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HomeMy WebLinkAboutSubsoils Report for Foundation Designffi CTLITHOMPSON i ;i,rj;,'1, ii .. :i;l .i ii], '1, ':1,:' ll 6resl26,h #G GEOTECHNICAL ENGINEERING INVESTIGATION SWEETWATER RANGH GUEST GABINS 4894 SWEETWATER ROAD GARFIELD COUNTY, COLORADO Prepared for: Beck Building Company P.O. Box 4030 Vail, CO 81658 CTLIT Project No. GS06935.000-125-R3 January 24,2025 CTl[Thompson. lnc. Denver, Fort Collins, Colorado Sprinqs, Glenwood Sprinqs,.Pueb!g., Summit Countv - Colorado th-eyenne, Wyoming and Bozeman, Montana N $a N5\.\ N d ffi Table of Contents scoPE....,...... PROPERTY DESCRI PTION.,....... UPPER BUILDINGS SITE .........,. PROPOSED CONSTRUCTTON .................... 1 1 2 3 4 5 6 b 7 7 I I I 0 1 1 2 3 4 5 5 o SITE EARTHWORK........ SUBSURFACE CONDITIONS...,. Foundation Wall Backfi ll Utilities........ BUILDING FOUNDATION.. Footings.,.... SLAB-ON-GRADE CONSTRUCTION .. CRAWL SPACE CONSTRUCTION.............. FOUNDATION WALLS CONCRETE CONSTRUCTION OBSERVATIONS ......... GEOTECHNICAL RISK LIMITATIONS FIGURE 1 - PROPERTY BOUNDARY FIGURE 2. DEVELOPMENT PLAN FIGURE 3 - PROPOSED UPPER BUILDINGS FIGURE 4 - PROPOSED GUEST CABIN 2 FIGURE 5 - PROPOSED GUEST CABIN 3 FIGURE 6 - PROPOSED GUEST CABIN 4 FIGURES 7 AND 8 - SUMMARY LOGS OF EXPLORATORY P]TS FIGURE 9 AND 1O - GRADATION TEST RESULTS FIGURES 11 AND 12 - FOUNDATION WALL DRAIN CONCEPTS TABLE I- SUMMARY OF LABORATORY TESTING APPENDIX A - EXPLORATORY PIT PHOTOGRAPHS BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS CTLIT PROJECT NO. GS06935.000-125-R3 ffi SCOPE CTLlThompson, lnc. (CTLIT) has completed a geotechnicalengineering investigation regarding the guest cabins proposed at Sweetwater Ranch in Gaffield County, Colorado. We conducted this investigation to evaluate subsurface conditions at the site and provide geotech- nical engineering recommendations for the planned construction. The scope of our investigation was set forth in our Proposal No. GS 24-0170-CM1. Our report was prepared from data developed from our field exploration, laboratory test- ing, engineering analysis, and our experience with similar conditions. This report includes a de- scription of the subsurface conditions found in our exploratory pits and provides geotechnical engineering recommendations for design and construction of the foundation, floor systems, be- low-grade walls, subsurface drainage, and details influenced by the subsoils. Recommendations in this report were developed based on our understanding of the currently planned construction. We should be provided with architectural plans, as they are further developed, so that we can provide geotechnical/geo-structural engineering input. PROPERTY DESCRIPTION The Sweetwater Ranch property is located west of the intersection of Sweetwater Road (County Road 40) and Sheep Creek Road (Forest Road 8450) in Eagle County, Colorado. The road intersection is about 1,OOO feet northeast of the confluence of Sweetwater Creek and the East Fork of Sheep Creek. A property boundary map is included as Figure 1. The property is comprised of an east parcel of appioxim alely 732 acres in Eagle County and a west parcel of about 1,953 acres in Garfield County. Sweetwater Creek flows to the south along the east property boundary. Mason Creek and Morris Creek, which are tributaries to Sweetwater Creek, flow down to the east in the north and south parts of the property, respec- tively. The HMS Relocated Ditch trends south across the property on the west side of the county line. The property is generally comprised of a hummocky terrace that slopes down to the southeast. Steep slopes drop down from higher elevations adjacent to the property boundary at the west and south. The creek channels are incised in the terrace terrain. The east edge of the property is on the valley floor of the Sweetwater Creek drainage. Several reservoirs and ponds BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS CTLIT PROJECT NO. GS06935.000-125-R3 Page 1 of 16 ffi are present on the upper parts property. Ranch roads provide access to various parts of the property and facilities, including residences and agricultural buildings. Numerous inigated hay- fields and pastures are on the property. Natural vegetation adjacent to the irrigated areas con- sists of oak brush, pinion and juniper trees, aspen trees, and sage brush. UPPER BUILDINGS SITE The upper buildings are proposed within, and adjacent to, an irrigated hayfield that is about 1,200 feet west of the county line. The center of the development area is about 700 feet from the crest of the steep slope that drops down to the Morris Creek drainage. The alignment of the HMS Relocated Ditch is downhill of the general location, about 800 feet to the northeast. At this writing, the proposed buildings include a main residence, community barn, and three guest cabins. The development plan is shown on Figure 2. Guest Cabins 2, 3 and 4 are planned at the northwest, west, and southwest sides of the hayfield referenced above. The buildings are proposed on hillsides that generally slope down to the northeast at grades ranging from 5 to 20 percent. Vegetation at the sites consists of sage brush and grass with scattered pinion and juniper trees. We observed numerous sandstone cobbles and boulders at the ground surface. Photographs of the guest cabin sites below, The upper buildings site is shown on Figure 3. Looking northwest toward Guest Cabin 2 site (beyond