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Home My WebLink AboutHARMONY SAFEWAY, BLOCKBUSTER - FINAL - 33-94C - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTi r TABLE D2 l` RECOMMENDED PREVENTATIVE MAINTENANCE POLICY FOR JOINTED CONCRETE PAVEMENTS Distress Distress Recommended Distress Distress Recommended Type Severity Maintenance Type Severity Maintenance Low None No Blow-up Polished Severity Groove Surface Medium Full -Depth Concrete Patch/ Aggregate Levelsor Overlay High Slab Replacement Defined Low Seal Cracks No Medium Full -Depth Comer Break Popouts Severity Levels None High Concrete Patch Defined Low Seal Cracks No Undersea[, Divided Severity Seal cracks/joints Slab Medium Slab Pumping Levels and High Replacement Defined Restore Load Transfer Low None Low Seal Cracks Medium Full -Depth Patch Medium Full -Depth Durability Punchout Cracking Concrete High Slab Replacement High Patch Low None Low No Medium Medium Faulting Railroad Crossing Policy for this Grind High High Project Low None Scaling Low None Medium Reseal Medium Slab Replacement, Joint Seal MC��w"g g Joints Full -depth Patch, High High or Overlay Low Regrade and No Medium Lane/Shoulder ' Fill Shoulders Shrinkage Severity None Drop-off to Match Cracks Levels High Lane Height Defined Linear Cracking Low Clean & Low None Longitudinal, Transverse and Medium Seal all Cracks Spalling Medium (Comer) Partial -Depth High Full -Depth Patch High Diagonal Cracks Concrete Patch Low None Low None Large Patching S al6n and Medium Seal Cracks or (Joint) Medium Partial -Depth Patch High High Reconstruct Joint Utility Cuts Replace Patch Low None Medium Replace Small Patching Patch High lrerracon TABLE D7 RECOMMENDED PREVENTATIVE MAINTENANCE POLICY FOR ASPHALT CONCRETE PAVEMENTS Distress Distress Recommended Distress Distress Recommended Type Severity Maintenance Type Severity Maintenance Low None Low None Alligator Alligator CrackingMedium Patching & utility Cut Patching Full -Depth Asphalt Concrete Medium Full -Depth Asphalt Concrete High Patch High Patch Low None Low Bleeding Polished Aggregate None Medium Surface Sanding Medium High Shallow AC Patch High Fog Seal Low None Low Shallow AC Patch Medium Clean & Seal Medium Full -Depth Asphalt Concrete Block Cracking Potholes High All Cracks High Patch Bumps & Sags Low None Railroad Crossing Low No Policy for This Project Medium Shallow AC Patch Medium High Full -Depth Patch High Low None Low None Medium Full -Depth Asphalt Concrete Medium Shallow AC Patch Corrugation Rutting High Patch High Full -Depth Patch Low None low None Medium Shallow AC Patch Medium Mill & Shallow AC Depression Shoving High Full -Depth Patch High Patch Low None Low None Edge Cracking Medium Seal Cracks Slippage Cracking Medium Shallow Asphalt Concrete High Full -Depth Patch High Patch Low Clean & Low None Joint Reflection Seal All Cracks Swell Medium Medium Shallow AC Patch High Shallow AC Patch High Full -Depth Patch Low None Low Lane/Shoulder Drop -Off Weathering & Ravelling Fog Seal Medium Regrade Shoulder Medium High High Low None Longitudinal & Transverse Cracking lrerracon Medium Clean & Seal All Cracks High f .. 1 REPORT TERMINOLOGY (Based on ASTM D653) Expansive Potential The potential of a soil to expand (increase in volume) due to absorption of moisture. Finished Grade The final grade created as a part of the project. Footing A portion of the foundation of a structure that transmits loads directly to the soil. Foundation The lower part of a structure that transmits the loads to the soil or bedrock. Frost Depth The depth of which the ground becomes frozen during the winter season. Grade Beam A foundation element or wall, typically constructed of reinforced concrete, used to span between other foundation elements such as drilled piers. Groundwater -Subsurface water found in the zone of saturation of soils, or within fractures in bedrock. Heave Upward movement. Lithologic The characteristics which describe the composition and texture of soil and rock by observation. Native Grade The naturally occuring ground surface. Native Soil Naturally occurring on -site soil, sometimes referred to as natural soil. Optimum Moisture The water content at which a soil can be compacted to a maximum dry unit Content weight by a given compactive effort. Perched Water Groundwater, usually of limited area maintained above a normal water elevation by the presence of an intervening relatively impervious continuing stratum. Scarify To mechanically loosen soil or break down existing soil structure. Settlement Downward movement. Skin Friction (Side The frictional resistance developed between soil and an element of structure Shear) such as a drilled pier or shaft.. Soil (earth) Sediments or other unconsolidated accumulations of solid particles produced by the physical and chemical disintegration of rocks, and which may or may not contain organic matter. Strain The change in length per unit of length in a given direction. Stress The force per unit area acting within a soil mass. Strip To remove from present location. Subbase A layer of specified material in a pavement system between the subgrade and base course. Subgrade The soil prepared and compacted to support a structure, slab or pavement system. lrarracon REPORT TERMINOLOGY (Based on ASTM D653) Allowable Soil The recommended maximum contact stress developed at the interface of the Bearing Capacity foundation element and the supporting material. Alluvium Soil, the constituents of which have been transported in suspension by flowing water and subsequently deposited by sedimentation. Aggregate Base A layer of specified material placed on a subgrade or subbase usually beneath Course slabs or pavements. Backfill A specified material placed and compacted in a confined area. Bedrock A natural aggregate of mineral grains connected by strong and permanent cohesive forces. Usually requires drilling, wedging, blasting or other methods of extraordinary force for excavation. Bench A horizontal surface in a sloped deposit. Caisson (Drilled pier A concrete foundation element cast in a circular excavation which may have an or Shaft) enlarged base. Sometimes referred to as a cast -in -:place pier or drilled shaft. Coefficient of A constant proportionality factor relating normal stress and the corresponding Friction shear stress at which sliding starts between the two surfaces. Colluvium Soil, the constituents of which have been deposited chiefly by gravity such as at the foot of a slope or cliff. Compaction The densification of a soil by means of mechanical manipulation. Concrete Slab -on- A concrete surface layer cast directly upon a base, subbase or subgrade, and Grade typically used as a floor system. Differential Unequal settlement or heave between, or within foundation elements of a Movement structure. Earth Pressure The pressure or force exerted by soil on any boundary such as a foundation wall. ESAL Equivalent Single Axle Load, a criteria used to convert traffic to a uniform standard, 0 8,000 pound axle loads). Engineered Fill Specified material placed and compacted to specified density and/or moisture conditions under observations of a representative of a geotechnical engineer. Equivalent Fluid A hypothetical fluid having a unit weight such that it will produce a pressure against a lateral support presumed to be equivalent to that produced by the actual soil. This simplified approach is valid only when deformation conditions are such that the pressure increases linearly with depth and the wall friction is neglected. Existing Fill (or Materials deposited through the action of man prior to exploration of the site. man-made fill Existing Grade The ground surface at the time of field exploration. rarracon LABORATORY TESTS SIGNIFICANCE AND PURPOSE TEST SIGNIFICANCE PURPOSE California Used to evaluate the potential strength of subgrade soil, Pavement Bearing subbase, and base course material, including recycled Thickness Ratio materials for use in road and airfield pavements. Design Consolidation Used to develop an estimate of both the rate and amount of Foundation both differential and total settlement of a structure. Design Direct Used to determine the consolidated drained shear strength of Bearing Capacity, Shear soil or rock. Foundation Design & Slope Stability Dry Used to determine the in -place density of natural, inorganic, Index Property