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HomeMy WebLinkAbout5554 W. 27th Avenueiµ neasga BaMAr Valvae Prrims Sewage BaMlmv. a,here IN $balI lmElevelrl of Mplull mum cel ere heeare upstream n W Ne maMdemve dmenee fee, me nlanmlammapuha am". the lihaws allb ll InrtKCMbye Wcnch of ebullarmin meripporgErvin. brats dmebwlamgtramnbob:mdl brats sm"lesuch shares, Plumbing thenalJON level nmmeryeINNlnsverof the hall roverM me Nur spencers shall act manhole in megha leevrertairaml discharge Mmigb a betltwelervLve. Lud n DQpD0I1�fNs es ASO F. iUC'.FO :OP9: i 36623 i g9o�5�2��,'�¢ SSS/ONALEHG\� PROJECT: FREEDMAN RESIDENCE TEEG, INC. PROJECT No: ADDRI 5554 W. 27th Ave. i Wheat Ridge, CO 20 Quell R Bldg 600, On@ 211 Denver, P R e Q 1 9 Colorado 80230 ph: 303.321-OBID CLIENT: Chad Freedman email: dave@tmeglnc.com tlud.freedman@gmail.corn PROJECT NO: 21-103 Colorado Geoscience & Design, Inc. P.O. Box 68 FFankown, Colorado Bonn • Phone: 303.688.2v5o • Fax: 303.688.=95 • COGeoDengn.Com Thirty Two Development 1615 Platte Street, and Floor Denver, CO 80202 SUBSURFACE INVESTIGATION OF 5554 WEST 27rod AVENUE WEST LOT JEFFERSON COUNTY, COLORADO REPORT NO. 21-369 July 16, 2021 Revised October 20, 2021 Revised December 15, 2021 NOTVALIDIVITHOOT ORIGINALSIGNATURB GEOTECHNICAL STRUCTUPAL CIVIL ENGINEERS TABLE OF CONTENTS General Site Conditions Field and Laboratory Investigation Foundation Recommendations Criteria for Concrete Slab on Grade Construction Placement of Structural Fill Placement of Foundation Fill Subsurface Drainage Surface Drainage Foundation Excavation Radon Gas General Information Location Map Log of Test Holes Swell / Consolidation Charts Summary of Laboratory Testing Details of Foundation Drain System Foundation Grading Detail Appendix 1 1 i 2 4 6 7 7 7 8 8 9 Figure 1 Figure 2 Figure 3 Table 1 Detail 1 Detail 2 Information about the Report W he, Y u{° Thifty 0Davelopme„ TInc Twp ire. 21-30 9 Colpretlo Geoederm antl Desgn, Ino- RepaM1 No. 21-308 GENERAL This report presents the results of data obtained during the subsurface investigation at 5554 WEST 27TH AVENUE, WEST LOT, JEFFERSON COUNTY, COLORADO. This investigation was made to determine the type of foundation required, allowable bearing capacity, and groundwater conditions encountered at the time of the field investigation. SITE CONDITIONS At the present time there is an existing single -family residence located at this site. It is our understanding a single -family residence with a basement attached garage is planned for this site. The proposed structure will consist of wood framed construction with a steel reinforced concrete foundation. We anticipate the foundation loads to range from 1,000 to 2,500 pounds per linear foot of foundation wall. The general topography of the site slopes approximately 2% to the south. The vegetation at the site consists of native trees, grass, and weeds. The weather was warm and clear at the time of the investigation. If the type of construction changes from that specified above, please contact this office for additional recommendations and/or requirements. FIELD AND LABORATORY INVESTIGATION One (1) exploratory test hole (B1) was drilled for the single -family residence and one (1) exploratory test hole (62) for the attached garage on June 30, 2021, at the site shown on the Location Map. The test holes were drilled with a four-inch (4") diameter auger advanced with a CME-45 soil exploration drill rig. At specific intervals, the drilling tools were removed from the test holes and soil samples were obtained with a two-inch (T') diameter spoon sampling tube. The depths at which soil samples were taken and a description of the soil encountered are shown on the Log of Test Holes, Figure 2, and the Summary of Laboratory Testing, Table 1. All soil samples were carefully observed in the field during the drilling operation. These samples were classified in the laboratory through visual observation and laboratory testing to determine the pertinent properties. The natural moisture content and dry density was obtained from relatively undisturbed drive samples of typical soils. Swell- consolidation tests were performed on typical soil samples see Figure 3. These tests indicate the behavior of the soil upon various loadings in a wetted condition. Groundwater was encountered at a depth of 15 feet in 81 at the time of the field Investigation. When checked later, groundwater was encountered at a depth of 12.5 feet in B1 and 13 fest in B2. B1 caved to 14 feet and B2 caved to 14.5 feet. These observations represent the groundwater conditions at the time of drilling or December 15, 2021 1 measurement and may not be indicative of the conditions at other times. Groundwater levels can be expected to fluctuate with varying seasonal weather conditions and if the sites use irrigation for lawns. Site soil conditions encountered may appear different from the test borings as presented in this report. An excavation observation is required and must be performed by a representative of this office to verify existing soil conditions, and the proposed design bearing pressure. The excavation observation must be performed only after the entire building footprint has been excavated to the bottom of bearing elevation. In addition, it may be necessary to revise our foundation recommendations based upon results of the excavation. Failure to follow the observation requirements noted herein may jeopardize the success of this construction project and Colorado Geoscience and Design Inc. shall be absolved from any and all responsibility for any damages arising from the failure to obtain proper site observations. If an individual or contractor performs an open -hole or site observation or disregards the foundation recommendations cited herein, other than those provided by Colorado Geoscience and Design, Inc.'s, or that which has been approved by the local building officials, that individual or contractor will assume all liability for using this subsurface investigation and its relevant construction recommendations. FOUNDATION RECOMMENDATIONS Based on our evaluation of the subsurface conditions, we recommend the proposed single-family residence be founded on drilled piers and grade beams or continuous concrete footings and pads. A professional engineer should use the following design criteria to design the foundations. 1. Piers shall be a minimum 10 -inch diameter. 2. Piers shall be a minimum of 24 feet deep embedded 5 -feet into the claystone bedrock. 3. Piers shall be designed for a maximum end bearing capacity of 12,500 pounds per square foot. 4. Side shear resistance of 1,250 pounds per square foot for the 5 -foot portion of the pier embedded into the claystone bedrock. 