hayfield) BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS GTLIT PROJECT NO. GS06935.000-125-R3 Page 2 of 16 ffi Looking southwest at Guest Cabin 3 site PROPOSED CONSTRUCTION CTLIT was provided with schematic design drawings for the Guest Cabins 2 and 4 by Centre Sky Architecture, LTD (dated December 19,2024). The guest cabins are planned as BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS CTLIT PROJECT NO, GS06935.000.125-R3 View northwest across Guest Gabin 4 site Page 3 of {6 ffi one-level buildings with attached or detached carports. Construction will include decks and entry patios. The schematic design drawings indicate that floors in living areas of the guest cabins will be structurally supported with crawl spaces below, The carports will have slab-on-grade floors. We expect similar construction for Guest Cabin 3. The proposed footprints of Guest Cabins 2, 3 and 4 are shown on Figures 4 through 6. The guest cabins will likely be steel and wood-framing with cast-in-place foundation walls. Maximum foundation excavation depths of about I to 10 feet are anticipated at the uphill sides of the buildings. We expect foundation loads.between 2,000 and 3,000 pounds per linear foot of foundation wall and column loads of less than 50 kips. SITE GEOLOGY As part of our geotechnical engineering investigation, we reviewed geologic mapping by the U.S. Geological Survey (USGS) titled, "Geologic Map of the Leadville 1 Degree x 2 Degree Quadrangle, Northwestern Colorado", bV Tweto, Moench, and Reed (dated 1978). We also re- viewed mapping by the Colorado geologicalsurvey titled, "Geologic Map of the Dotsero Quad- rangle, Eagle and Garfield Counties. The maps indicate the soils at the planned site of the up- per buildings consist of landslide deposits of the Holocene and Pleistocene Epochs. These ma- terials are unconsolidated, unsorted, and unstratified. The materials are heterogeneous and range in size from cobbles and boulders to silt and clay. We judge the soils found in our explora- tory pits for the main residence are consistent with landslide deposits. Based on geologic mapping and our site observations, it appears the overburden soils are underlain at depth by bedrock of the Minturn Formation (Middle Pennsylvanian Period) and Belden Formation (Lower Pennsylvanian Period). The Minturn Formation is generally gray, tan, and red sandstone, conglomerate, and shale. The Belden Formation is dark gray to black shale and carbonate rocks and sandstone. The mapping indicates the bedrock formations are undi- vided in the vicinity of Sweetwater Creek. The weathered sandstone and sahdstone bedrock encountered in our MR-C pit appeared consistent with The Minturn Formation. BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS GTLIT PROJECT NO. GS06935.000-1 25-R3 Page 4 of 16 ffi SUBSURFACE CONDITIONS Subsurface conditions at the planned locations of Guest Cabins 2, 3, and 4 were investi- gated by directing excavation of six exploratory pits at the approximate locations shown on Fig- ures 3 through 6. GC2-A and GC2-B were excavated for Guest Cabin 2, GC3-A and GC-B, were excavated for Guest Cabin 3, and GC4-A and GC4-B were excavated for Guest Cabin 4. The pits were excavated with a trackhoe on November 18, 2025. Exploratory excavation opera- tions were directed by our engineer, who logged subsurface conditions encountered and ob- tained samples of the subsoils. Graphic logs of subsurface conditions found in our exploratory pits are shown on Figures 7 and 8, Photographs of the exploratory pits and excavated materials are attached as Appendix A. Subsurface conditions encountered in our exploratory pit, GC2-A, for Guest Cabin 2 consisted of about 6 inches of topsoil, 5.5 feet of sandy clay, and 2.5 feet of weathered sand- stone, underlain by competent sandstone. The hardness of the sandstone made exploratory excavation deeper than 9 feet not practical. GC2-B exposed 6 inches of topsoil and 2.5 feet of sandy clay, underlain by clayey gravel and sandy clay to the total excavated depth of 10 feet. Subsoils observed in our exploratory pit, GC3-A, for Guest Cabin 3 consisted of about 1 foot of topsoil over sandy clay and clayey gravel to the total excavated depth of 12 feet. GC3-B exposed 1 foot of topsoil, 6 feet of clayey gravel and sandy clay, and 3 feet of weathered sand- stone, underlain by competent sandstone. The hardness of the sandstone made exploratory excavation deeper than 10.5 feet not practical. The subsoils found in our exploratory pit, GC4-A, for Guest Cabin 4 consisted of about 6 inches of topsoil and 1 foot of sandy clay, underlain by clayey gravel and sandy clay to the total excavated depth of 12 feet. Subsurface conditions in GC4-B were 6 inches of topsoil and 7.5 feet of clayey gravel and sandy clay, underlain by competent sandstone. The hardness of the sandstone made exploratory excavation deeper than 8.5 feet not practical. Groundwater was not encountered in our exploratory pits at the time of our subsurface investigation. The pits were backfilled immediately after exploratory excavation operations were completed. BECK BUILOING COMPANY SWEETWATER RANCH. GUEST CABINS CTLIT PROJECT NO. GS06935.000-1 25-R3 Page 5 of '16 ffi Samples of the subsoils obtained from our exploratory pits were returned to our laborato- ry for peftinent testing. Laboratory testing included Atterberg limits and gradation analyses, Gradation analysis results are shown on Figures 9 and 10, Laboratory testing is summarized on Table