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HomeMy WebLinkAbout12 Evergoods Geotechnical Report January 22, 2025 Doug Minarik Minarik Architecture, Inc. 618 N. Wallace Ave. Bozeman, MT 59715 e-mail: doug@minarikarch.com (Sent via email only) jack@evergoods.us Re: Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Commerce Sub. – Bozeman, MT Dear Mr. Minarik: This letter and attachments comprise our final geotechnical report for the proposed Evergoods project, which will be constructed on Lot 2A, Block 1 of the Glen Lake Commerce Subdivision on the northeast side of Bozeman, MT. This project site is located along the west side of Manley Road and across the street from the Mesa Moving and Storage facility. The new site development will include a two-story commercial building that is underlain by an at-grade slab (slab-on-grade) and surrounded on its west and south sides by a small, asphalt parking lot area. The content and geotechnical recommendations in this report are based on our understanding of the project, investigation of the project area’s subsurface conditions (via 10 test pits that were dug back on February 13, 2003 and May 9, 2018), and our previous geotechnical experience on other commercial building projects in Bozeman. The purpose of the report is to summarize the site’s soil and groundwater conditions; identify any geotechnical issues that either exist or we foresee; and present geotechnical- related recommendations for planning, design, and construction. This report should be reviewed and used by the Design Team, General Contractor, and the Site/Earthwork Contractors. • Note: In 2003, AESI dug seven test pits and prepared a geotechnical report for the property that was subdivided/developed into the Glen Lake Commerce Subdivision. At that time, the property was being considered for a new City of Bozeman solid waste transfer station project. The seven test pit logs from this earlier work are included as part of this report, which updates and builds upon our 2003 geotechnical report and provides specific recommendations for Lot 2A. • Note: In May 2018, AESI dug three additional test pits in the project area (along the west side of Manley Road) as part of our geotechnical investigation for the Manley Road improvements. The test pit logs and test pit photos from this earlier work are also included as part of this report. Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 2 • Note: In May 2018, Iron Horse Road, which is the city street within the Glen Lake Commerce Subdivision, was constructed. AESI was retained to observe/inspect the roadway’s subgrade soil conditions (which consisted of shallow, native sandy gravel). A few subgrade photos from the road construction are included as part of this report. • Note: No current test pits were conducted on Lot 2A during the preparation of this geotechnical report. Due to all of our existing 2003 and 2018 soils information from the project area, which includes six test pits that were dug on or very near Lot 2A, we do not believe that additional test pits are warranted for this project. • Note: During our 2003 test pits, which were dug across an undeveloped piece of property, the Lot 2A area was found to be blanketed by about a 6 to 9-inch thick layer of gravelly fill material (ie. random surface fill) that overlies a buried layer of native topsoil. There is a possibility that during the development of Glen Lake Commerce Subdivision (in 2018) that some additional fill material was spread on Lot 2A. Therefore, the thickness of surface fill may be thicker than what is shown in this report. If this is found to be the case, we do not expect it will be significantly different, since the site terrain generally appears to be unchanged from the 2003 work. UNDERSTANDING OF SUBSURFACE CONDITIONS Test pit logs and photos are attached to this report for reference. However, trying to review 10 test pit logs and relate them to a map showing the test pit locations can be time consuming and difficult to do. For this report, we have prepared five figures that illustrate and summarize the site conditions across the entire Glen Lake Commerce Subdivision area. We recommend these attached figures be reviewed since they show an easy-to-understand, “snapshot view”. A description of the figures is as follows: • Figure 1 – Test Pit Locations: This figure shows the Lot 2A project site and the approximate locations of the 10 test pits. Pits 1 through 7 were dug in 2003; while pits A through C were dug in 2018. The base map for all five figures is an OnXmaps aerial photo of the project area. • Figure 2 – Test Pit Locations w/ Thickness of Native Topsoil (Incl. Any Surface Fill): This figure shows the thickness of native topsoil (including any surface fill material) at each of the test pit locations. In most test pits, the ground surface is covered by a 6 to 9-inch layer of surface fill that in turn overlies a 3 to 12-inch layer of buried, native topsoil (depending on the location). • Figure 3 – Test Pit Locations w/ Thickness of Native Silt/Clay (Under Topsoil Layer): This figure shows the thickness of native silt/clay (underlying the buried topsoil layer) at each of the test pit locations. In most areas, the silt/clay thickness ranges from 0.5 to 1.0 feet, but it was found to have a “top-end” thickness of 1.5 feet in TP-B (which lies adjacent to Lot 2A). • Figure 4 – Test Pit Locations w/ Depth to Native Sandy Gravel (“Target” Bearing Material): This figure shows the depth to top of native sandy gravel (“target” bearing material) at each of the Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 3 test pit locations. In most areas, the depth to native gravel ranges from 1.5 to 2.5 feet; with the deepest gravel being found in TP-B at 3.2 feet. It should be noted that the upper 6 to 9 inches of native gravel is often a little more of a smaller, silty, sandy gravel, which transitions to “cleaner” gravel with depth. Ideally, the “target” foundation bearing material for all perimeter, interior, and exterior footings is the “cleaner” gravel. • Figure 5 – Test Pit Locations w/ Depth to Groundwater on 2/13/03: This figure shows the depth to groundwater on 2/13/03 (during test pit exploration) at each of the test pit locations. Depth to groundwater ranged from 10 feet to > 15 feet (depending on location). In the area of Lot 2A, the water level was > 12 feet. UNDERSTANDING OF FOUNDATION RECOMMENDATIONS The two main foundation recommendations include: 1) Support all footings directly on native gravel or on granular structural fill that in turn bears on the “target” gravel; and 2) Support the interior slab on a minimum 18-inch gravel section consisting of 6 inches of crushed rock underlain by 12 inches of granular structural fill. Two foundation details (ie. Figures 6 and 7) are provided that illustrate the site conditions and our recommendations. Figure 6 presents Option 1, which entails supporting the interior slab on the minimum gravel section and excavating (over-excavating as necessary) all perimeter/exterior/interior footings down to footing grade and to reach “target” gravel. In contrast, Figure 7 shows Option 2, which consists of mass over-excavating the entire building slab area to “target” gravel and excavating (over- excavating as necessary) all perimeter/exterior footings down to footing grade and to reach “target” gravel. Due to shallow gravel depths, most perimeter footings should bear in or very near the “target” gravel; meaning there should not be much need for footing over-excavation/replacement. In contrast, the interior footings (under slab) will likely require more/deeper over-excavation/replacement in order to reach “target” gravel. The excavation choice (by the Contractor) between Options 1 and 2 (ie. trench excavation of interior footings vs. mass excavation of building footprint) will likely be dictated by the locations, spacing, and concentration of interior footings. SITE LOCATION AND EXISTING CONDITIONS Lot 2A is a 1.06-acre property located in the southern half of the Glen Lake Commerce Subdivision. It is bounded by Manley Road (on the east), by Iron Horse Road (on the west), by Lot 1 (on the south), and by Lot 5 (on the north). The site terrain is relatively flat-lying that slopes to the north at about a 1.0 to 2.0 percent grade. Nearby businesses include Mesa Moving and Storage and Map Brewing. To date, all lots in the subdivision remain undeveloped, except for one. See Figures 1 through 5 for a site map that shows an aerial image of the project area. PROJECT UNDERSTANDING Provided below (on the following page) is our understanding of the site development project and what it will include (based on review of Architectural concept plans): Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 4 • The building will be located on the north/northeast side of the lot. • It will be a two-story, commercial building that is underlain by an at-grade slab (slab-on-grade) and supported on a conventional shallow foundation (consisting of perimeter footings/frost walls and interior footings). • No basement or crawl space areas are being planned under the building. • Site utilities will include water, fire, and sewer services that connect to City of Bozeman water and sewer mains within Iron Horse Road as well as on-site stormwater drainage improvements (piping and infrastructure). • Most likely, the project will include an underground stormwater system for stormwater disposal and detention. • Site concrete areas will include sidewalks, building entryways, and exterior patio spaces. • Asphalt parking lots will border the west and south sides of the building with two driveway approaches to Iron Horse Road. The site will not be accessed directly from Manley Road (on the east). Due to the nature of the commercial business, the parking lot will predominately be used by light vehicles with truck traffic being limited to weekly garbage truck service. SUMMARY OF SITE CONDITIONS Provided below is a quick summary of the site conditions. More detail is provided later in the report. • In 2003, the Lot 2A area was blanketed by about a 1.5-foot thick section of “random surface fill material overlying a buried topsoil layer”. The surface fill is gravelly with intermixed silt/clay and ranges from 6 to 9 inches thick; while the underlying topsoil is black/organic and ranges from about 6 to 12 inches. Due to the subdivision development/construction in 2018, there may be a little more fill thickness on the lot now than what was observed in 2003. • Underlying the buried topsoil layer is a 0.5 to 1.5-foot layer of native silt/clay (depending on the location). These soils are dark brown to brown, stiff to very stiff, and slightly moist to moist. • Beginning at depths of 1.5 to 2.5 feet (in most areas) and as deep as 3.2 feet (in TP-B) is the native sandy gravel with cobbles. These gravel materials extended to the bottom of all test pits at depths of 12 to 15 feet. In general, the uppermost 6 to 9 inches of the native gravel is a little more of a silty, sandy gravel (“dirtier gravel) with smaller gravels. Below this depth, the gravels transition to “cleaner” gravels with larger cobbles. • In February 2003, the groundwater depth was > 12 feet (in the area near Lot 2A). Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 5 SUMMARY OF RECOMMENDATIONS Provided below is a quick summary of the geotechnical recommendations. More detail is provided later in the report. • The native sandy gravel beginning at depths of 1.5 to 2.5 feet (in most areas) is the “target” bearing material for foundation support. Ideally, all footings should bear on the “cleaner” gravel that begins about 6 to 9 inches below the top of the gravel. • All building footings (including perimeter, interior, and exterior footings) must bear on “target” sandy gravel or on granular structural fill that in turn bears on “target” gravel. Based on gravel bearing conditions, the design soils bearing pressure for foundation design is 2,500 psf. • The interior slab shall be underlain by a minimum 18-inch section of crushed rock and granular structural fill. Depending on topsoil stripping depths (relative to bottom of slab grade), more than 18 inches of gravel may be needed. • All structural fill under footings, slabs and for interior wall backfill shall be imported gravel. We do also recommend that exterior wall backfill under slabs consist of imported or on-site gravel (to minimize any frost heaving potential). • We recommend the interior slab be underlain by a 15-mil vapor barrier for moisture protection. If required by the IBC, perimeter foundation walls shall be damp-proofed. Due to the at-grade slab foundation configuration, no perimeter footing drains are necessary. • Exterior concrete slabs for sidewalks, building entryways, and patios shall be 4 inches thick (min.) and supported on 6 to 12 inches of crushed rock (depending on the slab location relative to the building foundation). Concrete areas away from building shall be underlain by 6 inches (min.) of crushed rock; while those adjacent to the building shall be underlain by 12 inches (min.) of crushed rock. A greater thickness of crushed rock will further reduce frost heaving. • Exterior concrete slabs for driveway approaches shall be 6 inches thick (min.) and supported on an 18-inch gravel section consisting of crushed rock (6 inches) and sub-base gravel (12 inches). • We recommend a light-duty, pavement section for the asphalt parking lot. This is our standard section for commercial/office-type projects. Provided below is the design pavement section: o 3” Asphalt o 6” Base Course Gravel (1.5”-minus) o 15” Sub-Base Course Gravel (6”-minus) – New or Salvaged Gravel o 8 oz. Non-Woven Geotextile Fabric (Not necessary for “clean” gravel subgrade) o Stable subgrade (dry/hard/compaced) 24” Total Section Thickness Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 6 DESIGN CONSIDERATIONS Provided below are some design considerations for the project: • Geotechnical Report included in Bid Documents: This geotechnical report should be included in the bidding documents and made part of the project specifications. All bidding contractors need to be informed of the site conditions and geotechnical recommendations. • Polyethylene Encasement of DIP Fire Service: The building’s water service line will most likely be copper; while the fire service will be ductile iron pipe (DIP) per Bozeman design standards. For conservancy, we recommend that DIP fire lines be wrapped with V-bio enhanced, polyethylene encasement (for added corrision protection). • Hydraulic Connection of Stormwater System to Native Gravel: We recommend that the under- ground stormwater system(s) be designed/sized for a gravel infiltration rate of 4.0 inches/hour (per Circular DEQ-8). By doing so, the system footprint will be smaller (as opposed to using a much slower silt/clay rate). This will require the system be hydraulically connected to the native sandy gravel. This can be accomplished by bearing the system directly in/on native gravels or by over-excavating under the system as needed (down to native gravel) and placing free-draining gravel/rock/cobble material (back up to system grade). The Civil Plans should clearly state that the system needs to drain into native gravels. CONSTRUCTION CONSIDERATIONS Provided below are some construction considerations for the project: • Footing Excavation vs. Mass Excavation: All footings need to bear on either native gravel or on granular structural fill that in turn bears on “target” gravel. We expect all perimeter footings will be trench excavated (and over-excavated as necessary to reach “target” gravel). The main choice (by the Contractor) will be how to excavate interior footings. Two options are provided. Option 1 consists of individual over-excavation of interior footings (down to “target” gravel); while Option 2 consists of mass over-excavation of the slab area (down to “target” gravel). The number and spacing of interior footings will likely drive the excavation decision. • Over-Excavation of Sand Seams at Footing Grade: In some areas, the native gravels will likely contain some interbedded, thin seams of sand. If during foundation excavation there are sandy areas within the “target” gravel surface at footing grade, we recommend these areas/pockets of loose sand be removed/replaced down to more gravelly material. • Salvaging/Re-Use of Native Gravel: Due to the site’s shallow gravels, foundation excavation may generate some native gravel. Provided the gravel is “clean” and not contaminated with silt/clay, it can be salvaged/re-used for exterior wall backfill and sub-base gravel under pavements. Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 7 • Use of 1”-Minus Clean Crushed Rock for Plumbing Trench Backfill under Slabs: We have found that the use of 1”-minus, clean crushed rock works great for backfill of plumbing trenches under slabs. This material is easy to place and vibratory compact with small, walk-behind equipment (plate compactors). We recommend using crushed rock for all sub-slab trench backfill material. EXPLORATIONS, TESTING, AND SUBSURFACE CONDITIONS Subsurface Explorations Subsurface conditions were investigated across the Glen Lake Commerce Subdivision area by Lee Evans, a professional geotechnical engineer with Allied Engineering, on February 13, 2003. At the time, this site was being considered by the City of Bozeman for a new solid waste transfer station. Seven test pits were dug as part of this work and identified as TP-1 through TP-7. All pits extended to depths of 12 to 15 feet. In May 2018, AESI dug test pits along Manley Road as part of the geotechnical investigation for the road improvements project. Three of the pits, which extended to depths of 3 to 6 feet, were located adjacent to the subdivision area. These were identified as TP-A through TP-C. See Figures 1 through 5 for site maps that show the approximate test pit locations. • Note: The test pits located on or near Lot 2A include TP-5 through TP-7 and TP-A through TP-C. • Note: In addition to the test pits, AESI was also involved during the construction of Iron Horse Road in 2018. We inspected the subgrade conditions, which consisted of clean, cobbly sandy gravel beginning at shallow depths. Five construction photos are attached. During the explorations, soil and groundwater conditions were visually characterized, measured, and logged. The relative density of the soils was estimated based on pocket penetrometer measurements, ease/difficulty of digging, and the sidewall stability of the test pit excavations. Test pit logs are attached. Each log provides an array of field information, such as soil depths, thicknesses, and descriptions, groundwater depth measurements (at the time of exploration), relative density data, soil sample information, and a sketch of the soil stratigraphy. Please be aware that the detail provided on the logs cannot be accurately summarized in a paragraph; thus, it is important to review the logs in conjunction with the report. Following completion of the fieldwork, the excavations were backfilled, staked with identifying lath, and cleaned up to the best extent possible. To better illustrate the on-site soil conditions, a few test pit photos from our 2018 Manley Road test pits are attached. The photos show the excavation sidewalls and soil piles. The purpose of the photos is to clearly illustrate the soil stratigraphy (ie. surface fill overlying topsoil overlying silt/clay overlying sandy gravel) and the “target” sandy gravel (in sidewall and upon excavation). All photos have been marked up to call out the soil layers and materials that are described on the logs. • Note: Please be aware that compaction of test pit backfill soils was not done; therefore, these areas could be susceptible to future settlement. As discussed in a later section of the report, all Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 8 old test pit locations (that are found to be soft/loose) should be re-excavated to their original depth and properly backfilled/compacted if they underlie any of the building site improvements, including foundation footprints, exterior slabs, and asphalt pavement areas. Laboratory Testing In 2003, several soil samples were collected and tested for natural moisture content, gradation, and atterberg limits. See the test pit logs for all available lab testing data. Soil Conditions The best way to fully comprehend the site’s soil conditions is to review the test pit location maps (Figures 1 through 5) in conjunction with the test pit logs/photos. The purpose of the figures is to give a “snapshot” of the conditions that were found in each test pit, including thickness of native topsoil (including any random surface fill), thickness of native silt/clay (under the topsoil layer), depth to native sandy gravel (“target” bearing material), and depth to groundwater on February 13, 2003. As discussed throughout the first half of the report, the Lot 2A area was found to be blanketed by about 6 to 9 inches of random surface fill in 2003. This material was generally “dirty” sandy gravel with areas of intermixed silt/clay. • Note: Due to the 2018 development/construction of Glen Lake Commerce Subdivision, there is a chance that more random surface fill has been spread on the lot area since the test pits were dug in 2003. Therefore, the thickness of fill may be found to be thicker than 6 to 9 inches. If this is the case, the depth to bottom of native topsoil and the depth to top of native sandy gravel will both be greater than what is presented herein. With that said, the site terrain of Lot 2A does look very similar to the 2003 conditions; thus, if more fill was spread, it’s likely not overly thick. Underlying the random surface fill is a 6 to 12-inch layer of buried, native topsoil, which in turn overlies a 0.5 to 1.5-foot layer of native silt/clay. The topsoil is black; while the silt/clay is dark brown to brown, stiff to very stiff, and slightly moist to moist. Beginning at a depth of 1.5 to 2.5 feet (in most areas) and as deep as 3.2 feet on the east side of Lot 2A (in TP-B) is the top of the native sandy gravel. The gravel materials extended to the bottom of all test pits at depths of 12 to 15 feet. In general, the upper 6 to 9 inches of the native gravel is a little more of a silty, sandy gravel (“dirtier” gravel) with smaller gravels. Below this depth, the sandy gravel is “cleaner” and contains larger gravels and cobbles. Provided in Tables 1 and 2 (on the following page) are quick summaries of the soil conditions observed in TP-1 through TP-7 (from the 2003 geotechnical investigation of the subdivision area/property) and in TP-A through TP-C (from the 2018 geotechnical investigation for the 2020 Manley Road improvements project). This terminology matches the attached test pit logs. Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 9 Table 1. Summary of Soil Conditions in TP-1 through TP-7 – Subdivision Area TP # RANDOM SURFACE FILL NATIVE TOPSOIL (BURIED LAYER) NATIVE SILT/CLAY NATIVE SANDY GRAVEL 1 0.0’ - 0.8’ 0.8’ - 1.7’ 1.7’ - 2.3’ 2.3’ - 13.0’ 2 0.0’ - 0.5’ 0.5’ - 0.8’ 0.8’ - 1.6’ 1.6’ - 13.0’ 3 -------- 0.0’ - 0.5’ 0.5’ - 1.5’ 1.5’ - 15.0’ 4 0.0’ - 0.8’ 0.8’ - 1.4’ 1.4’ - 2.0’ 2.0’ - 15.0’ 5 0.0’ - 0.5’ 0.5’ - 1.3’ 1.3’ - 2.3’ 2.3’ - 14.0’ 6 0.0’ - 0.7’ 0.7’ - 1.3’ 1.3’ - 2.3’ 2.3’ - 12.0’ 7 0.0’ - 0.5’ 0.5’ - 1.5’ -------- 1.5’ - 12.0’ Notes: 1) All soil measurements are depths below existing ground. 2) The closest test pits to Lot 2A include TP-5, TP-6, and TP-7. Table 2. Summary of Soil Conditions in TP-A through TP-C – Manley Road Corridor TP # ASPHALT (MANLEY RD) GRAVEL SECTION (MANLEY RD) RANDOM SURFACE FILL NATIVE TOPSOIL (BURIED LAYER) NATIVE SILT/CLAY NATIVE SANDY GRAVEL A -------- -------- 0.0’ - 1.0’ 1.0’ - 1.5’ 1.5’ - 2.5’ 2.5’ - 6.0’ B 0.0’ - 0.2’ 0.2’ - 1.8’ -------- -------- 1.8’ - 3.2’ 3.2’ - 3.5’ C -------- -------- 0.0’ - 0.4’ 0.4’ - 1.0’ 1.0’ - 2.0’ 2.0’ - 6.0’ Notes: 1) All soil measurements are depths below existing ground. 2) All three test pits lie on the southeast, east, and northeast sides of Lot 2A. Groundwater Conditions Groundwater depths are expected to be at 10 feet (or greater) throughout the year in the Lot 2A area. During our test pits on February 13, 2003, no groundwater was observed in the two, on-site test pits (TP-5 and TP-7) or the two, nearby test pits (TP-4 and TP-6), all of which extended to 12 to 15 feet. The shallowest groundwater was found on the west side of the subdivision area (next to railroad) at 10 feet. GEOTECHNICAL ISSUES The site conditions do not present any foreseeable geotechnical issues for the proposed project. The shallow gravels will provide “target” foundation bearing; the building will not have a basement, which negates high groundwater as a possible concern; and the silt/clay is stiff/slightly moist and will provide suitable subgrade support for interior/exterior slabs and asphalt pavements. Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 10 GENERAL CONSTRUCTION RECOMMENDATIONS Re-Excavation of Test Pits Some of the old test pits will be encroached upon during site work, foundation earthwork, and asphalt area construction. During backfilling of the pits, the spoils were not compacted. As a result, they may undergo some soil settlement over time. It is standard practice to address any soft test pit backfill areas during construction (if they are found). As a general rule, where any of site and building improvements, including foundations, interior/exterior concrete slabs, underground utilities, and asphalt pavement areas, will overlie any of the old test pits (especially those that are soft/loose), we recommend they be re-excavated down to their original depth and properly backfilled/compacted with suitable material using suitable means/methods. The two, 2003 test pits on Lot 2A were dug to depths of 12 to 14 feet. Topsoil Stripping and Re-Use All native topsoil (and old surface fill) must be completely removed from within the building foundation footprint areas and from under all exterior concrete slab and asphalt pavement areas. Final site grading (in landscape areas) and the reclamation of disturbed construction areas are the only recommended uses for organic topsoil or organic-laden materials. • Note: The Lot 2A area is blanketed by a minimum of 6 to 9 inches of gravelly, random fill that in turn overlies a 6 to 12-inch layer of buried native topsoil. Due to recent construction activity, there may be more random fill on the site now as compared to 2003. Groundwater Dewatering Due to deep groundwater conditions, groundwater dewatering should not be needed. Silt/Clay Subgrade Conditions Once the buried topsoil layer is stripped from under the building, under exterior concrete areas, and from under parking lots, the subgrade soils will consist of native, dark brown to brown, silt/clay. Based on the test pits, these soils should be in a slightly moist to moist and stiff to very stiff condition. As a result, we do not expect any subgrade challenges (ie. overly moist or soft soils). We anticipate stable subgrade will exist or can be easily achieved with air drying (once the subgrade surface is exposed). Salvaging and Re-Use of On-Site Gravels Due to the site’s shallow gravel conditions, there may be an opportunity to generate and salvage some on-site gravel during foundation excavation and parking lot earthwork. As long as the on-site gravels are “clean” and not contaminated with silt/clay, they can be re-used for exterior foundation wall backfill (under exterior slabs) and/or for the sub-base component of the asphalt pavement section. Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 11 Areas Where New Gravel Will Be Required • All granular structural fill under footings and interior slabs shall consist of new gravel (either 3”- minus gravel or 1.5”-minus gravel). A commercially-processed gravel material will be more uniform and compact better. • We recommend that interior foundation wall backfill under interior slabs consist of new gravel (either 3”-minus gravel, 1.5”-minus gravel, or 1”-minus crushed rock). Here again, it will be important to use a small aggregate size material that is easy to compact with small equipment. • All base course gravel under asphalt pavements shall be new gravel (1.5”-minus gravel). • Assuming not much quantity of on-site “clean” gravel can be stripped, salvaged, and re-used from the site work, then most, if not all, of the sub-base course gravel under asphalt pavements will need to be new gravel (6”-minus gravel). STRUCTURAL DESIGN PARAMETERS Foundation Design The building will be underlain by an at-grade slab (slab-on-grade) and supported on a conventional shallow foundation consisting of perimeter strip footings/frost walls and interior strip/spread footings (under the slab). Seismic Design Factors A main requirement of the Structural Engineer’s seismic analysis will be a determination of the site class. Based on our on-site explorations and knowledge of the underlying geology, the site class for the project site will be Site Class D (as per criteria presented in the 2021 IBC). This site class designation is valid as long as our foundation recommendations are followed. To obtain site-specific seismic loading and response spectrum parameters, a web-based application from the USGS Earthquake Hazards Program can be used. The link to their web page is as follows: https://earthquake.usgs.gov/hazards/designmaps/. Upon entering this page, there are links to three third- party interfaces that can be used to obtain the seismic information. The user needs to enter the design code reference document, site soil classification, risk category, site latitude, and site longitude. Foundation Bearing Pressure (Conventional Foundation) As long as our foundation earthwork recommendations are followed, the allowable bearing pressure for all perimeter, interior, and exterior footings and any other foundation component is 2,500 pounds per square foot (psf). Allowable bearing pressures from transient loading (due to wind or seismic forces) Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 12 may be increased by 50 percent. We estimate that the above-referenced design bearing pressure will result in total foundation settlements of one inch or less, with only minor differential settlements. 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). 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 backfill should be assumed to have an equivalent fluid pressure of 280 pcf; while a coefficient of friction of 0.5 is estimated between cast-in- place concrete and the “target” sandy gravel (or granular structural fill that is placed to build back up to footing grade from the “target” gravel subgrade). 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 above-referenced, equivalent fluid pressures (for at rest, active, and passive conditions) assume that the wall will be backfilled with a suitable material that is compacted to an unyielding condition and it will lie above the groundwater table and/or be well drained; thereby, preventing the backfill from becoming saturated and the wall from experiencing hydrostatic pressure. Each of these design pressures is for static conditions and will need to be factored accordingly to represent seismic loading. We recommend that we be retained to evaluate lateral earth pressures for geometries and/or loading conditions that do not meet the previously mentioned criteria. Subgrade Reaction Modulus (under Slabs) As long as our interior slab support recommendations are followed (as presented later in the report), the subgrade reaction modulus (k) can be assumed to be 200 pounds/cubic inch (pci). This is a modified design value that uses the subgrade reaction modulus (k) of the native silt/cay and factors it (increases it) based on a minimum section thickness of imported gravel to be placed under the slab. This design value assumes the slab will be underlain by at least 18 inches of compacted gravel or crushed rock. • Note: We recommend a minimum 18-inch thick, gravel support section under all interior slabs. Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 13 Interior Slab Thickness We expect that the interior slab thickness will be 4 to 5 inches; and may be reinforced with rebar or wire mesh. The Structural Engineer is designing the slab. Soil Corrosivity to Concrete According to Montana Department of Transportation (MDT) highway design standards, Type I-II cement is used when soil sulfate contents are less than 0.20%. However, if sulfate levels are between 0.20 and 2.00%, then Type V cement is used. • Note: Over the years, we have tested several samples of Bozeman-area silt/clay and sandy gravel. All samples have been non-corrosive to standard concrete. • Note: Based on previous test results of similar soils, the on-site silt/clay and sandy gravel soils will not be corrosive to standard concrete. There is no reason to use Type V cement in the foundation concrete. FOUNDATION RECOMMENDATIONS General Two detailed illustrations showing our excavation/fill/earthwork, foundation bearing, slab support, and moisture protection recommendations for a slab-on-grade (at-grade slab) foundation configuration are included as Figures 6 and 7. Both figures are identical, except for providing different options for the excavation/support of interior footings (under the slab). Please refer to this figure during the review of the report. • Note: Figure 6 shows trench over-excavation/replacement of individual interior footings down to “target” gravel. This is Option 1. The minimum width of over-excavation/structural fill under footings is dependent on the thickness of structural fill. See the criteria/formula on the figure. • Note: Figure 7 shows mass over-excavation/replacement of the entire building slab area down to “target” gravel (which would hence include all interior footings). This is Option 2. Foundation Design • The building foundation will be designed as a conventional foundation that consists of perimeter footings/frost walls and interior footings (under the slab). It will underlain by an at-grade slab. • The minimum depth of cover for frost protection of perimeter and exterior footings is four feet. This dimension is measured from bottom of footing up to the final grade of the ground surface. Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 14 Foundation Support • The “target” foundation bearing material for all perimeter, interior, and exterior footings is the native sandy gravel that underlies the Lot 2A area beginning at depths of 1.5 to 2.5 feet (in most areas) and as a deep as 3.2 feet on the east side (in TP-B). Ideally, the best/preferred bearing material is the “cleaner” sandy gravel with cobbles that underlies the uppermost 6 to 9 inches of silty, sandy gravel (“dirtier” gravel) with smaller gravels. • All footings must bear directly on “target” gravel or on granular structural fill that in turn bears on “target” gravel. Most perimeter frost wall footings are expected to bear in or very near the shallow target” gravel (meaning a possibility for little or no over-excavation/replacement); while the interior footings under the slab will require more/deeper over-excavation/replacement to reach the “target” gravel. • In some areas, the native gravel contains some pockets/seams/veins of loose sand. If footing grade has any of these sandy areas, they should be excavated deeper (down to better gravel) and re-filled with granular structural fill. • The bottom of all perimeter, interior, and exterior footing excavations (or over-excavations) must consist of native, “clean” cobbly, sandy gravel. • To minimize disturbance to the native gravel subgrade surface, the excavation should be dug with a smooth-edge foundation bucket. • Prior to placing granular structural fill or forming footings, the native gravel subgrade surface shall be cleaned of loose spoil materials and re-compacted to a dense and unyielding condition with a smooth drum roller. No compaction testing is required on the gravel subgrade. • All granular structural fill that is placed under footings must consist of either 3”-minus, sandy (pitrun) gravel or 1.5”-minus, crushed (roadmix) gravel. Specifications for these materials are provided in a later section of the report. We recommend new 3”-minus gravel for structural fill. • The granular structural fill section should be placed in multiple lifts (depending on thickness of fill required and the size of the roller used) with each lift being vibratory compacted to a dense and unyielding condition. See a later report section for additional compaction specifications. A large, smooth drum roller should be used wherever possible. Small, walk-behind sheepsfoot rollers and hand-held, jumping jack compactors should be used in narrow/confined excavations and along edges and in corners of the excavation. FOUNDATION WALL BACKFILL RECOMMENDATIONS Provided on next page are general recommendations for interior and exterior foundation wall backfill. Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 15 • For interior foundation wall backfill (under interior slab areas), all backfill material must consist exclusively of either 3”-minus granular structural fill or 1”-minus, clean crushed rock. Both of these materials are easy to compact and will minimize any settlement potential under the slab. All backfill must be placed in thin lifts and be vibratory compacted to a dense and unyielding condition (even the crushed rock). We do not recommend using any on-site silt/clay and sandy gravel soils for any interior backfill. • Select native silt/clay/sand or sandy gravel soils can be used for exterior foundation wall backfill. These materials must be well compacted to prevent unwanted settlements, especially under exterior slab areas. Use only the driest material available. If on-site sandy gravel is used, it should be a 6”-minus material to prevent point loading the foundation walls with large, over- sized, cobbles and boulders. All backfill must be placed in lifts and be well compacted. • Under exterior slab areas (at doorways and under patios), we recommend foundation backfill consist of relatively clean, sandy gravel. By doing so, any frost heaving potential is minimized. INTERIOR SLAB RECOMMENDATIONS All interior building slabs shall be supported on a minimum, 18-inch thick, compacted gravel section consisting of 6 inches of clean crushed rock underlain by 12 inches of granular structural fill that overlies stable and compacted subgrade (ie. non-organic silt/clay with all surface fill and buried topsoil stripped). • Note: Depending on the slab elevation relative to the bottom of the stripped topsoil surface, more than 18 inches of gravel/crushed rock may be needed under the slab area. • Note: Depending on the locations/spacing/concentrations of interior footings, it may be more advantageous and cost effective to mass over-excavate the building slab area down to “target” gravel (thereby removing the 0.5 to 1.5-foot silt/clay layer that underlies the topsoil) and re-fill the excavation with structural fill (as opposed to individually over-excavating interior footings). MOISTURE PROTECTION AND SUBSURFACE DRAINAGE RECOMMENDATIONS Provided below are our foundation moisture protection and subsurface drainage recommendations for the at-grade slab configuration. • The interior slab area shall be underlain by a heavy-duty, 15-mil vapor barrier. The barrier that we recommend is a Stego 15-mil vapor barrier. The barrier must be sealed at all seams, pipe penetrations, and walls. • Unless required by the IBC, damp proofing of foundation walls is not typical for at-grade slabs. • A perimeter footing drain is not needed/required. Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 16 EXTERIOR SLAB RECOMMENDATIONS Provided in Table 3 are our recommendations for the design section under the light-duty, exterior slabs (including standard pedestrian sidewalks away from the building foundation and next to streets). Table 3. Exterior Concrete Slab (Light-Duty) – Sidewalks Away From Building – Stable Subgrade COMPONENT COMPACTED THICKNESS (IN) Concrete Slab: 4 (min.) 1”-Minus Clean Crushed Rock: 6 Granular Structural Fill – 3”-Minus Gravel or 1.5”-Minus Roadmix: No 8 oz. Non-Woven Geotextile Fabric (Mirafi 180N or Equal): No Stable Subgrade Soils (Less Topsoil) or Embankment Fill: Rolled/Compacted TOTAL SECTION THICKNESS: 6 + Slab Thickness Notes: 1) We recommend this section for std. pedestrian sidewalks away from the building foundation and next to streets. 2) We expect pedestrian slabs will be 4 inches thick (min.). 3) The purpose of the 6-inch thick, crushed rock section is to provide better support under the slab. Provided in Table 4 (below and continuing on following page) are our recommendations for the design section under the light-duty, exterior slabs (including pedestrian sidewalks next to building foundation wall, slabs in front of all doorway entries, patios, and garbage enclosure slabs). • Note: In the table below, we recommend a minimum of 12 inches of crushed rock under these slabs. For doorway and patio slabs, a better recommendation to further lower the potential for frost heaving is to increase the gravel section to 24 inches (instead of 12 inches). This 24-inch sub-slab section can consist of 12 to 18 inches of granular structural fill topped by 6 to 12 inches of clean crushed rock. Sidewalk slabs next to foundation walls (but not at doors or patios) and garbage enclosure slabs (under the dumpster) can be underlain by 12 inches of crushed rock. • Note: To remove all frost heaving risk under slabs adjacent to doorways (including patio area slabs), strong consideration should be given to fully backfilling these relatively small areas with either “clean” on-site sandy gravel, granular structural fill, or clean crushed rock from footing grade up to the bottom of slab grade. Table 4. Exterior Concrete Slab (Light-Duty) – Sidewalks Next To Building – Stable Subgrade COMPONENT COMPACTED THICKNESS (IN) Concrete Slab: 4 (min.) 1”-Minus Clean Crushed Rock: 12 (See Below for Recommendations) Granular Structural Fill – 3”-Minus Gravel or 1.5”-Minus Roadmix: No 8 oz. Non-Woven Geotextile Fabric (Mirafi 180N or Equal): No Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 17 Stable Subgrade Soils (Less Topsoil) or Embankment Fill: Rolled/Compacted TOTAL SECTION THICKNESS: 12 + Slab Thickness Notes: 1) We recommend this section for pedestrian sidewalks next to the building, at doorways, and garbage enclosures. 2) We expect pedestrian slabs and garbage enclosure slabs will be 4 inches thick (min.). 3) The purpose of the 12-inch thick, crushed rock section is to lower the frost heaving risk of the underlying silt/clay. 4) For slabs in front of doorways (incl. patios), we recommend the sub-slab gravel section be increased to 24 inches. 5) The purpose of the “expanded” 24-inch gravel section under slabs is to further reduce frost heaving potential. 6) Option 1: The 24-inch gravel section can consist of 6 inches of crushed rock and 18 inches of structural fill. 7) Option 2: The 24-inch gravel section can consist of 12 inches of crushed rock and 12 inches of structural fill. 8) Option 3: The 24-inch gravel section can consist entirely of 24 inches of crushed rock. 9) An option for removing all frost heaving risk next to doors (incl. patios) is to backfill under slabs w/ structural fill. 10) The granular backfill material shall extend from footing grade up to the bottom of the layer of clean crushed rock. 11) In lieu of granular structural fill, the doorway/patio slabs can be fully backfilled with clean crushed rock. Provided in Table 5 are our recommendations for the design section under heavy-duty, exterior slabs for vehicle and truck traffic (including driveway approaches). Table 5. Exterior Concrete Slab (Heavy-Duty) – Vehicle Slabs – Stable Subgrade COMPONENT COMPACTED THICKNESS (IN) Concrete Slab: 6 (min.) 1”-Minus Clean Crushed Rock or 1.5”-Minus Base Course Gravel: 6 Granular Structural Fill (3”-Minus) or Sub-Base Gravel (6”-Minus): 12 8 oz. Non-Woven Geotextile Fabric (Mirafi 180N or Equal): Yes Stable Subgrade Soils (Less Topsoil) or Embankment Fill: Rolled/Compacted TOTAL SECTION THICKNESS: 18 + Slab Thickness Notes: 1) We recommend this section for driveway approaches. 2) We expect driveway approaches will be 6 inches thick (min.); but could be up to 8 inches. 3) The final design of the slab thickness and slab reinforcement will be provided by others. 4) If our recommendation is needed for reinforcement, we recommend #4 rebars at 18” on-center (at a minimum). 5) The purpose of the 18-inch thick, total gravel section is to provide better support under the vehicle slabs. 6) We recommend a 24-inch total section thickness for slabs that will be subjected to vehicle/truck traffic loading. 7) If the slab thickness will be 8 inches instead of 6 inches, then reduce the crushed rock thickness from 6 to 4 inches. SURFACE DRAINAGE RECOMMENDATIONS Final site grading next to the building must establish and promote positive surface water drainage away from the foundation footprint in all directions. Absolutely no water should be allowed to accumulate against or flow along any exposed wall (and thereby soak into the foundation wall backfill). Concrete or asphalt surfacing that abut the foundation should be designed with a minimum grade of two percent; while adjacent landscaped areas should have a slope of at least five percent within ten feet of the wall. Steeper side slopes than five percent (in landscape areas) are encouraged wherever possible. By doing Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 18 this, any minor settlements in the foundation backfill should not negatively affect the positive drainage away from the building. Note: The “dirt grade” in all adjacent backfill and landscape areas must be properly graded away from the foundation walls with positive slopes of five percent (min.) prior to the placement of the landscape bed/covering materials. This also applies to the subgrade surface under adjacent concrete areas (below the gravel/crushed rock section materials). To further reduce the potential for moisture infiltration along foundation walls, backfill materials should be placed in thin lifts and be well compacted, and in landscaped areas, they should be capped by four to six inches of topsoil. With the exception of the locations that will be surfaced by concrete or asphalt, finished grades (next to foundation walls) should be set no less than six inches below the top of the interior concrete slab or below the bottom of the sill plate for framed floor applications. FOUNDATION-RELATED FILL MATERIAL RECOMMENDATIONS Provided below are specifications for the fill materials that are recommended for use during foundation earthwork construction. These include on-site excavated soils, sandy (pitrun) gravel, crushed (road mix) gravel and clean crushed rock. Fill placement/compaction criteria follow the specifications. On-Site Excavated Soils All on-site generated, non-organic silt/clay that has a moisture content conducive to proper compaction can be re-used for exterior foundation wall backfill. If “clean” gravel (not contaminated with silt/clay) can be salvaged, it can be re-used for exterior foundation wall backfill (under doorway and patio slabs) and for the sub-base component of the asphalt pavement section. Sandy (pitrun) Gravel Sandy (pitrun) gravel is a granular structural fill alternative for placement under footings and slabs and behind walls. This material shall be a non-plastic, well-graded, mixture of clean, sand and gravel with 100 percent of its gravels/cobbles passing a three-inch screen and between 2 and 10 percent of its silt/clay particles (by weight) finer than the No. 200 sieve. It should meet all material and gradation specifications as presented in Section 02234 of the Montana Public Works Standard Specifications (MPWSS) for 3”-minus, uncrushed, sub-base course gravel. Crushed (road mix) Gravel Crushed (road mix) gravel is a granular structural fill alternative for placement under footings and slabs and behind 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 rock fragments pass a 1-1/2-inch screen and between 0 and 8 percent of its silt/clay particles (by weight) are finer than the No. 200 sieve. It should Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 19 meet all material and gradation specifications as presented in Section 02235 of the MPWSS for 1-1/2”- minus, 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 be 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 containing 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 readily compacted by vibratory means. In general, the maximum “loose lift thickness” for all fill materials (prior to compaction) should be limited to 12 inches for large, self-propelled rollers, 6 inches for remote-controlled, dual drum rollers and walk-behind, jumping jack compactors, and 4 inches for walk-behind vibratory plate compactors. The moisture content of any material to be compacted should be within approximately two percent (+/-) of its optimum value for maximum compaction. Provided in Table 6 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 6. Compaction Recommendations (Application vs. Percent Compaction) APPLICATION % COMPACTION Granular Structural Fill Under Footings and Slabs: 97 Interior Wall Backfill under Slabs (Granular Structural Fill): 97 Exterior Wall Backfill (Native Soil or Granular Structural Fill): 95 Clean Crushed Rock Under Footings/Slabs and Behind Walls: N/A (Vibration Required) Site Fill Around Building and Under Concrete and Pavement Areas: 95 UNDERGROUND UTILITIES General The underground utilities for this project will include water/fire/sewer services, storm drainage piping and infrastructure, and underslab piping/plumbing. • Note: See the following report section for a discussion on underground stormwater systems. Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 20 Installation The installation of all water, sewer, and storm drainage outside of the building should follow the project plans/specifications, Monana Public Works Standard Specifications, and City of Bozeman Specifications. Pipe Bedding In some areas, the native gravels contain large, 6” to 10” cobbles and boulders. In order to protect the pipes during installation/backfilling (from being damaged or point-loaded by the rocky gravel material), generous amounts of 1”-minus crushed rock pipe bedding material should be used under, around, and over the pipes. Soil Corrosivity Potential and Recommendations for DIP Pipes Based on past experience, the site’s silt/clay and sandy gravel soils are not corrosive to standard ductile iron pipe (DIP). With that said, we do recommend installing the DIP fire service line (into the building and under the building slab) with polyethylene encasement for added corrosion protection. This is considered cheap insurance. Most likely, the water service line will be copper and therefore, does not require any polyethylene encasement. In summary, our recommendations include: • Use standard DIP pipe that is wrapped in V-bio enhanced, polyethylene encasement. • The site conditions do not require the use of special, zinc-coated, DIP pipe. Sub-Slab Plumbing Excavation and Trench Backfill In our opinion, the best material for trench backfill of sub-slab plumbing is 1”-minus, clean crushed rock. This material is easy to place and compact in tight and confined areas. We recommend that the crushed rock be placed in reasonable lifts and be vibratory compacted to a dense and unyielding condition with small, walk-behind, plate compactors. UNDERGROUND STORMWATER SYSTEMS Provided below are recommendations for designing and installing underground stormwater systems: Design Infiltration Rate We recommend designing the system to drain into the underlying native sandy gravels. By doing so, the system footprint area will be much smaller; and the surface water drainage will rapidly drain out of the system. We recommend using Table 3 in Appendix A of Circular DEQ-8 for the design infiltration rate for native sandy gravel. According to the table, an infiltration rate of 4.0 inches per hour can be assumed for sand and gravel. Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 21 Hydraulic Connection Using the above-referenced design infiltration rate for native gravel will require that the system be hydraulically connected to the native gravel. This can be done by bearing the system directly in the native gravel (where the native gravels are shallow); or by over-excavation and replacement under the system (where the native gravels are deeper and below the bottom of system elevation). Excavation and Replacement (If Needed) If needed (based on native gravel depth), we recommend mass over-excavating under the stormwater system down to “clean” sandy gravel. In order to re-fill the excavation area and build back up to the system elevations, we recommend either using clean crushed rock or over-sized cobbles (available from a commercial pit) as the replacement material. Since the cobbles are free-draining, we prefer them over standard 6”-minus pitrun gravel. When using “open-graded” cobbles, the top of the cobbles must be covered with a layer of 8 oz. non-woven geotextile separator fabric (Mirafi 180N or equal) before placing the bedding rock/gravel under the stormwater systems. A detail that shows the over-excavation and replacement material should be included on the civil plans. The civil plans should clearly state that the system must drain into the native gravels and that this may require over-excavation and replacement. ASPHALT PAVEMENT SECTION RECOMMENDATIONS Pavement Section Design Provided in Table 7 is our recommended light-duty pavement section for the parking lot improvements. This section requires stable subgrade and is our standard section for light commercial/office building- type project sites. Table 7. Pavement Section (Light-Duty) – Stable Subgrade COMPONENT COMPACTED THICKNESS (IN) Asphalt Concrete: 3 Base Course – 1.5”-Minus Crushed (Roadmix) Gravel: 6 Sub-Base Course – 6”-Minus Uncrushed Sandy (Pitrun) Gravel: 15 8 oz. Non-Woven Geotextile Fabric (Mirafi 180N or Approved Equal): Yes (for Silt/Clay & “Dirty” Gravel) Stable Subgrade Soils (Less Topsoil): Hard and Compacted TOTAL SECTION THICKNESS: 24 Notes: 1) Base course gravel shall be new gravel. 2) Sub-base gravel can be new gravel or salvaged gravel (provided it is “clean” and not contaminated with silt/clay). 3) For silt/clay and/or “dirty” gravel subgrade, place an 8 oz. non-woven fabric for subgrade separation. 4) The placement of geotextile fabric is not required/not needed where subgrade consists of “clean” sandy gravel. 5) Stable subgrade conditions are required, meaning it must be dry, hard, and compacted. 