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HomeMy WebLinkAboutSubsoils Test for Foundation DesignK+AKunar b Asssclatm Inc.* Geotechnical and Materials Engineers and Environmental Scientists An Employee Owned Company 2390 South Lipan Street Denver, CO 80223 phone: (303) 742-9700 email: kadenver@kumerusa.com www.kumarusa.com Office Locations: Denver (HO). Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit County, Colorado GEOTECHNICAL ENGINEERING STUDY PROPOSED SINGLE-FAMILY HOME RESIDENCE DEVELOPMENT SOUTHEAST OF 7985 COLORADO STATE HIGHWAY 13 RIFLE, COLORADO Prepare;B: Kamal M. Hasan, E.I. PREPARED FOR: Reviewed By: Joshua L. Barker, P.E. A,, '(_r ?I I li ATTENTION: MS. Dora Gomez SOUTHEAST SIDE OF 7985 COLORADO STATE HIGHWAY 13 RIFLE, COLORADO Project No. 25-6-193 October 8, 2025 Revised: March 4, 2026 TABLE OF CONTENTS PURPOSEAND SCOPE OF STUDY......................................................................................... 1 PROPOSEDCONSTRUCTION................................................................................................. 1 SITECONDITIONS................................................................................................................... 2 FIELDEXPLORATION............................................................................................................... 2 SUBSURFACECONDITIONS................................................................................................... 2 LABORATORYTESTING.......................................................................................................... 3 GEOTECHNICAL ENGINEERING CONSIDERATIONS............................................................ 3 SITEGRADING......................................................................................................................... 4 FOUNDATIONS.......................................................................................................................... G FOUNDATIONAND RETAINING WALLS.................................................................................10 FLOORSLABS.........................................................................................................................11 EXTERIORFLATWORK............................................................................................................11 UNDERDRAIN SYSTEM AND DAMP-PROOFING...................................................................12 SURFACEDRAINAGE.............................................................................................................12 CONTINUINGSERVICES........................................................................................................13 LIMITATIONS...........................................................................................................................13 FIG. 1 - LOCATION OF EXPLORATORY BORINGS FIG. 2 - LOGS OF EXPLORATORY BORINGS FIG. 3 - LEGEND AND NOTES FIG. 4 - SWELL -CONSOLIDATION TEST RESULTS TABLE I - SUMMARY OF LABORATORY TEST RESULTS Kumar & Associates, Inc 1 PURPOSE AND SCOPE OF STUDY This report presents the results of a geotechnical engineering study for the proposed single-family residence development located at the adjacent property on the southeast side of 7985 Colorado State Highway 13 in Rifle, Colorado. The project site is shown on Fig. 1. The study was conducted to characterize the general site subsurface conditions and provide geotechnical engineering recommendations to be used for design. The study was conducted in general accordance with the scope of work in our Proposal No. P6-25-235 to Ms. Dora Gomez, dated August 22, 2025. A field exploration program consisting of exploratory borings and a site reconnaissance was conducted to obtain information on the surface and subsurface conditions. Samples of the subsoils obtained during field exploration were tested in the laboratory to determine their classification and other engineering characteristics. The results of the field exploration and laboratory testing were analyzed to develop recommendations for foundation types, depths, and allowable pressures for the proposed structure foundations, floor slabs, and pavement design. This report summarizes the data obtained during this study and presents our conclusions, design recommendations, and other geotechnical engineering considerations based on the proposed construction and the subsoil conditions encountered. PROPOSED CONSTRUCTION Based on the information provided, we understand the project will consist of constructing a new at -grade single-family house and a pre-engineered metal barn structure. Based on the site plan provided, we understand the proposed house will have an approximate footprint of 2,250 square feet, and the proposed barn will have an approximate footprint of 4,800 square feet. A conceptual architectural plan was provided at the time of this report preparation. Based on