Density fine-grained soils. Soil Behavior Expansion Used to measure the expansive potential of fine-grained soil Foundation & Slab and to provide a basis for swell potential classification. Design Used for the quantitative determination of the distribution of Soil Gradation particle sizes in soil. Classification Liquid & Used as an integral part of engineering classification systems Plastic Limit, to characterize the fine-grained fraction of soils, and to Soil Plasticity specify the fine-grained fraction of construction materials. Classification Index Used to determine the capacity of soil or rock to conduct a Groundwater Permeability liquid or gas. Flow Analysis Used to determine the degree of acidity or alkalinity of a soil. Corrosion PH Potential Used to indicate the relative ability of a soil medium to carry Corrosion Resistivity electrical currents. Potential Used to evaluate the potential strength of subgrade soil, Pavement R-Value subbase, and base course material, including recycled Thickness materials for use in road and airfield pavements. Design Soluble Used to determine the quantitative amount of soluble Corrosion Sulphate sulfates within a soil mass. Potential To obtain the approximate compressive strength of soils that Bearing Capacity Unconfined possess sufficient cohesion to permit testing in the Analysis Compression unconfined state. for Foundations Water Used to determine the quantitative amount of water in a soil Index Property Content mass. Soil Behavior lrerracon ABased on the material passing the 3-in. (75-mm) sieve sif field sample contained cobbles or ZCu-D6,1D1, CC " (D00)r Die x DEn boulders, or both, add "with cobbles or boulders, or both" to group name. cGravels with 5 to 12% fines require dual EIf soil contains > 15% sand, add "with symbols: sand" to group name. GW-GM well -graded gravel with silt Olf fines classify as CL-ML, use dual symbol GW-GC well -graded gravel with clay GC -GM, or SC-SM. GP -GM poorly graded gravel with silt "If fines are organic, add "with organic fines" GP -GC poorly graded gravel with clay to group name. 'Sands with 5 to 12% fines require dual 'If soil contains > 15% gravel, add "with symbols: gravel" to group name. SW-SM well -graded sand with silt 'If Atterberg limits plot in shaded area, soil is SW -SC well -graded sand with clay a CL-ML, silty clay. SP-SM poorly graded sand with silt SP-SC poorly graded sand with clay s0 50 X .0 C Z } 00 E U_ 20 a 10 7 4 UNIFIED SOIL CLASSIFICATION SYSTEM Soil Classification Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests Group Symbol Group Names Coarse -Grained Gravels more than Clean Gravels Less Cu > 4 and 1 < Cc <3E GW Well -graded Soils more than 50% of coarse than 5% finesc gravel` 50% retained on fraction retained on No. 200 sieve No. 4 sieve Cu < 4 and/or 1 > Cc > 3E GP Poorly graded gravel' Gravels with Fines more than 12% finesc Fines classify as ML or MH Y GM Silty y gravel,G,H Fines classify as CL or CH GC Clayey gravel-O-H Sands 50% or more Clean Sands Less Cu > 6 and 1 < Cc < 3E SW Well -graded sand' of coarse fraction than 5% finesE passes No. 4 sieve Cu < 6 and/or 1 > Cc > 3E SP Poorly graded sand' Sands with Fines Fines classify as ML or MH SM Silty sand'-"-' more than 12% fines° Fines Classify as CL or CH SC Clayey sand,"' Fine -Grained Soils Silts and Clays inorganic PI > 7 and plots on or above "A line CL Lean clay'-LM 50% or more Liquid limit less passes the than 50 PI < 4 or plots below "A" line ML SiltK.LM No. 200 sieve organic Liquid limit -oven dried Organic clayKLM," < 0.75 OL Liquid limit - not dried Organic siltKIL.M0 Silts and Clays inorganic PI plots on or above "A" line CH Fat clay`•LM Liquid limit 50 or more PI lots below "A" line MH Elastic Silt`E'M organic Liquid limit - oven dried Organic clayCLM.P < 0.75 OH Liquid limit - not dried Organic siltKE'M,O Highly organic soils Primarily organic matter, dark in color, and organic odor PT Peat Elf soil contains 15 to 29% plus No. 200, add .with sand" or "with gravel", whichever is predominant. Elf soil contains > 30% plus No. 200 predominantly sand, add "sandy" to group name. MY soil contains > 30% plus No. 200, predominantly gravel, add "gravelly" to group name. "PI > 4 and plots on or above "A" line. OPI < 4 or plots below "A" line. PPI plots on or above "A" line. OPI plots below "A" line. Far .1...ln.allan at In.a •.u. and Tina-wrala.d h.01.n of inane- 'nain.d • b Eauatian ofA LL 251 ��t] 2. Q Equation of V - fin., Ve/1i.a1 l LL - 19 to PI ), h 0.9 (LL - !) 0(L then G`r • � Q�r JOH OQ' MH o _— cL-ML , ML oIt OL 0 0 10 19 20 00 .o So w 70 E0 90 1a0 Tic LIQUID LIMIT (LL) lrerracon DRILLING AND EXPLORATION DRILLING & SAMPLING SYMBOLS: R : Ring Barrell - 2.42" I.D., 3" O.D., unless otherwise noted SS : Split Spoon - 1%" I.D., 2" O.D., unless otherwise noted PS : Piston Sample ST : Thin -Walled Tube - 2" O.D., unless otherwise noted WS : Wash Sample PA : Power Auger FT : Fish Tail Bit HA : Hand Auger RB : Rock Bit DB : Diamond Bit = 4", N, B BS : Bulk Sample AS: Auger Sample PM : Pressure Meter HS : Hollow Stem Auger DC : Dutch Cone WB : Wash Bore Penetration Test: Blows per foot of a 140 pound hammer falling 30 inches on a 2-inch O.D. split spoon, except where noted. WATER LEVEL MEASUREMENT SYMBOLS: WL : Water Level WS : While Sampling WCI : Wet Cave in WD :While Drilling DCI : Dry Cave in BCR : Before Casing Removal AB : After Boring ACR : After Casting Removal Water levels indicated on the boring logs are the levels measured in the borings at the time indicated. In pervious soils, the indicated levels may reflect the location of groundwater. In low permeability soils, the accurate determination of groundwater levels is not possible with only short term observations. DESCRIPTIVE SOIL CLASSIFICATION: Soil Classification is based on the Unified Soil Classification system and the ASTM Designations D-2487 and D-2488. Coarse Grained Soils have more than 50% of their dry weight retained on a #200 sieve; they are described as: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are described as: clays, if they are plastic, and silts if they are slightly plastic or non -plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse grained soils are defined on the basis of their relative in -place density and fine grained soils on the basis of their consistency. Example: Lean clay with sand, trace gravel, stiff (CL); silty sand, trace gravel, medium dense (SM). CONSISTENCY OF FINE-GRAINED SOILS: Unconfined Compressive Strength, Qu, psf Consistency < 500 Very Soft 500 - 1,000 Soft 1,001 - 2,000 Medium 2,001 - 4,000 Stiff 4,001 - 8,000 Very Stiff 8,001-16,000 Very Hard RELATIVE PROPORTIONS OF SAND AND GRAVEL Descriptive Term(s) (of Components Also Percent of Present in Sample) Dry Weight Trace < 15 With 15 - 29 Modifier > 30 RELATIVE PROPORTIONS OF FINES Descriptive Term(s) (of Components Also Percent of Present in Sample) Dry Weight Trace < 5 With 5-12 Modifier > 12 RELATIVE DENSITY OF COARSE -GRAINED SOILS: N-Blows/ft. Relative Density 0-3 Very Loose 4-9 Loose 10-29 Medium Dense 30-49 Dense 50-80 Very Dense 80+ Extremely Dense GRAIN SIZE TERMINOLOGY Major Component of Sample Size Range Boulders Over 12 in. (300mm) Cobbles 12 in. to 3 in. 1300mm to 75mm) Gravel 3 in. to #4 sieve (75mm to 4.75mm) Sand #4 to #200 sieve (4.75mm to 0.075mm) Silt or Clay Passing #200 Sieve (0.075mm) lrarracon SUMMARY OF TEST RESULTS PROJECT NO. 20965128 Boring No. Depth Ft. Moisture % Dry Density (PCF) Compressive Strength (PSF) Swell Pressure (PSF) Soluble Sulfates % pH Liquid Limit % Plasticity Index % Group Index Classification AASHTO USCS Resistivity (OHM -CM) Penetration Blow/In. 1 .5-1.5 10 11/12 3-4 14 113 21,810 1430 .0033 4-5 12 14/12 7-8 11 117 23,850 8-9 11 19/12 14-15 22 6/12 19-20 21 18/12 2 0-1 11 10/12 1-2 15/12 4-5 13 15/12 9-10 16 11/12 Comp. Samp. .5-4.0 35 18 11 A-601); CL 3 0-1 35 20 9 A-6(9); CL 8/12 1-2 13 12/12 4-5 11 12/12 9-10 10 14/12 Irerracon CONSULTANTS WESTERN, INC. 301 North Howes Street Fort Collins, Colorado 80521 (970) 484-0359 FAX (970) 484-0454 CLIENT: Safeway PROJECT: Harmony Market LOCATION: 2 @ 0.5-4 TERRACON NO. 20965128 CLASSIFICATION: See Att TEST SPECIMEN NO. 1 2 3 COMPACTION PRESSURE (PSI) 100 120 140 DENSITY (PCF) 101.5 104.7 106.2 MOISTURE CONTENT (%) 22.4 21.4 20.4 EXPANSION PRESSURE 0.00 0.00 0.00 HORIZONTAL PRESSURE @ 160 PSI 139 135 130 SAMPLE HEIGHT (INCHES) 2.52 2.47 2.52 EXUDATION PRESSURE (PSI) 257.8 290.4 319.0 CORRECTED R-VALUE 9.6 12.6 15.5 UNCORRECTED R-VALUE 9.7 12.4 15.6 R-VALUE @ 300 PSI EXUDATION PRESSURE = M 100 90 80 70 w 60 a 50 40 30 20 10 0 100 200 300 400 500 600 700 800 EXUDATION PRESSURE - PSI LOG OF BORINGNo. 