l. SITE EARTHWORK Excavations Based on our subsurface investigation, we expect excavations for construction of the main residence can be accomplished using conventional, heavy-duty excavating equipment, such as a medium-sized trackhoe. Excavations more than a few feet into the bedrock may re- quire a hydraulic hammer attachment on a trackhoe. From a "trench safety" standpoint, sides of excavations must be sloped or retained to meet local, state, and federal safety regulations. Th6 soils in excavations at this site will likely classify as Type B and Type C soils, based on OSHA criteria. Excavations deeper than 5 feet and above groundwater should be sloped no steeper than 1 to 1 (horizontal to vertical) in Type B soils and 1.5 to 1 in Type C soils. Groundwater seepage into excavations can cause slumps and sloughing and the need for flatter slopes. Contractors are responsible for site safety and providing and maintaining safe and stable excavations. Contractors should identify the soils en- countered in excavations and ensure that OSHA standards are met. CTLIT did not encounter a groundwater table in our exploratory pits. Our experience in similar geologic conditions in the region indicates that the upper soils can becbme saturated during snowmelt in spring and early summer. Zones of groundwater seepage could occur in ex- cavations at the site. lt appears feasible that construction dewatering can be accomplished by sloping excavations to gravity outlets or to sump pits where water can be removed by pumping. Trenches along the perimeter of the excavation, outside the structure footprint, can help convey water to outlets or sumps. We recommend that excavation and earthwork operations commence after peak snowmelt has occurred. BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS GTLIT PROJECT NO. GS06935.000-125-R3 Page 6 of 16 ffi Subexcavation and Structural Fill The overburden soils at this site are relatively heterogeneous. Furthermore, the soils have not been subject to geologic loads and have potentialfor consolidation when wetted under building loads. We judge the use of footings and slabs-on-grade is reasonable, provided poten- tial for differential building movement is mitigated. ' To create more uniform support conditions and reduce the potentialfor differential movement of foundations for the building, we recommend subexcavation of the soils below the bottoms of footings and floor slabs to a depth at least 3 feet. The sub-excavated areas should extend laterally at least 1 foot beyond the edges of footings and slabs. The excavated soils should be replaced with densely-compacted, structural fill, The excavated soils can be reused as structuralfill, provided they are screened to re- move rocks larger than 4 inches in diameter, organics, and debris. lmport soil needed for struc- tural fill should consist of a clayey sand or gravel with a maximum rock size of 4 inches and 20 to 40 percent silt and clay sized material. A sample of potential import soilfor structuralfill should be submitted to CTLIT for approval prior to the hauling to the site. Structural fill should be placed in loose lifts of 8 inches thick or less, moisture- conditioned to within 2 percent of optimum moisture content and compacted to at least 98 per- cent of standard Proctor (ASTM D 698) maximum dry density. Moisture content and density of structural fill should be checked by a representative of CTLIT during placement. Observation of the compaction procedure is necessary. Foundation Wall Backfill Proper placement and compaction of foundation backfill is important to reduice infiltration of surface water and settlement from consolidation of backfill soils. This is especially important for backfill areas that will support exterior concrete flatwork, such as patios, walkways, and driveways. The excavated soils can be reused as backfill, provided they are screened to remove or- ganics, debris, and rocks larger than 6 inches in diameter. Backfill should be placed in loose lifts BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS cTLIT PROJECT NO. GS06935.000-12s-R3 Page 7 of 16 ffi of approximately 10 inches thick or less and moisture-conditioned to within 2 percent of opti- mum moisture content. Backfill soils that will not support exterior concrete slabs should be compacted to at least 95 percent of standard Proctor (ASTM D 698) maximum dry density. Backfill soils that will sup- port exterior concrete slabs should be compacted to at least 98 percent of ASTM D 698 maxi- mum dry density. Moisture content and density of the backfill should be checked during place- ment by CTLIT. Observation of the compaction procedure is necessary. Foundation backfill that will support exterior slabs requires strict adherence to specifica- tions. Even well-placed backfill will settle 0.5 to 1 percent of total backfill thickness. Structures placed over backfill zones will need to be designed to accommodate differential movement with respect to the building. lf slabs and structures that are sensitive to settlement will be located above deeper zones of backfill, consideration should be given to designing these elements as structurally supported. Utilities Sides of utility trenches should be sloped or braced to meet local, state and federal safe- ty requirements. Anticipated OSHA soil type classifications are provided in the Excavations sec- tion. We believe the natural soils at this site have low corrosion potential. We can perform re- sistivity