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Home My WebLink About10_Lmbryd Geotechnical Report GEOTECHNICAL REPORT FOR: Lumber Yard Apartments Bozeman, Montana April 2022 Project 22-015 Allied Engineering Services, Inc. Page 1 TABLE OF CONTENTS INTRODUCTION ............................................................................................................................................. 4 DESCRIPTION OF PROPERTY ......................................................................................................................... 4 SCOPE OF WORK ........................................................................................................................................... 5 EXECUTIVE SUMMARY .................................................................................................................................. 5 GEOLOGY ....................................................................................................................................................... 6 EXPLORATIONS, TESTING, AND SUBSURFACE CONDITIONS ......................................................................... 6 Subsurface Explorations ........................................................................................................................... 6 Soil Conditions .......................................................................................................................................... 7 Groundwater Conditions .......................................................................................................................... 8 Laboratory Testing .................................................................................................................................... 8 GENERAL CONSTRUCTION RECOMMENDATIONS ........................................................................................ 8 Sediment Control ...................................................................................................................................... 8 Topsoil Stripping and Re-Use .................................................................................................................... 8 Moisture Sensitivity of Fine-Grained Soils ................................................................................................ 9 Excavation and Re-Use of On-Site Soils .................................................................................................... 9 Groundwater Dewatering ......................................................................................................................... 9 FOUNDATION, SLAB, AND DRAINAGE RECOMMENDATIONS ....................................................................... 9 Seismic Design Factors.............................................................................................................................. 9 Building Foundation Design .................................................................................................................... 10 Slab and Footing Elevations .................................................................................................................... 10 Foundation Support Under Buildings – Option 1: Over-Excavation and Replacement .......................... 10 Foundation Support Under Buildings – Option 2: Helical Piers .............................................................. 12 Interior Concrete Slabs Under Buildings................................................................................................. 13 Lateral Earth Pressures ........................................................................................................................... 14 Foundation Wall Backfill ......................................................................................................................... 14 Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 2 Surface Water Drainage ......................................................................................................................... 15 Subsurface Drainage and Damp-Proofing .............................................................................................. 15 Vapor Barrier .......................................................................................................................................... 15 Exterior Concrete Slabs – Sidewalks ....................................................................................................... 15 Exterior Concrete Slabs and Garage Slabs .............................................................................................. 16 FOUNDATION-RELATED FILL MATERIAL RECOMMENDATIONS .................................................................. 16 Excavated Foundation Soils .................................................................................................................... 16 Sandy (Pitrun) Gravel .............................................................................................................................. 17 Crushed (Road Mix) Gravel ..................................................................................................................... 17 Clean Crushed Rock ................................................................................................................................ 17 Fill Placement and Compaction .............................................................................................................. 17 Granular Structural Fill Under Footings and Interior Slabs: ............................................................... 18 Embankment Fill Under Interior and Exterior Slabs:.......................................................................... 18 Backfill Behind Foundation and Retaining Walls: .............................................................................. 18 UNDERGROUND UTILITY RECOMMENDATIONS ......................................................................................... 18 ASPHALT PAVEMENT RECOMMENDATIONS ............................................................................................... 19 Pavement Section Design ....................................................................................................................... 19 Pavement Section Materials, Placement, and Compaction ................................................................... 21 COLD/WINTER WEATHER CONSTRUCTION ................................................................................................. 21 FUTURE AESI INVOLVEMENT ...................................................................................................................... 22 LIMITATIONS ............................................................................................................................................... 22 REFERENCES ................................................................................................................................................ 23 Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 3 SUPPLEMENTAL INFORMATION • List of Tables o Table 1. Compaction Recommendations (Application vs. Percent Compaction) o Table 2. Pavement Section Design – Parking Lots (Stable Subgrade) o Table 3. Pavement Section Design – Parking Lots (Unstable Subgrade) o Table 4. Pavement Section Design – Local Roads (Stable Subgrade) o Table 5. Pavement Section Design – Local Roads (Unstable Subgrade) • List of Figures o Figure 1 – Vicinity Map o Figure 2 – Quadrangle Map o Figure 3 – Test Pit Location Map o Figure 4 – Geology Map o Figure 5 – Groundwater Map • List of Appendices o Appendix A – Test Pit Logs and Borehole Logs o Appendix B – Laboratory Testing Results o Appendix C – Pavement Section Design o Appendix D – Limitations of Your Geotechnical Report Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 4 INTRODUCTION This report presents our geotechnical assessment for the proposed Lumber Yard Apartments located just north of Kenyon Noble in Bozeman, Montana. Presented herein is a description of the site’s soil and groundwater conditions and our geotechnical analysis and recommendations for foundation support and drainage. We are assuming standard construction practices in this report and suggest AESI remain involved in both the design and construction of structures on this property to assure the work is completed consistent with our recommendations. The geotechnical information contained herein is based on an investigation and analysis of the subsurface conditions, laboratory testing of select soil samples, a review of geologic maps for the general area, and previous experience on similar projects in Bozeman. The purpose of this report is to inform all associated parties of the site’s soil and groundwater conditions and its critical geotechnical issues; and to provide important recommendations that pertain to general earthwork, foundations, slabs, walls, fill materials, underground utilities, asphalt pavement sections, and surface and subsurface drainage. Note that this work was completed as a continuation of earlier work completed by this firm on a much larger parcel, which this property was once part of. DESCRIPTION OF PROPERTY The Lumber Yard Apartments property is comprised of Lots 1, 2, and 3A of Block 3 per Plat J- 498. Lot 1 is approximately 1.64 acres, Lot 2 is approximately 1.19 acres, and Lot 3A is approximately 9.06 acres. The combined 11.89-acre property is bound by Patrick Street to the south, the extension of North 15th Avenue to the west, North 11th Avenue to the east, and an undeveloped field to the north. Please see Figures 1 and 2 for illustrations showing the site location and property lines. The legal description for the site is Lots 1, 2, and 3A of Block 3, PT Land Phase 2 Subdivision per Plat J-498, located in a portion of the Northwest One-Quarter of Section 1, Township 2 South, Range 5 East, Principal Meridian Montana, Gallatin County, Montana. We understand the proposed development includes six apartment buildings up to four stories tall, six carriage buildings, a clubhouse/leasing building, and one commercial building in the northwest corner of the site. The proposed development will also include associated parking facilities, the extension of local streets, and the installation of utilities (i.e., water, sewer, storm sewer, and dry utilities). No plans (beyond the site plan) have been provided to-date, but we anticipate the buildings will consist of concrete slab-on-grades with associated frost walls/footings and spread footings. Given the elevated groundwater levels found across much of the site, slab-on-grade buildings will be the most appropriate option for the development. Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 5 SCOPE OF WORK The scope of services for this project included: • Review of available geologic maps and previous AESI geotechnical report from 2016. • Excavation of four (4) additional test pits across the property and installation of monitor wells in each test pit. • Laboratory testing of select samples from the test pits. • Providing allowable bearing capacity criteria. • Providing lateral earth pressures. • Surface and subsurface drainage recommendations. • Backfill material and compaction recommendations. • Asphalt pavement section materials and design thickness. EXECUTIVE SUMMARY Subsurface conditions were found to be relatively consistent between the March 2022 subsurface explorations and the November 2016 explorations. The 2022 explorations included four (4) shallow test pits dug with an excavator and the installation of four (4) monitor wells for future monitoring of water levels. The 2016 explorations consisted of five (5) shallow test pits and four (4) boreholes extended to depths of up to 30 feet. The general soil profile consisted of 4.0 to 8.0 feet of very soft, very moist to wet, fine-grain silt/clay overlying medium dense to very dense alluvial gravels. During our March 2022 explorations, groundwater was measured at depths ranging from 5.0 to 7.5 feet below existing ground. Weekly groundwater monitoring has shown that groundwater levels have come up since the time of the explorations. At the time of this report (April 19, 2022), the shallowest groundwater level recorded is 2.25 feet below the ground surface in MW-3. Please refer to Figure 3 for the approximate test pit and monitor well locations. AESI will continue monitoring on a weekly basis through peak groundwater season. During the November 2016 explorations, groundwater levels ranged from 2.8 to 8.0 feet deep. Given the shallow depth to groundwater in many areas of the site, we expect the elevation of many of the proposed buildings will be raised. Raising the finished floor elevation will help promote positive drainage away from each building. Given the depth to “target” bearing in the native gravels and the anticipated elevation of the main floors, granular structural fill will most likely be required to bring the subgrade up from the “target” bearing layer (gravel) to the footing/slab grades. Depending on the target bearing depth relative to footing elevation, the required thickness of structural fill could range from approximately 3.0 to 7.0 feet depending on location. Dewatering will likely be required to install the structural fill. Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 6 Since much of the overlying fine-grain soils are wet and soft, one option is to remove all fine- grain native material (clay and silt) within the building footprints down to the target bearing soils (sand and gravel) and replaced with structural fill. The second option is to chase out the fine-grains soils down to gravel under footings only and leave the fine-grain soil in place under interior slabs. A significant gravel section with geotextile reinforcement would be required to support the interior slabs if the fine-grain soil is left in place. Given the depth to target bearing, a final option to provide foundation support is the installation of helical piers at regular spacings under the buildings which would eliminate the need for structural fill. We anticipate the helical piers would be installed at 10-foot spacings and the footings would be designed as grade beams to span the helical piers. The slabs could also be supported on helical piers to eliminate the need to remove the soft, fine-grain silt and clay or sufficient gravel with geotextile reinforcement as described later. We briefly considered the use of rammed aggregate piers (RAPs) but based on previous experience would be concerned that the integrity of the RAPs could be compromised if installed in groundwater and soft fine-grained soils. The design team could also consider using a combination of these methods across the property depending on the depth to the gravel and/or the depth to high groundwater. GEOLOGY According to the preliminary geologic map prepared by Lonn and English in 2002 for the eastern part of the Gallatin Valley (Figure 4), the project site is underlain by Quaternary-aged alluvium of braid plains deposits (Qabo). Based on previous geotechnical experience, the soil stratigraphy in this general area of Bozeman usually consists of topsoil overlying a mantling of silt, clay, and/or sand, which in turn overlies alluvial sands and gravels. Consolidated beds of Tertiary-aged gravels, sands, silts, and clays underlie the Quaternary gravel deposits throughout the Bozeman area. Our test pit and borehole findings were consistent with the described soil conditions. EXPLORATIONS, TESTING, AND SUBSURFACE CONDITIONS Subsurface Explorations Subsurface conditions were investigated at the project site on March 10, 2022, under the direction of Erik Schnaderbeck, a professional geotechnical engineer with Allied Engineering. A total of four (4) additional test pits were dug in the areas of the proposed improvements. Five (5) test pits and four (4) boreholes were completed across the property during our original subsurface explorations in November of 2016. The 2022 test pits (identified as TP-1 through TP- 4) were completed using a Hitachi 130 excavator provided by RLS Construction of Manhattan, Montana. The test pits were located at various strategic locations across the property to provide an idea of soil variability within the development. Test pits ranged from 9.0 to 9.5 Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 7 feet deep. See Figure 3 for an exhibit showing the approximate test pit locations from 2022, as well as applicable test pit and borehole locations from 2016. During the explorations, soil and groundwater conditions were visually characterized, measured, and logged. The relative densities of the exposed soil profiles were estimated based on the ease or difficulty of digging and the overall stability of the completed excavations. Copies of our test pit and borehole logs are attached in Appendix A. Each of the logs provide assorted field information, such as soil depths and descriptions, groundwater conditions, relative density data, sample information, and a diagram of the soil stratigraphy. Please be aware that the detail provided on the logs cannot be accurately summarized in a paragraph; therefore, it is important to review the logs in conjunction with this report. Following the completion of the fieldwork, the test pit locations were backfilled with native soils and cleaned up to the extent possible. Each location was staked with a wooden lathe that identified it accordingly. If any test pits underlie future site improvements, they should be completely re-excavated and backfilled in properly compacted lifts to avoid undesirable settlements. Soil Conditions Similar soil conditions were encountered in all four test pits. In general, subsurface conditions consisted of 1.25 to 2.5 feet of topsoil overlying very soft, very moist to wet, fine-grain sandy silt/clay that extended to 4.0 to 7.0 feet and became softer with depth. Underneath the fine- grain silt/clay, we encountered dense to very dense alluvial sandy gravel with 3-inch to 6-inch minus rounded cobbles. The sandy gravel extended to the bottom of all four test pits which reached 9.0 to 9.5 feet in depth. Subsurface explorations in 2016 were consistent with the explorations completed in 2022. Five test pits (identified as TP-4 through TP-8) and four boreholes (identified as BH-5 through BH-8) were completed across the property during our original subsurface explorations in 2016. The explorations generally found 0.75 to 2.0 feet of topsoil overlying fine-grain sandy silt/clay that extended to 4.0 to 8.0 feet. Underneath the fine-grain silt/clay, soil conditions transitioned to medium dense to very dense alluvial sandy gravel with cobbles up to six inches in diameter. The sandy gravel extended to the bottom of all test pits and boreholes. The test pits ranged from 5.5 to 9.0 feet in depth while the boreholes ranged from 16.0 to 30.0 feet in depth. Target bearing for foundations is within the native sandy gravel deposits found at a depth of 4.0 to 8.0 feet depending on location. Foundation support recommendations provided later in this report are based on excavation to the native sandy gravel and placement of the footings either directly on the native sandy gravel or on granular structural fill that bears on the native sandy gravel. Alternative options include the use of helical piers that support footings/slabs and extend to the native gravel. Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 8 Groundwater Conditions During our March 2022 explorations, groundwater was encountered at depths of 5.0 to 7.5 feet below existing grade depending on location. Groundwater levels ranged from 2.8 to 8.0 feet deep during the November 2016 explorations. The groundwater table throughout the Bozeman area fluctuates on a seasonal basis depending on the time of year. Groundwater levels are typically at their lowest during the winter season and at their highest during the spring and early summer due to runoff from mountain snowmelt and spring rains. We anticipate groundwater levels to rise well above the 5.0 to 7.5-foot mark as more of the mountain snowpack melts. Monitoring wells installed in all four test pits in March 2022 and the two wells installed in 2016 are currently being monitored by AESI on a weekly basis through the peak groundwater season. The highest groundwater level recorded as of the date of this report (April 19, 2022) is 2.25 feet below the ground surface in MW-3. Please refer to Figure 3 for approximate monitor well locations. Groundwater monitoring data can be provided upon request and results will be issued at the end of monitoring. Construction of the foundations and utilities will be impacted by high groundwater levels. The Contractor should be made aware of this prior to construction. We anticipate that groundwater dewatering will be required during construction. Laboratory Testing Multiple soil samples were collected from each test pit during the explorations. All sack samples were tested in the AESI laboratory for natural moisture content. Laboratory testing results are found in Appendix B. GENERAL CONSTRUCTION RECOMMENDATIONS Sediment Control Prior to beginning any earthwork construction at the site, adequate sediment control measures must be in place to prevent disturbed soils/sediment from being carried down slope and off the site via surface water runoff. According to Montana State Law, all surface waters must be fully protected from the introduction of sediment by construction-related activities. Most obviously, sediment protection barriers will need to be placed along/around all established drainages, waterways, ponds, wetlands, storm water catch basins, etc, that lie within or adjacent the project area. In addition to protecting these elements, we also believe it is a responsible practice to install a continuous barrier along the down slope side of the construction limits, especially on sloping sites. This “minimal level of effort” will help keep disturbed soils as close to the “source area” as possible and restrict them from being washed of property. Topsoil Stripping and Re-Use A majority of the site is covered by some form of topsoil. All organic soils must be adequately stripped from within each building’s foundation footprint and in all exterior areas that will Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 9 receive asphalt surfacing, concrete slabs, or embankment fills. Final site grading (in landscape areas) and the reclamation of disturbed construction areas are the only recommended