HomeMy WebLinkAboutGeotechnical Engineering Investigation 01.21.21:::1+gFtrCTL I THOMPSONWGEOTECHNICAL ENGINEERING INVESTIGATIONTOMASWICK RESIDENCELOS AMtcOS RANCH, LOT 64, FfLtNG 5, PHASE 2GARFiELD COUNTY, GOLORADOPrepared For:JOE AND BETSY TOMASWCKP.O. Box 1594Silverthorne, CO 80498Project No. GS06522.0A0-120January 21,2021234 Cente¡: Drive I Glenwood Springs, Colorado 81601Telephone: 970-945-280S F ax 970-945-741 1
ffiTABLE OF CONTENTSSUMMARY OF CONCLUSIONSstTE coNDn't0NS .,......PROPOSED CONSTRUCTIONSUBSURFACE CONDtTtONS............._..SITE EARTHWORK,..,. .Excavations.Structural Fill .,..........,..Foundation Wall Backfiil.FOUNDATTON ........f irrtrrrrr'r.'¡',.r",'r't1I2î34ob7IIoSLABS-ON-GRADE CONSTRUCT|ON..... ì.r.i..¡..,¡... ¡,.STRUCTURAL FLOORS AND CRAWL SPACESFOUNDATION WALLSSUBSURFACE DRATNAGESURFACE DRAINAGE.,CONCRETECONSTRUCTION OBSERVATIONSSTRUCTURAL ENGINEERING SERVICES ...GEOTECHNICAL RISKLIMITATIONSFIGURE 1-VICINITYMAPFIGURE 2 - AERIAL PHOTOGRAPHFIGURE 3 - PROPOSED BUILDING FOOTPR!NTFIGURE 4 - SUMMARY LOGS OF EXPLORATORY PITSFIGURE 5 _ GRADATION TEST RESULTSF]GURES 6 AND 7 - FOUNDATION WALL DRAIN CONCEPTSTABLE I - SUMMARY OF LABORATORY TESTINGJOE AND BETTY TOMASWICKTOMASWCK RESIDENCEPROJECT NO. cS06522.000-120
ffiSCOPEThis report presents the results of our geotechnical engineering investiga-tion for the Tomaswick Residence proposed on Los Amigos Ranch, Lot 64, Filing5, Phase 2 in Garfield County, Colorado. We conducted this investigation to evalu-ate subsurface conditions at the site ând provide geotechnical engineering recom-mendations for the proposed construction. The scope of our investigation was setforth in our Proposal No. GS 20-0320. Our report was prepared from data devel-oped from our field exploration, laboratory testing, engineering analysis and ourexperience with similar conditions. This report lncludes a description of the súbsur-face conditions observed in the exploratory pits and presents our geotechnicalen-gineering recommendations for design and construction of foundations, floor sys-tems, below-grade walls, and details ínfluenced by the subsoils. We should be pro-vided with architectural plans, as they are developed, so that we can provide ge-otechnicaligeo-structural engineering input. A summary of our conclusions Ís pre-sented below.SUMMARY OF CONCLUSIONS1Subsurface conditions observed in our exploratory pits (Tp-1 andTP-?) excavated at the site consisted of about 3 inches of topsoir and3 feet of sandy çlay, underlain by basalt cobbles and boulders in amatrix of sandy clay and silt to the total explored depth of 10 feet,Densely-nested boulders prevented excavation deeper than 4 feet inTP-2. Free groundwater was notfound in the exploratory pits.we anticipate excavations at th.is site will be more difficurt than usualdue to the dense cobbles and boulders. voids resulting from removarof large boulde¡:s should be filled with densely-compacted, granularstructural fill, Additionally, the large amount of cobbles and bourdersin the natural soil may result in a significant percentage of the exoa-vated soils that are unsuitable for reuse as fill and backfill.We judge footing a foundation is appropriate for the residence. Thefootings should be supported by the undisturbed, cobble and bourdersoil or densely-compacted, granular, structuralfill. We recommend amaximum 4-foot thickness of structural fill below footings.2.JOE AND BETry TOMASWICKTOMASVI¡ICK RESIDENCEPROJECT NO. GSo6522.000-,l2031
ffi4.we expect slab-on-grade construction can be sr-rpported by the un-disturbed, cobble and boulder soil or densely-compacted, granular,structural fill. consolidation settlement of more than 1 inch is likelyfor slabs supported on structural fill thíckness greater than 6 feet.'The residence should be provided with a perimeter foundation drainaround beiow-grade areas. Surface drainage should be designedand constructed to rapidly convey surface water"away from the resi-dence.SITE CONDITIONSThe Tomaswick Residence is proposed on Los Amigos Ranch, Lot 64, Fil-ing 5, Phase 2 in in Garfield County, Colorado. A vicinity map with the location ofthe site is included as Figure 1. The site is an approximately 2-acre, triangular-shaped parcel at the south end of Crescent Place. An aerial photograph is shownon Figure 2. Ground surface in the building envelope generally slopes down to theeast at grades of approximately 10 percent. Steeper slopes are east of the env€-lope. Vegetation on the property consists predominanily of pinyon, Juniper andSage. Several inches of snow was on the ground at the time of our subsurface in-vestigation. A photograph of site conclitions is below.5¡- d'.o ÇJOE AND BETTY TOMASWICKTOMASWCK RESINFNCEPROJECT NO. GS06522.000-1202Trackhoe at TP,2 location
