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CC - Updated Geotech July 2020 24 July 2020 Page # 1 of 16 b201057g_limitedgeo  Environmental Services  Geotechnical Engineering  Construction Materials Testing  Special Inspections 2791 S Victory View Way  Boise, ID 83709  (208) 376-4748  Fax (208) 322-6515 www.mti-id.com  mti@mti-id.com Copyright © 2020Materials Testing & Inspection Mr. Zach Evans Zach Evans Construction, Inc. 7761 West Riverside Drive, Suite 100 Eagle, ID 83714 (208) 853-1205 Re: Update Letter Calvary Chapel 3727 East Lake Hazel Road Meridian, ID Dear Mr. Evans: In compliance with your instructions, MTI has conducted a limited soils exploration and update letter for the above referenced development. Fieldwork for this investigation was conducted on 9 July 2020. Additionally, MTI conducted a geotechnical investigation for the project site in February 2003. The proposed development is in the southern portion of the City of Meridian, Ada County, ID, and occupies a portion of the NE¼NW¼ of Section 4, Township 2 North, Range 1 East, Boise Meridian. This project will consist of construction of a church building. The site to be developed is approximately 14.87 acres in size. Total settlements are limited to 1 inch. Loads of up to 4,000 pounds per lineal foot for wall footings, and column loads of up to 50,000 pounds were assumed for settlement calculations. Retaining walls are not anticipated as part of the project. MTI has not been informed of the proposed grading plan. Authorization Authorization to perform this exploration and analysis was given in the form of a written authorization to proceed from Mr. Zach Evans of Zach Evans Construction, Inc. to Monica Saculles of Materials Testing and Inspection (MTI), on 1 July 2020. Said authorization is subject to terms, conditions, and limitations described in the Professional Services Contract entered into between Zach Evans Construction, Inc. and MTI. Our scope of services for the proposed development has been provided in our proposal dated 12 June 2020 and repeated below. Scope of Investigation The scope of this investigation included review of geologic literature and existing available geotechnical studies of the area, visual site reconnaissance of the immediate site, subsurface exploration of the site, field and laboratory testing of materials collected, and engineering analysis and evaluation of foundation materials. Our scope of work did not include pavement design. Report Updates The original report references the 2000 International Building Code (IBC). Since that time, the 2015 IBC has been adopted and remains in current use. The original report references the IBC in 3 different sections within the document. These references have been listed below: 24 July 2020 Page # 2 of 16 b201057g_limitedgeo  Environmental Services  Geotechnical Engineering  Construction Materials Testing  Special Inspections 2791 S Victory View Way  Boise, ID 83709  (208) 376-4748  Fax (208) 322-6515 www.mti-id.com  mti@mti-id.com Copyright © 2020Materials Testing & Inspection • The first reference can be found in the Introduction section on page 5, which is a general reference to the 2000 IBC. • The second reference is on page 8 in the Geoseismic Setting section, and references Site Class D in accordance with Chapter 16 of the 2000 IBC. This Site Class is still in use and would still be Site Class D for this site. However, the 2015 IBC references Chapter 20 of the American Society of Civil Engineers (ASCE) publication ASCE/SEI 7-10 for site class determination. • The third reference is on page 13 in the Foundation Design Recommendations section, and states “Footings should be proportioned to meet either the stated soil bearing capacity or the 200 0 IBC minimum requirements.” This should now reference the 2015 IBC and is further addressed in the Updated Foundation Design Recommendations section of this report. General Site Characteristics The site to be developed is approximately 14.87 acres in size. Ten Mile Creek is present on the western border of the project site. The site consists of agricultural pasture land. To the west and south of the project site is undeveloped land. Along the eastern property boundary is a golf course. To the north of the site are residential developments. Vegetation on the site consists primarily of bunchgrass and other native weeds and grasses. The site is relatively flat and level. However, a stockpile of material was present in the west-central portion of the site. MTI was unable to advance a test pit in this area to assess the stockpiled material because the area had been fenced in and no gate was noted. Regional drainage is north and west toward the Boise River. Stormwater drainage for the site is achieved by percolation through surficial soils. The site is situated so that it is unlikely that it will receive any stormwater drainage from off-site sources. Stormwater drainage collection and retention systems are not in place on the project site and were not noted within the vicinity of the project site. Exploration and Sampling Procedures Field exploration conducted to determine engineering characteristics of subsurface materials included a reconnaissance of the project site and investigation by test pit. Test pit sites were located in the field by means of a Global Positioning System (GPS) device and are reportedly accurate to within ten feet. Upon completion of investigation, each test pit was backfilled with loose excavated materials. Re-excavation and compaction of these test pit areas are required prior to construction of overlying structures. 