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COMMISSIONERS' COURT AGENDA REQUEST
PLEASE FURNISH ONE ORIGINAL AND NINE COPIES OF THIS REQUEST
AND DOCUMENTS TO BE REVIEWED BY THE COURT.
MADE BY: Commissioner Williams OFFICE: Precinct 2
MEETING DATE: November 27, 2006 TIME PREFERRED:
SUBJECT: (Please be specific).Consider, discuss and take appropriate action
on report and recommendations of TCEQ Dam Safety Division regarding Flat Rock Lake
Dam.
EXECUTIVE SESSION REQUESTED:
NAME OF PERSON(S) ADDRESSING THE COURT: Commissioners Williams.
ESTIMATED LENGTH OF PRESENTATION:
IF PERSONNEL MATTER-NAME OF EMPLOYEE:
Time for submitting this request for Court to assure that the matter is posted in
accordance with Title 5, Chapter 551 and 552, Government Code, is as follows:
Meeting scheduled for Mondays: 5:00 P.M. previous Tuesday
THIS REQUEST RECEIVED BY:
THIS REQUEST RECEIVED ON:
All Agenda Requests will be screened by the County Judge's Office to determine if adequate
information has been prepared for the Court's formal consideration and action at time of Court
meetings. Your cooperation is appreciated and cornributes towazd your request being addressed
at the eazliest opportunity. See Agenda Request Rule adopted by Commissioners Court.
5' ~
Kathleen Hartnett White, Chairman , ~ `-
/ r f ~r ~~,
Larry R Soward, Commissioner 1~ ~.i
Martin A. Hubert, Commissioner \ ~m~ i~
Glenn Shankle, Executive Director ~~_
TEXAS COMMISSION ON ENVIRONMENTAL QUALITY
Protecting Texas by Reducing and Prettenting Pollution
November 8, 2006
Mr. William "Bill" Williams
Commissioner Precinct No. 2
Kerr County
700 Main
Kerrville, Texas 78028
Re: Kerrville Lake Dam, (Flat Rock Dam)
Inventory # TX 02457
Kerr County
Deaz Mr. Williams:
I would first like to thank you and Mr. Leonard Odom for your assistance in inspecting
the Kerrville Lake Dam. Your assistance and information you provided were important
in the completion of the report generated by the inspection. Enclosed is a copy of the
inspection report as well as a list of engineering firms experienced in dam design,
construction and repair.
As noted in the inspection report, the dam was found to be in fair condition. Of primary
concern for this structure is the need to determine the integrity of the concrete cap and the
condition of the underlying fill material.
It was a pleasure to meet you and Mr. Odom and thanks again for your assistance. If you
have any questions regarding the dam or our program please feel free to contact me at
(512) 239-0416.
Sincerely,
Bob Wucher, P.E.
Dam Safety Program
Field Operations Support Division, MC -174
Attachments
P.O. Box 13087 • Austin, Texas 78711-3087 • 512/239-1000 • Internet address: www.tceq.state.tx.us
printed on recycled paper usln~* sny teased ink
~~
TCEQ DAM SAFETY
,Field Operations
~~ Dam Evaluation Report
`~ November 1, 2006
TCEC~
Kerrville Lake Dam (Flat Rock Dam) TX 02457
GENERAL INFORMATION
INVENTORY NG.: TX 02457 WATER RIGHT ADJUDICATION: 02004
OWNER: Kerr County
STREAM: Guadalupe River
BASIN: Guadalupe River Basin
COUNTY: Kerr
GENERAL LOCATION: 2.4 miles southeast of Kerrville, Texas
DAM HEIGHT: 2O R DOWNSTREAM HAZARD RATING: LOW
NORMAL CAPACITY: 720 aC-ft MAXIMUM CAPACITY: 820 aC-$
NORMAL WATER LEVEL: 1561 feet mean sea Level (msl)
CURRENT WATER LEVEL: 1561.2 feet mSl
PREVIOUS INSPECTION DATE: DOCembeT 5, 1988
CURRENT INSPECTION DATE: NOVember 1, 2006
INSPECTION BY TCEQ PERSONNEL: BOb WUCher P.E.
Johnny Cosgrove, P.E.
PERSONNEL CONTACTED: Bill Williams, Ken County Precinct 2 Commissioner
INTRODUCTION
On November 1, 2006, Mr. Bob Wucher and Mr. Johnny Cosgrove of the Texas Commission on
Environmental Quality (TCEQ) Dam Safety Program arrived at the Ken• County Road and
Bridge Office and met with Bill Williams and Leonard Odom, Kerr County Road Administrator.
Mr. John Jones of the TCEQ San Antonio Field Office met the inspection party at the dam.
The TCEQ is an equal opportunity/al8rmawa action employer. The agency does not allow dis<dmination an the basis of race, color, religion, national origin. sez, tlisabiliry, age, sexual
ientation, or veteran stews. In compliance wiN Ne Americans wiN Disabilities Att, this document my be requasletl in alternate formats by wmacting Ne TCEO et 517/239.0028, hx239-
B8, a 1-800-RELAV-TX (TDD), or by writing PO Box 13087, Austin, Texas, 78717-3087 AuNOdzation for use w reprotluction of any original matetlal wntainetl in Nis publiWtion, i.e., not
obtained by other sources, is beery grentetl. The Commission woultl apPreclate acknovdedgement.
