AD-AI05 310 REITZ AND JENS INC ST LOUIS MO / 13 3INATIONAL DA M SAFETY PROGRAM. STRUCKHOFFS DAM (MO 30100), MISSOU--ETCIU)

SEP 78 H M REITZ, J J BAILEY DACW43-78-C-OI62UNCLASSIFIED NL

Ho IIIIIIhEIIIIEEEIIIEIIIEEEEE

MISSOURI-KANSAS CITY BASIN

0

ST. CHARLES COUNTY, MISSOURI

MO 30100

PHASE 1 INSPECTION REPORT

NATIONAL DAM SAFETY PROGRAM

PREPARED BY: U.S. ARMY ENGINEER DISTRICT, ST. LOUIS \ j

FOR: STATE OF MISSOURI'p. D

SEPTEMBER 1978 DISTI,

Appy.v-, fc

UNrL ASSrTFTPSECURITY CLASSIFICATION OF THIS PAGE (Whmt Date Entored)

REPORT DOCUMENTATION PAGE READ INSTRUC71ONSBEFORE COMPLETING FORM

1. REPORT NUMBER 2. GOVT ACCESSION NO. 3. RECIPIENT1S CATALOG NUMBER

A ,-/o 31xc)4. TITLE (and Subtitle) S. TYPE OF REPORT & PERIOD COVERED

Phase I Dam Inspection ReportNational Dam Safety Program - Final eport,Struckhoffs Dam (MO 30100) 6. Pe~WNe O". RtPORT NUMBER

St. Charles County, Missouri7. AUTHOR(e) S. CONTRACT OR GRANT NUMBER(#)

Reitz & Jens, Inc.

___ DAC43_78.C_0162 "g. PERFORMING ORGANIZATION NAME AND ADDRESS 10.. iA1ttRWENT7 WlROJECT, TASK

AREA & WORK UNIT NUMBERSU.S. Army Engineer District, St. LouisDam Inventory and Inspection Section, LMSED-PD210 Tucker Blvd., North, St. Louis, Mo. 63101

II. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE

U.S. Army Engineer District, St. Louis September 1978Dam Inventory and Inspection Section, LMSED-PD ..:'sufo-PK-

210 Tucker Blvd., North, St. Louis, Mo. 63101 ADproximately 3514. OITORING AGENCY NAME & ADDRESS(I difflerent from Controlling Olflce) IS. SECURITY CLASS. (of thlA report)

( National Dam Safety Program. StruckhoffsDarn (MO 30100), Missouri - Kansas City UNCLASSIFIED

Basin, St. Charles County, Missouri. IS. DECLASSIFCATION/OOWNGRAOINGPhase I Inspection Report.

Is. OISTi

Approved for release; distribution unlimited. 'Tj.

17. DISTRIBUTION STATEMENT (of the abstract entered In Block 20, II diflerent from Report)

I. SUPPLEMENTARY NOTES

I. KEY WORDS (Continue On faors aide it neceaary and Identify by block number)

Dam Safety, Lake, Dam Inspection, Private Dams

26 ABSTRACT (Cbnbem mm aftf N reatvemy Idedtify by block number)

This report was prepared under the National Program of Inspection ofNon-Federal Dams. This report assesses the general condition of the dam withrespect to safety, based on available data and on visual inspection, todetermine if the dam poses hazards to human life or property.

DD W3 14O3 OF o10 NOVG IS OSOLETE N S E/,,/ AM SC r IFAI UNCL SIFIED/ , '.SECURITY CLASSIFICATION OfTI AE(he aeEtrd/ /1.,

S9CURITY CLASW VCATION OF THIS PAOSC(Wbm. Da EIIIU.

aSCUftITy CLASSIFICATION OF THIS PAGErlv,.n Date KnIorm)

DEPARTMENT OF THE ARMYST. LOUIS DISTRICT, CORPS OF ENGINEERS

210 NORTH 12TH STREET

~ST& LOUIS, MISSOURI 03101

ift safty RumFE y

SUBJECT: Richard Struckhoff Dam, ID No. 30100, Phase I InspectionReport

This report presents the results of field inspection and evaluation* of the Richard Struckhoff dam:

It was prepared under the National Program of Inspection of Non-FederalDams.

The St. Louis District has classified this dam as unsafe, non-emergencybecause the spillway will not pass 50 percent of the Probable MaximumFlood.

SUBMITTED BY: SIGNED 25 SEP 1978Chief, Engineering Division Date

APPROVED BY:_____________ z___SEP

Colonel, CE, District Engineer Date

A'-cession For

NTIS GRA&IDTIC TAB ClUnannounced___TEJustification-~ __

Distribution/ UC 19 1981AvailabilitY Codeos

Avail and/orDist SpecialD

RICHARD STRUCKHOFF DAMST. CHARLES COUNTY, MISSOURI

MISSOURI INVENTORY NO. 30100

PHASE I INSPECTION REPORTNATIONAL DAM SAFETY PROGRAM

PREPARED BY: REITZ & JENS, INC. UNDER CONTRACT WITHST. LOUIS DISTRICT CORPS OF ENGINEERS

FOR: GOVERNOR OF MISSOURI

SEPTEMBER 1978

PHASE I REPORT

NATIONAL DAM SAFETY PROGRAM

Name of Dam Richard Struckhoff DamState Located MissouriCounty Located St. Charles CountyStream Unnamed tributary to Bigelow CreekDate of Inspection 22 August 1978

Richard Struckhoff Dam was inspected by an interdisciplinary team ofengineers from Reitz & Jens, Inc. under contract with the St. Louis DistrictCorps of Engineers. The purpose of the inspection was to make an assessmentof the general condition of the dam with respect to safety, based upon avail-able data and visual inspection, in order to determine if the dam poses hazardsto human life or property.

