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HomeMy WebLinkAboutSubsoil Study for Foundation Design 02.02.2007caLiTHoMPsoN SOILS AND FOUNDATION INVESTIGATION PETROSIUS RESIDENCE LOT 30, CERISE RANCH GARFIELD COUNTY, COLORADO Prepared For: MR. ED PETROSIUS P.O. Box 4199 Aspen, CO 81612 Project No. GSO4925-120 February 2, 2007 234 Center Drive I Glenwood Springs, Colorado 81601 Telephone:970-945-2809 Fax:970-945-7411 TABLE OF CONTENTS SCOPE SUMMARY OF CONCLUSIONS SITE CONDITIONS GEOLOGIC HAZARDS AND MITIGATION PROPOSED CONSTRUCTION SUBSURFACE CONDITIONS SITE EARTHWORK Excavations Structural Fits Fill and Backfill FOUNDATIONS Helical Piers Footings FLOOR SYSTEM AND SLABS -ON -GRADE BELOW -GRADE CONSTRUCTION SUBSURFACE DRAINAGE SURFACE DRAINAGE LIMITATIONS FIGURE 1 - APPROXIMATE LOCATIONS OF EXPLORATORY BORINGS FIGURE 2 -- SUMMARY LOGS OF EXPLORATORY BORINGS FIGURE 3 — SWELL -CONSOLIDATION TEST RESULTS FIGURES 4 AND 5 — EXTERIOR FOUNDATION WALL DRAIN TABLE I — SUMMARY OF LABORATORY TEST RESULTS MR. ED PETROSIUS PETROSIUS RESIDENCE PROJECT NO. GSO4925-120 S:%GS04925.000112012. ReportslG50492$ 120 Rtdoc 1 1 2 2 3 3 4 4 5 6 6 7 7 8 10 10 11 12 SCOPE This report presents the results of our soils and foundation investigation for the Petrosius Residence proposed on Lot 30, Cerise Ranch in Garfield County, Colorado. We conducted the investigation to evaluate the subsurface conditions at the site and provide geotechnical engineering recommendations for the planned construction. Our report was prepared from data developed from our field exploration, laboratory testing, engineering analysis, and experience with similar conditions. This report includes a description of the subsurface conditions found in our exploratory borings and our opinions and recommendations for design and construction of foundations, floor systems, below -grade construction, drain systems and details influenced by the subsoils. The recommendations contained in the report were developed based on the currently planned construction. We should be informed if actual construction will differ significantly from the descriptions herein. A summary of our conclusions is presented below. SUMMARY OF CONCLUSIONS 1. Subsurface conditions encountered in our exploratory borings consisted of about 3 inches of silty sand "topsoil' underlain by silty sand with gravel and occasional cobbles and boulders to the total explored depth of 23 feet. Practical auger refusal occurred on boulders at 23 feet in our TH-2. Free ground water was not found in our exploratory borings during drilling operations. 2. Our exploratory borings indicate that natural sand soils are present at anticipated foundation elevations. Our investigation did not identify collapsible soils on the site, however, the potential exists that some of the soils could possess the potential for excessive settlement when wetted or vibrated. In our opinion, two foundation design alternatives should be considered. The residence can be founded on helical piers or on footings. Design criteria for helical piers and footings and additional discussion are presented in the report. 3. We judge that slabs -on -grade constructed on the natural soil will have a low to moderate risk of differential movement and associated damage. The risk of slab -on -grade movement can be reduced by placing a minimum 2 foot thick layer of structural fill below slabs. After the sub -excavation process is accomplished, we judge that a slab -on - MR. EO PETROSIUS PETROSIUS RESIDENCE PROJECT NO. GSO4925-120 &IGS04925,000112012. RapartslG504925 120 R1.dac grade floor can be supported with low a risk of differential movement and associated damage. Additional discussion is in the report. 