE OR CHINK - Placement of stones on theupstream or downstream face (respectively) of astone masonry or rubble wall.

CONDUIT - A closed channel to convey the dis-charge through or under a dam, typically a pipe.

CONSTRUCTION JOINT - The interface betweentwo successive placements of concrete wherebonding, not permanent separation, is intended.

GLOSSARY OF TERMS

CONTRACTION JOINT - A joint constructed suchthat shrinkage of the concrete would cause a crack.

CORE - A zone of material of low permeability,within an embankment, the purpose of which is toreduce the quantity of seepage through the dam.

CORE WALL - A wall of substantial thickness builtof impervious materials, usually of concrete orasphaltic concrete, within an embankment to preventleakage.

CORROSION - The chemical attack on a metal byits environment. Corrosion is a reaction in whichmetal is oxidized.

CREST - The crown of an overflow section of thedam. In the United States, the term crest of dam isoften used when top of dam is intended. To avoidconfusion, the terms crest of spillway and top of damshould be used for referring to the overflow sectionand dam proper, respectively.

CUTOFF - A relatively impervious barrier of soil,concrete, or steel constructed either to minimize theflow of water through pervious or weathered zones ofa dams foundation or to direct flow around suchzones. May be a trench filled with impervious mate-rial or a wall of impervious material built into thefoundation.

DAM - Any barrier which is capable of impoundingor controlling the flow of water, including but notlimited to stormwater retention or detention dams,flood control structures, dikes and incompletelybreached dams.

DRAINAGE LAYER OR BLANKET - A layer ofpervious material in a dam to relieve pore pressuresor to facilitate drainage of the fill.

DRAINAGE WELL - Vertical wells or boreholesdownstream of, or in the downstream berm of, anembankment to collect and control seepage throughor under the dam and so reduce water pressure. Aline of such wells forms a drainage curtain.

DRAWDOWN - The resultant lowering of water-surface level due to release of water from thereservoir.

DROP INLET SPILLWAY - A spillway consisting ofa vertical pipe or conduit in the impoundment con-nected to a near horizontal pipe which passes throughthe dam and discharges downstream of the dam.

EMBANKMENT - Fill material, usually earth orrock, placed with sloping sides and usually longer thanhigh.

EMERGENCY SPILLWAY - See Spillway.

ENERGY DISSIPATER - Any device constructed ina waterway to reduce the energy of fast-flowingwater.

EROSION - Wear or scouring caused by the abra-sive action of moving water.

FACE - The external surface limits of a structure,e.g., the face of a wall or dam.

FAILURE - An incident resulting in the uncontrolledrelease of water from an operating dam.

FILTER - A bank or zone of granular material that isincorporated in a dam and is graded (either naturallyor by selection) to allow seepage to enter the filterwithout causing the migration of fill material fromzones adjacent to the filter.

FLOOD - A general and temporary condition ofpartial or complete inundation of normally dry landareas.

FLOOD PLAIN - An area adjoining a body of wateror natural stream that has been or may be covered byflood water.

FOUNDATION OF DAM - The natural material onwhich the dam structure is placed.

FREEBOARD - The vertical dimension between thetop of the dam at its lowest point and the reservoirwater surface elevation.

GRAVITY DAM - A dam constructed of concrete ormasonry, which relies on its own weight for stability.

GROIN AREA - The area at the intersection ofeither the upstream or downstream slope of anembankment and the valley wall or abutment.

GROUT - A thin cement or chemical mortar used tofill voids, fractures, or joints in masonry, rock, sandand gravel, and other materials. As a verb, it refersto filling voids with grout.

GULLY - Rainfall erosion of earthen embankmentslopes. Also may be caused in part by vehiculartraffic or foot traffic.

HEEL OF DAM - The junction of the upstream faceof a gravity dam with the foundation surface. In thecase of an embankment dam the junction is referredto as the upstream toe of the dam.

HEIGHT OF DAM - The vertical distance mea-sured from the downstream toe of the dam at itslowest point to the elevation of the top of the dam.

HOMOGENEOUS EARTHFILL - An embankmenttype construction of more or less uniform earthmaterials throughout, except for possible inclusion ofinternal drains or blanket drains. The term is used todifferentiate from a zoned earthfill embankment.

INTAKE - Any structure in a reservoir, dam, or riverthrough which water can be drawn from the im-poundment or river to a discharge point.

INTERNAL EROSION - See Piping.

INUNDATION MAP - A map delineating the areathat would be inundated in the event of a dam failure.

LEAKAGE - Uncontrolled loss of water by flowthorough a hole or crack.

LOW-LEVEL OUTLET - A low-level reservoiroutlet, valve and pipe system through the dam gener-ally used for lowering reservoir water level.

