Villages C P3&4-SY 961119;ULTANTS, ~NC.
Ms. Cheryl Turner
Bragg, Chumlea, McQuality, Smithers & Curry
3102 Maple Avenue
Suite 330
Dallas, Texas 75201
Re: Lakes of Coppell
Slope Stability and Erosion Control
Plan of Repair
973 to 985 Parker Drive
Coppell, Texas
November 19, 1996
Dear Ms. Turner:
I have completed the majority of the geotechnical and structural analyses for
the repair of the slope at the above referenced site. These
recommendations and repair concepts have been provided to Mr. Craig
Olden with Craig Olden, Inc. to prepare an initial budget estimate. This
document and the attached sections and detail are released for the purpose
of interim review and are subject to change upon final review of permitting
issues and refinement with new geotechnical information. The attached
drawings are not to be used for construction, permit or final bidding
purposes.
Please find enclosed the following drawings and figures:
1. Site Plan showing location of wall and erosion control system
2. Sections 1 through 7 and A showing profiles of the retaining wall and
erosion control systems.
3. Typical section detail showing specific concepts of construction.
4. The boring logs performed for this investigation.
The final design will require some additional information concerning
specifications and details typically at transiions between sections. Thd
additional information will simply refine the design and may provide a less
expensive repair with the cost savings passed on to the responsible parties.
A final bid will be prepared based upon the final testing, design and review
information at a later date.
PEC Project DF96-041.POR2.L
Page2
November 19, 1996
PROPOSED CONCEPTUAL PLAN OF REPAIR
The following conceptual plan of repair for the slope is design to provide a
long term solution to the slope stability problem at this site. Other plans have
some of the required aspects. As a result, we have integrated these
features. However, we have also added some important features.
The proposed plan of repair was developed from the following:
1.PE Consultants (PEC) geotechnical and site investigations
2. Fugro-McClelland Geotechnical Engineering Study of June 6, 1996 as
well as, detailed telephone conversations with Mr. Gary Gregory, P.E. of
Fugro-McClelland.
3. The Reed Engineering Group Geotechnical Investigation of October
31,1995.
4. Conversations and meetings with Mr. Craig Loftin with the US Army
Corps of Engineers in Fort Worth, Texas concerning permitting for
construction with the water ways and brief discussions concerning flow
velocities in Denton Creek.
5. Conversations with Mr. Bill Stroman, P.E., a local geotechnical engineer
with over 30 years of earth structure retaining wall design experience.
6. Conversations with Mr. Craig Olden, the proposed contractor most
familiar with the conditions at this site.
7. Conversations with Mr. Mike Martin, a civil engineer with the City of
Coppell concerning permitting issues.
8. Review of the various suggestions and plans of repair at the slope
including R-Rap gravity bag wall, drilled shaft and concrete wall, gabion
systems and composite gabion/drilled shaft systems.
9. Conversations, meetings and design studies with Mr. Paul Brown, P.E., a
structural engineer concerning preliminary design of the beam, tie-back and
drilled shaft system.
10. Conversations and ideas developed during the August 26, 1996
technical experts meeting at the offices of Hunt & Joiner.
11. Conversations, meetings and design studies with Dr. Max Spindler, p.E
concerning the erosion control system and stability issues.
PEC Project DF96-U41,POR2.L
Page3
November 19, 1996
12. Approximately seven additional site visits to confirm the site conditions
and take water elevations.
The PEC conceptual plan of repair for this slope consists of a composite
gabion and drilled shaft system with passive tie backs positioned about 8
feet on center along the entire wall length and sloped at an angle of 30
degrees from horizontal founded into the gray shale below about EL 426 to
425. At present, the wall is approximately 265 feet long extending
approximately 20 feet to the south of 973 Parker and terminating on the
drainage channel around the promontory behind 985 Parker Drive. The
drilled shafts will be spaced at 8 feet on center along the slope at
corresponding locations of the tiebacks.
Based upon our technical experts meeting on August 26, 1996 the
consensus of the group was to provide an erosion control system at the base
of the wall to prevent excessive erosion and loss of the materials behind the
slope and to provide local slope stability and stability against sliding, while
eliminating the tangent shaft piers which would serve the same purpose.
