The URL can be used to link to this page

Home My WebLink About3265 Gray St. SI,WFee,q u ry m O f r� COMPLETE ENGINEERING SERVICES, INC. SUBSURFACE INVESTIGATION AND ENGINEERING ANALYSIS PROPOSED SINGLE FAWIQ.Y RESIDENCE 3265 Orgy Street Wheat. Ridge, Colorado Prepared For: Harlwood Homes, LLC. 4134 Fenton St Denver, CO 80212 Attention: Mr. Brent Metz „°REe,,.,,,, Project Number: 19-11193 �ONAFebruary 3, 2020 912 TWELFTH STREET, GOLDEN, CO 80401 303 279-6418 FAX 303-2799585 TABLE OF CONTENTS SCOPE................................................................1 PROPOSED CONSTRUCTION................................................1 SITE CONDITIONS......................................................1 SUBSURFACE CONDITIONS................................................2 FOUNDATION DESIGN SPECIFICATIONS.....................................3 DRAIN SYSTEMS........................................................3 EXCAVATION SPECIFICATIONS............................................4 FOUNDATION BACKFILL..................................................5 INTERIOR FLOOR SLAB CONSTRUCTION ................................. ....5 LAWNAND LANDSCAPE IRRIGATION........................................6 INSPECTION }SND CONSULTATION..........................................7 FIGURES TEST HOLE LOCATION PLAN.......................................FIGURE 1 TEST HOLE LOG........................................................2 SWELL CONSOLIDATION TESTING..........................................3 DRAIN SYSTEM DETAIL..................................................4 WINDOW WELL DETAIL...................................................5 TYPICALEXCAVATION PROFILE...........................................6 ,Wnee,q u e om^s PROMCT NO. 19-11193 February 3, 2020 Page 1 of 8 A geotechnical and geological engineering investigation was conducted at 3265 Gray Street, Denver, Colorado, to determine foundation design criteria for a proposed single family residence and detached accessory building. Recommendations for design and construction, based on soil and groundwater conditions, are provided. This investigation does not include evaluation of soil or groundwater for the presence of pollutants or other environmental hazards. Conclusions and recommendations presented are based on results of a field and laboratory investigation, other investigations conducted by this firm in the area, and experience with similar projects and conditions. PROPOSED CONSTRUCTION Plans call for razing and removing a single family residence. A new single family residence will be constructed within the approximate building envelope of the previous residence. The residence will be two stories over a full -depth basement. New wood frame superstructures will be supported by reinforced concrete foundations. The site is in a fully developed residential subdivision in Denver,l Colorado. The surface within this lot is relatively flat. vegetation consists of shrubs, trees, sod and groundcover plants typical of landscaped residential property in the area. There are no apparent geologic hazards that should affect the proposed construction. PROJECT NO. 19-11193 February 3, 2020 Page 2 of 8 "-"' W Subsurface conditions were investigated by drilling one foundation design test hole in the anticipated building envelope. Approximate test hole location is shown in Figure 1, Test Hole Location Plan. The test hole was drilled to a depth of 30 feet and samples were taken at various intervals based on anticipated foundation bearing depths and materials encountered. A lithologic log and Standard Penetration test results are shown in Figure 2, Test Hole Log. Soils have been deposited by wind, low-energy stream flow and in-place weathering of the underlying bedrock. The test hole encountered five feet of silty medium -grained sand overlying four feet of sandstone. Claystone was present beneath the sandstone to the total depth investigated. Bedrock has been mapped by the O.S.G.S. as the Denver Formation. The Denver Formation consists of silty claystones and sandy siltstones interbedded with sandstones and conglomerate