5. Piers shall be designed for a minimum dead load of 3,500 pounds per square foot to resist uplift. If the minimum dead load pressure cannot be met, the pier length should be increased to offset any dead load deficiency. December 15, 2021 u_e{° �,}m Strinr ace lnnodgabon Th'Ny Two Developmern 9 Colorado GeoSOi¢nce and Deal Inc. Report No. 21-368 measurement and may not be indicative of the conditions at other times. Groundwater levels can be expected to fluctuate with varying seasonal weather conditions and if the sites use irrigation for lawns. Site soil conditions encountered may appear different from the test borings as presented in this report. An excavation observation is required and must be performed by a representative of this office to verify existing soil conditions, and the proposed design bearing pressure. The excavation observation must be performed only after the entire building footprint has been excavated to the bottom of bearing elevation. In addition, it may be necessary to revise our foundation recommendations based upon results of the excavation. Failure to follow the observation requirements noted herein may jeopardize the success of this construction project and Colorado Geoscience and Design Inc. shall be absolved from any and all responsibility for any damages arising from the failure to obtain proper site observations. If an individual or contractor performs an open -hole or site observation or disregards the foundation recommendations cited herein, other than those provided by Colorado Geoscience and Design, Inc.'s, or that which has been approved by the local building officials, that individual or contractor will assume all liability for using this subsurface investigation and its relevant construction recommendations. FOUNDATION RECOMMENDATIONS Based on our evaluation of the subsurface conditions, we recommend the proposed single-family residence be founded on drilled piers and grade beams or continuous concrete footings and pads. A professional engineer should use the following design criteria to design the foundations. 1. Piers shall be a minimum 10 -inch diameter. 2. Piers shall be a minimum of 24 feet deep embedded 5 -feet into the claystone bedrock. 3. Piers shall be designed for a maximum end bearing capacity of 12,500 pounds per square foot. 4. Side shear resistance of 1,250 pounds per square foot for the 5 -foot portion of the pier embedded into the claystone bedrock. 5. Piers shall be designed for a minimum dead load of 3,500 pounds per square foot to resist uplift. If the minimum dead load pressure cannot be met, the pier length should be increased to offset any dead load deficiency. December 15, 2021 6. All piers shall be reinforced their full length with steel rebar. The pier reinforcing shall be designed to resist the tension resulting from the maximum uplift pressures. No less than 1% of steel based on the pier end area shall be used. The pier reinforcing steel shall extend into the foundation wall a sufficient distance to fully develop the bars in tension. 7. The recommended diameter must be maintained at the top of each pier hole. We recommend forming the top portion of the pier with cylindrical cardboard forms to prevent mushrooming 8. The drilled pier holes shall be cleaned of all loose material and filled immediately with concrete to prevent sloughing of loose soil or infiltration of water. 9. The foundation walls shall be designed for an active horizontal pressure based on an equivalent fluid density of 40 pounds per cubic foot plus any applicable surcharge or hydrostatic loads and shall be designed to distribute the applied loads between piers. 10.A void form of a minimum of four inches (4") shall be placed under the foundation grade beam walls between the drilled piers. 11.If water is present in the drilled pier hole, the concrete shall be pumped or tremmied to the bottom of the pier to displace the water. ALTERNATE FOUNDATION RECOMMENDATION: An alternate and satisfactory foundation recommendation for the proposed single-family residence would be continuous concrete footings and pads. A professional engineer should use the following design criteria to design the foundations. 1. The footings and pads shall be designed for a maximum soil bearing pressure of 1,000 pounds per square foot (DL+LL). The entire basement foundation shall bear on 3 -feet of structural fill and 3 -feet above the groundwater. (See "Placement of Structural Fill'). 2. No footing or pad shall bear upon topsoil or soils that contain organic material. All loose and disturbed soil shall be removed before pouring the concrete for the footings or bearing pads. 3. All continuous footings supporting perimeter concrete foundation walls shall be at least 16 inches wide. We recommend footings be reinforced to bridge isolated soft areas up to 10 feet. Exterior footings should be provided with at least 3 -feet of soil cover for frost protection, or per county codes. 4. The foundation walls shall be designed for an active horizontal pressure based on an equivalent fluid density of 40 pounds per cubic foot plus any applicable surcharge or hydrostatic loads. December 15, 2021 3 W he, m sublimates mvestemion mimy Two Development Cobrado Geoscence and Design, Inc. Report No. 01369 6. All piers shall be reinforced their full length with steel rebar. The pier reinforcing shall be designed to resist the tension resulting from the maximum uplift pressures. No less than 1% of steel based on the pier end area shall be used. The pier reinforcing steel shall extend into the foundation wall a sufficient distance to fully develop the bars in tension. 7. The recommended diameter must be maintained at the top of each pier hole. We recommend forming the top portion of the pier with cylindrical cardboard forms to prevent mushrooming 8. The drilled pier holes shall be cleaned of all loose material and filled immediately with concrete to prevent sloughing of loose soil or infiltration of water. 9. The foundation walls shall be designed for an active horizontal pressure based on an equivalent fluid density of 40 pounds per cubic foot plus any applicable surcharge or hydrostatic loads and shall be designed to distribute the applied loads between piers. 10.A void form of a minimum of four inches (4") shall be placed under the foundation grade beam walls between the drilled piers. 11.If water is present in the drilled pier hole, the concrete shall be pumped or tremmied to the bottom of the pier to displace the water. ALTERNATE FOUNDATION RECOMMENDATION: An alternate and satisfactory foundation recommendation for the proposed single-family residence would be continuous concrete footings and pads. A professional engineer should use the following design criteria to design the foundations. 1. The footings and pads shall be designed for a maximum soil bearing pressure of 1,000 pounds per square foot (DL+LL). The entire basement foundation shall bear on 3 -feet of structural fill and 3 -feet above the groundwater. (See "Placement of Structural Fill'). 