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Home My WebLink AboutSoils & Foundation Investigation 07.11.2018ffi CTL ITHOMPSON@ RECEIVED JUL I I 20tS GARFIELD COUNTY COMMUNITY DEVELOPMET{Î SOILS AND FOUNDATION INVESTIGATION PROVOST RESIDENCE LOT 53-8, PANORAMA RANCHES GARFIELD COUNTY, COLORADO Prepared For: TOM PROVOST P.O. Box 1129 Carbondale, CO e1625 Project No. GS06 219.000-120 234 Center Drive I Glenwood Springs, Colorado g1601 Telephone: 970-945-2809 Fax: 970_945-2411 April 17,2018 ffi TABLE OF CONTENTS scoPÊ...... SUMMARY OF CONCLUSIONS SITE CONDITIONS PROPOSED CONSTRUCTION.... GEOLOGIC HAZARDS.. SUBSURFACE CONDITIONS...... SITE EARTHWORK..... Excavations Sub-Excavation ..... FOUNDAT|ONS.............. Drilled Piers .......... Footings on Structural F¡11.......... SLAB-ON-GRADE FLOORS ........ STR UCTU RALLY-SUPPO RTED FLOORS FOUNDATION WALLS Foundation Wall Backfill .......................... SUBSURFACE DRAI NAGE.............. SURFACE DRAINAGE CONCRETE GEOTECHNICAL RISK 1tMtTATtONS................. FIGURE 1 -VICINITY MAP FIGURE 2 - LOCATIONS OF EXPLORATORY BORINGS FIGURE 3 - SUMMARY LOGS OF EXPLORATORY BORINGS FIGURES 4 AND 5 _ SWELL-CONSOLIDATION TEST RESUTLS FIGURE 6 - STRUCTURAL FILL CONCEPT FIGURES 7 AND B _ FOUNDATION DRAIN CONCEPTS APPENDIX A _ SURFACE DRAINAGE, IRRIGATION AND MAINTENANCE TOM PROVOST PROVOST RESIDENCE PROJECT NO. GS0621 9.000-120Clusers\athate\Box\Projects\GlenwoÕd Spr¡ngs - Projects\c50621 9.000\1 20\2, Reports\Gs062'l 9.000 1 20 Ri.docx ...............1 ...............1 ...............2 ...............2 .............. 3 ..............3 ....4 ....4 ....5 ....6 ....6 ....7 B 9 ........12 ........12 .... 13 ....14 ffi SCOPE This report presents geotechnical engineering recommendations for the Provost Residence proposed on Lot 53-B of the Panorama Ranches Subdivision in Garfield County, Colorado. Our report was prepared frorn data developed from our subsurface exploration, laboratory testing, engineering analysis, and our expe- rience with similar conditíons. This report includes a description of the subsurface .- conditions encountered in our exploratory borings and presents geotechnical engi- neering recommendations for desígn and construction of the building foundation, floor system, below-grade walls, subsurface drainage, and details influenced by the subsoils. Recommendations contained in this report were developed based on our understanding of the proposed construction. A summary of our conclusions is presented below. SUMM,ARY OF GONCLUSIONS Our exploratory borings encountered about 13 and 15 feet of pre- dominantly sandy clay underlain by clayey gravel to the maximum explored depth of 30 feet. Free groundwater was not found in our borings at the time of drilling. 2 We judge there is high risk of differential movement and associated damage if shallow foundation systems are constructed directly on the undisturbed natural soils at this site. ln our opinion, a drilled pier foundation system is appropriate for the residence. The residence can be constructed on footi foundation ded the natural soils are su a an mo l. The owner must acce a movement and building amage rn- herent With Jhis áþproãch Añ ce, as comþãiedio ioıllngÞ, would be construction of a reinforced con- crete mat foundation on the structural fill. 3. ln our op inion, the risk of differential movement and associated dam- c,eish h for slab-on-grade floors s rted d U natural sot recommen SU vation of at least 3 feet of the soils below slabs and re lacement with structural fill to en ance nce. The most posr- m tom e movement ts construction of structurally- 1 TOM PROVOST PROVOST RESIDENCE PROJECT NO. GS06219.000-120 C:\Users\athate\Box\Projects\clenwood Spr¡ngs - projects\GS06219.000\120\2. Reports\G506219.000 120 Rl.docx 1 ffi supported floors. The owner must accept the risk of potential move- ment of slab floors. Building performance is influenced by moisture conditions in the sub- soils. An exterior foundation drain svstem should be constructed around be rade areas in the residence. Ground surfaces should e designed an g provide for rapid removal of surface wa- ter away from the resídence. SITE CONDITIONS Panorama Ranches is a residential development located northeast of Car- bondale in Garfield County, Colorado. A vicinity map with the location of the site is shown on Figure 1. Lot 53-B Ís an approximately 16-acre parcel, near the termi- nus of Buck Point Road. Ground surface at the site generally slopes down to the west at grades of about 10 