the plan provided, we understand the proposed barn structure will be constructed in approximately the central portion of the site, and the proposed house will be constructed in the western portion of the property. Foundation loads are expected to be light, consistent with this type of construction. If the proposed construction varies significantly from that described above or depicted in this report, we should be notified to reevaluate the recommendations provided in this report. Kumar & Associates, Inc 2 SITE CONDITIONS At the time of the field exploration program, the site consisted of approximately 23.2 acres of vacant land. The site is bounded on the north by a residential property, on the east by Colorado State Highway 13, and on the south and west by undeveloped lands. Based on available topographic information, the site slopes down from west to east with about 40 to 45 feet of relief across the site. FIELD EXPLORATION The field exploration for the project was conducted on September 5, 2025. Two exploratory borings were drilled near the proposed development area to evaluate the subsurface conditions, as shown on Fig. 1. The borings were advanced with 4-inch diameter continuous flight solid stem augers powered by a truck -mounted CME-45 drill rig. The borings were logged by a representative of Kumar and Associates, Inc. Samples of the subsoils were taken with a 2-inch I.D. modified California liner sampler. The samplers were driven into the subsoils at various depths with blows from a 140-pound hammer failing 30 inches. Sampling with the 2-inch California liner sampler is similar to the standard penetration test ASTM Method D1586. When properly evaluated, penetration resistance values (blow counts) indicate the soil's relative density or consistency. Depths at which the samples were taken, and the blow counts, are shown on the Logs of Exploratory Borings, Fig. 2. The samples were returned to our laboratory for review by the project engineer and for laboratory testing. SUBSURFACE CONDITIONS Soil Types Encountered: The subsurface conditions encountered in Boring 1 consisted of about 1 foot of topsoil underlain by naturally deposited (natural) soil extending to the maximum drilled depth of about 35 feet. Boring 2 encountered pre-existing fill extending to natural soil at a depth of about 1.5 feet. The boring was terminated in natural soil at a depth of about 25 feet. The pre-existing fill consisted of sandy silt with frequent roots, and was slightly moist and tan to brown. The natural soil varied between cohesive and granular soils. The cohesive soil consisted of lean clay with variable silt and sand content. The cohesive soil was slightly moist to moist and tan to brown. The granular soil consisted of silty sand to clayey sand. The granular soil was slightly Kumar & Associates, Inc 3 moist and tan to brown. Based on blow counts, the natural cohesive soil was hard, and the natural granular soil was medium dense to dense. Groundwater: Groundwater was not encountered in the borings during the drilling. The borings were backfilled after drilling was completed. LABORATORY TESTING Laboratory testing performed on samples obtained from the exploratory borings consisted of natural moisture content, liquid limits, and swell -consolidation behavior. The laboratory test results are shown on the Logs of Exploratory Borings, Figure 4, and summarized in Table 1. Swell -Consolidation: Swell -consolidation tests were conducted on a representative sample of the pre-existing fill and a sample of the natural soil to determine the swell and/or compressibility potential under loading and when submerged in water. The samples were prepared and placed in a confining ring between porous discs, subjected to a surcharge pressure of 1,000 psf, and allowed to consolidate before being submerged in water. The samples were then inundated with water, and the change in sample height when deformation ceased was measured with a dial gauge. The samples were then loaded incrementally to maximum surcharge pressures of 3,000 psf or 5,000 psf, and the sample heights were monitored until deformation practically ceased under each load increment. Results of the in -situ swell -consolidation tests conducted on the relatively undisturbed drive samples are presented on Fig. 4 as plots of the curve of the final strain at each increment of pressure against the log of the pressure. Based on the results of the swell -consolidation testing, the pre-existing fill sample exhibited additional compression, and the natural soil sample exhibited moderate swell potential under the applied surcharge pressure when wetted. We believe the slight additional compression is primarily the result of sample disturbance and not indicative of collapsibility. GEOTECHNICAL ENGINEERING CONSIDERATIONS Subsurface data indicate that pre-existing fill and natural soils will likely be the predominant soil types