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HomeMy WebLinkAboutCC - GeoTech Report ik _. s �. r {� r + • p,r I, • i �r 1 � e k �imI CHNICAL INVESTIGATION CONNOR SQUARE APARTMENTS 604 & 528 West Broadway Avenue Meridian, ID PREPARED FOR: Ms. Shellie Robertson AKR Enterprises 3350 South Selatir Place Meridian, ID 83642 PREPARED BY: Atlas Technical Consultants, LLC April 6, 2021 2791 South Victory View Way B210709g Boise, ID 83709 �TrT—G7T�11 2791 South Victory View Way Boise, ID 83709 (208)376-4748 1 oneatlas.com April 6, 2021 Atlas No. B210709g Ms. Shellie Robertson AKR Enterprises 3350 South Selatir Place Meridian, ID 83642 Subject: Limited Geotechnical Investigation Connor Square Apartments 604 & 528 West Broadway Avenue Meridian, ID Dear Ms. Robertson: In compliance with your instructions, Atlas has conducted a limited soils exploration for the above referenced development. Fieldwork for this investigation was conducted on March 25 and 26, 2021. Data have been analyzed to evaluate pertinent geotechnical conditions. Results of this investigation, together with our recommendations, are to be found in the following report. We have provided a PDF copy for your review and distribution. Often, questions arise concerning soil conditions because of design and construction details that occur on a project. Atlas would be pleased to continue our role as geotechnical engineers during project implementation. If you have any questions, please call us at (208) 376-4748. Respectfully submitted, Jacob Schlador, PE Elizabeth Brown, PE Geotechnical Engineer Geotechnical Services Manager Distribution: Shellie Robertson, AKR Enterprises, LLC (PDF Copy); Joe Canning, B&A Engineers (PDF Copy) �TrT-G7T�1 CONTENTS 1. INTRODUCTION................................................................................................................. 1 1.1 Project Description ..................................................................................................... 1 1.2 Authorization .............................................................................................................. 1 1.3 Scope of Investigation................................................................................................ 1 2. SITE DESCRIPTION........................................................................................................... 2 2.1 Regional Geology....................................................................................................... 2 2.2 General Site Characteristics....................................................................................... 2 3. SOILS EXPLORATION....................................................................................................... 2 3.1 Exploration and Sampling Procedures........................................................................ 2 3.2 Soil and Sediment Profile........................................................................................... 3 4. SITE HYDROLOGY............................................................................................................ 3 4.1 Groundwater.............................................................................................................. 4 4.2 Soil Infiltration Rates .................................................................................................. 4 4.3 Infiltration Testing....................................................................................................... 5 5. GENERAL COMMENTS..................................................................................................... 5 6. REFERENCES ................................................................................................................... 6 TABLES Table1 — Groundwater Data.......................................................................................................4 APPENDICES Appendix I Warranty and Limiting Conditions Appendix II Vicinity Map Appendix III Site Map Appendix IV Geotechnical Investigation Test Pit Log Appendix V Geotechnical General Notes Appendix VI Important Information About This Geotechnical Engineering Report Atlas No. B210709g Page I i Copyright©2021 Atlas Technical Consultants 1. INTRODUCTION This report presents results of a geotechnical investigation and analysis. Information in support of groundwater and stormwater issues pertinent to the practice of Civil Engineering is included. Revisions in plans or drawings from those enumerated in this report should be brought to the attention of the soils engineer to determine whether changes in the provided recommendations are required. Deviations from noted subsurface conditions, if encountered during construction, should also be brought to the attention of the soils engineer. 