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Home My WebLink AboutGeotechnical Investigation.. ,, CTLITHOMPSON .I RN C 0 a P O ~R •A T ~I D ~ January 29 . 2014 Phil Vaughan Construction Management, Inc. 1038 County Road 323 Rifle, CO 81650 Attention: Mr. Phil Vaughan Subject: Geotechnlcal Investigation Dewatering Building WPX Energy-Parachute Water Management Facility Garfield County. Colorado Project No. GS0544B.001-125 This letter presents the results of our geotechnical investigation for the proposed soft-covered , steel truss structure referred to as the WPX Oewatering Building. The purpose of our investigation was to evaluate the subsurface conditions at the site and provide geotechnlcal engineering recommendations for the anticipated construction. Our recommendations were developed from data obtained during our field exploration and laboratory testing, engineering analysis and our experience with similar conditions. Site Conditions The site for the new structure Is adjacent and southeast of the existing WPX Energy-Parachute Water Management Facility In Garfield County, Colorado. The structure will be constructed west of an existing gravel access road to the facility (see Figure 1 ). The site has been graded relatively flat and level . Eight existing 300 barrel upright tanks are on the site, as well as an existing natural gas well. The new structure will cover the existing tanks. Vegetation at the site has been removed by grading operations. The site is shown on Figure 2. Anticipated Construction The dewatering structure will be 40 or 52 feet wide by 80 feet long. The structure will be a prefabricated steel truss skeleton with a soft membrane cover constructed over the eight existing 300 barrel upright tanks at the site . The membrane material will be a coated polyolefin fabric. A steel frame. lined gravel pit will be Installed Inside the building . Grade beams for the structure's steel frame will be either 3 feet or 4 feet tall . The steel frame will be welded truss arches with parallel tube cords. The steel frame will likely be attached to the grade beam with J- bolt anchors . The fabric membrane Is tensioned over the structural frame work . 234 Center Drive I Glenwood Springs, Colorado 81601 Telephone: 970-945-2809 Fax: 970-945-7411 We expect maximum foundation excavation depths of 3 to 4 feet, for frost protection and to provide positive earth pressure resistance. Vertical downward foundation loads for the structure are expected to be less than 1,000 pounds per lineal foot of foundation. The lateral and uplift loads on the foundation from wind loads may be the controlling factor relative to foundation design. Subsurface Conditions To Investigate subsurface conditions below the structure site, we directed the drilling of one exploratory boring (TH-1) at the approximate location shown on Figure 2. The boring was drilled with 4-inch diameter, solid-stem, continuous flight auger and a track-mounted drill rig. Drilling operations were directed by our project engineer who logged the soils encountered In the boring and obtained samples . A graphic log of the soils encountered In our exploratory boring is shown on Figure 3. Subsurface conditions encountered in our exploratory boring consisted of about 1 foot of aggregate base course and 9 feet of sandy clay underlain by claystone bedrock to the maximum explored depth of 20 feel Atterberg limits on a sample of the clay and claystone tested were a liquid limit of 39 and 71 percent and plastic Indices of 24 and 51, respectively. The samples contained 85 and 89 percent silt and clay size particles (passing the No . 200 sieve). A sample of the clay and a sample of the claystone were selected for one dimensional swell consolidation testing. The samples were wetted under an applied load of 1,000 psf and the resulting volume change measured. The samples exhibited 2.4 and 15.9 percent swell when wetted. The potential for future expansion of the soil and underlying bedrock have been considered in choosing appropriate foundation alternatives . Our observations during drilling indicated the clay was very stiff and the bedrock was very hard . Free groundwater was not found in our boring at the time of drilling. The boring was backfilled immediately after drilling operations were completed. Earthwork Excavations will likely be that required to construct the grade beams and the lined gravel pit. Excavation depths of about 3 to 4 feet are anticipated for frost protection. Deeper excavations to construct taller grade beams