percent. Steeper slopes are along the northwest prop- erty boundary. Vegetation on the lot consisted of weeds and grasses. An aerial photograph of the site is on Figure 2. PROPOSED CONSTRUCTION Building plans for the Provost Residence were being developed at the time of our investigation. We anticipate the residence will be a one or two-story, wood- frame building with an attached garage and a basement or crawl space. Maximum foundation excavation depths of about B to 10 feet are expected to construct the residence. We expect maximum foundation loads of about 2,000 to 3,000 pounds per lineal foot of foundation wall and maximum column loads of 30 kips. lf actual construction will differ significantly from the descriptions above, we should be in- formed so that we can provide geotechnical engineering input and revise our rec- ommendations, if necessary. TOM PROVOST PROVOST RESIDENCE 3îr?jlî,,TrÏ3,.u3-Ì3"iJ:,"tr3[#3". sprinss - projects\cso621e.oo0\120\2. Reports\GsoG21s.ooo r20 Rl.docx 4 2 ffi GEOLOGIC HAZARDS We reviewed the open file mapping titled, "Geologic Map of The Leon Quadrangle Eagle and Garfield Counties, Colorado", bV the Colorado Geologic Survey (dated 1998). The site is mapped as sediments of Missouri Heights of the early Quaternary and late Tertiary Periods. These deposits consist of locally de- rived gravel, sand, silt, and clay deposited in the Missouri Heights area in alluvial and colluvial environments. These are deposited in areas topographically lowered by collapse or subsidence related to dissolution of the underlying Eagle Valley Evaporite. The open file mapping does not indicate sinkholes created by piping or collapse of surficial deposits in the area of the site. No surface evidence of subsid- ence was noted on the subject lot. We also reviewed the Colorado Geological Survey mapping titled, "Collapsi- ble Soils and Evaporite Karst Hazards Map of the Roaring Fork River Corridor, Garfield, Eagle, and Pitkin Counties, Colorado", by Jonathan White (dated 2002). No sinkholes have been mapped in the vicinity the subject lot. lt is possible that other sinkholes that have not been defected are present. SUBSURFACE CONDITIONS To investigate subsurface conditions at the site, we directed the drilling of two exploratory borings (TH-1 and TH-2) at the approximate locations shown on Figure 2. Exploratory drilling operations were directed by our field representative who logged subsurface conditions exposed in the borings and obtained samples of the soils. Graphic logs of the soils encountered in our exploratory borings are shown on Figure 3. Subsurface conditions encountered in our exploratory borings drilled at the site consisted of about 13 and 15 feet of predominantly sandy clay underlain by clayey gravel to the total explored depth of 30 feet. Results of field penetration re- sistance tests and our observations during drilling operations indicated the clay TOM PROVOST PROVOST RESIDENCE PROJEGT NO. GS06219.000-120 c:\Users\athate\Box\Projects\Glenwãod spr¡ngs - Projects\GSo62'l9'000\120\2' Reports\GS06219'000 12o R1'docx 3 ffi was medium stift to very stiff and the gravel was dense to very dense. Ground wa- ter was not found in our exploratory borings. Two samples of the soil selected for one-dimensional, swell-consolidation testing exhibited no movement and 8.4 percent swell when wetted under an ap- plied pressure of 1,000 psf. Our geotechnical engineering experience in the area of the site indicates the soils exhibit volume change potential ranging from moder-. ate consolidation to high expansion. Swell-consolidation test results on two sam- ples of the sandy clay from our exploratory borings drilled at the site are shown on. Figures 4 and 5. Results of laboratory testing are summarized on Table l. SITE EARTHWORK Excavations Our subsurface information indicates excavations for the planned residence will be in natural sandy clay soil. Excavation can be accomplished using conven- tional, heavy-duty excavating equipment. Excavations can likely be sloped to meet local, state and federal safety regulations. We expect the soils will generally classify as Type B soils based on OSHA standards governing excavations. Tem- porary slopes at this site for excavations should be no steeper than 1 to 1 (hori- zontal to vertical) in Type B soils. The contactor should identify soils encountered in excavations and refer to OSHA standards to determine appropriate slopes. Free groundwater was not encountered in our exploratory borings during drilling operations. We