The 3' by 6' wall gabion baskets will be stair stepped on an approximate 45
degree angle back to EL 443. Above the wall, an erosion control system
consisting of an 18 inch gabion mattress anchored with a 3' by 3' gabion
basket will be located at the top of the slope. The lower 3' by 6' gabion
basket will be attached to a 3' by 3' reinforced concrete beam that will run
continuously along the slope. The beam will be structurally connected to the
tangent drilled shafts.
The plan of repair presented by PE Consultants consists of a series of 18
inch diameter continuously reinforced drilled shafts penetrating at least 4
shaft diameters into the unweathered dark gray Eagle Ford shale located
below approximately elevation 426. These straight-sided drilled shafts will
be drilled near tangent and placed approximately 60 to 80 feet from the back
of the residences and conforming approximately existing with the contours
and creek bank geometry. These drilled shafts will act as a foundation
system which coupled with the erosion control system in front of the wall to
prevent scour will control the erosion and slope stability problems along this
reach of Denton Creek. Further, the drilled shafts act as a better system to
connect the concrete reaction beam and the tiebacks together.
The stability of the slope must be maintained for the life of the structures.
According to HUD this could mean 30 to 60 years. The global and local
stability of the slope must be satisfied, as well as, the prevention of possible
mechanisms that could potentially produce failures of the system throughout
this time period. In general, the presence of the slope failure on the creek,
and in particular at the cut bank, as well as the lack of long-term water and
flow information in the creek requires a more redundant system to account
for erosion at the base of the wall and to provide an overall global stability to
the slope.
PEC Project DF96-041.POR2.L
Page4
November 19, 1996
LIMITATIONS
This document is released for the purpose of interim review under the
authority of John T. Bryant, P.E. Texas No. 80163 on November 19, 1996.
The drawings, sketches and plans in this document shall not be used for
construction, permitting or final bidding purposes unless authorized by PE
Consultants in writing. Any final design drawings or construction
implementation will be subject to review by PE Consultants and John T.
Bryant, P.E.
Some of the observations, discussions and conclusions in this report are
based on information provided by others. The observed conditions are
subject to change with the passage of time. This investigation was
performed by PE Consultants and the engineer in a manner consistent with
that level of care and skill ordinarily exercised by members of the profession
currently practicing in the same locality under similar conditions. No other
representation, expressed or implied, and no warranty or guarantee is
intended for the opinions or observations represented in this report.
Conceptual recommendations of repair provided in this report are not
intended to act as express or implied warranties or guarantees of future
performance. Actual implementation of these recommendations should be
coordinated by the geotechnical engineer, the structural engineer and the
owner. This report should not be used as a construction specification.
Unless otherwise indicated, this report was prepared exclusively for Bragg,
Chumlea, McQuality, Smithers & Curry and expressly for purposes indicated
by the Bragg, Chumlea, McQuality, Smithers & Curry. Permission for use by
any other persons for any purpose, or by Bragg, Chumlea, McQuality,
Smithers & Curry for a different purpose must be provided by PE
Consultants in writing.
PEC Project DF96-u41,POR2.L
Page5
November 19, 1996
CLOSURE
Craig Olden indicated that the bid price for the proposed plan of repair will
be ready eminently, I will call you with the cost as soon as I receive it from
Craig, I trust this provides you with the required information at this time.
Please call me at home with any questions over the weekend (214) 343-
4220.
Sincerely,
PE CONSULTANTS/DALLAS
John T. Bryant, Ph.D., P.G., P.E.
Principal
cc: Mr. Craig Olden
LOG OF BORING B-1 Page I of
Project: Lakes of Coppell Location: See Figure 1,
Client: Bragg, Chumlea, McQuality, Smithers & Curry Coppell, Texas
Date Drilled: 8/1/96 Casing To: N/A Ground Elevation: Existing Grade
'~ Drilling Method: Continuous Flight Augerv=~'~'
Subsurface Water Observations ~
~ o ~ ~ E o
~ ~ ~ Groundwater encountered ~ 12 feet. o
J~Material/Stratum Description ~
~ Loose Yellowish Brown and Dark Brown C~YEY 1210~ 39 722 4.41 4.5.
