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Home My WebLink AboutGeotechnical Evaluation' ,,"- t. I.\ IfD ,,,) ENGINEERING Geotech n ical Eval uation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised Prepared For: Tectonic Management Group, lnc. 6695 West 48th Avenue Wheat Ridge, Golorado Attention: Mr. Kevin C. Larson Job Number: 22-6004 September 28,2022 41 lnvernessDriveEast I Englewood,C080112 | (303)289-1989 lwwwgroundeng.com ENGLEWOOD I COMMTRCE C|TY I TOVELAND I GRANBY I GYPSUM I COLORADO SPRINGS Approximate Project Area TABLE OF CONTENTS Purpose and Scope of Study Proposed Construction Site Conditions Su bsu rface Exploration Laboratory Testing Subsurface Conditions Seismic Classification Geotechnical Considerations for Design Shallow Foundations ............. Slab-on-Grade Floors Retaining Walls Lateral Loads Water Soluble Sulfates Soil Corrosivity Project Earthwork Excavation Considerations ......... Utility Lateral lnstallation Surface Drainage Subsurface Drainage Pavement Sections Exterior Flatwork Closure Locations of Test Holes Logs of the Test Holes Legend and Notes Gradation Test Results California Bearing Ratio Test Results Typical Underdrain Detail Summary of Laboratory Test Results ..... Detailed Logs of the Test Holes Page .. 1 ..2 ..3 ..4 ..5 ..5 ..8 ..9 .13 .15 .18 .19 .20 .21 .23 .27 .29 .32 .35 .37 .45 .48 re1Figu ...... Figure 2 ...... Figure 3 Figures 4 & 5 ...... Figure 6 ...... Figure 7 Tables 1 & 2 . Appendix A Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised PURPOSE AND SCOPE OF STUDY This report presents the results of a geotechnical evaluation performed by GROUND Engineering Consultants, lnc. (GROUND) in support of design of the proposed hangar at the Rifle Garfield County Airport in Rifle, Colorado. Our study was conducted in general accordance with GROUND's Proposal Number 2206-1064 dated June 1 ,2022 between Tectonic Management Group, lnc. and GROUND. A field exploration program was conducted to obtain information on the subsurface conditions. Material samples obtained during the subsurface exploration were tested in the laboratory to provide data on the classification and engineering characteristics of the on-site soils. The results of the field exploration and laboratory testing are presented herein. This report has been prepared to summarize the data obtained and to present our findings and conclusions based on the proposed development/improvements and the subsurface conditions encountered. Design parameters and a discussion of engineering considerations related to the proposed improvements are included herein. This report should be understood and utilized in its entirety; specific sections of the text, drawings, graphs, tables, and other information contained within this report are intended to be understood in the context of the entire report. This includes the Closure section of the report which outlines important limitations on the information contained herein. This report was prepared for design purposes of Tectonic Management Group, lnc., based on our understanding of the project at the time of preparation of this report. The data, conclusions, opinions, and geotechnical parameters provided herein should not be construed to be sufficient for other purposes, including the use by contractors, or any other parties for any reason not specifically related to the design of the project. Furthermore, the information provided in this report was based on the exploration and testing methods described below. Deviations between what was reported herein and the actual surface and/or subsurface conditions may exist, and in some cases those deviations may be significant. Job No. 22-6004 GROUND Engineering Consultants, Inc.Page 1 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised PROPOSED CONSTRUCTION We understand that present plansl call for a relatively tall, single-story hangar structure to be constructed on the east side of the Rifle Garfield County Airport. The structure is planned to be approximately 34,500 square-feet in footprint area and will contain an approximately 4,500 square-foot office area and an approximately 1,000 square-foot mezzanine level. Structural loads are anticipated to be relatively low to moderate, typical of this type of construction. No-below grade levels are planned at this time. We also understand that an aircraft apron / ramp is planned on the west side of the building. Automobile parking stalls and drive lanes are planned on the north and east sides of the building, and a relatively short retaining wall (less than 5 feet tall) is planned on the south side of the building. Additionally, we assume that new underground utilities will be provided for the new buildings. We understand that FAA aircraft pavement sections are not planned as part of construction or will be addressed by others. Grade changes at the site are anticipated to relatively small, on the order of 5 feet or less, and retaining walls are not planned at this time. lf our described understanding/interpretation of the proposed project is incorrect or project elements differ in any way from that expressed above, including changes to improvement locations, dimensions, orientations, loading conditions, elevations/grades, etc., and/or additional buildings/structures/site improvements are incorporated into this project, either after the original information was provided to us or after the date of this report, GROUND or another geotechnical engineer must be retained to re-evaluate the conclusions and parameters presented herein. Performance Expectations Based on our experience with similar projects, we understand that post-construction, building foundation and floor movements on the order of 1 inch are acceptable to, and anticipated by Tectonic Management Group, lnc., as are the resultant distress and maintenance measures. Similarly, we anticipate that I Attantic Aviation - Rifle Hangar, Conceptual Desrgn, TECTONIC Project No.: 202199, TECTONIC Management Group, lnc., SheetAl .00, May 19,2022. Job No. 22-6004 GROUND Engineering Consultants, lnc.Page 2 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised movements of somewhat greater magnitude (2 to 3 inches) are acceptable and anticipated for flatwork. Assuming that traffic speeds will be relatively low, still greater movements (3+ inches locally) are acceptable and anticipated for the parking area and drive-lane pavements, as well as for flatwork that is not adjacent to the building. GROUND will be available to discuss the risks and remedial approaches outlined in this report, as well as other potential approaches, upon request if post-construction movements of these magnitudes are not acceptable and anticipated. SITE CONDITIONS At the time of our subsurface exploration program, the site was largely undeveloped lot within an active airport. The proposed building footprint appeared to have been previously graded, but existing hangars, asphalt and concrete pavements and flatwork, utility easements, and other improvements were observed near the project site. The unpaved/unsurfaced areas of the project site, were largely covered with short to tall grasses and weeds. The project site was on a gently sloped crown, with relatively low angled swales on the south, east, and west sides of the site. Beyond the building footprint, the topography sloped gently to the north, displaying approximately 8 feet of relief between the building footprint and the north taxiway. Beyond the building footprint to the south, a shallow, north-facing slope displaying approximately 5 feet of relief separated the proposed building footprint from adjacent airport development. Review of historical aerial imagery available on Google Earth@ indicated that the site usage had not changed significantly since the early 1990s (earliest available images). However, periods of development that included the construction of new hangars, Job No. 22-6004 GROUND Engineering Gonsultants, lnc.Page 3 Geotechn ical Eval uation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised pavements, grading operations, and other improvements occurred during that time. Some grading appears to have occurred, both cuts and fills, within the proposed hangar footprint. ln general, former buildings, pavements, etc. did not appear to have occupied the proposed building footprint during our review. SUBSURFACE EXPLORATION Subsurface exploration for the project was conducted on July 18 and 19,2022. A total of 9 test holes were drilled with a conventional, truck-mounted drilling rig advancing 4-inch diameter, solid stem, continuous flight auger to evaluate the subsurface conditions and retrieve samples for laboratory testing. Of these, 5 test holes were advanced within the proposed approximate building footprint to depth of about 22 to 49 feet below existing grade. The remaining 4 test holes were advanced to depths of about 5 to 9 feet within the areas proposed for paving. A GROUND engineer directed the subsurface exploration, logged the test holes in the field, and prepared the samples for transport to our laboratory. Samples of the subsurface materials were retrieved with a 2-inch inner diameter California liner sampler and a 1Ta-inch inner diameter Standard Penetration Test sampler. The samplers were driven into the substrata with blows from a 140-pound hammer falling 30 inches, in general accordance with (in the case of the 1%-inch sampler) the Standard Penetration Test described by ASTM Method D1586. Penetration resistance values, when properly evaluated, indicate the relative density or consistency of soils. Depths at which the samples were obtained and associated penetration resistance values are shown on the test hole logs. The approximate locations of the test holes are shown in Figure 1. Summary logs of the test holes are presented in Figure 2. A legend and notes are provided in Figure 3. Detailed logs are provided in Appendix A. Job No. 22-6004 GROUND Engineering Gonsultants, lnc.Page 4 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised LABORATORY TESTING Samples retrieved from our test holes were examined and visually classified in the laboratory by the prolect engineer. Laboratory testing of soil samples included standard property tests, such as natural moisture contents, dry unit weights, grain size analyses, and Atterberg limits. Swell - consolidation, water-soluble sulfate content, and a suite of corrosivity tests were completed on selected samples as well. Additionally, California Bearing Ratio (CBR) testing was performed on a composite sample collected from the test holes. Laboratory tests were performed in general accordance with applicable ASTM protocols. Results of the laboratory testing program are summarized in Tables 1 and 2. Gradation plots are provided in Figures 4 and 5. The results of the CBR testing are provided in Figure 6. SUBSURFACE CONDITIONS Geologic Seffing Published geologic maps, e.9., Shorba and Scott (2001),2 depict the site as underlain by the Pleistocene Loess (Qlo). Holocene and Pleistocene Alluvium and Colluvium (Qac) and other alluvial and colluvial deposits were mapped in the greater project area. These surficial deposits are mapped as being underlain by the Eocene Shire Member of the Wasatch Formation (Tws). A portion of that map is reproduced below. Loess, an eolian (windblown) deposit, typically consists of fine sands and silts with varying fractions of clays. Weathering typically increases the clay contents of these deposits. Eolian deposits, such as loess, can be subject to hydro-consolidation (collapse). ln the project area, alluvial (stream, terrace, and outwash) deposits typically consist of fine to coarse sands, gravels, and cobbles with silts and clays. Boulders also can be present locally. The large clasts present in alluvial deposits may be awkward or difficult to handle and may not be appropriate for reuse in all project fills. The Shire Member of the Wasatch Formation, in the project area consists largely of claystones, siltstones, sandstones, and conglomerates. The formation includes well 2 Shroba, R.R. and Scott, R.8., 2001, Geotogy map of the Sitt quadrangle, Garfield County, Cotorado,lJ.S. Geological Survey, Miscellaneous Field Studies Map MF-233 1, 1 :24,000. Job No. 22-6004 GROUND Engineering Consultants, lnc.Page 5 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised cemented beds which can be very hard and difficult to excavate, handle, and/or process Additionally, the siltstones and claystones can be moderately to highly expansive. Local Conditions ln general, the test holes penetrated approximately 1 to 3 inches of topsoil3 before penetrating fill soils that were recognized to depths of about 15 to 23 feet below existing grade before penetrating. Beneath the fill soils, native sands, silts, and clays were encountered to the depths explored in Test Holes 1, 3, and 5 or to depths of about 42 feet below existing grade in Test Holes 2 and 4. Beneath the native soils, sandstone bedrock was encountered that extended to depths explored. We interpret the fill soils to be materials placed during the construction of the airport and related improvements. We native sands, silts, and clays to be interbedded alluvial and colluvial deposits and the sandstone to be Wasatch Formation. 3 'Topsoil' as used herein is defined geotechnically. The materials so described may or may not be suitable for landscaping or as a growth medium for plants that may be proposed for the project. er{Io 'ft ;r ] r" ':11 1 Approximate Project Site I', I 'I B 8o ! ii :, SP : .. -. Job No. 22-6004 GROUND Engineering Consultants, Inc.Page 6 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised Fill materials, were recognized in the test holes and are likely are present across the site. (See the Sde Conditions section of this report.) These fill soils may contain coarse gravels and cobbles, as well as similarly sized pieces of construction, debris even though these items where not recognized in the test holes. Delineation of the complete lateral and vertical extents of the fills at the site and their compositions was beyond our present scope of services. lf more detailed information regarding fill extents and compositions at the site are of significance, they should be evaluated using test pits. Similarly, coarse gravel and larger clasts are not well represented in small diameter liner samples collected from the test holes. Therefore, such materials may be present even where not called out in the material descriptions herein. Frll consisted of silts, clays, fine to coarse sands, and local gravels. Gravel sized clasts of sandstone, siltstone, and claystone bedrock were encountered locally. They were slightly dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. Sands, S/fs, and Clays consisted of clean to silty or clayey, fine to coarse sands, silts, and clays with local gravels and cobbles. They were dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. lron staining was encountered commonly. Caliche was encountered locally. Sandsfone Bedrock consisted of fine to medium grained sandstones with interbedded locally with claystones and siltstones. They were slightly moist, non- to moderately plastic, hard to very hard, and brown in color. Groundwafer was not encountered in the test holes at the time of drilling during to the depths explored. The test holes were backfilled upon drilling completion per Code of Colorado Regulations (2 CCR 402-2). Additionally, review of estimates of saturation of the samples suggested that the shallow site soils had not been saturated recently. Groundwater levels can be expected to fluctuate, however, in response to annual and longer-term cycles of precipitation, irrigation, surface drainage, nearby rivers and creeks, land use, and the development of transient, perched water conditions. The groundwater Job No. 22-6004 GROUND Engineering Consultants, Inc.Page 7 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised observations performed during our exploration must be interpreted carefully as they are short-term and do not constitute a groundwater study. ln the event the Tectonic Management Group, lnc. desires additional/repeated groundwater level observations, GROUND should be contacted; additional exploration and fees will be necessary in this regard. It has been our experience that surface and groundwater levels fluctuate greatly in mountainous areas, primarily due to seasonal conditions such as spring runoff. These conditions are often highly variable and difficult to predict. Although these conditions generally exist for 1 to 3 months annually, their impact on design can be significant. ln Garfield County, Colorado, it is common during construction to encounter dry conditions in the fall and wet conditions in the spring with relative groundwater fluctuations of 10 feet or more. This is particularly critical for foundation and deep utility excavations, cut