do not anticipate that groundwater will affect the antici- pated construction. Excavations should be sloped to a gravity discharge or to a temporary sump where water can be removed by pumping. TOM PROVOST PROVOST RESIDENCE PROJECT NO. GS06219.000-120 C:\Users\athate\Box\Projects\Glenwood Springs - Projecls\G506219'000\120\2' Reports\G506219.O0O 120 Rl.docx 4 ffi Sub-Excavation Laboratory test results and our geotechnical engineering experience in the area indicate that the natural soils below the subject lot possess the potential for moderate consolidation to high swell when wetted under building loads. Differen- tial movement of foundations and floor slabs is likely if the residence is constructed directly on the undisturbed, natural clay soils. To reduce potential risk of differen- " tial movement and building damage, we recommend sub-excavation, moisture- treatment and recompaction of the subsoils. ln our opinion, a drilled pier founda- tion and structurally-supported floors are most positive for the proposed residence. The owner must accept the potential risk of movernent of shallow founda- tion systems and floor slabs. As discussed in the FOUNDATIONS and SLAB-ON- GRADE FLOOR sections, we recommend sub-excavation of the soils to a depth of at least 3 feet below bottom of footings and slabs to reduce risk of differential movement and enhance potential perlormance. The structuralfill concept is shown on Figure 6. The bottom of the sub-excavated areas should extend later- ally at least 2 feet beyond the perimeters of the footings and slabs. The bottom of the sub-excavated areas should be scarified to a depth of at least I inches, mois- ture-treated and compacted. We recommend re-using the excavated soils for structuralfill in sub-exca- vated areas, provided they are free of organics, debris and rocks larger than 3 inches in diameter. Structuralfill should be moisture-treated to within 2 percent of optimum moisture content and compacted to at least gB percent of Standard Proc- tor (ASTM D 698) maximum dry density. Additionalwater required to increase the existing soil moisture content to the specified moisture content should be uniformly mixed into the fill soil prior to compaction. We recommend a maximum loose lift thickness of B inches. The actual thickness of fill lift that can be properly com- pacted will depend on the type of compaction equipment. ln order for the proce- dure to perform properly, close control of structural fill placement to specifications TOM PROVOST PROVOST RESIDENCE PROJECT NO. GSo621 9.000-120 C:\Users\athate\Box\Projects\ctenwood Springs - Projects\GsO6219.000\120\2' Reports\GS06219.000 120 Rl.docx 5 ffi is required. Our representative should be called to check compactíon and mois- ture content of the structuial fill during placement. FOUNDATIONS We judge there is high risk of differential movement and damage if shallow footing foundations are supported directly by the undisturbed natural soils at this site. ln our opinion, a drilled pier foundation system is appropriate for the resi- dence. The residence can be constructed on footing foundations, provided the natural soils are sub-excavated to a depth of at least 3 feet below bottom of foot- ings and replaced with moisture-treated, structuralfill. Recommendations for sub- excavation and structural fill in the Sub-Excavation section should be followed. The owner must accept the additional risk of movement and building damage in- herent with footing foundations at this site. An alternative to enhance foundation performance, as compared to footings, would be construction of a reinforced con- crete mat foundation on the structural fill. CTl/Thompson, lnc. can provide criteria for a reinforced concrete mat foundation if requested. Recommended design and construction criteria for drilled piers and footing foundations on structuralfill are presented below. Dri lled Piers Piers should be designed for a maximum allowable end pressure of 12,000 psf and an allowable skin friction o'f 1,200 psf. Skin friction should be neglected for the upper 10 feet of pier below grade beams. Piers should be designed for a minimum deadload pressure of 10,000 psf based on pier cross-sectional area. lf this deadload can- not be achieved through the weight of the structure, the pier length should be increased beyond the minimum values specified in the next paragraph. Piers should have a minimum length of 30 feet. lt would be prudent for drilled piers to be designed with a minimum diameter of at least 1 2 3 TOM PROVOST PROVOST RESIDENCE PROJECT NO. cS06219.000-l20C:\Users\athate\Box\Projects\Gtenwood Springs - Projects\GSO6219.000\120\2. Reports\GS06219.000 12O Rl.docx 6 ffi 4. 