re-uses for this organic material. Moisture Sensitivity of Fine-Grained Soils The fine-grained soils (silt/clay) that underlie the site are moisture sensitive materials that can be problematic during construction. It should be noted that the fine-grained soils onsite are already overly moist and excessively wetted by high groundwater levels. It is anticipated that some drying and re-working of the material will be required to enable the sols to be workable and suitable for earthwork construction. Assuming the materials can be properly dried, these soils should be workable and suitable for earthwork construction. However, with only minor increases in moisture content, compaction of these soils can be difficult, if not impossible, until they are adequately dried. The air drying of fine-grained soils requires time, warm weather, and often scarification. For this reason, exposed soils should be protected against precipitation and infiltration. Excavated and fill surfaces should never be left in a rough condition with undrained depressions. In addition to becoming hard to compact in wet conditions, the soils are susceptible to erosion and frost heave. Stormwater pollution prevention (SWPPP) measures should be considered to minimize erosion as discussed above. Furthermore, care should be taken to ensure concrete is not poured over frozen ground that is in a frost heaved condition. Excavation and Re-Use of On-Site Soils Much of the soil that will be excavated during foundation and general site earthwork will consist of native silt, clay, sand, and gravel. In general, these soils can be re-used as site fill, embankment fill, exterior foundation wall backfill, and trench backfill provided they have a moisture content that is conducive for proper compaction. For a more detailed discussion on the acceptable re-use of excavated on-site soils, please refer to the foundation-related fill material section later in this report. Groundwater Dewatering As noted earlier, groundwater dewatering will be necessary for nearly all aspects of construction. FOUNDATION, SLAB, AND DRAINAGE RECOMMENDATIONS Seismic Design Factors Based on our on-site explorations and knowledge of the underlying geology, the seismic site class for the project should be Site Class D (as per criteria presented in the 2018 IBC). Please note that is not the Default Site Class D. Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 10 Building Foundation Design We have assumed the new buildings will be underlain by a concrete slab-on-grade with conventional frost walls and footings around the perimeter and interior spread footings. The site’s subsurface conditions will allow for the use of a shallow foundation system (conventional strip and spread footings) provided all footings are constructed in accordance with our geotechnical recommendations. The use of helical piers is also an option at the site as discussed earlier. We considered the use of crawlspace foundations at the site, but do not have enough information currently to provide specific recommendations due to the unknown levels that high groundwater may reach. Proper separation between footing grades and high groundwater would be required. If possible, we recommend maintaining a minimum of two feet of separation between high groundwater and the bottom of footings in crawlspace applications. Note that providing appropriate separation in crawlspace applications will require additional structural fill to extend from the target bearing sandy gravels encountered at 4.0 to 8.0 feet below existing grade up to footing grade. Achieving this separation will also result in higher finished grades across the site to maintain 4 feet of cover for frost protection, increasing costs associated with fill. Substantial subsurface drainage measures will also likely need to be implemented in crawlspace applications given the possibility of water intrusion into the crawlspace. Clean crushed rock would be recommended to infill the crawlspace up to top of footings. Given the flatness of the site, perimeter footing drains and sub-drains in the crawlspace will need to connect to an exterior sump to pump out any water. Based on our experience with other projects in the City of Bozeman and surrounding area, there are associated challenges with pumping out groundwater and re-routing the water away from the structures to an acceptable location that does not impact surrounding structures. For these reasons, we suggest staying away from crawlspace foundations if possible. Slab and Footing Elevations Assuming buildings will be constructed on slab-on-grade foundations with finished floor elevations set two to three feet above existing grade, we anticipate that 3.0 to 7.0 feet of structural fill may be required to extend from the target bearing gravels up to the bottom of footings. For frost protection, exterior footings should bear at a depth of four feet below the lowest adjacent exterior finished grade. Foundation Support Under Buildings – Option 1: Over-Excavation and Replacement The native sandy gravel found at a depth of 4.0 to 8.0 feet is the “target” foundation bearing material for building improvements. All foundation components, including perimeter, interior, and exterior footings, must bear on the native gravels or granular structural fill that extends from the native gravels up to the footing grade. Two options are provided below with respect to the installation of structural fill under footings. Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 11 The first option is to mass-excavate down to the target bearing gravels within the footprint of the buildings and replace with compacted structural fill. This may be the easiest and quickest option if there are a significant number of interior spread footings that need to be excavated as well. For this scenario, the minimum excavated width (beyond the outside edge of perimeter footings) will depend on the thickness of granular structural fill to be placed under the footing. The excavation should extend a minimum of one-half (½) the required thickness of structural fill at any given location beyond the outside edge of the perimeter footing, but at a minimum should extend 4.0 feet. This dimension is measured at the bottom of the excavation. An additional option is to excavate only the footing lines down to the native gravels and leave some of the fine-grained silt/clay under the slab. This option is only acceptable if the upper fine-grain soils are relatively dry and stable. If this option is selected, we must evaluate the fine-grain soils at the time of excavation to verify they are relatively dry and stable and enough gravel and geotextile reinforcement is added to adequately support the slab as described below. For individual footing lines, the width of the excavation (to ensure load transfer occurs in the structural fill) is the width of the footing plus the depth from the bottom of footing to target bearing (essentially 0.5H:1V). For instance, if the width of the footing is 2 feet and the depth to the native gravels below the bottom of footing is 3 feet, the necessary width of the excavation is 5 feet. The footing is assumed to be centered on the trench. In this scenario, the slab should be supported directly on six inches of clean crushed rock overlying 15 inches of granular structural fill that in turn bears on the native fine-grained soils. The native fine-grained soils should be proof rolled to an unyielding condition and covered with a woven Mirafi 600x geotextile fabric prior to the placement of structural fill. If any wet or soft spots are identified in the subgrade, they should be completely removed and replaced with lifts of compacted granular structural fill. Both the structural fill and clean crushed rock should be vibratory compacted to an unyielding condition with a large smooth drum roller. For exterior footings outside the building footprint that will be excavated and/or over- excavated on an individual basis, the minimum excavation dimensions (centered under the footing) will depend on the thickness of granular structural fill to be placed under the footing, as well as the footing width. The minimum excavation width is equal to the footing width plus the thickness of structural fill under the footing. For instance, if the exterior spread footing is 4 feet by 4 feet and the depth to the native gravel from the bottom of footing is three feet, the dimensions of the over-excavation (measured at the bottom of the excavation) will be 7 feet by 7 feet. The spread footing would need to be centered on the over-excavation. The over- excavated dimensions will allow footing loads to be transmitted within the structural fill to the target bearing soils. If the excavation is only dug to the minimum width dimensions that will satisfy the compacted structural fill requirement, it is important that proper compaction of the structural fill is achieved along the edges and in the corners of the excavation. To accomplish this, the use of small compaction equipment that can “hug” the side of the excavation will be necessary. Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 12 Alternatively, the excavation can be widened beyond the minimum width dimensions to allow for the use of a larger roller. The compaction of granular structural fill materials can be accomplished more effectively and efficiently with large, self-propelled, smooth drum rollers. For this reason, we suggest foundation excavations be made wide enough to accommodate a large roller. In the event groundwater is encountered at the bottom of the excavation (at the native gravel elevation), clean crushed rock may be placed to raise the bottom of the excavation above the groundwater before switching to more traditional structural fill (pit run or crushed sandy gravel). Providing separation from groundwater using the non-moisture-sensitive clean crushed rock will avoid the saturation of the structural fill and subsequent difficulty with compaction. Clean crushed rock should be placed in lifts not exceeding 12 inches and vibratory compacted. Clean crushed rock should be covered with a nonwoven geotextile fabric such as a Mirafi 180N or equal prior to structural fill placement to prevent the migration of fines into the crushed rock. Prior to pouring footings or placing structural fill, the native subgrade should be proof-rolled to an unyielding condition. Any soft or overly moist areas should be removed and replaced with lifts of structural fill compacted to a dense, unyielding condition. A leveling course of crushed rock may be used if there are excessive large rocks in the subgrade that would create an uneven bearing surface. For a complete description of acceptable import, granular structural fill alternatives, along with our specifications for the placement and compaction of these materials, please refer to a later section of this report. In summary, there are only two available options for structural fill under footings (as well as under the entire building area). These include 4”-minus sandy (pitrun) gravel or 1.5”-minus crushed (road mix) gravel. Please recognize that groundwater dewatering will likely be necessary to install the structural fill given the elevated groundwater levels found across much of the