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HomeMy WebLinkAboutB12-0274 Soils Report 062812.pdfKOECHLEIN CONSULTING ENGINEERS, INC. CONSULTING GEOTECHNICAL AND MATERIALS ENGINEERS a GEOTECHNICAL INVESTIGATION PROPOSED ACKERMAN RESIDENCE LOT I LIA ZNEIMER SUBDIVISION VAIL, COLORADO i l ' Prepared for: Paige & Charles Ackerman 819 West Forest Road Vail, CO 81657 Job No. 05 -166 October 5, 2005 DENVER: 12364 West Alameda Prlcwy., Suite 115, Lakewood, CO 80228 (303) 989 -1223 AVONISILVERTHORNE: (970) 949 -6009 A TABLE OF CONTENTS SCOPE I EXECUTIVE SUMMARY I SITE CONDITIONS 3 PROPOSED CONSTRUCTION 4 GEOLOGIC HAZARDS INVESTIGATION 4 INVESTIGATION 5 SUBSURFACE CONDITIONS 6 RADON 7 MOLD 7 GROUND WATER 7 EXCAVATIONS 8. SHORING 9— FOUNDATIONS 9 FLOOR SLABS 12 FOUNDATION DRAINAGE 13 LATERAL WALL LOADS 13. RETAINING WALLS 14 SURFACE DRAINAGE 15 IRRIGATION 16 COMPACTED FILL 17 . LIMITATIONS 18 , ` VICINITY MAP Fig. I LOCATIONS OF EXPLORATORY BORINGS Fig. 2 LOGS OF EXPLORATORY BORINGS Fig..3 LEGEND OF EXPLORATORY BORINGS Fig. 4 GRADATION TEST RESULTS Figs. 5 and. 6 SWELL-CONSOLIDATION TEST RESULTS Fig. 7 TYPICAL WALL DRAIN DETAIL Fig. 8. _ TYPICAL RETAINING WALL DRAIN DETAIL Fig. 9. SUMMARY OF LABORATORY TEST RESULTS Table I October 5, 2005 KOECHLEIN CONSULTING ENGINEERS, INC. Job No. 05 -166 Consulting Geotechnical Engineers SCOPE This report presents the results of a geotechnical investigation for the proposed residence to be located on Lot 1 in the Lia Zneimer Subdivision in Vail, Colorado. The approximate site location is shown on the Vicinity Map, Fig. 1. The purpose of this investigation was to evaluate the subsurface conditions at the site and to provide geotechnical recommendations for the proposed residence. This report includes descriptions of subsurface soil, bedrock, and ground water conditions encountered in the_ exploratory borings and recommendations for foundation systems, allowable bearing capacity, and design and construction criteria. This report was prepared from data developed during our field and laboratory investigations and our experience with similar projects and subsurface conditions in the area. The recommendations presented in this report are based on a residence being constructed on the lot at the approximate location indicated on the Locations of Exploratory Borings, Fig. 2. We must be contacted by the contractor and /or owner to review our recommendations when final plans for the structure have been completed. A summary of our findings and conclusions is, presented in the following paragraphs. EXECUTIVE SUMMARY 1. The subsurface conditions encountered in the exploratory borings varied across the site. The subsurface conditions encountered in exploratory boring TH -1 consisted of very dense, gravelly, clayey sand to a depth of 18.5 feet. Underlying the gravelly, clayey sand, to the maximum depth explored . of 23.0 feet, the subsurface conditions consisted of very hard October 5, 2005 KOECHLEIN CONSULTING ENGINEERS, INC. Job No. 05 -166 Consulting Geotechnical Engineers sandstone bedrock. Practical drill rig refusal in sandstone bedrock was encountered af a depth. of 23.0 feet in boring TH -1. The subsurface conditions encountered in exploratory borings TH -2 and TH -3 consisted of approximately 1.0 foot of topsoil overlying stiff to hard, sandy, gravelly clay to a depth of 22.0. feet in boring TH -2, and the maximum depth explored of 14.0 feet in boring TH -3. Underlying the sandy, gravelly clay . in boring . TH -2, to the maximum depth explored , of 35.0 feet, the subsurface conditions consisted of very. dense, gravelly, . clayey sand. Practical drill rig refusal on sandstone bedrock was encountered in exploratory boring TH -3 at a depth of 14.0 feet. Laboratory test results indicate that the natural, sandy, clay has low swell potential. 2. At the time of this investigation,_ no free ground water was encountered in any of the exploratory borings to the maximum depth explored' of 35.0 feet. 3. We anticipate that the subsurface conditions at the proposed foundation elevation' will consist of gravelly, clayey sand, sandy, gravelly clay, or sandstone bedrock.. In our opinion, the gravelly, clayey sand, sandy, . gravelly clay, or sandstone bedrock will support spread footings for .the proposed residence. However, if both soil and bedrock are encountered within the foundation excavations for the residence, special precautions should be followed: Refer to. the FOUNDATIONS section . of this report for more .details. 4. The subsurface conditions encountered at the proposed floor slab elevations consisted of natural, gravelly, clayey sand or sandy, gravelly clay. In our opinion, slabs -on -grade may be constructed on the natural, gravelly, clayey sand or sandy, gravelly clay with a low risk'of movement. Refer to the FLOOR SLABS section of this report for more details. 