3 Page 1 of 1 CLIENT ARCHITECT I ENGINEER Safeway Inc. Concept West Architecture, Inc. SITE Harmony Safeway Marketplace PROJECT Fort Collins, Colorado Sa e ay Store #1552 SAMPLES TESTS N >- - J } W m Cl) U DESCRIPTION Z\ H� w Cn H = m fA W W W � I to � H W O LL C.1' ZZ to (A W CHZ 0- F 0- 0 U m m W a. O U 3 HO fn H ylL ow UD_'IL W H H HELL CD Approx. Surface Elev.: 4975.5 ft. o z Od w m Z o a Cnn a CC_j N ^^" " 0.5 6" TOPSOIL 4975.0 SANDY LEAN CLAY CL 1 SS 12" 8 13 35/20/60 2 SS 12" 12 Brown to tan, dry to moist, Stiff to very stiff CL 3 SS 12" 12 10 5 4 SS 12" 14 1 10 10.0 4965.5 10 BOTTOM OF BORING THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL. WATER LEVEL OBSERVATIONS BORING STARTED 8-20-96 � g None W.D. =NoneEAE.B.]Irenracon RING COMPLETED N0.96 IL � CME-55 FoitE�tg DML Water checked 3 days A.B. APPROVED NRS JOB # 20965128 LOG OF BORING No. 2 Page 1 of 1 CLIENT ARCHITECT / ENGINEER Safeway Inc. Concept West Architecture, Inc. SITE Harmony Safeway Marketplace PROJECT Fort Collins, Colorado S ay Store #1552 SAMPLES TESTS \ } CD J } W � z U DESCRIPTION z\ H� w Un = x In W W W =0 1 cn :3W o LL cD zz m rn W Wiz a- t- N m W O 3 to O W W H H Q d U M U HO H >-LL L)WLL HzLL Approx. Surface Elev.: 4978.5 ft. C3 � z � W Cn ccoo E o a. m u) a. ¢ � 1-1-A' 0.5 6" TOPSOIL 4978.0 T $AN CLAY CL 1 SS 12" 10 11 2 SS 12" 15 2.0 Brown, dry to moist, stiff 4976.5 35/18/72 777 LEAN C T AY WT_TH SAND AND 3 BS GRAVEL Red to tan, moist, CL 4 SS 12" 15 13 Stiff to very stiff composite sample ® 0.5' - 4.0' S 5 SS 12" 11 16 10.0 4968.5 10 BOTTOM OF BORING THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL. WATER LEVEL OBSERVATIONS �� 0� I r BORING STARTED 8-20-96 g None W.D. IT None A B RING COMPLETED NO.96 v�vl RIG CME-55 FO�g DML W Water checked 3 days A.B. APPROVED NRS JOB � 20965128 LOG OF BORING No. 1 Page 1 of 1 CLIENT ARCHITECT / ENGINEER Safeway Inc. Concept West Architecture, Inc. SITE harmony Safeway Marketplace PROJECT Fort Collins, Colorado S ay Store #1552 SAMPLES TESTS W M E z W d w O G.L X Z\ i to 3 I-O U)CO ? F- fn H = � w O YLL oa o FAF- ZZ O W UWLL �Na JLn J fn WWI_ waa 0 H = 0- DESCRIPTION Approx. Surface Elev.: 4979.0 ft. 2 F d Wo o N fn U � "A"A" 0.5 6" TOPSOIL 4978.5 LEAN CLAY Brown, dry to moist, stiff CL 1 SS 12" 11 10 P/z' 3.5 4975.5 1430 2 ST 12" 14 113 21810 CL 3 SS 12" 14 12 LF-AN CLAY WITH SAND AND GRAVEL 5 Red to tan, moist to wet Medium to very hard 625 4 ST 12" 11 117 23850 5 SS 12" 19 11 = 10 Sz 6 SS 1 12" 6 1 22 15 17.5 4961.5 SILTY SAND Tan, wet, medium dense SM 7 SS 12" 18 1 21 20.0 4959.0 20 BOTTOM OF BORING THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL. WATER LEVEL OBSERVATIONS BORING STARTED 8-20-96 WL 1Z 14.6 W.D. 10.3 A.B. BORING COMPLETED 8-20-96 WLIrerracon RIG CME-55 FOREMAN DML WL Water checked 3 da s A.B. APPROVED NRS JOB a 20965128 No`3\' GG `\ TBM MANHOLE (fin `tl - CAI? o� No.30 RIM = ELEV. 4981.3'\`O / *No.4 No.9 `�-i' • No.27 No. •2 5 • No.15 \No. ' /' PROPOSED 3 • `j • No.4 SAFEWAY \ BUILDING • No.14 • No.10 • No.26 FF=ELEV. 80.5 • No.16 \ \� W • No.3 N• o.17 • No.24 , • No.18 1 •No.13 Q, • No.11 • No.25 I' i B Ns.3 Z •No.2 OI I No. • • No.12 • No.19 No.2 • No.32 FIGURE 1: SITE PLAN HARMONY SAFEWAY MARKETPLACE FORT COLLINS, COLORADO TCW INC. PROJECT No. 20965128 • No.20 • No.21 HARMONY ROAD LEGEND • BORING DRILLED IN OCTOBER 1980 BORING DRILLED IN AUGUST 1996 • No.22 D `W a a 2 CCU G • No.29 N SCALE 1" = 200' .1rerracon CONSULTANTS WESTERN. INC. EMPIRE DIVISION Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 GENERAL COMMENTS It is recommended that the Geotechnical Engineer be retained to provide a general review of final design plans and specifications in order to confirm that grading and foundation recommendations have been interpreted and implemented. In the event that any changes of the proposed project are planned, the conclusions and recommendations contained in this report should be reviewed and the report modified or supplemented as necessary. The Geotechnical Engineer should also be retained to provide services during excavation, grading, foundation and construction phases of the work. Observation of footing excavations should be performed prior to placement of reinforcing and concrete to confirm that satisfactory bearing materials are present and is considered a necessary part of continuing geotechnical engineering services for the project. Construction testing, including field and laboratory evaluation of fill, backfill, pavement materials, concrete and steel should be performed to determine whether applicable project requirements have been met. It would be logical for Terracon Consultants Western, Inc. to provide these additional services for continuing from design through construction and to determine the consistency of field conditions with those data used in our analyses. The analyses and recommendations in this report are based in part upon data obtained from the field exploration. The nature and extent of variations beyond the location of test borings may not become evident until construction. If variations then appear evident, it may be necessary to re-evaluate the recommendations of this report. Our professional services were performed using that degree of care and skill ordinarily exercised, under similar circumstances, by reputable geotechnical engineers practicing in this or similar localities. No warranty, express or implied, is made. We prepared the report as an aid in design of the proposed project. This report is not a bidding document. Any contractor reviewing this report must draw his own conclusions regarding site conditions and specific construction techniques to be used on this project. This report is for the exclusive purpose of providing geotechnical engineering and/or testing information and recommendations. The scope of services for this project does not include, either specifically or by implication, any environmental assessment of the site or identification of contaminated or hazardous materials or conditions. If the owner is concerned about the potential for such contamination, other studies should be undertaken. 19 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 Additional Design and Construction Considerations Exterior Slab Design and Construction Exterior slabs -on -grade, exterior architectural features, and utilities founded on, or in backfill may experience some movement due to the volume change of the backfill. Potential movement could be reduced by: • minimizing moisture increases in the backfill • controlling moisture -density during placement of backfill • using designs which allow vertical movement between the exterior features and adjoining structural elements • placing effective control joints on relatively close centers • allowing vertical movements in utility connections Underground Utility Systems All piping should be adequately bedded for proper load distribution. It is suggested that clean, graded gravel compacted to 75 percent of Relative Density ASTM D4253 be used as bedding. Where utilities are excavated below groundwater, temporary dewatering will be required during excavation, pipe placement and backfilling operations for proper construction. Utility trenches should be excavated on safe and stable slopes in accordance with OSHA regulations as discussed above. Backfill should consist of the on -site soils or existing bedrock. If bedrock is used, all plus 6-inch material should be removed from it prior to its use. The pipe backfill should be compacted to a minimum of 95 percent of Standard Proctor Density ASTM D698. All underground piping within or near the proposed structure should be designed with flexible couplings, so minor deviations in alignment do not result in breakage or distress. Utility knockouts in grade beams should be oversized to accommodate differential movements. Corrosion Protection Results of soluble sulfate testing indicate that ASTM Type 1-II Portland cement is suitable for all concrete on or below grade. Foundation concrete should be designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4. 