24 July 2020 Page # 3 of 16 b201057g_limitedgeo  Environmental Services  Geotechnical Engineering  Construction Materials Testing  Special Inspections 2791 S Victory View Way  Boise, ID 83709  (208) 376-4748  Fax (208) 322-6515 www.mti-id.com  mti@mti-id.com Copyright © 2020Materials Testing & Inspection In addition, samples were obtained from representative soil strata encountered. Samples obtained have been visually classified in the field by professional staff, identified according to test pit number and depth, and placed in sealed containers. Subsurface materials have been described in detail on logs provided in the Enclosures section. Results of field tests are also presented in the Enclosures section. MTI recommends that these logs not be used to estimate fill material quantities. Soil and Sediment Profile The profile below represents a generalized interpretation for the project site. Note that on site soils strata, encountered between test pit locations, may vary from the individual soil profiles presented in the logs, which can be found in the Enclosures section. Surficial soils were predominately lean clays, lean clays with varying sand content. Lean clay soils were dark brown to brown, dry to moist, soft to hard, and contained fine to medium-grained sand. Underlying the surficial lean clays in test pit 2 were sandy silt soils. Sandy silts were light brown, dry to slightly moist, stiff to very stiff, and contained fine to medium-grained sand. At depth throughout the site were poorly graded gravel with sand sediments. Poorly graded gravels with sand were light brown, slightly moist to saturated, medium dense to dense, and contained fine to coarse-grained sand, fine to coarse gravel, and 5-inch-minus cobbles. Competency of test pit walls varied little across the site. In general, fine grained soils remained stable while more granular sediments readily sloughed. However, moisture contents will also affect wall competency with saturated soils having a tendency to readily slough when under load and unsupported. Groundwater During this field investigation, groundwater was encountered in test pits at depths ranging from 4.5 to 5.9 feet bgs. Soil moistures in the test pits were generally dry to moist within surficial soils. Within the poorly graded gravels with sand, soil moistures graded from slightly moist to saturated as the water table was approached and penetrated. In the vicinity of the project site, groundwater levels are controlled in large part by residential and commercial irrigation activity and leakage from nearby canals. Maximum groundwater elevations likely occur during the later portion of the irrigation season. In the geotechnical investigation performed in 2003 on the project site, groundwater was encountered in test pits at depths ranging from 3.6 to 4.6 feet bgs. MTI has previously performed 8 geotechnical investigations within 0.50 mile of the project site. However, three of these investigations were noted to be at a higher elevations than the project site, and therefore, the data was not relevant to the project site. Information from the relevant investigations has been provided in the table below. 24 July 2020 Page # 4 of 16 b201057g_limitedgeo  Environmental Services  Geotechnical Engineering  Construction Materials Testing  Special Inspections 2791 S Victory View Way  Boise, ID 83709  (208) 376-4748  Fax (208) 322-6515 www.mti-id.com  mti@mti-id.com Copyright © 2020Materials Testing & Inspection Groundwater Data Date Approximate Distance from Site (mile) Direction from Site Groundwater Depth (feet bgs) December 2015 0.13 Northwest 4.7 to 5.4 August 2017 0.10 North 3.6 to 6.9 March 2018 0.10 North 5.4 to 7.1 September 2018 0.07 West 4.7 to 5.4 September 2019 0.30 Northwest 6.7 to 7.1 Furthermore, according to groundwater monitoring data collected by MTI within approximately ½-mile of the project site, groundwater was measured at depths ranging between 2.36 and 5.3 feet bgs. For construction purposes, groundwater depth can be assumed to remain greater than 2 feet bgs throughout the year. Since this is an estimated depth and seasonal groundwater levels fluctuate, actual levels should be confirmed by periodic groundwater data collected from piezometers installed in test pits 1, 2, and 3. If desired, MTI is available to perform this monitoring. Soil Infiltration Rates Soil permeability, which is a measure of the ability of a soil to transmit a fluid, was not tested