encountered beneath shallow foundations, floor slabs, and flatwork. Shallow foundations and floor slabs placed on structural fill are considered feasible for the proposed house and barn. All pre-existing fill and topsoil should be removed from development areas to expose the underlying natural soils and replaced with structural fill, as recommended in the following sections of this report. Kumar & Associates, Inc 4 Kumar and Associates should observe the building and footing excavation areas prior to placement of footing concrete and structural fill materials to assess bearing conditions. Structural fill placement should be observed and tested for compaction by Kumar and Associates to document the recommendations in this report are implemented. As previously mentioned, expansive on -site natural clay soils were encountered at the site. The clay sample generally exhibited moderate swell potential when wetted. The samples tested generally had low in -situ moisture contents and high dry densities, which we believe resulted in higher swell potentials. We believe the swell potential can be greatly reduced through the process of moisture -conditioning as described in the "Site Grading and Earthwork" section of this report. As an alternative to shallow foundations, a deep foundation system consisting of helical piers is considered feasible for supporting the proposed barn. Shallow and deep foundation recommendations are presented in the FOUNDATIONS section of this report. SITE GRADING The following recommendations should be followed for grading, site preparation, and fill compaction. 1. Where fill is to be placed, loose or otherwise unsuitable materials should be removed prior to placement of new fill. The exposed soils should then be scarified to a depth of 8 inches, moisture conditioned, and compacted preferably by vibratory compaction equipment to the minimum requirements of the overlying fill. Soils should be compacted with appropriate equipment for the lift thickness placed. Lift thickness should be no more than 8 inches compacted at the recommended moisture content and to the minimum required density. 2. Permanent unretained cut and fill slopes should be graded at 2 horizontals to 1 vertical (2:1) or flatter, and protected against erosion by revegetation or other means. The risk of slope instability will increase if seepage is encountered in cuts, and flatter slopes may be necessary. If seepage is encountered in permanent cuts, an investigation should be conducted to determine if the seepage will adversely affect the cut stability. This office should review site grading plans for the project prior to construction. 3. Slopes of 4:1 or steeper should be benched to provide a sufficiently wide level bench surface for compaction. All backfill should be processed so that it does not contain rock Kumar & Associates, Inc 5 fragments and/or cobbles larger than 6 inches in diameter and placed at the recommended moisture content. 4. The fill should be uniformly graded to prevent nesting of large -sized gravel and cobbles. Suitability of On -Site Soil The on -site natural granular soils are suitable as backfill after processing to remove all plus 6- inch material, if encountered, and moisture treatment. The existing sand fill should be suitable for use as structural fill after processing to remove oversize rock and deleterious materials. Due to the expansive nature of the on -site natural cohesive soil, it should be moisture -treated prior to being used as structural fill. All new fill should be further evaluated by Kumar & Associates for suitability at the time of excavation. Topsoil, if encountered, is not suitable for reuse except in the upper 6 to 12 inches of backfill in landscape areas. Structural Fill Structural fill used for support of the proposed construction should consist of on -site processed soils or relatively well -graded imported granular material with 5 to 60 percent material passing the No. 200 sieve, 60 percent or more passing the No. 4 sieve, and no rocks larger than 6 inches. Structural fill should be properly placed and compacted to reduce the risk of settlement and distress. The Geotechnical engineer should evaluate the suitability of any proposed imported fill for its intended use. Fill Placement Criteria New fill placed at the site should be adjusted to a moisture content within 2 percentage points of optimum moisture content for granular materials and between optimum and 3 percentage points above optimum for clay materials. New fill should be placed in maximum 8-inch-thick loose lifts and compacted as specified below. Compaction Requirements The following compaction requirements should be used: Kumar & Associates, Inc TYPE OF FILL PLACEMENT SOIL TYPE - Compaction Percent (ASTM D698 — Standard Proctor) Below Foundations Structural Fill — 95% Foundation Wall Backfill Processed On -site or Structural Fill — 95% Below Floor