ffiPROPOSED CONSTRUCTIONWe were provided with design development plans for the Tomaswick Resi-dence by slryker/Brown Architecis, P.c. (dated December 10,2020). The resi-dence will be a one-story, wood-framed building with a walkout basement lowerlevel below about 213 ol the main level living area. Crawl space will be below theremaining part of the main levelfloor. An attached garage will be at the north endof the residence. Slab-on-grade floors are expected in the garage and lower levelof the residence. Plans show the main level and lower level floors at elevations7048 feet and 7038 feet, respectively. Patio areas will be constructed at the southside of the building.The site plan indicates maximum foundation exoavation depth of less than 5feet at the uphill (west) side of the building. Struetural fill as thick as 10 feet and Ifeet is pt'oposed below the garage floor and patio slabs, respectively. Typical foun-dation loads for this type of construction are about 1,500 to 3,000 pounds per lín-eal foöt of foundation wall wíth maximum interior column loads of less than 75kips. We should be provided with architectural plâns, as they evolve, so that wecan provide geotech n ical/geo-structu ral engineering input.SITE GEOLOGYAs part of our geotechnical engineering investigation, we reviewed geologicmapping by the Colorado Geological Survey titled, "Geologie Map of the Carbon-dale Quadrangle, Garfield county, colorado", by Kirkham and widmann (dated2008). The mapping indicates the site is an area of sheetwash deposits (Holoceneand late Pleistocene Epochs) underlain by basalt that was deposited by volcanicflows during the Miocene Epoch. The upper rock is fractured and weathered intoboulders and cobbles. These rocks are in a matrix of sheetwash deposits of síltysand and clayey sand, Subsurface conditions encountered in our exploratory pitsare consistent with the geologic mapping.JOE AND BETTY TOMASWICKTOMASWICK RESIOËNCEPROJEçT NO. G306522.000-,t 203
ffiWe also reviewed the GGS mapping, "Collapsible Soils and Evaporite KarstHazards Map of the Roaring Fork River Corridoi, Garfìeld, Eagle and pitkin Coun-ties, Colorado", by Jonathan L. white (dated zo0z). The map indícates the subjectsite is in an a¡'ea of unconsolidated surficial deposits that includes outwash depos-its. These deposits are geologically, recen-t and typically loosely-packed, porousand dry. ln many cases, the soils have a potential collapse when wetted underIoad. Our subsurrace investigation indicates the soils at the subject site are clas!supported by the basalt cobbles and bedrock with outwash materialfilling thevoids between the rocks. We judge the potential for soil collapse ís low at this site.SUBSURFACE CONDITIONSSubsurface conditions at the site were investígated by observing excavationof two exploratory pits (TP-1 and TP-2). The pits were excavated with a trackhoeatthe approximate locations shown on Figures 2and 3. Exploratoryexcavationoperations were directed by our engineer, who logged subsurface conditions en-countered and obtained samples of the excavated soils. Graphic logs of the soilsencountered in our explorqtory pits are shown on Figuro 4.Subsurface conditions observed in our exploratory pits consisted of about 3inches of topsoil and approximately 3 feet of sandy clay, underlain by basalt boul-ders, cobbles and gravel in a matrix of sandy clay and silt to the total exploreddepth of 10 feet. Densely-nested boulders prevented excavation deeper than 4feet in TP.2. Free groundwater was not found in our exploratory pits at the time ofexcavation. The pits were backfilled immediately after excavation operations werecompleted. Photographs of conditions found in our pits are below.JOE AND BETTY TOMASWICKTOII'IASWCK RESIDENCEPRoJEcr No. csoô522.000¡204
