Loading...
HomeMy WebLinkAboutSubsoil Study 04.30.2012~tech HEPWORTH-PAWLAK GEOTECHNICAL SUBSOIL STUDY I lq •11·(,l'l li-J' I',\ I 11 ( '"' d ,-,_I I! I le ,1 I. I 1.l )(\2('1(",q111l\ !~"hi 11-j l ~l..'.11\'.t"H ,J ..-::,1 1111'-'· ( ,,l,·1.1.J. S.] '"'I i'h·•IW: '.1(L1-'Lj_l ;-h- J-,1\: 1)"/\~.ll-J.l-.')-}5-l ~·m;iil: L~'c.'1:,,rJhr!..'c:1 r,-,1-,_,_,,:11 FOR FOUNDATION DESIGN PROPOSED BRIDGE, BARN AND SHOP 4110 COUNTY ROAD 243, MAIN ELK CREEK NORTHWEST OF NEW CASTLE GARFIELD COUNTY, COLORADO JOB NO. 112 OSSA APRIL 30, 2012 PREPARED FOR: SMITHBUILT ATTN: BRIDGER SMITH P.O. BOX 8616 ASPEN, COLORADO 81612 smith.bridger@gmail.com TABLE OF CONTENTS PURPOSE AND SCOPE OF STUDY ........................................................................ -I - PROPOSED CONSTRUCTION ................................................................................. - l - SITE CONDITIONS ................................................................................................... - 2 - FIELD EXPLORATION ............................................................................................ - 3 - SUBSURFACE CONDITIONS .................................................................................. -3 - FOUNDATION BEARING CONDITIONS ............................................................... - 4 - DESIGN RECOMMENDATIONS ............................................................................. - 4 - BRIDGE FOUNDATIONS ..................................................................................... - 4 - ABUTMENT AND WING WALLS ....................................................................... - 5 - BARN AND SHOP FOUNDATIONS .................................................................... - 6 - FOUNDATION AND RETAINING WALLS ......................................................... - 7 - FLOOR SLABS ...................................................................................................... - 9 - UNDERDRAIN SYSTEM ................................................... ; .................................. - 9 - SITE GRADING .................................................................................................. • 10 • SURFACE DRAINAGE ....................................................................................... -10- PERCOLATION TESTING ..................................................................................... • l l - LIMITATIONS ........................................................................................................ -12- FIGURE J -LOCATIONS OF EXPLORATORY BORINGS AND PERCOLATION TEST HOLES FIGURE 2-LOGS OF EXPLORATORY BORINGS FIGURE 3 -LEGEND AND NOTES FIGURE 4-SWELL-CONSOLIDATION TEST RESULTS FIGURE 5 -GRADATION TEST RESULTS FIGURES 6 & 7-USDA GRADATION TEST RESULTS TABLE I-SUMMARY OF LABORATORY TEST RESULTS TABLE 2 -PERCOLATION TEST RESULTS I PURPOSE AND SCOPE OF STUDY This report presents the results of a subsoil study for a proposed bridge, barn and shop to be located at 4110 County Road 243, Main Elk Creek, nmihwest of New Castle, Garfield County, Colorado. The project site is shown on Figure I. The purpose of the study was to develop recommendations for the foundation design. The study was conducted in accordance with our proposal for geoteclmical engineering services to Smithbuilt dated April 16 and revised April 17, 2012. A preliminary geotechnical investigation was performed by Yeh and Associates, Inc. dated November 15, 2007, their Project No. 27- 314. The overall site geology and geologic hazards were addressed in the Yeh report that should be referenced fur additional information. A field exploration program consisting of exploratory borings was conducted to obtain information on the subsurface conditions. Samples oftbe subsoils obtained during the field exploration were tested in the laboratory to detenuine their classification, compressibility and other engineering characteristics. The results of the field exploration and laborato1y testing were analyzed to develop recommendations for foundation types, depths and allowable pressures for the proposed building foundation. This repo1t summarizes the data obtained during this study and presents our conclusions, design recommendations and other geotechnical engineering considerations based on the proposed construction and the subsurface conditions encountered. PROPOSED CONSTRUCTION The proposed