or foundation walls may be required to provide lateral resistance to uplift or lateral loads. We anticipate that excavations can be accomplished using conventional, heavy-duty excavation equipment. Sides of excavations deeper than 4 feet will need to be sloped or braced to meet local, state and federal safety regulations. We expect the upper clay soils will classify as a Type B soil based on OSHA standards governing excavations. Temporary slopes deeper than 4 feet that are not retained should be no steeper that 1 to 1 (horizontal to vertical) in Type B soils according to OSHA standards . PHIL VAUGHAN CONSTRUCTION MANAGEMENT, INC. DEWATERING BUILDING WPX ENERGY -PARACHUTE WATER MANAGEMENT FACIJTY PROJECT NO. GS05C4UOM25 ll:IOllK4Cl.011\1Zlll>. Lldl8nlGllllSMl.IOt 125 Lt.doc 2 Backfill adjacent to foundation walls should be property moisture treated and denslfled to prevent infiltration of surface water. The on·site natural clay soils are suitable for reuse as backfill . Backfill should be placed In lifts of 1 O Inches thick or less, molsture·treated, and compacted to at least 95 percent of standard Proctor (ASTM 0 698) maximum dry density. We recommend that density of backfill be checked during placement. Foundations Our boring Indicates that sandy clay will be present at proposed foundation elevations. Due to the expansive nature of the natural clay and underlying bedrock, shallow footing foundations are not appropriate at this site. We recommend constructing the structure foundation walls on a deep foundation system of either drilled piers or microplles. Helical piers where considered, but not recommended because of concerns about water movement along the shaft wetting the highly expansive bedrock. Drilled piers and mlcropiles concentrate building deadloads and anchor the foundation below the zone of probable moisture variation to resist potential swelling pressures from the expansive soils . Design and construction criteria for the foundation alternatives are presented below. Drilled Piers 1. Piers should be bottomed In the claystone bedrock. Piers should be designed for a maximum allowable end bearing pressure of 30,000 psf and an allowable skin friction value of 3,000 psf for the portion of the pier in claystone. The skin friction value Is appropriate to resist both upward and downward loads. Skin friction should be neglected for the portion of the pier within 5 feet of the bottom of the foundation walls and grade beams. 2. The bedrock should be assigned a skin friction value of 3,000 psf for uplift resistance. The soils above the bedrock should not be used In calculations to determine pier capacity. 3. Piers should penetrate at least 10 feet into the relatively unweathered bedrock . Piers should have a total length of at least 20 feet. 4. Piers should be reinforced to resist a potential uplift tension force of (47 kips x pier diameter In feet) less the applied load . Reinforcement should extend into grade beams and foundation walls . 5. A 4-lnch continuous void will be required beneath all grade beams and foundation walls, between piers , to concentrate the deadload of the building on the piers. Foundation walls and grade beams should PHIL VAUGHAN CONSTRUCTION MANAGEMENT, INC. DEWAT£RINO BUILDING WPX ENERGY -PARACHUTE WAT!R MANAGEMENT FACILITY PROJECT NO. 0105"1.DGM25 a:1GSUW1.0111teu. L11tn\GSO$Ml.OOt 125 u .doc 3 be well reinforced; the reinforcement should be designed by the structural engineer. 6. Piers should be carefully cleaned prior to placement of concrete. To reduce potential for problems during pier Installation, we recommend that a "drill and pour" construction procedure be used, In which concrete is placed in the pier holes Immediately after the holes are drilled, cleaned and Inspected by our representative. Concrete should not be placed by free fall In pier holes containing more than 3 Inches of water. 7. Formation of mushrooms or enlargements at the top of piers should be avoided during pier drilling and subsequent construction operations. 8. Installation of drilled piers should be observed by a representative of our firm to identify the proper bearing strata . Micro piles 1. Commonly available micropile systems have a maximum working capacity in the range of 20 to 100 kips. 2. Micropiles should be designed and installed in accordance w ith Case I, Type B requirements as specified in USDOT publication number FHWA-NHl-05-039 for portions of the mlcropile In the clay soils above the bedrock. Grout Is placed through casing under pressure during Installation of a Type B mlcroplle. Type A mlcroplles construction is appropriate for the portion of the mlcroplle in bedrock. We are concerned about contamination of grout during Type A mlcroplle Installation In the upper clay soils. We recommend load tests be performed prior to the start of production micropile installation to check bond stress and Installation methods. We can assist in the design of microplles, If requested. 