5. Open cuts and excavations require precautions as outlined in this report in order to maintain the stability of slopes and sides of excavations. Refer to - the EXCAVATION section of this report for additional details. 6. 'Because cobbles and very hard sandstone were encountered at this site, heavy -duty excavation equipment may be -required to complete the required excavations. If encountered, pockets of very hard sandstone may require blasting or chiseling in order Jo complete the necessary excavations. Refer to the EXCAVATIONS - section of this report for additional details. K October 5, 2005 KOECHLEIN CONSULTING ENGINEERS, INC. € Job No. 05 -166 Consulting Geotecknical Engineers I. 7. Due to the anticipated depth of excavation along the north side of the proposed residence, shoring of the excavation may be required. Refer to i the SHORING section of this report for additional details. 8. Drainage around the residence should be designed and constructed to provide for rapid removal of surface runoff and avoid concentration of water adjacent to foundation walls. Refer to the FOUNDATION DRAINAGE section of this report for additional details. 9. The potential for radon gas is a concern in the area. Building design should include 'ventilation systems for below grade areas such as crawl spaces and basements. Refer to the RADON section of this report for additional details. 10. The potential for mold is a concern. We recommend that the contractor and /or owner contact a professional Industrial Hygienist for specific recommendations on how to prevent and/or mitigate mold. Refer to the MOLD section of this report for additional details. SITE CONDITIONS The proposed residence will be located on Lot 1 in the Lia Zneimer Subdivision in Vail, Colorado. Access to the lot will be from the east and a new driveway that will branch off from Buffehr Creek Road. At the time of this investigation, the lot was undeveloped. Vacant land borders the site to the north and east. Bordering the site to the west is an existing retaining wall and the driveway used to access Lots 2 through 6 of the same subdivision. Bordering the site to the south is Buffehr Creek Road. Topography of the lot slopes steeply down towards the south at an approximate grade of 42 percent. Vegetation on the lot consists of grasses, weeds, shrubs, and aspen trees. 3 October 5, 2005 Job No. 05 -166 KOECHLEIN CONSULTING ENGINEERS, INC. Consulting Geotechnical Engineers PROPOSED CONSTRUCTION Based on a conversation with a representative of Fritzlen Pierce Architects, we understand that .a two- story, single family residence with a walkout lower level and attached garage will be constructed on the lot. The finished floor elevation for the lower level will be 8269. The proposed residence will most likely be of wood frame construction with cast -in -place concrete foundations and slab -on -grade floors. We understand that a.three tiered retaining wall system will be constructed adjacent to the .driveway. We anticipate that excavations up to 35 feet may be required for construction of the proposed residence and attached garage. In addition, cuts up to 12 feet and fills up to 4 feet may be required for the construction of the driveway. Access to the residence will be from the east and a new driveway that will branch off from Buffehr Creek Road southeast of the proposed building site. Maximum column and wall loads were assumed to be those normally associated with residential structures. GEOLOGIC HAZARDS INVESTIGATION A geologic hazards investigation was outside the scope of this investigation. We recommend that the owner review the Town of Vail regulations to determine whether a geologic hazards investigation has been performed previously for this subdivision or site. If a geologic hazards investigation has not been performed for this site, we recommend that a professional geologist be contacted to perform this service. 4 a INVESTIGATION Subsurface conditions at this site were investigated on September 19, 2005 by drilling three exploratory borings with a four -inch diameter, continuous flight, solid stem power auger -mounted on a tracked drill rig at the approximate locations shown on the Locations of Exploratory Borings, Fig. 2. Initially, we planned to drill four exploratory . borings. However, due to the steep topography of the lot, and the presence of a large growth of Aspen trees, access to boring locations was extremely limited. An engineer from our office was on the site to observe the drilling of the exploratory borings and visually classify and document the subsurface soil, bedrock and ground water conditions. A description of the, subsurface soils and bedrock observed in the exploratory borings is shown on the Logs of Exploratory Borings, Fig. 3; and on the Legend of Exploratory Borings, Fig. 4. Representative soil samples obtained from the exploratory borings were tested in our