SS9301-SY 920619SUPPLEMENTAL SUBSURFACE EXPLORATION
FOR
GRAPEVINE SEWER TRUNK MAIN
PHASE I
COPPELL, TEXAS
Prepared For
Ginn and Case, Inc.
Dallas, Texas
June 19, 1992
Addendum No. 1 to
SWL Report No. 91-586
._ ..
M~e~, envi~nmen~ and geotechn~al enginee~ng, nondestruc~ve, metMiu~ic~ and analyticM se~ices
8~7~ Lone Star Orive · ~ O. Box 224287. OsIl~s, Texas 75222 · 214/631 -2700
June 19, 1992
Ginn and Case, Inc.
17103 Preston Road
Suite 100
Dallas, Texas 75248
... Attention: Mr. Gabe Favre
Re: Supplemental Subsurface Investigation
Grapevine Creek Sewer Trunk Main-Phase I
Coppell, Texas
Addendum No. 1 to SWL Report No. 91-586
- Dear Mr. Favre:
In accordance with your request, a supplemental
subsurface investigation has been performed for an
alternate route of a section of the proposed Grapevine
Creek Sewer Trunk Main. Seven Additional borings were
made along the Bethel Road Alignment. Laboratory testing
was performed to compare the subsurface conditions along
the alternate route of the proposed sewer main to
conditions encountered during our initial investigation.
The results of this supplemental investigation and a
comparison of conditions along .~the alternate route to the
original alignment are provided in the attached report.
It has been a pleasure to perform this work for you. If,
during the course of this project we can be of further
assistance, please do not hesitate to call on us.
Sincerely,
SOUTH~T~RN LABORATORy, INC.
Michael L. Lester, P.E.
Geotechnical Division
CBB: MLL: ams
Attachment
HOUSTON · DALLAS · AUSTIN · BEAUMONT · GALVESTON COUNTY · RIO GRANOE VALLEY · ALEXANDRIA
SAN ANTONIO · FORT WORTH · MIE~ND · MONROE · SHi~IEVEPORT · T~XARKANA · O~N~SON s BATON ROUGE
TABLE OF CONTENTS
Page
New Sewer Alignment ................................ 1
Field Operations ................................... 2
Laboratory Testing ................................. 4
Geology/Subsurface Conditions ...................... 5
Boring B1-9 .................................... 5
Borings B1-A thru B1-7A (Alternate Alignment) .. 6
Active Clays ................................... 8
Groundwater .................................... 9
Analysis and Recommendations
Allowable Bearing Pressures .................... 10
Construction Considerations-Footings ........... 13
Trench Excavations ............................. 14
Construction Considerations-Trench Excavations..21
Trench Backfill ................................ 23
Limitations and Reproductions ...................... 24
APPENDIX
Boring Location Diagram ........................ A-1
Log of Boring .................................. A-2
Grain Size Analysis ............................ A-Ii
ADDITIONAL SUBSURFACE EXPLORATION
GRAPEVINE CREEK SEWER TRUNK MAIN
PHASE I
COPPELL, TEXAS
NEW SEWER ALIGNMENT
The original alignment of the proposed 30 inch diameter
sewer main included a section along the Grapevine Creek
channel from Denton Tap Road (Sta. 129+00) at the western
end of the Phase I alignment, to about Sta. 91+00. At
about Sta. 91+00, the proposed sewer would leave the
natural creek channel and become parallel to an existing
sanitary sewer line within an existing sewer easement.
The planned alternate route being considered would
replace the section of the alignment located in the creek
bottom with a line running along Bethel Road which is
located south of the creek in this location. The line
would be installed in .the roadway right-of-way of Bethel
Road, beginning at Denton Tap Road and extending eastward
to the end of the road in the Creek View Addition.
The line would then turn northeast between lots 10 and 11
of Block B in this addition, and join an existing
sanitary sewer easement at the north end of these lots.
91-586 -1-
This portion of the alignment will be microtunneled to
avoid cut and cover excavations near the existing
residences. Once the alignment joins the existing
sanitary sewer easement, it will continue to the east
along the originally proposed alignment described in our
initial investigation (SwL Report No. 91-586).
FIELD OPERATIONS
A total of 7 additional borings were made to investigate
the alternate route of the proposed sewer along Bethel
Road. These borings were made in the right-of-way for
Bethel Road and spaced approximately 500 feet apart,
along this alignment. In addition to these borings,
Boring B1-9 was completed east of the sewer alignment's
crossing below Moore Road. This boring was made on an
_ unchanged portion of the alignment, and is included in
this report because it had 'not been completed at the time
of the original report was submitted.
Boring B1-9 was made at the site on April 17, 1992, and
it's location is indicated on Figure lB, Boring Location
Diagram. Borings Bi-lA through B1-7A were made during the
period May 12 to 15, 1992 at the approximate locations
shown on Figures lA and lB, Boring Location Diagrams.
Truck-mounted and all terrain vehicle (ATV) mounted auger
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drilling rigs were used to advance these borings and to
obtain samples for laboratory evaluation.