3. We believe mlcroplles should be designed using grout/ground Interface bond strength of 20 psi in the claystone bedrock. The soils above the bedrock should not be Included in capacity calculations. The Installation contractor should verify this strength is appropriate for their installation method and experience based on load testing. Higher bond stresses based on contractors experience and load tests may be appropriate . 4. Microplles should have a total length of at least 20 feet. PHIL VAUGHAN CONITRUC:TION MANAGEMENT, INC. DEWATERING BUILDING WPX ENERGY ~ PARACHUTE WATER MANAGEMENT FACIUTY PROJECT NO. OS05441.GDM25 l:IGSOM41.D•U11!1U. Ldllnl08054M.OCl1 125L1 .dlMI 4 5. We recommend that the upper 10 feet of casing be permanent to reduce uplift forces. This upper section of permanent casing may also be required for lateral load considerations. 6. Micropiles should be reinforced their full length. The area of reinforcing steel should be sufficient to withstand uplift. 7. Drilling methods should be determined by the contractor. Ory rotary or air flush methods are preferable to water flush due to expansive soils. 8. Micropiles should have a minimum diameter of 5 inches. 9. A 4-lnch void (or thicker) should be established underneath all grade beams and foundation walls between piles, to allow free swell or heave of soils under the grade beams and walls. Surface Drainage Surface drainage is critical to the performance of foundations. The ground surface around the structure should be sloped to direct runoff away from the structure. Backfill adjacent to foundation walls should be moisture conditioned and compacted as recommended In the Earthwork section. Final Design Consultation and Construction Obseivatlon This report has been prepared for the exclusive use of Phil Vaughan Construction Management, Inc. and the design team for the purpose of providing geotechnical criteria for the proposed project. The information and the conclusions and recommendations presented herein are based upon the considerations of many factors including , but not limited to, the type of structure proposed, the configuration and location of the structure, the geologic setting, and the subsurface conditions encountered. The conclusions and recommendations contained In the report are not valid for use by others. Standards of practice continuously change In the area of geotechnical engineering. The recommendations provided are appropriate for about three years . If the proposed project Is not constructed within about three years, we should be contacted to determine if we should update this report . It is recommended that CTL I Thompson, Inc. be retained to provide general review of the final construction plans prior to construction . Our firm should also be retained to provide geotechnlcal engineering and material testing during construction. The purpose Is to obseive the construction with respect to the geotechnical design concepts, specifications or recommendations, and to facilitate design changes in areas where the subsurface conditions differ from those anticipated prior to start of construction. PHIL VAUGHAN CONSTRUCTION MANAGEMENT, INC. DEWATERING BUILDING WPX ENERGY-PARACHUTE WATER MANAGEMENT FACILITY PROJECT NO. G8054C8.00M25 S:\GIOs.u&.001\125\3 . l.eltwa\GS0544U01121 L1.dDC 5 Geotechnlcal Risk The concept of risk Is an Important aspect of any geotechnlcal evaluation. The primary reason for this Is that the analytical methods used to develop geotechnlcal recommendations do not comprise an exact science. The analytical tools which geotechnlcal engineers use are generally empirical and must be tempered by engineering judgment and experience. Therefore, the solutions or recommendations presented In any geotechnlcal evaluation should not be considered risk-free and, more Importantly, are not a guarantee that the interaction between the soils and the proposed structure will perform as desired or intended. What the engineering recommendations presented In the preceding sections do constitute is our estimate, based on the Information generated during this and previous evaluations