slopes, culvert sizing, and for development adjacent to intermittently dry streams or rivers. Furthermore, if development has not established positive surface drainage, particularly prior to temporary winter shutdown procedures, other components of partial and complete development are compromised. The contractor and the project team should consider these complex conditions prior to commencing as well as during construction. Swell-Consolidation Testing of selected samples of on-site soils recovered from the test holes indicated consolidations of up to 3.3 percent and swells of up to approximately 0.4 percent under various surcharge loads approximating in-place overburden pressures. (See Table 1.) SEISMIC CLASSIFICATION Based on extrapolation of available data to depth and our experience in the project area, we consider the area of the proposed addition likely to meet the criteria for a Seismic Site Classification of D according to the ASCE 7-16 (Table 20.3-1). (Exploration and/or shear wave velocity testing to a depth of 100 feet or more was not part of our present scope of services.) lf, however, a quantitative assessment of the site seismic properties is desired, then shear wave velocity testing should be performed. GROUND can provide a fee estimate for shear wave velocity testing upon request. We consider the likelihood of achieving a Site Class C to be low. Job No. 22-6004 GROUND Engineering Consultants, Inc.Page 8 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised Using longitude and latitude coordinates obtained from Google Earth and the ASCE 7 Hazard Tool (https:llasceThazardtool.online/), the project area is indicated to possess an Sos volue of 0.347 and an Sor value of 0.123 for the site latitude and longitude and a Site Class of D. GEOTECHNICAL CONSIDERATIONS FOR DESIGN The conclusions and parameters provided in this report were based on the data presented herein, our experience in the general project area with similar structures, and our engineering judgment with regard to the applicability of the data and methods of forecasting future performance. A variety of engineering parameters were considered as indicators of potential future soil movements. Our parameters and conclusions were based on our judgment of "likely movement potentials," (i.e., the amount of movement likely to be realized if site drainage is generally effective, estimated to a reasonable degree of engineering certainty) as well as our assumptions about the owner's willingness to accept ge otechnical risk. "Maximum possible" movement estimates necessarily will be larger than those presented herein. They also have a siqnificantly lower likelihood of beinq realized. in our opinion, and generally require more expensive measures to address. We encourage Tectonic Management Group, lnc., upon receipt of this report, to discuss the risks and the geotechnical information presented in this report with us. Depth of Wetting at the Site The "depth of wetting" (the depth to which foundation soils will gain moisture and experience volume change over the design-life of a structure) estimated for a given site strongly affects the anticipated performance of structures at that site. Based on the data obtained at this site and our experience with similar geotechnical settings, a "depth of wetting" of 20 feet was used to develop geotechnical parameters for foundation system design. A depth of wetting of 20 feet is equal to or greater than the depth of wetting found at about 72 percent of the sites evaluated in a study by Walsh and others (2009).4 a Walsh, K.D., C.A. Colby, W.N. Houston and S.A. Houston, 2009, Method for Evaluation of Depth of Wetting in Residential Areas, Journal of Geotechnical and Geoenvironmental Engineering, American Society of Civil Engineers, Vol. 135, No. 2, pp. 169 - 176. Job No. 22-6004 GROUND Engineering Consultants, Inc.Page 9 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised "Depths of wetting" of 30, 40, or 70 feet or more have been considered (e.9., Chao and others, 2006)5 and have been encountered locally in the field. Depths of wetting of such magnitudes, however, generally are in unusual geologic conditions, such as the Dipping Bedrock Overlay District near Denver, Colorado, or identified forensically in unusual circumstances such as a pipe leak that has remained unrepaired for an extended period. ln our experience, such deep 'depths of wetting' are considered only rarely in engineering consulting practice in more typical geologic settings in the Western Slope atea. GROUND considers wetting to a depth of 20 feet to be appropriately conservative for the proposed project. However, if Tectonic Management Group, lnc. prefers that a more conservative (or less conservative) depth be used to develop geotechnical parameters for design, GROUND should be contacted to revise the criteria provided herein. General Geotechnical Risk ln GROUND's opinion, the primary geotechnical risk to new construction at this site is presence of undocumented fill soils which were recognized to irregular depths between about 15 and 23 feet below existing grade. (This irregular depth of undocumented fill likely reflects the antecedent topography of the area.) Testing records for the fill were not available for review. GROUND therefore, cannot guarantee that these fill soils were placed in a controlled manner or that the compaction criteria used, if any, was suitable to support the proposed construction. Additionally, swell-consolidation testing of these fill soils yielded consolidations of up to about 3.3 percent under loads approximating in place overburden pressures. For these reasons, GROUND considers these fill soils to be undocumented fill soils that are unsuitable to support to the proposed construction. Undocumented fills commonly have varying compositions and constituencies, and often do not provide laterally consistent support to new improvements. Where improvements are underlain by undocumented fill soils in the greater project area, damaging post- construction movements have resulted. Where they are present beneath a proposed improvement, undocumented fill soils will need to be removed and replaced as properly compacted fill or the effects of undocumented fill soils othenvise mitigated. 5 Chao, K-C, D.D. Overton, and J.D. Miller, 2006, The Effects of Sife Conditions on the Predicted Time Rate of Heave, Unsaturated Soils 2006, American Society of Civil Engineers, Special Publication No. 147, pp. 2086 - 2097. Job No. 22-6004 GROUND Engineering Gonsultants, Inc.Page 10 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised Likely Posf-construction Movemenfs Based on our data, the selected depth of wetting, and our experience with similar sites, we estimate improvements supported directly on the existing site soils are subject to likely, post-construction, vertical movements of 3 to 6 inches where improvements bear directly on the existing undocumented fill soils. Lateral movements will result, as well. Foundation and slab/flatwork movements of these magnitudes can result in significant damage. Nearly all of the proposed improvements are vulnerable in this regard. Building Foundation and Floor Types ln GROUND's opinion, supporting the proposed buildings on drilled pier or driven pile foundation systems will provide the lowest estimates of likely post-construction foundation movement (about /, inch, with similar differential movements over spans of about 40 feet) and will provide the least risk of excessive foundation movements. However, deep foundation systems may not be practical because they may not be required to carry the structural loads and because the depth to bedrock at the site is relatively great. (Bedrock was encountered at 42 feet in two of the test holes.) Constructing the lowest level building floors as structural floors, also supported on drilled piers or driven piles, will yield similarly low post-construction floor movement estimates. Exterior flatwork adjacent to the building, particularly at and near building entrances also should be constructed as structural floors in such cases. Geotechnical parameters for drilled pier / driven pile foundations and structural floors can be provided upon request, but additional geotechnical evaluation will be required. As a higher risk but commonly used alternative, shallow foundations and slab-on-grade floors appear to be geotechnically feasible at this site, provided that they are founded upon improved (densified) soils. At this site, rammed aggregate piers appear to be able to reduce estimates of post-construction movements to about 1 inch or possibly less. Rammed aggregate piers are proprietary systems developed by specialty designer/installers. The allowable bearing capacity, number, and depth/length of the individual elements, are determined by the specialty designer/installer. The data in this report should be sufficient for the designer/installer to provide their design, but GROUND may be contacted if additional geotechnical data is needed. Job No. 22-6004 GROUND Engineering Consultants, lnc.Page 1 1 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised For additional information, w€ suggest contacting a qualified and experienced designer/installer of these systems. We suggest contacting the following firms for additional information, though others may be available: Ground lmprovement Engineering 816 I 421 - 4334a a Keller (Hayward Baker) 303 / 469 - 1 136 As an alternative to rammed aggregate piers, remedial fill sections are commonly used to improve site soils. Due to the depth of excavation required to remove and replace all of the undocumented fill and the proximity of existing improvements, we anticipate that the use of rammed aggregate piers will be more practical for the project. Additionally, rammed aggregate piers likely will provide a higher bearing capacity than a remedial fill section and, in our opinion, will have a lower likelihood of the post-construction movement estimates provided in this report being exceeded. Such additional greater than forecast movements could result from complications during the construction of a remedialfill section. At this site, a remedial fill section would need to extend to a depth that removes and replace all of the undocumented fill soils beneath the building footprint. Based on the information collected from our test holes, we anticipate that this would require excavations to a depth of about 23 feet below existing grade, though greater depths of fill could be encountered. Post-construction movements for improvements bearing on such a fill section are estimated by GROUND to be aboul 1/z inch, and we understand that movements of these magnitudes likely will not be acceptable for the project. Should those estimates of post-construction movements be acceptable, GROUND can provide parameters for shallow foundations and slab-on-floors bearing on a remedial fills section. More detailed geotechnical parameters for design of shallow foundations and slab-on- grade floors supported on soils improved by rammed aggregate piers are provided in subsequent sections of this report. ln general, we anticipate that the majority of the existing site soils will be suitable geotechnically to be reused as fill. Retaininq Walls Job No. 22-6004 GROUND Engineering Gonsultants, Inc Page 12 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised We understand a relatively short retaining wall is planned along the south side of the proposed building. Due to the close proximity of the proposed wall to the building, the wall could bear on the site soils improved by installation of a limited number of additional rammed aggregate piers. This presumably would result in post-construction movements similar to the building (1 inch or possibly less). As a higher risk alternative, the retaining wall could be supported directly on the existing site soils, but doing so would entail a risk of 3 to 6 inches of likely post-construction vertical movements. Boulder-stack and mechanically stabilized earth walls generally are more tolerant of such post-construction movement than rigid wall types, such as concrete walls. Additional retaining wall considerations and parameters are provided in the Retaining Wall section of this report. SHALLOW FOUNDATIONS The geotechnical parameters below may be used for design of foundations for the proposed building. Geotechnical Parameters for Shallow Foundation Desiqn 1)Footings should bear on soils improved by rammed aggregate piers as discussed in the Geotechnical Considerations for Design section of this report. 2)Footings bearing on soils improved by rammed aggregate piers may be designed based on an allowable bearing capacity provided by the rammed aggregate pier designer/installer. To reduce differential settlements between footings or along continuous footings, footing loads should be as uniform as possible. Differentially loaded footings will settle differentially. 3)Spread footings should have a minimum lateral dimension of 16 or more inches for linear strip footings and 24 or more inches for isolated pad footings. Actual footing dimensions should be determined by the structural engineer. 4)Footings should bear at an elevation 36 or more inches below the lowest adjacent exterior finish grades to have adequate soil cover for frost protection. Job No. 22-6004 GROUND Engineering Gonsultants, lnc.Page 13 5) 6) 7) 8) Geotechn ical Eval uation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised Continuous foundation walls should be reinforced as designed by a structural engineer to span an unsupported length of at least 10 feet. Geotechnical parameters for lateral resistance to foundation loads are provided in the Lateral Loads section of this report. Connections of all types must be flexible and/or adjustable to accommodate the anticipated, post-construction movements of the structure. To the extent possible, utility lines should not be routed under shallow foundations, particularly isolated pad foundations, nor in the soils supporting the foundations. Where doing so cannot be avoided, there is increased risk to both the pipe and the foundation. Measures should be included in design to protect the footings and structure from increased settlement, and to protect the pipe from deformation. Where utility lines penetrate footings or stem walls, etc., measures should be included to accommodate the likely total and differential, post-construction movements discussed in this report. Some footings also may experience lateral displacements as structural loads are applied. S h al I ow Fo u ndation Co nstru ctio n The contractor should take adequate care when making excavations not to compromise the bearing or lateral support for nearby improvements. 10) Care should be taken when excavating the foundations to avoid disturbing the supporting materials particularly in excavating the last few inches. 11) Footing excavation bottoms may expose loose, organic, or otheruvise deleterious materials, including debris. Firm materials may become disturbed by the excavation process. All such unsuitable materials should be excavated and replaced with properly compacted fill or the foundation deepened. 12) Foundation-supporting soils may be disturbed or deform excessively under the wheel loads of heavy construction vehicles as the excavations approach footing e) Job No. 22-6004 GROUND Engineering Consultants, Inc Page 14 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised bearing levels. Construction equipment should be as light as possible to limit development of this condition. The movement of vehicles over proposed foundation areas should be restricted. 13) All foundation subgrade should be compacted prior to placement of concrete 14) Fill placed against the sides of the footings should be properly compacted in accordance with the Project Earthwork section of this report. SLAB.ON.GRADE FLOORS The geotechnical parameters below may be used for design of slab-on-grade floors for the proposed buildings. ACI Sections 30113021360 provide guidance regarding concrete slab-on-grade design and construction. for of Slab-on-Grade 1)A slab-on-grade floor system should bear on soils improved by rammed aggregate piers as discussed in the Geotechnical Considerations for Design section of this report. 