laboratory in order to determine their natural moisture content, gradation properties and swell- consolidation potential. The results of the laboratory tests are presented on the Logs of Exploratory Borings, Fig. 3; on the Gradation Test Results, Figs. 5 and 6; on the Swell- Consolidation Test Results, Fig. 7; and on the Summary of Laboratory Test Results, Table I. 5 October 5, 2005 KOECHLEIN CONSULTING ENGINEERS, INC. �. Job No. 05 -166 Consulting Geotechnicnl Engineers SUBSURFACE CONDITIONS The subsurface conditions - encountered in the exploratory borings varied across the site. The subsurface conditions encountered in exploratory boring TH -1 consisted of red- brown, dry to moist, very dense, gravelly, clayey sand with scattered cobbles to a depth of 18.5 feet. Underlying the gravelly, clayey sand with scattered cobbles to the maximum depth explored of 23.0 feet, the subsurface conditions consisted of red- brown, dry, very hard sandstone bedrock. Practical drill rig refusal in sandstone bedrock was encountered at a depth of 23.0 feet in boring TH -1. The subsurface conditions encountered in exploratory borings TH -2 and TH -3 consisted of approximately 1.0 foot I of topsoil overlying red - brown, white, green, slightly moist to very moist, stiff to hard, sandy, gravelly clay with scattered cobbles to a depth of 22.0 feet in boring TH -2 and the maximum. depth explored of 14.0 feet in boring TH -3. Practical drill rig refusal on i sandstone bedrock was encountered at a depth of 14.0 feet in boring TH -3. Underlying the sandy, gravelly clay with scattered cobbles in boring TH -2, to the maximum depth I- explored of 35.0 feet, the subsurface conditions consisted of the red - brown, moist, very ,I dense gravelly, clayey sand with scattered cobbles. Laboratory test results indicated that i the sandy, gravelly clay has low swell potential. At the time of this investigation, no free ground water was encountered in any of 1 the exploratory borings to the maximum depth explored of 3.5.0 feet. 6 October 5, 2005 KOECHLEIN CONSULTING ENGINEERS, LNC Job No. 05 -166 Consulting Geotechnical Engineers i RADON In recent years, radon gas has become a concern. Radon gas is a colorless, odorless gas that is produced by the decay of minerals in soil and rock. The potential for radon gas in the subsurface strata of mountain terrain is likely. Since excavations for lower levels in the residence are anticipated, we suggest that the building be designed with ventilation for below grade areas. MOLD Mold tends to grow in areas that are dark and damp, such as crawlspaces, below grade areas, or bathrooms. Recommendations for mold prevention, mitigation, or remediation are outside the scope of this, investigation. We recommend that the contractor and /or owner contact a professional Industrial Hygienist to provide specif c recommendations for the p revention and /or remediation of mold. GROUND WATER 'At the time of this investigation, no free ground water was encountered in any of the exploratory borings to the maximum depth explored of 35.0 feet. Therefore, we do not anticipate that ground water will affect construction of the proposed residence. However, our investigation was performed during a dry time of the year. It is possible. that groundwater may be encountered during wetter times of the year. If ground water is encountered within excavations for the proposed residence, the ground water can 7 a October 5 2005 KOECHLEIN CONSULTING ENGINEERS, INC. .lob No. 05 -166 Consulting Geotechnicol Engineers typically be controlled by shallow trenches on the outside of the foundation for the residence. The shallow trenches should be sloped down to a sump pit, where the water can be removed by pumping or to a gravity outlet. If ground water is encountered within } the excavation for the residence, we must be contacted to provide specific recommendations at that time. EXCAVATIONS We anticipate that excavations up to 35 feet in depth may be required for construction of the proposed residence. Because cobbles and very hard sandstone were encountered in the exploratory borings, it is our opinion that heavy -duty construction equipment may be required to complete the necessary excavations at this site. The sandstone bedrock. may require chiseling or blasting to complete the necessary excavations. Care needs to be exercised during construction so that the excavation slopes remain stable. The subsurface soils, which consisted of the gravelly, clayey sand and sandy, gravelly clay, classify as. Type B soils in accordance with OSHA regulations. Weathered sandstone classifies as Type A soils in accordance with OSHA regulations. Hard sandstone classifies as Stable Rock.. in accordance with OSHA regulations. OSHA regulations should be followed in all excavations and cuts. 8 4 October 5, 2005 KOECI-ILEIN CONSULTING ENGINEERS, INC. Job No. 05 -166 