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HomeMy WebLinkAboutHAMPSHIRE POND PUD PRELIMINARY - 44 93 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTTABLE 02 RECOMMENDED PREVENTATIVE MAINTENANCE POLICY FOR JOINTED CONCRETE PAVEMENTS Distress Distress Recommended Distress Distress Recommended Type Severity Maintenance Type Severity Maintenance Low None No Polished Severity Groove Surface Blow-up Medium Full -Depth Aggregate Levels or Concrete Patch/ Overlay High Slab Replacement Defined Low Seal Cracks No Comer Pts opou Severity Levels None Medium Full -Depth Break High Concrete Patch Defined Low Seal Cracks No Underseal, Seal cracksljoints Medium Divided Pumping Severity and Slab Slab Levels Restore High Replacement Defined 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 Faulting Railroad Crossing Policy for this Medium Medium High High Grind Project Low None Scaling Low None Medium Medium Slab Replacement, Joint Map Cracking Seal Reseal Crazing Full -depth Patch, High High Joints or Overlay Low Regrade and No Lane/Shoulder Fill Shoulders Shrinkage Severity None Medium Drop-off to Match Cracks Levels High Lane Height Defined Linear Cracking Low Clean & Low None Medium Longitudinal, Seal all Cracks Spalling Transverse and Medium (Comer) Partial -Depth High Full -Depth Patch High Diagonal Cracks Concrete Patch Low None Low None Large Patching and Spalling Medium Medium Partial -Depth Patch Seal Cracks or (Joint) High High Reconstruct Joint Utility Cum Replace Patch Low None Medium Replace Small Patching Patch Empire Laboratories, Inc. High A Division of The Terracon Companies, Inc. TABLE D1 RECOMMENDED PREVENTATIVE MAINTENANCE POLICY FOR ASPHALT CONCRETE PAVEMENTS Distress Type Distress Severity Recommended Maintenance Distress Type Distress Severity Recommended Maintenance Alligator Cracking Low None Patching & Utility Cut Patching Low None Medium Full -Depth Asphalt Concrete Patch Medium Full -Depth Asphalt Concrete Patch High High Bleeding Low None Polished Aggregate Low 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 ag Low None 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 Patch Medium Shallow AC Patch Corrugation Rutting High 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 Medium Seal Cracks Medium Shallow Asphalt Concrete Edge Cracking Slippage Cracking 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 Medium Medium Shoulder Weathering & Ravelling Medium Fog Seal High High Low None Longitudinal & Clean & Transverse Medium Cracking Seal High All Cracks Empire Laboratories, Inc. 1 r\ vIvlawn v� .,... ._.. 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. Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. 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. Coluuvium 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, (18,000 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. Empire Laboratories, Inc. A Division of The Terracon Companies, inc. 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 Used to develop an estimate of both the rate and amount of Foundation Consolidation both differential and total settlement of a structure. Design Used to determine the consolidated drained shear strength of Bearing Capacity, Direct soil or rock. Foundation Design & Shear Slope Stability Dry Used to determine the in -place density of natural, inorganic, Index Property Density fine-grained soils. Soil Behavior Used to measure the expansive potential of fine-grained soil Foundation & Slab Expansion 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. Classifcation 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 Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. UNIF&iJ SOIL CLASSIFICATION SYSTEM Criteria for Assigning Group Symboh and Group Names Using Laboratory Tests` Coarse -Grained Gravels more than Clean Gravels Less Cu > 4 and 1 < Cc <3r Soils more than 50% of coarse than 5% finest 50% retained on fraction retained on Cu < 4 end/or 1 > Cc > 3` No. 200 sieve No. 4 sieve Sands 50% or more of coarse fraction passes No. 4 sieve Fine -Grained Soils Silts and Clays 50% or more Liquid limit less passes the than 50 No. 200 sieve Silts and Clays Liquid limit 50 or more Highly organic soils Prim ABased on the material passing the 3-in. (75-mm) sieve elf field sample contained cobbles or boulders, or both, add "with cobbles or boulders, or both" to group name. "Gravels with 5 to 12% fines require dual symbols: GW-GM well -graded gravel with silt GW-GC well -graded gravel with clay GP -GM poorly graded gravel with silt GP -GC poorly graded gravel with clay °Sands with 5 to 12% fines require dual symbols: SW-SM well -graded sand with silt SW -SC well -graded sand with clay SP-SM poorly graded sand with silt SP-SC poorly graded sand with clay W Gravels with Fines c Fines classify as ML or MH more than 12% fines Fines classify as CL or CH Clean Sands Less Cu > 6 and 1 < Cc < 39 then 5% fines` Cu < 6 end/or 1 > Cc > 3` Sands with Fines Fines classify as ML or MH more than 12% fines inorganic organic inorganic organic "Cu"DrolDio Cc o (Dm)a Dio X Dto 'If soil contains > 15% sand, add "with sand" to group name. olf fines classify as CL-ML, use dual symbol GC -GM, or SC-SM. Hlf fines are organic, add "with organic fines" to group name. 