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Home My WebLink AboutSW6180602_Infiltration Report_20180613 March 23, 2018 Mr. Jason Sesler, P.E. Stantec 5565 Centerview Drive Raleigh, North Carolina 27606 Reference: Report of Seasonal High Water Table Estimation and Infiltration Testing Linden 230 kV 150509F01, Greenfield HRS Substation Linden, Harnett County, North Carolina ECS Project No. 33.4260 Dear Mr. Sesler: ECS Southeast, LLP (ECS) recently conducted a seasonal high water table (SHWT) estimation and infiltration testing within the substation footprint off of Horseshoe Bend Road in Linden, Harnett County, North Carolina. This letter, with attachments, is the report of our testing. Field Testing On March 22, 2018, ECS conducted an exploration of the subsurface soil conditions at four requested locations shown on the attached Boring Location Plan (Figure 1). ECS located the borings using GPS equipment. The purpose of this exploration was to obtain subsurface information of the in situ soils for the SCM area(s). ECS explored the subsurface soil and groundwater conditions by advancing one hand auger boring into the existing ground surface at each of the requested boring locations. ECS visually classified the subsurface soils and obtained representative samples of each soil type encountered. ECS also recorded the SHWT and groundwater elevation observed at the time of the hand auger borings. The attached Infiltration Testing Form provides a summary of the subsurface conditions encountered at the hand auger boring locations. The SHWT elevation was estimated at the boring locations below the existing grade elevation. A summary of the findings are as follows: Location SHWT B-1 74 inches B-2 62 inches B-3 72 inches B-4 70 inches ECS has conducted four infiltration tests utilizing a compact constant head permeameter near the hand auger borings in order to estimate the infiltration rate for the subsurface soils. The tests requested to be conducted at the surface elevation of each boring. Report of SHWT Estimation and Infiltration Testing Linden 230kV Substation Linden, Harnett County, North Carolina ECS Project No. 33.4260 March 23, 2018 2 Field Test Results Below is a summary of the infiltration test results: Location Description Depth Inches/ hour B-1 Tan/orange sandy CLAY 12 inches 0.0017 B-2 Brown/tan clayey SAND 10 inches 0.018 B-3 Orange sandy CLAY 12 inches 0.0013 B-4 Tan/gray clayey SAND 10 inches 0.080 Infiltration rates and SHWT may vary within the proposed site due to changes in elevation and subsurface conditions. Closure ECS’s analysis of the site has been based on our understanding of the site, the project information provided to us, and the data obtained during our exploration. If the project information provided to us is changed, please contact us so that our recommendations can be reviewed and appropriate revisions provided, if necessary. The discovery of any site or subsurface conditions during construction which deviate from the data outlined in this exploration should be reported to us for our review, analysis and revision of our recommendations, if necessary. The assessment of site environmental conditions for the presence of pollutants in the soil and groundwater of the site is beyond the scope of this geotechnical exploration. ECS appreciates the opportunity to provide our services to you on this project. If you have any questions concerning this report or this project, please contact us. Respectfully, ECS SOUTHEAST, LLP K. Brooks Wall W. Brandon Fulton, PSC, PWS, LSS Project Manager Environmental Department Manager bwall@ecslimited.com bfulton@ecslimited.com 910-686-9114 704-525-5152 Attachments: Figure 1 - Boring Location Plan Infiltration Testing Form ASFE Document APPROXIMATE BORING LOCATIONS SCALE SHOWN ABOVE Linden 230kV Substation Linden, Harnett County, North Carolina ECS Project # 33.4260 March 22, 2018 KBW Figure 1– Boring Location Plan Provided by: Google Earth B-1 B-2 N W S E N W S E B-3 B-4 Infiltration Testing Form Linden 230kV 150509F01, Greenfield HRS Substation Linden, Harnett County, North Carolina ECS Project No. 33.4260 March 22, 2018 Location Depth USCS Soil Description B-1 0-10” SC Tan clayey SAND 10”-48” CL Tan/orange sandy CLAY 48”-70” SW T/o/g fine to coarse SAND w/ clay lens Seasonal High Water Table was estimated to be at 74 inches below the existing grade elevation. Test was conducted at 12 inches below existing grade elevation Infiltration Rate: 0.0017 inches per hour Location Depth USCS Soil Description B-2 0-16” SC Brown/tan clayey SAND 16”-66” CL Tan/orange sandy CLAY Seasonal High Water Table was estimated to be at 62 inches below the existing grade elevation. Test was conducted at 10 inches below existing grade elevation Infiltration Rate: 0.018 inches per hour Location Depth USCS Soil Description B-3 0-10” SC Tan clayey SAND 10”-36” CL