Villas at LV 2-LR121206 (2) From: 12/12/2012 15:22 #234 P.007/021
Geoteclrnical 2209 Wisconsin St. Tel:972.620.8911
S L P N A ikTESTING Construction Materials Suite/00 Fax:972.620.1302
Environmental Dollar, Texas 75229 www.alphatesting.corn
TBPE Firm No.813
WHERE IT ALL BEGINS
December 6,2012
JBGL BF Development LLC
3131 Harvard Ave.,Suite 103
Dallas,TX 75205
Attention:Scot Whitwer
Re: Laboratory Testing-Soluble Sulfates
Villas at Lake Vista Phase 2
Utilities&Paving
Coppell,Texas
ALPHA Report No. 121732-5
Soil samples obtained at random locations from the exposed pavement subgrade have been tested for the presence of
soluble sulfates. Sulfate induced heave in soil has been known to occur on a local basis in the residual soils of
primarily the Eagle Ford formation. Further,some other formations have been known to contain soils with soluble
sulfates. Results of the laboratory testing(EPA Method)on the samples obtained are tabulated below.
Sample No. Approximate Location Soluble Sulfate,
Mg/Kg
1 Chipping Way at Station 1+60 813
2 Calcot Drive at Station 1+55 9,130
3 Cotswold Lane at Station 0+75 3,070
4 Snowshill Trail at Station 0+40 1,090
5 Snowshill Trail at Station 4+50 1,170
6 Snowshill Trail at Station 6+90 3,260
Please note that relatively high concentrations of soluble sulfates (in excess of 2,000 ppm) in soil can be very
localized and the field sampling and laboratory testing performed herein, regardless of sampling and testing
frequency, does not preclude the possibility that soils with significantly different (higher or lower) amounts of
soluble sulfates are present on the site.
Soluble sulfate test results in excess of 2,000 ppm indicate high risk of sulfate induced heave in lime treated
subgrade. Based on the test results,the exposed subgrade along all streets should be treated by a double application
of lime. Half of the total specified lime percentage(by a lime series)plus 1 percent extra should be initially mixed
into the subgrade soils with excess water(5 percentage points over optimum). The mixture should be thoroughly
blended, with the material kept continually wet. The surface should then be sealed with a drum roller or other
suitable equipment,and allowed to mellow for at least seven(7)days. During the curing period,the surface should
be wet cured using a water truck and observations should be made to determine if any heaving is taking place.After
seven days,the remaining half of the total lime plus 1 percent extra should be mixed in with the subgrade soils.This
material should be thoroughly mixed with additional water so that the soils are above optimum moisture, and then
the surface should be sealed again. The soils should be allowed to mellow for 72 hours while the surface is kept
continually moist and observed for signs of distress. If no significant problems are observed, the soils should be
final mixed to meet the project gradation specifications and compacted. Use of Type V cement(sulfate resisting)in
the concrete is required to reduce the potential for the sulfates to attack the concrete. If time is a factor and the
construction schedule does not allow sufficient time for the double lime process, the owner/developer may elect to
treat subgrade soils using the Alternative Method described below.
Dallas• Ft.Worth•inn Anntonio
From: 12/12/2012 15:23 #234 P.008/021
7'
Alternative Method: Lime treatment of the subgrade soils can be eliminated by increasing the PCC thickness in the
pavement section by 1 inch. Use of a Type V cement(sulfate resisting)or approved equal in the concrete is required
to reduce the potential for the sulfates to attack the concrete.
Thank you for this opportunity to provide our services. If we can be of further assistance,please contact us.
Sincerely,
ALPHA TESTING,IN•
P�E OF TEL` /��
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f ;;°.................t. Theodore A.(Tony Janis,P.E.
THEODORE A.JANISH : Principal
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