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HomeMy WebLinkAboutSubsoil Study for Foundation Design 05.10.15HEPWORTH I [,k hni...I In.. i020 C:.amn Road 154 Glrnm'nd Spring-. CnLmiJo I W I Phone- 9794;-7988 P,,: 90.945.1454 moo, hpc.. �'�Iq�emomdia,in JOB NO. 116 136A MAY 10, 2015 PREPARED FOR: JOEL RUIZ P.O. BOX 37 ILT, COLORADO 81652 ioel-ruiz@live.com Parker 303-841-7119 h Colorado I Springs 719-633-5562 • Silverrhome 970-468-1989 SUBSOIL STUDY FO t FOUNDATION DESIGN P 10POSED RESIDENCE LOT 2', SUN MEADOWS ESTATES SC UTH MEADOW CIRCLE GARF ELD COUNTY, COLORADO JOB NO. 116 136A MAY 10, 2015 PREPARED FOR: JOEL RUIZ P.O. BOX 37 ILT, COLORADO 81652 ioel-ruiz@live.com Parker 303-841-7119 h Colorado I Springs 719-633-5562 • Silverrhome 970-468-1989 PURPOSE AND SC OPE OF S' PROPOSED CONS FRUCTIOl SITE CONDITION ................ FIELD EXPLORA ION.......... SUBSURFACE CO DITIONS FOUNDATION BE RING C( DESIGN RECOMMENDATIC FOUNDATIONS .................. FLOOR SLABS .................. UNDERDRAINYSTEM... SURFACE DRA AGE...... FIGURE I - LOCATION OF E FIGURE 2 - LOGS F EXPLO FIGURE 3 - LEGED D AND NI FIGURES 4 AND 5 - SWELL -1 TABLE 1- SUMMARY OF LA Job No. 115 112A OF CONTENTS ORATORY BORINGS TORY BORINGS CION TEST RESULTS TEST RESULTS The proposed reside ice will bet o story wood frame construction over a crawlspace and - located between the xploratory borings as shown on Figure 1. Ground floor of the garage will be slab -ca -grade. Grading for the structure is assumed to be relatively minor - with cut depths betty en about 3 to 5 feet. We assume relatively light foundation loadings, typical of t ic proposed type of construction. If building loadings, ocation or ading plans change significantly from those described above, we should be otified to r -evaluate the recommendations contained in this report. PURPOSE AND SCOPE OF STUDY - This report present the results f a subsoil study for a proposed residence to be located on Lot 27, Sun Me dows Estate;, South Meadow Circle, Garfield County, Colorado. The - project site is show i on Figure . The purpose of the study was to develop recommendations f r the foundation design. The study was conducted in accordance - with our agreement for geotecla ical engineering services to Joel Ruiz dated April 22, 2016. Hepworth -P wlak Geote hnical Inc., previously performed a preliminary - geotechnical study I or Sun Meai low Estates (formerly Manaus View Subdivision) and presented our findings in a repoit dated March 28, 2000, Job No. 100 169. - A field exploration program consisting of exploratory borings was conducted to obtain - information on the subsurface conditions. Samples of the subsoils obtained during the field exploration were tested in the laboratory to determine their classification, - compressibility ors ell and orb r engineering characteristics. The results of the field exploration and labc ratory testing were analyzed to develop recommendations for foundation types, depths and allowable pressures for the proposed building foundation. This report summar' zes the data Dbtained during this study and presents our conclusions, - design reconimendai ions and other geotechnical engineering considerations based on the proposed constructin and the subsurface conditions encountered. PR OSED CONSTRUCTION - The proposed reside ice will bet o story wood frame construction over a crawlspace and - located between the xploratory borings as shown on Figure 1. Ground floor of the garage will be slab -ca -grade. Grading for the structure is assumed to be relatively minor - with cut depths betty en about 3 to 5 feet. We assume relatively light foundation loadings, typical of t ic proposed type of construction. If building loadings, ocation or ading plans change significantly from those described above, we should be otified to r -evaluate the recommendations contained in this report. Job No. 115 -2 - SITE CONDITIONS Lot 27 is located to he north of outh Meadow Circle, west of South Meadow Drive with - County Road 216 t the north. a ground surface in the building area is gently sloping down to the south. Vegetation