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HomeMy WebLinkAboutSubsoil Studyffi CTLITHOMPSON YEARS FOUNsEÐ $N T97r CTL I THOMPSONrc GEOTECHNICAL ENGINEER¡NG INVESTIGATION CLUBHOUSE AND POOL HIGH ASPEN RANCH 491 HIGH ASPEN DRIVE GARFIELD COUNTY, COLORADO Prepared For: GREEN LINE ARCHITECTS 64 North 4th Street, Suite 5 Carbondale, CO 81623 Project No. GS06546.000-1 25 April16,2021 234 Center Drive I Glenwood Springs, Colorado 81601 Telephone: 970-945-280S Fax: 970-945-741 1 :lrrrLÜrrtrn:ttttIÜ;rITI ffi TABLE OF CONTENTS scoPE......., SUMMARY OF CONCLUSIONS SITE CONDITIONS PROPOSED CONSTRUCTION SITE GEOLOGY AND GEOLOGIC HAZARDS.. SUBSURFACE CONDITIONS........... SITE EARTHWORK........ Excavations Subexcavation and Structu ral Fi11........................ Foundation Wall Backfill Footings on Structural Fiil .,........... Drilled Piers........,........... SLAB-ON-GRADE CONSTRUCTION ........... STRUCTU RALLY.SUPPO RTED FLOORS.............. FOUNDATION WALLS.... SUBSURFACE DRAINAG8........,...... EARTH RETAINING WALLS. POOL CONSTRUCTION ......, SURFACE DRAINAGE..., ...10 ...11 12 13 14 15 15 16 17 17 18 19 CONCRETE CONSTRUCTION OBSERVATIONS STRUCTURAL ENGINEERING SERVICES GEOTECHNICAL RISK LIMTTATTONS ................. FIGURE 1-VICINITYMAP FIGURE 2 _ AERIAL PHOTOGRAPH FIGURE 3 - PROPOSED CONSTRUCTION FIGURE 4 _ SUMMARY LOGS OF EXPLORATORY PITS AND BORINGS FIGURES 5 THROUGHT - SWELL-CONSOLIDATION TEST RESULTS FIGURE 8 - GRADATION TEST RESULTS FIGURES 9 AND 1O - FOUNDATION WALL DRAIN CONCEPTS TABLE I _ SUMMARY OF LABORATORY TESTING GREEN LINEARCHITECTS NEW CLUBHOUSE AND POOL PROJECT NO. GSo6546,000-{25 1 '........,.1 2 3 4 5 Þ 6 6 7 III ffi SCOPE CTL I Thompson, lnc. has completed a geotechnicalengineering investiga- tion for the clubhouse and swimming pool proposed at 491 High Aspen Drive within High Aspen Ranch in Garfield County, Colorado. We conducted this investi- gation to evaluate subsurface conditions at the site and provide geotechnicalengi- neeríng recommendations for the planned construction. The scope of our investi- gation was set forth in our Proposal No. GS 20-0323. our report was prepared from data developed from our field exploratíon, laboratory testing, engineering analysis, and our experience with similar conditions. This report includes a de- scription of the subsurface conditions observed in our exploratory pits and explora- tory borings and provides geotechnical engineering recommendations for design and construction of foundation and floor systems and details influenced by the subsoils. We should be provided with architectural plans, as they are further devel- oped, so we can provide geotechnical/geo-structuralengineering input. A sum- mary of our conclusions is below. SUMMARY OF CONGLUSIONS Subsurface conditions encountered in our exploratory pits and ex- ploratory borings at the site generally consisted of about B ínches of aggregate base course and nil to 2 feet of existing fill, underlain by natural sandy clay to the total explored depth of 35 feet. Free groundwater was not found in our pits and borings during our subsur- face investigation. The natural sandy clay at this site has potentialfor moderate amounts of expansion when wetted. Without mitigation, expansion of the clay soil is likely to result in differential heave and damage to the building. We judge the clubhouse can be constructed on a footing foundation, provided the soils are subexcavated to a depth of at least 3 feet below footíngs and replaced with moisture-treated, structural fill. A drilled pier foundation is a positive alternative that would further mitigate risk of building movement. GREEN LINEARCHITECTS CLUBHOUSEAND POOL PROJECT NO. GS06sd6.000-125 1 2 1 ffi lf a slab-on-grade floor will be constructed in the building, we recom- mend subexcavation of the soils below the slab to a depth of at least 3 feet and replacement with moisture-treated, structural fill to miti- gate potential heave of the slab. A minimum structuralfillthickness of 2-feet is recommended below the pool deck, patios, and side- walks. A positive alternative to reduce risk of differential heave would be construction of a building floor that is struclurally-supported by the foundation system with a crawlspace below, Soils below the swimming pool shell should be subexcavated to a depth of 3 feet and replaced with moisture-treated structural fill. ln- stallation of a drain system below the pool will be criticalfor perfor- mance. 