1.1 Project Description The proposed development is in the west-central portion of the City of Meridian, Ada County, ID, and occupies a portion of the NW'/4SE'/4 of Section 12, Township 3 North, Range 1 West, Boise Meridian. This project will consist of frontage improvements along Broadway Avenue. New sidewalk, curb, gutter, and seepage beds will be constructed as part of the project. However, our scope of work is limited to providing drainage recommendations. Atlas has not been informed of the proposed grading plan. 1.2 Authorization Authorization to perform this exploration and analysis was given in the form of a written authorization to proceed from Ms. Shellie Robertson of AKR Enterprises to Clinton Wyllie of Atlas Technical Consultants (Atlas), on March 15, 2021. Said authorization is subject to terms, conditions, and limitations described in the Professional Services Contract entered into between AKR Enterprises and Atlas. Our scope of services for the proposed development has been provided in our proposal dated March 11, 2021 and repeated below. 1.3 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 testing of materials collected, and engineering analysis and evaluation of drainage materials. Our scope of work did not include foundation and pavement design recommendations. Atlas No. B210709g Page11 Copyright©2021 Atlas Technical Consultants 2. SITE DESCRIPTION 2.1 Regional Geology The project site is located within the western Snake River Plain of southwestern Idaho and eastern Oregon. The plain is a northwest trending rift basin, about 45 miles wide and 200 miles long, that developed about 14 million years ago (Ma) and has since been occupied sporadically by large inland lakes. Geologic materials found within and along the plain's margins reflect volcanic and fluvial/lacustrine sedimentary processes that have led to an accumulation of approximately 1 to 2 km of interbedded volcanic and sedimentary deposits within the plain. Along the margins of the plain, streams that drained the highlands to the north and south provided coarse to fine-grained sediments eroded from granitic and volcanic rocks, respectively. About 2 million years ago the last of the lakes was drained and since that time fluvial erosion and deposition has dominated the evolution of the landscape. The project site is underlain by "Sandy Alluvium of Side-Stream Valleys and Gulches" as mapped by Othberg and Stanford (1993). Locally, these deposits are composed of medium to coarse sand interbedded with silty fine sand and silt and are mostly derived from weathered granite and reworked Tertiary sediments of the Boise Foothills. The thickness of this unit is variable. Because of the relative youthfulness of these deposits they contain only minor pedogenic clay and calcium carbonate. 2.2 General Site Characteristics The site to be developed is approximately 0.64 acre in size. Currently the site exists as an undeveloped parcel of land. The site used to contain two separate residential structures fronting Broadway Avenue; however, these structures have since been demolished. The site is surrounded by existing residential properties in all directions. An irrigation canal was also present along the southern property boundary. Vegetation on the site consists primarily of mature trees, bunchgrass, and grasses. The site is relatively flat and level. 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 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. 3. SOILS EXPLORATION 3.1 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. Atlas No. B210709g Page12 Copyright©2021 Atlas Technical Consultants rrN+M= 'T�� __1 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, placed in sealed containers, and transported to our laboratory for additional testing. Subsurface materials have been described in detail on logs provided in the Appendix. Results of field and laboratory tests are also presented in the Appendix. Atlas recommends that these logs not be used to estimate fill material quantities. 3.2 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 Appendix. At ground surface within the test pits were silt soils. Silts were brown to light brown, slightly moist, medium stiff to very stiff, and contained fine-grained sand. Organic materials were encountered to depths of 1.4 feet bgs. Underlying the surficial silt soils were silty sand sediments and sandy silt soils, in test pit 1 and 2, respectively. Silty sands and sandy silts were brown to light brown, dry, medium dense to dense/very stiff, and contained fine to medium-grained sand. In test pit 1, clayey gravel with sand sediments were encountered beneath the silty sand sediments. Clayey gravels with sand were brown, dry to slightly moist, dense