C Drisisted of grass, weeds, and brush. A natural drainage located in the weste m part of the property and on the order of 10 feet deep was dry at the time of our field ex loration. IELD EXPLORATION The field exploratio i for the pro ject was conducted on April 27, 2016. Two exploratory borings were drilled at the locati ns shown on Figure 1 to evaluate the subsurface n conditions. The hot ings were ad vanced with 4 -inch diameter continuous flight augers powered by a truck- mounted C -45B drill rig. The borings were logged by a - representative of He pworth-Paw lak Geotechnical, Inc. - Samples of the subs ils were taken with a 2 inch I.D. spoon sampler. The sampler was - driven into the subsoils at various depths with blows from a 140 pound hammer falling 30 inches. This test is imilar to the standard penetration test described by ASTM Method - D-1586. The peneu ition resista cc values we an indication of the relative density or consistency of the st bsoils. Depais at which the samples were taken and the penetration - resistance values are shown on the Logs of Exploratory Borings, Figure 2. The samples were returned to our laboratory f Dr review by the project engineer and testing. SUBSURFACE CONDITIONS - Graphic logs of the ubsurface conditions encountered at the site me shown on Figure 2. The subsoils encoun ered, below a minor (about Y: foot) depth of topsoil, consisted of - stiff to very stiff, vei y sandy silt md clay underlain at about 10 feet in Boring 1 by medium dense, silty 3and with gr avel and sandy silt layers that extended down to the - drilled depth of 31 ft et. - 1 Job No. 115 No free water was�ttcountered �tr the borings at the time of drilling and the subsoils were slightly moist BEARING CONDITIONS The soils encountered at the site possess low bearing capacity and are expected to mainly tend to settle if wett d. Spread I 3otings bearing on the natural soils can be used for foundation support provided son ie risk of movement and distress is acceptable to the owner. The risk of movement is primarily from wetting and precautions should be taken to keep the bearing oil dry. The swell potential encountered in one of the samples tested is considered an aroaly and c be neglected in the foundation design. However, the settl-ment/heave po ,tial of the be soils should be further evaluated at the time of construction. Providing several let t of strucmr it fill (reworking of the on-site natural soils) below the footings or use of a I elical pier t3 pe foundation down to dense soils would reduce the risk of foundation moven Lent. Provided below are recommendations for footings bearing on the natural soils. If r!con=cndal ions for bearing on structural fill or for a helical pier type foundation systc m are desired, we should be contacted. DESI N RECOMMENDATIONS FOUNDATIONS Considering the subs irface condii Vons encountered in the exploratory borings, the nature of the proposed coast ruction and i he soils typical of this area, we believe the building can Job No. -3- Laboratory testing erformed o i samples obtained from the borings included natural moisture content at d density, a id percent finer than sand size gradation analyses. Results of swell-consolidat on testing p rformed on relatively undisturbed drive samples of the soils, presented on igures 4 an 15, generally indicate low to moderate compressibility under conditions of loading and wetting. The sample from Boring 1 at 2%x feet showed a low hydro-compres ion potenti 1. The sample from Boring 2 at 5 feet showed a low swell potential who i wetted unc er a constant light surcharge. The laboratory testing is summarized in Tab a 1. No free water was�ttcountered �tr the borings at the time of drilling and the subsoils were slightly moist BEARING CONDITIONS The soils encountered at the site possess low bearing capacity and are expected to mainly tend to settle if wett d. Spread I 3otings bearing on the natural soils can be used for foundation support provided son ie risk of movement and distress is acceptable to the owner. The risk of movement is primarily from wetting and precautions