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HomeMy WebLinkAboutSubsoil Study for Foundation Design 03.20.2021TCL Zan #n È î-52/Colleen Wirth From: Sent: To: Cc: Subject: Colleen Wirlh Thursday, September 2,2021 10:06 AM wrw3 @hotm ai l.com; stu ca rch @com cast.net; j d olezal @ctlthom pson.com don.hecker@comcast.net; Andy Schwal ler BLRE-08-21 -7061 - Hecker Residence, 131 River Glen Rd, Lot 3, Flg 5 Aspen Glen BLRE-O8-ZL-7A61 - Hecker Residence, 13L River Glen Rd, Lot 3, Flg 5 Aspen Glen Courtesy message for Hecker Residence Project Team: l'm now starting the structural review for the Hecker residence (at address above). Could someone please email me a copy of CTL Thompson's soils report Project No GS06553.000-120, dated March 30 202I? I would like a copy to place in our building file record, and to have the opportunity to read through it to satisfy a subdivision plat note. Thanks in advance for your response, emails can be directed to cwirth@garfíeld-county.com. Have a good day! Colleen Wirth Plans Examiner Garfield County Building Divísion 108 8th Street, Suite 401 Glenwood Springs, CO 81601 cwirth(ôsa ntv.com office (970) 945-1377 ext. L6L0 trF CTL I THOMPSONW GEOTECHNICAL ENGINEERING INVESTIGATION HECKER RESIDENCE (A.K.A. AS'EN GLEN .LUB o*o ulrtloï:51'ffå=,Tåi GARFIELD COUNTY, COLORADO Prepared For: DON HECKER 300 Wulfsohn Road, Unit 8313 Glenwood Springs, CO 81601 Project No. GS06553.000-'1 20 March 30,2021 ffi TABLE OF CONTENTS scoPE........ SUMMARY OF CONCLUSIONS,... SITE CONDITIONS PROPOSED CONSTRUCTION GEOLOGY AND GEOLOGIC HAZARDS. SUBSURFACE CONDtTtONS................... SITE EARTI.iWORK........ Excavations Subexcavation and Structural F¡||........... Foundation Wall Backfill FOUNDAT|ON ................. Footings...... Reinforced Concrete Mat Foundation .... SLAB.ON-GRADE CONSTRUCTION ...,.,. CRAWL SPACE CONSTRUCTION........... FOUNDATION WALLS suBsuRFAc E DRATNAGË....................... SURFACE DRAINAGE coNcRETE...... CONSTRUCTION OBSERVATIONS .......... STRUCTU RAL ENGINEERING SERVICES GEOTECHNICAL RISK LtMtTATIONS ................. FIGURE 1_VICINITYMAP FIGURE 2 - AERIAL PHOTOGRAPH FIGURE 3 _ SUMMARY LOGS OF ËXPLORATORY PITS FIGURES 4 AND 5 _ GRADATION TEST RESULTS FIGURE 6 - FOUNDATION WAIL DRAIN CONCEPT TABLE I * SUMMARY OF LABORATORY TËS]"ING DON HECKER HECKER RESIDENCE PROJECT NO. GS06553.000-l 20 .....1 .....1 .....2 ã..... ù ..... 3 .....5 ..... o ,..'.6 '',',7 .....7 . ...8 ..... I .... I ...10 ,..11 ...12 ...13 ...13 .. 14 ...15 ...15 ...15 4ê,.. r(J ffi SCOPE CTL lThompson, lnc. has completed a geotechnical engineering investi- gation for the Hecker Residence proposed at 131 River Glen Road (a.k.a. Aspen Glen Club Villas, Filing 5, Lot 3) in Garfield County, Colorado. We conducted this investigation to evaluate subsurface conditions at the site and provide geotech- nical engineering recommendations for the proposed construction. The scope of our investigation was set forth in our Proposal No. 21-0143. Our report was pre- pared from data developed from our field exploration, laboratory testing, engi- neering analysis, and our experience with similar conditions. This report includes a description of the subsurface conditions observed in our exploratory pits and presents geotechnical engineering recommendations for design and construction of the building, floor system, below-grade walls, subsurface drainage, and details influenced by the subsoils. A summary of our conclusions is below. SUMMARY OF CONCLUSIONS Subsoils encountered in our exploratory pits excavated at the site consisted of about 1 lo 2 feet of topsoil and fill over 3 to 9 feet of natural silty sand and gravel, underlain by silty gravel and cobbles to the maximum explored depth of 1 1.5 feet. Groundwater was not found in our exploratory pits. Based on geologic mapping and our engineering experience, the silty sand and gravel soil has potentialfor moderate to high amounts of consolidation when wetted under building loads. We judge the residence can be constructed with a footing foundation with a slab-on-grade garage floor, provided the soils below footings and slabs are sub-excavated to a depth of at least 3 feet and re- placed as densely-compacted, structural fill. An alternative to allow construction directly on the undisturbed soils would be a reinforced concrete mat fou nd ation/floor system. A foundation wall drain should be constructed around the perimeter of the crawl space to mitigate water that infiltrates backfill soils ad- jacent to the residence. Surface grading should be designed and constructed to rapidly convey surface water away from the building. 