testing to assist in judging corrosivity of the native soils, if desired. Water mains and other utilities may be constructed of common ductile iron pipe. Some municipalities recommend iron fittings, joints, couplings and appurtenances be wrapped with polyethylene for corrosion protection regardless of soil resistivity. Properly compacted backfill in utility trenches is important to reduce subsequent consoli- dation of backfill soils and infiltration of surface water. Backfill soils should consist of the on-site soils, free of rocks larger than 4 inches in diameter, organic matter and debris. Backfill should be placed in thin lifts, moisture conditioned to within 2 percent of optimum moisture content and compacted to at least 95 percent of standard Proctor (ASTM D 698) maximum dry density. Density and moisture content of backfill should be checked by GTLIT during placement. BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS CTLIT PROJECT NO. GS06935.000-125-R3 Page 8 of 16 BUILDING FOUNDATIONS The overburden soils at this site are relatively heterogeneous. Furthermore, the soils have not been subject to geologic loads and have potentialfor consolidation when wetted under building loads. We judge the use of footing foundations is reasonable for Guest Cabins 2, 3 and 4, provided potentialfor differential building movement is mitigated. To create more uniform support conditions and reduce the potentialfor differential movement of foundations for the buildings, we recommend subexcavation pf the soils below the bottoms of footings to a depth at least 3 feet. The sub-excavated areas should extend laterally at least 1 foot beyond the edges of the building footprints. The excavated soils should be re- placed with densely-compacted, structuralfill in accordance with recommendations in the Subexcavation and Structural Fill section. Recommended design and construction criteria for footings are below. These criteria were developed based on our analysis of fleld and laboratory data, as well as our engineering experience. Footings Footings should be supported by densely compacted, structuralfillthat is at least 3 feet thick. The structuralfill should be in accordance with recommendations in the Subexcavation and Structural Fill section. Footings on densely compacted, structural fill can be designed for a maximum net allowable soil bearing pressure of 3,000 psf. The weight of backfill soils above the footings ian be neglected for bearing pressure calculation. A 1,000 psf increase in this bearing pressure is acceptable when using the alternative load combination of IBC 2015, Section 1605.3.2 that include wind and earthquake load. A friction factor of 0.35 can be used to calculate resistance to sliding between concrete footings and the structural fill. Continuous wall footings should have a minimum width of at least 18 inches, Foundations for isolated columns should have minimum dimensions of 30 inches by 30 inches. Larger sizes may be required, depending upon foundation loads. Grade beams and foundation walls should be well-reinforced. We recommend re- inforcement sufficient to span an unsupported distance of at least 12 feet. BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS CTLIT PROJECT NO. GS06935.000-12s-R3 I 2 3 4 5 Page 9 of 16 The soils under exterior footings should be protected from freezing. We recom- mend the bottom of footings be constructed at least 42 inches below finished ex- terior grades for frost protection. The Garfield County building department should be consulted regarding frost protection requirements. SLAB-ON.GRADE CONSTRUCTION The overburden soils at this site are relatively heterogeneous. Furthermore, the soils have potential for consolidation when wetted under building loads. We judge the use of slab-on- grade floors and exterior flatwork is reasonable for Guest Cabins 2, 3 and 4, provided potential for differential movement is mitigated. To create more uniform support conditions and reduce the potential for differential movement of foundations for the building, we recommend subexcavation of the soils below the bottoms of interior slabs to a depth at least 3 feet. The sub-excavated areas should extend lat erally at least 1 foot beyond the edges of the slabs. A minimum structuralfillthickness of 12 inches is recommended below exterior flatwork. The excavated soils should be replaced with densely-compacted, structuralfill in accordance with recommendations in the Subexcavation and Structural Fill section Based on our analysis of field and laboratory data, as well as our engineering experi- ence, we recommend the following precautions for slab-on-grade construction at this site. Slabs should be separated from footings and columns pads with slip joints which 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 utili- ties which pass through slabs should be isolated from the slabs with sleeves and provided with flexible couplings to slab supported appliances. Exterior patio slabs and concrete flatwork should be isolated from the building. These slabs should be well-reinforced to function as independent units. Frequent controljoints should be provided, in accordance with American Con- crete lnstitute (ACl) recommendations, to reduce problems associated with shrinkage and curling. The lnternational Building Code (lBC) may require a vapor retarder be placed be- tween the base course or subgrade soils and concrete slab-on-grade floors. The merits of installation of a vapor retarder