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HomeMy WebLinkAboutHARVEST PARK - Filed SER-SUBSURFACE EXPLORATION REPORT - (2)OCT 1 C 2000 SOILS AND FOUNDATION INVESTIGATION BRIDGE ACROSS MCCLELLAND CHANNEL AT LARIMER COUNTY ROAD 9 FORT COLLINS, COLORADO Prepared For: THE WRITER CORPORATION Northern Colorado Division 5200 Hahns Peak Drive Suite 160 Loveland, Colorado 80538 Attention: Mr. Jim Burczyk Job No. FC-1606 October 13, 2000 CTL/THOMPSON, INC. CONSULTING ENGINEERS 375 E HORSETOOTH RD THE SHORES OFFICE PARK BLDG 3, SUITE 100 FT COLLINS, CO 80525 970)206-9455 TABLE OF CONTENTS SCOPE 1 SUMMARY OF CONCLUSIONS 1 SITE CONDITIONS 1 PREVIOUS AND CONCURRENT INVESTIGATIONS 2 PROPOSED CONSTRUCTION 2 SUBSURFACE CONDITIONS 3 SITE DEVELOPMENT 4 BRIDGE FOUNDATION 5 Drilled Piers Bottomed in Bedrock 5 Footing Foundations 8 LATERAL LOADS ON PIERS 8 ABUTMENTS AND WING WALLS 9 Foundations 9 Excavations 10 Backfill 11 Dewatering 11 CONCRETE 11 LIMITATIONS 12 FIG. 1 - LOCATIONS OF EXPLORATORY BORINGS FIG. 2 - SUMMARY LOGS OF EXPLORATORY BORES FIG. 3 - SWELL-CONSOLIDATION TEST RESULTS FIG. 4 - GRADATION TEST RESULTS FIG. 5 -TYPICAL EARTH RETAINING WALL DRAIN DETAIL TABLE 1 - SUMMARY OF LABORATORY TEST RESULTS THE WRITER CORPORATION BRIDGE ACROSS McCLELLAND CHANNEL AT LARIMER COUNTY ROAD 9 CTLIT JOB NO.FC-1606 SCOPE This report presents the results of our Soils and Foundation Investigation for the proposed bridge across McClelland Channel at Larimer County Road 9 (Ziegler Road) in Fort Collins, Colorado. The report includes descriptions of the subsoil and ground water conditions found in our exploratory borings, discussions of foundation alternatives and design criteria for the bridge, and our opinions regarding the influence of the subsoils on design and construction. Our report was prepared from data developed during our field and laboratory investigations, engineering analysis and our experience. The recommendations presented in this report are based on the proposed construction as we understand it is currently planned. We should be contacted to review our recommendations if plans change. A summary of our findings and conclusions is presented below. Recommendations and criteria for design and construction are presented in the report. SUMMARY OF CONCLUSIONS 1.Strata found in our borings generally consisted of 7 to 12 feet of sandy clay and 0 to 3 feet of slightly clayey sand with gravel underlain by interbedded claystone/sandstone bedrock to the maximum depth explored of 25 feet. A layer of sandy clay fill was encountered in TH-2 from 0 to 5 feet. Ground water was measured at depths of 12 feet in TH-1 and 13 feet in TH-2 respectively).4894 and 4895 feet, res P Y). 2.The bridge can be founded with drilled piers bottomed in bedrock or with footing foundations. Due to ground water on conditions, temporary casing of the piers may be necessary. Footings will need to be protected from scour. Design and construction criteria are presented in the report. SITE CONDITIONS The bridge site is located on Larimer County Road 9 (Ziegler Road) at the McClelland Channel (about 800 feet north of Larimer County Road 36) in Fort Collins, THE WRITER CORPORATION BRIDGE ACROSS McCLELLAND CHANNEL AT LARIMER COUNTY ROAD 9 CTUT JOB NO.FC-1606 Colorado (Fig. 1). At the time of our investigation, County Road 9 was a dirt and gravel road over an existing steel culvert at McClelland Channel. Grading and road construction were in progress on County Road 9 in the vicinity of the channel and utility installation had recently been completed across County Road 9 just north of the channel. McClelland Channel was flowing at a light volume from west to east. The channel banks were moderately vegetated with native grasses, bushes and deciduous trees. An irrigation ditch runs northeast from the north side of the channel east of County Road 9. Land to the east of County Road 9 at the proposed bridge location was primarily agricultural fields or pasture. West and south of the