bridge will be a single lane and about 50 foot span. The barn will be a two sto1y structure with a lower level walkout to the north. The shop will be a one story wood frame structure. Ground floor of the shop will be slab-on-grade. Grading for the structures is assumed to be relatively minor with cut depths between about 3 to I 0 feet. We assume relatively light foundation loadings for the buildings and moderate loadings for the bridge, typical of the proposed type of construction. Job No. 112 088A ~ech - 2 - If building loadings, locations or grading plans change significantly from those described above, we should be notified to re-evaluate the recommendations contained in this report. SITE CONDITIONS The existing ranch site is cmTently occupied by a single story house, shop, barn and sheds. The site slopes moderately down to the east from the County Road to Main Elk Creek at grades of 5 to 15% with locally steeper slopes north of the barn and shop and along the creek bed. Vegetation in the development areas consists of grass and weeds with scattered bmsh and trees. The area between the County Road and the creek is historically ilTigated pasture. SUBSIDENCE POTENTIAL Bedrock of the Pennsylvanian age Eagle Valley Evaporite underlies the site. These rocks are a sequence of gypsiferous shale, fine-grained sandstone and siltstone with some massive beds of gypsum and limestone. There is a possibility that massive gypsum deposits associated with the Eagle Valley Evaporite underlie portions of the lot. Dissolution of the gypsum under cettain conditions can cause sinkholes to develop and can produce areas of localized subsidence. Sinkholes were not observed in the immediate area of the subject site. No evidence of cavities was encountered in the subsurface materials; however, the explorato1y borings were relatively shnllow, for foundation design only. Based on our present knowledge of the subsurface conditions at the site, it cannot be said for certain that sinkholes will not develop. The risk of future ground subsidence throughout the service life of the proposed structures, in our opinion, is low; however, the owner should be made aware of the potential for sinkhole development. If further investigation of possible cavities in the bedrock below the site is desired, we should be contacted. Job No. I I 2 088A - 3 - FIELD EXPLORATION The field exploration for the project was conducted on April I 8, 20 I 2. Four exploratory borings were drilled at the locations shown on Figure I to evaluate the subsurface conditions. The borings were advanced with 4 inch diameter continuous flight augers powered by a truck-mounted CME-45B drill rig. The borings were logged by a representative ofHepwo11h-Pawlak Geoteclmical, Inc. Samples of the subsoils were taken with 1% inch and 2 inch LD. spoon samplers. The samplers were driven into the subsoils at various depths with blows from a 140 pound hammer falling 30 inches. This test is similar to the standard penetration test described by ASTM Method D-1586. The penetration resistance values are an indication of the relative density or consistency of the subsoils. Depths at which the samples were taken and the penetration resistance values are shown on the Logs of Exploratory Borings, Figure 2. The samples were returned to our laboratory for review by the project engineer and testing. SUBSURFACE CONDITIONS Graphic logs of the subsurface conditions encountered at the site are shown on Figure 2. The subsoils consist of about I Y, to 5Y, feet of fill overlying up to SY, feet of loose, slightly clayey silty gravelly sand (alluvial fan deposit). Relatively dense silty sandy gravel with cobbles (creek a!luvium) was encountered in Borings I and 2 at depths of about 4 feet and at Boring 3 at 13 feet. Dense sandy gravel was not encountered in Boring 4 and the loose to medium dense sand soils were encountered to the maximum depth explored, 40 feet. The gravelly sand soils are generally interlayered with sandy silt, sandy clay, and sandy gravel soils, consistent with alluvial fan deposits. Drilling in the dense gravel alluvium with auger equipment was difficult due to the cobbles. Laboratory testing performed on samples obtained from the borings included natural moisture content, density and gradation analyses. Results of swell-consolidation testing Job No. 112 088A GJil!)tech -4- performed on relatively undisturbed