below floor slab depend on the sensitivity BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS cTLlr pRoJEcT NO. GS06935.000-125-R3 6 1 2 3 4 5. Page 10 of 16 ffi of floor coverings and building to moisture. A properly installed vaper retarder (10 mil minimum) is more beneficial below concrete slab-on-grade floors where floor coverings will be sensitive to moisture. The vapor barrier/retarder is most effec- tive when concrete is placed directly on top of it. A sand or gravel leveling course should not be placed between the vapor barrier/retarder and the floor slab. CRAWL SPACE CONSTRUCTION The schematic design drawings indicate that crawl space areas may be constructed be- low parts of the main-level floors in the guest cabins. The required crawl space height depends on the materials used to construct the floor system above the crawl space. Building codes nor: mally require a clear space of at least 18 inches between exposed earth and untreated wood components of the structural floor. Utility connections, including water, gas, air duct, and exhaust stack connections to ap- pliances on structural floors should be capable of absorbing some deflection of the floor. Plumb- ing 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. Control of humidity in crawl spaces is important for indoor air quality and performance of wood floor systems. We believe the best current practice to control humidity involves 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. lt may be appropriate to install a ventilation system that is controlled by a humidistat. FOUNDATION WALLS Foundation walls that 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 basements and crawl spaces. Many factors affect the values of the design lateral earth pres- sure, 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 backfilltypes), design for a lower "active" lateral earth pressure BECK BUILDING COMPANY PAgE 11 Of 16 SWEETWATER RANCH - GUEST CABINS CTLIT PROJECT NO. GS06S35.000-1 25-R3 ffi may be appropriate. Our experience indicates typical below-grade walls in residences deflect or rotate slightly under normal degign 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 backfillsoils conforming with recommendations in the Foundation Wall Backfillsec- tion 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 is appropriate using an equivalent fluid pressure of 60 pcf. SUBSURFACE DRAINAGE Our experience in similar geology and topography in the region indicates the upper soils can become saturated during snowmelt in spring and early summer months. Frozen ground dur- ing spring runoff can also create a perched condition. Additionally, 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 ex- cavations. These sources of water can cause wet or moist conditions in below-grade areas after construction. To reduce the likelihood water pressure will develop outside foundation walls, we recommend provision of foundation wall drains around the perimeters of the gudst cabin founda- tion. The foundation wall drains should consist of 4-inch diameter, slotted PVC pipe encased in free-draining gravel. A prefabricated drainage composite should be placed adjacent to foun- dation wall exteriors. Care should be taken during backfill operations to prevent damage to drainage composites. The drains should discharge via positive gravity outlets. The gravi$ out- lets should not be susceptible to clogging or freezing. We recommend installation of clean-outs along the drainpipes. A representative of our firm should be called to observe the drain con- struction, prior to backfilling. To further mitigate subsurface water, we recommend a drainage layer (below slabs and on crawl space floor:s) consisting of 4-inch diameter, slotted PVC pipe installed on I to 10-foot centers and embedded in at least 6 inches of screened rock. lf a vapor barrier/retarder is placed BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS cTLIT PROJECT NO. GS06935.000-1 25-R3 Page 12 of 16 ffi below the slabs, the gravel layer should be below the barrier. The pipes should convey water to perimeter drain collector pipes. Water collected should be discharged via positive gravity out- lets. The foundation wall drain concepts are shown on Figures 11 and 12: SURFACE DRAINAGE Surface drainage is critical to the performance of foundations, floor slabs, and concrete flatwork. Surface drainage should be designed to provide rapid runoff of surface water away from the residence. Proper surface drainage and irrigation practices can help control the amount of surface water that penetrates to foundation levels and contributes to settlement of soils that support the building foundation and slabs-on-grade. Positive drainage away from the buildings foundation and avoidance of irrigation near the foundations also help to avoid excessive 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 guest cabins should be sloped to rapidly convey surface water away from the building in all directions. We recommend a constructed slope of at least 12 inches in the first 10 feet (10 percent) in landscaped areas around the buildings, where practical. Backfill around the foundation walls should be moisture{reated and compacted pursuant to recommendations in the Foundation Wall Backfill section. We recommend that the guest cabins be provided with roof drains or gutters and downspouts. The drains or downspouts should discharge well beyond the limits of all backfill. Splash blocks and/or extensions should be provided so water dis- charges onto the ground beyond the backfill. We generally recommend against burial of downspout discharge pipes. Landscaping should be designed and maintained to minimize irrigation. Plants placed close to foundation walls should be limited to those with low moisture re- quirements. lrrigated grass should not be located within 5 feet of the foundations. 