5.lf a structurally-supported floor system with a crawl space is utilized for the building, we recommend a foundation wall drain be con- structed around the perimeter of the crawl space. Surface grading should be designed and constructed to rapidly convey surface water off concrete flatwork and away from the building. SITE CONDITIONS The subject site is located at 491 High Aspen Drive (a.k.a. Lot 31, High As- pen Ranch) within High Aspen Ranch in Garfield County, Colorado. A vicinity map with the location of the site is included as Figure 1. An irrigation ditch trends down to the southwest along an alignment that is uphill (north) of the subject site. A club- house, swimming pool, tennis courts, and paved parking area were prevíously lo- cated at the site. These structures are shown on Figure 2, whích is an aerial pho- tograph from June 2017. These structures were deconstructed during the time be- tween excavation of our exploratory pits and drilling of our exploratory borings. The new clubhouse and swimming pool are planned at the location of the previous tennis courts. This area has been graded as a relatively flat bench. A photograph of the proposed building site at the time of our exploratory drilling is below. GREEN LINE ARCHITECTS CLUBHOUSE AND POOL PROJECT NO. GS06546.000-l 25 3 4 2 | '1 ,:.. ili ffi Looking southeast across site with drill rig atTH-Z PROPOSED CONSTRUCTION Architectural plans for the proposed clubhouse and swimming pool were preliminary at the time of our geotechnical engineering ínvestigation. We were pro- vided with a site plan and floor plan by Green Line Architects (dated April12, 2021). The clubhouse is contemplated as a one-story building with the footprint shown on Figure 3. We expect wood and steel-frame constructíon, The current plans suggest a slab-on-grade floor with no below-grade areas, such as a crawl space or basement. Foundation loads for this type of construction are expected to be less than 3,000 pounds per linear foot of foundation wall with maximum interior column loads of less than 30-kips, The swimming pool is proposed south of the building. Details showing the planned swimming pool construction, including depth, were not developed. Signifi- cant areas of concrete pool deck, patio, and sidewalk are proposed adjacent to the building and swimmíng pool. lt appears that structural fíll as thick as about I feet is planned below the south and east sides of these areas. The site plan indicates a GREEN LINE ARCHITECTS CLUBHOUSE AND POOL PROJECT NO. GS06546.000-12s 3 ffi two-tiered earth retaíning wall will be needed to provide lateral support for the structuralfill. The specific earth retaining wallsystem has not been determined. We should be provided with architectural plans, as they are further developed, so we can provide geotechnical/geo-structural engineering input. SITE GEOLOGY AND GEOLOGIC HAZARDS As part of our geotechnical engineering investigation, we reviewed geologic mapping by the colorado Geological survey (cGS) tifled, "Geologic Map of the Carbondale Quadrangle, Garfield County, Colorado", by Kirkham and Widmann (dated 2008). The mapping indicates that trachyandesite bedrock (Pliocene Epoch) is at or near the ground surface at the site. We did not encounter bedrock in our exploratory pits and exploratory borings. The natural sandy clay soils we found in our pits and borings are likely part of the undivided deposits of alluvium and colluvium (Holocene and Late Pleistocene Epochs) that are mapped to the west of the subject site. We also reviewed the CGS map "Collapsible Soils and Evaporite Karst Haz- ard Map of the Roaring Fork Valley, Garfield, Pitkin and Eagle Counties", by Jona- than L. White (dated 2002). This map indicates unconsolidated deposits in the ar- eas adjacent to the subject site. These deposits are described as including collu- vium, sheetwash, and alluvium. The map descriptions indicate these types of soils are geologically recent and typically loosely-packed, porous, and dry. These soil deposits are often prone to collapse when wetted, especially under applied building loads. Our laboratory testing on samples from our exploratory borings indicate the soils at this site have potential for expansion and not collapse. We judge that ex- pansion of the soils is the primary hazard for structures at the site. GREEN LINE ARCHITECTS CLUBHOUSE AND POOL PROJECT NO. GS06546.000-125 4 ffi SUBSURFACE CONDITIONS Subsurface conditions at the site were investigated by directing excavation of three exploratory pits (TP-1 through TP-3) and drilling three exploratory borings (TH-1 through TH-3) at the approximate locations shown on Figures 2 and 3. The pits were excavated with a trackhoe on February 10, 2021. Exploratory borings were drilled on April 8,2021 with solid-stem auger and a track-mounted drill rig. Exploratory excavation and drilling operations were directed by our representa- tives, who logged subsurface conditions encountered and obtained representative samples. Graphic logs of the soils encountered in our exploratory pits and explora- tory borings are shown on Figure 4. Subsurface conditions encountered in our exploratory pits and borings at the site generally consisted of about I inches of aggregate base course and nil to 2 feet of existing fill, underlain by natural sandy clay to the total explored depth of 35 feet. Free groundwater was not found in our pits and borings during our subsur- face ínvestigation. The pits were backfilled immediately after excavation opera- tions were completed. PVC pipe was installed in our borings to facilitate future checks of groundwater. Samples of the soils obtained from our exploratory pits and borings were re- turned