drive samples of the sandy silt and clay soils, presented on Figure 4, indicate moderate compressibility under conditions of loading and wetting. One of the samples showed a low collapse potential (settlement under constant load) when wetted. Results of gradation analyses performed on small diameter drive samples (minus I Y, inch fraction) of the coarser granular soils are shown on Figure 5. The laboratory testing is summarized in Table I. Free water was encountered in the borings at about the level of the creek at the time of drilling. The subsoils above the water level were slightly moist to moist. FOUNDATION BEARING CONDITIONS Foundations for the bridge will be based on the relatively dense gravel alluvium encountered at about 4 to 4Y, foet deep. Foundations for the barn and shop can be placed on the medium dense, silty to clayey gravelly sand (alluvial fan deposit). There is some risk oflong-te1111 settlement of shallow foundations placed on the alluvial fan soils. DESIGN RECOMMENDATIONS BRIDGE FOUNDATIONS Considering the subsurface conditions encountered in Exploratory Borings I and 2 and the nature of the proposed construction, we recommend the bridge be founded with spread footings bearing on the natural dense granular soils. We assume that potential scour of the bearing soils will be addressed by armoring the creek banks in the area of the bridge. If desired, recommendations for a deep foundation alternative such as driven piles can be provided. The design and construction criteria presented below should be observed for a spread footing foundation system. Job No. 112 088A ~tech - 5 - l) Footings placed on the undisturbed natural granular soils should be designed for an allowable bearing pressure of3,000 psf. Based on experience, we expect settlement of footings designed and constructed as discussed in this section will be about 1 inch or less. 2) Footings should be provided with adequate soil cover above their bearing elevation for frost protection. Placement of foundations at least 36 inches below grade is typically used in this area. 4) Abutment and wing walls should be reinforced top and bottom to span local anomalies such as by assuming an unsupported length of at least 10 feet. Abutment and wing walls acting as retaining structures should also be designed to resist lateral earth pressures as discussed in the "Abutment and Wing Walls" section of this repot1. 5) All existing fill, topsoil and any loose or disturbed soils should be removed and the footing bearing level extended down to the relatively dense natural granular soils. If water seepage is encountered, the footing areas should be dewatered before concrete placement. 6) A representative of the geotechnical engineer should observe all footing excavations prior to concrete placement to evaluate bearing conditions. ABUTMENT AND WING WALLS Abutment walls which are laterally supported and can be expected to undergo only a slight amount of deflection should be designed for a lateral eaiih pressure computed on the basis of an equivalent fluid unit weight of at least 45 pcffor backfill consisting of the on-site granular soils. Cantilevered retaining structures, such as wing walls, which can be expected to deflect sufficiently to mobilize the full active earth pressure condition should be designed for a lateral earth pressure computed on the basis of an equivalent fluid unit weight of at least 40 pcffor backfill consisting of the on-site granular soils. All abutment and wing wall retaining structures should be designed for appropriate hydrostatic and surcharge pressures such as adjacent footings, traffic, construction materials and equipment. The pressures recommended above assume drained conditions Job No. 112 088A - 6 - behind the walls and a horizontal backfill surface. The buildup of water behind a wall or an upward sloping backfill surface will increase the lateral pressure imposed on a retaining structure. An underdrain or gravel-packed weep holes should be provided to prevent hydrostatic pressure buildup behind walls. Backfill should be placed in uniform lifts and compacted to at least 95% of the maximum standard Proctor density at a moisture content near optimum. Care should be taken not to overcompact the backfill or use large equipment near the wall, since this could cause excessive lateral pressure on the wall. Some settlement of deep abutment or wing