5 1.2 inches. The pier length should not exceed about 30 times the pier diameter. Piers should be reinforced their full length with at least three No. 6 (19. mm), Grade 60 (420 Mpa) reinforcing bars (or their equívalent) toresist tension in the event of swelling. Reinforcement should extend into grade beams and foundation wàlls There should be a 6-inch (or thicker) continuous void beneath allgrade beams and foundation walls, between piers, to allow potential.. swell of heave of the soils. Piers should be carefully cleaned prior to pracement of concrete. Ground water was not encountered during this investigation. werecommend a "drill-and-pour" procedure for pier installation. con- crete should be ready on-síte and placed in the pier holes immedi- ately after the holes are drilled, cleaned and observed by our repre- sentative. concrete placed in pier holes should have sufficient slump to fillthepier hole and not hang on the reinforcement or the sides of the cas-ing during extraction (if used). we recommend a slump in the rangeof5toTinches. 6 7 Formation of mushrooms or enlargements at the top of piers should be avoided during pier drilling and subsequent construction opera- tions. lnstallation of drilled piers should be observed by a representative of our firm to identify the proper bearing strata and check pier length and plumb. Footinqs on Structural Fill The residence can be constructed on footing foundations supported on a 3-feet thick mat of moisture-treated structuralfill, provided the owner accepts the increased risk of difierential movement and poten- tial for building damage. 8. I 1 2 toru pnovosi PROVOST RESIDENCEPROJECT NO. cS06219.000_120C:\Users\athate\Box\Projects\clenwood Spr¡ngs - Projects\c506219.OOO\'l2O\2. Reports\Gso62t9.000 i20 Rl.docx Footings on structuralfill can be sized using a maximum allowable bearing pressure of 3,000 psf. 7 ffi Continuous wall footings should have a minimum width of at least 16 inches. Foundations for isolated columns should have minimum di- mensions of 24 inches by 24 inches. Larger sizes may be required, depending upon foundation loads. 4.Grade beams and foundation walls should be well reinforced, top and bottom, to span undisclosed loose or soft soil pockets. We rec- ommend reinforcement sufficient to span an unsupported distance of at least 12 feeL 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 frost protection depth. SLAB-ON.GRADE FLOORS Floors in basements and garages in residences are often constructed as slabs-on-grade. The risk of differential movement and damage is high for slab-on- grade floors supported directly on the undisturbed natural soils at this site. lf the owner desires slab-on-grade floors, we recommend sub-excavation of at least 3 feet of the soils below slabs and replacement with moisture-treated, structural fill to enhance potential slab performance. Sub-excavation and structuralfill should be in accordance with the recommendations in the Sub-Excavation section. The most positive method to mitigate floor movement is construction of structurally- supported floors. We recommend the following precautions for slab-on-grade construction at this site. These precautions will not prevent movement from occurring; they tend to reduce damage if slab movement occurs. Slabs should be separated from exterior walls and interior bearing members with slip joints which allow free vertical movement of the slabs. 2. The use of underslab plumbing should be minimized. Underslab plumbing should be pressure tested for leaks before the slabs are TOM PROVOST PROVOST RESIDENCE PROJECT NO. cs062l 9.000_120c:\Users\athate\Box\Projects\ctenwood Springs - projects\Gs06219.000\12O\2. Reports\G506219.000 120 Rl.docx 3. 