to our laboratory for pertinent testing. Six samples of the sandy clay se- lected for one-dimensional, swell-consolidation testing exhibited 0.3 to 3.0 percent swell when wetted under an applied pressure of 1,000 psf. Gradation analyses on two clay samples indicated 31 percent gravel, 10 and 12 percent sand, and 59 and 57 percent silt and clay size material (passing the No. 200 sieve). Engineering in- dex testing on one sample showed high plasticity with a liquid limit of 54 percent and a plastic index of 30 percent. One sample of soil tested had a water-soluble content of 0.00 percent. Swell-consolidation test results are shown on Figures 5 through 7. Gradation test results are provided on Figure 8. Laboratory testing is summarized on Table l- GREEN LINË ARCHITECTS CLUBHOUSE AND POOL PROJECT NO. G506546.000-125 5 ffi SITE EARTHWORK Excavations We expect maximum excavation depths of less than 10 feet for the proposed constructíon, including the recommended 3-feet of subexcavation. Based on our subsurface investigation, excavations at the site can be made with conventionalex- cavating equipment. Sides of excavations need to be sloped or braced to meet lo- cal, state and federal safety regulatíons. The sandy clay soil at the site will likely classifo as a Type B soil based on OSHA standards governing excavations. Tem- porary excavation slopes that are not retained should be no steeper than 1 to 1 (horizontal to vertical) in Type B soils. Contractors are responsible for maintaining safe excavations. Contractors should ídentify the soils encountered and ensure that OSHA standards are met. Free groundwater was not encountered in our exploratory pits and borings. 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 temporary sump where water from precipitation and snowmelt can be removed by pumping. Subexcavatio n and Structural Fill It appears that structural fill as thick as about I feet is planned below the south and east sides of the pool deck and patio areas. These areas should be stripped of vegetation and organics, prior to placement of structural fill. Addition- ally, we recommend subexcavation of the soils to a depth of at least 3 feet below footings and floor slabs (if constructed) and below the swimming poolto mitigate the potentialfor soil expansion and heave-related damage. The subexcavation process should extend laterally at least 1 foot beyond the perimeter of the building GREEN LINE ARCHITECTS CLUBHOUSE AND POOL PROJECT NO. GS06s46.000-1 2s 6 ffi and swimming pool footprint. A minimum structural fill thickness of 2-feet is recom- mended below the pool deck, patios, and sidewalks. Structural fill to raise grades for exterior areas, and to reattain construction elevations in subexcavated areas, can consist of the natural sandy clay soils exca- vated from the site, provided they are free of rocks larger than 3 inches ín diame- ter, organic matter, and debris. As an alternative, a CDOT aggregate base course can be imported to the site for use as structural fill. A sample of desired import soil should be submitted to our office for approval. Structural fill soils should be moisture-condítioned to within 2 percent of op- timum moisture content, placed in loose lifts of 8 inches thick or less, and com- pacted to at least 98 percent of standard Proctor (ASTM D 698) maximum dry density. Moisture content and density of structural fill should be checked by a rep- resentative of our firm during placement. Observation of the compaction procedure is necessary. Foundation Wall Backfill Proper placement and compaction of foundation wall backfill is important to reduce infiltration of surface water and settlement from consolidation of backfill soils. This is especially important for backfill areas that will support concrete slabs, such as the pool deck, patios, and sidewalks. The natural sandy clay soil can be used as backfill, provided it is free of rocks larger than 3-inches in diameter, organ- ics, änd debris. 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 95 percent of maximum standard Proctor (ASTM D 698) dry GREEN LINE ARCHITECTS CLUBHOUSE AND POOL PROJECT NO. GSo9546.000-125 7 ffi density. Moisture content and density of the backfill should be checked by a repre- sentative of our firm during placement. Observation of the compaction procedure is necessary. FOUNDATIONS Our laboratory testing indicates the natural sandy clay at this site has po- tentialfor moderate amounts of expansion when wetted. Without mitigation, ex- pansion of the in-situ clay soil is likely to result in differential heave and damage to the building. We judge the clubhouse can be constructed on a footing foundation, provided the soils are subexcavated to a depth of at least 3 feet below footings and replaced with moisture-treated, structuralfill. The subexcavation and structural fill should be in accordance with the Subexcavation and Structural Fill section. A drilled pier foundation is a positive alternative that would further mitigate risk of building movement. Drilled piers in expansive soils are designed and con- structed