wall backfill should be expected, even if the material is placed correctly, and could result in distress to facilities constrncted on the backfill. The lateral resistance of abutment or wing wall footings will be a combination of the sliding resistance of the footing on the foundation materials and passive earth pressure agaii1st the side of the footing. Resistance to sliding at the bottoms of the footings can be calculated based on a coefficient of friction of0.50. Passive pressure of compacted backfill against the sides of the footings can be calculated using an equivalent buoyant fluid unit weight of275 pct: The coefficient of friction and passive pressure values recommended above assume ultimate soil strength. Suitable factors of safety should be included in the design to limit the strain which will occur at the ultimate strength, particularly in the case of passive resistance. Fill placed against the sides of the footings to resist lateral loads should be compacted to at least 95% of the maximum standard Proctor density at a moisture content near optimum. BARN AND SHOP FOUNDATIONS Considering the subsurface conditions encountered in Exploratory Borings 3 and 4 and the nature of the proposed construction, we recommend the barn and shop buildings be founded with spread footings bearing on the natural sandy soils. Care should be taken to prevent wetting of the foundation soils as described in the "Surface Drainage" Section of this report. Job No. 112 0881\ ~ech - 7 - The design and construction criteria presented below should be observed for a spread footing foundation system. 1) Footings placed on the undisturbed natural sandy soils should be designed for an allowable bearing pressure of 1,500 psf. Based on experience, we expect initial settlement of footings designed and constructed as discussed in this section will be about 1 inch or less. Additional settlement on the order of I to 2 inches could occur in the event of wetting of the sandy soils below the foundation. 2) The footings should have a minimum width of20 inches for continuous walls and 2 feet for isolated pads. 3) Exterior footings and footings beneath unheated areas should be provided with adequate soil cover above their bearing elevation for frost protection. Placement of foundations at least 36 inches below exterior grade is typically used in this area. 4) Continuous foundation walls should be reinforced top and bottom to span local anomalies such as by assuming an unsupported length of at least I 0 feet. Foundation walls acting as retaining structures should also be designed to resist lateral emth pressures as discussed in the "Foundation and Retaining Walls" section of this report. 5) All existing fill, topsoil and any loose or disturbed soils should be removed m1d the footing bearing level extended down to the natural sandy soils. The exposed soils in footing area should then be moistened and compacted. 6) A representative of the geotechnical engineer should observe all footing excavations prior to concrete placement to evaluate bearing conditions. FOUNDATION AND RETAINING WALLS Foundation walls and retaining stmctures which are laterally suppotted and can be expected to undergo only a slight amount of deflection should be designed for a lateral Job No. 112 088A ~tech - 8 - eat1h pressure computed on the basis of an equivalent fluid unit weight of at least 50 pcf for backfill consisting of the on-site sandy soils. Cantilevered retaining structures which are separate from the buildings and can be expected to deflect sufficiently to mobilize the full active earth pressure condition should be designed for a lateral earth pressure computed on the basis of an equivalent fluid unit weight of at least 40 pcf for backfill consisting of the on-site sandy soils. All foundation and retaining stmctures should be designed for appropriate hydrostatic and surcharge pressures such as adjacent footings, traffic, construction materials and equipment. The pressures recommended above assume drained conditions behind the walls and a horizontal backfill surface. The buildup of water behind a wall or an upward sloping backfill surface will increase the lateral pressure imposed on a foundation wall or retaining strncture. An underdrain should be provided to prevent hydrostatic pressure buildup behind walls. Backfill should be placed in unifonn liits and compacted to at least 