6) If subgrade soils are overly moist and rut/pump/deflect, they must be dried out to a stable condition. Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 22 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 6-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 the MPWSS, Sections 02234 and 02235. All gravels shall be placed in loose lifts not exceeding 12 inches in thickness and be compacted to at least 95 percent of the material’s maximum dry density as defined in ASTM D-698. Asphalt pavement shall meet specifications in MPWSS Section 02510 and be compacted to a minimum of 93 percent of the Rice mix density. GEOTECHNICAL INSPECTION If desired, AESI can be retained for geotechnical inspection of the foundation excavation. We request that we be given about a week notice and we will need to be involved from the first day of foundation excavation. As part of our work, we will observe the bottom of the excavation (down to “target” native gravel) and the placement/compaction of granular structural fill (up to footing grade). • Note: A City Building Department requirement is that a stamped, geotechnical inspection letter (prepared by a professional engineer) be provided that documents the foundation earthwork prior to scheduling the City’s pre-pour footing inspection. We can provide this; but we will need to be retained for geotechnical inspection services under a separate contract. PRODUCTS Provided in Table 8 is a reference guide for all products that have been recommended within this report. Listed below is the product name, its intended use, and where it can be obtained. The manufacturer specification sheet for each of these products is attached at the end of the report. • Note: Several notes are presented under the table that describe the recommended products, where they can be obtained, and where they can be used. Table 8. Product Reference Guide PRODUCT USE SOURCE PHONE Stego 15-mil Vapor Barrier Moisture Protection under Bldgs MaCon Supply – Bozeman 551-4281 Mirafi 180N Non-Woven Fabric Road Subgrade Separation Multiple Sources – Belgrade N/A Notes: 1) Use Stego 15-mil vapor barrier only. There are no approved equals for this product. 2) Stego 15-mil vapor barrier has a water transmission rate that meets national standards for vapor barriers. 3) Stego 15-mil vapor barrier is a heavy-duty vapor barrier for placement under interior slabs and in crawl spaces. 4) We recommend the placement of a Stego 15-mil vapor barrier under building slabs. 5) Use Mirafi 180N non-woven fabric or an approved equal that meets or exceeds Mirafi 180N fabric specifications. 6) Approved equals for Mirafi 180N non-woven fabric are available from multiple sources in the Belgrade. Final Geotechnical Report – Evergoods Project Lot 2A, Blk 1, Glen Lake Com. Sub. – Bozeman, MT Project: 24-166 January 22, 2025 Page 24 enc: Figure 1 – Test Pit Locations Figure 2 – Test Pit Locations w/ Thickness of Native Topsoil (Incl. Any Surface Fill) Figure 3 – Test Pit Locations w/ Thickness of Native Silt/Clay (Under Topsoil Layer) Figure 4 – Test Pit Locations w/ Depth to Native Sandy Gravel (“Target” Bearing Material) Figure 5 – Test Pit Locations w/ Depth to Groundwater on 2/13/03 Figure 6 – Foundation Detail – At-Grade Slab – Option 1 (Interior Footing Over-Excavation) Figure 7 – Foundation Detail – At-Grade Slab – Option 2 (Building Slab Mass Over-Excavation) Test Pit Logs for TP-1 through TP-7 from 2/13/03 (Glen Lake Commerce Sub. Area) Test Pit Logs for TP-A through TP-C from 5/9/18 (Manley Road Improvements) Test Pit Photos for TP-A through TP-C – Excavation Sidewalls and Spoil Piles Iron Horse Road Construction Photos from 5/2/18 – Native Sandy Gravel Subgrade Product Sheet – Stego 15-mil Vapor Barrier Product Sheet – Mirafi 180N Non-Woven Geotextile Fabric Limitations of your Geotechnical Report REFERENCES International Code Council, 2021, “International Building Code”. Montana Contractors’ Association, April 2021, “Montana Public Works Std. Specifications”, 7th Edition. P:\2024\24-166 Lot 2A, Block 1, Glen Lake Commerce Sub. - Geotech\Design\Geotech\Report\Text\Lot 2A, GLCS - Geotechnical Report - 01.22.25 Figure 6 24-166 Jan. 2025 Lot 2A, Blk 1, Glen Lake Commerce Sub. Foundation Detail - At-Grade Slab - Option 1 Bozeman, Montana Damp-Proofing As Required (typ.) Foundation Wall (typ.)Approved Non-Woven Filter Fabric To Encase Bedding Gravel (typ.) Interior Floor Slab (typ.)Interior Steel Column (typ.)Interior Spread Footing (typ.) 6” Of 3/4" Minus Crushed Washed Gravel Hydraulically Connected To Sub-Drain or Existing Surface Drainage (typ.) Native Topsoil andRandom Surface Fill Imported 4-Inch Minus Sandy Pitrun Gravel Native Silt/ClayImported Flowable Fill Six Inch Diameter Sub-Drain Pipe (Graded To Drain To Sump Area) Concrete SidewalkLow Permeability Soils(Landscaped Area)LegendConcrete Wall and/or Footing Low Permeable Topsoil No Scale (Parts Of This Exhibit Have Been Exaggerated For Clarity) ALLIEDENGINEERING SERVICES, INC. Civil Engineering Geotechnical Engineering Land Surveying 32 Discovery Drive Bozeman, MT 59718 Phone: (406) 582-0221 Fax: (406) 582-5770 Slope Away @ 2% In All Concrete Or Pavement Areas (typ.) Footings 6’ max. depth below existing ground Native Topsoil 6” Minus Sandy (Pitrun) Gravel 4” Minus Sandy PitrunGravel (ie. Structural Fill)4’ max fill above existing ground 4' min. 4’ Max Fill Above Existing Ground 3” (min.) Thickness Will Vary Due To Depth Of Bedbrock Strata 6” (min.) 3” (min.) 8” (min.) 4.0’ (min.) 6” (min.) Of Rock Bedding To Be Placed Around Drain Piping (typ.) Under-Slab Rock Layer To Be Hydraulically Connected To Sub-Drain System By 3” Of Rock Or 2” Sch. 80 Piping Spaced On 10’ Centers (typ.) B H (Variable; Depends On Depth To Gravel) 18” (min.) 18” (min.) 6” (min.) 6” (min.) 1’ (min.) H = 3.5’ (Based On4.0’ Footing Depth And The Depth To Gravel In TP-4) H = 5.5’ (Based On4.0’ Footing Depth And The Depth To Gravel In TP-2) D D Woven Geotextile Filter Fabric (Amoco 2004)Vapor Barrier Under Slab (typ.) 9.5’ Deep (TP-2) 7.5’ Deep (TP-4) Non-Woven Filter Fabric To Encase 1-Inch Minus Rock 6” (min.) Rock Layer (typ.) Asphalt/Concrete Areas To Be Sloped Away @ 2% (min.). 6” (min.) 6” (min.)4” PE Sub-Drain (typ.) Crawl Space Opening Must Be Properly Vented. Note: Elevation Difference Between The Top Back Of Curb And The Finished Floor Should Be Maximized. I Believe The Subdivision Covenants Call For A Minimum Separation Of 2.0’ And A Maximum Of 5.0’. Due To High Groundwater Concerns, An Elevation Difference Of More Than 2.0’ Is Recommended. This Should Be Thoroughly Considered On A Case By Case Basis. Please Refer To The Covenants For More Detail. Important Notes: The Three-Foot Wide (Min.) Over-Excavation From The Center Of The Footing Is Calculated Based On A 16-Inch Footing Width (B) And An Average Depth To Native Gravel (GD) Below The Footing Elevation Equal To Five Feet. If The Footing Is Substantially Wider Or The Depth To Gravel Substantially Deeper; The Width Of The Excavation Will Need To Be Increased. The Equation For Determining Excavation Width (EW) From The Center Of Footing Is: EW = (B + GD) / 2.0. If Caving (ie. Sloughing) Of The Excavation Side Walls Is A Problem; EW Will Need To Be Increased Accordingly. Since The Footings Are Supported On Structural Fill That Bears On Native Gravel; There Is No BenefitTo Increasing Footing Size Beyond What Is Shown On The Plans. If Groundwater Is Encountered In The Over-Excavation Above The Native Sandy Gravel Surface, We Recommend A Layer Of Crushed Rock First Be Used To Get Above The Groundwater Elevation. The Crushed Rock Should Be Placed In A Single Lift That Does Not Extend More Than Four Inches Above The Groundwater. After Placement, The Crushed Rock MUST Be Compacted By Vibratory Methods. Compactors That Are Suitable For Crushed Rock Include Walk-Behind Plate Compactors; Remote-Controlled Sheepsfoot Trench Rollers; And Self-Propelled Smooth Drum Rollers. Note: If Groundwater Is Not Encountered, The Use Of Crushed Rock Is Not Necessary. Compacted Structural Fill. Use Sandy Pitrun Gravel, Not Crushed Rock. Gravelly Materials Are Not Only Less Expensive But They Will Also Reduce The In-Flow Of Groundwater Into The Crawl Space In The Event That High Groundwater Exceeds The Crawl Space Elevation. Place The Pitun In Lifts (Six-Inch Thick Max. For Small Remote-Controlled Sheepsfoot Trench Rollers And Twelve-Inch Thick Max. For Self- Propelled Smooth Drum Rollers) And Compact To An Unyielding Condition. Note: A Material That Works Very Well For Foundation Structural FilI Is The 3” Minus Pitrun Gravel Product That Is Available From TMC In Belgrade. Pay Special Attention To Compaction Of Crushed Rock And Structural Fill Along Edges. Native Soils Could Be Soft. Rock / Fill Will Need To Be Compacted Into Side Of Excavation. Place Woven Geotextile Fabric Over The Crushed Rock. This Will Prevent Fines Migration Into The Rock After Placement Of The Structural Fill. 4” (max.) 3’ (min.) 3’ (min.) Interior Footing As A Precaution For Groundwater, Install 4” PE Slotted Drain Piping Along The Inside Of The Perimeter Footings And Grade To A Shallow Sump Chamber In The Crawl Space. If Water Becomes An Issue, Install Sump Pump And Discharge Out Of The Crawl Space. A Four-Inch Layer Of Crushed Rock Will Facilitate Rapid Drainage And Eliminate The Sight Of Standing Water. If A Vapor Barrier Is Placed Above The Crushed Rock; Ensure It Is A Material That Can Breathe (Not Polyethylene). All Interior Footings Shall Bear On Structural Fill. Finished Floor Elev. (At-Grade Slab) GD Existing Ground Surface Existing Ground 4” Slotted PE Pipe. Install Drain Piping Around Inside Perimeter Of Foundation. Piping Should Be Placed At Footing Grade Or Preferably Below The Top Of The Crushed Rock Fill (When Used). Connect Piping To Shallow Sump Chamber. If High Groundwater Is An Issue, A Pump Can Be Installed At A Later Time. 32” 48” Reviewed By: __________________ 4” To 6” (Min.) Thickness As Required 2.5’ 4’ (min.) Damp Proofing 4” Footing Drain (typ.) Min. Depth Of Cover For Frost Protection Min. Required Width Of Mass Over-Excavation Beyond Edge Of Footing 1.0’ - 17.0’ Depth To “Target” Bearing Material. Silt/Clay Below 2.5’ (+/-) Is Generally V. Moist To Wet. See TP Logs For Soil And Groundwater Conditions. 5.0’ - 13.5’ Depth To “Target” Bearing Material. Groundwater Depth Ranged From 6.0’ to 13.5’. Depending On Time Of Year, Groundwater May Be At Or Above The Sandy Gravel (“Target” Bearing Material). Therefore, Groundwater Dewatering May Be Needed. Dewatering Wells Are Recommended To Lower Water Below Gravel Surface. Strip, Remove, And Replace All Random Fill From Under The Entire Building Area, Including Under Interior House And Garage Slabs (typ.) Note: De-Watering Will Likely Not Be Required For Foundation Excavation. Based On Our Test Pits, All Evidence Suggests The Groundwater Table Stays Within The Sandy Gravel Most Of The Time. LSE, 1/17/25 Prior To The Placement Of Granular Structural Fill, The Site’s Shallow Groundwater Conditions May Require That An Initial Layer Of Clean Crushed Rock Be Placed And Compacted Up To A Height Of At Least 6 Inches Above The Level Of The Standing Water. Structural Fill: Use 4” Minus Sandy (pitrun) Gravel Due To Shallow, Seasonal High Groundwater Conditions, Footing And Crawl Space Depth Must Be Minimized Below The Existing Ground Surface. Bottom Of Footing Elevation Should Be Kept Within At Least 2.5’ To 3.0’ Of Existing Grades. As An Added Precaution Against High Groundwater In The Crawl Space (And Especially If Footing Depth Nears Or Exceeds 2.5’ To 3.0’ Below Existing Site Grades), We Strongly Encourage The Placement Of A 6” To 8” Layer Of Crushed Rock In The Crawl Space To Raise The Floor Elevation Up To The Top Of Footings. In The Event That Groundwater Ever Rises Above The Crushed Rock Layer, A Sump Chamber And Pump Can Easily Be Installed Later To Address The Problem. We Do Not Recommend Placing The Initial Layer Of Clean Crushed Rock In Standing Water Exceeding 10 Inches In Depth. Therefore, Depending On The Time Of Year, Some Groundwater De-Watering May Be Required During Foundation Earthwork. All Perimeter, Interior, And Exterior Footings Must Bear On A Minimum 2.0’ Thickness Of Granular Structural Fill That In Turn Is Supported On The Native Sandy Gravel (Which Is The ”Target” Foundation Bearing Material). Given The 4.5’ To 6.5’ Depth To Gravel, Along With The Anticipated Slab Grade, Perimeter Footings Will Likely Lie 2.0’ to 6.0’ Above The Top Of The “Target” Gravel. Mass Over-Excavate The Entire Foundation Footprint Area, Including All Exterior Footing Locations, Down To The “Target” Bearing Material (Native Sandy Gravel); Thereby, Completely Removing All Native Silt, Clay, Sand From Under The Building. Over-Dig The Excavation To The Minimum Width Dimensions As Shown On This Figure And As Stated In The Report. Important Note: Mass Over-Excavation Of The Foundation (As Illustrated By Option #2) Will Be Required If The Individual Footing Over-ExcavationsThat Are Depicted As Option #1 Will Not Stay “Open” Due To Trench Wall Collapse. Foundation Earthwork Notes: 1) Slab On Grade - Option “B” Consists Of Over-Excavating Under All Perimeter, Interior, And Exterior Footings.2) This Is Most Applicable Where The Building Is Underlain By Relatively Deep Gravels And The Foundation Contains Less Interior Footings.3) Where Present, All Random Surface Fill Material Must Be Fully Removed From Under The Entire Building Area Down To Native Soils. Foundation Excavation Recommendations: Due To The Large Number and Close Spacing Of Interior Footings (Many Of Which Are 13 To 14 Feet On-Center), We Recommend The Entire Foundation Footprint Area Of The Apartment Buildings Be Mass Over-Excavated Down to Native Sandy Gravel And Built Back Up To Footing And Slab Grades With Compacted Structural Fill. The Limits Of The Mass Excavation Must Encapsulate All Perimeter And Exterior Footings. Important Note: It Is Now COB Policy That The Foundation Earthwork Be Inspected And Certified By The Geotechnical Engineer. Suggestions: In Order To Reduce The Amount Of Required Structural Fill Under Footings And The Slab Area, The Finished Floor Elevation Should Be Minimized Above Existing Site Grades. Another Option To Reduce Fill Under Perimeter Footings Is To Use A 6’ Tall Foundation Wall. Foundation Backfill and Embankment Fill Granular Structural Fill(1.5”Minus Roadmix Gravel)Granular Structural Fill(1.5”Minus Roadmix Gravel)Sandy Gravel(”Target” Bearing Material) Low Permeable Topsoil Native Silt/Clay(Unsuitable Bearing Material) Native Silt Native Silt/Clay/SandAnd Sand w/ Small Gravels(Unsuitable Bearing Material) Native Silt/Clay/SandAnd Sand w/ Small Gravels(Unsuitable Bearing Material) Native Topsoil Granular Structural Fill(4” Minus Sandy Gravel)Granular Structural Fill(1.5” Minus Roadmix Gravel)1” Minus CleanCrushed Rock Groundwater (on 4/19/16) Concrete Slab Exterior Foundation Wall Backfill Should Only Consist Of Excavated Soils That Are Not Overly Moist. It Must Be Placed In Multiple Lifts And Properly Compacted. Slab Grade Should Be Set Above Existing Grades. For The Mass Over- Excavation Option, There Is No Limit On Slab Height Above Existing Grades. H W = Footing Width + H; (5’ min.) All Foundation Fill Materials Should Be Placed In Uniform, Horizontal Lifts And Be Well Compacted. Granular Structural Fill Shall Be Compacted To A Dense, Unyielding Condition, While Clean Crushed Rock Or Lean Mix Concrete Must Be Compacted By Vibratory Means. In General, The “Loose” Thickness Of Each Lift Prior To Compaction Should Not Exceed 12 Inches For Large, Self- Propelled Rollers; 6 Inches For Remote-Controlled Trench Rollers And Walk-Behind Jumping Jack Compactors; And 4 Inches For Walk- Behind, Plate Compactors. Pay Special Attention To Compaction Of Structural Fill Along Edges And In Corners Of The Excavation. Place Crushed Rock As Fill Under Slab (6” min.) And Interior Wall Backfill Strip Topsoil Under Slab and Re-Compact The Subgrade Surface. Vapor Barrier Under Slab. Seal Barrier At Seams/Penetrations. Minimize New Fill Height For Settlement Reasons The Uppermost 6” Of Lean Mix Concrete Fill Can Be Replaced w/ Clean Crushed Rock For Easier Leveling Of Footing Grade. Bearing Pressure 4000 psf (max.) Important Note: To Stabilize The Trench Excavations And Minimize The Potential For Caving/Sloughing, Groundwater Dewatering May Be Required. Shallow Frost- Proof Foundation. Insulate As Per Applicable Codes. Interior Footing (typ.) Radon Mitigation System Should Be Considered Under Interior Slab. Important Note: If Foundation Construction Will Occur During The Cold/Winter Weather Season, The Contractor Shall Take All Necessary Precautions To Prevent The Earth- Work From Freezing And/Or From Being Contaminated With Snow. Note: At A Minimum, Use A Large, Smooth Drum Roller To Compact The Upper-Most Lift Of Structural Fill Under Footings And Slabs. 