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 and allow some evaporation to occur. BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS CTLIT PROJECT NO. GS06935.000-1 2s-R3 1 2 3 4 Page 13 of 16 CONCRETE Concrete in contact with soil can be subject to sulfate attack. Our experience with pro- jects in similar geology indicates the soils have water soluble sulfate concentrations of less than 0.10 percent. Pursuant to our test and ACl332-20, this concentration corresponds to a sulfate exposure class of "Not Applicable" or RSO as indicated on the table below. SULFATE EXPOSURE CLASSES PER ACI 332.20 by mass in soil determined by ASTM C1580 For this level of sulfate concentration, ACI 332-20,"Code Requirements for Residential Concrete", indicates no special cement type requirements for sulfate resistance as indicated on the table below. CONCRETE DESIGN REQUIREMENTS FOR SULFATE EXPOSURE PER ACI 332.20 A) Concrete strength specified shall be based on 28-day tests per ASTM C39/C39M B) Alternate combinations of cementitious materials of those listed in ACI 332-20 Table 5.4.2 shall be permitted when tested for sulfate resistance meeting the criteria in section 5.5. C) Other available types of cement such as Type lll or Type I are permitted in Exposure Classes RS1 or RS2 if the C3A contents are less than 8 or 5 percent, respectively. D) The amount of the specific source of pozzolan or slag to be used shall not be less than the amount that has been determined by service record to improve sulfate resistance when used in concrete containing Type V cement. Alternatively, the amount of the specific source of the pozzolan or slab to be used shall not be less BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS cTLIT PROJECT NO. GS06935.000-125-R3 Water-Soluble Sulfate (SOr) in Soil'A (o/o\ Exposure Classes < 0.10Not Applicable RSO RS1 0.10 to 0.20Moderate RS2 0.20 to 2.00Severe > 2.00Very Severe RS3 s Maximum Water/ Cement Ratio Minimum Compressive Strength A (psi) ASTM c150/ c150M ASTM c595/ o595M ASTM c1157t c1 157M Calclum Chlo- ride Admix- tures Exposure Class No Type Restrictions No Type Restrictions No RestrictionsRS0N/A 2500 No Type Restrictions il Type with (MS) Designation MS No RestrictionsRS10.50 2500 Not PermittedRS24.45 3000 Vc Type with (HS) Designation HS HS + Pozzolan or Slag Cement E Not PermittedRS3o.45 3000 V + Pozzolan or Slag Cement D Type with (HS) Designation plus Pozzolan or Slag Cement E Page 14 of 16 ffi than the amount tested in accordance with ASTM C10'l2lC1O12M and meeting the criteria in section 5.5.1 of ACl332-20. E) Water-soluble chloride ion content that is contributed from the ingredients including water aggregates, ce- mentitious materials, and admixtures shall be determined on the concrete mixture ASTM C1218/C1218M between 29 and 42days. Superficial damage may occur to the exposed surfaces of highly permeable concrete. To control this risk and to resist freeze thaw deterioration, the water-to-cementitious materials ratio should not exceed 0.50 for concrete in contact with soils that are likely to stay moist due to sur- face drainage or high-water tables. Concrete should have a total air content of 6% +/-1.5%. We recommend foundation walls and grade beams in contact with the subsoils be damp-proofed. CONSTRUCTION OBSERVATIONS We recommend that CTLIT be retained to provide construction observation and materi- als 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 ob- servations, they must accept responsibility to judge whether the recommendations in this report remain appropriate. lt is also beneficialto projects, from economic and practical standpoints, when there is continuity between engineering consultation and the construction observation and materials testing phases. 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 geotechnical recommendations do not comprise an exact science. We never have complete knowledge of subsurface conditions, Our analysis must be tempered with engineering judgment and experience. Therefore, the rec- ommendations presented in any geotechnical evaluation should not be considered risk-free. We cannot provide a guarantee that the interaction between the soils and the proposed guest cab- ins will lead to performance as desired or intended. Our recommendations represent our judg- ment of those measures that are necessary to increase the chances that the buildings will per- form satisfactorily. tt is criticalthat all recommendations in this report are followed. BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS CTLIT PROJECT NO. GS06935.000-125-R3 Page 15 of 16 ffi LIMITATIONS This report was prepared for the exclusive use of Beck Building Company with respect to Guest Cabins 2, 3 and 4 proposed at Sweetwater Ranch. The information, conclusions, and recommendations provided 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 in the report are not valid for use by others. Standards of practice continuously change in geotechnicalengineering. The recommendations provided in.this report are appropriate for about three years. lf the proposed building is not constructed within three years, we should be contacted to determine if we should update this report. Our exploratory pits provide a reasonable characterization of subsurface conditions at the planned guest cabin locations. Variations in subsurface conditions not indicated by the pits will occur. We should be provided with architectural plans, as they are fufther developed, so we can provide geotechnical/geo-structural engineering input. 