2. No footing or pad shall bear upon topsoil or soils that contain organic material. All loose and disturbed soil shall be removed before pouring the concrete for the footings or bearing pads. 3. All continuous footings supporting perimeter concrete foundation walls shall be at least 16 inches wide. We recommend footings be reinforced to bridge isolated soft areas up to 10 feet. Exterior footings should be provided with at least 3 -feet of soil cover for frost protection, or per county codes. 4. The foundation walls shall be designed for an active horizontal pressure based on an equivalent fluid density of 40 pounds per cubic foot plus any applicable surcharge or hydrostatic loads. December 15, 2021 3 5. In place structural settlements are very difficult to predict with any reasonable accuracy, due to the large number of variable geotechnical parameters involved. However, based upon the currently available methods of settlement prediction, it is estimated that total structural settlement will be on the order of 1" and differential structural settlement will be on the order of W. CRITERIA FOR SLAB -ON -GRADE CONSTRUCTION Virtually all concrete slabs undergo some type of movement. Concrete slabs placed on soils comprised of medium dense or dense granular material or comprised of sof[ or stiff clays with swell potential less than 1% under a 1000 Ib surcharge is considered unlikely to sustain intolerable movement by standard engineering practice. Cracking of slabs -on -grade is difficult to control and should be expected to occur with time. Cracking may be the result of many factors such as concrete shrinkage and daily and seasonal variability in temperature and humidity and not necessarily the result of soil movement. Further, cracks and movement of slabs -on -grade can be transmitted through rigid floor coverings such as ceramic tile. Performance expectations should be taken into consideration in the selection of floor slab coverings. If floor coverings or coatings less permeable than the concrete slab are used, or if moisture is a concern, we recommend a vapor retarder be placed beneath the slab. Flooring installation should be consistent with the flooring manufacturer's recommendations for subsoil and slab construction and moisture testing prior to installation. A chanoe in water content in soils is a major contributor to slab movement Colorado Geoscience and Design recommends that steps be taken to reduce the possibility of intolerable concrete slab movement due to changes in water content. Properly landscaped yards, drainage from the foundation walls, and the installation of perimeter and/or under slab drainage systems are ways to mitigate changes in the water content of the indigenous soils (See "Surface Drainage"). A slab performance risk evaluation was conducted in general compliance with industry guidelines for the local area. The risk assessment of a site for potential movement is not absolute; rather, it represents a judgment based upon the data available and our experience in the area. Movement of foundations and concrete flat work will occur over time in low to very high risk areas as the soil moisture content increases. On low and moderate rated sites, slab movements of up to 3 inches across the slab with cracking of up to % inch in width and/or differential are not unusual. The damage generally increases as the risk assessment increases and as the depth of wetting increases. It must be understood, however, that assessing risk is an opinion, and the prediction of heave is not an exact science. Therefore, it may be possible that heave less than or in excess of what is described herein may be experienced. This risk should be communicated to the subsequent homebuyer. We recommend the owner or December 15, 2021 4 W he, " y SudsuNece lnvestlgadon q Thirty Two Development '% ou' Colorado Gwsol nc and Deslgn lw Report No. 21-389 5. In place structural settlements are very difficult to predict with any reasonable accuracy, due to the large number of variable geotechnical parameters involved. However, based upon the currently available methods of settlement prediction, it is estimated that total structural settlement will be on the order of 1" and differential structural settlement will be on the order of W. CRITERIA FOR SLAB -ON -GRADE CONSTRUCTION Virtually all concrete slabs undergo some type of movement. Concrete slabs placed on soils comprised of medium dense or dense granular material or comprised of sof[ or stiff clays with swell potential less than 1% under a 1000 Ib surcharge is considered unlikely to sustain intolerable movement by standard engineering practice. Cracking of slabs -on -grade is difficult to control and should be expected to occur with time. Cracking may be the result of many factors such as concrete shrinkage and daily and seasonal variability in temperature and humidity and not necessarily the result of soil movement. Further, cracks and movement of slabs -on -grade can be transmitted through rigid floor coverings such as ceramic tile. Performance expectations should be taken into consideration in the selection of floor slab coverings. If floor coverings or coatings less permeable than the concrete slab are used, or if moisture is a concern, we recommend a vapor retarder be placed beneath the slab. Flooring installation should be consistent with the flooring manufacturer's recommendations for subsoil and slab construction and moisture testing prior to installation. A chanoe in water content in soils is a major contributor to slab movement Colorado Geoscience and Design recommends that steps be taken to reduce the possibility of intolerable concrete slab movement due to changes in water content. Properly landscaped yards, drainage from the foundation walls, and the installation of perimeter and/or under slab drainage systems are ways to mitigate changes in the water content of the indigenous soils (See "Surface Drainage"). A slab performance risk evaluation was conducted in general compliance with industry guidelines for the local area. The risk assessment of a site for potential movement is not absolute; rather, it represents a judgment based upon the data available and our experience in the area. Movement of foundations and concrete flat work will occur over time in low to very high risk areas as the soil moisture content increases. On low and moderate rated sites, slab movements of up to 3 inches across the slab with cracking of up to % inch in width and/or differential are not unusual. The damage generally increases as the risk assessment increases and as the depth of wetting increases. It must be understood, however, that assessing risk is an opinion, and the prediction of heave is not an exact science. Therefore, it may be possible that heave less than or in excess of what is described herein may be experienced. This risk should be communicated to the subsequent homebuyer. We recommend the owner or December 15, 2021 4 prospective buyer review "A Guide to Swelling Soils for Colorado Homebuyers and Homeowners", which is