in the field. Given the absence of direct measurements, for this report an estimation of infiltration is presented using generally recognized values for each soil type and gradation. Of soils comprising the generalized soil profile for this study, lean clay, lean clay with sand, and sandy lean clay soils generally offer little permeability, with typical hydraulic infiltration rates of less than 2 inches per hour. Sandy silt soils will commonly exhibit infiltration rates from 2 to 4 inches per hour. Poorly graded gravel sediments typically exhibit infiltration values in excess of 12 inches per hour; however, the presence of groundwater will significantly reduce these estimated infiltration rates. It is recommended that infiltration facilities constructed on the site be extended into native, poorly graded gravel with sand sediments. Excavation depths of roughly 2.9 to 4.2 feet bgs should be anticipated to expose these poorly graded gravel with sand sediments. However, the high groundwater depth is expected to be higher than these soils through portions of the year. When this occurs, vertical drainage of stormwater will be limited. An infiltration rate of 1 inch per hour should be used in design to account for this condition. Actual infiltration rates should be confirmed at the time of construction. Updated Foundation Design Recommendations Based on data obtained from the site, MTI recommends the following guidelines for the net allowable soil bearing capacity: 24 July 2020 Page # 5 of 16 b201057g_limitedgeo  Environmental Services  Geotechnical Engineering  Construction Materials Testing  Special Inspections 2791 S Victory View Way  Boise, ID 83709  (208) 376-4748  Fax (208) 322-6515 www.mti-id.com  mti@mti-id.com Copyright © 2020Materials Testing & Inspection Soil Bearing Capacity Footing Depth ASTM D1557 Subgrade Compaction Net Allowable Soil Bearing Capacity Footings must bear on competent, undisturbed, native lean clay soils, lean clay with sand soils, sandy lean clay soils, sandy silt soils, or compacted structural fill. Existing organic materials and fill materials (if encountered) must be completely removed from below foundation elements.1 Excavation depths ranging from roughly 1.0 to 1.2 feet bgs should be anticipated to expose proper bearing soils.2 Not Required for Native Soil 95% for Structural Fill 1,500 lbs/ft2 A ⅓ increase is allowable for short-term loading, which is defined by seismic events or designed wind speeds. Footings must bear on competent, undisturbed, native poorly graded gravel with sand sediments or compacted structural fill. Existing organic materials and fill materials (if encountered) must be completely removed from below foundation elements.1 Excavation depths ranging from roughly 2.9 to 4.2 feet bgs should be anticipated to expose proper bearing soils.2 Not Required for Native Soil 95% for Structural Fill 3,000 lbs/ft2 A ⅓ increase is allowable for short-term loading, which is defined by seismic events or designed wind speeds. 1It will be required for MTI personnel to verify the bearing soil suitability for each structure at the time of construction. 2Depending on the time of year construction takes place, the subgrade soils may be unstable because of high moisture contents. If unstable conditions are encountered, over-excavation and replacement with granular structural fill and/or use of geotextiles may be required. The following sliding frictional coefficient values should be used: 1) 0.35 for footings bearing on native lean clay soils, sandy lean clay soils, and sandy silt soils and 2) 0.45 for footings bearing on granular structural fill and native poorly graded gravel with sand sediments. A passive lateral earth pressure of 309 pounds per square foot per foot (psf/ft) should be used for lean clay soils and 339 psf/ft should be used for sandy lean clay soils and sandy silt soils. For compacted sandy gravel fill and native poorly graded gravel with sand sediments, a passive lateral earth pressure of 496 psf/ft should be used. Footings should be proportioned to meet either the stated soil bearing capacity or the 2015 IBC minimum requirements. Total settlement should be limited to approximately 1 inch, and differential settlement should be limited to approximately ½ inch. Objectionable soil types encountered at the bottom of footing excavations should be removed and replaced with structural fill. Excessively loose or soft areas that are encountered in the footings subgrade will require over-excavation and backfilling with structural fill. To minimize the effects of slight differential movement that may occur because of variations in the character of supporting soils and seasonal moisture content, MTI recommends continuous footings be suitably reinforced to make them as rigid as possible. MTI recommends that the bottom of external footings be 30 inches below finished grade for frost protection. Based on the soil types encountered onsite, foundation drains are not needed. 