'If soil contains > 15% gravel, add "with gravel" to group name. 'If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay. Fines Classify as CL or CH PI > 7 and plots on or above "A line' PI < 4 or plots below "A" line Liquid limit - oven dried < 0.75 Liquid limit - not dried PI plots on or above "A" line PI lots below "A" line Liquid limit - oven dried < 0.75 Liquid limit - not dried dark in color, and organic odor PT Peat 'if soil contains 15 to 29% plus No. 200, add .with sand" or "with gravel", whichever is predominant. 4f soil contains > 30% plus No. 200 predominantly sand, add "sandy" to group name. "If soil contains > 30% plus No. 200, predominantly gravel, add "gravelly" to group name. "PI > 4 and plots on or above "A" line. oPl < 4 or plots below "A" line. PPI plots on or above "A" line. °PI plots below "A" line. Group GW GP GM GC So# Ciassiflcation Group Name Well -graded gravel Poorly graded grave Silty gravel,G,H i F., clovilkonon of nno-y,oN.O IN OM lln.-yynvin.E fnaef of a".- p-1.0 IN I. rwof of W - Fn. 2l.0 "then�M -"ari (u" 20) OR V.nicd M LL- felon -9. i i MH OR OH ML OR OL a:"'`Cti.°'IK10„t' 10 f E N 00 SW Well -graded sand' SP Poorly graded sand' SM Silty sand"J SC Clayey sand-"4 CL Lean clay' L�" ML SiltK-" OL Organic clay"" Organic silt"A40 CH Fat clays" MH Elastic Silt'L-" Organic clay""' OH Orqanic siltK - 'o LIQUID UNIT (LL) Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. L _LING 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 RB : Rock Bit HA : Hand Auger 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, Ou, 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 RELA TIVE 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. (300mm 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) Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. SUMMARY OF TEST RESULTS PROJECT NO. 20935113 Boring No. Depth Ft. Moisture % Dry Density (PCF) Compressive Strength (PCF) Swell Pressure (PCF) Soluble Sulfates % pH Liquid Limit % Plasticity Index % Group Index Classification AASHTO USCS Resistivity (OHM- CM) Penetration Blow/In. 1 0.5-1.5 9.3 13/12 3.0-4.0 9.0 90.6 1430 25.5 9.3 1.0 A-4(1) SC 4.0-5.0 7.1 18/12 7.0-8.0 6.2 9/12 14.0-15.0 5.1 13/12 2 0.5-1.5 7.2 16/'" 3.0-4.0 4.9 6/12 7.0-8.0 3.6 23.0. 8.2 0 A-24(0) SC 8.0-9.0 4.6 6/12 14.0-15.0 14.5 4/12 3 0.5-1.5 7.7 18/12 3.0-4.0 4.9 4.0-5.0 1.5 29/12 7.0-8.0 2.2 16/12 14.0-15.0 2.0 16/12 LOG OF BORING NO. 3 Page 1 of 1 CLIENT ARCHTTECT/ENG]NEFR Storck Development SITE Drake & Hamshire PROJECT Fort Collins Colorado 18-Acre Residential Development SAMPLES TESTS JU. H DESCRIPTION N w ZLL ce w H� = S U w CO :0o 1 Cn F- O Z Z U � C. Q. W w O CW. Y L.1 W 1� 0 C.J H O Y lL WL) LL ZHfA 0 O O Z F- w 0M = OC. MU)C. "-""" 0.5 6" TOPSOIL. 1 ISS 12" 18 7.7 rT AVFv SAND WITH GRAVEL _ Tan/red, moist, stiff PA SC 2 ST 12" 1 4.9 4.0 3 SS 12" 29 1.5 SILTY SAND WITH GRAVEL 5 PA Tan/red, dry, dense SM 4 SS 12" 16 2.2 PA 10 13.0 .� '4 SAND WITH GRAVEL Red/gray, moist, medium dense SW 5 SS 12" 16 2.0 .4 15.0 15 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 5-13-93 Empire Laboratories W- y None W.D.IT None A.B. BORING COMPLETED 5-13-93 Incorporated Division of Tertacon WI. RIG CME-55 FOREMAN DAR WL Checked 24 hrs. A.B. APPROVED NR,S JJOBN 20935113 LOG OF BORING NO. 2 Page 1 of 1 CLIENT ARCH]TECf/ENGINEFR Storck Development SITE Drake & Hamshire PROJECT Fort Collins Colorado 18-Acre Residential Development SAMPLES TESTS ►r- o J z z H� W a H DESCRIPTION r N it z\ zz WHJ = W = to 1— O _ 1— fN Co W O 3 fA ow W H (L 0. C. L) I-_ IL V 1-0 H >-lL t)0:LL 1_ E\ W W O Y W ICJ O O:L) Zt_Cn 1—H-i a, O 7 z HW tAm E OIL MW(L CJJ C "•""" 0.5 6" TOPSOIL. 1 SS 12' 16 1.7.2 PA CLAYEY S ND Lt. brown/red, moist, medium stiff SC 2 SS 12' 6 1 4.9 PA 5 25/15/8 3 ST 12" 3.6 SC 4 SS 12" 6 4.6 8.5 SM SILTY SAND WITH GRAVEL PA Red, moist, medium dense 10 12.5 SANDY LEAN CLAY WITH GRAVEL Red/tan, moist, medium stiff CL 5 SS 12' 4 14.5 15.0 15 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 5-13-93 Empire Laboratories Incorporated Division of Termcon WL g None W.D.