channel crossing, site grading was in progress for Sage Creek Subdivision. PREVIOUS AND CONCURRENT INVESTIGATIONS CTL/Thompson, Inc. performed a Subgrade Investigation and Pavement Design for Larimer County Road 9 at Rock Creek Drive (CTL/T Job No. FC-1607; report dated September 15, 2000). We also performed a Soils and Foundation Investigation for Harvest Park Subdivision, Block 7 (CTL/T Job No. FC-1471; report dated August 17, 2000). We are also performing a Soils and Foundation Investigation for Harvest Park Subdivision, Block 9 (CTL/T Job No. FC-1604). Data from these investigations was considered in the preparation of this report. PROPOSED CONSTRUCTION We believe the proposed bridge will be a three-sided concrete box culvert. We understand the preferred foundation system for the bridge and associated structures is a footing foundation bearing on structural fill below frost and scour depth. We believe the bridge could also be founded with a drilled pier foundation. We have provided geotechnical criteria for drilled piers bottomed in bedrock and for a footing foundation. Larimer County Road 9 and the approaches to the bridge will be paved. Abutments and wing walls will act as retaining walls. The channel flowing will be at an approximate elevation of 4899.8 feet. We anticipate foundation loads will be light THE WRITER CORPORATION BRIDGE ACROSS McCLELLAND CHANNEL AT LARIMER COUNTY ROAD 9 2CTLJTJOBNO.FC-1606 to moderate. Cuts and fills are anticipated to be minor in the vicinity of the proposed bridge. SUBSURFACE CONDITIONS Subsurface conditions were investigated by drilling two exploratory borings at the approximate locations shown on Fig. 1. The borings were advanced using a truck-mounted drill rig and 4-inch diameter, continuous flight auger. Drilling operations were observed by our field representative who logged the soils and obtained samples. The samples were returned to our laboratory where they were visually classified and samples were selected for testing. Graphical logs of the soils and bedrock encountered in the borings and results of field penetration resistance tests are presented on Fig. 2. Strata found in our borings generally consisted of 7 to 12 feet of sandy clay and 0 to 3 feet of slightly clayey sand and gravel underlain by interbedded claystone/sandstone bedrock to the maximum depth explored of 25 feet. A layer of sandy clay fill was encountered in TH-2 from 0 to 5 feet. Ground water was encountered during drilling at a depth of 25 feet in TH-1 and 6 feet in TH-2. When the borings were checked several days after drilling, ground water was measured at depths of 12 feet in TH-1 and 13 feet in TH-2 (elevation 4894 and 4895 feet, respectively). Field penetration tests indicated the fill and clays were medium stiff to stiff, the sands and gravels were medium dense, and the bedrock was medium hard to very hard. One sample of clay fill exhibited an unconfined compressive strength of 6000 psf, a liquid limit of 45 percent and a plasticity index of 30 percent with 85 percent silt and clay-sized particles (passing the No. 200 sieve). A sample of natural clay had a liquid limit of 43 percent and a plasticity index of 28 percent with 80 percent silt and clay-sized particles. Two samples of bedrock exhibited low swell (1.3 and 1.6 percent) when wetted under an applied pressure of 1,000 psf. Two samples of bedrock exhibited unconfined compressive strengths of 13,600 and 17,700 psf. A sample of the bedrock had a liquid limit of 51 percent and plasticity index of 35 THE WRITER CORPORATION BRIDGE ACROSS McCLELLAND CHANNEL AT LARIMER COUNTY ROAD 9 CTLJT JOB NO.FC-1606 3 percent with 95 percent silt and clay-sized particles. The bedrock is approximately 5 to 7 feet below the channel flowline (elevation 4894 in TH-1 and 4893 in TH-2). Laboratory test results are presented on Figs. 3 and 4 and summarized in Table I. SITE DEVELOPMENT Our borings indicate the soils excavated at elevations above the channel flowline will be predominantly