24 July 2020 Page # 6 of 16 b201057g_limitedgeo  Environmental Services  Geotechnical Engineering  Construction Materials Testing  Special Inspections 2791 S Victory View Way  Boise, ID 83709  (208) 376-4748  Fax (208) 322-6515 www.mti-id.com  mti@mti-id.com Copyright © 2020Materials Testing & Inspection General Comments Based on the subsurface conditions encountered during this investigation and available information regarding the proposed structure, the site is adequate for the planned construction. When plans and specifications are complete, and if significant changes are made in the character or location of the proposed structure, consultation with MTI must be arranged as supplementary recommendations may be required. Often, questions arise concerning soil conditions because of design and construction details that occur on a project. MTI would be pleased to continue our role as geotechnical engineers during project implementation. Additionally, MTI can provide materials testing and special inspection services during construction of this project. If you will advise us of the appropriate time to discuss these engineering services, we will meet with you at your convenience. MTI appreciates this opportunity to be of service to you and looks forward to working with you in the future. If you have questions, please call (208) 376-4748. Respectfully Submitted, Materials Testing & Inspection Jacob Schlador, P.E. Reviewed by: Monica Saculles, P.E. Geotechnical Engineer Senior Geotechnical Engineer Enclosures: Warranty and Limiting Conditions Vicinity Map Site Map Geotechnical Investigation Test Pit Logs Geotechnical General Notes Important Information About This Geotechnical Engineering Report 24 July 2020 Page # 7 of 16 b201057g_limitedgeo  Environmental Services  Geotechnical Engineering  Construction Materials Testing  Special Inspections 2791 S Victory View Way  Boise, ID 83709  (208) 376-4748  Fax (208) 322-6515 www.mti-id.com  mti@mti-id.com Copyright © 2020Materials Testing & Inspection WARRANTY AND LIMITING CONDITIONS MTI warrants that findings and conclusions contained herein have been formulated in accordance with generally accepted professional engineering practice in the fields of foundation engineering, soil mechanics, and engineering geology only for the site and project described in this report. These engineering methods have been developed to provide the client with information regarding apparent or potential engineering conditions relating to the site within the scope cited above and are necessarily limited to conditions observed at the time of the site visit and research. Field observations and research reported herein are considered sufficient in detail and scope to form a reasonable basis for the purposes cited above. Exclusive Use This report was prepared for exclusive use of the property owner(s), at the time of the report, and their retained design consultants (“Client”). Conclusions and recommendations presented in this report are based on the agreed-upon scope of work outlined in this report together with the Contract for Professional Services between the Client and Materials Testing and Inspection (“Consultant”). Use or misuse of this report, or reliance upon findings hereof, by parties other than the Client is at their own risk. Neither Client nor Consultant make representation of warranty to such other parties as to accuracy or completeness of this report or suitability of its use by such other parties for purposes whatsoever, known or unknown, to Client or Consultant. Neither Client nor Consultant shall have liability to indemnify or hold harmless third parties for losses incurre d by actual or purported use or misuse of this report. No other warranties are implied or expressed. Report Recommendations are Limited and Subject to Misinterpretation There is a distinct possibility that conditions may exist that could not be identifie d within the scope of the investigation or that were not apparent during our site investigation. Findings of this report are limited to data collected from noted explorations advanced and do not account for unidentified fill zones, unsuitable soil types or conditions, and variability in soil moisture and groundwater conditions. To avoid possible misinterpretations of findings, conclusions, and implications of this report, MTI should be retained to explain the report contents to other design professionals as well as construction professionals. Since actual subsurface conditions on the site can only be verified by earthwork, note that construction recommendations are based on general assumptions from selective observations and selective field exploratory sampling. Upon commencement of construction, such conditions may be identified that require corrective actions, and these required corrective actions may impact the project budget. Therefore, construction recommendations in this report should be considered preliminary, and MTI should be retained to observe actual subsurface conditions during earthwork construction activities to provide additional construction recommendations as needed. Since geotechnical reports are subject to misinterpretation, do not separate the soil logs from the report. Rather, provide a copy of, or authorize for their use, the complete report to other design professionals or contractors. Locations of exploratory sites referenced within this report should be considered approximate locations only. For more accurate locations, services of a professional land surveyor are recommended. 