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HomeMy WebLinkAboutSoils Report 10.24.2014ITCTLITHOMPSON 1 H C O R POR 1L T ID October 24, 2014 Phil Vaughan Construction Management, Inc. 1038 County Road 323 Rifle, CO 81650 Attention: Mr. Phil Vaughan Subject: Geologic Hazard Evaluation and Geotechnical Investigation WPX Energy Trail Ridge Employee Housing Facility Garfield County, Colorado Project No. GS05884-115 Revised This letter presents the results of our geologic hazard and geotechnical investigation for the proposed Trail Ridge Employee Housing Facility in Garfield County, Colorado. Our geologic hazard evaluation consisted of literature review and a field reconnaissance by our geologist. The purpose of our geotechnical investigation was to evaluate the subsurface conditions at the site and provide geotechnical engineering recommendations. Recommendations were developed from information obtained during our field exploration, laboratory testing, engi- neering analysis and our experience with similar conditions. Site Conditions The site is about 22 miles north of DeBeque, Colorado. Access is via Rio Blanco County Road 5 and Trail Ridge Road, which is aligned with Parachute Creek. The turnoff to the site is near mile marker 20 at the West Fork of Para- chute Creek. The site location is 39°38' 58" N and 108° 15' 45" W. A relatively flat area is in the northern quadrant of the site. To the south and west of the flat area, slopes drop down steeply to the south. Vegetation is sage and natural grasses and weeds. A vicinity map is shown on Figure 1. The site is shown on Figure 2. Anticipated Construction The Trail Ridge Employee Housing Facility will include five factory built units placed together. The individual unit dimensions are 58 feet long and 13 feet wide. The final building footprint will be approximately 75 feet by 62 feet. 234 Center Drive I Glenwood Springs, Colorado 81601 Telephone: 970-945-2809 Fax: 970-945-7411 The building frame is three 12 x 26 steel beam skids. The skids will bear on a layer of compacted gravel. The storage building will likely be 60 feet by 125 feet in plan dimension and 50 feet high. Building construction will be a prefabricated steel truss skele- ton with a soft membrane cover tensioned over the framework. The membrane material will likely be a coated polyolefin fabric. The steel frame will be welded truss arches. The steel frame will be supported on micropiles. We expect maximum foundation excavation depths of 3 to 5 feet, for frost protection and to provide positive earth pressure resistance. Vertical downward foundation loads for the structures 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. Site Geology and Geologic Hazards Site geology and geologic hazards on this parcel were evaluated by David A. Glater, P.E., C.P.G., using field reconnaissance on October 3, 2014 and a re- view of available literature. The ground surface at the time of our visit was snow - free. Literature references are cited at the end of this section. The Trail Ridge Employee Housing Facility will be situated at about 8500 feet elevation along the top of a south -facing slope on an east -trending ridge above the West Fork of Parachute Creek. Aerial photos from Google Earth indi- cate that sometime between April of 2006 and August of 2010, the current site was formed by excavation that resulted in a nearly -level pad about 450 feet long (east -west) by 150 feet wide (north -south). Since there is little downslope fill em- bankment and the uphill cut slope is about 20 feet high, we assume the approx- imately 25,000 cubic yards of excavated materials were used as fill off-site. The excavation slopes expose light brown, fine-grained marlstone and sandstone from the Eocene -age Unit E of the Uinta Formation (Reference 1). Little soil has