5 1 I ffi 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 building. These slabs should be well-reinforced to function as independent units. Movements of these slabs should not be transmitted to the buílding Frequent controljoints should be provided, in accordance with Amer- ican Concrete lnstitute (ACl) recommendations, to reduce problems . associated with shrinkage and curling. STRU CTURALLY.SU PPORTED FLOORS Structurally-supported floors are a positive method to enhance potential performance of floors as compared to slabs-on-grade. Structurally-supported floors are supported by the foundation system with a crawl space between the floor and soil surface. The required air space depends on the materials used to construct the floor and the potential expansion of the underlying soils. Building codes normally require a clear space of at least 1B inches between exposed earth and untreated wood floor components. We recommend increasing the clear space to at least 24 inches to allow for heave of the ground under the floor. For non-or- ganic systems, we recommend a minimum clear space of 12 inches. This mini- mum clear space should be maintained between any point on the underside of the floor system (including beams, plumbing 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 ex- cavation. This configuration may not be achievable for some parts of the installa- tion. 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. TOM PROVOST PROVOST RESIDENCE PROJECT NO. cs06219.000_120C:\Users\athate\Box\Projects\Glemood Spr¡ngs - projects\cS06219-000\120\2. Reports\GSo6219.0oO 120 Rl.docx 3 4 I ffi Control of humidity in crawl spaces is important for indoor air quality and pedormance 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 below accessible subfloor areas. The vapor retarder/barrier should be sealed at joints and attached to concrete foundation elements. FOUNDATION WALLS Many factors affect the values of the design lateral eañh 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 wall where negligible or very little deflection will occur, an "at-rest" lateral earth pressure should be used in design. For walls that can deflect or rotate 0.5 to 1 percent of wall height (depending upon the backfill types), lower lateral earth pressures approaching the "active" condition may be appropriate. Our experíence indicates typical basement walls in residences deflect or rotate slightly under nor- mal design loads, and that this deflection results in satisfactory wall performance. Thus, the earth pressures on the walls will likely be between the "active" and "at- rest" conditions. lf the on-site soils are used as backfill and the backfill is not saturated, we recommend design of below-grade walls at this site using an equivalent fluid den- sity of at least 50 pcf. This value assumes some deflection; some minor cracking of walls may occur. lf very little wall deflection is desired, a higher design value is appropriate. For the on-site soils, an at-rest lateral earth pressure of 60 pcf, and a passive lateral earth pressure of 270 pcf can be used. u a Wall Backfill Proper placement and compaction of foundation backfill is important to re- duce infiltration of surface water and settlement of backfill. Foundation wall backfill TOM PROVOST PROVOST RESIDENCEPRoJECT NO. GSo621 9.000_120L:ìusers\athate\8ox\Projects\clenwood Spr¡ngs - projects\GSO6219.0OO\120\2- Reports\Gs06219.000 120 Rl.docx 10 ----nrr---ffi: must be moisture-treated and compacted to reduce settlement. However, com- paction of the backfill soils adjacent to concrete walls may result in cracking of the wall. The potential for cracking can vary widely based on many factors including the degree of compaction achieved, the weight and type of compaction equipment utilized, the structural design of the wall, the strength of the concrete at the time of backfill compaction. The natural clay soils can be used as backfill, provided they are free of rocks larger than 3-inches in diameter, organics, and debris. Backfill should be placed in loose lifts of approximately B inches thick or less, moisture-conditioned to within 2 percent of optimum moisture content, and compacted. Thickness of lifts will likely need to be about 6 inches if there are small confined areas of backfill, which limít the size and weight of compaction equipment. We recommend backfill soils be compacted to g5 percent of maximum standard Proctor (ASTM D 6g8) dry density. Moisture content and density of the backfill should be checked during place- ment by a representative of our firm. Observation of the compaction procedure is necessary. Testing without observation can lead to undesirable performance. Backfill that will support exterior slabs requires strict adherence to specifications. Even well-placed backfill will settle 0.5 to 1 percent of total backfill thickness. SUBSURFACE DRAINAGE Water from rain, snow melt and surface irrigation of lawns and landscaping frequently flows through relatively permeable backfill placed adjacent to a resi- dence and collects on the surface of less permeable soils occurring at the bottom of foundation excavations. This