Undisturbed specimens of cohesive soils were obtained at
intermittent intervals with standard, thin-walled,
seamless Shelby tube samplers. These specimens were
extruded in the field, logged, sealed and packaged to
protect them from disturbance and maintain their in-situ
moisture content during transportation to our laboratory.
Where cohesionless or very stiff clay soils were
encountered, an indication of their engineering
properties was obtained by means of the Standard
Penetration Test. This test consists of determining the
number of blows required for a 140 pound hammer falling
30 inches to drive a standard split-spoon sampler 12
inches into the soil.
The consistency of the shales were evaluated during
drilling by the Texas Highway Department (THD) Cone
_ Penetrometer Test. This tests consists of determining
the penetration of a 3-inch diameter cone driven with an
approximate energy equivalent of a 170-pound hammer
falling 24 inches.
91-586 -3-
The results of the boring program are presented on the
attached Logs of Boring in the Appendix.
LABORATORY TESTING
Samples were examined at our laboratory by the project
geotechnical engineer. Selected samples were subjected
to laboratory tests under the supervision of this
engineer. The boring logs were edited by this engineer
to reflect visual examination of the samples and the
results of laboratory testing.
The in-situ unit weight and moisture content of the
samples were determined and used in conjunction with the
Atterberg Limits tests to evaluate the potential
volumetric change of the different strata, and as an
indication of the uniformity of the material.
Unconfined compression tests were performed on selected
undisturbed samples of the cohesive soils. These tests
were performed to evaluate the strength of these
materials.
The results of our testing program are presented on the
attached Logs of Boring. Based on the results of these
tests, the natural soils were classified using the
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Unified Soil Classification System (USCS) and these
classifications are indicated on the logs.
GEOLOGY/SUBSURFACE CONDITIONS
The subsurface conditions encountered in the borings are
presented on the Logs of Boring in the Appendix.
Detailed descriptions of the various strata and their
depths and thicknesses are given. A brief summary of the
stratigraphy and geology indicated by Boring B1-9 (Moore
Road) included on this addendum is given below. A
summary of the stratigraphy and geology indicated by
Borings Bi-iA through B1-7A follows the description for
Boring B1-9.
Boring B1-9
Subsurface conditions encountered in Boring B1-9 made
near the east side of Moore Road were consistent with
Boring Bi-10 located approximately 500 feet east of this
location. Existing fill soils were encountered at the
ground surface, typically consisting of grayish-brown
sandy clays with pieces of broken asphalt, becoming dark
brown and brown clay fills with depth. Based on visual
examination of the samples, these fills extended to a
depth of approximately 4.5 feet.
SOUTHWESTERN LABO~:~%TC:R ES
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Dark grayish brown silty to sandy clays were then
present, with tan and gray sandy clays and then shaly
clays present with depth. This soil profile is typical
of the alluvial deposits overlying the decomposed (shaly
clays) and weathered shales (clayey shales) of the Eagle
Ford formation.
Borings B1-A thru B1-7A (Alternate Aliqnment)
Concrete paving of Bethel Road was penetrated at the
ground surface in the borings made along Bethel Road.
This paving generally varied from 5.5 to 8 inches thick.
The subsurface conditions encountered along Bethel Road
were generally similar in the areas of Borings Bi-IA,
B1-5A, B1-6A, B1-7A, and between Borings B1-2A,and B1-3A.
Boring B1-4A indicated a deeper interval of sands and
gravel than encountered ak the other boring locations.
Conditions along this section of the alignment show some
variation between borings due to the close proximity of
Grapevine Creek, normal differences in the alluvial soils
deposited in this area, and cut/fill operations
associated with construction of Bethel Road.
In Borings Bi-iA, B1-5A, B1-6A and B1-7A, clay, sandy
clay and silty clay fill soils were present to depths of
3.5 to 6 feet. These fills generally were tan, brown and
91-586 -6-
gray in color. The surficial fill soils in Borings Bi-iA
and B1-5A were underlain by dark brown sandy clays
extending from 6 to 7 feet, where tan and gray or
reddish tan sandy clays were encountered and extended to
12 to 14 feet. Tan and gray clays were present below the
sandy clays in Boring BI-IA and B1-5A. These clays
extended to gray shale at a depth of 17 feet in Boring
Bi-lA to boring termination at a depth of 20 feet in
Boring B1-5A.
Tan clays with traces of silt and lime and gypsum
partings were present at a depth of 6 feet in Borings
B1-6A below the overlying fill. This tan clay extended
to gray weathered shale at a depth of 17 feet. The
boring was terminated in gray shale at a depth of 23
feet. Tan sandy clay with occasional gravel was
encountered below the fill at a depth of 5 feet in Boring
B1-7A. This sandy clay extended to a depth of 12.5 feet
where tan clay was encountered. This tan clay became
light grayish tan below a depth of 17 feet and extended
to dark gray weathered shale at a depth of 23 feet. The
boring was terminated in gray shale at a depth of 32
feet.