sandy clays. The interbedded claystone/sandstone was predominantly medium hard to hard. No cemented zones were encountered in our borings. We anticipate excavation of these soils can be done with conventional excavating and earth-moving equipment. We anticipate conventional drilling equipment will be adequate for the construction of drilled piers. Excavations should be sloped or braced to maintain stable excavation slopes and meet applicable local, state and federal safety regulations. We believe the clays encountered in our borings will classify as Type B soils (under dry conditions) according to the Occupational Safety and Health Administration (OSHA) standards governing excavations published by the Department of Labor. OSHA recommends a minimum slope of 1:1 (horizontal:vertical) for Type B soils. Based on our measurements, ground water was encountered at an approximate elevation of 4895 feet. Clays, sands and gravels, and bedrock below this elevation will likely classify as Type C soils (under wet conditions). OSHA requires a minimum slope of 1.5:1 for Type C soils. These preliminary soil classifications are based on materials encountered in our exploratory borings. The contractor's responsible person should evaluate the soils exposed in excavations as part of the contractor's safety procedures. Soils removed from an excavation should not be stockpiled at the edge of the excavation. We recommend all vehicles and excavated soils be kept at a minimum distance from the top of the excavation equal to at least one-half the depth of the excavation. The exposed slope faces should be protected from the elements. borings at aGroundwaterwasmeasuredinourdepth of 12 to 13 feet belowg the existing ground surface (an approximate elevation of 4895 feet). We anticipate excavations for foundations will be near measured ground water levels for the THE WRITER CORPORATION BRIDGE ACROSS McCLELLAND CHANNEL AT LARIMER COUNTY ROAD 9 4CTLJTJOBNO.FC-1606 construction planned. If groundwater is encountered during excavation and construction, temporary dewatering may be necessary. Construction dewatering to depths of 3 to 4 feet below ground water can likely be accomplished by sloping excavations to sumps and removing the water by pumping or creating gravity outlets. The sumps should be several feet below the bottom of the excavations so that water is pumped down through the soils rather than up through the bottom of the excavation which can decrease the soil support capacity. Stabilization of the subgrade soils may also be necessary to allow construction to continue. This can be accomplished by crowding clean crushed rock into the subgrade soils until a firm surface is achieved. BRIDGE FOUNDATION We have considered two types of foundations for the bridge, including drilled piers bottomed in bedrock and spread footings. The relatively shallow ground water may make the installation of drilled piers difficult and costly, requiring the use of temporary casing and/or dewatering. Our investigation indicates the proposed bridge structures will bottom in sandy clay and clayey sand and gravel. The sandy clays are medium stiff to stiff at foundation level and are expected to be low-swelling. Footing foundations bearing below the zone of probable scour are an alternative. Relatively shallow ground water may create the need for dewatering of footing excavations. Stabilization of some areas of soft subgrade soils may be necessary to allow access with construction equipment. Footing foundations must be protected from scour. Design and construction criteria for drilled piers bottomed in bedrock and for footing foundations are presented below. Drilled Piers Bottomed in Bedrock 1.Piers bottomed in bedrock should be designed for a maximum allowable end pressure of 25,000 psf and an allowable skin friction value of 2,500 psf for the portion of the pier in bedrock. THE WRITER CORPORATION BRIDGE ACROSS McCLELLAND CHANNEL AT LARIMER COUNTY ROAD 9 CTUT JOB NO.FC-1606 5 C-Caj3 2. We recommend designinggg the piers for a minimum deadload pressureof5,000 psf or as high as practical based on the pier cross-sectionalarea. If the minimum deadload pressure cannot be achieved, pierlengthandbedrockpenetrationshouldbeincreasedtocompensatefor the deficiency, using a skin friction value of 2,500 psf for upliftresistance. 