24 July 2020 Page # 8 of 16 b201057g_limitedgeo  Environmental Services  Geotechnical Engineering  Construction Materials Testing  Special Inspections 2791 S Victory View Way  Boise, ID 83709  (208) 376-4748  Fax (208) 322-6515 www.mti-id.com  mti@mti-id.com Copyright © 2020Materials Testing & Inspection This report is also limited to information available at the time it was prepared. In the event additional information is provided to MTI following publication of our report, it will be forwarded to the client for evaluation in the form received. Environmental Concerns Comments in this report concerning either onsite conditions or observations, including soil appearances and odors, are provided as general information. These comments are not intended to describe, quantify, or evaluate environmental concerns or situations. Since personnel, skills, procedures, standards, and equipment differ, a geotechnical investigation report is not intended to substitute for a geoenvironmental investigation or a Phase II/III Environmental Site Assessment. If environmental services are needed, MTI can provide, via a separate contract, those personnel who are trained to investigate and delineate soil and water contamination. 24 July 2020 Page # 11 of 16 b201057g_limitedgeo  Environmental Services  Geotechnical Engineering  Construction Materials Testing  Special Inspections 2791 S Victory View Way  Boise, ID 83709  (208) 376-4748  Fax (208) 322-6515 www.mti-id.com  mti@mti-id.com Copyright © 2020Materials Testing & Inspection GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP-1 Date Advanced: 9 July 2020 Logged by: Jacob Schlador, P.E. Excavated by: Struckman’s Backhoe Service Location: See Site Map Plates Latitude: 43.54622 Longitude: -116.34674 Depth to Water Table: 4.5 Feet bgs Total Depth: 5.8 Feet bgs Notes: Piezometer installed to 5.8 feet bgs. Depth (Feet bgs) Field Description and USCS Soil and Sediment Classification Sample Type Sample Depth (Feet bgs) Qp Lab Test ID 0.0-2.9 Sandy Lean Clay (CL): Dark brown to brown, dry to slightly moist, medium stiff to very stiff, with fine to medium-grained sand. --Organics to a depth of 1.0 foot bgs. 1.0-2.0 2.9-5.8 Poorly Graded Gravel with Sand (GP): Brown to light brown, slightly moist to saturated, medium dense, with fine to coarse- grained sand, fine to coarse gravel, and 4- inch-minus cobbles. 24 July 2020 Page # 12 of 16 b201057g_limitedgeo  Environmental Services  Geotechnical Engineering  Construction Materials Testing  Special Inspections 2791 S Victory View Way  Boise, ID 83709  (208) 376-4748  Fax (208) 322-6515 www.mti-id.com  mti@mti-id.com Copyright © 2020Materials Testing & Inspection GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP-2 Date Advanced: 9 July 2020 Logged by: Jacob Schlador, P.E. Excavated by: Struckman’s Backhoe Service Location: See Site Map Plates Latitude: 43.54392 Longitude: -116.34511 Depth to Water Table: 4.6 Feet bgs Total Depth: 5.2 Feet bgs Notes: Piezometer installed to 5.2 feet bgs. Depth (Feet bgs) Field Description and USCS Soil and Sediment Classification Sample Type Sample Depth (Feet bgs) Qp Lab Test ID 0.0-1.0 Lean Clay (CL): Dark brown, dry, very stiff to hard, with fine-grained sand. --Organics encountered throughout. 2.5-4.5 1.0-3.1 Sandy Silt (ML): Light brown, dry to slightly moist, stiff to very stiff, with fine to medium- grained sand. 3.1-5.2 Poorly Graded Gravel with Sand (GP): Light brown, moist to saturated, medium dense to dense, with fine to coarse-grained sand, fine to coarse gravel, and 5-inch-minus cobbles. 24 July 2020 Page # 13 of 16 b201057g_limitedgeo  Environmental Services  Geotechnical Engineering  Construction Materials Testing  Special Inspections 2791 S Victory View Way  Boise, ID 83709  (208) 376-4748  Fax (208) 322-6515 www.mti-id.com  mti@mti-id.com Copyright © 2020Materials Testing & Inspection GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log #: TP-3 Date Advanced: 9 July 2020 Logged by: Jacob Schlador, P.E. Excavated by: Struckman’s Backhoe Service Location: See Site Map Plates Latitude: 43.54510 Longitude: -116.34514 Depth to Water Table: 5.9 Feet bgs Total Depth: 6.3 Feet bgs Notes: Piezometer installed to 6.3 feet bgs. Depth (Feet bgs) Field Description and USCS Soil and Sediment Classification Sample Type Sample Depth (Feet bgs) Qp Lab Test ID 0.0-4.2 Lean Clay with Sand (CL): Dark brown to brown, dry to moist, soft to stiff, with fine- grained sand and intermittent medium- grained sand. --Organics to a depth of 1.2 feet bgs. 0.5-1.5 4.2-6.3 Poorly Graded Gravel with Sand (GP): Light brown, moist to saturated, medium dense to dense, with fine to coarse-grained sand, fine to coarse gravel, and 5-inch-minus cobbles. 