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Children's World-CS 860820! Subsurface Investigation I CHILDREN$ WORLD Child Care Center I Hoore Road Coppell, Texas ! CHILDRENS WORLD C/O Smith, Ekbiad & Associates, Inc. Daiias, Texas By Hooper Engineering Laboratories, Inc. 2870 Walnut Hill Lane I Dallas Texas 75229 Tel 214/~51-6419 I HEL .lob No. 86.2:~0 /tugust 20, 1986 I TABLE OF CONTENTS INTRODUCTION ............. FIELD EXPLORATION ........... 1 LABORATORY TESTING .......... 2 GENERAL CONDITIONS Topography ............. Geology of the Site ....... 4 Soil/Rock Profile ......... 4 Shrink/Swell Movements ....... 6 Ground Water ...... RECOMMENDATIONS Shallow Foundations .... 6 Floor Slab-on-Grade ........ 7 Pavement Subgrade Preparation ...... 8 Surface ..Drainage Plan ........ SUMMARY .......... LIMITATIONS ............. 11 SUMMARY OF LABORATORY TEST RESULTS ...... 12 BORING LOCATIONS ........... 13 LOG OF BORINGS ............ 14 INTRODUCTION This investigation was conducted to determine the gao- technical engineering characteristics of the subsurface soil/ rock profile at the proposed location for a new Child Care Cen- ter on Moore Road in Coppelt, Texas. The subsurface conditions were evaluated in order to formulate recommendations for the type of foundation system that is best suited to this particular site and the structure that is planned. Two test borings were drilled at specific locations t~at were selected by the geotechnical engineer to represent the area to be covered by the building and the paved parking areas. Each of the test borings was drilled to a depth that is suffici- ent to evaluate the soil/rock profile for consideration of a drilled pier foundation system to support the light single story structure. A drawing is included in this report that notes the boring locations referenced to the property lines and building lines shown on the site plan furnished to the geotechnical engi- neer by the architect. FIELD EXPLORATION Test borings were advanced with a truck mounted rotary drill using a continuous flight, hollow stem auger, and since this method of drilling does not require the use of water, there was no moisture contamination of the subsurface soils that were sampled. R~ 9xn Undisturbed samples of the subsurface "cohesive soils and disturbed samples of rock were obtained through the hollow stem auger using a thin wall Shelby tube sampler. The soil and rock samples were ejected in the field to examine for sample quality and testability. The low cohesion soils found in the subsurface profile cannot be sampled in a condition that would allow for effective strength testing in the laboratory, and were evaluated in-place using the Standard Penetration Test apparatus. This test con- sists of driving- a two inch diameter, split-spoon sampler into the soil layer with blows from a 140 poun~ weight dropped with a 50 inch free fall. The number of blows required to drive the sampler 12 inches is a value that can be correlated to the allowable bearing capacity for the coarse grain soil, and the blow count is shown on the boring logs at the test depth.' Each soil and rock sample was sealed in a polyethylene bag to ma'intain the in-place moisture content, a~d packed in a protective wooden box for transporting to the laboratory. Relative elevation of the surface at each boring ground location was determined using a hand level, and the elevations noted on the boring logs are accurate to within one foot. LABORATORY TESTING Each soil sample was visually examined by an experi- enced soils technician, and classified according to the Unified Soil Classification System. Undisturbed soil samples were trimmed to required test- ing dimensions, and were tested for in-place water content, dry unit weight and unconfined compressive strength. The results of these tests give the normal engineering characteristics required for evaluating the shear strength and consistency of fine grain soils found in the subsurface profile. Soil samples obtained from the Standard Renetration Test are disturbed from their in-place condition and are tested in the laboratory for in-place water content only. Representative samples of each fine grain soil type found in the subsurface soil profile were tested for Atterberg Limit values· These index values give an indication of the potential soil volume change that might occur when there are changes in the soil' moisture content. Coarse grain soils were tested for the quantity of particle sizes finer than the 200 mesh sieve to assist in the classification of the soil type, and to evaluate' the in-place penetration test results. GENERAL CONDITIONS - Topography The ground surface at this site on ~4oore Road is fairly flat terrain, with only a two feet difference in elevation noted at the test boriog locations· This relatively flat ground sur- face does not cause surface water to drain off of the site read- ily, and is an unfavorable feature