ffiConditions exposed in TP-1JOE AND BETTYTOMASW|ÖKTOMASWCK RESIDENCEPROJECT NO. GS0652¿000-1205Soils excavated from TP.2
ffiSamples of the soils obtained fro.m our exploratory pits were returned to olrrlaboratory for pertinent testing. One sample of the soil selected for gradation anal-ysis contained 41 percent gravel, 43 percent sand, and 16 percent silt and clay(passing the No. 200 sieve). Gradation tests are not inclusive of rocks larger than5 inches. We judge the soils are compCIsed predomínantl¡t of cobbles and boul.ders. Gradation test results are shown on Figure 5. Engineering index testing ontwo samples of the matrix soil indicated low plasticity with liquld limits of 41 and 42percent and plasticity indices of 14 and 18 percent, .Based qur laboratory testíngand our expêrience at nearby sites, the matrix soil has low to moderate potentialfor expansion when wetted. One sample of the soil teeted had a wator-soluble sul-fate content of 0.0 percent" Laboratory test results are summarized on Table l.SITE EARTHWORKThe site plan indicates maximum foundation excavation depth of less than 5feet at the uphill (west) side of the building. Structural fill as thick as 10 feet and Ifeet is proposed below the garage floor and patio slabs, respectively. We recom-mend a maximum 4-foot thickness of structuralfill below footings. Consolidationsettlement of more than '1 inch is likely for slabs supported on structural fill thick-ness greater than 6 feet.ExcavationsWe anticipate excavations at thís site for the building and underground utíli-ties will be more difficult than usual due to the dense cobbles and boulders.Heavy-duty excavation equipment will be necessary. Excavations may require orbe most efficiently made with blasting to loosen the soils. Large boulders shouldbe expected. Voids below the building resulting from removal of large bouldersshould be filled with densely-compacted, granular, structuralfill in accordance withrecommendations in the Structural Fill section.JOE AND BETTY TOMASWCKTOMASWICK RË$IDENCEPROJECT NO. GSo6622.000-1206
ffiFrom a "trench" safety standpoint, sides of excavations need to be slopedor braced to meet local, state and federal çafety regulations. The soils encoun-tered in the excavation to construct the residence will likely classify as Type B andType C soils based on OSHA standards governing excavations, Temporary slopesdeeper than 5 feet that are not retained should be no steeper than 1 to 1 (horizon-talto vertical) in Type B soils and 1.5 to 1 in Type C soils. Contractors are respon*sible for determining the actual OSHA soil type when excavations are made andfor maintaining safe excavations.Free groundwater was not found in our exploratory pits. We do not antici-pate excavations for foundations or utilities will penetrate groundwater, We recom-mend against excavation during snowmelt. Excavations should be sloped to agravity díscharge or to a temporary surnp where water from precipitation andsnowmelt can be removed by pumping, The ground surrounding the excavationsshould be sloped to direct runoff away from the excavations.Structural FillClose control will be required for structural fill to raise grades for the garageand patio and/or to fill voids resulting from removal of large boulders. Areas thatreceive fill should be stripped of vegetation, organic soils and debris. Structural fillbelow the garage and patios should consist of an aggregate base course or pit runmaterial with a maximum rock size of 3 inches. The on-site soils free of rockslarger than about 6 inches, organics, and debris can be used as fill in landscapeareas.Structural fill should be placed in loose lifts of 8 inches thick or less andmoisture-conditioned to within 2 percent of optimum moisture eontent. Structuralfill should be compacted to at least g8 percent of standard Proctor (ASTM D 69S)maximum dry density. Moisture content and densÍty of structural fill should beJOE AND BETTY TOMASWCKTOMASW|CK RESIDENCË7PROJECT NO. GS06522.000-120