1 2 3 DON HECKER HECKER RESIDENCE PROJECT NO. GSo6553.000-120 1 ffi SITE CONDITIONS The Hecker Residence is planned at 131 River Glen Road (a.k.a. Aspen Glen club villas, Filing 5, Lot 3) in Garfield county, colorado. A vicinity map with the location of the site is included as Figure 1 . Lot 3 is an approximately 0.51- acre parcel bordered by River Glen Road at the east and golf course property to the northwest, Existing residences are on the lots surrounding the pr-operty. An aerial photograph of the site is shown on Figure 2. No buildings or structures were present on the lot at the time of our subsurface investigation. Historic photo- graphs indicate buildings were previously located on the site, and appear to have been deconstructed. Ground sudace on the site appears to generally slope gen- tly down to the north at grades less than b percent. vegetation on the property consists of sparse grasses and weeds. A mature cottonwood is to the south. A photograph of the site at the time of our subsurface investigation is below. DON HECKER HECKER RESIDENCE PROJECT NO. GS06553.000-l 20 2 Looking east across the site ffi PROPOSED CONSTRUCTION Architectural plans for the Hecker Residence were not developed at the time of our geotechnical engineering investigation. The residence will likely be a two-story, wood-frame building with an attached garage. The main level floor will be structurally-supported by the foundation with a crawl space below the floor. A slab-on-grade floor is expected in the garage. Excavation depths of about 3 to 4 feet are expected to attain proposed foundation elevations, Additional excavation of at least 3 feet will be required to accomplish the recommended subexcavation and recompaction process below footings and slabs. We expect perimeter foun- dation loads between 1,000 and 3,000 pounds per linear foot and maximum inte- rior column loads of less than 50 kips. We should be provided with architectural plans, as they are developed so that we can provide geotechnical/geo-structural engineering input. GEOLOGY AND GEOLOGIC HAZARDS We reviewed the geologic map by the Colorado Geology Survey (CGS), titled, "Geologic Map of ihe Cattle Creek Quadrangle, Garfield County, Colo- rado", by Kirkham, Streufert, Hemborg, and Stelling (dated 2014). The area of the subject property is on a mapped debris flow feature. The overburden soils consist of younger debris flow deposits of the Holocene Epoch. The silty sand and gravel soil found in our exploratory pits is consistent with the description of the debris flow deposits. Due to the depositional method, the debris flow deposits have not been subject to significant geologic loads. These soils are prone to con- solidation when wetted under building loads. We judge the silty sand and gravel soil (i.e., debris flow deposits) has potential for moderate to high amounts of con- solidation when wetted under building loads. The deeper silty gravel and cobbles found in our exploratory pits appears to be underlying terrace alluvium deposits that are associated with the Roaring DON HECKER HECKER RESIDENCE PROJECT NO. GS065s3.000-120 3 ffi Fork River. The alluvium has relatively low potentialfor consolidation as com- pared to the debris flow deposits. The overburden soils are underlain at depth by bedrock of the Eagle Valley Evaporite formation. We also reviewed the CGS map "Collapsible Soils and Evaporite Karst Hazard Map of the Roaring Fork Valley, Garfield, Pitkin and Eagle Counties", by Jonathan L. White (elated 2002,\. The surficia! soils at the site are mapped as un- consolidated, which possess potentialfor hydrocompaction when wetted, espe- cially under building loads. The mapping indicates Eagle Valley Evaporite bed- rock is below the site. CGS has mapped several sinkhole, subsidence and soil collapse features in the area of the subject property. Surface subsidence in the area of the subject site is usually due to solution cavities that form in the underlying Eagle Valley Evaporite bedrock. The Evaporite minerals in the bedrock formation are dissolved and removed by circulating groundwater. Most of the flow in the area of this site is subflow tributary to the Roaring Fork River. The groundwater circulates through the permeable atluvial terrace gravel, forming solution cavities in the Eagle Valley Evaporite. Overburden soils collapse into the solution cavities. When caving propagates to the ground surface, ground subsicjence andlor sinkholes occur. Formation of sinkholes is random and can occur anywhere anci at any time in the geologíc environment at this site and cannot be predicted. The degree of risk related to sinkholes cannot reasonably be quantified. We did not observe ob- vious visual evidence of sinkhole/subsidenee formations on or immediateiy adja- cent to the subject property. We are not aware of buildings in the immediate vicin- ity of the subject property that have