to very dense, and contained fine to coarse-grained sand, fine to coarse gravel, and 5-inch-minus cobbles. Beneath the clayey gravels with sand in test pit 1 were poorly graded gravel with clay and sand sediments. Poorly graded gravels with clay and sand were light brown, slightly moist to saturated, dense, and contained fine to coarse-grained sand, fine to coarse gravel, and 5-inch-minus cobbles. Beneath the sandy silts in test pit 2 were poorly graded gravel with sand sediments. Poorly graded gravels with sand were light brown, dry, medium dense to dense, and contained fine to coarse-grained sand, fine to coarse gravel, and 8-inch-minus cobbles. Competency of test pit sidewalls 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. 4. SITE HYDROLOGY Existing surface drainage conditions are defined in the General Site Characteristics section. Information provided in this section is limited to observations made at the time of the investigation. Either regional or local ordinances may require information beyond the scope of this report. Atlas No. B210709g Page 13 Copyright©2021 Atlas Technical Consultants 4.1 Groundwater During this field investigation, groundwater was encountered in test pit 1 at a depth of 8.8 feet bgs. Soil moistures in the test pits were generally dry to slightly moist within surficial soils. Within the poorly graded gravels with clay and sand in test pit 1, 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. Atlas has previously performed 7 geotechnical investigations within 0.35 mile of the project site. Information from these investigations has been provided in the table below. Table 1 — Groundwater Data Date Approximate Distance Di undwater Depth from Site (mile) rm"&O (feet . . January 2007 0.33 Southwest 11.6 January 2010 0.35 Southwest 10.9 to 11.1 November 2012 0.27 West 8.0 to 9.0 April 2016 0.30 Southeast 6.6 to 8.4 September 2016 0.31 South 13.1 to 14.5 November 2016 0.23 East Not Encountered to 7.8 September 2018 0.32 South 11.7 to 15.7 For construction purposes, groundwater depth can be assumed to remain greater than 6.5 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 the piezometer installed in test pit 1. If desired, Atlas is available to perform this monitoring. 4.2 Soil Infiltration Rates Soil permeability, which is a measure of the ability of a soil to transmit a fluid, was tested in the field. For this report, an estimation of infiltration is also presented using generally recognized values for each soil type and gradation. Of soils comprising the generalized soil profile for this study, silt soils and silt with sand 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. Clayey gravel with sand sediments and poorly graded gravel with clay and sand sediments typically have infiltration rates ranging from 2 to 6 inches per hour. Silty sand sediments usually display rates of 4 to 8 inches per hour. Poorly graded gravel with sand sediments typically exhibit infiltration values in excess of 12 inches per hour. However, the presence of groundwater will significantly reduce these estimated rates. Atlas No. B210709g Page14 Copyright©2021 Atlas Technical Consultants 4.3 Infiltration Testing Infiltration testing was conducted in general accordance with the Ada County Highway District (ACHD) Policy Manual. The test pit area will need to be re-excavated and compacted prior to construction of structures that will be sensitive to settlement. The test location was presoaked prior to testing. Pre-soaking increases soil moistures, which allows the tested soils to reach a saturated condition more readily during testing. Saturation of the tested soils is desirable in order to isolate the vertical component of infiltration by inhibiting horizontal seepage during testing. On March 26, 2021, testing was conducted within poorly graded gravel with sand sediments at a depth of 6.1 feet bgs in test pit 2. An infiltration rate in excess of 16 inches per hour was obtained during testing. Per the ACHD Policy Manual requirements, the maximum design soil infiltration rate shall not exceed 8 inches per hour. Therefore, a design infiltration rate of 8 inches per hour should be used for the poorly graded gravel with sand sediments encountered at depth across the site. It should be confirmed that infiltration facilities are constructed on relatively silt-free and clay-free poorly graded gravel with sand sediments. Atlas recommends that all infiltration facilities be constructed in accordance with the local municipality requirements. 