24 July 2020 Page # 14 of 16 b201057g_limitedgeo  Environmental Services  Geotechnical Engineering  Construction Materials Testing  Special Inspections 2791 S Victory View Way  Boise, ID 83709  (208) 376-4748  Fax (208) 322-6515 www.mti-id.com  mti@mti-id.com Copyright © 2020Materials Testing & Inspection GEOTECHNICAL GENERAL NOTES UNIFIED SOIL CLASSIFICATION SYSTEM Major Divisions Symbol Soil Descriptions Coarse-Grained Soils < 50% passes No.200 sieve Gravel & Gravelly Soils < 50% coarse fraction passes No.4 sieve GW Well-graded gravels; gravel/sand mixtures with little or no fines GP Poorly-graded gravels; gravel/sand mixtures with little or no fines GM Silty gravels; poorly-graded gravel/sand/silt mixtures GC Clayey gravels; poorly-graded gravel/sand/clay mixtures Sand & Sandy Soils > 50% coarse fraction passes No.4 sieve SW Well-graded sands; gravelly sands with little or no fines SP Poorly-graded sands; gravelly sands with little or no fines SM Silty sands; poorly-graded sand/gravel/silt mixtures SC Clayey sands; poorly-graded sand/gravel/clay mixtures Fine-Grained Soils > 50% passes No.200 sieve Silts & Clays LL < 50 ML Inorganic silts; sandy, gravelly or clayey silts CL Lean clays; inorganic, gravelly, sandy, or silty, low to medium-plasticity clays OL Organic, low-plasticity clays and silts Silts & Clays LL > 50 MH Inorganic, elastic silts; sandy, gravelly or clayey elastic silts CH Fat clays; high-plasticity, inorganic clays OH Organic, medium to high-plasticity clays and silts Highly Organic Soils PT Peat, humus, hydric soils with high organic content RELATIVE DENSITY AND CONSISTENCY CLASSIFICATION MOISTURE CONTENT AND CEMENTATION CLASSIFICATION Coarse-Grained Soils SPT Blow Counts (N) Description Field Test Very Loose: < 4 Dry Absence of moisture, dusty, dry to touch Loose: 4-10 Slightly Moist Damp, but not visible moisture Medium Dense: 10-30 Moist Visible moisture Dense: 30-50 Wet Visible free water Very Dense: > 50 Saturated Soil is usually below water table Fine-Grained Soils SPT Blow Counts (N) Description Field Test Very Soft: < 2 Weak Crumbles or breaks with handling or slight finger pressure Soft: 2-4 Medium Stiff: 4-8 Moderate Crumbles or breaks with considerable finger pressure Stiff: 8-15 Very Stiff: 15-30 Strong Will not crumble or break with finger pressure Hard: > 30 PARTICLE SIZE ACRONYM LIST Boulders: > 12 in. GS grab sample Cobbles: 12 to 3 in. LL Liquid Limit Gravel: 3 in. to 5 mm M moisture content Coarse-Grained Sand: 5 to 0.6 mm NP non-plastic Medium-Grained Sand: 0.6 to 0.2 mm PI Plasticity Index Fine-Grained Sand: 0.2 to 0.075 mm Qp penetrometer value, unconfined compressive strength, tsf Silts: 0.075 to 0.005 mm Clays: < 0.005 mm V vane value, ultimate shearing strength, tsf Geotechnical-Engineering Report Important Information about This Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes. While you cannot eliminate all such risks, you can manage them. The following information is provided to help. The Geoprofessional Business Association (GBA) has prepared this advisory to help you – assumedly a client representative – interpret and apply this geotechnical-engineering report as effectively as SRVVLEOH,QWKDWZD\\RXFDQEHQH¿WIURPDORZHUHG exposure to problems associated with subsurface conditions at project sites and development of them that, for decades, have been a principal cause of construction delays, cost overruns, claims, and disputes. If you have questions or want more information about any of the issues discussed herein, contact your GBA-member geotechnical engineer. Active engagement in GBA exposes geotechnical engineers to a wide array of risk-confrontation WHFKQLTXHVWKDWFDQEHRIJHQXLQHEHQH¿WIRU everyone involved with a construction project. Understand the Geotechnical-Engineering Services Provided for this Report Geotechnical-engineering services typically include the planning, collection, interpretation, and analysis of exploratory data from widely spaced borings and/or test pits. Field data are combined with results from laboratory tests of soil and rock samples obtained from field exploration (if applicable), observations made during site reconnaissance, and historical information to form one or more models of the expected subsurface conditions beneath the site. Local geology and alterations of the site surface and subsurface by previous and proposed construction are also important considerations. Geotechnical engineers apply their engineering training, experience, and judgment to adapt the requirements of the prospective project to the subsurface model(s). Estimates are made of the subsurface conditions that will likely be exposed during construction as well as the expected performance of foundations and other structures being planned and/or affected by construction activities. The culmination of these geotechnical-engineering services is typically a geotechnical-engineering