BACKGROUND
Kerrville Lake Dam is a 20 foot high, concrete capped overflow structure which spans the
Guadalupe River between State Highway 173 and State Highway 27. The darn is currently
categorized as a small size, low hazard dam which impounds water for the authorized purpose of
recreation.
Previous inspections have noted seeping cracks and joints. In 1989, grout and hydraulic cement
were pumped into cavities located under the concrete cap.
Mr. Ray Buck of the Upper Guadalupe River Authority (UGRA) was contacted during the week
of October 9, 2006 about a leak on the downstream slab of the dam. UGRA then visited the site,
contacted TCEQ and forwazded photos of the leak to Bill Williams of Precinct 2 in Ken County.
Mr. Williams then visited the site and forwarded the photos to TCEQ. The photos showed a leak
on the downstream slab with a moderate dischazge. An inspection by TCEQ was then scheduled.
HYDROLOGIC /HYDRAULIC ANALYSES
In accordance with state rule 30 TAC 299.12 - 299.14 of the Texas Administrative Code, low
hazazd dams of this size are required to safely pass 25 percent of the probable maximum flood.
This dam was designed to safely pass overtopping flows and therefore is considered
hydraulically adequate.
CURRENT EVALUATION
Summary
This inspection was primarily concerned with the integrity of the concrete cap. A thorough
inspection of all aspects of the dam was not conducted. Based on this limited inspection, the
dam appeared to be in overall fair condition. The crest of the concrete cap was in fair condition
with cracks noted, some which were open. The upstream slab was not visible due to the
reservoir. The downstream slab had cracks, one lazge hole and several small holes, minor
seepage and some plant growth in cracks and seems. The leak reported the second week of
October, which was located approximately in the middle of the left section of the dam, was now
dry and was reported dry during the Kerr County inspection of the week prior to this inspection.
The downstream slab of the spillway was in poor condition with numerous cracks and at least 3
sizeable holes.
Concrete Cap of the Embankment
Portions of the concrete cap were sound tested (with a sledge hammer) for cavities under the cap.
Some "hollowness" was detected under the crest of the cap on the left end of the dam. No
indication of a hollow area was detected immediately azound the now dry leak noted above. The
pictures of the leak that were forwazded to this agency showed a moderate amount of water
dischazging from a contraction joint/crack. A fan shaped deposit of dried material was evident
on the slab beneath the leak. This material was examined but no conclusive determination was
Kem~i//e Lake Dam, TX 02457
Kerr County • Inspection Date 11/1/06 • by TCEQ Staff 2
made in identifying embankment fill in the deposit. It is probably safe to say that based on the
quantity of flow evident in the photographs and previous pictorial evidence of seeps and stains
on the slab in this location, a channel exists which periodically discharges water and presumably
some fill material.
The water line on the downstream slope appeared to be more uneven now than in previous
inspection photos.
The weep holes at the toe of the slab were located under water and it was not possible to
determine if they were operating as designed.
Spillway
The spillway is created by a 200-foot wide section of the cap that is 1-foot lower at the crest.
The downstream slab of the spillway was inspected by John Jones. He located three holes in the
lower fourth of the slab. A rendition of his sketches is attached. The three holes were located at
about the same elevation and were possibly connected by a horizontal crack. The easternmost
hole, see sketch sheet and photo 13, an opening of approximately 5 squaze feet, had water
entering but not exiting, indicating the possibility of a substantial loss of embankment fill from
beneath the slab. The spillway had 0.2-foot of flow and it was not possible to perform a
thorough inspection of the downstream slab.
The low-flow outlet mechanical control is no longer operable; the gate was removed in 1988.
Control of the outlet is now maintained with a propane canister which has been inserted in the
inlet.
REVIEW OF DOWNSTREAM HAZARD CLASSIFICATION
A downstream inspection was not performed.
RECOMMENDATIONS
There aze two modes of failure that are directly related to the integrity of the concrete cap and the
underlying fill material, which current conditions indicate could be problems. First, loss of
material from under the cap in the main embankment can create cavities that weaken the
structure and increase the likelihood of a catastrophic failure during a major overtopping event.
The sound check indicating cavities under the crest, the apparently increasing unevenness of the
downstream slope waterline and the periodic seepage in the cracks on the downstream slab could
indicate the loss of fill material from beneath the concrete cap.
The second and more likely mode of failure for this structure would be a failure of the spillway
section due to loss of fill from under the spillway downstream slab.
It is recommended that an engineer with experience in dam design and repair be retained and the
status of the embankrent fill and the integrity of the concrete cap be determined. If it is
Keirvl//e Lake Oam, TX 02457
Kerr County • Inspection Date 11/1/06 • by TCEQ Staff 3
determined that the integrity of the cap is not compromised, it is recommended that, after
backfilling all cavities, the holes and open cracks in the concrete cap should be cleaned, plant
growth removed, the holes patched and a sealant applied. It may be necessary to repair the
reinforcement in the lazger holes.