18 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 Drainage Surface Drainage: Positive drainage should be provided during construction and maintained throughout the life of the proposed construction. Infiltration of water into utility or foundation excavations must be prevented during construction. Planters and other surface features which could retain water in areas adjacent to the building or pavements should be sealed or eliminated. 2. In areas where sidewalks or paving do not immediately adjoin the structure, we recommend that protective slopes be provided with a minimum grade of approximately 5 percent for at least 10 feet from perimeter walls. Backfill against footings, exterior walls and in utility and sprinkler line trenches should be well compacted and free of all construction debris to reduce the possibility of moisture infiltration. 3. Downspouts, roof drains or scuppers should discharge into splash blocks or extensions when the ground surface beneath such features is not protected by exterior slabs or paving. 4. Sprinkler systems should not be installed within 5 feet of foundation walls. Landscaped irrigation adjacent to the foundation system should be minimized or eliminated. Subsurface Drainage Free -draining, granular soils containing less than five percent fines (by weight) passing a No. 200 sieve should be placed adjacent to walls which retain earth. A drainage system consisting of either weep holes or perforated drain lines (placed near the base of the wall) should be used to intercept and discharge water which would tend to saturate the backfill. Where used, drain lines should be embedded in a uniformly graded filter material and provided with adequate clean -outs for periodic maintenance. An impervious soil should be used in the upper layer of backfill to reduce the potential for water infiltration. 17 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 Maximum Slope Material Horizontal•Vertical Cohesive soils (clays).................................................................................3:1 Detention pond slopes................................................................................3:1 If steeper slopes are required for site development, stability analyses should be completed to design the grading plan. Compliance Performance of slabs -on -grade, foundations and pavement elements supported on compacted fills or prepared subgrade depend upon compliance with "Earthwork" recommendations. To assess compliance, observation and testing should be performed under the direction of the geotechnical engineer. Excavation and Trench Construction Excavations into the on -site soils will encounter a variety of conditions. Excavations into the clays can be expected to stand on relatively steep temporary slopes during construction. However, caving soils and/or groundwater may also be encountered. The individual contractor(s) should be made responsible for designing and constructing stable, temporary excavations as required to maintain stability of both the excavation sides and bottom. All excavations should be sloped or shored in the interest of safety following local and federal regulations, including current OSHA excavation and trench safety standards. The soils to be penetrated by the proposed excavations may vary significantly across the site. The preliminary soil classifications are based solely on the materials encountered in widely spaced exploratory test borings. The contractor should verify that similar conditions exist throughout the proposed area of excavation. If different subsurface conditions are encountered at the time of construction, the actual conditions should be evaluated to determine any excavation modifications necessary to maintain safe conditions. As a safety measure, it is recommended that all vehicles and soil piles be kept to a minimum lateral distance from the crest of the slope equal to no less than the slope height. The exposed slope face should be protected against the elements. 16 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 beneath pavement should be compacted within a moisture content range of 2 percent below to 2 percent above optimum. 5. Granular soils should be compacted within a moisture content range of 3 percent below to 3 percent above optimum unless modified by the project geotechnical engineer. 6. If a well defined maximum density curve cannot be generated by impact compaction in the laboratory for any fill type, engineered fill should be compacted to a minimum of 75 percent relative density as determined by ASTM D4253 D4254. Shrinkage For balancing grading plans, estimated shrink or swell of soils and bedrock when used as compacted fill following recommendations in this report are as follows: Material Estimated Shrink(-) Swell (+) Based on ASTM D698 On -site soils: Clays.....................................................................................15 to -20% Slopes: 1. For permanent slopes in compacted fill areas, maximum slope angles of 2'/:1 (horizontal to vertical) for on -site materials are recommended. If steeper slopes are required for site development, stability analyses should be completed to design the grading plan. 2. The face of all slopes should be compacted to the minimum specification for fill embankments. Alternately, fill slopes can be over -built and trimmed to compacted material. 3. For permanent slopes in cut areas, the following maximum angles are recommended as follows: 15 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 Percent fines by weight Gradation (ASTM C1361 611 .......................................................................................................... 100 3".....................................................................................................70-100 No. 4 Sieve........................................................................................50-80 No. 200 Sieve...............................................................................50 (max) LiquidLimit.......................................................................35 (max) Plasticity Index..................................................................15 (max) MinimumR-value.......................................................................14 6. Aggregate base should conform to Colorado Department of Transportation Class 5 or 6 specifications. Placement and Compaction: 1. Place and compact fill in horizontal lifts, using equipment and procedures that will produce recommended moisture contents and densities throughout the lift. 2. No fill should be placed over frozen ground. 3. Materials should be compacted to the following: Material Minimum Percent Compaction (ASTM D698) Subgrade soils beneath fill areas.........................................................................95 On -site soils or approved imported fill: Beneath foundations...........................................................................98 Beneathslabs.....................................................................................95 Beneath pavements............................................................................95 Utilities.................................................................................................95 Aggregate base (beneath slabs).........................................................95 Miscellaneous backfill.........................................................................90 4. Clay soils placed around or beneath foundations should be compacted within a moisture content range of optimum to 2 percent above optimum. Clay soils placed 14 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 2. Depending upon depth of excavation and seasonal conditions, groundwater may be encountered in excavations on the site. Pumping from sumps may be utilized to control water within excavations. Well points may be required for significant groundwater flow or where excavations penetrate groundwater to a significant depth. 