The guidelines used in the assessment were furnished by the Departmentof the Army, Office of the Chief of Engineers and developed with the help ofseveral Federal and State agencies, professional engineering organizations,and private engineers. Based on these guidelines, this dam is classified asa small size dam with a high downstream hazard potential. The estimateddamage zone from failure of the dam extends two miles downstream from the dam.

Failure would threaten the life and property of two families and causeappreciable damage to a county road and the MKT Railroad.

-Our inspection and evaluation indicates that the spillway does not meetthe criteria set forth in the guidelines for a dam having the above size andhazard potential. The dam will begin to be overtopped by a flood having adischarge (peak and volume) equal to 35% of the PMF. The dam storage andprincipal spillway will contain a 1% chance flood (100-year flood) withoutovertopping the emergency spillway. This is a flood that has a 1% chanceof being exceeded in any given year.

Another deficiency found was the lack of seepage and stability analysisrecords.

Other deficiencies observed by the inspection team were tree growthstarting on the downstream face and shallow erosion channels on the downstreamface and at the toe of the dam on the west slope.- f

We recommend that the owner take action to correct or control the defi-ciencies described. A detailed report discussin each of these deficiencieswas prepared and submitted to the lake o7 a toe ror of Missouri.

i M

& REITZ,

Preside

t

JOHN J. BVE, JR., V C hChief EngineerReitz & Jens, Inc.

OVERVIEW - MO. 30100

PLATE I

PHASE I INSPECTION REPORTNATIONAL DAM SAFETY PROGRAM

RICHARD STRUCKHOFF DAM - ID NO. 30100

TABLE OF CONTENTS

Paragraph No. Title Page No.

SECTION 1 - PROJECT INFORMATION

1.1 General 11.2 Description of Project 11.3 Pertinent Data 2

SECTION 2 - ENGINEERING DATA

2.1 Design 42.2 Construction 42.3 Operation 42.4 Evaluation 4

SECTION 3 - VISUAL INSPECTION

3.1 Findings 63.2 Evaluation 7

SECTION 4 - OPERATIONAL PROCEDURES

4.1 Procedures 84.2 Maintenance of Dam 84.3 Maintenance of Operating Facilities 84.4 Description of Any Warning System in Effect 84.5 Evaluation 8

SECTION 5 - HYDRAULIC/HYDROLOGIC

5.1 Evaluation of Features 9

SECTION 6 - STRUCTURAL STABILITY

6.1 Evaluation of Structural Stability 10

SECTION 7 - ASSESSMENT/REMEDIAL MEASURES

7.1 Dam Assessment 1]7.2 Remedial Measures 11

APPENDIX

A Hydrologic Computations A-i

TABLE OF CONTENTS (Cont.)

LIST OF PLATES

Plate No. Title

1 Overview - Lake and Environs

2 Plan and Profile Sheet (in pocket on back cover)

A-I (5 sheets) Hydrologic and Hydraulic Computations

(HEC-1 Input and Output)

LIST OF INDICES AND PHOTOGRAPH NUMBERS

Index No. Title

1 Index of Dam Photos (Dl through D8)

2 Index of Panorama Photos (P1 through P2)

3 Index of Spillway Photos (S1 through S4)

4 Index of Valley Below Dam Photos (VI through V7)

5 Index of Seepage Photos (SEl through SE4)

Lt

SECTION 1 - PROJECT INFORMATION

1.1 GENERAL

a. Authority The National Dam Inspection Act, Public Law 92-367,authorized the Secretary of the Army, through the Corps of Engineers, toinitiate a program of safety inspection of dams throughout the UnitedStates. Pursuant to the above, the St. Louis District, Corps of Engineers,District Engineer contracted with Reitz & Jens, Inc. (Contract DACW43-78-C-0162)for a safety inspection of the Richard Struckhoff Dam.

b. Purpose of Inspection The purpose of the inspection was to make anassessment of the general condition of the dam with respect to safety, basedupon available data and visual inspection to determine if the dam poseshazards to human life or property.

c. Evaluation Criteria Criteria used to evaluate the dam were furnishedby the Department of the Army, Office of the Chief of Engineers, in "RecommendedGuidelines for Safety Inspection of Dams". These guidelines were developedwith the help of several Federal agencies and many State agencies, professionalengineering organizations and private engineers.

