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Home My WebLink AboutObservation of Excavation 05.14.18GRAND JUNCTION LINCOLN DeVORE, Inc. CEOTtrCIINICAL ENGINEERS - GEOI,OGTSTS ,trt cmy"" ct v¿ cell: (970) 260'3332 Grand Junction, CO 81507 E-Mail: gildem@earthlink'net ll'lay 14,2018 Mr. Brandon & Mrs. Kelly Baker 7677 CP.30l Parachute, Colorado 81636 Re: Open Excavation Observation, New Residence at7677 CR 301, Parachute, CO Mr. & Mrs. Baker: As requested, Grand Junction Lincoln DeVore personnel completed a foundation excavation evaluation at the above-referenced site on 5-11-2018. The purpose of this observation and evaluation was to deterrrine the type and condition of the soils on the site and to relate their engineering cha¡acteristics to foundation reactions of the proposed structure. This letter contains general recommendations for construction of a residential foundation, Èut it is not a foundation design and may not be used as such. The site previously contained a manufactured housing unit, which was removed and the site reworked and a man-matlc fill placed, based upon rccommendations contained in our Report of Subsurface Soils Exploration for this site, Job No. 9533 I -GJ, dated October 31,,2017 . It is our understanding the proposed new residence will be a steel-framed, pre-engineered building. Our conclusions and recommendations for this site are presented below. Soil Classification: The soils at foundation level on this site are visually classified as gravelly, sandy tr"" "t"t (CL) of low compressive properties. These soils are man-made fills obtained from a borrow area immediately west of the building site. The larger fragments of basalt had been worked out of the soil during placement. This upper soil is believed tobe 2 to 4 feet thick below the foundation excavation and overlies gravelly, sandy lean-clay (CL) containing scattered small boulders,.all of low compressive properties. The ãUo*uút" bearing capacities of the upper soils on this site, after wetting and compaction, are 4000 psf maximum and 400 psf minimum. Unless specifically noted, this site observation, any associated testing, and the reworking/compaction ofthe soils at foundation level address only the soils within I to 2 feet below the bottom of the building foundation excavation. It is possible that soil conditions which may affect the performance of this foundation system are present below thè depth of soil compaction by the contractor and the testing performed by Grand Junction Lincoln DeVore. The grading and drainage recommendations are considered very important for the long-term stability of this foundation system and the structure. Man-madc Fill: personnel of Grand Junction Lincoln DeVore observed the recently placed structural fill ott the above-referenced site on May 11, 2018. The structural fill was found to consist of approximately 2 to 4 feet of gravelly, sandy lean clay. In-place soil density tests taken on t}re structural frll indicated that compaction was either equal to or in excess of 90Yo of the modified proctor density (ASTM D-l557) for these materials. The structuruf frll upp"*s to meet the minimum recommendations in the Report of Subsurface Soil Exploration performed by Grand Junction Lincoln DeVore. Mr. Brandon & Mrs. Kelly Baker Open Excavation Observation, New Residence at7677 CR 301, Parachute, CO. lr{ay I4,2Al8 Page? Soil Moisture Conditions: The subgrade soils at foundation level within the original excavation were believed to be dry to damp based upon site conditions and our experience in this a¡ea. No free water was noted in the excavation. Some moisture was added to the soils in the excavation by the contractor in order to obtain proper compaction. Foundation Tyoe Recommended: We understand that a designed foundation system of the pad and grade beam type, for a PESB, apparently based upon the recommendations provided in our previous report, has b""tt pt.p-"d by Tom Cronlq P.8.. That foundation design has not been reviewed by this office. The foundation system must be constructed in strict compliance with these plans and specifications, with no alterations or devia- tions allowed unless prior approval is frst obtained from the design engineer. Voids Beneath Foundation Walls: Voids may be required to mitigate expansive pressures and to attarn proper balance. see the design for proper location ofany required voids. Reinforcing: The foundation shall be reinforced as shown on the foundation design. No changes shall be made to this placement of reinforcing without written approval of the design cnginccr or architcct. Floor Slabs: Non-structural tloor slabs on grade, if any, should be positively separated from all structural