3. On -site clay soils in proposed pavement areas may pump or become unstable or unworkable at high water contents. Workability may be improved by scarifying and drying. Overexcavation of wet zones and replacement with granular materials may be necessary. Lightweight excavation equipment may be required to reduce subgrade pumping. [Minimizing construction traffic on -site is recommended.] Use of lime, fly ash, kiln dust, cement or geotextiles could also be considered as a stabilization technique. Laboratory evaluation is recommended to determine the effect of chemical stabilization on subgrade soils prior to construction. Proof -rolling of the subgrade may be required to determine stability prior to paving. Fill Materials: 1. Clean on -site soils or approved imported materials may be used as fill material for the following: jet general site grading exterior slab areas • foundation areas pavement areas • interior floor slab areas foundation backfill 2. On -site soils are not recommended for use beneath slabs or as backfiR. _ 3. Select granular materials should be used as backfill behind retaining walls. 4. Frozen soils should not be used as fill or backfill. 5 . Imported soils (if required) should conform to the following or be approved by the Project Geotechnical Engineer: 13 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 the first priority when implementing a planned pavement maintenance program and provides the highest return on investment for pavements. Recommended preventative maintenance policies for asphalt and jointed concrete pavements, based upon type and severity of distress, are provided in Appendix D. Prior to implementing any maintenance, additional engineering observation is recommended to determine the type and extent of preventative maintenance. Earthwork • Site Clearing and Subgrade Preparation: Strip and remove existing vegetation, debris, and other deleterious materials from proposed building and pavement areas. All exposed surfaces should be free of mounds and depressions which could prevent uniform compaction. 2. If unexpected fills or underground facilities are encountered during site clearing, such features should be removed and the excavation thoroughly cleaned prior to backfill placement and/or construction. All excavations should be observed by the geotechnical engineer prior to backfill placement. 3. Stripped materials consisting of vegetation and organic materials should be wasted from the site or used to revegetate exposed slopes after completion of grading operations. If it is necessary to dispose of organic materials on -site, they should be placed in non-structural areas and in fill sections not exceeding 5 feet in height. 4. The site should be initially graded to create a relatively level surface to receive fill, and to provide for a relatively uniform thickness of fill beneath proposed building structures. 5. All exposed areas which will receive fill, floor slabs and/or pavement, once properly cleared and benched where necessary, should be scarified to a minimum depth of 8 inches, conditioned to near optimum moisture content, and compacted. Excavation: 1. It is anticipated that excavations for the proposed construction can be accomplished with conventional earthmoving equipment. 12 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20966128 Longitudinal and transverse joints should be provided as needed in concrete pavements for expansion/contraction and isolation. The location and extent of joints should be based upon the final pavement geometry and should be placed (in feet) at roughly twice the slab thickness (in inches) on center in either direction. Sawed joints should be cut within 24-hours of concrete placement, and should be a minimum of 25% of slab thickness plus 1/4 inch. All joints should be sealed to prevent entry of foreign material and dowelled where necessary for load transfer. Future performance of pavements constructed on the clay soils at this site will be dependent upon several factors, including: • maintaining stable moisture content of the subgrade soils and • providing for a planned program of preventative maintenance. Since the clay soils on the site have shrink/swell characteristics, pavements could crack in the future primarily because of expansion of the soils when subjected to an increase in moisture content to the subgrade. The cracking, while not desirable, does not necessarily constitute structural failure of the pavement. The performance of all pavements can be enhanced by minimizing excess moisture which can reach the subgrade soils. The following recommendations should be considered at minimum: • Site grading at a minimum 2% grade away from the pavements; • Compaction of any utility trenches for landscaped areas to the same criteria as the pavement subgrade; • Sealing all landscaped areas in or adjacent to pavements to minimize or prevent moisture migration to subgrade soils; • Placing compacted backfill against the exterior side of curb and gutter; and, • Placing curb, gutter and/or sidewalk directly on subgrade soils without the use of base course materials. Preventative maintenance should be planned and provided for an on -going pavement management program in order to enhance future pavement performance. Preventative maintenance activities are intended to slow the rate of pavement deterioration and to preserve the pavement investment. Preventative maintenance consists of both localized maintenance (e.g. crack sealing and patching) and global maintenance (e.g. surface sealing). Preventative maintenance is usually 11 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 Aggregate base course (if used on the site) should consist of a blend of sand and gravel which meets strict specifications for quality and gradation. Use of materials meeting Colorado Department of Transportation (CDOT) Class 5 or 6 specifications is recommended for base course. Aggregate base course should be placed in lifts not exceeding six inches and should be compacted to a minimum of 95% Standard Proctor Density (ASTM D698). Asphalt concrete and/or plant -mixed bituminous base course should be composed of a mixture of aggregate, filler and additives, if required, and approved bituminous material. The bituminous base and/or asphalt concrete should conform to approved mix designs stating the Hveem properties, optimum asphalt content, job mix formula and recommended mixing and placing temperatures. Aggregate used in plant -mixed bituminous base course and/or asphalt concrete should meet particular gradations. Material meetin Col ortation Grading C or CX s ecification is rec s halt concrete. Aggregate meeting is recommended for plant -mixed bituminous base course. Mix designs should be submitted prior to construction to verify their adequacy. Asphalt material should be placed in maximum 3-inch lifts and should be compacted to a minimum of 95% Hveem density (ASTM D1560) (ASTM D1561). Where rigid pavements are used, the concrete should be obtained from an approved mix design with the following minimum properties: • Modulus of Rupture @ 28 days.......................................................600 psi minimum • Strength Requirements............................................................................. ASTM C94 Minimum Cement Content............................................................... 6.5 sacks/cu. yd. • Cement Type......................................................................................Type I Portland • Entrained Air Content......................................................................................6 to 8% • Concrete Aggregate ............................................ ASTM C33 and CDOT Section 703 AggregateSize..................................................................................1 inch maximum • Maximum Water Content.............................................................0.49 lb/lb of cement • Maximum Allowable Slump............................................................................4 inches Concrete should be deposited by truck mixers or agitators and placed a maximum of 90 minutes from the time the water is added to the mix. Other specifications outlined by the Colorado Department of Transportation should be followed. 