1.2 DESCRIPTION OF PROJECT

a. Description of Dam and Appurtenances

(1)'The dam is an earth structure built in a narrow draw in the uplandsof the Missouri River Bluffs. Topography adjacent to the valley is rollingto steep. Soils are formed in thick loess deposits over weathered materialfrom the St. Peters Sandstone. Topography in the vicinity of the dam isshown on Plate 2. From 1"=2000' aerial photographs taken in 1977, it appearsthat about 70% of the watershed is cultivated and about one-half of this areais contoured. A 30-acre portion of the watershed at the northwest extremityis severely eroded.

(2) An 8-inch steel pipe (principal spillway) is provided to bleed offwater retained in the lake. Additional spillways (emergency spillways), flatchannels excavated in earth, are provided at each abutment.

(3) Pertinent physical data are given in paragraph 1.3 below.

b. Location The dam is located in the southwestern portion of St. CharlesCounty, Mo. in the NW of the SW of Section 10, T44N, RIE, as shown on Plate2. The lake formed by the dam is not shown on the Missouri-St. Charles CountyWashington East Quadrangle Sheet (1972).

c. Size Classification Criteria for determining the size classificationof dams and impoundments are presented in the guidelines referenced in para-graph l.lc above. Based on these criteria, this dam and impoundment are in thesmall size category.

d. Hazard Classification Guidelines for determining hazard classificationare presented in the same guidelines as referenced in paragraph c above. Basedon referenced guidelines, this dam is in the High Hazard Classification.

A1

e. Ownership This dam is owned by Richard Struckhoff, Route 1, Augusta,

Missouri, 63332, who also owns and farms the greater part of the watershed aswell as adjoining property.

f. Purpose of the Dam The dam forms an 8-acre recreational andagricultural lake and serves a flood control function for interior drainageof the Hancock Bottoms.

g. Design and Construction History The dam was constructed between1970 and 1972. Design and construction advice was furnished by the USDA

Soil Conservation Service. Contractor's name, design and constructionrecords are not currently available.

h. Normal Operating Procedure Normal rainfall, runoff, transpirationand evaporation all combine to maintain a relatively stable water surfaceelevation. The principal spillway pipe is capable of discharging waterponded to the level of the emergency spillway in 5 to 6 days. The maximumwater depth ever experienced at the spillway is unknown.

1.3 PERTINENT DATA

a. Drainage Area - 157 acres, 70% cultivated (35% terraced) 20% eroded.About 1/2 Menfro silt loam and 1/2 Winfield silt loam soils according tothe soil map of St. Charles County, Mo., surveyed in 1937 and published in1955.

b. Discharge at Dam Site

(1) Discharge at the dam site is through an uncontrolled 8-inchdiameter steel pipe. Emergency spillways are provided at the east and westends of the dam. The elevation of the west spillway is so high, relativeto the top of dam, that it provides little usable capacity.

(2) Estimated experienced maximum flood at dam site - unknown.

(3) Estimated ungated spillway capacity at crest of dam elevation6 cfs in principal spillway; 282 cfs east emergency spillway; 30 cfs westemergency spillway; total 318 cfs.

c. Elevation (Feet above M.S.L.)

(1) Top of dam -527.0 to529+ (see Plate 2).

(2) Spillway crest - 519.4 Principal spillway524.4 East Emergency Spillway526.6 West Emergency Spillway

(3) Streambed at centerline of dam - 493 (est.)

(4) Maximum tailwater- unknown.

d. Reservoir Length of maximum pool - 1800 ft.+ (est. from USGS

Contour Map).

e. Storage (Acre-feet) Crest of principal spillway - 73 Ac/ft. (est.)Top of dam - 156 Ac/ft.

21

f. Reservoir Surface (Acres)

(1) Top of dam 14.0 Acres (interpolated from USGS)

(2) Principal Spillway Crest - 8.3 Acres (est.)

g. Dam

(1) Type - earth embankment

(2) Length - 400 feet

(3) Height - 36 feet maximum

(4) Top width - 13 to 14 ft.

(5) Side slopes -

(a) Downstream - iV on 2.4H (determined from Stations 2+00and 3+00, Plate 2.)

(b) Upstream - IV on 3H to water surface - below water surfaceunknown.

(6) Zoning - unknown

(7) Impervious core - unknown

(8) Cutoff - unknown

(9) Grout Curtain - unknown

h. Diversion and Regulating Tunnel - None

i. Spillways

(1) Principal spillway - smooth steel 8-inch pipe with trashrackthrough dam approximately 145 feet long at 15%+ average grade. Upper flowlineat elevation 519.4; lower flowline elevation 493.7.

(2) East Emergency Spillway - 8-foot flat bottom earth channel withIV to 6H and IV to 10H side slopes at control section; crest elevation 524.4+.

(3) West Emergency Spillway - 25-foot flat bottom earth channelwith IV to 8H and IV to 25H side slopes at control section; crest elevation526.4+.

J. Regulating Outlets - None

3-

SECTION 2 - ENGINEERING DATA

2.1 DESIGN

No design data were found to be readily available.

2.2 CONSTRUCTION

The dam was constructed between 1970 and 1972 with advice from thelocal representatives of the USDA-SCS. No additional construction dataare currently available.

2.3 OPERATION

Lake levels remain stable during average precipitation of 38 inchesper year. It appears from the condition of the east emergency spillway thatwater has flowed over it at some time since completion.