= None A.B. BORING COMPLETED 5-13-93 WL RIc CMIE 55 FOREMAN DAR �vl. Checked 24 hrs. A.B. APPROVED NRS JOB N 20935113 LOG OF BORING NO. 1 Page 1 of 1 ARCHITF=/ENGINEFR CLIENT Storck Development SITE Drake & Hamshire PROJECI Fort Collins Colorado 18-Acre Residential Development SAMPLES TESTS H >- F-- O C9 i. J O O J LL CO z z H� w a H DESCRIPTION } N � zLL H O Zz OR'IN-J = F to to > O I N 3 to O W W H 0- 0. G. U E (L L) 11-0 H t >LL Gd L3wLL MNd FE\ ¢JJ O 7 Z F� fAm CD AwAAA 0.5 6" TOPSOIL 1 SS 12" 13 9.3 PA CLAYEY S ND Red/tan, moist, stiff 25/16/9 SC 2 ST 12" 9.0 91 1430 3 SS 12" 18 7.1 5 PA 7.5 4 SS 12" 9 6.2 SILTY SAND WITH GRAVEL SM PA Red/tan, moist, medium 10 11.0 SANDY LEAN CLAY_ WITH GRAVEL Red, moist, stiff CL 5 SS 12' 13 5.1 15.0 15_T 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 Empire Laboratories Incorporated Division of Terracon BORING STARTED 5-13-93 4 None W.D =None A.B. BowNG comPLETED 5-13-93 r RIG CME-55 FO�AN DAR Checked 24 hrs. A.B. APPROVED NRS JOB d 20935113 0011 1 Lu z I Oi ZOO 4dol l000 �IeimLj re, t : Sl j fF.- ZLAv� I S-AC �51 t�EN7AL De R14T. pfzAKE fte;�46.0 � 4-MFl;Hl f:k .2 Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. Storck Development ELi Project No. 20935113 • Comniiance: Recommendations for 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. • Utility Construction: Excavations into the on -site soils may encounter caving soils and groundwater, depending upon the final depth of excavation. 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. Where necessary, excavations should be sloped or shored in the interest of safety following local, and federal regulations, including current OSHA excavation and trench safety standards. Extensive drying or replacement with dry soil may be required for proper utility backfill. GENERAL COMMENTS This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranty, express or implied, is made. This report has been prepared to aid in the evaluation of the property and to assist the architect and/or engineer in the design of this project. It should be noted that this was a preliminary investigation and the bearing capacities recommended in this report are based on preliminary tests. Due to variations in soil conditions encountered at the site, it is recommended that additional test borings be made prior to construction. Samples obtained from the borings should be tested in the laboratory to provide a basis for evaluating subsurface conditions. Q Storck Development ELi Project No. 20935113 Material On -site soils: Minimum Percent Compaction (ASTMD698) Beneath foundations ................................... au 95 Beneathslabs ....................................... 95 Beneath pavements .................................... Imported fill: Beneath foundations ................................... yo Beneathslabs ....................................... 95 95 Beneath pavements ................................... Miscellaneous backfill....................................... 90 5. On -site clay soils should be compacted within a moisture content range of optimum moisture to 2 percent above optimum. Subgrade and fill below streets and imported granular soils should be compacted within a moisture range of 2 percent below to 2 percent above optimum. • Slopes: 1. For permanent slopes in compacted fill areas, recommended maximum configurations for on -site materials are as follows: , Maximum Slope Material Horizontal: Vertical Cohesive soils (clays) ...................................... 2:1 Cohesionless soils ........................................ 2:1 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. Storck Development EL/ Project No. 20935113 • Pavement Subarade Preparation: The subgrade should be scarified, moistened as required, and recompacted for a minimum depth of 8 inches prior to placement of fill and pavement materials. 1. On -site clay soils 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. Use of lime, fly ash, kiln dust, cement or geotextiles could also be considered as a stabilization technique. Adequate laboratory tests should be performed prior to use of chemical stabilization to evaluate the strength characteristics and the effect these materials have on the physical properties of the soil. Lightweight excavation equipment may be required to reduce subgrade pumping. • Fill Materials: 1. Clean on -site soils or imported materials may be used as fill material for the following: 0 general site grading 0 exterior slab areas • foundation areas • pavement areas • interior floor slab areas • foundation backfill • 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. Uncompacted fill lifts should not exceed 10 inches loose thickness. 