to resist uplift from heave by anchoring in the soils below the depth of po- tentialwetting. Typically, drilled foundations experience less movement, as com- pared to footing foundations. Design criteria for footings on structural fill and drilled piers are below. These criteria were developed from our analysis of field and laboratory data and our experience. Footinqs on Structural Fill Footings should be supported by at least 3 feet of moisture-treated, structuralfill in accordance with the Subexcavation and Structural Fill section. Footings on the structuralfill can be sized using a maximum net al- lowable bearing pressure of 3,000 psf. The weight of backfill soil above the footings can be neglected. GREEN LINE ARCHITECTS CLUBHOUSË AND POOL PROJECT NO. GS06546.000-1 25 1 2 I ffi Drilled Piers 2. GREEN LINË ARCHITECTS CLUBHOUSEAND POOL PROJECT NO. GS06s46.000-l 25 3 4 5. 6 3 4 1 A friction factor of 0.35 can be used to calculate resistance to sliding between concrete footings and the structuralfill soil. Continuous wall footings should have a minimum width of at least 16' inches. Foundations for isolated columns should have minimum di- mensions of 24 inchesby 24 inches. Larger sizes may be required, depending upon foundation loads. Grade beams and foundation walls should be well-reinforced. We rec- ommend reinforcement sufficient to span an unsupported distance of at least 12feet. 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. Piers should be designed for a maximum allowable end bearing pressure of 12,000 psf and an allowable skin friction value of 1,200 psf. Skin friction should be neglected for the portion of the upper 3 feet of pier below grade beams. Piers should be designed for a minimum deadload pressure of b00 psf based on pier cross-sectional area. lf this deadload cannot be achieved through the weight of the structure, the pier length should be increased beyond the minimum values specified in the next para- graph. The clay soil should be assigned a skin friction value of 1,200 psf for uplift resistance. Piers should have minimum lengths of 25 feet. The pier length should not exceed about 30 times the pier diameter. Piers should be reinforced to full length with at least three No.5 (16mm), Grade 60 (420 Mpa) reinforcing bars (or the equivalent)to resist a potential uplift tension. Reinforcement should extend into grade beams and foundation walls. A 6-inch continuous void will be required beneath all grade beams and foundation walls, between piers, to allow for potential soil heave and concentrate the deadload of the building on the piers. Piers should be carefully cleaned prior to placement of concrete. To reduce potentialfor problems during pier installation, we recommend 5 6 I ffi that a "drill and pour" construction procedure be used, in which con- crete is placed in the pier holes immediately after the holes are drilled, cleaned and inspected by our representative. Concrete should not be placed by free falf in pier holes containing more than 3 inches of water. Concrete should have sufficient slump to fill the pier holes and not hang on the reinforcement. We recommend a slump in the range of 5 to 7 inches. 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 CTL I Thompson, lnc. to identify the proper bearing strata. SLAB.ON.GRADE CONSTRUCTION The current architectural plans suggest a slab-on-grade floor in the building with no below-grade areas, such as a crawl space or basement. Significant areas of concrete pool deck, patio, and sidewalk are proposed adjacent to the building. We recommend subexcavation of the soils below the interior floor slab to a depth of at least 3 feet and replacement with moisture-treated, structural fill to mitigate po- tential heave of the slab. A minímum structural fill thickness of 2 feet is recom- mended below the pool deck, patios, and sidewalks. The subexcavation and struc- turalfill should be in accordance with the Subexcavation Stru ctural Fill section. A positive alternative to reduce risk of differential heave would be construc- tion of a building floor that is structurally-supported by the foundation system with a crawl space befow. Design and construction issues associated with structurally- supported floors include lateral loads on foundation walls and ventilation of crawl spaces. Additional discussion is in the STRUCTURALLY-SUPPORTED FLOORS section. 7 I I GREEN L¡NE ARCHITECTS CLUBHOUSE AND POOL PROJECT NO. G506546.000-1 2s l0 ffi We recommend the following precautions to enhance potential performance of slab-on-grade construction at this site. slabs should be separated from exterior walls and interior bearing members with slip joints that allow free vertical movement of the slabs. The use of underslab plumbing should be minimized. 