Consulting Geotechnicul Engineers SHORING Due to the anticipated depth of excavation along the north side of the proposed residence, shoring of the excavation may be required. If a shoring system is necessary, we recounnend a contractor specializing in shoring be contacted . for design recommendations and construction of the shoring. . i FOUNDATIONS The subsurface conditions at the proposed foundation elevations may consist of the gravelly, clayey sand, sandy, gravelly clay, or sandstone bedrock. We anticipate that sandstone bedrock could be encountered in the north side of the excavation for the - I residence. Because the bedrock is very hard and unyielding, spread footings constructed on a combination of soil and bedrock could experience differential movement of approximately I to 2 inches. In order to reduce the risk of differential movement between spread footing elements, special design and construction techniques could be .used. One technique that could be used to reduce the risk of differential movement is to design the foundation using varying maximum allowable bearing pressures. Another alternative is to overexcavate the bedrock and soils below the proposed foundation and construct a geosynthetic- reinforced structural fill below the entire building footprint. The i foundation may then be designed using a uniform maximum allowable bearing pressure. i 9 October 5, 2005 KOECHLERV CONSULTING ENGINEERS, INC Job No. 05 -166 Consulting Geotechnical Engineers . While this technique does not eliminate the risk of differential movement, it- will reduce the amount of differential movement if it occurs. If the owner is not willing to accept the risk of differential movement between the foundation elements, then the foundation system should be constructed entirely on the sandstone bedrock or on a deep foundation system. If the owner chooses to support the proposed residence on a deep foundation system, we should be contacted for additional recommendations. If the owner is willing to accept the risk of differential movement, then the foundation may be constructed on a combination of natural soils and bedrock. . We. recommend 'the following design and construction criteria for foundations bearing on a combination of natural soils and bedrock. 1. Footings may be supported by the* natural, gravelly, clayey sand; sandy, gravelly clay; sandstone bedrock; or properly moisture conditioned and compacted structural fill, as described below in Items 3, 4, 6, 9, and 10. 2. Spread footings constructed on the gravelly, clayey sand or' sandy, gravelly clay may be designed for a maximum allowable bearing pressure of 3,000 psf. -Spread footings constructed on the sandstone bedrock may be designed for a maximum allowable bearing pressure of 6,000 psf. 3. As an alternative to constructing the foundation directly on the natural soils and bedrock, if the owner chooses to further reduce the effect of differential movement on the foundation elements, the natural soils and bedrock may be overexcavated a minimum of 2.0 feet and replaced with a properly moisture conditioned and compacted structural fill with a geotextile reinforcement at the, base over the entire excavation. The geotextile reinforcement may cnsist of Tensar BX1100, Tensar BX1200 or equivalent. Spread footings may then be constructed on the reinforced structural fill._ Spread footings constructed on a uniform layer of structural 10 October 5, 2005 KOECHLEIN CONSULTING ENGINEERS, INC. JobNo..05 -I66 Consulting Geotechnical Engineers fill may be designed for a. maximum allowable bearing pressure of 2,000 psf. 4.. If structural fill is. placed'below the proposed foundation, we recommend that a uniform thickness of fill be placed beneath all foundation elements. The structural fill should be moisture treated and compacted as recommended in the COMPACTED FILL section of this report. 5... WaII footings and foundation walls should be designed to span a distance of at least 10.0 feet in order to account for anomalies in the soil or fill. 6. Foundation wall backfill should not be considered for support of load bearing footings. Footings should be stepped and supported by undisturbed natural soils and should not be constructed. on foundation walI backfill. Foundation walls or grade beams should be designed to span across an excavation backfill zone and should not be constructed with footings within this zone. 7. - The base of the exterior footings should be established at a -minimum depth below the final exterior ground. surface, as required by the local building code. We believe that the depth for frost protection in the -local. building code in this area is 4.0 feet. 8. Column footings should have a- minimum dimension of 24 inches square and continuous wall footings should have a minimum width of 16 inches. Footing, widths may be greater to accommodate structural design loads. 