3. No fill should be placed over frozen ground. 4. Materials should be compacted to the following: 7 Storck Development ELl Project No. 20935113 Although fills or underground facilities such as septic tanks, cesspools, basements, utilities were not observed during site reconnaissance, such features might be encountered during construction in the area of the existing farmhouse and outbuildings. • Site Clearing: 1. 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, the excavation thoroughly cleaned and backfilled. All excavations should be observed by the geotechnical engineer prior to backfill placement. 3. Sloping areas steeper than 2:1 (horizontal: vertical) should be benched to reduce the potential for slippage between existing slopes and fills. Benches should be level and wide enough to accommodate compaction and earth moving equipment. • Exca va tion: 1. It is anticipated that excavations for the proposed construction can be accomplished with conventional earthmoving equipment. 2. Depending upon depth of excavation and seasonal conditions, groundwater may be encountered in utility excavations on the site. Pumping from sumps or construction of area subdrains may be utilized to control water within excavations. • Slab Subgrade Preparation: 1. Where existing clay soils will support floor slab, the soils should be scarified, moisture conditioned and compacted to a minimum depth of 8 inches. 2. A minimum 4-inch layer of clean, graded gravel or crushed rock should be placed beneath floor slabs. Basement slabs surrounded by perimeter drains should be underlain by a minimum of 8 inches of clean, graded gravel or crushed rock devoid of fines. 5 Storck Development EL/ Project No. 20935113 assumptions concerning fill placement when the final site plan is developed, the conclusions and recommendations contained in this geotechnical engineering report should be reviewed and confirmed or modified as necessary to reflect the final planned site configuration. Because of variations in the engineering properties of the on -site soils, foundation bearing levels, structural loads and possible final site grades, the following foundation systems were evaluated for use on the site. • Conventional -type spread footings and/or continuous grade beams bearing on undisturbed soils, and • Conventional -type spread footings and/or continuous grade beams bearing on engineered fill. Foundation Systems: Due to the presence of low to slight swelling potential soils on the site, conventional -type spread footings and/or continuous grade beam foundation systems bearing upon undisturbed soils and/or engineered fill material is recommended for support of the proposed structures. Based on preliminary test results, the footings may be designed for a maximum allowable bearing pressure between 1,000 and 2,000 pounds per square foot (psf). In addition, the footings should be sized to maintain a minimum deadload pressure of between 250 and 500 psf. Footings should bear a minimum of 30 inches below finished grade for frost protection. Basement Construction: Groundwater was not encountered on the site to the maximum depth of exploration, that is to say 15 feet below grade. Therefore, full -depth basement construction is considered acceptable on the site. Floor Slab Deshm and Construction: Non -expansive, or low expansive soils will support the floor slab. Some differential movement of a slab -on -grade floor system is possible should the subgrade soils become elevated in moisture content. Such movements are considered within general tolerance for normal slab -on -grade movements. To reduce any potential slab movements, the subgrade soils should be prepared as outlined in the earthwork section of this report. Earthwork: 0 General Considerations: The conclusions contained in this report for the proposed construction are contingent upon compliance with recommendations presented in this section. 5 Storck Development ELI Project No. 20935113 Soil and Bedrock Conditions: 1. 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 and should not be used as a bearing or as a fill and/or backfill material. 2. Clayey Sand. This light brown to red, moist, medium dense clayey sand with trace of gravel underlies the topsoil and extends to the silty sand and gravel stratum encountered at depths of four (4) to eight and one-half (8'/:) feet the surface. The clayey sand generally exhibits low plasticity and low to moderate bearing characteristics in its moist, in -situ condition. When wetted, the clayey sand exhibits slight swell potential. 