~ ~ SILT with silty sand and clay laminations
]~4 3.0 5
~ Hard Yellowish Brown and Dark Brown CLAY
with silty sand laminations 5 1 27 51235 4.57 3.5
13 4.5~ 4.5*
.9.09.0
I ~ Sof~ Stiff Dar~rown and Gray C~Y with 18 49 93~ 4.46 4.0
I
organic
silt
~ 2810( 3.84 0.25
I
; 15.0
~ G~H~kfiY Gk~Y with silty ~and laminations
) (Highly Weathered Shale)
1
~'/~00
'Standard ~netration l~st ~ote~:
"Modifiod Gono ~onotration lo~t ~C°n~ult~nt~
LOG OF BORING B-2 Page I of 1
Project: Lakes of Coppell Location: See Figure 1,
Client: Bragg, Chumlea, McQua~ity, Smithers & Curry Coppell, Texas
Date Drilled: 8/1/96 Casing To: N/A Ground Elevation: Existing Grade
Drilling Method: Continuous Flight Auger ~ ~ >
Subsurface Water Observations ~ .cc - x co o .~ -~ ~ E
I
Groundwater encountered ~ 7 feet. Water ~
~ ~ level ~ 13 feet after 1 hour. --
Material/Stratum Description __--
Ve~ Stiff Dark Brown and Yellowish Brown CLAY 26 4.27 2.7~
with sand and occasional gravel (FILL) 2.0 29 94 4.1C 3.0
Hard Yellowish Brown and Dark Brown SIL~
C~Y with silty sand laminations and layers of 14 38 16 22 75 3.87 4.0
gray clay
6.0 25 4.0C 3.5
Loose Yellowish Brown SIL~ SAND
6 8.0
-10~ Dark Brown and Gray C~Y with organic silt 34 91 59 22 37 3.9~ 0.5
11.0
__~;.'~ ~ Medium Dense Yellowish Brown SAND with
g, ve
~ .... 14.0
~['~:J I Gray SHALEY C~Y with sil~ sand laminations
*~0 ~~~~ * 6 /100
IIIBoHng Scheduled to and Terminated ~ 25 Feet
-30 ' '
*Standard Penetration Test Notes:
**Modified Cone Penetrration Test PEC0nsultants
~ ~Figure 3
LOG OF BORING B-3 Page I of
Project: Lakes of Coppell Location: See Figure 1,
Client: Bragg, Chumlea, McQuality, Smithers & Curry Coppell, Texas
Date Drilled: 8/14/96 Casing To: N/A Ground Elevation: Existing Grade
Drilling Method: Continuous Flight Auger
Subsurface Water Observations ~ ~ ~ x '~ o o
~ ~' No water encountered. Boring remained dry
~_ ~ and uncaved.
c3 Material/Stratum Description ~ _~ ~' E. ~- ~. ~- z ~- ~ u~ u.