should be taken to keep the bearing oil dry. The swell potential encountered in one of the samples tested is considered an aroaly and c be neglected in the foundation design. However, the settl-ment/heave po ,tial of the be soils should be further evaluated at the time of construction. Providing several let t of strucmr it fill (reworking of the on-site natural soils) below the footings or use of a I elical pier t3 pe foundation down to dense soils would reduce the risk of foundation moven Lent. Provided below are recommendations for footings bearing on the natural soils. If r!con=cndal ions for bearing on structural fill or for a helical pier type foundation systc m are desired, we should be contacted. DESI N RECOMMENDATIONS FOUNDATIONS Considering the subs irface condii Vons encountered in the exploratory borings, the nature of the proposed coast ruction and i he soils typical of this area, we believe the building can Job No. FLOOR SLABS 115 112A -4 - be founded with sp -ead footing bearing on the natural soils with a risk of movement. The risk of movement A mainly fro wetting the bearing soils and precautions should be taken to keep them dry. The design and con struction cri eria presented below should be observed for a spread W footing foundation ystem. 1) Foo 'ngs placed on the undisturbed natural soils should be designed for an allowable bearing pressure of 1,500 psf. Based on experience, we expect inti settlement of footings designed and constructed as discussed in this secti Do will be at out I inch or less. There could be additional differential mov ment of abc or V2 to 1 inch if the bearing soils become wetted depe iding on the depth and extent of the wetting. 2) The i outings sho Id have a minimum width of 18 inches for continuous so walh and 2 feet f 3r isolated pads. 3) Extei for footings and footings beneath unheated areas should be provided with idequate soil cover above their bearing elevation for frost protection. Placement of foundations at least 36 inches below exterior grade is typic dly used in is area. 4) Cont nuous founc ation walls should be heavily reinforced top and bottom to sp local anomalies and better withstand the effects of some diffej ential movement such as by assuming an unsupported length of at least 4 feet. Foundation walls acting as retaining structures should also be de igned tore 'st a lateral earth pressure corresponding to an equivalent fluid nit weight f at least 55 pcf for the on-site soil as backfill. 5) The topsoil and any loose or disturbed soils should be removed and the food g bearing level extended down to the undisturbed natural soils. The subgr ide should then be moistened and compacted. 6) A rep esentative of the geotechnical engineer should observe all footing excav tions prior concrete placement to evaluate bearing conditions. FLOOR SLABS 115 112A -5- The natural on-site s Als, excludi ig topsoil, should be suitable for support of lightly loaded floor slabs o -grade. The re could be slab movement if the subgrade becomes wetted as discussed bove. Prov ding several feet of structural fill below the slabs would act to reduce the risk of floor slal i movement. The settlement/heave potential of the bearing soils and = d for structural fill should be further evaluated at the time of • construction. M To reduce the effect of some differential movement, floor slabs should be separated from all bearing walls and columns with expansion joints which allow unrestrained vertical movement. Floor slab control joints should be used to reduce damage due to shrinkage cracking. The requij ements for j Dint spacing and slab reinforcement should be • established by the dc signer basec on experience and the intended slab use. A minimum 4 inch layer of relatively well grad d sand and gravel, such as road base, should be placed beneath slabs for support. This material should consist of minus 2 inch aggregate with at least 50% retained o i the No. 4 sieve and less than 12% passing the No. 200 sieve. • All fill materials placed for support of floor slabs should be compacted to at least 95% of • maximum standard