experienced recent subsidence-related dam- age. we rate the potential risk of sinkhole development at the site as low. DON HECKER HECKER RESIDENCE PROJECT NO. GS065s3.000-1 20 4 ffi SUBSURFACE CONDITIONS Subsurface conditions were investigated by observing the excavation of three exploratory pits (TP-1 through TP-3) spaced across the site. The pits were excavated with a trackhoe at the approximate locations shown on Figure 2. Ex- ploratory excavation operations were directed by our representative, who logged the subsoils encountered and obtained representative samples of the soils. A photograph of soils excavated from TP-1 is below. Soils excavated from TP-1 Graphic logs of the soils found in our exploratory pits are included as Fig- ure 3. Subsoils encountered in our exploratory pits excavated at the site con- sisted of about 1 to 2 feet of topsoil and fill over 3 to 9 feet of natural silty sand and gravel, underlain by silty gravel and cobbles to the maximum explored depth of 1 1.5 feet. Groundwater was nol found in our exploratory pits at the time of ex- cavation. Pits were backfilled immediately after completion of exploratory excava- tion operations. DON HECKER HECKER RESIDENCE PROJECT NO. GSo6553.000120 5 ffi Samples of the soils obtained from our exploratory pits were returned to our laboratory for pertinent laboratory testing. Three samples selected for grada- tion analysis contained 20 to 30 percent gravel, 40 to 57 percent sand, and 20 to 40 percent silt and clay (passing the No. 200 sieve). Gradation test results are not inclusive of gravel and cobbles larger than 5 inches. Engineering index test- ing on two samples of the silty sand indicated low plasticity with liquid limits of 27 and 20 percent and plasticity indices of 4 and 1 percent. One sample of the sci! tested contained 0.0 percent water-soluble sulfates. Gradation test results are shown on Figures 4 and 5. Laboratory testing is summarized on Table l. SITE EARTHWORK Excavations Excavation depths of about 3 to 4 feet are expected to attain proposed foundation elevations. Additional excavation of at least 3 feet will be required to accomplish the recommended subexcavation and recompaction process below footings and slabs. Based our subsurface investigation, excavations in the soils at the site can be made with conventional, heavy-duty equiprnent, such as me- dium-size trackhoe. Sides of excavations deeper than 5 feet need to be sloped or braced to meet local, state, and federal safcty regulations. The on-site soils will classify as Type C soils, based on OSHA criteria. Sides of excavations in T-rrpe C soils should be sloped no steeper than 1.5 to 1 (horizontal to vertical). Contrac- tors are responsible for site safety and providing and maintainíng safe and stable excavations. Contraetors should identify the soiis encountered end ensure that OSHA standards are rnet. Free groundwater was not encountered in our exploratory pits. We do not expect that excavations for the proposed construction will penetrate a free groundwater table. Excavations should be sloped to a gravity discharge or to a DON HECKER HECKER RESIDENCE PROJECT NO. cS06553,000-t 20 6 ffi temporary sump where water from precipitation and snowmelt can be removed by pumping. Subexcavation and Structural Fill Based on our field and laboratory data from the site, and our engineering experience, we judge the silty sand and gravel soil (i.e., debris flow deposÍts) at the site has potential for moderate to high amounts of consolidation when wetted under building loads. We expect the proposed residence can be constructed on a footing foundation with a slab-on-grade garage floor, provided the soils below the building are subexcavated to a depth of at least 3 feet below bottom of footing and slab elevations. The subexcavation process should extend at least 1 foot be- yond the edges of the building perimeter. A reinforced concrete mat founda- tion/floor system can be supported directly by the undisturbed, natural soils. CTL should be called to observe conditions in the subexcavated area, prior to placement of structural fill. The subexcavated soils, free of organic mat- ter, debris and rocks larger than 3 inches in diameter can be re-used as struc- tural fill. The structural fill soils should be moisture-conditioned to within 2 percent of optimum rnoisture content and placed in loose lifts of I inches thick or less. Structuralfill should be compacted to at least g8 percent of standard Proctor (ASTM D 698) maximum dry density. Moisture content and density of structural fill should be checked by a representative of our firm during placement. Observa- tion of the compaction procedure is necessary. Foundation Wall Backfill Proper placement and compaction of foundation backfill