Borings B1-2A and B1-3A encountered shallow sandy clays
__ below the pavement, varying in color from brownish gray,
91-586 -7-
dark brown, tan and brown. The upper 2.5 and 7.5 feet of
these sandy clays appeared to be fill materials in
Borings B1-2A and B1-3A, respectively. In Boring B1-2A
these sandy clays become tan and gray with depth and
extend to tan sand at a depth of 17.5 feet with the
boring terminated in this sand at a depth of 20 feet.
Sands, silty sands and clayey sands and sand and gravel
mixtures were encountered in Boring B1-4A from the bottom
of the pavement to a depth of 9.5 feet where gray shale
was encountered. These sands vary in color from tan to
reddish tan. In Boring B1-3A a one foot interval of sand
and gravel was encountered below the fill. At a depth of
8 feet and was underlain by tan and gray shaly clay which
extended to gray shale at a depth of 13 feet. The boring
was terminated in this shale at a depth of 20 feet.
Active Clays
The Atterberg limits series tests indicate that the clay
soils encountered in the area of this site are highly
active. The sandy clays and silty clays are considered
moderately active. Active clays are subject to moisture
induced volume changes (expansion and contraction) with
fluctuations in their moisture content.
91-586 -8-
Groundwater
Seepage was encountered at a depth of 16 feet in Boring
B1-9 during drilling and sampling. Water was measured at
a depth of 10 feet 1.5 hours after completion.
Seepage was encountered at depths of 8 to 17.5 feet
during the advancement of most of the borings made along
the alternate (Bethel Road) alignment; Borings B1-2A,
B1-3A, B1-4A, B1-6A, and B1-7A. The remaining borings
(Borings BI-iA and B1-5A) were dry at completion.
Groundwater observations after completion at individual
boring locations are indicated on the Logs of Boring in
the Appendix.
Seepage observations and water level readings generally
indicated water is present in the alluvial soils where
these soils overlie shale or shaly clay, or in the sandy
soils where they extend down to relatively deep
elevations. Seepage is typically present above the
shales and residual shaly clays of the Eagle Ford
Formation. Water can also be present at various depths
in existing fill materials.
Water levels will tend to fluctuate due to seasonal
variations in rainfall. Water seepage will most likely
be encountered in the sandy alluvial soils. The
91-586 -9-
possibility of encountering seepage increases in
locations closer to the creek.
ANALYSIS AND RECOMMENDATION
Allowable Bearing Pressures
Subsurface conditions along the proposed new alignment
will vary with location. The typical profile of shale
overlain by residual clay soils and shallow sandy
alluvial soils will vary. This is primarily due to
creek's previous alignment that eroded away some of these
soils and shales and replaced them with alluvial
deposits, and to cut/fill operations associated with
grading and construction of Bethel Road. The alluvial
deposits are predominately sandy soils, including sands,
silty sands, clayey sands and sandy clays and the fills
generally consisted of sandy clays, silty clays and
clayey sands.
Although excavations for structures such as manholes are
likely to extend through the surficial fills, excavations
near the existing culverts and buried utilities may
encounter fills at the bearing depth of these
structures. It is important that all footing excavations
be extended through these fill materials and bear at
least 12 inches into the natural soils or on the
unweathered gray shale.
91-586 -10-
Based on profile drawings of the improvements recently
made to Bethel Road, creek channels were located near
Stas. 5+00, 15+70, and Sta. 24+40 at depths extending to
14 to 17 feet below the finished elevation of Bethel
Road. These creek~ were routed through concrete box
culverts or drain lines to cross Bethel Road and
backfilled to establish finished grades for the roadway.
We anticipate that the soils in the vicinity of these
creek channels will be predominately the sandy alluvial
soils along the creek banks and be fill soils in the
creek channel.
With the exception of these creek channel areas,
excavations for the sewer line in the proposed new
alignment section will extend into clays or the
underlying shale or weathered shale strata. Shales were
encountered in Borings No. Bi-iA, B1-3A, B1-4A, B1-6A and
B1-7A at depths as shallow as 9.5 feet in Boring B1-4A,
and were as deep as 25 feet in Boring B1-7A. Shales were
not encountered in Boring B1-2A made near the old creek
- channel around Sta. 5+00, and in Boring B1-5A, although
the presence of shaly clays near the bottom of Boring
B1-5A indicates this depth approaches of the underlying
shales.
91-586 -11-
In summary, we anticipate that sandy soils will be
encountered near the base of manhole structures in the
vicinity of the old creeks (existing culverts and creek
diversion lines) near Sta. 5+00 and Sta. 15+70 (in the
areas of Borings B1-2A, B1-3A and B1-4A) and possibly in
the vicinity of the old creek at Sta. 24+40. These soils
could be wet and soft. The bottom of pipe and structure
excavations in these areas may need to be stabilized with
crushed stone to establish a working platform. Where
water is encountered, dewatering techniques may be
necessary to establish a firm subgrade. A maximum
allowable bearing pressure of 1,500 pounds per square
foot is recommended in these soils for footings or mat
type foundations. If the excavations expose the
underlying shales, a maximum allowable bearing pressure
of 5,000 pounds per square foot is recommended in these
shales. The above bearing pressures contain a factor of
safety of at least 3 against a general shear failure.