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 cou- plings to slab supported appliances. Exterior concrete flatwork 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 building. Frequent controljoints should be provided, in accordance with Ameri- can Concrete lnstitute (ACl) recommendations, to reduce problems associated with shrinkage and curling. STRUCTURALLY.SUPPORTED FLOORS A positive alternative to reduce risk of differential heave would be construc- tion of a building floor that is structurally-supported by the foundation system with a crawl space below. Design and construction issues associated with structurally- supported floors include lateral loads on foundation walls and ventilation of crawl spaces. Building codes normally require a clear space of at least 18 inches be- tween exposed earth and untreated wood components of the structural floor. For non-organic systems, we recommend a minimum clear space of 12 inches. This minimum 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. 1 2 3. 4 GREEN LINE ARCHITECTS CLUBHOUSE AND POOL PROJECT NO. GS06546.000-125 11 ffi Utility connections, including water, gas, air duct, and exhaust stack connec- tions to appliances on structural floors should be capable of absorbing some deflec- tíon 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 maíntain the minimum clear space below all plumbing lines. lf trench- íng below the línes is necessary, we recommend sloping these trenches, so they discharge to the foundation drain. Control of humidity in crawl spaces is important for indoor air.quality and per- formance of wood floor systems. We believe the best current practices to control humídity involve the use of a vapor retarder or vapor barrier (10 mil minimum) placed on the soils below accessible subfloor areas. The vapor retarder/barríer should be sealed at joints and attached to concrete foundation elements. lt may be appropriate to installventilation systems that are controlled by humidistat. 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 de- sign 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. ln general, 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 that can deflect 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 experience indicates below-grade walls in typical buildings deflect or rotate slightly GREEN LINÈ ARCHIÎECTS CLUBHOUSE AND POOL PROJECT NO. cS06546.000-t 25 12 ffi under normal design loads, and that this deflection results in satisfactory wall per- formance. Thus, the earth pressures on the walls will likely be between the "active" and "at-rest" conditions. For backfill soils conforming with recommendations in the Foundation Wall Backfill section that are not saturated, we recommend design of below-grade walls at this site using an equivalent fluid density of at least 45 pcf. This value assumes deflection; some minor cracking of walls may occur. lf very little wall deflection is desired, a higher design value for the at-rest condition using an equivalent fluid pressure of 60 pcf is recommended. An equivalent fluid pressure of 300 pcf can be used for the "passive" earth pressure case. We should be provided with construc- tion plans, when available, so we can confirm these recommendations. SUBSURFACE DRAINAGE Water from precipitation, snowmelt, and irrigation frequently flows through relatively permeable backfill placed adjacent to a building and collects on the sur- face of less permeable soils at the bottom of the foundation excavation. This pro- cess can cause wet or moist conditions in below-grade areas, such as crawl spaces, and result in water pressure developing outside foundation walls. lf a structurally-supported floor system with a crawl space is utilized for the building, we recommend construction of a foundation wall drain around the perimeter of the crawl space. The exterior foundation wall 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 dis- charge via a positive gravity outlet or lead to a sump where water can be removed GREEN LINE ARCHITECTS CLUBHOUSE AND POOL PROJECT NO. GS06s46.000-12s 13 -F by pumping. Gravity outlets should not be susceptible to clogging or freezing. ln- stallation of clean-outs along the drain pipes is recommended. The foundation wall drain concepts are shown on Figures 9 and 10. EARTH RETAINING WALLS The site plan provided to us indicates a two-tiered earth retaining wall is proposed to provide lateral support for the structural fill below the south and east sides of the pool deck and patio area. lt appears the wall heights would be less than 6 feet. The specific earth retaining wallsystem has not been determined. ln our opinion, mechanically stabilized earth (MSË) structures could be utilized for these walls. An MSE structure consists of alternating layers of compacted structuralfill and geogrid reinforcement. Mobilized friction between the geogrid and structuralfill results in a zone of reinforced earth that essentially acts as a gravity retaining structure. The structure is faced with masonry blocks that are connected to the ge- ogrid reinforcement. The facing blocks prevent erosion and sloughing of the mate- rials at the front of the reinforced earth zone and create an aesthetically pleasing wall. The bottom course of blocks is typically placed on a layer of densely-com- pacted, granular structural fíll. A drainage layer is required behind the facing blocks. MSE