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HomeMy WebLinkAboutFile Documents.993 Moore Dr.0192.2019 (50).ARBKf GEOTECHNICAL INVESTIGATION HARLAND LEEDS RESIDENCE 993 MOORE DRIVE (aka LOT 7, BLOCK G, M F PUD) ASPEN, COLORADO Prepared For: Christopher Harland c!o CCY Architects P.O. Box 529 228 Midland Avenue Basalt, CO 81621 Attention: Simon Elliot, AIA Associate Project No. GS06203.000-125 December 20, 2017 TABLE OF CONTENTS SUMMARYOF CONCLUSIONS..................................................................................................... 1 SITECONDITIONS......................................................................................................................... 2 SITE GEOLOGY AND GEOLOGIC HAZARDS...............................................................................2 PROPOSEDCONSTRUCTION....................................................................................................... 3 SUBSURFACECONDITIONS......................................................................................................... 4 EARTHWORK.................................................................................................................................. 5 FOUNDATION................................................................................................................................. 7 SLAB -ON -GRADE CONSTRUCTION.............................................................................................8 STRUCTURAL FLOORS AND CRAWL SPACES......................................................................... 10 FIGURE 1 -VICINITY MAP FIGURE 2-LOCATIONS OF EXPLORATORY BORINGS FIGURE 3 - SUMMARY LOGS OF EXPLORATORY BORINGS FIGURES 4 AND 5-FOUNDATION WALL DRAIN CONCEPTS TABLE I - SUMMARY OF LABORATORY TESTING CHRISTOPHER HARLAND HARLAND LEEDS RESIDENCE PROJECT NO. GS06203.000.125 GWsemlrtM1mml WmjecwGlenw Spin9eProjectsGS88203.OM128V.RePw IGSO....12$Rt.d Derr= This report presents the results of our geotechnical investigation for the Harland Leeds Residence proposed at 993 Moore Drive within the Five Trees de- velopment in Aspen, Colorado. A vicinity map with the location of the site is shown on Figure 1. We developed this report to provide geotechnical engineer- ing recommendations for the planned construction. The scope of our work is de- scribed in our proposal GS 17-0285; dated December 12, 2017. Our report was prepared utilizing data developed from our previous field and laboratory investigations for a different residence on the property, as well as our current engineering analysis and our professional experience with similar conditions. This report includes a description of the subsurface conditions ob- served in our exploratory borings, results of laboratory testing, and presents ge- otechnical engineering recommendations for design and construction of founda- tions, floor systems, excavations, subsurface and surface drainage, and details influenced by the subsoils. A summary of our conclusions is presented below. SUMMARY OF CONCLUSIONS Subsurface conditions encountered in our exploratory borings consisted of 0.5 to 2 feet of sandy clay "topsoil' and 10 to 16.5 feet of clayey to silty gravel with cobbles and boulders underlain by sandstone bedrock. Sand- stone was found at 12 to 17 feet below the ground surface. Practical auger refusal occurred on boulders and in bedrock at several depths in our bor- ings. Free groundwater was not found in our exploratory borings during drilling operations. Our experience is groundwater will flow on the surface of the sandstone during spring snowmelt. 2. Our subsurface information indicates that the gravel and sandstone bed- rock are present at currently planned foundation elevations. We recom- mend constructing the Harland Leeds Residence on footing foundations. Supported by the undisturbed gravel soil and sandstone bedrock. Further discussion and design and construction criteria for footings are presented in the report. CHRISTOPHERHARLAND NARLAND LEEDS RESIDENCE PROJECT NO. GS062W.000A25 C:WnernW[M1alflBoa@ro)edeWePNOOESpfi„ya.RolecislG50630]00]tl2A2 7r 3. We judge potential risk of differential movement will be low for slab -on - grade construction supported by the undisturbed gravel