9. We anticipate that cobbles could be - encountered at the foundation elevation. Removal of the cobbles may result in depressions and rough bottoms in the excavation.. The resulting depressions can be backfilled with compacted backfill or lean concrete. 10. Fill should be placed and compacted as outlined in the COMPACTED FILL section of this report. We recommend that a representative of our office observe and test the placement and compaction of structural fill used in foundation construction. It has been our experience that without engineering quality control, poor construction techniques can occur which result in poor foundation performance. 11: A representative of our office must observe completed. foundation excavation. Variations from the conditions described in this report, which 11. October 5, 2005 KOECHLEINCONSULTININC G ENGINEERS, IN Job T4o. 05-166 Con suiting Geotechnical Engitteers were not indicated by our borings, can occur. The representative can observe the excavation to evaluate the exposed subsurface conditions. FLOOR SLABS We anticipate that the residence will, be constructed with slabs -on- grade. The subsurface soils at the floor slab elevations will consist of the natural, gravelly, clayey sand, or sandy, gravelly clay. In our opinion the.natural, gravelly, clayey sand or sandy, gravelly clay will support slab s -on :grade with a low risk of movement. We recommend the following precautions for the construction of slab -on -grade floors at this site: 1. Slabs may be placed on the natural, gravelly,. clayey sand; sandy, gravelly clay;' or properly moisture conditioned and compacted structural fill. 2. We anticipate that cobbles could be encountered at the floor slab elevations. 'The removal of cobbles may result in depressions and rough bottoms in the excavation. Fill may be placed and compacted beneath the slabs -on -grade to fill in depressions and act as a leveling course for the slabs. 3. Slabs should be separated from exterior walls and interior beating members.. Vertical. movement of the slab should not be restricted. . 4. Exterior slabs should be separated from the building. These slabs should be reinforced- to function as independent units. Movement of these slabs should not be transmitted directly to the foundations or walls of the structures. 5. - Frequent control joints should be provided in all" slabs to reduce problems associated with shrinkage of concrete: . 6. Fill beneath slabs -on -grade may consist of on -site soils free of deleterious material or approved fill. Fill should be placed and compacted as recommended in the COMPACTED FILL section of this report. Placement 12 y October 5, 2005 KOECHLEIN CONSULTING ENGINEERS, INC. . Job No. 05 -166 Consulting Geotechnical Engineers and compaction of fill beneath slabs should be observed and tested by a representative of our office. FOUNDATION DRAINAGE Surface water, especially that originating from 'snowmelt, tends to flow through relatively permeable backfill typically found adjacent to foundations. The water that i flows through the fill collects on the surface of relatively impermeable-soils occurring at the foundation elevation. Both this surface water and possible. ground water can cause wet or moist below grade conditions after construction. Since we anticipate below grade areas, we recommend the installation of a drain along the below grade foundation walls. The drain should consist of a 4 -inch diameter perforated pipe encased in free draining gravel and a manufactured wall drain. The drain should be sloped so that water flows to a sump where .the water can be removed by pumping, or to a positive gravity outlet. Recommended details for a typical foundation wall drain. are presented in the Typical Wall Drain Detail, Fig. 8. LATERAL WALL LOADS i - We anticipate that walls will be planned.which may require lateral earth pressures i for design. Lateral earth pressures depend on the type of backfill and the height and type of wall. Walls, which are free to rotate sufficiently to mobilize the strength of the backfill, should be designed, to resist the. "active" earth pressure condition. Walls, which 13 N October 5; 2005 KOECHLEIN CONSULTING ENGINEERS, INC Job No. 05 -I66 Consulting Geotechnical Engineers j i i are restrained, should be designed to resist the "at rest" earth pressure condition. i Basement walls are typically restrained. The following table presents the lateral wall !: pressures that may be assumed for design. Earth Pressure Condition Equivalent Fluid Pressure ef) Active 35 At -rest 50 Passive 300 Notes: 1. Equivalent fluid pressures are for a horizontal backfill condition with no hydrostatic pressures or live loads. 