site. Provided our recommendations are followed (as described above), the allowable bearing pressure for all perimeter, interior, and exterior footings is 3,000 pounds per square foot (psf). Allowable bearing pressures from transient loading (due to wind or seismic forces) may be increased by 50 percent. We estimate that the above-referenced bearing pressure will result in total settlements of less than one inch, with only minor differential settlements. This bearing capacity only applies if our recommendations are followed. Foundation Support Under Buildings – Option 2: Helical Piers A second option to provide foundation support is the installation of helical piers, which would eliminate much of the need for structural fill. We anticipate the helical piers would be installed at regular 10-foot spacings down to the target bearing soils and the footings designed as Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 13 grade beams to span the helical piers. The slabs could also be supported on helical piers to eliminate the need to remove the soft, fine-grain silt and clay or gravel and geotextile as described below. The helical piers would penetrate the soils and torque up to the appropriate level to achieve a working load, design capacity of 25 to 50 kips. Assuming a factor of safety of 2.0, the ultimate capacity of the helical piers would be 50 to 100 kips. The piers may be battered as necessary to provide uplift and lateral resistance. We recommend that test piers be completed in this area to determine if the recommended capacities and associated installation torques can be achieved. We recommend piers manufactured by AB Chance or an approved equal. All helical piers shall be galvanized for corrosion protection. In this case, interior and exterior grade beams/footings should be designed to span between the helical piers with no support provided by the soils. Alternatively, if the interior slabs and interior footings will not be supported by helical piers, we recommend supporting the slab directly on six inches of clean crushed rock overlying 15 inches of granular structural fill. The native subgrade should be proof rolled to an unyielding condition and covered with a woven Mirafi 600x geotextile fabric prior to the placement of structural fill. If any wet or soft spots are identified in the subgrade, they should be completely removed and replaced with additional lifts of compacted granular structural fill. Both the structural fill and the clean crushed rock should be vibratory compacted to an unyielding condition with a large smooth drum roller. If this alternative is selected, we recommend we be allowed to evaluate the condition of the fine-grained subgrade at the time of excavation. As mentioned previously, the design team could also consider utilizing both the above discussed options for individual buildings depending on the depth to gravel in that area. We would be happy to provide additional recommendations/details if helical piers are the chosen option. Interior Concrete Slabs Under Buildings All interior slabs must be supported on at least six inches of clean crushed rock, which in turn overlies 15 inches (min.) of granular structural fill and geotextile reinforcement. If mass excavation down to native gravels under the footprint of the buildings is chosen, the geotextile reinforcement may be eliminated. Based on the 4.0-to-8.0-foot depth to native gravel in the building areas, and the assumption that finished floor elevations will be set above existing site grades, multiple feet of granular structural fill will need to be placed in the footprint area to build back to interior slab grade. Both the crushed rock and structural fill materials must be compacted to a dense and unyielding condition by vibratory methods. A large, smooth drum roller should be used to compact granular structural fill whenever possible. Native subgrade should be compacted to an unyielding condition prior to the placement of structural fill. Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 14 Lateral Earth Pressures All foundation walls that will be fixed at the top prior to the placement of backfill should be designed for an “at rest” equivalent fluid pressure of 60 pounds per cubic foot (pcf). In contrast, cantilevered retaining walls may be designed for a lower, “active” equivalent fluid pressure of 45 pcf, provided either some slight outward rotation of the wall is acceptable upon backfilling or the wall is constructed in such a way that accommodates the expected rotation. These “at rest” and “active” design values are only applicable for walls that will have backfill slopes of less than ten percent; and which will not be externally loaded by surface pressures applied above and/or behind the wall. Lateral forces from wind, earthquakes, and earth pressures on the opposite side of the structure will be resisted by passive earth pressure against the buried portion of the foundation wall and by friction at the bottom of the footing. Passive earth pressures in compacted, fine- grained backfill should be assumed to have an equivalent fluid pressure of 280 pcf; while a coefficient of friction of 0.4 is estimated between cast-in-place concrete and granular structural fill or native gravel. Actual footing loads (not factored or allowable loads) should be used for calculating frictional resistance to sliding along the base of the footing. Please be aware that the friction coefficient has no built-in factor of safety; therefore, an appropriate safety factor should be selected and used in all subsequent calculations for each load case. The lateral earth pressures summarized above assume that the wall will be backfilled with a suitable material that is compacted to an unyielding condition. It is also assumed that proper drainage measures will be taken to prevent the development of hydrostatic pressures. The lateral earth pressures provided are for static conditions and should be factored accordingly for seismic conditions. Foundation Wall Backfill Exterior foundation wall backfill can consist of any excavated foundation soil, other than topsoil, provided it is not overly moist, highly plastic, or too rocky in composition. In contrast, interior foundation wall backfill shall be limited to the use of granular structural fill materials only. The native soils may require drying prior to re-use as backfill. All select backfill materials must be placed in multiple, thin lifts and properly compacted to 95 percent of their Standard Proctor density. Foundation walls intended to be braced should not be backfilled until the bracing (such as floor joists) is in place to prevent unintended rotation/deflection of the wall. To prevent damaging foundation walls during the backfilling process, only hand-operated compaction equipment is recommended within three feet of walls that are not buried on both sides. To minimize the potential for future settlement problems, the level of care (with respect to the selection of dry backfill materials and the compactive effort that is used) should be increased significantly in those areas that will receive concrete/asphalt surfacing or that will support a retaining wall. Finally, the re-use of topsoil as backfill should be limited to the uppermost four to six inches in landscaped areas. To reduce the infiltration capacity of the Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 15 topsoil (directly next to the foundation wall), it should be well compacted (especially under rock or mulch-filled landscape beds). Surface Water Drainage No water should be allowed to accumulate against or flow along any exposed foundation walls. Concrete or asphalt surfacing that abuts the foundation should be designed with a minimum grade of 2 percent away from all structures, and adjacent landscaped areas should have a slope of at least 5 percent within 10 feet of the wall (see the IBC building codes). To further reduce the potential for moisture infiltration along foundation walls, backfill materials should be well- compacted. The upper 4 to 6 inches of backfill should consist of low permeability topsoil. Except for the locations that will be surfaced by concrete or asphalt, finished grades next to foundation walls should be set no less than 6 inches below the top of the sill plate. We recommend that sediment protection barriers be installed at all points of concentrated discharge, such as at the end of a ditch/swale, to keep all disturbed soils on the property. Subsurface Drainage and Damp-Proofing As noted earlier, there is significant complexity with installing footing drains and interior subdrains in crawlspace applications. The site is relatively flat with no place to daylight drainage. Therefore, we anticipate sumps and pumps would be required. However, this option becomes even more complicated in that the City does not allow dewatering elements that are routed to storm drainage ponds. For these reasons, we have significant concern with the use of crawlspaces and would lean more towards slab-on-grade foundations. Perimeter footing drains for slab-on-grade foundations are not necessary unless the exterior grade will extend above the top of slab (which is normally not done). Buried foundation walls should be damp-proofed with an acceptable commercial product as per the requirements of the International Building Code (IBC 2018). Vapor Barrier To control moisture vapor, we recommend installing a heavy-duty vapor barrier directly under interior slabs. We recommend a vapor barrier with a water vapor transmission rate of 0.006 or lower as established by ASTM E 96, such as a Stego 15-mil Vapor Barrier. The vapor barrier should be installed as per the manufacturer recommendations and ASTM E 1643, ensuring it is properly attached to footings/walls and sealed at the seams. Exterior Concrete Slabs – Sidewalks Depending on site grading, exterior concrete sidewalks can either be supported on non-organic, native soils or on embankment fill material that is placed above the stripped subgrade surface to raise design elevations. The City of Bozeman standard details for non-traffic and traffic slabs depict four and six-inch sections of concrete, respectively, overlying three inches of Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 16 clean crushed rock. We believe a three-inch thickness of crushed rock under slabs is a “minimum value” and, in fact, recommend that it be thickened to at least six inches. The placement of additional crushed rock will increase the drainage capacity under the sidewalk as well as provide additional separation from the underlying fine-grained soils. Consequently, the frost heave potential of the slab should be reduced. Prior to placing embankment fill or crushed rock, both of which must be adequately compacted, the excavated subgrade surface should be compacted and proof-rolled to confirm its stability. If soft or wet areas are identified, these areas should be over-excavated and replaced with suitable, compacted structural fill. Exterior Concrete Slabs and Garage Slabs Depending on site grading, exterior concrete slabs can be supported on non-organic native soils or on compacted on-site soils (see Excavated Foundation Soils section later in this report) placed above the stripped subgrade surface to raise