can cause wetting of foundation soils, hydrostatic pressures on below-grade walls and wet or moist conditions in below-grade areas after construction. TOM PROVOSTPRovosr REstDENcEPRoJEcr No. GSo621 9.ooo-120ui\Users\athate\Box\Projects\Glenwood Spr¡ngs - Projects\cs06219.OOO\120\2. Reports\GSO6219.OOO 1zO Rl.docx 11 ffi The exterior 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 back- fill operations to prevent damage to drainage composites. The drain should lead to a positive gravity outlet, or to a sump pit where water can be removed by pump- ing. Gravity outlets should not be susceptible to clogging or freezing. lnstallation of clean-outs along the drain pipes is recommended. Typicalfoundation drain concepts are presented on Figures 7 and B. SURFACE DRAINAGE Surface drainage is critical to the performance of foundations, floor slabs and concrete flatwork. lnfiltration of water can cause heave of expansible soils and increase the potential for building movement. Recommendations in thÍs report are based on effective drainage for the life of the structure and cannot be relied upon if effective drainage is not maintained. Appendix A contains our recommen- dations for surface drainage, irrigation, and maintenance. CONCRETE Concrete in contact with soil can be subject to sulfate attack. We measured water-soluble sulfate concentrations in 2 samples of the soils from our borings at this site. Concentrations were measured at 0.01 and 0.08 percent. For this levet of sulfate concentration, ACI 332-08 Code Requirements for Resídential Concrete indicates there are no special requirements for sulfate resistance. ln our experience, superficial damage may occur to the exposed surfaces of highly permeable concrete, even though sulfate levels are relatively low. To con- trol this risk and to resist freeze-thaw deterioration, the water-to-cementitious ma- terials ratio should not exceed 0.50 for concrete in contact with soils that are likely to stay moist due to surface drainage or high-water tables. Concrete should have TOM PROVOST PROVOST RESIDENCEPROJECT NO. cs06219.000_120u:ìusers\athate\Box\Projects\ctenwood Springs - projects\Gso62l9.000\12o\2. Reports\Gso6219.000 I20 Rl.docx 12 ffi a total air content of 6% +l- 1.5%. We recommend all foundation walls and grade beams in contact with the subsoils be damp-proofed. 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 tools which geotechnical engineers use are generally empirical and must be tem- pered by engineering judgment and experience. Therefore, the solutions or recom- mendations presented in any geotechnical evaluation should not be considered risk-free and, more importantly, are not a guarantee that the interaction between the soils and the proposed structure will perform as desired or intended. What the engineering recommendations presented in the preceding sections do constitute is our estimate, based on the information generated during this and previous evalua- tions and our experience in working with these conditions, of those measures that are necessary to help the building perform satisfactorily.' This report was prepared for the exclusive use of the client for the purpose of providing geotechnical design and construction criteria for the proposed project. The information, concluèíons, and recommendations presented herein are based upon consideration of many factors including, but not limited to, the type of struc- tures proposed, the geologic setting, and the subsurface conditions encountered. The conclusions and recommendations contained in the report are not valid for use by others. Standards of practice continuously change in the area of geotech- nical engineering. The recommendations provided in this report 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. TOM PROVOSTPROVOST RESIDENCF ËitÏ"i:"Î"ltl'3;3,ì3,1íJ"1!131"Í13"0 .',,^ss - projecrs\cso62.r e.'oo\i 2o\2. Reports\cso62.r e.0oo i 20 R1 .docx l3 =ffi LIMITATIONS Our exploratory borings provided a reasonable estirnate of subsurface con- ditions for the currently proposed project. Variations in the subsurface conditions not indicated by the borings will occur. \ This investigatíon 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. tf we can be of further service in discussing the contents of this re- port, please call * ilf c 2ol-a3 V e ion R o tiNg, P.E ncipal Engineer :JM:at TOM PROVOSTPROVOST RESIDENCE ã'i'ii"Î"1Ï3t3î9å?J:,"t3gÍí3". sprinss. projects\cs0621e.ooo\120\2. Repors\cso621s.o'o i20 Ri.docx 14 tt ffi SCALE: 1o = 1'OO0' Vicinity Map Tom ProvostProvost Resldenoe Project No. GSO621 9.OOO-1 20 Fis. 1 fs '! ffi SCALE:1n = 100' Tom ProvostProvost ResldenceProject No. GSO621 9.OOO-1 20 LEGEND: TH-l APPROXIMATE LOCATION OFO EXPLORATORY BORING. Locations of Exploratory Borings Fig. 2 : ! I i !I I ¡ t t .