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McDonald's-LR 870428 SOILS AND FOUNDATION INVESTIGATION MCDONALD'S RESTAURANT DENTON TAP ROAD & SANDY LAKE ROAD C0PPELL, TEXAS REPORT NO. DE-7029 TO MCDONALD'S CORPORATION IRVING, TEXAS BY TERRA-MAR, INC. AUSTIN / DALLAS / FT. WORTH / HOUSTON APRIL 1987 Consulting Englnee~ · GeOtechnl~l · Environmental * Con~lon Martials Testing April 28, 1987 Report No. DE-7029 McDonald's Corporation 511 E. Carpenter Frwy., Suite 375 Irving, Texas 75062 ATTN: Mr. John Roper Real Estate and Construction Coordinator SOILS AND FOUNDATION INVESTIGATION MCDONALD'S RESTAURANT DENTON TAP ROAD & SANDY LAKE ROAD COPPELL, TEXAS Gentlemen: Submitted here is our report on the evaluation of soils and foundation conditions for the above project site. This report presents the results of field and laboratory investigations together with recommendations for the design and construction of foundations for the proposed structure and pavement sections for automobile parking and drives. This study was authorized by Mr. John Roper on April 9, 1987. INTRODUCTION It iS planned to construct a McDonald's Restaurant at the above referenced location. Proposed facilities consist of a single-level structure, paved parking, and drives. Objectives of this investigation were to evaluate soil conditions and develop recommendations for the structure and elevated road sign foundations including foundation type, depth, and allowable loading. Related construction includes pavement for automobile parking and drives to be constructed at or near existing grades. Pavement sections and subgrade preparations-including the~ necessity, .if any; for soil stabilization were to be addressed in our study. This report briefly describes the general soils and design conditions followed by engineering analyses and recommendations for the design and construction of foundations for the proposed structure and pavement for automobile parking and drives. 2679 Lombardy, Dallas, Texas 7S220 Phone:Z14-352-8352 FIELD AND LABORATORY INVESTIGATION Subsurface conditions at the site were evaluated by six soil test borings. These borings were located 'as.specified by the client. Approximate locations are shown on the Plan of Borings, Plate 1. Boring depths varied from 5.0 feet in parking areas to 20.0 feet beneath the structure. Sample depths, soil. descriptions and classifications (based on the Unified Soil Classification System) are shown on the Logs of Borings, Plates 2 through 7. A key to the descriptive terms and s~mbols used on the logs is presented on Plate 8. Soil formations were sampled using a thin-walled Shelby tube sampler to sample cohesive soils while granular soils were sampled using the split barrel sampler in conjunction with the Standard Penetration Test (SPT). The borings were drilled dry without the aid of drilling fluids to more accurately determine the depth to groundwater. Water observations made at the completion of drilling and 24 hours later are indicated on the boring logs. Field soil classifications were verified by laboratory tests to determine liquid limit, plastic limit, percent passing the No. 200 sieve size and natural moisture content. Results of these tests are tabulated at the appropriate sample depth on the boring log. Shear strength of the cohesive soils was evaluated by hand penetrometer tests and verified by unconfined compression tests. The strength test results are tabulated at the appropriate sample depth on the boring logs. The natural moisture content and unit dry weight, determined as part of the unconfined compression test, are also shown on the boring logs. GENERAL SOIL AND DESIGN CONDITIONS Site Conditions The site for the proposed McDonald's Restaurant is located near the southwest corner of the Denton Tap Road and Sandy Lake Road intersection in Coppell, Texas. The site is a vacant lot approximately 115 feet south of Sandy Lake Road, on the west side of Denton Tap Road. Short grass and weeds cover the site with