formed on the bedrock and outcrops are common outside the excavated area. The structural dip is nearly level in this area. No significant structural faulting is mapped in the area. We performed a radiation survey. Our survey consisted of walking along lines the length of the site in a north -south direction. Lines were spaced approx- imately 60 feet apart. We observed radiation measurements that were taken with a Ludlum Instruments, Inc. Model No. 19 Micro -R -Meter carried at arms length (approximately 2 feet above the ground surface). Radiation readings were observed by continuously glancing back and forth from the Micro -R -Meter to the line of travel. We observed radiation measurements averaging approxi- mately 1 microroentgen per hour. Some areas had readings as low as 0 microroentgens per hour and as high as 2 microroentgens per hour. In our opin- PHIL VAUGHAN CONSTRUCTION MANAGEMENT, INC. WPX ENERGY TRAIL RIDGE EMPLOYEE HOUSING FACILITY PROJECT NO. GS05884-125 REVISED S:1GS05554.000111513. Latlara1GS05854115 11511 Revlaad.doe 2 ion, these readings on the site are very low, indicative of normal background ra- diation for this area of Garfield County. Subsurface Conditions To investigate subsurface conditions, we directed the drilling of five ex- ploratory borings (TH-1 and TH-5) at the approximate locations shown on Figure 2. The borings were drilled with 4 -inch diameter, solid -stem, continuous flight auger and a track -mounted drill rig. Drilling operations were directed by our la- boratory/field manager who logged the soils encountered in the borings and ob- tained samples. Graphic logs of the soils encountered in our exploratory borings are shown on Figure 3. Subsurface conditions encountered in our exploratory borings TH-1 through TH-5 consisted of hard to very hard, moist marlstone and sandstone bedrock with interbedded claystone layers. Our boring TH-5 was located on the top of a stockpile placed on the existing bench. Boring TH-5 penetrated 12 feet of stockpiled sandstone from previous excavation. Atterberg limits on the sand- stone were liquid limits of non -liquid (NL), 30 or 32 percent and plastic indices were non -plastic to 11 percent. Samples tested contained between 4 and 27 percent silt and clay size particles (passing the No. 200 sieve). A sample select- ed for one dimensional swell/consolidation testing was wetted under an applied load of 1,000 psf and the resulting volume change measured. The sample ex- hibited 0.2 percent consolidation. Laboratory test results are shown on Figure 4 and 5 and summarized on Table I. Free groundwater was not found in our bor- ings at the time of drilling. Earthwork A plan that we reviewed shows a 540 to 600 feet long by 120 feet wide pad. This pad will require cuts of up to 20 feet deep at the east one-third of the pad footprint. Fill (if required) to construct the pad and below buildings can be broken down sandstone free of organics and rock fragments larger than 3 inches in diameter. Fill should be moisture treated within 2 percent of optimum moisture content. Fill to construct the pad outside of an area 3 feet beyond the building footprints should be compacted to 95 percent of standard Proctor (ASTM 17 698) maximum dry density. Fill placed below and within 3 feet of building footprints should be compacted to at least 100 percent of ASTM D 698. Placement of fill should be checked by a representative of our firm. Excavations at the site will be into sandstone bedrock. The sandstone bedrock will likely classify as a Type A soil based on OSHA standards governing excavations. Temporary slopes deeper than 4 feet should be no steeper than 3/4 to 1 (horizontal to vertical) in Type A soils. The contractor's personnel should PHIL VAUGHAN CONSTRUCTION MANAGEMENT, INC. WPX ENERGY TRAIL RIDGE EMPLOYEE HOUSING