6” (min.) Crushed Rock Layer Under Slab Areas (typ.) Additional Thickness Of Gravel Building Pad As Req’d To Bear On “Target” Gravel. For Mass Excavation, Over-Excavation Width Beyond Perimeter Ftgs Is 5.0’ (typ.) See Fig. 6 For Over-Excavation Width Under Individual Ftg Excavations. Embankment Fill Can Be Used Below 18” Of Slab Grade. Note: No Topsoil Observed In On-Site Borings. Product Recommendation: A Stego 15-mil Vapor Barrier Is Recommended.Available From MaCon Supply In Bozeman. W = Footing Width + H; (5’ min.) Min. Width = 1/2(H); But Must Be 5’ Min. H H = 2’ Min. Important Note: If TP-3, A Clay Layer Was Observed Under The Native Sandy Gravel At A Depth Of 6.0’. It Is Recommended That All Footings Bear On A Minimum 24” Thickness Of Native Gravel Or Granular Structural Fill. This Should Be Confirmed With Test Pits Around The Perimeter Of The Building During Construction. Important Note: If The Trench Excavations Are Prone To Minor Caving, Their Width Will Have To Be Increased Accordingly To Prevent Slough From Underlying Or Being Mixed Into The Minimum Required Width Of Structural Fill. Given The 4.5’ To 6.0’ Depth To Native Sandy Gravel, We Do Not Expect That Most (If Any) Of The Perimeter Footings Will Bear Directly On Native Gravel. Most Likely, Footings Will Need To Be Supported On Structural Fill That In Turn Bears On Native Gravel (Similar To All Interior Footings). Excavation Alternative: In Lieu Of Only Excavating Footings, The Entire Foundation Footprint Area Of The Building Can Be Mass Over-Excavated Down To Native Sandy Gravel And Filled With Granular Structural Fill. Given The Gravel Depth, This Is Far Less Economical As Compared To The Above Recommendations. Prior To Granular Structural Fill Placement, The Excavated Gravel Surface (Under Entire Foundation Footprint Area) Must Be Vibratory Re-Compacted With A Large, Smooth Drum Roller In Order To Densify The Native Sandy Gravel. Due To Groundwater Depths Of 7.8’ To 9.8’, Wet Subgrade Conditions Should Not Be An Issue. Depending On Location, Groundwater Could Be At Or Above The Top Of Native Sandy Gravel During The Seasonal High Water Time Of Year. A Large, Smooth Drum Roller Must Be Used To Compact All Granular Structural Fill Whenever and Wherever Possible. Lean Mix Concrete(Flowable Fill)Embankment Fill(On-Site or Import Material)Non-Organic Embankment Fill(On-Site, “Drier” Silt/Clay/Sand) 2500 psf (max.) B 2500 psf (max.) B Mass Excavate Under Entire Foundation Footprint Area Down To Native, Clean Sandy Gravel; Thereby Removing All Of The Silt/Clay Under The Interior Slab. All Footings Must Bear On Native Sandy Gravel Or On Compacted Granular Structural Fill That In Turn Is Supported On This “Target” Bearing Material. Shallow Frost-Proof Foundation Per IBC Is Also Acceptable. H H If Exc. Walls Slough, Widen Exc. To Ensure Min. Struct. Fill Width Beyond Edge Of Ftg. Bottom Of Exc. Measurement Centered Under The Footing. If Exc. Walls Slough, Widen Exc. To Ensure Min. Struct. Fill Width Beyond Edge Of Ftg. Bottom Of Exc. Measurement Centered Under The Footing. Min. Width = (B + H); But 5’ (min.) Crushed Rock Is Only Needed If Gravel Subgrade Is Wet Or Contains Standing Water. All Fill Material Placed Under Footings And Slabs To Consist Of Compacted Granular Structural Fill. No On-Site Soils Are To Be Used As Embankment Fill Under Slabs. Do Not Place Granular Structural Fill Materials Over Wet Subgrade Or In Shallow Standing Water. De-Water The Excavation If Required. If Bottom Of Excavation Is Wet, Place An Initial, Thin Layer Of Clean Crushed Rock Under The Structural Fill. The Crushed Rock Should Extend A Minimum Of About 4” Above The Wet Conditions. Vibratory Compact The Crushed Rock And Then Cover With A Medium-Weight, Non-Woven Fabric Prior To Structural Fill Placement. Overlap Seams Of Fabric By 12” Minimum. Over-Excavate Under All Perimeter, Interior, And Exterior Footings Down To Native, Clean Sandy Gravel; Thereby Removing All Silt/Clay Under Footings. All Footings Must Bear On Native Sandy Gravel Or On Compacted Granular Structural Fill That In Turn Is Supported On This “Target” Bearing Material. Embankment Fill Under Structural Fill Layer Must Be Compacted To Project Specifications. See Figure 7 For Recommendations For Foundation Fill Material Placement And Compaction. See Figure 7 For Recommendations For Ext. Foundation Wall Backfill Material And Compaction. For Basements, Additional SubsurfaceDrainage And Moisture Protection Recommendations Will Need To BeIncorporated That Are Not Shown On This Exhibit. See Report For More Details. No Scale (Parts Of This Exhibit Have Been Exaggerated For Clarity) No Scale (Parts Of This Exhibit Have Been Exaggerated For Clarity, Especially The Depth To Gravel & The Thickness Of Req’d Structural Fill.) This Figure Shows A Deeper Gravel Depth On One End Of The Building To Illustrate The Possible Need For Over-Excavation/Replacement Under Perimeter Footings. Due To Shallow Gravel Depths Across The Site, This May Not Be Applicable/Necessary. Geotechnical Notes: 1) Figure 6 Provides Our Option 1 Recommendations For Foundation Earthwork And Support Under An At-Grade Slab Foundation Configuration. 2) Option 1 Includes Supporting The Slab On A 18-Inch (min.) Gravel Section And Over-Exc. Perimeter Footings (As Necessary) To Reach “Target” Gravel. 3) Due To Shallow Gravel Depths, Perimeter Footings Will Likely Bear In Native Gravel. Over-Excavation/Replacement May Be Limited To Interior Footings. Granular Structural Under Footings And Slabs Can Consist Of4”-Minus Sandy Pitrun Gravel Or 1.5”-Minus Roadmix Gravel. Based On Test Pits, Depth To “Target” Bearing Material Is 4’ To 5’ On Downhill Side And 3’ On Uphill Side Of The Lot. Legend Random Fill (Unsuitable Bearing Material) Random Fill (Unsuitable Bearing Material) Low Permeable Topsoil Granular Structural Fill(4”-Minus Sandy Gravel)Granular Structural Fill (*)Place In Thin Lifts And Vib. Compact To 97% (min.). Import Granular Structural Fill (*) Under Interior Slab Area (Rq’d) Vibratory Compact To 97% (min.). Import Granular Structural Fill (*) Under Footings (As Needed) Vibratory Compact To 97% (min.). 1” Minus CleanCrushed Rock 1” Minus Clean Crushed Rock 1” Minus CleanCrushed Rock1” Minus CleanCrushed RockExisting Grade (Ground Surface) Native Topsoil Topsoil or Asphalt/GravelSurfacing Materials Native Topsoil Floor Joist Exterior Wall Backfill And/Or Site Fill (Silt/Clay Or Gravel) Borrow Pit Fill (Silt/Clay) Native Topsoil Native “Clean” Sandy Gravel (“Target” Bearing Material) Native “Dirty” Sandy Gravel(Unsuitable Bearing Material) Native Silt/Clay Native Topsoil Random Fill Material (“Dirty” Gravel w/ Intermixed Silt/Clay) Flowable Fill (Lean Mix Concrete)Under Footings (Option 2)(500 psi Mix; Consolidate w/ Vib.) Interior Wall Backfill (Gran. Struct. Fill Or Crushed Rock) Interior Wall Backfill(Gran. Struct. Fill Or Crushed Rock) “Target” Bearing Material Is The Glacial Till. It Is Identifiable Based On Its Clean Sandy Composition, Abundance Of 6”-Minus, Sub-Rounded Gravels, And Dense Configuration. It Looks Like “Clean Pitrun Gravel” w/ Large Cobbles And Boulders. All Footings Shall Bear On A Minimum Of 1’ Of Granular Structural Fill That In Turn Bears On “Target” Glacial Till (typ). Additional Structural Fill Thickness Will Be Required Under Some Footings In Order To Reach “Target” Bearing Material. Recompact Subgrade Prior To Fill Placement (typ). All Foundation Fill Materials Should Be Placed In Uniform, Horizontal Lifts And Be Well Compacted. Granular Structural Fill, Embankment Fill, And Wall Backfill Shall Be Compacted To A Dense, Unyielding Condition, While Clean Crushed Rock Must Be Compacted By Vibratory Means. In General, The “Loose” Thickness Of Each Lift Prior To Compaction Should Not Exceed 12 Inches For Large, Self-Propelled Rollers; 6 Inches For Remote-Controlled Trench Rollers And Walk-Behind Jumping Jack Compactors; And 4 Inches For Walk-Behind, Plate Compactors. Pay Special Attention To Compaction Of Fill Materials Along Edges And In Corners Of The Excavation; And Along Foundation Walls. Daylight Footing And Sub-Slab Drains (typ.) See Figures 8 And 9 For Note On Exterior Foundation Wall Backfill. Granular Structural Fill Should Be Used For Interior Wall Backfill Under Slabs. See Figures 8 And 9 For Note On Foundation Fill Material Placement And Compaction. All Excavated Soils Can Be Re-Used For Exterior Wall Backfill Or Embankment Fill Provided They Are Not Organic Or Overly Moist. All Fill Must Be Placed In Thin, Level Lifts And Properly Compacted. H = 1’ or 2’ (Depending On Ftg Width) H = 1.0’ (min.) H H = 1.0’ (min.) 15-mil Vapor Barrier Under Slab (Above Rock Layer). Seal Barrier At Seams, Penetrations, And Footings. Vapor Barrier Not Typ. Under Garage Slabs. Note: Due To Unheated/Non-Insulated Buildings, Consider Insulating Under Interior Slabs To Minimize Frost Heaving Potential Of Silt/Clay. (*) Granular Structural Fill Can Consist Of 3”-Minus Sandy (Pitrun) Gravel Or 1.5”-Minus Crushed (Roadmix) Gravel Note: Deep Groundwater Conditions Exist At The Site. In Feb. 2003, Groundwater Was > 14.0’ Deep In The Area Of Lot 2A. Note: In October 2022, Groundwater Depths Ranged From 5.0’ To 10.0’ Across The Property. High Groundwater Depths In 2023 Ranged From 2.9’ To 6.9’ (Highest GW Depths On West Side). Note: We Do Not Recommend Trench Over-Excavating Footings On An Individual Basis; But Rather Mass Over-Exc. Strip Topsoil And Bench Subgrade Level Prior To Placing Fill (typ.) About 6” Of Dirty Gravel Overlies The Clean Gravel.It Is Important To Vibratory Re-Compact The Excavated “Target” Gravel Subgrade Surface Prior To Pouring Ftgs Or Placing Struct. Fill. Where Possible, Enlarge The Excavation To Allow For Use Of Large, Smooth Drum Roller. Product Recommendation: A Stego 15-mil Vapor Barrier Is Recommended. Perimeter Footing Drain To Wrap Around The Exterior Of Home (typ.) Over-Excavate Under All Perimeter, Interior, And Exterior Footings Such That They Bear On A Minimum Of 1’ Of Compacted Granular Structural Fill That In Turn Bears On “Target” Glacial Till. Min. Width Is B+H, But It Shall Not Be Less Than 5’. Use Light-Weight Fabric Around Footing Drains (typ.). Over-Excavation Width Must Be Centered On The Footings (typ.) More Than 1.0’ Of Structural Fill Is Expected (typ.) Min. Width = (B + H); But Shall Be 5.0’ (min.) This Is A Bottom Of Exc. Dimension. Assumes No Sloughing Of Exc. Side Walls. Min. Width = (B + H); But Shall Be 5.0’ (min.) This Is A Bottom Of Exc. Dimension. Assumes No Sloughing Of Exc. Side Walls. A Large, Smooth Drum Roller Should Be Used To Vibratory Compact Subgrade Soils And Granular Structural Fill Wherever Possible. Concrete Slab The Excavated Gravel Surface (Under All Footings) Must Consist Of Dense, Clean, Native Sandy Gravel. Use A Smooth Foundation Bucket To Prevent Unnecessary Disturbance To The Native Gravel Subgrade. Do Not Stop Excavation In Lowermost Silt/Clay, Which Does Contain Some Scattered Gravels. The Silt/Clay w/ Gravels (Which Looks Like A “Dirty Gravel”) Does Not Constitute The Clean, Native Sandy Gravel (“Target” Bearing Material). Vibratory Re-Compact Subgrade Surface Whenever Possible. Re-Compact Subgrade Prior To Fill Placement. Additional Structural Fill Thickness As Required. For Strip Footings With Width Of 2.0’ Or Less, Min. Structural Fill Thickness (H) Is 1.0’. For Larger Pad Footings With Width Of 3.0’ To 6.0’, Min. Structural Fill Thickness (H) Is 2.0’. Exterior Wall Backfill Can Consist Of Any Non-Organic Soil. Suggest Removing Cobbles Over 6” Directly Next To Walls. Strip Topsoil/Surfacing Material And Cut To A Min. Depth Of 18 Inches Below Bottom Of Slab Grade. For Easier Compaction, Consider Using Only High Quality Granular Material Or Clean Crushed Rock For Interior Backfill. Place In Lifts / Vibratory Compact. “Target” Clean Gravel Surface. Re-Compact Prior To Placing Fill. Pad Footing Over-Excavation On Individual Basis “Target” Clean Gravel Surface. Re-Compact Prior To Pouring Ftgs Or Placing Struct. Fill. “Target” Clean Gravel Surface. Re-Compact Prior To Pouring Ftgs Or Placing Struct. Fill. Foundation Bearing Recommendation: All Footings Must Bear On “Target” Sandy Gravel Or On Granular Structural Fill That In Turn Bears On “Target” Gravel. Note: Remove Any Sand Seams In “Target” Gravel From Bottom Of Excavation (Prior To Fill Placement Or Pouring Footings). All Excavations And Structural Fill Under Footings Must Be Centered Under The Footing. Note: If Native Gravel Is Wet, Place An Initial Thin Layer Of Clean Crushed Rock Covered By Non-Woven Fabric Prior To Structural Fill. Vibratory Compact The Rock. Excavations Should Be Wide Enough To Permit The Use Of A Large, Smooth Drum Roller For Compaction Of Gravel Subgrade And Granular Structural Fill. Footing Subgrade Will Consist Of Native Silt/Clay. Dig With Smooth- Edged Bucket To Prevent Disturbance. Vibratory Compact To Re-Tighten Soils And Induce Consolidation/Settlement. Due To Dry Soils, Construction Water May Need To Be Added To Facilitate Better Compaction. (Typ. All Locations) Over-Excavation And Structural Fill To Be Centered Under Footing And Extend A Minimum Of 2.0’ Beyond Outside Edge Of Ftg In All Directions. Over-Excavation And Structural Fill To Be Centered Under Footing And Extend A Minimum Of 2.0’ Beyond Outside Edge Of Ftg In All Directions. Strip Topsoil Before Placing Fill Material. Strip Gravel. Depending On The Number/Spacing Of Interior Footings. Consideration Should Be Given To Mass Excavating Down To “Target” Gravel Throughout Foundation Footprint And Increasing Thickness Of The 12-Inch Structural Fill Layer. By Doing This, Over-Excavation (On An Individual Basis) Under Interior Footings Could Be Avoided. H Min. Width = H / 2 Min. Width = H / 2 Existing Ground Landscape Areas To Grade Away @ 5% (min.). Perimeter Footing And Foundation Wall (typ.) Depth To “Target” Sandy Gravel Ranges From 1.5’ To 5.0’; But Is 3.0’ To 5.0’ In Most Areas. (See Fig. 3) Note: Due To Site’s 3.0’ To 5.0’ Gravel Depth, Most Perimeter Ftgs Will Need To Bear On Struct. Fill. Note: Depending On Finished Floor Elevation And Perimeter Footing Depth, (Below Ex. Grades), Some Perimeter Footings May Bear Directly On “Target” Gravel. Strip Surface Fill And Topsoil Prior To Filling. Most Likely, Perimeter Footings Will Readily Bear In Or Near “Target” Gravel (Meaning Either No Req’d Structural Fill Or Only A Relatively Thin Amount). The Benefit Of Mass Over-Excavation And Replacement Is That Interior Footings Now Do Not Have To Be Over- Excavated On An Individual Basis. “Target” Clean Gravel Must Be Exposed Throughout The Bottom Of Excavation. Re-Compact Subgrade Prior To Structural Fill Placement. See Figure 5 For An Illustration That ShowsA Crawl Space Foundation Configuration. We Recommend Mass Over-Excavation Under Slab-On-Grade Foundations Down To “Target” Bearing (In Lieu Of Trench Excavating Under All Perimeter, Interior, And Exterior Footings On An Individual Basis). This Excavation Approach Is Faster; But It Requires In-Filling/Backfilling Inside The Foundation Walls With Granular Structural Fill Back Up To Interior Footing Grade. For Figure 6, We Have Shown A Deep Native Gravel Surface To Purposely Illustrate The Need For The Placement Of A Structural Fill Building Pad Back Up To Perimeter Footing Grade. Due To Shallow Gravels, Most Perimeter Footings Should Readily Bear In/Near The “Target” Gravels. Due To The Complexity Of Most Foundation Plans (Many/Closely Spaced Interior Footings),Individual Footing Over-Excavation Is Time Consuming, Difficult, And Not Recommended. Due To The Shallow Gravels, Assumed Complexity Of The Foundation Plan (Number And Spacing Of Interior Footings), And Need To Fully Remove All Fill Material (That Was Found In The NE Corner), The Best Approach Will Likely Be Mass Over-Excavation Of The Entire Foundation Footprint Area. Some Perimeter Ftgs May Require Some Struct. Fill. No Underslab Drains Req’d. Due To Shallow Gravels And Likely Complexity Of The Foundation Plan (Many/Closely Spaced Interior Footings), We Assume Most Building Foundations Will Be Mass Over-Excavated Down To “Target” Gravel And Re-Filled With Structural Fill Up To Interior Footing Grade. Interior Footings Will Most Likely Require Struct. Fill. Min. Exc. Width = H / 2; 2.0’ (min.) Compacted Subgrade (Non-Organic Silt/Clay) Edge Of Borrow Pit Compacted Subgrade (“Target” Sandy Gravel)Compacted Subgrade (“Target” Sandy Gravel) No Footing Over-Excavation Or Structural Fill Rq’d Where Footings Bear In “Target” Sandy Gravel. Compacted Subgrade (“Target” Sandy Gravel) Given The Shallow Gravel Depth In Most Areas, Footing Grade Should Be Close To “Target” Gravel. Structural Fill Thickness (H) As Needed/Required To Build Up From “Target” Gravel To Ftg. Grade. Due To Shallow Gravel Depths, Perimeter Footings Should Bear In Or Near The Native Gravel, With Limited Needed For Over-Excavation (To Reach “Target” Gravel). The Majority Of Over-Excavation/Replacement Will Likely Be Required Under The Higher Elevation Interior Footings (Under The Slab). Note: The Upper 6” To 9” Of Native Gravel Is Generally A Little More Of A Silty, Sandy Gravel, Which Transitions To “Cleaner” Sandy Gravel With Depth. Note: Where Possible, Use Medium to Large Smooth Drum Roller For Compaction Of Native Subgrade And Granular Struct. Fill. “Target” Clean Gravel Surface At Bottom Of Mass Excavation. If The Surface Is Dry, Vibratory Re-Compact Prior To Pouring Footings Or Placing Granular Structural Fill. Note: Dig Foundation Exc. With Smooth-Edged Bucket To Minimize DisturbanceTo Native Gravel Subgrade. Unless The Site Has Been Filled With A Little More Surface Fill Since The Test Pits Were Dug In Feb. 2003, The Depth To Gravel Will Range From 1.5’ To 3.0’. “Target” Clean Gravel Surface At Bottom Of Mass Excavation. If The Surface Is Wet, Track-Pack With Excavator And Static Roll With Roller Prior To Placing Crushed Rock. No Ftg Drains Req’d 4’ (min.) For Frost Protection If Rq’d By IBC, Damp Proof Foundation Walls Note: This Figure Illustrates The Possible Need For Some Fabric- Covered, Clean Crushed Rock To Get Above Wet Conditions Or Shallow Groundwater. If The Bottom Of Excavation Is Dry, Then No Crushed Rock Will Be Necessary. If Groundwater Is Above The Native Gravel, Lower Groundwater By De-Watering. If The Gravel Subgrade Is Wet Or Contains Areas Of Shallow Standing Water, Place And Vibratory Compact An Initial Layer Of 1”-Minus Clean Crushed Rock To Get Above The Wet Conditions. Cover The Crushed Rock Layer With A Layer Of 8 oz. Non-Woven Geotextile Fabric Prior To Placing The Granular Structural Fill. Min. Exc. Width = H / 2; 2.0’ (min.) Min. Exc. Width = H / 2; 2.0’ (min.) W W W W Note: Due To Expected 5.0’ To 7.0’ Gravel Depth, Interior Ftgs Will Need To Bear On Several Feet Of Structural Fill. Note: Due To Mass Over-Exc., A Thick Structural Fill Bldg Pad Will Be Placed Under Interior Ftgs. Landscape Areas To Slope Away @ 5% (min.) Within 10’ Of Wall. Upper 4” - 6” Of Backfill Should Consist Of Low Permeable Topsoil. 