a special publication produced (SP43) by the Colorado Geological Survey to assist homeowners in reducing damage caused by swelling soils. Swell Potential Chart Slab Performance Risk Category Representative Percent Swell (1,000 psf Surcharge) Low u{° Moderate 2 to <4 subsurface Investigation 4 to <6 Thirty Two nnelcpmem 'T^aoM' Colorado Geosdence and Desgn, Inc. Report No. 21-369 prospective buyer review "A Guide to Swelling Soils for Colorado Homebuyers and Homeowners", which is a special publication produced (SP43) by the Colorado Geological Survey to assist homeowners in reducing damage caused by swelling soils. Swell Potential Chart Slab Performance Risk Category Representative Percent Swell (1,000 psf Surcharge) Low 0 to <2 Moderate 2 to <4 High 4 to <6 Very High a6 Note: the representative percent swell values presented are not necessarily measured values: rather, they are a judgment of the swell of the soil and bedrock profile likely to influence slab performance. The swell potential of the indigenous soils for the residence at this site meets the criteria for low risk of slab -on -grade movement. Concrete slabs may be used for basement slabs, garage slabs and exterior surface (sidewalks, patios, and aprons) placed on the native soil. Furthermore, intolerable movement of any slab on grade may occur at the site as a result of future factors beyond the control of Colorado Geoscience and Design, Inc. If differential slab -on -grade movement is not acceptable to the owner/builder, and if the owner/builder is unwilling to accept the risk of differential slab -on -grade movement, a structural Floor above a crawl space is required in the basement. The owner/builder shall be cautioned that problems with mold may arise when floors are built over a crawl space or with a structural floor. In order to prevent such problems, it may be necessary to take specific actions to mitigate the potential for molds, such as installing actively controlled humidistat systems and devices, providing adequate ventilation of enclosed spaces below the floor, and/or treatment of the soils with anti - mold, anti -fungal chemical agents. Colorado Geoscience and Design, Inc. will not be responsible for any and all claims arising from issues of mold or fungal contamination. It is the builder's responsibility to adequately address these issues during construction. If the owner/builder accepts the risk of slab -on -grade movement and chooses a slab -on - grade floor, the following steps shall be part of the concrete slab design: • Any soil disturbed during construction shall be compacted by use of a vibratory plate in the case of loose granular soils or wheel rolled by heavy equipment in the case of soft clay or silt soils prior to placement of the concrete slab. • The soil should be kept moist but not wet during the compaction process as well as immediately prior to the placement of the concrete slab directly onto the soil. Steps shall be taken to ensure that subsurface moisture beneath the concrete slab remains constant during the construction process. December 15, 2021 • The concrete slab shall be structurally isolated from all foundations and shall be isolated from penetrations by suitable expansion material not less than %" thick. The floating concrete slab shall be completely isolated from all utility lines. • Control joints shall be provided in the concrete slab. These control joints must be saw out or tooled to a minimum of one third of the thickness of the slab. No portion of the concrete slab will have an area greater than neither 100 square feet nor a maximum dimension of 12'-0" in any direction without a control joint. • All non-bearing partition walls shall be constructed with a minimum of 3 inches of float to allow for slab -on -grade movement. • If a hot water heating system is used, the piping may be cast within the concrete slab if the slab is reinforced with steel rebar and special care is taken not to damage the piping during future construction activities. Nails shall not be driven into a concrete slab that has hot water piping. Base plates should be attached with construction adhesive or anchor bolts cast in the concrete slab at the time of placement. • If a forced air furnace is used, a 2" flexible connection should be installed between the furnace and the duct. PLACEMENT OF STRUCTURAL FILL Where structural fill placement is required, the following requirements shall be followed. The entire basement foundation shall be over -excavated 3 -feet below the bottom of the footings and pads and 4 feet in all directions beyond the footprint of the foundation. The structural fill material shall consist of non -expansive soil free of deleterious material (organic, frozen of other unsuitable material) and rocks greater than 3" in diameter. The fill material should be compacted in lifts not to exceed 8 inches after compaction, while maintaining a minimum of 95% of its maximum standard Proctor dry density (ASTM D-898). Non -cohesive soils (sand) shall be placed at t2% of the optimum moisture content and cohesive soils (clay) shall be placed at +3% to —1% of optimum moisture content. A Standard or Modified Proctor Curve (whichever is applicable) by Colorado Geoscience and Design, Inc. or an approved testing firm is required. An excavation observation and soil density test is required and shall be performed by a representative of Colorado Geoscience and Design, Inc. to verify soil conditions, the depth of excavation, and quality of the compacted soil prior to the placement of the footings and pads. The fees for these tests are not included in the cost of the subsurface investigation. December 15, 2021 g W he, u{° s mlpaesuppnon Iny mint ThRepon Colorado Gemdence and Design, Incro. Report No. 21388 No.. 21mle • The concrete slab shall be structurally isolated from all foundations and shall be isolated from penetrations by suitable expansion material not less than %" thick. The floating concrete slab shall be completely isolated from all utility lines. • Control joints shall be provided in the concrete slab. These control joints must be saw out or tooled to a minimum of one third of the thickness of the slab. No portion of the concrete slab will have an area greater than neither 100 square feet nor a maximum dimension of 12'-0" in any direction without a control joint. • All non-bearing partition walls shall be constructed with a minimum of 3 inches of float to allow for slab -on -grade movement. • If a hot water heating system is used, the piping may be cast within the concrete slab if the slab is reinforced with steel rebar and special care is taken not to damage the piping during future construction activities. Nails shall not be driven into a concrete slab that has hot water piping. Base plates should be attached with construction adhesive or anchor bolts cast in the concrete slab at the time of placement. • If a forced air furnace is used, a 2" flexible