90% of the maximum standard Proctor density at a moisture content near. Backfill in pavement and walkway areas should be compacted to at least 95% of the maximum standard Proctor density. Care should be taken not to overcompact the backfill or use large equipment near the wall, since this could cause excessive lateral pressure on the wall. Some settlement of deep foundation wall backfill should be expected, even if the material is placed correctly, and could result in distress to facilities constructed on the backfill. The lateral resistance of foundation or retaining wall footings will be a combination of the sliding resistance of the footing on the foundation materials and passive earth pressure against the side of the footing. Resistance to sliding at the bottoms of the footings can be calculated based on a coefficient of friction of0.40. Passive pressure of compacted backfill against the sides oftl1e footings can be calculated using an equivalent fluid unit weight of300 pct: The coefficient of friction and passive pressure values recommended above assume ultimate soil strength. Suitable factors of safety should be included in the design to limit the strain which will occur at the ultimate strength, pai1icularly in the case Job No. 112 088A ~ech • 9 - of passive resistance. Fill placed against the sides of the footings to resist lateral loads should compacted to at least 95% of the maximum standard Proctor density at a moisture content near optimum. FLOOR SLABS The natural on-site soils, exclusive of topsoil, are suitable to support lightly loaded slab- on-grade constrnction. To reduce the effects of some differential movement, floor slabs should be separated from all bearing walls and columns with expansion joints which allow unrestrained vertical movement. Floor slab control joints should be used to reduce damage due to shrinkage cracking. The requirements for joint spacing and slab reinforcement should be established by the designer based on experience and the intended slab use. A minimum 4 inch layer of free-draining gravel should be placed beneath basement level slabs to facilitate drainage. This material should consist of minus 2 inch aggregate with at least 50% retained on the No. 4 sieve and less than 2% passing the No. 200 sieve. All fill materials for supp01t of floor slabs should be compacted to at least 95% of maximum standard Proctor density at a moisture content near optimum. Required fill can consist of the on-site sandy soils devoid of vegetation, topsoil and oversized rock. UNDERDRAIN SYSTEM Although free water was not encountered during our exploration, it has been our experience in mountainous areas that local perched groundwater can develop during times of heavy precipitation or seasonal runoff. Frozen ground during spring runoff can create a perched condition. We recommend below-grade construction, such as retaining walls, basement level and below grade areas, be protected from wetting and hydrostatic pressure buildup by an underdrain system. The drains should consist of drainpipe placed in the bottom of the wall backfill su1rnunded above the invert level with free-draining granular material. The drain should Job No. 112 088A -JO - be placed at each level ofexcavation and at least 1 foot below lowest adjacent finish grade and sloped at a minimum I% to a suitable gravity outlet. Free-draining granular material used in the underdrain system should contain less than 2% passing the No. 200 sieve, less than 50% passing the No. 4 sieve and have a maximum size of2 inches. The drain gravel backfill should be at least I Y, feet deep. An impervious membrane such as 20 mil PVC should be placed beneath the drain gravel in a trough shape and attached to the foundation wall with mastic to prevent wetting of the bearing soils. SITE GRADING The risk of construction-induced slope instability at the site appears low provided the buildings are located away from the steep slopes as planned and cut and fill depths are limited. We assume the cut depths for the barn lower level will not exceed one level, about 10 to 12 feet. Fills should be limited to about 8 to l 0 feet deep, especially at the downhill side of the barn where the slope steepens. Embankment fills should be compacted to at least 95% of the maximum standard Proctor density near optimum moisture content. Prior to fill placement, the subgrade should be carefully