report providing the data obtained, a discussion of the subsurface model(s), the engineering and geologic engineering assessments and analyses made, and the recommendations developed to satisfy the given requirements of the project. These reports may be titled investigations, explorations, studies, assessments, or evaluations. Regardless of the title used, the geotechnical-engineering report is an engineering interpretation of the subsurface conditions within the context of the project and does not represent a close examination, systematic inquiry, or thorough investigation of all site and subsurface conditions. Geotechnical-Engineering Services are Performed IRU6SHFL¿F3XUSRVHV3HUVRQVDQG3URMHFWV DQG$W6SHFL¿F7LPHV Geotechnical engineers structure their services to meet the specific needs, goals, and risk management preferences of their clients. A geotechnical-engineering study conducted for a given civil engineer will not likely meet the needs of a civil-works constructor or even a different civil engineer. Because each geotechnical-engineering study is unique, each geotechnical-engineering report is unique, prepared solely for the client. Likewise, geotechnical-engineering services are performed for a specific project and purpose. For example, it is unlikely that a geotechnical- engineering study for a refrigerated warehouse will be the same as one prepared for a parking garage; and a few borings drilled during a preliminary study to evaluate site feasibility will not be adequate to develop geotechnical design recommendations for the project. Do not rely on this report if your geotechnical engineer prepared it: • for a different client; • for a different project or purpose; • for a different site (that may or may not include all or a portion of the original site); or • before important events occurred at the site or adjacent to it; e.g., man-made events like construction or environmental remediation, or natural events like floods, droughts, earthquakes, or groundwater fluctuations. Note, too, the reliability of a geotechnical-engineering report can be affected by the passage of time, because of factors like changed subsurface conditions; new or modified codes, standards, or regulations; or new techniques or tools. If you are the least bit uncertain about the continued reliability of this report, contact your geotechnical engineer before applying the recommendations in it. A minor amount of additional testing or analysis after the passage of time – if any is required at all – could prevent major problems. Read this Report in Full Costly problems have occurred because those relying on a geotechnical- engineering report did not read the report in its entirety. Do not rely on an executive summary. Do not read selective elements only. Read and refer to the report in full. You Need to Inform Your Geotechnical Engineer About Change Your geotechnical engineer considered unique, project-specific factors when developing the scope of study behind this report and developing the confirmation-dependent recommendations the report conveys. Typical changes that could erode the reliability of this report include those that affect: • the site’s size or shape; • the elevation, configuration, location, orientation, function or weight of the proposed structure and the desired performance criteria; • the composition of the design team; or • project ownership. As a general rule, always inform your geotechnical engineer of project or site changes – even minor ones – and request an assessment of their impact. The geotechnical engineer who prepared this report cannot accept responsibility or liability for problems that arise because the geotechnical engineer was not informed about developments the engineer otherwise would have considered. Most of the “Findings” Related in This Report Are Professional Opinions Before construction begins, geotechnical engineers explore a site’s subsurface using various sampling and testing procedures. Geotechnical engineers can observe actual subsurface conditions only at those specific locations where sampling and testing is performed. The data derived from that sampling and testing were reviewed by your geotechnical engineer, who then applied professional judgement to form opinions about subsurface conditions throughout the site. Actual sitewide-subsurface conditions may differ – maybe significantly – from those indicated in this report. Confront that risk by retaining your geotechnical engineer to serve on the design team through project completion to obtain informed guidance quickly, whenever needed. This Report’s Recommendations Are &RQ¿UPDWLRQ'HSHQGHQW The recommendations included in this report – including any options or alternatives – are confirmation-dependent. In other words, they are not final, because the geotechnical engineer who developed them relied heavily on judgement and opinion to do so. Your geotechnical engineer can finalize the recommendations only after observing actual subsurface conditions exposed during construction. If