2)Floor slabs should be adequately reinforced. thickness, concrete strength, jointing, and developed by a structural engineer. Floor slab design, including slab slab reinforcement should be 3) 4) An allowable vertical modulus of subgrade reaction (Kv) provided by the rammed aggregate pier designer/installer may be used for design of a concrete, slab-on- grade floor bearing on soils improved by rammed aggregate piers. Floor slabs should be separated from all bearing walls and columns with slip joints, which allow unrestrained vertical movement. Slip joints should be observed periodically, particularly during the first several years after construction. Slab movement can cause previously free-slipping joints to bind. Measures should be taken to assure that slab isolation is maintained in order to reduce the likelihood of damage to walls and other interior improvements. Job No. 22-6004 GROUND Engineering Consultants, Inc.Page 15 5) Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised Concrete slabs-on-grade should be provided with properly designed control joints. ACl, AASHTO, and other industry groups provide guidelines for proper design and construction concrete slabs-on-grade and associated jointing. The design and construction of such joints should account for cracking as a result of shrinkage, curling, tension, loading, and curing, as well as proposed slab use. Joint layout based on the slab design may require more frequent, additional, or deeper joints, and should reflect the configuration and proposed use of the slab. Particular attention in slab joint layout should be paid to areas where slabs consist of interior corners or curves (e.9., at column blockouts or reentrant corners) or where slabs have high length to width ratios, significant slopes, thickness transitions, high traffic loads, or other unique features. lmproper placement or construction will increase the potential for slab cracking. lnterior partitions resting on floor slabs should be provided with slip joints so that if the slabs move, the movement cannot be transmitted to the upper structure. This detail is also important for wallboards and doorframes. Slip joints should allow 11/z inches or more of vertical, differential movement. Accommodation for differential movement also should be made where partitions meet bearing walls. Post-construction heave may not displace slab-on-grade floors and utility lines in the soils beneath them to the same extent. Design of floor penetrations, connections, and fixtures should accommodate up to 2 inches of differential movement. Moisture can be introduced into a slab subgrade during construction and additional moisture will be released from the slab concrete as it cures. A properly compacted layer of free-draining gravel, 4 or more inches in thickness, should be placed beneath the slabs. This layer will help distribute floor slab loadings, ease construction, reduce capillary moisture rise, and aid in drainage. Selection and specification of sub-slab gravel should be coordinated with soil gas mitigation systems, where such systems are used. 7) 6) 8) Job No. 22-6004 GROUND Engineering Consultants, Inc.Page 16 e) Geotechn ical Eval uation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised The free-draining gravel should contain less than 5 percent material passing the No. 200 Sieve, more than 50 percent retained on the No. 4 Sieve, and a maximum particle size of 2 inches. The capillary break and the drainage space provided by the gravel layer also may reduce the potential for excessive water vapor fluxes from the slab after construction as mix water is released from the concrete. We understand, however, that professional experience and opinion differ with regard to inclusion of a free-draining gravel layer beneath slab-on-grade floors. lf these issues are understood by the owner and appropriate measures are implemented to address potential concerns including slab curling and moisture fluxes, then the gravel layer may be deleted. A vapor barrier beneath a building floor slab can be beneficial with regard to reducing exterior moisture moving into the building, through the slab, but can retard downward drainage of construction moisture. Uneven moisture release can result in slab curling. Elevated vapor fluxes can be detrimental to the adhesion and performance of many floor coverings and may exceed various flooring manufacturers' usage criteria. Per the 2006 ACI Location Guideline, a vapor barrier is required under concrete floors when that floor is to receive moisture-sensitive floor covering andior adhesives, or the room above that floor has humidity control. Therefore, in light of the several, potentially conflicting effects of the use vapor- barriers, the owner and the architect and/or contractor should weigh the performance of the slab and appropriate flooring products in light of the intended building use, etc., during the floor system design process and the selection of flooring materials. Use of a plastic vapor-barrier membrane may be appropriate for some building areas and not for others. ln the event a vapor barrier is utilized, it should consist of a minimum 15 mil thickness, extruded polyolefin plastic (no recycled content or woven materials), maintain a permeance less than 0.01 perms per ASTM E-96 or ASTM F-1249, Job No. 22-6004 GROUND Engineering Consultants, Inc.Page 17 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised and comply with ASTM E-1745 (Class "A"). Vapor barriers should be installed in accordance with ASTM E-1643. Polyethylene ("poly") sheeting (even if 15 mils in thickness which polyethylene sheeting commonly is not) does not meet the ASTM E-1745 criteria and should not be used as vapor barrier material. lt can be easily torn and/or punctured, does not possess necessary tensile strength, gets brittle, tends to decompose over time, and has a relatively high permeance. Construction Considerations for Slab-on-Grade Floors 10) Loose, soft, or otherwise unsuitable materials exposed on the prepared surface on which the floor slab will be cast should be excavated and replaced with properly compacted fill. 11) The fill section beneath a slab should be of uniform thickness 12) Concrete floor slabs should be constructed and cured in accordance with applicable industry standards and slab design specifications. 13) AII plumbing lines should be carefully tested before operation. Where plumbing lines enter through the floor, a positive bond break should be provided. RETAINING WALLS We understand a relatively short retaining wall (less than 5 feet tall) is planned along the south side of the proposed building. Although the type of the wall was unknown at the time of this report revision, we understand a boulder-stack wall may be considered. Geotechnical parameters for fill placement and compaction are provided in the Project Earthwork section of this report. lt must be understood the wall will move after completion and that movement generally will be noticeably differential. Bearing capacity for the retaining wall should be developed by the wall designer or the rammed aggregate pier designer/installer based on the width of the wall reinforced zone using the parameters presented below for retaining wall design and Meyerhoff or other appropriate bearing capacity methods. Movement potential and services limit states Job No.22-6004 GROUND Engineering Gonsultants, lnc Page 18 Geotechn ical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised should be evaluated by the wall designer based on the soil conditions and anticipated wall bearing pressure. Based on the geotechnical data from the test holes drilled relatively near the proposed wall alignment, we anticipate that the wall subgrade materials will typically consist exiting fill soils consisting of sands, silts, and clays. Estimated soil parameters for use in the retaining wall design for on-site material are summarized in the following table. These values must be verified prior to and during the wall construction. lt should be noted these tabulated values do not reflect improvement of the soils by installation of rammed aggregate piers and that direct shear testing was not performed. 34135CDOT Class 1 Structure Backfill 20120 Existing Fill (Sands, Silts, and Clays) lnternal Frictlon Angle (degrees) Moist Unit Weight @cA Material Type It should be noted that soil strength could be significantly reduced if the soils become wetted, and earth pressures realized that are greater than those tabulated above. Therefore, effective surface drainage near the wall should be included in project design, and drainage should be maintained effectively after construction. Wall Drainage Effective drainage of the retaining wall will be critical to the retaining wall's performance. Heel drains, weep holes, and other drainage elements should be considered to provide the retaining wall with effective drainage. GROUND can provide a typical heel drain detail upon request. LATERAL LOADS Values for equivalent fluid pressures and the coefficient for frictional resistance to sliding are provided below. These values were based on moist unit weight (y) of 120 pcf and an angle of internal friction (Q) of 20 degrees for site soils re-worked as properly Job No. 22-6004 GROUND Engineering Gonsultants, lnc.Page 19 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised compacted fill and are un-factored. Appropriate factors of safety should be included in design calculations. Shallow Elements Resisfing Lateral Loads A friction coefficient of 0.24 between a foundation element and the site soils may be used for design of shallow foundations and thrust blocks resisting lateral loads. Passive soil pressure at this site may be estimated using an equivalent fluid pressure of 210 pct for drained conditions, to a maximum of 2,100 psf. The upper 1 foot of embedment should be neglected for passive resistance, however. Where passive soil pressure is used to resist lateral loads, it should be understood that significant lateral strains will be required to mobilize the full value indicated above, likely 1 inch or more. A reduced passive pressure can be used for reduced anticipated strains, however. Af-Resf and Active Lateral Earth Pressures Site soils placed as backfill against a structure in an at-rest condition may be considered to exert an equivalent fluid unit weight of 80 pcf. Site soils placed as backfill where the full, active earth pressure condition applies may be considered to exert an equivalent fluid unit weight of 59 pcf. WATER.SOLU BLE SU LFATES The concentration of water-soluble sulfates measured in selected samples of site soils were approximately 0.01 and 0.03 percent by weight., (See Table 2.) Such a concentration of soluble sulfates represents a negligible environment for sulfate attack on concrete exposed to these materials. Degrees of attack are based on the scale of 'negligible,' 'moderate,' 'severe' and 'very severe' as described in the "Design and Control of Concrete Mixtures," published by the Portland Cement Association (PCA). The Colorado Department of Transportation (CDOT) utilizes a corresponding scale with four classes of severity of sulfate exposure (Class 0 to Class 3) as described in the table below. Reoutneve NTS To Pnorrcr AcRrrusr DAMAGE To Coucnrre BY SULFATE ArrRcr FRoM ExTcRTRT SOunCES OF SULFATE Job No. 22-6004 GROUND Engineering Consultants, Inc.Page 20 Class 30.4010,001 or greater2.01 or greaterClass 3 Class 20.451501 to 10,000O.21to2.OAClass 2 Class 10.45151 to 15000.11 to 0.20Class 1 Class 00.450to f500.00 to 0.10Class 0 Cementitious Material Requirements Water Gementitious Ratio (maximum) Sulfate (SOn) ln Water (ppm) Water-Soluble Sulfate (SOr=) ln Dry Soil (%) Severity of Sulfate Exposure Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised Based on our test results and PCA and CDOT guidelines, sulfate-resistant cement should be used in all concrete exposed to site soils, conforming to one of the following Class 0 requirements: Class 0 (Neqliqible) 1)ASTM C150 Tvpe I, ll, lll, or V 2)ASTM C595 Tvpe lL. lP. lP(MS). lP(HS), or lT SOIL CORROSIVITY Data were obtained to support an initial assessment of the potential for corrosion of ferrous metals in contact with earth materials at the site, based on the conditions at the time of GROUND's evaluation. The test results are summarized in Table 2. Reduction-Oxidation testing indicated red-ox potentials of approximately -59 and -95 millivolts. Such low potentials typically create a more corrosive environment. Sulfide Reactivity testing indicated a'trace'and 'positive' results in the local soils. The presence of sulfides in the soils suggests a more corrosive environment. Sofl Resistivity ln order to assess the "worst case" for mitigation planning, samples of materials retrieved from the test holes were tested for resistivity in the laboratory, after being saturated with water, rather than in the field. Resistivity also varies inversely with temperature. Therefore, the laboratory measurements were made at a controlled Job No. 22-6004 GROUND Engineering Gonsultants, lnc.Page 21 Geotechnical Eval uation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised temperature. Measurement of electrical resistivity indicated a value of approximately 7,400 ohm-centimeters in a sample of site soils. pH Where pH is less than 4.0, soil serves as an electrolyte; the pH range of about 6.5 to 7.5 indicates soil conditions that are optimum for sulfate reduction. ln the pH range above 8.5, soils are generally high in dissolved salts, yielding a low soil resistivity.6 Our testing indicated pH values of about 8.2 and 8.8. Corrosivity Assessmenf The American Water Works Association (AWWA) has developed a point system scale used to predict corrosivity. The scale is intended for protection of ductile iron pipe but is valuable for project steel selection. When the scale equals 10 points or higher, protective measures for ductile iron pipe are indicated. The AWWA scale is presented below. The soil characteristics refer to the conditions at and above pipe installation depth. We anticipate that drainage at the site after construction will be effective. Nevertheless, based on the values obtained for the soil parameters, the fill and native soils appear to comprise a severely corrosive environment for ferrous metals (1 1% points). lf additional information or evaluation is needed regarding soil corrosivity, then the American Water Works Association or a corrosion engineer should be contacted. lt should be noted, however, that changes to the site conditions during construction, such as the import of other soils, or the intended or unintended introduction of off-site water, m ight alter corrosion potentials sig n ificantly. Table A.1 Soil-Test Evaluation Soil Characteristic / Value Redox Potential < 0 (negative values) 0 to +50 mV.......... +50 to +100 mV ....... > +100 mV ....... Sulfide Reactivity Positive Trace Negative 6 American Water Works Association ANSI/AWWA C1051A21.5-05 Standard Points 5 4 3% 0 3% 2 0 Job No. 22-6004 GROUND Engineering Gonsultants, Inc.Page 22 Geotechnical Eval uation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised Soil Resistivity <1,500 ohm-cm 1,500 to 1,800 ohm-cm 1,800 to 2,100 ohm-cm 2,100 to 2,500 ohm-cm 2,500 to 3,000 ohm-cm >3,000 ohm-cm pH 0 to 2.0 2.01o 4.0 4.0 to 6.5 6.5 to 7.5 7.5 to 8.5 >8.5 .......... Moisture Poor drainage, continuously wet Fair drainage, generally moist Good drainage, generally dry . lf sulfides are present and low or negative redox-potential obtained, add three (3) points for this range. 