MAXIMUM WATER LEVEL - The maximum waterlevel, including the flood surcharge, the dam isdesigned to withstand.

NORMAL WATER LEVEL (NORMAL POOL)-For a reservoir with a fixed overflow spillway crest, itis the lowest level of that crest.

OBSERVATION WELL - Small-diameter perforatedvertical tube installed within an embankment. Usedto measure the height of the internal water surface inthe embankment at the location of the well.

ONE-HUNDRED YEAR (100-YEAR) RETURNFREQUENCY FLOOD - The flood magnitude withone percent chance of being exceeded in any givenyear. A 100-year rainfall event is currently said tooccur when seven inches of precipitation falls in a 24-hour period.

OUTLET - An opening through which water can befreely discharged from a reservoir to a downstreamchannel.

OWNER - Any person or entity holding legal title to adam or water obstruction.

PERMEABILITY - A material property whichdefines the materials capacity to transmit water.

PERVIOUS ZONE - A part of the cross section ofan embankment dam comprising material of highpermeability.

PHREATIC SURFACE - The upper surface ofseepage in an embankment. All the soil below thissurface will be saturated when the steady-stateseepage condition has been reached.

PIPING - Progressive erosion and removal of soil byconcentrated seepage flows through a dam, dike, orlevee, its foundation, or its abutments. As material iseroded, the area of the pipe increases and thequantity and velocity of flow increase; these changesin turn result in the erosion of more material. Theprocess continues at a progressively faster rate.Dam failure can result if the piping cannot be broughtunder control.

RELIEF WELL - See Drainage Well.

RESERVOIR - An impoundment of water created bya dam.

RILL - See Gully.

RIPRAP - A layer of large stone, broken rock, orprecast blocks placed in random fashion on the slopeof an embankment dam, on a reservoir shore or in achannel as a protection against erosive flows, wavesand ice.

SCALING - The peeling away of a concrete surface.

SEEPAGE - The slow percolation of water through adam, its foundation, or abutment. A small amount ofseepage will normally occur in any dam or embank-ment that retains water.

SEEPAGE COLLAR - A projecting collar, usually ofconcrete, built around the outside of a pipe, tunnel, orconduit, under an embankment dam, to lengthen theseepage path along the outer surface of the conduit.Sometimes referred to as anti-seepage collar.

SLIDE - The movement of a mass of earth or tailingsdown a slope. In embankments and abutments, thisinvolves the separation of a portion of the slope fromthe surrounding material.

SLOPE PROTECTION - The armoring of theembankment slope against wave action and erosion,usually done by the installation of riprap.

SLOUGH - The separation from the surroundingmaterial and downhill movement of a small portion ofan earth slope. Usually this refers to a shallow earthslide.

SPALLING - Breaking (or erosion) of small frag-ments from the surface of concrete, masonry or stoneunder the action of weather or erosive forces.

SPILLWAY - A structure over or through a dam bywhich normal or flood flows are discharged. If theflow is controlled by gates, it is considered a con-trolled spillway; if the elevation of the spillway crest isthe only control, it is considered an uncontrolledspillway. A principal spillway conveys normal flows;an emergency spillway is used to convey moreinfrequent flood flow.

SPILLWAY CHANNEL - A channel conveyingwater from the spillway crest to the water course.

SPILLWAY DESIGN FLOOD - The rainfall andrun-off event used to design a dams spillway capac-ity. The current DEP recommended minimumspillway design is the run off associated with the 100-year return frequency flood with an additional foot offreeboard.

STILLING BASIN - An energy-dissipating device atthe outlet of a spillway to dissipate the high velocity(energy) of the flowing water, in order to protect thespillway structure and avoid serious erosion of theoutlet channel and subsequent undermining.

STOP LOGS - Large logs, timbers, metal panels orsteel beams, placed on top of each other with theirends held in guides on each side of a channel orconduit, to provide means of controlling or stoppingthe flow of water. Sometimes referred to as weirboards.

STORAGE - The retention of water or delay ofrunoff either by planned operation, as in a reservoir,or by temporary filling of overflow areas, as in theprogression of a flood through a natural streamchannel.

TAILWATER LEVEL - The level of water in thedischarge channel immediately downstream of thedam.

TOE OF DAM - The base portion of a dam whichintersects with natural ground at the downstreamside.

TOP OF DAM - The elevation of the uppermostsurface of a dam.

TRASHRACK - A device located at the intake of aconduit inlet or waterway to prevent entrance ofsome floating or submerged debris.

UPLIFT - The upward pressure in the pores of amaterial or on the base of a structure.

UPSTREAM BLANKET - An impervious layerplaced on the reservoir floor upstream of a dam. Inthe case of an embankment, this blanket may beconnected to the impermeable zone of the embank-ment.