2500 psf (max.) B 12” (min.) Structural Fill Layer Under Interior Slab Area. (typ.) More Than 12 Inches Of Structural Fill May Be Required In Areas Of Thicker Surface Fill And Deeper Topsoil Stripping. Gravel/Rock Backfill Is Recommended Under Interior Slabs (typ.) In Most Areas, Thickness Of Silt/Clay Ranges From 0.5’ To 1.5’. Gravel Backfill Is Recommended Under Exterior Concrete Areas To Minimize Frost Heaving Potential Crushed Rock/ Gravel Section H H W W Note: Deep Over-Excavations Will Require Wider Excavations For Rq’d Min. Structural Fill Width. Note: Depending On Borrow Pit Edge/Location, Shape, Depth, And Side Wall Slope, Significant Over- Excavation May Be Required Under The East Side Footing/Wall Line. Important Note: An Old Borrow Pit Area That Is Re-Filled With Silt/Clay Is Located On The East Side Of The Phase 1 Building Location. The West Edge Of The Borrow Pit Encroaches Inside The East Side Of The Building. In Most Areas Along The East Footing/Wall Line, The Depth To “Target Bearing”, Sandy Gravel Should Be Between About 2.0’ And 7.0’; However The Pit Depth Falls Sharply To The East Down To A Depth Of About 15.5’. (See Figures 2, 3, 4, & 5)Strip Topsoil And Place Site Fill Under Ext. Slabs. Figure 7 24-166 Jan. 2025 Lot 2A, Blk 1, Glen Lake Commerce Sub. Foundation Detail - At-Grade Slab - Option 2 Bozeman, Montana Damp-Proofing As Required (typ.) Foundation Wall (typ.)Approved Non-Woven Filter Fabric To Encase Bedding Gravel (typ.) Interior Floor Slab (typ.)Interior Steel Column (typ.)Interior Spread Footing (typ.) 6” Of 3/4" Minus Crushed Washed Gravel Hydraulically Connected To Sub-Drain or Existing Surface Drainage (typ.) Native Topsoil andRandom Surface Fill Imported 4-Inch Minus Sandy Pitrun Gravel Native Silt/ClayImported Flowable Fill Six Inch Diameter Sub-Drain Pipe (Graded To Drain To Sump Area) Concrete SidewalkLow Permeability Soils(Landscaped Area)LegendConcrete Wall and/or Footing Low Permeable Topsoil No Scale (Parts Of This Exhibit Have Been Exaggerated For Clarity) ALLIEDENGINEERING SERVICES, INC. Civil Engineering Geotechnical Engineering Land Surveying 32 Discovery Drive Bozeman, MT 59718 Phone: (406) 582-0221 Fax: (406) 582-5770 Slope Away @ 2% In All Concrete Or Pavement Areas (typ.) Footings 6’ max. depth below existing ground Native Topsoil 6” Minus Sandy (Pitrun) Gravel 4” Minus Sandy PitrunGravel (ie. Structural Fill)4’ max fill above existing ground 4' min. 4’ Max Fill Above Existing Ground 3” (min.) Thickness Will Vary Due To Depth Of Bedbrock Strata 6” (min.) 3” (min.) 8” (min.) 4.0’ (min.) 6” (min.) Of Rock Bedding To Be Placed Around Drain Piping (typ.) Under-Slab Rock Layer To Be Hydraulically Connected To Sub-Drain System By 3” Of Rock Or 2” Sch. 80 Piping Spaced On 10’ Centers (typ.) B H (Variable; Depends On Depth To Gravel) 18” (min.) 18” (min.) 6” (min.) 6” (min.) 1’ (min.) H = 3.5’ (Based On4.0’ Footing Depth And The Depth To Gravel In TP-4) H = 5.5’ (Based On4.0’ Footing Depth And The Depth To Gravel In TP-2) D D Woven Geotextile Filter Fabric (Amoco 2004)Vapor Barrier Under Slab (typ.) 9.5’ Deep (TP-2) 7.5’ Deep (TP-4) Non-Woven Filter Fabric To Encase 1-Inch Minus Rock 6” (min.) Rock Layer (typ.) Asphalt/Concrete Areas To Be Sloped Away @ 2% (min.). 6” (min.) 6” (min.)4” PE Sub-Drain (typ.) Crawl Space Opening Must Be Properly Vented. Note: Elevation Difference Between The Top Back Of Curb And The Finished Floor Should Be Maximized. I Believe The Subdivision Covenants Call For A Minimum Separation Of 2.0’ And A Maximum Of 5.0’. Due To High Groundwater Concerns, An Elevation Difference Of More Than 2.0’ Is Recommended. This Should Be Thoroughly Considered On A Case By Case Basis. Please Refer To The Covenants For More Detail. Important Notes: The Three-Foot Wide (Min.) Over-Excavation From The Center Of The Footing Is Calculated Based On A 16-Inch Footing Width (B) And An Average Depth To Native Gravel (GD) Below The Footing Elevation Equal To Five Feet. If The Footing Is Substantially Wider Or The Depth To Gravel Substantially Deeper; The Width Of The Excavation Will Need To Be Increased. The Equation For Determining Excavation Width (EW) From The Center Of Footing Is: EW = (B + GD) / 2.0. If Caving (ie. Sloughing) Of The Excavation Side Walls Is A Problem; EW Will Need To Be Increased Accordingly. Since The Footings Are Supported On Structural Fill That Bears On Native Gravel; There Is No BenefitTo Increasing Footing Size Beyond What Is Shown On The Plans. If Groundwater Is Encountered In The Over-Excavation Above The Native Sandy Gravel Surface, We Recommend A Layer Of Crushed Rock First Be Used To Get Above The Groundwater Elevation. The Crushed Rock Should Be Placed In A Single Lift That Does Not Extend More Than Four Inches Above The Groundwater. After Placement, The Crushed Rock MUST Be Compacted By Vibratory Methods. Compactors That Are Suitable For Crushed Rock Include Walk-Behind Plate Compactors; Remote-Controlled Sheepsfoot Trench Rollers; And Self-Propelled Smooth Drum Rollers. Note: If Groundwater Is Not Encountered, The Use Of Crushed Rock Is Not Necessary. Compacted Structural Fill. Use Sandy Pitrun Gravel, Not Crushed Rock. Gravelly Materials Are Not Only Less Expensive But They Will Also Reduce The In-Flow Of Groundwater Into The Crawl Space In The Event That High Groundwater Exceeds The Crawl Space Elevation. Place The Pitun In Lifts (Six-Inch Thick Max. For Small Remote-Controlled Sheepsfoot Trench Rollers And Twelve-Inch Thick Max. For Self- Propelled Smooth Drum Rollers) And Compact To An Unyielding Condition. Note: A Material That Works Very Well For Foundation Structural FilI Is The 3” Minus Pitrun Gravel Product That Is Available From TMC In Belgrade. Pay Special Attention To Compaction Of Crushed Rock And Structural Fill Along Edges. Native Soils Could Be Soft. Rock / Fill Will Need To Be Compacted Into Side Of Excavation. Place Woven Geotextile Fabric Over The Crushed Rock. This Will Prevent Fines Migration Into The Rock After Placement Of The Structural Fill. 4” (max.) 3’ (min.) 3’ (min.) Interior Footing As A Precaution For Groundwater, Install 4” PE Slotted Drain Piping Along The Inside Of The Perimeter Footings And Grade To A Shallow Sump Chamber In The Crawl Space. If Water Becomes An Issue, Install Sump Pump And Discharge Out Of The Crawl Space. A Four-Inch Layer Of Crushed Rock Will Facilitate Rapid Drainage And Eliminate The Sight Of Standing Water. If A Vapor Barrier Is Placed Above The Crushed Rock; Ensure It Is A Material That Can Breathe (Not Polyethylene). All Interior Footings Shall Bear On Structural Fill. Finished Floor Elev. (At-Grade Slab) GD Existing Ground Surface Existing Ground 4” Slotted PE Pipe. Install Drain Piping Around Inside Perimeter Of Foundation. Piping Should Be Placed At Footing Grade Or Preferably Below The Top Of The Crushed Rock Fill (When Used). Connect Piping To Shallow Sump Chamber. If High Groundwater Is An Issue, A Pump Can Be Installed At A Later Time. 32” 48” Reviewed By: __________________ 4” To 6” (Min.) Thickness As Required 2.5’ 4’ (min.) Damp Proofing 4” Footing Drain (typ.) Min. Depth Of Cover For Frost Protection Min. Required Width Of Mass Over-Excavation Beyond Edge Of Footing 1.0’ - 17.0’ Depth To “Target” Bearing Material. Silt/Clay Below 2.5’ (+/-) Is Generally V. Moist To Wet. See TP Logs For Soil And Groundwater Conditions. 5.0’ - 13.5’ Depth To “Target” Bearing Material. Groundwater Depth Ranged From 6.0’ to 13.5’. Depending On Time Of Year, Groundwater May Be At Or Above The Sandy Gravel (“Target” Bearing Material). Therefore, Groundwater Dewatering May Be Needed. Dewatering Wells Are Recommended To Lower Water Below Gravel Surface. Strip, Remove, And Replace All Random Fill From Under The Entire Building Area, Including Under Interior House And Garage Slabs (typ.) Note: De-Watering Will Likely Not Be Required For Foundation Excavation. Based On Our Test Pits, All Evidence Suggests The Groundwater Table Stays Within The Sandy Gravel Most Of The Time. LSE, 1/17/25 Prior To The Placement Of Granular Structural Fill, The Site’s Shallow Groundwater Conditions May Require That An Initial Layer Of Clean Crushed Rock Be Placed And Compacted Up To A Height Of At Least 6 Inches Above The Level Of The Standing Water. Structural Fill: Use 4” Minus Sandy (pitrun) Gravel Due To Shallow, Seasonal High Groundwater Conditions, Footing And Crawl Space Depth Must Be Minimized Below The Existing Ground Surface. Bottom Of Footing Elevation Should Be Kept Within At Least 2.5’ To 3.0’ Of Existing Grades. As An Added Precaution Against High Groundwater In The Crawl Space (And Especially If Footing Depth Nears Or Exceeds 2.5’ To 3.0’ Below Existing Site Grades), We Strongly Encourage The Placement Of A 6” To 8” Layer Of Crushed Rock In The Crawl Space To Raise The Floor Elevation Up To The Top Of Footings. In The Event That Groundwater Ever Rises Above The Crushed Rock Layer, A Sump Chamber And Pump Can Easily Be Installed Later To Address The Problem. We Do Not Recommend Placing The Initial Layer Of Clean Crushed Rock In Standing Water Exceeding 10 Inches In Depth. Therefore, Depending On The Time Of Year, Some Groundwater De-Watering May Be Required During Foundation Earthwork. All Perimeter, Interior, And Exterior Footings Must Bear On A Minimum 2.0’ Thickness Of Granular Structural Fill That In Turn Is Supported On The Native Sandy Gravel (Which Is The ”Target” Foundation Bearing Material). Given The 4.5’ To 6.5’ Depth To Gravel, Along With The Anticipated Slab Grade, Perimeter Footings Will Likely Lie 2.0’ to 6.0’ Above The Top Of The “Target” Gravel. Mass Over-Excavate The Entire Foundation Footprint Area, Including All Exterior Footing Locations, Down To The “Target” Bearing Material (Native Sandy Gravel); Thereby, Completely Removing All Native Silt, Clay, Sand From Under The Building. Over-Dig The Excavation To The Minimum Width Dimensions As Shown On This Figure And As Stated In The Report. Important Note: Mass Over-Excavation Of The Foundation (As Illustrated By Option #2) Will Be Required If The Individual Footing Over-ExcavationsThat Are Depicted As Option #1 Will Not Stay “Open” Due To Trench Wall Collapse. Foundation Earthwork Notes: 1) Slab On Grade - Option “B” Consists Of Over-Excavating Under All Perimeter, Interior, And Exterior Footings.2) This Is Most Applicable Where The Building Is Underlain By Relatively Deep Gravels And The Foundation Contains Less Interior Footings.3) Where Present, All Random Surface Fill Material Must Be Fully Removed From Under The Entire Building Area Down To Native Soils. Foundation Excavation Recommendations: Due To The Large Number and Close Spacing Of Interior Footings (Many Of Which Are 13 To 14 Feet On-Center), We Recommend The Entire Foundation Footprint Area Of The Apartment Buildings Be Mass Over-Excavated Down to Native Sandy Gravel And Built Back Up To Footing And Slab Grades With Compacted Structural Fill. The Limits Of The Mass Excavation Must Encapsulate All Perimeter And Exterior Footings. Important Note: It Is Now COB Policy That The Foundation Earthwork Be Inspected And Certified By The Geotechnical Engineer. Suggestions: In Order To Reduce The Amount Of Required Structural Fill Under Footings And The Slab Area, The Finished Floor Elevation Should Be Minimized Above Existing Site Grades. Another Option To Reduce Fill Under Perimeter Footings Is To Use A 6’ Tall Foundation Wall. Foundation Backfill and Embankment Fill Granular Structural Fill(1.5”Minus Roadmix Gravel)Granular Structural Fill(1.5”Minus Roadmix Gravel)Sandy Gravel(”Target” Bearing Material) Low Permeable Topsoil Native Silt/Clay(Unsuitable Bearing Material) Native Silt Native Silt/Clay/SandAnd Sand w/ Small Gravels(Unsuitable Bearing Material) Native Silt/Clay/SandAnd Sand w/ Small Gravels(Unsuitable Bearing Material) Native Topsoil Granular Structural Fill(4” Minus Sandy Gravel)Granular Structural Fill(1.5” Minus Roadmix Gravel)1” Minus CleanCrushed Rock Groundwater (on 4/19/16) Concrete Slab Exterior Foundation Wall Backfill Should Only Consist Of Excavated Soils That Are Not Overly Moist. It Must Be Placed In Multiple Lifts And Properly Compacted. Slab Grade Should Be Set Above Existing Grades. For The Mass Over- Excavation Option, There Is No Limit On Slab Height Above Existing Grades. H W = Footing Width + H; (5’ min.) All Foundation Fill Materials Should Be Placed In Uniform, Horizontal Lifts And Be Well Compacted. Granular Structural Fill Shall Be Compacted To A Dense, Unyielding Condition, While Clean Crushed Rock Or Lean Mix Concrete Must Be Compacted By Vibratory Means. In General, The “Loose” Thickness Of Each Lift Prior To Compaction Should Not Exceed 12 Inches For Large, Self- Propelled Rollers; 6 Inches For Remote-Controlled Trench Rollers And Walk-Behind Jumping Jack Compactors; And 4 Inches For Walk- Behind, Plate Compactors. Pay Special Attention To Compaction Of Structural Fill Along Edges And In Corners Of The Excavation. Place Crushed Rock As Fill Under Slab (6” min.) And Interior Wall Backfill Strip Topsoil Under Slab and Re-Compact The Subgrade Surface. Vapor Barrier Under Slab. Seal Barrier At Seams/Penetrations. Minimize New Fill Height For Settlement Reasons The Uppermost 6” Of Lean Mix Concrete Fill Can Be Replaced w/ Clean Crushed Rock For Easier Leveling Of Footing Grade. Bearing Pressure 4000 psf (max.) Important Note: To Stabilize The Trench Excavations And Minimize The Potential For Caving/Sloughing, Groundwater Dewatering May Be Required. Shallow Frost- Proof Foundation. Insulate As Per Applicable Codes. Interior Footing (typ.) Radon Mitigation System Should Be Considered Under Interior Slab. Important Note: If Foundation Construction Will Occur During The Cold/Winter Weather Season, The Contractor Shall Take All Necessary Precautions To Prevent The Earth- Work From Freezing And/Or From Being Contaminated With Snow. Note: At A Minimum, Use A Large, Smooth Drum Roller To Compact The Upper-Most Lift Of Structural Fill Under Footings And Slabs. 6” (min.) Crushed Rock Layer Under Slab Areas (typ.) Additional Thickness Of Gravel Building Pad As Req’d To Bear On “Target” Gravel. For Mass Excavation, Over-Excavation Width Beyond Perimeter Ftgs Is 5.0’ (typ.) See Fig. 6 For Over-Excavation Width Under Individual Ftg Excavations. Embankment Fill Can Be Used Below 18” Of Slab Grade. Note: No Topsoil Observed In On-Site Borings. Product Recommendation: A Stego 15-mil Vapor Barrier Is Recommended.Available From MaCon Supply In Bozeman. W = Footing Width + H; (5’ min.) Min. Width = 1/2(H); But Must Be 5’ Min. H H = 2’ Min. Important Note: If TP-3, A Clay Layer Was Observed Under The Native Sandy Gravel At A Depth Of 6.0’. It Is Recommended That All Footings Bear On A Minimum 24” Thickness Of Native Gravel Or Granular Structural Fill. This Should Be Confirmed With Test Pits Around The Perimeter Of The Building During Construction. Important Note: If The Trench Excavations Are Prone To Minor Caving, Their Width Will Have To Be Increased Accordingly To Prevent Slough From Underlying Or Being Mixed Into The Minimum Required Width Of Structural Fill. Given The 4.5’ To 6.0’ Depth To Native Sandy Gravel, We Do Not Expect That Most (If Any) Of The Perimeter Footings Will Bear Directly On Native Gravel. Most Likely, Footings Will Need To Be Supported On Structural Fill That In Turn Bears On Native Gravel (Similar To All Interior Footings). Excavation Alternative: In Lieu Of Only Excavating Footings, The Entire Foundation Footprint Area Of The Building Can Be Mass Over-Excavated Down To Native Sandy Gravel And Filled With Granular Structural Fill. Given The Gravel Depth, This Is Far Less Economical As Compared To The Above Recommendations. Prior To Granular Structural Fill Placement, The Excavated Gravel Surface (Under Entire Foundation Footprint Area) Must Be Vibratory Re-Compacted With A Large, Smooth Drum Roller In Order To Densify The Native Sandy Gravel. Due To Groundwater Depths Of 7.8’ To 9.8’, Wet Subgrade Conditions Should Not Be An Issue. Depending On Location, Groundwater Could Be At Or Above The Top Of Native Sandy Gravel During The Seasonal High Water Time Of Year. A Large, Smooth Drum Roller Must Be Used To Compact All Granular Structural Fill Whenever and Wherever Possible. Lean Mix Concrete(Flowable Fill)Embankment Fill(On-Site or Import Material)Non-Organic Embankment Fill(On-Site, “Drier” Silt/Clay/Sand) 2500 psf (max.) B 2500 psf (max.) B Mass Excavate Under Entire Foundation Footprint Area Down To Native, Clean Sandy Gravel; Thereby Removing All Of The Silt/Clay Under The Interior Slab. All Footings Must Bear On Native Sandy Gravel Or On Compacted Granular Structural Fill That In Turn Is Supported On This “Target” Bearing Material. Shallow Frost-Proof Foundation Per IBC Is Also Acceptable. H H If Exc. Walls Slough, Widen Exc. To Ensure Min. Struct. Fill Width Beyond Edge Of Ftg. Bottom Of Exc. Measurement Centered Under The Footing. If Exc. Walls Slough, Widen Exc. To Ensure Min. Struct. Fill Width Beyond Edge Of Ftg. Bottom Of Exc. Measurement Centered Under The Footing. Min. Width = (B + H); But 5’ (min.) Crushed Rock Is Only Needed If Gravel Subgrade Is Wet Or Contains Standing Water. All Fill Material Placed Under Footings And Slabs To Consist Of Compacted Granular Structural Fill. No On-Site Soils Are To Be Used As Embankment Fill Under Slabs. Do Not Place Granular Structural Fill Materials Over Wet Subgrade Or In Shallow Standing Water. De-Water The Excavation If Required. If Bottom Of Excavation Is Wet, Place An Initial, Thin Layer Of Clean Crushed Rock Under The Structural Fill. The Crushed Rock Should Extend A Minimum Of About 4” Above The Wet Conditions. Vibratory Compact The Crushed Rock And Then Cover With A Medium-Weight, Non-Woven Fabric Prior To Structural Fill Placement. Overlap Seams Of Fabric By 12” Minimum. Over-Excavate Under All Perimeter, Interior, And Exterior Footings Down To Native, Clean Sandy Gravel; Thereby Removing All Silt/Clay Under Footings. All Footings Must Bear On Native Sandy Gravel Or On Compacted Granular Structural Fill That In Turn Is Supported On This “Target” Bearing Material. Embankment Fill Under Structural Fill Layer Must Be Compacted To Project Specifications. See Figure 7 For Recommendations For Foundation Fill Material Placement And Compaction. See Figure 7 For Recommendations For Ext. Foundation Wall Backfill Material And Compaction. For Basements, Additional SubsurfaceDrainage And Moisture Protection Recommendations Will Need To BeIncorporated That Are Not Shown On This Exhibit. See Report For More Details. No Scale (Parts Of This Exhibit Have Been Exaggerated For Clarity) No Scale (Parts Of This Exhibit Have Been Exaggerated For Clarity, Especially The Depth To Gravel & The Thickness Of Req’d Structural Fill.) This Figure Shows A Deeper Gravel Depth On One End Of The Building To Illustrate The Possible Need For Over-Excavation/Replacement Under Perimeter Footings. Due To Shallow Gravel Depths Across The Site, This May Not Be Applicable/Necessary. Geotechnical Notes: 1) Figure 7 Provides Our Option 2 Recommendations For Foundation Earthwork And Support Under An At-Grade Slab Foundation Configuration. 