0I 5 2 1 0 5 3 0 0 0 3 1 2 1 0 results (< 50 mV) are PROJECT EARTHWORK The earthwork criteria below are based on our interpretation of the geotechnical conditions encountered in the test holes. Where these criteria differ from applicable municipal specifications. e.q., for trench backfill compaction alonq a public utilitv line. the latter should be considered to take precedence. General Considerations Project grading should be performed as early as possible in the construction sequence to allow settlement of fills and surcharged ground to be realized to the greatest extent prior to subsequent construction. Prior to earthwork construction, existing construction debris, vegetation, and other deleterious materials should be removed and disposed of off-site. Relic underground utilities should be abandoned in accordance with applicable regulations, removed as necessary, and properly capped. Topsoil and other organic materials present on-site should not be incorporated into ordinary fills. lnstead, topsoil should be stockpiled during initial grading operations for placement in areas to be landscaped or for other approved uses. These materials Job No. 22-6004 GROUND Engineering Gonsultants, Inc Page 23 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised should be removed and replaced where fill will be placed above them or where they will be beneath a proposed improvement. Use of Existing Fill Soils Fill materials were recognized in the test holes during our subsurface exploration, and likely are present elsewhere on the site, given the apparent grading. (See the Site Conditions section of this report.) Because not all of fill soils were sampled or tested, it is possible that, some of the fill soils may not be suitable for re-use as compacted fill, due to the presence of deleterious materials such as trash, organic material, coarse cobbles and boulders, or construction debris. Therefore, excavated fill materials should be evaluated and tested, as appropriate, with regard to re-use. We anticipate, however, that the majority of the existing site fill soils will be suitable for reuse as fill. Additionally, it should be noted that environmental assessment of the suitability of the existing fill was not part of our scope of services. lf this is a concern for the project team, an environmental consultant should be retained. Use of Existing Native Soils Based on the samples retrieved from the test holes, we anticipate that the existing site soils that are free of organic materials, coarse cobbles, boulders, or other deleterious materials will be suitable, in general, for re-use as compacted fill. Fragments of rock and cobbles, (as well as inert construction debris, e.9., concrete or asphalt) up to 3 inches in maximum dimension may be included in project fills, in general. Such materials should be evaluated on a case-by-case basis, where identified during earthwork. S/fy Soils Significant portions of the site soils are silty. Such materials commonly require greater than typical efforts to place as compacted fill because they can become unstable and difficult to compact at moisture contents near or above the optimum. Stable and compacted soils can become unstable if allowed to become wetted. The contractor should be prepared to work in these materials, or to export and replace them. lmported Fill Materials Materials imported to the site as (common) fill should be free of organic material, and other deleterious materials. lmported material should exhibit 65 Job No. 22-6004 GROUND Engineering Consultants, lnc.Page 24 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised percent or less passing the No. 200 Sieve and a plasticity index of 10 or less. Materials proposed for import should be approved prior to transport to the site. Fill Platform Preparation Prior to filling, the top 12 inches of in-place materials on which fill soils will be placed (except for utility trench bottoms where bedding will be placed) should be scarified, moisture conditioned and properly compacted in accordance with the criteria below to provide a uniform base for fill placement. lf surfaces to receive fill expose loose, wet, soft, or otherurrise deleterious material, additional material should be excavated, or other measures taken to establish a firm platform for filling. A surface to receive fill must be effectively stable prior to placement of fill, including trench bottoms prior to placement of bedding. General Considerations for Fill Placemenf Fill soils should be thoroughly mixed to achieve a uniform moisture content, placed in uniform lifts not exceeding 8 inches in loose thickness, and properly compacted. Excavated bedrock materials, such as those present in the existing fill, will require a well-coordinated effort to moisture treat, process, place, and compact properly. ln-place bedrock fragments were hard to very hard, and should be broken down in to a soil-like mass. Greater than typical watering, and compaction equipment that aids in breaking down such material (e.9., a Caterpillar 825 compactor-roller), likely will be needed. Crushing or other methods should be anticipated to sufficiently reduce sandstone bedrock fragments where encountered. Applied water will be taken up into the structures of the claystone. The contractor should anticipate that handlinq and orocessinq the excavated bedrock more than once may be necessary to achieve the requirements herein Excavated bedrock, such as those present in the existing fill, to be used as trench backfill, will require additional moisture conditioning and processing in an open area outside of trenches prior to placement as backfill. No fill materials should be placed, worked, rolled while they are frozen, thawing, or during poor/inclement weather conditions. Job No. 22-6004 GROUND Engineering Consultants, Inc.Page 25 Geotech n ical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised Where soils on which foundation elements will be placed are exposed to freezing temperatures or repeated freeze - thaw cycling during construction - commonly due to water ponding in foundation excavations - bearing capacity typically is reduced and/or settlements increased due to the loss of density in the supporting soils. After periods of freezing conditions, the contractor should re-work areas affected by the formation of ice to re-establish adequate bearing support. Care should be taken with regard to achieving and maintaining proper moisture contents during placement and compaction. Materials that are not properly moisture conditioned may exhibit significant pumping, rutting, and deflection at moisture contents near optimum and above. The contractor should be prepared to handle soils of this type, including the use of chemical stabilization, if necessary. Compaction areas should be kept separate, and no lift should be covered by another until relative compaction and moisture content within the specified ranges are obtained. Compaction Criteria Soils that classify as GP, GW, GM, GC, SP, SW, SM, or SC in accordance with the USCS classification system (granular materials) should be compacted to 95 or more percent of the maximum dry density at moisture contents within 2 percent of the optimum moisture content as determined by ASTM D1557, the 'modified Proctor.' Soils that classify as ML, MH, CL, or GH should be compacted to at least 95 percent of the maximum dry density at moisture contents between 1 percent below and 3 percent above the optimum moisture content as determined by ASTM D698, the 'standard Proctor.' lJse of Sgueegee Relatively uniformly graded fine gravel or coarse sand, i.e., "squeegee," or similar materials commonly are proposed for backfilling foundation excavations, utility trenches (excluding approved pipe bedding), and other areas where employing compaction equipment is difficult. ln general, this procedure should not be followed for the following reasons. Job No. 22-6004 GROUND Engineering Gonsultants, Inc.Page 26 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised Although commonly considered "self-compacting," uniformly graded granular materials require densification after placement, typically by vibration. The equipment to densify these materials is not available on many job-sites. Even when properly densified, uniformly graded granular materials are permeable and allow water to reach and collect in the lower portions of the excavations backfilled with those materials. This leads to wetting of the underlying soils and resultant potential loss of bearing support as well as increased local heave or settlement. Wherever possible, excavations should be backfilled with approved, on-site soils placed as properly compacted fill. Where achieving adequate compaction is difficult, then Controlled Low Strength Material" (CLSM), i.e., a lean, sand-cement slurry ("flowable fill") or a similar material should be used for backfilling. Where "squeegee" or similar materials are proposed for use by the Contractor, the design team should be notified by means of a Request for lnformation (RFl), so that the proposed use can be considered on a case-by-case basis. Where "squeegee" meets the project requirements for pipe bedding material, however, it is acceptable for that use. Settlemenfs Settlements will occur in newly filled ground, typically on the order of 1 to 2 percent of the fill depth. This is separate from settlement of the existing soils left in place. For an 18-foot fill, for example, that corresponds to a total settlement of about 3 inches. lf fill placement is performed properly and is tightly controlled, in GROUND's experience the majority (on the order of 60 to 80 percent) of that settlement typically will take place during earthwork construction, provided the contractor achieves the compaction levels indicated herein. The remaining potential settlements likely will take several months or longer to be realized, and may be exacerbated if these fills are subjected to changes in moisture content. Cut and Filled Slopes Permanent, un-retained, graded slopes supported by local soils up to 10 feet in height should be constructed no steeperthan 3 : 1 (horizontal : vertical). Minor raveling or surficial sloughing should be anticipated on slopes cut at this angle until vegetation is well re-established. Surface drainage should be designed to direct water away from slope faces into designed drainage pathways or structures. Job No. 22-6004 GROUND Engineering Gonsultants, Inc.Page 27 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised Steeper slope angles and heights may be possible but will require detailed slope stability analysis based on final proposed grading plans. A geotechnical engineer should be retained to evaluate this on a case-by-case basis. EXCAVATION CONSIDERATIONS Excavation Difficulty Test holes for the subsurface exploration were advanced to the depths indicated on the test hole logs by means of conventional, truck-mounted, geotechnical drilling equipment. Therefore, in general, we anticipate no unusual excavation difficulties in these materials, in general, for the proposed construction with conventional, heavy duty, excavating equipment. However, given the inherent nature of undocumented fill soils, materials that may be awkward or otherwise difficult to handle (e.9., relatively large pieces of construction or bedrock debris) may be encountered, even though these were not recognized in the test holes. (See the Site Conditions section of this report.) Temporary Excavations and Personnel Safety Excavations in which personnel will be working must comply with all applicable OSHA Standards and Regulations, particularly CFR 29 Part 1926, OSHA Standards-Excavations, adopted March 5, 1990. The contractor's "responsible person" should evaluate the soil exposed in the excavations as part of the contractor's safety procedures. GROUND has provided the information in this report solely as a service to Tectonic Management Group, lnc., and is not assuming responsibility for construction site safety or the contractor's activities. The contractor should take care when making excavations not to compromise the bearing or lateral support for any adjacent, existing improvements. Temporary, un-shored excavation slopes up to 20 feet in height, in general, should be cut no steeper than 11/z: 1 (horizontal : vertical) in the on-site soils in the absence of seepaqe. Some surface sloughing may occur on the slope faces at these angles. Should site constraints prohibit the use of the above-indicated slope angle, temporary shoring should be used. GROUND is available to provide shoring design upon request. Stockpiling of materials should not be permitted closer to the tops of temporary slopes than 5 feet or a distance equal to the depth of the excavation, whichever is greater. Job No. 22-6004 GROUND Engineering Consultants, lnc.Page 28 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised Groundwafer Groundwater was not encountered in the test holes at the depths explored. Therefore, based on conditions at the time of this subsurface exploration, relatively shallow excavations at the site appear unlikely to encounter groundwater except, limited volumes of perched groundwater. Significant volumes of perched or transient groundwater could be encountered at shallow depths, during period of seasonal runoff, significant snowmelt events, and/or after relatively large precipitation events. Should seepage or flowing groundwater be encountered in project excavations, the slopes should be flattened as necessary to maintain stability or a geotechnical engineer should be retained to evaluate the conditions. The risk of slope instability will be significantly increased in areas of seepage along excavation slopes. Surtace Water The contractor should take pro-active measures to control surface waters during construction and maintain good surface drainage conditions to direct waters away from excavations and into appropriate drainage structures. A properly designed drainage swale should be provided at the tops of the excavation slopes. ln no case should water be allowed to pond near project excavations. Temporary slopes should also be protected against erosion. Erosion along the slopes will result in sloughing and could lead to a slope failure. UTILITY LATERAL INSTALLATION The measures and criteria below are based on GROUND's evaluation of the local, geotechnical conditions. Where the parameters herein differ from applicable municipal requirements. the latter should be considered to govern. Pipe Supporf The bearing capacity of the site soils appeared adequate, in general, for support of typical utility lines. The pipes + contents are less dense than the soils which will be displaced for installation. Therefore, in general GROUND anticipates no significant pipe settlements in these materials where properly bedded from loading alone. Job No. 22-6004 GROUND Engineering Consultants, Inc Page29 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised Trench bottoms may expose existing fill soils, or soft, loose, or otherwise deleterious materials. Firm materials may be disturbed by the excavation process. All such unsuitable materials should be excavated and replaced with properly compacted fill. Areas allowed to pond water will require excavation and replacement with properly compacted fill. The contractor should take particular care to ensure adequate support near pipe joints which are less tolerant of extensional strains. Where thrust blocks are needed, the parameters provided in the Lateral Loads section of this report may be used for design. Trench Backfilling Some settlement of compacted soil trench backfill materials should be anticipated, even where all the backfill is placed and compacted correctly. Typical settlements are on the order of 1 to 2 percent of fill thickness. However, the need to compact to the lowest portion of the backfill must be balanced against the need to protect the pipe from damage from the compaction process. Some thickness of backfill may need to be placed at compaction levels lower than specified (or smaller compaction equipment used together with thinner lifts) to avoid damaging the pipe. Protecting the pipe in this manner can result in somewhat greater surface settlements. Therefore, although other alternatives may be available, the following options are presented for consideration: Controlled Low Strenqth Material Because of these limitations, the entire depth of the trench (both bedding and common backfill zones) should be backfilled with "controlled low strength material" (CLSM), i.e., a lean, sand-cement slurry, "flowable fill," or similar material alonq all trench alionment reaches with low tolerances for surface settlements. CLSM used as pipe bedding and trench backfill should exhibit a 28-day unconfined compressive strength between 50 to 150 psi so that re-excavation is not unusually difficult. Placement of the CLSM in several lifts or other measures likely will be necessary to avoid 'floating' the pipe. Measures also should be taken to maintain pipe alignment during CLSM placement. Job No. 22-6004 GROUND Engineering Consultants, lnc.Page 30 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised Compacted Soil Backfillinq ln areas that are tolerant of surface settlements, conventional soil backfilling may be used. Where compacted soil backfilling is employed, using the site soils or similar materials as backfill, the risk of backfill settlements entailed in the selection of this higher risk alternative must be anticipated and accepted by Tectonic Management Group, lnc. We anticipate that the on-site soils excavated from trenches will be suitable, in general, for use as common trench backfill within the above-described limitations. Backfill soils should be free of vegetation, organic debris and other deleterious materials. Fragments of rock, cobbles, and inert construction debris (e.9., concrete or asphalt) coarser than 3 inches in maximum dimension should not be incorporated into trench backfills. Soils placed for compaction as trench backfill should be conditioned to a relatively uniform moisture content, placed and compacted in accordance with the parameters in the Project Earthwork section of this report. Pipe Bedding Pipe bedding materials, placement and compaction should meet the specifications of the pipe manufacturer and applicable municipal standards. Bedding should be brought up uniformly on both sides of the pipe to reduce differential loadings. As discussed above, the use of CLSM or similar material in lieu of granular bedding and compacted soil backfill should be considered where the tolerance for surface settlement is low. (Placement of CLSM as bedding to at least 12 inches above the pipe can protect the pipe and assist construction of a well-compacted conventional backfill, although possibly at an increased cost relative to