3. Silty Sand with Gravel. The stratum was encountered below the clayey sand material and extends beyond the depths explored in test borings 2 and 3 and extends to 11 feet below the surface in test boring No. 1. The granular stratum varies from a silty sand with gravel to a relatively clean sand with gravel, is medium dense to dense and exhibits generally moderate bearing characteristics in its moist in -situ condition. 4. Sandy Lean Clay with Gravel. This cohesive, red, moist, stiff, sandy lean clay with gravel was encountered below the granular stratum in test boring No. 1 at a depth of 11 feet below the surface and extends beyond the depths explored. The sandy lean clay is plastic, moist and exhibits moderate bearing characteristics in its moist in -situ condition. Groundwater Conditions: Groundwater was not encountered in any test boring at the time of preliminary field exploration and 24 hours after drilling. 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/or weather conditions. CONCLUSIONS AND RECOMMENDATIONS Site Development Considerations: The site appears suitable for the proposed residential construction. There are no known geologic hazards which would preclude development as currently planned. The recommendations contained in this report assume that certain cut and fill areas will be required to achieve final grading and the fill will be placed accordingly to the specifications provided in the "Earthwork" section of this report. If there are any significant deviations from the n Storck Development ELI Project No. 20935113 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 preliminary foundation and earthwork recommendations. All laboratory tests were performed in general accordance with applicable ASTM, local and/or other accepted standards. SITE CONDITIONS The site consists of an 18-acre horse pasture. The site is vegetated with medium dense growth of grass, weeds and sparse sagebrush. The property is relatively flat and exhibits positive surface drainage in the. south to southwest directions. West of the subject property is an existing residence with horse corrals and north of the site is Drake Road with the Safeway supermarket complex to the northeast and Hampshire Square, a subdivision currently under construction to the northwest. East of the property is a vacant tract.of land with residential property horse corrals and Taft Hill Road beyond. Southeast of the site is a small lake/pond and directly south of the property is a marshy/wetlands area. SUBSURFACE CONDITIONS Geo/o4v: The proposed area is located within the Colorado Piedmont section of the Great Plains physiographic province. The Colorado Piedmont, formed during Late Tertiary and Early quaternary time (approximately two million (2,000,000) years ago), is a broad, erosional trench which separates the Southern Rocky Mountains from the High Plains. Structurally, the site lies along the western flank of the Denver Basin. During the Late Mesozoic and Early Cenozoic Periods (approximately seventy million (70,000,000) years ago), intense tectonic activity occurred, causing the uplifting of the Front Range and the associated downwarping of the Denver Basin to the east. Relatively flat uplands and broad valleys characterize the present-day topography of the Colorado Piedmont in this region. The site is underlain by the Cretaceous Pierre shale. Bedrock was not encountered in the test borings and it is anticipated bedrock underlies the subject site at depths of 20 to 30 feet below existing grade. The bedrock is overlain by colluvial and residual clays of the Pleistocene and/or recent age. The regional dip of the bedrock in this area is slight and in an easterly direction. Seismic activity in the area is anticipated to be low; therefore, from a structural standpoint, the property should be relatively stable. The site lies within the drainage basin of Spring Creek. It is anticipated that drainage flows in a southeast direction toward the lake and wetlands area located south of the subject property. K Storck Development ELI Project No. 20935113 SITEEXPLORATION The scope of the services performed for this project included site reconnaissance by a geotechnical engineer, a subsurface exploration program, laboratory testing and engineering analyses. Field Exploration: A total of three (3) test borings were drilled at the subject site to depths of fifteen (15) feet below the surface at the locations shown on