FACILITY PROJECT NO. GS05884-125 REVISED S:1GS06884.0001116q. Lettan1GS06884116 L1 Revfaed.doe 3 check that the soils in excavations are laid back in accordance with OSHA re- quirements, where applicable. Foundations We understand the temporary housing buildings are framed with structural steel runners. The runners are commonly referred to as skids. The skids will bear on a layer of compacted gravel placed on the sandstone bedrock. We be- lieve a compacted gravel layer on sandstone bedrock will provide good support. The housing building complex will resist lateral loads with tie downs. Plans show helical pier tie downs. The subgrade soils will be hard to very hard sandstone bedrock. The specialty contractor should opine on the ability to helix the hard sandstone. Micropiles could also be used as tie down elements, if desired. Micropiles can be installed into the sandstone. We understand the storage building will likely be founded on micropiles. We are providing recommendations for micropiles and helical piers. Our representative should be called to test the placement of fill and ob- serve conditions exposed in the completed foundation excavations to confirm that the exposed soils are as anticipated and suitable for support of the founda- tion as designed. Design and construction criteria for micropiles and helical piers are presented below. Micropiles 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 with re- quirements as specified in USDOT publication number FHWA-NHI- 05-039. We recommend load tests be performed prior to the start of production micropile installation to check bond stress and instal- lation methods. We can assist in the design of micropiles, if re- quested. 3. We believe micropiles should be designed using grout/ground inter- face bond strength of 20 psi in the sandstone bedrock. Soil above the bedrock should not be included in capacity calculations. The in- stallation 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. Micropiles should have a total length of at least 20 feet. PHIL VAUGHAN CONSTRUCTION MANAGEMENT, INC. WPX ENERGY TRAIL RIDGE EMPLOYEE HOUSING FACILITY PROJECT NO. GS06884125 REVISED 5:1GS05584.000111613. Latten1GS06854115 L7 Ravlaed.doc 5. We recommend that the upper 10 feet of casing be permanent. This upper section of permanent casing will likely be required for lateral load considerations. 6. Micropiles should be reinforced their full length. The area of rein- forcing steel should be sufficient to withstand uplift. 7. Micropiles should have a minimum diameter of 5 inches. Helical Piers 1. In general, manufactured helical piers are available with allowable mechanical capacities between 30 and 50 kips. Helical pier bear- ing capacity shall be verified in the field using manufacturer rec- ommended capacity/torque ratios. A minimum factor of safety of 2.0 is required. 2. Contractor shall use the number and size of helical blades required to achieve the required depth and capacity. However, the ratio of design bearing capacity specified by the structural engineer and the total area of helical blades used by the contractor shall not exceed 30,000 pounds per square foot. 3. Helical piers should have a minimum shaft cross sectional dimen- sions of 1.75 inches per side, and solid for square shafts or 3 inch diameter, schedule 80 for round shafts. 4. Helical piers should have a minimum length of 15 feet. Helical piers should be placed as close to vertical as possible. 5. At a minimum, helical piers bearing on bedrock should be spaced apart a distance equal to three times the average helix diameter to avoid group efficiency effects. 