and/or sandstone bedrock. A permanent drain system consisting of washed rock and imbed- ded PVC drain pipe network should be installed below the lower level slab - on -grade and on crawl space floors. Surface drainage should be designed to provide for rapid removal of sur- face water away from the proposed residence. An exterior foundation drain should be installed around the building. SITE CONDITIONS Five Trees is a residential development south of the Aspen High School Campus in Pitkin County, Colorado. The Harland Leeds Residence will be built at 993 Moore Drive (Lot 7), which is located at the south (upper) terminus of Moore Drive on the lower, north flank of Highland Peak. Ground surface on the lot gen- erally slopes steeply down to the north and northeast. The building envelope is at the west -central part of the lot. Slopes range from about 7 percent in the west (upper) part of the planned building footprint to 25 percent in the east (lower) part. The property is vegetated with aspen, oak brush and dense undergrowth. SITE GEOLOGY AND GEOLOGIC HAZARDS We reviewed USGS Map 1-785A, "Map Showing Areas of Selected Geo- logic Hazards in the Aspen Quadrangle, Pitkin County, Colorado" by Bruce Bry- ant. Bedrock below the site consists of Maroon Formation sandstone with minor siltstone layers. Overlying the sandstone bedrock are surficial deposits of clayey to silty gravel and sand containing some cobbles. We performed a site reconnaissance as part of this investigation. The map identifies areas of flood plains, alluvial fans, landslides, rock fall areas, wet CHRISTOPHER HARLAND HARLAND LEEDS RESIDENCE PROJECT NO. GS06203.000-125 C1WeN thMo�xkPmlevkl I wmd SpdO s -P,aJe WG50620&OW125Q Repa *S06203.000126M.Aa meadows and potentially unstable slopes. Based on the mapping, Lot 7, Moore Family PUD was not shown to be in one of these areas. Our review of geologic mapping and site observations indicate there are no geologic hazards that would preclude the proposed construction or require avoidance. Man-made excavations could result in unstable excavation slopes. High ground water may be encountered during peak snowmelt. Excavation and water control recommendations in this report should be followed. PROPOSED CONSTRUCTION The Harland Leeds Residence will be a two -level, wood -frame building. The main level of the residence will be constructed above -grade on all sides with the floor at elevation 8,395 feet. Garage space will be incorporated into the south part of the main level. The lower (basement) level will be a basement below the north part of the main level. The lower level finished floor will be at about 8,380 feet. Crawl space areas with slab floors will be constructed below some main level living areas. Exterior patios and a swimming pool and spa will be adjacent to the main level. Slab -on -grade floors are the anticipated in the lower (basement) level and in the garage. We expect maximum foundation excavation depths will be about 10 to 15 feet. Foundation loads are expected to vary between 1,500 and 4,000 pounds per foot of foundation wall with maximum interior column loads of 80 kips. If construction will differ significantly from the descriptions above, we should be informed so that we can adjust our recommendations and design criteria, if neces- sary. CHRISTOPHER HARLANO HARLAND LEEDS RESIDENCE PROJECT NO. GE06203.000-126 41UsenWhab\SaMrolecwc;]bx SPUnps-Projects*806203.0W12W. Repo,bIG508203ACO 125 R1.Eme SUBSURFACE CONDITIONS To investigate subsurface conditions for our previous geotechnical engi- neering investigation at the site, we drilled three exploratory borings. The currently planned footprint of the Harland Leeds Residence and the approximate locations of the borings are shown on Figure 2. Exploratory borings were advanced using 4-inch diameter, solid -stem auger and a track -mounted drill rig. Drilling was di- rected by our representative who logged subsurface conditions encountered in the borings and obtained samples. Samples obtained in the field were returned to our laboratory where typical samples were selected for pertinent testing. Graphic logs of the soils encountered in our exploratory borings showing the planned floor level elevations are shown on Figure 