{ j q I I I i i ì - 'i i 1 t-lrJultL z tr uJul TH-1 8t.7545 7,545 7,540 7,535 7,530 7,525 7,520 7,515 7,510 7,505 7,500 .IOM PROVOST PROVOST RESIDENCEPROJECT NO. cso621ó.OOO_1 20 TH-2 E|.7530 50i8 36t12 26112 50/9 50t4 37112 37t12 40112 5014 50/5 7,545 7,540 7,535 7,530 7,525 7,520 7,515 7,510 7,505 50/6 5014 a / / / / / / / / / / / / a a I I 2 a a a a a I LEGEND: CLAY, SANDY, OCCASIONAL GRAVEL, LENSES OF CLAYEY SAND, MEDIUM STIFF TO VERY STTFF, MOTST, BROWN. (CL, SC) GRAVEL, CLAYEY, OCCASIONAL CLAY LAYERS, DENSE TO VERY DENSE, MOIST, BROWN. (GC) DRIVE SAMPLE. THE SYMBOL 36/12INDICATES 36 BLOWS OF A 14O.POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2,s-INCH O.D. SAMPLER 12INCHES. DRIVE SAMPLE.THE SYMBOL 50/6 INDICATES 50 BLOWS OF A 14o-POUND HAMMER FALLING 30 INCHES WERE REQUIRËD TO DRIVE A 2.o-INCH O.D. SAMPLER 6 INCHES. NOTES: EXPLORATORY BORINGS WERE DRILLED ON MARCH 28,2018 WITH 4-INCH DIAMETER, SOLID.STEM AUGER AND A TRACK-MOUNTED DRILL RIG. 2. LOCATIONS AND ELEVATIONS OF EXPLORATORY BORINGS ARE APPROXIMATE. 3. FREE GROUNDWATER WAS NOT FOUND IN OUR EXPLORATORY BORINGS AT THE TIME OF DRILLING. 4. EXPLORATORY BORINGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS CONTAINED IN THIS REPORT, ffi þ I t--ul t-uLL zo¡- ulJ uJ 5014 7,500 Summ ary Logs of Exp!oratóryttorl ngs Frc 3 ffi 7 b Â 4 3 2 0 -J zo-4 Øz Àx-5t¡lszQ-o U)ct) uJÉ.O- -7 =oo -8 0.1 10 DRY UNITWEIGHT= MOISïURE CONTENT= 102 8.7 Swell Gonsolidation Test Results 100 PCF APPLI Somple of From TH-1 AT 9 ED PRESSURE - KSF CLAY, SANDY o/o . NO MOVEMENT DUE TO WETTINGtttt|t t lltl¿ \ ) JoM pnovosr Ë R3y33ì,i"=låîîT 1,,1, oo0.,, o FEET 1.0 FIG.4 ffi "/( ì. ) \ \ \ \ \ 7 6 5 4 .1 2 0 -J -4 -5 zo U)z o-X ]¡JszIU'U,u¡ É.o-Eo C) -6 0.1 APPLI Somple of From ED PRESSURE . KSF 10 DRY UNITWEIGHT= MOISTURE CONTENT= 113 16.6 Swell Gonsolidation Test Results 'r00 PCF % CLAY, SANDY (CL) TH-2 AT 9 FEET TOM PROVOST PROVOST RESIDENCErxoJECT NO. cs06219.000-120 1.0 FIG.5 *¡¡:t 1: ffi BELOW-GRADE WAII. SUP JO]NÏ FOOTNG OR PAD+ 2, MINIMUM =Ð =z. =¡ Structural Fill ConceptJOM PROVOSTenovost Res¡oeñcerroject No. Gso621 9.OOO_1 20 Fig.6 :j SLOPE 2-3' ATTACH POLYEÍ}IYLENE SHEENNG TO FOUNDANON WALI MIRADRAIN G2OON OR EOUIVALENT BELOW-GRADE WALI CRAWL SPACE OR VOID SLOPE OSHA PER COVER E¡¡NRE WIDT}I OF GRAVEL WÍTH NON-WOVEN ceorornue FABRIC (MlRAn l+ıñ-on eoutvAt"ENT). ROORNG FELT lS Al'l ACC EPTABLE ALTERNATIVE. VOID 2, MIN. DRILLED PIER 4-INCH DIAMETER PERFORATED RIGID DRAIN PIPE. T}lE PIPE SHOULD BE PTACED IN A TRENCH W[T}I A SLOPE OF AT rEASr 1/4-INCH DROP PER FOOT OF DRAIN. ENCASE PIPE tN 1/2' -rO 1-1/2' TVASHED GRAVEL. RLL ENNRE TRENCH WIH GRAVEL ÐCTEND GRAVEL LA'ÍERALLY TO VOID AND AT LEAST 1,/2 HEIGHT OF VOID. NOTES: 1.) THE BorToM oF THE DRqrN sHouLD BE AT LEAsr 2 tNcHEs BELow BorroM oF votD AT THE HIGHEST POINT AND SLOPE DOWNWARD TO A POSÍTIVE GRAVITY OTJTTET ORTO A SUMP WHERE WATER CAN BE REMOVED BI PUMPING. 2.) I9 HELe coNTRoL TltE HUMtDlry tN THE cRAwL spAcE, A MINIMUM to-Mll POLYEfl.ÍYLENE VAPOR RETARDER MAY BE PI.ACED OVER-THE CRAWL SPACE SOILS, AT THE BUILDER'S OPTON. THE RET'ARDER SHOULD BE ATTACHED TOCONCREÍE FOUNDATON ELEMENTS AND EXTEND UP FOUNDATION WALIS ATLEqST 8 ¡NCHES ABOVE TOP OF VOID. OVERLAP JOINTS 3 FEEr AND SEAL. SEE NOTE 2 Foundation Wall Drain Concept SÎRUCTRi\L FLOOR roM PROVOSTpRovost nesroeñceeroject No. Gso621 9.OOO_1 20 Fig. 7 OSHA COVER ENTRE WIDTH OF SLOPE PREFABRICATED DRAINAGE COMPOSrrE (MTRADRATN 6000 oR EOUTVAT.ENT) ATTACH PI.ASNC SHEENNG TO FOUNDATION BELOW-GRADE WALI SUP JOINT FOOÏNG OR PAD s PER ! : GMVEL WTÍH NON-WOVEN GEOTEKNLE FABRIC (MIRAFI 14ON OR EOUTVALENT). ROORNG FELT IS AN ACCEPTABLE ALTERMTT\E. 2 MINIMUM 8" MINIMUM OR BEYOND 1:1 SLOPE FROM BOTÏOM OF FOOTNG (WHTCHEVER rS GRF^TER) 4-INCH DIAMETER PERFORATED RIGID DRAIN PIPE.THE PIPE SHOULD BE PI-ACED IN A TRENCH WTN.IA SLOPE OF AT rEASr 1/S-!NCH DROP pER FOOT OF DRAIN. ENCASE P¡PE IN GRA\€1. ÐfiEND AND AT L.EAST ENTRE TRENCH 1/2'TO 1-1/2'WASHED GRAVEL I.ATERALLY TO FOOTNG1/2 HEtc¡-ff OF FOOTNG. RLL WTTH GRAVEL. NOTE: Il^Ejg¡o-lt oF THE DRAIN sHouLD BE AT Ltr\sr 2 tNcHES BELow BorToM oF lygrlNG 4T THE HtcHESr pOtNT AND SLOPE DOWNWARD TO A POSTTTVE cRAVtryUUILLT OR TO A SUMP WHERE WATER CAN BE REMOVED Ð/ PUMPING. Foundation Wall Drain Conceptr9M PROVOSTtsHOVOST RESIDENCErro.