several.small to.medium sized, trees scattered ~ throughout the site. The site is relatively flat, sloping to the north with two to three feet of relief. During the site inspection no evidence of seasonal high water was noted. Soil Stratigraphy The site is geologically located in the Woodbine Formation as indicated on the Dallas Sheet of The Geologic Atlas of Texas. Geologic data shows that surficial soils of the Mabank and Report No. DE-7029 2 Silawa series overlie the area. Generally, these soils consist of surficial sandy loam underlain by clay loam. The clays are moderately plastic and are susceptible to moderate shrink/swell potential accompanying variations in soil moisture contents. These soils have a moderate to high corrosivity to uncoated and unprotected steel and a moderate corrosivity to concrete. -Soil stratigraphy and engineering properties determined from the results of this study show similar characteristics. Soil formations encountered at the site are shown on the boring logs, Plates 2 through 7. These data indicate that soil conditions are relatively uniform across the site and can be grouped into major strata as follows: Average Stratum Depth, Ft. Soil Description I 0.0 - 3.0 Medium dense to dense reddish brown, brown, tan and gray silty and clayey fine sand. (SM - SC)* Note: Borings B-5 and B-6 encountered sandy clays and mixed clayey sands and sandy clays. (sc - CL)* II 3.0 - 16.0 Stiff to hard brownish gray, tan and gray sandy clay with occa- sional iron nodules. (CL)* III 16.0 - Completion Dense to very dense clayey fine sand. (SC)* *Classification according to the Unified Soil Classification System. Groundwater level observations made at the completion of drilling and 24 hours later, indicate that groundwater levels occur below the caved depths of the borings. It should be noted that groundwater levels may not remain static and will fluctuate with variations in seasonal precipitation and surfic±al runoff. Design Conditions The surface soils-of ~Stratum I consist mainly of'low plastic' silty and clayey sands. These soils have liquid limits ranging from 23 to 26 and plasticity indices ranging from 12 to 15. Present moisture levels in these soils ranged from three to six percent above the plastic limit, a condition indicative of low shrink/swell potential accompanying variations in soil moisture content. Report No. DE-7029 3 Strata II soils consist of sandy clays. These clays are compact with shear strengths ranging from 0.31 tons per square foot (tsf) to 2.63 (tsf). These soils are moderately plastic with liquid limits ranging from 32 to .35 and plasticity indices ranging from 21' to 23. Present moisture levels in these soils ranged from five to seven percent above the plastic limit, a condition indicative of moderate shrink/swell potential accompanying variations in soil moisture contents. The sand formation of Stratum III is relatively strong and will not be subject to shrink/swell movements accompanying variations in soil moisture contents. ANALYSES AND RECOMMENDATIONS General Based on the results of the field and laboratory investigation and the presence of surficial iow plastic clayey sands underlain by moderately plastic sandy clays that will not be subject to high shrink/swell movements, it is recommended that the structure be founded either on a stiffened and strengthened concrete slab-on-grade or structural loads be founded on individual shallow spread footings or a continuous wall footing with an interior floor slab at grade. Both the slab-on-grade and the shallow footing foundation systems are adequate and are discussed in the following sections. Shallow Footings Shallow footings may be used for the support of structural loads. They may consist either of spread or continuous strip footings and may be founded in the medium dense surficial clayey fine sands or on the stiff to hard sandy clays at a minimum depth of 3.0 feet below finished grade. The footings may be proportioned for an allowable bearing pressure