2. A coefficient of friction of 0.3 may be used at the base of footings to resist lateral loads. Backfill placed behind or adjacent to foundation walls and retaining walls should be placed and compacted as recommended in the COMPACTED FILL section of this report. Placement and compaction of the fill must be observed and tested by a representative of our office. RETAINING WALLS Based on the site plan provided by the architect, several retaining walls will be constructed on the north side of the proposed driveway. The retaining walls will vary in height from approximately 1 to 6 feet. Retaining wall types that could be used for this application include mechanically stabilized earth (MSE) retaining walls, concrete cantilever walls, boulder gravity walls, timber or concrete crib walls, and soil nails. A 14 i October 5, 2005 hOECHLEIN CONSULTING ENGINEERS, INC. ,lob No. 05 -166 Consulting Geotechnical Engineers professional Geotechnical Engineer should design retaining walls greater than 4 feet in height. Because we anticipate retaining walls greater than 4 feet in height will be constructed on.this site, we have provided the following information for the design and i construction of retaining walls. Foundations for retaining walls may be designed and constructed as outlined in the FOUNDATIONS section of this report. Lateral earth loads for retaining wall designs are presented in the LATERAL WALL LOADS section of this report. In order to reduce j the possibility of developing hydrostatic pressures behind retaining walls, a drain should be constructed adjacent to the wall. The drain may consist of .a manufactured drain system and gravel. -The gravel should have, a maximum size of 1.5 inches and have a maximum of 3 percent passing the No. 200 sieve. Washed concrete aggregate will be j i satisfactory for the drainage layer. The manufactured drain should extend from the bottom of the retaining wall to within 2 feet of subgrade elevation. The water can be °I drained by a perforated pipe with collection of the water at the bottom of the wall leading to a positive gravity outlet. A typical detail for a retaining wall drain is presented in the Typical Retaining Wall Drain Detail, Fig. 9. SURFACE DRAINAGE Reducing . the wetting of structural soils and the potential of developing hydrostatic pressure behind below grade walls can be achieved by carefully planned and .15 maintained surface drainage. We recommend the following precautions be observed ! . i during construction and maintained at all times after the residence is completed: 1. Wetting or drying -of the open excavation should be minimized during j construction. 2.- All surface water should be directed away from the top. and sides of the excavation during construction. 3. The ground surface surrounding the exterior of the residence should be sloped to drain away from the building in all directions. We recommend a slope of at least 12 inches in the first 10 feet. 4. Hardscape (concrete and asphalt) should be sloped to drain away from the buildings. We recommend a slope of at least 2 percent for all hardscape within 10 feet of the buildings: 5. Roof drains should discharge at least 10 feet away from foundation walls with drainage directed away from the residences. I 6. Backfill, -especially around foundation walls, should be placed and compacted as recommended in the. COMPACTED- FILL section of this report. 7. Surface drainage for this site should be designed by a Professional Civil Engineer. IRRIGATION Irrigation systems installed next to foundation walls, retaining walls, or sidewalks could cause consolidation of backfill below and adjacent to these areas. This can resu t in settling of exterior steps,. patios and/or. sidewalks over backfilled areas. We recommend the following precautions be followed: 16 October 5, 2005 KUECWLEi1V C'U1V3UL1RVU B1VU11YLC1tJ, J1Vl.. Job No. 05 -166 Consulting Geotechnical Engineers 1. Do not install an irrigation system next to foundation walls or above retaining walls. The irrigation system should be at least 10 feet away from the residence or face of retaining walls. 2. Irrigation heads should be pointed away from the structure or in a manner that does not allow the spray to come within 5 feet of the residence or face of retaining walls. 3'. The landscape around the irrigation system should be sloped so that no poalding occurs at the irrigation heads. 4. Install landscaping geotextile fabrics to inhibit growth of weeds and to allow normal moisture evaporation. We do not recommend the. use of a plastic membrane to inhibit the growth of weeds. 