2.4 EVALUATION

a. General The inspection team believes the Soil Conservation Serviceof the U.S. Department of Agriculture furnished design and construction advicefor this dam and others in the Bigelow Creek watershed.

During the period of the late 1960's and early 1970's, SCS was imple-menting a project to minimize problems of interior drainage in the HancockBottom generally between Missouri River Miles 61L and 65L. Bigelow Creekflows between the toe of bluff and this bottom. Construction of a series ofupland dams, proportioned to contain at least the 100-year runoff, reducedpeak flows in the relatively flat lower end of the creek. Crop damage fromflooding in the bottom was thereby reduced.

Some confusion was found in SCS records because of incomplete descrip-tions of each of the dams in which they had some involvement which was furthercomplicated by several of the different ground owners having the same surname.The description by section and name of owner could be any one of several dams.Further, there is considerable similarity between lengths and heights of damsmaking specific identification of an existing record questionable. (Note:an effort is being made Lo retrieve copies of original field notes and surveyswhich would clarify this matter.)

b. Adequacy The engineering data available were inadequate to make adetailed assessment of design, construction and operation. The owner shouldhave an engineer, experienced in the design of dams, perform detailed seepageand stability analyses.

However, for the size of dam, materials used and measurements taken, a* satisfactory hydrologic/hydraulic evaluation resulted. Also, for the section

and the presence of the primary spillway plus the visual inspection of a damwith reservoir of at least 6 years of age, the generally good condition of thedam, when considered by the experienced engineers, indicated that even thougha detailed assessment of the design and construction in an analytical sensewas not possible, a defensible evaluation of the dam as a structure, wasfeasible.

4

c. Validity This report is primarily for safety through maintenance

and operation and the conclusions and evaluation for this Phase I Inspectionare considered to be adequate for the definitive statement to this report.

5I

I

I

5."

6Q

SECTION 3 - VISUAL INSPECTION

3.1 FINDINGS

a. General A visual inspection of the Richard Struckhoff dam was madeon 22 August 1978. This followed two days of field measurements by a surveyparty on 25 and 26 July 1978. The training and experience of personnel inthese two inspections included hydrologic/hydraulic engineering, soils andmaterials engineering, surveying and structural engineering. Specificobservations are discussed below.

b. Dam The grade of top of dam is relatively uniform for an earth dam.Vehicles infrequently will cross the dam.

Both the downstream and upstream slopes of the dam were covered withhealthy growth of low grass. Neither slope had any weed growth as differ-entiated from grasses. There is marked freedom from shrubs or undergrowth.Several first-year tree seedlings, less than 2 feet high (photo D4) werevisible. There was some shallow erosion in a ditch typical of the erosionpattern for the low plasticity soils which had resulted from overland flowoff the downstream face of the dam. At one point, entering the erosionpocket at the lower end of the spillway from the east (photo SE2) had alsoa relatively indistinct "Y" erosion pattern upslope from this entry intothe photo number area (photo D4). There is also some erosion at the contactof the toe of dam and virgin soil running up the west slope and the originalground surface (photos Vl and V2). Some water, less than an inch deep, wasin the bottom (photo SEl).

No hydrophilic plants were at or above the downstream toe of the dam inany portion.

c. Appurtenent Structures Some trash had accumulated on the rack at theend of the principal spillway which is shown on photo Pl. The discharge endof the 8-inch pipe from the principal spillway appeared to be at the originalground surface (photo V3) in the life of the dam, a limited erosion, roughlycircular in shape, about 6 feet in lateral dimension and to a depth about3 feet below the flowline of the pipe, had occurred. Since the bottom ofthis scour hole is below the downstream channel, water was standing in it.

The east emergency spillway is lower and better defined than the westand it carries the majority of flow when the high intensity storms occur.The east is an earth spillway beyond the end of the dam in virgin soil withgrass cover of the same nature as the dam and surrounding fields (photosS3 and S4). While there is a fence with change in direction in this generalarea, the location of the posts and the heights of the barbed wire strandsare such that they will not catch debris which could adversely affect thecarrying capacity of this spillway. Water, flowing over this spillway, isconfined by a low man-made dike along the west side (photo S4) which directsits flow into a deep, natural channel that is downstream from the dam andbeyond another fence line which roughly parallels the dam from the east tothe west (photo V4).

6

At the west end of the dam there is some additional capacity for flowsto leave the reservoir before the lake level reaches the top of the dam.This spillway at this location is less well defined (photo Sl).

d. Reservoir Area No wave wash, excessive erosion or slides wereobserved along the shore of the reservoir.

e. Downstream Channel Except as described in paragraph 3.1c above, thedownstream channel is in good condition.

3.2 EVALUATION

None of the conditions observed is significant enough to indicate theneed for immediate remedial action or a serious potential failure. Continuedannual attention to cutting growth on the slopes of the dam is suggested.The shallow erosion channels that were enumerated and can be observed onthe downstream face due to surface runoff should be filled and then turfre-established.

!

.7 l

SECTION 4 - OPERATIONAL PROCEDURES

4.1 PROCEDURES

There are no controlled outlet works for this dam; therefore, noregulating procedures exist. The pool is controlled by rainfall, runoff,evaporation and capacity of the uncontrolled spillways, in particular,the 8-inch pipe principal spillway which is capable of evacuating waterstored to the elevation of the emergency spillway crest in 5 to 6 days.