of 2,000 pounds per square foot (psi). Minimum recommended spread footing dimension is 30 inches while the minimum strip footing width is 18 inches. Foundation settlement for the recommended loads will be less than 0.75 inch. Monolithic Stiffened and Strengthened Concrete Slab-on-Grade As noted earlier, the foundation soils are moderately plastic and will not be subject to appreciable shrink and swell movement accompanying changes in moisture content. Therefore, support of the structure may be on a conventional stiffened and strengthened concrete slab-on-grade. The grade beams of the slab may bear directly on the prepared subgrade soils at a minimum depth of 24 inches. The minimum recommended exterior grade beam width is 12 inches. Although a conventional stiffened and strengthened slab-on-grade is designed to distribute superstructure loads, maximum allowable soil bearing pressures should not exceed 1,500 psi at any point Report No. DE-7029 4 under the slab. Sufficient reinforcing should be provided in the slab and beams to resist concrete shrinkage and cracking due to bending moments created by some movements in the foundation soils. The slab design should be based on a Potential Vertical Rise (PVR) of 1.1 inches. The interior floor slab with the shallow footings may also be supported at. grade and designed in accordance with the above requirements. Two to four inches of granular material such as coarse sand or pea gravel are recommended beneath the floor slab to enhance drainage, to reduce vertical moisture/vapor movement, and to serve as a leveling course. Additionally, polyethylene sheeting or equivalent materials should be placed between the concrete and granular layer to act as a vapor barrier in areas where floor coverings or coatings are planned or where moisture penetration is undesirable. It is recommended that floor slab areas not be structurally connected to interior columns. Isolation joints should be placed between the columns and the slab to ensure that any vertical floor slab movement is not transferred to structural members. Sign Foundation A proposed McDonald's sign will be sub3ected to axial and lateral loads due to gravity and wind effects. Based on the soil stratigraphy at the site, we recommend that the proposed signs be supported on drilled footings (straight shaft) founded in the very stiff to hard sandy clay of Stratum II. The straight shaft piers should be proportioned using an allowable end bearing pressure of 7,500 psf. An allowable lateral pressure used to resist the horizontal forces and moment imposed on the pier may be 5,000 psf for the sandy clays. Lateral resistance in the top four feet of the pier should be neglected from the calculations. Corrosion Potential During wet seasons of the year, underground piping may be exposed to free moisture in the form of surface saturated soils or perched water in trench bedding which could cause metal piping to corrode. Therefore, cathodic protection will be required~ for metal piping 'or alternately non-corrosive materials or conventional PVC piping should be specified. Pavement The surficial soils at the site consist of silty and clayey fine sands overylying moderately plastic sandy clays. In these areas a temporary perched water table may develop. The perched water could lead to prolonged saturation and reduced Report No. DE-7029 5 strength of the surficial sands and clay subgrade. It is, therefore, recommended that flexible asphaltic pavement not be used and consideration be given to rigid concrete pavement only. Based on correlations of subgrade type and supporting capacity, the required pavement thickness as a function of estimated traffic and wheel loading for rigid paving has been determined using the AASHTO "Structural Number" (SN) system. Listed on Table I of Appendix A are typical pavement sections. These pavement sections' will be suitable for frequent applications of the design wheel loading and infrequent loads of greater magnitude. Adequate