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Home My WebLink AboutItem No 14 - Addendum to Report of Preliminary Subsurface Ex-OCRP.A August 18 2006 Beazer Homes 1300 South Boulevard Suite Charlotte North Carolina 28203-4265 Attention Mr Kevin Holdenrid Reference ADDENDUM TO REPORT OF PRELIMINARY SUBSURFACE EXPLORATION West End Development Charlotte North Carolina ESP Project No E4-UD42.300 Dear Mr Holdenrid ESP Associates P.A ESP is submitting this letter as an addendum to our Report of Preliminary Subsurface Exploration dated May 26 2006 We understand that Beazer Homes has requested allowable shallow foundation bearing capacity recommendations for specific areas of the site utilizing the current site plan information Our analysis began with review of our previous report of Preliminary Subsurface Exploration dated May 26 2006 the Mactec report titled Report of Preliminary Geotechnical Exploration dated April 18 2005 and the Preliminary Grading Plan provided by Tumbull Sigmon Design dated August 2006 The referenced plan includes proposed roadway grades but does not include any site grading information in building pad areas nor does it include current topography During our analysis we have made very general assumptions regarding potential grade changes in specific areas of the site In general we have assumed the eastern portion of the site would be cut as much as 10 feet the western and western central portions of the site would consist of filling operations potentially as high as to 10 feet with the central portion of the site remaining approximately on grade In addition many areas of existing fill and debris were encountered in our previous exploration These materials were predominately surveying P0 Box 7030 Charlotte NC 2824 704 583-4949 Fax 704 583-4950 wwwespassoc jates corn Addendum to Report of Preliminary Subsuiface Exploration ESP Project No E4-UD42.300 West End Development August 18 2006 observed to be unsuitable in nature and will require undercutting This analysis assumes that all existing fill encountered on the site will be undercut Any suitable existing fill soils that are removed may be replaced in structural areas Any unsuitable soils that were undercut shall be placed in non-structural areas or removed from the site It is our understanding that the surface layer of gravel located on-site is planned for re-use as structural fill material It is recommended that representative from our office be present during all undercutting operations in order to assist in delineating the unsuitable fill from any fill that may be re-used The following recommendations are general in nature and are based on the above assumptions and information If more specific analysis on individual buildings and/or specific areas of the site become necessary additional field exploration would be required Please refer to the attached Preliminary Grading Plan for more specific locations The following sections outline our allowable bearing pressure recommendations for fbundations bearing on residual soils and newly placed structural fill The recommendations are based on anticipated building settlement potentials of inch total and V2 inch differential These recommendations assume all existing fill will be removed and replaced Allowable bearing capacity recommendations for building foundations bearing in RESIDUAL SOILS Note N-value equal to or greater than 20 blows per foot bp Note N-value equal to or greater than bpf Note value equal to or greater than bpf Addendum to Report ofPreliminary Subsurface Exploration ESP Project No E4-UD42.300WestEndDevelopmentAugust18 2006 Allowable bearing capacity recommendations for building foundations bearing in STRUCTURAL FILL SOILS Area Recommended Allowable Based On Bearing Pressure psf 3000 Notes Note Structural fill compacted to at least 95%of the soils Standard Proctor maximum dry density Note The maximum dry density of the fill material must be at least 100 pounds per cubic foot pcf Due to the limited testing performed and the wide spacing of test pits and borings the possibility of deleterious inclusions and variable density material in variety of areas of the site is likelyWewouldalsoliketopomtoutthatourexperienceindicatesrockinweatheredboulderand massive form varies erratically in location and depth in the Piedmont Geologic Province which contains Charlotte North Carolina Therefore there is always potential that these materials could be encountered at shallow depths between the exploration locations If more detailed evaluation in specific areas of the site or specific building areas is desired additional field evaluations can be performed All foundation excavations should be evaluated in the field by representative of the geotechnical engineer to verify consistency with our previous findings The analysis and recommendations submitted herein are based in part upon the data obtained from the subsurface explorations The nature and extent of variations between the borings and test pits will not be known until construction is underway If variations appear evident then we request the opportunity to re-evaluate the recommendations of this report Also once final site grading plan is available our recommendations should be re-evaluated for any possible changes to the above soil bearing pressures In the event that any changes in the nature design or location of the structures are planned the conclusions and recommendations contained in this report will not be considered valid unless the changes are reviewed and conclusions modified or verified in writing by ESP The information contained in this letter is provided with respect to proposed building foundations only The information shall not be utilized for other purposes and/or structures planned for the site Addendum to Report of Preliminary Subsurface Exploration ESP Project No E4-UD42.300 West End Development August 18 2006 ESP appreciates the opportunity to assist you during this phase of the project If you should have any questions concerning this report or if we may be of further assistance please contact us Sincerely ESF Associates P.A ennifer Payne Project Manager Brian Welch PE N.C Registration No 21615 JAP/BFW/mb Copies Submitted Attachments Area Plan Figure LiD43OO SHEET TITLE SCALE N1S DATEAIRJ.II PROJECTDAV.1V DUNCHECKED BYRPWFIGURE WEST END AREA PLAN WEST END SITE 1TI ESP ASSOCIATES 14 flIl 372 Croinpten Street Charlotte 1/C 28273 704 504 4015