In the remaining areas uncut by creeks, manholes will
most likely bear in shale where they exceed depths of 15
to 17 feet. An allowable bearing pressure of 5,000
pounds per square foot is recommended in these shales,
provided that the footing support is based a minimum of 1
foot penetration into the shale stratum. Manholes in
some areas may not extend deep enough to bear in the
SOUTHWESTERN L&BORATORIE5
91-586 -12-
shales and would most likely bear in the overlying clays,
shaly clays or weathered, clayey shales. We recommend a
maximum allowable bearing pressure of 3,000 pounds per
square foot be used for any structures supported on the
clays, shaly clays or weathered shales. These bearing
pressures contain a factor of safety of at least 3
against a general shear failure.
As previously indicated, the conditions encountered in
Boring B1-9 were similar to conditions in the adjacent
Boring Bi-10. Bearing strata and the recommended maximum
allowable bearing pressure for any structures in the area
around Boring B1-9 are the same as discussed in our
original report for this section of the alignment.
Construction Considerations-Footings
Excavation of the footings, placement of concrete and
steel, and any required backfilling should proceed in as
continuous a manner as practical. This will serve to
minimize deterioration of the bearing surfaces. Footing
excavations should be maintained at/or near their in-situ
moisture levels prior to concrete placement. Any bearing
surface subjected to ponding of water should be dewatered
as quickly as possible and soft, wet soils should be
excavated to a firm subgrade immediately prior to
concrete placement. If bearing soils are allowed to
91-586 -13-
become dry, post-construction movement of footings can
occur due to volume changes in the active clays. Footing
excavations which will remain open for more than 48 hours
should be protected by a 3 to 4 inch thick seal (mud)
slab of footing strength concrete.
Individual footings or structure bottoms may be square,
round, or rectangular and should maintain a minimum width
of 3 feet. Concrete should be placed directly against
the sides of footing or mat excavations with no loose or
pervious backfill placed below the level of the general
excavation and around the structure.
Trench Excavations
Excavations along the proposed alignment will encounter a
variety of conditions due to the alluvial deposits
associated with the creek and the fill deposits installed
to grade Bethel Road. Existing fill soils primarily
consisting of silty to sandy clays and clayey sands are
anticipated at the ground surface in most areas,
- typically varying in thickness from 2.5 to 7.5 feet.
Clays, sandy clays and silty clays overlying a deeper
shale strata will typically be the natural soils and rock
underlying these fills along most of the proposed new
alignment. Some sections of the alignment will be
predominately sandy clays, clayey sands, silty sands, and
91-586 -14-
sand and gravel mixtures, and these will most likely
occur in the vicinity of the old creek channels.
Based on the construction plans for Bethel Road,
excavations for the sewer line should encounter shallow
fills (up to 5 feet) along most of the new alignment,
with deeper fills present in the vicinity of each old
creek crossing (Sta. 5+00, 15+70 and 24+40) , and from
approximately Sta. 5+00 to 10+00, Sta. 20+00 to 24+40 and
Sta. 27+50 to 28+50. Construction plans for Bethel Road
indicate that the fills were compacted.
Shales were generally encountered at depths varying from
13 to 25 feet in the borings, but were as shallow as 9.5
feet in Boring B1-4A, and were not encountered in the 20
foot deep Borings B1-2A and B1-5A. Planned invert
elevations along most of the new alignment will be on the
order of 15 to 25 feet below the existing ground
surface. Based on the proposed invert elevation of the
sewer line, we estimate the underlying gray shale strata
will be at or above the sewer invert elevation from
approximately Sta. 92+00 to 99+90 and in the vicinity of
Borings BI-lA and B1-3A. In the deepest section of the
alignment near Boring B1-7A, shales were present at a
depth of 25 feet and the invert of the planned sewer is
more that 30 feet below the existing grade.
91-586 -15-
In general, most trench excavations will not exceed 20
feet along most of the new alignment, with the exception
of the section east of Sta. 99+90, where excavation
depths will be from 22 to 30 feet deep. In the areas of
the new alignment where excavations will be greater than
20 feet, shales and clayey shales were encountered at
depths of 17 to 23 feet. Trench safety parameters for
excavation depths of 20 feet or less were provided in our
original geotechnical report. These parameters would
apply in any areas where trenches are 20 feet deep or
less and can be sloped back as indicated. It is
anticipated that deeper excavations will require
temporary bracing or shoring due to the limited area
available to slope back the excavations and the presence
of existing pavement, structures and other underground
utilities which would be disturbed or removed by sloping
back the excavation.
As previously indicated, the proposed new alignment will
run in a northeasterly direction from the proposed
manhole at Sta. 95+45. This alignment will pass between
existing residences at 248 and 252 East Bethel Road. It
is our understanding the sewer line in this area will be
installed in a microtunnel through this section of the
alignment to avoid disturbing the foundations, pavements,
and landscaping of the existing residences.