connection should be installed between the furnace and the duct. PLACEMENT OF STRUCTURAL FILL Where structural fill placement is required, the following requirements shall be followed. The entire basement foundation shall be over -excavated 3 -feet below the bottom of the footings and pads and 4 feet in all directions beyond the footprint of the foundation. The structural fill material shall consist of non -expansive soil free of deleterious material (organic, frozen of other unsuitable material) and rocks greater than 3" in diameter. The fill material should be compacted in lifts not to exceed 8 inches after compaction, while maintaining a minimum of 95% of its maximum standard Proctor dry density (ASTM D-898). Non -cohesive soils (sand) shall be placed at t2% of the optimum moisture content and cohesive soils (clay) shall be placed at +3% to —1% of optimum moisture content. A Standard or Modified Proctor Curve (whichever is applicable) by Colorado Geoscience and Design, Inc. or an approved testing firm is required. An excavation observation and soil density test is required and shall be performed by a representative of Colorado Geoscience and Design, Inc. to verify soil conditions, the depth of excavation, and quality of the compacted soil prior to the placement of the footings and pads. The fees for these tests are not included in the cost of the subsurface investigation. December 15, 2021 g ,W nea� Subaudace lnveetgatlon Tbidy Two Development Colorado Geosebnce and Deegn, Inc. Repoli No, 21-368 PLACEMENT OF FOUNDATION FILL Expansive soil is not suitable for backfill material adjacent to the foundation backfill or for retaining walls. Any sail disturbed or imported material adjacent to the foundation walls shall be re-compacted to a minimum of 90% of Standard Proctor Density, ASTM D-698. Compaction of each lift adjacent to walls should be accomplished with hand-operated tampers or other lightweight compactors. Over compaction may cause excessive lateral earth pressure, which could result in wall movement. No water flooding techniques should be used in the compaction of backfill. SUBSURFACE DRAINAGE The installation of an exterior foundation perimeter drainage system is required for any habitable space below grade level. See Perimeter Drain Detail 1, for a suggested method of installing this system. The perimeter drain shall discharge at a daylight location a minimum of 15-feet away from the home. The daylight end shall have a screened end section to prevent rodents from entering the drain. Alternatively, the perimeter drain may discharge into a sump pit with a sump pump. If a sump pit is used, homeowners should perform routine observations of the sump pump system to make sure it remains in good working order. Failure to install and failure of a sump pump system can cause serious foundation problems. Water accumulation around foundation elements is the major cause of foundation stress, therefore proper installation of the perimeter drain is very important. SURFACE DRAINAGE The backfill soil around the foundations should be moistened and well-compacted in 12- inch maximum lifts with hand operated mechanical compaction equipment to prevent future settling. Controlled puddling of the backfill soils is not allowed. She grading is critical. A simple means of reducing moisture change to prevent water infiltration into the soil is to slope the ground away from the foundation. For proper drainage, a slope of 10% (1' in 10) away from the foundations in all directions is required. This slope must be maintained for a minimum distance of 10'-0". The property owner should inspect the area around the foundation regularly particularly after rainstorms to determine if proper drainage away from the structure has been maintained. The owners are advised to immediately fill in any settled area near the foundations to eliminate containment of water. Roof drainage should include gutters, downspouts, extensions, and splash blocks. Down spouts must discharge onto concrete splash blocks or into metal gutter extensions at least 6 feet away from the foundation walls and beyond any backfill zones directing water away from the foundation. December 15, 2021 7 The owners should be cautioned regarding the installation of a lawn adjacent to the foundation walls. Lawn irrigation must be more than five feet (5') from the foundation walls to prevent wetting of the subsurface soils. Lawn and/or plants should not be planted within five feet (5') of the foundation walls. We recommend providing decorative gravel or bark around the foundations, as shown in Foundation Grading Detail 2. This method will prevent ponding of water and provide for proper drainage from the foundations. Non -woven geo textile fabric can be placed under the mulch to reduce weed growth and still allow some evaporation of soil moisture. Sprinkler heads and emitters should not be located or spray within 5 feet of the foundation or patio slabs and beyond backfill zones. Plantings near the foundations should not trap surface runoff. Furthermore, sidewalks or low-water consumption groundcover are recommended to further reduce the risk of water infiltration near the foundation walls. All pressurized irrigation lines and valve boxes should be located at least 10 feet from the foundation or patio slabs. Buried rain gutter discharge pipes are not recommended because of often undetected seepage problems caused by clogging, crushing and adverse grading of the pipes. Similarly, infiltration basins are not recommended adjacent to or upgrade of adjacent structures. If detention is required by statute, infiltration basins should be located down gradient and at least 30 feet from foundations. Changes in site grading by landscapers or property owners can have damaging effects on foundations and concrete basement and garage slabs -on -grade. It is the property owner's responsibility to control water and maintain the site to prevent infiltration near foundations. Additionally, it is the property owner's responsibility to maintain downspouts and buried sprinkler system conduits. FOUNDATION EXCAVATION Precautions should be taken in deep excavations for safety of workers and to protect nearby structures. The sides of the temporary excavations should be sloped or benched per OSHA excavation requirements. Spoils from the excavation should not be placed within 2 feet of the excavation sidewalls and the excavation should not be subject to excess vibration wetting or drying. It is the owner/contractor responsibility to be familiar with the OSHA Safety and Health Standards for the Construction Industry, 29 CFR Part 1926, or the appropriate foundation chapters of the International Building Code prior to construction. RADON GAS Most counties in Colorado have average radon levels (measured in homes) above the U.S. EPA recommended level of 4 PicoCuries per liter of air (pCi/q. Results of a 1987- 1988 EPA -supported radon study