is important to re- duce infiltration of surface water and settlement of backfill. This is especíally im- portant for backfill areas that will support concrete slabs, such as driveways and DON HECKER HECKER RESIDENCE PROJECT NO. GSo6553.000-120 7 ffi patios. The natural soils free of rocks larger than 4 inches in diameter, organics and debris can be reused as backfill adjacent to foundation wall exteriors. Backfill should be placed in loose lifts of approximately 10 inches thick or less, moisture-conditioned to within 2 percent of optimum moisture content and compacted to at least g5 percent of standard Proctor (ASTM D 6gs) maximum dry density. Moisture content and density of the backfill should be checked during placement by a representative of our firm. Observation of the compaction proce- dure is necessary. FOUNDATION Based on geologic mapping and our engineering experience, the silty sand and gravel soil has potential for moderate to high amounts of consolidation when wetted under building loads. We judge the residence can be constructed with a footing foundation with a slab-on-grade garage floor, provided the soils be- low footings and slabs are sub-excavated to a depth of at least 3 feet and re- placed as densely-compacted, structural fill. We expect the excavated soils can be moisture-treated and reused to build a mat of densely-compacted, structural fiil below the building. Subexcavation and structural fill should be in accordance with recommendations in the Subexcavation and Structural Fill section. An alternative would be construction of the residence on a reinforced con- crete mat foundationlfloor system. This system would integrate the foundation ^-i ¡l^^- ^^l :- l^-^ .^---^ ^ L- -trÉ----cilru iluut irilu Ñr te55 pf une tu utltef enUat movemenl. Íl relnTorceo conereïe mal foundation can be constructed directly on the undisturbed, naturai soí! without subexcavation and replacement with structural fill. Recommended design and construction criteria for footings and a rein- forced mat are below. These criteria were developed based on our analysis of field and laboratory data, as well as our engineering experience. DON HËGKER HECKER RESIDENCE PROJECT NO. GS06553.000-1 20 I ffi Footinqs Footings should be supported on densely-compacted, structuralfill that is at least 3 feet thick. Structuralfill should be in accordance with recommendations in the Subexcavation and Structural Fillsec- tion. Footings supported on densely-compacted, structural fill can be de- signed for a maximum net allowable bearing pressure of 3.000 psf. - The weight of soil backfill above the footings can be neglected. A friction factor of 0.4 can be used to calculate resistance to sliding between concrete footings and the structural flll. Continuous wall footings should have a minimum width of at least 16 inches. Foundations for isolated columns should have rninimum dimensions of 24 inches by 24 inches, Larger sizes may be re- quired, depending upon foundation loads. Grade beams and foundation walls should be well reinforced to span undisclosed loose or soft soil pockets. We recommend rein- forcement sufficient to span an unsupported distance of at least 12 feet. The soils under exterior footings should be protected from freezing. We recommend the bottom of footings be constructed at a depth of at least 36 inches below finished exterior grades. The Garfield County building department should be consulted regarding required depth. Reinforced Concrete Mat Foundation The reinforced concrete mat foundation can be supported on the undisturbed, silty sand and gravel soil. The reinforced concrete mat should be designed for a maximum al- lowable soil pressure of 2,000 psf for dead load plus live load and 3,000 psf for total loads including wind or seismic. Stiffening mem- bers such as thickened sections for interior wall and column sup- port will likely be needed. 3. We recommend the reinforced concrete mat be at least 18-inches thick. The mat should be heavily-reinforced and preferably in a sin- gle monolithic configuration to help maintain its integrity in the event DON HECKER I HECKER RESIDENCE PROJECT NO. GS0€553.000-120 3 4 1 2 5 6 1 2 ffi of ground movement. The mat should be sufficienily stiff to span 12 feet in the center and a 5 feet cantilever along the edges. Modulus of subgrade reaction (lG) ¡s normally used for reinforced mat founclation design. The modulus of subgrade reaction is de- pendent upon the compressibility of the foundation soils and the size (or effective loaded area) of the foundation. lf the entire mat foundation is uniformly loaded, then a Ks varue of 120 pci is recom- mended. A friction coefficient of 0 40 can he used for lateral re- sistant between conerete and the undisturbed. siltv -sand