3. Subsurface conditions encountered in our exploratory borings consisted of 0.5 to 2 feet of sandy clay "topsoil' and 10 to 16.5 feet of clayey to silty gravel with cobbles and boulders underlain by sandstone bedrock. Observations during drill- ing indicated the gravel was dense to very dense and the sandstone bedrock was very hard. Practical drill rig refusal occurred on boulders and bedrock at multiple depths in two of our borings. Free ground water was not found in our exploratory borings during drilling operations. Borings were backfilled immediately after drilling operations were completed. Two samples of the gravel tested contained 21 and 34 percent silt and clay size particles (passing the No. 200 sieve). Soil sampling equipment limited the maximum retrievable soil particle size to 1.5 and 1.9 inches, depending on the sampler used. Laboratory testing is representative of only the smaller diameter fraction of the actual soil. Observations during drilling and our experience indicate a significant percentage of the subsoils at this site are comparatively larger diam- eter cobbles and boulders. Laboratory testing is summarized on Table I. CHRISTOPHER HARLAND 4 HARLAND LEEDS RESIDENCE PROJECT NO. GS06203.000-125 C.WamWhamsoAPmfeclsMalemv SIfings.Pm*ts%GS06203.OMI26U. Repmts\G606203.000126 RiEoox EARTHWORK We expect maximum foundation excavation depths of 10 to 15 feet. Patios and a pool and spa will be adjacent to the exterior of some basement walls. We recommend an excavation retention system, such as soil nailing, be considered in these areas to reduce the lateral extent of sloped excavations and limit backfill below these structures. A soil nail excavation retention system can be installed with a vertical face. CTUFhompson, Inc. can provide a proposal for design of the soil nail excavation retention system, if requested. Based on our subsurface information, bedrock at the site is near elevation 8382 feet. The planned lower level construction will require an excavation to ap- proximate elevation of 8,380 feet. Excavations that extend more than 2 to 3 feet into sandstone will likely require pneumatic hammer attachments. We anticipate excavation of the gravel overburden soil can be accomplished using conventional, heavy-duty excavation equipment. Boulders will likely be encountered in the ex- cavations. The natural gravel classifies as a Type C soil based on OSHA standards governing excavations. Unretained, temporary excavations deeper than 4 feet should be no steeper than 1.5 to 1 (horizontal to vertical) in Type C soils. The sandstone will likely classify as stable rock. Contractors should identify the soils encountered in the excavations and refer to OSHA standards to determine appro- priate slopes. Contractors are responsible for creating safe and stable excavation slopes. Free ground water was not found in our exploratory borings during this in- vestigation. Groundwater conditions vary seasonally. Our experience in the area CHRISTOPHER HARLAND 5 HARLAND LEEDS RESIDENCE PROJECT NO. G8062D3.000-035 Ce s&Ml th lelEsitPmjttls lenwWd Spings.hofMsMC6E3.OWV26 Re ftIGSN203.M46R1.docx L is that the upper soils become saturated during snowmelt, which can result in sig- nificant flow of ground water into excavations. We recommend sloping excavation floors to gravity discharges or temporary sumps where water can be removed by pumping. Excavations made during spring and early summer will likely encounter areas of ground water seepage into the excavation. If possible, excavations should be made subsequent to peak runoff. Structural Fill Structural fill will be required to attain grades for the driveway, garage, and pool and spa decks. Areas which will receive fill should be stripped of vegetation, organic soils and debris. The on -site gravel soil free of organic matter, debris and rocks larger than 3 inches in diameter can be used as structural fill. Import fill should consist of a CDOT Class 6 aggregate base course or similar soil. Structural fill should be placed in loose lifts of 10 inches thick or less and moisture -conditioned to within 2 percent of optimum moisture content. Structural fill should be compacted to near 100 percent of ASTM D 698 maximum dry density. Moisture content