Orange sandy CLAY 36”-96” SW T/o/g fine to coarse SAND w/ clay lens Seasonal High Water Table was estimated to be at 72 inches below the existing grade elevation. Groundwater was observed at 96 inches below existing grade elevation Test was conducted at 12 inches below existing grade elevation Infiltration Rate: 0.0013 inches per hour Infiltration Testing Form Linden 230kV 150509F01, Greenfield HRS Substation Linden, Harnett County, North Carolina ECS Project No. 33.4260 March 22, 2018 Location Depth USCS Soil Description B-4 0-18” SC Tan/gray clayey SAND 18”-40” CL Tan/orange sandy CLAY 10”-70” SW T/o/g fine to coarse SAND w/ clay lens Seasonal High Water Table was estimated to be at 70 inches below the existing grade elevation. Test was conducted at 10 inches below existing grade elevation Infiltration Rate: 0.080 inches per hour Important Information About Your Geotechnical Engineering Report Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes The following information is provided to help you manage your risks. Geotechnical Services Are Performed for Speciﬁ c Purposes, Persons, and Projects Geotechnical engineers structure their services to meet the speciﬁ c needs of their clients. A geotechnical engineering study conducted for a civil engineer may not fulﬁ ll the needs of a construction contractor or even another civil engineer. Because each geotechnical engineering study is unique, each geo- technical engineering report is unique, prepared solely for the client. No one except you should rely on your geotechnical engineering report without ﬁ rst conferring with the geotechnical engineer who prepared it. And no one - not even you - should apply the report for any purpose or project except the one originally contemplated. Read the Full Report Serious problems have occurred because those relying on a geotechnical engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only. A Geotechnical Engineering Report Is Based on A Unique Set of Project-Speciﬁ c Factors Geotechnical engineers consider a number of unique, project-speciﬁ c factors when establishing the scope of a study. Typical factors include: the client’s goals, objectives, and risk management preferences; the general nature of the structure involved, its size, and conﬁ guration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless the geotechnical engi- neer who conducted the study speciﬁ cally indicates otherwise, do not rely on a geotechnical engineering report that was: • not prepared for you, • not prepared for your project, • not prepared for the speciﬁ c site explored, or • completed before important project changes were made. Typical changes that can erode the reliability of an existing geotechnical engineering report include those that affect: • the function of the proposed structure, as when it’s changed from a parking garage to an ofﬁ ce building, or from alight industrial plant to a refrigerated warehouse, • elevation, conﬁ guration, location, orientation, or weight of the proposed structure, • composition of the design team, or • project ownership. As a general rule, always inform your geotechnical engineer of project changes - even minor ones - and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed. Subsurface Conditions Can Change A geotechnical engineering report is based on conditions that existed at the time the study was performed. Do not rely on a geotechnical engineering report whose adequacy may have been affected by: the passage of time; by man-made events, such as construction on or adjacent to the site; or by natu- ral events, such as ﬂ oods, earthquakes, or groundwater ﬂ uctuations. Always contact the geotechnical engineer before applying the report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems. Most Geotechnical Findings Are Professional Opinions Site exploration identiﬁ es subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engineers review ﬁ eld and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ-sometimes signiﬁ cantly from those indi- cated in your report. Retaining the geotechnical engineer who developed your report to provide construction observation is the most effective method of managing the risks associated with unanticipated conditions. A Report’s Recommendations Are Not Final Do not overrely on the construction recommendations included in your re- port. Those recommendations are not ﬁ nal, because geotechnical engineers develop them principally from judgment and opinion. Geotechnical engineers can ﬁ nalize their recommendations only by observing actual subsurface conditions revealed during construction. The geotechnical engi- neer who developed your report cannot assume responsibility or liability for the report’s recommendations if that engineer does not perform construction observation. A Geotechnical Engineering Report Is Subject to Misinterpretation Other design team