4. Surface drainage should be designed to provide for rapid removal of surface water away from the proposed residence. A foundation drain should be installed around below -grade areas. SITE CONDITIONS Cerise Ranch is a residential development located north of Highway 82 in Garfield County, Colorado. Lot 30 is east of the cul-de-sac at the end of Larkspur Drive (see Figure 1). Ground surface on the lot slopes down to the southwest at grades of about 20 percent. Stockpiles of rock and about I foot of snow were present on the lot at the time of our investigation. Vegetation on the lot consists of pinion trees and native grasses. GEOLOGIC HAZARDS AND MITIGATION Portions of Lot 30 were mapped as rockfall hazard areas and potentially unstable slopes in our Revised Geologic Hazard Evaluation (CTL ! Thompson, Inc. Job No. GS-2953, dated February 3, 2000). Recent mapping by the Colorado Geologic Survey titled "Collapsible Soils and Evaporite Karst Hazards Map of the Roaring Fork Corridor, Garfield, Eagle and Pitkin Counties, Colorado" (Jonathan White, 2002) identified the soils at the site as potentially collapsible and underlain by Eagle Valley Evaporite. Eagle Valley Evaporite bedrock formations are soluble and possess the potential for spontaneous ground openings (sinkholes) and subsidence deformation and settlement near sinkholes and closed depressions. We judge that the risk of sinkhole formation on this lot is low and does not require mitigation. We judge that the risk of soil collapse in the building envelope on this lot is low to moderate. If some risk is acceptable, no mitigation is an alternative. The risk of soil collapse can be mitigated on this lot by constructing the residence on a helical pier foundation as described in the Foundations section. We judge that the MR. ED PETROSIUS 2 PETROSIUS RESIDENCE PROJECT NO. G504925-120 5:5G5n4925.000112012. RoporlsYGS04925 120 R1.das risk to the proposed construction from potentially unstable slopes and rock fall is low and does not require mitigation. PROPOSED CONSTRUCTION Building plans for the Petrosius Residence were notavailable atthe time of our investigation. We understand the residence will likely be a two-story, wood -frame building. A basement or walkout lower -level may be constructed. A garage will likely be north of the building. We expect the client desires a slab -on -grade floor in the garage. Maximum excavation depths will be between 3 and 10 feet. We expect maximum foundation loads of 1,000 to 3,000 pounds per linear foot of foundation wail and maximum column loads of 30 kips. If actual construction will differ significantly from the descriptions above, we should be informed so that we can check that our recommendations are appropriate. SUBSURFACE CONDITIONS Subsurface conditions on Lot 30, Cerise Ranch were investigated by drilling two exploratory borings (TH-1 and TH-2) with 4-inch diameter, solid -stem auger and a track -mounted drill rig at the approximate locations shown on Figure 1. Drilling operations were directed by our laboratory/field manager who logged the soils encountered in the borings and obtained samples for testing in our laboratory. Graphic logs of the soils found in our exploratory borings are shown on Figure 2. Subsurface conditions encountered in our exploratory borings consisted of about 3 inches of silty sand "topsoil" underlain by silty sand with gravel and occasional cobbles and boulders to the total explored depth of 23 feet. Practical auger refusal occurred on boulders at 23 feet in our TH-2. Results of field penetration resistance tests and observations during drilling indicated the sand was loose to dense. Free ground water was not found in our exploratory borings during drilling operations. Borings were backfilled immediately after drilling operations were completed or piped to facilitate future measurements of ground water levels. MR. ED PETROSIUS 3 PETROSIUS RESIDENCE PROJECT NO. GSO4925-120 S;1GSO4925.00GM02. ReportslG504925 120 R1.doc Samples obtained in the field were returned to our laboratory where typical samples were selected for testing. One sample of the sand was selected for one- dimensional, swell -consolidation testing. During the test procedure the sample at natural moisture content was loaded with 1,000 psf and then flooded. The resulting volume change (i.e., swell or consolidation) was then measured. The sample tested exhibited nil consolidation when wetted under an applied load of 