design elevations. Traffic-loaded exterior slabs should be underlain by a minimum of six inches of clean crushed rock and 12 inches of granular structural fill reinforced with woven geotextile fabric (Mirafi 600X or equal). Thickening the crushed rock layer to greater than six inches will improve the drainage capacity under the slab as well as provide additional separation from the underlying soils. Consequently, the frost heave potential of the slab should be reduced. Critical exterior slab areas which cannot undergo any heaving should be underlain by additional crushed rock and two inches or more of below-grade insulation extending outward two feet from the edge of the slab to limit frost penetration. Prior to placing any embankment fill or structural fill, both of which must be adequately compacted, the subgrade surface should be proof-rolled to confirm its stability. If soft or wet areas are identified, they should be over-excavated and replaced with suitable, compacted structural fill. FOUNDATION-RELATED FILL MATERIAL RECOMMENDATIONS Provided below are our recommendations for the foundation-related fill materials that may be used during construction. These include on-site excavated soils, sandy (pitrun) gravel, crushed (road mix) gravel, and clean crushed rock. General placement and compaction criteria follow the specifications. Excavated Foundation Soils During foundation and site earthwork, excavated soils will include native topsoil, silt, clay, sand, and gravel. Please refer to an earlier section of the report, along with the attached exploration logs found in Appendix A, for a detailed description of the site’s subsurface conditions. Based on the shallow groundwater levels found across the development, some saturation of the upper fine-grain soils should be expected. For this reason, moisture conditioning (by drying) will be needed to reuse this material. The acceptable re-uses of this material include site fill, embankment fill, exterior foundation wall backfill, and trench backfill. Only the driest Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 17 soils should be used for compacted fill, while all wetter soils should be placed in non-critical areas that do not require compaction or can tolerate some future settlement. Except for some of the native sand and gravel, none of these soils will qualify for re-use as granular structural fill under footings and interior slabs. Deleterious materials (fill, topsoil, fat clays, etc) should not be used as foundation backfill. Sandy (Pitrun) Gravel Sandy (pitrun) gravel is a granular structural fill alternative for placement under exterior slabs, pavements, and behind foundation walls. This material shall be a non-plastic, well-graded, mixture of clean sand and gravel with 100 percent of its fragments passing a four-inch screen and less than 10 percent of its particles (by weight) finer than the No. 200 sieve. In addition to these material and gradation recommendations, it should meet all other applicable specifications as presented in Section 02234 of the Montana Public Works Standard Specifications (MPWSS) for uncrushed, sub-base course gravel. Crushed (Road Mix) Gravel Crushed (road mix) gravel is another granular structural fill alternative for placement under and/or behind footings, slabs, and walls. This material shall be a non-plastic, well-graded, mixture of clean, sand and gravel that is processed (crushed) such that 100 percent of its fragments pass a 1-1/2-inch screen and less than 5 percent of its particles (by weight) are finer than the No. 200 sieve. In addition, it should meet all other specifications as presented in Section 02235 of the MPWSS for crushed, base course gravel. Clean Crushed Rock The primary uses for crushed rock include placement under concrete slabs and behind foundation and retaining walls for drainage-related purposes. Crushed rock shall consist of a clean assortment of angular fragments with 100 percent passing a one-inch screen and less than 1 percent (by weight) finer than the No. 100 sieve. This aggregate product needs to be manufactured by a crushing process and over 50 percent of its particles must have fractured faces. It is not acceptable to use rock that contains abundant spherical particles for foundation- related applications. Fill Placement and Compaction All fill materials should be placed in uniform, horizontal lifts and compacted to an unyielding condition. This includes clean crushed rock, which can be compacted and/or consolidated by vibratory means. The maximum “loose lift thickness” for all fill materials (prior to compaction) should be limited to 10 inches for large, self-propelled rollers, 6 inches for remote-controlled, dual drum rollers, and 4 inches for walk-behind plate or jumping jack compactors. The moisture content of any material to be compacted should be within approximately two (2) percent (+/-) of its optimum value for maximum compaction. Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 18 Special attention must be paid to the proper compaction of structural fill materials along the edges and in the corners of the foundation excavation. These areas are usually “tight and confined” and, as a result, cannot be adequately compacted with large equipment. This is especially important where footing alignments/locations are only over-excavated to the minimum width requirements that were presented in an earlier section of this report. There are two available options for dealing with this issue. Either small compactors must be used that are able to “hug” the side of the excavation or the limits of the excavation must be increased such that compaction of the entire minimum structural fill width can be achieved with larger equipment. Provided in Table 1 are compaction recommendations for general foundation applications. These are presented as a percentage of the maximum dry density of the fill material as defined in ASTM D-698. Table 1. Compaction Recommendations (Application vs. Percent Compaction) APPLICATION % COMPACTION Granular Structural Fill Under Footings and Interior Slabs: 98 Embankment Fill Under Interior and Exterior Slabs: 95 Backfill Behind Foundation and Retaining Walls: 95 Clean Crushed Rock Under Slabs and Behind Walls: N/A (Vibration Required) Site Fill Around Building and Under Pavement Areas: 95 UNDERGROUND UTILITY RECOMMENDATIONS All underground utility improvements shall be designed according to City of Bozeman (COB) standards and constructed in accordance with the Montana Public Works Standard Specifications (MPWSS) and the COB Modifications to these specifications. For the most part, water and sewer pipe will most likely be supported in the native gravels. Given the elevated groundwater levels, dewatering will probably be required. Should utility lines be supported by the upper fine-grained soils that were very moist and soft, Type 2 bedding may be required by the Engineer to support the lines. We recommend a bid item be included on the bid form in case Type 2 bedding is deemed necessary. During utility installation, the trench excavation soils will consist of native topsoil, silt, clay, sand, and gravel. Much of the material could be very moist to saturated and may need to be dried prior to re-use. All trench backfill materials should be placed in thin lifts and compacted to at least 95 percent of the material’s maximum dry density. Given that the native gravels Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 19 contain abundant large cobbles, all utilities should be well-bedded with crushed rock in accordance with COB and MWPSS standards. ASPHALT PAVEMENT RECOMMENDATIONS Pavement Section Design Presented in Tables 2 through 5 is our recommended asphalt pavement section for all new parking lots and local road improvements associated with the project. The design sections assume a 20-year service life and are based on the site’s shallow, fine-grained subgrade soil conditions, a conservative estimate for traffic loading, and our previous experience with other similar developments. They were designed in accordance with City of Bozeman, Montana Department of Transportation (MDT), and American Association of State Highway and Transportation Officials (AASHTO) guidelines and standards. For a detailed review of our design calculations and an explanation of design input parameters, please see the documentation provided in Appendix C. Tables 2 and 3 provide the recommended design thickness for parking lots assuming stable and unstable subgrade conditions. As summarized in Table 3, if the subgrade conditions are unstable, we suggest the addition of a non-woven geotextile fabric and geogrid to the design section. All fabric and geogrid utilized should be overlapped at seams in accordance with manufacturer recommendations. Geogrid seams should be zip-tied together. Table 2. Pavement Section Design – On-Site Parking Lots – Option 1 Stable Subgrade COMPONENT COMPACTED THICKNESS (IN) Asphalt Concrete: 3 Base Course - Crushed (road mix) Gravel: 6 Sub-Base Course - Uncrushed Sandy (pitrun) Gravel: 15 Woven Geotextile Fabric (Mirafi 600X or Approved Equal): Yes Stable Subgrade Soils (Less Topsoil): Compacted to 95% TOTAL SECTION THICKNESS: 24 Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 20 Table 3. Pavement Section Design – On-Site Parking Lots – Option 2 Unstable Subgrade COMPONENT COMPACTED THICKNESS Asphalt Concrete: 3 Base Course - Crushed (road mix) Gravel: 6 Sub-Base Course - Uncrushed Sandy (pitrun) Gravel: 15 Tensar TX-190L TriAxial Geogrid (No Approved Equals): Yes 8 oz. Non-Woven Geotextile Fabric (Mirafi 180N or Approved Equal): Yes Unstable Subgrade Soils (Less Topsoil): Smooth and Rut-Free TOTAL SECTION THICKNESS: 24 Tables 4 and 5 provide the recommended design thickness for local roads assuming stable and unstable subgrade conditions. Table 4. Pavement Section Design – Local Roads – Option 1 Stable Subgrade COMPONENT COMPACTED THICKNESS (IN) Asphalt Concrete: 3 Base Course - Crushed (road mix) Gravel: 6 Sub-Base Course - Uncrushed Sandy (pitrun) Gravel: 21 Woven Geotextile Fabric (Mirafi 600X or Approved Equal): Yes Stable Subgrade Soils (Less Topsoil): Compacted to 95% TOTAL SECTION THICKNESS: 30 Table 5. Pavement Section Design – Local Roads – Option 2 Unstable Subgrade COMPONENT COMPACTED THICKNESS (IN) Asphalt Concrete: 3 Base Course - Crushed (road mix) Gravel: 6 Sub-Base Course - Uncrushed Sandy (pitrun) Gravel: 21 Tensar TX-190L TriAxial Geogrid (No Approved Equals): Yes 8 oz. Non-Woven Geotextile Fabric (Mirafi 180N or Approved Yes Unstable Subgrade Soils (Less Topsoil): Smooth and Rut-Free TOTAL SECTION THICKNESS: 30 Please note, unstable conditions are subgrade that ruts and deflects when proof-rolled with a loaded truck. In those cases, we recommend switching to the unstable subgrade design section (i.e., the addition of non-woven geotextile and geogrid). Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 21 Also note that if the subgrade conditions are stable, we still recommend the addition of a woven geotextile separator fabric to separate the native fine-grain soils and the gravel. Pavement Section Materials, Placement, and Compaction The sub-base and base course materials that comprise the granular parts of the pavement section shall consist of 4-inch minus uncrushed sandy (pitrun) gravel and 1-1/2-inch minus crushed (road mix) gravel, respectively. Both gravel courses shall meet the material and gradation specifications as presented in MPWSS, Sections 02234 and 02235. Under normal circumstances, the gravel products shall be placed in loose lifts not exceeding 10 inches in thickness (depending on size of the compactor) and compacted to at least 95 percent of the maximum dry density as defined in ASTM D-698. However, if subgrade soils are found to be overly soft and the sub-base gravel section needs to be increased to greater than 15 inches, we recommend placing and compacting this material in one single lift to prevent damaging and tearing the geotextile fabric and geogrid with the construction equipment. COLD/WINTER WEATHER CONSTRUCTION If foundation construction will occur during the cold/winter weather season, the Contractor shall take all necessary precautions to prevent the earthwork from freezing and/or from being contaminated with snow. Exposed subgrade and fill materials (under footings, slabs, and walls) should be adequately covered with concrete insulation blankets to prevent frost penetration and to protect them from snow. All soils that are used for fill under or around foundation components should be relatively dry, be free of intermixed snow and frozen clods, and must not be placed when it is snowing. No fill materials (or footings) should be placed on frozen soils, which may be in a “frost-heaved condition”, or over layers of snow. When earthwork will proceed during the non-optimal times of the year, we recommend that it be performed in an expeditious manner; thereby, minimizing the time that the foundation excavations are open and exposed to the elements. In addition, positive drainage must be established away from the excavations to prevent the entry of surface water runoff and the saturation of the underlying soils. Please be fully aware that carelessness with respect to any of the above-referenced items can potentially lead to foundation settlement problems in the spring when the frost thaws and/or the snow melts. Cold weather concrete practices/methods should be implemented when the conditions dictate. Virga Capital April 19, 2022 Lumber Yard Apartments Geotechnical Report Bozeman, Montana Allied Engineering Services, Inc. Page 23 REFERENCES 1. International Code Council, 2018, “2018 International Building Code”. 2. Montana Bureau of Mines and Geology, 2014, “Well Logs”, Groundwater Information Center. 3. Montana Contractors’ Association, April 2010, “Montana Public Works Standard Specifications”, Sixth Edition. 4. Slagle, Steven E., May 1995, “Geohydrologic Conditions and Land Use in the Gallatin Valley, Southwestern Montana, 1992-93”, U.S. Department of the Interior, U.S. Geological Survey. LIST OF FIGURES FFiigguurree 11 –– VViicciinniittyy MMaapp FFiigguurree 22 –– QQuuaaddrraannggllee MMaapp FFiigguurree 33 –– TTeesstt PPiitt LLooccaattiioonn MMaapp FFiigguurree 44 –– GGeeoollooggyy MMaapp FFiigguurree 55 –– GGrroouunnddwwaatteerr MMaapp FIGURECivil Engineering Geotechnical EngineeringLand Surveying 32 DISCOVERY DRIVE . BOZEMAN, MT 59718PHONE (406) 582-0221 . FAX (406) 582-5770www.alliedengineering.com LOTS 1, 2, & 3A, BLK 3, PT LAND PH 2 SUB. VICINITY MAP BOZEMAN, MONTANA 1 N FIGURECivil Engineering Geotechnical EngineeringLand Surveying 32 DISCOVERY DRIVE . BOZEMAN, MT 59718PHONE (406) 582-0221 . FAX (406) 582-5770www.alliedengineering.com LOTS 1, 2, & 3A, BLK 3, PT LAND PH 2 SUB. QUADRANGLE MAP BOZEMAN, MONTANA 2 N FIGURECivil Engineering Geotechnical EngineeringLand Surveying 32 DISCOVERY DRIVE . BOZEMAN, MT 59718PHONE (406) 582-0221 . FAX (406) 582-5770www.alliedengineering.com LOTS 1, 2, & 3A, BLK 3, PT LAND PH 2 SUB. TEST PIT LOCATION MAP BOZEMAN, MONTANA 3 TP#MW-# LOT 1 TP-2MW-2 TP-3MW-3 N LOT 2 LOT 3A TP-1 MW-1 TP-4MW-4 TP# MW-# BH# TP-8 TP-4MW-A TP-5 TP-6 TP-7MW-B BH-5 BH-6 BH-7 BH-8 FIGURECivil Engineering Geotechnical EngineeringLand Surveying 32 DISCOVERY DRIVE . BOZEMAN, MT 59718PHONE (406) 582-0221 . FAX (406) 582-5770www.alliedengineering.com LOTS 1, 2, & 3A, BLK 3, PT LAND PH 2 SUB. GEOLOGY MAP BOZEMAN, MONTANA 4 N FIGURECivil Engineering Geotechnical EngineeringLand Surveying 32 DISCOVERY DRIVE . BOZEMAN, MT 59718PHONE (406) 582-0221 . FAX (406) 582-5770www.alliedengineering.com LOTS 1, 2, & 3A, BLK 3, PT LAND PH 2 SUB. GROUNDWATER MAP BOZEMAN, MONTANA 5 N LIST OF APPENDICES AAppppeennddiixx AA –– TTeesstt PPiitt LLooggss aanndd BBoorreehhoollee LLooggss AAppppeennddiixx BB –– LLaabboorraattoorryy TTeessttiinngg RReessuullttss AAppppeennddiixx CC –– PPaavveemmeenntt SSeeccttiioonn DDeessiiggnn AAppppeennddiixx DD –– LLiimmiittaattiioonnss ooff YYoouurr GGeeootteecchhnniiccaall RReeppoorrtt APPENDIX A TTeesstt PPiitt LLooggss 22002200 TTeesstt PPiitt LLooggss 22001166 BBoorreehhoollee LLooggss 22001166 {0.0' - 1.25'}: Native Topsoil:Soft; dark brown to black; organic SILT/CLAY;very moist.{1.25' - 5.0'}: Fine-Grain Deposit:Very soft; brown; sandy SILT/CLAY; very moistto wet.·Pocket Penetrometer @ 2.0' = 1.0 tsf.·Pocket Penetrometer @ 3.0' = 0.5 tsf.·Softer with depth.{5.0' - 9.0'}: Alluvium:Dense; brown; sandy GRAVEL with abundant3"-minus rounded cobbles; wet.·Occasional 6"-minus rounded cobbles.·Groundwater encountered at 6.5'.Notes:·MW-1 installed.·Composite sample collected from all fourtest pits from 4.0 to 6.0 feet.12DEPTH (FT) SAMPLES % WATER CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA22-0159.0'6.5'Test Pit Designation: TP-1 Location:Surface Elevation: Backhoe Type: Hitachi 130 Job Number:Total Depth: Backhoe Operator: John (RLS Construction) Project: Lumber Yard ApartmentsGroundwater: Logged By: EGS (AESI) Date: March 10, 20223S1-A@4.0'See Test Pit Location Map;45.69579, -111.0555630.1%246810GWT at 6.5'108642132Target Bearing at 5.0' {0.0' - 1.5'}: Native Topsoil:Soft; dark brown to black; organic SILT/CLAY;very moist.{1.5' - 7.0'}: Fine-Grain Deposit:Very soft; brown; sandy SILT/CLAY; very moistto wet.·Pocket Penetrometer @ 2.0' = 1.0 tsf.·Pocket Penetrometer @ 3.0' = 0.5 tsf.·Softer with depth.{7.0' - 9.5'}: Alluvium:Dense; brown; sandy GRAVEL with abundant3"-minus rounded cobbles; wet.·Groundwater encountered at 7.5'.Notes:·MW-2 installed.·Composite sample collected from all fourtest pits from 4.0 to 6.0 feet.12DEPTH (FT) SAMPLES % WATER CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA22-0159.5'7.5'Test Pit Designation: TP-2 Location:Surface Elevation: Backhoe Type: Hitachi 130 Job Number:Total Depth: Backhoe Operator: John (RLS Construction) Project: Lumber Yard ApartmentsGroundwater: Logged By: EGS (AESI) Date: March 10, 20223S2-A@5.0'See Test Pit Location Map;45.69635, -111.0547030.4%246810GWT at 7.5'108642132Target Bearing at 7.0' {0.0' - 2.5'}: Native Topsoil:Soft; dark brown to black; organic SILT/CLAY;very moist.{2.5' - 4.0'}: Fine-Grain Deposit:Very soft; brown; sandy SILT/CLAY; very moist.·Pocket Penetrometer @ 3.0' = 0.5 tsf.·Softer with depth.{4.0' - 9.0'}: Alluvium:Very dense; brown; sandy GRAVEL withabundant 4"-minus rounded cobbles; wet.·Groundwater encountered at 5.0'.Notes:·MW-3 installed.·Composite sample collected from all fourtest pits from 4.0 to 6.0 feet.12DEPTH (FT) SAMPLES % WATER CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA22-0159.0'5.0'Test Pit Designation: TP-3 Location:Surface Elevation: Backhoe Type: Hitachi 130 Job Number:Total Depth: Backhoe Operator: John (RLS Construction) Project: Lumber Yard ApartmentsGroundwater: Logged By: EGS (AESI) Date: March 10, 20223S3-A@4.0'See Test Pit Location Map;45.69622, -111.0534123.6%246810GWT at 5.0'108642132Target Bearing at 4.0' {0.0' - 1.25'}: Native Topsoil:Soft; dark brown to black; organic SILT/CLAY;very moist.{1.25' - 4.5'}: Fine-Grain Deposit:Very soft; brown; sandy SILT/CLAY; very moist.·Pocket Penetrometer @ 2.5' = 0.5 tsf.·Softer with depth.{4.5' - 9.0'}: Alluvium:Dense; brown; sandy GRAVEL with abundant3"-minus rounded cobbles; wet.·Groundwater encountered at 5.0'.Notes:·MW-4 installed.·Composite sample collected from all fourtest pits from 4.0 to 6.0 feet.12DEPTH (FT) SAMPLES % WATER CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA22-0159.0'5.0'Test Pit Designation: TP-4 Location:Surface Elevation: Backhoe Type: Hitachi 130 Job Number:Total Depth: Backhoe Operator: John (RLS Construction) Project: Lumber Yard ApartmentsGroundwater: Logged By: EGS (AESI) Date: March 10, 20223S4-A@3.0'See Test Pit Location Map;45.69554, -111.0526127.0%246810GWT at 5.0'1086421Target Bearing at 4.5'32 November 21, 2016Embassy Suites-Hampton Inn16-202John Deere 310 SKCalen - Townsend ExcavatingEGS (AESI)Observed at 6.0'8.0'N/A1Location: 45.697167 N -111.054996 WDEPTH (FT)SAMPLES% WATERCONTENTDESCRIPTION OF MATERIALSSURFACE ELEVATION:TOTAL DEPTH:GROUNDWATER:LOGGED BY:BACKHOE OPERATOR:BACKHOE TYPE:DATE:PROJECT:JOB NUMBER:2016128420161284Test Pit Designation: TP-4 (2016)Horizontal Distance in Feet2{0.0' - 1.5'}: TopsoilSoft; dark brown to black; organic sandy SILT;very moist.{1.5' - 5.0'}: Lean CLAY/SILTMedium stiff to stiff; light brown; leanCLAY/SILT; moist.-Pocket Penetrometer = 1.0 tsf @ 3.0'Atterberg Limits (S4-A @ 3.0')-PL = 24.1-LL = 40.0-PI = 15.9{5.0' - 8.0'}: AlluviumDense to very dense; brown; sandy GRAVELwith rounded rock up to 6" in diameter; wet.Notes:-groundwater monitoring well installed (MW-A)-Test Pit completed in 2016.Civil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comS4-A@3'3S4-B@7'7.428.7321Groundwater at 6'Suitable Bearing at 5' November 21, 2016Embassy Suites-Hampton Inn16-202John Deere 310 SKCalen - Townsend ExcavatingEGS (AESI)8.0'9.0'N/A1Location: 45.695557 N -111.054573 WDEPTH (FT)SAMPLES% WATERCONTENTDESCRIPTION OF MATERIALSSURFACE ELEVATION:TOTAL DEPTH:GROUNDWATER:LOGGED BY:BACKHOE OPERATOR:BACKHOE TYPE:DATE:PROJECT:JOB NUMBER:2016128420161284Test Pit Designation: TP-5 (2016)Horizontal Distance in Feet2{0.0' - 0.75'}: TopsoilSoft; dark brown to black; organic sandy SILTwith small roots; very moist.{0.75' - 8.0'}: Lean CLAY/SILTSoft to stiff; light brown to brown; leanCLAY/SILT; moist.-Pocket Penetrometer = 2.0 tsf @ 3.0'{8.0' - 9.0'}: AlluviumMedium dense; brown; sandy GRAVEL withrounded rock up to 6" in diameter; wet.Notes:-Test Pit completed in 2016.Civil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comS5-C@5'3S5-B@2.5'23.124.7321S5-D@8.0'19.7S5-A@1'22.9Groundwater at 8'Suitable Bearing at 8' November 21, 2016Embassy Suites-Hampton Inn16-202John Deere 310 SKCalen - Townsend ExcavatingEGS (AESI)5.5'5.5'N/A1Location: 45.6695744 N -111.053249 WDEPTH (FT)SAMPLES% WATERCONTENTDESCRIPTION OF MATERIALSSURFACE ELEVATION:TOTAL DEPTH:GROUNDWATER:LOGGED BY:BACKHOE OPERATOR:BACKHOE TYPE:DATE:PROJECT:JOB NUMBER:2016128420161284Test Pit Designation: TP-6 (2016)Horizontal Distance in Feet2{0.0' - 1.5'}: TopsoilSoft; dark brown; organic sandy SILT with smallroots; moist.{1.5' - 4.0'}: Lean CLAY/SILTStiff to very stiff; brown; lean CLAY/SILT; moist.