91-586 -16-
Based on the subsurface conditions encountered in Boring
B1-7A, shale was encountered at a depth of 25 feet. The
microtunnel crown will be approximately 28 feet below
_ grade, which is approximately one tunnel diameter below
the top of shale. We recommend that additional
subsurface investigations be made prior to construction
in the middle and at the northeastern end of the
microtunnel alignment, to determine the amount of shale
cover through the tunnel section. We also recommend that
the ground surface above the microtunnel be monitored
during construction. This monitoring is a means to
detect if tunnel excavations begin to undermine the
overburden soils. Tunneling should be discontinued if
movements approach levels that could cause structural
distress in the existing residences, walls, etc.
It is our understanding that all trenches or structure
excavation operations for the project will be short term
and therefore excavations will not remain open for more
than 1 or 2 days. The clays and clay fill materials are
subject to caving and must be sloped or braced in the
interest of safety. The gray shales contain fractures
and possible bentonite layers and should also be sloped
back or braced. Excavations in the firm unweathered gray
shale can be cut on near vertical slopes for short
periods; however, due to the presence of possible joints,
91-586 -17-
bentonite seams and old fault planes, they should be
shielded or very carefully monitored by qualified
personnel to identify areas which could require
additional support or bracing.
- Along a significant portion of the alignment, it is
anticipated that groundwater will be encountered. Based
on the results of the boring program, this ground water
appears most likely in the old creek channels and deeper
sandy soils (including areas around Borings B1-2A, B1-3A
.... and B1-4A) and above the shales at the eastern end of the
alignment (near Borings B1-6A and B1-7A). The quantity
of ground water will also be influenced by seasonal
conditions. During periods of seasonal rain, greater
quantities of groundwater should be expected. Seepage
could also occur in joints and fissures in the clay
rocks.
Seepage in the clays and above the shales can often be
controlled by pumping any water accumulation from low
points along the trench bottom. Seepage in the sandy
alluvial soils is expected to be more significant and
dewatering techniques such as well points could be
required, particularly if construction proceeds during a
wet period of the year. Excavation slopes of 1.5
horizontal to 1 vertical or flatter will be required if
91-586 -18-
water levels are not lowered below the bottom of the
trench excavation.
Care must be taken when excavating near and below any
existing utility trenches. The backfill materials for
these lines may be loose and saturated. Careful
observations will be required to determine if changes in
the side slopes or temporary bracing are necessary.
Where gravel backfill materials are encountered,
sloughing and caving of these materials will require that
they be sloped flatter than indicated or that continuous
shoring is used.
An earth pressure envelope for temporary shoring for
trench excavations is presented on Figure 2 of the
original report. This diagram is considered applicable
for the planned excavations along the proposed new
alignment. As previously indicated, temporary surcharge
loads (due to traffic, equipment, spoil material, etc.)
must be considered when they are located closer than
one-half the depth of the excavation. A minimum
surcharge equivalent of two feet of soil is recommended.
Therefore, the depth to the bottom of the excavation or
the depth to unweathered shale should be increased by two
feet or more to account for this surcharge. For
calculation of surcharge loads, use of a soil unit weight
91-586 -19-
of 125 pounds per cubic foot is recommended. Design of
trench shoring or bracing systems should be submitted to
the city of Coppell for approval prior to beginning
construction.
Excavations made in close vicinity to any existing
structures or pavement will require use of retention
systems to prevent excavation limits from encroaching on
these structures or reducing the amount of pavement
removed. Design of the retention systems must consider
surcharge loads imposed by the structures or pavements.
It should be recognized that some movement of the ground
behind the retention system will occur. The extent of
movement and any resulting damage is highly dependent on
the workmanship and procedures used in constructing and
removing the retention system. Existing structures with
foundations bearing within a 1 horizontal to 1 vertical
slope from the base of the proposed excavation must be
considered in the design of shoring systems.
Underpinning of the portions of the existing structures
next to excavations could be considered to reduce
potential for movement of these structures during and
after the construction. The type of existing foundation
system supporting these structures should be determined
to evaluate the need for underpinning. Monitoring of the
ground surface, adjacent to the braced trench excavations
91-586 -20-
for ground movement should be performed while the trench
excavations are open; particularly in the area of
structures sensitive to ground movement.
Construction Considerations-Trench Excavations
In the event a trench box is utilized, the manufacturer
of the box should certify that the trench box will resist
an active earth pressure of 85 pounds per square foot per
foot of depth. The capacity of the trench box should be
based on the depths of the excavation plus any surcharge
loads. It is emphasized that use of a trench box could
allow surface movement to occur if the trench walls
slough or cave.
SwL also emphasizes the importance of continuous
observations by qualified geotechnical personnel during
trenching or excavation operations at the site. These
observations are required to verify that the conditions
encountered are as anticipated, that side slopes are as
recommended, or that shoring is as specified. The
relatively rapid excavation and cover process associated
with pipe installations will require that these personnel
be capable of making on site decisions regarding changes
in the side slopes or shoring or that work in a given
area should be halted until additional investigations and
analyses can be performed.