3.Piers should penetrate at least 6 feet into relatively unweatheredbedrock. Piers should have a minimum length of at least 18 feet. Longer piers may be necessary to achieve proper bedrock penetration. 4.Shear rings should be installed (using a side tooth) in the lower portionofallpierstohelpresistupliftforcesduetoswellingpressures. We recommend provision of shear rings which extend 2 to 4 inches beyond the nominal pier diameter to increase the load transfer through skin friction. The shear rings should be spaced about 2 feet on centerforthelower6feetofpierinbedrock. 5.Pier drilling should produce shafts with relatively undisturbed bedrockexposed. Excessive remolding and caking of bedrock on pier wallsshouldberemoved. 6.Piers should be reinforced their full length and the reinforcement should extend into wing wall and abutment structures. To calculate the minimum reinforcement required, we recommend assuming an upliftequalto2,500 psf applied to the upper 12 feet of pier, minus thedeadload. In addition, a minimum steel ratio of 0.007 of the pier areausingGrade60steelisrecommended. These steel requirements for potential uplift due to swelling are not considered additive to other steel requirements to resist structural loads such as bending or shear.More reinforcement may be required because of structural considerations. 7.There should be a 4-inch continuous void beneath the grade beams,between the piers, to concentrate the deadload of the structures ontothepiers. 8.Piers should have a center-to-center spacing of at least 3 pierdiameterswhendesigningforverticalloadingconditions, or theyshouldbedesignedasagroup. Piers aligned in the direction of lateral forces should have a center-to-center spacing of at least 8 pierdiameters. Reductions for laterally loaded piers spaced closer than 8 diameters are discu ssed in the following section. If it is necessaryto have piers in close proximity,please call so that we may providedesigncriteriaforpiergroups. THE WRITER CORPORATION BRIDGE ACROSS McCLELLAND CHANNEL AT LARIMER COUNTY ROAD 9CTLTJOBNO.FC-1606 6 9.Quantity and size of column reinforcement may dictate the most convenient size of drilled piers. Economy can be achieved by varying the pier length and limiting the number of pier sizes. We recommend a minimum pier diameter of 20 inches based on the loads anticipated. 10. Piers should be carefully cleaned prior to placement of concrete. Concrete should be on-site and placed in the pier holes immediately after the holes are drilled, cleaned and inspected, using a drill and pour construction procedure. Ground water was encountered in our borings. If ground water is encountered during drilling, temporary casing or a tremie pipe may be required for proper cleaning, dewatering and placement of concrete during pier installation. Concrete should not be placed in pier holes containing more than 3 inches of water. 11. If casing or pumped/tremie concrete placement is required, we recommend the use of high slump concrete, 6 inches (± 1 inch) to provide proper consolidation of the concrete and reduce the probability of concrete arching or hanging on the side of the casing and/or reinforcing steel. The concrete should be designed for the specified strength at the higher slump. At least 5 feet of concrete should be maintained above the ground water level prior to (and during) casing/tremie removal. Casing into the load bearing skin friction zone is not recommended, since casing installation and removal can reduce the friction capacity. 