the use of conventional bedding.) lf a granular bedding material is specified, with regard to potential migration of fines into the pipe bedding, design and installation should follow ASTM D2321, Appendix X1.8. lf the granular bedding does not meet filter criteria for the enclosing soils, and we don't anticipate that it will, then non-woven filter fabric (e.9., Mirafi@ 140N, or the equivalent) should be placed around the bedding to reduce migration of fines into the bedding which can result in severe, local surface settlements. Where this protection is not provided, settlements can develop/continue several months or years after completion of the project. ln addition, clay or concrete cut-off walls should be installed to interrupt the Job No. 22-6004 GROUND Engineering Consultants, Inc.Page 31 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised granular bedding section to reduce the rates and volumes of water transmitted along the sewer alignment which can contribute to migration of fines. lf granular bedding is specified, the contractor should not anticipate that the shallow on- site soils may be suitable for that use with significant processing. Materials proposed for use as pipe bedding should be tested for suitability prior to use. Other Considerations Because of the potential for local consolidation and heave of undocumented fill soils to result in significant, extensional strains to utility pipes, pipes should be provided with restrained joints to reduce the potential for failure at joints. Connections to the building or other structures should be flexible and easily replaced or adjusted. Non-pressurized lines should be evaluated periodically for deformations such as pipe 'bellies' that would impair their efficiency, and appropriate repairs made. Maintenance plans should anticipate greater than typical utility line maintenance and replacement because of the undocumented fill soils that will remain beneath utility lines. SURFACE DRAINAGE The site soils are relatively stable with regard to moisture content - volume relationships at their existing moisture contents. Other than the anticipated, post-placement settlement of fills, post-construction soil movements will result primarily from the introduction of water into the soils underlying the proposed structure, hardscaping, and pavements. Based on the site surface and subsurface conditions encountered in this study, we do not anticipate a rise in the local water table sufficient to approach foundation or floor elevations. Therefore, local saturation of project foundation soils likely will result from infiltrating surface waters (precipitation, irrigation, etc.), and water flowing along constructed pathways such as bedding in utility pipe trenches. The following drainage measures should be followed both for during construction and as part of project design. The facility should be observed periodically to evaluate the surface drainage and identify areas where drainage is ineffective. Routine maintenance of site drainage should be undertaken throughout the design life of the proposed facility. Maintenance should be anticipated to include removal and replacement of sidewalk stones, curb and qutter. sections of pavement. etc., to restore effective drainaqe. lf Job No. 22-6004 GROUND Engineering Consultants, Inc Page 32 Geotechnical Eval uation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised these measures are not implemented and maintained effectively, the movement estimates provided in this report could be exceeded. 1)Wetting or drying of the underslab areas should be avoided during and after construction. Permitting increases/variations in moisture to the adjacent or supporting soils may result in increased total and/or differential movements. 2)Measures for positive surface drainage away from the building should be provided and maintained to reduce water infiltration into foundation soils. Underdrains should not be relied upon in surface drainage design to collect and discharge surface waters. A minimum slope of 12 inches in the first 10 feet in the areas not covered with pavement or concrete slabs should be established. For areas covered with asphalt pavement or concrete slabs, slopes should comply with ADA requirements where required. lncreasing slopes to a minimum of 3 percent in the first 10 feet in the areas covered with pavement or concrete slabs will reduce, but not eliminate, the potential for moisture infiltration and subsequent volume change of the underling soils. ln no case should water be allowed to pond near or adjacent to foundation elements, hardscaping, etc. 3)Drainage also should be established and maintained to direct water away from sidewalks and other hardscaping as well as utility trench alignments which are not tolerant of increased post-construction movements. The ground surface near foundation elements should be able to convey water away readily. Cobbles or other materials that tend to act as baffles and restrict surface flow should not be used to cover the ground surface near the foundations. Where the ground surface does not convey water away readily, additional post- construction movements and distress should be anticipated. Job No. 22-6004 GROUND Engineering Gonsultants, lnc.Page 33 4) 5) 6) 7) Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised ln GROUND's experience, it is common during construction that in areas of partially completed paving or hardscaping, bare soil behind curbs and gutters, and utility trenches, water is allowed to pond after rain or snow-melt events. Wetting of the subgrade can result in loss of subgrade support and increased settlements. By the time final grading has been completed, significant volumes of water can already have entered the subgrade, leading to subsequent distress and failures. The contractor should maintain effective site drainage throughout construction so that water is directed into appropriate drainage structures. ln no case should water be permitted to pond adjacent to or on sidewalks, hardscaping, or other improvements as well as utility trench alignments, which are likely to be adversely affected by moisture-volume changes in the underlying soils or flow of infiltrating water. Roof downspouts and drains, if used, should discharge well beyond the perimeter of the structure foundation, or be provided with positive conveyance off-site for collected waters. Downspouts should not be routed to discharge into an underdrain system. lf roof downspouts and drains are not used, then surface drainage design should anticipate concentrated volumes of water adjacent to the buildings. lrrigation water - both that applied to landscaped areas and over-spray - commonly is a significant cause of distress to improvements. Where (near-) saturated soil conditions are sustained, distress to nearby improvements should be anticipated. To reduce to potential for such distress, vegetation requiring watering should be located 10 or more feet from the building perimeter, flatwork, or other improvements. lrrigation sprinkler heads should be deployed so that applied water is not introduced near or into foundation/subgrade soils. Landscape irrigation should be limited to the minimum quantities necessary to sustain healthy plant growth. Job No. 22-6004 GROUND Engineering Gonsultants, Inc.Page 34 Geotechn ical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised Use of drip irrigation systems can be beneficial for reducing over-spray beyond planters. Drip irrigation also can be beneficial for reducing the amounts of water introduced to building foundation soils, but only if the total volumes of applied water are controlled with regard to limiting that introduction. Controlling rates of moisture increase beneath the foundations, floors and other improvements should take higher priority than minimizing landscape plant losses. Where plantings are desired within 10 feet of the building, plants should be placed in watertight planters, constructed either in-ground or above-grade, to reduce moisture infiltration in the surrounding subgrade soils. Planters should be provided with positive drainage and landscape underdrains. As an alternative involving only a limited increase in risk, the use of watertight planters may be replaced by local, shallow underdrains beneath the planter beds. 8)Plastic membranes should not be used to cover the ground surface near the building without careful consideration of other components of project drainage. Plastic membranes can be beneficial to directing surface waters away from the building and toward drainage structures. However, they effectively preclude evaporation and transpiration of shallow soil moisture. Therefore, soil moisture tends to increase beneath a continuous membrane. Where plastic membranes are used, additional shallow, subsurface drains should be installed. Perforated "weed barrier" membranes that allow ready evaporation from the underlying soils may be used. SUBSURFACE DRAINAGE As a component of project civil design, properly functioning, subsurface drain systems ("underdrains") can be beneficial for collecting and discharging saturated subsurface waters. Although the subsurface drainage system anticipated for this project may consist of perimeter underdrains along the building perimeter and underdrains constructed beneath floor system, they are addressed as underdrains herein. Underdrains will not collect water infiltrating under unsaturated (vadose) conditions, or moving via capillarity, however. ln addition, if not properly constructed and maintained, Job No. 22-6004 GROUND Engineering Consultants, Inc.Page 35 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised underdrains can transfer water into foundation soils, rather than remove it. This will tend to induce heave or settlement of the subsurface soils, and may result in distress. Underdrains can, however, provide an added level of protection against relatively severe post-construction movements by draining saturated conditions near individual structures should they arise, and limiting the volume of wetted soil. It is GROUND's opinion that it will be beneficial to include a perimeter underdrain system to help limit wetting of the foundation bearing soils. However, we understand that the owner and project team may consider that the reduction of risk provided by a properly constructed and maintained underdrain system does not justify the costs associated with including an underdrain. ln such a case, an underdrain system can be excluded. lf an underdrain system is excluded, then there will be an increased risk of the likely post construction movements estimated in this report being exceeded. GROUND considers this risk to be low, but it is not zero. Where an underdrain system is excluded, extra care should be taken to establish and maintain effective surface drainage, identify and repair wet utility leaks in a timely manner, seal open cracks joints, and restore effective surface drainage as necessary to limit the volume of water infiltrating the site. lf a below grade level is included, then an underdrain should be included. lf the below- grade level underlies only a portion of the building, then the underdrain could be limited to the below grade area. Damp-proofing should be applied to the exteriors of below- grade elements. The provision of Tencate MiraFi@ G-Series backing (or comparable wall drain provisions) on the exteriors of (some) below-grade elements may be appropriate, depending on the intended use. GROUND is available to discuss the above options and as well as other underdrain alternatives upon request. Geotechnical Parameters for Underdrain Design Where underdrains are included as a part of facility drainage design at depths less than 10 feet, underdrain design should incorporate the parameters below. The actual underdrain layout, outlets, and locations should be developed by a civil engineer. A typical, cross-section detail of an underdrain that may be implemented for this project is provided in Figure 7. Job No. 22-6004 GROUND Engineering Gonsultants, lnc.Page 36 2) s) Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised An underdrain system should be tested by the contractor after installation and after placement and compaction of the overlying backfill to verify that the system functions properly. 1)An underdrain system for a building should consist of perforated, rigid, PVC collection pipe at least 4 inches in diameter, non-perforated, rigid, PVC discharge pipe at least 4 inches in diameter, free-draining gravel, and filter fabric. The free-draining gravel should be naturally occurring (not recycled) material with 5 percent or less passing the No. 200 Sieve and 50 percent or more retained on the No. 4 Sieve, and have a maximum particle size of 2 inches. Each collection pipe should be surrounded on the sides and top (only) with 6 or more inches of free-draining gravel. The gravel surrounding the collection pipe(s) should be wrapped with filter fabric (Mirafi 140N@ or the equivalent) to reduce the migration of fines into the drain system. 4)The underdrain system should be designed to discharge at least 10 gallons per minute of collected water. 5)The high point(s) for the collection pipe flow lines should be below the grade beam or shallow foundation bearing elevation as shown on the detail. Multiple high points can be beneficial to reducing the depths to which the system would be installed. The collection and discharge pipe for the underdrain system should be laid on a slope as determined by the underdrain designer. Underdrain 'clean-outs'should be provided at intervals of no more than 150 feet to facilitate maintenance of the underdrains. Clean-outs also should be provided as near as practical to collection and discharge pipe elbows of 60 degrees or more. Job No. 22-6004 GROUND Engineering Consultants, lnc.Page 37 6) 7) Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised lf a below grade level is included, the underdrain system should include both a perimeter drain and lateral drains. Lateral drains should be spaced such that no point of the basement floor is more than 50 feet horizontally from a perimeter or lateral drain collection pipe. The underdrain discharge pipes should be connected to one or more sumps from which water can be removed by pumping, or to outlet(s) for gravity discharge. We suggest that collected waters be discharged directly into the storm sewer system, if possible. 