members’ misinterpretation of geotechnical engineer- ing reports has resulted in costly problems. Lower that risk by having your geotechnical engineer confer with appropriate members of the design team after submitting the report. Also retain your geotechnical engineer to review pertinent elements of the design team’s plans and speciﬁ cations. Contractors can also misinterpret a geotechnical engineering report. Reduce that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing construction observation. Do Not Redraw the Engineer’s Logs Geotechnical engineers prepare ﬁ nal boring and testing logs based upon their interpretation of ﬁ eld logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical engineering report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separating logs from the report can elevate risk. Give Contractors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give con- tractors the complete geotechnical engineering report, but preface it with a clearly written letter of transmittal. In that letter, advise contractors that the report was not prepared for purposes of bid development and that the report’s accuracy is limited; encourage them to confer with the geotechnical engineer who prepared the report (a modest fee may be required) and/or to conduct ad- ditional study to obtain the speciﬁ c types of information they need or prefer. A prebid conference can also be valuable. Be sure contractors have sufﬁ cient time to perform additional study. Only then might you be in a position to give contractors the best information available to you, while requiring them to at least share some of the ﬁ nancial responsibilities stemming from unantici- pated conditions. Read Responsibility Provisions Closely Some clients, design professionals, and contractors do not recognize that geotechnical engineering is far less exact than other engineering disciplines. This lack of understanding has created unrealistic expectations that have led to disappointments, claims, and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of 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 equipment, techniques, and personnel used to perform a geoenviron- mental study differ signiﬁ cantly from those used to perform a geotechnical study. For that reason, a geotechnical engineering report does not usually re- late any geoenvironmental ﬁ ndings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated environmental problems have led to numerous project failures. If you have not yet obtained your own geoenvironmental in- formation, ask your geotechnical consultant for risk management guidance. Do not rely on an environmental report prepared for someone else. Obtain Professional Assistance To Deal with Mold Diverse strategies can be applied during building design, construction, op- eration, and maintenance to prevent signiﬁ cant amounts of mold from grow- ing on indoor surfaces. To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a comprehensive plan, and executed with diligent oversight by a professional mold prevention consultant. Because just a small amount of water or moisture can lead to the development of severe mold infestations, a number of mold prevention strategies focus on keeping building surfaces dry. While groundwater, wa- ter inﬁ ltration, and similar issues may have been addressed as part of the geotechnical engineering study whose ﬁ ndings are conveyed in-this report, the geotechnical engineer in charge of this project is not a mold prevention consultant; none of the services performed in connection with the geotechnical engineer’s study were designed or conducted for the purpose of mold prevention. Proper implementation of the recommendations conveyed in this report will not of itself be sufﬁ cient to prevent mold from growing in or on the struc- ture involved. Rely on Your ASFE-Member Geotechnical Engineer For Additional Assistance Membership in ASFE/The Best People on Earth exposes geotechnical engi- neers to a wide array of risk management techniques that can be of genuine beneﬁ t for everyone involved with a construction project. Confer with your ASFE-member geotechnical engineer for more information. 8811 Colesville Road/Suite G106, Silver Spring, MD 20910 Telephone:’ 301/565-2733 Facsimile: 301/589-2017 e-mail: info@asfe.org www.asfe.org Copyright 2004 by ASFE, Inc. Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with ASFE’s speciﬁ c written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of ASFE, and only for purposes of scholarly research or book review. Only members of ASFE may use this document as a complement to or as an element of a geotechnical engineering report. Any other ﬁ rm, individual, or other entity that so uses this document without being anASFE member could be committing negligent or intentional (fraudulent) misrepresentation. IIGER06045.0M The Best People on Earth