prepared by removing all vegetation and topsoil and compacting to at least 95% of the maximum standard Proctor density. The fill should be benched into the portions of the hillside exceeding 20% grade. Permanent unretained cut and fill slopes should be graded at 2 horizontal to 1 vertical or flatter and protected against erosion by revegetation or other means. The risk of slope instability will be increased if seepage is encountered in cuts and flatter slopes may be necessary. If seepage is encountered in permanent cuts, an investigation should be conducted to determine if the seepage will adversely affect the cut stability. This office should review site grading plans for the project prior to construction. SURFACE DRAINAGE The 2007 Yeh and Associates report identified the assessment of Main Elk Creek as being potentially impacted by debris flows. We have not evaluated the risk but based on our Job No. 112 fl88A ~tech • 11 • cursory review, the risk appears to be low at the bottom of the alluvial fon area where the current development is proposed. If this risk of potential impact is not acceptable we can provide site specific evaluation for mitigation design as needed. The following drainage precautions should be observed during construction and maintained at all times after the barn and shop have been completed: I) Inundation of the foundation excavations and underslab areas should be avoided during construction. 2) Exterior backfill should be adjusted to near optimum moisture and compacted to at least 95% of the maximum standard Proctor density in pavement and slab areas and to at least 90% of the maximum standard Proctor density in landscape areas. 3) The ground surface surrounding the exterior of the building should be sloped to drain away from the foundation in all directions. We recommend a minimum slope of 12 inches in the first I 0 feet in unpaved areas and a minimum slope of 3 inches in the first 10 feet in paved areas. Free-draining wall backfill (if any) should be capped with about 2 feet of the on-site soils to reduce surface water infiltration. 4) Roof downspouts and drains should discharge well beyond the limits of all backfill. 5) Landscaping which requires regular heavy irrigation should he located at least I 0 feet from foundation walls. Consideration should be given to use ofxeriscape to reduce the potential for wetting of soils below the building caused by irrigation. PERCOLATION TESTING Percolation tests were conducted on April 25, 2012 to evaluate the feasibility of an infiltration septic disposal system at the site. One profile boring and three percolation pits were dug at the locations shown on Figure I. The test ho Jes (nominal 12 inch diameter by 12 inch deep) were hand dug at the bottom of shallow backhoe pits and were soaked with Job No. 112 ll88A ~ech -12 - water one day prior to testing. The soils exposed in the percolation holes are similar to those exposed in the Profile Boring shown on Figure 2 and consist of loam to extremely gravelly sand. Gradation test results performed on samples of the subsoils obtained from the Profile Boring and Percolation Hole P-3 are shown on Figures 6 and 7. The percolation test results are presented in Table 2. The percolation test results were variable and the overall average percolation rate was about 30 minutes per inch. Based on the subsurface conditions encountered and the percolation test results, the tested area should be suitable for a conventional infiltration septic disposal system. LIMITATIONS This study has been conducted in accordance with generally accepted geotechnical engineering principles and practices in this area at this time. We make no warranty either express or implied. The conclusions and reconunendations submitted in this rep01t are based upon the data obtained from the exploratory borings drilled at the locations indicated on Figure 1, the proposed type of construction and our experience in the area. Our services do not include determining the presence, prevention or possibility of mold or other biological contaminants (MOBC) developing in the future. If the client is concerned about MOBC, then a professional in this special field of practice should be consulted. Our findings include interpolation and extrapolation of the subsurface conditions identified at the exploratory borings and variations in the subsurface conditions may not become