-Pocket Penetrometer = 4.0 tsf @ 3.5'{4.0' - 5.5'}: AlluviumDense to very dense; brown; sandy GRAVELwith rounded rock up to 6" in diameter; wet.Notes:-Test Pit completed in 2016.Civil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.com3S6-B@5'8.4321S6-A@3'19.5Groundwater at 5.5'Suitable Bearing at 4' November 21, 2016Embassy Suites-Hampton Inn16-202John Deere 310 SKCalen - Townsend ExcavatingEGS (AESI)7.0'8.5'N/A1Location: 45.695799 N -111.052029 WDEPTH (FT)SAMPLES% WATERCONTENTDESCRIPTION OF MATERIALSSURFACE ELEVATION:TOTAL DEPTH:GROUNDWATER:LOGGED BY:BACKHOE OPERATOR:BACKHOE TYPE:DATE:PROJECT:JOB NUMBER:2016128420161284Test Pit Designation: TP-7 (2016)Horizontal Distance in Feet2{0.0' - 2.0'}: TopsoilSoft; dark brown to black; organic sandy SILTwith occasional small roots; moist.{2.0' - 5.5'}: Lean CLAY/SILTStiff to very stiff; light brown to brown; leanCLAY/SILT; moist.-Pocket Penetrometer = 2.0-3.0 tsf @ 3.0'-Pocket Penetrometer = 1.0 tsf @5.0'Atterberg Limits (S1-B @ 4.0')-PL = 23.7-LL = 36.1-PI = 12.4{5.5' - 8.5'}: AlluviumDense to very dense; brown; sandy GRAVELwith rounded rock up to 6" in diameter; wet.Notes:-Monitoring well installed-TP walls caving-Test pit completed in 2016.Civil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.com3S7-C@5'28.0321S7-A@1.5'29.0S7-B@3'27.7S7-D@7'9.8Bucket@8'Groundwater at 7'Suitable Bearing at 5.5' November 21, 2016Embassy Suites-Hampton Inn16-202John Deere 310 SKCalen - Townsend ExcavatingEGS (AESI)4.5'5.5'N/A1Location: 45.696074 N -111.056308 WDEPTH (FT)SAMPLES% WATERCONTENTDESCRIPTION OF MATERIALSSURFACE ELEVATION:TOTAL DEPTH:GROUNDWATER:LOGGED BY:BACKHOE OPERATOR:BACKHOE TYPE:DATE:PROJECT:JOB NUMBER:2016128420161284Test Pit Designation: TP-8 (2016)Horizontal Distance in Feet2{0.0' - 2.0'}: TopsoilSoft; dark brown to black; organic sandy SILT;moist.{2.0' - 4.0'}: Lean CLAY/SILTVery soft to medium stiff; brown; leanCLAY/SILT; moist to very moist.-Pocket Penetrometer < 1.0 tsf @ 3.0'{4.0' - 5.5'}: AlluviumDense to very dense; brown; sandy GRAVELwith rounded rock up to 4" in diameter; wet.Notes:-Test Pit completed in 2016.Civil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.com3321S8-A@1'41.1S8-B@3'31.0Groundwater at 4.5'Suitable Bearing at 4' DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION 10.0 20.0 Geotechnical Engineering 32 DISCOVERY DRIVE BOZEMAN, MT 59718 FAX (406) 582-5770 PHONE (406) 582-0221Land SurveyingCivil Engineering LOG OF BORING PROJECT: Embassy Suites - Hampton Inn JOB #: 16-202 BORING: BH-5 (2016) PAGE: 1 of 1 LOCATION: Bozeman, MT. ELEVATION: N/A DEPTH: 30.0' GW: 2.8' DRILL TYPE: Mobile B-60 FIELD ENGINEER: EGS DATE: 11/22/16 DRILLER: O'Keefe Drilling of Butte, MT CASING/HAMMER/SAMPLER: 3.75"ID/140 lb./SSS {0.0' - 1.0'}: TopsoilSoft; dark brown; sandy SILT with abundant roots; moist. S5-A @ 0.0' - 1.5'(SSS) S5-B @ 4.0' - 5.5'(SSS) S5-C @9.0' - 10.5'(SSS) S5-D @14.0'-15.5'(SSS) S5-E @19.0'-20.5'(SSS) S5-F @ 24.0'-25.5'(SSS) S5-G @ 29.0'-30.5'(SSS) 4 93 37 75 71 94 58 29.2% 12.5% 9.9% 12.4% 15.8% 8.5% 13.9% General Notes:1. On top of possible rock at4.0'-5.5'2. Drill grinding from 4.0'-15.0'3. Drills slow at 20.0'4. Easy drilling at 28.0'-30.0' ·SSS - 2.0'' O.D. Split SpoonSample ·The beginning and endingdepths of the individual soillayers are approximate.End of Boring @ 30' {1.0' - 4.0}: Lean CLAY/SILTMedium stiff to stiff; light brown; leanCLAY/SILT; moist. {4.0' - 30.0'}: AlluviumDense to very dense; brown; sandyGRAVEL; wet. DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION 10.0 20.0 Geotechnical Engineering 32 DISCOVERY DRIVE BOZEMAN, MT 59718 FAX (406) 582-5770 PHONE (406) 582-0221Land SurveyingCivil Engineering LOG OF BORING PROJECT: Embassy Suites - Hampton Inn JOB #: 16-202 BORING: BH-6 (2016) PAGE: 1 of 1 LOCATION: Bozeman, MT. ELEVATION: N/A DEPTH: 16.0' GW: 5.5' DRILL TYPE: Mobile B-60 FIELD ENGINEER: EGS DATE: 11/22/16 DRILLER: O'Keefe Drilling of Butte, MT CASING/HAMMER/SAMPLER: 3.75"ID/140 lb./SSS {0.0' - 1.0'}: TopsoilSoft; dark brown; organic sandy SILT; moist. S6-A @ 0.0' - 1.5'(SSS) S6-B @ 4.0' - 5.5'(SSS) S6-C @9.0' - 10.5'(SSS) S6-D @14.0'-15.5'(SSS) S6-E @15.0'-16.5'(SSS) 6 27 47 50+ 50+ 29.5% 26.6% 15.5% - - General Notes:1. Sandy GRAVEL containsreddish rock fragments2. Seam of dark brown sandyGRAVEL at 10.0'3. Drill grinding at 11.0'4. Significant drill jumping at13.0'5. Very slow/rough drillin at15.0'6. Drilled for 25 minutes with noprogress (drill refusal).7. No sample returned for bothS6-D and S6-E. ·SSS - 2.0'' O.D. Split SpoonSample ·The beginning and endingdepths of the individual soillayers are approximate. End of Boring @ 16' {1.0' - 4.0}: Lean CLAY/SILTMedium stiff to stiff; light brown; leanCLAY/SILT; moist. {4.0' - 16.0'}: AlluviumDense to very dense; brown with traces ofgrey and red; sandy GRAVEL; wet. DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION 10.0 20.0 Geotechnical Engineering 32 DISCOVERY DRIVE BOZEMAN, MT 59718 FAX (406) 582-5770 PHONE (406) 582-0221Land SurveyingCivil Engineering LOG OF BORING PROJECT: Embassy Suites - Hampton Inn JOB #: 16-202 BORING: BH-7 (2016) PAGE: 1 of 1 LOCATION: Bozeman, MT. ELEVATION: N/A DEPTH: 25.0' GW: 5.1' DRILL TYPE: Mobile B-60 FIELD ENGINEER: EGS DATE: 11/22/16 DRILLER: O'Keefe Drilling of Butte, MT CASING/HAMMER/SAMPLER: 3.75"ID/140 lb./SSS {0.0' - 1.0'}: TopsoilSoft; dark brown; sandy SILT with abundant roots; moist. 5 6 33 27 16 60 25 29 22.1% 25.8% 12.5% 25.0% 27.8% 13.1% 18.0% 29.7% General Notes:1. Drill grinding at 5.0' andsignificant grinding at 10.0'2. Reddish rock in sample at 5.0'3. Appears to be seam of brownlean CLAY/SILT in samplerat ~20.0' ·SSS - 2.0'' O.D. Split SpoonSample ·The beginning and endingdepths of the individual soillayers are approximate. End of Boring @ 25' {1.0' - 4.0}: Lean CLAY/SILTMedium stiff to stiff; light brown; leanCLAY/SILT; moist. {4.0' - 25.0'}: AlluviumDense; brown; sandy GRAVEL; wet. S7-A @ 0.0' - 1.5'(SSS) S7-B @ 2.0' - 3.5'(SSS) S7-C@4.0'-5.5'(SSS) S7-C @7.0' - 8.5'(SSS) S7-D @9.0'-10.5'(SSS) S7-E @14.0'-15.5'(SSS) S7-F @ 19.0'-20.5'(SSS) S7-G @ 24.0'-25.5'(SSS) DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION 10.0 20.0 Geotechnical Engineering 32 DISCOVERY DRIVE BOZEMAN, MT 59718 FAX (406) 582-5770 PHONE (406) 582-0221Land SurveyingCivil Engineering LOG OF BORING PROJECT: Embassy Suites - Hampton Inn JOB #: 16-202 BORING: BH-8 (2016) PAGE: 1 of 1 LOCATION: Bozeman, MT. ELEVATION: N/A DEPTH: 25.0' GW: 5.9' DRILL TYPE: Mobile B-60 FIELD ENGINEER: EGS DATE: 11/22/16 DRILLER: O'Keefe Drilling of Butte, MT CASING/HAMMER/SAMPLER: 3.75" ID/140 lb./SSS {0.0' - 0.5'}: TopsoilSoft; dark brown; sandy SILT with abundant roots; moist. General Notes:1. Drill grinding at 5.0' andsignificant grinding at 10.0'2. Reddish rock in sample at 5.0'3. Appears to be seam of brownlean CLAY/SILT in samplerat ~20.0' ·SSS - 2.0'' O.D. Split SpoonSample ·The beginning and endingdepths of the individual soillayers are approximate. End of Boring @ 25' {0.5 - 4.0}: Lean CLAY/SILTMedium stiff to stiff; light brown; leanCLAY/SILT; moist. {4.0' - 25.0'}: AlluviumDense; brown; sandy GRAVEL; wet. S8-A @ 0.0' - 1.5'(SSS) S8-B @ 4.0' - 5.5'(SSS) S8-C @9.0' - 10.5'(SSS) S8-D @14.0'-15.5'(SSS) S8-E @19.0'-20.5'(SSS) S8-F @ 24.0'-25.5'(SSS) 6 40 37 35 43 30 26.4% 3.3% 14.7% 13.2% 12.1% 13.2% APPENDIX B LLaabboorraattoorryy TTeessttiinngg RReessuullttss MOISTURE CONTENT DETERMINATION (ASTM D-2216) Project: Lumber Yard Apartments Project Number: 22-015Sample Identification: Varies Soil Classification: Varies Date Sampled: March 10, 2022 Date Tested: March 18, 2022 Tested By: HRT Sample Identification:S1-A S2-A S3-A S4-A Exploration Location:TP-1 TP-2 TP-3 TP-4 Sample Depth (ft):4.0 5.0 4.0 3.0 Container Number:P AA T R Weight of Container:49.29 49.07 51.59 50.73 Container + Wet Soil:250.27 354.79 261.37 293.20 Container + Dry Soil:203.80 283.58 221.29 241.72 Weight of Water:46.47 71.21 40.08 51.48 Weight of Dry Soil:154.51 234.51 169.70 190.99 Moisture Content:30.1%30.4%23.6%27.0% Sample Identification: Exploration Location: Sample Depth (ft): Container Number: Weight of Container: Container + Wet Soil: Container + Dry Soil: Weight of Water: Weight of Dry Soil: Moisture Content: Reviewed By: 32 Discovery DriveBozeman, MT 59718 Phone (406) 582-0221 Fax (406) 582-5770 APPENDIX C PPaavveemmeenntt SSeeccttiioonn DDeessiiggnn PAVEMENT SECTION DESIGN Project: Lumber Yard Apartments Project Number: 22-015 Date: April 15, 2022 Prepared By: Jessi Ellingsen Important Notes: 1) See following pages for an Explanation of the Design Input Parameters. 2) Sub-base course shall be comprised of import sandy pitrun gravel.3) Assumes the subgrade is stable. 4) For unstable subgrade, we recommend the addition of a non-woven geotextile fabric and geogrid to the design section. Please see geotech report for details. PARKING LOTS DESIGN INPUT PARAMETERS ESALs (total)100,000 Subgrade CBR, (%)2.50 Subgrade Resilient Modulus, MR (psi)3,750 Reliability, R (%)90Standard Normal Deviate, ZR -1.282 Overall Standard Deviation, So 0.45 Initial Serviceability, po 4.2 DESIGN EQUATION Terminal Serviceability, pt 2.0 Design Serviceability Loss, (PSI)2.2 5 = left side 5.0073 = right side Required Structural Number, RSN 3.00 (Manipulate RSN such that the left and right side of equation match.) Asphalt Concrete Layer Coefficient, a1 0.41 Base Course Layer Structural Coefficient, a2 0.14 Base Course Layer Drainage Coefficient, m2 0.90 Sub-Base Course Layer Structural Coefficient, a3 0.09 Sub-Base Course Layer Drainage Coefficient, m3 0.90 DESIGN PAVEMENT SECTION Asphalt Concrete Thickness, D1 (in)3.0 Granular Base Course Thickness, D2 (in)6.0 Granular Sub-Base Course Thickness, D3 (in)15.0 Calculated Structural Number, CSN 3.20 Pavement Section Design: Page 1 of 1 PAVEMENT SECTION DESIGN Project: Lumber Yard Apartments Project Number: 22-015 Date: April 15, 2022 Prepared By: Jessi Ellingsen Important Notes: 1) See following pages for an Explanation of the Design Input Parameters. 2) Sub-base course shall be comprised of import sandy pitrun gravel. 3) Assumes the subgrade is stable. 