subgrade drainage is essential to pavement performance in accordance with design criteria. Site Preparation Site preparation may require minor cuts and fills to bring the site to desired grades. The fill required to bring the site to desired grades may consist of on-site soils from cut sections, free of any vegetation or debris or off-site inorganic soils with a plasticity index less than 20. Recommended earthwork construction procedures are included in Appendix A. INSPECTION AND TESTING Many problems can be avoided or solved in the field if proper inspection and testing services are provided. It is recommended that site preparation, pavement construction, and floor slab construction be monitored by a qualified engineering technician. Density tests should be performed to verify compaction and moisture content of any earthwork. Inspection should be performed prior to and during concrete placement procedures. LIMITATIONS The recommendations presented in this report were based on a discrete number of soil test borings. Although our field personnel visually survey the site for surface features indicative of variable soil conditions (fill, borrow, or drainage areas, faulting, etc..), subsurface conditions may be encountered that differ from these data. In this case, we should be notified immediately so that the effects of these conditions on design and construction can be addressed. AnY changes in the project character and location, or, substantial grade changes should be discussed with our firm in order to assess possible changes in the recommendations. This study was conducted for the exclusive use of the McDonald's Corporation. The reproduction of this report or any part thereof, in plans or other documents supplied to persons other than the owner, should bear language indicating Report No. DE-7029 6 that the information contained therein is for general design purposes only and not for bidding purposes. We appreciate the opportunity to assist with the design phase of this - Project. Should you have any questions or need additional assistance, please call. Very truly yours, TERRA-MAR, INC. Project Engineer ~,o~,, ...... ,..,~ Berry R. Srubbs, P.E. %'~7"~'~%::'It.~'' ' '" Principal Engineer Assistance in Data Analyses ~:E~=~*ll and Report Preparation By: Mark E. Wyatt, E.I.T. Staff Engineer APP/BRG/dak Copies submitted: (7) McDonald's Corporation Mr. John Roper ILLUSTRATIONS Plates Plan of Borings 1 Logs of Borings 2 - 7 Key to Log Terms and Symbols 8 Appendix A - Table I - Pavement Sections Site Preparation Report No. DE-7029 7 ILLUSTRATIONS SANDY LAKE ROAD 1" =/40' /,-- P~operty line ~6 PLAN OF ~,IN(;S PLATE 1 ~ LOG OF BORING NO. -"' McDotlaJ. dts Restat.h--arlt PROJECT NO.: L PROJECt: ~t~ Tap ~. ~d ~dy ~ ~. ~ ~1~ T~ LOCATION: SEE PLATE ~ ~ [ [ SUnF~CE ELEVATmOfl: EX(ST'~G ~0[~ SHE~R ~ . [ [ BOR)~ UETHOD= DRY AUGER 0,0 lO ~,0. FT. wzO FREE WATER ENCOUNTERED AT __ _ FT. ~ ~ ~ ~ ~ ~ ~ ~O mj STRATUM CRIPTIO ~ PL Pm m 5 - ~.~ -l~ter ~ color at ~.5' 1.~ -20' '50' SAUPL~ m S~ELBY LEGEND: Tofl~ ~ STANDARD ~ TEXAS H(GH~AY ROC~ NO COUPLEI)ON DEPTH: 10,0 FT. PeNEIRAliON DEPT. PEnET. ~ ~ RECOVERY CORE , DATE: ~1~7 ~'~ PLATE 2 2 LOG OF BORING NO. ~,~ z _~ ~or~ld's Festaurant ,,., PROJECT: Dent(x] Tap ~. ~ ~dy ~ ~. PROJECT NO.: ~7~ = ~p~11~ T~ LOCATION: SEE PLATE ~ SURFACE ELEVATION~ EXISTING SOIL SHEAR ~ - BORI~ METHOD~ DRY AUGER 0.0 TO 5.0 FT, ~ W~H BORE TO FT. ~ ~ ~ ~X ~ : ~ ~__~ F"EE WATER ENC~NTERED AT FT. OZ ~ ~ WATER AT FT. AFTER HRS. 20 ~ HOLE CAVED [ DRY) AT 5.0 FT. AFTER 2~ HRS. Z Z ~ STRATUM DESCRIPTION 3.0 ~ br~ ~yey f~e ~d ~ s~t 0.92 ~ d~ at 2.0' (m) Ve~ s~f ~ ~ ~y ~dy 5- 2.5 ~) 0.78 ~te: ~le ~ at ~leti~. - I0 - - 15 ~20. -25- '30' SAMPLE ~ SHELBY ~ TEXAS HIGHWAY ROCK L~G[.D: ~U~[ ~ STANDARU I P[NET.A],ON DEPT. P~N~. ~CO"~ ~ RECOV~R~"O COUPL~T,O. DEPTH: 5.0 FT. I I I J DATE: ~1~7 ~-~ PLATE 3 LOG OF BORING NO. l~23~ld's P~tau~ant PROJECT: l~ntc~ Tap ~. ~d ~dy ~ ~. PROJECT NO.: ~ ~p~ T~ LOCATION: SEE PLATE ~ I SURFACE ELEVATION: EXISTING S01L SHEAR I BORING METHOD: DRY AUGER 0,0 TOE0.0 FT. ~ ~ ~, ~ STRENGTH ~ I · ~ ~ ~ : TONS/SO.F' . W~H BORE TO FT. ' ~ ~' ~ ~ O> O~ ~ I WATER LEVEL O~ERVATIO~: ~ ~ U ~0 Z~ ~ ~Z ~ ~ / STRATUM CRIPTi ~ "~ 4.