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 implied, is made. Please contact us if we can be of further service in discussing the contents of this report. CTLITHOMPSON, tN Reviewed by: owtu Division Barbone, Manager t- /zv/zo 25. R. o76Bs # mes D. Kellogg, P ior Principal Engi BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS GTLIT PROJECT NO. GS06935.000-12s-R3 o o38298 2 Page 16 of 16 { LEGEND:ffi APPROXIMATE LOCA11ON OF PROPERTY BOUNDAR' APPROXIMATE LOCATION OF COUNTY LINE 0tm@r NOIT: SATEIfTE IMACE FROM MAOR (coPYRrcHT 2022) EEd( BUIJIMI OWPN lwlMEM.qffN Prcllot l,b, OaO3OS5.OOO-i26-Rg Property Boundary Flg, I { 0FtdtrlErrru t'.16' 3ld( lULDflO olvlPAlwWMilDs.c5qN Frcl.ot tb. Gaooeg5.ooo-l 2&Fo tr APPROXIMATS LOCATION OF PROPERTY BOUNDARIES SATSLLM IMACE FROM GO@I.E EARTH (MTED Ar,rCUSr r, 2025) LEGENDI NOtEr Development Plan Eo. 2 + trLEGEND: NOTE: BASE DMWNc sY BLI.IEoREEN ASPEN ccl-A rnrnoxrvrre LocAIroN oF gxptomlon/ ptT ot@dEFEIE-Iru l'.tr 8EOK AJI.DSIO OOMPAIYmtraBm,ffiq Fre,6t No O80603!.000426-RS Propoccd Upper Bulldlnga Fh. g ffi o 50 60 SCALET 1'- 6O' ^ -..7 LEGEND: GC2_A APPROXIMATE LOCATION OF I EXPLORATORY PIT NOTE: fi\ BASE DRAWING BY BLUEGREEN ASPEN (DATED DECEMBER s, 2024) GC2_B tr* \ I XI / 2 posed Cobin Pro est + GC2_A \ ,G,7o \ I ,{ ,/ \ \) /L/ ) \ \ ) t ( BECK BUILDING COMPAT'IY SWEETWATER RANCH . GUEST CABINS oTUT PROJECT NO. GSO6935.OOO-1 25-R3 Proposed Guest Gabin 2 Flg. 4 =ffi 60 LEGEND: GC3-A APPROXIMATE LOCATION OF f EXPLORATORY PIT NOTE: o JO SCALE: 1'- 60' I I ) BASE DRAWING BY BLUEGREEN ASPEN (DATED DECEMBER 3, 2024) t/ % \- 'l I\% Proposed I-l ( \ ) z-- )ro Y__t*o 41"" cobin 3 GC3-B- ,r%I GC5-A \ \ I \ \ 1 BECK BUILDING COMPAiIY SWEETWATER RANCH - GUEST CAFINS cruT PRoJECT NO. GS06935.O00-1 25-R3 Proposed Guest Cabin 3 Flg. 5 ffi 05060 LEGEND: GC4-A APPROXIMATE LOCATION OF I EXPLORATORY PrT NOTE: \ SCAI-Er 1'- 60' BASE DRAWING BY BLUEGREEN ASPEN (DATED DECEMBER s, zo24) \\ \ )% \ \ GC4_B / 7170 // BECKBUILDING COMPATW SWEtrWATER RANCH . GIUEST CABINS \ Guest Cobin 4 Propos \ "oo, Proposed Guest Gabin 4 a GC4-A I \ l t \ \ I oTUT PROJECT NO. GSO6935.OOO-1 25-R3 Flg. 6 ffi GC2-A EL7f2A (lC2-B EL.7Z16 BECK BUIDIilO CilPANYSWEMAruN MNCH MS A'N8 CTLJTPrcJEfr rc, GS$,MIDM GUEST CABIN 2 FLOOR EL.7726 NN 7726 7i20 7716 7110 7706 oclA GC3€ EL.7772EL.NA? 7786 CABIN 3 EL,N77 fn6 n7.0 77BE SUMMARY LOOS OF EXFLORATORY PITS GC44 EL.n76 GC48 aL7788 7780 m8 cAatN4 7770 EL.7/68 n6 776D r'55 h g a d HE FIG. 7 LEGEND: TOPSOIL, CLAY, SANDY, MOIST, DARK BROWN CLAYEY GRAVELAND SANDY CLAY, SCATTERED ANGUIAR SANDSTONE COBBLES, MEDIUM DENSE OR sTrFF, MOTST, BROWN, TAN. (GC, SC, CL) CLAY, SANDY, MEDIUM STIFFTO STIFF, MOIST, BROWN. (CL) WEATHERED SANDSTONE, SILTY, ANGULAR, SLIGHTLY MOIST, TAN, BEDROCK SANDSTONE, HARD TO VERY HARD, TAN, GRAY. ffi Summarv Loqs FIrSl<oloiator! FIG.8 a U H SYMBOL INDICATES A BULK SAMPLE OBTAINED FROM EXCAVATED SOILS, SYMBOL INDICATES A HAND DRIVE SAMPLE OBTAINED DURING EXCAVATION. NOTES: 1. THE EXPLOMTORY PITS WERE EXCAVATED WITH A TRACKHOE ON NOVEMBER 18, 2024, 2. GROUNDWATERWAS NOT FOUND IN OUR EXPLORATORY PITS AT THE TIME OF EXCAVATION. THE PITS WERE BACKFILLED IMMEDIATELYAFTER EXPLOMTORY EXCAVATION OPEMTIONS WERE COMPLETED, 3. EXPLOMTORY PIT ELEVATIONS WERE ESTIMATED FROM GROUND SURFACE CONTOURS SHOWN ON FIGURE 3. 4. THESE LOGS ARE SUBJECT TO THE EXPI.ANATIONS, llnltrrAnons AND coNcLUsroNs tN THrs REpoRT. F F BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS oTLIT PROJECT NO. GS06935.000-125.R3 ffi GRAVELSANDS MEDIUM COARS FINE COARSE COBBLESCLAY (PLASTIC) TO SILT (NON.PLASTIC) FINE SIEVE ANALYSIS 0 t0 20 30 40 50 60 70 80 90 100 2706 K.oFz 850e.l!L4o 30 20 10 0 oU2 FUu Fz ulod UJI 127 200 152 90 80 100 .100 '50 *40'30 9.52 19.1 36.1 76.2.001 0.002 .005 .000 .019 .037 TIME READINGS 60 MtN. 19 MrN. 4 MtN. 1 MtN. '200 SERIES '16 '10'8 CLEAR SOUARE OPENINGS 3/8' 3t4" 1n' 3' 5'6" 8', .o74 .149 .297 .590 1.19 2.0 2.38 4.76 o.42 DIAMETER OF PARTICLE IN MILLIMETERS 25 HR. 7 HR, 45 MtN. 15 MlN. Somple of cTRy, SANDY (cL)GRAVEL srLT & CLAY 87 PLASTICITY INOEX -' GRAVEL stLT & ct_AY _-5-g PLASTICITY INDEX SAND LIQUID LIMIT 10 SAND LIQUID LIMIT Gradation Test Results o/o o/o 't3 % From Somple From GC2.A AT 5 FEET o/o Vo % % % of ctey,SANDY (CL)3o/o o/oGC3.A AT 6 FEET BECK BUlLDING COMPANY SWEETWATER RANCH - GUEST CABINS PROJECT NO. GS06935.000-125-R3 SANDS GMVEL FINE MEOIUM COARS FINE COARSE COBBLEScLAY (PLASTTC) TO srLr (NON-PLASTTC) 100 90 00 (9toz6 po Fz 860c.u9o 30 20 10 0 10 20 30 40 50 60 70 80 g0 100 __t__-_t- _t_ -t----- ::-:l------__._.t..-_ --f-- -t-/r* ----t'--.--t --------r----'-*-t-- - - -t--- -l--.t-- - . - . * . _ t . . . . . . . . * _t-- -t- "-'-*.'-t--- -t- .-.-.--.-t-..-- -t-*--. -.---t-" . --_--.-t- - .-.--t- I__t- _._t_. --t- --*t-. --".--t_.