structures are relatively tolerant to ground movement. CTL can assist with design of MSE structures for the project. We can pro- vide additional recommendations as architectural plans are further developed. A survey of existing and proposed grades will be important to facilitate design of the MSE system. GREEN LINE ARCHITECTS CLUBHOUSEAND POOL PROJECT NO. GS06546.000.1 25 14 ffi POOL CONSTRUCTION Details showing the planned swimming pool construction, including depth, were not developed at the time of our investigation. Considering the site surface conditions, we recommend that the pool footprint be excavated to a depth of at least 3 feet below the planned bottom of the pool shell. A 2.5-feet thick layer of moisture-treated, structuralfill in accordance with the Suhexcavation and Struc- tural Fill section should be placed. We recommend placement of a geotextile sepa- rator fabric above the structural fill. We recommend a 6-inch thick drain layer of screened rock with an embedded PVC pipe network between the separator fabric and the bottom of the pool. The drain pipes should lead to a collector pipe and a positive gravity outlet. In many cases, the bottom and sides of pool shells are integrated and con- structed with concrete or shotcrete. Backside forms for pouring concrete or shot- crete application for wall construction are often set away from the excavation sides. Flowable fill (low-strength concrete) is a positive choice to fill the void be- tween the back of the concrete or shotcrete walls and the excavation sides. The pool deck should be constructed on a 2 feet thickness of moisture-treated, struc- turalfill as outlined in the Subexcavation and structural Fill section. CTl/Thompson, lnc. should be províded with detailed pool plans, as they become available, so we can refine our recommendations. SURFACE DRAINAGE Surface drainage is critical to the performance of foundations, floor slabs, and concrete flatwork. Surface drainage should be designed to provide rapid run- off of surface water away from the proposed buildings and swimming pool area. Proper surface drainage and irrigation practices can help control the amount of surface water that penetrates to foundation levels and contributes to heave of soils GREEN LINE ARCHITECTS CLUBHOUSE AND POOL PROJECT NO. GSo6s46.000-1 25 l5 ffi that support foundations, slabs, and other structures. Positive drainage away from foundations and avoidance of irrigation near foundations 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. The ground surface surrounding the exterior of the building shourd be sloped to rapidly convey surface water off concrete fratwork and away from the building in all directions. We recommend a minimum constructed slope of at least 12 inches in the first 10 feet (10 per- cent) in landscaped areas around the building, where practical. Backfill around the foundation walls should be moisture-treated and compacted pursuant to recommendations in the Foundation Wall Backfill section. 4. The building should be provided with roof gutters and downspouts. The downspouts should discharge well beyond the limits of alr back- fill soils. splash blocks and/or extensions should be provided at all downspouts so water discharges onto the ground beyond the back- fill. we generally recommend against burial of downspout discharge. Where it is necessary to bury downspout discharge, solid, rigid pipe should be used, and it should slope to an open gravity ouflet. lrrigation should be limited to the minimum amount sufficient to main- tain vegetation; application of more water will increase likerihood of slab and foundation movements. Plants placed close to foundation walls should be limited to those with low moisture requirements. lrri- gated grass should not be located within S feet of the foundation. sprinklers should not discharge within 5 feet of foundations. plastic sheeting should not be placed beneath landscaped areas adjacent to foundation walls. Geotextile fabric will inhibit weed growth yet still al- low naturalevaporation to occur. CONCRETE Concrete in contact with soil can be subject to sulfate attack. We measured a water-soluble sulfate concentration of 0.00 percent in one sample of the natural 1 2. 3 GREEN LINE ARCHITECTS CLUBHOUSE ANÐ POOL PROJECT NO. GSo6546.0û0-t2s l6 ffi sandy clay from the site (see Table l), For low levels of soluble sulfate concentra- tion, ACI 332-08 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 wíth soils that are likely to stay moist due to surface drainage or high-water tables. Concrete should have a total air content of 60/o +l- 1.5%. CONSTRUCTION OBSERVATIONS We recommend that CTL I Thompson, lnc. be retained to provide construc- tion observation and materials testing services for the project. This would allow us the opportunity to verify whether soil conditions are consistent with those found during this investigation. lf others perform these observations, they must accept responsibility to judge whether the recommendations in this report remain appro- priate. lt is also beneficialto projects, from