~ {~ br~ c~yey f~e ~d 1.~ 1.0 ~St~f br~ ~ ~y ~y ~y 0.31 {-v s~f at 3.~' 5 2.~ 0.~ ~ <~) {d ~ ~d Fay ~dy ~y ~ n~o~ ~ s~ .~o 4.~ . <~) [.~ 15' '20' '~5' -50' SAMPLE ROCK LEGEND: ~ SHELBY ~ I i I DATE: ~'~ PLATE LOG Of BORING NO. ~II~ MzDonald's Restaurant PROJECT: I)entcm Tap Rd. and Sandy lake Rd. PeO.JECT .~O.: ]]g-7029 Coppell, Texas LOCATION: SEE PLATE ~ SurFACE ELEVATION: FXmTING SOIL SHEAR ~ . BORING METHOD: DRY AUGER 0.0 TO 20.0 FT. ~- ~- ~ ~ STRENGTH ,: wASH SORE TO FT. ,~,~ ~ -~ _o~--× { .' i. ..,_: o ~-c~ z~_ ~: mz ~' 0~ WATER LEVEL OBSERVATIONS: ::Dz-- -- Z- ~ FREE WATER ENCOUNTERED AT FT. _ ~, ,,=, ? WAT[. AT__ ~T. AFTER __ HRS. O S ~- O"' <Z HOLE CAVED'( DRY) AT 16.5 FT. AFTER 24 HRS. Z Z ,,~n~ Z'~ : STRATUM DESCRIPTION ~ "' Median dense red, tan and gray clayey fine sand 1.5 16 23 11 12 ~8 0.47 (sc) -5 2.5 Very stiff red, tan and gray sandy c~y 18 3.78 -hard at 8.5~ lO-4.5+ 15 32 11 21 119 1.5+1.9~ :3.0 -lncr~ng gray color, very stiff at 13.5' (CL) 16 0.93 ~5-Dense tan and gray clayey fine sand -very de~se at 18.0' 6~ (sc) -20' Note: Hole dry at completion. -25- -30- , , SAMPLE SHELBY 10~ STAN[)ARD ~;~ TEXAS HIGHWAY IT~ mOCK [~1 NO COMPLETION DEPTH: 20.0 FT. L~G~ND: ~ TU[~ I I~ p[Ne~RA]~ON i D~PT. P~N~'r. I "'COR~ I RECOVERY DATE: 4--15--87 T'r~o~ PLATE 5 ~rJ)onald's P~staurantLOG Of BORING NO. ~5 ~O~ECr: l~tcn Tap ~. ~ ~dy ~ ~. v~oJecr NO.: ~ G~ll, T~ LOCATION: SEE PLATE ~ SURFACE ELEVATION: EXISTING SOIL SHEAR ~ ~ STRENGTH ~ - BORI~ METHOD: DRY AUGER 0.0 TO ~.0 FT, ~ - ~ ~ = > ~ TONS/SQ.F~ . · W~H BORE TO FT. ~ ~_~ WATER LEVEL OmERVATIONS: g~ ~* g -- m~ ~ *o ~ZO FREE WATER ENCOUNTERED AT FT. ~ _ ( ~ (~ ~ ~ ~Z~ ~ ZTM OZ ~ ~ ~m ~ ( &~ Z~ - o ~ HOLE CAVEO ( DRY) AT ~.~ FT. AFTER 2~ HRS. Z Z = . STRATUM DESCRIPTION ~ .~l ., 1.5 ~ d~ r~ c~yey f~e ~d ~ ~c1~ md 14 0.47 1.~ ~ 17 26 11 15 52 0.~ (~) 5 - n~ ~d -~O- 3.75 16 35 12 ~ ..16 I -15 3.0 -~~g ~d c~t~t aL 14.5~ ~8 l~ (&) Ve~ ~ ~ md ~ay ~yey f~e ~d · 20.63 ~te= ~le ~ at c~let~. -5o- , LEGEND: SAMPLE ~ SHELBYTUBE ' ~ STANDARD ~ TEXAS HIGHWAY ' ~ ROCK ' ~RECOVERyNO COMPLETION DEPTH: ~.OFT. PENETRA]ION DEPT. PENET. ~ CORE DATE: ~7 I I I ~-~ PLATE LOG OF BORING NO. '-' McDonald's Restaurant PROJECT: Dento~ Tap Rd. and Sandy Lake Rd. PROJECT NO.:I~-7029 = Coppell, Texas LOCATION: SEE PLATE ~ SURFACE ELEVATION: EXISTING SOIL SHEAR "~ ~C{ BORING mETHOD: DRY AUGER 0.0 TO 5.0 FT. ,,,zO FREE WATER ENCOUNTERED AT FT. -~- ~ Z-~ OZ = ~.g WATER AT FT. AFTER HRS. ~, .OLE CAVED'( O~Y) AT 4.1 FT. ^~T[R 24 '"S. Z Z O < STRATUM DESCRIPTION 2.25 Very stif~ ~eddi.~h b~oun sandy clay with occas~ona~ ~z-on 10.70 nedu~es 2.75 3.85 ~ Very stiff red, tan and gray sandy clay with nunerous 1.24 4.O --x_irc~ stains Note: Hole dry at ccmpleticm. - lO - · 18 -RO- -~8. -~O' SA~PtE ~ S~E~¥ ~ TEXAS M~OMWA¥ ~SE~D: ~US~ ~ STANDAR~ ~ RECOV£R~ CO~E~ION OE~M:5.0 FT. ~ENE~R~,O~ DE~T. ~NE~. ~CO~E~OC~ ~ ~ I I DATE: 4--15--87 ~- ~aU"~ PLATE 7 SYMBOLS AND TERMS USED ON BO G LOGS SAMPLE TYPES ~ .or,.Ea .... '-I ~v ~.*O~DG~vE~S 6.*VE~ INDICATES DE~H OF STANDARD PENETRATION TEST ~[1MIX*URES INDICATES DE~H OF DISTURBED OR AUGER SAMPLE ~.~ ~,.ES, '~1 KEY TO SAMPLES ~ ~c~ ~c,~s~ LIQUID LIMIT -- ~ S,EVE ~ : 10 o ~ ~ - ~ P~STICI~ CHART SOIL C~SSIFICATION CHART UNIFIED SOIL CLASSIFICATION SYSTEM RESTIVE DENSI~ OF COHESlONLESS SOILS CONSISTENCY OF COHESIVE SOILS COARSE G~INED SOILS (major potion retained on No. 2~ FINE GRAINED SOILS (major potion passing No. 2~ sie~): sieve): Includes (1) clean grovels and sands, and (2) silty or Includes (1) inorganic and organic silts and clays, (2) gravelly, clayey gravels and sands. Conditions rated ac~rding to stan- sandy, or silty clays, and (3) clayey silts. Consistency is rat~ dard penetration test (S~ as pedormed in the field, according to shearing strength as Indicated by penetrometer readings or by unconfined compression tests. Desc~ptive Te~ Blows Per F~t* Unconlin~ Ve~ L~se 0 - 4 Compressive Loose 5 - 10 DescHpti~e Te~ Strength Firm 11 - 30 To. Sq. FL Dense 31 - ~ Ve~ Dense over ~ Ve~ Soft Less than 0.25 Soft 0.25 to 0.