the Site Plan included in Appendix A as Figure 1. The borings were located in the field by the geotechnical engineer with reference to the east and north boundaries of the subject site. The borings were advanced with a truck - mounted, drilling rig, utilizing 4-inch diameter continuous -type, power -flight auger drill. Continuous lithologic logs of each boring were recorded by the geotechnical engineer during the drilling operations. At selected intervals, samples of the subsurface materials were taken by means of pushing a thin -walled Shelby tube (ST) and by driving a split -spoon sampler (SS). Penetration resistance measurements were taken with each sampling using the SS by driving the sampler with a 140-pound hammer falling 30 inches. When properly interpreted, the penetration resistance is a useful index to the consistency, relative density or hardness of the materials encountered. Groundwater conditions were evaluated in each test boring at the time of site exploration, and 24- hours after the initial drilling. Laboratory Testin4: All samples retrieved during the field exploration were returned to the laboratory for evaluation 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, final boring logs prepared, and an applicable laboratory testing program was formulated to determine engineering properties of the subsurface materials. Boring Logs prepared from the field logs for the project are presented in Appendix A. Selected soil samples were tested for the following engineering properties: • Water content • Expansion Potential • Dry density • Plasticity • Unconfined Compressive Strength 2 GEOTECHN/CAL ENGINEERING REPORT PROPOSED 18-ACRE RESIDENTIAL DEVELOPMENT DRAKE ROAD AND HAMPSHIRE ROAD FORT COLLINS, COLORADO ELI PROJECT NO. 20935113 INTRODUCTION This report contains the results of our preliminary geotechnical engineering exploration for the proposed 18-acre residential development to be located south of Drake Road and west of Taft Hill in southwest Fort Collins, Colorado. The site is located in the north half of Section 28, Township 7 North, Range 69 West of the 6th Principal Meridian, Larimer County, Colorado. The purpose of these services is to provide information and geotechnical engineering recommendations relative to: • subsurface soil conditions • groundwater conditions • preliminary foundation design and construction • preliminary floor slab design and construction • earthwork • drainage The conclusions and recommendations contained in this report are based upon the results of preliminary field and laboratory testing, engineering analyses, and experience with similar soil and structural conditions. PROPOSED CONSTRUCTION Based on preliminary information provided by Stock Development, it is our understanding the site will be developed for single-family, lightly -loaded one and two-story, slab -on -grade, crawl space and/or basement structures. Other major site development will include overlot grading and construction of residential collector and/or arterial streets throughout the project area. TABLE OF CONTENTS (cont.) APPENDIX A Page No. Figure No. SitePlan ...................................................... 1 Logs of Borings .......................................... Al thru A3 APPENDIX B Laboratory Test Data: Summary of Test Restults.................................... 131 APPENDIX C: GENERAL NOTES Drilling & Exploration ............................................ C1 Unified Soil Classification ......................................... C2 Laboratory Testing, Significance and Purpose ........................... C3 ReportTerminology ............................................. C4 APPENDIX D Recommended Preventative Maintenance -Asphalt Concrete Pavements ......... D1 Recommended Preventative Maintenance -Jointed Concrete Pavements ......... D2 TABLE OF CONTENTS Page No. Letterof Transmittal .................................................. i 1 INTRODUCTION..................................................... PROPOSED CONSTRUCTION ........................................... 1 2 SITE EXPLORATION .................................................. FieldExploration ............................................... 2 LaboratoryTesting ............................................... 2 3 SITE CONDITIONS ...:............................................... SUBSURFACE CONDITIONS ............................................ 3 Geology..................................................... 3 Soil and Bedrock Conditions ....................................... 4 Groundwater Conditions .......................................... 