6. Installation of helical piers should be observed by a representative of our firm to confirm the depth and installation torque of the helical piers are adequate. Surface Drainage Surface drainage is critical to the performance of foundations. The ground surface around the structures should be sloped to direct runoff away from the structures. Backfill adjacent to foundation walls should be moisture condi- tioned and compacted as recommended in the Earthwork section. PHIL VAUGHAN CONSTRUCTION MANAGEMENT, INC. WPX ENERGY TRAIL RIDGE EMPLOYEE HOUSING FACILITY PROJECT NO. GS05884-125 REVISED S:1GS✓76834.0001116M Leila rs5G505884115 L1 Ravl.ud.doc Access Road and Parking Lot The proposed parking areas subgrade is sandstone bedrock. Access road and parking lots are to be gravel. We anticipate that the majority of vehicle traffic wilt be light trucks. Heavy trucks will be limited to those required to provide sup- plies. If the anticipated traffic loads are considerably different than those as- sumed, we should be informed so that we can review our recommendations. Aggregate Base Course (ABC) 1. A Class 5 or 6 Colorado Department of Transportation (CDOT) specified aggregate base course should be used. A recycled con- crete alternative which meets the Class 5 or 6 designation is also acceptable. 2. Aggregate base course or recycled concrete should be laid in thin lifts not to exceed 8 inches, moisture treated to within 2 percent of optimum moisture content, and compacted to at least 95 percent of maximum modified Proctor dry density (ASTM D 1557, AASHTO T 180). 3. Placement and compaction of aggregate base course or recycled concrete should be observed and tested by a representative of our firm. Placement should not commence until the underlying sub - grade is properly prepared and tested. Drives and parking lots at the facility can be constructed with a 6 inch lay- er of Class 6 aggregate base course placed on the prepared natural sandstone bedrock surface. A primary cause of early driving surface deterioration is water infiltration into the subgrade. The addition of moisture usually results in softening of sub - grade and the eventual failure of the drive surface. We recommend drainage be designed for rapid removal of surface runoff from drives and parking areas. Fi- nal grading should be carefully controlled so that design cross -slope is main- tained and low spots in the subgrade which could trap water are eliminated. Final Desicn Consultation and Construction Observation This report has been prepared for the exclusive use of Phil Vaughan Con- struction Management, Inc. and the design team for the purpose of providing ge- otechnical 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 subsur- PHIL VAUGHAN CONSTRUCTION MANAGEMENT, INC. WPX ENERGY TRAIL RIDGE EMPLOYEE HOUSING FACILITY PROJECT NO. GS06884125 REVISED S:1G505I54.000111613. Letten1GS05584115 L1 Remit, ed.doc 6 face 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 up- date this report. It is recommended that CTL 1 Thompson, Inc. be retained to provide gen- eral review of the final construction plans prior to construction, Our firm should also be retained to provide geotechnical engineering and material testing during construction. The purpose is to observe the construction with respect to the ge- otechnical design concepts, specifications or recommendations, and to facilitate design changes in areas where the subsurface conditions differ from those antic- ipated prior to start of construction. Limitations Our exploratory borings were located to obtain a reasonably accurate pic- ture of subsurface conditions. Variations in the subsurface conditions not indi- cated by our borings will occur. A representative of our firm should be called to observe the completed foundation excavations to check fill moisture content and density. 