5. GENERAL COMMENTS Based on the subsurface conditions encountered during this investigation and available information, the site is adequate for the planned construction. When plans and specifications are complete, consultation with Atlas must be arranged as supplementary recommendations may be required. Suitability of subgrade soils and compaction of structural fill materials must be verified by Atlas personnel prior to placement of structural elements. Additionally, monitoring and testing should be performed to verify that suitable materials are used for structural fill and that proper placement and compaction techniques are utilized. Atlas No. B210709g Page 15 Copyright©2021 Atlas Technical Consultants 6. REFERENCES Ada County Highway District (ACHD) (2017). Ada County Highway District Policy Manual (August 2017). [Online] Available: <http://www.achdidaho.org/AboutACHD/PolicyManual.aspx> (2021). American Society for Testing and Materials (ASTM) (2017). Standard Practice for Classification of Soils for Engineering Purposes(Unified Soil Classification System):ASTM D2488.West Conshohocken, PA:ASTM. Othberg, K. L. and Stanford, L. A., Idaho Geologic Society (1993). Geologic Map of the Boise Valley and Adjoining Area, Western Snake River Plain, Idaho. (scale 1:100,000). Boise, ID: Joslyn and Morris. Atlas No. B210709g Page 16 Copyright©2021 Atlas Technical Consultants Appendix I WARRANTY AND LIMITING CONDITIONS Atlas 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 incurred 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 identified 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, Atlas 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 Atlas 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 Atlas No. B210709g Page 17 Copyright©2021 Atlas Technical Consultants 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. This report is also limited to information available at the time it was prepared. In the event additional information is provided to Atlas 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 geoenviron mental investigation or a Phase II/III Environmental Site Assessment. If environmental services are needed, Atlas can provide, via a separate contract, those personnel who are trained to investigate and delineate soil and water contamination. Atlas No. B210709g Page 18 Copyright©2021 Atlas Technical Consultants I / , © Delorme Street Atlas ��� .�■ -Not to Scale W, LEGEND Te Approximate Site Location win ■s i■■■■��■ate Site Location IL Conor Square Apartments 604 and 528 Broadway Avenue Meridian,ID F R .. '. . D' 21 , Drawing:B210709g 2791 S.Victory View Way Phone: ,: . . .8 Site Map Figure 2 NOTES: N •Not to Scale — — — — — — — — — — — — — — IDAHOAVENUE— — — — — — — — — — — — — — — — — — — — — LEGEND Approximate Site — - - — Boundary Approximate Atlas Test Pit Location Approximate Atlas Test Pit Location with Piezometer I I I I I _ _ I I I I I T� — — —T02 Conor Square Apartments 604— — — — — — — — — — — — — — —BROADWAYAVENUE— — — — — — — — — — — — — — — — — — — Mer andidian,,ID Broadway Avenue MerD To NW 4TH STREET Drawn by:JBS April 2,2021 Drawing:B210709g 2791 S.Victory View Way Phone: (208)376-4748 Boise,ID 83709 Fax: (208)322-6515 Web: oneatlas.com Appendix IV GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-1 Latitude: 43.61030 Date Advanced: March 25, 2021 Longitude: -116.40108 Excavated by: Client Supplied Excavator Depth to Water Table: 8.8 feet bgs Logged by: Elizabeth Brown, PE Total Depth: 9.0 feet bgs Depth Field Description and USCS Soil and Sample Sample Depth Lab • .$) Sediment Classification • • . Test ID h . Silt with Sand (ML): Brown, slightly moist, 0.0-2.8 medium stiff to very stiff, with fine-grained 1.0-2.25 sand. --Organics to a depth of 1.4 feet bgs. Silty Sand (SM): Brown to light brown, dry, 2.8-4.4 medium dense to dense, with fine to medium- grained sand. Clayey Gravel with Sand (GC): Brown, dry to 4.4-6.1 slightly moist, dense to very dense,with fine to coarse-grained sand, fine to coarse gravel, and 5-inch-minus cobbles. Poorly Graded Gravel with Clay and Sand (GP-GC): Light brown, slightly moist to 6.1-9.0 saturated, dense, with fine to coarse-grained sand, fine to coarse gravel, and 5-inch-minus cobbles. Notes:See Site Map for test pit location. Piezometer installed to a depth of 9.0 feet bgs. Atlas No. 13210709g Page 111 Copyright©2021 Atlas Technical Consultants �TrT-G7T�1 GEOTECHNICAL INVESTIGATION TEST PIT LOG Test Pit Log#: TP-2 Latitude: 43.61031 Date Advanced: March 25, 2021 Longitude: -116.40068 Excavated by: Client Supplied Excavator Depth to Water Table: Not Encountered Logged by: Jacob Schlador, PE Total Depth: 6.1 feet bgs Depth Eield Description and USCS Soil and Sample Sample Depth Qp Lab •• Jiment Classification • bgs) Test ID Silt (ML): Brown to light brown, slightly moist, 0.0-1.9 stiff to very stiff, with fine-grained sand. 1.5-2.0 --Organics to a depth of 1.0 foot bgs. 1.9-3.2 Sandy Silt (ML): Light brown, dry, very stiff, with