Slabs Structural Fill — 95% Landscape Areas Processed On -site — 95% Below Concrete Flatwork/Pavements Structural Fill — 95% Utility Trenches As they apply to the finished area Excavation Considerations In our opinion, it is anticipated that the on -site soils encountered in the exploratory borings drilled for this study can be excavated with conventional heavy-duty construction equipment. Although not encountered in our borings, large -sized boulders should be anticipated in excavations, requiring suitable -sized excavation equipment to move and possible off -site disposal. TemporarV Excavation Slopes: We assume that the temporary excavations will be constructed by excavating the slopes to a stable configuration or stabilized using properly designed shoring. All excavations should be constructed in accordance with OSHA requirements, as well as state, local, and other applicable requirements. In our opinion, the on -site pre-existing fill and the natural granular soil should be classified as OSHA Type C soils. The natural cohesive soil should be classified as OSHA Type B soils. Excavations where perched water exists and seeps into the excavation are possible and could require much flatter side slopes than those allowed by OSHA. All excavations greater than 20 feet should be designed by a registered professional engineer. FOUNDATIONS Scread Foatin_gs: Considering the subsoil conditions encountered in the exploratory borings and the nature of the proposed construction, the proposed buildings may be founded on spread footings bearing on a minimum of 2 feet of properly compacted new structural fill extending to undisturbed natural soils. The design and construction criteria presented below should be observed for a spread footing foundation system. Kumar & Associates, Inc 7 1) Footings placed on a minimum of 2 feet of compacted new structural fill should be designed for a net allowable soil bearing pressure of 2,500 pounds per square foot (psf). Based on experience, we expect the settlement of footings designed and constructed as discussed in this section will be about 1 inch or less. 2) Footings should be designed for a minimum dead load pressure of 800 psf. To satisfy the minimum dead load pressure and minimum footing width criteria, it may be necessary to concentrate loads by using a grade beam and pad. If this system is used, a void should be provided beneath the grade beams and between pads. Wall -on -grade construction is not acceptable for achieving the minimum dead load pressure. 3) The footings should have a minimum width of 16 inches for continuous walls and 2 feet for isolated pads. 4) Exterior footings and footings beneath unheated areas should be provided with adequate soil cover above their bearing elevation for frost protection. Placement of foundations at least 36 inches below exterior grade, or in accordance with local building code requirements, is recommended for foundations bearing on the sand and gravel soils. Concrete should not be placed on frost, frozen soil, snow, or ice. Interior footings and/or thickened slab sections should bear a minimum of 12 inches below the base of the floor slab, or in accordance with local building code requirements. 5) Continuous foundation walls should be reinforced top and bottom to span local anomalies, such as by assuming an unsupported length of at least 10 feet. Foundation walls acting as retaining structures should also be designed to resist lateral earth pressures as discussed in the "Foundation and Retaining Walls" section of this report. 6) Existing fill, topsoil, and any loose or disturbed soils should be removed and replaced with properly compacted structural fill. 7) The exposed soil in footing areas should then be adjusted to within 2 percentage points of the optimum moisture content and recompacted to at least 95% of the standard Proctor (ASTM D698) maximum dry density. If water seepage is encountered, the footing areas should be dewatered before concrete placement, and we shall be contacted for further evaluation. Kumar & Associates, Inc o 8) Voids in the footing area subgrade created by boulder removal should be backfilled with properly compacted structural fill, lean mix "flow -fill' concrete, or structural concrete. 9) Structural fill used for support of the foundation should meet the requirements listed in the SITE GRADING section of this report. 10) A representative of the geotechnical engineer should observe all footing excavations prior to forming footings and concrete placement to evaluate bearing conditions. Helical Piers: As discussed in the GEOTECHNICAL ENGINEERING CONSIDERATIONS section of this report, a deep foundation consisting of helical piers is considered feasible for supporting the proposed barn. The axial design load of helical piers should be determined in general accordance with the current International Building Code (IBC), which states the allowable axial design load, Pa, should be determined as follows: Pa= 0.5 Pu, where Pu (the ultimate load) is the least value of: 1. Sum of the areas of the helical bearing plates times the ultimate bearing capacity of the soil or rock comprising the bearing stratum. 