lenses. One-dimensional swell -consolidation testing was conducted on two representative bedrock sample from depths of 19 and 29 feet below existing grade. Results indicate the claystone has low consolidation potential. The soil samples consolidated 0.1 and 1.6 percent when saturated under a constant load of 1000 psf. Detailed swell - consolidation test results are presented in Figure 3. Groundwater was not encountered during drilling. Groundwater was measured at nine feet below existing grade when checked seven days after drilling. Due to the geologic and topographic location of the site, it is unlikely that groundwater will affect the residence during PROJECT NO. 19-11193 February 3, 2020 Page 3 of 8 or after construction. Groundwater may become more shallow following periods of heavy precipitation. Groundwater conditions can be better evaluated during construction by observing the foundation excavation. FOUNDATION DESIGN SPECIFICATIONS The residence and accessory building foundations can be supported on continuous spread footings and isolated pads designed for a maximum contact pressure of 2000 psf. Maximum contact pressure shall be calculated using full dead load plus full live load. Footings shall be constructed on relatively undisturbed native soil that is smooth, even and free of organic materials, debris or rocks over three inches in diameter. Footings shall not be constructed on frozen or saturated soils. Foundation walls and other walls retaining soil that are restrained at the top shall be designed to withstand an at -rest lateral earth pressure of 90 lb/cu-ft/£t. Walls retaining soil that are not restrained at the top shall be designed using an active equivalent fluid pressure of 30 pcf/ft. A pull-out friction coefficient of 0.8 shall be'used for soil retaining structures using geotextiles as reinforcement. An equivalent fluid pressure of 290 pcf/ft shall be used for passive lateral soil pressures. Concrete -to -soil friction coefficient shall be 0.9. ;,.j A drain system shall be constructed around the exterior basement foundation perimeter. The drain system shall be constructed in compliance with details shown in Figure 9, Drain System Detail, and PROJECT NO. 19-11193 February 3, 2020 Page 4 of B shall be graded to a sump pit with an automatic pump. The pump shall discharge to the ground surface a minimum of 10 feet from the structure. Bottom of the sump should be above the seasonal high water level for normal -depth basement construction. Particular attention shall be given to placing polyethylene along the bottom of the exterior drain and up the foundation wall and to proper grading of drain pipes. Improper grading, such as high or low spots in the drain pipes, could result in damage to the foundation and superstructure by overwetting of foundation bearing soils. Window well drains shall be constructed in conformance with specifications contained in Figure 5, Window well Details, and connected to the foundation drain system. iPGP ZOO "=ZPECXCIVS Soils encountered within the excavation profile are Type A according to OSSA classification parameters. These soils should hold a vertical face for a short time, but excavation sides may slough and/or fail if not retained. Excavation requirements are: i 1. Vertical cuts may be made to a maximum depth of four feet. The excavation shall be benched and sloped in conformance with Figure 6, Typical Excavation Profile, if excavation depth is greater than four feet. 2. The excavation shall be set back from the property line a distance equal to the first vertical cut depth. 3. Maximum allowable effective slope of the excavation shall be 1:1 (horizontal to vertical) or 45 degrees. Excavation shoring will be required if property constraints prohibit achieving this profile. Crawl -space and garage -depth excavations may have vertical cuts abutting the property line without shoring. 