2) Option 2 Includes Mass Excavating The Building Area Down To “Target” Gravel; And Over-Exc. Perimeter Ftgs (As Necessary) To Reach “Target” Gravel. 3) Due To Shallow Gravel Depths, Perimeter Footings Will Likely Bear In Native Gravel. Mass Exc. Will Eliminate Trench Over-Excavaton Under All Interior Ftgs. Granular Structural Under Footings And Slabs Can Consist Of4”-Minus Sandy Pitrun Gravel Or 1.5”-Minus Roadmix Gravel. Based On Test Pits, Depth To “Target” Bearing Material Is 4’ To 5’ On Downhill Side And 3’ On Uphill Side Of The Lot. Legend Random Fill (Unsuitable Bearing Material) Random Fill (Unsuitable Bearing Material) Low Permeable Topsoil Granular Structural Fill(4”-Minus Sandy Gravel)Granular Structural Fill (*)Place In Thin Lifts And Vib. Compact To 97% (min.). Import Granular Structural Fill (*) Under Interior Slab Area (Rq’d) Vibratory Compact To 97% (min.). Import Granular Structural Fill (*) Under Footings (As Needed) Vibratory Compact To 97% (min.). 1” Minus CleanCrushed Rock 1” Minus Clean Crushed Rock 1” Minus CleanCrushed Rock1” Minus CleanCrushed RockExisting Grade (Ground Surface) Native Topsoil Topsoil or Asphalt/GravelSurfacing Materials Native Topsoil Floor Joist Exterior Wall Backfill And/Or Site Fill (Silt/Clay Or Gravel) Borrow Pit Fill (Silt/Clay) Native Topsoil Native “Clean” Sandy Gravel (“Target” Bearing Material) Native “Dirty” Sandy Gravel(Unsuitable Bearing Material) Native Silt/Clay Native Topsoil Random Fill Material (“Dirty” Gravel w/ Intermixed Silt/Clay) Flowable Fill (Lean Mix Concrete)Under Footings (Option 2)(500 psi Mix; Consolidate w/ Vib.) Interior Wall Backfill (Gran. Struct. Fill Or Crushed Rock) Interior Wall Backfill(Gran. Struct. Fill Or Crushed Rock) “Target” Bearing Material Is The Glacial Till. It Is Identifiable Based On Its Clean Sandy Composition, Abundance Of 6”-Minus, Sub-Rounded Gravels, And Dense Configuration. It Looks Like “Clean Pitrun Gravel” w/ Large Cobbles And Boulders. All Footings Shall Bear On A Minimum Of 1’ Of Granular Structural Fill That In Turn Bears On “Target” Glacial Till (typ). Additional Structural Fill Thickness Will Be Required Under Some Footings In Order To Reach “Target” Bearing Material. Recompact Subgrade Prior To Fill Placement (typ). All Foundation Fill Materials Should Be Placed In Uniform, Horizontal Lifts And Be Well Compacted. Granular Structural Fill, Embankment Fill, And Wall Backfill Shall Be Compacted To A Dense, Unyielding Condition, While Clean Crushed Rock Must Be Compacted By Vibratory Means. In General, The “Loose” Thickness Of Each Lift Prior To Compaction Should Not Exceed 12 Inches For Large, Self-Propelled Rollers; 6 Inches For Remote-Controlled Trench Rollers And Walk-Behind Jumping Jack Compactors; And 4 Inches For Walk-Behind, Plate Compactors. Pay Special Attention To Compaction Of Fill Materials Along Edges And In Corners Of The Excavation; And Along Foundation Walls. Daylight Footing And Sub-Slab Drains (typ.) See Figures 8 And 9 For Note On Exterior Foundation Wall Backfill. Granular Structural Fill Should Be Used For Interior Wall Backfill Under Slabs. See Figures 8 And 9 For Note On Foundation Fill Material Placement And Compaction. All Excavated Soils Can Be Re-Used For Exterior Wall Backfill Or Embankment Fill Provided They Are Not Organic Or Overly Moist. All Fill Must Be Placed In Thin, Level Lifts And Properly Compacted. H = 1’ or 2’ (Depending On Ftg Width) H = 1.0’ (min.) H H = 1.0’ (min.) 15-mil Vapor Barrier Under Slab (Above Rock Layer). Seal Barrier At Seams, Penetrations, And Footings. Vapor Barrier Not Typ. Under Garage Slabs. Note: Due To Unheated/Non-Insulated Buildings, Consider Insulating Under Interior Slabs To Minimize Frost Heaving Potential Of Silt/Clay. (*) Granular Structural Fill Can Consist Of 3”-Minus Sandy (Pitrun) Gravel Or 1.5”-Minus Crushed (Roadmix) Gravel Note: Deep Groundwater Conditions Exist At The Site. In Feb. 2003, Groundwater Was > 14.0’ Deep In The Area Of Lot 2A. Note: In October 2022, Groundwater Depths Ranged From 5.0’ To 10.0’ Across The Property. High Groundwater Depths In 2023 Ranged From 2.9’ To 6.9’ (Highest GW Depths On West Side). Note: We Do Not Recommend Trench Over-Excavating Footings On An Individual Basis; But Rather Mass Over-Exc. Strip Topsoil And Bench Subgrade Level Prior To Placing Fill (typ.) About 6” Of Dirty Gravel Overlies The Clean Gravel.It Is Important To Vibratory Re-Compact The Excavated “Target” Gravel Subgrade Surface Prior To Pouring Ftgs Or Placing Struct. Fill. Where Possible, Enlarge The Excavation To Allow For Use Of Large, Smooth Drum Roller. Product Recommendation: A Stego 15-mil Vapor Barrier Is Recommended. Perimeter Footing Drain To Wrap Around The Exterior Of Home (typ.) Over-Excavate Under All Perimeter, Interior, And Exterior Footings Such That They Bear On A Minimum Of 1’ Of Compacted Granular Structural Fill That In Turn Bears On “Target” Glacial Till. Min. Width Is B+H, But It Shall Not Be Less Than 5’. Use Light-Weight Fabric Around Footing Drains (typ.). Over-Excavation Width Must Be Centered On The Footings (typ.) More Than 1.0’ Of Structural Fill Is Expected (typ.) Min. Width = (B + H); But Shall Be 5.0’ (min.) This Is A Bottom Of Exc. Dimension. Assumes No Sloughing Of Exc. Side Walls. Min. Width = (B + H); But Shall Be 5.0’ (min.) This Is A Bottom Of Exc. Dimension. Assumes No Sloughing Of Exc. Side Walls. A Large, Smooth Drum Roller Should Be Used To Vibratory Compact Subgrade Soils And Granular Structural Fill Wherever Possible. Concrete Slab The Excavated Gravel Surface (Under All Footings) Must Consist Of Dense, Clean, Native Sandy Gravel. Use A Smooth Foundation Bucket To Prevent Unnecessary Disturbance To The Native Gravel Subgrade. Do Not Stop Excavation In Lowermost Silt/Clay, Which Does Contain Some Scattered Gravels. The Silt/Clay w/ Gravels (Which Looks Like A “Dirty Gravel”) Does Not Constitute The Clean, Native Sandy Gravel (“Target” Bearing Material). Vibratory Re-Compact Subgrade Surface Whenever Possible. Re-Compact Subgrade Prior To Fill Placement. Additional Structural Fill Thickness As Required. For Strip Footings With Width Of 2.0’ Or Less, Min. Structural Fill Thickness (H) Is 1.0’. For Larger Pad Footings With Width Of 3.0’ To 6.0’, Min. Structural Fill Thickness (H) Is 2.0’. Exterior Wall Backfill Can Consist Of Any Non-Organic Soil. Suggest Removing Cobbles Over 6” Directly Next To Walls. Strip Topsoil/Surfacing Material And Cut To A Min. Depth Of 18 Inches Below Bottom Of Slab Grade. For Easier Compaction, Consider Using Only High Quality Granular Material Or Clean Crushed Rock For Interior Backfill. Place In Lifts / Vibratory Compact. “Target” Clean Gravel Surface. Re-Compact Prior To Placing Fill. Pad Footing Over-Excavation On Individual Basis “Target” Clean Gravel Surface. Re-Compact Prior To Pouring Ftgs Or Placing Struct. Fill. “Target” Clean Gravel Surface. Re-Compact Prior To Pouring Ftgs Or Placing Struct. Fill. Foundation Bearing Recommendation: All Footings Must Bear On “Target” Sandy Gravel Or On Granular Structural Fill That In Turn Bears On “Target” Gravel. Note: Remove Any Sand Seams In “Target” Gravel From Bottom Of Excavation (Prior To Fill Placement Or Pouring Footings). All Excavations And Structural Fill Under Footings Must Be Centered Under The Footing. Note: If Native Gravel Is Wet, Place An Initial Thin Layer Of Clean Crushed Rock Covered By Non-Woven Fabric Prior To Structural Fill. Vibratory Compact The Rock. Excavations Should Be Wide Enough To Permit The Use Of A Large, Smooth Drum Roller For Compaction Of Gravel Subgrade And Granular Structural Fill. Footing Subgrade Will Consist Of Native Silt/Clay. Dig With Smooth- Edged Bucket To Prevent Disturbance. Vibratory Compact To Re-Tighten Soils And Induce Consolidation/Settlement. Due To Dry Soils, Construction Water May Need To Be Added To Facilitate Better Compaction. (Typ. All Locations) Over-Excavation And Structural Fill To Be Centered Under Footing And Extend A Minimum Of 2.0’ Beyond Outside Edge Of Ftg In All Directions. Over-Excavation And Structural Fill To Be Centered Under Footing And Extend A Minimum Of 2.0’ Beyond Outside Edge Of Ftg In All Directions. Strip Topsoil Before Placing Fill Material. Strip Gravel. Depending On The Number/Spacing Of Interior Footings. Consideration Should Be Given To Mass Excavating Down To “Target” Gravel Throughout Foundation Footprint And Increasing Thickness Of The 12-Inch Structural Fill Layer. By Doing This, Over-Excavation (On An Individual Basis) Under Interior Footings Could Be Avoided. H Min. Width = H / 2 Min. Width = H / 2 Existing Ground Landscape Areas To Grade Away @ 5% (min.). Perimeter Footing And Foundation Wall (typ.) Depth To “Target” Sandy Gravel Ranges From 1.5’ To 5.0’; But Is 3.0’ To 5.0’ In Most Areas. (See Fig. 3) Note: Due To Site’s 3.0’ To 5.0’ Gravel Depth, Most Perimeter Ftgs Will Need To Bear On Struct. Fill. Note: Depending On Finished Floor Elevation And Perimeter Footing Depth, (Below Ex. Grades), Some Perimeter Footings May Bear Directly On “Target” Gravel. Strip Surface Fill And Topsoil Prior To Filling. Most Likely, Perimeter Footings Will Readily Bear In Or Near “Target” Gravel (Meaning Either No Req’d Structural Fill Or Only A Relatively Thin Amount). The Benefit Of Mass Over-Excavation And Replacement Is That Interior Footings Now Do Not Have To Be Over- Excavated On An Individual Basis. “Target” Clean Gravel Must Be Exposed Throughout The Bottom Of Excavation. Re-Compact Subgrade Prior To Structural Fill Placement. See Figure 5 For An Illustration That ShowsA Crawl Space Foundation Configuration. We Recommend Mass Over-Excavation Under Slab-On-Grade Foundations Down To “Target” Bearing (In Lieu Of Trench Excavating Under All Perimeter, Interior, And Exterior Footings On An Individual Basis). This Excavation Approach Is Faster; But It Requires In-Filling/Backfilling Inside The Foundation Walls With Granular Structural Fill Back Up To Interior Footing Grade. For Figure 6, We Have Shown A Deep Native Gravel Surface To Purposely Illustrate The Need For The Placement Of A Structural Fill Building Pad Back Up To Perimeter Footing Grade. Due To Shallow Gravels, Most Perimeter Footings Should Readily Bear In/Near The “Target” Gravels. Due To The Complexity Of Most Foundation Plans (Many/Closely Spaced Interior Footings),Individual Footing Over-Excavation Is Time Consuming, Difficult, And Not Recommended. Due To The Shallow Gravels, Assumed Complexity Of The Foundation Plan (Number And Spacing Of Interior Footings), And Need To Fully Remove All Fill Material (That Was Found In The NE Corner), The Best Approach Will Likely Be Mass Over-Excavation Of The Entire Foundation Footprint Area. Some Perimeter Ftgs May Require Some Struct. Fill. No Underslab Drains Req’d. Due To Shallow Gravels And Likely Complexity Of The Foundation Plan (Many/Closely Spaced Interior Footings), We Assume Most Building Foundations Will Be Mass Over-Excavated Down To “Target” Gravel And Re-Filled With Structural Fill Up To Interior Footing Grade. Interior Footings Will Most Likely Require Struct. Fill. Min. Exc. Width = H / 2; 2.0’ (min.) Compacted Subgrade Non-Organic Silt/Clay Edge Of Borrow Pit Compacted Subgrade (“Target” Sandy Gravel) Perimeter Footing Excavation Compacted Subgrade (“Target” Sandy Gravel) No Footing Over-Excavation Or Structural Fill Rq’d Where Footings Bear In “Target” Sandy Gravel. Compacted Subgrade (“Target” Sandy Gravel) Given The Shallow Gravel Depth In Most Areas, Footing Grade Should Be Close To “Target” Gravel. Structural Fill Thickness (H) As Needed/Required To Build Up From “Target” Gravel To Ftg. Grade. Due To Shallow Gravel Depths, Perimeter Footings Should Bear In Or Near The Native Gravel, With Limited Needed For Over-Excavation (To Reach “Target” Gravel). Note: The Upper 6” To 9” Of Native Gravel Is Generally A Little More Of A Silty, Sandy Gravel, Which Transitions To “Cleaner” Sandy Gravel With Depth. Note: Where Possible, Use Medium to Large Smooth Drum Roller For Compaction Of Native Subgrade And Granular Struct. Fill. “Target” Clean Gravel Surface At Bottom Of Mass Excavation. If The Surface Is Dry, Vibratory Re-Compact Prior To Pouring Footings Or Placing Granular Structural Fill. Note: Dig Foundation Exc. With Smooth-Edged Bucket To Minimize DisturbanceTo Native Gravel Subgrade. Unless The Site Has Been Filled With A Little More Surface Fill Since The Test Pits Were Dug In Feb. 2003, The Depth To Gravel Will Range From 1.5’ To 3.0’. “Target” Clean Gravel Surface At Bottom Of Mass Excavation. If The Surface Is Wet, Track-Pack With Excavator And Static Roll With Roller Prior To Placing Crushed Rock. No Ftg Drains Req’d 4’ (min.) For Frost Protection If Rq’d By IBC, Damp Proof Foundation Walls Note: This Figure Illustrates The Possible Need For Some Fabric- Covered, Clean Crushed Rock To Get Above Wet Conditions Or Shallow Groundwater. If The Bottom Of Excavation Is Dry, Then No Crushed Rock Will Be Necessary. If Groundwater Is Above The Native Gravel, Lower Groundwater By De-Watering. If The Gravel Subgrade Is Wet Or Contains Areas Of Shallow Standing Water, Place And Vibratory Compact An Initial Layer Of 1”-Minus Clean Crushed Rock To Get Above The Wet Conditions. Cover The Crushed Rock Layer With A Layer Of 8 oz. Non-Woven Geotextile Fabric Prior To Placing The Granular Structural Fill. Min. Exc. Width = H / 2; 2.0’ (min.) Min. Exc. Width = H / 2; 2.0’ (min.) W W W W Note: Due To Expected 5.0’ To 7.0’ Gravel Depth, Interior Ftgs Will Need To Bear On Several Feet Of Structural Fill. Note: Due To Mass Over-Exc., A Thick Structural Fill Bldg Pad Will Be Placed Under Interior Ftgs. Landscape Areas To Slope Away @ 5% (min.) Within 10’ Of Wall. Upper 4” - 6” Of Backfill Should Consist Of Low Permeable Topsoil. 2500 psf (max.) B 12” (min.) Structural Fill Layer Under Interior Slab Area. (typ.) More Than 12 Inches Of Structural Fill May Be Required In Areas Of Thicker Surface Fill And Deeper Topsoil Stripping. Gravel/Rock Backfill Is Recommended Under Interior Slabs (typ.) In Most Areas, Thickness Of Silt/Clay Ranges From 0.5’ To 1.5’. Mass Over-Excavation/Replacement Under The Entire Building Area Down To “Target” Gravel. Due To Shallow Gravels, This Will/May Be More Advantageous If There Are Numerous Interior Footings. This Will Eliminate Having To Trench Over-Excavate/Replace Under Interior Footings. Gravel Backfill Is Recommended Under Exterior Concrete Areas To Minimize Frost Heaving Potential Crushed Rock/ Gravel Section H H W W Note: Deep Over-Excavations Will Require Wider Excavations For Rq’d Min. Structural Fill Width. Note: Depending On Borrow Pit Edge/Location, Shape, Depth, And Side Wall Slope, Significant Over- Excavation May Be Required Under The East Side Footing/Wall Line. Important Note: An Old Borrow Pit Area That Is Re-Filled With Silt/Clay Is Located On The East Side Of The Phase 1 Building Location. The West Edge Of The Borrow Pit Encroaches Inside The East Side Of The Building. In Most Areas Along The East Footing/Wall Line, The Depth To “Target Bearing”, Sandy Gravel Should Be Between About 2.0’ And 7.0’; However The Pit Depth Falls Sharply To The East Down To A Depth Of About 15.5’. (See Figures 2, 3, 4, & 5)Strip Topsoil And Place Site Fill Under Ext. Slabs. % WATERCONTENTSAMPLESDEPTH (FT)HORIZONTAL DISTANCE (FT): JOB NUMBER: 18-024 PROJECT: Manley Road DATE: May 9, 2018 BACKHOE TYPE: Hitachi Mini-Excavator BACKHOE OPERATOR: TJ - Townsend Backhoe LOGGED BY: Lee S. Evans - AESI SURFACE ELEVATION: 4714.28’ TOTAL DEPTH: 6.0’ GROUNDWATER: Dry TEST PIT DESIGNATION: TP-A 2 4.0’ 8.0’ 4.25’ 5.0’ 2.5’ 9.0’ 0.7’ 4 6 8 10 12 2 4 8 106 4 Nuclear Density Test at 3.5’ Dry Unit Wt. = 73 pcf Moisture Content = 13.3% Den Notes: 1. Nuclear Density Testing at 2.5’ Dry Unit Weight = 123 pcf Moisture Content = 3.6% ALLIEDENGINEERING SERVICES, INC. Civil Engineering Geotechnical Engineering Land Surveying 32 Discovery Drive Bozeman, MT 59718 Phone: (406) 582-0221 Fax: (406) 582-5770 DESCRIPTION OF MATERIALS 4 5 67 LOCATION: Sta. 14+80 (+/-); W. Side of Ex. Road 15.6% 21.1% 20.1% 42.4% 8.4% 7.9% N/A 8.3% 5.1% 3.4% 15.7% 24.9% 23.0% 21.4% 00.0% N/A 23.9% 2 S2-E @ 9.0’ (Sack) 11.1% S2-C @ 3.0’ (Sack) S5-D @ 3.5’ (Sack) S1-A @ 2.0’ (Sack) 13.6% N/A Comp. A @ 2.0’ (Bucket) 3.2% S2-B @ 4.0’ (Sack) N/A Comp. B @ 3.0’ to 4.0’ (Bucket) N/A Comp. 2 @ 1.5’ to 3.0’ (Bucket) S5-D @ 1.0’ to 2.0’ (Bucket) S2-C @ 6.0’ (Sack) S1-C @ 3.0’ (Sack) CS-2/5 @ 5.0’ (Bucket) N/A N/A S1-D @ 1.0’ to 2.0’ (Bucket) CS-1/2 @ 2.0’ (Bucket) S1-D @ 8.0’ (Sack) S2-B @ 5.3’ to 9.0’ S2-C @ 9.0’ to 10.5’ S2-D @ 10.5’ to 14.0’ S2-E @ 14.0’ to 15.0’ S-1 @ 1’ 7 Qu @ 4.0’ - 9.0’ = 0.5 - 1.5 tsf Percentage and size of shale fragments increases w/ depth. Density of layer appears to increase near a depth of 4.0’. No apparent bedding of rock fragments. Depth of roots TD = 12.0’ Assumed watertable based on seepage depth. Due to water pressure in pit walls, moderate soil caving began at depth of 6.0’. Caving was confined to the clays only. Very distinct North Natural Ground Slope South 4 5 6 Liquid Limit Plastic Limit Plasticity Index 121.0 % = 48.2 % = 72.8 % Atterberg Limits for S2-C Based on the orientation of the boundary between soil types, it appears that the soils dip toward the east at grades from 0 to 10 percent. Based on previous site grading, the test pit area is relatively flat. Soil consistency decreases w/ increased depth. (See Fig. 1 & 2 for Surveyed Location) Lab Testing Results: S1-C Gravel Portion Sand Portion Silt/Clay Portion Liquid Limit Plastic Limit Plasticity Index = 67.1% = 26.5% = 6.4% = NP = NP = NP @ 6.0’ (approx.) Soils were very moist; darker in color; and walls tended to cave. Qu > 3.5 tsf General Note: Depth to groundwater was measured about 0.5 hr after excavation. This is the “stabilized” groundwater table depth. Reviewed By: __________________ GENERAL NOTES: - Orange discoloration at 6.0’ may indicate high water - Sandy gravel below 6.0’ was silty to clayey and moist - Installed PVC monitoring well (4” diameter, 10’ long) No Samples CollectedGROUNDWATER MONITORING NOTE: Test pit explorations were dug before 2015 seasonal high groundwater date. If time permits, monitoring should be conducted during spring/summer of 2015 to identify high groundwater depth. Monitoring well installed (MW-1).Bottom of 4” PVC well extends to a depth of between 9.5’ and 10.0’. (*) Groundwater seepage entering pit at 13.0’ and below. If pit had been left open for longer period of time, groundwater would have risen to a depth of about 13.0’ (+/-). STD. PROCTOR TEST RESULTS Composite A: TP-1, 2, 3, & 4 Max. Dry Density Optimum Moisture = 000.0 pcf = 00.0 % STD. PROCTOR TEST RESULTS Composite B: TP-1, 2, 3, & 4 Max. Dry Density Optimum Moisture = 000.0 pcf = 00.0 % STD. PROCTOR TEST RESULTS Composite A: TP-1 - TP -7 Max. Dry Density Optimum Moisture = 113.3 pcf = 15.7 % STD. PROCTOR TEST RESULTS Composite B: TP-1, 2, 3, & 4 Max. Dry Density Optimum Moisture = 000.0 pcf = 00.0 % LAB TESTING RESULTS Sample: S2-B Sand Portion Silt/Clay Portion Liquid Limit Plastic Limit Plasticity Index Soil Classification = 2.4 % = 97.6 % = 36.5 % = 25.1 % = 11.4 % = ML “Target” foundation bearing in “clean” cobbly, sandy GRAVEL below 3.0’ depth. Orangish “banding” in gravels at 6.0’ (+/-).Could be a sign of seasonal high groundwater. General Note: From the top down, this TP was the most rocky of all four. Upon backfilling, the surface of this TP was the most difficult to clean up due to the quantity and size of the rocks. Soil profile turned dark brown and moist below 6.5’ depth, which may be an indication of seasonal high groundwater levels. Other than surfacing materials, all soils in test pit are native. No random/foreign fill encountered. 