8)Regular maintenance of the underdrain systems should be performed to ensure that the system continues work properly. PAVEMENT SECTIONS A pavement section is a layered system designed to distribute concentrated traffic loads to the subgrade. Performance of the pavement structure is directly related to the physical properties of the subgrade soils and traffic loadings. Standard practice in pavement design describes a typical flexible pavement section as a "2}-year" design pavement. However, a pavement should not be anticipated to remain in satisfactory condition without routine maintenance and rehabilitation procedures performed throughout the life of the pavement. Pavement sections for the private pavements at the subject facility were developed in general accordance with the guidelines and procedures of the American Association of State Highway and Transportation Officials (AASHTO) and local pavement construction practice. Note that the pavement sections provided in this report consider only automobile traffic and light aircraft traffic, and may not be appropriate for areas subject to larger, heavier aircraft. Subgrade Materials Our data indicate that the shallow soils at the site classify primarily as A-4 soils with group index values up to 5 in accordance with the AASHTO Job No. 22-6004 GROUND Engineering Consultants, Inc.Page 38 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised classification system. Such soils generally provide relatively poor to moderate subgrade support. California Bearing Ratio testing was performed on a composite sample of site soils, and the results of that testing are present in Figure 6. Based on the results of the CBR testing, we estimated that a resilient modulus value of 4,000 psi would be representative of the site soils and was used to develop the pavement sections. lt is important to note that significant decreases in soil support have been observed as the moisture content increases above the optimum. Pavements that are not properly drained may experience a loss of the soil support and subsequent reduction in pavement life. Anticipated Traffic Project-specific traffic loads had not been provided to GROUND at the time of preparation of this report. Therefore, assumed traffic loadings were used to develop the pavement section alternatives based on our experience with similar facilities. An ESAL value of 22,000 (corresponding to an EDLA value of 3 for a2}-year design life) was assumed for parking stalls for light vehicles (automobiles and similar). An ESAL value of 73,000 (corresponding to an EDLA value of 10 for a 2}-year design life) was assumed for the parking lot and individual building driveways. An ESAL of 365,000 (corresponding to an EDLA value of 50 for a 2}-year design life) was estimated for the heavy-duty pavements (i.e. hangar aprons/ramps, heavy truck routes, loading and unloading areas, trash collection routes, etc.). lf design traffic loadings differ significantly from these assumed values, GROUND should be notified to re-evaluate the pavement sections below. Pavement Secfions The soil resilient modulus and the ESAL values were used to determine the required structural number for the project pavements which then was then used to develop the pavement sections based on the DARW|nTM computer program that solves the 1993 AASHTO pavement equations. A reliability level of 85 percent and a terminal serviceability of 2.0 were utilized for design of the pavement sections. A structural coefficient of 0.44 was used for hot bituminous asphalt and 0.12 was used for aggregate base course. The minimum pavement sections for a 2Q-year design are tabulated below. Job No. 22-6004 GROUND Engineering Gonsultants, Inc.Page 39 Geotech nical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised Minim u m Pavement Secfions Truck routes, truck loading and unloading areas, trash collection areas, hangar aprons/ramps, and other pavement areas subjected to high turning stresses, heavy truck traffic, or high point-loading should be provided with rigid pavements consisting of 61/z or more inches of portland cement concrete underlain by 6 inches of properly compacted CDOT Class 6 Aggregate Base Course. A theoretically equivalent flexible pavement section for these areas would be 5 inches of asphalt over 10 inches of aggregate base course. However, in our experience, asphalt pavements will not perform as well as rigid pavement in areas of repeated turning stresses or static loading. Pushing, rutting, and tearing of the asphalt should be anticipated, with local ponding of water, and additional maintenance costs should be anticipated if this section were selected. Pavement Materials Asphalt pavement should consist of a bituminous plant mix composed of a mixture of aggregate and bituminous material. Asphalt mixture(s) should meet the requirements of a job-mix formula established by a qualified engineer as well as applicable municipal design requirements. Aggregate base material should meet the criteria of CDOT Class 6 Aggregate Base Course. Base course should be placed in and compacted in accordance with the standards in the Project Earthwork section of this report. Aggregate composed of recycled asphalt should not be expected to provide the same support for the wearing course as native, Class 6 material and should not be considered as an equivalent for it. Our experience suggests that recycled asphalt is difficult to compact properly when placed and can hold water after the wearing course is placed on it. 6%16 Heavy Truck Traffic and Fire Truck Routes/Hangar Aprons/Ramps 6/64t86Light Vehicle Drive Lanes 6/64165 Light Vehicle Parking Stalls Rigid Secfion (inches Concrote / inches A,agreqate Base) Composite Secfion (inches Asphalt / inches Aaareoate Base) Full Depth Asphalt (inches Asphalt) Loeation Job No. 22-6004 GROUND Engineering Consultants, Inc Page 40 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised Pavement concrete should consist of a plant mix composed of a mixture of aggregate, portland cement and appropriate admixtures meeting the requirements of a job-mix formula established by a qualified engineer as well as applicable municipal design requirements design requirements. Concrete should have a minimum modulus of rupture of third point loading of 650 psi. Normally, concrete with a 28-day compressive strength of 4,500 psi should develop this modulus of rupture value. The concrete should be air-entrained with approximately 6 percent air and should have a minimum cement content of 6 sacks per cubic yard. Maximum allowable slump should be 4 inches. These concrete mix design criteria should be coordinated with other project requirements including any criteria for sulfate resistance presented in the Water-Soluble Su/fafes section of this report. To reduce surficial spalling resulting from freeze-thaw cycling, we suggest that pavement concrete meet the requirements of CDOT Class P concrete. ln addition, the use of de-icing salts on concrete pavements during the first winter after construction will increase the likelihood of the development of scaling. Placement of flatwork concrete during cold weather so that it is exposed to freeze-thaw cycling before it is fully cured also increases its vulnerability to scaling. Concrete placing during cold weather conditions should be blanketed or tented to allow full curing. Depending on the weather conditions, this may result in 3 to 4 weeks of curing, and possibly more. Concrete pavements should contain sawed or formed joints. CDOT and various industry groups provide guidelines for proper design and concrete construction and associated jointing. ln areas of repeated turning stresses, such as truck loading and unloading areas, the concrete pavement joints should be fully tied and doweled. Example layouts for joints, as well as ties and dowels, which may be applicable, can be found in CDOT's M standards, found at the CDOT website: http://www.dot.state.co.us/DesiqnSupporU. PCA, ACl, and ACPA publications also provide useful guidance in these regards. Joint spacings less than the 1S-foot maximum indicated in in CDOT's M standards, e.9., 10 feet or 12 feel, may be beneficial to reduce concrete cracking. Subgrade Preparation Although subgrade preparation to a depth of 12 inches is common in the general project area, the local soils are sufficiently collapsible that we do not consider 12 inches to be a sufficient depth of subgrade preparation. Remedial Job No. 22-6004 GROUND Engineering Gonsultants, Inc.Page 41 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised earthwork to any depth will not prevent pavement distress on these soils, but will tend to reduce it and improve perceived rideability. At this site, it's likely that greater than typical maintenance measures, including the removal and replacement of pavements will be required. Remedial Earthwork Pavements and aprons/ramps in close proximity to the building, and for which performance similar to that of the slab-on-grade floor is desired, should be underlain by a section of properly compacted fill as outlined for the slab-on-grade floor in the Geofechnical Considerations for Design section of this report. For pavements and aprons/ramps that are at a greater distance from the building, based on the plasticity of the soils and CDOT guidelines, the pavements should be constructed, in general, on a section of properly moisture-conditioned and compacted to a depth of at least 24 inches or a depth that removes and replaces all undocumented fill soils and all soft, wet, otherwise unsuitable soils, whichever is greater. This section assumes that a)traffic speeds in the parking areas and driveways will be relatively slow, and b) the facility owner will be tolerant of significant total and differential pavement post- construction movements (on the order of several inches) and the associated maintenance costs that that are necessary to re-establish effective drainage, replace distressed pavement, etc. We understand, however, that it may not be practical remove and replace all the undocumented fill soils or soft, yielding, or othenvise deleterious soils as properly compacted fill due the presence of utility lines and the proximity of existing improvements. Therefore, if the owner opts to reduce the fill section beneath the pavements, additional post-construction movements, accelerated pavement distress, and additional maintenance should be anticipated. We suggest remedial earthwork should be performed to no less than 24 inches in such a case. Similarly, where existing utility lines or other site constraints limit the depth to which remedial earthwork can be accomplished, additional maintenance should be anticipated. ln general, increasing the depth of fill beneath the pavements will decrease the risk of post-construction movements. lf performance like the building's floor is desired, then project pavements should be constructed in a similar manner as the buildings' floor. Job No. 22-6004 GROUND Engineering Consultants, lnc.Page 42 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised Subgrade preparation of the selected depth should extend the full width of the pavement from back-of-curb to back-of-curb. The subgrade for any sidewalks and other project hardscaping also should be prepared in the same manner. Geotechnical criteria for fill placement and compaction are provided in the Proiect Earthwork section of this report. The contractor should be prepared to either dry the subgrade materials or moisten them, as needed, prior to compaction. Proof Rollinq lmmediately prior to paving, the subgrade should be proof rolled with a heavily loaded, pneumatic tired vehicle. Areas that show excessive deflection during proof rolling should be excavated and replaced and/or stabilized. Areas allowed to pond prior to paving will require significant re-working prior to proof-rolling. Establishment of a firm pavinq platform (indicated bv oroof rollino) is an additional requirement bevond proper fill placement and compaction. lt is possible for soils to be compacted within the limits indicated in the Project Earthwork section of this report and fail proof rolling, particularly in the upper range of moisture content. Additional Observations The collection and diversion of surface drainage away from paved areas is extremely important to the satisfactory performance of the pavements. The subsurface and surface drainage systems should be carefully designed to ensure removal of the water from paved areas and subgrade soils. Allowing surface waters to pond on pavements will cause premature pavement deterioration. Where topography, site constraints, or other factors limit or preclude adequate surface drainage, pavements should be provided with edge drains to reduce loss of subgrade support. The longterm performance of the pavement also can be improved greatly by proper backfilling and compaction behind curbs, gutters, and sidewalks so that ponding is not permitted and water infiltration is reduced. Landscape irrigation in planters adjacent to pavements and in "island" planters within paved areas should be carefully controlled or differential heave and/or rutting of the nearby pavements will result. Drip irrigation systems are suggested for such planters to reduce over-spray and water infiltration beyond the planters. Enclosing the soil in the planters with plastic liners and providing them with positive drainage also will reduce differential moisture increases in the surrounding subgrade soils. Job No. 22-6004 GROUND Engineering Gonsultants, Inc.Page 43 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised ln our experience, infiltration from planters adjacent to pavements is a principal source of moisture increase beneath those pavements. This wetting of the subgrade soils from infiltrating irrigation commonly leads to loss of subgrade support for the pavement with resultant accelerating distress, loss of pavement life and increased maintenance costs. This is particularly the case in the later stages of project construction after landscaping has been emplaced but heavy construction traffic has not ended. Heavy vehicle traffic over wetted subgrade commonly results in rutting and pushing of flexible pavements, and cracking of rigid pavements. ln relatively flat areas where design drainage gradients necessarily are small, subgrade settlement can obstruct proper drainage and yield increased infiltration, exaggerated distress, etc. (These considerations apply to project flatwork, as well.) Also, GROUND's experience indicates that longitudinal cracking is common in asphalt- pavements generally parallel to the interface between the asphalt and concrete structures such as curbs, gutters, or drain pans. Distress of this type is likely to occur even where the subgrade has been prepared properly and the asphalt has been compacted properly. The anticipated traffic loading does not include excess loading conditions imposed by heavy construction vehicles. Consequently, heavily loaded concrete, lumber, and building material trucks can have a detrimental effect on the pavement. Most pavements will not remain in satisfactory condition and achieve their "design lives" without regular maintenance and rehabilitation procedures performed throughout the life of the pavement. Maintenance and rehabilitation measures preserve, rather than improve, the structural capacity of the pavement structure. Therefore, an effective program of regular maintenance should be developed and implemented to seal cracks, repair distressed areas, and perform thin overlays throughout the lives of the pavements. The greatest benefit of pavement overlaying will be achieved by overlaying sound pavements that exhibit little or no distress. Crack sealing should be performed at least annually and a fog seal/chip seal program should be performed on the pavements every 3 to 4 years. After approximately 8 to 10 years after construction, patching, additional crack sealing, and asphalt overlay may be required. Prior to overlays, it is important that all cracks be sealed with a flexible, Job No. 22-6004 GROUND Engineering Gonsultants, Inc Page 44 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Golorado Revised rubberized crack sealant in order to reduce the potential for propagation of the crack through the overlay. lf actual traffic loadings exceed the values used for development of the pavement sections, however, pavement maintenance measures will be needed on an accelerated schedule. Temporary Fire Access Roufes Commonly, construction sites are required by local fire departments to provide temporary access for emergency response. lt has been GROUND's experience these access drives are to provide support for trucks weighing up to 90,000 pounds and are typically desired to be gravel/aggregate-surfaced. Based on our experience, a temporary section consisting of at least 12 inches of material meeting the requirements of CDOT Class 5 or Class 6 Aggregate Base Course or at least 8 inches of CDOT Class 5 or Class 6 Aggregate Base Course over a layer of stabilization geotextile/geofabric, such as Mirafi@ RS380i or the equivalent, could be utilized provided the owner understands that this section is for temporary access during construction only and is not a replacement or an equal alternate to the pavement section(s) that was indicated previously. The aggregate base course placed for this purpose should be compacted to at least 95 percent of the maximum modified Proctor dry density. lt should be noted that the aggregate base course sections indicated above are not intended to support fire truck outriggers without cribbing or similar measures. The aggregate comprising such a wearing course will be displaced and rutted under the loads imposed by heavy vehicles. Therefore, regular maintenance including re-grading and application of additional aggregate should be implemented to ensure proper drainage, repair distressed/damaged areas, and re-establish grades. Additionally, the ability of a temporary aggregate-surfaced route to accommodate loads as indicated above is directly related to the quality of the subgrade materials on which the aggregate is placed, not only on the aggregate section. lf water infiltrates these areas, additional rutting and other distress, including a reduction in capacity, will result, requiring additional maintenance. EXTERIOR FLATWORK We anticipate that the exterior of the proposed buildings and other portions of the site may be provided with concrete flatwork. Like other site improvements, flatwork will Job No. 22-6004 GROUND Engineering Gonsultants, lnc.Page 45 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised experience post-construction movements as soil moisture contents increase after construction and distress likely will result. The following measures will help to reduce damages to these improvements, but will not prevent all movements. Critical flatwork, which may include flatwork at entrances and exits, should be constructed as a slab-on- grade floor in a similar manner to project floors. Such areas should be identified by the owner. 1)Remedial earthwork to prepare flatwork subgrades is subject to the same factors discussed in the Pavement Secfions section of this report, and should be undertaken to the same depth. Regardless of the depth of subgrade preparation, due to the potentials for hydro- consolidation at this site, greater than typical maintenance, including the removal and replacement of portions of flatwork, should be anticipated for p@ect exterior flatwork. Greater depths of subgrade preparation will tend to reduce the extent and frequency of extra maintenance, however. 