5. Control valve boxes for automatic irrigation systems should be at least 10 feet away from the structure and periodically checked for leaks and flooding. COMPACTED FILL Structural fill for this project may consist of the on -site gravelly, clayey sand; sandy, gravelly clay; or approved imported granular fill. The imported fill may consist of non- expansive silty or clayey sands or gravels with up to 30 percent passing the No. 200 sieve and a maximum plasticity index of 10. No cobbles, boulders or sandstone fragments larger than 6 inches should be placed in fill areas. Fill areas should be stripped of all vegetation and topsoil, scarified, and then compacted. Topsoil may be used in landscape areas. Fill should be placed in thin loose lifts then moisture treated and compacted as shown in the following table. The recommended compaction varies for the given use of the fill. 17 S Use of Fill Recommended Compaction Percentage of the Standard Proctor Maximum Dry Density (ASTM D -698) Percentage of the Modified Proctor Maximum Dry Density ASTM D -1557) Below Structure Foundations 98 95 Below Slabs -On -Grade 95 90 Retaining Wall Backfill 95 90 Utility Trench Backfill 95 90 Backfill (Non- Structural ) 90 90 Notes: 1. For clay soils the moisture content should be 0 to +3 percent of the optimum moisture content. 2. For granular soils the moisture content should be —2 to +2 of the optimum moisture content. We recommend that a representative from our office observe and test the placement and compaction of each lift placed for structural fill. Fill placed below foundations, behind retaining walls, or below slabs -on -grade is considered structural. It has been our experience that without engineering quality control, inappropriate construction techniques can occur which result in poor foundation and slab performance. - LIMITATIONS i Although the exploratory borings were located to obtain a reasonably accurate determination of subsurface conditions, variations in the subsurface conditions are always possible. Any variations that exist beneath the site generally become evident during excavation for the structure. Therefore, we must be contacted by the contractor and /or owner so that a representative of our office can observe the completed excavations to confirm that the soils are. as indicated by the exploratory borings, and to verify our 18 b October 5, 2005 XOECHLEIN CONSULTING ENGINEERS, INC. Job No. 05 -166 Consulting Geolechnical Engineers foundation and floor slab recommendations. In addition, the final construction plans 1. i including fill placement should be submitted to our office for study to determine compliance. with the recommendations presented in this report or to provide required a 5 additional recommendations prior to construction. The placement and compaction of fill, as well as installation of foundations, should also be observed and tested. The preliminary design criteria and subsurface data presented in this report are valid for 3 years from the date of this report provided that a representative from our office observes the site at that time and confirms that the site i conditions are similar to the conditions presented in the SITE CONDITIONS section of this report and that the recommendations presented in this report are still applicable. i October 5, 2005 KOECffMbV CONSULTING ENGINEERS, INC. suiting Geoiechnicai Engineers Job No. 05 -166 Con We appreciate the opportunity to provide this service. If we can be of further assistance in discussing the contents of this report or in analyses of the proposed structure from a soils and foundation viewpoint, please contact our office. KOECHLEIN CONSULTING ENGINEERS; INC. Richard M. Wenzel III, P.E. Project Engineer Reviewed by: William H. Koechlein, P.E. President i(4 copies sent) i 20 1 JOB NO. 05 -166 FIG.1 1 " =60' LOCATIONS OF EXPLORATORY BORINGS JOB NO. 05 -166 FIG. 2 8270 LU LU 8265 Z O Q 7 IL —1 8260 W 8255 r 8250 KOECHLEIN CONSULTING ENGINEERS, INC. . Consulting Geotechnical Engineers w TH -1 AP P. EL. 8284 134/12 WC =4 8285 8285 DD =115 OaQ lza: �;;:;• r:r:� • - 200 =17 TH -2 odca 1 8/1 2 APP.EL. 8279 8280 o"A TH -3 8280 •r. za • x x:x WC=4 o • o•Iz� 30/12 Y.7a.' APP.EL.8277 rz:� - 200 =14 ►Q -• 7:.7 U.' -. 16/12 X'?:x' .: >:x• WC =17 5 0/3 %:i:x' DD =113 8275 prop - 200 =72 y'% %: 18112 tr l: 8275 I 8270 LU LU 8265 Z O Q 7 IL —1 8260 W 8255 r 8250 19112 WC =7 DD =125 - 200 =31 8270 m 8265 G O Z m m 8260 I 8255 —I 8250— 8245 Mcl 82 45 35/12 LOGS OF EXPLORATORY BORINGS JOB NO. 05 -166 FIG. 3 a 4 134/12 WC =4 10/12 DD =115 lza: �;;:;• r:r:� • - 200 =17 r:r:c 1 8/1 2 I38112 •r. za • x x:x WC=4 51!12 DD =126 Y.7a.' rz:� - 200 =14 7:.7 U.' 16/12 X'?:x' .: >:x• WC =17 5 0/3 %:i:x' DD =113 - 200 =72 19/12 19112 WC =7 DD =125 - 200 =31 8270 m 8265 G O Z m m 8260 I 8255 —I 8250— 8245 Mcl 82 45 35/12 LOGS OF EXPLORATORY BORINGS JOB NO. 05 -166 FIG. 3 a 4 KOECHLEIN CONSULTING ENGINEERS, INC. . Consulting Geotechnical Engineers i LEGEND: Q. SAND, Gravelly, Clayey, Scattered cobbles, Dry to a moist,, Very dense, Red - brown. B® T SANDSTONE, Dry, Very Hard, Red - brown. TOPSOIL CLAY, Sandy, Gravelly, Scattered cobbles, Slightly moist to very moist, Stiff to hard, Red- brown, White, Green. REFUSAL. Indicates practical drill rig refusal in sandstone bedrock. CALIFORNIA DRIVE SAMPLE. The symbol 30/12 indicates that 30 blows of a 140 pound hammer falling 30 inches were required to drive a 2.5 inch O.D. sampler 12 inches. Notes: 1. Exploratory borings were drilled. on September 19, 2005 using a 4 -inch diameter auger mounted on a tracked drill rig. 2. No free ground water was encountered at the time of drilling in any of the exploratory borings to the maximum depth explored of 35.0 feet. 3. The Boring Logs are subject to the explanations, limitations, and conclusions as contained in this report. 