91-586 -21-
Pressure diagrams and slope configurations represent
recommended design approaches consistent with generally
accepted practice. Proper monitoring during construction
must be provided to verify the subsurface conditions and
confirm that these recommendations are applicable. Any
changes in subsurface conditions must be evaluated to
determine if adjustments are necessary in shoring or
slope configurations.
The contractor is solely responsible for designing and
constructing stable, temporary excavations and should
shore, slope, or bench the sides of the excavations as
required to maintain stability of both the excavation
sides and bottom. The contractor should submit a trench
shoring plan to the city prepared by a Registered
Professional Engineer experienced in the design of trench
shoring systems. The contractor's engineer should submit
sufficient experience history to indicate qualifications
to design these systems. All excavations should comply
with applicable local, state and federal safety
regulations including the current OSHA Excavation and
Trench Safety Standards. The contractor is responsible
for construction site safety through the means, methods
and sequencing of construction activities.
$OUTHWEST£~N LABORATOR,E$
91-586 -22-
Trench Backfill
We recommend that utility trenches be backfilled in lifts
with density controlled compaction to prevent unusual
settlement. We do not recommend the use of jetting, even
if granular (sandy) backfill materials are used. Ail
trenches and excavations should comply with OSHA and
state law requirements for trench safety.
Where trenches are located in existing and/or proposed
paving and structure areas and trench backfill is made
with on-site swelling soils (PI >20), we recommend the
fill be placed in loose lifts less than 9 inches thick,
compacted between 93 percent and 98 percent of Standard
Proctor density (ASTM D 698) at optimum moisture to five
percent above the soil's optimum moisture content. Where
backfill will exceed 5 feet in depth, minimum compaction
of deeper backfill material should be increased to
between 95 and 100 percent. Properly compacted fill
sections up to 20 feet deep could settle on the order of
2 inches after construction.
Granular, generally non-active to slightly active, soils
(PI < 20) should be compacted to a minimum of 95 percent
of Standard Proctor density (ASTM D 698). Granular soils
should be placed in loose lifts 6 to 9 inches thick and
compacted from -2% to +3 percentage points above their
91-586 -23-
optimum moisture content. Use of very granular
free-draining soils (coarse sands, sand/gravel mixtures,
or gravel) which could trap and hold water in utility
trenches should be avoided in areas where the surrounding
soils are predominately clay materials.
LIMITATIONS AND REPRODUCTIONS
The foregoing recommendations are based on analyses of
the soils from each of the indicated borings with the
assumption of uniform variation in the soil properties
between borings.
Should any conditions at variance with this report be
encountered during construction, this office should be
notified immediately so further investigations can be
made and supplemental recommendations can be given.
The reproduction of this report, or any part thereof,
supplied to persons other than the owner, should indicate
that this study was made for foundation design and trench
safety purposes only and that verification of the
subsurface conditions for purposes of determining
difficulty of excavation, trafficability, etc., are
SO~JTH~ESTERN LABORATORIES
91-586 -24-
-- responsibilities of others. This report should not be
used as a construction specification but as a guide for
developing final foundation and excavation plans and
specifications.
Analysis performed by: Clement B. Bommarito, P.E.
91-586 -25-
APPENDIX
....... ~ ~ / ~o~os[.~
~ ~ - ~ / SEWERLINE-..._ ~ '~ I1~
'~ ~ / ALIGNMENT
~ v~lTi i ~.~V~''''~'~'°'''''''~'· ~' 6EWERLINE
.,. ~_L__~ ."L . ,/ x x _.__~.~_...~ /
._ o ,ch-BI- IA'"'"'-~'x -~,. ~1 ' ..,C~.// 'v __....-.-.~
~--.~__~ --. ~-~... -~.. ~, ...~:.~ ----~
BI-SA INCLUDED IN
ADDENDUM REPORT
I
I
I
NOTE: BORING LOCATIONS ARE APPROXIMATE
PROJECT /TITLE SITE LOCATION SHEET I OF 2
PROPOSED GRAPEVINE SEWER TRUNK MAIN COPPELL, TEXAS
BORING LOCATION DIAGRAM SWL 91 - 586 SCALE: 1" = 300' +/- DATE: 03/17/92 DRAWN BY: CD
FIGURE IA
- ;~ "~4~ow-a-~-~.--_
I ~ ~
/ ~'~ ~'~ ,.
J ~~al-TA ',
~-- ~' (ALTERNATE ALIGNMENTJ
NOTE: BORINGS 6A ~ 7A
INCLUDED IN
ADDENDUM REPORT.