that should be corrected in the design of the final grading plan for tbs development of the property. )4OOl~:i~ & &IIIOClATI'I. INC., ~ There is a solid cover of grass and w~ist high weeds growing on the site, and stripping to a depth of one to two inches will be necessary to remove this vegetation prior to con- struction in the building area and the paved areas. Trees on the site will draw moisture from the subsur- face soil in an irregular pattern. This loss of moisture, and the subsequent rewetting of the soil profile will cause move- ment in shallow foundations and surface structures. Trees should be planted at least one half the full grown tree height from surface structures to substantially avoid the effect of these movements. Geology of the Site - Terrace Deposit/Ea~le Ford Shale This site is located in an area of Dallas County where the primary geological formation, the Eagle Ford Shale, is over- lain by a very thick deposit of alluvial terrace materials. The alluvial soils are thoroughly mixed during the transporting of the materials, and a terrace deposit normally consists of all soil sizes, including clay, silt, sand and gravel. The terrace deposit varies laterally, changing from fine grain soil to coarse grain soil in very short distances. Often, the surface soil is a high plasticity clay or silt that may be subject to significant shrink/swell volume changes with seasonal changes in soil moisture content. Soil/Rock Rrofile Samples obtained from th~ test borings show the surface soil is a brown to tan and orange clayey sand that has low plas- ticity characteristics (PI = 5 to 15), and is the type of soil that will exhibit negligible shrink/ swell volume changes with seasonal changes in soil moisture content. In-place penetration test results indicate the near surface soil has moderate bearing capacity, and could be used to support light foundation loads. The brown to tan and orange clayey sand is dense to medium dense in consistency, moist in water content, and extended from the ground surface to a depth of six feet at the test boring loca- tions. Below the brown to tan and orange clayey sand is a thick layer of tan and orange sand that has low plasticity char- acteristics (RI = 5). In-place penetration test results indi- cate the sand is medium dense in consistency, and there should not be excessive settlement in the sand under light foundation loads that are based in the overlying soil. The sand is moist to wet in water content and extended to depths of ten and a half feet and ~leven feet at the boring locations. Grey and orange clay with thick seams of sand is found below the clayey sand, and extended to depths of seventeen feet and seventeen and a half feet at the boring locations. In-place penetration test results indicate the grey and orange clay with thick seams of sand is very stiff to medium dense in consistency and moist to wet in water content. Brown and grey clayey sand is found below these depths and extended to the termination depth of the test borings at twenty five feet. In-place penetration test results indicate R4 9%n the brown and grey clayey sand is medium dense in consistency and moist to wet in water content. Shrink/Swell Movement Total shrink/swell potential for this soil profile is less than one inch as the soil profile goes from a dry weather condition to a point of complete saturation. Ground Water ~Ground water was found in each of the two test borings drilled for this investig@tion, at depths of ten and a half feet and seventeen and a half feet below the existing ground surface. RECOMMENDATIONS - Shallow Foundations The subsurface soil/rock profile consists of low to moderate plasticity soils for a significant depth, and there should be negligible shrink/swell movement in the profile as there are seasonal changes in soil moisture content. Under these conditions, a shallow foundation system will perform well, and is recommended. Grade beams and spread footings should be set in the natural soil profile at a minimum depth of eighteen inches below finished grades, and an allowable bearing capacity of 2 000 psf should be used to size these structural members. The beams should be cast monolithic with the floor slab to give added stiffness to the foundation system. NOOKN & &IIC)CN&TI:~ INC, · Floor Slab-on-Grade '~ A slab-on-grade floor system can be used at this site, and the finished floor elevations should be set high enough to assure that surface water will drain away from the perimeter of the building. The ground surface should slope away from the foundations at a minimum slope of one foot vertical in ten feet horizontal, for a minimum distance of six feet. Some mixed clay fill was found at the ground surface at test boring two, and suggests that some preparation of the buil- ding area should be performed to assure firm support for founda- tions and the floor slab-on-grade. After the building area has been stripped