2)Prior to placement of flatwork, a proof roll should be performed to identify areas that exhibit instability and deflection. The deleterious soils in these areas should be removed and replaced with properly compacted fill. The contractor should take care to achieve and maintain compaction behind curbs to reduce differential sidewalk settlements. Passing a proof roll is an additional requirement to placing and compacting the subgrade fill soils within the specified ranges of moisture content and relative compaction in the Project Earthwork section of this report. Subgrade stabilization may be cost-effective in this regard. Flatwork should be provided with control joints extending to an effective depth and spaced no more than 10 feet apart, both ways. Narrow flatwork, such as sidewalks, likely will require more closely spaced joints. 4)ln no case should exterior flatwork extend to under any portion of the building where there is less than 2 inches of vertical clearance between the flatwork and any element of the building. Exterior flatwork in contact with brick, rock facades, or any other element of the building can cause damage to the structure if the flatwork experiences movements. 3) Job No. 22-6004 GROUND Engineering Gonsultants, lnc.Page 46 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised Construction and Drainage Between Buildings and Pavements Proper design, drainage, construction and maintenance of the areas between individual buildings and parking/driveway areas are critical to the satisfactory performance of the project. Sidewalks, entranceway slabs and roofs, fountains, raised planters and other highly visible improvements commonly are installed within these zones, and distress in or near these improvements is common. Commonly, proper soil preparation in these areas receives little attention during overlot construction because they fall between the building and pavement areas which typically are built with heavy equipment. Subsequent landscaping and hardscape installation often is performed by multiple sub-contractors with light or hand equipment, and necessary over-excavation and soil processing is not performed. Consequently, subgrade soil conditions commonly deviate significantly from specified ranges. Therefore, the contractor should take particular care with regard to proper subgrade preparation in the immediate building exteriors. Concrete Scaling Climatic conditions in the project area including relatively low humidity, large temperature changes and repeated freeze - thaw cycles, make it likely that project sidewalks and other exterior concrete will experience surficial scaling or spalling. The likelihood of concrete scaling can be increased by poor workmanship during construction, such as 'over-finishing' the surfaces. ln addition, the use of de-icing salts on exterior concrete flatwork, particularly during the first winter after construction, will increase the likelihood of scaling. Even use of de-icing salts on nearby roadways, from where vehicle traffic can transfer them to newly placed concrete, can be sufficient to induce scaling. Typical quality control / quality assurance tests that are performed during construction for concrete strength, air content, etc., do not provide information with regard to the properties and conditions that give rise to scaling. We understand that some municipalities require removal and replacement of concrete that exhibits scaling, even if the material was within specification and placed correctly. The contractor should be aware of the local requirements and be prepared to take measures to reduce the potential for scaling and/or replace concrete that scales. ln GROUND's experience, the measures below can be beneficial for reducing the likelihood of concrete scaling. Which measures, if any, used should be based on cost and the owner's tolerance for risk and maintenance. lt must be understood, however, Job No. 22-6004 GROUND Engineering Consultants, lnc.Page 47 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised that because of the other factors involved, including weather conditions and workmanship, surface damage to concrete can develop, even where all of these measures were followed. Also, the mix design criteria should be coordinated with other project requirements including criteria for sulfate resistance presented in the Water- Soluble Su/fafes section of this report. 1)Maintaining a maximum water/cement ratio of 0.45 by weight for exterior concrete mixes. 2)lnclude Type F fly ash in exterior concrete mixes as 20 percent of the cementitious material. 3)Specify a minimum, 28-day, compressive strength of 4,500 psi for all exterior concrete. 4)lncluding 'fibermesh' in the concrete mix also may be beneficial for reducing surficial scaling. 5)Cure the concrete effectively at uniform temperature and humidity. This commonly will require fogging, blanketing and/or tenting, depending on the weather conditions. As long as 3 to 4 weeks of curing may be required, and possibly more. 6)Avoid placement of concrete during cold weather so that it is not exposed to freeze-thaw cycling before it is fully cured. 7)Avoid the use of de-icing salts on given reaches of flatwork through the first winter after construction. We understand that sometimes it is not practical to implement some of these measures for reducing scaling due to safety considerations, project scheduling, etc. ln such cases, where these measures are not implemented, additional costs for flatwork maintenance or reconstruction should be incorporated into project budgets. Frost and lce Considerations Nearly all soils other than relatively coarse, clean, granular materials are susceptible to loss of density if allowed to become saturated and Job No. 22-6004 GROUND Engineering Gonsultants, lnc.Page 48 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised exposed to freezing temperatures and repeated freeze - thaw cycling. The formation of ice in the underlying soils can result in heaving of pavements, flatwork, and other hardscaping ("ice jacking") in sustained cold weather up to 3 inches or more. This heaving can develop relatively rapidly. A portion of this movement typically is recovered when the soils thaw, but due to loss of soil density, some degree of displacement will remain. This can result even where the subgrade soils were prepared properly. Where hardscape movements are a design concern, e.9., at doonvays, replacement of the subgrade soils with 40 or more inches of clean, coarse sand or gravel should be considered or supporting the element on foundations similar to the building and spanning over a void. Detailed guidance in this regard can be provided upon request. lt should be noted that where such open graded granular soils are placed, water can infiltrate and accumulate in the subsurface relatively easily, which can lead to increased settlement or heave from factors unrelated to ice formation. Therefore, where a section of open graded granular soils is placed, a local underdrain system should be provided to discharge collected water. GROUND will be available to discuss these concerns upon request. CLOSURE Geotechnical Review The author of this report or a GROUND principal should be retained to review project plans and specifications to evaluate whether they comply with the intent of the measures discussed in this report. The review should be requested in writing. The geotechnical conclusions and parameters presented in this report are contingent upon observation and testing of project earthworks by representatives of GROUND. lf another geotechnical consultant is selected to provide materials testing, then that consultant must assume all responsibility for the geotechnical aspects of the project by concurring in writing with the parameters in this report, or by providing alternative parameters. Materials Testing Tectonic Management Group, lnc. should consider retaining a geotechnical engineer to perform materials testing during construction. The performance of such testing or lack thereof, however, in no way alleviates the burden of Job No. 22-6004 GROUND Engineering Consultants, lnc.Page 49 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised the contractor or subcontractor from constructing in a manner that conforms to applicable project documents and industry standards. The contractor or pertinent subcontractor is ultimately responsible for managing the quality of his work; furthermore, testing by the geotechnical engineer does not preclude the contractor from obtaining or providing whatever services that he deems necessary to complete the project in accordance with applicable documents. Limitations This report has been prepared for Tectonic Management Group, lnc. as it pertains to design and construction of the proposed hangar buildings and related improvements as described herein. lt may not contain sufficient information for other parties or other purposes. ln addition, GROUND has assumed that project construction will commence by summer 2023. Any changes in project plans or schedule should be brought to the attention of a geotechnical engineer, in order that the geotechnical conclusions in this report may be re-evaluated and, as necessary, modified. The geotechnical conclusions in this report relied upon subsurface exploration at a limited number of exploration points, as shown in Figure 1, as well as the means and methods described herein. Subsurface conditions were interpolated between and extrapolated beyond these locations. lt is not possible to guarantee the subsurface conditions are as indicated in this report. Actual conditions exposed during construction may differ from those encountered during site exploration. lf during construction, surface, soil, bedrock, or groundwater conditions appear to be at variance with those described herein, a geotechnical engineer should be retained at once, so that reevaluation of the conclusions for this site may be made in a timely manner. ln addition, a contractor who obtains information from this report for development of his scope of work or cost estinrates may find the geotechnical information in this report to be inadequate for his purposes or find the geotechnical conditions described herein to be at variance with his experience in the greater project area. The contractor is responsible for obtaining the additional geotechnical information that is necessary to develop his workscope and cost estimates with sufficient precision. This includes current depths to groundwater, etc. Job No. 22-6004 GROUND Engineering Gonsultants, Inc Page 50 Geotechnical Evaluation Atlantic Aviation - Rifle Hangar Rifle, Colorado Revised ALL DEVELOPMENT CONIAINS INHERENT R/SKS. lt is important that ALL aspects of this report, as well as the estimated performance (and limitations with any such estimations) of proposed improvements are understood by Tectonic Management Group, lnc. Utilizing these criteria and measures herein for planning, design, and/or construction constitutes understanding and acceptance of the conclusions with regard to risk and other information provided herein, associated improvement performance, as well as the limitations inherent within such estimates. lf any information referred to herein is not well understood, then Tectonic Management Group, lnc. or other members of the design team, should contact the author or a GROUND principal immediately. We will be available to meet to discuss the risks and remedial approaches presented in this report, as well as other potential approaches, upon request. GROUND makes no warranties, either expressed or implied, as to the professional data, opinions or conclusions contained herein. This document, together with the concepts and conclusions presented herein, as an instrument of service, is intended only for the specific purpose and client for which it was prepared. Reuse of, or improper reliance on this document without written authorization and adaption by GROUND Engineering Consultants, lnc., shall be without liability to GROUND Engineering Consultants, lnc. GROUND appreciates the opportunity to complete this portion of the project and welcomes the opportunity to provide Tectonic Management Group, lnc. or the owner with a proposal for construction observation and materials testing. Sincerely, GROUND Engineering Gonsultants, lnc. Lil' L.l 4 vfea Ben Fellbaum, P.G., E.l ?la Reviewed by Brian H. Reck, P.G., C.E.G., P.E Job No. 22-6004 GROUND Engineering Consultants, Inc.Page 51 .l ,) I I , I I I I IIItI II I IIt aIIIt.'l II I III IIII aIIItIII''| I,t -" II I atI I t II II I I I I I a I ti * -rE t 't ,]tqw&, j_*._; P-2 .r73 SF Snowmett SidewaJr q'r 4, .r' ys { 'u-* r j. .l ,. a' ;'.n: p.. .1 , l i; {f . *t 1 & l'-{},. r*jiE Lf, tsg*#*-- -ft RFSt.-t - - 4,530 SF I 3 + Hangar 30,000 sF 4 + I '4.* ! 1 I ! t -I F SITE PLAN PROVIDED BY CLIENT !. s LOCATION OF TEST HOLES FIGURE: 1 JOB NO.: 22-6004 ENGINEERING :EROIINII lndicates test hole number and approximate location NOT TO SCALE LOGS OF THE TES.I HOLES PROJECT l,lAME: Atlantic Aviation - Rifle Hanoar PROTECT LOCATION: Rifle. CO ENGINEERING TeclonicGLIENTT JOBNO: 22-6004 Grouo. lnc. 2 3 4 5 P_1 P-2 P_3 P_4100-ELEV. 100-ELEV. 100-ELEV. 100-ELEV. 100-ELEV. .100-ELEV. 100-ELEV. 100-ELEV. 1 m;,,; 100 7-6-7 8-7-14 13-14-14 5-6-8 17t12 28t12 21t12 13t12 20t12 10.12-14 20t12 21t12 9-8-1 1 1 6-1 6-1 9 12-11-12 12t12 14-15-11 35-30-40 50/6 20t12 45t12 45112 20112 8-12-50t3 tro (E o lrJ 7-8-9 8-7-8 7-9-10 67t12 33112 13t12 11t12 6-8-1 1 9-7-11 8-11-12 20112 25t12 16112 29t12 9t12 5012 50t2 50/1 Figure 2 LEGEND AND NOTESEROT'IfD ENGINEERING ?LIENT: Tectonic Management Group, lnc. JOB NO: 22-6004 MATERIAL SYMBOLS TOPSOIL FILL SAND, SILT, and CLAY SANDSTONE BEDROCK NOTE: See Detailed Logs for Material descriptions. V Water Level at Time of Drilling, or as Shown !. Water Level at End of Drilling, or as Shown V Water Level After 24 Hours, or as Shown PROJECT NAME: Atlantic Aviation - Rifle Hanqar PROJECT LOCATION Rifle CO m W W NV NP No Value Non-Plastic wOTES 1. Test holes were drilled onTll9 and7l19l2o22 with 4" solid stem auger 2. Locations of the test holes were determined approximately by pacing from features shown on the site plan provided. 3. Elevations of the test holes were not measured and the logs of the test holes are drawn to depth. Nominal elevation of "100 feet" indicates existing ground level at the test hole at the time of drilling. 4. The test hole locations and elevations should be considered accurate only to the degree implied by the method used. 5. The lines between materials shown on the test hole logs represent the approximate boundaries between material types and the transitions may be gradual. 6. Groundwater level readings shown on the logs were made at the time and under the conditions indicated. Fluctuations in the water level may occur with time. 7. The material descriptions on these logs are for general classification purposes only. See full text of this report for descriptions of the site materials & related information. 8. All test holes were immediately backfilled upon completion of drilling, unless otherwise specified in this report. Modified Galifornia Liner Sampler 23 I 12 Drive sample blow count indicates 23 blows of a 140 pound hammer falling 30 inches were required to drive the sampler 12 inches. Standard Penetration Test Sampler 20-25-30 Drive sample blow count, indicates 20,25, and 30 blows of a 140 pound hammer falling 30 inches were required to drive the sampler 18 inches in three 6 inch increments. SAMPLER SYMBOTS ABBREVIAT'O'VS Figure 3 Praject flo.: 22-6004 ENGINEERING Atlantic Aviation - Rifle Hangar 100 90 80 70 G radati on and Hyd rometer (ASTM D422-63120071) US Standard Sieves Hydrometer 3'2%"2', 1%" 't', %" %', %" 4 810 16 20 30 40 5060 ',100 140 200 10 0.1 0.01 Particle Size (mm) :; ;60a$ ebo t') 'aE+otu o o30 f E5o20 10 0 100 0.001 .