and nrar-¡e! soil. Lateral loads can be resolved by evaluating passive resistance us- ing an equivalent fluid density of 300 pcf for the granular structural fill or natural granular soils, provided the backfiil is compacted and is not removed, A moist unit weight or i25 pcf can be assumed for backfill soils. These values have not been factored; appropriate fac- tors of safety should be applied in design. Soils beneath the building should be protected from freezing. We recommend the perimeter of mat be at least 36 inches deep. The Garfield county building department should be consurted regarding roquired depth. SLAB.ON-GRADE CONSTRUCTION A slab-on-grade floor can be utilized in the garage, provided the soils be- low the slab are subexcavated to a depth of at least 3 feet. The excavated soils should l,re replaced with densely-compacted, structural fill. lhe structuralfill should be in accordance with recommendations in the Subexcavatisn And Struc- tural Fill section. A reinforced concrete mat foundation/floor system can be sup- ported dlrectly on the undisturbed, silty sand and gravel soilwithout subexcava- +;^ñ ^^¡ -^^l^^^-^*¡ ...:¡L ^¡-..-a- ---r .:riioil anû replacemenî wltn structl¡rai lti. A mat system iniegrates ihe founciation and fioor and is less prone to differential movement. Based on our analysis of field and laboratory data, as well as our engi- neering experience, we recommencJ the following precautions for slab-on-grade construction at this site. 4 5 6 IION HEGKER HECKER RESIDENCE PROJECT NO. cS06553.000-l 20 1CI ffi Slabs should be separated from footings and columns with slip joints which allow free vertical movement of the slabs. Underslab plumbing should be pressure tested for leaks before the slabs are constructed. Plumbing and utilities which pass through slabs should be isolated from the slabs with sleeves and provided with flexible couplings to slab supported appliances. Exterior patio slabs should be isolated from the buildings. These slabs should be well-reinforced to function as independent units. Frequent controljoints should be provided, in accordance with American Concrete lnstitute (ACl) recommendations, to reduce prqblems associated with shrinkage and curling. CRAWL SPACE CONSTRUCTION The main level floor of the residence is proposed as structurally-supported by the foundation walls with a crawl space below the floor. Building codes nor- mally require a clear space of at least 18 inches between exposed earth and un- treated wood floor components. For non-organic systems, we recommend a mini- mum clear space of 12 inches. This minimum clear space should be maintained between any point on the underside of the floor system (including beams, plumb- ing pipes, and floor drain traps and the soils. Utility connections, including water, gas, air duct, and exhaust stack con- nections to appliances on structural floors should be capable of absorbing some deflection of the floor. Plumbing that passes through the floor should ideally be hung from the underside of the structural floor and not laid on the bottom of the excavation. lt is prudent to maintain the minimum clear space below all plumbing lines. lf trenching below the lines is necessary, we recommend sloping these trenches, so they discharge to the foundation drain. 1 2 3. 4. DON HECKER HECKER RESIDENCE PROJECT NO. GS06553.000-1 20 11 ffi Cotrtrol of humidity in crawl spaces is important for indoor air quality and performance of wood floor systems. We believe the best cunent practices to con- trol humidity involve the use of a vapor retarder or vapor barrier (10 mil mÍnimum) placed on the soils below accessible subfloor âreas. The vapor retarder/barrie¡. should be sealed at joints and attached to concrete foundation elements. FOUNDATION WALLS Foundation walls which extend below-grade should be designed for lateral earth pressures where backfill is not present to about the same extent on both sides of the wall, such as in crawl spaces. Many factors affect the values of the design lateral earth pressure. These factors include, but are not limited to, the type, compaction, slope, and drainage of the backfill, and the rigidity of the wall against rotation and deflection. For a very rigid wallwhere negligible or very little deflection will occur, an "at-rest" lateral eaÉh pressure should be used in design. For walls that can de- flect or rotate 0.5 to 1 percent of wall height (depending upon the backfill types), design for a lower "active" lateral earth pressure may be appropriate. Our experi- ence indicates typical below-grade walis in residences deflect or rotate slightly under normal design loacls, and that this deflection results in satisfactory wall performance. Thus, the earth pressures on the walis will likely