portions of this building and allowed to float freely. Frequent scoring (control joints) of the slabs should be provided to allow for possible shrinkage cracking of the slab. These control joints should be placed to provide maximum slab areas of approximately 200 to 360 square feet. Any man-made frll placed below floor slabs on grade shouldbe compactedto aminimum of90% of its maximum modifiedproctordrydensity(ASTMD-1557). These soils should be placed at a moisture content conducive to the required compaction (usually proctor optimum moisture content + 2%). Drainage and Grading: Adequate site drainage should be provided in the foundation area, both during and after construction, to prevent the ponding of water and the wetting or saturation of the subsurface soils. We recommend that the ground surface around the structure be graded so tbat surface water will be carried quickly away from the building. The minimum gradient within 10 feet of the building will depend on surface landscaping. We recommend that paved areas maint¿in a minimum gradient of 2Yo and that landscaped areas maintain a minimum gradientof SYo.ltisfurtherrecommendedthatroofdraindownspoutsbecarriedatleast5 feetbeyond all backfilled areas and discharge a minimum 10 feet away from the structure. Proper discharge of roof drain downspouts may require the use of subsurface piping in some areas. Under no circumstances should a "dr¡r well discharge" be used on this site unless specifically sited by a geotechnical engineer. Planters, if any' should be constructed so that moisture is not allowed to seep into foundation areas or beneath slabs or pavements. The existing drainage on the site must either be maintained carefully or improved. We recommend that water be drained away from structures as rapidly as possible and not be allowed to stand or pond within 15 feet of the building or foundation. 'We recommend that water removed from one building not be directed onto the backfill areas of adjacent buildings. Mr. Brandon & Mrs. Kelly Baker Open Excavation Observation, New Residence at7677 CR 301, Parachute, CO May 14, 2018 Page 3 Should an automatic lawn irrigation system be used on this site, we recommend that the sprinkler heads, irrigation piping, and valves be installed no less than 5 feet from the building. In addition, these heads should be adjusted so that spray from the system does not fall onto the walls of the building and that such water does not excessively wet the backfill soils. It is recommended that lawn and landscaping irrigation be reasonably limited to prevent undesirable saturation of subsurface soils or bacldlled areas. Several methods of irrigation water control are possible, to include, but not be limited to: Metering the inigation water. Sizing the inigation distribution service piping to limit onsite water usage. Encourage efficient landscaping practices. Enforcing reasonable limits on the size of high water usage landscaping within 5 feet of the building or foundation. Incorporating "xeriscaping" landscaping and irrigation techniques. A plastic membrane placed on ¿Lny crawlspace ground surfaces may retain/trap excessive amounts of water beneath the membrane. If future moisture problems develop or are anticipated, the foundation design engineer or the geotechnical engineer may require that the membrane be partially or completely removed from the crawlspace arca. Provided that all recommendations found herein pertaining to site surface drainage, grading and soil compaction are closely followed, aperimeter foundation drain would not be required. For fully finished basements, however, the use of a perimeter foundation drain would significantly reduce potential moisture-related problems that can arise from subsequent area development. Backfill: To reduce settlement and aid in keeping water from reaching beneath this building, all backfrll around this building should be mechanically compacted to a minimum of 90Yo of its maximum modified proctor dry density (ASTM D-1557). The only exception to this would be the çsmponents of the perimeter foundation drain, if any. All backfill should be composed of the native soils and should not be placed by soaking, jetting or puddling. All backfill placed in utility trenches around this structure or below foundation walls should bcmcchanically compactcdto aminimumof90% ofitsmaximummodificdproctordrydensity(ASTMD-1557). These soils should be placed at a moisfure content conducive to the required compaction (usually proctor optimum content +2%). Cement Type: Type II, Type l-tr, or Type II-V cement is recommended for all concrete in contact with the soils on this site. Calcium chloride should not be added to a Type II, Type l-tr, or Type II-V cement under any circumstances. Remarks: We recommend that the bottom of all foundation components rest a minimum of 2-1/2 feet below finished grade or as required bythe local building codes. Foundation components must not be placed on frozen soils. Mr. Brandon & Mrs. Kelly Baker Open Excavation Observation, New Residence at7677 CR 301, Parachute, CO. May 14,2018 Page 4 Senate Bill 13 (CRS 6-6.5-101) Discussion: This particular residence is being constructed on foundation soils that do not possess a "significant potential for expansion." 