\ I i Ii J 1 :- \ \\\:i: ii: tltiirlrtl \ \\\ \\\ L\\*\ Cc61.30.075No. 2001004.75No. 4 Cu0.106No. 1409.53i8 in D05750.150No. 10012.5112 in D100.250No. 6019.0314 in D15870.300No.5025.01in D30170.001920.425No. 4037.51.5 in D40230.0030.60No.30502in D50310.0060.85No.20632.5 in D60340.0099B1.18No. 16753in o_202D8037o.0122.00No. 101004in 0.267D85440.0202.36No.81255in 0.368D90460.0321004.75No. 41506in ValueCoefficientPassing by Mass (%) Particle Size (mm) Passing by Mass (%) Particle Size (mm) US Standard Sieve Passing by Mass (%) Particle Size (mm) US Standard Sieve GradingHvdrometerFine GradationCoarse Gradation Localion: TH-2 at 9 feet Descriptian: FILL: Sandy, Silty Clay Classificatian: S(CL-ML) i A-4 (0) Liquid Limit: 20 Plasticity lnclex: 5 Actlvity: 0.3 Gravel {%}: 0 Sand {%): 39 Silt/Ctay {%): 61 < .002 rnnt {%): 2O to each reading. This report should not be reproduced, except in full, without the written permission of GROUND Engineering Consultants, lnc. www.groundeng.com Englewood, Commerce City, Loveland, Granby, Gypsum, Colorado Springs 4Figure IiRlIUIfI Praject No.: 22-6004 ENGINEERING Atlantic Aviation - Rifle Hangar 3',2%" 2" 't%" 1" %" % %" G radati on and Hyd rometer (ASTM D422-63120071) US Standard Sieves 4 8 10 16 20 30 40 5060 100 140 200 100 90 80 70 Hydrometer 0.01 s;60a G e50 o) .cafrqo(L E30f E =o20 10 0 100 10 0.1 0.001 Particle Size (mm) li' \. li, \\ li \ li. \ \:i :r li. \\t;: it: :i: li : \:r: ili. li \\ li. Cc77.80.075No. 200964.75No.4 Cu0.1 06No. 140979.53/B in D05860.150No.1009812.5112 in Dl00.250No.6099'19.0314 in D15900.300No. 509925.01in D30170.001910.425No.4037.51.5 in D40240.0030.60No. 30502in D50300.0060.85No. 20632.5 in D60320.009951.18No.'16753in 0.090D8035o.o122.OONo. 101004in 0.137D854',l0.0202-36No. 81255in 0.294D90460.032964.75No. 41506in ValueGoeflicientPassing by Mass (%) Particle Size (mm) Passing by Mass (%) Particle Size (mm) US Standard Sieve Passing by Mass (%) Particle Size (mm) US Standard Sieve GradinqHydrometerFine GradationCoarse Gradation Lacation: Composite at 0-5 feet Description: CLAY with Sand Cfassi#caflon: (CL)s / A-4 (5) Liquicl Linit: 24 Plasticity lndex: 9 Activity: O.4 www.groundeng.com Englewood, Commerce City, Loveland, Granby, Gypsum, Colorado Springs Gravel (%): 4 Sand (%): 18 Silt/Clay {%): 78 <.002 mm {%}: 2O to each reading. This report should not be reproduced, except in full, without the written permission of GROUND Engineering Consultants, lnc. f igune 5 ERIlrTfN ENGINEERING Praject No.: 22-6004 Atlantic Aviation - Rifle Hangar 4 3.5 3 ^2.5a d, COUE2o o 8 r.s L '6o o '6p. s0 coFo oCoo 100 0 California Bearing Ratio (ASTM D1883) 0:5 / / -/ /-/ ,/ ro2 ro4 106 108 110 1t2 rl4 Molded Dry Density (pcf) 2102.090 3ro7.695 4113.3100 cBR (%)Dry Density (pcf) Relative Comp. (%l Corrected CBR at 0.1 in from Graph 0.0 0.1 o.2 0.3 0.4 0.5 0.6 Pr7ttor Methad: Max. {}ry Density {pcf}: Apt. Maisttrrc Cantent {%): D698 113.3 14.8 Penetration Depth (in) 1 / ) /,l/ 3.13.5-0.11018.5ro7.3L7.OII2.499.23A 2.62.70.11018.8106.317.0108.39s.62o 1.9r.70.01019.1104.517.o103.090.910 0.2 in0.1 in Swell (%lSurcharge (lb)Moisture Content (%) Dry Density (pc0 Moisture content (%) Dry Density (pc0 Relative comp. (%) Specimen Corrected CBR (%lSoaked PropertiesMolded Properties Sanple: Composite classification: (cl)s / A-a(5) < 3/4 in {2/o): 99 Description: CLAY with Sand Liquid Limit: 24 < Na. 4 {%): 95 Plasticity lndex: 9 < lJa. 2AA (%): 77.8 Test Remarks: Ranat+2o/o above Optimum Moisture Content the written permission of GROUND Engineering Consultants, lnc. www. g ro u n d e ng. co m Englewood, Commerce City, Loveland, Granby, Gypsum Figure 6 INSTALL WALL DRAIN BOARD, WHERE APPROPRIATE FREE - DRAINING GRAVEL PRODUCED FROM NATURALLY OCCURING MATERIALS (NOT RECYCLED) FILTER FABRIC COLLECTION PIPE WITH PERFORATIONS AT 4 O'CLOCK AND B O'CLOCK POSITIONS 6" MIN NOTES: 1. This is NOT a design - level drawing. it should be used solely for general information purposes only. Actual Underdrain design should be completed by others. 2. The underdrain system must be tested by the contractor after installation and backfilling to verify that it functions properly. 3. lnclusion of this figure in construction documents is done so at the document preparer's risk. 4. Reproduction of this document should be in color. 12" MIN APPLY DAMP PROOFING, WHERE APPROPRIATE PROVIDE SHEETING OR MEMBRANE GLUED TO FOUNDATION WALL TO REDUCE MOISTURE PENETRATION 12'' MINIMUM STAYING OUTSIDE PLANE DESCENDING FROM FOOTING EDGE AT 45" NOT TO SCLE SEE TEXT FOR ADDITIONAL INFORMATION TYPICAL UNDERDRAIN DETAIL FIGURE: 7ENGINEERING ROUNIIiE JOB NO.: 22-6004 ENG II{ EERIhIG Atlantic Aviation - Rifle Hangar TABLE 1: SUMMARY OF LABORATORY TEST RESULTS SD = Samp/e disfurbed, NV = No value, NP = Non-plastic, *indicates optimum moisture content and maximum standard Proctor density (ASTM D698)Job No.22-6004 Composite P-4 P-2 P-1 TH-5 TH-4 TH-4 TH.4 TH-3 rH-2 rH-2 rH-2 rH-2 TH-1 Test Hole No. 0-5 2 3 A 16 24 I 4 13 44 14 I 4 7 Oepth (feet) 14.8- 6.7 6.9 10.6 7.7 11.1 12.6 6.6 5.8 J.b 9.9 7.4 6.2 4.8 Natural Moisture Content (%) 1 13.3. SD 1 10.0 107.5 120.8 115.1 116.1 98.2 107.6 SD 120.9 SD 104.3 1 10.0 Natural Dry Density (pcfl i 7 0 0 25 0 1 0 I 0 0 0 I 4 Gravel (%) Gradation 18 37 58 58 51 31 48 51 .4 35 41 50.5 50 30 39 30 39 57.5 Sand (%) Fines (%) 77.8 55.7 41.8 41.9 24.2 69.5 65.0 50.3 70.1 61.3 69.4 24 30 23 26 NV 20 4 26 23 23 18 24 20 24 21 Liquid Limit Plasticity lndex Atterberg Limits I 10 5 8 NP 10 I 8 6 11 5 I 8 3% CBR 0.1 -0.6 -0.2 -3.3 0.4 o.2 -1.6 Volume Change (%) Swell/Consolidation 500 3,000 1 .100 1.600 't.750 500 900 Surcharge Pressure (ps0 (CL)s s(CL) SC-SM SC (SM)o s(CL-ML) s(CL) s(CL) s(CL) s(CL-ML) (CL)s s(CL-ML) s(CL) s(CL) uscs Equivalent Classification A-4 (5) A-4 (3) A-4 (0) A-4 (0) A-2-4 (0\ A-4 (0) A-4 (2) A-4 (3) A-4 (1) A-4 (0) 4-6 (5) A-4 (0) A-4 A\ A-4 (21 AASHTO Equivalent 'Classification (Group lndex) CLAY with Sand FILL: Sandy Clav FILL: Siltv. Clavev Sand FILL: Clavev Sand FILL: Siltv Sand with Gravel Sandv. Siltv CLAY FILL: Sandv Clav FILL: Sandv Clav FILL: Sandv Clav CLAYSTONE Bedrock FILL: Clay with Sand FILL: Sandy, SilW Clay FILL: Sandv Clav FILL: Sandy Clay Sample Description ENGINETRING Atlantic Aviation - Rifle Hangar TABLE 2: SUMMARY OF SOIL CORROSION TEST RESULTS Job No.22-6004 P-2 4 Test Hole No. Sample Location 3 4 Depth (feet) 0.03 0.01 Water Soluble Sulfates (w 8.8 8.2 pH 95 59 Redox Potential (mv) Trace Positive Sulfide Reactivlty 7.400 Reslstivity (ohm-cm) SC-SM s(CL) uscs Equivalent Classification A-4 (0) A-4 (3) AASHTO Equivalent Classificatlon (Group lndex) FILL: Siltv. Clavev Sand FILL: Sandv Clav Sample Description Appendix A Detailed Logs of the Iesf Holes EROT'IfD TEST HOLE 1 PAGE 1 OF 1 ENGINEERING CLIENT: Tectonic Manaqement Group, lnc.PROJECT NAME: Atlantic Aviation - Rifle Hanqar JOBNO: 22-6004 PROJECT LOCATION: Rifle, CO 6-8-1 1 X 67112SANDS, SILTS, and CI-AYS: Clean to silty or clayey, fine to coarse sands, silts, and clays with local gravels and cobbles. They were dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. lron staining was encountered commonly. Caliche was encountered locally. 20112X X 40 35-30- 10 X 1 10.04.821t12 s(CL)-1.6 (e00)B2158 X 13-14- 14 FILL: Silts, clays, fine to coarse sands, and local gravels. Gravel sized clasts of sandstone, siltstone, and claystone bedrock were encountered locally. They were slightly dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. TOPSOIL 'ix.;-s o9(g! d E E: '5 : o)cq) 9,.do(,(Lo EO6Ngc; &z EA =a+c)1O }Eog E:G.o9\o_>66F\6€oz c foo =oo o)o- F o) E- Eoa Material Descriptions and Drilling Notes o)oJ .o (E o o e c c)o 100 e co G q) uJ c (, oi6al6 (J 4 =E)*a LI.o(_) _o o.? c EAbc 5 K6.9O-E-cqa coo) EBE 89e 6@ -^()-^o>\vogE' a Atterberg Limits Bottom of borehole at Approx. 28.5 feet. EROUIfD TEST HOLE 2 PAGE 1 OF 2 ENGINEERING CLIENT: Tectonic Manaqement Group, lnc. PROJECT NAME:Atlantic Aviation - Rifle Hanqar JOB NO: 22-6004 PROJECT LOCATION:Rifle. CO X 8-1 1- 1230 13112Xffi*: SANDS, SILTS, and CI-AYS: Clean to silty or clayey, fine to coarse sands, silts, and clays with local gravels and cobbles. They were dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. lron staining was encountered commonly. Caliche was encountered locally. X 7-A-92080 X (CL)s0.4 (1750)112470120.99.920t12 X 52061SD7.412-11- 12 s(CL-ML) X 21112 s(CL)0.2 (500)I2469104.36.2 FILL: Silts, clays, fine to coarse sands, and local gravels. Gravel sized clasts of sandstone, siltstone, and claystone bedrock were encountered locally. They were slightly dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. TOPSOIL 595 'ixEP69o!d E E =p f.sJ100 e Co G o ul o EG.o9\o.-z6 TE =o€oz c5oo 3 -9co oo- F o o- E (Ea Material Descriptions and Drilling Notes o)oJ .oEo-g(t o -ci1Sogo c =oo o'i6ar 6 O4=E) -*aul! C) oraC69s. U) o9(D= tsd) odPE oo gEE 89e 6a -6 Q6 E Egta Atterberg Limits ct)co'@: o.yG('o-o =obN 9ci &z }Eoe' EA =6LY 0)4o (Continued Next Page) EROITIfI TEST HOLE 2 PAGE 2 OF 2 ENGINEERING CLIENT: Tectonic Manaqement Group, lnc.PROJEGT NAMEI Atlantic Aviation - Rifle Hanoar JOB NO: 22-6004 PROJECT LOCATION: Rifle. CO 50t2 3.650t2 s(CL-ML)61850SD SANDSTONE BEDROGK: Fine to medium grained sandstones with interbedded locally with claystones and siltstones. They were slightly moist, non- to moderately plastic, hard to very hard, and brown in color. 29112X SANDS, SILTS, and GI-AYS: Clean to silty or clayey, fine to coarse sands, silts, and clays with local gravels and cobbles. They were dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. lron staining was encountered commonly. Caliche was encountered locally. (continued) 4060 '^- x #€(s!d =E:p :fu =35 e .c o-oo 65 s c .o G o ul E x- = [BeOFE-c =u) oo'.i: o)6gEe 89e 6@ -^()*^a>\v(Dgsi U) Atterberg Limitsco nd(E('o-; bN9ci &z bEog Ei. =aE54o E;G.@o\o->6 6F\6froz C oO; -9m o F _g E (E ct) Material Descriptions and Drilling Notes o) 3 .o -c (! o c =ooorE I g# J=6fi-sO Bottom of borehole at Approx. 49.17 feet. EROTfIfD TEST HOLE 3 PAGE 1 OF 1 ENGINEERING CLIENT: Tectonic Manaqement Group, lnc.PROJECT NAME:Atlantic Aviation - Rifle Hanqar JOB NO: 22-6004 PROJECT LOCATION:Rifle. CO Bottom of borehole at Approx. 34 feet. 25t12 X 9-7-11 X 33t12SANDS, SILTS, and CI-AYS: Clean to silty or clayey, fine to coarse sands, silts, and clays with local gravels and cobbles. They were dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. lron staining was encountered commonly. Caliche was encountered locally. 25 1 8-12- 50/3 82351107.65.850/6><s(CLl-3.3 (1600) 1 6-1 6- 19 90 17112X FILL: Silts, clays, fine to coarse sands, and local gravels. Gravel sized clasts of sandstone, siltstone, and claystone bedrock were encountered locally. They were slightly dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. TOPSOIL I E Jp fft = 'ix.:oo9(r! o- oo- F o o_ E (Ea Material Descriptions and Drilling Notes oJ .9 (u o 0 e .c o- a)o 100 e Co o -gul EO o o:E at 6 o 4 =E) -*6fioo ..'9 O'; c = [Bs s 5s) coo EPE EE; 6@dq6 Eg8' U) Atterberg Limits o)co n6(t (/)(Lo bNgci &z i6og EAe2 -:Y c.)z6 E .? G..o\o- =.E \6 €c)z =o;o6 -^. ERtrI'IfD TEST HOLE 4 PAGE 1 OF 2 ENGINEERING ?LIENT: Tectonic Management Group, lnc. JOB NO: 22-6004 PROJECT NAME: Atlantic Aviation - Rifle Hansar PROJECT LOGATION: Rifle, CO 16t12X35 20t12X3070 s(CL-ML)-0.6 (3000)42070115.111.111112X X 8-7-8 SANDS, SILTS, and CLAYS: Clean to silty or clayey, fine to coarse sands, silts, and clays with local gravels and cobbles. They were dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. lron staining was encountered commonly. Caliche was encountered locally. X 45t1215 102651116.112.612t12X s(cL)-0.2 (1 100)10s0 X 13112 s(CL)I236598.26.6 FILL: Silts, clays, fine to coarse sands, and local gravels. Gravel sized clasts of sandstone, siltstone, and claystone bedrock were encountered locally. They were slightly dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. TOPSOIL 595 'ix.ts o)a9(5: (L =E: '3u: }Eog EA =a-:y 0)4o E .= G..@Lo->sE# €oz Joo =o6 (!) o- F c) o- E G U) Material Descriptions and Drilling Notes o)oJ .o o. (E o 0 c*ae o 1n0 e c .o (E _gul c=o(,oftar 6 O E =EJ*a uliO o)6C6Es q) o99'f--=aEEOoPE<o coo EgE 39e 6a'^OE o>\uc)ggd CD Atterberg Limits o)co ndo(t(Lo,obN9o &z (Continued Next Page) EROI'IfD TEST HOLE 4 PAGE 2 OF 2 ENGINEERING CLIENT: Tectonic Manaqement Group, Inc. PROJECT NAME:Ailantic Aviation - Rifle Hanoar JOBNO: 22-6004 PROJECT LOGATION: Rifle, CO Bottom of borehole at Approx. 44.08 feet. SANDSTONE BEDROCK: Fine to medium grained sandstones with interbedded locally with claystones and siltstones. They were slightly moist, non- to moderately plastic, hard to very hard, and brown in color. X 9t12 SANDS, SILTS, and CLAYS: Clean to silty or clayey, fine to coarse sands, silts, and clays with local gravels and cobbles. They were dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. lron staining was encountered commonly. Caliche was encountered locally. (contin ued) 4060 'ix.YO (E! d =E =p l.gJ ct)co 9,.6II CJ)(Lo bN9o &z }Eog EA =6E51A E .= G-.o5o->5 6F froz c =o;od oo- F o o- Eo U) Material Descriptions and Drilling Notes o)oJ ,o -co.(! C' 35 e c o- o)o 65 e c .9 G o IJJ c!oobE 8:'H)*6 fiso o99'as E gflp O-E-CFA coo) EEE99or 6ad96 E egda Limits Atterberg EROUIfI TEST HOLE 5 PAGE 1 OF 1 ENGINEFRING CLIENT: Tectonic Manaqement Group, lnc.PROJECT NAME:Atlantic Aviation - Rifle Hanoar JOBNO: 22-6004 PROJECT LOCATION Rifle. CO , .7-9-10 SANDS, SILTS, and CLAYS: Clean to silty or clayey, fine to coarse sands, silts, and clays with local gravels and cobbles. They were dry to moist, non- to moderaiely plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. lron staining was encountered commonly. Caliche was encountered locally. X NPNV24120.87.745112 (sM)s )1 14-15- 11 X 20112 5 7-6-7FILL: Silts, clays, fine to coarse sands, and local gravels. Gravel sized clasts of sandstone, siltstone, and claystone bedrock were encountered locally. They were slightly dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. TOPSOIL '-x.Y d)69o:d E E:p f: o)oJ .9 -co (E (, 0 !-ae o 100 e C .9 o -guJ o)co) ndo(,(Lo bNgc; &z bEog E,a =a -:Y q)zo E;G'.c5o- frF\6froz CfoO 3od oo- F o Eo U) Material Descriptions and Drilling Notes C cn arE() 6 o4=5) -dAfi-sO E O'CC6Es.a o99'6,=atso)ooO- -eio co0)€ 9E'p-Eg 89s 6a -- 96 E g 8o-a Atterberg Limits 85 Bottom of borehole at Approx. 22.5feel. EROUIfIT TEST HOLE P.l PAGE 1 OF 1 ENGINEERING GLIENT: Tectonic Manasement Group, lnc. PROJECT NAME: JOBNO: 22-6004 PROJECT LOCATION Rifle. CO Bottom of borehole at Approx. 5 feet. Atlantic Aviation - Rifle Hanqar 42107.510.620112X SC0.1 (500)826 l\FILL: Silts, clays, fine to coarse sands, and local gravels. Gravel sized clasts of sandstone, siltstone, and claystone bedrock were encountered locally. They were slightly dry to moist, non- 1o moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown io gray brown in color. B-7-14 TOPSOIL 595 :Et a9o: (L ,e E Jp =f10n e .9 o -gtu Atterberg Limits o,co) ndo(,(Lo bN9ct &z }Eog EB eE E EG..o Q)o- =.E \6froz c oO =_9d) oo- F -go. E (Ea Material Descriptions and Drilling Notes o)o -J =o- E(, o FEo C (/)oEo $.9a.=EJ -*afi-g C) -co)GC6E*' U) o99'a.=a =dibb-PEio cEe89e €? fi Hs- EREUIfI TEST HOLE P.2 PAGE 1 OF 1 ENGINEERING CLIENT: Tectonic Manaqement Group, lnc. PROJECT NAME: JOB NO: 22-6004 PROJECT LOCATION:Rifle. CO Bottom of borehole at Approx. 8.5 feet. Atlanfic Aviation - Rifle Hanoar ?' 2(9-8-1 1 X SC-SM523421 10.06.928112 FILL: Silts, clays, fine to coarse sands, and local gravels. Gravel sized clasts of sandstone, siltstone, and claystone bedrock were encountered locally. They were slightly dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to brown to gray brown in color. TOPSOIL 'ix.Eoo9cr5d E E Jp ilo FEo 100 e co o _g Llt o)co nd6A(Lo 6N9ct &z }Eog EA =aE5zo E EG..o5o->56F\6€oz Jo c) 3o6 q) o- F o o- Eoa Material Descriptions and Drilling Notes o)oJ .o o"(o o cts.o(, oEa) 6 () 6.>_E) =-afi(u() !o)cCqES CD o9 9'a,.=6EO OoO--eio Coo EPD EE; 6@'^96 E 98. U) Atterberg Limits EROI'IfD TEST HOLE P.3 PAGE 1 OF 1 PROJECT NAME: Atlantic Aviation - Rifle Hansar ENGINEERING Tectonic Manaoement Group, lnc.GLIENT: JOB NO:22-6004 PROJECT LOCATION:Rifle. CO Bottom of borehole at Approx. 3 feel. X 24t12 FILL: Silts, clays, fine to coarse sands, and local gravels. Gravel sized clasts of sandstone, siltstone, and claystone bedrock were encountered locally. They were slightly dry to moist, non- to moderately plastic, medium dense to very dense or sliff to hard, and pale brown to brown to gray brown in color. TOPSOIL E;69.o!d =E =p fu = c JoO 3o m o F c) o- Eo @ Material Descriptions and Drilling Notes o) J =o(! (, o -c-ae o 100 e co (! _9 ]U =ocnorEo $.9 31=nfioo -c O'FC6Es. CN o99'6-=aEo)OoPEqo ooEps*de 89e 6ad96 Egst U) Atterberg Limits o)co Ed6 (/)(Lo P-O 6 c.l 9ci &z }EoS EA =66>- z6 o :G..oco->5 \6E /\ z ERtrT'IfD TEST HOLE P-4 PAGE 1 OF 1 ENGINEERING SLIENT:Tectonic Manaqement Group. lnc.PROJEGT NAME:Atlantic Aviation - Rifle Hanqar JOBNO: 22-6004 PROJECT LOGATION:Rifle. CO X 10-12- 14 X 6.75-6-8 s(CL)103056SD FILL: Silts, clays, fine to coarse sands, and local gravels. Gravel sized clasts of sandstone, siltstone, and claystone bedrock were encountered locally. They were slightly dry to moist, non- to moderately plastic, medium dense to very dense or stiff to hard, and pale brown to.brown to gray brown in color. TOPSOIL 595 ! E ='3 il :a66pcr! o- 10n e co (! 0) ul cfoO;o6 oo" F oE E(E U) Material Descriptions and Drilling Notes o)oJ .oEo-(\t (t o €= c)o o99'aEE 9? c',a 5 HF.9 3 E6 - coo EPE 39e 6@d96 Egst U) Atterberg Limits o)co) Ed(\t (,(Lo 6N9ct &z }Bog EA3a ly 0)z6 E .= G..o5o-sts-o)EF =6ftoz c =O(,o6 8q#J --afi-sO Bottom of borehole at Approx. 6.5 feet.