1,000 psf. A sample of the sand selected for engineering classification testing contained 33 percent silt and clay sized particles (passing the No. 200 sieve) and indicated a liquid limit of 30 percent and a plasticity index of 2 percent. Results of swell -consolidation testing are shown on Figure 3. Laboratory test results are summarized on Table I. While not indicated by our subsurface information or laboratory testing, the potential for collapsible soils exists on this lot. Collapsible soils have been identified in the area of Cerise Ranch. If subjected to excessive wetting, such as from a leaking water line, irrigation line, or watering of landscaping, the potential exists that excessive settlement of the soils could occur. SITE EARTHWORK Excavations The planned excavation to construct the residence will encounter sand with occasional cobbles and boulders. Bedrock will not likely be encountered. Excavations for the planned foundation and utilities at this site can be accomplished using conventional, heavy-duty excavation equipment. Excavation sides will need to be sloped or braced to meet local, state and federal safety regulations. The sand will likely classify as a Type C soil based on OSHA standards governing excavations. Temporary slopes deeper than 4 feet should be no steeper than 1.5 to 1 (horizontal to vertical) in Type C soils. Contractors should identify the soils encountered in excavations and refer to OSHA standards to determine appropriate slopes. MR. ED PETROSIUS 4 PETROSIUS RESIDENCE PROJECT NO. GSO4925-920 5:5GS04925.0=120%2. Reports5GSO4925 120 Ri.doc Free ground water was not found in our exploratory borings during this investigation. We do not anticipate excavations for foundations or utilities will penetrate ground water. Excavations should be sloped to a positive gravity outfall or to a temporary sump where water from precipitation can be removed by pumping. Structural Fill Our exploratory borings indicate that natural sand will likely be present at anticipated foundation elevations. Removal (i.e. sub -excavation), moisture -treatment and recompaction of the soils below the planned building footprint to a depth of at least 2 feet below bottom of slab elevations will reduce the risk of slab movement. The bottom of the sub -excavated area should extend laterally at least t foot beyond the perimeter of the building footprint. The bottom of the sub -excavated area should be scarified to a depth of at least 8 inches, moisture -treated and compacted. Our representative should be called to observe conditions exposed in the sub -excavated area prior to beginning placement of structural fill. We recommend re -using the excavated soil as structural fill, provided it is free of organics, debris and rocks larger than 3 inches in diameter. An alternative that can be considered would be to import an aggregate base course for use as structural fill. A sample of desired import fill soils should be submitted to our office for approval prior to hauling. Structural fill should be moisture treated to within 2 percent of optimum moisture content and compacted to 100 percent of standard Proctor (ASTIVI D 698) maximum dry density. Fill soils should be uniformly mixed to create a relatively homogeneous fill soil. Additional water required to increase the existing soil moisture content to the specified moisture content should be uniformly mixed into the fill soil during mixing prior to compaction. We recommend fill be placed in maximum loose lift thickness of 8 inches. The actual thickness of fill lift that can be properly compacted will depend on the type of compaction equipment. In order for the procedure to perform properly, close control of structural fill }placement to MR. ED PETROSIUS 5 PETROSIUS RESIDENCE PROJECT NO. GSO4925-120 S:XGS04926.000%12012. RoportsM04925120 Ri.doo specifications is required. Our representative should observe placement and check compaction and moisture content of the structural fill. Fill and Backfill Proper placement and compaction of fill and backfill adjacent to foundation walls is important