Yellowish Brown CLAY with occasional gravel 6
(FILL) 2.£
~ I Yellowish Brown and Dark Brown SILTY CLAY 2~ 38 17 21
(FILL) 4.c
._~J Yellowish Brown and Medium Brown CLAY with
-$ occasional gravel (FILL) 6.C 2~ 70 -)~ 4.~
"='ii I YellowiShlayers of ctayeyBr°wn CLAYEYsand SAND with silt and
1 ~ 31
I
Boring Terminated @ 10 Feet
-30
Notee:
PE Consultants
~ ~ Figure 4
Project: Lakes of Coppell LOG OF BORING B-4 Page 1 of 1
Location: See Figure 1,
Client: Bragg, Chumlea, McQuality, Smithers & Curry Coppell, Texas
Date Drilled: 8/1/96 Caalng To: N/A Ground Elevation: Existing Grade
Drilling Method: Continuous Flight Auger o~' ~' ~ -~' ~' ~' '~
: GrounOwator oncountorod ~ 27 [~ot. o ~ ~ .- ~ ~ ~ ~ ~ ° ~ .~
~ Material/Stratum Description = ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~ ~ ~ I Hard Dark Brown and Yellowish Brown CLAY ~ -- 4.4z 4.5+ --
--~ ~ ~ withsandandoccasionalgravel 17 : 4.5; 4.5
· ~ I, 8 Loose to Medium Dense Yellowish Brown and
'5- ~ ~ ~' Dark Brow~ G~Y[Y SlkT with sil~ sand
~ 8.0
~ ~4.0
15. ~ · I Vo~ Stiff Yellowish Brown and Olive Gray C~Y 35 ~ 4.3: ~
~ ~ ~th sil~ sand laminations
~.~.~Y CLAY with silty sand ~ 4.5z 4.5+
~0~:~:~ laminations (Highly Weathered sh~le~
· '5"/1 00
., '5.5"/1 00
Boring Scheduled to and Terminated ~ 30 Feet Notes: 14 - 15' CD Direct Shear: e = 26.5~
· Standard Penetration Test PE Consultants c = 288 psf
· *Modified Cone Penerometer Test ~
~ ~Flgure 5
LOG OF BORING B-5 Page I of
Project: Lakes of Coppell Location: See Figure 1,
Client: Bragg, Chumlea, McQuality, Smithers & Curry Coppell, Texas
Date Drilled: 8/2/96 Casing To: N/A Ground Elevation: Existing Grade
Drilling Method: Continuous Flight Auger~'~ ~ ~.~. ~ .~
o
Subsurface Water Observations~ ~ ~ g o ~ ~ E ~ ~ c
Groundwater encountered ~ 14feet. Water ~~'~ ~.~ ~ ~ ~ ~' -- m -~ ~ ~ '~
level ~ 17 ~eot aftor 1 hour. . .- 2 D ~ ~ m = ~ ~ ~
Material/Stratum Description ~ ~E E ~ ~ ~° m~ ~° ~c~= ~
Hard Yellowish Brown and Dark Brown SANDY 1 4.7: 4.5+
CLAY with silty sand laminations and roots and
interbedded with layers of brown silty clay and
brown clay 0 48 92861 4.71 4.5+
3 IC 4.634.5+
3 56 2234 4.66
11.0
~'~]'~] *48°fDenSedecayedYellowiShvegetationBrOwn SIL~ SAND with traces
45
24.( ~
Hard Gray SHALEY CLAY with silty sand 20 4.51 4.5+
laminations (Highly Weathered Shale)
'8"/100
*Standard Penetration Test Notes: 4 - 5' CU Triaxial: e = 31.9~
**Modified Cone Penetration Test PEConsultants c = 1022 psf
LOG OF BORING B-5 (Cont'd) Page 2 of 2
Project: Lakes of Coppell Location: See Figure 1,
Client: Bragg, Chumlea, McQuality, Smithers & Curry Coppell, Texas
Date Drilled: 8/2/96 Casing To: N/A Ground Elevation: Existing Grade
Drilling Method: Continuous Flight Auger ~ ~!~- ~ >~
E Subsurface Water Observations '~ ~ _ o~ ~ => c ~
~ _ ° ~' ~ E
~ Groundwater encountered ~ 14 feet. Water ~ ~ ~ -~ = ~ ~ =~ ~ '-
~ level ~ 17 feet after 1 hour. ~ ~,
~ m ~ Material/Stratum Description ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~m ~
.2.. Hard Gray SHALEY CLAY with silty sand
· ~.. laminations (Highly Weathered Shale)
0o
Boring Terminated ~ 33 Feet
'3 5'
'4 0'
'4 5'
-50-
~5-
~0
· *Modified Cone Penetration Test Notes:
PEC0nsultants
~ ~Flgure 6A
LOG OF BORING B-6 Page 1 of 2
Project: Lakes of Coppell Location: See Figure 1,
Client: Bragg, Chumlea, McQuality, Smithers & Curry Coppell, Texas
Date Drilled: 8/2/96 Casing To: N/A Ground Elevation: Existing Grade
Drilling Method: Continuous Flight Auger
Subsurface Water Observations
~1Groundwater encountered @ 20 feet. Water
, TI level @ 22 feet after 1 hour.