4.2 MAINTENANCE OF DAM

Based on the size of weeds and brush growing on the dam it appearsthat the slope has been cut at intervals sufficient to keep trees and bushesfrom being established. Some attention should be given to filling theerosion channels on the downstream face of the dam described in paragraph3.1c.

4.3 MAINTENANCE OF OPERATING FACILITIES

No operating facilities exist at this dam.

4.4 DESCRIPTION OF ANY WARNING SYSTEM IN EFFECT

The inspection team is not aware of any existing warning system forthis dam.

4.5 EVALUATION

If the vegetation on the downstream slope is allowed to continue,a serious potential of failure may develop.

8

SECTION 5 - HYDRAULIC/HYDROLOGIC

5.1 EVALUATION OF FEATURES

a. Design Data No design data are available.

b. Experience Data The drainage area is developed from V"f;S WashingtonEast Missouri Quadrangle. The lake surface area was determint from a 1"-200'enlargement of a 1"-2000' aerial photograph obtained from Surdex Corp. Picturewas made 22 March 1977. The spillway and dam layout are from surveys madeduring the inspection.

c. Visual Observations

(1) The 8-inch smooth steel pipe principal spillway and the eastand west emergency spillway channels are in good condition. The east emer-gency spillway channel shows evidence of erosion from flow through it.

(2) No drawdown facilities are available to evacuate the pool.

(3) The principal spillway pipe is located at the west abutment.Spillway releases will not endanger the integrity of the dam.

d. Overtopping Potential The spillways are too small to pass theminimum required flood of one-half the probable maximum without overtopping.The probable maximum flood is defined as the flood discharge that may beexpected from the most severe combination of critical meteorologic andhydrologic conditions that are reasonably possible in the region. The damwill start to be overtopped by a flood equal to 35% of the PMF. The one-halfPMF will overtop the dam to a maximum depth of about 0.94 feet. The depthwill vary to zero across the dam because of the sloping crest. A width of140+ feet of dam crest will be subject to some overtopping flow. Maximumrate of flow over the dam crest will be about 135 cubic feet per second.Overtopping flow will have a duration of one hour and 30 minutes. The existinglake and principal spillway will contain a 100-year frequency flood below thecrest of the emergency spillway. According to the recommended guidelinesfrom the Department of the Army, Office of the Chief of Engineers, the 100-year frequency flood is only adequate for a low hazard dam of small size.

Failure of the four small upstream water impoundments shown on the 1972revised USGS map would not have a significant impact on the hydrologic orhydraulic analysis.

The effect from rupture of the dam could extend approximately two milesdownstream of the dam. Within the damage zone are two farmhouses and asso-ciated farm buildings, one main county road and one railroad bridge.

9

SECTION 6 - STRUCTURAL STABILITY

6.1 EVALUATION OF STRUCTURAL STABILITY

a. Visual Observations Visual observations which adversely affectthe structural stability of this dam are discussed in Section 3, paragraph3.1b.

b. Design and Construction Data No design or construction datarelating to the structural stability of the dam were found.

c. Operating Records No appurtenant structures requiring operationexist at this dam.

d. Post Construction Changes No post construction changes, otherthan those referenced to in paragraph a above, exist which will affect thestructural stability of the dam.

e. Seismic Stability Considering the seismic zone (2) in which thisdam is located, an earthquake of this magnitude is not expected to cause astructural failure of this dam.

. 10

a - ,

SECTION 7 - ASSESSMENT/REMEDIAL MEASURES

7.1 DAM ASSESSMENT

a. Safety Several items were noted during the visual inspection bythe inspection team which should be corrected or controlled. These itemswhich exist on the downstream slope are young trees beginning to grow anderosion. The stability of and seepage conditions on the downstream slopeshould be investigated by an engineer experienced in the design of dams.The one-half PMF will overtop the dam; however, the reservoir and principalspillway are adequate to contain a flood which has a 1% chance of beingexceeded (100-year flood) in any given year.

b. Adequacy of Information Due to the lack of engineering designand construction data, the conclusions in this report were based on per-formance history and external visual conditions. The inspection teamconsiders that these data are sufficient to support the conclusions herein.

c. Urgency The remedial measures recommended in paragraph 7.2 shouldbe accomplished in the near future. If the safety deficiencies listed inparagraph a are not corrected in the near future, they will continue todeteriorate and lead to a serious potential of failure.

d. Necessity for Phase II Based on the results of the Phase Iinspection, no Phase II inspection is recommended.

e. Seismic Stability This dam is located in Seismic Zone 2. An

earthquake of this magnitude is not expected to be hazardous to this dam.

7.2 REMEDIAL MEASURES

a. Alternatives Spillway size and/or height of dam should be increasedto pass one-half the probable maximum flood without overtopping the dam.

b. Perform Stability and Seepage Analyses If the results indicate aneed, appropriate corrective measures should be designed and constructed.

c. O&M Maintenance and Procedures The following O&M maintenance andprocedures are recommended:

(1) Remove first-year sapling trees and vegetation from the down-stream slope. Care should be taken during removal not to destroy the existingcondition of the downstream slope.