of vegetation, the top one foot of subgrade soil should be scarified, wetted and lightly recompacted. The sub- grade should be compacted to the range of 95 to 100 percent of ASTM D698 (Standard Proctor) maximum density at a moisture con- tent above optimum. On-site soils could be used to raise the' grade for the building pad. The brown clayey sand surface soil should be placed in thin lifts (8 to 12 inches), and should be uniformly compacted to a minimum of 95 percent of ASTM D698 (Standard Proctor) maximum density. Moisture content of this material should be within three percent of optimum during compaction. If borrowed fill is used to raise the grade beneath the floor slab, the fill should be a non-expansive soil having a plasticity index less than fifteen. The fill should be placed in thin lifts (8 to 12 inches), and should be uniformly compac- ted to a minimum of 95 percent of ASTH D698 (Standard Proctor) ~ ~-'z~ "*7 maximum density at a moisture content within three percent of optimum. Moisture content and density of the subgrade and the fill is very important, and each compacted lift should be tested in-place at a frequency of one test per ~000 square feet to verify that the materials are properly placed. A four inch minimum thickness of cushion sand could be used for fine grading the subgrade beneath the floor slab, and a moisture barrier membrane could be specified to prevent water movement through the floor slab. Ravement Subgrade Preparation The existing sub~orade soil is sufficiently low in plas- ticity characteristics to be classified as a good subgrade for an asphalt pavement or concrete pavement without the use of a stabilizing agent. After the surface has been brought to grade, the top six inches of subgrade soil should be compacted to a minimum of 95 percent of ASTM 0698 (Standard Proctor) maximum density at a moisture content above optimum. The compacted sub- grade should be tested for in-place density and moisture content at a frequency of one test per 5~000 square feet, within 48 hours of pavement construction. A 4 inch thickness of asphalt pavement should be used in automobile parking and traffic areas, and a thicker pavement should be designed for areas where heavier wheel loads are an- ticipated. The 4 inch thickness is normally made up of a 2.5 inch coarse graded binder course, and a 1.5 inch fine graded surface course. Thinner pavements will require more maintenance than most owners feel is normal, and it is a problem for them to arrange and coordinate the repairs. Concrete pavement may be placed directly on the pre- pared clay subgrade, and a subgrade modulus value of 150 should be used in the thickness design for the pavement. Surface Drainage Plan .The subsurface soils at this site are not overly sensi- tive to changes in soil moisture content, but an effective sur- face drainage plan is always important when a shallow foundation system is used. All surface moisture should be drained away from the building and not allowed to pond near the foundations. Allowing moisture to penetrate into the subsurface soils will result in a reduction in soil shear strength that would have adverse effects 'on the foundation system and pavement surfaces, and should be avoided. " Currently there are rather poor drainage conditions due to the relatively flat ground surface at the site, and final grades should be designed to improve this unfavorable condition. SUMMARY This site for the single story Child Care Center on Moore Road is located in an area of Dallas County where the primary geological formation, the Eagle Ford Shale, is overlain by a very thick layer of alluvial terrace materials. There is a thick surface layer of low plasticity, brown to tan and orange clayey sand, a layer of low plasticity, tan and orange sand, a thick layer of grey and orange clay with sand seams, and then brown and grey clayey sand extended to the termination depth of the test borings at twenty five feet. There should be negligible shrink/swell movement in the soil profile as there are changes in soil moisture content, and shallow foundations could be used at this site. In-place penetration test results indicate the near surface soil has moderate bearing capacity, and could be used to support light foundation loads. Ground water was found in each of the test borings drilled for this investigation. There should be negligible shrink/swell activity in the soil profile, and a shallow foundation system could be used to support the single story building. Grade beams and spread foot- ings should be set in the natwral soil profile at a minimum depth of eighteen inches, and the beams should be cast monolith- ic with the floor slab to give added stiffness to the foundation system. A slab-on-grade floor system can be used' at this site, and the finished floor elevations should be set high enough to assure that surface water away perimeter will drain from the of the building. On-site