be between the "active" and "at-rest" conditions. For backfilisoils conforming with reeommendations in ihe Foundation Waii Backfill seetion that are not saturated, we recommend design of below-grade walls at this site using an equivalent fluid density of at least 40 pcf. This value as- sumes deflection; some minor cracking of walls may occur. lf very little wall de- flection is desired, a higher design value for the at-rest condition using an equiva- lent fluid pressure of 55 pcf is recommended. These equivalent densities do not include allowances for sloping backfill, surcharges or hydrostatic pressures. DON HECKËR HECKER RESIDENCE PROJECT NO. GSo8553.000-1 20 12 ffi SUBSURFACE DRA¡NAGE Water from precipitation, snowmelt, and irrigation frequently flows through relatively permeable backfill placed adjacent to a residence and collects on the surface of less permeable soils at the bottom of foundation excavations. This pro- cess can cause wet or moist conditions in below-grade areas, such as crawl spaces, after construction. To reduce the likelihood water pressure will develop outside foundation walls and the risk of accumulation of water in below-grade ar- eas, we recommend provision of a foundation wall drain. The foundation drain should consist of 4-inch diameter, slotted PVC pipe encased in free-draining gravel. A prefabricated drainage composite should be placed adjacent to foundation walls. Care should be taken during backfill opera- tions to prevent damage to drainage composites. The drain should discharge via a positive gravity outlet or lead to a sump where water can be removed by pumping. The foundation wall drain concept is shown on Fígure 6. SURFACE DRAINAGE Surface drainage is criticalto the performance of foundations, floor slabs, and concrete flatwork. Surface drainage should be designed to provide rapid run- off of sudace water away from the residence. Proper surface drainage and irriga- tion practices can help control the amount of surface water that penetrates to foundation levels and contributes to settlement or heave of soils and bedrock that support foundations and slabs-on-grade. Positive drainage away from the foun- dation and avoidance of irrigation near the foundation also help to avoid exces- sive wetting of backfill soils, which can lead to increased backfill settlement and possibly to higher lateral earth pressures, due to increased weight and reduced strength of the backfill. We recommend the following precautions. DON HECKER HECKER RESIDENCE PROJECT NO. GSo6553.000-120 13 ffi The ground sufface surrounding the exterior of the residence should be sloped to drain away from the building in alr directions. we recommend a minimum constructed slope of at least 12 inches in the first 10 feet (10 percent) in landscaped areas around the resi- dence, where practical. Backfill around the foundation walls should be moistened and com- pacted pursuant to recommendations in the Foundation wall Back- fill section, The residence should be provided with roof gutters and down- spouts. Roof downspouts and drains should discharge well beyond the limits of all backfill. splash blocks andlor extensions should be provided at all downspouts so water discharges onto the ground beyond the backfill. we generally recommend against burial of downspout discharge. Where it is necessary to bury downspout dis- charge, solid, rigid pipe should be used, and the pipe should slope to an open gravity outlet. Landscaping should be carefully designed and maintained to mini- mize irrigation. Plants placed close to foundation wails should be limited to those with low moisture requirements. sprinklers should not discharge within 5 feet of foundations. plastic sheetirrg should not be placed beneath landscaped areas adjacent to foundation walls or grade beams. Geotextile fabric will inhibit weed growth yet still allow natural evaporation to occur. CONCRETE Concrete in contact with soil can be subject to sulfate attack, We meas- ured a soluble sulfate concentration of 0.00 percent in a sample of the soii from this site (see Table l). For this level of sulfate concentration, ACI 332-08, "Code Requirements for Residential Concrete", indicates there are no special require- ments for sulfate resistance_ ln our experience, superficial damage may occur to the exposed surfaces of highly permeable concrete. To control this risk and to resist freeze thaw deteri- oration, the water-to-cementítious materials ratio should nof exceecl 0.50 for con- crete in contact wíth soils that are likely to stay rnoist due to surface drainage or DON I{ECKER HECKER RESIDENCE PROJECT NO. GS065s3.000-120 1 2. 3. 