(2) Fill, grade, fertilize, seed and mulch the erosion channels onthe downstream slope. If these are allowed to continue to erode, eventualsloughing and sliding of the downstream face of the dam may occur.

(3) Periodically check the condition of the 8-inch steel pipethrough the dam for evidence of corrosion and leakage. Water leaking into orout of a corroded principal spillway pipe could cause piping failure of theearth embankment.

~11

:I

(4) Maintain the trash rack at the inlet of the principal spillway.Remove accumulations of trash which, if left in place, could eventuallygreatly reduce the capacity of the pipe.

(5) The owner should keep a record of all future repairs andmaintenance.

(6) A detailed inspection of the dam should be made periodicallyby an engineer experienced in design and construction of dams.

I1

Il

I1

j APPENDIX A

HYDROLOGIC COMPUTATIONS

HYDROLOGIC AND HYDRAULIC ANALYSIS METHODOLOGY

1. The hydrologic analysis used in development of the overtoppingpotential is based on applying a hypothetical storm to a unit hydrographto obtain the inflow hydrograph for a reservoir routing. The ProbableMaximum Precipitation for those dams in the high hazard potentialcatagory is derived and determined from regional charts prepared bythe National Weather Service in "Hydrometeorological Report No. 33."Reduction factors have not been applied. A 24-hour storm duration isassumed with the 24-hour rainfall depths distributed over 6 hour periodsin accordance with procedures outlined in EM 1110-2-1411 (SPF Determin-ation). The maximum 6-hour rainfall period is then distributed tohourly increments by the same criteria. Within-the-hour distributionis based upon NOAA Technical Memorandum NWS HYDRO-35. The non-peak6 hour rainfall periods are distributed uniformly. All distributedvalues are arranged in a critical sequence by the SPF criteria. Thefinal inflow hydrograph is produced by deduction of infiltrationlosses appropriate to the soil, land use, and antecedent moistureconditions.

2. The reservoir routing is accomplished by using Modified Pulsrouting techniques wherein the flood hydrograph is routed throughlake storage. Hydraulic capacities of the outlet works, spillway,and crest of dam are used as outlet controls in the routing.Storage in the pool area is defined by an elevation-area curve. Thehydraulic capacity of the spillways is defined by an elevation-discharge curve. The hydraulic capacity of the sloping top of damis defined by a triangular broad-crested weir equation.

3. Dam overtopping analysis has been conducted by hydrologicmethods for this dam and lake. This computation determines thepercentage of the PMF hydrograph that the reservoir can containwithout the dam being overtopped. An output summary in thehydrologic appendix displays this information as well as othercharacteristics of the simulated dam overtopping.

4. The above methodology has been accomplished for this reportusing the systemized computer program HEC-1 (Dam Safety Version),July 1978, prepared by the Hydrologic Engineering Center, U.S. ArmyCorps of Engineers, Davis, California. The numeric parametersestimated for this site are listed on PLATE 2A. Definitions ofthese variables are contained in the "User's Manual" for thecomputer program.

.A-1

HYDRAULIC COMPUTATIONS

5. Capacity of the 8-inch pipe spillway was based on one velocityhead energy and 0.5 velocity head entrance loss up to 6 cfs. Abovethis discharge friction in the outlet pipe controls. The dischargein the emergency spillways was calculated using critical depth at thecontrol section near where the dam centerline crosses the spillwaychannels, allowing 0.2 velocity head for non-uniform velocitydistribution, velocity transition losses and friction in the shortapproach channel. This is equivalent to calculating the spillway asa broad-crested weir with a discharge coefficient of 2.80.

b

CCD *'C C

er 0

Ln in* C*

hC-O

.. oc cr .c I et..* 0 f CC 4( f c cc

00 * C Lv.0 0 0

Ow a.(

O7w a- - -e *NOZ .4 4 c

W4 4 % 0

~0e Qr - - r a'

CC4UC Q ft %C - Cca, cc c m.

0 It.

C U

cc Qt

CLI Li' If -- C N:I- f * fl6ft U

-ft

Sheet 1 of

0. 0.

U

cCr

LL C -CCc II, .;c

*r0- c 0c 4 cw 0 - II C

ct 4.OtC20 1- C. W - .I

if CDI L.I.JCc l C if 9

2 ft If uC IL6 (F It.

P.... 7J -a 3if.. 7 CC C.; .0 1-

a.fi ftS m.- a. CC t\I-. u0.i 1-7 C 1- - Cr I

>ifi c It CL c I.- . C 'I

u-ii 0 v 't. C -e-F-(r'ii if C.; 2: ~ c ftr1

I. if CI NC (p W *C ~ zi 7- if 2 I I'. Cf C

UIfU 0. 4r if f; 3- 7 , 1I 0-

if.. i IC *CCifi. C. i t c

ji It ft wC It It t

Ln I , ft O L- ft Ir cn tr 11 u v,

00' 0 1.10 c cU 7- C- 4. SI

c t @ fZi- 1' if Ot 1 * r I-. .) I 4 1C,-f ,r It C . i 0 c .C Oft IfCL (I LL.

rCf c Z C .1 1- U ft I - .

ar .. f I. 0 ft *. CE . I .