1 2 3 4 {0.0’ - 1.0’}: Random Fill Dense; dark brown to brown; “dirty” sandy GRAVEL w/ some intermixed silt/clay; slightly moist. Notes: - Mostly small gravels. - Not much for silt/clay. {1.0’ - 1.5’}: Native Topsoil Very stiff; black to dark brown; organic clayey SILT; slightly moist. Notes: - B-horizon soil. Not very organic. {1.5’ - 2.5’}: Native Silt/Clay Stiff to very stiff; brown; sandy SILT to sandy lean CLAY w/ some small gravels in lowermost 6 inches; moist. Notes: - Qu = 1.75 - 2.25 tsf. - Moist, but stiff soil. - Transition zone to underlying sandy gravel from 2.0’ to 2.5’. {2.5’ - 6.0’}: Native Sandy Gravel Dense; brown; sandy GRAVEL w/ abundant 6”-minus gravels and scattered 6” to 10” cobbles; slightly moist. Notes: - “Clean” sandy gravel. 1 “Target” foundation bearing in sandy GRAVEL below 7.0’ depth. Groundwater depth on 08/12/14 was 5.92’. No signs or evidence of seasonal high groundwater down to a depth of 3.0’ (+/-). Moisture break at 1.0’ (+/-). Very moist/very soft below. Band of intermixed gravel from 0.5’ to 1.0’. LSE, 3/10/20 Pretty gravelly in lower 1.0’. Abundant 6”-minus gravels and scattered 6” to 10” cobbles Some caving below groundwater table. Very stiff; black to brown;silt/clay w/ multiple, inter-bedded, thin, sand seams. Layers of asphalt millings inter-bedded w/ layers of small gravels. Clean sandy gravel (native) Silt/clay (native) B-horizon topsoil (native) Random fill (gravelly) This pit had much moretopsoil than other 6 pits. Very moist/wet and very soft at 4.5’ (+/-). Based on saturated soil conditions, high groundwater could rise to a depth of 2.5’ (+/-). 2 POCKET PENETROMETER MEASUREMENTS (tsf) @ 1.0’: Qu = 2.50, 2.50, 2.75, 2.75, 3.00 @ 2.0’: Qu = 0.50, 0.50, 1.00, 1.00, 1.00 POCKET PENETROMETER MEASUREMENTS (tsf) @ 1.0’: Qu = 2.50, 2.75, 2.75, 2.75, 2.75 @ 2.0’: Qu = >4.50, >4.50, >4.50, >4.50 @ 3.0’: Qu = >4.50, >4.50, >4.50, >4.50 10’ monitoring well installed (MW-1), casing height = 12” (+/-) 3 4 5 Loose, gravelly sand LOCATION NOTE: TP-A was dug well off the west side of the ex. road. {7.0’ - 10.0’}: Native Sandy Gravel Dense; brown; sandy GRAVEL w/ abundant 6”-minus gravels and scattered 8” to 10” cobbles; slightly moist to wet. Notes: - “Clean” sandy gravel. - “Target” bearing material. DESCRIPTION OF MATERIALS (cont.): 5 6 {0.0’ - 0.2’}: Asphalt (2” Thick) % WATERCONTENTSAMPLESDEPTH (FT)HORIZONTAL DISTANCE (FT): JOB NUMBER: 18-024 PROJECT: Manley Road DATE: May 9, 2018 BACKHOE TYPE: Hitachi Mini-Excavator BACKHOE OPERATOR: TJ - Townsend Backhoe LOGGED BY: Lee S. Evans - AESI SURFACE ELEVATION: 4713.09’ TOTAL DEPTH: 3.5’ GROUNDWATER: Dry TEST PIT DESIGNATION: TP-B 2 4.0’ 8.0’ 4.25’ 5.0’ 2.5’ 9.0’ 0.7’ 4 6 8 10 12 2 4 8 106 4 Nuclear Density Test at 3.5’ Dry Unit Wt. = 73 pcf Moisture Content = 13.3% Den Notes: 1. Nuclear Density Testing at 2.5’ Dry Unit Weight = 123 pcf Moisture Content = 3.6% ALLIEDENGINEERING SERVICES, INC. Civil Engineering Geotechnical Engineering Land Surveying 32 Discovery Drive Bozeman, MT 59718 Phone: (406) 582-0221 Fax: (406) 582-5770 DESCRIPTION OF MATERIALS 4 5 67 LOCATION: Sta. 15+90 (+/-); W. Side of Ex. Road 15.6% 21.1% 20.1% 42.4% 8.4% 7.9% N/A 8.3% 5.1% 3.4% 15.7% 24.9% 23.0% 21.4% 00.0% N/A 23.9% 2 S2-E @ 9.0’ (Sack) 11.1% S2-C @ 3.0’ (Sack) S5-D @ 3.5’ (Sack) 13.6% N/A S1-A @ 2.0’ (Sack) Comp. A @ 2.0’ (Bucket) 3.2% S2-B @ 4.0’ (Sack) N/A Comp. B @ 3.0’ to 4.0’ (Bucket) N/A Comp. 2 @ 1.5’ to 3.0’ (Bucket) S5-D @ 1.0’ to 2.0’ (Bucket) S2-C @ 6.0’ (Sack) S1-C @ 3.0’ (Sack) CS-2/5 @ 5.0’ (Bucket) N/A N/A S1-D @ 1.0’ to 2.0’ (Bucket) CS-1/2 @ 2.0’ (Bucket) S1-D @ 8.0’ (Sack) S2-B @ 5.3’ to 9.0’ S2-C @ 9.0’ to 10.5’ S2-D @ 10.5’ to 14.0’ S2-E @ 14.0’ to 15.0’ S-1 @ 1’ 7 Qu @ 4.0’ - 9.0’ = 0.5 - 1.5 tsf Percentage and size of shale fragments increases w/ depth. Density of layer appears to increase near a depth of 4.0’. No apparent bedding of rock fragments. Depth of roots TD = 12.0’ Assumed watertable based on seepage depth. Due to water pressure in pit walls, moderate soil caving began at depth of 6.0’. Caving was confined to the clays only. Very distinct North Natural Ground Slope South 4 5 6 Liquid Limit Plastic Limit Plasticity Index 121.0 % = 48.2 % = 72.8 % Atterberg Limits for S2-C Based on the orientation of the boundary between soil types, it appears that the soils dip toward the east at grades from 0 to 10 percent. Based on previous site grading, the test pit area is relatively flat. Soil consistency decreases w/ increased depth. (See Fig. 1 & 2 for Surveyed Location) Lab Testing Results: S1-C Gravel Portion Sand Portion Silt/Clay Portion Liquid Limit Plastic Limit Plasticity Index = 67.1% = 26.5% = 6.4% = NP = NP = NP @ 6.0’ (approx.) Soils were very moist; darker in color; and walls tended to cave. Qu > 3.5 tsf General Note: Depth to groundwater was measured about 0.5 hr after excavation. This is the “stabilized” groundwater table depth. Reviewed By: __________________ GENERAL NOTES: - Orange discoloration at 6.0’ may indicate high water - Sandy gravel below 6.0’ was silty to clayey and moist - Installed PVC monitoring well (4” diameter, 10’ long) No Samples CollectedGROUNDWATER MONITORING NOTE: Test pit explorations were dug before 2015 seasonal high groundwater date. If time permits, monitoring should be conducted during spring/summer of 2015 to identify high groundwater depth. Monitoring well installed (MW-1).Bottom of 4” PVC well extends to a depth of between 9.5’ and 10.0’. (*) Groundwater seepage entering pit at 13.0’ and below. If pit had been left open for longer period of time, groundwater would have risen to a depth of about 13.0’ (+/-). STD. PROCTOR TEST RESULTS Composite A: TP-1, 2, 3, & 4 Max. Dry Density Optimum Moisture = 000.0 pcf = 00.0 % STD. PROCTOR TEST RESULTS Composite B: TP-1, 2, 3, & 4 Max. Dry Density Optimum Moisture = 000.0 pcf = 00.0 % STD. PROCTOR TEST RESULTS Composite A: TP-1 - TP -7 Max. Dry Density Optimum Moisture = 113.3 pcf = 15.7 % STD. PROCTOR TEST RESULTS Composite B: TP-1, 2, 3, & 4 Max. Dry Density Optimum Moisture = 000.0 pcf = 00.0 % LAB TESTING RESULTS Sample: S2-B Sand Portion Silt/Clay Portion Liquid Limit Plastic Limit Plasticity Index Soil Classification = 2.4 % = 97.6 % = 36.5 % = 25.1 % = 11.4 % = ML “Target” foundation bearing in “clean” cobbly, sandy GRAVEL below 3.0’ depth. Orangish “banding” in gravels at 6.0’ (+/-).Could be a sign of seasonal high groundwater. General Note: From the top down, this TP was the most rocky of all four. Upon backfilling, the surface of this TP was the most difficult to clean up due to the quantity and size of the rocks. Soil profile turned dark brown and moist below 6.5’ depth, which may be an indication of seasonal high groundwater levels. Other than surfacing materials, all soils in test pit are native. No random/foreign fill encountered. 1 2 3 4 5 6 7 8 {0.0’ - 0.17’}: Asphalt (2”) {0.17’ - 0.5’}: Base Gravel (4”) Dense; brown; 1.5”-minus base course GRAVEL (“clean” roadmix gravel); slightly moist. {0.5’ - 0.83’}: Silt/Clay Layer (4”) Very stiff; black to dark brown; sandy SILT to sandy lean CLAY; slightly moist. {0.83’ - 1.17’}: Sub-Base Gravel (4”) Dense; brown; 3”-minus sub-base course GRAVEL (“clean” pitrun gravel); slightly moist. {1.17’ - 1.33’}: Silt/Clay Layer (2”) Very stiff; black to dark brown; sandy SILT to sandy lean CLAY; slightly moist. {1.33’ - 1.75’}: Sub-Base Gravel (5”) Dense; brown; 3”-minus sub-base course GRAVEL (“clean” pitrun gravel); slightly moist. {1.75’ - 3.2’}: Native Silt/Clay Stiff to very stiff; black to brown; sandy SILT to sandy lean CLAY; slightly moist. {3.2’ - 3.5’}: Native Sandy Gravel Dense; brown; sandy GRAVEL w/ abundant 6”-minus gravels and scattered 6” to 10” cobbles; sl. moist. 1 “Target” foundation bearing in sandy GRAVEL below 7.0’ depth. Groundwater depth on 08/12/14 was 5.92’. No signs or evidence of seasonal high groundwater down to a depth of 3.0’ (+/-). Moisture break at 1.0’ (+/-). Very moist/very soft below. Band of intermixed gravel from 0.5’ to 1.0’. LSE, 3/10/20 Pretty gravelly in lower 1.0’. Abundant 6”-minus gravels and scattered 6” to 10” cobbles Some caving below groundwater table. Very stiff; black to brown;silt/clay w/ multiple, inter-bedded, thin, sand seams. Layers of asphalt millings inter-bedded w/ layers of small gravels. Clean sandy gravel (native) Silt/clay (native) B-horizon topsoil (native) Asphalt (2”) Base Course (4”) Sub-Base Course (4”) Sub-Base Course (5”) This pit had much moretopsoil than other 6 pits. Very moist/wet and very soft at 4.5’ (+/-). Based on saturated soil conditions, high groundwater could rise to a depth of 2.5’ (+/-). 2 POCKET PENETROMETER MEASUREMENTS (tsf) @ 1.0’: Qu = 2.50, 2.50, 2.75, 2.75, 3.00 @ 2.0’: Qu = 0.50, 0.50, 1.00, 1.00, 1.00 POCKET PENETROMETER MEASUREMENTS (tsf) @ 1.0’: Qu = 2.50, 2.75, 2.75, 2.75, 2.75 @ 2.0’: Qu = >4.50, >4.50, >4.50, >4.50 @ 3.0’: Qu = >4.50, >4.50, >4.50, >4.50 10’ monitoring well installed (MW-1), casing height = 12” (+/-) 3 4 7 6 8 5 5 Loose, gravelly sand LOCATION NOTE: TP-B was dug perpendicular to the road directly off the west edge of the ex. road. The purpose of the pit was to “knife in” and observe the pavement section structure and underlying subgrade soils. SUB-BASE NOTE: Interbedded within the 3”-minus sub-base gravel section were two thin layers (4” & 2”) of silt/clay. These were located at depths of 0.5’ to 0.83’ and from 1.17’ to 1.33’. {7.0’ - 10.0’}: Native Sandy Gravel Dense; brown; sandy GRAVEL w/ abundant 6”-minus gravels and scattered 8” to 10” cobbles; slightly moist to wet. Notes: - “Clean” sandy gravel. - “Target” bearing material. DESCRIPTION OF MATERIALS (cont.): 5 6 {0.0’ - 0.2’}: Asphalt (2” Thick) % WATERCONTENTSAMPLESDEPTH (FT)HORIZONTAL DISTANCE (FT): JOB NUMBER: 18-024 PROJECT: Manley Road DATE: May 9, 2018 BACKHOE TYPE: Hitachi Mini-Excavator BACKHOE OPERATOR: TJ - Townsend Backhoe LOGGED BY: Lee S. Evans - AESI SURFACE ELEVATION: 4710.93’ TOTAL DEPTH: 6.0’ GROUNDWATER: Dry TEST PIT DESIGNATION: TP-C 2 4.0’ 8.0’ 4.25’ 5.0’ 2.5’ 9.0’ 0.7’ 4 6 8 10 12 2 4 8 106 4 Nuclear Density Test at 3.5’ Dry Unit Wt. = 73 pcf Moisture Content = 13.3% Den Notes: 1. Nuclear Density Testing at 2.5’ Dry Unit Weight = 123 pcf Moisture Content = 3.6% ALLIEDENGINEERING SERVICES, INC. Civil Engineering Geotechnical Engineering Land Surveying 32 Discovery Drive Bozeman, MT 59718 Phone: (406) 582-0221 Fax: (406) 582-5770 DESCRIPTION OF MATERIALS 4 5 67 LOCATION: Sta. 17+75 (+/-); W. Side of Ex. Road 15.6% 21.1% 20.1% 42.4% 8.4% 7.9% N/A 8.3% 5.1% 3.4% 15.7% 24.9% 23.0% 21.4% 00.0% N/A 23.9% 2 S2-E @ 9.0’ (Sack) 11.1% S2-C @ 3.0’ (Sack) S5-D @ 3.5’ (Sack) S2-A @ 1.5’ (Sack) 13.6% N/A Comp. A @ 1.5’ (Bucket) 3.2% S2-B @ 4.0’ (Sack) N/A Comp. B @ 3.0’ to 4.0’ (Bucket) N/A Comp. 2 @ 1.5’ to 3.0’ (Bucket) S5-D @ 1.0’ to 2.0’ (Bucket) S2-C @ 6.0’ (Sack) S1-C @ 3.0’ (Sack) CS-2/5 @ 5.0’ (Bucket) N/A N/A S1-D @ 1.0’ to 2.0’ (Bucket) CS-1/2 @ 2.0’ (Bucket) S1-D @ 8.0’ (Sack) S2-B @ 5.3’ to 9.0’ S2-C @ 9.0’ to 10.5’ S2-D @ 10.5’ to 14.0’ S2-E @ 14.0’ to 15.0’ S-1 @ 1’ 7 Qu @ 4.0’ - 9.0’ = 0.5 - 1.5 tsf Percentage and size of shale fragments increases w/ depth. Density of layer appears to increase near a depth of 4.0’. No apparent bedding of rock fragments. Depth of roots TD = 12.0’ Assumed watertable based on seepage depth. Due to water pressure in pit walls, moderate soil caving began at depth of 6.0’. Caving was confined to the clays only. Very distinct North Natural Ground Slope South 4 5 6 Liquid Limit Plastic Limit Plasticity Index 121.0 % = 48.2 % = 72.8 % Atterberg Limits for S2-C Based on the orientation of the boundary between soil types, it appears that the soils dip toward the east at grades from 0 to 10 percent. Based on previous site grading, the test pit area is relatively flat. Soil consistency decreases w/ increased depth. (See Fig. 1 & 2 for Surveyed Location) Lab Testing Results: S1-C Gravel Portion Sand Portion Silt/Clay Portion Liquid Limit Plastic Limit Plasticity Index = 67.1% = 26.5% = 6.4% = NP = NP = NP @ 6.0’ (approx.) Soils were very moist; darker in color; and walls tended to cave. Qu > 3.5 tsf General Note: Depth to groundwater was measured about 0.5 hr after excavation. This is the “stabilized” groundwater table depth. Reviewed By: __________________ GENERAL NOTES: - Orange discoloration at 6.0’ may indicate high water - Sandy gravel below 6.0’ was silty to clayey and moist - Installed PVC monitoring well (4” diameter, 10’ long) No Samples CollectedGROUNDWATER MONITORING NOTE: Test pit explorations were dug before 2015 seasonal high groundwater date. If time permits, monitoring should be conducted during spring/summer of 2015 to identify high groundwater depth. Monitoring well installed (MW-1).Bottom of 4” PVC well extends to a depth of between 9.5’ and 10.0’. (*) Groundwater seepage entering pit at 13.0’ and below. If pit had been left open for longer period of time, groundwater would have risen to a depth of about 13.0’ (+/-). STD. PROCTOR TEST RESULTS Composite A: TP-1, 2, 3, & 4 Max. Dry Density Optimum Moisture = 000.0 pcf = 00.0 % STD. PROCTOR TEST RESULTS Composite B: TP-1, 2, 3, & 4 Max. Dry Density Optimum Moisture = 000.0 pcf = 00.0 % STD. PROCTOR TEST RESULTS Composite A: TP-1 - TP -7 Max. Dry Density Optimum Moisture = 113.3 pcf = 15.7 % STD. PROCTOR TEST RESULTS Composite B: TP-1, 2, 3, & 4 Max. Dry Density Optimum Moisture = 000.0 pcf = 00.0 % LAB TESTING RESULTS Sample: S2-B Sand Portion Silt/Clay Portion Liquid Limit Plastic Limit Plasticity Index Soil Classification = 2.4 % = 97.6 % = 36.5 % = 25.1 % = 11.4 % = ML “Target” foundation bearing in “clean” cobbly, sandy GRAVEL below 3.0’ depth. Orangish “banding” in gravels at 6.0’ (+/-).Could be a sign of seasonal high groundwater. General Note: From the top down, this TP was the most rocky of all four. Upon backfilling, the surface of this TP was the most difficult to clean up due to the quantity and size of the rocks. Soil profile turned dark brown and moist below 6.5’ depth, which may be an indication of seasonal high groundwater levels. Other than surfacing materials, all soils in test pit are native. No random/foreign fill encountered. 1 2 3 4 {0.0’ - 0.4’}: Random Fill Dense; dark brown to brown; “dirty” sandy GRAVEL w/ some intermixed silt/clay; slightly moist. Notes: - Mostly small gravels. - Not much for silt/clay. {0.4’ - 1.0’}: Native Topsoil Very stiff; black to dark brown; organic clayey SILT; slightly moist. Notes: - More black and organic than TP-1. {1.0’ - 2.0’}: Native Silt/Clay Stiff to very stiff; brown; sandy SILT to sandy lean CLAY w/ some small gravels in lowermost 6 inches; moist. Notes: - Qu = 2.5 - 3.0 tsf. - Moist, but stiff soil. - Transition zone to underlying sandy gravel from 1.5’ to 2.0’. {2.0’ - 6.0’}: Native Sandy Gravel Dense; brown; sandy GRAVEL w/ abundant 6”-minus gravels and scattered 6” to 10” cobbles; slightly moist. Notes: - “Clean” sandy gravel. 1 “Target” foundation bearing in sandy GRAVEL below 7.0’ depth. Groundwater depth on 08/12/14 was 5.92’. No signs or evidence of seasonal high groundwater down to a depth of 3.0’ (+/-). Moisture break at 1.0’ (+/-). Very moist/very soft below. Band of intermixed gravel from 0.5’ to 1.0’. LSE, 3/10/20 Pretty gravelly in lower 1.0’. Abundant 6”-minus gravels and scattered 6” to 10” cobbles Some caving below groundwater table. Very stiff; black to brown;silt/clay w/ multiple, inter-bedded, thin, sand seams. Layers of asphalt millings inter-bedded w/ layers of small gravels. Clean sandy gravel (native) Silt/clay (native) Organic topsoil (native) Random fill (gravelly) This pit had much moretopsoil than other 6 pits. Very moist/wet and very soft at 4.5’ (+/-). Based on saturated soil conditions, high groundwater could rise to a depth of 2.5’ (+/-). 2 POCKET PENETROMETER MEASUREMENTS (tsf) @ 1.0’: Qu = 2.50, 2.50, 2.75, 2.75, 3.00 @ 2.0’: Qu = 0.50, 0.50, 1.00, 1.00, 1.00 POCKET PENETROMETER MEASUREMENTS (tsf) @ 1.0’: Qu = 2.50, 2.75, 2.75, 2.75, 2.75 @ 2.0’: Qu = >4.50, >4.50, >4.50, >4.50 @ 3.0’: Qu = >4.50, >4.50, >4.50, >4.50 10’ monitoring well installed (MW-1), casing height = 12” (+/-) 3 4 5 Loose, gravelly sand LOCATION NOTE: TP-C was dug well off the west side of the ex. road. {7.0’ - 10.0’}: Native Sandy Gravel Dense; brown; sandy GRAVEL w/ abundant 6”-minus gravels and scattered 8” to 10” cobbles; slightly moist to wet. Notes: - “Clean” sandy gravel. - “Target” bearing material. DESCRIPTION OF MATERIALS (cont.): 5 6 {0.0’ - 0.2’}: Asphalt (2” Thick) 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. 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 lesson 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.