and density of structural fill should be checked by a representa- tive of our firm during placement. Backfill Compaction Foundation wall backfill should be placed and compacted to reduce settle- ment. However, compaction of the backfill soils adjacent to concrete walls may result in cracking of the wall. The potential for cracking can vary widely based on many factors including the degree of compaction achieved, the weight and type of compaction equipment utilized, the structural design of the wall, the strength of the concrete at the time of backfill compaction, and the presence of temporary or per- manent bracing. CHRISTOPHER HARLAND HARLAND LEEDS RESIDENCE PROJECT N0. G906201.600-126 C:%USSMIhWISOx Ji ChlGlenwood SPdNS-% J40SM06]0].00011361 Repoftl"fi203.0W 125 RI.EMx Based on our experience, we recommend that wall backfill soils be mois- ture -conditioned to within 2 percent of optimum moisture content and compacted to at least 95 percent of maximum standard Proctor dry density (ASTM D 698) are typically sufficiently dense to reduce settlement. Compacting the backfill soils to higher density increases the risk of cracking the concrete wall. Particles in excess of 3 inches in diameter should be excluded from the backfill soils. Frost or frozen soils should not be used for backfill. FOUNDATION Our subsurface information indicates the bedrock surface below the build- ing envelope is about elevation 8,381 to 8,382 feet. We anticipate sandstone bed- rock and gravel will be encountered in the excavation for the lower (basement) level. Gravel soil is most likely to be found in shallower excavations for crawl spaces and the garage. The Harland Leeds Residence can be constructed on footing foundations supported by the undisturbed, natural gravel soil and/or sandstone bedrock. Total settlement of 1 inch or less can be expected for the residence if it is supported by the undisturbed, natural gravel. Total settlement of less than inch is expected for footings supported by the bedrock. Differential settlement will likely be to % of the total movement. Our representative should be called to observe conditions in the completed foundation excavation to confirm that exposed conditions are suitable for support of the designed foundations. Recommended design and con- struction criteria for footings are presented below. The footing foundations should be supported by the undisturbed, net- CHRISTOPHER NARLAND HARLAND LEEDS RESIDENCE PROJECT NO. 0806203.000126 C:WaenleNna\BpaVroj«MGlenwaoE SprLps. Frojaeu1G305S1].OW.1351]. RapoNaW505R0].000125 R1..O U ural gravel soil and/or sandstone. Soils loosened during the excava- tion or forming process for the footings should be removed prior to placing concrete. 2. Footings should be designed for a maximum allowable soil pressure of 4,000 psf. To resist sliding, a friction factor of 0.40 between con - crate and the soils and/or bedrock can be used. 3. Continuous wall footings should have a minimum width of at least 16 inches. Foundations for isolated columns should have minimum di- mensions of 24 inches by 24 inches. Larger sizes may be required, depending upon foundation loads. 4. Grade beams and foundation walls should be well reinforced, top and bottom, to span undisclosed loose or soft soil pockets. We recom- mend reinforcement sufficient to span an unsupported distance of at least 12 feet. 5. The soils under exterior footings should be protected from freezing. We recommend the bottom of footings be constructed at a depth of at least 42 inches below finished exterior grades for frost protection. SLAB -ON -GRADE CONSTRUCTION Floors in the basement and garage are proposed as slabs -on -grade. Exte- rior concrete slabs will be constructed for the pool and spa deck, patios and auto - court. Based on our field and laboratory information and our experience, we judge slab -on -grade construction supported by the undisturbed, natural gravel or sand- CHRISTOPHER HARLAND HARLAND LEEDS RESIDENCE PROJECT NO. 0806203.000-126 C:IUe (ha%l XWfOJOCWGlen dSOnga-PMJeCMGWG20MMI25M ReWm 80831IM In RLEaa stone will have a low risk of significant differential movement and associated dam- age. Structural fill placed to attain subgrade elevations for floor slabs and exterior concrete flatwork should be in accordance with the recommendations outlined in the Structural Fill section. We recommend the following precautions for slab -on -grade construction at this site. Slabs should be separated from exterior walls and interior bearing members with slip joints which allow free vertical movement of the slabs. 