ffichecked by a representative of our firm during placement. Observation of the com-paction procedure is necessary. Testing without observation can lead to undesira=ble performance.Foundation Wall BackfillProper placement and eompaction of foundation backfill is important to re.duce infiltration of surfâce water and settlement of backfill. Backfill compaction isespecially important in areas that will support exterior slabs-on-grade, such asdriveways and patios. Backfill that wíll support tlrese shuctures should conslst ofän aggreEate base course or pit run materialwith a maximum rock size of 3inches. The natural soils can be used as backfill in areas thât will not supportstructures, provided they are free of rocks larger than 4-inches in diameter, organ-ics, and debris.Backfill should be placed in loose lifts of approximately 10 inches thick orless, moisture-conditioned to within 2 percent of optimum moisture content andcompacted. Thickness of lifts will likely need to be about 6 inches if there are smallconfined areas of backfill, which limit the size and weight of compaction equip-ment. Foundation backfill soils below patio and driveway slabs should be com-pacted to at least gB percent of maximum standard proctor (ASTM D 6gg) drydensity. Backfill soils in landscape areas.should be compacted io at least g5 per-cent of maximum standard Proctor (ASTM D 69S) dry density. Moisture contentand density of the backfillshould be checked during placement by a representativeof our firm. Observation of the compaction procedure is necessary.FOUNDATIONBased on our subsurface information from the site, we judge a footing foun-dation is appropriate for the residence. The footings can be supported direcly onJOE AND BETTY TOMAEWCKTOMASWICK RË.SIÞENCEPROJEcT NO. GS06522,000-1 20I
ffithe undisturbed, cobble and boulder soil or densely-compacted, granular, struc-tural fill. Plans indicate structural fill as thick as 10 feet is proposed below the gar-age floor elevation. We recommend a maximum 4-foot thickness of structur,al fillbelow footings to reduce potential for consolidation settlement. Voids resultingfrom removal of large boulders should be filled with granular, structural fill in ac-cordance with recornmendations in the Structural Fill section. Recommended de-sign and construction criteria for footings are presented below.1The footing foundation should be supble and boulder soil or a maximum 4-pacted, granular, structural fill.ported by the undisturbed, cob-foot thickness of densely-com-23.Footings on the undisturbed, coþble and boulder soil or densely-compacted, granular, structuralfill should be designed for a maxi-mum allowable soilressure of 3000continuous wall footings shouid have a minimum width of at reast 16inches, Foundations for isolated columns should have minimurr¡ -mensions of 24 inches by 24 inches. Larger sizes may be required,depending upon foundation loads.Grade beams and foundation walls should be well-reinforced, topand bottom, to span undisclosed ioose or soft soil pockets. We rec-ommend rêinforcement sufficient to span an unsupported distance ofat least 10 feet.The soils beneath exterior footings should be protected from freez-ing. We recommend the bottom of footings be constructed at a depthof at leastS6-ineh.es below finished exterior grades. The GarfieldCounty building department should be consulted regarding requiredfrost protection depth.SLABS.ON.GRADE CONSTRUCTIONSlab-on-grade floors are expected in the garage and lower level of the resi-dence. Structural fill as thick as 10 feet and I feet is proposed below the garagefloor and patio slabs, respectively. Consolidation settlement of more than 1 inch islikely for slabs supported on struc-tural fill thickness greater than 6 feet. A 1 to Z-foot thickness of flowable fill (lean mix concrete) can be utilized for the upper partJOEANDBETTYTOMASWICK ^ToMAswrcK RESTDENcE YPROJECT NO, c506522.000-{204.5.