VALVE - A device fitted to a pipeline or orifice tocontrol or stop flow.

WEEP HOLE - A small pipe opening into structuressuch as concrete abutments, downstream mortaredstone wall or concrete aprons to relieve any buildupof water pressure from seepage or groundwater.

WEIR - A type of spillway in which flow is con-stricted and caused to fall over a crest. Sometimesspecially designed weirs are used to measure flowamounts.

ZONED EARTHFILL - An earthfill-type embank-ment, the cross section of which is composed ofzones of selected materials having different degreesof porosity, permeability and density.

DAM NAME:

OWNER:

DAM I.D. No.: INSPECTOR

Directions: Mark an "X" in the YES or NO column. If an item does not apply, write "NA." ff possible, identify anychanges since the last inspection in Section 11 - Other Comments/Observations.

DATE:

WEATHER:

TEMPERATURE:

ITEM

1. TOP OF DAM

a. Any visual settlements?

b. Misalignment?

c. Cracking?

2. UPSTREAMSLOPE

a. Adequate grass cover?

b. Any erosion?

c. Are trees growing on slope?

d. Longitudinal cracks?

e. Transverse cracks?

f. Adequate riprap protection?

g. Any stone deterioration?

h. Visual depressions or bulges?

i. Visual settlements?

j. Debris or trash present?

3. DOWNSTREAM SLOPE

a. Adequate grass cover?

b. Any erosion?

c. Are trees growing on slope ?

d. Longitudinal cracks?

DATE:

ITEM

e. Transverse cracks?

f. Visual depressions or bulges?

g. Visual settlements?

h. Is the toe drain dry?

i. Are the drainage wells flowing?

j. Are boils present at the toe?

k. Is seepage present?

1. Soft or spongy zones present?

m. Are foundation toe drain pipes:

(1) Broken, bent, or missing?

(2) Corroded or rusted?

(3) Obstructed?

(4) Is discharge carrying sediment?

4. ABUTMENT CONTACTS

a. Any erosion?

b. Visual differential movement?

c. Any cracks noted?

d. Is seepage present?

5. PRINCIPAL SPILLWAY INLET

a. Do concrete surfaces show:

(1) Spalling?

(2) Cracking?

(3) Erosion?

(4) Scaling?

(5) Exposed rebar?

b. Do the joints show:

(1) Displacement or offset?

DAM INSPEC

DATE:

ITEM

(2) Loss of joint material?

(3)Leakage?

Metal appurtenances:

(1) Rust present?

(2) Broken components?

(3) Anchor system secure?

d. Trashrack operational?

6. PRINCIPAL SPILLWAY CONDUIT

a. Is the conduit concrete?

b. Do concrete surfaces show:

(1) Spalling?

(2) Cracking?

(3) Erosion?

(4) Scaling?

(5) Exposed rebar?

c. Do the joints show:



(3)Leakage?

d. Is the conduit metal?

(1) Rust present?

(2) Protective coatings adequate?

(3) Is the conduit misaligned?

e. Is there seepage around the conduit?

7. STILLING BASIN

a. Do concrete surfaces show:

(1) Spalling?

DATE:

ITEM

(2) Cracking?

(3) Erosion?

(4) Scaling?

(5) Exposed rebar?




(3) Leakage?

c. Do energy dissipaters or riprap areas show:

(1) Signs of deterioration?

(2) Accumulated debris?

d. Is the channel:

(1) Eroding?

(2) Sloughing?

(3) Obstructed?

e. Is discharged water:

(1) Undercutting the outlet?

(2) Eroding the embankment?

8. EMERGENCY SPILLWAY

a. Does spillway concrete show:

(1) Spalling?

(2) Cracking?

(3) Erosion?

(4) Scaling?

(5) Exposed rebar?



DATE:

ITEM


(3) Leakage?

c. Is the spillway in rock or soil?(circle one)

(1) Are slopes eroding?

(2) Are slopes sloughing?

d. Is the discharge channel:

(1) Eroding or back cutting?

(2) Obstructed?

(3) Is vegetative cover adequate?

e. Has discharged water:

(1) Eroded the embankment?

(2) Undercut the outlet?

f. Is the weir in good condition?

9. VALVES/GATES

a. Are the valves/gates:

(1) Broken or bent?

(2) Corroded or rusted?

(3) Periodically maintained?

(4) Operational?

b. Is there a low level valve?

c. Is the low level valve operational?

10. AREA DOWNSTREAM

a. Recent downstream development?

b. Seepage or wetness?

11. OTHER COMMENTS/OBSERVATIONS (Include Date):

i12. SKETCI:IES:

12. SKETCHES:

Guidelines for Inspection and Maintenance of Dams

Documents

Transcript of Guidelines for Inspection and Maintenance of Dams