12. Some pier drilling contractors use casing with an O.D. equal to the specified pier diameter. This results in a pier diameter less than specified, typically on the order of 2 inches smaller in diameter. The design and specification of piers should consider the alternatives. If full size casing is desired (I.D. of casing equal to specified pier diameter) it should be clearly specified. If design considers the potential reduction in diameter, then the specification should include a tolerance for a smaller diameter for cased piers. 13. Some movement of the drilled pier foundation is anticipated to mobilize the skin friction. We estimate this movement to be on the order of 1/4 to 1/2 inch. Differential movement may be equal to the total movement. 14. The installation of the drilled pier foundations should be observed by a representative of our firm to confirm the piers are bottomed in the proper bearing strata and to observe the contractor's installation procedures. THE WRITER CORPORATION BRIDGE ACROSS McCLELLAND CHANNEL AT LARIMER COUNTY ROAD 9 CTLJT JOB NO. FC-1606 7 Footing Foundations 1.Footings should bear on undisturbed natural soils, bedrock or properly compacted structural fill. Where soils are loosened during the excavation or in the forming process for the footings, they should be removed and replaced with on-site soils compacted to at least 95 percent of maximum standard Proctor dry density (ASTM D 698)within 0 to 3 percent of optimum moisture content prior to placing concrete. 2. We understand 11/2 inch crushed rock (COOT No. 4 or No. 57 coarse aggregate) is proposed for use as stabilization and structural fill below footings. We believe CDOT No. 4 or No. 57 aggregate is a suitable structural fill material. It should be placed in 8 inch lifts and compacted with a vibratory compactor. The structural fill should extend at least 4 feet beyond the edge of footings and slope down from that point at a 1:1 slope (horizontal:vertical). If crushed rock is used to stabilize the soils in contact with the foundation, adjustment of the coefficient of friction against sliding (given in a following section ABUTMENTS AND WING WALLS) may be necessary. 3. The footings should be designed for a maximum allowable soil pressure of 2,500 psf. 4.Footings should have a minimum width of 2 feet. Isolated column pads should be at least 30 inches square. Larger sizes may be required depending upon the loads and structural system used. 5.Footings should bear below the zone of probable scour, or be protected from scour. The soils under the footings should be protected from the effects of scour. 6.Footings should be protected from frost action. Normally, 3 feet of frost cover is assumed in the Fort Collins area. 7. The completed foundation excavations should be inspected by our firm prior to placing concrete to verify subsurface conditions are as anticipated from our borings. Placement of backfill should be observed and tested. LATERAL LOADS ON PIERS We believe footings are the preferred foundation type. If piers are ultimately chosen, please call and we will provide the needed criteria for lateral load analysis. THE WRITER CORPORATION BRIDGE ACROSS McCLELLAND CHANNEL AT LARIMER COUNTY ROAD 9 CTL/T JOB NO.FC-1606 1;43 ABUTMENTS AND WING WALLS Foundations. Wing walls should be founded with a system similar to the bridge. Wing walls for the bridge can be founded with footings bearing on the natural soils or densely compacted (95 percent of ASTM D 698) structural fill and designed for a maximum soil bearing pressure of 2,500 psf. The footings should be placed sufficiently deep to protect against frost (36 inches) and scour (depends on hydraulics of the channel). The lateral loads acting on abutment and wing walls are primarily dependent on the height of wall, backfill configuration and backfill type. For the purposes of design, we have assumed the backfill will be on-site or similar soils. For abutment and wing walls which will be restrained from rotation, we recommend the walls be designed to resist the "at rest" earth pressure condition. For backfill similar to the on-site