through observation your geotechnical engineer confirms that the conditions assumed to exist actually do exist, the recommendations can be relied upon, assuming no other changes have occurred. The geotechnical engineer who prepared this report cannot assume responsibility or liability for confirmation-dependent recommendations if you fail to retain that engineer to perform construction observation. This Report Could Be Misinterpreted Other design professionals’ misinterpretation of geotechnical- engineering reports has resulted in costly problems. Confront that risk by having your geotechnical engineer serve as a continuing member of the design team, to: • confer with other design-team members; • help develop specifications; • review pertinent elements of other design professionals’ plans and specifications; and • be available whenever geotechnical-engineering guidance is needed. You should also confront the risk of constructors misinterpreting this report. Do so by retaining your geotechnical engineer to participate in prebid and preconstruction conferences and to perform construction- phase observations. Give Constructors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can shift unanticipated-subsurface-conditions liability to constructors by limiting the information they provide for bid preparation. To help prevent the costly, contentious problems this practice has caused, include the complete geotechnical-engineering report, along with any attachments or appendices, with your contract documents, but be certain to note conspicuously that you’ve included the material for information purposes only. To avoid misunderstanding, you may also want to note that “informational purposes” means constructors have no right to rely on the interpretations, opinions, conclusions, or recommendations in the report. Be certain that constructors know they may learn about specific project requirements, including options selected from the report, only from the design drawings and specifications. Remind constructors that they may perform their own studies if they want to, and be sure to allow enough time to permit them to do so. Only then might you be in a position to give constructors the information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. Conducting prebid and preconstruction conferences can also be valuable in this respect. Read Responsibility Provisions Closely Some client representatives, design professionals, and constructors do not realize that geotechnical engineering is far less exact than other engineering disciplines. This happens in part because soil and rock on project sites are typically heterogeneous and not manufactured materials with well-defined engineering properties like steel and concrete. That lack of understanding has nurtured unrealistic expectations that have resulted in disappointments, delays, cost overruns, claims, and disputes. To confront that risk, geotechnical engineers commonly include explanatory provisions in their reports. Sometimes labeled “limitations,” many of these provisions indicate where geotechnical engineers’ responsibilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly. Geoenvironmental Concerns Are Not Covered The personnel, equipment, and techniques used to perform an environmental study – e.g., a “phase-one” or “phase-two” environmental site assessment – differ significantly from those used to perform a geotechnical-engineering study. For that reason, a geotechnical-engineering report does not usually provide environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated subsurface environmental problems have led to project failures. If you have not obtained your own environmental information about the project site, ask your geotechnical consultant for a recommendation on how to find environmental risk-management guidance. 2EWDLQ3URIHVVLRQDO$VVLVWDQFHWR'HDOZLWK 0RLVWXUH,Q¿OWUDWLRQDQG0ROG While your geotechnical engineer may have addressed groundwater, water infiltration, or similar issues in this report, the engineer’s services were not designed, conducted, or intended to prevent migration of moisture – including water vapor – from the soil through building slabs and walls and into the building interior, where it can cause mold growth and material-performance deficiencies. Accordingly, proper implementation of the geotechnical engineer’s recommendations will not of itself be sufficient to prevent moisture infiltration. Confront the risk of moisture infiltration by including building-envelope or mold specialists on the design team. Geotechnical engineers are not building-envelope or mold specialists. Copyright 2019 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document or its wording as a complement to or as an element of a report of any kind. Any other firm, individual, or other entity that so uses this document without being a GBA member could be committing negligent or intentional (fraudulent) misrepresentation. Telephone: 301/565-2733 e-mail: info@geoprofessional.org www.geoprofessional.org