~, ADDENDUM REPORT ) ~EXISTING SEWERLINE ~- '~ '
I - ' "
~~do~~~. ,,
NOTE' BORING LOCATIONS ARE APPROXIMATE ' ~ ~ATCHLINE D--
P~EC~ ~LE
PROPOSED GRAPEVINE SEWER TRUNK MAIN OOPPELL, TEXAS
- 586 I SCALE: 1" = 300' * / - DATE: 031 17 / 92 DRAWN BY: CD
BORING
LOCATION
DIA~
RAM
SWL
91
FI~UEE
LOG OF BORING
PROJECT: Grapevine Sewer Trunk Hain - ?base I BORING NO.: B1-9
CLIENT: Ginn and Case, Inc. LOCATION: Coppell, Texas
DATE: 4-17-92 TYPE: Auger CASED TO: GROUND ELEV:
' ~ ~ Seepage at 16', water at 11
~ ~ ~ ~ at completion, water at 10'
... ~
_~ ~rayish brown sandy clay
~ ~ron oxida traces
-~ith broken asphalt abovo 1
~Dark bro~ and brown sandv s/
5 ~ clay with calcareous nodule ................................... ' .................... ~ ......
~~Dark grayish brown silty f
clay to sandy clay (CL)
10 .................................................................
~ : Tan and gray sandy clay with
i calcareous nodules and iron
ore Cebbles
Tan and gray shaly clay ~ith
bentonite seams (CH)
.
20 ~ ~ Dark gray and tan shaly clay
25- Boring terminated at 20I r - ..... J ..................... ~ ........................... ] ......
30 ~ .................................... ~ ...........................
3fi .................................................................
PROJECT NO. : 91-586 SOUTHWESTERN ~BORATOR/ES INC.
LOG OF BORING
PROJECT: Grapevine Sewer Trunk Main - Phase I BORING NO.: Bi-iA
CLIENT: Ginn and Case, Inc. LOCATION: Coppell, Texas
DATE: 5-12-92 TYPE: Auger CASED TO: GROUND ELEV:
,~ Brown and tan clay 16 ~ .8
~ Tan silty sand ~
' ~ ~ Brown clayey sand ~14 36 I 18 18
Dark brown to blac~ sandy
1~ ~i , ~ [Grav and tan sandy clay_with pebbles below 10' (CL)[ Z__~i ..................... ' ...................................
~ ~ ~ [~ Tan and gray shaly clay ] ,
--10¢~' -with embedded shale (CH)
20 ; 1~" layers
~ Gray shale ~ ~
Boring terminated at 20'
*T~
35 ~ ...................... i ..........................................
-- [ I
I ~ I
40 -- · .................... ] ................... ; ............. 4 ......
454 ~ ............. -] .................................................
,
PROJECT NO.: 91-586 SOUTHWESTERN I_ABORATORIES
A-4
LOG OF BORING
PROJECT: Grapevine Sewer Trunk Main - Phase I BORING NO.: B1-2A
CLIENT: Ginn and Case, Inc. LOCATION: Coppell, Texas
DATE: 5-12-92 TYPE: Auger CASED TO: GROUND ELEV:
i ~ ~ ~ 17' and water at 15' on
Dark brown and gray silty
~ to sandy clay .................................... ~ .................... 4 ......
_ ~ Brown sandy clay (eL) i '
~: 11 37 ~ 15 22 [
10 ~ i: Brownish gray sandy clay. ' ; '
.... with pebbles (CL) !
15- ~ Tan and gray sandy clay
! . Gray and tan sandy clay
' I -with clavev sand layers
20
Tan sand (SM)
-with clay seams below 19' .
i Boring terminated at 20f
30 ~ ..................... J ....... ~ ..................................
35 ~
--- ~ .................... ~ .............. ~ ......
45 .............. ~ ..................... ¢ ...........................
PROJECT NO.: 91-586 SOUTHWESTERN ~BORATORIES INC.
A-5
LOG OF BORING~
~ROJECT: Grapevine Sewer Trunk Main - Phase I BORING NO.: B1-3A
'- CLIENT: Ginn and Case, Inc. LOCATION: Coppell, Texas
DATE: 5-13-92 TYPE: Auger CASED TO: GROUND ELEV:
~ ~ ~ ~ ~ _~ 14' at completion.
Z
Tan and brown sandy clay 11 1126 ' ~ 7,430 6.5
'~ ~ Brown and gray. sandy clay
, ~ -FILL-
10~ ~ 25 Tan sandy clay (CL) i
Tan sand and gravel (SM-GM)
--' ~ 30*
15~ ~,' ....................
= ~ Tan and gray shaly clay (CH)
-with shale seams below i1'
- Gray weath~rod shale
25 Boring terminated at 20~
30 ~ .............. ~ ............................ r ....................
.................... z ....... [ ...... ~ ...... ~ ....................
40-- i ................................................................
4s- [ ...... ..............
PROJECT NO.: 91-586 ~OUTHWESTERN ~BORATORIES lNG.