evident until excavation is performed. If conditions encountered during construction appear different from those described in this rcpo1t, we should be notified so that re-evaluation of the recommendations may be made. This repmt has been prepared for the exclusive use by our client for design purposes. We are not responsible for technical interpretations by others ofour information. As the project evolves, we should provide continued consultation and field services during construction to review and monitor the implementation of our recommendations, and to verify that the recommendations have been appropriately interpreted. Significant design Joh No. 112 088A ~tech -13 - changes may require additional analysis or modifications to the recommendations presented herein. We recommend on-site observation of excavations and foundation bearing strata and testing of structural fill by a representative of the geotecbnical engineer. Respectfully Submitted, HEPWORTH -PAWLAK GEOTECHNICAL, INC. Reviewed by: Steven L. Pawlak, P.E. DEH/ksw Job No. 112 088A ~tech I I ) / ../ ' ' (,/ -I I ----· r ) ' I ' I ' () 112 088A -----~ ', ---------- ------ --------...____,,-_. ---- \ ----- \ ___________ ........... ___ ___.. ----------------\ LOCATIONS OF EXPLORATORY BORINGS, AND PERCOLATION TEST HOLES FIGURE 1 tu w LJ. J: ti: w Cl 0 5 10 15 20 25 30 35 40 BORING 1 ELEV.=6026' BORING2 ELEV.=6024' 53/12 43/12 BORING3 ELEV.= 6036' 2/6,20/6 WC40 -200=33 12/12 WC=5.8 DD=86 -200=56 2/6,20/6 33/12 BORING 4 PROFILE BORING ELEV.=6047' ELEV.=6032' 6/12 WC=17.1 DD=105 -200=52 16/12 WC=6.2 DD=121 +4=51 -200=25 21/12 12/12 8/12 WC=21.2 DD=99 5/12 WC=14.8 +4=3 0 -200=73 5 23/12 WC=3.8 -200=13 10 15 20 25 30 35 40 tu ~ J: I-a. w Cl NOTE: Explanation of symbols is shown on Figure 3. 112088A ~tech LOGS OF EXPLORATORY BORINGS FIGURE 2 HEPWORTH-PAWLAK GEOTECHNJCAL LEGEND: FILL;Slightly silty sandy gravel with cobbles, loose to medium dense, slightly moist, brown. Clayey gravelly sand at Boring 1, with wood debris and organics at Borings 3 and 4. SAND (SM): Gravelly, silty to slightly clayey, loose, moist, brown. SAND AND GRAVEL (SM-GC); Silty to clayey with cobbles, medium dense, slightly moist to moist, mixed browns. Interlayer with sandy silty and clay. GRAVEL AND COBBLES (GM-GP); Sand, silty, dense, wet, brown. Relatively undisturbed drive sample; 2-inch l.D. California liner sample. Drive sample; standard penetration test (SPT), 1 3/8 Inch l.D. split spoon sample, ASTM D-1586. Drive sample blow count: indicates that 4 blows of 140 pound hammer falling 30 inches were required to drive the 4/1 2 California sampler 12 inches. Depth at which boring caved immediatley following drilling. --Free water depth measured in boring. NOTES: 1. Exploratory borings and the profile boring were drilled on April 18, 20t2 with 4-inch diameter continuous flight power auger and the percolation test holes were dug wiht a mini excavator. 2. Locations of exploratory borings, profile boring and percolation test holes were measured approximately by pacing from features shown on the site plan provided. 3. Elevations of exploratory borings and profile boring were obtained by interpolation between contours shown on the site plan provided. The logs of exploratory and profile borings are drawn to depth. 4. The exploratory boring, profile boring and percolation test hole locations and elevations should be considered accurate only to the degree implied by the method used. 5. The lines between materials shown on the exploratory boring logs represent the approximate boundaries between material types and transitions may be gradual. 6. Water level readings shown on the logs were made at the time and under the conditions indicated. Fluctuations in water level may occur with time. 7. Laboratory Testing Results: WC = Water Content ( % ) DD = Dry Density ( pol) +4 = Percent retained on the No. 4 sieve -200 = Percent passing No. 200 sieve 112088A G&5'tech HEPWORTH·PAWLAK GEOTECHNJCAL LEGEND AND NOTES FIGURE 3 Moisture Content = 5.8 percent Dry Density = 86 pcf Sample of: Sandy Silt and Clay From: Boring 3 at 4 Feet 0 -----... ... -1 -----~ ( _Compression ~~ upon _.,.. ~ wetting 2 ~ *-~ c 0 ·c;; "' 3 ~ E "\ 0 0 4 \ 5 \ 0.1 1.0 10 100 APPLIED PRESSURE -ksf Moisture Content = 21.2 percent Dry Density = 99 pcf 0 Sample of: Sandy Silty Clay ---.......... From: Boring 4 at 20 Feet 1 ....... ' ', 2 / ~ I( No movement upon *-3 wetting c '\ 0 ·c;; I'\ ~ 4 Q. E 0 "' 0 5 ' 6 0.1 1.0 10 100 APPLIED PRESSURE -ksf 112 088A ~tech SWELL-CONSOLIDATION TEST RESULTS FIGURE 4 HEPWORTH·PAWLAK GEOTECHNICAL I HYDROMETER ANALYSIS I SIEVE ANALYSIS I I TIME READINGS I U.S. STANDARD SERIES I CLEAR SQUARE OPENINGS I 24H~ 7HR 3/8' 3/4' 1 1/2' 3" 5"6" 8' 45 IN. 15 MIN. 60MIN19MIN.4 MIN. 1 MIN. #200 #100 #50 #30 #16 #8 #4 0 100 10 90 0 20 so w (') z 30 " z ~ Ui (j) 40 "' ct. 0:: ~ f- 50 .. z w w 0 0 0:: 60 ., 0:: w w !L !L 70 30 BO "' 90 IO 100 0 . 