Proctor density at a moisture content new optimum. Required fill can consist of the onsite oils devoid of vegetation and topsoil. UNDERDRAIN SY TEM • It is our understanding the finished d floor elevation at ground level will be at or above the surrounding grade wid that craw space grade will be shallow, on the order of 3 feet below • existing grade. The fore, a foundation drain system is not required provided surface grading and drainage is properly constructed as recommended below. It has been our • experience in the ar a that local perched groundwater can develop during times of heavy precipitation or seasonal rano££ Frozen ground during spring runoff can create a perched condition. We recut end belo -grade construction, such as retaining walls or deep crawlspace or basen ent, be protf cted from wetting and hydrostatic pressure buildup by • an underdrain and w ffl drain sys em. • • Job No. 115 112A C-.t'9taC h 5) Land caping which -6 - If the finished floc, elevation of the proposed structure has a floor level below the surrounding grade, we should I e contacted to provide recommendations for an underdrain cause I by irrigation. system. All earth claiming stractures should be properly drained. LIMITATIONS SURFACE DRAD AGE This study has been onducted in accordance with generally accepted geotechnical Positive surface dr 'nage is an important aspect of the project to prevent wetting of the bearing soils. The following dr iinage precautions should be observed during construction and maintained at all times Met the residence has been completed: 1) Inun Jation of thE foundation excavations and underslab areas should be avoi ed during c instruction. 2) Exte ior backfill hould be adjusted to near optimum moisture and compacted to at least 95% of the maximum standard Proctor density in pave nent and sla b areas and to at least 90% of the maximum standard Proc or density it landscape areas. 3) The ground surfa a surrounding the exterior of the building should be slopt d to drain at fay from the foundation in all directions. We teem end a mil imum slope of 12 inches in the first 10 feet in unpaved areas and a minin turn slope of 3 inches in the first 10 feet in paved areas. 4) Roof downspouts and drains should discharge well beyond the limits of all 5) Land caping which requires regular heavy irrigation should be located at least 10 feet from foundation walls. Consideration should be given to use of xei 'scape to reduce the potential for wetting of soils below the building cause I by irrigation. LIMITATIONS This study has been onducted in accordance with generally accepted geotechnical engineering principit s and practices in this area at this time. We make no warranty either express or implied. he conclusi ns and recommendations submitted in this report are based upon the data btained fror i the exploratory borings drilled at the locations indicated on Figure 1 the proposed type of construction and our experience in the area. 115 I12A se'x� Steven L. Pawlak P. y r $ _ Reviewed by:�� Daniel E. Hardin, P. . SLP/ksw cc: Wester, Inc. Stephen Kesler (westu@rof.net Job No. 115 112A -7 - Our services do not include dete mining the presence, prevention or possibility of mold or other biological con aminants ( OBC) developing in the future. If the client is concerned about M BC, then a rofessional in this special field of practice should be consulted. Our find ngs include interpolation and extrapolation of the subsurface conditions identifiec at the expl ratory borings and variations in the subsurface conditions may not I iecome evid mit until excavation is performed. If conditions encountered during onstruction appear different from those described in this report, we should be notified so that re-eval uation of the recommendations may be made. This report has been prepared foi the exclusive use by our client for design purposes. We are not responsible r technical interpretations by others of our information. As the project evolves, we hould provide continued consultation and field services during construction to revic w and monitor the implementation