soils, we recommend an "at rest" earth pressure corresponding to an equivalent fluid density of 50 pcf. A coefficient of friction of 0.30 may be used to calculate sliding resistance between foundation concrete and the native soils. If crushed rock is used to stabilize the subgrade soils under the footings, a coefficient of friction of 0.40 may be used to calculate sliding resistance. For abutment and wing walls which are free to rotate to develop the shear strength of the backfill, with the associated settlement and cracking of the ground surface behind the walls, we believe the "active" earth pressure can be used. For backfill similar to the on-site soils, we recommend an "active" equivalent fluid pressure of 40 pcf. A "passive" earth pressure equivalent fluid density of 240 pcf is suggested for the native soils used as backfill and 350 pcf for granular compacted fill, provided the soils providing the resistance cannot be removed. Walls which are free to rotate to develop the shear strength of the backfill should be designed for deflections of 0.001 times the height of the wall for granular backfill and 0.004 times the height of the walls for cohesive backfill, and should be battered back accordingly. A moist unit weight of 125 pcf can be used for fill or native soils. The pressures given above do not include allowances for surcharge loads such as sloping backfill, vehicle traffic, or excessive hydrostatic pressure. To reduce THE WRITER CORPORATION BRIDGE ACROSS McCLELLAND CHANNEL AT LARIMER COUNTY ROAD 9 9CTLTTJOBNO.FC-1606 the hydrostatic pressure,we recommend a gravel drain behind the wing walls. Weep holes could be used to drain water through the wing walls. The drain should consist of at least 12 inches of clean, well-graded sand and gravel (e.g. 50 percent fine concrete aggregate mixed with 50 percent coarse concrete aggregate) backfill against the back of the wall to within 2 feet of the ground surface. The top 2 feet should be compacted clays. Weep holes should be at least 4 inches in diameter and spaced 10 feet on-center with no less than three weep holes provided per wall. The back of the weep holes should be protected from clogging and should be screened to prevent drain material from falling out of the weep holes. A manufactured drain such as Miradrain could be substituted for the drain gravel. Manufactured drains should be installed following the manufacturer's recommendations. A typical earth retaining wall drain detail is shown on Fig. 5. Excavations. Our exploratory borings indicate the soils that will likely be excavated will be sands, clays, and claystones. We anticipate that weathered bedrock will be penetrated by excavations for wingwalls and a headwall. For the most part, we believe excavation can be done with backhoes or conventional earthmoving equipment. We do not anticipate blasting will be required. Excavation sides will need to be sloped or braced. The soils across the site vary. We judge that the claystones encountered in our borings are Type A, the clays are Type B and the sands are Type C soils as defined by the OSHA publication, Construction Standard for Excavations". The Type A sands will control the excavation slopes, since they underlie the clays. The publication indicates maximum allowable slopes of 1.5:1 (horizontal:vertical) for Type C soils. In shallower excavations where only Type B soils are exposed, 1:1 (h:v) slopes are permitted by the OSHA standards. OSHA requires the contractor employ a competent person to classify soils for determination of the appropriate slope inclination. The contractor should be familiar with and follow all local, State and Federal safety regulations, particularly the OSHA Standards for Excavations. Side slopes for excavations 20 feet tall or taller are required to be designed by a registered engineer experienced in earth slope design. THE WRITER CORPORATION BRIDGE ACROSS McCLELLAND CHANNEL AT LARIMER COUNTY ROAD 9 0CTLTJOBNO.FC-1606 Ci3-11 BackfilL Wall backfill