At . 7C i f 2l CrON aN 'I C C f.

AtI ft c tr I- .I' 2c £ s t CC420 II C.. UU.2-

U.. At 270 ft4-4 .0 C

AN-C m-fl 0f -MC. 2. ftx - C

:0 M4 ft -U Cf ; t UAtr -9 c- aC0 .J . I

2t O- >. Ct if c 2CL) - - i 1- I-0 LL u

-~ "If 0 - - 0

0U.'4See 2f of~ 5-*C

4.CN Wt r- r- m m 0 M C - 4 Wt C Z' 'V C 'C ZC N- 04 'D fN W x C M C C V M 4 7 Z C N F7 m a N a N & F 'C a, At Wt Wt 'r 0

.... M. . . . . .4' C N N C OC C ~~~t ~ t r t, t

.cCC CC'000I0CcOte.- P..- CC A ceC, 4),a a a a &c 17a61r

c. eCuec e cc ccecc e c c c c cc eCCe ce o -e e

O~occOCC~~e44444At t~t~tar . .W NC A4CN C ~ '' .- OO O .777..I.

r t N N N N zN NNz zf 7 7 z .z-.zL77,Ul t rp rML U , A 1,1-rC'IC u I,-' At 7C UN N Nt. 0,N & N N& 0 & M

4444421 1 tM -Mtlme 444-04'9 -*-C'C'C'C'C'C'CNNNNNNCC ""ctCC c Qrc Cz CC~ C ce 0 e

.......................................................

o f -Z ?-C C CC 0 C C M0 C 0 It C 0 rw a F, 04 C1 0 P0 00 C F 0 t0 CC 0 W0 * C ;: N F 0 C(N F- Cc a 0...... ...... ...... ...... ...... ...... ......

------------------------------------------------

- - . .- . .- . .- . .-.--. --. --. --.-. .-. .- . .- . .-.-- .--.--.--.- . .- . .-. .-.

O..........( NNNN NNNN t.NN NNN NNN77444t~t.t'C''CNN 0PLATE' Aco- --

O ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~he 3 00000000 5 0000 000 000000

r44 4444 44 4 4 4W w w w ut ccNNw e

MM M M MMN NN NN NN NN NN NN NN NN NN NN N&N N N & K N M N M N N N N M M N r. N & M N N Nl N

a 0 N N Nr , Nw 0000 000O000 C0 00 000OM0 U0 000 0 00 0 O000 w00 0 000O a0 000000w

... .. .. .. .. .. .. ... .. .. .. .. .. .. ..

N! . . . .N N .N 10 Ct 0 0 00 0 C CO 0 C0C C 0 C 000 C C C. C C. C CO 0. C C C. C:

.0' . -N... ..Ir C -NMC.' CO 0N.r~- u C C. C.7 C.' C..N4I C9£'..N4, - C

Lrr~t~ll~r--COCOC CCC CO 'OC 0''claw000 00c --------- &&a* NNNNN

- - - - -- - - - - - - - - - - - - - - - - - - --. .. . . % ..... . . N. . . .. .. . . . . . .. . .

------------------------------------------------------

C C00 0 C0 0 00 0 CC C0 00 C0 00 0 0 0 CC CC C 00C 0 00CC PLCA0TECC'A-0 00

..... ..... ..... ..... ..... .. e.. ..... ....

0:u ce;cea:

c c (r CCC~cC~Cc

C4

0?-~~np OL..U EFC -CNN")M

CC CC OC CC CC;C ccC MI. C~ r

m CO # OD 0c

ft mU w- I- CCaaC m Vr-m

NNNN NNNNNa a' - V. mccecr-NOe

ft a a t 1W

~~ It

N~ ~ M.' r'.,4

N'~ M fMfM 4

.N :D. Z 4 w (. 3 (9cC -C >. > c4 ' N

OCCrC0!CCC CCCCCC rUFN Ia t.jMI, a

ma p

=0 4'41t 04 CI

P - wa a0

a * N -;c

wC -D I8- -C-ZC I 1 c Z -DcI l al

2t c

*4 4* -43 j E U t lI

> aLL. 7>1 .%. .r.r-p P t - I-1 t- .t. P . - .I- I -- LLc t: IXI MiIi %cC E~ft'c r- .?.1,.

(reC 0 00 0 00 0 x -.- L C C Cc:* c *: % C. % :Out XL

r-~~~ ~ ~ & a t

N- L, LL L,.-ff0-Nfc4I * c

C* c: C . .%I . *af.

CL

tc~t~atoa'oatPLATE A-1af~P44If~t0CSheet"45 ofI5

*0 (00 200 400

FEET

EDGEOF

POOL

PHOTO INDEX IFOR

DAM

STRUCKNOFFS DAM

PREPARED BY ST CHARLES COUNTY, MO.

REITz a JENS, INC SEPTEMBER 1978

p'*

9A

eA

- vt

.4*4V

''I 'f 'i

0 loo 200 400

FEET

EDGEOF

POOL

Vsa

PHOTO INDEX 2FOR

PANORAMA

STRUCKHOFFS DAMPREPARED GY ST. CHARLES COUNTY, MO.