ffiof the structural fill to reduce consolidation settlement potential. We judge slab-on-grade construction can be supported by the undisturbed, cobble and boulder soilwith low risk of difierential movement. The structuralfill below slabs should beplaced in accordance with recommêRdations in the Structural Fill section. We rec-ommehd the following precautions for slab-on-grade construction at this site.slabs should be separated from exterÍor warls and interíor bearingmembers with slip joints which allow free verticar movement of théslabs.The use of underslab plumbing should be rninimized. unclerslahplumbing shouid be pressure tested for leaks before the slabs areconstrucled. Flumbing and utilities which pass through slabs shouldbe isolated from the slabs with sleeves and provided*with flexiblecouplings to slab supported appliances.Exterior concrete flatwork should be isolated from the residence,These slabs should be well-reinforced to function as independentunits.1234Frequent controljoints should be provided, in accordance with Amer-ican concrete lnstitute (ACl) recommendations, to reduce problemsassociated with shrinkage and curling.STRUCTURAL FLOORS AND CRAWL SPACESWe understand that crawl spaces will be constructed below parts of themain levelfloors, Where structurally-supported floors are installed over a crawlspace, the required air space depends on the materials used to construct the floor.Building codes require a clear space of 18 inches between exposed earth and un-treated wood floor components. For non-organio systems, we recommend a mini-mum clear space of 18 ínches. Where structurally supported floors are used, utilityconnections, including water, gas, air duct, and exhaust stack connections to floor.supported appliances, should be capable of absorbing some deflection of the floor.JOE AND BETTY TOMASWCKTOMA$WCK RE8IOENCEPROJECT NO. GS06522.000-12010
ffiControl of humidity in crawl spaces is important for indoor air quality andperformance of wood floor systems. We believe the best current practices to con-trol humidity involve the use of a vapor retarder or vapor barrier (10 mil minimum)placed on the soils. The vapor retarder/barrier should be sealed at joints and at-tached to concrete foundation elements. An active ventilation system controlled bya humidistat is beneficial.FOUNDATION WALLSFoundation walls which extend below-gr:ade should be designed for lateralearth pressures where backfill is not present to about the same extent on bothsides of the wall, such as ín basement and crawl space areas. Many factors affectthe values of the design lateral earth pressure. These factors include, but are notlimited to, the type, compaction, slope and drainage of the backfíll, and the rigídityof the wall against rotation and deflection.For a very rigid wallwhere negligible or very little deflection will occur, an"at-rest" lateral earth pressure should be used in design. For walls which can de-flect or rotate 0.5 to 1 percent of wall height (depending upon the backfill types),lower "active" lateral earth pressures are appropríate. Our experience indicatestypical below-grade walls in residences can deflect or rotate slightly under normaldesign loads, and that this deflection results in satisfactory wall performance.Thus, the earth pressures on the walls wíll likely be between the "active" and "at*rest" conditions.For backfill conforming to recommendations in the Foundation Wall Backfillsectíon that is not saturated, we recommend design of below-grade walls using anequivalent fluid density of at least 45 pcf for this site. This equivalent density doesnot include allowances for sloping backfill, surcharges or hydrostatic pressures.The recommended equivalent density assumes deflection; some minor cracking ofwalls may occur. lf very little wall deflection ís desired, a higher equivalent fluidJoEAND BErIYToMASWicKTOMASWIqK RES.IQENCEPROJECT NO. GS06s22.000-12011
