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Park West CC(4)-CS 931210 l rracon CONSULTANTS, INC. '258~ S'.em, r-orS F-eewa-:' SJte 907 C'a as Tee'as *5234 Cemeqt B. Bommard3 DE - 1993 _~.,~ D a~,e :s'ae. PE December 10, 1993 Mr. Mike Nuzum ~ ,..~'~ Dupey Management Corporation 7557c/° James Harwick and Partners, lnC.Rambler Road ~{4~ ~ Suite 367 Dallas, Texas 75231 ~ Attn: Mr. Robert H. James, AIA Re: Addition~[..P~,,ement Recommendations Proposect M J Design~ Corporate Headquarters and Distribution Center Coppell, Texas Job No. 17931033 Gentlemen: At the request of Mr. Dennis Chovan of Albert Halff and Associates, we are providing additional clarification regarding alternate pavement sections for the above referenced project. It is our understanding that concrete pavement sections will be used for the facility. Our original geotechnical report for this project recommended a 5-inch thick concrete section placed on a subgrade stabilized with hydrated lime for automobile and light truck parking areas. A 6-inch thick concrete section was suggested /hr drive lanes and 7 inches of concrete was recommended in heavy truck areas, and both of these pavement sections are based on the assumption that the subgrade will be stabilized. Offices of The Terracon Companies, Inc. Geotechnical, Environmental and Materials Engineers ~r.zcqa T~CSC-" · Co oradc Coorado Spr'ngs. Der..-e. F~ Co,I rS, G'ee'ey Lcqg~or: · Ida"c Bc se · ;Iqrc:s ~lo¢,"lll~g:O~ C~,Jcago ~oc< Is a~d · Iowa. Ce.nar Fai s Ceca: '~.aods Da~enpc-t Oas Mo:nas. Sto'm Lake · Kansas _e¢.exa Tcpeka. Web la · M c-esc:a St Pab, · Missc,~r, Ka"sas C:y · Nebras,~a. Lmcoln. Omaha · Nevada -as Vegas · O< at'oma O4 a-cma C:7 Tv sa · Texas: Da :as. Fo-I We'.'.'~ · U.'.an Sa,: Lake C,Ik · Wyom.n3 Cheyenne QUALITY ENGINEERING SINCE 1965 Mr. Mike Nuzum Terracon Job No. 17931033 December 10, 1993 Increasing the thickness of the concrete pavement sections described above by 1 inch can be considered to allow the deletion of subgrade stabilization. The concrete sections for placement on a properly compacted, unstabilized subgrade are as follows: CONCRETE TRAFFIC SECTION Automobile and light truck parking 6" Drive Lanes 7" Heavy Truck Areas 8" Subgrades beneath these paving areas should be proof-rolled with heavy compaction equipment and any soft or spongy soils should be removed and replaced in a controlled manner. The subgrade should be scarified to a depth of 6 inches and compacted to a minimum of 95 percent of standard Proctor maximum dry density (ASTM D-698) at --+2 percent of optimum moisture content. The subgrade soils should be protected from excessive wetting or drying prior to placement of the paving. Positive drainage should be provided on area paving to prevent ponding of water. Water should not be allowed to pond behind curbs and/or adjacent to paving. The ponding of water can result in the softening of subgrades that support the paving, and premature pavement distress. 2 Mr. Mike Nuzum Terra¢on Job No. 17931033 December 10, 1993 We trust this information will be of benefit to you on this project. If you have any questions or we can be of further assistance, please contact this office Sincerely, TERR&CON COISi$,I.J~LT~NTS, INC. Eric J. Cleveland, P.E. Clement B. Bommarito, P.E. Project Engineer Office Manager EJC:CBB:kms Copy To: Mr. Dennis Chovan Albert Halff and Associates 3 12/08/95 16:01 '~214 ?39 0095 ~LFF ASSOCIATES ~ 002/003 M.J Designs Terracon Job No. 17935076 October 8, 1993 Page 17 Pavements The existing active clay soils are subject to strength loss with the increases in moisture content that normally occur beneath paving. California Bearing Ratio (CBR) tcst~ performed on two samples of the surficial grayish brown to brown clays indicate CBR values of about 3, which classifies as a poor subgmde soil. Mixing hydrated lime with these soils typically improves their subgrade support value, even a[ thc higher moisture levels that occur beneath area paving. An application rate of 7% hydrated lime by dry soil weight is recommended for trea~nent of the on-site clay soils. The hydrated lime should meet the requirements of Item 264 (Type A) in the Texas State Department of Highways and Public Transportation Standard Specifications for Construction of Highways, Streets and Bridges. This lime should be thoroughly mixed and blended with the top 6 inches of subgrade and compacted to at least 95% of it's maximum standard Proctor dry density. The moisture content of the lime modified material at the time of compaction should be within a range of-2% to +4% of it's optimum value. Mixing, curing and compaction of the lime modified layer is described in Item 260 of the previously mentioned Standard Specifications. Modification is recommended beneath asphaltic concrete pavements. Modification will also improve the performance of Portland cement concrete pavement sections, although it is sometimes omitted in light traffic areas (automobiles, light trucks, etc.) with generally satisfactory performance. Recommended concrete pavement thicknesses in truck traffic areas are provided for stabilized and unstabilized subgrades. If asphaltic concrete pavement is used, we recommend a full depth asphaltic concrete section having a minimum total thickness of 5.0 inches for automobile parking areas and 6.5 inches for drive lanes receiving light to medium size trucks. A minimum surface course thickness of 2.5 12:08/93 16:02 '~'214 739 0095 ~LFF ASSOCIATES ~003/003 MJ Designs Terracon Job No. 17935076 October 8, 1993 Page 18 inches is recommended for asphaltic concrete pavements. The asphaltic concrete surface coarse should conform to Type D and the base course should conform to Type A or B in Item 340 of the THD Standard Specifications. The coarse aggregate in the surface course should b~ crushed limestone rather than gravel. If portland cement concrete pavement is used, a minimum thickness of 5 inches of concrete is recommended for parking areas for automobiles and light trucks, and 6 inches for drive lanes. A minimum 7 inch section is recommended in the heavy truck areas with a stabilized subgrade, and this should be increased to 8 inches if the subgrade is scarified and compacted to 95 percent of standard Proctor maximum dry density (near optimum moistures) without the addition of lime. Concrete with a minimum 28 day compressive strength of 3,500 psi should be used. The above sections should be considered minimum pavement thicknesses and higher traffic volumes ~d heavy trucks may require thicker pavement sections. Additional recommendations can be provided after traffic volumes and loads are known. Periodic maintenance should be anticipated for minimum pavement thickness. This maintenance should consist of sealing cracks and timely repair of isolated distressed areas. Asphaltic concrete pavement over granular base is not recommended beneath asphaltic or concrete pavements, bemuse water can collect in the granular base, softening the subgrade soils and possibly causing heave of these active clays. Pavements should be placed on the prepared clays with no sand leveling course, and they should'be sloped to provide rapid drainage of surface water. Water allbwed to pond on or adjacent to the pavement could saturate the subgrade and contribute to premature pavement deterioration.