for Colorado indicated that granitic rocks, in particular, generally have elevated levels of uranium. December 15, 2021 8 W he, Sumudece Investgationy Tbi ty Two Development le Mn' Colorado Decadence and Despn. Inc. Report No. 21.159 The owners should be cautioned regarding the installation of a lawn adjacent to the foundation walls. Lawn irrigation must be more than five feet (5') from the foundation walls to prevent wetting of the subsurface soils. Lawn and/or plants should not be planted within five feet (5') of the foundation walls. We recommend providing decorative gravel or bark around the foundations, as shown in Foundation Grading Detail 2. This method will prevent ponding of water and provide for proper drainage from the foundations. Non -woven geo textile fabric can be placed under the mulch to reduce weed growth and still allow some evaporation of soil moisture. Sprinkler heads and emitters should not be located or spray within 5 feet of the foundation or patio slabs and beyond backfill zones. Plantings near the foundations should not trap surface runoff. Furthermore, sidewalks or low-water consumption groundcover are recommended to further reduce the risk of water infiltration near the foundation walls. All pressurized irrigation lines and valve boxes should be located at least 10 feet from the foundation or patio slabs. Buried rain gutter discharge pipes are not recommended because of often undetected seepage problems caused by clogging, crushing and adverse grading of the pipes. Similarly, infiltration basins are not recommended adjacent to or upgrade of adjacent structures. If detention is required by statute, infiltration basins should be located down gradient and at least 30 feet from foundations. Changes in site grading by landscapers or property owners can have damaging effects on foundations and concrete basement and garage slabs -on -grade. It is the property owner's responsibility to control water and maintain the site to prevent infiltration near foundations. Additionally, it is the property owner's responsibility to maintain downspouts and buried sprinkler system conduits. FOUNDATION EXCAVATION Precautions should be taken in deep excavations for safety of workers and to protect nearby structures. The sides of the temporary excavations should be sloped or benched per OSHA excavation requirements. Spoils from the excavation should not be placed within 2 feet of the excavation sidewalls and the excavation should not be subject to excess vibration wetting or drying. It is the owner/contractor responsibility to be familiar with the OSHA Safety and Health Standards for the Construction Industry, 29 CFR Part 1926, or the appropriate foundation chapters of the International Building Code prior to construction. RADON GAS Most counties in Colorado have average radon levels (measured in homes) above the U.S. EPA recommended level of 4 PicoCuries per liter of air (pCi/q. Results of a 1987- 1988 EPA -supported radon study for Colorado indicated that granitic rocks, in particular, generally have elevated levels of uranium. December 15, 2021 8 Radon tends to accumulate in poorly ventilated areas below ground level and can accumulate in above grade construction as well. Providing increased ventilation of basements and crawl spaces and sealing of the joints can mitigate build-up of radon gas. This mitigation is best implemented during the design and construction phase of the residence. The Colorado Geologic Survey and the U.S. EPA are both good sources for additional information regarding radon. GENERAL INFORMATION Based on this subsurface investigation, the proposed foundations appear to be technically feasible to be constructed at the proposed site. The structures should be designed for construction in the direct vicinity of the boring location. If the proposed locations change, additional borings will be required to assess the soil conditions at the new location. Permitting work will be required to obtain any local and state approval, and design work will need to be performed by a qualified professional engineer to bring this project into final design, and subsequent construction. A qualified contractor experienced with similar projects should carry out the construction of this project. The construction process should be carefully observed and documented to ensure the construction is performed in accordance with the design drawings and technical specifications. In any soil investigation it is necessary to assume that the subsurface soil conditions do not vary greatly from the conditions encountered in our field and laboratory testing. Our experience has been that at times soil conditions do change and variations do occur and may become apparent at the time of excavation for the foundation system. The work contained herein was performed by, or under the direct supervision of a licensed Professional Engineer in the State of Colorado. Professional judgments and evaluations are presented based on information gathered during the drilling operations, conversations with the owner and/or contractor, and on experience with similar projects. The performance of the project is not guaranteed in any manner, only that the engineering work and judgments rendered meet the standard of care of the engineering profession. The engineering services performed are within the limits set by the Client, with the usual thoroughness and competence of the engineering profession. No other representation, expressed or implied, is included or intended. The parties specifically agree that Colorado Geoscience and Design, Inc. has not been retained nor will they render an opinion concerning any environmental issues, hazardous waste or any other known or unknown conditions that may be present on this site, since this is not in the scope of this report. If this subsurface investigation is 4 years or older, Colorado Geoscience and Design, Inc. shall review the recommendations cited in this report to ensure all applicable codes are current and comply with the current state and county regulations. December 15, 2021 9 W he, u{° Subsurtace lnresligation Thinly Two Devbpnent 'TnS oW' T"5oM' Colondo Geaacience aM Daegn. Inc. Report No. 21-Mg Radon tends to accumulate in poorly ventilated areas below ground level and can accumulate in above grade construction as well. Providing increased ventilation of basements and crawl spaces and sealing of the joints can mitigate build-up of radon gas. This mitigation is best implemented during the design and construction phase of the residence. The Colorado Geologic Survey and the U.S. EPA are both good sources for additional information regarding radon. GENERAL INFORMATION Based on this subsurface investigation, the proposed foundations appear to be technically feasible to be constructed at the proposed site. The structures should be designed for construction in the direct vicinity of the boring location. If the proposed locations