~.. 21~ 4.5
CLAY with sand and some gravel (FILL) . 2.0 17 94 ~.5E 4.0
~ D~ Orange SANDY CLAY with 3.0'~ I 33 15 1[ ¢.4~c 4.0
sand laminations . ..
~ H~d Yellowish Brown CLAY
I with sand and some gravel 16 4.7~ 4.5+
~,7~ 53213; 4.6.'4.5+
9.(; 1,~ 115 4.5+ 2520( __
-4-inch decayed log ~ 10 font
~ y~wnSILTY SAND with clay' 6 36 4.5;
laminations 12.£
Orenge a ,a G ay SANDY
CLAY with occasional gravel and traces of
I I ¥ n vs. mYCLAYwith
[ ~ silty sand laminations
__ 20X~
t I H~LEY CLAY with s_i!ty.s~nd
1 I laminations (Highly Weathered Shele)
*Modified Cone Penetrometer Test Notes:
PE C0nsultsnts
LOG OF BORING B-6 (Cont'd) Page 2 of 2
Project: Lakes of Coppell Location: See Figure 1,
Client: Bragg, Chumlea, McQuality, Smithers & Curry Coppell, Texas
Date Drilled: 8/2/96 Casing To: N/A Ground Elevation: Existing Grade
Drilling Method: Continuous Flight Auger ~ >
E Subsurface Water Observations
c)- Groundwater encountered @ 14 feet. Water
~ o ~ level ~ 17 feet after I hour.
'-~
~ ~ o Material/Stratum Description
.c.. Hard Gray SHALEY CLAY with silty sand
..~.."2" ~ *6.5"/1001aminations (Highly Weathered Shale)
Boring Terminated ~ 32 Feet
'4 0-
-4 5'
-50-
-55~
~0
*Modified Cone Penetration Test Notes:
PE Consultants
~ ~ Figure 7A
LOG OF BORING B-7 Page I of 2
Project: Lakes of Coppell Location: See Figure 1,
Client: Bragg, Chumlea, McQuality, Smithers & Curry Coppell, Texas
Date Drilled: 8/1/96 Casing To: N/A Ground Elevation: Existing Grade
Drilling Method: Continuous Flight Auger
Subsurface Water Observations
~ Material/Stratum Description
Hard Dark Brown and Yellowish Brown SANDY 14 4.77 4.0
C~Y with sand and some gravel (FILL) 10 38 16 22 4.5C 4.5~
4.~ 1~ 118 ~.87 4.5+~
Vew Stiff to Hard Yellowish Orange MARL with
_~ many limestone fragments (FILL) I 8 4.4~ 4.0
Ve~ Stiff to Hard Dark Brown C~Y with silt, 14 4.3~;4.5+
occasional gravel, and traces of decayed
vegetation ~4 97 4.5+ 880[
Z5 97 74 27 4~ 4.3~ 4.25
1 ~ 4.5( 4.0
~5'
18.~
~;~;~ I Yellowish Brown SAND with clay and some
19.~
/
~ Vo~ Stiff Yollowish Brown and ~ray Gk~Y with
~ [ siltg ~and lamination~
...... 25.0
~5-~ I Gray SHALEY C~Y with bentonite 27.0
2~-~ ~ Gray SHALE with silty sand laminations
2-2-~ ~llO'NXCore
'~0
'Standard ~enotration Iesl
~on*ult~nt~
LOG OF SORtNG B-7 (Cont'd) Page 2 of 2
Project: Lakes of Coppell Location: See Figure 1,
Client: Bragg, Chumlea, McQuality, Smithers & Curry Coppell, Texas
Date Drilled: 8/1/96 Casing To: N/A Ground Elevation: Existing Grade
Drilling Method: Continuous Flight Auger
E Subsurface Water Observations '> ~e O ~ ~ c
Q ~ ~ Material/Stratum Description
~-' Gray SHALE with silty sand laminations
~. 10' NX Core 7~ 68
-3 5- 7~.