2. Ultimate capacity determined from well -documented correlations with installation torque. 3. Ultimate capacity determined from load tests. 4. Ultimate capacity of the pier shaft. 5. Ultimate capacity of pier couplings. 6. Sum of the ultimate axial capacity of helical bearing plates affixed to the pier. Items 1 through 3 are related to the geotechnical capacity of the piers; Items 4 through 6 are related to the structural capacity and should be evaluated by the structural engineer. The owner and structural designer should be aware that certain proprietary helical pier systems have been subjected to acceptance testing administered by the International Code Council (ICC), while other systems provided by specialty contractors may be fabricated according to designs by registered professional engineers. The certified systems have documentation that addresses many of the structural capacity issues, while the non -certified systems require structural design by an Kumar & Associates, Inc i' engineer. Many of the lighter -duty helical pier systems available, with working capacities on the order of 50 kips or less, are certified, which can simplify the design and submittal process. However, higher capacity systems, where single piers may have working capacities of 200 kips or more, sometimes referred to as screw piles, are often designed and fabricated and are not certified manufactured systems. Based on consideration of bearing capacity theory and published correlations of boring penetration resistance values with ultimate bearing capacity, we recommend an ultimate bearing capacity for a helical pier embedded to a minimum depth of 15 feet (measured from the ground surface) in the natural overburden clays of 7,500 psf, for capacity based on bearing provided by the helices. Helical piers are typically very slender foundation elements with a low capacity for resisting lateral loads. Lateral restraint of a helical pier foundation system is normally provided through the use of passive pressure on pier caps or foundation walls or through the use of battered piers. It is normally assumed that a battered pier can be designed for the same axial load as a vertical pier, with the lateral restraint being provided by the horizontal component of the battered pier. Helical piers are often assumed to have tension capacities similar to the axial compressive capacity, although that should be evaluated through load testing or otherwise addressed by the specialty contractor's submittal. Acceptance of helical pier installation should be based on attaining a specified torque in the recommended bearing stratum determined in accordance with correlations of installation torque to capacity based on calibrated torque measurements and axial load test data. In our opinion, the ultimate bearing capacity recommended above may be exceeded if supported by adequate site - specific load test data. If site -specific load tests are not performed, the specialty helical pier contractor's submittal should contain torque -to -capacity data for their pier system in similar soil conditions. If that information cannot be provided, site -specific load tests should be performed in accordance with ASTM D1143. We recommend that a qualified helical pier specialty contractor be retained to provide the required design submittal and to provide and install the helical piers. The project design should include a performance specification indicating required capacities, structural requirements, and submittal requirements. At a minimum, the submittal should be required to contain information supporting the capacity determination, a description of equipment and installation procedures that will ensure penetration to the required depths, and acknowledgment that the helical bearing plates will be Kumar & Associates, Inc 10 installed into the recommended bearing stratum, as well as all necessary information to satisfy the requirements of the project structural designer. We should be retained to review the contractor's submittal and to provide installation observation, including monitoring depths and general conformance with the plans and specifications. Our observation and testing services will be intended to document that all of the helix -bearing plates on the piers are installed into the design -bearing stratum. FOUNDATION AND RETAINING WALLS Although significant below grade construction is not currently anticipated, foundation walls and retaining structures (if constructed) which are laterally supported and can be expected to undergo only a slight amount of deflection should be designed for the at -rest lateral earth pressure computed on the basis