~ '1~ pound weight having a frae fall of ~ inches. Medium 0.~ to 1.~ Stiff 1.~ to 2.~ Ve~ Stiff 2.~ to 4.~ Hard 4.~ and higher NOTE: Slickensided and fissured clays may have lower um confined compressive strengths than shown above, because of weakness or cracks in the soil. The consistency ratings of such soils are based on penetrometer readings. TERMS CHARACTERIZING SOIL STRUCTURE Slickensided -- having inclined planes of weakness that are slick and glossy in appearance. Fissur~ -- containing shrinkage cracks, frequently fill~ with fine sand or silt; usually more or less vertical. ~minated -- composed of thin layers of vayng colors and texture. Inter~dded ~ composed of alternate layers of different soil ty~s Calcareous ~ containing appreciable quantities of calcium car~nate Well graded -- having wide range in grain sizes and substantial amounts of all intermediate panicle sizes. P~rly graded -- predominantly of one groin size, or having a range of sizes with some interm~iate size missing. l'EratA-~ PLATE 8 APPENDIX A TABLE I - PAVEMENT SECTIONS Rigid Pavement (Protected Corner) Pavement Thickness, inches Auto Service Drive Traffic Truck Traffic Concrete Pavement: 5.0" 6.0" Scarified and Compacted to 95% 6.0" 6.0" Compacted Subgrade: Standard Density ASTM D-698 at +1 to +4 percentage points of optimum moisture (a) Auto parking areas to be reinforced with #3 bars at 24 inches on-center and truck drives at 18 inches on-center or flat sheets of welded wire mesh 6 x 6 - 6/6 and 6 x 6 - 4/4, respectively. Specifications should require a minimum clear distance of 2 inches between the soil and steel. Strength of concrete should be 3,000 psi at 28 days. Recommended 3oint spacing is 20 to 25 feet. (b) Heavy traffic areas such as truck unloading and garbage truck zones, should be reinforced with #3 bars at 12 inches on-center each direction. Strength and clear distance to reinforcement should be as above. Referenced Specifications Texas Highway Department Standard Specifications (THD S.S.): Item 200 - Site Stripping. Item 216 - Proofrolling. SITE PREPARATION The recommended earthwork construction procedures are .as follows: 1. Remove all vegetation, organic topsoil and any undesirable materials from the construction area. Average stripping depth is estimated to be six inches. 2. Structural pavement and fill areas should then be proofrolled with a loaded dump truck, scraper, or similar pneumatic-tired equipment. The proofrolling serves to densify loose surficial soils and to detect any soft or loose zones. Any soils deflecting excessively under moving load should be undercut to fi£., soils and recompacted. The proofrolling operations should be observed by an experienced geotechnician. 3. Scarify the subgrade, add moisture if necessary and recompact to 95 percent of the maximum dry density as determined by ASTM D-698 (Standard Proctor). The moisture content at the time of compaction of subgrade soils should be from plus one to plus four percentage points above the proctor optimum value. 4. Fill may consist of on-site soils or off-site inorganic soils with a plasticity index less than 20 and should be placed in loose lifts not exceeding nine inches in thickness and compacted to 95 percent of the maximum dry density determined by ASTM D-698 (Standard Proctor). The moisture content of the fill at the time of compaction should be from plus one to plus four percentage points above the proctor optimum value. 5. In cut areas, the soil should be excavated to grade and the surface soil proofrolled and scarified to a minimum depth of six inches and recompacted to the previously mentioned density and moisture content. 6. The subgrade moisture content and density must be maintained until Daving or floor slab~ ara comDla%~d.