should be placed in 8-inch maximum loose lifts, moisture-conditioned to within 2 percent of optimum moisture content for granular materials and within 0 to 3 percent of optimum moisture content for clay materials and compacted to at least 95 percent of maximum standard Proctor dry density ASTM D 69-8). We suggest assuming a moist density of 125 pcf for backfill in design calculations. The placement of fill should be observed and tested by a representative of our firm during construction. Dewatering. Free groundwater was measured in our exploratory borings at 12 and 13 feet below the ground surface during this investigation, and near the approximate elevation of the planned excavation. Head wall and wing wall foundations will likely be lower than the current groundwater elevation. Soils in the borings were very moist, and soft ground conditions may be encountered. Higher groundwater levels may develop during the spring season, particularly in wetter years. Groundwater should be lowered in advance of deeper excavations to reduce the caving of excavation side slopes. In excavations into the bedrock, dewatering from trenches in the bottom of the excavations will be more economical and likely possible. When dewatering, care should be taken to draw water down through the soils to reduce the destruction of their bearing capacity. This means sumps should bottom at least 2 feet below the floor of the excavation for which the dewatering is being done. CONCRETE Concrete which comes into contact with the subsoils can be subject to sulfate attack. We measured water soluble sulfate concentrations in a sample of clay and a sample of bedrock from this site. Measured concentrations were 0.002 percent in both samples. Sulfate concentrations less than 0.1 percent indicate negligible exposure to sulfate attack for concrete which comes into contact with the subsoils, according to the American Concrete Institute (ACI). ACI indicates Type I or Type II cement can be used for concrete which comes into contact with the subsoils. Moderate sulfate resistance can be provided by using modified Type II cement with a maximum water-cement ratio of 0.5. THE WRITER CORPORATION BRIDGE ACROSS McCLELLAND CHANNEL AT LARIMER COUNTY ROAD 9 CTLJT JOB NO.FC-1606 11 Our borings were spaced to obtain a reasonable characterization of subsurface conditions. The subsoils identified in our borings are representative of conditions at the boring locations only. Variations in the subsurface conditions not indicated by our borings are possible. Our representative should inspect drilled piers or foundation excavations to confirm the subsurface conditions are as anticipated from our borings. The recommendations presented in this report are based on the proposed construction as we understand it is currently planned. Revision of the construction plans could affect our recommendations. We should be contacted to review our recommendations if plans change. This investigation was conducted with that level of skill and care normally used by geotechnical engineers practicing in this area at this time. No other warranty, express or implied, is made. If we can be of further service in discussing the contents of this report or in the analysis of the influence of the subsoil conditions on design of the structures, please call. CTL/THO OS iNG:NG Marilyn W. S. Palmer, PE Geotechnical Staff Engineer =:r_; y0 REGis Reviewed b e'. cti. -' t i- 33848 fEL)I I /15-Z, /49;Thomas A. Chapel, CPG,I? Project Manager ss H\,E .G,;' MWP:TAC:jll 6 copies sent) THE WRITER CORPORATION BRIDGE ACROSS McCLELLAND CHANNEL AT LARIMER COUNTY ROAD 9 2CTLITJOBNO.FC-1606 L O HARMONY ROAD coo Scc u SITE z U 70 SCALE: 1"=50' 2 v COUNTY ROAD 36 VICINITY MAP NO SCALE Q> a Q 0 Z 0 0 W BM TH-1 McClelland Channel A TH-2 LEGEND: B IDGE TH-1 INDICATES LOCATION OF A COUNTY EXPLORATORY BORING R AD 9 BENCHMARK=SANITARY BM SEWER MANHOLE COVER RIM ELEVATION=4905.77 FEET) 8 Locations of The Writer Corporation Exploratory MCCLELLAND CHANNEL CROSSING AT COUNTY ROAD 9 Borings Job No. FC-1606 Fig. 1 TH-1 TH-2 EL=4906 EL=4908 4910 APPROXIMATE 491* LEGEND: CHANNEL FLOWLINE\ 1 FILL, CLAY, SANDY, STIFF, SLIGHTLY MOIST, YELLOW-BROWN. i 12/12 4/12 4900 490* 7 CLAY, SANDY, OCCASIONAL SAND AND 6/12 GRAVEL LENSES, MEDIUM STIFF TO STIFF, MOIST, BROWN, 12i12 1 YELLOW-BROWN, RUST, GRAY (CL) .RN 14/12 T2' SAND, GRAVELLY, SLIGHTLY CLAYEY, 1j 40i12 MEDIUM DENSE, WET, BROWN, 4890 489• YELLOW-BROWN (SC). II 50/11 50/6 INTERBEDDED CLAYSTONE/SANDSTONE, MEDIUM HARD TO VERY HARD, 50/10 SLIGHTLY MOIST, BROWN,RUST, GRAY BEDROCK). 