of an equivalent fluid unit weight of at least 50 pounds per cubic foot (pcf) for backfill consisting of the on -site processed granular soils or suitable granular import. Cantilevered retaining structures, which are separate from the building foundation and can be expected to deflect sufficiently to mobilize the full active earth pressure condition, should be designed for lateral earth pressure computed on the basis of an equivalent fluid unit weight of at least 40 pcf for backfill consisting of the processed on -site granular soil or suitable granular import. The backfill should not contain rocks larger than 6 inches in diameter. The lateral resistance of foundation or retaining wall footings will be a combination of the sliding resistance of the footing on the foundation materials and passive earth pressure against the side of the footing. Resistance to sliding at the bottoms of the footings can be calculated based on a coefficient of friction of 0.40. Passive pressure of compacted backfill against the sides of the footings can be calculated using an equivalent fluid unit weight of 390 pcf. The coefficient of friction and passive pressure values recommended above assume ultimate soil strength. Suitable factors of safety should be included in the design to limit the strain which will occur at the ultimate strength, particularly in the case of passive resistance. Fill placed against the sides of the footings to resist lateral loads should be a suitable granular material compacted to at least 95% of the maximum standard Proctor dry density at a moisture content near optimum. All foundation and retaining structures should be designed for appropriate hydrostatic and surcharge pressures, such as adjacent footings, traffic, construction materials, and equipment. The pressures recommended above assume drained conditions behind the walls and a horizontal backfill surface. The buildup of water behind a wall or an upward -sloping backfill surface will Kumar & Associates, Inc m 11 increase the lateral pressure imposed on a foundation wall or retaining structure. An underdrain should be provided to limit hydrostatic pressure buildup behind walls. Backfill in pavement and walkway areas should be placed in uniform lifts and compacted to at least 95% of the maximum standard Proctor (ASTM D698) dry density. Backfill placed in landscape areas should be compacted to at least 95% of the maximum standard Proctor dry density at a moisture content near optimum. Care should be taken not to overcompact the backfill or use large equipment near the wall, since this could cause excessive lateral pressure on the wall. Some settlement of the deep foundation wall backfill should be expected, even if the material is placed correctly, and could result in distress to facilities constructed on the backfill. FLOOR SLABS Slabs -on -grade should be placed on a minimum of 3 feet of structural fill extending to undisturbed natural soils. To reduce the effects of some differential movement, floor slabs should be separated from all bearing walls and columns with expansion joints which allow unrestrained vertical movement. Floor slab control joints should be used to reduce damage due to shrinkage cracking. The requirements for joint spacing and slab reinforcement should be established by the designer based on experience and the intended slab use. All backfill below floor slabs should be placed in accordance with the SITE GRADING section of this report. We recommend vapor retarders conform to at least the minimum requirements of ASTM E1745 Class C material. Certain floor types are more sensitive to water vapor transmission than others. For floor slabs bearing on angular gravel or where a flooring system sensitive to water vapor transmission is utilized, we recommend using a vapor barrier conforming to the minimum requirements of ASTM E1745 Class A material. The vapor retarder should be installed in accordance with the manufacturers recommendations and ASTM 1643. EXTERIOR FLATWORK To limit potential post -construction movement, subgrade preparation beneath exterior flatwork immediately adjacent to the building, including sidewalks and patio areas, if constructed, where reduction of the potential for movement is considered critical, should be done in accordance with the recommendations provided in the "Floor Slabs" section of this report, including depth of overexcavation and backfilling with structural fill. Where reduction of the potential for movement is less of a concern, such as for sidewalks located more than 10 feet from the building, subgrade preparation may be performed in accordance with the subgrade preparation recommendations provided in the "Site Grading" section of this report. Proper surface drainage measures, as Kumar & Associates, Inc 12 recommended in the following sections of this report, are also critical to limiting moisture- or frost - related movement. UNDERDRAIN