change, additional borings will be required to assess the soil conditions at the new location. Permitting work will be required to obtain any local and state approval, and design work will need to be performed by a qualified professional engineer to bring this project into final design, and subsequent construction. A qualified contractor experienced with similar projects should carry out the construction of this project. The construction process should be carefully observed and documented to ensure the construction is performed in accordance with the design drawings and technical specifications. In any soil investigation it is necessary to assume that the subsurface soil conditions do not vary greatly from the conditions encountered in our field and laboratory testing. Our experience has been that at times soil conditions do change and variations do occur and may become apparent at the time of excavation for the foundation system. The work contained herein was performed by, or under the direct supervision of a licensed Professional Engineer in the State of Colorado. Professional judgments and evaluations are presented based on information gathered during the drilling operations, conversations with the owner and/or contractor, and on experience with similar projects. The performance of the project is not guaranteed in any manner, only that the engineering work and judgments rendered meet the standard of care of the engineering profession. The engineering services performed are within the limits set by the Client, with the usual thoroughness and competence of the engineering profession. No other representation, expressed or implied, is included or intended. The parties specifically agree that Colorado Geoscience and Design, Inc. has not been retained nor will they render an opinion concerning any environmental issues, hazardous waste or any other known or unknown conditions that may be present on this site, since this is not in the scope of this report. If this subsurface investigation is 4 years or older, Colorado Geoscience and Design, Inc. shall review the recommendations cited in this report to ensure all applicable codes are current and comply with the current state and county regulations. December 15, 2021 9 Wne, u{ . _ PlI UK Omrnauitsm AFOUNDATION,� s n6 0 na ro xa wn.eroe'u'tau scALE THIRTY TWO A DEVELOPMENT IOH NO. I510AnON 5554 WESTYILH AVENUE, 21-369 WFST LQ JEFFERSON CO[ COLOR4O0 FIG.1 SITE MAP MWISRED IF OTHFAPFD COMATIESDADE IN ME HELD BOY "CHOT Colorado K 31 N B69 10I III ALL oe.A..c.sA.e.o.. IELIn wODTOE AAmn. scALE THIRTY TWO A DEVELOPMENT IOH NO. I510AnON 5554 WESTYILH AVENUE, 21-369 WFST LQ JEFFERSON CO[ COLOR4O0 FIG.1 SITE MAP MWISRED IF OTHFAPFD COMATIESDADE IN ME HELD BOY "CHOT Colorado aweina s pEq�na sEmM ALL oe.A..c.sA.e.o.. IELIn wODTOE AAmn. fW neaeHv u{ PROJECT: Subsurface Investigation JOB NO: 2133 Colorado Geoacienca and Design, Inc. CLIENT. Thirty Two Development —o -a Log of Test Holes LOCATION:5554 West 27th Avenue WestLot Jefferson Counlv Colorado Clay, slightly sandy to sandy, medium soft. very moist to saturated, calcareous, brown Clay, sandy to very sandy, stiff, very moist W saturated, calcareous, brown Claystone, very moist to saturated, gray brown Clay, slightly sandy to sandy, medium soft, very moist to saturated, calcareous, brown Clay, sandy to very santly, stiff, very moist to saturated, calcareous, brown Claystone, very moist to saturated, gray brown Notes: WMreMpliewbb- 1. Wy indicter thatfe number of blwn of a 140.pound hammer falling ng a' t Intllwba ground water encountered EunnB the Milos Inches are required to dome a 2 inch diameter sampler" y' number Nihre. I b. a Indicates ground water enwuntered after 24 hours. Figure 2 SWELL- CONSOLIDATION TESTS ++8 J +6 J 3 +0 0 y O K 42 at a p z _ w ¢ -2 U W J -0 a O i -6 O U -8 100 300 1M 3M 5M 10M 20,000 28,000 APPLIED PRESSURE (PSF) Test Hole No. 1 Depth 3' Soil Description: Clay, slightly sandy to sandy, medium soft. very moist to saturated, calcareous. brown ++8 100 300 1M 3M 5M 10M 20,000 28,000 APPLIED PRESSURE (PSF) Test Hole No. 1 Depth 8' Soil Description: Clay, slightly sandy to sandy, medium soft very moist to saturated, calcareous. brown JOB NO. 21-368 FIGURE 3 SWELL- CONSOLIDATION TESTS ++8 J � J ro LLH O O i2 2 0 O F -2 U O W p -4 a z -s 0 U -8 1vu Juu lM 3M 5M 10M 20,000 28,000 APPLIED PRESSURE (PSF) Test Hole No. 1 Depth 14' Soil Description: Clay, sandy to very sandy stiff, very moist to Saturated calcareous, brown iw awi m im om luM 2u,ouu 28,000 APPLIED PRESSURE (PSF) Test Hole No. 1 Depth 24' Soil Description Claystone very moist to saturated, pray brown JOB NO. 21-369 FIGURE 3 SWELL- CONSOLIDATION TESTS ++8 J +6 J +d 0 H U 0 +2 0 0 Q -2 U W J -4 o O _ -6 O U 8 100 300 1M 3M 5M 10M 20,000 28,000 APPLIED PRESSURE (PSF) Test Hole No. 2 Depth 4' Soil Description: Clay. sliahtly sandy to sandv. medium soft, veru moist to saturated, calcareous. brown 100 300 1M 3M 5M 10M 20,000 28,000 APPLIED PRESSURE (PSF) Test Hole JOB NO. 21-369 FIGURE 3 SWELL- CONSOLIDATION TESTS ++8 100 300 1M 3M 5M 10M 20,000 28,000 APPLIED PRESSURE (PSF) Test Hole No. 2 Depth 19' Soil Description: Claystone, veru moist to saturated, gray brown JOB NO. 21-369 FIGURE 3 �! \(!!f!! `!{!/|! RRH�I§! FOUNDATION GRADING DETAIL NOTE: 1. PROVIDE A MINIMUM SLOPE OF 6" IN THE FIRST 10'-0" FROM HOUSE (10%). 2. DOWNSPOUTS AND EXTENSIONS SHOULD EXTENDED 5'-0" BEYOND THE FOUNDATION. SECTION Colorado SCALE: NTS eeo.eMc. a D"!�, mo BRACE WALLS, TOP & BOTTOM 11 PRIOR TO BACKFILLING WELL SLOPED - 12" PER 10 FT. MIN. DO NOT DIKE NTH r�SOD OR EDGING CONCRETE GRADE OF WELL -COMPACTED Y COMPACTED SLOTTED DRAIN COVER ,e -DRAIN TO CONNECT WITH PERIMETER R SLAB3" TO 4" DAMP PROOFING POLYETHYLENE GLUED TO WALL AND EXTENDED ALONG THE EXPANSION JOINT\ BOTTOM OF THE EXCAVATION. VOID BETWEEN -15# BUILDING FELT 4MI . _ 3/4" TO 1 1/2" CLEAN GRAVEL 4" MIN. 4" DIAMETER PERFORATED PIPE. SLOPE DRAIN PIPE 1/8" PER FOOT TO DAYLIGHT, OR TO A SUMP PIT. IF TO DAYLIGHT, COVER END WITH SCREEN. BACKFILL AROUND THE FOUNDATION SHOULD BE MOISTENED AND COMPACTED AND THE FINAL GRADE SHOULD BE WELL SLOPED TO PRECLUDE PONDING OF RAINFALL, IRRIGATION WATER, AND SNOW MELT ADJACENT TO FOUNDATION WALLS. CAUTION: DO NOT DIKE OR IMPEDE THE FLOW OF WATER AWAY FROM FOUNDATION WALLS WITH SOD, EDGING OR DECORATIVE GRAVEL AND POLYETHYLENE. DOWNSPOUTS AND SILL COCKS SHOULD DISCHARGE INTO SPLACE BLOCKS OR LONG EXTENSIONS. EXTERIOR DRAIN SYSTEM BELOW GRADE AND BACKFILL DETAILS (FOR PIER FOUNDA-noNI SECTION SCALE: NTS m h �mign, in APPENDIX Important Information About the Report The data collected by Colorado Geoscience & Design, Inc. during this investigation was used to provide geotechnical information and recommendations regarding subsurface conditions on the site investigated, the effect of those conditions on the proposed construction, and the foundation type for the named client. The stratification lines indicated