2 ~ ~J-
Bob Wucher, P.E.
Dam Safety Program
rcQl%e; P.E.
Program
Kem~i//e Lake Dam, TX 02457
Kerr County • Inspection Date 11/1/06 • by TCEQ Staff 4
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Photo I : An overview of the dam from the left (east) end of the dam.
Keirvi//e Lake Dam, TX 02457
Kerr County • Inspection Date 11!1106 • by TCEQ Staff tj
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Kerrvi//e Lake Dam, TX 02457
Kerr County • Inspection Date 11/1/06 • by TCEQ Staff s
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Photo 6:	This spot of missing concrete was on the downstream slab.
Kerrvi//e Lake Dam, TX 02457
Kerr County • Inspection Date 11/1/06 • by TCEQ Staff 7
et.
Kerrvi//e Lake Dam, TX 02457
Kerr County • Inspection Date 11/1/06 • by TCEQ Staff $
Yhoto 8: The low-flow outlet. Indicated at bottom is a weep hole.
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Photo ] 0: Open cracks and a hole located on the crest.
Kerrvi//e Lake Dam, TX 02457
Kerr County • Inspection Date 11/1/06 • by TCEQ Staff J
Photo 11: This crack, which descends into
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Kem~i//e Lake Dam, TX 02457
Kerr County • Inspection Date 1111/06 • by TCEQ Staff ~ ~
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Photo 16: The downstream abutment at the left end of the dam.
Kerrvi//e Lake Dam, TX 02457
Kerr County • Inspection Date 11/1/06 • by TCEQ Staff 12
TX 02457 NOVIINBER 1, 2006
KERRVILLE LAKE DAM CO[JN'TY OF KERB
SKETCHES OF HOLES ON SPILLWAY DOWNSTREAM SLOPE
5
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WEST HOLE

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THIS HOLE
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EAST HOLE
Kerrvi/le Lake Dam, TX 02457
Kerr County • Inspection Date 1'1/'1/06 • by TCEQ Staff
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County of Kerr
November 1, 2006
Kerrville Lake Dam County of Kerr
TX 02457 November 1,1006
Dam Engineers experienced in dam design, construction, and repair
Dorian French Dee Purkeypile
Brown & Gay Engineers RJ Brandes Company
Houston Austin
(713)488-8140 (512)343-1070
dfrench(a~browngay.com dpurkewilena ribco.com
Joe Harle Michael Reedy
East Texas Engineers Turner, Collie & Braden, Inc.
Longview Houston
(903) 663-4509 (713) 267-3127
inharle ,cablelvnx.com mike.reedv~?.tab.aecom.com
Scott Hibbs Rich Shoemaker
Enprotec/Hibbs & Todd HDR Engineering, Inc.
Abilene Austin
(325) 698-5560 (512) 912-5157
Abilene e,e-ht.com rshoemak(c-r~,hdrinc.com
Jeff Irvin	Melinda Silva
URS Corporation	Brown & Gay Engineers
Austin	Houston
(512)419-6523	(713)488-8140
jell irvinna,ursco .com	msilva ,browngav.com
Tom Mountz John King
Carter & Burgess Freese and Nichols, Inc.
Austin Austin
(512) 314-3100 (512) 451-7955
,~
m~~:tzt~i,a,;c-b.con: irk,a.frecsc.cuiu
Janis Murphy	Neal Velvin
Freese and Nichols, Inc.	Velvin & Weeks
Fort Worth	Athens
(817)735-7345	(903/675-3903
jcm(n~,freese.com	vwcena velvin-weeks.com
Gary Pettit (H&H specialist) Gerald Harris, Jr.
Nationwide Water Resources Gerald B. Harris, Jr. & Associates
Dallas Huntsville
(972)490-6977 936/291-1081
g_arvna nwrservices.com
Updated September 21, 2006'
Pierce L. Chandler, Jr., P.E.
1204 Bayshore
Rockwall, Texas 75087
972/771-1310
omc(a~airmail.net
Wes Birdwell, P. E.
Halff Associates, Inc.
1421 Wells Branch Parkway
Pflugerville, Texas 78660
512/913-2906
Wbirdwell(a,Austin.Halff.com
David C. Riddle, Ph.D., P. E.
Adams Consulting Engineers, Inc.
P. O. Box 131599
Tyler, Texas 75713
903/324-8400
david.riddlenn,adams-en ineering.com
Kenneth Tillman, P. E.
TRC Engineers
6136 Frisco Square Blvd.
Suite 375
Frisco, Texas 75034
972/712-6400
ktillman(a tresolutions.com
David Givler, P. E.
Givler Engineering, Inc.
2161 Northwest Military Highway
Suite 114
San Antonio, Texas 78213
210/342-3991 x204
ivler(a~givlerenaineering.com
UpdatedJu/y~24, 2006