to reduce infiltration of surface water and settlement of backfill soil. f Backfill should consist of the on -site soils or similar soils free of organics, debris and rocks larger than 6 inches in diameter. Backfill should be placed in loose lifts of 8 inches thick or less, moisture -treated to within 2 percent of optimum moisture content and compacted to at least 95 percent of standard Proctor (ASTM D 698) maximum dry density. The top 1 to 2 feet of backfill should consist of a clay soil to limit infiltration of surface water. FOUNDATIONS Our exploratory borings and site investigation indicate that natural sands are likely present at anticipated foundation elevations of the proposed residence. While not indicated by our subsurface information or laboratory testing, the potential for collapsible soils exists on this lot. Collapsible soils have been identified in the area of Cerise Ranch. If subjected to excessive wetting, such as from a leaking water line, irrigation ditches or lines, or watering of landscaping, the potential exists that excessive settlement of the soils could occur. A positive method to reduce the potential for differential movement of the building foundation is the installation of helical piers. Helical piers transfer building loads to soils below the zone of wetting. A. second foundation alternative is to constructthe residence on a footing foundation. We believe risk of differential foundation movement and associated damage is higher with a footing foundation. If the residence is constructed on footings, care must be taken to ensure that soils below the structure are not wetted. Recommendations in the Subsurface Drainage and Surface Drainage sections will be critical to performance of the structure. The helical piers or footings should be designed and constructed with the criteria below. MR. ED PETROSIUS 6 PETROSIUS RESIDENCE PROJECT NO, GSO4925-120 SAGS04925.090112M. Roports5G504925 120 R1.doc Helical Piers 1, In general, manufactured helical piers are available with allowable mechanical capacities between 30 and 50 kips. Helical pier bearing capacity shall be verified in the field using manufacturer recommended capacity/torque ratios. A minimum factor of safety of 2.0 is required between ultimate and allowable capacity. 2. Contractor shall use the number and size of helical blades required to achieve the required depth, torque, and capacity. However, the ratio of allowable capacity specified by the structural engineer and the total area of helical blades (in square feet) used by the contractor shall not exceed 75,000 pounds per square foot. 3. Due to the occasional layers of gravel with potential cobble on this site, we recommend using helical piers with a dual cutting edge blade as manufactured by Magnum Piering, Inc. and installed by Hayward Baker/Denver Grouting. 4. In order to bear on the sand below the zone of probable wetting, helical piers should have a minimum length of 20 feet below final ground surface. Longer piers may be required to achieve specified installation torque. 5. Helical piers should be installed as close to vertical as possible unless a batter is required to resist lateral loads. Lateral loading conditions should be analyzed during design. 6. The helical pier cap and the connection between the pier and grade beam should be designed to resist both tension and compression. A structural engineer should design this connection. 7. Foundation walls and grade beams should be well reinforced to span between piers. A qualified structural engineer should design the reinforcement. 8. installation of helical piers should be observed by a representative of our firm to confirm the depth and installation torque of the helical piers are adequate. Footings 1. Footings foundations should be supported on the natural sand soils. Soils loosened during the forming process for the footings should be removed or re -compacted prior to placing concrete MR. ED PETROSIUS 7 PETROSIUS RESIDENCE PROJECT NO, G504925-120 S:%G504925.00MI2012. Repor:s%G504925 120 R1.doc Footings should be designed for a maximum allowable soil bearing pressure of 2,000 psf. 3. Continuous wail footings should have a minimum width of at least 20 inches. Foundations for isolated columns should have minimum dimensions of 30 inches by 30 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 recommend reinforcement sufficientto span an unsupported distance of at least'12 feet. Reinforcement should be designed by the structural engineer. 