A-6
LOG OF BORING
PROJECT: Grapevine Sewer Trunk blain - Phase I BORING NO.: B1-4A
CLIENT: Ginn and Case, Inc. LOCATION: Coppell, Texas
DATE: 5-15-92 TYPE: Auger CASED TO: GROUND ELEV:
~ Seepage at 8', water at 12'
m ~ ' 0 z
~ 6" Pavement / 11 118 22 14 6 42.0 1,200 1.2
Tan clayey sand (SC) . , ~ I
21 Tan clavev sand with gravel 8 ;
(SC) I
~ '' ~m Reddish tan silty sand (SM) ~ ' ~ ~ '
10 · ~ with trace gravel
15-- ~ ~ Gray shale ................................................................
~ i; Boring terminated at 20'
LOG OF BORING
PROJECT: Grapevine Sewer Trunk Main - Phase I BORING NO.: B1-5A
CLIENT: Ginn and Case, Inc. LOCATION: Coppell, Texas
DATE: 5-15-92 TYPE: Auger CASED TO: GROUND ELEV:
PEN i RECOVERY L~
Dry at completion.
! ~- 0 z
~ O __.
6" Pavement /
11 126 23 16 7 45.6 9,220 2.8
Tan sandy clay with dark
8 brown silty clav with trace
Brown and gray sandy clay
~ to clayey sand
-FII.L- 14 120 , 6,440 A.0
~ . Dark brown sandy clay (CL)
10
'Reddish tan sandy clay (CL) 27
15 ~- ' ' '
\ Tan clay (CL)
20 · ! 'Fan and gray shaly clay with
' silt traces
--i -with shale seams below 18~
--, (CH)
25 Boring terminated at 20~ ~. ..................... - .........................................
30 -i
35 -. . ................................... ~_ ..........................
i
40 ~ .................................... ~_ ..........................
" ~ i I
45- i
i
PROJECT NO. ' 91-586 SOUTHWESTERN LABORATORIES INC.
A-8
LOG OF BORING
PROJECT: Grapevine Sewer Trunk Main - Phase I BORING NO.: B1-6A
CLIENT: Ginn and Case, Inc. LOCATION: Coppell, Texas
DATE: 5-15-92 TYPE: Auger CASED TO: GROUND ELEV:
,
, ,I [] ~ I~ ~ ~! ': ' - ~- ~
ZuJ n
~,~ ~ 'GROUNDWATER INFORMATION :. U ~ I-'~ -- . 13. O i ~ Z ~ ·
Seepage at 17', water at i~ ~ ~ ~ ~ ~ ~ ~z ~ Om
~ ~ ~ 17' after 5 hours ~ ~ ~ ~ ,,,
~O O; 03 O
Z!~zO-
~'---'~ I 6½'' Pavement
-- 20 113 2,750 4.3
Tan and gray silty clay ; ~
$ - ---~-z ....................... ? ............. ~ ............. : ......
~i Brown and tan sandy clay
i with occasional burnt 16 !05 7,020
3.9
~0-~ - wood f~_~t~,t_s ....... .............
' Tan clay (limy) with gypsum ,
--: partings (CH) ,
' I -with shale seams below 12~ : ...... ~ ............................ ~ ......¢ ....................
15d ,
,
i ' Gray weathered s~ale ~
[40* -with occasional bentonite
20 '~, 6" .~ m mm.~ i - ~
100'! i '
'zF-'T/;5" Gray s~ale ,. ~
Boring
terminated
23~
25- ~' - ...... ...... ....... - ...... ...... ..................... ~ ......
! ·
' i
· THD i
30 ....... ~; ...... ; ............................ '-' ....................
i
.__ 35 -~ ,- ................... ~ ..........................................
" I
40 ~ ..................... ~ ........................................ ~
'
" "
45 -q ....... ? .......................................................
PROJECT NO. : 91-586 SOUTHWESTERN LABORATORIES INC.
A-g
LOG OF BORING
PROJECT: Grapevine Sewer Trunk Hain Phase I BORING NO.: B1-TA
CLIENT: Ginn and Case, Inc. LOCATION: Coppell, Texas
DATE: 5-15-92 TYPE: Auger CASED TO: GROUND ELEV:
co~ · CONE
Seepage at 17', water at 22'
O z
10 116 22 14 6 39 ~ 2,320 9.9
Tan sandy clay and clayey
5 sand
_FILL- 13 12.
Tan sandy clay with (eL)
10 - occasional gravel ............. ~ ............................ 7 ....................
~ Tan clay with silt and (CL)
~' ~ lime traces 29 98~ ~ 3,960 2.5
15 q -with bentonite se~ at 14.5 ' .............. i, .................... ~ ~ ...... ~ ....................
20-- ~ Light grayish tan clay ~ith
silt se~s and 5ton oxide t ...... ~ ..................... { ......7 ...........................
--~ traces (Ca)
Dark gray clayey weathorod
100~ Dark gray shale
__~ Boring termSnated at 32~ ~'
3s - ': .............. [ ..................................
' ~THD
P~O~[ClUO.: 91-586 A-10
(/3· ~- / '----- z
.~ c- 0
I~1 .~_ N -- ~
~ 0 ~ Z
o
0 0 0 0 0 0 0 0 0 0 O~
~B~o~ ~q [u[ssod ~uoa~od
A-11