and our experience In working with these conditions, of those measures that are necessary to help the development perform satisfactorily. The owner must understand this concept of risk, as it Is they who must decide what is an acceptable level of risk for these structures. Limitations Our exploratory boring was located to obtain a reasonably accurate picture of subsurface conditions. Variations In the subsurface conditions not Indicated by our boring will occur. A representative of our firm should be called to observe the completed foundation excavations to confirm that the exposed soils are suitable for support of the culvert and wing walls as designed. This investigation was conducted In a manner consistent with that level of care and skill ordinarily exercised by geotechnical engineers currently practicing under similar conditions In the locality of this project. No warranty, express or Implied, Is made. If we can be of further service in discussing the contents of this report or In the analysis of the Influence of the subsoil conditions on the planned construction, please call. Very Truly Yours ERW:JM:cd cc: Via email to phll@pvcmi.com PHIL VAUGHAN CONSTRUCTION MANAGEMENT, INC. DEWATERING BUILDING WPX ENERGY-PARACHUTE WATER MANAGEMENT FACIUTY PROJECT NO. 0805441.001-125 S :IOl50SUUtt\125U. u11'1ra\GIOl44.001125L1.doc 6 ! ::: • 8 i SCALE: 1" • 2,000' PHIL VAUGHN CONSTRUCTION MANAGEMENT, INC. WPX CEWATIRINO BUILDINQ Project No. GS05448.001-125 Vicinity Map Fig. 1 "4,• PROPOSED BUILDING .. LOCATION •TH-1 • ~~· · . ... .j "" . \f"' ~ "---EXISTING NATURAL GAS WELL ~ NOTE: f exploratory Location :;,xJmate. borfng I• app HANCONS'TR IJCTION MANAG EMENT,INC. PHIL V~19WG llULOINQ544S 001-125 WPX l:llW" GSO • Project No. Rg. 2 TH-1 T 0 0 LEGEND: • l!I 5 22/12 l 10 35/12 10 i' '!. :r .5 5' .c '&. 50/7 l • 15 15 Q ----- 20 ~· 20 25 25 NOTES: Gravel driving •urf ace, aggregate ba•e courae. Clay, sandy, calcareou•, shale fragmenh, moist, very .tiff, brown. (CL) Clay.tone bedrock, sandy, very hard, mol ... gray, tan. Drive sample. The 1ymbol 22/12 Indicates that 22 blows of a 140 pound hammer falllng 30 Inches were n1qulred to drive a 2.5 Inch O.D. Callfomla 1ampler 12 Inch••· 1. An exploratory boring wa• drlll•d on January 10, 2014 with 4-lnch diameter, aontlnuou•-fllght •olld-.. •m auger and a track-mounted drlll rig. 2. Location of exploratory boring I• approximate. 3. No free ground water was found In our exploratory boring at the time of drllllng. 4. Thi• exploratory boring I• •ubJect to the explanatlon1, !Imitation• and conclu•lon• as contained In thl• report. SUMMARY LOG OF EXPLORATORY BORING Project No. GSOS«S.001-125 Fig. 3 APPLIED PRESSURE • KSF Semple of CLAY, SANDY(CH) From TH-f AT9 FEET------- PHIL VAUGHAN CONSTRUCTION M,ANAGEMENT, INC. WPX DEWATERJNG BUILDING PROJECT NO. GS05448.001-125 l:IGSD54Cll.ID1112N. C.lca'oGSH441.llD1 125 lwll.llla 10 DRY UNIT WEIGHT:o MOISTURE CONTENT= 100 113 PC F 11.9 % Swell Consolidation Test Results FlG .4 17 l I I i : : --t_j-l-llilJLUJJ.li-~ =-j-L ! 1 · Ll EXPANSION UNDER CONSTANT 111 15 ~,____..._PRESSURE DUE TO WETTING e·• I I : l I t 11 ! ---1--~ -l1 -t--. -~ J 14 z 0 13 12 11 10 7 B 5 4 3 ;; 2 ~ ~1 ~ z 0 0 ;; v I -- I 1;----_,_ - \ -l.l \ I I\. t ., -' "' :'II:"' - - ,_ -:-c-c---,--- I i I ---t--·--·-'. ~-r-r -~=r ~-·- f3 _, D::: a. ~ -2 0 u -3 I :11 ~ -1--!--] -111-rT v- 0.1 APPLIED PRESSURE -KSF Sample of CLAYSTONE From TH-1AT14 FEET 1.0 PHIL VAUGHAN CONSTRUCTION M.ANAGEMENT, INC. WPX DEWATERING BUILDING PROJECT NO. GSD5448.0D1-125 S:IGSOS441.DD1\125\I, C11ca\GSOIM41.DD1125 &w.11.als \!, I I \Jl-r-_,_ t-- J II I \)., I I I ~ I ·- \ I' I .. ' \ ! I I I I-> • -! \ ! I _,_ ~l I n· ~ ! ··\-t l l l I ' l l I ; \ -I I I ..,._ r-,__ ..... ,_ I I I I H-~f 1--! .7-r · --rr l_J_ ---·+-- --· --: r: i 1--± ·-lt ~ 1 I iTllt-1--i--11111 I - 10 DRY UNIT WEIGHT= MOISTURE CONTENT= 100 122 PCF 7.4 % Swell Consolidation Test Results FIG .5 MOISTURE DRY · EXPLORATORY DEPTH CONTENT DENSITY BORING (FEET) (%) (PCF} IH+1 4 13.5 121 TH-1 9 11.9 113 TH-1 14 7.4 122 'fH.1 19 8.8 I I A11~ LIQUID LIMIT (%) 39 71 TABLE I SUMMARYOFLABORATORYTESTING PROJECT NO. GSOS448.001-125 i=J'tG LIMITS SWELL TEST l"(I :sULTs• PLASTICITY SWELL INDEX SWELL PRESSURE (%) (%) (PSFl 24 2.4 2,800 15.9 12,000 51 • SWEU. MEASURED WrTH 1000 PSF APPLIED PRESSURE, OR ESTIMATED IN-SITU OVERBURDEN PRESSURE. NEGATIVE VALUE INDICATES COMPRESSION. .. PASSING SOLUBLE N0.200 SULFATES SIEVE (%) (%) DESCRIPTION 0.040 85 CLAY, SANIJy (Cll CLAY, SANDY (CL) CLAYSTONE 89 CLAYSTONE I Page 1of1