economic and praetical standpoints, when there is continuity between engineering consultation and the constructíon 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 structural fram- ing and foundation plans. We can also design earth retention systems. Based on our experience, cTL I Thompson, lnc. typically provides value to projects from schedule and economic standpoínts, due to our combined expertise and GREEN LINE ARCHITECTS CLUBHOUSE AND POOL PROJECT NO. G506546.000.12s 17 ffi experience with geotechnical, structural, and materials engineering. We can pro- vide a proposal for structural engineering services, 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 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 are not a guarantee that the interaction between the soils and that the proposed structure will lead to performance as desired or intended. The engi- neering recommendations in the preceding sections constitute our estimate of those measures necessary to help the building and structures perform satisfacto- rily. This report has been prepared for the exclusive use of the client for the pur- pose of providing geotechnical design and construction criteria for the proposed 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 conditions encoun- tered. The conclusions and recommendatíons contained ín the report are not valid for use by others. Standards of practice continuously change ín the area of ge- otechnical engineering. lf the proposed project is not constructed within three years, we should be contacted to determine íf we should update this report, GREEN LINE ARCHITECTS cluaHouse À¡¡D pooL PROJECT NO. GS06546.000-.t2s l8 ffi LIMITATIONS Our exploratory pits and exploratory borings provide a reasonable charac- terization of subsurface conditions below the site. Variations in the subsurface conditions not indicated by the pits and borings will occur. We should be provided with architectural plans, as they are further developed, so we can provide geotech- nical/geo-structural eng ineering input. This investigation was conducted in a manner consistent with that level of care and skill ordinarily exercised by geotechnical engineers currently practicing under simÍlar 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 re- port, please call. cTL I THOM ',{} , 7o>l D. Ke Manage JDK:abr GREEN LINE ARCHITECTS CLUBHOUSE AND POOL PROJECT NO. GS06A|6,000-1 2s l9 ffi 0 1000 2000 NOTE: SCALE: 1'= 2000' GREEN LINEARCHNECTS 49T H¡OHA,SPEN DñN'E SATELLITE IMAGE FROM GOOGLE EARTH (DATED JUNE 2017) Vicinity Map 491 Hìçh Ronch l)Ð N) PROJECT NO. GSO6546.OOO-1 25 Fls. 1 LEGEND: TP_1 APPROXIMATE LOCATION OFI EXPLoRAToRY PIT TH*1 APPROXIMATE LOCATION OFI EXPLORATORY BORING ffi 0 100 NOTE:SATELLITE IMAGE FROM GOOGLE EARTH (DATED JUNE 2017) Aerial SCALE¡ t'- f00' LINE ASPEN GREEN ARCHITECTS 4sl HloH DRIT/E TP_1TH_1 TH-3 TP-3TP_2 TH_2 PROJECT NO. cS06546.O00-1 25 Photograph Flg. 2 LEGEND: TP_1 APPROXIMATE LOCATION OFre EXPLoRAToRY PIT Ii.i i APPROXIMATE LOCATION OFåi EXPLORATORY BORING NOTE: îffi 0 20 40 SCÁLEI 1' = 4O' BASE DRAWING BY GREEN LINE ARCHTTECTS (DATED APRIL 12, 2021) ærçs¡¡ørAq4A' ¡ãtatþÁvt titÌ¡ c{rrå4¡l d, ' lt.l#æ¿AfJltttfÁ-_-L .o o'' o r3 lø!':g !øi e: t3 Tt".r-- 1_- TP*1 &Kæ¡oeÊ¡æa TP-2 E GREEN LINEARCHÍrECTÍ¡ 49I HISH ÂSPEN DRfi/E PROJECT NO. GSO6546.OOO-125 Proposed Construction Hs. I TH-3 rr g i-F A TP-3 H I n-¿ tä\ TP-1TP-2TP.3TH.1TH.2TH-322t1218t1217112't9t1231t12ffi05LEGEND:ffiñnFFNOTES:4. LOCATIONS OF EXPLORATORY PITS AND BORINGSARE APPROXIMATE,5, THESE LOGS ARE SUSJECT TO THE EXPI..AI'¡ATIONS,LIMITÁTIONS AND CONCLUSIONS CONTAINED IN fiISREPORT-AGGREGATE BASE COURSE.FILL, GRAVEL. CLAYEY, MÊDIUM DENSE,BROWN, GRAY.CtAÏ SANOY, MOIST. STIFF TO VERY STIFF,BASALT PIECES. SROWN, GRAY, RUSI, TAN.(cH, cL)INDICATES BULK SÂMPLE FROM Ð(CAVATEO SOILS.DRIVÊ SAMPLE. lHE SYMBOL 5O/I I,5 INDICA'ÍES 50 BLOWS OFA ''4GPOUND FÙqMMER FALLING 30 INCHES WERE REOUIREDTO DRIVÊ A z.s-INCH O.D. CALIFORNIA BARREL SAMPLÊR 1 1.5INCHES.EXPLOR,ATORY PfTS WËRE EXCAVATED W'IH ATRACKHOE ON FEBRUARY 10, 2021. THE PITS WEREBACKFILLED IMMEDIATELY AFTÊR EXPLORAIORYEXCAVATION OPERATIONSWERE COMPLETED.EçLORATORY BORINGS WERE DRILLED WT¡'H 4.INCHDIAMETER, SOLID.SIEM AUGERAND ATRACK:MOUNTED DRILL RIG ON APRIL 8, 2021,3. GROUNDWATER WAS NOT FOUND IN EXPLORATORYPITS OR BORINGSATTHE TIME OF EXCAVATION ANDDRILLING, PVC PIPE WAS INTALLED IN TH.I. TT!2, ANDTH.3 TO FACILNATE FUTURE CHECKS OFGROUNDWATER.07t1213t1215t1230t121015305onaImrIoñ4TmmI202535GREEN UNE ARCHIIECIT}49I HIGHÆPEN RANCHclllT PROJECT NO. GS06il6.000-125SUMMARY LOGS OF EXPLORATORY PITS AND BORINGSFIG.4 ffi 3 2 z0o6z(-rÀx u.l sz-2Iu,Ølll -aÉ. o-ãoO¿ 0.1 APPLIED PRESSURE. KSF 1.0 10 ÐRYUNITWEIGHT= MOISTURE CONTENT= 100 102 PCF 2A.7 % Somple of CLAY, SANDY (CL} From From TH.1 AT 10 FEET J 2 áo CI'z o.