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 36 inches below finished exterior grades. The Garfield County building department should be consulted regarding required frost protection depth. FLOOR SYSTEM AND SLABS -ON -GRADE We anticipate that the owner will desire a slab -on -grade floor in the garage and in basement areas. If the soils below slabs are sub -excavated to a depth of at least 2 feet below bottom of slab elevation, moisture -treated and recompacted, we judge that the risk of slab -on -grade movement will be low. The process was described in the Structural Fill section. We judge that slabs -on -grade constructed directly on the natural sand soils will have a low to moderate risk of differential movement. Care must be taken to ensure that soils below the slabs are not wetted. We recommend the following precautions for slab -on -grade construction at this site. These precautions will not prevent movement from occurring, they tend to reduce damage if slab movement occurs. 1. Slabs should be separated from exterior walls and interior bearing members with slip joints which allow free vertical movement of the slabs. 2. Plumbing and utilities which pass through slabs should be isolated from the slab with sleeves and be constructed with flexible connections to slab supported appliances. Mai. E❑ PETROSIUS 8 PETROSIUS RESIDENCE PROJECT NO. GSO4925-120 S:YG904925.000112012. RoporlslGSO4925 120 R1.doc 3. Exterior patio and porch slabs should be isolated from the residence. These slabs should be well -reinforced to function as independent units. Movements of these slabs should not be transmitted to the residence foundation. 4. Frequent control joints should be provided, in accordance with American Concrete Institute (ACI) recommendations, to reduce problems associated with shrinkage and curling. Our experience indicates panels which are approximately square generally perform better than rectangular areas. 5. The 2003 International Building Code (IBC) or 2003 international Residential Code (IRC) may require a vapor retarder be placed between the base course or subgrade soils and the concrete slab -on -grade floors. The merits of installation of a vapor retarder below floor slabs and PT slabs depend on the sensitivity of floor coverings and building to moisture. A properly installed vapor retarder (10 mil minimum) is more beneficial below concrete slab -on -grade floors where floor coverings, painted floor surfaces or products stored on the floor will be sensitive to moisture. The vapor retarder is most effective when concrete is placed directly on top of it. A sand or gravel leveling course should not be placed between the vapor retarder and the floor slab. The placement of concrete on the vapor retarder may increase the risk of shrinkage cracking and curling. Use of concrete with reduced shrinkage characteristics including minimized water content, maximized coarse aggregate content, and reasonably low slump will reduce the risk of shrinkage cracking and curling. Considerations and recommendations for the installation of vapor retarders below concrete slabs are outlined in Section 3.2.3 of the 2003 report of American Concrete Institute (ACI) Committee 302, "Guide for Concrete Floor and Slab Construction (ACI 302.R-96)". The most positive method to mitigate potential floor movement is to construct structural floors. if the owner wishes to reduce the potential for floor movement we recommend structural floors in living areas. Structural floors are supported by the foundation system. There are design and construction issues associated with structural floors, such as deeper excavation depths, ventilation, and increased lateral load that must be considered. MR. ED PETROSIUS 9 PETROsIus RESIDENCE PROJECT NO. GSO4925-120 SAGSO4925.0001120%2. ReporWGSO4925 120 R1.doc BELOW -GRADE CONSTRUCTION Foundation and basement 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 pressure. 