4) For unstable subgrade, we recommend the addition of a non-woven geotextile fabric and geogrid to the design section. Please see geotech report for details. LOCAL STREETS DESIGN INPUT PARAMETERS ESALs (total)400,000 Subgrade CBR, (%)2.50 Subgrade Resilient Modulus, MR (psi)3,750 Reliability, R (%)90Standard Normal Deviate, ZR -1.282 Overall Standard Deviation, So 0.45 Initial Serviceability, po 4.2 Terminal Serviceability, pt 2.0 DESIGN EQUATION Design Serviceability Loss, (PSI)2.2 5.60206 = left side Required Structural Number, RSN 3.69 5.6099 = right side (Manipulate RSN such that the left and right side of equation match.) Asphalt Concrete Layer Coefficient, a1 0.41 Base Course Layer Structural Coefficient, a2 0.14 Base Course Layer Drainage Coefficient, m2 0.90 Sub-Base Course Layer Structural Coefficient, a3 0.09 Sub-Base Course Layer Drainage Coefficient, m3 0.90 DESIGN PAVEMENT SECTION Asphalt Concrete Thickness, D1 (in)3.0 Granular Base Course Thickness, D2 (in)6.0 Granular Sub-Base Course Thickness, D3 (in)21.0 Calculated Structural Number, CSN 3.69 (Manipulate layer thicknesses such that CSN matches or exceeds RSN.) Pavement Section Design: Page 1 of 1 Explanation of Design Input Parameters: Page 1 of 3 PAVEMENT SECTION DESIGN (EXPLANATION OF DESIGN INPUT PARAMETERS) Design Life (yr): 20 ESALs (total): Parking Lots – 100,000 Local Streets - 400,000 Subgrade CBR, (%): 2.50 Subgrade Resilient Modulus, MR (psi): 3,750 Reliability, R (%): 90 Standard Normal Deviate, ZR: -1.282 Overall Standard Deviation, So: 0.45 Initial Serviceability, po: 4.2 Terminal Serviceability, pt: 2.0 Design Serviceability Loss, (PSI) 2.2 Asphalt Concrete Layer Coefficient, a1: 0.41 Base Course Layer Structural Coefficient, a2: 0.14 Base Course Layer Drainage Coefficient, m2: 0.90 Sub-Base Course Layer Structural Coefficient, a3: 0.09 Sub-Base Course Layer Drainage Coefficient, m3: 0.90 Design Life: A design life of 20 years is typical for new asphalt projects in Bozeman. ESALs (total): According to Table 18.12 in Reference 1, the estimated design Equivalent 18,000-lb Single Axle Load (ESAL) value for roadways subjected to light vehicle and medium truck traffic ranges from 10,000 to 1,000,000. Since we do not anticipate much for truck traffic in the new parking lot, we believe a value of 100,000 is a reasonable assumption for the anticipated ESAL loading for parking lots. Light passenger cars, vans, and pick-up trucks will be the primary users of the new lot. These are classified as Class 1, 2, and 3 vehicles and have an equivalent ESAL value ranging from 0.001 to 0.007 per trip. Using 0.005 ESALS per trip as a conservative average, this calculates to about 3,000 vehicle trips per day for the next 20 years to get close to the ESAL loading design value. With respect to local streets, we have conservatively assumed an ESAL value of 400,000, equivalent to about 11,000 vehicle trips per day. Subgrade CBR: In our experience, CBR values for fine-grained soils often range from 2.0 to 3.0%. For this reason, we picked a CBR value of 2.5% for design purposes. Subgrade Resilient Modulus: For fine-grained soils with a CBR of 10.0 or less, an Explanation of Design Input Parameters: Page 2 of 3 accepted correlation between CBR and resilient modulus is MR = 1500 x CBR. Based on this equation, the design resilient modulus value shall be 3,750 psi. Reliability: According to Table 2.2 in Reference 2, the recommended reliability level for local streets (low volume) in urban settings ranges from 50 to 80 percent; while collector streets (high volume) should be designed with a level of reliability between 80 and 95 percent. We chose an elevated design reliability level of 90 percent. Standard Normal Deviate: According to Table 4.1 in Reference 2, a 90 percent reliability value corresponds to a standard normal deviate of –1.282. Overall Standard Deviation: According to Sections 2.1.3 and 4.3 in Reference 2, a design value of 0.45 is recommended for flexible pavements. Initial Serviceability: According to Section 2.2.1 in Reference 2, a design value of 4.2 is recommended for flexible pavements. Terminal Serviceability: According to Section 2.2.1 in Reference 2, a design value of 2.0 is suggested for roads that will be subjected to small traffic volumes; while a value of 2.5 or higher should be used when designing major highways. We selected a terminal serviceability of 2.0. Design Serviceability Loss: This is the difference between the initial and terminal serviceability. Therefore, the design value shall be 2.2. Asphalt Concrete Layer Coefficient: According to the table with the revised surfacing structural coefficients in Reference 4, a design value of 0.41 is recommended for all asphalt plant mix grades. This value replaces the 0.33 asphalt coefficient that was provided in Table 3-2 of Reference 3. Base Course Layer Structural Coefficient: According to the table with the revised surfacing structural coefficients in Reference 4, a design value of 0.14 is recommended for new 1.5”-minus, crushed base course gravel. This value replaces the 0.12 crushed gravel coefficient that was provided in Table 3-2 of Reference 3. Base Course Layer Drainage Coefficient: According to Table 2.4 in Reference 2, a coefficient of 0.80 to 1.00 should be used when fair to good drainage is anticipated within the pavement structure. We assume good drainage for this project with a corresponding drainage coefficient of 0.90 for design. Sub-Base Course Layer Structural Coefficient: For Pavement Section Design, we are assuming that imported, uncrushed sandy (pitrun) gravel will be placed for the sub-base section of the parking lot. This is the standard product used in the Bozeman area for sub-base. According to pavement design charts for gravelly soils, we estimated that Explanation of Design Input Parameters: Page 3 of 3 pitrun will have a CBR of between 15.0 and 20.0%, which correlates to a structural coefficient of 0.09. Sub-Base Course Layer Drainage Coefficient: The drainage coefficients for sub-base and base course layers are typically the same; therefore, we selected a value of 0.90 for the design. See the base course layer drainage coefficient section for an explanation. Reference List 1) Traffic and Highway Engineering; Nicholas J. Garber and Lester A. Hoel; 1988. 2) Design of Pavement Structures; AASHTO; 1993. 3) Pavement Design Manual; Montana Department of Transportation; 1991. 4) Pavement Design Memo; Montana Department of Transportation; May 11, 2006. 5) Geotechnical Manual; Montana Department of Transportation; July 2008. APPENDIX D LLiimmiittaattiioonnss ooff YYoouurr GGeeootteecchhnniiccaall RReeppoorrtt LIMITATIONS OF YOUR GEOTECHNICAL REPORT GEOTECHNICAL REPORTS ARE PROJECT AND CLIENT SPECIFIC Geotechnical investigations, analyses, and recommendations are project and client specific. Each project and each client have individual criterion for risk, purpose, and cost of evaluation that are considered in the development of scope of geotechnical investigations, analyses and recommendations. For example, slight changes to building types or use may alter the applicability of a particular foundation type, as can a particular client’s aversion or acceptance of risk. Also, additional risk is often created by scope‐of service limitations imposed by the client and a report prepared for a particular client (say a construction contractor) may not be applicable or adequate for another client (say an architect, owner, or developer for example), and vice‐versa. No one should apply a geotechnical report for any purpose other than that originally contemplated without first conferring with the consulting geotechnical engineer. Geotechnical reports should be made available to contractors and professionals for information on factual data only and not as a warranty of subsurface conditions, such as those interpreted in the exploration logs and discussed in the report. GEOTECHNICAL CONDITIONS CAN CHANGE Geotechnical conditions may be affected as a result of natural processes or human activity. Geotechnical reports are based on conditions that existed at the time of subsurface exploration. Construction operations such as cuts, fills, or drains in the vicinity of the site and natural events such as floods, earthquakes, or groundwater fluctuations may affect subsurface conditions and, thus, the continuing adequacy of a geotechnical report. GEOTECHNICAL ENGINEERING IS NOT AN EXACT SCIENCE The site exploration and sampling process interprets subsurface conditions using drill action, soil sampling, resistance to excavation, and other subjective observations at discrete points on the surface and in the subsurface. The data is then interpreted by the engineer, who applies professional judgment to render an opinion about over‐all subsurface conditions. Actual conditions in areas not sampled or observed may differ from those predicted in your report. Retaining your consultant to advise you during the design process, review plans and specifications, and then to observe subsurface construction operations can minimize the risks associated with the uncertainties associated with such interpretations. The conclusions described in your geotechnical report are preliminary because they must be based on the assumption that conditions revealed through selective exploration and sampling are indicative of actual Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 2 conditions throughout a site. A more complete view of subsurface conditions is often revealed during earthwork; therefore, you should retain your consultant to observe earthwork to confirm conditions and/or to provide revised recommendations if necessary. Allied Engineering cannot assume responsibility or liability for the adequacy of the report’s recommendations if another party is retained to observe construction. EXPLORATIONS LOGS SHOULD NOT BE SEPARATED FROM THE REPORT Final explorations logs developed by the consultant are based upon interpretation of field logs (assembled by site personnel), field test results, and laboratory and/or office evaluation of field samples and data. Only final exploration logs and data are customarily included in geotechnical reports. These final logs should not be redrawn for inclusion in Architectural or other design drawings, because drafters may commit errors or omissions in the transfer process. To reduce the likelihood of exploration log misinterpretation, contractors should be given ready access to the complete geotechnical report and should be advised of its limitations and purpose. While a contractor may gain important knowledge from a report prepared for another party, the contractor should discuss the report with Allied Engineering and perform the additional or alternative work believed necessary to obtain the data specifically appropriate for construction cost estimating purposes. OWNERSHIP OF RISK AND STANDARD OF CARE Because geotechnical engineering is much less exact than other design disciplines, there is more risk associated with geotechnical parameters than with most other design issues. Given the hidden and variable character of natural soils and geologic hazards, this risk is impossible to eliminate with any amount of study and exploration. Appropriate geotechnical exploration, analysis, and recommendations can identify and reduce these risks. However, assuming an appropriate geotechnical evaluation, the remaining risk of unknown soil conditions and other geo‐hazards typically belongs to the owner of a project unless specifically transferred to another party such as a contractor, insurance company, or engineer. The geotechnical engineer’s duty is to provide professional services in accordance with their stated scope and consistent with the standard of practice at the present time and in the subject geographic area. It is not to provide insurance against geo‐hazards or unanticipated soil conditions. The conclusions and recommendations expressed in this report are opinions based our professional judgment and the project parameters as relayed by the client. The conclusions and recommendations assume that site conditions are not substantially different than those exposed by the explorations. If during construction, subsurface conditions different from those encountered in the explorations are observed or appear to be present, Allied Engineering should be advised at once such that we may review those conditions and reconsider our recommendations where necessary. RETENTION OF SOIL SAMPLES Allied Engineering will typically retain soil samples for one month after issuing the geotechnical report. If you would like to hold the samples for a longer period of time, you should make specific arrangements to have the samples held longer or arrange to take charge of the samples yourself.