10 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 characteristics are considered to control the design. These characteristics, coupled with the approximate duration of saturated subgrade conditions, results in a design drainage coefficient of 1.0 when applying the AASHTO criteria for design. For flexible pavement design, a terminal serviceability index of 2.0 was utilized along with an inherent reliability of 70% and a design life of 20 years. Using the correlated design R-value of 13, appropriate ESAUday, environmental criteria and other factors, the structural numbers (SN) of the pavement sections were determined on the basis of the 1986 AASHTO design equation. In addition to the flexible pavement design analyses, a rigid pavement design analysis was completed, based upon AASHTO design procedures. Rigid pavement design is based on an evaluation of the Modulus of Subgrade Reaction of the soils (K-value), the Modulus of Rupture of the concrete, and other factors previously outlined. The design K-value of 100 for the subgrade soil was determined by correlation to the laboratory tests results. A modulus of rupture of 600 psi (working stress 488 psi) was used for pavement concrete. The rigid pavement thicknesses for each traffic category were determined on the basis of the AASHTO design equation. Recommended alternatives for flexible and rigid pavements, summarized for each traffic area, are as follows and should replace pavement recommendations discussed in the original report: Traffic Area : AltemaNve Recommended'Pavementihlckr esses �Inchesj Asphak Aggregate Plant Mixed Portland Total ...... Base Course Bituminous Cement '. . Surface Base .. Concrete Automobile A 3 4 7 Parking B 2 2'/2 4'/2 C 5 5 Main Traffic A 3 6 9 Corridors B 2 3Yz 5'/a C 6% 6Y: Each alternative should be investigated with respect to current material availability and economic conditions. 0 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 Berm Dewatering System To reduce the potential for surface water to enter the building subsurface adjacent to the proposed berm, installation of a dewatering system is recommended. The dewatering system should include a perimeter drainage system. The drainage system should be constructed along to the north side of the building adjacent to the berm and should consist of a properly sized perforated pipe, embedded in free -draining gravel, placed in a trench at least 12 inches in width. The pipe should be placed a minimum of one foot below the finished floor. The gravel should extend a minimum of 3 inches beneath the bottom of the pipe to within 1 foot above the top of the berm above the pier. The gravel should be covered with drainage fabric and backfilled with on -site clay material and topsoil. A manufactured wall drain, such as Contech StripDrain, may be used in place of a conventional pipe and gravel drainage system. The drainage system should slope at least 1/8 inch per foot and should daylight into the detention pond to the east or empty into a suitable outlet, such as a storm drain or sump and pump system. Pavement Design and Construction Design of pavements for the project have been based on the procedures outlined in the 1986 Guideline for Design of Pavement Structures by the American Association of State Highway and Transportation Officials (AASHTO). Pavement recommendations discussed below reflect current standards. Areas within proposed pavements on the site will be divided into two categories based upon anticipated traffic and usage. Traffic criteria provided for pavement thickness designs include equivalent 18-kip single axle loads (ESAL's) of 21,900 for automobile parking, and 87,500 for driveways and truck access. The traffic data is based on information provided by Safeway, Inc., which includes approximately four semi -tractor trailers and 20 delivery trucks per week. Based upon AASHTO criteria, Colorado is located within Climatic Region VI of the United States. This region is characterized as being dry, with hard ground freeze and spring thaw. The spring thaw condition typically results in saturated or near -saturated subgrade soil moisture conditions. The AASHTO criteria suggests that these moisture conditions are prevalent for approximately 12-1/2% of the annual moisture variation cycle. Local drainage characteristics of proposed pavement areas are considered to vary from fair to good depending upon location on the site. For purposes of this design analysis, fair drainage rl Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 subsurface materials, a seismic site coefficient, "s" of 1.0 should be used for the design of structures for the proposed project (1994 Uniform Building Code, Table No. 16-J). Floor Slab Design and Construction In general, low to moderate expansive soils or engineered fill will support the floor slab. However, thin layers of moderate to high expansive soils were encountered at the site. Therefore, some differential movement of a slab -on -grade floor system is possible should the subgrade soils increase in moisture content. Such movements are normally within general tolerance for slab -on -grade construction. To reduce potential slab movements, the subgrade soils should be prepared as outlined in the "Earthwork" section of this report. Additional floor slab design and construction recommendations are as follows: • Positive separations and/or isolation joints should be provided between slabs and all foundations, columns or utility lines to allow independent movement. • Contraction joints should be provided in slabs to control the location and extent of cracking. The American Concrete Institute (ACI) recommends the control joint spacing in feet for nonstructural slabs should be 2 to 3 times the slab thickness in inches in both directions. Maximum joint spacing of 15 to 20 feet in each direction is recommended. Sawed or tooled joints should have a minimum depth of 25% of slab thickness plus % inch. • Interior trench backfill placed beneath slabs should be compacted in accordance with recommended specifications outlined below. • In areas subjected to normal loading, a minimum 4-inch layer of clean -graded gravel should be placed beneath interior slabs. Slabs supporting heavy loading should be underlain by a minimum 6-inch layer of crushed aggregate base course. • If moisture sensitive floor coverings are used on interior slabs, consideration should be given to the use of barriers to minimize potential vapor rise through the slab. • Floor slabs should not be constructed on frozen subgrade. • Other design and construction considerations, as outlined in the ACI Design Manual, Section 302.1 R are recommended. For structural design of concrete slabs -on -grade, a modulus of subgrade reaction of 100 pounds per cubic inch (pci) may be used for floors supported on existing or engineered fill consisting of on -site soils. A modulus of 150 pci may be used for floors supported on a minimum of 6 inches of crushed aggregate base course. 7 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 Foundations and masonry walls should be reinforced as necessary to reduce the potential for distress caused by differential foundation movement. The use of joints at openings or other discontinuities in masonry walls is recommended. Foundation excavations should be observed by the geotechnical engineer. If the soil conditions encountered differ from those presented in this report, supplemental recommendations will be required. Lateral Earth Pressures For soils above any free water surface, recommended equivalent fluid pressures for unrestrained foundation elements are: • Active: • Cohesive soil backfill (clay)............................................................................ 45 psf/ft • Passive: • Cohesive soil backfill (clay).......................................................................... 350 psf/ft • Adhesion at base of footing................................................................................. 500 psf Where the design includes restrained elements, the following equivalent fluid pressures are recommended: • At rest: • Cohesive soil backfill (clay)............................................................................ 