fine to medium-grained sand. Poorly Graded Gravel with Sand (GP): Light 3.2-6.1 brown, dry, medium dense to dense, with to coarse-grained sand, fine to coarse gravel, and 8-inch-minus cobbles. Notes:See Site Map for test pit location. Infiltration testing conducted at a depth of 6.1 feet bgs. Atlas No. B210709g Page112 Copyright©2021 Atlas Technical Consultants �TrT-G7Tdr-W1 Appendix V GEOTECHNICAL GENERAL NOTES Unified Soil Classification System Major Divisions Symbol Soil Descriptions Gravel & GW Well-graded ravels; ravel/sand mixtures with little or no fines Coarse- Gravelly Soils GP Poorl - raded ravels; ravel/sand mixtures with little or no fines Grained < 50% GM Silty gravels; poorly-graded ravel/sand/silt mixtures Soils < coarse GC Clayey gravels; poorly-graded gravel/sand/clay mixtures 50% Sand & Sandy SW Well-graded sands; gravelly sands with little or no fines passes Soils > 50% SP Poorl - raded sands; gravelly sands with little or no fines No.200 coarse SM Silty sands; poorly-graded sand/gravel/silt mixtures sieve fraction Sc Clayey sands; poorly-graded sand/gravel/clay mixtures Fine- ML Inorganic silts; sandy, gravellyor clayey silts Grained Silts & Clays CL Lean clays; inorganic, gravelly, sandy, or silty, low to medium- Soils > LL < 50 plasticity clays 50% OL Organic, low-plasticity clays and silts passes MH Inorganic, elastic silts; sand ravel) or clayey elastic silts No.200 Silts &Clays CH Fat clays; high-plasticity, inorganic clays sieve LL > 50 OH Organic, medium to high-plasticity clays and silts Highly Organic Soils PT Peat, humus, h dric soils with high organic content Relative Density • Consistency oisture Contentand Cementation • Class ificatlorh� Coarse-Grained Soils SPT Blow Counts N Description Field Test Very Loose: <4 Dry Absence of moisture, dry to touch Loose: 4-10 Slightly Moist Damp, but no 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 Soft: 2-4 slight finger pressure Medium Stiff: 4-8 Moderate Crumbles or breaks with Stiff: 8-15 considerable finger pressure Very Stiff: 15-30 Strong Will not crumble or break with finger Hard: >30 pressure 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 Silts: 0.075 to 0.005 mm strength, tsf Clays: < 0.005 mm V vane value, ultimate shearing strength, tsf Atlas No. B210709g Page113 Copyright©2021 Atlas Technical Consultants IMPOPIOnt InfOPM81100 Rhout ■ GeolechnicalmEngineeping 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) will not likely meet the needs of a civil-works constructor or even a has prepared this advisory to help you—assumedly different civil engineer.Because each geotechnical-engineering study a client representative—interpret and apply this is unique,each geotechnical-engineering report is unique,prepared geotechnical-engineering report as effectively as solely for the client. possible. In that way, you can benefit from a lowered Likewise,geotechnical-engineering services are performed for a specific exposure to problems associated with subsurface project and purpose.For example,it is unlikely that a geotechnical- conditions at project sites and development of engineering study for a refrigerated warehouse will be the same as them that,for decades, have been a principal cause one prepared for a parking garage;and a few borings drilled during of construction delays, cost overruns, claims, a preliminary study to evaluate site feasibility will not be adequate to and disputes. If you have questions or want more develop geotechnical design recommendations for the project. information about any of the issues discussed herein, contact your GBA-member geotechnical engineer. Do not rely on this report if your geotechnical engineer prepared it: Active engagement in GBA exposes geotechnical • for a different client; engineers to a wide array of risk-confrontation • for a different project or purpose; techniques that can be of genuine benefit for • for a different site(that may or may not include all or a portion of everyone involved with a construction project. the original site);or before important events occurred at the site or adjacent to it; e.g.,man-made events like construction or environmental Understand the Geotechnical-Engineering Services remediation,or natural events like floods,droughts,earthquakes, Provided for this Report or groundwater fluctuations. Geotechnical-engineering services typically include the planning, collection,interpretation,and analysis of exploratory data from Note,too,the reliability of a geotechnical-engineering report can widely spaced borings and/or test pits.Field data are combined be affected by the passage of time,because of factors like changed with results from laboratory tests of soil and rock samples obtained subsurface conditions;new or modified