4. Roof gutter downspouts and surface drainage from this, and adjacent, properties shall be diverted away from the excavation during construction. ,Wnee,q u e om^s PROJECT NO. 19-11193 February 3, 2020 Page 5 0£ B Temporary shoring elements shall be designed to withstand an active lateral earth pressure of 30 pcf/£t and a passive lateral earth pressure of 275 pc£/ft. Shoring design and specifications can be provided if required. Backfill placed against foundation walls shall be free of trash and fragments of rock over six inches in maximum diameter, moistened and adequately compacted to prevent excessive settlement. Walls should be a minimum of seven days old prior to backfilling. Walls should be backfilled on both sides simultaneously. Controlled puddling shall not be used. The ground surface shall slope away from the foundation. A minimum grade of 10 percent (one foot in ten) shall be provided within 10 feet of the structure, or as far as property boundaries permit, where the surface is not covered with concrete or other hardscaping. The owner should periodically inspect the surface around the foundation to locate and correct grading problems that may occur due to normal foundation backfill settlement. INTERIOR FLOOR SLAB CONSTRUCTION The builder and/or owner should be aware that concrete floor slabs placed on native soil or bedrock may move if support materials become wet. Construction of a suspended floor over crawl space is one means of minimizing risk that slab movement will occur. PROJECT NO. 19-11193 February 3, 2020 Page 6 of 8 Expansion potential of soils at, and below, interior floor bearing elevation indicates there is a low risk of significant floor slab movement. Procedures that will help improve slab performance, minimize potential for movement, and help prevent damage, if some risk of movement can be tolerated, are: 1. Subgrade should be prepared based on the soil type encountered. Granular soils should be wetted and thoroughly compacted priorto slab placement. Cohesive materials should not be compacted more than necessary during excavation and construction. Clays and silts should not be allowed to dry excessively. The sure should be thoroughly wetted 29 hours prior to slab placement. 2. Concrete slabs should be reinforced with steel mesh and should be separated from all bearing members and utilities to allow independent movement I i.e., a "floating slab"). 3. Joints should be scored in the slab at maximum 200 -square -foot areas. 9. A minimum void space of one -and -one-half inches should be con- structed above or below any nonbearing partition walls. In finished areas, any furring strips, drywall, paneling, etc., should stop a minimum of two inches above the floor. 5. Water pipes should not be placed under the floor slab if hot water is used. A flexible connection should be used to allow some movement between the furnace and the heating ducts if forced -air heating is used. 6. Flexible connections should be used on all mechanical systems placed on floor slabs. All plumbing which extends below floor slabs should have flexible connections and allowance for movement with the slab. 9. Foundation drain systems and landscaping should be completed in strict compliance with specifications contained herein to help prevent wetting of slab support soils. LAWN AND LANDSCAPE' IRRIGATION Lawn and landscaping irrigation shall be controlled to prevent additional wetting of subsoils. Automatic sprinkling systems shall be ,Wnee,q u e O f PROJECT NO. 19-11193 February 3, 2020 Page 7 of 8 placed so that, under full pressure, spray does not fall within five feet of foundation walls. Drip or mist irrigation systems shall not be placed within five feet of foundation walls. Installing any portion of the irrigation system within five feet of walls should be avoided. Decorative landscape, such as rock and/or bark should be used in areas next to foundation walls. vegetation planted within five feet of foundatidn walls should be hand watered and this watering should be minimized. Downspouts and sillcocks should not be allowed to discharge directly on the ground surface. Splash blocks and/or down spout extensions should be used to discharge water beyond foundation backfill where backfill soils are not covered by pavement and/or sidewalks. The owner is encouraged to read A Guide