-- o llJz Fl!E Fz uJ(,)tulc 76.2 127 200 152 ,4 .001 0.002 .005 .009 .019 .037 9.52 19.1 36.1 TIME READINGS 00 MlN. 19 MlN. 4 MlN. I MrN. '200 '100 U.S. STANDARD SERIES .50 .40 '30 '16 '10'8 CLEAR SQUARE OPENINGS 9/8' 3t4" 1y;', 3' 5"6', .o74 .149 .297 .590 1.19 2.0 238 4.76 0.42 DIAMETER OF PARTICLE IN MILLIMETERS 2s HR. 7 HR. 45 MtN. 15 MtN, FIG.9 ffi GRAVELSANOS COARSE COBBLESFINEMEDIUMCOARSFINECLAY (PLASTTC) TO SrLT (NON.PLASTTC) SIEVE ANALYSIS .o74 .149 .257 .500 1.19 2.0 2.38 4.78 S.52 19.1 36.1 78.2 127,-200'- 0.42 152 DIAMETER OF PARTICLE IN MILLIMETERS '4 t00 g0 80 2706 3uo Fz 850tU[40 70 80 90 100 .001 0.002 .005 .009 .019 .o37 TIME READINGS 60 MtN. 19 MtN. 4 MlN. I MlN. '200 U.S. STANDARD SERIES .'t00 '50 r40 '30 '16 '10'8 CLEAR SQUARE OPENINGS 3/8' 3t4" Ivt' 3" 5"6' 8' 30 20 10 0 0 10 20 gofiz 340 ItdFso6o E,ul60G 25HR. 7HR. 45 MtN. 15 MtN. Somp IE Of CLAY, SANDY (CL)GRAVEL o/o Yo 20 SAND srLT & oLAY 67 PLASTICIry INDEX LIQUID LIMIT GRAVEL o/o SAND SILT & CLAY o/o LIQUID LIMIT PLASTICITY INDEi Gradation Test Results 13% From Gc4-B AT 6 FEET o/o o/o % % % Somple of From BECK BUILDING COMPANY SWEETWATER RANCH . GUEST CABINS PROJECT NO. GS06935.000-1 25-R3 SANDS GRAVEL MEDIUM COARS FINE COARSE COBBLEScrAY (Pr-AsTlc) To srLT (NoN-Pr.AsTrc) FINE HYDROMETERANALYSIS ----l- t-- -l-l- - I -t*,---. _.t_t_- --t---t------ -t-*t-.- 10 20 30 40 50 60 70 80 90 100 stoz6 @ f30 Fz 850EUolo '4 127 200 152 90 80 100 30 20 10 0 9.52 19.1 36.1 74.2.001 0.002 .005 .009 .019 .0r7 U.S. STANDARD SERIES '100 .50'40'30 '16 10 '8 CLEAR SQUARE OPENINGS 3/8" 3t4', 1v'. 3' 5'6" TIME READINGS 60 MrN. 19 MlN. 4 MlN. 1 MlN. '200 .o74 .149 .257 .590 1.19 2.0 2.38 4.76 0.42 DIAMETER OF PARTICLE IN MILLIMETERS 25HR. 7HR. 45 MrN. t5 MtN. FIG,1O SLOPE 2-3' BACKN[.L\ PREFABRICATED DRAI],lAGE coMPosm (M!RA,DRA|N 6000 oR EAUMAENT) GRAVEL WIH NON-WO\EN GEOTEflIE FABRIC (MIRAR r40N oR EAUMAT.ENI). SLOPE PER OSHA CO\ER ENNRE WDTH OF ATTACH PTASTIC SHEENNG TO FOUNDATION 8, MINIMUM OR BEYOND SUP JOINT a t.r r4" f I tit .. t F'C DRAN EMBEDDED IN WASHED CONCRETE AGGREGATE I 'o ta. t :J .i.l Foundation Wall Drain Concept I MINIMUM 1:1 SLOPE FROM BOTTOM OF FOOING (wHTCHEVER rS GREATER) 4-INCH DhMETER PERFORATED RIGID DRNN PIPE. THE PIPE SHOULD BE PIACED IN A TRENCH ITTTTI A SLOPE OF AT LEASr |/E-INCH DROP PER FOOT OF DRAIN. ENCASE ptpE tN 1/2' TO 1-1/2' SCREENED GRAVEL DfiEND GRA\EI LATERAIIY TO FOOTING AND AT tEASr 1/2 HEIGHI OF FOOTING. Ru- EIiIIIRE TRENCH WMI GRAI/EL NOIE: TI{E BOTTOM OF TTIE DMIN SHOUI..D BE AT TEAST 2 NCHES BELOW BOTTOM OF FOOIING AT THE HIGHEST PONT AND SLOPE DOWNIVARD TO A POS]IIVE GRAVITY OI'ILET OR TO A SUMP IYHERE WATER CAI.I BE REIIO/ED Bf PUMPING. BECKBUILDING COMPANY 8I/I/EETWAIET FANCH . oUEST CABINS ProJect No. GS06935.O0O-1 25-Rg Flg. 11 STRUSTRAL FLOOR SLOPE 2-3' BAC'fi\ PREFABRICATED DMIMGE coMPosm (MTMDRATN 6000 oR EOUMAT.ENT) SLOPE PER osllA CO\ER ENNRE Y'IDTH OF ,-CRAWL SPi|OE J ATTACH PI.ASNC SHEETING TO FOUNDATION 8, MINIMUM OR BETOND 'MuD SI.AB, oR BA,RRIER GRAVET WtTtl NON-WOIIEN GEOTEflIE FABRIC (MIRAR 14ON OR EOU|VA!..ENi). a a sI rrl'. $ e ' .2i :f.l t !4: '.t 14'-6'It..i { Foundation Wall Drain Concept 1:1 SLOPE FROM BOTTOM OF FOOTING (wHrcHEvER rs GREATER) 4-INCH DNT'ETER PERFORATED RIGID DRAIN PIPE. THE PIPE SHOULD BE PTACED IN A TRENCH WIITI A SLOPE OF AT tEASr trl8-INCH DROP PER FOOT OF DRAIN. FTC DMIN NEIWORK E}TBEDDD IN WASHED CONCREIE AGGREGATE ENCASE ptPE tN 1/2' TO 1-1/2' SCREE{ED GRA\GL DflEND CRA\EL I.ATERAI."LY TO FOOTING AND AT tEASr 1/2 HE|GHT OF FooTING. Ru- ENNRE TRENCH WTTH GRA\IEL NOTE THE BOTTOM OF THE DRA,IN SHOUI.D BE AT I.EASf 2 INCHES BELOIY BOTTOM OF FOOTING AT THE HIGHEST POIhIT AT,ID SLOPE DOIVI.ITVARD TO A POSIITVE GRAVITY OI'IIET OR TO A SUMP WHERE TYATER CAI.I BE REMOVED FY PUMPING. BECK BUILDING COMPATW AWEETWATEII R/qNCH - GUEST CAEINS ProJect No. GSO6935.OOO-1 25-Rg Fts.12 TABLE I SUMMARY OF LABORATORY TESTING GTLIT PROJECT NO. cS06935.000-1 25-R3 ffi DESCRIPTION CLAY. SANDY (CL) CLAY, SANDY (CL) CLAY. SANDY (CL) CLAY, SANDY (CL) CLAY, SANDY (CL) PASSING NO.200 SIEVE (o/o\ a7 59 u 61 67 PERCENT SAND (o/o'l 13 31 13 PERCENT GRAVEL (o/o) 10 20 SOLUBLE SULFATES (o/o) *SWELL (o/ol PLASTICITY INDEX (o/"i 19 LIQUID LIMIT (o/o\ 39 DRY DENSITY (PCF) MOISTURE CONTENT (o/o\ 12.9 11-0 12.7 9.3 10.8 DEPTH (FEET) 5:7 6-7 4 67 6-7 EXPLORATORY BORING GC 2-A GC }A GC 3-B GC+A GC 4-B .SWELL MEASURED UNDER 1,OOO PSF APPLIED PRESSURE. NEGATIVE VALUE INDICATES CONSOLIDATION.Page 1 of 1 ffi APPENDIX A EXPLORATORY PIT PHOTOGRAPHS BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS cTLIT PROJECT NO. GS06935.000-125-R3 ffi Soils exposed in Guest Cabin 2 - Pit A Soils excavated from Guest Cabin 2 - Pit A BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS cTLIT PROJECT NO. GS06935.000-125-R3 A-1 ffi Soils exposed in Guest Cabin 2 - Pit B Soils excavated from Guest Cabin 2 - Pit B BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS cTLIT PROJECT NO. GS06935.000-125-R3 A-2 ffi Soils exposed in Guest Cabin 3 - Pit A Soils excavated from Guest Cabin 3 - Pit A ".. ..,'' .::. BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS oTLIT PROJECT NO. GS06935.000-125-R3 A-3 ffi Soils exposed in Guest Cabin 3 - Pit B Soils excavated from Guest Cabin 3 - Pit B BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS CTLIT PROJEcT NO. GS0693s.000-12s-R3 A-4 ffi Soils exposed in Guest Cabin 4 - Pit A '::::i.:.ri 1: Soils excavated from Guest Cabin 4 - Pit A BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS crLlT PROJECT NO. GS06935,000-125-R3 A-5 ffi Soils exposed in Guest Cabin 4 - Pit B Soils excavated from Guest Cabin 4 - Pit B BECK BUILDING COMPANY SWEETWATER RANCH - GUEST CABINS cTLIT PROJECT NO. GS06935.000-125-R3 A-6