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 which can deflect or 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 can 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. We recommend design of below -grade walls using an equivalent fluid density of at least 50 pcf for this site. Backfill placed adjacent to foundation wall exteriors should be in accordance with the recommendations in the Backfill section. This equivalent density does not include allowances for sloping backfill, surcharges or hydrostatic pressures. The recommended equivalent density assumes deflection; some minor cracking of walls may occur. If very little wall deflection is desired, a higher equivalent fluid density may be appropriate for design. SUBSURFACE DRAINAGE Water from precipitation, snow melt and surface irrigation of landscaping frequently flows through relatively permeable backfill placed adjacent to a residence and collects on the surface of relatively undisturbed soils at the bottom of the excavation. This can cause wetting of foundation soils, hydrostatic pressures on below -grade wails, and moist or wet conditions in below -grade areas after construction. To mitigate these concerns, we recommend provision of a foundation drain around the residence. The drain should consist of a 4-inch diameter, open joint MR. ED PDTROSIUS 10 PETROSIUS RESIDENCE PROJECT NO. GSO4925-120 S:\GS04925.000112012. Reports4GSO4925 120 R1.doo BE or slotted pipe encased in free draining gravel. The drain should lead to a positive gravity outfall or to a sump pit where water can be removed by pumping. Typical foundation drain details are shown on Figures 4 and 5. The top 1 to 2 feet of backfill should consist of a clay soil to limit infiltration. Ventilation is important to maintain acceptable humidity levels in crawl spaces. The mechanical systems should consider the humidity and temperature of air, and air flow volumes during design of crawl space ventilation systems. We believe it is appropriate to install a ventilation system that is controlled by a humidistat. SURFACE DRAINAGE Surface drainage is critical to the performance of foundations, floor slabs and concrete flatwork. 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 building in all directions. We recommend providing a slope of at least 6 inches in the first 5 feet in landscaped areas around the building. 2. Backfill adjacent to foundation wall exteriors should be placed and compacted as described in the Fill and Backfill section. 3. The residence should be provided with gutters and downspouts. Roof downspouts and drains should discharge well beyond the limits of all backfill. Splash blocks and downspout extensions should be provided at all discharge points. Water from roof and surface runoff should not be introduced to the foundation drain system. 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 or other landscaping requiring comparatively large amounts of irrigation should not be located within 5 feet of the foundation. Sprinklers should be at least 5 feet from building foundations and directed away from the building. Irrigation should be limited to the minimum amount sufficient to maintain vegetation; the application of additional water will increase the likelihood of slab and foundation movements. MR. ED PETROSIUS PETROSIUS RESIDENCE PROJECT NO. G504925.120 S:IGSO4925.000112012. Reporls%GSO4925 120 R1.doo 5. Impervious plastic membranes should not be used to coverthe ground surface immediately surrounding the building. 