4 14 tr high-water tables. Concrete should have a total air content of 60/o +/-1.5%. We recommend all foundation walls and grade beams in contact with the subsoils be damp-proofed. CONSTRUCTION OBSERVATIONS We recommend that CTL I Thompson, lnc, be retained to provide con- struction observation and materials testing services for the project. This would al- low us the opportunity to verify whether soil conditions are consistent with those found during lhis investigation. lf others perform these observations, they must accept responsibility to judge whether the recommendations in this report remain appropriate. lt is also beneficialto projects, from economic and practical stand- points, when there is continuity between engineering consultation and the con- struction observation and materials testing phases. STRUCTURAL ENGINEERING SERVICES CTL I Thompson, lnc. is a full-service geotechnical, structural, materials, and environmental engineering firm. Our services include preparation of struc- turalframing and foundation plans. We can also design earth retentíon systems. Based on our experience, CTL I Thompson, lnc. typically provides value to pro- jects from schedule and economic standpoints, due to our combined expertise and experience with geotechnical, structural, and materials engineering. We can provide a proposal for structural design of the foundation, if requested. GEOTECHNICAL RISK The concept of risk is an important aspect of any geotechnical evaluation The primary reason for this is that the analytical methods used to develop ge- otechnical recommendations do not comprise an exact science. The analytical DON HECKER HECKER RESIDENCE PROJECT NO. G506553.000-120 l5 ffi tools which geotechnicalengineers use are generally empirical and must be tem- pered by engineering judgment and experience. Therefore, the solutions or rec- ommendations presented in any geotechnical evaluatÍon should not be consid- ered risk-free and, more importantly, are not a guarantee that the interaction be- tween the soils and the proposed structure will result in performance as desired or intended. The engineering recommendations presented in the preceding sec- tions constitute gur estimate of those mea$ures necessary to heln fhe hr¡ilrtinn perform satisfactorily. This report has been prepared for the exclusive use of the client for the purpose of providing geotechnical design and construction criteria for the pro- posed project. The information, conclusions, and recommendations presented herein are based upon consideration of many factors including, but not limited to, the type of structures proposed, the geologic setting, and the subsurface condi- tions encountered- The conclusions and recommendations contained !n the re- port are not valid for use by others. Standards of practice continuously change in the area of geotechnical engineering. The recommendations provided in this re- port are appropriate for three years. lf the proposed project is not constructed within three years, we should be contacted to determine if we should update this report. LIMITAT¡ONS Our exploratory pits provide a reasonable characterization of subsurface conditions at the site. Variations in the subsurface eonditions not indicated by the pits will occur. We should be provided with architectural plans, when available, sc that we can provide geotechnical/geo-structural engineering input. NON HECKER HECKER RESIDENGE PROJECT NO. GS06553.000-120 16 This investigation was conducted in a manner consistent with that level of care and skill ordinarily exercised by geotechnical engineers currently practicing under similar conditions in the locality of this project. No warranty, express or im- plied, is made. lf we can be of further service in discussing the contents of this report, please call. cTL I THOMPSO INC Reviewed -*2;......*__- * ffi 't¿. J'":'t'."4 ¿'tt¡ tr' 2o-l Ryan Barbone, P.E. Project Engineer RRB:JDK:abr DON HECKER HECKER RESIDENCE PROJECT NO. G506553.000-120 esD ISION '17 ffi 0 5c[) f (xx'NOTE: SCÅLE: 1'= 10OO' Don Hecker H¡dorR¡¡Uoncc SATELLITE IMAGE FROM GOOGLE FÁRTH (ÐATED JUNE 2017) l Vicinity Map Residence PROJECT NO. GSO6553.OOO-1 20 Flg. I LEGEND TP_1I 25 50 NOTE: SCALE: 1'= 50' Don Hecker HsÕlør Boddônco APPROXIMATE LOCATION OF EXPLORATORY PIT APPROXIMATE LOCATION OF PROPERTY BOUNDARY SATELLITE IMAGE FROM GOOGLE EARTH (DATED JUNE 2017) ffi t:.¿ ,1 :l !ñ ot Aerial Photograph '.1 PROJECT NO. GSO6553.OOO-120 Flg. 2 TP.1 rP-2 0 10 15 DON HECKER HECKER RESIDENEE PROJECT NO. GS065s3.000-120 FILL, GRAVEL, CLAYEY. MEDIUM DENSE, MOIST. BROWN. TOSOIL, SAND, SILTY, ORGANICS, MOIST BROWN, SAND, SILTY, SCATTERED GRAVEL AND COBBLES, MEDIUM DENSE TO DENSE, SLIGHTLY MOIST TO MOIST, RUST, BROWN (sM) GRAVEL, SILTY. COBBLES, SCATTERED BOULDERS. MEDIUM DENSE TO VERY DENSE, SLIGHTLY MOIST TO MOIST, BROWN, RUST, TAN. (cM) INDICATES BULK SAMPLE FROM EXCAVATEÐ SOILS EXPLORATORY PITS WERE EXCAVATEÐ WITH A TRACKHOE ON MARCH 9,2021. PITS WERE BACKFILLED IMMEDIATELY AFTER EXPLORATORY EXCAVATION OPERATIONS WERE COMPLETED. 