codes,standards,or from field exploration(if applicable),observations made during site regulations;or new techniques or tools.If you are the least bit uncertain reconnaissance,and historical information to form one or more models about the continued reliability of this report,contact your geotechnical of the expected subsurface conditions beneath the site.Local geology engineer before applying the recommendations in it.A minor amount and alterations of the site surface and subsurface by previous and of additional testing or analysis after the passage of time-if any is proposed construction are also important considerations.Geotechnical required at all-could prevent major problems. engineers apply their engineering training,experience,and judgment to adapt the requirements of the prospective project to the subsurface Read this Report in Full model(s). Estimates are made of the subsurface conditions that Costly problems have occurred because those relying on a geotechnical- will likely be exposed during construction as well as the expected engineering report did not read the report in its entirety.Do not rely on performance of foundations and other structures being planned and/or an executive summary.Do not read selective elements only.Read and affected by construction activities. refer to the report in full. The culmination of these geotechnical-engineering services is typically a You Need to Inform Your Geotechnical Engineer geotechnical-engineering report providing the data obtained,a discussion About Change of the subsurface model(s),the engineering and geologic engineering Your geotechnical engineer considered unique,project-specific factors assessments and analyses made,and the recommendations developed when developing the scope of study behind this report and developing to satisfy the given requirements of the project.These reports may be the confirmation-dependent recommendations the report conveys. titled investigations,explorations,studies,assessments,or evaluations. Typical changes that could erode the reliability of this report include Regardless of the title used,the geotechnical-engineering report is an those that affect: engineering interpretation of the subsurface conditions within the context - the site's size or shape; of the project and does not represent a close examination,systematic inquiry,or thorough investigation of all site and subsurface conditions. the elevation,configuration,location,orientation, function or weight of the proposed structure and Geotechnical-Engineering Services are Performed the desired performance criteria; the composition of the design team;or for Specific Purposes, Persons, and Projects, . project ownership. and At Specific Times Geotechnical engineers structure their services to meet the specific As a general rule,always inform your geotechnical engineer of project needs,goals,and risk management preferences of their clients.A or site changes-even minor ones-and request an assessment of their geotechnical-engineering study conducted for a given civil engineer impact.The geotechnical engineer who prepared this report cannot accept responsibility or liability for problems that arise because the geotechnical conspicuously that you've included the material for information purposes engineer was not informed about developments the engineer otherwise only.To avoid misunderstanding,you may also want to note that would have considered. "informational purposes"means constructors have no right to rely on the interpretations,opinions,conclusions,or recommendations in the Most Of the "Findings" Related in This Report report.Be certain that constructors know they may learn about specific Are Professional Opinions project requirements,including options selected from the report,only Before construction begins,geotechnical engineers explore a site's from the design drawings and specifications.Remind constructors subsurface using various sampling and testing procedures.Geotechnical that they may perform their own studies if they want to,and be sure to engineers can observe actual subsurface conditions only at those specific allow enough time to permit them to do so.Only then might you be in locations where sampling and testing is performed.The data derived from a position to give constructors the information available to you,while that sampling and testing were reviewed by your geotechnical engineer, requiring them to at least share some of the financial responsibilities who then applied professional judgement to form opinions about stemming from unanticipated conditions.Conducting prebid and subsurface conditions throughout the site.Actual sitewide-subsurface preconstruction conferences can also be valuable in this respect. conditions may