-1x l¡J s 2-to6ØlrlÉ, -tÀ =oo 0.1 APPLIED PRESSURE. KSF Somple of cLAy, sANDy (cL)DRY UNIT WEIGHT= MOISTURE CONTENT= 10 102 23.O Swell-Consolidation Test Results 100 PCF o/oTH.1 AT 15 FEET GREEN LINE ARCHITECTS 49I HIGH ASPEN RANCH PROJECT NO. GS06546.000-f 25 f ?EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTINGllllllrrrrrr \ ,\ t 4-- EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING \ ) \\ \ ) 1.0 FIG.5 ffi z0o ttz{-ro-xu¡sz-2I 11,olll -aÉ. o-ËoO+ 3 2 3 2 0.1 APPLIED PRESSURE. KSF Somple of CLAY SANDY From TH-1 AT20 FEET 1.0 10 DRY UNITWEIGHT= 1O2 MOISTURË CONTENT= 23"0 10 100 PCF To zo v,z-l o-xuJ -2sz9-sqt Ø ]¡J ú. À-4 Eoo -5 0.1 APPLIED PRESSURE . KSF Somple of cLAy SANDY From TH-2 AT ,I5 FEET DRY UNITWEIGHT= MOISTURE CONTENT= 100 78 PCF SgJ "/" GREEN LINE ARCHITECTS 49I HIGH ASPEN RANCH PROJECT NO. GS06546.000.1 25 Swell-Gonsolidation Test Results r i ll|llt. EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTINGlillll illlr\\ I , ) /é- || EXPANSION UNDER CONSTANT.PRESSURE DUE TO WETTING l l|tf\-- 1 I 1.0 FIG.6 ffi 3 2 z0o U'z(-rÀxuisz-2o6(t, IJJ -aÉ.À =oO4 0.1 APPLIED PRESSURE - KSF 1.0 10 DRY UNITWEIGHT= MOISTURE CONTËNI= 100 100 PCF*- zsd-v" Somple of CLAY, SANDY (CL) From 5omple From TH-z AT 20 FEET 3 2 óoØz À-1X t¡J s Z-¡o6ØulÉ. "3o. =o(J 4 o.f APPLIED PRESSURE . KSF 10 DRY UNITWEIGHT= MOISTURE CONTENT= 100 105 PCF zol "t, Of CLAY, SANDY (CL) TH.3 AT 30 FEET GREEN LINE ARCHITECTS 491 HIGH ASPEN RANCH PROJECT NO. cS06546.000-1 25 Swell-Gonsolidation Test Results r ll !|| - EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTINGll t ltri| <_ ) \ ) | |t | |lI. EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTINGlllll l t t|l| a? \ t ) 1.0 FIG- 7 ffi SANDS GRAVELcLAY (PLASïC) TO StLT (NON-PLASnC) FINE MED¡UM COARS FINE COARSE COBBLES HYDROMETERANALYSIS * ôt!z Fudt-2ul(J É.uÀ '100 90 80 '16 .10'8 .4 100 l0 20 30 4t 60 70 s0 90 1û0 970 Ø Í60 t--z ot50 U¿40 30 20 10 .001 0.002 .00s .009 .019 .037 .O74 .149 9.1 36.1 76.2 't27 200 152 5"6', I' DIAMETER OF PARTICLE IN MILLIMETERS U.S, STANDARD '50 '40 ,30 TIMÊ READINGS 60 M¡N. 1S MrN. 4 MrN. 1 MtN. .200 CLEAR SQUARE OPENINGS 3ts" 3t4" 1yt' . 3. .297 .590 0,42 1.19 2.O 2.38 4.76 9.52 25HR.7HR. 45 MlN. 15 MtN. Somple of çlAY.SANDY (CL)GRAVEL 31 o/o SILT & CLAY 59 o/o PTASTICITY INDÈX SAND 1O o/o L|QUID [lMtî - -- o/o Yo From TP - 1 AT 8-9 FEET SANDS GRAVELctAY (PTASTTC) rO StLr (NoN-pLAsTtc) FINE MEDIUM COARS FINE COARSE COBBLES 90 80 (,70z6ø Í60 Fz 8e0 É,tu14o 30 20 10 0 100 30 40 50 ô0 70 90 100.001 0.002 ,005 .009 ,019 .037 9.52 19.'t 36.1 76.2 127 200 152 TIME READINGS 60 MrN. 19 MtN. 4 MtN. 1 MtN. .200 U.S. STANDARD SERIES '50 .40 .30 .16 .10 '8 CLEAR SQUARE OPENINGS 3/8" 314" 1Y,' 3' 5"6' .o74 .'t49 .297 .590 1.19 2.0 2.38 4.76o.42 DIAMETER OF PARTICLE IN MILLIMETERS 25HR. 7HR. 45 MtN. 15 MtN. Somple of ç_LAy, s¿N_Dy (c!)From fË -7 Àr s-o perr GRAVEL SILT A CLAY PLASTICITY INDEX SAND 12 o/o LIQUID LIMIT o/o % 31 o/o li v" GREEN LINE ARCHITECTS 491 HIGH ASPEN DRIVE PROJECT NO. GS06546.000-125 Gradation Test Results FIG,8 ffi SLOPE PER SLOPE PREFABRICåTED DRA¡MCE coMPosrÍE (MTMDRA|N 6000 0R EAUMAT-EilI) ATTACH PUSNC SHEENNG TO FOUNDATON WALL E, MINIMUM rcR tttL sPAcEJ OSll¡{ COVER GRAVEL ENNRE WDT}I WIIH GREEN UNEARCHITECTS 481 HIGHAEPENDßIVE PROJECT NO. GSO6546.OOO-125 Foundation Wall Drain Concept VAPOR MINIMUM OR BEYONDl:1 SLOPE BOTÍOM OF (ïTHnHEVER f:¡!c! phuEÍER PERFORA'IED DRATN ptpE. THEptpE sHÖuto BE ptAcED tN A TRENçI hrn¡ e sLopE oF AT IEASÍ t,/8-tNcH DROP pER FOOTOF DRAII.I. qlc,qFE ptpE tN l/2' To 1-7/2. SCREENED ROCK. ÐfiEND GRAVEL I.ATERALLY TO FOOTNG AND AT t'EÆír t/2 HEtcHr oF FooTlNc. R[${IIRE TRENCH IIÏTH GRAVE- NOTÉ IUE-BO'TTOM OF 'IHE DRAI! SHOULÐ BE AT- LEASÍ 2 INCHES BELOIY BOTTOM OF¡qqnNo Ar rHE HtcHEsf poillr nN0 sr-ops Do¡vi¡wAräi-ib-n-ñsärvr-cnÂùrnorrï.Er oR To A suMp WHERE wÁilER cffi ef nnnbwo'#'pi,ruÞiñe FROM FOOTINO rs GREATER) SIRUCruRAI FLOOR Flg.9 ffi (MrRAfrRA¡N 6000 -òn ÈcuvAtfhfi) \ PREFABRNATED DRAII.IAßE coMPosfrE ATTACH PI.ASÍIC SHEENNG TO FOUNDATON TYAI.J- SLOPE PER osltA //- cR VtL sPecz J VAPOR BARRIER 2, MIN. AREEN UNEARCH]TECTS 481 HIOTI A,SPEN DRrrlE Profect No. GSO6546.OOO-1 25 Foundation Wall Drain Concept l/OlD DRII.IED PIER t-lNçlt DtAilETER PERFORATED RtCtD DRATN ptpE THE ptpE snout¡ BE pt¡cEp N n rns{Cn r¡ffi ô_g_Lo?E oF AT .-FSr V4-tNcH DROP pER FOOT OF DRAIN. EÎ'¡CÂSE ptpE tN 1/2. TO l-1/2'wASHED GRAì/ELRr Ð{nRE rnsNin wm cn¡úzu Ë}nËko omiæL' r-ATEßAtry To votD Al{D AT tE,.sr V2 HBct{T OFvotD. NOTES: 1') I!LLOTT.O!I._q !!E!RAI,N SHOULÐ ÞF-ôI._LFÁqI 2 NCHES BELOTV BOTTOM OF VOIDAr THE HrcHEsrrorirT Ar{D sLopE oorl¡1v4¡ı io à iıÉinvE-cnÁwïtñirr-'onTo A suMp wHERE TvATER cân BE narcvro sr piriúþNc: STRUSTRAI FTOOR Flg. 1O TABLE ISUMMARY OF LABORATORY TESTINGPROJECT NO. cS06546.000.1 25ffiDESCRIPTIONCLAY. SANDY ICHìCLAY, SANDY (CH)CLÂY. SANÞY ICH)CLAY, SANDY ICHICLAY. SANDY (CH)CLAY. SANDY (CH)CLAY, SANDY (CH)CLAY, SANDY (CH)CIAY, SANDY (CH)PASSINGNO.200SIÉVE(olol595794PERCENTSAND(o/o\1012PERCENTGRAVEL(o/"\3131SOLUBLESULFATESlo/o\0.00SWELL TEST RÉSULTS'(%l1.42.23,00.32.82.1LIMITSPLASTICITYINDEX(o/o\30LIQUIDLIMIT(%\54DRYDENSITY(PCF)'t0210214278I00105MOISTURECONTÊNT(o/o\20.723.023.O3S.123.A24.1DEPTHIFEETI8-95S10-11101520l5203f)EXPLORATORYBORINGS AND PITSTP.1TP-2TP.3TH-1TH-1TH.1ïH-2TH-2TH-3"SWELL MEASURED WITH lOOO PSF APPLIED PRESSURE.Page 1 of 1