2. The use of underslab plumbing should be minimized. Underslab plumbing should be pressure tested for leaks before the slabs are constructed. Plumbing and utilities which pass through slabs should be isolated from the slabs with sleeves and provided with flexible couplings to slab supported appliances. 3. Exterior patio and porch slabs should be isolated from the residence. These slabs should be well -reinforced to function as independent units. 4. Frequent control joints should be provided, in accordance with Amer- ican Concrete Institute (ACI) recommendations, to reduce problems associated with shrinkage and curling. CHRISTOPHER HARLAND 9 HARLAND LEEDS RESIDENCE PRO.IECT NO. OS06203.000-125 C:Wsera lhaM Pmj tsk;lenwWd Spr[W5. Profe[I¢MS0M.0O0If 251 RepobGS0820 M126 Rl. e STRUCTURAL FLOORS AND CRAWL SPACES Crawl space areas will be constructed below some main level living areas of the residence. There are design and construction issues associated with struc- tural floors, such as ventilation and increased lateral loads, which must be consid- ered. Ventilation is important to maintain acceptable humidity levels in crawl spaces. The mechanical systems designer should consider the humidity and tem- perature of air, and air flow volumes, during design of crawl space ventilation sys- tems. We believe it is appropriate to install a ventilation system that is controlled by a humidistat. Drain systems in crawl spaces are discussed in the Subsurface Drainage section. FOUNDATION WALLS Foundation walls which extend below -grade should be designed for lateral earth pressures where backfill is not present to about the same extent on both sides of the wall. Many factors affect the values of the design lateral earth pres- sure. These factors include, but are not limited to, the type, compaction, slope and drainage of the backfill, and the rigidity of the wall against rotation and deflection. For a very rigid wall where negligible or very little deflection will occur, an "at -rest" lateral earth pressure should be used in design. For walls that can deflector rotate 0.5 to 1 percent of wall height (depending upon the backfill types), lower "active" lateral earth pressures are appropriate. Our experience indicates typical basement walls in residences deflect or rotate slightly under normal design loads, and that this deflection results in satisfactory wall performance. Thus, the earth pressures on the walls will likely be between the "active" and "at -rest' conditions. If the on -site soils are used as backfill, we recommend design of below - grade walls using an equivalent fluid density of at least 50 pcf for this site. This equivalent density does not include allowances for compaction energy, sloping CHRISTOPHER HARLAND 10 HARLAND LEEDS RESIDENCE PROJECT NO- GS06203.000-126 CW6enWhaW%5a ProleCftZIG dSpHga-hotectatG&I6M3.0=I 25V. R@PDOSIG56B210W 125 RIAE X backfill, surcharges or hydrostatic pressures. An "active" lateral earth pressure of 45 pcf, an "at -rest' lateral earth pressure of 55 pcf, and a "passive" lateral earth pressure of 275 pcf can be used. Backfill should be placed in accordance with the recommendations contained in the Backfill Compaction section. SUBSURFACE DRAINAGE A permanent dewatering system will be required for below -grade areas in the residence. We recommend installation of an exterior foundation drain around the residence. A washed rock layer with an embedded PVC drain pipe network should be installed on crawl space floors and below basement floor slabs. Water from rain, snow melt and surface irrigation of lawns and landscaping frequently flows through relatively permeable backfill placed adjacent to a resi- dence and collects on the surface of relatively impermeable soils occurring at the bottom of the excavation. This can cause wetting of foundation soils, hydrostatic pressures on below -grade walls, and wet or moist conditions in