of our recommendations, and to verify that the recon endations have been appropriately interpreted. Significant design changes may require additional analysis or modifications to the recommendations presented herein. recommend on-site observation of excavations and foundation bearing strata and to ting of stru total fill by a representative of the geotechnical engineer. Respectfully Submit ed, HEPWORTH - PAV FLAK GEQMLHNICAL, INC. se'x� Steven L. Pawlak P. y r $ _ Reviewed by:�� Daniel E. Hardin, P. . SLP/ksw cc: Wester, Inc. Stephen Kesler (westu@rof.net Job No. 115 112A APPROXIMATE SCALE 1"=50' COUNTY 60AD 216 / C BORING 1 (HP GEOTECH \ JOB NO. 100169 LOT 25 I v v 3/28/2000) OT 27 i / BENS BORING 2 / / I / / I BORING 1 SOUTH MEADOW CIRCLE 0 O 0 D 0 O 116136A I u_I ILOCATION OF EXPLORATORY BORINGS I Figure 1 BORING 1 BORING 2 2 14/12 WC -6,5 =5.6 DD -109 97 -200=44 2 14/12 -4.4 WC=4.6 108 DD=103 `46 -200=50 17/12 4.5 132 112 M 5 10 15 20 25 30 35 Note: Ixplanation o symbols is shown on Figure 3. ech LOGS OF EXPLORATORY BORINGS Figure 2 b LEGEND: ration test (SI ® TOPSOIL; organic sandy silt ind clay, f required to drive the Californi sampler 12 NOTES: SILT AND CLAY (ML -CL); sar dy to very 2. The exploratory boring locations wE plasticity. provided. 3. The exploratory boring elevations w re not meas 4. The exploratory boring locations should be consi SAND (SM); silty to very silty, catered n the explon material types and transitions may it layers. 6, No free water was encountered in t e borings at t _ 7. Laboratory Testing Results: stiff to very stiff, slightly moist, light brown to brown, low to gravelly, medium dense, slightly moist, brown, some sandy silt Relatively undisturbed drives mple; 2 -inch II.D. California liner sample. 13/8 inch I.D. split spoon sample, ASTM -1586, vs of a 140 pound hammer falling 30 inches were 6 with a 4 -inch diameter continuous flight power auger. xoximately by pacing from features shown on the site plan J and the log of exploratory borings are drawn to depth. ed accurate only to the degree implied by the method used. ry boring logs represent the approximate boundaries between time of drilling. Fluctuation in water level may occur with time 116 136A I uc I LEGEND AND NOTES I Figure ■ Drive sample; standard penel ration test (SI 39/12 Drive sample blow count; indi mtes that 39 required to drive the Californi sampler 12 NOTES: 1. The exploratory borings were drillec on April 27, 2. The exploratory boring locations wE re measured provided. 3. The exploratory boring elevations w re not meas 4. The exploratory boring locations should be consi 5. The lines between materials shown n the explon material types and transitions may it a gradual. 6, No free water was encountered in t e borings at t _ 7. Laboratory Testing Results: WC = Water Content (%) DD = Dry Density (pcf) _ -200 = Percent passing No. 200 si 13/8 inch I.D. split spoon sample, ASTM -1586, vs of a 140 pound hammer falling 30 inches were 6 with a 4 -inch diameter continuous flight power auger. xoximately by pacing from features shown on the site plan J and the log of exploratory borings are drawn to depth. ed accurate only to the degree implied by the method used. ry boring logs represent the approximate boundaries between time of drilling. Fluctuation in water level may occur with time 116 136A I uc I LEGEND AND NOTES I Figure Moisture Content = 5.6 percent Dry Density = 97 pcf Sample of: Sandy Silt 0 From: Boring 1 at 2y Feet 2 Compression 4 upon wetting 6 c 0 N m g E E o U 10 12 14 0.1 1.0 10 APEU PRESSURE -ksf 100 116136A [ TION TEST RESULTS I Figure 4 A LIED PRESSURE -ksf 10 100 116136A ~ .ak s� o SWELL -CONSOLIDATION TEST RESULTS Figure 5 Moisture Content = 4.6 percent Dry Density = 103 Oct Sample of: Very Sandy Silty Clay From: Boring 2 at 5 Feet fEppan;lon A LIED PRESSURE -ksf 10 100 116136A ~ .ak s� o SWELL -CONSOLIDATION TEST RESULTS Figure 5 w U C o_ z inF Odz z V U Z J _ N X g Z Q W F a - U_ Z N p UIW- f H a o ¢ X O p a l7 Y O i W m > J 3 www b b W O O = C QQ 3 L Q X W 2 V1 M z� 0 p0� r b V vi Q,W v� �D tj r X a z 2 o vi a b v - s 0 z 2 N 0