Lost Creek TH-CS070614
Rone Engineering
..
. GEOTECHNICAL ENGINEERING
. CONSTRUCTION MATER IALS TESTING
. ENVIRotIMENTAL CONSULTING
. FORENSIC ENGINEERING
DALLASIFORT WORTH
8908 AMBASSADOR ROW
DALLAS, TEXAS 75247
TELEPHONE 214-630-9745
TELEPHONE B17~Z84-1318
FACSIMILE 214-630-9819
HOUSTON
7701 WEST LITTLE YORK
SUITE 600
HOUSTON, TEXAS 77040
TELEPHONE 7 I 3-996-9979
FACSIMILE 713-996-9972
AUSTIN
422' FREIORICH LANE
SUITE 195
AUSTIN, TEXAS 78744
TELEPHONE 512-462-2733
FACSIMILE 512-462-1155
June 14, 2007
Mr. Jason Rose
JR Development Companies
1207 Bethel School Court
Coppell, Texas 75019
Re: Geotechnical Engineering Report
Proposed Lost Creek Townhomes
Coppell, Texas
Rone Project No. 07-12989
Dear Mr. Rose:
Submitted herewith are the results of a geotechnical investigation
conducted for the referenced project. This investigation was performed
in accordance with our proposal 07-11444 dated April 19, 2007.
This report presents engineering analyses and recommendations for site
grading and foundations. Results of our field and laboratory investigation
are submitted in detail in the Appendix section of the report.
We appreciate the opportunity to be of service to you on this project.
Please contact us if you have any questions or need any additional
services.
Respectfully Submitted,
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Mark L. McKay, P.E. ;' * ," ". * 'A
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Senior Geotechnical Engineer ~"":",,,,,,,,,,,,,,,,;,,,"l
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trenches should be free of any loose or soft material prior to the placement of the concrete. All
grade beams and floor slabs should be adequately reinforced with steel to minimize cracking as
normal movements occur in the foundation soils.
According to the Post-Tension Institute (PTI) the design parameters for design of foundations at this
site are as follows:
Edge Moisture Variation Distance
Center Lift 5.1 feet
Edge Lift 4.1 feet
Differential Swell
Center Lift
Edge Lift
2.4 inches
1.4 inches
A moisture barrier should be used beneath the slab foundation in areas where floor coverings will be
utilized (such as, but not limited to, wood flooring, tile, linoleum, and carpeting).
Pavement Design Recommendations
The fottowing pavement sections are a minimum recommended for this project based on a 2D-year
life design. They are based on our engineering judgment and experience with environmental
factors, including temperature, humidity, rainfall and swell characteristics of the soils.
We recommend a 5-inch section of Portland cement concrete (PCG) for automobile parking areas
and a 6-inch section for drive lanes receiving medium volume truck traffic. A minimum 7 -inch
section is recommended in areas receiving frequent heavy trucks and dumpsters. Concrete with a
minimum 28-day compressive strength of 3,500 pounds per square inch is recommended.
All topsoil, existing pavement and structures, vegetation, and any unsuitable materials should be
removed. The pavement subgrade should be proofrolled with a fully loaded tandem axle dump truck
or similar pneumatic-tire equipment to locate areas of loose subgrade. In areas to be cut, the
proofroll should be performed after the final grade is established. In areas to be filled, the proofroll
should be performed prior to placement of engineered fill and after the pavement subgrade is
established. Areas of loose or soft subgrade encountered in the proofroll should be removed and
replaced with engineered fill, or moisture conditioned (dried or wetted, as needed) and compacted in
place.
Project No. 01-12989
Page 4
The clay soils are plastic and can undergo some volume change when subjected to moisture
variations. If the moisture contents of these upper soils reduce, they may shrink and cracks may
develop. If the moisture content of these materials increase, they could swell and lose strength.
Shrinkage, swelling, or strength loss could be detrimental to the proper function of the pavement.
Lime treatment of clay subgrade is recommended in areas receiving heavy truck traffic to provide
more uniform subgrade support and improve these soil's strength characteristics. Lime treatment is
not necessary in areas subject to light vehicular traffic. we l'='\.iUnll'ft::TI~hrn,~,I_"um-0t8 ~Cdllt
lime' (by dry soif weight)' to a depltt of & inches:' Lime stabilization should be performed in
accordance with Item 260, current Standard Specifications for Construction of Highways, Streets,
and Bridges, Texas Department of Transportation (TxDOT) or applicable standards.
The final grades must be such that drainage is facilitated, and access of surface water to the
subgrade materials is prevented. Water can be introduced beneath the pavement through granular
materials used for aggregate bases and utility line embedment, and this water can cause differential
movement in the pavement. Aggregate base or a granular leveling course should not be used
beneath pavements, and all utilities should have clay plugs substituted for granular embedment
material at the edges of the pavement to reduce the risk of moisture access and possible swelling.
General
All grade supported slabs, outward swinging doors, outside stairs, etc. should be designed to
accommodate anticipated potential movements as presented in the section titled "Potential Vertical
Soil Movements" earlier in this report.
Every attempt should be made to limit the extreme wetting or drying of the subsurface soils because
swelling and shrinkage of these soils will result. Standard construction practices of providing good
surface water drainage should be used. A positive slope of the ground away from any foundation
should be provided. Also, ditches or swales should be provided to carry the run-off water both
during and after construction. Lawn areas should be watered moderately, without allowing the clay
soils to become too dry or too wet. Roof runoff should be collected by gutters and downspouts, and
should discharge away from the building.
Backfill for utility lines or along the perimeter beams should consist of site-excavated soil. If the
backfill is too dense or too dry, it will swell and a mound will form along the trench line. If the backfill
is too loose or too wet, it will settle and a sink will form along the trench line. Backfill should be
Project No. 07-12989
Page 5