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 im- plied, is made. 1f 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. CTL 1 THDMPS.QNi ANG, �• � '�+ice v hn �1� •*a�j Q L .fid ngP__0 r Bra ManagerN� �M:cd cc: Via email to phil pvcmi.com PHIL VAUGHAN CONSTRUCTION MANAGEMENT, INC. WPX ENERGY TRAIL RIDGE EMPLOYEE HOUSING FACILITY PROJECT NO. GS05864-126 REVISED sAGS05884 ODOV1151.3. 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Project No. GS05884-125 n r 0 -J R Locations of Exploratory Borings Fig. 2 s, 9 S:15505/114 000111515 ORAFTING1GSOM&I 115 R1 FIGURE 3 BORING LOG OPJ DEPTH FEET LTi 111 ■ v. $ e en 1111.1.11.111111111MillW \ ! § § ■ E 0 I. i 1 1 1 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 111 1 \„ I._ ...7.1 0 °"--ET -rs . § § MI o . . . § §2F§ § /e; zsPe Z 0-4 / j{ \k�0 - k§ §!§ , m 0n, 9§ f% k) ) k \r"2 m-< )§ « § ®AIS 23P �P !§ ® 22 ) k k q 53k —) # § om \ �§ -,§ n ix 13 Tc - ! ;] o� _0 �o ; k ) §. § 7 q r. 2* | ) §- . /, 2§ ] S 2t / § B§ r-@ / - - -1 m z �m '3." k> En - 31 --(Zr — -1=1- 3NOlSONVS 31WM30lS -11I § 1 f / HYGROMETER ANALYSIS SIEVE ANALYSIS 25 HR. 7 HR. TIME READINGS U.B. STANDARD SERIES CLEAR SQUARE OPENINGS 45 MIN. 15 MIN. 60 MIN. 19 MIN. 4 MIN. 1 MIN. '200 '100 50 '40 '30 16 '10 1 '4 3/8' 3/4' 1'i 3' 5'6' R' 100 1- T ` 90 80 L� 70 <60 r Too 30 20 10 0 .001 0 002 .005 .009 .019 .037 .074 .149 .2970.42.590 1 19 2.0 2.38 4 76 9 52 DIAMETER OF PARTICLE IN MILLIMETERS 19.1 36.1 10 20 30 8 2 40 ru 50 U d' 60 a- 70 70 80 90 100 76.2 1275200 JCLAY (PLASTIC) TO SILT (NON -PLASTIC) SANDS GRAVEL FINE MEDIUM I COARS FINE I COARSE J COBBLES Sample of SANDSTONE From TH -1 AT 0-10 FEET GRAVEL 16 % SAND 57 % SILT & CLAY 27 % LIQUID LIMIT 82 % PLASTICITY INDEX 11 % HYDROMETER ANALYSIS SIEVE ANALYSIS 25 HR. 7 HR. TIME READINGS U.S. STANDARD SERIES CLEAR SQUARE OPENINGS 45 MIN, 15 MIN. 60 MIN. 19 MIN. 4 MIN. 1 MIN. '200 '100 '50 '40 '30 16 10 '8 '4 3/8' 3/4' 1Ye 8' 76' ' 100 90 80 30 20 10 0 .005 .009 .019 .037 .074 .149 2 0.42 1.19 20 2.38 4.76 9.52 19.1 36.1 DIAMETER OF PARTICLE IN MILLIMETERS 10 20 30 x 40 F 50 w U 60 0. 70 80 90 100 76 2 12152 CLAY (PLASTIC) TO SILT (NON -PLASTIC) SANDS GRAVEL FINE MEDIUM I COARS FINE I COARSE COBBLES Sample of SANDSTONE From TH - 4 AT 0-10 FEET PHIL VAUGHAN CONSTRUCTION MANAGEMENT, INC. TRAIL RIDGE EMPLOYEE HOUSING FACILITY PROJECT NO. GS05884-125 S:1G505884.000111516. CaIca1GS05884 Graddion.xla GRAVEL 29 % SAND 51 % SILT & CLAY 20 % LIQUID LIMIT 30 % PLASTICITY INDEX 9 % Gradation Test Results FIG. 4 COMPRESSION % EXPANSION 7 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 -7 -8 0.1 APPLIED PRESSURE - KSF Sample of SANDSTONE From TH-5 AT 24 FEET 1.0 PHIL VAUGHAN CONSTRUCTION MANAGEMENT, INC. TRAIL RIDGE EMPLOYEE HOUSING FACILITY PROJECT NO. GS05884-125 S:IGS05884.000111516. CaIea1GS05884 SweIIa15 10 100 DRY UNIT WEIGHT= 101 PCF MOISTURE CONTENT= 12.6 % Swell Consolidation Test Results FIG. 5 li ADDITIONAL CONSTANT L COMPRESSION PRESSURE f DUE UNDER TO . .. 0.1 APPLIED PRESSURE - KSF Sample of SANDSTONE From TH-5 AT 24 FEET 1.0 PHIL VAUGHAN CONSTRUCTION MANAGEMENT, INC. TRAIL RIDGE EMPLOYEE HOUSING FACILITY PROJECT NO. GS05884-125 S:IGS05884.000111516. CaIea1GS05884 SweIIa15 10 100 DRY UNIT WEIGHT= 101 PCF MOISTURE CONTENT= 12.6 % Swell Consolidation Test Results FIG. 5 0 La pi 0 w g� J 0 � g6 pw rp Q� Y! DESCRIPTION ;SANDSTONE [SANDSTONE [SANDSTONE [SANDSTONE ISANDSTONE 'SANDSTONE 1SANOSTONE :SANDSTONE ,-- w w z p 1- 2 2 z a 'J' o iw z d 1— Z 0,sui Z 3,,e CL co .- ." PERCENT GRAVEL (%) 1 ilg IA SOLUBLE SULFATES (%) 000'0 000'0 UNCONFINED COMPRESSION (PSF) 8,200 SWELL TEST RESULTS' 1 APPLIED PRESSURE (PSF) .8 SWELL cN 9 ERG LIMITS 1 PLASTICITY INDEX (%) L LL NP �,a z m a 3.7 C•Q O F M de J. rii PI Z C9i :Z L ›- I- OZUa O o 0 MOISTURE CONTENT (%) u0 '33.0?iN IN Nim m lW N •m =.-.0 '1'b. W n_, 3° Nrv. .q ''r 0 4 QN EXPLORATORY BORING 11 F 1 TH-3 1 TF1.4 H H F- a a w CL 4 a a O 0 Lu Lu K O w a 0 wa eCLw Q LL 2 a0 8 c of G W yjy J � Lj3W yz