Boring Terminated ~ 38 Feet
-40-
'45
-50-
~5'
~0 Notes:
PE COnsultants
LOG OF BORING B-8 Page I of 2
Project: Lakes of Coppeil Location: See Figure 1,
Client: Bragg, Chumlea, McQuality, Smithers & Curry Coppell, Texas
Date Drilled: 8/1/96 Casing To: N/A Ground Elevation: Existing Grade
Drilling Method: Continuous Flight Auger
Subsurface Water Observations ~ o~ x ~o o o
~ Groundwater encountered @ 17 feet. Water (~ :2 p · .-
= level @ 17 feet after I hour.
c) Material/Stratum Description _:~ c~ __ L~ D_ E. ~- ~ ~- :c o. ~ 03 u_
Stiff Dark Brown and Yellowish Brown CLAY
with sand and rootlets (FILL) 2.£ f ~ 4.1<. 3.5
Stiff Gray to Grayish Black and Yellowish Brown
CLAY with many limestone fragments (FILL) 4.¢ 1~ 10§ 4.0; 1.0
Hard Yellowish Orange MARL with many
i limestone fragments (FILL) 6.¢ -~£ ~ 4.1; 4.0
Very Stiff Grayish Brown CLAY with silt and
traces of decayed vegetation (FILL) 8.(~_~3 52 21 31 ~4.4z 3.5
Stiff to Very Stiff Dark Brown CLAY with silt,
occasional gravel, and traces of decayed vegetatior
-1 -
25 59 22 3~ 4.1.~ .75
22 4.2; 2.5
-15'
18.0
~iL~ Medium Dense Yellowish Brown SAND with clay
* 1 7 20 0
and
some
gravel
'20 .~ I Very Stiff Yellowish Brown and Gray CLAY with
II silty sand laminations
'25 25.0
Z-----ti Gray SHALE with silty sand laminations
'30
· Standard Penetration Test Notes:
· *Modified Penetrometer Test PE Co'nsultants
~ ~Flgure 9
Project: Lakes of Coppell LOG OF BORING B-8 (Cont'd) Page 2 of 2
Location: See Figure 1,
Client: Bragg, Chumlea, McQuality, Smithers & Cur~ Coppell, Texas
Date Drilled: 8/1/96 Casing To: N/A Ground Elevation: Existing Grade
-5 Drilling Method: Continuous Flight Auger ~ --~'o o~ ~_~°~ ~ =~' '~">
E Subsurface Water Observations E ~ ~ ~ ~ o
= ~ ~ Groundwater encountered ~ 17 feet. Water ~ .[ ~ _
~ o ~ Material/Stratum Description
7~ Gray SHALE with silty sand laminations
Bodn~ lorminalod ~ 35
'4 0-
'4 $
~0
"Modifiod Gono ~onotrafion Test
~ Oon~ult~nt~
~ rFigure gA
LEGEND OF BORING LOG SYMBOLS
SYMBOL
DESCRIPTION SYMBOL
CLAY (CH)
CLAY (CL)
SANDY CLAY (CL)
SILTY CLAY (CL)
SHALEY CLAY (CH)
CLAYEY SAND (CL)
CLAYEY SILT (CL-ML, MH) ·
SHELBY TUBE V
SAMPLE
STANDARD PEN~- I HATION
SAMPLE
DESCRIPTION
SAND (SW, SP)
SILT (ML-MH)
LIMESTONE
WEATHERED LIMESTONE
WEATHERED SHALE
MODIFIED TxDOT CONE
PENt i HOM~ i ~-R TEST
FIRST WATER ENCOUNTERED
STATIC WATER LEVEL
SOIL CONSISTENCIES
CLAYS
Consistency
Very Soft
Medium
Stiff
Very Stiff
Hard
Penetrometer
Value (t~f)
< 0.25
0.5 - 1,0
1.0 - 2.0
2.0 - 4.0
> 4.0
SANDS
Number of Blows
per Foot
0-4
4 - 10
10 - 30
30 - 50
> 50
Relative
Density
Very Loose
Loose
Medium
Dense
Very Dense
PE Consultants
Figure 1 0
NOTES
PE
CONSULTANTS
o -~, ~o
/
0 0 0 0 0 0 0
NOTES
NOTES
NOTES
0
NOTES
NOTES
NOTES
0
0 0 0 0 0 0 0 G
NOTES
P E
CONSULTANTS