SYSTEM AND DAMP -PROOFING Groundwater was not encountered during our exploration, but it has been our experience in mountainous areas that groundwater levels can rise, and that local perched groundwater can develop during times of heavy precipitation or seasonal runoff. Frozen ground during spring runoff can create a perched water condition. We recommend below -grade construction (if planned), such as retaining walls, crawlspace, and basement areas, be protected from wetting and hydrostatic pressure buildup by an underdrain and wall drain system. Slab -on -grade, at -grade construction should not require an underdrain or damp -proofing. The underdrain should consist of a drainpipe placed in the bottom of the wall backfill, surrounded above the invert level with free -draining gravel. The drain should be placed at each level of excavation and at least 12 inches below the lowest adjacent finish grade and sloped at a minimum 1 % to a suitable gravity outlet, sump and pump system, or drywell. Free -draining gravel used in the underdrain system should contain less than 2% passing the No. 200 sieve, less than 50% passing the No. 4 sieve, and have a maximum size of 1-inch. The drain gravel backfill should be at least 1 Y2 feet deep and protected by filter fabric. Atypical drain detail is shown on Figure 6. For exterior below -grade foundation walls, we recommend, as a minimum, that damp -proofing consist of bituminous material, 3 Ibs per square yard, extending from the top of the footing to above ground level. A wall drain system consisting of a geocomposite, MiraDrain 6000, or equivalent, should be placed adjacent to below -grade construction walls, with 100 percent coverage on the foundation wall facing the uphill slope and a minimum of 50 percent coverage for the adjacent foundation walls. The wall drain system should connect to the underdrain and extend to within 1 to 2 feet of the ground surface. SURFACE DRAINAGE The following drainage precautions should be observed during construction and maintained at all times after the buildings have been completed: 1. Inundation of the foundation excavations and underslab areas should be avoided during construction. Kumar & Associates, Inc 13 2. Backfill in pavement and slab areas should be compacted to at least 95% of the maximum standard Proctor dry density at a moisture content within 2% of optimum. Exterior backfill placed in landscape areas should be compacted to at least 90% of the maximum standard Proctor dry density at a moisture content near optimum. 3. The ground surface surrounding the exterior of the building should be sloped to drain away from the foundation in all directions. We recommend a minimum slope of 6 inches in the first 10 feet in unpaved areas and a minimum slope of 3 inches in the first 10 feet in paved areas. These slopes may be changed as required for handicap access points in accordance with the Americans with Disabilities Act. 4. Roof downspouts and drains should discharge well beyond the limits of all backfill. CONTINUING SERVICES Two additional elements of geotechnical engineering service are important to the successful completion of this project. 1) Consultation with design professionals during the design phases. This is important to ensure that the intentions of our recommendations are properly incorporated in the design, and that any changes in the design concept properly consider geotechnical aspects. 2) Observation and monitoring during_ construction. A representative of the Geotechnical engineer from our firm should observe the foundation excavation, earthwork, and foundation phases of the work to determine that subsurface conditions are compatible with those used in the analysis and design, and our recommendations have been properly implemented. Placement of backfill should be observed and tested to judge whether the proper placement conditions have been achieved. We recommend a representative of the geotechnical engineer observe the drain and damp -proofing phases of the work, if constructed, to judge whether our recommendations have been properly implemented. LIMITATIONS This study has been conducted in accordance with generally accepted geotechnical engineering principles and practices in this area at this time. We make no warranty either express or implied. The conclusions and recommendations submitted in this report are based upon the data obtained from the exploratory borings at the locations indicated on Fig. 2, the proposed type of construction and our experience in the area. Kumar & Associates, Inc 14 Our services do not include determining the presence, prevention or possibility of mold or other biological contaminants (MOBC) developing in the future. If the client is concerned about MOBC, then a professional in this special field of practice should be consulted. Our findings include interpolation and extrapolation of the subsurface conditions