REITZ a JENS, INC SEPTEMBER 1978

Al''

PANOR A

£0 lo0 200 400

FEET

EDGE0OF

POOL

I-I

t PHOTO INDEX 3FOR

SP ILL WAYS

STRUCKHOFFS DAM

(IPREPARED BY ST. CHARLES COUNTY, MO.REITZ & JENS, INC SEPTEMBER 1978

r

CV)k

j~4

304

SPIL t 1 '.1

0 100 200 4C0

FEET

EDGEOF

POOL

4--

PHOTO INDEX 4 4

FORVALLEY BELOW DAM

STRUCKHOFPS DAMPREPARED BY ST CHARLES COUNTY, MO.4REITZ 8 JENS, INC SEPTEMBER 1978

Aft..

,x VALLEY BELOW

-LN

ti.r

* '~f der

is.o

0 100 200 400

FEET

EDGEO F

POOL

SE2

PHOTO INDEX 5FOR

SEEPAGE

STRUCKHOFFS DAMPREPARED BY ST. CHARLES COUNTY, MO.

REITZ & JENS, INC SEPTEMBER 1978

v

E4

A~INA

4'

N .4i f ..

~C~)..or

NN

t:4:

%i. .,

410.

vI j

SE EPAGE

............. ~ru.

...- . . . .I o

8"DIA.~4 Sf ..

0 8"I 00S~OTH STEELPIPE 145± LONG WITH ~ .* ~

> TRASH RACK AT INLET.

zuj

z z(0 o

FL. ELEV.73.7

I'FDA N

I tnC~f

A. .

MO-

.009

>4i

-,-

I tV

WATE RSHED A ND OUT F L W 7C

roe

OW.

C S.o

TFLW HA-E

0 50 100 200 300FT

. . . . . . . . . . . .I-~. . . . ._ __.. . ._

. . . . . .

.U. . . . . . .

........

. . . . . . . .

0.... ......... ....... __ ._ _ _ _

. ......... ..........

.... ~ILA .... ... SPLL A

30FT

. _ _ _ _ .. _.._.. ._. . 120_ _ _ _ _ _ _ _

~OF DAM.. . ... AT ER

EV8L.. .. . .. . . 25 JU LY'78 .-

.. ........ ... .0 9 . . 2,

.. .o : ... .. .. _ _

.. _ ..... ... .8 .. _ ._ _: :_ 0_

.. .... ... UN I 9 ..... . . . . .. ... ...6 0. .. . . . . .

.... ... .......... . . . . . . . . . . . . . . . i

.. . . . .. . . . . . . .. . . . . I . . . . . . .. . . . . . . . .. . . .

.o b --ta 40OFY

_________ __ _ ____ ___ ___ ____ _ __ ____ 120_ _ _ _

q- OF DAM

* *100

___ SECTION 0 DAMAT STA. 00

1 0. ....... I .. . .2 0. .

... T....N F .A ... _ ..... ... _ .....

STA.... 3..+.....00

. . .. ~ ~ H GH A . .O ~A . . . . . . . . . .H. . . . . . . . . . . .

PLAT 4..NGL PLAN. AND C.OS ....N ~ ...001......... ..... ...m. ...

0 1000 2000 4000 s00

. . . ......

. . . .. .. . .

. . . . . . . . . ... . ... . .U P P E R. .I .. F. L. 8":pP

... ... .... 6+Q 5+40 '4+ 80 4+20 3+0 3+ 0 2+40

. . . . .~~ . .D A S C.. . . . . . .I . . . . .. . . J L E S

: . 5.C tE

- ~~ -2 OF__ -DAM. . . . . . .. . . . . . . . . . . . . . . . . . . . . . .

... . .. ... . .. I. . . .. ... . .... ... VE T .:-

. . . .. . . . . . . . . . . . . . . . . . .

10.0. 0+60 -+2 1+8

.~ ~ R .. LE.. 0... WEST..

.. .. .. EM E . ~ C .... LLW. .. .Y. ... . .... .. .-. V. .

. . . . ." .. .... .T.2 3'

loo: ~ ~ ~ ~ ~ ~ ~ ~ ~ D 420... 0 .LVA ONS. S. N... ....... . 0 . ..

00,~BT I ... .. ... .. . . D .. ... ..

. .. . .. .

No4000 6000 FT.

4 l10

. . .. . . .. .. to

0 3+.0. +40 -f s 1+2 0+6 0+0

- "' VERT -

1~~ ~ ~ ='-OI. LO A

. . .... ... .

r* 1+8so 1+ 20 0 .+60 .. 0+00

PROF~ [-E OF: EASM. ERGE'Ny CYSPI 'LWAY-

I 1:'.5 VERT... . .. PHASE ......- INSPECTION6... COUNTY 1. D. NO. 183

*'A.....ST. CHARLES COUNTY, MISSOURI. ... .. ...... INVENTORY NO. 1. D. 30100

ILVA O S H NTOO ST. LOUIS DISTRICT, CORPS OF ENGINE~fts.... .... EITZOr JNS, NC.ST. LOUIS, MISSOCUM

..... _._..... Ot4SULTING ENGINEEIRS 19TE WR gi

'10 PLATE 2. ,-