on the boring log are approximate, and subsurface conditions encountered may differ from those presented herein. This uncertainty cannot be eliminated because of the many variabilities associated with geology. Torexample, material and engineering characteristics of soil and bedrock may change more gradually or more quickly than indicated in this report, and the actual engineering propertics of non -sampled soil or rock may differ from interpretations made based on boring logs. Quantitative conclusions regarding the performance of geotechnical structures prior to construction are not possible because of the complexity of subsurface conditions. Rather, engineering judgments and experience are used to estimate likely geotechnical performance and provide the necessary recommendations for design and construction. Put another way, we cannot be sure about what is not visible, so the collected data and our training and experience are used to develop predictions and recommendations. There are no guarantees or warranties implied or expressed. The owner and/or client must understand that uncertainties are associated with geotechnical engineering, and they, the owner and/or client, must determine the level of risk they are willing to accept for the proposed construction. The risks can be reduced, but not eliminated, through more detailed investigation, which costs more money and takes more time, and through any appropriate construction which might be recommended as a result of that more detailed investigation. To reduce the level ofuncerninty, this report was prepared only for the referenced client and for the proposed construction indicated in the report. Unless authorized by Colorado Gcoscience & Design, Inc. in writing, the owner will assume additional geotechnical risk if this report is used for any construction that differs from that indicated in the report. Our firm should he consulted well before changes in the proposed construction occur, such as the nature, size, configuration, orientation, or location of any improvements. Additionally, the knowledge and experience of local geotechnical practices is continually expanding and it must be understood the presented recommendations were made according to the standard of practice at the time of report issuance. If the construction occurs one or more years after issuance of the report, the owner and/or client should contact our firm to determine if additional investigation or revised recommendations would be advisable. Geotechnical practice in the Denver Region must consider the risk associated with expansive soils and bedrock. Geotechnical practice in the Denver area uses a relative scale to evaluate swelling potentials. As stated in the Subsurface Investigation, when the sample is wetted under a surcharge pressure (loading) of 1000 pounds per square foot (PST), the measured amount of swell is classified as low, moderate, high, or very high. Page I of Y T"5M" Table 1 presents the relative classification criteria for the percentage of expansion relative to the initial sample height, at the indicated surcharge pressure. Swell Poteafial Chart L AT 1,000 LBS. CLASSIFICATION% Non-expansive/Very low% Lowh% a Moderate% High Very Highn 8% Critical The swell potential classifications are based on The percentage of swell for samples placed on sweNconsohdation machines under a surcharge of 1000 pounds per square foot. The relative swell classification can be correlated to potential slab damage as follows: Low - minor slab cracking, minor differential movement, and heave Moderate - lab cracking and differential movement, partial framing void and furnace plenum closure. High to Very High - large slab cracking and differential movement, closed voids, closed furnace plenum, and passible pipe rupture. These effects are based on monitoring and observation by several firms in the Denver metropolitan area and are not limited to the relative swell classification. More or less damage can occur in all classifications because of the uncertainty associated with subsurface conditions and geotechnical engineering. It is important to note that measured swell or soil expansion is not the only geotechnical criteria for the type of floor and foundation recommendations. Additional criteria considered include: • Soil and bedrock type and variability • Stratigraphy • Groundwater depth and anticipated post -construction moisture conditions. • Surface water drainage and features • Post -construction landscaping and irrigation • Construction details and proposed use • Local experience Page 2 of 3 Y T"5dr' Post -construction landscaping and owner maintenance will greatly affect structures on expansive soils and bedrock. Typically, irrigated landscaping increases the soil moisture content above the pre-constmcted water content. Slabs, pavements, and structures significantly reduce evaporation of the soil moisture. Therefore, post - construction heave and resulting damage to buildings and other improvements are likely to occur on sites with expansive soils because of the high probability that subsurface moisture content will increase as the property and surrounding area is developed. Poor owner maintenance, such as negative slopes adjacent to foundation walls and irrigated landscaping adjacent to the foundation, also will significantly increase the risk of damage from expansive soil and bedrock. The property owner, and anyone he or she plans to sell the property to, must understand the risks associated with construction in an expansive soil ares and also must assume responsibility for maintenance of the structure. The owner and prospective purchaser also should review "A Guide to Swelling Soils for Colorado Homebuyers and Homeowners, "which is a special publication (SP 43) produced by the Colorado Geological Survey to assist homeowners in reducing damage caused by swelling soils. Page 3 of 3 BRACE WALLS, TOP & BOTTOM, PRIOR TO BACKFILLING WELL SLOPED - 12" PER 10 FT. MIN. DO NOT DIKE WITH SOD OR EDGING CONCRETE GRADE 12" OF WELL -COMPACTED COMPACTED SLOTTED DRAIN COVER �-DRAIN TO CONNECT NTH PERIMETER R SLABS" TO 4" DAMP PROOFING \1/ \ POLYETHYLENE GLUED TO WALL AND EXTENDED ALONG THE EXPANSION JOINZ BOTTOM OF THE EXCAVATION. VOID BETWEEN --15# BUILDING FELT 4" MI ' 3/4" TO 1 1/2" CLEAN GRAVEL 4" MIN, 4" DIAMETER PERFORATED PIPE. SLOPE DRAIN PIPE 1/8" PER FOOT TO DAYLIGHT, OR TO A SUMP PIT. IF TO DAYLIGHT, COVER END NTH SCREEN. BACKFILL AROUND THE FOUNDATION SHOULD BE MOISTENED AND COMPACTED AND THE FINAL GRADE SHOULD BE WELL SLOPED TO PRECLUDE PONDING OF RAINFALL, IRRIGATION WATER, AND SNOW MELT ADJACENT TO FOUNDATION WALLS. CAUTION: DO NOT DIKE OR IMPEDE THE FLOW OF WATER AWAY FROM FOUNDATION WALLS WITH SOD, EDGING OR DECORATIVE GRAVEL AND POLYETHYLENE. DOWNSPOUTS AND SILL COCKS SHOULD DISCHARGE INTO SPLACE BLOCKS OR LONG EXTENSIONS. EXTERIOR DRAIN SYSTEM BELOW GRADE AND BACKFILL DETAILS (FOR PIER FOUNDATION) SECTION SCALE: NTS