001 .002 ·""' ""' .019 .00, .074 .I .. ... .eoo 1.18 .... ..,, 9.5 12.5 19.0 "·' 76.2 1'2 "" "' DIAMETER OF PARTICLES IN MILLIMETERS CLAYTOSILT SAND ""'"'" COBSLES FINE MEDIUM COARSE ""' ' COARSE GRAVEL 46 % SAND 35 % SILT AND CLAY 19 % SAMPLE OF: Silty Clayey Sand and Gravel FROM: Boring 1 at 1 O and 15 Feet (Combined) HYDROMETER ANALYSIS SIEVE ANALYSIS R. 7 HR TIME READINGS I U.S. STANDARD SERIES I CLEAR SQUARE OPENINGS I 24 3/8' 3/4' 1 1/2' 3' 5'6' 8" 45 IN. 15 MIN. 60MIN19MIN.4 MIN. 1 MIN. #200 #100 #50 #30 #16 #8 #4 0 100 10 90 0 20 80 w (') z 30 70 z ~ Ui 40 60 ~ 0:: f-f- z 50 50 z w w 0 0 0:: 60 40 ffi w !L !L 70 30 80 20 90 10 100 0 .001 .002 .005 .009 .019 .037 .074 .150 .300 .600 1.18 2.36 4.75 9.51 2 _519.o 37.5 76.2 12J,52 203 DIAMETER OF PARTICLES IN MILLIMETERS I SAND I COARSE I QAA'<R I CLAYTOSILT FINE I MEDIUM ""' I [O!AASE COBBLES GRAVEL 51 % SAND 24 % SILT AND CLAY 25 % SAMPLE OF: Slightly Clayey Silty Sandy Gravel FROM: Boring 4 at 5 and 10 Feet (Combined) 112 088A ~tech GRADATION TEST RESULTS FIGURE 5 HEPWORTH-PAWLAK GEOIECHNICAL HYDROMETER ANALYSIS I SIEVE ANALYSIS U.S. STANDARD SERIES I CLEAR SQUARE OPENINGS I HR TIME READINGS I 24 HR. 7 O 45 MIN. 15 MIN. 60MINJ9MIN.4 MIN. 1 MIN. #200 #100 #50 #30 #16 #8 #4 3/8" 3/4" 1 1/2' 3' 5" 6" 8' 100 10 20 30 D w 40 z <( f-w D'.'. f-50 z w u "' w Q_ 60 70 80 90 GRAVEL 5 % SAND 45 % USDA SOIL TYPE: Loam 112 088A ~tech HEPWORTH.PAWLAK GEOTECHNICAL SILT 43 % CLAY 7 % FROM: Profile Boring at 2 Y, Feet USDA GRADATION TEST RESULTS 90 80 70 60 so 40 30 20 10 " z (/j Ul <( Q_ f-z w u "' w Q_ FIGURE 6 0 w z < >--w 0: >--z w (.) 0: w a. HYDROMETER ANALYSIS SIEVE ANALYSIS I CLEAR SQUARE OPENINGS I 24 IHR. 7 HR TIME READINGS I U.S. STANDARD SERIES O 45 MIN. 15 MIN. 60MIN19MIN.4 MIN. 1 MIN. #200 #100 #50 #30 #16 #8 #4 3/8' 3/4' 1 1/2" 3" 5"6" 8' 100 10 20 30 40 50 60 70 80 90 100 .001 .002 Gravel .005 .009 .019 .037 .074 .150 .300 .600 1.18 2.36 4.75 9.5 19.0 37.5 12.5 76.2 152 203 127 DIAMETER OF PARTICLES IN MILLIMETERS SILT I SAND I V. FINE FlNE I MEDllM 1 COARSE V. C0ARSC sw.t.l MEOIUM G";\fl t.AAGE I COB6lES 72 % Sand 19 % -200 9 % USDA SOIL TYPE: Extremely Gravelly Sand From: Percolation Hole P-3 90 80 70 60 50 40 30 20 10 0 " z iii IJ) < a. >--z w (.) 0: UJ a. 112088A ~tech USDA GRADATION TEST RESULTS FIGURE 7 HEPWORTH-PAWLAK GEOTECHNlCAL HEPWORTH-PAWLAK GEOTECHNICAL, INC. TABLE1 Job No. 112 088A SUMMARY OF LABORATORY TEST RESULTS SAMPLE LOCATION NATURAL NATURAL GRADATION PERCENT ATTERBERG LIMITS UNCONFINED MOISTURE DRY GRAVEL SAND PASSING LIQUID PLASTIC COMPRESSIVE SOIL OR BORING DEPTH CONTENT DENSITY NO. ZOO LIMIT INDEX STRENGTH BEDROCK TYPE (%) (%) SIEVE (ft) (%) (pcf) (Ofo) (%) (PSF) 1 10& 15 46 35 19 Silty Clayey Sand and Gravel (combined) 3 1 8.0 33 Silty Gravelly Sand (Fill) 4 5.8 86 56 Sandy Silt and Clay 4 5 17.1 105 52 :Slightly uravelly Sandy Silty clay (Fill) 5 & 10 6.2 121 51 24 25 Slightly Clayey Silty Sandy Gravel (combined) 20 21.2 99 Sandy Silty Clay Profile 2 1h 14.8 3 24 73 :slightly Clayey Silt and Sand (Loam) 8 3.8 13 Silty Sand and Gravel - Pere 3 72 19 9 Slightly Silty Sandy Gravel HOLE NO. HOLE DEPTH (FEET) P-1 30 P-2 33 P-3 30 HEPWORTH-PAWLAK GEOTECHNICAL, INC. TABLE 2 PERCOLATION TEST RESULTS LENGTH OF WATER WATER INTERVAL DEPTH AT DEPTH AT (MIN) START OF END OF INTERVAL INTERVAL (INCHES) (INCHES) 15 7 6Y, 6Y. 6 Water added 7 6% 6% 6Y. 6!4 6 6 5% 15 6Y, 5% Water added 7 6!4 6!4 5% 5% 5!4 4% 4!4 4!4 3% 5 3Y, y, Water added 4~ 1% Water added 4!4 1!4 Water added 4!4 1!4 DROP IN WATER LEVEL (INCHES) y, y, !4 !4 !4 !4 % % y, y, y, y, 3 2% 3 3 JOB NO. 112 OSSA AVERAGE PERCOLATION RATE (MIN./INCH) 60 30 2 Note: Percolation test holes were hand dug in the bottom of backhoe pits and soaked on April 24, 2012. Percolation tests were conducted on April 25, 2012. The average percolation rates were based on the last three readings of each test.