ffidensity approaching the at-rest condition using a value of 60 psf may be appropri-ate for design.SUBSURFACE DRAINAGEWater from surlace precipitatio¡, snowmelt, and irrigation frequqn¡y flowsthrough relatívely permeable backfill placed adjacent to a residence and collectson the surface of less permeable soils occurring at the bottom of foundatiCIn exca-vations' This process €n cause wet or moist conditions in below-grade areas,such as hasement ancl crawl spaces, after construotion.Wê recommend an exterior foundatíon wall drain be installed around theperimeter of the basement and crawl space areas in the residence. The exteriorfoundation draín should conçist of 4-inch diameter, slottêd, PVC pipe encased infree=draining gravel. A prefabricated drainage composite should be placed adja-cent to foundation walls. Care should be taken during backfill operations to preventdamage to drainage composites. The drain should discharge via a positive gravityoutlet, or lead to a sump pit where water can be removed by pLrmping. Gravity out-lets should not be susceptible to clogging or freezing, lnstallation of clean-outsalong the drainpipes is recommended. The foundation wall drain concepts areshown on Figures 6 and 7.SURFACE DRAINAGESurface drainage is critícal to the performance of foundations, floor slabs,and concrete flatwork. Surface drainage should be designed to provicle rapicl run-off of surface water away from the residence. Proper surface drainage and irriga-tion practices can help control the amount of surface wäter that penetrates to foun-dation levels and contributes to settlement or heavo of soils and bedrock that sup-port foundations and slabs-on-grade. Positive drainage âway from the foundationJOE AND BETTY TOMASWICKTOMASWICK RESIDENCEPROJECT NO. cS06522.000-120t2
ffiand avoidance of it't'igation near the foundation also help to avoid excessive wet-ting of backfill soils, which can lead to increased backfill settlement and possibly tohigher lateral earth pressures, due to increased weight and reduced strength ofthe backfill. We recommend the following precautions.The ground surtace surrounding the exterior of the residence shouldbe sloped to drâin away from the building in all directions. We recom-mend â minimum constructed slope öf at least 12 inches in the first10 feet (10 percent) in landscaped areas around the residence,where practical.Backfill around the foundation walls should be moistened and com-pacted pursuant to recommendations in the Foundation wall Backfillsection.The residence should be provided with roof gutters and downspouts.Roof downspouts should discharge well beyond the limits of all back-fill. Splash blocks and/or extensions should be provided at all down,spouts so water discharges onto the ground beyond the backfill. Wegenerally recommend against burial of downspout discharge. Whereit is necessary to bury downspout discharge, solid, rigid pipe shouldbe used, and the pipe should slope to an open gravity outlet.ln'igation should be limited to the minimum amount sufficient to main-tain vegetatíon; application of more water will increase likelihood ofslab and foundation movements. Plants placed close to foundationwalls should be limited to those with low moisture requirements. lrri-gated grass should not be located withín 5 feei of the foundation.Sprinklers should not discharge within 5 feet of foundations. Plasticsheetíng should not be placed beneath landscaped areas adjacent tofoundation walls or grade beams. Geotextile fabric will inhibit weedgrowth yet still allow natural evaporation to occur.GONCRETEConcrete in contact with soil can be subject to sulfate attack. We measureda water-soluble sulfate concentration of 0.0 percent in one sample of the soil fromthe site (see Table l). Forthis levelof sulfate concentration, ACI 332-08, Code Re-quirements for Residential Concrefe, indicates there are no special requirementsfor sulfate resistance.1234.JOE AND BETTY TOMASW¡CKTOMASWCK RESIDENCEPROJECT NO. GS06522.000-12013
ffiFln our experience, superficial damage may occur to the exposed surfaces ofhighly-permeable concrete, even though sulfate levels are relatively low. To con-trol this rísk and to resist freeze{haw deterioration, the water-to-cementitious ma-terials ratio should not exceed 0,50 for concrete in contact with soils that are likelyto stay moist due to surface drainage or high-water tables. Concrete should have atotal air content of 6% +l- 1.5o/o. We recommend all foundation walls and gradebeams in contact with the subsoils be damp-proofed,CONSTRUCTION OBSERVATIONSWe reçommend that CTL I Thompson, lnc. be retained to provide construc-tion observation and materials testing services for the project. This would allow usthe opportuníty to,verify whether