60 psf/ft The lateral earth pressures herein are not applicable for submerged soils. Additional recommendations may be necessary if such conditions are to be included in the design. Fill against grade beams and retaining walls should be compacted to densities specified in "Earthwork". Medium to high plasticity clay soils should not be used as backfill against retaining walls. Compaction of each lift adjacent to walls should be accomplished with hand - operated tampers or other lightweight compactors. Overcompaction may cause excessive lateral earth pressures which could result in wall movement. Seismic Considerations The project site is located in Seismic Risk Zone I of the Seismic Zone Map of the United States as indicated by the 1994 Uniform Building Code. Based upon the nature of the I Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 CONCLUSIONS AND RECOMMENDATIONS Geotechnical Considerations The subsurface conditions encountered during this investigation are consistent with those described in our October 17, 1980 report. The recommendations presented in that report may be used. For convenience, the are summarized in the following paragraphs. The site appears suitable for the proposed construction from a geotechnical engineering point of view. Potentially expansive soils will require particular attention in the design and construction. The following foundation systems were evaluated for use on the site: spread footings and/or grade beams bearing on undisturbed soils; and, spread footings and/or grade beams bearing on engineered fill. Slab -on -grade construction is considered acceptable for use, provided that design and construction recommendations are followed. Foundation Systems Due to the presence of expansive soils on the site, spread footing and/or grade beam foundations bearing upon undisturbed subsoils and/or engineered fill are recommended for support for the proposed structure. The footings and/or grade beams may be designed for a maximum bearing pressure of 2,000 psf. In addition, the footings should be sized to maintain a minimum dead -load pressure of 500 psf. The design bearing pressure applies to dead loads plus design live load conditions. The design bearing pressure may be increased by one-third when considering total loads that include wind or seismic conditions. Exterior footings should be placed a minimum of 30 inches below finished grade for frost protection. Finished grade is the lowest adjacent grade for perimeter footings. Footings should be proportioned to minimize differential foundation movement. Proportioning on the basis of equal total settlement is recommended; however, proportioning to relative constant dead -load pressure will also reduce differential settlement between adjacent footings. Total settlement resulting from the assumed structural loads is estimated to be on the order of 3/4 inch. Proper drainage should be provided in the final design and during construction to reduce the settlement potential. 5 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 • Silty Topsoil: The area tested is overlain by a 6-inch layer of silty topsoil. The topsoil has been penetrated by root growth and organic matter. • Lean Clay: This stratum underlies the topsoil in Borings 1 and 2 and extends to depths of 2 to 3'/2 feet below the surface. The lean clay is dry to moist and stiff in consistency. • Lean Clay with Sand: A layer of lean clay with sand underlies the upper lean clay in Borings 1 and 2 and extends to depths of 10 to 12% feet below the surface. The lean clay with sand contains gravel, is moist to wet and medium to very hard in consistency. • Sandy Lean Clay: A layer of red sandy lean clay underlies the topsoil in Boring 3 and extends beyond the depths explored. The red sandy lean clay is dry to moist and stiff to very stiff in consistency. • Silty Sand: The silty sand stratum was encountered in Boring 1 at a depth of 17'/ feet and extends beyond the depths explored. The silty sand is medium dense and wet in situ. Field and Laboratory Test Results Field and laboratory test results indicate the clay soils at the site exhibit moderate to high swell potential and moderate to high bearing characteristics. Groundwater Conditions Groundwater was observed in Boring 1 at an approximate depth of 14%2 feet at the time of field exploration. Borings 2 and 3 were dry at the time of drilling. When checked three days after drilling, free groundwater was encountered in Boring 1 at an approximate depth of 10'/ feet below the surface, and Borings 2 and 3 remained dry. These observations represent only current groundwater conditions, and may not be indicative of other times, or at other locations. Groundwater levels can be expected to fluctuate with varying seasonal and weather conditions. 4 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20966128 Groundwater measurements were made in each boring at the time of site exploration, and three days after drilling. Laboratory Testing All samples retrieved during the field exploration were returned to the laboratory for observation by the project geotechnical engineer, and were classified in accordance with the Unified Soil Classification System described in Appendix C. At that time, the field descriptions were confirmed or modified as necessary and an applicable laboratory testing program was formulated to determine engineering properties of the subsurface materials. Boring logs were prepared and are presented in Appendix A. Selected soil samples were tested for the following engineering properties: • Water content • Dry density • Consolidation • Compressive strength • Expansion • Plasticity Index • R-value • Water soluble sulfate content The significance and purpose of each laboratory test is described in Appendix C. Laboratory test results are presented in Appendix B, and were used for the geotechnical engineering analyses, and the development of foundation and earthwork recommendations. All laboratory tests were performed in general accordance with the applicable ASTM, local or other accepted standards. SITE CONDITIONS The site consists of a vacant tract of land vegetated with native grasses and weeds. A grass berm and trees are located along the south edge of the site adjacent to Harmony Road. The property is relatively flat and has minor drainage to the east. The site is bordered to the north by Monte Carlo Drive, to the east by McMurray Drive, to the west by Wheaton Drive, and to the south by Harmony Road. SUBSURFACE CONDITIONS Soil Conditions The following describes the characteristics of the primary soil strata in order of increasing depths: 3 Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 require approximately one foot of fill below the majority of the proposed Safeway Store. A large berm will be constructed along the north side of the proposed Safeway building. Parking and drive areas will be constructed along the front of the proposed Safeway Store and other building pads. A detention pond is proposed in the northeast comer of the site. PREVIOUS REPORT Thirty-four test borings were previously drilled at the site for a neighborhood center by Empire Laboratories, Inc., our predecessor firm. A Report of a Geotechnical Investigation was prepared for the site in October of 1980. SITE EXPLORATION The scope of the services performed for this project included site reconnaissance by an engineering geologist, a subsurface exploration program, laboratory testing and engineering analysis. Field Exploration A total of three test borings were drilled on August 20, 1996 to depths of 9 to 20 feet at the locations shown on the Site Plan, Figure 1. One boring was drilled within the footprint of the proposed building, and two borings were drilled in the area of proposed pavements. All borings were advanced with a truck -mounted drilling rig, utilizing 4-inch diameter solid stem auger. The Borings were located in the field by pacing from property lines and/or existing site features. Elevations were taken at each boring location by measurements with an engineer's level from a temporary bench mark (TBM) shown on the Site Plan. The accuracy of boring locations and elevations should only be assumed to the level implied by the methods used. Continuous lithologic logs of each boring were recorded by the engineering geologist during the drilling operations. At selected intervals, samples of the subsurface materials were taken by pushing thin -walled Shelby tubes, or by driving split -spoon samplers. Representative bulk samples of subsurface materials were obtained from pavement borings. Penetration resistance measurements were obtained by driving the split -spoon into the subsurface materials with a 140-pound hammer falling 30 inches. The penetration resistance value is a useful index to the consistency, relative density or hardness of the materials encountered. 