basement areas after construction. We recommend provision of a foundation drain around below - grade areas in the building. The drain should consist of a 4-inch diameter, slotted PVC pipe encased in free draining gravel. The drain should lead to a gravity dis- charge or to a sump pit where water can be removed by pumping. The discharge locations should remain free of blockage at all times. Typical foundation drain de- tails are presented on Figures 4 and 5. Crawl space and basement areas must be provided with efficient drainage. We recommend constructing drains consisting of 2-inch diameter, slotted PVC pipe installed on 6 to 8 foot centers and imbedded in at least 6 inches of washed gravel. The pipes should convey water to perimeter drain collector pipes. Water collected should be discharged to a positive gravity outlet, such as the subdrain CHRISTOPHER HARLAND ff HARLAND LEEDS RESIDENCE PROJECT NO. GS06203.000-025 C:1UeB[a41M1Me\EI[p%Ne[,alGlenwootl SpM,I.-%.j-%IGS0620J.00OIM. IUI.4 WII2..OM45 R1Ao[a located below the sewer, or to sump pits where water can be removed by pumping. The discharge locations should remain free of blockage at all times. A vapor re- tarder should be placed above the washed rock layers to mitigate the potential for standing water in crawl space and subslab areas. A drain should be constructed below the swimming pool. The drain can consist of a 4 to 6-inch layer of washed rock. We recommend an impervious mois- ture barrier between the gravel layer and the subgrade soils. This drain can likely discharge to the same point or structure as the foundation drain system. EARTH RETAINING WALLS Earth retaining walls may be constructed adjacent to the residence and drivewaylautocourt. We consider boulder walls to be landscaping features with little capacity to resist lateral earth loads and movements. We recommend other types of earth retaining systems, such as mechanically stabilized earth (MSE) structures or reinforced concrete retaining walls, at this site. MSE Structures MSE structures consist of a reinforced soil zone comprised of horizontal layers of backfill and geogrid reinforcement. The reinforced zone of the structure then essentially acts like a gravity wall structure to retain soils behind the reinforced zone. This type of system is well -suited for the construction of fill embankments. CTL I Thompson, Inc. can provide designs for MSE systems. Designs are depend- ent on specific material properties of the geogrid reinforcement and wall facing. Some design details and actual construction costs would need to be determined by a specialty contractor. CHRISTOPHER HARLAND 12 HARLAND LEEDS RESIDENCE PROJECT NO G5052D3.000-125 C:\UsanWNeN\BoxlProjettslGlenwmJ Spinga. holecu1G5082:,] 0�12612. Repo,q\GSOBID] WO 121 R1A. Reinforced concrete retaining walls that are attached to the building should be constructed on the same foundation system that is used for the residence. Re- taining wall foundations shall be designed with criteria presented in the FOUNDATIONS section. Retaining walls which can rotate should be designed to resist "active" lateral earth pressure calculated using an equivalent fluid density of at least 45 pcf. Re- taining walls with reinforcement that is tied into building foundation walls, that are not free to rotate, should be designed to resist lateral earth pressure similar to the basement walls. These pressures do not include allowances for sloping backfill or hydrostatic pressures. Backfill behind retaining walls and in front of retaining wall footings should be placed and compacted as outlined in the Backfill Compaction section. Drains are required to control hydrostatic pressures behind retaining walls. The drains should lead to positive gravity outlets or be provided with weep holes. SURFACE DRAINAGE Surface drainage is critical to the performance of foundations, floor slabs and concrete flatwork. Estimated movements in this report are based on effective drainage for the life of the structure and cannot be relied upon if effective drainage is not maintained. We recommend the following precautions be observed during construction and maintained at all times after the residence is completed: The ground surface surrounding the exterior of