4 CONCLUSIONS AND RECOMMENDATIONS ................................. 5 5 Site Development Considerations .................................... Foundation Systems ............................................. 5 Basement Construction ........................................... 5 Floor Slab Design and Construction .................................. 5 Earthwork.................................................... 5 General Considerations ...................................... 5 Site Clearing 6 ............................................. Excavation.............................................. 6 Slab Subgrade Preparation .................................... 6 Pavement Subgrade Preparation ................................ 7 Fill Materials ............................................. 7 Placement and Compaction ................................... 7 8 Slopes................................................. 9 Compliance .............................................. Utility Construction ........................................ 9 GENERAL COMMENTS ................................................ 9 Storck Development ELi Project No. 20935713 We have appreciated being of service to you in the preliminary geotechnical engineering phase of this project, and are prepared to assist you in the final design and construction phases as well. If you have any questions concerning this report or any of our testing, inspection, design and consulting services, please do not hesitate to contact us. Sincerely, EMPIRE LABORATORIES, INC. A Division of The Terracon Companies, inc. David A. Richer, P.E: Geotechnical Engineer Reviewed by: Chester C. Smith, P.E. Division Manager DAR/CCS/dmf Copies to: Storck Development (3) Empire'. ,boratories, Inc. A Division of The Terracon Companies, Inc. P.O. Box 503 • 301 No. Howes Fort Collins, Colorado 80522 (303)484-0359 FAX No. (303) 484-0454 Chester C. Smith. P.E. Neil R. Sherrod, C.P.G. May 27, 1993 Storck Development P.O. Box 270218 Fort Collins, CO 80527 Re: Preliminary Geotechnical Engineering Report, Proposed 18-Acre Residential Development, Drake Road and Hampshire Road, Fort Collins, Colorado ELl Project No. 20935113 Empire Laboratories, Inc. (ELI) has completed a preliminary geotechnical engineering exploration for the proposed 18-acre residential development to be south of Drake Road in southwest Fort Collins, Colorado. This investigation was performed in general accordance with our proposal dated May 4, 1993. The results of our engineering study, including the boring location diagram, laboratory test results, test boring records, and the preliminary geotechnical recommendations needed to provide preliminary design of foundations and other earth connected phases of this project are included in this report. The subsurface exploration indicated soil conditions which are typical of soils commonly found in this portion of southwest Fort Collins. The subsurface soils at the site consisted predominately of a sandy lean clay with gravel underlain by a silty sand with gravel material. The information obtained and the results of the field exploration and laboratory testing completed for this study indicated the soils at the site have low expansive potential. Based on the preliminary geotechnical engineering analyses, subsurface exploration and laboratory test results, Empire recommends the proposed structures be supported on a conventional -type, spread footing and/or continuous grade beam foundation systems. Slabs -on -grade may be utilized for the interior floor systems provided care is taken in the placement and compaction of the subgrade soil. Other design and construction details, based upon geotechnical conditions, are presented in the report. Offices of The Terracon Companies, Inc. Geotechnical, Environmental and Materials Engineers Arizona: Tucson ■ Colorado: Colorado Springs. Denver, Ft. Collins, Greeley, Longmont 0 Idaho: Boise 0 Illinois: Bloomington. Chicago, Rock Island ■ Iowa: Cedar Falls, Cedar Rapids. Davenport, Des Moines. Storm Lake ■ Kansas: Lenexa. Topeka. Wichita ■ Minnesota: St. Paul ■ Missouri: Kansas City 0 Nebraska: Lincoln, Omaha ■ Nevada: Las Vegas ■ Oklahoma: Oklahoma City. Tulsa ■ Texas: Dallas ■ Utah: Salt Lake City ■ Wyoming: Cheyenne QUALITY ENGINEERING SINCE 1965 PRELIMINARY GEO TECHNICAL ENGINEERING REPORT PROPOSED RESIDENTIAL DEVELOPMENT 18-ACRE TRACT DRAKE ROAD AND HAMPSHIRE ROAD FORT COLLINS, COLORADO ELI PROJECT NO. 20935113 Prepared for: STORCK DEVELOPMENT P.O. BOX 270212 FORT COLLINS, COLORADO 80527 ATTN. MR. RICHARD STORCK Empire Laboratories, Inc. A Division of The Terracon Companies, Inc.