identified at the exploratory borings and variations in the subsurface conditions may not become evident until excavation is performed. If conditions encountered during construction appear different from those described in this report, we should be notified so that re-evaluation of the recommendations may be made. This report has been prepared for the exclusive use by our client for design purposes. We are not responsible for technical interpretations by others of our information. As the project evolves, we should provide continued consultation and field services during construction to review and monitor the implementation of our recommendations, and to verify that the recommendations have been appropriately interpreted. RRK/db Rev: JLB cc: File Kumar & Associates, Inc 'i NW Corner Section 15 ase V; s>ti W 1 / 16 Comer Section I S tb 10 — 3.5" USGLO Brass Cap I 3" U$GLO Brass Cap _f 1975 N 89* 34'27' E� 133I.96' `-4r--r 1975 --- -- — - -- -.._ -- •- -- -- -- .. - - � k Gravel Driveway I o t.- Excrimrn ` -1` N64'08101'W 105,90 IN N46'10'32'W 771;58 —�� \ CConttrolMonument Irt *4* I L=391,62, R=2805;00 Culvert W S4c" 7 y3..�7 379.31 r-`.•'� I Cn Y 120' ROW Fence -,Oe 96' \\gook 260. Page 494 Power Linr \\ \\ CDO'I \\ Control Monument Graved I + \ Driveway 1 �pJ \\ 4fa \ \ \ 23.2 Acres t � 424.58. I '�s�, q„ \ i Proposed Building 125.00' Colorado Ute Electrical 80x60 . Crpstes�iioe �$ ky�G \ \\ v. Association Inc. Easetperft Gi, rnnlent 0%ti k Book 351, Page 562 BORING 1 • BORING 2 I \ ti , tiNo 5 Rebar 94. 10' \ 489'31'39'E 1960.20 I 2000 Access Road tasemenf lip \ Book 352, Page 234E - `- \ \ Ovc^. fiend Utility Imes 1 lIl \ (typical o RIFLE GAP sm STATE PARK SILT ANTLERS RIFLE INTERSTATE 70 150 0 150 300 APPROXIMATE SCALE —FEET VICINITY MAP NOT TO SCALE 25-6-193 Kumar & Associates I LOCATION OF EXPLORATORY BORINGS Fig. 1 BORING 1 BORING 2 c 0 0 47/12 8/12 36/12 17/12 5 WC=11 WC=6 5 DD=1 13 DD=1 11 -200=84 -200=55 LL= 24 LL=18 PI=7 PI=3 A-4 (4) A-4 (0) 38/12 36/12 10 10 20/12 26/12 15 WC=7 15 w DD=114 - w W -200=52 W j LL=20 = = C" d PI=4 a W W 24/12 fl 29/12 20 20 26/12 40/12 25 5 2 -� 35 24/12 23/12 E " A Cn O � O � w yn N � [S N O N N M P � .000. 25-6-193 Kumar & Associates 13 •. zi> 30 d j 35 —I LOGS OF EXPLORATORY BORINGS I Fig. 2 LEGEND M TOPSOIL. FILL: SANDY SILT (ML); FREQUENT ROOTS, SLIGHTLY MOIST, TAN TO BROWN. NA LEAN CLAY WITH VARIABLE SILT AND SAND CONTENT (CL-ML), HARD, SLIGHTLY MOIST TO © MOIST, TAN TO BROWN. SILTY SAND (SM) TO CLAYEY SAND (SC), ''. TO BROWN. MEDIUM DENSE TO DENSE, SLIGHTLY MOIST, TAN pDRIVE SAMPLE, 2-INCH I.D. CALIFORNIA LINER SAMPLE. 47/12 DRIVE SAMPLE BLOW COUNT. INDICATES THAT 47 BLOWS OF A 140-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE THE SAMPLER 12 INCHES. NOTES 1. THE EXPLORATORY BORINGS WERE DRILLED ON SEPTEMBER 5, 2025 WITH A 4-INCH-DIAMETER CONTINUOUS -FLIGHT POWER AUGER. 2. THE LOCATIONS OF THE EXPLORATORY BORINGS WERE LOCATED BY GPS COORDINATES OBTAINED FROM GOOGLE EARTH- AND LOCATED IN THE FIELD WITH A HANDHELD GPS UNIT. 3. THE ELEVATIONS OF THE EXPLORATORY BORINGS WERE NOT MEASURED AND THE LOGS OF THE EXPLORATORY BORINGS ARE PLOTTED TO DEPTH. 4. THE EXPLORATORY BORING LOCATIONS SHOULD BE CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD USED. 5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY BORING LOGS REPRESENT THE APPROXIMATE BOUNDARIES BETWEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE GRADUAL. 6. GROUNDWATER WAS NOT ENCOUNTERED IN THE BORINGS AT THE TIME OF DRILLING. 7. LABORATORY TEST RESULTS: WC = WATER CONTENT (%) (ASTM D2216); DD = DRY DENSITY (pcf) (ASTM D2216); -200= PERCENTAGE PASSING NO. 200 SIEVE (ASTM D1140); LL = LIQUID LIMIT (ASTM D4318); PI = PLASTICITY INDEX (ASTM D4318); A-4 (4) = AASHTO CLASSIFICATION (GROUP INDEX) (AASHTO M 145). 25-6-193 1 Kumar & Associates LEGEND AND NOTES Fig. 3 SAMPLE OF: Silty Clay with Sand (CL—ML) FROM: Boring 1 ® 4' WC = 11 %, DD = 113 pcf —200=84%,LL=24,PI=7 v 3 W EXPANSION UNDER CONSTANT PRESSURE UPON WETTING N 2 1 z O 1 a 0 J O 0 z O U —1 —2 1 La APPLIED PRESSURE - KSF 10 100 —^ SAMPLE OF: Fill: Sandy Silt (ML) FROM: Boring 2 ® 4' WC=6%,DD= 111 pcf —200=55%,LL= 18,PI=3 1 ADDITIONAL COMPRESSION —T UNDER CONSTANT PRESSURE C 3 DUE TO WETTING e%1 in 0 �— I 1 z S —1 � a � O � J � O z —2 v_ O v U v 0 —3 M Of I T�hrdprlrOre nenAb� �y odr to tM WI] fup, +�Ilkw�R Ih�s�l�►+7aQ�e�ef d N ifwnor mid A„eeiolr, ♦K r con.0udntlOn ueernq perlamtl � c1 nacaNa+e..me �sne u—as�6 -- 0 1 1.0 APPLIED PRESSURE — KSF 10 100 n v m 25-6-193 Kumar & Associates SWELL —CONSOLIDATION TEST RESULTS Fig. 4 y � S g 3 3 g ro 0 k nO A A \2 � 2 9 9 9 CD 0 $ / E / CDK)kk alma 0 ƒ ƒ 2 � � / 3 Cl)E � CD c 2 _ § c A � - U)fƒƒ a a � OD A m $ o ƒ CD oc3 rr k o k/\TO co & CD § c � Q A v k k / max0 / � G D D D ¢ �� -k? 0 0 - g % ¥ o X Cl) ƒ' @ «l<Uom §U® 0 a £ o Cf) 0 » CD / 0 k k � � 9 @ K) CJI 2/ o C x m £ g � § n O 2 2 w O m 3 £ � n 0 § � n 0 0 k 0