the residence should be sloped to drain away from the residence in all directions. We rec- ommend providing a slope of at least 6 inches in the first 5 feet around the residence. CHRISTOPHERHARLAND 13 HARLAND LEEDS RESIDENCE PROJECTNO G505203.000-125 C:1Uaen\eNab\eoalProl�ta101mwaoa SpNga. P.l tp MIIU.000IM.R .10506=000126 R1A. 2. Backfill around the exterior of foundation walls should be placed as described in the Backfill Compaction section. Increases in the mois- ture content of the backfill soils after placement often results in set- tlement. Settlement is most common adjacent to north facing walls. Re -attaining proper slopes away from the residence may be neces- sary. 3. The residence should be provided with roof gutters and downspouts. Roof downspouts and drains should discharge well beyond the limits of all backfll. Splash blocks and downspout extensions should be provided at all discharge points. 4. Landscaping should be carefully designed to minimize irrigation. Plants used near foundation walls should be limited to those with low moisture requirements; irrigated grass should not be located within 5 feet of the foundation. Sprinklers should not discharge within 5 feet of the foundation and should be directed away from the residence. 5. Impervious plastic membranes should not be used to cover the ground surface immediately surrounding the residence. These membranes tend to trap moisture and prevent normal evaporation from occurring. Geotextile fabrics can be used to control weed growth and allow some evaporation to occur. CONSTRUCTION OBSERVATIONS This report has been prepared for the exclusive use of the client for the purpose of providing geotechnical design and construction criteria forthe proposed project. The information, conclusions, and recommendations presented herein are CHRISTOPHER HARLAND 14 HARLAND LEEDS RESIDENCE GWseMellteb180x\Rro)ecb\GlmwwL SM,,s-Mj40sW80 3.00013611. Repvb M62010W 126 Rtdo based upon the consideration of many factors including, but not limited to, the type of structure proposed, the geologic setting, and the subsurface conditions encoun- tered. The conclusions and recommendations contained in the report are not valid for use by others. Standards of practice change continuously in the area of ge- otechnical engineering. The recommendations provided are appropriate for about three years. If the proposed structure is not constructed within about three years, we should be contacted to determine if we should update this report. We recommend that CTL I Thompson, Inc. provide construction observation services to allow us the opportunity to verify whether soil conditions are consistent with those found during this investigation. If others perform these observations, they must accept responsibility to judge whether the recommendations in this re- port remain appropriate. GEOTECHNICAL RISK The concept of risk is an important aspect of any geotechnical evaluation. The primary reason for this is that the analytical methods used to develop geotech- nical recommendations do not comprise an exact science. The analytical tools which geotechnical engineers use are generally empirical and must be tempered by engineering judgment and experience. Therefore, the solutions or recommen- dations presented in any geotechnical evaluation should not be considered risk - free and, more importantly, are not a guarantee that the interaction between the soils and the proposed structure will perform as desired or intended. What the engineering recommendations presented in the preceding sections do constitute is our estimate, based on the information generated during this and previous eval- uations and our experience in working with these conditions, of those measures that are necessary to help the residence perform satisfactorily. CHRISTOPHER HARLAND 16 HARLAND LEEDS RESIDENCE PROJECT NO. 6506200,000-126 CSUeeMall,ablSeeNroy[IatGlemroe! Syln9e'%olec kGSM203.WN12%1 ROPOm 40820 MMR1E X LIMITATIONS Our exploratory borings provide a reasonably accurate picture of subsur- face conditions. Variations in the subsurface conditions not indicated by the bor- ings will occur. A representative of our firm should be called to observe the com- pleted foundation excavation to confirm that the exposed soils are suitable for sup- port of the footings as designed. This investigation was conducted in a manner consistent with that level of care and skill ordinarily exercised by geotechnical engineers currently practicing under similar conditions in the locality of this project. No warranty, express or im- plied, is made. If we can be of further service in discussing the contents of this report, please call. CTL 11 N, I C. John Mechling, P.E. Senior Principal Engineer Reviewed by "A;M2ho�I� I n � mesD Kellbg P.E. V, \.