¡ect No. Gso621 9.OOO_1 20 Fig.8 TABLE ISUMMARY OF LABOR.ATORY TESTINGPROJECT NO. c506219.000-120- SWELL MEASURED WITH lOOO PSF APPLIED PRESSURE, OR ESTIMATED IN-SITU OVERBURDEN PRESSURE.NEGATIVE VALUE INDICATES COMPRESSION.ffiCLAY, SANDY (CL)CLAY. SANDY (CL)CLAY. SANDY ICL\GRAVEL. CLAYEY (GC)GRAVEL, CLAYEY (GC)SAND. CLAYEY {SC)SANDYDESCRIPTIO}¡93151078a1SSINGl. 200ìIEVE(%)PIt{I0.0100.080SOLUBLESULFATES(%\250000SWELLPRESSURE(PSF)1 000APPLIEDPRESSURE(PSF)1 000SWELLSWELL(o/o\8.40.0PLASTICITYINDËX(%\21ATTERBERG LIMITSLIQUIDLIMIT(%\40DRYDENSITYIPCF)10298113111MOISTURECONTENT(%\o.l12.73.11 0.516.6DEPTHIFEET) ]41414'f94IIEXPLORABORINGTORYTH.1TH-1TH.1rH-2TH-11H-2TH-2Page 1 of 1 ffi APPENDIX A SURFACE DRAINAGE, IRRIGATION AND MAINTENANCE Ëiq$"T$Ì*iîitti-p"Í*.1"0 "onnn" - prorects\cs0621s.000\,20\2. Reporrs\cso621e.oo' i20 Ri.docx *il SURFACE DRAINAGE' IRRIGATION AND MAINTENANCE Performance of foundations and concrete flatwork is influenced by the moisture conditions existing with in the foundation soils. Surface drainage should be desig ned to provide raPid run off of surface water away from the proposed res- idence. ProP er surface drainage and irrigation practices can help control the amount of su r'Íacewater 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 fou ndation and avoidance of irrigation near the foundati on also helP to avoid exces sive wetting of backfill soils, which can lead to increased backfíll settlement and possibly to higher lateral earth pres- sures, due to increased weight and reduced strength of the backfill. CTL Thomp- son, lnc. recommends the followino orecautions. The home owner should main- tain surface rainaoe and. if an i svstem is installed, it should su bstan- tiallv nform to these recommend ations. Wetting or drying of the open foundation excavations should be avoided. Excessive wetting of foundation soils before, during and after construction can cause heave or soften fill and foundation soils and re- sult in foundation and slab movements. Proper surface drainage around the residence is critical to control wetting. 2. The ground surface surrounding the exterior of the residence should be sloped to drain away from the buildíng in all directions. We recom- mend a minimum constructed slope of at least 12 inches in the first 10 feet (10 percent) in landscaped areas around the residence, where practical. Construction of retaining walls and decks adjacent to the residence should not alter the recommended slopes and surface drainage around the residence. Ground surface under the deck should be compacted and slope away from the residence. A 1O-mil plastic sheeting and land- scaping rock is recommended above the ground under the decks to re- duce water dripping from the deck causing soil erosion and/or formingf depressions under the deck. The plastic sheeting should direct water away from the residence. Retaining walls should not flatten the surface drainage around the residence and block or impede the surface runoff. Roof downspouts and drains should discharge well beyond the limits of all backfill. Splash blocks and/or extensions should be provided at alldownspouts so water discharges onto the ground beyond the backfill.we generally recommend against burial of downspoút discharge. tm nce of own ctices cannot be e on sho lim the 1 4 3 iili,.$i:r,.+j,""",îi.*".,3r"#:". Spr¡ngs - Projects\c506219.OOO\í2O\2. Reporrs\GSO62l9.0OO l20 Rl.docx A-l linmal Land scaping should belihood of s carefully designed and maintained to minimize irrigation. Plants Placed close to foundation walls should be limited to those with low moisture requirements. lrrigated grass should not be located within 5 feet of the foundation. Sprinklers should not discharge within 5 feet of founda- tions. Plastic sheeti ng should not be Placed beneath landscaPed areas adjacent to foundation walls or grade beams.Geotextile fabric will in- hibit weed grovrrth yet still allow natural evapo ration to occur 5. TOM PROVOST PROVOST RESIDENCE ii8jlÎ"1Ï3;ocì3å?J:*t3åÍÍ3,d sprinss . projects\G5062re'000\120\2' Rêports\Gs062is.ooo 120 Rl.docx The design and construction criteria for foundations and floor system alternativês were compiled with the expectation that all other recom- mendations presenteO'¡n tf,it report reiated to surface and subsurface drainage, landscaping irrigationi backfill compaction, etc. will be incor- porated into the pio¡eit. lfis critícal that all recommendations in this re- port are followed. A-2