differ-maybe significantly-from those indicated in this report.Confront that risk by retaining your geotechnical engineer Read Responsibility Provisions Closely to serve on the design team through project completion to obtain Some client representatives,design professionals,and constructors do informed guidance quickly,whenever needed. not realize that geotechnical engineering is far less exact than other engineering disciplines.This happens in part because soil and rock on This Report's Recommendations Are project sites are typically heterogeneous and not manufactured materials Confirmation-Dependent with well-defined engineering properties like steel and concrete.That The recommendations included in this report-including any options or lack of understanding has nurtured unrealistic expectations that have alternatives-are confirmation-dependent.In other words,they are not resulted in disappointments,delays,cost overruns,claims,and disputes. final,because the geotechnical engineer who developed them relied heavily TO confront that risk,geotechnical engineers commonly include on judgement and opinion to do so.Your geotechnical engineer can finalize explanatory provisions in their reports.Sometimes labeled"limitations,' the recommendations only after observing actual subsurface conditions many of these provisions indicate where geotechnical engineers' exposed during construction.If through observation your geotechnical responsibilities begin and end,to help others recognize their own engineer confirms that the conditions assumed to exist actually do exist, responsibilities and risks.Read these provisions closely.Ask questions. the recommendations can be relied upon,assuming no other changes have Your geotechnical engineer should respond fully and frankly. occurred.The geotechnical engineer who prepared this report cannot assume responsibility or liabilityfor confirmation-dependent recommendations fyou Geoenvironmental Concerns Are Not Covered fail to retain that engineer to perform construction observation. The personnel,equipment,and techniques used to perform an environmental study-e.g.,a"phase-one"or"phase-two"enviromnental This Report Could Be Misinterpreted site assessment-differ significantly from those used to perform a Other design professionals'misinterpretation of geotechnical- geotechnical-engineering study.For that reason,a geotechnical-engineering engineering reports has resulted in costly problems.Confront that risk report does not usually provide environmental findings,conclusions,or by having your geotechnical engineer serve as a continuing member of recommendations;e.g.,about the likelihood of encountering underground the design team,to: storage tanks or regulated contaminants.Unanticipated subsurface • confer with other design-team members; environmental problems have led to project failures.If you have not • help develop specifications; obtained your own environmental information about the project site, review pertinent elements of other design professionals'plans and ask your geotechnical consultant for a recommendation on how to find specifications;and environmental risk-management guidance. • be available whenever geotechnical-engineering guidance is needed. Obtain Professional Assistance to Deal with You should also confront the risk of constructors misinterpreting this Moisture Infiltration and Mold report.Do so by retaining your geotechnical engineer to participate in While your geotechnical engineer may have addressed groundwater, prebid and preconstruction conferences and to perform construction- water infiltration,or similar issues in this report,the engineer's phase observations. services were not designed,conducted,or intended to prevent migration of moisture-including water vapor-from the soil Give Constructors a Complete Report and Guidance through building slabs and walls and into the building interior,where Some owners and design professionals mistakenly believe they can shift it can cause mold growth and material-performance deficiencies. unanticipated-subsurface-conditions liability to constructors by limiting Accordingly,proper implementation of the geotechnical engineer's the information they provide for bid preparation.To help prevent recommendations will not of itself be sufficient to prevent the costly,contentious problems this practice has caused,include the moisture infiltration.Confront the risk of moisture infiltration by complete geotechnical-engineering report,along with any attachments including building-envelope or mold specialists on the design team. or appendices,with your contract documents,but be certain to note Geotechnical engineers are not building-envelope or mold specialists. 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