` Division JM:JDK:at cc: Via email to selliota).ccvarchitects.com CHRISTOPHER HARLAND 16 HARLAND LEEDS RESIDENCE PROJECT NO. G806200.000-125 C:Wae,ela0anegBonnPralectnGleneooE Songs- PrnlecU10506303.00012M. Repw1 GS06201000125R1.Eecz �' - ..lion Mcoer Hoer wo J 1 SCALE: 1" = 60 LEGEND: TH-1 APPROXIMATE LOCATION • OF EXPLORATORY BORING. Christopher Harland ~ar Residen a Project No. GS06203.000-125 Locations of Exploratory Borings Fig. 2 8400 8395 8390 m 4 Fma 8385 0 8380 8375 8370 TH-1 TH-2 TH-3 LEGEND: EL=8393 EL=8395 EL=8399 ® Sandy clay "topsoil", organics, 8400 moist, dark brown. Gravel, clayey, silty, dense, cobbles and boulders, dense to very dense, ^� moist, rust, brown. (GC, GC —GM) 50/5 8395 ® Sandstone bedrock, very hard, rust. Garage and T Auto Court Drive sample. The symbol 50/7 ' T Slab 8390 indicates that 50 blows of a 140 (EL=8395) pound hammer foiling 30 Inches m were required to drive a 2.5 Inch 17 O.D. sampler 7 inches. 50/8 p 57 8385 Drive sample. The symbol 50/3 Crowlspace Indicates that 50 blows of a 140 Slabs pound hammer falling 30 Inches (EL=8388) m were required to drive a 2.0 inch O.D. sampler 3 Inches. 8380 Indicates practical auger refusal. 50/3 Symbols above the bottom of borings indicate hole location was moved to advance boring farther. Lower Level Lower Level NOTES: Floor Slab Floor Slab 8375 (EL=8380) (EL=8380) 1. Exploratory borings were drilled on September 24, 2004 with 4—Inch diameter, solid —stem auger and a track —mounted drill rig. Exploratory borings were backfilled immediately 8370 after drilling operations were completed. 2. Locations and elevations of exploratory borings are approximate. 3. No free ground water was found in our exploratory borings at the time of drilling. 4. These exploratory borings are subject to the explanations, limitations and conclusions as contained in this report. IV SUMMARY LOGS OF EXPLORATORY BORINGS Project No. GS06203.000-125 Fig. 3 SLOPE PER L OSHA COVER ENTIRE WIDTH OF - GRAVEL WITH NON -WOVEN GEOTEXTILE FABRIC (MIRAFI 140N OR EQUIVALENT). ROOFING FELT IS AN ACCEPTABLE ALTERNATIVE. BACKFILL� PREFABRICATED DRAINAGE COMPOSITE — (MIRADRAIN 6000 OR EQUIVALENT) ATTACH PLASTIC TO FOUNDATION FROM FOOTING IS GREATER) 4-INCH DIAMETER PERFORATED RIGID DRAIN PIPE. THE PIPE SHOULD BE PLACED IN A TRENCH WITH A SLOPE OF AT LEAST 1/8-INCH DROP PER FOOT OF DRAIN. ENCASE PIPE IN 1/2' TO 1-1/2' WASHED GRAVEL. EXTEND GRAVEL LATERALLY TO FOOTING AND AT LEAST 1/2 HEIGHT OF FOOTING. FILL ENTIRE TRENCH WITH GRAVEL. ir BELOW -GRADE WALL F9931H]1:1i D7:117:P] PVC DRAIN NETWORK IMBEDDED IN WASHED CONCRETE AGGREGATE NOTE: THE BOTTOM OF THE DRAIN SHOULD BE AT LEAST 2 INCHES BELOW BOTTOM 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. Foundation Wall Drain H. ft td . Hatlantl Concept Project No. GS06203.000-125 Fig. 4 2-3' BACKFILL � — MIRADRAIN 6000 OR EQUIVALENT H PLASTIC SHEETING NNDATION WALL-1 Pb9:0 COVER ENTIRE WIDTH OF GRAVEL WITH NON —WOVEN GEOTEXTILE FABRIC (MIRAFI 140N OR EQUIVALENT). \ ir NOTE: DRAIN SHOULD BE AT LEAST 2 INCHES BELOW BOTTOM 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. I E71:LRa11:�1�YIL�NI:i 8' MINIMUM I --- OR BEYOND 1:1 SLOPE FROM BOTTOM OF FOOTING. (WHICHEVER IS GREATER) CRAWL SPACE-) 'MUD SLAB' OR VAPOR, BARRIER 6 s 4—INCH DIAMETER PERFORATED DRAIN PIPE. THE PIPE SHOULD BE LAID IN A TRENCH WITH A SLOPE OF AT LEAST 1/8 INCH DROP PER FOOT OF DRAIN. ENCASE PIPE IN 1/2- TO 1-1/2' WASHED GRAVEL. EXTEND GRAVEL LATERALLY TO FOOTING AND AT LEAST 1/2 HEIGHT OF FOOTING. FILL ENTIRE TRENCH WITH GRAVEL. Christopher Harland H..d He:iee�cc Project No. GS06203.000-125 PVC DRAIN NETWORK IMBEDDED IN WASHED CONCRETE AGGREGATE Exterior Foundation Wall Drain Concept Fig. 5