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. LIMITATIONS Our exploratory borings were spaced to obtain a reasonably accurate picture of the subsurface. Variations in the subsurface conditions not indicated by our exploratory borings will occur. We should observe and test structural fill placement and observe installation of helical piers. This investigation was conducted in a manner consistentwith 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 implied, is made. If we can be of further service or if you have questions regarding this report, please call. CTL I THOMPSON, INC. /-7 Craig A. Burgej Project Pngin0 �11 J oh\n B ra ni CAB: d by Wing, P.E. Aanaqer (5 copies sent) MR. ED PETROSIUS 12 PETROSIUS RESIDENCE PROJECT NO. GSO4925.120 SAGSO4925.000112012. Rcpor[s%GSO4925 120 R1.doc SCAM: 1 °= IOU Ed PetrnSIUS L,ut 30, cease Ranch Project No. GSO4925-120 Approximate Locations of Exploratory Borings Fig. 1 TH-1 TH-2 ELW6455 EL= 6445 6455 6445 IV m 27/12 F— 6440 0 Ed 6435 25/12 6430 6425 1/-" 50/0 6420 Project No. GS04925-120 SUMMARY LO 455 450 445 5440 i435 5430 6425 6420 a 0 a s m LEGEND: Silty sand "topsoil", medium stiff, moist, dark ® brown. Sand, silty, gravel, occasional cobbles, boulders, loose to dense, slightly moist, brown. (SM—GM) Drive sample. The symbol 10/12 Indicates that 10 blows of a 140 pound hammer falling 30 Inches were required to drive a 2.5 inch O.D. California sampler 12 Inches. Drive sample. The symbol 25/12 Indicates that 25 blows of a 140 pound hammer falling 30 Inches were required to drive a 2.0 inch O.D. standard sampler 12 inches. Indicates practical auger refusal. NOTES: 1. Exploratory borings were drilled on January 16, 2007 with 4—inch diameter, solid —stem auger w and a track —mounted drill rig. PVC pipeas installed in TH-1 to facilitate future measurements of ground water levels. Exploratory boring TH-2 was backfilled immediately 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. 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I I I [ 1 1 1 1 1 I I I I I 1 f 1 I I 7_—__r__,__T-I-T'rTr-------r----I---r--1--r-1--r-rr-------T--- _r«_1__T_-1_T—I» i I I I 1 I 1 I I I I I I I 1 1 I { I I I I I I 1 I I I I I I 1 I I I l 1 I I 1 a I 1 1 I I I I I I I I I I I I I 1 I I I k 1 I I 1 ! I 1 1 I I I I I 1 I I I I I 1 I I I I 1 I I I I 1 ! I I 1 I I I 1 1 I 0.1 1.0 10 1uu APPLIED PRESSURE - KSF Sample of SAND, SILTY (SM) NATURAL DRY UNIT WEIGHT= 108 PCF From Tf-l-1 AT 14 FEET NATURAL MOISTURE CONTENT= 8.3 % SwO C®nsoflda on PROJECT NO. GSO4925-120 Test Results FIG.3 NOTE: DRAIN SHOULD BE AT LEAST 2 INCHES SLOPE BELOW BOTTOM OF FOOTING AT THE PER REPORT HIGHEST POINT AND SLOPE DOWNWARD TO A POSITIVE GRAVITY OUTLET OR TO A SUMP WHERE WATER CAN BE REMOVED BY PUMPING. BACKFILL (COMPOSITION ANn COMPACT]ON PER REPORT) 1 BELOW GRADE WALL ENCASE PIPE IN WASHED REINFORCING STEEL PER STRUCTURAL SLOPE CONCRETE AGGREGATE (ASTM DRAWINGS PER OSHA C33, NO. 57 OR NO. 67) EXTEND GRAVEL TO AT LEAST 1 /2 HEIGHT OF FOOTING. PROVIDE POSITIVE SLIP JOINT BETWEEN SLAB AND WALL. .......... FLOOR SLAB COVER GRAVEL WITH FILTER FABRIC. ........ FOOTING OR PAD :. 2" MINIMUM ---PROVIDE POLYETHYLENE 51O"" SHEETING GLUED TO EXTEND POLYETHYLENE FOUNDATION WALL TO UP TO TOP ELEVATION REDUCE MOISTURE OF DRAIN PIPE. g" MINIMUM PENETRATION OR BEYOND 1:1 SLOPE FROM BOTTOM OF FOOTING. (WHICHEVER IS GREATER) 4-INCH DIAMETER PERFORATED DRAIN PIPE. THE PIPE SHOULD BE LAID IN A TRENCH WITH A MINIMUM SLOPE OF 0.5 PERCENT. Exterior Foundation all ®rain Fig. 4 Project No. G804925-120 SLOPE PER REPORT BELOW GRADE WALL SLOPE PER OSHA ENCASE PIPE IN WASHED CONCRETE AGGREGATE (ASTM C33, NO. 57 OR NO. 67) EXTEND GRAVEL TO AT LEAST 1 /2 HEIGHT OF FOOTING. --_ EXTEND POLYETHYLENE UP TO TOP ELEVATION OF DRAIN PIPE. Project No. GSO4925-120 BACKFILL (COMPOSITION AND COMPACTION PER REPORT) COVER GRAVEL WITH FILTER FABRIC SUPPORTED 2" MINIMUM 8" MINIMUM I-�- OR BEYOND 1:1 SLOPE FROM BOTTOM OF FOOTING. (WHICHEVER IS GREATER) 4-INCH DIAMETER PERFORATED DRAIN PIPE. THE PIPE SHOULD BE PLACED IN A TRENCH WITH A SLOPE RANGE BETWEEN 1 /8 INCH AND 1/4 INCH DROP PER FOOT OF DRAIN. PROVIDE POLYETHYLENE SHEETING GLUED TO FOUNDATION WALL TO REDUCE MOISTURE PENETRATION. - REINFORCED STEEL PER STRUCTURAL DRAWINGS CRAWL SPACE-) FOOTING OR PAD BOTTOM OF EXCAVATION 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. Exterior Foundation Wall Drain Fig. 5