2 SUPPLEMENTAL GEOTECHNICAL ENGINEERING REPORT PROPOSED SAFEWAY STORE NO. 1552 HARMONY SAFEWAY MARKET PLACE FORT COLLINS, COLORADO Project No. 20965128 September 6, 1996 INTRODUCTION This report contains the results of our supplemental geotechnical engineering exploration for the proposed Safeway Store No. 1552 to be located on Harmony Road between Wheaton Drive and McMurray Avenue in southeast Fort Collins, Colorado. The site is located in the Southwest 1/4 of Section 31, Township 7 North, Range 68 West of the 6th Principal Meridian. The purpose of these services is to provide additional information and geotechnical engineering recommendations relative to: • subsurface soil conditions • groundwater conditions • foundation design and construction • lateral earth pressures • floor slab design and construction • pavement design and construction • earthwork • drainage The conclusions and recommendations contained in this report are based upon the results of field and laboratory testing, engineering analyses, our experience with similar soil conditions and structures and our understanding of the proposed project. PROPOSED CONSTRUCTION Based on information provided by Safeway, Inc., the proposed structure will be a single -story, slab -on -grade supermarket. Additional building pads for future construction will be built in conjunction with the Safeway building. Parking and drive areas will be constructed for the entire project. The finished first floor of the building will be placed at elevation 80.50. This will Supplemental Geotechnical Engineering Exploration Safeway, Inc. Project No. 20965128 TABLE OF CONTENTS (cont'd) Page No. GENERAL COMMENTS.....................................................................................................19 APPENDIX A Site Plan and Boring Location Diagram Logs of Borings APPENDIX B Laboratory Test Results APPENDIX C General Notes APPENDIX D Pavement Notes IV TABLE OF CONTENTS Page No. Letterof Transmittal.................................................................................................................. ii INTRODUCTION.................................................................................................................1 PROPOSEDCONSTRUCTION..........................................................................................1 PREVIOUS REPORT..........................................................................................................2 SITEEXPLORATION..........................................................................................................2 FieldExploration......................................................................................................2 LaboratoryTesting................................................................................................... 3 SITECONDITIONS.............................................................................................................3 SUBSURFACE CONDITIONS.............................................................................................3 SoilConditions.........................................................................................................3 Field and Laboratory Test Results........................................................................... 4 Groundwater Conditions..........................................................................................4 CONCLUSIONS AND RECOMMENDATIONS.................................................................... 5 Geotechnical Considerations...................................................................................5 FoundationSystems................................................................................................5 Lateral Earth Pressures...........................................................................................6 Seismic Considerations........................................................................................... 6 Floor Slab Design and Construction........................................................................ 7 BermDewatering System........................................................................................ 8 Pavement Design and Construction......................................................................... 8 Earthwork................................................................................................................12 Site Clearing and Subgrade Preparation......................................................12 Excavation...................................................................................................12 FillMaterials.................................................................................................13 Placement and Compaction.........................................................................14 Shrinkage.....................................................................................................15 Slopes..........................................................................................................15 Compliance..................................................................................................16 Excavation and Trench Construction............................................................16 Drainage..................................................................................................................17 SurfaceDrainage.........................................................................................17 SubsurfaceDrainage...................................................................................17 Additional Design and Construction Considerations.................................................18 Exterior Slab Design and Construction.........................................................18 Underground Utility Systems........................................................................18 CorrosionProtection....................................................................................18 N Supplemental Geotechnical Engineering Exploration Safeway, Inc. Terracon Project No. 20966128 We appreciate the opportunity to be of service to you on this phase of your project. If you have any questions concerning this report, or if we may be of further service to you, please do not hesitate to contact us. Sincerely, TERRACON CONSULTANTS WE TARN, INC. Empire Division ktof HOF& Prepared by: ��,.�v75u�BF``g Reviewed by: .�``��P��•RF��sl'''%. 18829 ^,,.yF'•••«'«'•M o° �` Wi liam J. Attwooll �o •' `" eil od "?,o(q. SHEAF `o� ,'•. .: Senior ngineering Geologis P�CFggp Office Manager '''�i,�`sS� ••••••�C��'\��`' Copies to: Addressee (2) 'yip//1ONA� Concept West Architecture, Inc. - Mr. Gary Harrison (2) September 6, 1996 Safeway, Inc. 6900 South Yosemite Englewood, Colorado 80011 Attn: Mr. Cam Potter Director of Denver/Phoenix Division Re: Supplemental Geotechnical Engineering Report Proposed Safeway Store No. 1552 Harmony Safeway Market Place Fort Collins, Colorado Project No. 20965128 Terracon Consultants Western, Inc., Empire Division has completed a supplemental geotechnical engineering exploration for the proposed Safeway Store to be located on Harmony Road in southeast Fort Collins, Colorado. This study was performed in general accordance with our proposal number D2096150 dated August 2, 1996. The results of our engineering study, including the boring location diagram, laboratory test results, test boring records, and the geotechnical recommendations needed to aid in the design and construction of foundations and other earth connected phases of this project are attached. The subsoils at the site consist of lean clay, lean'clay with sand and sandy lean clay. The clay materials recently tested are moderately to highly expansive. The soils at the site are similar to those described in a "Report of a Geotechnical Investigation" prepared for a neighborhood center at the site in October of 1980 by Empire Laboratories, Inc., our predecessor firm. Due to the type of construction proposed for the site, it is recommended the structures be supported by conventional -type spread footing and/or grade beam foundation systems. This is consistent with the foundation recommendations previously made at the site. Further details are provided in this report. I V SUPPLEMENTAL GEOTECHNICAL ENGINEERING REPORT PROPOSED SAFEWAY STORE NO. 1552 HARMONY SAFEWAY MARKET PLACE FORT COLLINS, COLORADO PROJECT NO. 20965128 September 6, 1996 Prepared for. SAFEWAY, INC. 6900 SOUTH YOSEMITE ENGLEWOOD, COLORADO 80112 ATTN: MR. CAM POTTER DIRECTOR OF DENVERIPHOENIX DIVISION Prepared by. Terracon Consultants Western, Inc. Empire Division 301 North Howes Street Fort Collins, Colorado 80521 lrarracon