2 50/10 w 4880 488* w h DRIVE SAMPLE. THE SYMBOL 4/12 w N INDICATES 4 BLOWS OF A 140-POUND 1 HAMMER FALLING 30 INCHES WERE z- z REQUIRED TO DRIVE A 2.5 INCH 0.0. 0 o SAMPLER 12 INCHES.H- H H H Q- w 4870 487* w INDICATES WATER LEVEL MEASURED AT TIME OF DRILLING. INDICATES WATER LEVEL MEASURED SEVERAL DAYS AFTER DRILLING. 4860 486* NOTES: 1.THE BORINGS WERE DRILLED ON AUGUST 24, 2000 USING 4-INCH DIAMETER, CONTINUOUS FLIGHT AUGER AND A TRUCK-MOUNTED DRILL RIG. 4850 485• 2.BORING LOCATIONS AND ELEVATIONS ARE APPROXIMATE AND WERE STAKED AND SURVEYED BY A REPRESENTATIVE OF OUR FIRM REFERENCING THE BENCHMARK SHOWN ON FIG. 1. 3.THESE LOGS ARE SUBJECT TO THE 4840 484* EXPLANATIONS, LIMITATIONS AND CONCLUSIONS IN THIS REPORT. 4830 4836 SUMMARY LOG OF EXPLORATORY BORING JOB NO. FC-1606 FIG. 2 3 2 1 EXPAI\JSION UNDER CONSTANT PRESSURE DUE TO WETTING z o I 0 6 z Q 1a x w 0 z -2 0 6 _ N w ix -3 a 2 0 U 4 0.1 1.0 10 100 APPLIED PRESSURE•KSF Sample of INTERBEDDED CLAYSTONE/SANDSTONE NATURAL DRY UNIT WEIGHT= 123 PCF From TH-1 AT 19 FEET NATURAL MOISTURE CONTENT= 13.3 % 3 1 2 j 1-- I EXPANSION UNDER CO1 STA" 1 PRESSURE DUE TOIWETTING 1 1 z 1 Hin a 1 0 2 w a -3 -- 2 0 U j 4 0.1 1.0 10 100 APPLIED PRESSURE - KSF Sample of INTERBEDDED CLAYSTONE/SANDSTONE NATURAL DRY UNIT WEIGHT= 114 PCF From TH-2 AT 19 FEET NATURAL MOISTURE CONTENT= 18.1 Swell Consolidation JOBNO. FC-1606 Test Results FIG. 3 1:Q1 . HYDROMETER ANALYSIS SIEVE ANALYSIS 25 HR. 7 HR.TIME READINGS U.S.STANDARD SERIES CLEAR SQUARE OPENINGS 45 MIN. 15 MIN. 60 MIN. 19 MIN. 4 MIN. 1 MIN. '200 '100 '50 '40 '30 "16 '10 '8 '4 3/8" 3/4" 1i4' 3" 5"6" 8" 100 I I 0 90 10 8020 7 70 30 Z N Q a B0 40 llaZ 50 w cc to 0 a 40 60 a 30 70 20 80 10 90 0 -- 100 001 0.002 .005 .009 .019 .037 .074 .149 .297 042590 1.19 2.0 2.38 4.76 9.52 19.1 36.1 76.2 127152200 DIAMETER OF PARTICLE IN MILLIMETERS SANDS GRAVEL CLAY(PLASTIC)TO SILT(NON-PLASTIC) FINE I MEDIUM I COARSE FINE I COARSE I COBBLES Sample of SAND, GRAVELLY,CLAYEY GRAVEL _ 20 % SAND 57 % From TH-2 AT 14 FEET SILT&CLAY 23 % LIQUID LIMIT - % PLASTICITY INDEX HYDROMETER ANALYSIS I SIEVE ANALYSIS I 25 HR. 7 HR.TIME READINGS U.S.STANDARD SERIES CLEAR SQUARE OPENINGS 45 MIN. 15 MIN. 60 MIN. 19 MIN. 4 MIN. 1 MIN. '200 '100 '50 '40 '30 '16 '10 '8 '4 3/8" 3/4" 1'/:" 3" 5"6" 8' 100 0 90 I 10 80 I T 20 0 70 30 0 z a7, I I 40 a 60 ill] cc w50 50 L.Li C w a40 ` I I I a 30 70 20 I . I I 80 10 90 0 I I . 100 001 0.002 .005 .009 .019 .037 .074 .149 .297 0.42590 1.19 2.0 2.38 4.76 9.52 19.1 36.1 76.2 12152200 DIAMETER OF PARTICLE IN MILLIMETERS SANDS GRAVEL CLAY(PLASTIC)TO SILT(NON-PLASTIC) FINE I MEDIUM COARSE FINE COARSE COBBLES Sample of GRAVEL SAND From SILT&CLAY LIQUID LIMIT PLASTICITY INDEX Gradation JOB NO. FC-1606 Test Results FIG. 4 1Q=1 1 12"MIN. 10 1 I BACKFILLED WITH CLAYEY ON-SITE T SOIL u RETAINING WALL a ' PROVIDE GRAVEL LAYER SCREEN OR COARSE a ed ti BEHIND WALL,WASHED CONCRETE AGGREGATE GRAVEL OVER HOLE ASTM C33,NO.57 OR 67). a c WEEP HOLES,SPACED 10 FEET O.C. BACKFILL 1 1 ON TERIMATERIALS ROUND SURFACE 4-INCH- DIAMETER PERFORATED DRAIN REINFORCING STEEL PIPE. THE PIPE SHOULD BE PLACED PER STRUCTURAL IN A TRENCH WITH A SLOPE RANGING DRAWINGS BETWEEN 1/16-INCH AND 1/8-INCH DROP PER FOOT OF DRAIN. NOTE: rip DRAIN PIPE TO GRAVITY OUTLET, OR WEEP HOLES,OR BOTH MAY BE USED FOOTING OR OTHER TYPE FOUNDATION Typical Earth Retaining Wall Drain I. 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