'We recommend that the owner receive a copy of this summary report of our soil analysis and site recommendations. Limitations: This report is issued with the understanding that it is the responsibility of the owner or his representative to ensure that the information and recommendations contained herein are broughtto the attention of ilte architect and engineer for the project and are incorporated into the plans. In addition, it is his responsibility to ensure that the necessary steps are taken to see that the contractor and his subcontractors carry out these recommendations during construction. The findings of this report are valid as of the present date. However, changes in the conditions of a property can occur with the passage of time, whether they be due to natural processes or the works of man on this or adjacent properties. In addition, changes in acceptable or appropriate standards may occur or may result from legislation or the broadening of engineering knowledge. Accordingly, the findings of this report may be invalid, wholly or partially, by changes outside our control. Therefore, this report is subject to review and should not be relied upon after a period ofthree years. The recommendations ofthis report pertain only to the site investigated and are based on the assumption that the soil conditions do not deviate from those described in this report. If any variations or undesirable conditions are encountered during construction, or if the proposed construction will differ from that planned on the day of this report, Grand Junction Lincoln DEVorc should be notified so that supplcmcntal rccommcndations can be provided, if appropriate. Grand Junction Lincoln DeVore makes no warrant¡r, either expressed or implied, as to the findings, recommendations, specifications, or professional advice except that they were prepared in accordance with generally accepted professional engineering practices in the field ofgeotechnical engineering. Respectfu lly submitted, GRAND JTINCTION LINCOLN DeVORE, INC. by: Edward Principal Engineer GJLD Job No. 95331-GJ cR?ctt DFÁ,t{^68 zoÀ,Ê ?Ttcg fiE NtDtH ç TlrE firdt^r Extc yÁ7t4, Ut¿I(váf,rEs - nm//c/n rF ã FEËf FRây Ealt-DtNô) RoOF 0O|ÍrlSp0Ul-.-- SOn F,rEP,liED.C't. !'DCF tD ¿¡¡þS¡PE: \ ¡lsË tor nArEñ usc ¡!?f pt¡r{rs øt!/t ffißÆtto. rËc*tMqr6s Hll,trl Í5 'ôtl¡all 0FAß,¡G zoivË,. 6È4/¡10 TCRæS âEIEAÏH I I In 3tr fHE NAI.W SfItS gEtor rHE 'cfi,7lcr¿ Dníil¡cE zotË fo æ ñESffi'(tD ¿r CdtPrctED FtFtA A/,MEU'/ tr t2 NCHES ä¡ sdt 8 ctFil.t COilPAôTED IO Nl//il//EE YÁ'ER !¡EEPáGE 70 TllE Fot,r't ^7'O{ Sd[S rtrtl ?HlCl(ltlEIìS I II--LJ _ I lmLM9,ûË5¡.1 smucrUR AL F¡LLa a o ô aaa öit'i¡ lFjit'o â oûêr¡¡ i fjit'ooooô oa. t l¡Ìa. r¡ a.¡t|l¡ ¡l ¡. ¡o a aoa ó¡ ¡ ri¡f aô $NLL TO EXTEND BENEATHALL FOUNDATION ELEMENTS. SEË AJOTES ,ao¡ôooôo aa¡... . .t'trÍ¡,r.I J ot t ¡aa o cf ¡rl¡oa ta !äc vlnÕt tztt GEETEXTILE FABRICsuch qs Contech C-180on Mlrofl 500-X a c ¡aaËa AS REOUIREII DRATNAGE / LANDSCAPTNG CONCEPT 'NO WA R ZONE,B YF N DATION CRINCAL DRA]NAGE ZONE nHcE ÏHE WU tr ttË ORt6ttr^¿ üc|v '/0N umt( v¡Frgs - HNM.tu tr a FEË1' Fn'il, BUUDN0 ) SOIL PREPAAED â' to 8' DEEP fO LiMTSCTFEUg 'LOV Í^rEñ U5É It'E Ptáilnt ñd/rr'tÉRtflnüe' IECHI,,d/ES *rtHn Ì¡lE ',cRtnc L DRANACE Zdi/Ê, Ræ c801,l{D stopE Ácnoss tár{DscåPrâtc rHE il IIiE SdtS anor ilE 'cRlncrü ÞnÁ,rrÁ68 zc[vË tÐ 8ã sdl EÁc,(trLl IA'EN 6EEF¡GE Tþ Ë É ËRilffiKH)¿r ú?YPåC7EO Fffi oF t2 rrvôtEt¡ t¡rE FOt ¿VDAttOt Sdt.s ä¡ A nNtNUU PVE DRllt{^6Ê PIPE ucåu nou uutT--+IFILL 7HlClO/ËSSl rr-_Ll r lFltl THlCKfilESSr -_ L.æI STRUCruRAL FILLoooo coooi?'r¡ ¡ Íji!'o o coooo o¡¡?'¡it.i¡FILL TO EXTEND BENEATHAU FOUNDANON ELEMENTS. SEE NOTESooooooo¡t ai . ra-¡aa. ¡ ¡ l¡l¡ ¡a lo o a o oc¡r'i¡f¡ oo ooooo coo. ¡l...rar ar ar ¡ ¡¿a¡ .a t. ¡ ¡l. a' oi!'oo ooooêo¡ ¡ f¡i!'i ¡GEETEXTILE FABRICo oð ô o such qs Contech C-180,NSTáLL DRA'N on Mlrofl 500-XÁS REOU'RED BY ENG'A/EER.AS REOUTREDSEE AJOTES FOR OETA'LS. DRAINAG / LANDScAPING CONCEPT,NO WA ZONE' BY FOU N DATI ON GRAND JUNCTION LïNCOIN-DeVORE, Inc. CEOTECHI¡ICÆ. ENGI}¡EERS- GEOT.OCXSTSIW EXTERIOR DRAINAGE LANDSCAPING CONCEPT D^18 9-'r 6-2oos Egill¡¡ NONE tDÍ F[r t D-DRAIN2