2. GROUNDWATER WAS NOT FOUND IN OUR EXPLORATORY PITS AT THE TIME OF EXCAVATION. LOCATIONS OF EXPLORATORY PITS ARE APPROXIMATE. 4" EXPLORATORY ptTS ARE SUBJECT TO THE EXPLANATIONS. LIMITATIONS AND CONCLUSIONS CONTAINED IN THIS REPORT, ffi Summary Logs of Fl[g,o'atôry FIG. 3 TP-3 LEGEND: 0 5Ë E w Fl1l TU TL TF ul(f ¡-t¡lulL TFt]-ulU 10 15 F NOTES: 3 ffi SANDS GRAVEL cLAY (PLASïC) TO SrLT (NON-PLCSflC)FINE MEDIUM COARS FINE COARSE COBBLÊS SIEVE ANALYSISHYDROMEÌER ANALYSIS 0 10 20 30 40 50 60 70 80 90 100 .074 .149 .297 .590 1.'19 2.0 2.38 4.76 9.52 19.1 36.1 76.2 127 200o.42 152 DIAMETER OF PARTICLE IN MILLIMETERS * ôuz tsut FzuotUo 100 90 80 2?oıø "<60Fz 350dlllÀao .001 0.002 .005 .009 .019 .03? 5"6" 8" U.S- STANDARD SERIES 100 '50 '40 '30 '16 '10'8 CLËAR SQUARE OPENINGS 3/8" 314" 1y;' 3' TIME READINGS 60 MrN. 19 MtN. 4 MtN. 't MlN. ',200 JU 20 10 0 25HR.7HR. 45 MtN. 15 MlN. Somple of SAND, StLTy (SM) From TP - 2 AT 5-6 FEET Somple of sAND, stlTy (sM)From rp - 2 AT 1o.s-11.5 FEET DON HECKER HECKER RESIDENCE PROJECT NO. G506553.000-1 20 GRAVEL SILT & CLAY PLASTICITY INDEX GRAVEL 23 o/o stLT & CLAY 20 o/o PLASTICITY INDËX SAND LIOU¡D LIMIT 40% % % 20 Yo 40 Yo SAND LIQUID LIMIT 57 o/o % % Gradation Test Results SANDS GRAVEL MEDIUM COARS FINE COARSE COBBLES CLAY (PIASTTC) TO SrLT (NON-PrAsTlC) FINE SIEVE ANALYSISYSIS _-_t_--t----.-t-^ -t---t.'*--_--1.---l _t_*_t__ ---1-.' ---------t------- --l---_-I :-1-----t--_-l --------t- -/:1,----,:: I --.---t-t -T:_t_-_t_#-:l- ---.t- --t, -t , .---t _t__-2/-___+----I'-t'-----.-----l--='--='_:l --- _t_ _-_--------+---_+------l-----'-- | I I - t----t- 10 20 JU 40 50 60 70 80 100 ouz Fùd 100 90 80 ¡g70z6Ø€0È tsz u50 u14o 30 2A 10 0 .001 0.002 .005 .009 .019 .037 9.52 19,1 36.1 76.2 127 200 152 U.S. SÍANDARÐ SER¡ES 'r00 '50'40'30 '16 '10'8 CLEAR SOUARE OPËNINGS 3/6' 3¡4" Iyì' 3" 5'6" TIME REAOINGS 60 MtN l9 MtN. 4 MtN. I MlN. '200 .o74 .149 .297 .590 1.19 2.0 2.38 4.76 o.42 DIAMETER OF PARTICLE IN MILLIMETERS 25 HR. 7 HR. 45 MrN 15 MlN. FIG. 4 ffi ANALYSIS SIEVE SANDS GRAVELcrAY (pLASTtC) TO SILT (NON-PLAST|C) FINE MEDIUM COARS FINË COARSE COBBLES 25 HR. 7 HR. 45 MlN. 15 MrN. 100 Sompie of From DON HËCKER HECKER RESIDENCE PROJECT NO. G506553.000-120 TIME REÂD¡NGS 60 MtN. tg MtN. 4 MtN. I MtN. .200 STANDARD SERIES.100 '50 '40 .30 .16 '10 .8 .4 3/8" GRAVEL sLr a cmy PLASTICITY INDEX GRAVEL SILT & CLAY PI-RSTtCt¡v ll.¡OEii SOUARE OPENINGS 3t4" Iy| 3"5'6" B" 90 970ıa Í60 F.z 850t uJÈ40 0 10 ?o 30 40 50 60 70 80 90 uzaFu Ê. Fzuo ff,utI 30 2Ð '10 0 .001 0.002 .005 .00e .019 ,037 .074 .140 .?07- .- .590 1,19 2.0 2.38 4.7A 9.52 19.1 36.1 76.2 12.t 2009.42 - - -i1z--- DIAMETER OF PARTICLE IN MILLIMETERS 100 Somple of SANp, SlLry (qll)From rp - I Ãî o-z reEÍ 30 o/o zsw SAND LtautD [lMtT % SAND % L1QUID LIMIT o/o 0/^ % Gradation Test Results 7: Æ__l I -l==l=_l=---t -_.:i-. SANDS GRAVELCLAY (PLASTIC) lO stLT (NON-pLASllC) FINE MEDIUM COARS FINE COARSE COBBLES i¡-_ t_L_:ril- _l_t_- 1_l__i_l__t_l_ tt_---+- t----,,,1-t---,--il:--- _Lt__]__t___ _._Ll__ _----F 0 10 20 40 50 70 80 90 100 (,10zı t60 Fz u50ÉUe4o 127 240 152 YStS '4 90 80 100 30 20 10 0 .001 0.002 .005 .009 .019 .037 9.0¿ ,v. I JO. r /ô 2 TIME REAÐINGS 60 MlN. 19 MtN. 4 MtN. I MtN. .200 U.S. STANDARD SERIES '100 '50 '40 ,30 .16 .10 .8 CLEAR SOUARE OPENINGS 3/8" 3t4" 1A' 3. ,874 .'!49 .297 .590 1.19 2.0 2.33 4.76o.42 DIAMETER. OF PARTIClE IN MILLIMETERS 25 HR. 7 HR. 45 MtN. 15 MrN. FIG.5 tr I NOÏE DRAIN SHOU1D BE AT I..EAST 2 NCHES BELOTV BOTTOM OF FOONNG AT THE HßHEST FONT AI.ID SLOPE DOTTI{WARD TO A FOSITTVE GRAVITY OIN..ET OR TO A SUMP TYHERE IVATER CÁI.I BE REMOVED FI PUMPING. SL]oPE SLOPE OSHA COVER S{NRE WIDTH OF M¡MDRAIN G2Í}ON OR EQUIVAI.ENÍ AfiACH PI.ASÍIC SHEENNG TO FOUNDATON WATI 8, MINIMUM OR BETOND r cRAtttL sPAcE J PER GRAVEL TVÍTH NON-WOVEN GEOrÞfitE FABRTC (Unnn 1¡t0N OR EaUMA[$fÌ). FOONNG OR PAD I|UD SI..åB' OR BARRIER MIN¡MUM ÞON HECKER FEOKER RESIDENOE 1:1 SLOPE FROM BOTTOM OF FOONNG (r!,þilcHEvER rs GRFATER) 4-INCH DIAMETER PERFORITTED DRAIN PIPE. T}IE PIPE SHOUL.D BE PI.ACED IN A TRENCH TUNi A sLoPE OF AT tE^Sr 1/S-|NCH DROP pER FOOT OF DRAIN. Foundation Wall Drain Concept SÍRUSTRAL FLOOR PROJECT NO. GSO6553.OOO-1 20 Fls.6 TABLE ISUMMARY OF LABORATORY TESTINGPROJECT NO. GSo6553.000-t 20ffiDESCRIPTIONSAND, SILTY (SM)SAND, SILTY (SM)SAND, SILTY (SM)SAND, S¡LTY (SM)SAND, SILTY (SM)PASSINGNO. ,ZOOSIE\/E(%\4646402025PERCENTSANDPA\405745EERCENTGRA,VEL(%)202330SOLUBLESULFATES(%)0.00ATTERBERG LIMITSPLASTICITYINDEX(%\41LIQUIDLIMIT(%\2V2ADRYDENSITY'(PCF)MOISTURËCONTENT(%)DEPÏH(FEET)2-38-95-610.5-11.56-7EXPLORATCRYPITTP.1TP.1TPA-rF-2TP-3Page I of 1