4. Laboratory Test Results: WC - Indicates natural moisture ( %) DD - Indicates dry density (pcf) -200- Indicates percent passing the. No. 200 sieve N 5. Approximate elevations are based on the topographic site plan provided by the Architect. LEGEND OF EXPLORATORY BORINGS JOB NO. 06 -166 FIG. 4 0 Sample of SAND, Gravelly, Clayey GRAVEL 28 % SAND 55 % Source TH -1 Sample No. Elev. /Depth 10.0 feet SILT & CLAY 17 % LIQUD LIMIT % PLASTICITY INDEX % Source TH -1 Sample No. Elev. /Depth 15.0 feet SILT & CLAY 14 % LIQUID LIMIT io PLASTICITY INDEX % GRADATION TEST RESULTS Job No. 05 -166 FIG. 5 U �mi�n��Niu��wnu�■�nN�u�iiuua� �uiun■�en�n���uiu■�imne■�mn��■■ Mill imomiiiiiilmmiiih no Sample of SAND, Gravelly, Clayey GRAVEL 28 % SAND 55 % Source TH -1 Sample No. Elev. /Depth 10.0 feet SILT & CLAY 17 % LIQUD LIMIT % PLASTICITY INDEX % Source TH -1 Sample No. Elev. /Depth 15.0 feet SILT & CLAY 14 % LIQUID LIMIT io PLASTICITY INDEX % GRADATION TEST RESULTS Job No. 05 -166 FIG. 5 U KOECHLEIN CONSULTING ENGINEERS Sample of CLAY, Sandy GRAVEL I % SAND ' 27 % Source TH -2 Sample No. Elev. /Depth 14.0 feet SILT & CLAY 72 % LIQUD LIMIT % PLASTICITY INDEX % Sample of SAND, Clayey GRAVEL 9 % SAND 60 % Source TH -2 Sample No. ElevdDepth 24.0 feet SILT & CLAY 31 % LIQUID LIMIT % PLASTICITY INDEX GRADATION TEST RESULTS Job No. 05 -166 FIG. 6 e a ■�IIYII�■� II�IIi��rinl�ni�IMIN1�Il1�II�I1H !�IINIIIl�IIIII�� �IIIRIB�RIIIH�Illlio MINIM 110 0 UNION I HIM I IN I oil HIM 0 MEN 111 110M INS 1E N NUNN umNnEimu�■N omHIM �mii�NE ■mii�E �m�■�nmtumnuill■�mi��■�nun� i uilliuminnmimi�aE uu����m� NINE 0 11111111111111110 1 lllism 11 illool iiiim■iinii�H�iiuiiu■i 11101111iimiiiii OEM= Sample of CLAY, Sandy GRAVEL I % SAND ' 27 % Source TH -2 Sample No. Elev. /Depth 14.0 feet SILT & CLAY 72 % LIQUD LIMIT % PLASTICITY INDEX % Sample of SAND, Clayey GRAVEL 9 % SAND 60 % Source TH -2 Sample No. ElevdDepth 24.0 feet SILT & CLAY 31 % LIQUID LIMIT % PLASTICITY INDEX GRADATION TEST RESULTS Job No. 05 -166 FIG. 6 e a rreSbWe, p, mw Sample of CLAY, Sandy Natural Dry Unit Weight= 123.0 (pcf) Source TH -2 Sample No. Elev. /Depth 4.0 feet Natural Moisture Content= 6 % SWELL - CONSOLIDATION TEST RESULTS Job No. 05 -166 FIG. 7 - s e� a EDGE OF EXCAVATION (EXCAVATE AS PER OSHA REGULATIONS) i KOECHLEIN CONSULTING ENGINEERS, INC. Consulting Geotechnical Engineers . fr BELOW GRADE WALL I MANUFACTURED WALL DRAIN 1 OR DAM PROOOF NG FILTER FABRIC ' i GRAVEL t2 PLASTIC SHEETING `— 12" MIN, PERFORATED PIPE NOTES: 1, DRAIN SHOULD BE AT LEAST 12 INCHES BELOW TOP OF FOOTING AT THE HIGHEST POINT AND SLOPE DOWNWARD TO A POSITIVE GRAVITY OUTLET OR TO A SUMP WHERE WATER CAN BE REMOVED BY PUMPING. 2. EXCAVATIONS ADJACENT TO FOOTINGS SHOULD BE CUT AT A 1 TO 1 (HORIZONTAL TO VERTICAL) OR FLATTER SLOPE FROM THE BOTTOM OF THE FOOTINGS. EXCAVATIONS ADJACENT TO FOOTINGS SHOULD NOT BE CUT VERTICALLY. 3. THE DRAIN SHOULD BE LAID ON A SLOPE RANGING BETWEEN 1/8 INCH AND 114 INCH DROP PER FOOT OF DRAIN. 4. GRAVEL SPECIFICATIONS: WASHED 1.5 INCH TO NO.4 GRAVEL WITH LESS THAN 3 % PASSING THE NO. 200 SIEVE. 5. THE BELOW GRADE CONCRETE FOUNDATION WALLS SHOULD BE PROTECTED FROM MOISTURE INFILTRATION BY APPLYING A SPRAYED ON MASTIC WATERPROOFING, DAMPPROOFING, OR AN EQUIVALENT PROTECTION METHOD. TYPICAL WALL DRAIN DETAIL JOB NO. 05 -166 FIG. 8 a 3 EDGE OF EXCAVATION (EXCAVATE AS PER OSHA REGULATIONS) JOB NO. 05 -166 FILTER PERFORATED PIPE NOTES: WATERPROOFING OR DAMPPROOFING 1. DRAIN SHOULD BE SLOPED DOWNWARD TO A POSITIVE GRAVI'T'Y OUTLET OR TO A SUMP WHERE WATER CAN BE REMOVED BY PUMPING. 2. THE DRAIN SHOULD BE LAID ON A SLOPE RANGING BETWEEN 118 INCH AND 114 INCH DROP PER FOOT OF.DRAIN. 3. GRAVEL SPECIFICATIONS: WASHED 1.5 INCH TO NO.4 GRAVEL WITH LESS THAN 3% PASSING THE NO. 200 SIEVE. 4. THE BELOW GRADE. CONCRETE RETAINING WALLS SHOULD BE . PROTECTED FROM MOISTURE INFILTRATION BY APPLYING A SPRAYED ON MASTIC WATERPROOFING, DAMPPROOFING, OR AN EQUIVALENT PROTECTION METHOD, TYPICAL RETAINING WALL DRAIN DETAIL FIG. 9 HOLE SAMPLE DEPTH `ft> NATURAL MOISTURE CONTENT N NATURAL DRY DENSITY (Pcf) ATTERBERG LIMITS PASSING NO. 200 SIEVE . N PERCENT SWELL AT 1,000 PSF N SOIL TYPE LIQUIrD LIMIT `%� PLASTICITY INDEX N TH -1 1 10.0 4 115 17 SAND, Gravelly, Clayey TH -1 15.0 4 126 14 SAND, Gravelly, Clayey TH -2 9.0 5 123 +0.2 CLAY, Sand TH -2 14.0 17 113 72 CLAY, Sand TH -2 24.0 7 125 31 SAND, Clayey JOB NO, 05 -166 G KOECHLEIN'CONSULTING ENGINEERS, INC.