to Swelling Soils Homebuyers and Homeowners, Special Publication No. 93, available from the Colorado Geological Survey. Recommendations contained in the report are applicable to all residential construction in the Denver area, regardless of soil expansion potential. INSPECTION AND CONSULTATION In any subsurface investigation it is necessary to assume conditions encountered in the field investigation are representative of the site. Actual conditions may differ from anticipated conditions. Subsurface conditions should be verified through visual inspection of the foundation excavation by a representative of this office prior to construction. Footing forms, reinforcing steel placement in foundation walls and drain system installation should also be inspected to ensure compliance with these recommendations and engineered foundation plans and comply with Denver Building Department requirements. PROJECT NO. 19-11193 February 3, 2020 Page 8 of 8 we are alailable to discuss the contents of this report with you. Please cntact us if you have questions or when further consultation or inspe tions are required. tWbee,q u TEST HOLE LOCATION PLAN e s 3265 GRAY STREET DENVER, COLORADO ----- •TH 1 —� I NPROPOSED� SI RESIDENCE Y I V EXPLANATIGN OTH-1 rlulmdngx rcsa >6r xalc 30 1 Teat holes are loaotetl using taping and map SCALE: 1" = 30' measurement. Locations should be aaneidead meu ate only to the degree Implied by the thod used. 19-11193T 0. COMPLETE ENGINEERING SERVICES FIGURE 1 f Wueerq u TEST HOLE LOG fi m_I e i MYaa EXPLANATION: 13/12 Indicates locution of standard penetration 5—C left Indicates 13 blows with a 1M pound 0.M, hammer falling 30 Inches were resulted to ® SAt10: 11y, gnMlg medium grained, donee, moist Moan (AI) di a 2.5" diameter vompls 12 pores. S—C Indicates sample tested lar swell— edldatim tmtid 8 percent emll an complain SANgSCNE: predominately medwm grained, hand. moil brawn B4AYSiCNE; sandy hard, molal army Indicates apprexlmate location of boundary between Ilthcll uni4 Transition may be gradual. 1j Indicates depth to water measured at ghm — number of dap after di n. ... indicates no groundwater prevent at time rimb f dnNng. PROJECT N0. PROJECT wississir F4 COMPLETE ENGINEERING SERVICES FIGURE 2 3 2 g 1 a 0 ■ 1 2 3 4 SWELL -CONSOLIDATION TEST RESULTS CONTENT:MOISTURE UNIT DRY WEIGHT:126.8 paf mm: IPRON: TMCI' AT 9&�y II I III Imo' III PRESWRENSOLNDER DUE TO WETTING 0.1 1.0 10 APPLFD PRESSLRE (kel) MOISTURE LDNTENT: 27.0% UNIT MY WEIGHT: 101.8 pal DESCRIPTION: Clartme, grey FROM: TI -1 AT 29 FEET mommlliilm�maiiali 0.1 1.0 10 APPLIED PRESSURE (kelt PRO111 3NO. e�ml COMPLETE ENGINEERING SERVICES 0 FIGURE 3 NWFee�q u e f DRAIN SYSTEM DETAIL FINAL GRADE COVER 1WTH +5 MILL PLASTIC AND DECORATIVE GRAVEL FLOOR SYSTEM LBACXFILL7 FOUNDATION WALL FOUNDATION EXCAVATION EXPANSION JOINT 1 + 5 MIL POLYETHYLENE GLUED TO WALL AND FLOOR SYSTEM EXTENDED ALONG BOTTOM OF EXCAVATION + 5 MIL POLYETHYLENE ,I�IL1. GRAVEL (MINUS 3/4')\� I I MIRAFI 1FILTER ABRIC OR EO IV. MINIMUM MI CLEAN FOOTING MINIMUM 8' CLEAN GRAVEL (MINUS 3/4") 3" DIAMETER PERFORATED PIPE MINIMUM SLOPE 1/8" PER FOOT. DISCHARGE TO SUMP WITH AUTOMATIC PUMP OR GRAVITY OUTFALL. 45 DEC. MAX. g�1t193 NO. COMPLETE ENGINEERING SERVICES FIGURE 4 WINDOW WELL DETAIL NOTE: APED NNDEPTH OF WINDOW WELL WELL CANNOTANNOT BE CONNECTED VARIES WITH NINDOW TO PERIMETER FOUNDATION ELEVATION AND GRADE DRAIN. WINDOW WELL FLOOR SYSTEM -117 EGRESS WINDOW =1 EMERGENCY LADDER COMPACTED EARTH MIN 3" CLEAN GRAVELOVERFLOW WINDOW DRAIN COMPACTED EARTH CONNECTED TO PERIMETER MIN 10% SLOPE —III FOUNDATION DRAIN FOUNDATION WALL INLET SHALL MIN 6" ABOVE 70—I COMPACTED SOIL AND COVERED EXPANSION JOINT WITH A GRATE OR SCREEN FLOOR SYSTEM III I'_III I I I FOOTING EXTERIOR DRAIN. RE: PROJECT NO. 19-11793 COMPLETE ENGINEERING SERVICES FIGURE 5 WFeeq u TYPICAL EXCAVATION PROFILE m 9265 GRAY STREET DFJfM COLORADO EXLAVATON Wall 6' MIN -1 ILO CNT& pUMM WM FWWAIIW r�� WALL TO w OF IX Wm W NNMAtt INE VN E NO UM TION 1% COMPLETE EXNWW OEPTI i FIGURE 6 FOUNOATON h H MIN. # r�� PROJECT Np. 19-11193 COMPLETE ENGINEERING SERVICES FIGURE 6