soil or borrowed fill could be used to raise the floor elevations and to improve the surface drainage conditions at the site. Asphalt pavements or concrete pavements could be placed directly on the subgrade soil, subgrade and the should be uni- formly compacted prior to pavin9 with either material. Effective control of surface water is very important when shallow foundations are used. The final grading plan should be designed to assure that all surface w~ter flows .away from the building without allowing substantial penetration of water into the soil profile. LIMITATIONS Every effort has been made to properly evaluate the subsurface conditions at this site based on the samples recov- ered from the test borings and the results of laboratory tests on these samples. However, it must be recognized t'hat the con- clusions reached in this report were based on the conditions at the two test boring locations. Our professional services were performed, our findings were obtained, and our recommendations prepared in accordance with generally accepted engineering prin- ciples and practices. To assure that recommendations made in this report are properly interpreted and implemented in the plans and specifica- tions, a general review of the final plans and specifications by the geotechnical engineer is recommended. If the geotechnical engineer is not provided an opportunity to make this review, he can assume no responsibility for misinterpretation of his recom- medations. Should any unusual conditions be encountered during construction of this project, this office should be notified immediately so that further investigation and supplemental m de. ~-.." Y-~ '...t R~spect fully submitted, ~C m D ~ R ~ '~ )'¢ ~ ~ ''~]:¢:1~ ~ C ' Darrow Hooper, M. Engr., P.E. ~:.~1@137'~)!i-:~ Consul ting Geotechntcal Engineer -- I SUMMARY OF LABORATORY TEST RESULTS JOB NO. 86.250 ~ 18 August 1986 Boring Depth Description Dry Liquid Plasticity Soil Water Unconfined Unit No. Feet Content Unit Limit Index CompressiYe Strain Class Weight Strength I 0 CLAYEY SAND, brown, SC 7.7 I 2 SANDY CLAY, tan ~ orange, CL 10.2 5B.4~ Minus 200 Mesh 1 4 CLAYEY SAND, tan ~ orange, I g SANO, tan & orange, with some fine gravel SP 16.0 1 14 CLAYEY SAND, tan & orange, SC 1 19 SANDY ~ CLAY, grey orange, CL 1 24 SANDY CLAY, grey & orange, CL !6.8 2 0 SANDY CLAY, tan & brown, ~Fill) CL 10.B , 2 2 . SANDY CLAY, tan & brown, (Fill) CL 10.8 2 4 SANDY CLAY, orange & tan, CL 12.0 57.3% Minus 200 Mesh 2 9 CLAYEY SAND, orange ~ tan, SC 5.7 2 14 CLAY, grey & orange, with sand seams CL 20.1 130 3g 26 1.g 8.~ 2 19 CLAYEY SAND, grey t orange, SC 18.3 2 24 CLAYEY SAND, grey ~ orange, SC 21.1 I-IOOl~Cli & lkllOCl&?[i. II, lC, -- mNORTH SCALE I" = 50' Boring Locations Project=DAY CARE CENTER COPPELL , TEXAS Client = CHILDRENS WORLD JobNo= 86.230 14 AUGUST 86 HOOPir~i & &IIOCI&T[~, INC. I I !. I LOG OF 80RINGS The boring logs and related information ~epict sub- I surface conditions at these specific locations and at the particular time desi§nated on the logs. Soil conditions at other locations may differ from the conditions found at these boring locations, and with I. the passage of time, soil conditions at these boring locations may change. ~Ki~ & &IIOCI&T[Io INC. · Log of Boring PROJECT: Day Care Center BORING NO: CLIENT: Children' s World LOCATION: Coppell, Texas JOB NO: 86. 230 BORING TYPE: Hollow Stem Auger DATE: 8/13/86 DRILLER: Wigington GROUND ELEVATION: 100 m m U. Z ~ LEGEND: B- BAG i,~ I- 12. I'- (J) 0 ~ S -- SHELBY TUBE C -- CORE W~ O'J i.~' ~m i- ~ ~ P-- STD PEN TEST X-- NO RECOVERY m O a T -- THD CONE TEST V-- WATER TABLE -- am (0( m EZm Em(/} DESCRIPTION OF STRATUM ?/~ B Brown clayey sand, medium dense h  moist 1.0 ' P 36/30/19Tan ~ oran~e clayey sand, dense ~ moist ,.?./.:?:, Orange & tan sand, medium dense '..;i..:;.. ~ moist 8.5' .:. I...:?': Tan sand with gravel medium ! '. . ~ , ~o :;i',:.i' ? b/10/l[1 dense ~ moist ~ 10.5' ~ Grey [ orange clayey sand, medium :'""/' dense [ moist S 5.25 .a~ P 7/8/13 17.0' ~//~//~ Grey S orange sandy clay, very · o~ P 5/6/9 stiff [ moist .~,~ P 4/6/9 End of Boring 25' -30- ~0' Log of Boring PROJECT: Day Care Center BORING NO: CLIENT: Children' S World LOCATION: Coppell, Texas JOBNO: 86.230 BORINGTYpE: Hollow Stem Auger DATE: 8/13/86 DRILLER: Wigington GROUND ELEVATION: 102 Itl IU u. Z · LEGEND: B- BAG 12 !- G. ~ 0 ~ S-- SHELBY TUBE C-- CORE ~1~1 ~' )" ~ I- ~ ~0 F- ~ P--STD PENTEST X-- NO RECOVERY = 0 .~ T -- THD CONE TEST V-- WATER TABLE ~' ( z -, ~ DESCRIPT,ON OF STRATUM  B Tan & brown sandy clay, hard & moist ~fill) 2.5' S ~'~~ Orange & tan clayey sand, medium -~- P 7/7/9 dense & moist ~...../.~'~:~.' Tan & orange sand, medium dense ....... :~: & moist ..' %~ ~o ~[~[~:? P 6/6/6 11.0'  Grey & orange clay with sand seams, very stiff & moist ~': :: ' Brown [ grey clayey sand, medium -~o ~ P ~4/6/5 dense [ moist -~ P 1/5/5 End of Boring 25' -$O- .40. H~P[~ & &IIOCI~TEI. INC.