soil condítions are consistent with those foundduring this investigation. lf others perform these observations, they must acceptresponsibility to judge whether the recommendations in this report remain appro-priate. lt is also beneficial to projects, from economic and practical standpoints,when there is continuity between engineering consultation and the constructionobservation and materials testing phases.STRUGTURAL ENGINEERING SERVICESCTL I Thompson, lnc.is a full-service geotechnical, structural, materials,and environmental engineering firm. Our services include preparation of structuralframing and foundation plans. We can also design temporary and permanent earthretentíon systems. Based on our experience, crl I Thompson, lnc. lypically pro_vides value to projects from schedule and economic standpoints, due to our com-bined expertise and experience with geotechnical, structural, and materials engi-neering. We can provide a proposal for structural engineering servíces, if re-quested.JOE AND BETTY IOM/\ÊWCKTOMAÊWICK REôIDEÑCEPROJECT NO. cS06522.000-l20t4
ffiGEOTECHNICAL RISKThe concept of rísk is an important aspect of any geotechnical evaluation.The primary reason for.this is that the analytical methods used to develop ge-otechnical recommendations ds not comprise an exaot science. The analyticaltools which geotechnical engineers use are generally empirical and must be tem-pered by engineering judgment and experience. Therefore, the solutions or reoom-mendations presented in any geotechnícal evaluation should not be consideredrisk-free and, more importantly, are not a guarantee that the interaction betweenthe soils and the proposed structure will result in performance as desired or in-tended. The engineering recommendations presented in the preceding sectionsconstitute our estimate of those measures necessary to help the building performsatisfactorily.This report has been prepared for the exclusive use of the client for the pur-pose of providing geotechnícal engineering design and construction criteria for theproposed residence. The information, conclusions, and recommendations pre-sented herein are based upon consideration of many factors including, but not lim-ited to, the type of structures proposed, the geologic setting, and the subsurfaceconditions encountered. The conclusions and recommendations contained in thereport are not valid for use by others. Standards of practice continuously change inthe area of geotechnical engineering. The recommendations provided in this reportare appropriate for about three years. lf the proposed project is not constructedwithin three years, we should be contacted to determine if we should update thisreport.LIMITATIONSThe exploratory pits provide a reasonable characterization of subsurfaceconditions at the site, Variations in the subsurface conditions not indicated by thepits will occur. We should be provided with architectural plans, as they evolve, soJOE AND BETIY TOMASWICKTOMASW¡CK RESIDENCEPROJECT NO. GS06522.000-{20't5
ffiwe can providê geotechniçal/geo-structural engineering input.This investigation was conducted in a manner consistent with that level ofcare and skill ordinaiíly exercised'by engineering geologists and geotechnicalen-gineers currently pracficing under sirnilar conditions in the locality of this project.No other waranty, express or implied, is made. lf we can be of further service indiscussing the contents of this report, please call.fitcTL I THOMPSON, lNC.þf Fn^Reviewed by:D. KeDivisionRyan W. DeMars, Ë.1.7Staff EngineerRWD;JDK:abrJOE AND BETTY TOMASWCKIUMASWICK RESIÞENCËPROJECT NO. cs0652z;000-i20?-13gãs8 CIl6
ffio1000 2000NOTE:Sç¡t¡: 1. - 2ooo'JOE ÄND BETSY TOIVIÁSWICKTOlVtASvríCK nE8ÞENCESATELLITE IMAGE FROM GOOGLE FÁRTH(DATED JUNE 2017)VicfnityPROJEC'T NO. cSO65 22,OOO-1 20MapFls. 1
LEGEND:TP_,I APPROXIMATE LOCATION OFI EXPLoRAToRY PITAPPROXIMATE PROPERTYBOUNDARYNOTE:ffi26 50scALÊ i'= 50'SATELLITE IMAGE FROM GOOGLE EARTIT(DATED JUNE 2017)TP_2TP_1JOE ANN RFTSY TOÍ\NASWIGKTOIIII.AEWþK FESICIENOEPROJECT NO. cSO65 22.OOO-1 20AerialPhotogräphFlg. 2
ffiLEGEND:TP-1 APPROXIMATE LOCAT¡ON OFr EXPLoRAToRY PITNOTE:o2550rlSCALEI l" * 50'd¡ i*^\ñBASE DRAWING FROMSTRYI(ER/BROWN ARCHTTECTS, PC'). :'t."rL-'í.', :llIatà',OIrP*28,t,'oJOEAND BETSYTOMASW¡CKTOMAAwtcl( FESIOËNCEProposed BuildingFootprint Hg. gìt:,:-'rPROJECT NO. GSO6522.OOO-1 20
ffiTP-1El, 7039TP-2Et. 7031LEGEND:7,0407,0357,0307,A257,0207,04ó7,0357,030w¡-tu4JltTQPSOIL SAND, CLAYEY, GRAVËI.oRGAN|CS, MOtsT, DARK BROWNT RUSI.CLAY, SANDY,. GRAVEL. SOFT TO MEDIUMSTIFF, MOIST, LIGHT BROWN, RUST,wHfrE. (cL, SC)BASALT COBBLES AND BOULDERS,GRAVEL, SANDY CLAY AND SILT MATRIX,DENSE, SLIGHTLY MOIST, BROWN, GRAY,CALCAREOUS,INDICATES BULK SAMPLE FROM EXCAVATED SOILS.zoËlrJJulFTPRACTIC¿L REFUSAL ON BOULDERS,SYMBOLS ABOVETHE BOTTOM OF PITSINDICATE THE PIT WAS MOVED TO EXCAVATEDEEPER,7,425NOTES:7,O201, EXPLORATORYPITSWEREEXCAVATEDWITH ATRACKHOE ON DECEMBER 23,2020, PITS WERÈ BACKFILLEDIMMEDIATELY AFTER EXPLORATORYEXCAVATION OPËRATIONS WERECOMPLETED.2. GROUÑDWATER WAS NOT FOUND IN OUREXPLORATORY PITS AT THE TIME OFËXCAVATION.3. LOCATIONS OF EXPLORATORY PITS AREAPPROXIMATE. ELEVATIONS WEREINTERPOI-ATED FROM GROUND SURFACECONTOURS SHOWN ON FIGURE 3.4. THESELOGSARESUBJECTTOTHEEXPLANATIONS, LIMITATIONS ANDCONCLUSIONS CONTAINED IN THISREPORT.9unlm ary Logs of,e¡gloratóryFIG.4{QE AND BETSY TOMASWICKTOMASWIOK RESIDENCfPROJECT NO. cs06s22.000-120
ffiCOBBLËScoARsËFINECOARSEMEDIUMFINESANDScLÂY (PI-ASTiC) To 6rLT (NON-PLAST|C)60MlN.19MtN. 4MtN. 1 MtN. .200 .100 .50.40 .30 '16 .J0 .8 .4 3t8, 3t4" Iyr' 3" 5"6" 8"-------l-*_t--+-_-l------l----l.-----.----t--------+-----------}-ê_-t.--...---l---------f--------...|---ufidt-zu(Jc]{,añıø160¡-z850cul[40127 200'152010203025 HR.45 MtN.2,0 238 4.76 S.52 19-1 !ô.1 76,20l0100s080OIAMETER OF PARTICLE IN MILLIMÊTERSREAÞINGS507080901007 HR.l5 MtÑ,.001 a.ooz .00s ,009 ,019 .037 .074 ,149 .291Ð.42,59QSomple ofFrom,gAl!p, _c!4yEY(sq)l?:1 Ar B:e rEETGRAVEL 41 %slLT & oLAV 16 YoPLASTICIÍY INDEX '-SANDLIOUID LIMIT43%-/0%COARSE I COBBLËSFINEfuIEDIUM I COAR$EFINEGRAVEI-SANOScLÀY (PLAST|C) TO S|LT (NON.PL.ASïC)60 MlN, 19 MtN. 4 MrN. 1 MtN, .200 "100 '50 .40 .30 .1ı *10 i8 .4.001 0.002 .005 .009 .01e .037 .074 .149 .2570.42.590 1.19 2.0 2,38tt"i__l--.--.:-----l--{|o70zøøf60F23s0út[40U.S; SIANDARDINDIAMETER0102030t-zIoú.U&801009.52 19.1 36.1 76.2 127 52200901001020304050OU70CLEAR SOUARE OPENINGS3/8' 3t4" 1v," 3" 5'6;25 HR. 7 HR.4s MtN. 15 MtN-Somple ofFromJOE AND BETSY TOMASWICKTOMASWCK RESIDENCEPROJECT NO. cS06522.000-1 20GRAVELSILT & CL.AY .PLASTICITY INDEX% SAND% LIOUID LIMIî%o/%GradationTest ResultsFIG.5
ffiI.sgSLOfEPEROSHAkxnDRAIT'IACEcoMPosm(MTRADRA|N 6000oR EauvAtrM)2-3'.FROMFOOTNCs ens¡rEn)BETOIY-GRADE WAII-SUP JOT'TTF@TTNG OR PADATIACH PLqSNCTO FOUNDATIONcoì/ERGRAVETEffNRE WIDTH4ON OR{qE 4\¡D BETSY TOMASWICKTBMASWCI( BESIDÊNCËPROJECT NO. csoö522.ooo_1 20FoundationWall DrainConceptB'MtNtMUtOR BEYOND1:l SLOPEBOTÍOM OF(ryHlcnannf-tNcH DtArrEtER PERFORATED RtctD DRA¡N ptpETltE ptpE sHoutD se pLAcED ñ lrnei¡öir'úmiô_g_roîE gf Ar rEAsr t/8-tNcH DRop pERFOOT OF DRAIN.ENCáSE PIPE IN 1/2'TO 1-1/2'WASHEDGRAVEL ÞfiEND CRAVEL UTUN¡U.Y rO TOOMTC¡{!q_ôr_!qtsr v2 H$ct{t oF FoorNG. FttrElrnRE TRENCH wtnr cRnrm_NOTEUEJO¡gII Of TIJE DR{!-T[oVLD BE AT Lqg*r ? ilCH6 BEI.OTY BOTTOM OFIggTr[G,ôr r]rE HroHESr._porNr nno sbÉÊ þryñÉö-ïiln-pııirnÆ cRAvfiyounEr oR To A suMp wHERE WATER cm,¡-eE ñEüin/ED'8,r"'p'uiËrxc.Flg.6
ffiI'€NOTEDRAIN SHOULD BE AT LEASÍ 2 INCHESBELOW BOTÍOM OF FOOTING AT THEHIGHE T FOhfT AND SLOPE DOITT{WARDTO A POSÍITVE GRAVÍTY OUTr"Er OR TOA SUMP WHERE WATER CAI.I BEREMOI/ED BT PUMPING.SLOPEENNREr cR wL sPAaeJPEROSHAMlMonru¡¡ c2o0NOR EQUIVAT.E¡TTATTACH PLASIICTO FOUNDATIONFROMFOOANeF GRF¡rER)4-INCH DNilEfEN PERFORATED DRA¡N PIPE TTIEPIPE SHOUI.D BE PTACED N A IRB{CH WT}I AslopE 0F AT tEASr 1/8-|NCH DROP pER FoOTOF DRAIN.@VERGRAVELFOOTNG OR PADïuD st-AB'oRBARRIER8' MINIMUMOR BEYONDt:l SLOPEBOTTOI' OFCI/HTcHEVERJOE AND BETSYTOMASW|CKTOMAI$JI'ICK REêIDENêEFoundationWall DrainGonceptSTBUCruRAL FLOORPROJECT NO. GSO6522.OOO-120Flg.7
TABLE ISUMMARY OF LABORATORY TESTINGPROJECT NO. cS06522.000-120ffi7P-2TP..1TP-1EXPLORATORYPIT3-48-93-4DEPTH(FEET)MOISTURËCONTENT(%\DRYDENSITY(PCF}IIII4241LIQUIDLIMIT(o/o\ATTERBERG LIMITS1814FLASTICITYINDÐ((%\0.00SOLUBLESULFATES(%\41PERCENTGRAVEL(/oJI43PERCENTSAND(%\ô816NO.200SIEVEDESCRIPTIONPage 1 of 1